WO2013057978A1 - Photoelectric conversion apparatus, method for manufacturing same, and photoelectric conversion module - Google Patents

Photoelectric conversion apparatus, method for manufacturing same, and photoelectric conversion module Download PDF

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Publication number
WO2013057978A1
WO2013057978A1 PCT/JP2012/063233 JP2012063233W WO2013057978A1 WO 2013057978 A1 WO2013057978 A1 WO 2013057978A1 JP 2012063233 W JP2012063233 W JP 2012063233W WO 2013057978 A1 WO2013057978 A1 WO 2013057978A1
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Prior art keywords
transparent electrode
electrode
photoelectric conversion
lower transparent
collector electrode
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PCT/JP2012/063233
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French (fr)
Japanese (ja)
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時岡　秀忠
努 松浦
弘也 山林
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三菱電機株式会社
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L31/02—Details
    • H01L31/0224—Electrodes
    • H01L31/022408—Electrodes for devices characterised by at least one potential jump barrier or surface barrier
    • H01L31/022425—Electrodes for devices characterised by at least one potential jump barrier or surface barrier for solar cells
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L31/02—Details
    • H01L31/0224—Electrodes
    • H01L31/022466—Electrodes made of transparent conductive layers, e.g. TCO, ITO layers
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00—Energy generation through renewable energy sources
    • Y02E10/50—Photovoltaic [PV] energy

Definitions

  • the present invention relates to a photoelectric conversion device, a manufacturing method thereof, and a photoelectric conversion module.
  • a thin film semiconductor layer having different conductivity and a transparent electrode are formed in this order on one side of a crystalline semiconductor substrate, and at least an amorphous semiconductor thin film having different conductivity on the other side.
  • a transparent electrode is formed in this order, and there is a solar cell that includes a photovoltaic cell that generates photovoltaic power in the crystalline semiconductor substrate and the semiconductor layer by light incidence from one or both surfaces of the crystalline semiconductor substrate.
  • a collector electrode patterned in a thin line shape is formed on both transparent conductives on one side and the other side.
  • the parasitic resistance of the solar battery cell must be reduced in order to efficiently collect charges generated by light irradiation.
  • the resistivity of indium oxide (ITO) added with tin constituting the transparent electrode and the silver (Ag) constituting the collector electrode Reduce resistivity. In addition to this, it is necessary to reduce the contact resistance between the transparent electrode and the collector electrode.
  • ITO which is the transparent electrode
  • ITO must have high light transmittance in order to guide irradiated light to the semiconductor layer and the crystalline semiconductor substrate.
  • the oxygen concentration of the transparent electrode when the oxygen concentration increases, the electrical resistivity increases, so that the collection efficiency of charges generated by light irradiation decreases, and the photoelectric conversion efficiency decreases.
  • the oxygen concentration of the transparent electrode in order to reduce the contact resistance between the transparent electrode and the collecting electrode, the oxygen concentration of the transparent electrode must be reduced to lower the electrical resistivity.
  • the electrical resistivity is reduced by reducing the oxygen concentration only in the ITO in contact with the collector electrode, thereby reducing the contact resistance. And in other locations in ITO, the light transmittance is ensured by increasing the oxygen concentration.
  • the contact resistance is reduced by forming the collector electrode by a plating method and reducing only the ITO at the contact portion between the transparent electrode and the collector electrode.
  • JP 2004-214442 A Japanese Patent No. 3619681
  • the present invention has been made in view of the above, and an object thereof is to obtain a photoelectric conversion device excellent in photoelectric conversion efficiency and a method for manufacturing the same.
  • a photoelectric conversion device is a photoelectric conversion device in which a semiconductor layer is formed on at least one surface of a crystalline semiconductor substrate, and includes a transparent electrode film.
  • a lower transparent electrode formed on a semiconductor layer, a collector electrode formed on the lower transparent electrode in contact with the lower transparent electrode, and a transparent electrode film formed to cover the collector electrode; And an upper transparent electrode formed in electrical contact with a part of the collector electrode and a part of the lower transparent electrode.
  • the present invention it is possible to reduce the contact resistance between the collector electrode and the transparent electrode by ensuring a wide contact area between the collector electrode and the transparent electrode, so that a solar cell with reduced parasitic resistance and excellent photoelectric conversion efficiency can be obtained. The effect is obtained.
  • FIG. 1 is a perspective view schematically showing a schematic configuration of the solar battery cell according to the first embodiment of the present invention.
  • FIG. 2 is a conceptual diagram illustrating the flow of charges in the solar battery cell according to the first embodiment of the present invention.
  • FIG. 3 is a diagram showing photoelectric conversion characteristics of the solar battery cell according to the first embodiment (Example) and a conventional solar battery cell (conventional example).
  • FIG. 4-1 is a cross-sectional view illustrating an example of the procedure of the method for manufacturing the solar battery cell according to the first embodiment of the present invention.
  • FIGS. 4-2 is sectional drawing which shows an example of the procedure of the manufacturing method of the photovoltaic cell concerning Embodiment 1 of this invention.
  • FIGS. FIGS. 4-3 is sectional drawing which shows an example of the procedure of the manufacturing method of the photovoltaic cell concerning Embodiment 1 of this invention.
  • FIGS. FIGS. 4-4 is sectional drawing which shows an example of the procedure of the manufacturing method of the photovoltaic cell concerning Embodiment 1 of this invention.
  • FIGS. FIGS. 4-5 is sectional drawing which shows an example of the procedure of the manufacturing method of the photovoltaic cell concerning Embodiment 1 of this invention.
  • FIGS. FIGS. 4-6 is sectional drawing which shows an example of the procedure of the manufacturing method of the photovoltaic cell concerning Embodiment 1 of this invention.
  • FIGS. FIG. 5 is a perspective view schematically showing a schematic configuration of the solar battery cell according to the second embodiment of the present invention.
  • FIGS. 6-1 is a cross-sectional view illustrating an example of the procedure of the method for manufacturing the solar battery cell according to the second embodiment of the present invention.
  • FIG. 6-2 is a cross-sectional view illustrating an example of the procedure of the method for manufacturing the solar battery cell according to the second embodiment of the present invention.
  • 6-3 is sectional drawing which shows an example of the procedure of the manufacturing method of the photovoltaic cell concerning Embodiment 2 of this invention.
  • 6-4 is sectional drawing which shows an example of the procedure of the manufacturing method of the photovoltaic cell concerning Embodiment 2 of this invention.
  • FIGS. 6-5 is sectional drawing which shows an example of the procedure of the manufacturing method of the photovoltaic cell concerning Embodiment 2 of this invention.
  • FIG. 6-6 is sectional drawing which shows an example of the procedure of the manufacturing method of the photovoltaic cell concerning Embodiment 2 of this invention.
  • FIGS. FIG. 7: is sectional drawing which shows typically schematic structure of the solar cell module concerning Embodiment 3 of this invention.
  • FIG. 8 is a cross-sectional view of the solar cell module taken along line A-A ′ in FIG. 7.
  • FIG. 1 is a perspective view schematically showing a schematic configuration of a solar battery cell 1 which is a photoelectric conversion device according to Embodiment 1 of the present invention.
  • This solar cell 1 is an i-type amorphous material having a thickness of approximately 5 nm on the surface of one surface of an n-type crystalline silicon substrate 2 constituting a photoelectric conversion layer in which both surfaces constituting the photoelectric conversion layer are processed to be uneven.
  • a silicon layer 3a is formed, and an i-type amorphous silicon layer 3b having a thickness of about 5 nm is formed on the surface on the other side. Thereby, a heterojunction between the amorphous silicon layer and the crystalline silicon substrate is formed.
  • the n-type crystalline silicon substrate 2 is a silicon substrate having a specific resistance of 1 to 10 ⁇ ⁇ cm, a crystal orientation of ⁇ 100>, and a thickness of 50 ⁇ m to 300 ⁇ m.
  • FIG. 1 for the sake of simplicity, the illustration of the concavo-convex structure on the surface of the n-type crystalline silicon substrate 2 is omitted.
  • a p-type amorphous silicon layer 4 having a thickness of about 5 nm is formed on the i-type amorphous silicon layer 3a, and an n-type non-layer having a thickness of about 5 nm is formed on the i-type amorphous silicon layer 3b.
  • a crystalline silicon layer 5 is formed. Thereby, a pn junction is formed by the n-type crystalline silicon substrate 2 and the p-type amorphous silicon layer 4 via the i-type amorphous silicon layer 3a.
  • Intrinsic semiconductor layers i-type amorphous silicon layer 3a and i-type amorphous silicon layer 3b
  • Intrinsic semiconductor layers can suppress diffusion of impurities between heterojunctions and can form a junction having a steep impurity profile.
  • a high open circuit voltage can be obtained by forming the bonding interface.
  • a lower transparent electrode 6a having a thickness of approximately 70 nm is formed on the p-type amorphous silicon layer 4, and a lower transparent electrode 6b having a thickness of approximately 70 nm is formed on the n-type amorphous silicon layer 5.
  • a collector electrode 7 made of silver (Ag) with a thickness of about 60 ⁇ m is formed on the lower transparent electrode 6a, and a collector electrode 8 made of silver (Ag) with a thickness of about 60 ⁇ m is formed on the lower transparent electrode 6b.
  • the lower transparent electrode 6a and the lower transparent electrode 6b may be collectively referred to as the lower transparent electrode 6.
  • the collector electrode 7 has a width of about 20 ⁇ m, a thickness of about 60 ⁇ m, and a plurality of grid electrodes 7 a arranged substantially in parallel with each other at a constant pitch, and a width of about 1 mm, which intersects the grid electrodes 7 a electrically. And a bus electrode 7b connected to the.
  • the collector electrode 8 has a width of about 20 ⁇ m, a thickness of about 60 ⁇ m, a plurality of grid electrodes 8 a arranged at a certain pitch and substantially parallel to each other, and a width of about 1 mm, which intersects the grid electrodes 8 a and is electrically And the bus electrode 8b connected to the.
  • An upper transparent electrode 9a is formed so as to cover a part of the lower transparent electrode 6a and the collector electrode 7, and an upper transparent electrode 9b is formed so as to cover a part of the lower transparent electrode 6b and the collector electrode 8. Yes.
  • the region adjacent to the collector electrode 7 on the surface is covered with the upper transparent electrode 9a
  • the region adjacent to the collector electrode 8 on the surface is covered with the upper transparent electrode 9b.
  • the upper transparent electrode 9a and the upper transparent electrode 9b may be collectively referred to as the upper transparent electrode 9.
  • the lower transparent electrode 6a and the upper transparent electrode 9a may be collectively referred to as one surface side transparent electrode, and the lower transparent electrode 6b and the upper transparent electrode 9b may be collectively referred to as other surface side transparent electrodes.
  • the upper transparent electrodes 9a and 9b may not be formed on the bus electrodes 7b and 8b, respectively.
  • the collector electrode 7 is in contact with the lower transparent electrode 6a, and further includes an upper transparent electrode 9a electrically connected to both the lower transparent electrode 6a and the collector electrode 7.
  • the contact area with the collector electrode 7 can be secured wider than that of a conventional solar battery cell.
  • the collector electrode 8 is in contact with the lower transparent electrode 6b, and further includes the upper transparent electrode 9b electrically connected to both the lower transparent electrode 6b and the collector electrode 8, whereby the solar cell 1 has the other surface side.
  • the contact area between the transparent electrode and the collector electrode 8 can be secured wider than that of a conventional solar battery cell.
  • the contact area between the transparent electrode and the collector electrode is increased, so that the contact resistance between the transparent electrode and the collector electrode is reduced, the parasitic resistance is lowered, and the power generation efficiency and the fill factor are improved. To do.
  • FIG. 2 is a conceptual diagram illustrating the flow of charges in the solar battery cell 1 according to the first embodiment of the present invention.
  • FIG. 2 shows a cross section along a direction substantially orthogonal to the extending direction of the collector electrode 7 in the surface direction of the n-type crystalline silicon substrate 2, and the arrows in the figure indicate the flow direction of charges.
  • the solar cell 1 is irradiated with light from one side or both sides of the solar cell 1
  • electric charge is generated in the n-type crystalline silicon substrate 2 that is a photoelectric conversion layer. That is, when the solar battery cell 1 is irradiated with light, holes and electrons are generated as charges.
  • a part of the generated charge reaches the lower transparent electrode 6 a through the i-type amorphous silicon layer 3 a and the p-type amorphous silicon layer 4.
  • the electric charge that has reached the lower transparent electrode 6a moves in the lower transparent electrode 6a to the vicinity of the region where the collector electrode (grid electrode) 7a and the lower transparent electrode 6a are in contact.
  • some charges pass through the lower transparent electrode 6a from the lower surface of the collector electrode (grid electrode) 7a, and other charges pass through the upper transparent electrode 9a.
  • the electrode moves from the side surface and the upper surface of the electrode 7a to the collector electrode (grid electrode) 7a.
  • the electric charge is larger than that of the conventional solar battery cell, that is, the collector electrode (grid electrode) 7a and the one-surface side transparent electrode (lower transparent electrode 6a, upper transparent electrode 9a) are in contact with each other.
  • the lower transparent electrode 6a reaches the collector electrode (grid electrode) 7a through the contact surface. It should be noted that the same charge movement as described above also occurs at the portion where the bus electrode 7b and the one-side transparent electrode (lower transparent electrode 6a, upper transparent electrode 9a) are in contact.
  • the lower transparent electrode 6 b On the other surface side of the solar battery cell 1, a part of the generated charges reaches the lower transparent electrode 6 b through the i-type amorphous silicon layer 3 b and the n-type amorphous silicon layer 5.
  • the electric charge that has reached the lower transparent electrode 6b moves in the lower transparent electrode 6b to the vicinity of the region where the collector electrode (grid electrode) 8a and the lower transparent electrode 6b are in contact with each other.
  • some charges pass through the lower transparent electrode 6b from the lower surface of the collector electrode (grid electrode) 8a, and other charges pass through the upper transparent electrode 9b.
  • the electrode moves from the side surface and the upper surface of the electrode 8a to the collector electrode (grid electrode) 8a.
  • the electric charge is wider than that of the conventional solar battery cell, that is, the collector electrode (grid electrode) 8a and the other side transparent electrode (lower transparent electrode 6b, upper transparent electrode 9b). It reaches the collector electrode (grid electrode) 8a from the lower transparent electrode 6a through the contacting surface. It should be noted that the same charge movement as described above also occurs at the portion where the bus electrode 8b and the other transparent electrode (lower transparent electrode 6b, upper transparent electrode 9ba) are in contact.
  • the size of the grid electrode 7a and the bus electrode 7b is about 20 ⁇ m in width and about 60 ⁇ m in thickness. For this reason, the contact area (conduction area) between the collector electrode and the transparent electrode in the solar battery cell 1 has a collector electrode of the same size as this, and the contact surface between the collector electrode and the transparent electrode is only the lower surface of the collector electrode. This is approximately 8 times the conventional solar battery cell.
  • FIG. 3 is a diagram illustrating photoelectric conversion characteristics of the solar battery cell 1 according to the first embodiment (Example) and the conventional solar battery cell (conventional example).
  • FIG. 3 shows the relationship between voltage (V) and short circuit current density (relative value).
  • the short-circuit current density indicates a relative value of the example with respect to the conventional example. It can be seen from FIG. 3 that the fill factor of the solar battery cell 1 is improved.
  • the improvement of the fill factor of the solar cell 1 is that by providing the upper transparent electrode 9a, the conductive area from the lower transparent electrode 6a to the collector electrode 7 is increased, and the contact resistance between the one-side transparent electrode and the collector electrode 7 is reduced.
  • FIGS. 4-1 to 4-6 are cross-sectional views illustrating an example of the procedure of the method for manufacturing the solar battery cell 1 according to the first embodiment.
  • an uneven structure called a texture is formed on the surface of the n-type crystalline silicon substrate 2.
  • the texture reduces reflection of light incident on the solar battery cell 1 and promotes light scattering in the n-type crystalline silicon substrate 2.
  • wet etching of the surface of the n-type crystalline silicon substrate 2 using an acidic or alkaline etching solution can be used.
  • a step of removing the damaged layer on the surface of the n-type crystalline silicon substrate 2 may be performed before the formation of the concavo-convex structure.
  • the gettering process for example, a phosphorus diffusion process or the like is used.
  • the formation of the concavo-convex structure may be performed only on the surface of the n-type crystalline silicon substrate 2 on the light incident side of the solar cell 1.
  • an i-type amorphous silicon layer 3a and a p-type amorphous silicon layer 4 are formed on one surface side of the n-type crystalline silicon substrate 2 in this order by chemical vapor deposition (CVD). ) Method.
  • the i-type amorphous silicon layer 3a and the p-type amorphous silicon layer 4 have a thickness of about 5 nm.
  • the i-type amorphous silicon layer 3a and the p-type amorphous silicon layer 4 have a thickness of about 5 nm.
  • the layer thickness is in the range of 5 nm to 10 nm. It doesn't matter.
  • the CVD method for example, a plasma CVD method or a thermal CVD method is preferably used.
  • the band gap of the p-type amorphous silicon layer 4 is 1.7 eV or more and the activation energy is 0.4 eV or less. It is necessary to be.
  • i-type amorphous silicon layer 3a an i-type amorphous silicon carbide layer, an i-type amorphous silicon oxide layer, or a multilayer film in which these layers are stacked may be used.
  • a p-type amorphous silicon carbide layer instead of the p-type amorphous silicon layer 4, a p-type amorphous silicon carbide layer, a p-type amorphous silicon oxide layer, a p-type microcrystalline silicon layer, or a multilayer film in which these layers are laminated may be used. .
  • the i-type amorphous silicon layer 3b and the n-type amorphous silicon layer 5 are formed in this order on the other surface side of the n-type crystalline silicon substrate 2 using the CVD method.
  • the i-type amorphous silicon layer 3b and the n-type amorphous silicon layer 5 each have a thickness of about 5 nm.
  • the i-type amorphous silicon layer 3b and the n-type amorphous silicon layer 5 have a thickness of about 5 nm.
  • the CVD method for example, a plasma CVD method or a thermal CVD method is preferably used.
  • the band gap of the n-type amorphous silicon layer 5 is 1.7 eV or more and the activation energy is 0.3 eV or less. It is necessary to be.
  • i-type amorphous silicon layer 3b an i-type amorphous silicon carbide layer, an i-type amorphous silicon oxide layer, or a multilayer film in which these layers are stacked may be used.
  • an n-type amorphous silicon carbide layer, an n-type amorphous silicon oxide layer, an n-type microcrystalline silicon layer, or a multilayer film in which these layers are stacked may be used.
  • thermal annealing treatment may be performed in an inert gas or hydrogen gas diluted with an inert gas.
  • the annealing temperature is preferably 200 ° C. or lower.
  • the formation order of i-type amorphous silicon layer 3a and p-type amorphous silicon layer 4, i-type amorphous silicon layer 3b and n-type amorphous silicon layer 5 may be reversed.
  • the lower transparent electrode 6a is formed on the p-type amorphous silicon layer 4 and the lower transparent electrode 6b is formed on the n-type amorphous silicon layer 5 by sputtering or vapor deposition.
  • the transparent electrode material of the lower transparent electrode 6a and the lower transparent electrode 6b ITO or indium oxide (In 2 O 3 : Indium Oxide) is used.
  • the thickness of the lower transparent electrode 6a and the lower transparent electrode 6b is preferably about 70 nm from the viewpoint of reducing the reflectance.
  • it is desirable that the electrical resistivity of the transparent electrode is low, but if the carrier density responsible for conductivity is high, the light absorption rate at the transparent electrode increases.
  • the material used as a transparent electrode must be able to realize high carrier mobility.
  • the carrier mobility is preferably 100 cm 2 / Vs or more, for example.
  • a collector electrode 7 made of Ag is formed on the lower transparent electrode 6a, and a collector electrode 8 made of Ag is formed on the lower transparent electrode 6b by screen printing.
  • FIG. 4-5 only the grid electrode 7a and the grid electrode 8a are shown.
  • the width of the grid electrode 7a constituting the collector electrode 7 and the grid electrode 8a constituting the collector electrode 8 is preferably as narrow as possible in order to prevent light incident on the solar cell 1 from being blocked. However, when the widths of the grid electrode 7a and the grid electrode 8a are narrow, the cross-sectional area becomes small and the electrical resistance increases.
  • the grid electrode 7a and the grid electrode 8a have a narrow width and a large layer thickness.
  • the width of the grid electrode 7a and the grid electrode 8a is approximately 20 ⁇ m, and the layer thickness is approximately 60 ⁇ m.
  • the collecting electrode 7 and the collecting electrode 8 may be formed by plating or the like in addition to screen printing. Further, copper (Cu) may be used as a material for the collector electrode 7 and the collector electrode 8. After the collector electrode 7 and the collector electrode 8 are printed, baking is performed at 200 ° C. or lower.
  • the upper transparent electrode 9a is formed by screen printing in a shape along the shape of the collector electrode 7 so as to cover a part of the lower transparent electrode 6a and the collector electrode 7.
  • the upper transparent electrode 9b is formed by screen printing in a shape along the shape of the collector electrode 8 so as to cover a part of the lower transparent electrode 6b and the collector electrode 8.
  • ITO is used as a transparent electrode material for the upper transparent electrode 9a and the upper transparent electrode 9b.
  • zinc oxide (ZnO: Zinc Oxide) to which indium oxide (In 2 O 3 : Indium Oxide), aluminum (Al), gallium (Ga) or the like is added is used as a transparent electrode material of the upper transparent electrode 9a and the upper transparent electrode 9b. It may be used.
  • the collector electrode 7 and the collector electrode 8 are respectively covered with the upper transparent electrodes 9a and 9b, whereby the collector electrode 7 and the collector electrode 8 can be protected, and the reliability is improved.
  • the layer thickness of the upper transparent electrode 9a is preferably greater than that of the lower transparent electrode 6a, and the layer thickness of the upper transparent electrode 9b is preferably greater than that of the lower transparent electrode 6b. Thereby, the resistance of the upper transparent electrodes 9a and 9b is lower than that of the lower transparent electrodes 6a and 6b. Then, most of the charges generated in the n-type crystalline silicon substrate 2 which is a photoelectric conversion layer are conducted to the collector electrode 7 through the upper transparent electrode 9a and to the collector electrode 8 through the upper transparent electrode 9b. The collector electrode 7 reaches the collector electrode 7 from the contact surface between the upper transparent electrode 9a and the collector electrode 8 from the contact surface between the collector electrode 8 and the upper transparent electrode 9b. As a result, the contact area between the one-side transparent electrode and the collector electrode 7 and the contact area between the other-surface lower transparent electrode and the collector electrode 8 are increased, and the contact resistance is lowered.
  • the width of the upper transparent electrode 9a is made several ⁇ m to several tens ⁇ m wider than the width of the collector electrode 7 in order to completely cover the collector electrode 7.
  • the width of the upper transparent electrode 9b is preferably set to be several ⁇ m to several tens ⁇ m wider than the width of the collector electrode 8 in order to completely cover the collector electrode 8.
  • the width of the upper transparent electrode 9a on the grid electrode 7a is approximately 40 ⁇ m
  • the width of the upper transparent electrode 9b on the grid electrode 8a is approximately 40 ⁇ m.
  • a method for forming the upper transparent electrode 9 may be used in which after the transparent electrode is once formed on the entire surface of the substrate, the transparent electrode other than the collecting electrode region is removed using an etching paste.
  • the solar cell 1 shown in FIG. 1 is obtained.
  • the solar cell 1 includes the upper transparent electrode 9a electrically connected to both the lower transparent electrode 6a and the collector electrode 7, whereby the one-side transparent electrode and the collector electrode are provided. 7 can be secured widely. Further, by providing the upper transparent electrode 9b electrically connected to both the lower transparent electrode 6b and the collector electrode 8, a wide contact area between the other-side transparent electrode and the collector electrode 8 can be secured. As a result, the contact resistance between the one-side transparent electrode and the collector electrode 7 and the contact resistance between the other-surface lower transparent electrode and the collector electrode 8 are reduced to reduce the parasitic resistance. improves.
  • the width of the collecting electrode 7 (or 8) is narrow, the contact area between the one-side transparent electrode and the collecting electrode 7 and the contact area between the other-side transparent electrode and the collecting electrode 8 are reduced. Since it can be secured widely, the parasitic resistance is reduced, and the power generation efficiency and the fill factor are improved.
  • the upper transparent electrode 9 even when the electrical resistivity is increased by increasing the oxygen concentration of ITO or the like in order to increase the light transmittance of the lower transparent electrode 6a and the lower transparent electrode 6b, the upper transparent electrode 9 Thus, the collection efficiency of charges generated by light irradiation can be improved, and the photoelectric conversion efficiency can be improved.
  • a solar battery cell having excellent fill factor and photoelectric conversion efficiency can be obtained.
  • the upper transparent electrode 9 may be configured to be in electrical contact with only a part of the collector electrodes 7 and 8. However, in order to obtain the effect of the present invention more effectively, it is preferable to increase the contact area between the upper transparent electrode 9 and the collector electrodes 7 and 8.
  • the electrical resistance of the upper transparent electrode 9a is lower than the electrical resistance of the lower transparent electrode 6a.
  • the electrical resistance of the upper transparent electrode 9b is preferably lower than the electrical resistance of the lower transparent electrode 6b.
  • the electrical resistance of the upper transparent electrode 9 may be made lower than the electrical resistance of the lower transparent electrode 6 by making the crystallinity of the upper transparent electrode 9 higher than that of the lower transparent electrode 6.
  • FIG. FIG. 5 is a perspective view which shows typically schematic structure of the photovoltaic cell 101 which is a photoelectric conversion apparatus concerning Embodiment 2 of this invention.
  • This solar cell 101 is a photoelectric conversion layer, and an i-type amorphous silicon layer 103a having a thickness of about 5 nm is formed on the surface of one surface side of an n-type crystalline silicon substrate 102 whose surfaces on both sides are processed to be uneven.
  • An i-type amorphous silicon layer 103b having a thickness of about 5 nm is formed on the surface on the other side.
  • the n-type crystalline silicon substrate 102 is a silicon substrate having a specific resistance of 1 to 10 ⁇ ⁇ cm, a crystal orientation of ⁇ 100>, and a thickness of 50 ⁇ m to 300 ⁇ m.
  • FIG. 5 for the sake of simplicity, the illustration of the concavo-convex structure on the surface of the n-type crystalline silicon substrate 2 is omitted.
  • a p-type amorphous silicon layer 104 having a thickness of about 5 nm is formed on the i-type amorphous silicon layer 103a, and an n-type non-layer having a thickness of about 5 nm is formed on the i-type amorphous silicon layer 103b.
  • a crystalline silicon layer 105 is formed.
  • a lower transparent electrode 106a having a thickness of approximately 70 nm is formed on the p-type amorphous silicon layer 104, and a lower transparent electrode 106b having a thickness of approximately 70 nm is formed on the n-type amorphous silicon layer 105.
  • a collector electrode 107 made of silver (Ag) with a thickness of about 60 ⁇ m is formed on the lower transparent electrode 106a, and a collector electrode 108 made of silver (Ag) with a thickness of about 60 ⁇ m is formed on the lower transparent electrode 106b.
  • the lower transparent electrode 106a and the lower transparent electrode 106b may be collectively referred to as the lower transparent electrode 106.
  • the collector electrode 107 has a width of about 20 ⁇ m, a thickness of about 60 ⁇ m, and a plurality of grid electrodes 107 a arranged in parallel with each other at a constant pitch, and a width of about 1 mm, which intersects the grid electrodes 107 a electrically.
  • the bus electrode 107b is connected to the bus electrode 107b.
  • the collector electrode 108 has a width of approximately 20 ⁇ m, a thickness of approximately 60 ⁇ m, and a plurality of grid electrodes 108 a arranged substantially in parallel with each other at a constant pitch, and a width of approximately 1 mm, which intersects the grid electrodes 108 a electrically.
  • the bus electrode 108b is connected to the bus electrode 108b.
  • An upper transparent electrode 109a is formed so as to cover the lower transparent electrode 106a and the collecting electrode 107
  • an upper transparent electrode 109b is formed so as to cover the lower transparent electrode 106b and the collecting electrode 108. That is, the lower transparent electrode 106a is entirely covered with the collector electrode 107 and the upper transparent electrode 109a. The lower transparent electrode 106b is entirely covered with the collector electrode 108 and the upper transparent electrode 109b.
  • the upper transparent electrode 109a and the upper transparent electrode 109b may be collectively referred to as the upper transparent electrode 109.
  • the lower transparent electrode 106a and the upper transparent electrode 109a may be collectively referred to as one side transparent electrode, and the lower transparent electrode 106b and the upper transparent electrode 109b may be collectively referred to as other side transparent electrodes.
  • the upper transparent electrodes 109a and 109b may not be formed on the bus electrodes 107b and 108b, respectively.
  • the contact area between the one-side transparent electrode and the collector electrode 107 in the solar battery cell 101 can be reduced. It can be secured widely compared to the cell.
  • the solar cell 101 has a conventional contact area between the transparent electrode on the other side and the collector electrode 108. It is possible to secure a wider area than that of solar cells. In the solar battery cell 101, the contact area between the transparent electrode and the collector electrode is increased, so that the contact resistance between the transparent electrode and the collector electrode is reduced and the parasitic resistance is lowered, and the power generation efficiency and the fill factor are improved. To do.
  • the charge is larger than that of the conventional solar cell, that is, the collector electrode 107 and one surface.
  • the collector electrode 107 reaches the collector electrode 107 from the one-side transparent electrode through the contact surface with which the side transparent electrodes (lower transparent electrode 106a, upper transparent electrode 109a) are in contact.
  • the electric charge is wider than that of the conventional solar cell, that is, the collector electrode 108 and the other surface side transparent electrode.
  • the collector electrode 108 is reached from the other transparent electrode through the contact surface with which the lower transparent electrode 106b and the upper transparent electrode 109b are in contact.
  • the results were the same as in the case of the first embodiment described with reference to FIG.
  • the curve factor is improved as compared with the solar battery cell. That is, the improvement of the fill factor of the solar battery cell 101 is the same as in the case of the first embodiment.
  • the conduction area from the lower transparent electrode 106a to the collecting electrode 107 is increased and the one surface side is increased.
  • the contact resistance between the transparent electrode and the collector electrode 107 is reduced, and the provision of the upper transparent electrode 109b increases the conduction area from the lower transparent electrode 106b to the collector electrode 108, thereby increasing the distance between the other-side transparent electrode and the collector electrode 108. This is because the contact resistance is reduced. Therefore, it became clear that the photoelectric conversion efficiency of the solar battery cell 101 according to the second embodiment is improved as compared with the conventional solar battery cell.
  • FIGS. 6-1 to 6-6 are cross-sectional views illustrating an example of the procedure of the manufacturing method of the solar battery cell 101 according to the second embodiment.
  • an uneven structure called texture is formed on the surface of the n-type crystalline silicon substrate 102.
  • the texture reduces reflection of light incident on the solar battery cell and promotes light scattering in the n-type crystalline silicon substrate 102.
  • wet etching of the surface of the n-type crystalline silicon substrate 102 using an acidic or alkaline etching solution can be used.
  • a step of removing the damaged layer on the surface of the n-type crystalline silicon substrate 102 may be performed before the formation of the concavo-convex structure.
  • the gettering process for example, a phosphorus diffusion process or the like is used.
  • the uneven structure may be formed only on the surface of the n-type crystalline silicon substrate 2 on the light incident side of the solar battery cell 101.
  • an i-type amorphous silicon layer 103a and a p-type amorphous silicon layer 104 are formed in this order on one surface side of the n-type crystalline silicon substrate 102 using the CVD method.
  • the i-type amorphous silicon layer 103a and the p-type amorphous silicon layer 104 each have a thickness of about 5 nm.
  • the i-type amorphous silicon layer 103a and the p-type amorphous silicon layer 104 have a thickness of about 5 nm.
  • the layer thickness is, for example, in the range of 5 nm to 10 nm. It doesn't matter.
  • the CVD method for example, a plasma CVD method or a thermal CVD method is preferably used.
  • the band gap of the p-type amorphous silicon layer 104 is 1.7 eV or more, and the activation energy is 0.4 eV or less. It is necessary to be.
  • an i-type amorphous silicon carbide layer, an i-type amorphous silicon oxide layer, or a multilayer film in which these layers are stacked may be used instead of the i-type amorphous silicon layer 103a.
  • a p-type amorphous silicon carbide layer instead of the p-type amorphous silicon layer 104, a p-type amorphous silicon carbide layer, a p-type amorphous silicon oxide layer, a p-type microcrystalline silicon layer, or a multilayer film in which these layers are stacked may be used. .
  • an i-type amorphous silicon layer 103b and an n-type amorphous silicon layer 105 are formed in this order on the other surface side of the n-type crystalline silicon substrate 102 using the CVD method.
  • the thicknesses of the i-type amorphous silicon layer 103b and the n-type amorphous silicon layer 105 are approximately 5 nm, respectively.
  • the i-type amorphous silicon layer 103b and the n-type amorphous silicon layer 105 have a thickness of about 5 nm. However, depending on the layer formation conditions, for example, a layer thickness in the range of 5 nm to 20 nm. It doesn't matter.
  • the CVD method for example, a plasma CVD method or a thermal CVD method is preferably used.
  • the band gap of the n-type amorphous silicon layer 105 is 1.7 eV or more and the activation energy is 0.3 eV or less. It is necessary to be.
  • an i-type amorphous silicon carbide layer, an i-type amorphous silicon oxide layer, or a multilayer film in which these layers are stacked may be used.
  • n-type amorphous silicon layer 105 an n-type amorphous silicon carbide layer, an n-type amorphous silicon oxide layer, an n-type microcrystalline silicon layer, or a multilayer film in which these layers are stacked may be used. .
  • thermal annealing treatment may be performed in an inert gas or hydrogen gas diluted with an inert gas.
  • the annealing temperature is preferably 200 ° C. or lower.
  • the formation order of the i-type amorphous silicon layer 103a and the p-type amorphous silicon layer 104, and the i-type amorphous silicon layer 103b and the n-type amorphous silicon layer 105 may be reversed.
  • the lower transparent electrode 106a is formed on the p-type amorphous silicon layer 104 and the lower transparent electrode 106b is formed on the n-type amorphous silicon layer 105 by sputtering or vapor deposition.
  • a transparent electrode material of the lower transparent electrode 106a and the lower transparent electrode 106b ITO or indium oxide (In 2 O 3 : Indium Oxide) is used.
  • the film thickness of the lower transparent electrode 106a and the lower transparent electrode 106b is preferably about 70 nm from the viewpoint of reducing the reflectance.
  • the electrical resistivity of the transparent electrode is low, but if the carrier density responsible for conductivity is high, the light absorption rate at the transparent electrode increases. For this reason, the material used as a transparent electrode must be able to realize high carrier mobility.
  • the carrier mobility is preferably 100 cm 2 / Vs or more, for example.
  • the collector electrode 107 made of Ag is formed on the lower transparent electrode 106a, and the collector electrode 108 made of Ag is formed on the lower transparent electrode 106b by screen printing.
  • the grid electrode 107a and the grid electrode 108a are shown.
  • the widths of the grid electrode 107 a constituting the collector electrode 107 and the grid electrode 108 a constituting the collector electrode 108 are preferably as narrow as possible in order to prevent light incident on the solar battery cell 101 from being blocked. However, when the widths of the grid electrode 107a and the grid electrode 108a are narrow, the cross-sectional area becomes small and the electrical resistance increases.
  • the grid electrode 107a and the grid electrode 108a have a narrow width and a large layer thickness.
  • the width of the grid electrode 107a and the grid electrode 108a is approximately 20 ⁇ m, and the layer thickness is approximately 60 ⁇ m.
  • the collecting electrode 107 and the collecting electrode 108 may be formed by a plating method in addition to screen printing. Further, copper (Cu) may be used as a material for the collector electrode 107 and the collector electrode 108. After the collector electrode 107 and the collector electrode 108 are printed, baking is performed at 200 ° C. or lower.
  • the upper transparent electrode 109a is formed in a shape along the shape of the collector electrode 107 by sputtering or vapor deposition so as to cover the lower transparent electrode 106a and the collector electrode 7 as a whole.
  • the upper transparent electrode 109b is formed in a shape in accordance with the shape of the collector electrode 108 by sputtering or vapor deposition so as to cover the lower transparent electrode 106b and the entire collector electrode 108.
  • ITO is used as a transparent electrode material for the upper transparent electrode 109a and the upper transparent electrode 109b.
  • zinc oxide (ZnO: Zinc Oxide) to which indium oxide (In 2 O 3 : Indium Oxide), aluminum (Al), gallium (Ga) or the like is added is used as a transparent electrode material for the upper transparent electrode 109a and the upper transparent electrode 109b. It may be used.
  • the collector electrode 107 and the collector electrode 108 are covered with the upper transparent electrodes 109a and 109b, respectively, whereby the collector electrode 107 and the collector electrode 108 can be protected, and there is an advantage that reliability is improved.
  • the upper transparent electrode 109a is thicker than the lower transparent electrode 106a, and the upper transparent electrode 109b is thicker than the lower transparent electrode 106b.
  • the resistance of the upper transparent electrodes 109a and 109b is lower than that of the lower transparent electrodes 106a and 106b.
  • Most of the charges generated in the n-type crystalline silicon substrate 102 which is a photoelectric conversion layer are conducted to the collector electrode 107 through the upper transparent electrode 109a and to the collector electrode 108 through the upper transparent electrode 109b. From the contact surface of the upper transparent electrode 109a to the collector electrode 107 and from the contact surface of the collector electrode 108 and the upper transparent electrode 109b to the collector electrode 108. As a result, the contact area between the one-side transparent electrode and the collector electrode 107 and the contact area between the other-surface lower transparent electrode and the collector electrode 108 are increased, and the contact resistance is lowered.
  • the width of the upper transparent electrode 109a be several ⁇ m to several tens ⁇ m wider than the width of the collector electrode 107 in order to completely cover the collector electrode 107.
  • the width of the upper transparent electrode 109b is preferably set to be several ⁇ m to several tens ⁇ m wider than the width of the collector electrode 108 in order to completely cover the collector electrode 108.
  • the width of the upper transparent electrode 109a on the grid electrode 107a is approximately 40 ⁇ m
  • the width of the upper transparent electrode 109b on the grid electrode 108a is approximately 40 ⁇ m.
  • the electrical resistivity of the upper transparent electrode 109a is set lower than that of the lower transparent electrode 106a.
  • the electrical resistivity of the upper transparent electrode 109b is set lower than that of the lower transparent electrode 106b.
  • the carrier mobility is preferably 100 cm 2 / Vs or more. For this reason, the crystallinity of the upper transparent electrode 109 may be higher than the crystallinity of the lower transparent electrode 106.
  • the solar cell 101 shown in FIG. 5 is obtained by performing the above steps.
  • the solar cell 101 includes the upper transparent electrode 109a electrically connected to both the lower transparent electrode 106a and the collector electrode 107, and the collector electrode 107 on the lower transparent electrode 106a. Since the entire region other than the formation region of the first electrode is covered with the upper transparent electrode 109a, a wider contact area between the one-side transparent electrode and the collector electrode 107 can be secured.
  • the upper transparent electrode 109b is electrically connected to both the lower transparent electrode 106b and the collector electrode 108, and the entire area of the lower transparent electrode 106b other than the region where the collector electrode 108 is formed is covered with the upper transparent electrode 109b. As a result, a wider contact area between the transparent electrode on the other side and the collector electrode 108 can be secured. As a result, the contact resistance between the one-surface side transparent electrode and the collector electrode 107 and the contact resistance between the other-surface-side lower transparent electrode and the collector electrode 108 are reduced to reduce the parasitic resistance. improves.
  • the contact area between the one-side transparent electrode and the collecting electrode 107 and the contact area between the other-side transparent electrode and the collecting electrode 108 are reduced. Since it can be secured widely, the parasitic resistance is reduced, and the power generation efficiency and the fill factor are improved.
  • the upper transparent electrode 109 even when the electrical resistivity is increased by increasing the oxygen concentration of ITO or the like in order to increase the light transmittance of the lower transparent electrode 106a and the lower transparent electrode 106b, the upper transparent electrode 109 Thus, the collection efficiency of charges generated by light irradiation can be improved, and the photoelectric conversion efficiency can be improved.
  • the electrical resistivity is increased by increasing the oxygen concentration of ITO or the like in order to increase the light transmittance of the lower transparent electrode 106a and the lower transparent electrode 106b, it is generated by light irradiation.
  • the efficiency of collecting collected charges can be improved, and the photoelectric conversion efficiency can be improved.
  • the upper transparent electrode 109 may have a structure in which only the collector electrodes 107 and 108 are in electrical contact. However, in order to obtain the effect of the present invention more effectively, it is preferable to increase the contact area between the upper transparent electrode 109 and the collector electrodes 107 and 108.
  • the electric resistance of the upper transparent electrode 109a is lower than the electric resistance of the lower transparent electrode 106a.
  • the electrical resistance of the upper transparent electrode 109b is preferably lower than the electrical resistance of the lower transparent electrode 106b.
  • the electrical resistance of the upper transparent electrode 109 may be lower than the electrical resistance of the lower transparent electrode 106 by making the crystallinity of the upper transparent electrode 109 higher than that of the lower transparent electrode 106.
  • the electrical resistance of the upper transparent electrode 109 may be lower than the electrical resistance of the lower transparent electrode 106 by making the crystallinity of the upper transparent electrode 109 higher than that of the lower transparent electrode 106.
  • the solar having excellent fill factor and photoelectric conversion efficiency A battery module can be realized.
  • the collector electrode on one surface side of the adjacent solar battery cells may be electrically connected to the collector electrode on the other surface side.
  • FIG. FIG. 7 is sectional drawing which shows typically schematic structure of the solar cell module 201 which is a photoelectric conversion module concerning Embodiment 3 of this invention.
  • the solar cell module 201 a plurality of solar cells 202 are covered with a sealing layer 203 having light transmittance.
  • the sealing layer 203 for example, ethylene vinyl acetate or the like is used.
  • a light-receiving surface holding substrate 204 having translucency is provided on the surface of the sealing layer 203 on the same side as the light-receiving surface of the solar battery cell 202.
  • a back surface holding substrate 205 is provided on the surface of the sealing layer 203 opposite to the light receiving surface (back surface side) of the solar battery cell 202.
  • the plurality of solar cells 202 are sealed between the light receiving surface holding substrate 204 and the back surface holding substrate 205 via the sealing layer 203.
  • both surfaces of the solar cell module 201 can be used as light receiving surfaces.
  • a frame 206 is provided on the outer periphery of the sealing layer 203, the light receiving surface holding substrate 204, and the back surface holding substrate 205.
  • Each of the solar cells 202 is connected to adjacent solar cells via bus electrodes 208a and 208b formed on the lower transparent electrodes 207a and 207b and wirings 209a and 209b bonded to the bus electrodes 208a and 208b.
  • 202 is electrically connected in series.
  • the bus electrode may be collectively referred to as the bus electrode 208
  • the wiring may be collectively referred to as the wiring 209.
  • the wirings 209a and 209b are connected to the bus electrodes 208 on different planes in the adjacent solar cells 202, respectively. Specifically, the wiring 209a connected to the bus electrode 208a on the light receiving surface side of the solar battery cell 202a is connected to the bus electrode 208c on the back surface side of the solar battery cell 202b adjacent to the solar battery cell 202a. Further, the wiring 209b connected to the bus electrode 208b on the back surface side of the solar battery cell 202a is connected to the bus electrode 208d on the light receiving surface side of the solar battery cell 202c adjacent to the solar battery cell 202a.
  • the solar battery cell 202 constituting the solar battery module 201 the solar battery cell 1 described in the first embodiment or the solar battery 101 described in the second embodiment is used.
  • the above-described upper transparent electrode is not formed on the bus electrode 208.
  • the bus electrode 208 and the wiring 209 are connected by low melting point solder or metal paste. Since the bus electrode 208 and the wiring 209 are electrically connected by a metal material having a resistivity lower than that of the upper transparent electrode, the connection resistance between the bus electrode 208 and the wiring 209 can be reduced.
  • FIG. 8 is a cross-sectional view of the solar cell module 201 taken along line A-A ′ in FIG.
  • the wirings 209a and 209b are bonded onto the bus electrodes 208a and 208b where the upper transparent electrodes 210a and 210b are not formed.
  • the connection between the bus electrode 208 having a low contact resistance and the wiring 209 can be realized. Since the configuration other than the connection between the bus electrode 208 and the wiring 209 of the solar battery cell 202 is the same as that in the first embodiment or the second embodiment, detailed illustration and description are omitted.
  • the solar cell having the structure shown in the first embodiment or the second embodiment has a higher curve factor than the conventional solar cell. And the curve factor of the solar cell module 201 comprised with such a photovoltaic cell also improves. From this, it is clear that the photoelectric conversion efficiency of the solar cell module 201 according to the third embodiment is improved as compared with the conventional solar cell module using solar cells.
  • a solar cell module having excellent fill factor and photoelectric conversion efficiency can be obtained.
  • the photoelectric conversion device according to the present invention is useful for realizing a photoelectric conversion device excellent in photoelectric conversion efficiency.

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Abstract

This photoelectric conversion apparatus has semiconductor layers (a p-type amorphous silicon layer (4) and an n-type amorphous silicon layer (5)), which are formed at least on one surface of a crystalline semiconductor substrate (an n-type crystalline silicon substrate (2)). The photoelectric conversion apparatus is provided with: lower layer transparent electrodes (a lower layer transparent electrode (6a) and a lower layer transparent electrode (6b)), which are composed of a transparent electrode film, and are respectively formed on the semiconductor layers (the p-type amorphous silicon layer (4) and the n-type amorphous silicon layer (5)); collecting electrodes (a collecting electrode (7) and a collecting electrode (8)), which are respectively formed on the lower layer transparent electrodes (the lower layer transparent electrode (6a) and the lower layer transparent electrode (6b)) by respectively being in contact with the lower layer transparent electrodes (the lower layer transparent electrode (6a) and the lower layer transparent electrode (6b)); and upper layer transparent electrodes (an upper layer transparent electrode (9a) and an upper layer transparent electrode (9b)), which are formed of a transparent electrode film to respectively cover the collecting electrodes (the collecting electrode (7) and the collecting electrode (8)), and are formed in electrical contact with a part of each of the collecting electrodes (the collecting electrode (7) and the collecting electrode (8)) and a part of each of the lower layer transparent electrodes (the lower layer transparent electrode (6a) and the lower layer transparent electrode (6b)).

Description

光電変換装置およびその製造方法、光電変換モジュールPhotoelectric conversion device, manufacturing method thereof, and photoelectric conversion module
　本発明は、光電変換装置およびその製造方法、光電変換モジュールに関するものである。 The present invention relates to a photoelectric conversion device, a manufacturing method thereof, and a photoelectric conversion module.
　従来の光電変換装置として、例えば結晶性半導体基板の一面側に導電性の異なる少なくとも薄膜半導体層と透明電極とがこの順で形成され、他面側に導電性の異なる少なくとも非晶質半導体薄膜と透明電極とがこの順で形成され、結晶性半導体基板の一方の面または両面からの光入射により結晶性半導体基板と半導体層で光起電力を発生する太陽電池セルを備えるものがある。この太陽電池セルでは、一面側および他面側の両透明導電上に細線状にパターニングされた集電極が形成される。 As a conventional photoelectric conversion device, for example, at least a thin film semiconductor layer having different conductivity and a transparent electrode are formed in this order on one side of a crystalline semiconductor substrate, and at least an amorphous semiconductor thin film having different conductivity on the other side. A transparent electrode is formed in this order, and there is a solar cell that includes a photovoltaic cell that generates photovoltaic power in the crystalline semiconductor substrate and the semiconductor layer by light incidence from one or both surfaces of the crystalline semiconductor substrate. In this solar battery cell, a collector electrode patterned in a thin line shape is formed on both transparent conductives on one side and the other side.
　このような太陽電池セルでは、光照射により発生した電荷を効率良く収集するために、太陽電池セルの寄生抵抗を低下させなければならない。寄生抵抗を低下させるためには、具体的には、透明電極を構成している錫を添加した酸化インジウム（ＩＴＯ：Indium　Tin　Oxide）の抵抗率および集電極を構成している銀（Ａｇ）の抵抗率を低減する。また、これに加えて透明電極と集電極間との間の接触抵抗も低減する必要がある。 In such a solar battery cell, the parasitic resistance of the solar battery cell must be reduced in order to efficiently collect charges generated by light irradiation. In order to reduce the parasitic resistance, specifically, the resistivity of indium oxide (ITO) added with tin constituting the transparent electrode and the silver (Ag) constituting the collector electrode Reduce resistivity. In addition to this, it is necessary to reduce the contact resistance between the transparent electrode and the collector electrode.
　一方、上記透明電極であるＩＴＯは照射された光を半導体層および結晶性半導体基板まで導くため、光透過性が高くなければならない。ＩＴＯの光透過性を高めるためには、酸素濃度を増加させる必要がある。しかし、ＩＴＯにおいては酸素濃度が増加すると電気抵抗率が上昇するため、光照射により発生した電荷の収集効率が低下し、光電変換効率が低下する。また、透明電極と集電極間の接触抵抗を低下させるためには、透明電極の酸素濃度を低減して電気抵抗率を低下させなければならない。 On the other hand, ITO, which is the transparent electrode, must have high light transmittance in order to guide irradiated light to the semiconductor layer and the crystalline semiconductor substrate. In order to increase the light transmittance of ITO, it is necessary to increase the oxygen concentration. However, in ITO, when the oxygen concentration increases, the electrical resistivity increases, so that the collection efficiency of charges generated by light irradiation decreases, and the photoelectric conversion efficiency decreases. Further, in order to reduce the contact resistance between the transparent electrode and the collecting electrode, the oxygen concentration of the transparent electrode must be reduced to lower the electrical resistivity.
　これらの課題を解決するために、たとえば特許文献１では、集電極と接触している箇所のＩＴＯのみ酸素濃度を低下させることで電気抵抗率を低減し、接触抵抗を減少させている。そして、ＩＴＯにおけるこれ以外の箇所では、酸素濃度を増加させることにより光透過性を確保している。 In order to solve these problems, for example, in Patent Document 1, the electrical resistivity is reduced by reducing the oxygen concentration only in the ITO in contact with the collector electrode, thereby reducing the contact resistance. And in other locations in ITO, the light transmittance is ensured by increasing the oxygen concentration.
　また、たとえば特許文献２では、集電極をメッキ法により形成し、透明電極と集電極との接触箇所のＩＴＯのみを低抵抗とすることにより、接触抵抗を低減している。 For example, in Patent Document 2, the contact resistance is reduced by forming the collector electrode by a plating method and reducing only the ITO at the contact portion between the transparent electrode and the collector electrode.
特開２００４－２１４４４２号公報JP 2004-214442 A 特許第３６１９６８１号公報Japanese Patent No. 3619681
　しかしながら、上記の特許文献１や特許文献２のように集電極に接触する箇所のＩＴＯのみ抵抗を低下させる方法では、集電極の幅が狭い場合は集電極と透明電極との接触面積が小さくなるため接触抵抗が増加する、という問題があった。また、集電極の幅が狭い場合は透明電極の電気抵抗が高い領域が相対的に広くなるため、透明電極の電気抵抗により光電変換効率が低下する、という課題があった。 However, in the method in which the resistance is reduced only in the ITO in contact with the collector electrode as in Patent Document 1 and Patent Document 2 described above, when the width of the collector electrode is narrow, the contact area between the collector electrode and the transparent electrode is reduced. Therefore, there was a problem that the contact resistance increased. Moreover, since the area | region where the electrical resistance of a transparent electrode is high becomes comparatively wide when the width | variety of a collector electrode is narrow, there existed a subject that photoelectric conversion efficiency fell by the electrical resistance of a transparent electrode.
　本発明は、上記に鑑みてなされたものであって、光電変換効率に優れた光電変換装置およびその製造方法を得ることを目的とする。 The present invention has been made in view of the above, and an object thereof is to obtain a photoelectric conversion device excellent in photoelectric conversion efficiency and a method for manufacturing the same.
　上述した課題を解決し、目的を達成するために、本発明にかかる光電変換装置は、結晶性半導体基板の少なくとも片面に半導体層が形成された光電変換装置であって、透明電極膜からなり前記半導体層上に形成された下層透明電極と、前記下層透明電極上に前記下層透明電極に接触して形成された集電極と、透明電極膜からなり前記集電極の上を覆うように形成され、前記集電極の一部および前記下層透明電極の一部と電気的に接触して形成された上層透明電極と、を備えることを特徴とする。 In order to solve the above-described problems and achieve the object, a photoelectric conversion device according to the present invention is a photoelectric conversion device in which a semiconductor layer is formed on at least one surface of a crystalline semiconductor substrate, and includes a transparent electrode film. A lower transparent electrode formed on a semiconductor layer, a collector electrode formed on the lower transparent electrode in contact with the lower transparent electrode, and a transparent electrode film formed to cover the collector electrode; And an upper transparent electrode formed in electrical contact with a part of the collector electrode and a part of the lower transparent electrode.
　本発明によれば、集電極と透明電極との接触面積を広く確保して集電極と透明電極との接触抵抗を低減できるため、寄生抵抗が低減し、光電変換効率に優れた太陽電池セルが得られる、という効果を奏する。 According to the present invention, it is possible to reduce the contact resistance between the collector electrode and the transparent electrode by ensuring a wide contact area between the collector electrode and the transparent electrode, so that a solar cell with reduced parasitic resistance and excellent photoelectric conversion efficiency can be obtained. The effect is obtained.
図１は、本発明の実施の形態１にかかる太陽電池セルの概略構成を模式的に示す斜視図である。FIG. 1 is a perspective view schematically showing a schematic configuration of the solar battery cell according to the first embodiment of the present invention. 図２は、本発明の実施の形態１にかかる太陽電池セルにおける電荷の流れを説明する概念図である。FIG. 2 is a conceptual diagram illustrating the flow of charges in the solar battery cell according to the first embodiment of the present invention. 図３は、実施の形態１にかかる太陽電池セル（実施例）と従来の太陽電池セル（従来例）との光電変換特性を示す図である。FIG. 3 is a diagram showing photoelectric conversion characteristics of the solar battery cell according to the first embodiment (Example) and a conventional solar battery cell (conventional example). 図４－１は、本発明の実施の形態１にかかる太陽電池セルの製造方法の手順の一例を示す断面図である。FIG. 4-1 is a cross-sectional view illustrating an example of the procedure of the method for manufacturing the solar battery cell according to the first embodiment of the present invention. 図４－２は、本発明の実施の形態１にかかる太陽電池セルの製造方法の手順の一例を示す断面図である。FIGS. 4-2 is sectional drawing which shows an example of the procedure of the manufacturing method of the photovoltaic cell concerning Embodiment 1 of this invention. FIGS. 図４－３は、本発明の実施の形態１にかかる太陽電池セルの製造方法の手順の一例を示す断面図である。FIGS. 4-3 is sectional drawing which shows an example of the procedure of the manufacturing method of the photovoltaic cell concerning Embodiment 1 of this invention. FIGS. 図４－４は、本発明の実施の形態１にかかる太陽電池セルの製造方法の手順の一例を示す断面図である。FIGS. 4-4 is sectional drawing which shows an example of the procedure of the manufacturing method of the photovoltaic cell concerning Embodiment 1 of this invention. FIGS. 図４－５は、本発明の実施の形態１にかかる太陽電池セルの製造方法の手順の一例を示す断面図である。FIGS. 4-5 is sectional drawing which shows an example of the procedure of the manufacturing method of the photovoltaic cell concerning Embodiment 1 of this invention. FIGS. 図４－６は、本発明の実施の形態１にかかる太陽電池セルの製造方法の手順の一例を示す断面図である。FIGS. 4-6 is sectional drawing which shows an example of the procedure of the manufacturing method of the photovoltaic cell concerning Embodiment 1 of this invention. FIGS. 図５は、本発明の実施の形態２にかかる太陽電池セルの概略構成を模式的に示す斜視図である。FIG. 5 is a perspective view schematically showing a schematic configuration of the solar battery cell according to the second embodiment of the present invention. 図６－１は、本発明の実施の形態２にかかる太陽電池セルの製造方法の手順の一例を示す断面図である。FIG. 6-1 is a cross-sectional view illustrating an example of the procedure of the method for manufacturing the solar battery cell according to the second embodiment of the present invention. 図６－２は、本発明の実施の形態２にかかる太陽電池セルの製造方法の手順の一例を示す断面図である。FIG. 6-2 is a cross-sectional view illustrating an example of the procedure of the method for manufacturing the solar battery cell according to the second embodiment of the present invention. 図６－３は、本発明の実施の形態２にかかる太陽電池セルの製造方法の手順の一例を示す断面図である。6-3 is sectional drawing which shows an example of the procedure of the manufacturing method of the photovoltaic cell concerning Embodiment 2 of this invention. 図６－４は、本発明の実施の形態２にかかる太陽電池セルの製造方法の手順の一例を示す断面図である。6-4 is sectional drawing which shows an example of the procedure of the manufacturing method of the photovoltaic cell concerning Embodiment 2 of this invention. 図６－５は、本発明の実施の形態２にかかる太陽電池セルの製造方法の手順の一例を示す断面図である。FIGS. 6-5 is sectional drawing which shows an example of the procedure of the manufacturing method of the photovoltaic cell concerning Embodiment 2 of this invention. FIGS. 図６－６は、本発明の実施の形態２にかかる太陽電池セルの製造方法の手順の一例を示す断面図である。FIGS. 6-6 is sectional drawing which shows an example of the procedure of the manufacturing method of the photovoltaic cell concerning Embodiment 2 of this invention. FIGS. 図７は、本発明の実施の形態３にかかる太陽電池モジュールの概略構成を模式的に示す断面図である。FIG. 7: is sectional drawing which shows typically schematic structure of the solar cell module concerning Embodiment 3 of this invention. 図８は、図７の線分Ａ-Ａ’に沿った太陽電池モジュールの断面図である。FIG. 8 is a cross-sectional view of the solar cell module taken along line A-A ′ in FIG. 7.
　以下に、本発明にかかる光電変換装置およびその製造方法の実施の形態を図面に基づいて詳細に説明する。なお、本発明は以下の記述に限定されるものではなく、本発明の要旨を逸脱しない範囲において適宜変更可能である。また、以下に示す図面においては、理解の容易のため、各部材の縮尺が実際とは異なる場合がある。各図面間においても同様である。 Hereinafter, embodiments of a photoelectric conversion device and a manufacturing method thereof according to the present invention will be described in detail with reference to the drawings. In addition, this invention is not limited to the following description, In the range which does not deviate from the summary of this invention, it can change suitably. In the drawings shown below, the scale of each member may be different from the actual scale for easy understanding. The same applies between the drawings.
実施の形態１．
　図１は、本発明の実施の形態１にかかる光電変換装置である太陽電池セル１の概略構成を模式的に示す斜視図である。この太陽電池セル１は、光電変換層を構成する両側の表面が凹凸加工された光電変換層を構成するｎ型結晶珪素基板２の一面側の表面に厚さが略５ｎｍのｉ型非晶質珪素層３ａが形成され、他面側の表面に厚さが略５ｎｍのｉ型非晶質珪素層３ｂが形成されている。これにより、非晶質珪素層と結晶珪素基板とのヘテロ接合が形成される。ｎ型結晶珪素基板２は、比抵抗が１～１０Ω・ｃｍ、結晶配向が＜１００＞、厚さが５０μｍ以上３００μｍ以下の珪素基板である。なお、図１においては簡略化のためｎ型結晶珪素基板２の表面の凹凸構造の図示を省略している。 Embodiment 1 FIG.
FIG. 1 is a perspective view schematically showing a schematic configuration of a solar battery cell 1 which is a photoelectric conversion device according to Embodiment 1 of the present invention. This solar cell 1 is an i-type amorphous material having a thickness of approximately 5 nm on the surface of one surface of an n-type crystalline silicon substrate 2 constituting a photoelectric conversion layer in which both surfaces constituting the photoelectric conversion layer are processed to be uneven. A silicon layer 3a is formed, and an i-type amorphous silicon layer 3b having a thickness of about 5 nm is formed on the surface on the other side. Thereby, a heterojunction between the amorphous silicon layer and the crystalline silicon substrate is formed. The n-type crystalline silicon substrate 2 is a silicon substrate having a specific resistance of 1 to 10 Ω · cm, a crystal orientation of <100>, and a thickness of 50 μm to 300 μm. In FIG. 1, for the sake of simplicity, the illustration of the concavo-convex structure on the surface of the n-type crystalline silicon substrate 2 is omitted.
　ｉ型非晶質珪素層３ａ上には、厚さが略５ｎｍのｐ型非晶質珪素層４が形成され、ｉ型非晶質珪素層３ｂ上には厚さが略５ｎｍのｎ型非晶質珪素層５が形成されている。これにより、ｉ型非晶質珪素層３ａを介してｎ型結晶珪素基板２とｐ型非晶質珪素層４とによりｐｎ接合が形成される。真性半導体層（ｉ型非晶質珪素層３ａおよびｉ型非晶質珪素層３ｂ）はヘテロ接合間の不純物拡散を抑制し、急峻な不純物プロファイルをもつ接合を形成することができるため、良好な接合界面形成により高い開放電圧を得ることができる。 A p-type amorphous silicon layer 4 having a thickness of about 5 nm is formed on the i-type amorphous silicon layer 3a, and an n-type non-layer having a thickness of about 5 nm is formed on the i-type amorphous silicon layer 3b. A crystalline silicon layer 5 is formed. Thereby, a pn junction is formed by the n-type crystalline silicon substrate 2 and the p-type amorphous silicon layer 4 via the i-type amorphous silicon layer 3a. Intrinsic semiconductor layers (i-type amorphous silicon layer 3a and i-type amorphous silicon layer 3b) can suppress diffusion of impurities between heterojunctions and can form a junction having a steep impurity profile. A high open circuit voltage can be obtained by forming the bonding interface.
　ｐ型非晶質珪素層４上には厚さが略７０ｎｍの下層透明電極６ａが形成され、ｎ型非晶質珪素層５上には厚さが略７０ｎｍの下層透明電極６ｂが形成されている。下層透明電極６ａ上には銀（Ａｇ）からなる厚さが略６０μｍの集電極７が形成され、下層透明電極６ｂ上には銀（Ａｇ）からなる厚さが略６０μｍの集電極８が形成されている。なお、以下においては下層透明電極６ａと下層透明電極６ｂとを総称して下層透明電極６と呼ぶ場合がある。 A lower transparent electrode 6a having a thickness of approximately 70 nm is formed on the p-type amorphous silicon layer 4, and a lower transparent electrode 6b having a thickness of approximately 70 nm is formed on the n-type amorphous silicon layer 5. Yes. A collector electrode 7 made of silver (Ag) with a thickness of about 60 μm is formed on the lower transparent electrode 6a, and a collector electrode 8 made of silver (Ag) with a thickness of about 60 μm is formed on the lower transparent electrode 6b. Has been. In the following, the lower transparent electrode 6a and the lower transparent electrode 6b may be collectively referred to as the lower transparent electrode 6.
　集電極７は、幅が略２０μｍ、厚さが略６０μｍであり一定のピッチで互いに略平行に配置された複数のグリッド電極７ａと、幅が略１ｍｍでありグリッド電極７ａに交差して電気的に接続されたバス電極７ｂとから構成されている。集電極８は、幅が略２０μｍ、厚さが略６０μｍであり一定のピッチで互いに略平行に配置された複数のグリッド電極８ａと、幅が略１ｍｍでありグリッド電極８ａに交差して電気的に接続されたバス電極８ｂとから構成されている。 The collector electrode 7 has a width of about 20 μm, a thickness of about 60 μm, and a plurality of grid electrodes 7 a arranged substantially in parallel with each other at a constant pitch, and a width of about 1 mm, which intersects the grid electrodes 7 a electrically. And a bus electrode 7b connected to the. The collector electrode 8 has a width of about 20 μm, a thickness of about 60 μm, a plurality of grid electrodes 8 a arranged at a certain pitch and substantially parallel to each other, and a width of about 1 mm, which intersects the grid electrodes 8 a and is electrically And the bus electrode 8b connected to the.
　そして、下層透明電極６ａの一部と集電極７を覆うように、上層透明電極９ａが形成され、下層透明電極６ｂの一部と集電極８を覆うように、上層透明電極９ｂが形成されている。下層透明電極６ａは、表面において集電極７に隣接した領域を上層透明電極９ａにより覆われ、下層透明電極６ｂは、表面において集電極８に隣接した領域を上層透明電極９ｂにより覆われている。なお、以下においては上層透明電極９ａと上層透明電極９ｂとを総称して上層透明電極９と呼ぶ場合がある。また、下層透明電極６ａと上層透明電極９ａとを総称して一面側透明電極と、下層透明電極６ｂと上層透明電極９ｂとを総称して他面側透明電極と呼ぶ場合がある。このとき上層透明電極９ａ、９ｂは、バス電極７ｂ、８ｂそれぞれの上には形成されなくてもよい。 An upper transparent electrode 9a is formed so as to cover a part of the lower transparent electrode 6a and the collector electrode 7, and an upper transparent electrode 9b is formed so as to cover a part of the lower transparent electrode 6b and the collector electrode 8. Yes. In the lower transparent electrode 6a, the region adjacent to the collector electrode 7 on the surface is covered with the upper transparent electrode 9a, and in the lower transparent electrode 6b, the region adjacent to the collector electrode 8 on the surface is covered with the upper transparent electrode 9b. In the following description, the upper transparent electrode 9a and the upper transparent electrode 9b may be collectively referred to as the upper transparent electrode 9. Further, the lower transparent electrode 6a and the upper transparent electrode 9a may be collectively referred to as one surface side transparent electrode, and the lower transparent electrode 6b and the upper transparent electrode 9b may be collectively referred to as other surface side transparent electrodes. At this time, the upper transparent electrodes 9a and 9b may not be formed on the bus electrodes 7b and 8b, respectively.
　集電極７は下層透明電極６ａに接触し、さらに下層透明電極６ａと集電極７との両方に電気的に接続された上層透明電極９ａを備えることにより、太陽電池セル１では一面側透明電極と集電極７との接触面積を、従来の太陽電池セルに比べて広く確保できる。また、集電極８は下層透明電極６ｂに接触し、さらに下層透明電極６ｂと集電極８との両方に電気的に接続された上層透明電極９ｂを備えることにより、太陽電池セル１では他面側透明電極と集電極８との接触面積を、従来の太陽電池セルに比べて広く確保できる。太陽電池セル１では、透明電極と集電極間との接触面積が増加することにより、透明電極と集電極との間の接触抵抗が低下して寄生抵抗が低下し、発電効率、曲線因子が向上する。 The collector electrode 7 is in contact with the lower transparent electrode 6a, and further includes an upper transparent electrode 9a electrically connected to both the lower transparent electrode 6a and the collector electrode 7. The contact area with the collector electrode 7 can be secured wider than that of a conventional solar battery cell. Moreover, the collector electrode 8 is in contact with the lower transparent electrode 6b, and further includes the upper transparent electrode 9b electrically connected to both the lower transparent electrode 6b and the collector electrode 8, whereby the solar cell 1 has the other surface side. The contact area between the transparent electrode and the collector electrode 8 can be secured wider than that of a conventional solar battery cell. In the solar battery cell 1, the contact area between the transparent electrode and the collector electrode is increased, so that the contact resistance between the transparent electrode and the collector electrode is reduced, the parasitic resistance is lowered, and the power generation efficiency and the fill factor are improved. To do.
　図２は、本発明の実施の形態１にかかる太陽電池セル１における電荷の流れを説明する概念図である。図２では、ｎ型結晶珪素基板２の面方向において集電極７の延在方向に略直交する方向に沿った断面を示しており、図中の矢印は電荷の流れ流方向を示している。例えば太陽電池セル１の片面側または両面側から太陽電池セル１に対して光を照射すると、光電変換層であるｎ型結晶珪素基板２で電荷が発生する。すなわち、光が太陽電池セル１に照射されると、電荷としてホールと電子が生成する。 FIG. 2 is a conceptual diagram illustrating the flow of charges in the solar battery cell 1 according to the first embodiment of the present invention. FIG. 2 shows a cross section along a direction substantially orthogonal to the extending direction of the collector electrode 7 in the surface direction of the n-type crystalline silicon substrate 2, and the arrows in the figure indicate the flow direction of charges. For example, when the solar cell 1 is irradiated with light from one side or both sides of the solar cell 1, electric charge is generated in the n-type crystalline silicon substrate 2 that is a photoelectric conversion layer. That is, when the solar battery cell 1 is irradiated with light, holes and electrons are generated as charges.
　太陽電池セル１における一面側では、発生した電荷のうち一部は、ｉ型非晶質珪素層３ａ、ｐ型非晶質珪素層４を通じて、下層透明電極６ａに到達する。下層透明電極６ａに到達した電荷は、集電極（グリッド電極）７ａと下層透明電極６ａとが接触している領域付近まで下層透明電極６ａ内を移動する。そして、集電極（グリッド電極）７ａ付近において、一部の電荷は下層透明電極６ａを通って集電極（グリッド電極）７ａの下面から、その他の電荷は上層透明電極９ａを通って集電極（グリッド電極）７ａの側面および上面から集電極（グリッド電極）７ａに移動する。したがって、太陽電池セル１においては、電荷は従来の太陽電池セルと比較して広い領域、すなわち集電極（グリッド電極）７ａと一面側透明電極（下層透明電極６ａ、上層透明電極９ａ）とが接触している接触面を通って下層透明電極６ａから集電極（グリッド電極）７ａに到達する。なお、バス電極７ｂと一面側透明電極（下層透明電極６ａ、上層透明電極９ａ）とが接触している部分でも、上記と同様な電荷の移動が生じる。 On one side of the solar battery cell 1, a part of the generated charge reaches the lower transparent electrode 6 a through the i-type amorphous silicon layer 3 a and the p-type amorphous silicon layer 4. The electric charge that has reached the lower transparent electrode 6a moves in the lower transparent electrode 6a to the vicinity of the region where the collector electrode (grid electrode) 7a and the lower transparent electrode 6a are in contact. In the vicinity of the collector electrode (grid electrode) 7a, some charges pass through the lower transparent electrode 6a from the lower surface of the collector electrode (grid electrode) 7a, and other charges pass through the upper transparent electrode 9a. The electrode moves from the side surface and the upper surface of the electrode 7a to the collector electrode (grid electrode) 7a. Therefore, in the solar battery cell 1, the electric charge is larger than that of the conventional solar battery cell, that is, the collector electrode (grid electrode) 7a and the one-surface side transparent electrode (lower transparent electrode 6a, upper transparent electrode 9a) are in contact with each other. The lower transparent electrode 6a reaches the collector electrode (grid electrode) 7a through the contact surface. It should be noted that the same charge movement as described above also occurs at the portion where the bus electrode 7b and the one-side transparent electrode (lower transparent electrode 6a, upper transparent electrode 9a) are in contact.
　太陽電池セル１における他面側では、発生した電荷のうち一部は、ｉ型非晶質珪素層３ｂ、ｎ型非晶質珪素層５を通じて、下層透明電極６ｂに到達する。下層透明電極６ｂに到達した電荷は、集電極（グリッド電極）８ａと下層透明電極６ｂとが接触している領域付近まで下層透明電極６ｂ内を移動する。そして、集電極（グリッド電極）８ａ付近において、一部の電荷は下層透明電極６ｂを通って集電極（グリッド電極）８ａの下面から、その他の電荷は上層透明電極９ｂを通って集電極（グリッド電極）８ａの側面および上面から集電極（グリッド電極）８ａに移動する。したがって、太陽電池セル１においては、電荷は従来の太陽電池セルと比較して広い領域、すなわち集電極（グリッド電極）８ａと他面側透明電極（下層透明電極６ｂ、上層透明電極９ｂ）とが接触している接触面を通って下層透明電極６ａから集電極（グリッド電極）８ａに到達する。なお、バス電極８ｂと他面側透明電極（下層透明電極６ｂ、上層透明電極９ｂａ）とが接触している部分でも、上記と同様な電荷の移動が生じる。 On the other surface side of the solar battery cell 1, a part of the generated charges reaches the lower transparent electrode 6 b through the i-type amorphous silicon layer 3 b and the n-type amorphous silicon layer 5. The electric charge that has reached the lower transparent electrode 6b moves in the lower transparent electrode 6b to the vicinity of the region where the collector electrode (grid electrode) 8a and the lower transparent electrode 6b are in contact with each other. In the vicinity of the collector electrode (grid electrode) 8a, some charges pass through the lower transparent electrode 6b from the lower surface of the collector electrode (grid electrode) 8a, and other charges pass through the upper transparent electrode 9b. The electrode moves from the side surface and the upper surface of the electrode 8a to the collector electrode (grid electrode) 8a. Therefore, in the solar battery cell 1, the electric charge is wider than that of the conventional solar battery cell, that is, the collector electrode (grid electrode) 8a and the other side transparent electrode (lower transparent electrode 6b, upper transparent electrode 9b). It reaches the collector electrode (grid electrode) 8a from the lower transparent electrode 6a through the contacting surface. It should be noted that the same charge movement as described above also occurs at the portion where the bus electrode 8b and the other transparent electrode (lower transparent electrode 6b, upper transparent electrode 9ba) are in contact.
　太陽電池セル１においては、グリッド電極７ａおよびバス電極７ｂのサイズは幅が略２０μｍ、厚さが略６０μｍである。このため、太陽電池セル１における集電極と透明電極との接触面積（導通面積）は、これと同じサイズの集電極を有して該集電極と透明電極との接触面が集電極の下面のみである従来の太陽電池セルに対して略８倍となる。 In the solar battery cell 1, the size of the grid electrode 7a and the bus electrode 7b is about 20 μm in width and about 60 μm in thickness. For this reason, the contact area (conduction area) between the collector electrode and the transparent electrode in the solar battery cell 1 has a collector electrode of the same size as this, and the contact surface between the collector electrode and the transparent electrode is only the lower surface of the collector electrode. This is approximately 8 times the conventional solar battery cell.
　図３は、実施の形態１にかかる太陽電池セル１（実施例）と上記従来の太陽電池セル（従来例）との光電変換特性を示す図である。図３では、電圧（Ｖ）と短絡電流密度（相対値）との関係を示している。短絡電流密度は、従来例に対する実施例の相対値を示している。図３から、太陽電池セル１の曲線因子が向上していることが分かる。太陽電池セル１の曲線因子の向上は、上層透明電極９ａを備えることにより下層透明電極６ａから集電極７への導通面積が増加して一面側透明電極と集電極７間の接触抵抗が低減したこと、および上層透明電極９ｂを備えることにより下層透明電極６ｂから集電極８への導通面積が増加して他面側透明電極と集電極８間の接触抵抗が低減したことに因るものである。したがって、実施の形態１にかかる太陽電池セル１の光電変換効率は、従来の太陽電池セルに比べて向上していることが明らかとなった。 FIG. 3 is a diagram illustrating photoelectric conversion characteristics of the solar battery cell 1 according to the first embodiment (Example) and the conventional solar battery cell (conventional example). FIG. 3 shows the relationship between voltage (V) and short circuit current density (relative value). The short-circuit current density indicates a relative value of the example with respect to the conventional example. It can be seen from FIG. 3 that the fill factor of the solar battery cell 1 is improved. The improvement of the fill factor of the solar cell 1 is that by providing the upper transparent electrode 9a, the conductive area from the lower transparent electrode 6a to the collector electrode 7 is increased, and the contact resistance between the one-side transparent electrode and the collector electrode 7 is reduced. This is because the conductive area from the lower transparent electrode 6b to the collector electrode 8 is increased by providing the upper transparent electrode 9b, and the contact resistance between the other transparent electrode and the collector electrode 8 is reduced. . Therefore, it became clear that the photoelectric conversion efficiency of the solar cell 1 according to the first embodiment is improved as compared with the conventional solar cell.
　次に、上記のように構成された実施の形態１にかかる太陽電池セル１の製造方法について図４－１～図４－６を参照して説明する。図４－１～図４－６は、実施の形態１にかかる太陽電池セル１の製造方法の手順の一例を示す断面図である。 Next, a method for manufacturing the solar cell 1 according to the first embodiment configured as described above will be described with reference to FIGS. 4-1 to 4-6. FIGS. 4-1 to 4-6 are cross-sectional views illustrating an example of the procedure of the method for manufacturing the solar battery cell 1 according to the first embodiment.
　まず、図４－１に示すように、ｎ型結晶珪素基板２の表面にテクスチャと呼ばれる凹凸構造を形成する。テクスチャは太陽電池セル１に入射する光の反射を低減し、ｎ型結晶珪素基板２内における光散乱を促進する。凹凸構造の形成には、酸性またはアルカリ性のエッチング溶液を用いたｎ型結晶珪素基板２の表面のウエットエッチングを用いることができる。 First, as shown in FIG. 4A, an uneven structure called a texture is formed on the surface of the n-type crystalline silicon substrate 2. The texture reduces reflection of light incident on the solar battery cell 1 and promotes light scattering in the n-type crystalline silicon substrate 2. For the formation of the concavo-convex structure, wet etching of the surface of the n-type crystalline silicon substrate 2 using an acidic or alkaline etching solution can be used.
　また、凹凸構造の形成前に、ｎ型結晶珪素基板２の表面のダメージ層を除去する工程を実施してもよい。また、これに加えてダメージ層除去工程後に、基板内不純物のゲッタリング処理を施すことが太陽電池セルの性能向上には好ましい。ゲッタリング処理としては、例えばリン拡散処理などを用いる。また、凹凸構造の形成は、ｎ型結晶珪素基板２において太陽電池セル１の光入射側となる面だけに施してもよい。 Further, a step of removing the damaged layer on the surface of the n-type crystalline silicon substrate 2 may be performed before the formation of the concavo-convex structure. In addition to this, it is preferable to perform gettering treatment of impurities in the substrate after the damaged layer removing step in order to improve the performance of the solar battery cell. As the gettering process, for example, a phosphorus diffusion process or the like is used. The formation of the concavo-convex structure may be performed only on the surface of the n-type crystalline silicon substrate 2 on the light incident side of the solar cell 1.
　つぎに、図４－２に示すように、ｎ型結晶珪素基板２の一面側にｉ型非晶質珪素層３ａとｐ型非晶質珪素層４とをこの順番で化学気相成長（ＣＶＤ）法を用いて形成する。ｉ型非晶質珪素層３ａおよびｐ型非晶質珪素層４の層厚は、それぞれの略５ｎｍである。なお、実施の形態１ではｉ型非晶質珪素層３ａおよびｐ型非晶質珪素層４の層厚を略５ｎｍとしたが、層の形成条件によってはたとえば５ｎｍ以上１０ｎｍ以下の範囲の層厚でも構わない。 Next, as shown in FIG. 4B, an i-type amorphous silicon layer 3a and a p-type amorphous silicon layer 4 are formed on one surface side of the n-type crystalline silicon substrate 2 in this order by chemical vapor deposition (CVD). ) Method. The i-type amorphous silicon layer 3a and the p-type amorphous silicon layer 4 have a thickness of about 5 nm. In the first embodiment, the i-type amorphous silicon layer 3a and the p-type amorphous silicon layer 4 have a thickness of about 5 nm. However, depending on the layer formation conditions, for example, the layer thickness is in the range of 5 nm to 10 nm. It doesn't matter.
　ＣＶＤ法としては、たとえばプラズマＣＶＤ法、熱ＣＶＤ法などを用いることが好ましい。光電変換層であるｎ型結晶珪素基板２に対して十分な内蔵電界を発生させるためには、ｐ型非晶質珪素層４のバンドギャップは１．７ｅＶ以上、活性化エネルギーは０．４ｅＶ以下であることが必要である。なおｉ型非晶質珪素層３ａの代わりに、ｉ型非晶質炭化珪素層、ｉ型非晶質酸化珪素層またはこれらを積層した多層膜を用いてもよい。また、ｐ型非晶質珪素層４の代わりにｐ型非晶質炭化珪素層、ｐ型非晶質酸化珪素層、ｐ型微結晶珪素層またはこれらを積層した多層膜などを用いてもよい。 As the CVD method, for example, a plasma CVD method or a thermal CVD method is preferably used. In order to generate a sufficient built-in electric field for the n-type crystalline silicon substrate 2 which is a photoelectric conversion layer, the band gap of the p-type amorphous silicon layer 4 is 1.7 eV or more and the activation energy is 0.4 eV or less. It is necessary to be. Instead of i-type amorphous silicon layer 3a, an i-type amorphous silicon carbide layer, an i-type amorphous silicon oxide layer, or a multilayer film in which these layers are stacked may be used. Instead of the p-type amorphous silicon layer 4, a p-type amorphous silicon carbide layer, a p-type amorphous silicon oxide layer, a p-type microcrystalline silicon layer, or a multilayer film in which these layers are laminated may be used. .
　つぎに、図４－３に示すように、ｎ型結晶珪素基板２の他面側にｉ型非晶質珪素層３ｂとｎ型非晶質珪素層５とをこの順番でＣＶＤ法を用いて形成する。ｉ型非晶質珪素層３ｂおよびｎ型非晶質珪素層５の層厚は、それぞれ略５ｎｍである。なお、実施の形態１ではｉ型非晶質珪素層３ｂおよびｎ型非晶質珪素層５の層厚を略５ｎｍとしたが、層の形成条件によってはたとえば５ｎｍ以上２０ｎｍ以下の範囲の層厚でも構わない。 Next, as shown in FIG. 4-3, the i-type amorphous silicon layer 3b and the n-type amorphous silicon layer 5 are formed in this order on the other surface side of the n-type crystalline silicon substrate 2 using the CVD method. Form. The i-type amorphous silicon layer 3b and the n-type amorphous silicon layer 5 each have a thickness of about 5 nm. In the first embodiment, the i-type amorphous silicon layer 3b and the n-type amorphous silicon layer 5 have a thickness of about 5 nm. However, depending on the layer formation conditions, for example, a layer thickness in the range of 5 nm to 20 nm. It doesn't matter.
　ＣＶＤ法としては、たとえばプラズマＣＶＤ法、熱ＣＶＤ法などを用いることが好ましい。光電変換層であるｎ型結晶珪素基板２に対して十分な内蔵電界を発生させるためには、ｎ型非晶質珪素層５のバンドギャップは１．７ｅＶ以上、活性化エネルギーは０．３ｅＶ以下であることが必要である。なおｉ型非晶質珪素層３ｂの代わりに、ｉ型非晶質炭化珪素層、ｉ型非晶質酸化珪素層またはこれらを積層した多層膜を用いてもよい。また、ｎ型非晶質珪素層５の代わりにｎ型非晶質炭化珪素層、ｎ型非晶質酸化珪素層、ｎ型微結晶珪素層またはこれらを積層した多層膜などを用いてもよい。 As the CVD method, for example, a plasma CVD method or a thermal CVD method is preferably used. In order to generate a sufficient built-in electric field for the n-type crystalline silicon substrate 2 which is a photoelectric conversion layer, the band gap of the n-type amorphous silicon layer 5 is 1.7 eV or more and the activation energy is 0.3 eV or less. It is necessary to be. Instead of i-type amorphous silicon layer 3b, an i-type amorphous silicon carbide layer, an i-type amorphous silicon oxide layer, or a multilayer film in which these layers are stacked may be used. Instead of the n-type amorphous silicon layer 5, an n-type amorphous silicon carbide layer, an n-type amorphous silicon oxide layer, an n-type microcrystalline silicon layer, or a multilayer film in which these layers are stacked may be used. .
　また、ｉ型非晶質珪素層３ｂおよびｎ型非晶質珪素層５の形成後、ｉ型非晶質珪素層３ａおよびｉ型非晶質珪素層３ｂと、ｎ型結晶珪素基板２との界面欠陥低減のために、不活性ガスまたは不活性ガスで希釈した水素ガス中で熱アニール処理を施してもよい。アニール温度は２００℃以下が好ましい。また、ｉ型非晶質珪素層３ａおよびｐ型非晶質珪素層４と、ｉ型非晶質珪素層３ｂおよびｎ型非晶質珪素層５との形成順序を反対にしてもよい。 Further, after the formation of the i-type amorphous silicon layer 3b and the n-type amorphous silicon layer 5, the i-type amorphous silicon layer 3a and the i-type amorphous silicon layer 3b and the n-type crystalline silicon substrate 2 In order to reduce interface defects, thermal annealing treatment may be performed in an inert gas or hydrogen gas diluted with an inert gas. The annealing temperature is preferably 200 ° C. or lower. Further, the formation order of i-type amorphous silicon layer 3a and p-type amorphous silicon layer 4, i-type amorphous silicon layer 3b and n-type amorphous silicon layer 5 may be reversed.
　つぎに、図４－４に示すように、ｐ型非晶質珪素層４上に下層透明電極６ａを、ｎ型非晶質珪素層５上に下層透明電極６ｂをスパッタリング法または蒸着法を用いて形成する。下層透明電極６ａおよび下層透明電極６ｂの透明電極材料としては、ＩＴＯまたは酸化インジウム（Ｉｎ２Ｏ３：Indium　Oxide）を用いる。下層透明電極６ａおよび下層透明電極６ｂの膜厚は、反射率低減の観点から略７０ｎｍが好ましい。また、透明電極の電気抵抗率は低いことが望ましいが、導電性を担うキャリア密度が高いと透明電極での光吸収率が増加する。このため、透明電極として用いる材料は高キャリア移動度を実現できなければならない。７０ｎｍの層厚で十分低い電気抵抗率を達成するために、キャリア移動度はたとえば１００ｃｍ２／Ｖｓ以上が好ましい。なお、下層透明電極材料としてアルミニウム（Ａｌ）やガリウム（Ｇａ）などを添加した酸化亜鉛（ＺｎＯ：Zinc　Oxide）を用いてもよい。 Next, as shown in FIG. 4-4, the lower transparent electrode 6a is formed on the p-type amorphous silicon layer 4 and the lower transparent electrode 6b is formed on the n-type amorphous silicon layer 5 by sputtering or vapor deposition. Form. As the transparent electrode material of the lower transparent electrode 6a and the lower transparent electrode 6b, ITO or indium oxide (In 2 O 3 : Indium Oxide) is used. The thickness of the lower transparent electrode 6a and the lower transparent electrode 6b is preferably about 70 nm from the viewpoint of reducing the reflectance. Moreover, it is desirable that the electrical resistivity of the transparent electrode is low, but if the carrier density responsible for conductivity is high, the light absorption rate at the transparent electrode increases. For this reason, the material used as a transparent electrode must be able to realize high carrier mobility. In order to achieve a sufficiently low electric resistivity with a layer thickness of 70 nm, the carrier mobility is preferably 100 cm 2 / Vs or more, for example. In addition, you may use the zinc oxide (ZnO: Zinc Oxide) which added aluminum (Al), gallium (Ga), etc. as a lower layer transparent electrode material.
　つぎに、図４－５に示すように、下層透明電極６ａ上にＡｇで構成される集電極７を、下層透明電極６ｂ上にＡｇで構成される集電極８をスクリーン印刷法で形成する。図４－５においてはグリッド電極７ａおよびグリッド電極８ａのみを示している。集電極７を構成するグリッド電極７ａおよび集電極８を構成するグリッド電極８ａの幅は、太陽電池セル１に入射する光の遮光を抑制するために狭いほど好ましい。しかし、グリッド電極７ａおよびグリッド電極８ａ幅が狭い場合には、断面積が小さくなるために電気抵抗が増加する。したがって、断面積を大きくして電気抵抗を低減するために、グリッド電極７ａおよびグリッド電極８ａは、幅が狭く、層厚が大きいことが好ましい。実施の形態１では、グリッド電極７ａおよびグリッド電極８ａの幅を略２０μｍ、層厚を略６０μｍとした。なお、集電極７および集電極８は、スクリーン印刷の他に、メッキ法などで形成してもよい。また、集電極７および集電極８の材料として銅（Ｃｕ）を用いてもよい。集電極７および集電極８の印刷後、２００℃以下で焼成を行う。 Next, as shown in FIG. 4-5, a collector electrode 7 made of Ag is formed on the lower transparent electrode 6a, and a collector electrode 8 made of Ag is formed on the lower transparent electrode 6b by screen printing. In FIG. 4-5, only the grid electrode 7a and the grid electrode 8a are shown. The width of the grid electrode 7a constituting the collector electrode 7 and the grid electrode 8a constituting the collector electrode 8 is preferably as narrow as possible in order to prevent light incident on the solar cell 1 from being blocked. However, when the widths of the grid electrode 7a and the grid electrode 8a are narrow, the cross-sectional area becomes small and the electrical resistance increases. Therefore, in order to increase the cross-sectional area and reduce the electrical resistance, it is preferable that the grid electrode 7a and the grid electrode 8a have a narrow width and a large layer thickness. In the first embodiment, the width of the grid electrode 7a and the grid electrode 8a is approximately 20 μm, and the layer thickness is approximately 60 μm. The collecting electrode 7 and the collecting electrode 8 may be formed by plating or the like in addition to screen printing. Further, copper (Cu) may be used as a material for the collector electrode 7 and the collector electrode 8. After the collector electrode 7 and the collector electrode 8 are printed, baking is performed at 200 ° C. or lower.
　つぎに、図４－６に示すように、下層透明電極６ａ上の一部と集電極７とを覆うように上層透明電極９ａを集電極７の形状に沿った形状にスクリーン印刷で形成する。また、下層透明電極６ｂ上の一部と集電極８とを覆うように上層透明電極９ｂを集電極８の形状に沿った形状にスクリーン印刷で形成する。上層透明電極９ａおよび上層透明電極９ｂの透明電極材料としては、ＩＴＯを用いる。また、上層透明電極９ａおよび上層透明電極９ｂの透明電極材料として酸化インジウム（Ｉｎ２Ｏ３：Indium　Oxide）やアルミニウム（Ａｌ）やガリウム（Ｇａ）などを添加した酸化亜鉛（ＺｎＯ：Zinc　Oxide）を用いてもよい。なお、集電極７および集電極８がそれぞれ上層透明電極９ａ、９ｂで覆われることで集電極７および集電極８を保護でき、信頼性が向上する、という利点もある。 Next, as shown in FIG. 4-6, the upper transparent electrode 9a is formed by screen printing in a shape along the shape of the collector electrode 7 so as to cover a part of the lower transparent electrode 6a and the collector electrode 7. Further, the upper transparent electrode 9b is formed by screen printing in a shape along the shape of the collector electrode 8 so as to cover a part of the lower transparent electrode 6b and the collector electrode 8. ITO is used as a transparent electrode material for the upper transparent electrode 9a and the upper transparent electrode 9b. Further, zinc oxide (ZnO: Zinc Oxide) to which indium oxide (In 2 O 3 : Indium Oxide), aluminum (Al), gallium (Ga) or the like is added is used as a transparent electrode material of the upper transparent electrode 9a and the upper transparent electrode 9b. It may be used. Note that the collector electrode 7 and the collector electrode 8 are respectively covered with the upper transparent electrodes 9a and 9b, whereby the collector electrode 7 and the collector electrode 8 can be protected, and the reliability is improved.
　また、上層透明電極９ａの層厚は下層透明電極６ａより厚くし、上層透明電極９ｂの層厚は下層透明電極６ｂより厚くすることが好ましい。これにより、上層透明電極９ａ、９ｂの抵抗が下層透明電極６ａ、６ｂに比べて低くなる。そして光電変換層であるｎ型結晶珪素基板２で発生した電荷の多くは上層透明電極９ａを通って集電極７へ、上層透明電極９ｂを通って集電極８へ向かって導通し、集電極７と上層透明電極間９ａの接触面から集電極７に、集電極８と上層透明電極間９ｂの接触面から集電極８に到達する。結果として、一面側透明電極と集電極７との間の接触面積および他面側下層透明電極と集電極８との間の接触面積が増加し、接触抵抗が低下する。 The layer thickness of the upper transparent electrode 9a is preferably greater than that of the lower transparent electrode 6a, and the layer thickness of the upper transparent electrode 9b is preferably greater than that of the lower transparent electrode 6b. Thereby, the resistance of the upper transparent electrodes 9a and 9b is lower than that of the lower transparent electrodes 6a and 6b. Then, most of the charges generated in the n-type crystalline silicon substrate 2 which is a photoelectric conversion layer are conducted to the collector electrode 7 through the upper transparent electrode 9a and to the collector electrode 8 through the upper transparent electrode 9b. The collector electrode 7 reaches the collector electrode 7 from the contact surface between the upper transparent electrode 9a and the collector electrode 8 from the contact surface between the collector electrode 8 and the upper transparent electrode 9b. As a result, the contact area between the one-side transparent electrode and the collector electrode 7 and the contact area between the other-surface lower transparent electrode and the collector electrode 8 are increased, and the contact resistance is lowered.
　上層透明電極９ａの幅は、集電極７を完全に覆うために集電極７の幅より数μｍ～数十μｍ程度広くすることが好ましい。また、上層透明電極９ｂの幅は、集電極８を完全に覆うために集電極８の幅より数μｍ～数十μｍ程度広くすることが好ましい。実施の形態１では、グリッド電極７ａ上の上層透明電極９ａの幅は略４０μｍとし、グリッド電極８ａ上の上層透明電極９ｂの幅は略４０μｍとした。 It is preferable that the width of the upper transparent electrode 9a is made several μm to several tens μm wider than the width of the collector electrode 7 in order to completely cover the collector electrode 7. Further, the width of the upper transparent electrode 9b is preferably set to be several μm to several tens μm wider than the width of the collector electrode 8 in order to completely cover the collector electrode 8. In the first embodiment, the width of the upper transparent electrode 9a on the grid electrode 7a is approximately 40 μm, and the width of the upper transparent electrode 9b on the grid electrode 8a is approximately 40 μm.
　また、上層透明電極９を形成する方法として、一旦基板全面に透明電極を形成した後に、集電極領域以外の透明電極を、エッチングペーストを用いて除去する方法を用いてもよい。 Further, as a method for forming the upper transparent electrode 9, a method may be used in which after the transparent electrode is once formed on the entire surface of the substrate, the transparent electrode other than the collecting electrode region is removed using an etching paste.
　以上の工程を実施することにより、図１に示す太陽電池セル１が得られる。 By performing the above steps, the solar cell 1 shown in FIG. 1 is obtained.
　上述したように、実施の形態１にかかる太陽電池セル１は、下層透明電極６ａおよび集電極７の両方に電気的に接続された上層透明電極９ａを備えることにより、一面側透明電極と集電極７との接触面積を広く確保できる。また、下層透明電極６ｂおよび集電極８の両方に電気的に接続された上層透明電極９ｂと備えることにより、他面側透明電極と集電極８との接触面積を広く確保できる。これにより、一面側透明電極と集電極７との間の接触抵抗および他面側下層透明電極と集電極８との間の接触抵抗が低下して寄生抵抗が低下し、発電効率、曲線因子が向上する。 As described above, the solar cell 1 according to the first embodiment includes the upper transparent electrode 9a electrically connected to both the lower transparent electrode 6a and the collector electrode 7, whereby the one-side transparent electrode and the collector electrode are provided. 7 can be secured widely. Further, by providing the upper transparent electrode 9b electrically connected to both the lower transparent electrode 6b and the collector electrode 8, a wide contact area between the other-side transparent electrode and the collector electrode 8 can be secured. As a result, the contact resistance between the one-side transparent electrode and the collector electrode 7 and the contact resistance between the other-surface lower transparent electrode and the collector electrode 8 are reduced to reduce the parasitic resistance. improves.
　また、実施の形態１によれば、集電極７（または８）の幅が狭い場合でも一面側透明電極と集電極７との接触面積および他面側透明電極と集電極８との接触面積を広く確保できるため、寄生抵抗が低下し、発電効率、曲線因子が向上する。 Further, according to the first embodiment, even when the width of the collecting electrode 7 (or 8) is narrow, the contact area between the one-side transparent electrode and the collecting electrode 7 and the contact area between the other-side transparent electrode and the collecting electrode 8 are reduced. Since it can be secured widely, the parasitic resistance is reduced, and the power generation efficiency and the fill factor are improved.
　また、実施の形態１によれば、下層透明電極６ａおよび下層透明電極６ｂの光透過性を高くするためにＩＴＯ等の酸素濃度を増加させて電気抵抗率が上昇した場合でも、上層透明電極９を備えることにより、光照射により発生した電荷の収集効率を向上させ、光電変換効率を向上させることができる。 In addition, according to the first embodiment, even when the electrical resistivity is increased by increasing the oxygen concentration of ITO or the like in order to increase the light transmittance of the lower transparent electrode 6a and the lower transparent electrode 6b, the upper transparent electrode 9 Thus, the collection efficiency of charges generated by light irradiation can be improved, and the photoelectric conversion efficiency can be improved.
　したがって、実施の形態１によれば、曲線因子および光電変換効率に優れた太陽電池セルが得られる。 Therefore, according to the first embodiment, a solar battery cell having excellent fill factor and photoelectric conversion efficiency can be obtained.
　なお、上述した本発明の効果を得るためには、上層透明電極９は集電極７、８の一部とのみ電気的に接触した構造とされてもよい。ただし、本発明の効果をより有効に得るためには、上層透明電極９と集電極７、８との接触面積は広くすることが好ましい。 In addition, in order to obtain the above-described effects of the present invention, the upper transparent electrode 9 may be configured to be in electrical contact with only a part of the collector electrodes 7 and 8. However, in order to obtain the effect of the present invention more effectively, it is preferable to increase the contact area between the upper transparent electrode 9 and the collector electrodes 7 and 8.
　また、上層透明電極９ａの電気抵抗が、下層透明電極６ａの電気抵抗よりも低いことが好ましい。これにより、下層透明電極６ａに到達した電荷の殆どが、集電極７との接触面積（導通面積）が広い上層透明電極９ａを通って集電極７に流れ、電荷が効率良く集電極７に収集される。同様に、上層透明電極９ｂの電気抵抗が、下層透明電極６ｂの電気抵抗よりも低いことが好ましい。これにより、下層透明電極６ｂに到達した電荷の殆どが、集電極８との接触面積（導通面積）が広い上層透明電極９ｂを通って集電極８に流れ、電荷が効率良く集電極８に収集される。 Moreover, it is preferable that the electrical resistance of the upper transparent electrode 9a is lower than the electrical resistance of the lower transparent electrode 6a. As a result, most of the charges reaching the lower transparent electrode 6a flow to the collector electrode 7 through the upper transparent electrode 9a having a large contact area (conduction area) with the collector electrode 7, and the charges are efficiently collected in the collector electrode 7. Is done. Similarly, the electrical resistance of the upper transparent electrode 9b is preferably lower than the electrical resistance of the lower transparent electrode 6b. As a result, most of the charges reaching the lower transparent electrode 6b flow to the collector electrode 8 through the upper transparent electrode 9b having a large contact area (conduction area) with the collector electrode 8, and the charges are efficiently collected in the collector electrode 8. Is done.
　また、上層透明電極９の結晶性を下層透明電極６の結晶性より高くすることにより、上層透明電極９の電気抵抗を下層透明電極６の電気抵抗よりも低減してもよい。これにより、ｎ型結晶珪素基板２で発生した電荷の殆どが下層透明電極６から上層透明電極９を通って集電極７（集電極８）に流れ、電荷が効率良く集電極７（集電極８）に収集される。 Alternatively, the electrical resistance of the upper transparent electrode 9 may be made lower than the electrical resistance of the lower transparent electrode 6 by making the crystallinity of the upper transparent electrode 9 higher than that of the lower transparent electrode 6. As a result, most of the charges generated in the n-type crystalline silicon substrate 2 flow from the lower transparent electrode 6 through the upper transparent electrode 9 to the collector electrode 7 (collector electrode 8), and the charges are efficiently collected. ) Collected.
実施の形態２．
　図５は、本発明の実施の形態２にかかる光電変換装置である太陽電池セル１０１の概略構成を模式的に示す斜視図である。この太陽電池セル１０１は、光電変換層であり両側の表面が凹凸加工されたｎ型結晶珪素基板１０２の一面側の表面に厚さが略５ｎｍのｉ型非晶質珪素層１０３ａが形成され、他面側の表面に厚さが略５ｎｍのｉ型非晶質珪素層１０３ｂが形成されている。ｎ型結晶珪素基板１０２は、比抵抗が１～１０Ω・ｃｍ、結晶配向が＜１００＞、厚さが５０μｍ以上３００μｍ以下の珪素基板である。なお、図５においては簡略化のためｎ型結晶珪素基板２の表面の凹凸構造の図示を省略している。ｉ型非晶質珪素層１０３ａ上には、厚さが略５ｎｍのｐ型非晶質珪素層１０４が形成され、ｉ型非晶質珪素層１０３ｂ上には厚さが略５ｎｍのｎ型非晶質珪素層１０５が形成されている。 Embodiment 2. FIG.
FIG. 5: is a perspective view which shows typically schematic structure of the photovoltaic cell 101 which is a photoelectric conversion apparatus concerning Embodiment 2 of this invention. This solar cell 101 is a photoelectric conversion layer, and an i-type amorphous silicon layer 103a having a thickness of about 5 nm is formed on the surface of one surface side of an n-type crystalline silicon substrate 102 whose surfaces on both sides are processed to be uneven. An i-type amorphous silicon layer 103b having a thickness of about 5 nm is formed on the surface on the other side. The n-type crystalline silicon substrate 102 is a silicon substrate having a specific resistance of 1 to 10 Ω · cm, a crystal orientation of <100>, and a thickness of 50 μm to 300 μm. In FIG. 5, for the sake of simplicity, the illustration of the concavo-convex structure on the surface of the n-type crystalline silicon substrate 2 is omitted. A p-type amorphous silicon layer 104 having a thickness of about 5 nm is formed on the i-type amorphous silicon layer 103a, and an n-type non-layer having a thickness of about 5 nm is formed on the i-type amorphous silicon layer 103b. A crystalline silicon layer 105 is formed.
　ｐ型非晶質珪素層１０４上には厚さが略７０ｎｍの下層透明電極１０６ａが形成され、ｎ型非晶質珪素層１０５上には厚さが略７０ｎｍの下層透明電極１０６ｂが形成されている。下層透明電極１０６ａ上には銀（Ａｇ）からなる厚さが略６０μｍの集電極１０７が形成され、下層透明電極１０６ｂ上には銀（Ａｇ）からなる厚さが略６０μｍの集電極１０８が形成されている。なお、以下においては下層透明電極１０６ａと下層透明電極１０６ｂとを総称して下層透明電極１０６と呼ぶ場合がある。 A lower transparent electrode 106a having a thickness of approximately 70 nm is formed on the p-type amorphous silicon layer 104, and a lower transparent electrode 106b having a thickness of approximately 70 nm is formed on the n-type amorphous silicon layer 105. Yes. A collector electrode 107 made of silver (Ag) with a thickness of about 60 μm is formed on the lower transparent electrode 106a, and a collector electrode 108 made of silver (Ag) with a thickness of about 60 μm is formed on the lower transparent electrode 106b. Has been. Hereinafter, the lower transparent electrode 106a and the lower transparent electrode 106b may be collectively referred to as the lower transparent electrode 106.
　集電極１０７は、幅が略２０μｍ、厚さが略６０μｍであり一定のピッチで互いに略平行に配置された複数のグリッド電極１０７ａと、幅が略１ｍｍでありグリッド電極１０７ａに交差して電気的に接続されたバス電極１０７ｂとから構成されている。集電極１０８は、幅が略２０μｍ、厚さが略６０μｍであり一定のピッチで互いに略平行に配置された複数のグリッド電極１０８ａと、幅が略１ｍｍでありグリッド電極１０８ａに交差して電気的に接続されたバス電極１０８ｂとから構成されている。 The collector electrode 107 has a width of about 20 μm, a thickness of about 60 μm, and a plurality of grid electrodes 107 a arranged in parallel with each other at a constant pitch, and a width of about 1 mm, which intersects the grid electrodes 107 a electrically. The bus electrode 107b is connected to the bus electrode 107b. The collector electrode 108 has a width of approximately 20 μm, a thickness of approximately 60 μm, and a plurality of grid electrodes 108 a arranged substantially in parallel with each other at a constant pitch, and a width of approximately 1 mm, which intersects the grid electrodes 108 a electrically. The bus electrode 108b is connected to the bus electrode 108b.
　そして、下層透明電極１０６ａと集電極１０７を覆うように上層透明電極１０９ａが形成され、下層透明電極１０６ｂと集電極１０８を覆うように上層透明電極１０９ｂが形成されている。すなわち、下層透明電極１０６ａは集電極１０７と上層透明電極１０９ａとにより外部側の表面全体を覆われている。下層透明電極１０６ｂは集電極１０８と上層透明電極１０９ｂとにより外部側の表面全体を覆われている。なお、以下においては上層透明電極１０９ａと上層透明電極１０９ｂとを総称して上層透明電極１０９と呼ぶ場合がある。また、下層透明電極１０６ａと上層透明電極１０９ａとを総称して一面側透明電極と、下層透明電極１０６ｂと上層透明電極１０９ｂとを総称して他面側透明電極と呼ぶ場合がある。このとき上層透明電極１０９ａ、１０９ｂは、バス電極１０７ｂ、１０８ｂそれぞれの上には形成しなくてもよい。 An upper transparent electrode 109a is formed so as to cover the lower transparent electrode 106a and the collecting electrode 107, and an upper transparent electrode 109b is formed so as to cover the lower transparent electrode 106b and the collecting electrode 108. That is, the lower transparent electrode 106a is entirely covered with the collector electrode 107 and the upper transparent electrode 109a. The lower transparent electrode 106b is entirely covered with the collector electrode 108 and the upper transparent electrode 109b. Hereinafter, the upper transparent electrode 109a and the upper transparent electrode 109b may be collectively referred to as the upper transparent electrode 109. Further, the lower transparent electrode 106a and the upper transparent electrode 109a may be collectively referred to as one side transparent electrode, and the lower transparent electrode 106b and the upper transparent electrode 109b may be collectively referred to as other side transparent electrodes. At this time, the upper transparent electrodes 109a and 109b may not be formed on the bus electrodes 107b and 108b, respectively.
　下層透明電極１０６ａと集電極１０７との両方に電気的に接続された上層透明電極１０９ａを備えることにより、太陽電池セル１０１では一面側透明電極と集電極１０７との接触面積を、従来の太陽電池セルに比べて広く確保できる。また、下層透明電極１０６ｂと集電極１０８との両方に電気的に接続された上層透明電極１０９ｂを備えることにより、太陽電池セル１０１では他面側透明電極と集電極１０８との接触面積を、従来の太陽電池セルに比べて広く確保できる。太陽電池セル１０１では、透明電極と集電極間との接触面積が増加することにより、透明電極と集電極との間の接触抵抗が低下して寄生抵抗が低下し、発電効率、曲線因子が向上する。 By providing the upper transparent electrode 109a electrically connected to both the lower transparent electrode 106a and the collector electrode 107, the contact area between the one-side transparent electrode and the collector electrode 107 in the solar battery cell 101 can be reduced. It can be secured widely compared to the cell. Further, by providing the upper transparent electrode 109b electrically connected to both the lower transparent electrode 106b and the collector electrode 108, the solar cell 101 has a conventional contact area between the transparent electrode on the other side and the collector electrode 108. It is possible to secure a wider area than that of solar cells. In the solar battery cell 101, the contact area between the transparent electrode and the collector electrode is increased, so that the contact resistance between the transparent electrode and the collector electrode is reduced and the parasitic resistance is lowered, and the power generation efficiency and the fill factor are improved. To do.
　実施の形態２にかかる太陽電池セル１０１においては、図２で説明した実施の形態１の場合と同様の理由により、電荷は従来の太陽電池セルと比較して広い領域、すなわち集電極１０７と一面側透明電極（下層透明電極１０６ａ、上層透明電極１０９ａ）とが接触している接触面を通って一面側透明電極から集電極１０７に到達する。また、太陽電池セル１０１においては、図２で説明した実施の形態１の場合と同様の理由により、電荷は従来の太陽電池セルと比較して広い領域、すなわち集電極１０８と他面側透明電極（下層透明電極１０６ｂ、上層透明電極１０９ｂ）とが接触している接触面を通って他面側透明電極から集電極１０８に到達する。 In the solar cell 101 according to the second embodiment, for the same reason as in the first embodiment described with reference to FIG. 2, the charge is larger than that of the conventional solar cell, that is, the collector electrode 107 and one surface. The collector electrode 107 reaches the collector electrode 107 from the one-side transparent electrode through the contact surface with which the side transparent electrodes (lower transparent electrode 106a, upper transparent electrode 109a) are in contact. Further, in the solar cell 101, for the same reason as in the case of the first embodiment described in FIG. 2, the electric charge is wider than that of the conventional solar cell, that is, the collector electrode 108 and the other surface side transparent electrode. The collector electrode 108 is reached from the other transparent electrode through the contact surface with which the lower transparent electrode 106b and the upper transparent electrode 109b are in contact.
　実施の形態２にかかる太陽電池セル１０１について光電変換特性を調べたところ、図３で説明した実施の形態１の場合と同様の結果となり、実施の形態１の場合と同様の理由により、従来の太陽電池セルに比べて曲線因子が向上する。すなわち、太陽電池セル１０１の曲線因子の向上は、実施の形態１の場合と同様であり、上層透明電極１０９ａを備えることにより下層透明電極１０６ａから集電極１０７への導通面積が増加して一面側透明電極と集電極１０７間の接触抵抗が低減したこと、および上層透明電極１０９ｂを備えることにより下層透明電極１０６ｂから集電極１０８への導通面積が増加して他面側透明電極と集電極１０８間の接触抵抗が低減したことに因るものである。したがって、実施の形態２にかかる太陽電池セル１０１の光電変換効率は、従来の太陽電池セルに比べて向上していることが明らかとなった。 When the photoelectric conversion characteristics of the solar battery cell 101 according to the second embodiment were examined, the results were the same as in the case of the first embodiment described with reference to FIG. The curve factor is improved as compared with the solar battery cell. That is, the improvement of the fill factor of the solar battery cell 101 is the same as in the case of the first embodiment. By providing the upper transparent electrode 109a, the conduction area from the lower transparent electrode 106a to the collecting electrode 107 is increased and the one surface side is increased. The contact resistance between the transparent electrode and the collector electrode 107 is reduced, and the provision of the upper transparent electrode 109b increases the conduction area from the lower transparent electrode 106b to the collector electrode 108, thereby increasing the distance between the other-side transparent electrode and the collector electrode 108. This is because the contact resistance is reduced. Therefore, it became clear that the photoelectric conversion efficiency of the solar battery cell 101 according to the second embodiment is improved as compared with the conventional solar battery cell.
　次に、上記のように構成された実施の形態２にかかる太陽電池セル１０１の製造方法について図６－１～図６－６を参照して説明する。図６－１～図６－６は、実施の形態２にかかる太陽電池セル１０１の製造方法の手順の一例を示す断面図である。 Next, a method for manufacturing the solar battery cell 101 according to the second embodiment configured as described above will be described with reference to FIGS. 6-1 to 6-6. FIGS. 6-1 to 6-6 are cross-sectional views illustrating an example of the procedure of the manufacturing method of the solar battery cell 101 according to the second embodiment.
　まず、図６－１に示すように、ｎ型結晶珪素基板１０２の表面にテクスチャと呼ばれる凹凸構造を形成する。テクスチャは太陽電池セルに入射する光の反射を低減し、ｎ型結晶珪素基板１０２内における光散乱を促進する。凹凸構造の形成には、酸性またはアルカリ性のエッチング溶液を用いたｎ型結晶珪素基板１０２の表面のウエットエッチングを用いることができる。 First, as shown in FIG. 6A, an uneven structure called texture is formed on the surface of the n-type crystalline silicon substrate 102. The texture reduces reflection of light incident on the solar battery cell and promotes light scattering in the n-type crystalline silicon substrate 102. For the formation of the concavo-convex structure, wet etching of the surface of the n-type crystalline silicon substrate 102 using an acidic or alkaline etching solution can be used.
　また、凹凸構造の形成前に、ｎ型結晶珪素基板１０２の表面のダメージ層を除去する工程を実施してもよい。また、これに加えてダメージ層除去工程後に、基板内不純物のゲッタリング処理を施すことが太陽電池セルの性能向上には好ましい。ゲッタリング処理としては、例えばリン拡散処理などを用いる。また、凹凸構造の形成は、ｎ型結晶珪素基板２において太陽電池セル１０１の光入射側となる面だけに施してもよい。 Further, a step of removing the damaged layer on the surface of the n-type crystalline silicon substrate 102 may be performed before the formation of the concavo-convex structure. In addition to this, it is preferable to perform gettering treatment of impurities in the substrate after the damaged layer removing step in order to improve the performance of the solar battery cell. As the gettering process, for example, a phosphorus diffusion process or the like is used. In addition, the uneven structure may be formed only on the surface of the n-type crystalline silicon substrate 2 on the light incident side of the solar battery cell 101.
　つぎに、図６－２に示すように、ｎ型結晶珪素基板１０２の一面側にｉ型非晶質珪素層１０３ａとｐ型非晶質珪素層１０４とをこの順番でＣＶＤ法を用いて形成する。ｉ型非晶質珪素層１０３ａおよびｐ型非晶質珪素層１０４の層厚は、それぞれ略５ｎｍである。なお、実施の形態２ではｉ型非晶質珪素層１０３ａおよびｐ型非晶質珪素層１０４の層厚を略５ｎｍとしたが、層の形成条件によってはたとえば５ｎｍ以上１０ｎｍ以下の範囲の層厚でも構わない。 Next, as shown in FIG. 6B, an i-type amorphous silicon layer 103a and a p-type amorphous silicon layer 104 are formed in this order on one surface side of the n-type crystalline silicon substrate 102 using the CVD method. To do. The i-type amorphous silicon layer 103a and the p-type amorphous silicon layer 104 each have a thickness of about 5 nm. In the second embodiment, the i-type amorphous silicon layer 103a and the p-type amorphous silicon layer 104 have a thickness of about 5 nm. However, depending on the layer formation conditions, the layer thickness is, for example, in the range of 5 nm to 10 nm. It doesn't matter.
　ＣＶＤ法としては、たとえばプラズマＣＶＤ法、熱ＣＶＤ法などを用いることが好ましい。光電変換層であるｎ型結晶珪素基板２に対して十分な内蔵電界を発生させるためには、ｐ型非晶質珪素層１０４のバンドギャップは１．７ｅＶ以上、活性化エネルギーは０．４ｅＶ以下であることが必要である。なおｉ型非晶質珪素層１０３ａの代わりに、ｉ型非晶質炭化珪素層、ｉ型非晶質酸化珪素層またはこれらを積層した多層膜を用いてもよい。また、ｐ型非晶質珪素層１０４の代わりにｐ型非晶質炭化珪素層、ｐ型非晶質酸化珪素層、ｐ型微結晶珪素層またはこれらを積層した多層膜などを用いてもよい。 As the CVD method, for example, a plasma CVD method or a thermal CVD method is preferably used. In order to generate a sufficient built-in electric field for the n-type crystalline silicon substrate 2 which is a photoelectric conversion layer, the band gap of the p-type amorphous silicon layer 104 is 1.7 eV or more, and the activation energy is 0.4 eV or less. It is necessary to be. Note that an i-type amorphous silicon carbide layer, an i-type amorphous silicon oxide layer, or a multilayer film in which these layers are stacked may be used instead of the i-type amorphous silicon layer 103a. Instead of the p-type amorphous silicon layer 104, a p-type amorphous silicon carbide layer, a p-type amorphous silicon oxide layer, a p-type microcrystalline silicon layer, or a multilayer film in which these layers are stacked may be used. .
　つぎに、図６－３に示すように、ｎ型結晶珪素基板１０２の他面側にｉ型非晶質珪素層１０３ｂとｎ型非晶質珪素層１０５とをこの順番でＣＶＤ法を用いて形成する。ｉ型非晶質珪素層１０３ｂおよびｎ型非晶質珪素層１０５の層厚は、それぞれ略５ｎｍである。なお、実施の形態２ではｉ型非晶質珪素層１０３ｂおよびｎ型非晶質珪素層１０５の層厚を略５ｎｍとしたが、層の形成条件によってはたとえば５ｎｍ以上２０ｎｍ以下の範囲の層厚でも構わない。 Next, as shown in FIG. 6-3, an i-type amorphous silicon layer 103b and an n-type amorphous silicon layer 105 are formed in this order on the other surface side of the n-type crystalline silicon substrate 102 using the CVD method. Form. The thicknesses of the i-type amorphous silicon layer 103b and the n-type amorphous silicon layer 105 are approximately 5 nm, respectively. In the second embodiment, the i-type amorphous silicon layer 103b and the n-type amorphous silicon layer 105 have a thickness of about 5 nm. However, depending on the layer formation conditions, for example, a layer thickness in the range of 5 nm to 20 nm. It doesn't matter.
　ＣＶＤ法としては、たとえばプラズマＣＶＤ法、熱ＣＶＤ法などを用いることが好ましい。光電変換層であるｎ型結晶珪素基板１０２に対して十分な内蔵電界を発生させるためには、ｎ型非晶質珪素層１０５のバンドギャップは１．７ｅＶ以上、活性化エネルギーは０．３ｅＶ以下であることが必要である。なおｉ型非晶質珪素層１０３ｂの代わりに、ｉ型非晶質炭化珪素層、ｉ型非晶質酸化珪素層またはこれらを積層した多層膜を用いてもよい。また、ｎ型非晶質珪素層１０５の代わりにｎ型非晶質炭化珪素層、ｎ型非晶質酸化珪素層、ｎ型微結晶珪素層またはこれらを積層した多層膜などを用いてもよい。 As the CVD method, for example, a plasma CVD method or a thermal CVD method is preferably used. In order to generate a sufficient built-in electric field for the n-type crystalline silicon substrate 102 which is a photoelectric conversion layer, the band gap of the n-type amorphous silicon layer 105 is 1.7 eV or more and the activation energy is 0.3 eV or less. It is necessary to be. Instead of the i-type amorphous silicon layer 103b, an i-type amorphous silicon carbide layer, an i-type amorphous silicon oxide layer, or a multilayer film in which these layers are stacked may be used. Instead of the n-type amorphous silicon layer 105, an n-type amorphous silicon carbide layer, an n-type amorphous silicon oxide layer, an n-type microcrystalline silicon layer, or a multilayer film in which these layers are stacked may be used. .
　また、ｉ型非晶質珪素層１０３ｂおよびｎ型非晶質珪素層１０５の形成後、ｉ型非晶質珪素層１０３ａおよびｉ型非晶質珪素層１０３ｂと、ｎ型結晶珪素基板１０２との界面欠陥低減のために、不活性ガスまたは不活性ガスで希釈した水素ガス中で熱アニール処理を施してもよい。アニール温度は２００℃以下が好ましい。また、ｉ型非晶質珪素層１０３ａおよびｐ型非晶質珪素層１０４と、ｉ型非晶質珪素層１０３ｂおよびｎ型非晶質珪素層１０５との形成順序を反対にしてもよい。 Further, after the formation of the i-type amorphous silicon layer 103b and the n-type amorphous silicon layer 105, the i-type amorphous silicon layer 103a and the i-type amorphous silicon layer 103b and the n-type crystalline silicon substrate 102 In order to reduce interface defects, thermal annealing treatment may be performed in an inert gas or hydrogen gas diluted with an inert gas. The annealing temperature is preferably 200 ° C. or lower. Further, the formation order of the i-type amorphous silicon layer 103a and the p-type amorphous silicon layer 104, and the i-type amorphous silicon layer 103b and the n-type amorphous silicon layer 105 may be reversed.
　つぎに、図６－４に示すように、ｐ型非晶質珪素層１０４上に下層透明電極１０６ａを、ｎ型非晶質珪素層１０５上に下層透明電極１０６ｂをスパッタリング法または蒸着法を用いて形成する。下層透明電極１０６ａおよび下層透明電極１０６ｂの透明電極材料としては、ＩＴＯまたは酸化インジウム（Ｉｎ２Ｏ３：Indium　Oxide）を用いる。下層透明電極１０６ａおよび下層透明電極１０６ｂの膜厚は、反射率低減の観点から略７０ｎｍが好ましい。また、透明電極の電気抵抗率は低いことが望ましいが、導電性を担うキャリア密度が高いと透明電極での光吸収率が増加する。このため、透明電極として用いる材料は高キャリア移動度を実現できなければならない。７０ｎｍの層厚で十分低い電気抵抗率を達成するために、キャリア移動度はたとえば１００ｃｍ２／Ｖｓ以上が好ましい。なお、下層透明電極材料としてアルミニウム（Ａｌ）やガリウム（Ｇａ）などを添加した酸化亜鉛（ＺｎＯ：Zinc　Oxide）を用いてもよい。 Next, as shown in FIG. 6-4, the lower transparent electrode 106a is formed on the p-type amorphous silicon layer 104 and the lower transparent electrode 106b is formed on the n-type amorphous silicon layer 105 by sputtering or vapor deposition. Form. As a transparent electrode material of the lower transparent electrode 106a and the lower transparent electrode 106b, ITO or indium oxide (In 2 O 3 : Indium Oxide) is used. The film thickness of the lower transparent electrode 106a and the lower transparent electrode 106b is preferably about 70 nm from the viewpoint of reducing the reflectance. Moreover, it is desirable that the electrical resistivity of the transparent electrode is low, but if the carrier density responsible for conductivity is high, the light absorption rate at the transparent electrode increases. For this reason, the material used as a transparent electrode must be able to realize high carrier mobility. In order to achieve a sufficiently low electric resistivity with a layer thickness of 70 nm, the carrier mobility is preferably 100 cm 2 / Vs or more, for example. In addition, you may use the zinc oxide (ZnO: Zinc Oxide) which added aluminum (Al), gallium (Ga), etc. as a lower layer transparent electrode material.
　つぎに、図６－５に示すように、下層透明電極１０６ａ上にＡｇで構成される集電極１０７を、下層透明電極１０６ｂ上にＡｇで構成される集電極１０８をスクリーン印刷法で形成する。図６－５においてはグリッド電極１０７ａおよびグリッド電極１０８ａのみを示している。集電極１０７を構成するグリッド電極１０７ａおよび集電極１０８を構成するグリッド電極１０８ａの幅は、太陽電池セル１０１に入射する光の遮光を抑制するために狭いほど好ましい。しかし、グリッド電極１０７ａおよびグリッド電極１０８ａの幅が狭い場合には、断面積が小さくなるために電気抵抗が増加する。したがって、断面積を大きくして電気抵抗を低減するために、グリッド電極１０７ａおよびグリッド電極１０８ａは、幅が狭く、層厚が大きいことが好ましい。実施の形態２では、グリッド電極１０７ａおよびグリッド電極１０８ａの幅を略２０μｍ、層厚を略６０μｍとした。なお、集電極１０７および集電極１０８は、スクリーン印刷の他に、メッキ法などで形成してもよい。また、集電極１０７および集電極１０８の材料として銅（Ｃｕ）を用いてもよい。集電極１０７および集電極１０８の印刷後、２００℃以下で焼成を行う。 Next, as shown in FIG. 6-5, the collector electrode 107 made of Ag is formed on the lower transparent electrode 106a, and the collector electrode 108 made of Ag is formed on the lower transparent electrode 106b by screen printing. In FIG. 6-5, only the grid electrode 107a and the grid electrode 108a are shown. The widths of the grid electrode 107 a constituting the collector electrode 107 and the grid electrode 108 a constituting the collector electrode 108 are preferably as narrow as possible in order to prevent light incident on the solar battery cell 101 from being blocked. However, when the widths of the grid electrode 107a and the grid electrode 108a are narrow, the cross-sectional area becomes small and the electrical resistance increases. Therefore, in order to increase the cross-sectional area and reduce the electrical resistance, it is preferable that the grid electrode 107a and the grid electrode 108a have a narrow width and a large layer thickness. In the second embodiment, the width of the grid electrode 107a and the grid electrode 108a is approximately 20 μm, and the layer thickness is approximately 60 μm. The collecting electrode 107 and the collecting electrode 108 may be formed by a plating method in addition to screen printing. Further, copper (Cu) may be used as a material for the collector electrode 107 and the collector electrode 108. After the collector electrode 107 and the collector electrode 108 are printed, baking is performed at 200 ° C. or lower.
　つぎに、図６－６に示すように、下層透明電極１０６ａ上と集電極７との全体を覆うように上層透明電極１０９ａを集電極１０７の形状に沿った形状にスパッタリング法または蒸着法で形成する。また、下層透明電極１０６ｂ上と集電極１０８との全体を覆うように上層透明電極１０９ｂを集電極１０８の形状に沿った形状にスパッタリング法または蒸着法で形成する。上層透明電極１０９ａおよび上層透明電極１０９ｂの透明電極材料としては、ＩＴＯを用いる。また、上層透明電極１０９ａおよび上層透明電極１０９ｂの透明電極材料として酸化インジウム（Ｉｎ２Ｏ３：Indium　Oxide）やアルミニウム（Ａｌ）やガリウム（Ｇａ）などを添加した酸化亜鉛（ＺｎＯ：Zinc　Oxide）を用いてもよい。なお、集電極１０７および集電極１０８がそれぞれ上層透明電極１０９ａ、１０９ｂで覆われることで集電極１０７および集電極１０８を保護でき、信頼性が向上する、という利点もある。 Next, as shown in FIG. 6-6, the upper transparent electrode 109a is formed in a shape along the shape of the collector electrode 107 by sputtering or vapor deposition so as to cover the lower transparent electrode 106a and the collector electrode 7 as a whole. To do. In addition, the upper transparent electrode 109b is formed in a shape in accordance with the shape of the collector electrode 108 by sputtering or vapor deposition so as to cover the lower transparent electrode 106b and the entire collector electrode 108. ITO is used as a transparent electrode material for the upper transparent electrode 109a and the upper transparent electrode 109b. Further, zinc oxide (ZnO: Zinc Oxide) to which indium oxide (In 2 O 3 : Indium Oxide), aluminum (Al), gallium (Ga) or the like is added is used as a transparent electrode material for the upper transparent electrode 109a and the upper transparent electrode 109b. It may be used. The collector electrode 107 and the collector electrode 108 are covered with the upper transparent electrodes 109a and 109b, respectively, whereby the collector electrode 107 and the collector electrode 108 can be protected, and there is an advantage that reliability is improved.
　また、上層透明電極１０９ａの層厚は下層透明電極１０６ａより厚くし、上層透明電極１０９ｂの層厚は下層透明電極１０６ｂより厚くすることが好ましい。これにより、上層透明電極１０９ａ、１０９ｂの抵抗が下層透明電極１０６ａ、１０６ｂに比べて低くなる。そして光電変換層であるｎ型結晶珪素基板１０２で発生した電荷の多くは上層透明電極１０９ａを通って集電極１０７へ、上層透明電極１０９ｂを通って集電極１０８へ向かって導通し、集電極１０７と上層透明電極１０９ａの接触面から集電極１０７に、集電極１０８と上層透明電極１０９ｂの接触面から集電極１０８に到達する。結果として、一面側透明電極と集電極１０７との間の接触面積および他面側下層透明電極と集電極１０８との間の接触面積が増加し、接触抵抗が低下する。 Further, it is preferable that the upper transparent electrode 109a is thicker than the lower transparent electrode 106a, and the upper transparent electrode 109b is thicker than the lower transparent electrode 106b. Thereby, the resistance of the upper transparent electrodes 109a and 109b is lower than that of the lower transparent electrodes 106a and 106b. Most of the charges generated in the n-type crystalline silicon substrate 102 which is a photoelectric conversion layer are conducted to the collector electrode 107 through the upper transparent electrode 109a and to the collector electrode 108 through the upper transparent electrode 109b. From the contact surface of the upper transparent electrode 109a to the collector electrode 107 and from the contact surface of the collector electrode 108 and the upper transparent electrode 109b to the collector electrode 108. As a result, the contact area between the one-side transparent electrode and the collector electrode 107 and the contact area between the other-surface lower transparent electrode and the collector electrode 108 are increased, and the contact resistance is lowered.
　上層透明電極１０９ａの幅は、集電極１０７を完全に覆うために集電極１０７の幅より数μｍ～数十μｍ程度広くすることが好ましい。また、上層透明電極１０９ｂの幅は、集電極１０８を完全に覆うために集電極１０８の幅より数μｍ～数十μｍ程度広くすることが好ましい。実施の形態２では、グリッド電極１０７ａ上の上層透明電極１０９ａの幅は略４０μｍとし、グリッド電極１０８ａ上の上層透明電極１０９ｂの幅は略４０μｍとした。 It is preferable that the width of the upper transparent electrode 109a be several μm to several tens μm wider than the width of the collector electrode 107 in order to completely cover the collector electrode 107. In addition, the width of the upper transparent electrode 109b is preferably set to be several μm to several tens μm wider than the width of the collector electrode 108 in order to completely cover the collector electrode 108. In the second embodiment, the width of the upper transparent electrode 109a on the grid electrode 107a is approximately 40 μm, and the width of the upper transparent electrode 109b on the grid electrode 108a is approximately 40 μm.
　また、集電極１０７の側面まで十分に電荷を導くため、上層透明電極１０９ａの電気抵抗率は下層透明電極１０６ａより低くする。集電極１０８の側面まで十分に電荷を導くため、上層透明電極１０９ｂの電気抵抗率は下層透明電極１０６ｂより低くする。また、下層透明電極１０６の場合と同様の理由により、キャリア移動度は１００ｃｍ２／Ｖｓ以上が好ましい。このために、上層透明電極１０９の結晶性を下層透明電極１０６の結晶性より高くしてもよい。 In addition, in order to sufficiently introduce charges to the side surface of the collector electrode 107, the electrical resistivity of the upper transparent electrode 109a is set lower than that of the lower transparent electrode 106a. In order to sufficiently guide the charge to the side surface of the collecting electrode 108, the electrical resistivity of the upper transparent electrode 109b is set lower than that of the lower transparent electrode 106b. For the same reason as in the case of the lower transparent electrode 106, the carrier mobility is preferably 100 cm 2 / Vs or more. For this reason, the crystallinity of the upper transparent electrode 109 may be higher than the crystallinity of the lower transparent electrode 106.
　以上の工程を実施することにより、図５に示す太陽電池セル１０１が得られる。 The solar cell 101 shown in FIG. 5 is obtained by performing the above steps.
　上述したように、実施の形態２にかかる太陽電池セル１０１は、下層透明電極１０６ａおよび集電極１０７の両方に電気的に接続された上層透明電極１０９ａを備え、下層透明電極１０６ａ上における集電極１０７の形成領域以外の領域の全てが上層透明電極１０９ａで覆われていることにより、一面側透明電極と集電極１０７との接触面積をより広く確保できる。また、下層透明電極１０６ｂおよび集電極１０８の両方に電気的に接続された上層透明電極１０９ｂと備え、下層透明電極１０６ｂ上における集電極１０８の形成領域以外の領域の全てが上層透明電極１０９ｂで覆われていることにより、他面側透明電極と集電極１０８との接触面積をより広く確保できる。これにより、一面側透明電極と集電極１０７との間の接触抵抗および他面側下層透明電極と集電極１０８との間の接触抵抗が低下して寄生抵抗が低下し、発電効率、曲線因子が向上する。 As described above, the solar cell 101 according to the second embodiment includes the upper transparent electrode 109a electrically connected to both the lower transparent electrode 106a and the collector electrode 107, and the collector electrode 107 on the lower transparent electrode 106a. Since the entire region other than the formation region of the first electrode is covered with the upper transparent electrode 109a, a wider contact area between the one-side transparent electrode and the collector electrode 107 can be secured. The upper transparent electrode 109b is electrically connected to both the lower transparent electrode 106b and the collector electrode 108, and the entire area of the lower transparent electrode 106b other than the region where the collector electrode 108 is formed is covered with the upper transparent electrode 109b. As a result, a wider contact area between the transparent electrode on the other side and the collector electrode 108 can be secured. As a result, the contact resistance between the one-surface side transparent electrode and the collector electrode 107 and the contact resistance between the other-surface-side lower transparent electrode and the collector electrode 108 are reduced to reduce the parasitic resistance. improves.
　また、実施の形態２によれば、集電極１０７（または１０８）の幅が狭い場合でも一面側透明電極と集電極１０７との接触面積および他面側透明電極と集電極１０８との接触面積を広く確保できるため、寄生抵抗が低下し、発電効率、曲線因子が向上する。 Further, according to the second embodiment, even when the width of the collecting electrode 107 (or 108) is narrow, the contact area between the one-side transparent electrode and the collecting electrode 107 and the contact area between the other-side transparent electrode and the collecting electrode 108 are reduced. Since it can be secured widely, the parasitic resistance is reduced, and the power generation efficiency and the fill factor are improved.
　また、実施の形態２によれば、下層透明電極１０６ａおよび下層透明電極１０６ｂの光透過性を高くするためにＩＴＯ等の酸素濃度を増加させて電気抵抗率が上昇した場合でも、上層透明電極１０９を備えることにより、光照射により発生した電荷の収集効率を向上させ、光電変換効率を向上させることができる。 Further, according to the second embodiment, even when the electrical resistivity is increased by increasing the oxygen concentration of ITO or the like in order to increase the light transmittance of the lower transparent electrode 106a and the lower transparent electrode 106b, the upper transparent electrode 109 Thus, the collection efficiency of charges generated by light irradiation can be improved, and the photoelectric conversion efficiency can be improved.
　また、実施の形態２によれば、下層透明電極１０６ａおよび下層透明電極１０６ｂの光透過性を高くするためにＩＴＯ等の酸素濃度を増加させて電気抵抗率が上昇した場合でも、光照射により発生した電荷の収集効率を向上させ、光電変換効率を向上させることができる。 Further, according to the second embodiment, even when the electrical resistivity is increased by increasing the oxygen concentration of ITO or the like in order to increase the light transmittance of the lower transparent electrode 106a and the lower transparent electrode 106b, it is generated by light irradiation. Thus, the efficiency of collecting collected charges can be improved, and the photoelectric conversion efficiency can be improved.
　したがって、実施の形態２によれば、曲線因子および光電変換効率に優れた太陽電池セルが得られる。 Therefore, according to the second embodiment, a solar battery cell having excellent fill factor and photoelectric conversion efficiency can be obtained.
　なお、上述した本発明の効果を得るためには、上層透明電極１０９は集電極１０７、１０８の一部とのみ電気的に接触した構造とされてもよい。ただし、本発明の効果をより有効に得るためには、上層透明電極１０９と集電極１０７、１０８との接触面積は広くすることが好ましい。 In addition, in order to obtain the above-described effects of the present invention, the upper transparent electrode 109 may have a structure in which only the collector electrodes 107 and 108 are in electrical contact. However, in order to obtain the effect of the present invention more effectively, it is preferable to increase the contact area between the upper transparent electrode 109 and the collector electrodes 107 and 108.
　また、上層透明電極１０９ａの電気抵抗が、下層透明電極１０６ａの電気抵抗よりも低いことが好ましい。これにより、下層透明電極１０６ａに到達した電荷の殆どが、集電極１０７との接触面積（導通面積）が広い上層透明電極１０９ａを通って集電極１０７に流れ、電荷が効率良く集電極１０７に収集される。同様に、上層透明電極１０９ｂの電気抵抗が、下層透明電極１０６ｂの電気抵抗よりも低いことが好ましい。これにより、下層透明電極１０６ｂに到達した電荷の殆どが、集電極１０８との接触面積（導通面積）が広い上層透明電極１０９ｂを通って集電極１０８に流れ、電荷が効率良く集電極１０８に収集される。 Further, it is preferable that the electric resistance of the upper transparent electrode 109a is lower than the electric resistance of the lower transparent electrode 106a. As a result, most of the charges reaching the lower transparent electrode 106a flow to the collector electrode 107 through the upper transparent electrode 109a having a large contact area (conduction area) with the collector electrode 107, and the charges are efficiently collected at the collector electrode 107. Is done. Similarly, the electrical resistance of the upper transparent electrode 109b is preferably lower than the electrical resistance of the lower transparent electrode 106b. As a result, most of the charges reaching the lower transparent electrode 106b flow to the collector electrode 108 through the upper transparent electrode 109b having a large contact area (conduction area) with the collector electrode 108, and the charges are efficiently collected in the collector electrode 108. Is done.
　また、上層透明電極１０９の結晶性を下層透明電極１０６の結晶性より高くすることにより、上層透明電極１０９の電気抵抗を下層透明電極１０６の電気抵抗よりも低減してもよい。これにより、ｎ型結晶珪素基板１０２で発生した電荷の殆どが下層透明電極１０６から上層透明電極１０９を通って集電極１０７（集電極１０８）に流れ、電荷が効率良く集電極１０７（集電極１０８）に収集される。 In addition, the electrical resistance of the upper transparent electrode 109 may be lower than the electrical resistance of the lower transparent electrode 106 by making the crystallinity of the upper transparent electrode 109 higher than that of the lower transparent electrode 106. As a result, most of the charge generated in the n-type crystalline silicon substrate 102 flows from the lower transparent electrode 106 through the upper transparent electrode 109 to the collector electrode 107 (collector electrode 108), and the charge is efficiently collected. ) Collected.
　また、上記の実施の形態で説明した構成を有する太陽電池セルを複数形成し、隣接する太陽電池セル同士を電気的に直列または並列に接続することにより、曲線因子および光電変換効率に優れた太陽電池モジュールが実現できる。この場合は、たとえば隣接する太陽電池セルの一方の一面側の集電極と他方の他面側の集電極とを電気的に接続すればよい。 In addition, by forming a plurality of solar cells having the configuration described in the above embodiment, and connecting adjacent solar cells electrically in series or in parallel, the solar having excellent fill factor and photoelectric conversion efficiency A battery module can be realized. In this case, for example, the collector electrode on one surface side of the adjacent solar battery cells may be electrically connected to the collector electrode on the other surface side.
実施の形態３．
　図７は、本発明の実施の形態３にかかる光電変換モジュールである太陽電池モジュール２０１の概略構成を模式的に示す断面図である。太陽電池モジュール２０１は、複数の太陽電池セル２０２が光透過性を有する封止層２０３で覆われている。図７においては、理解の容易のため複数の太陽電池セル２０２として３つの太陽電池セル２０２ａ、太陽電池セル２０２ｂ、太陽電池セル２０２ｃのみを示している。封止層２０３には、たとえばエチレン酢酸ビニルなどが用いられる。 Embodiment 3 FIG.
FIG. 7: is sectional drawing which shows typically schematic structure of the solar cell module 201 which is a photoelectric conversion module concerning Embodiment 3 of this invention. In the solar cell module 201, a plurality of solar cells 202 are covered with a sealing layer 203 having light transmittance. In FIG. 7, only three solar cells 202a, solar cells 202b, and solar cells 202c are shown as a plurality of solar cells 202 for easy understanding. For the sealing layer 203, for example, ethylene vinyl acetate or the like is used.
　封止層２０３の太陽電池セル２０２の受光面と同じ側の表面には透光性を有する受光面保持基板２０４が設けられている。封止層２０３の太陽電池セル２０２の受光面と反対側（裏面側）の表面には裏面保持基板２０５が設けられている。これにより、複数の太陽電池セル２０２は、受光面保持基板２０４と裏面保持基板２０５との間に封止層２０３を介して封止されている。なお、裏面保持基板２０５に透光性を持たせることにより、太陽電池モジュール２０１の両面を受光面とすることができる。封止層２０３、受光面保持基板２０４および裏面保持基板２０５の外周部には枠２０６が設けられている。太陽電池セル２０２それぞれは、下層透明電極２０７ａ、２０７ｂの上に形成されたバス電極２０８ａ、２０８ｂと、該バス電極２０８ａ、２０８ｂに接着された配線２０９ａ、２０９ｂとを介して、隣接する太陽電池セル２０２と電気的に直列接続されている。なお、以下においては、バス電極を総称してバス電極２０８と、配線を総称して配線２０９と呼ぶ場合がある。 A light-receiving surface holding substrate 204 having translucency is provided on the surface of the sealing layer 203 on the same side as the light-receiving surface of the solar battery cell 202. A back surface holding substrate 205 is provided on the surface of the sealing layer 203 opposite to the light receiving surface (back surface side) of the solar battery cell 202. Thus, the plurality of solar cells 202 are sealed between the light receiving surface holding substrate 204 and the back surface holding substrate 205 via the sealing layer 203. In addition, by providing the back surface holding substrate 205 with translucency, both surfaces of the solar cell module 201 can be used as light receiving surfaces. A frame 206 is provided on the outer periphery of the sealing layer 203, the light receiving surface holding substrate 204, and the back surface holding substrate 205. Each of the solar cells 202 is connected to adjacent solar cells via bus electrodes 208a and 208b formed on the lower transparent electrodes 207a and 207b and wirings 209a and 209b bonded to the bus electrodes 208a and 208b. 202 is electrically connected in series. In the following description, the bus electrode may be collectively referred to as the bus electrode 208, and the wiring may be collectively referred to as the wiring 209.
　配線２０９ａ、２０９ｂは、隣接する太陽電池セル２０２においてそれぞれ異なる面側のバス電極２０８に接続されている。具体的には、太陽電池セル２０２ａの受光面側のバス電極２０８ａに接続された配線２０９ａが、太陽電池セル２０２ａに隣接する太陽電池セル２０２ｂの裏面側のバス電極２０８ｃに接続されている。また、太陽電池セル２０２ａの裏面側のバス電極２０８ｂに接続された配線２０９ｂが、太陽電池セル２０２ａに隣接する太陽電池セル２０２ｃの受光面側のバス電極２０８ｄに接続されている。 The wirings 209a and 209b are connected to the bus electrodes 208 on different planes in the adjacent solar cells 202, respectively. Specifically, the wiring 209a connected to the bus electrode 208a on the light receiving surface side of the solar battery cell 202a is connected to the bus electrode 208c on the back surface side of the solar battery cell 202b adjacent to the solar battery cell 202a. Further, the wiring 209b connected to the bus electrode 208b on the back surface side of the solar battery cell 202a is connected to the bus electrode 208d on the light receiving surface side of the solar battery cell 202c adjacent to the solar battery cell 202a.
　太陽電池モジュール２０１を構成している太陽電池セル２０２には、実施の形態１に記載した太陽電池セル１、或いは実施の形態２に記載した太陽電池１０１が使用される。太陽電池セル２０２のバス電極２０８と配線２０９との接続抵抗を低下させるため、バス電極２０８の上には上述した上層透明電極は形成されない。バス電極２０８と配線２０９とは、低融点の半田や金属ペーストにより接続する。上層透明電極よりも抵抗率の低い金属材料によってバス電極２０８と配線２０９とが電気的に接続されるため、バス電極２０８と配線２０９との接続抵抗を低くできる。 As the solar battery cell 202 constituting the solar battery module 201, the solar battery cell 1 described in the first embodiment or the solar battery 101 described in the second embodiment is used. In order to reduce the connection resistance between the bus electrode 208 of the solar battery cell 202 and the wiring 209, the above-described upper transparent electrode is not formed on the bus electrode 208. The bus electrode 208 and the wiring 209 are connected by low melting point solder or metal paste. Since the bus electrode 208 and the wiring 209 are electrically connected by a metal material having a resistivity lower than that of the upper transparent electrode, the connection resistance between the bus electrode 208 and the wiring 209 can be reduced.
　図８は、図７の線分Ａ－Ａ’に沿った太陽電池モジュール２０１の断面図である。図８に示したように、配線２０９ａ、２０９ｂは上層透明電極２１０ａ、２１０ｂが形成されていないバス電極２０８ａ、２０８ｂ上に接着されている。これにより、接触抵抗の低いバス電極２０８と配線２０９との接続が実現できる。太陽電池セル２０２のバス電極２０８と配線２０９との接続以外の構成は、実施の形態１或いは実施の形態２と同等なため、詳細な図示および説明は割愛する。 FIG. 8 is a cross-sectional view of the solar cell module 201 taken along line A-A ′ in FIG. As shown in FIG. 8, the wirings 209a and 209b are bonded onto the bus electrodes 208a and 208b where the upper transparent electrodes 210a and 210b are not formed. Thereby, the connection between the bus electrode 208 having a low contact resistance and the wiring 209 can be realized. Since the configuration other than the connection between the bus electrode 208 and the wiring 209 of the solar battery cell 202 is the same as that in the first embodiment or the second embodiment, detailed illustration and description are omitted.
　実施の形態１或いは実施の形態２で示した構造の太陽電池セルは、曲線因子が従来の太陽電池より向上する。そして、このような太陽電池セルで構成された太陽電池モジュール２０１の曲線因子も向上する。これより、実施の形態３にかかる太陽電池モジュール２０１の光電変換効率は、従来の太陽電池セルを用いた太陽電池モジュールに比べて向上していることが明らかである。 The solar cell having the structure shown in the first embodiment or the second embodiment has a higher curve factor than the conventional solar cell. And the curve factor of the solar cell module 201 comprised with such a photovoltaic cell also improves. From this, it is clear that the photoelectric conversion efficiency of the solar cell module 201 according to the third embodiment is improved as compared with the conventional solar cell module using solar cells.
　したがって、実施の形態３によれば、曲線因子および光電変換効率に優れた太陽電池モジュールが得られる。 Therefore, according to the third embodiment, a solar cell module having excellent fill factor and photoelectric conversion efficiency can be obtained.
　以上のように、本発明にかかる光電変換装置は、光電変換効率に優れた光電変換装置の実現に有用である。 As described above, the photoelectric conversion device according to the present invention is useful for realizing a photoelectric conversion device excellent in photoelectric conversion efficiency.
　１　太陽電池セル
　２　ｎ型結晶珪素基板
　３ａ　ｉ型非晶質珪素層
　３ｂ　ｉ型非晶質珪素層
　４　ｐ型非晶質珪素層
　５　ｎ型非晶質珪素層
　６　下層透明電極
　６ａ　下層透明電極
　６ｂ　下層透明電極
　７　集電極
　７ａ　グリッド電極
　７ｂ　バス電極
　８　集電極
　８ａ　グリッド電極
　８ｂ　バス電極
　９　上層透明電極
　９ａ　上層透明電極
　９ｂ　上層透明電極
　１０１　太陽電池セル
　１０２　ｎ型結晶珪素基板
　１０３ａ　ｉ型非晶質珪素層
　１０３ｂ　ｉ型非晶質珪素層
　１０４　ｐ型非晶質珪素層
　１０５　ｎ型非晶質珪素層
　１０６　下層透明電極
　１０６ａ　下層透明電極
　１０６ｂ　下層透明電極
　１０７　集電極
　１０７ａ　グリッド電極
　１０７ｂ　バス電極
　１０８　集電極
　１０８ａ　グリッド電極
　１０８ｂ　バス電極
　１０９　上層透明電極
　１０９ａ　上層透明電極
　１０９ｂ　上層透明電極
　２０１　太陽電池モジュール
　２０２　太陽電池セル
　２０３　封止層
　２０４　受光面保持基板
　２０５　裏面保持基板
　２０６　枠
　２０７ａ　下層透明電極
　２０７ｂ　下層透明電極
　２０８　バス電極
　２０８ａ　バス電極
　２０８ｂ　バス電極
　２０８ｃ　バス電極
　２０８ｄ　バス電極
　２０９　配線
　２０９ａ　配線
　２０９ｂ　配線
　２１０ａ　上層透明電極
　２１０ｂ　上層透明電極 DESCRIPTION OF SYMBOLS 1 Solar cell 2 N-type crystalline silicon substrate 3a i-type amorphous silicon layer 3b i-type amorphous silicon layer 4 p-type amorphous silicon layer 5 n-type amorphous silicon layer 6 Lower transparent electrode 6a Lower transparent electrode 6b Lower layer transparent electrode 7 Collector electrode 7a Grid electrode 7b Bus electrode 8 Collector electrode 8a Grid electrode 8b Bus electrode 9 Upper layer transparent electrode 9a Upper layer transparent electrode 9b Upper layer transparent electrode 101 Solar cell 102 N-type crystalline silicon substrate 103a i-type amorphous Silicon layer 103b i-type amorphous silicon layer 104 p-type amorphous silicon layer 105 n-type amorphous silicon layer 106 lower transparent electrode 106a lower transparent electrode 106b lower transparent electrode 107 collector electrode 107a grid electrode 107b bus electrode 108 collector electrode 108a Grid electrode 108b Bus electrode 109 Upper transparent electrode 109a Upper transparent electrode 109b Upper transparent electrode 2 DESCRIPTION OF SYMBOLS 1 Solar cell module 202 Solar cell 203 Sealing layer 204 Light-receiving surface holding substrate 205 Back surface holding substrate 206 Frame 207a Lower layer transparent electrode 207b Lower layer transparent electrode 208 Bus electrode 208a Bus electrode 208b Bus electrode 208c Bus electrode 208d Bus electrode 209 Wiring 209a Wiring 209b Wiring 210a Upper layer transparent electrode 210b Upper layer transparent electrode

Claims (11)

  1. 　結晶性半導体基板の少なくとも片面に半導体層が形成された光電変換装置であって、
    　透明電極膜からなり前記半導体層上に形成された下層透明電極と、
    　前記下層透明電極上に前記下層透明電極に接触して形成された集電極と、
    　透明電極膜からなり前記集電極の上を覆うように形成され、前記集電極の一部および前記下層透明電極の一部と電気的に接触して形成された上層透明電極と、
    　を備えることを特徴とする光電変換装置。     A photoelectric conversion device in which a semiconductor layer is formed on at least one surface of a crystalline semiconductor substrate,
    A lower transparent electrode made of a transparent electrode film and formed on the semiconductor layer;
    A collector electrode formed on the lower transparent electrode in contact with the lower transparent electrode;
    An upper transparent electrode formed of a transparent electrode film so as to cover the collector electrode, and formed in electrical contact with a part of the collector electrode and a part of the lower transparent electrode;
    A photoelectric conversion device comprising:
  2. 　前記上層透明電極が、少なくとも前記下層透明電極の一部を覆って形成されていること、
    　を特徴とする請求項１に記載の光電変換装置。     The upper transparent electrode is formed so as to cover at least a part of the lower transparent electrode;
    The photoelectric conversion device according to claim 1.
  3. 　前記上層透明電極が、前記集電極および前記下層透明電極の全面を覆って形成されていること、
    　を特徴とする請求項２に記載の光電変換装置。     The upper transparent electrode is formed to cover the entire surface of the collector electrode and the lower transparent electrode;
    The photoelectric conversion device according to claim 2.
  4. 　前記上層透明電極の電気抵抗が、前記下層透明電極の電気抵抗より低いこと、
    　を特徴とする１乃至３のいずれか１つに記載の光電変換装置。     The electrical resistance of the upper transparent electrode is lower than the electrical resistance of the lower transparent electrode,
    The photoelectric conversion device according to any one of 1 to 3, wherein:
  5. 　前記上層透明電極の結晶性が、前記下層透明電極の結晶性より高いこと、
    　を特徴とする請求項１乃至４のいずれか１つに記載の光電変換装置。     The crystallinity of the upper transparent electrode is higher than the crystallinity of the lower transparent electrode,
    The photoelectric conversion device according to claim 1, wherein:
  6. 　前記上層透明電極の厚さが、前記下層透明電極の厚さより厚いこと、
    　を特徴とする請求項１乃至５のいずれか１つに記載の光電変換装置。     The upper transparent electrode is thicker than the lower transparent electrode;
    The photoelectric conversion device according to claim 1, wherein:
  7. 　前記上層透明電極の材料が、錫を添加した酸化インジウムであること、
    　を特徴とする請求項１乃至６のいずれか１つに記載の光電変換装置。     The material of the upper transparent electrode is indium oxide added with tin,
    The photoelectric conversion device according to claim 1, wherein:
  8. 　前記結晶性半導体基板がｎ型の導電型を有し、
    　前記結晶性半導体基板の一面側にｉ型半導体層とｐ型の前記半導体層がこの順で形成され、
    　前記結晶性半導体基板の他面側にｉ型半導体層とｎ型半導体層がこの順で形成されること、
    　を特徴とする請求項１乃至７のいずれか１つに記載の光電変換装置。     The crystalline semiconductor substrate has n-type conductivity;
    An i-type semiconductor layer and a p-type semiconductor layer are formed in this order on one surface side of the crystalline semiconductor substrate,
    An i-type semiconductor layer and an n-type semiconductor layer are formed in this order on the other surface side of the crystalline semiconductor substrate;
    The photoelectric conversion device according to claim 1, wherein:
  9. 　前記下層透明電極の材料が、錫を添加した酸化インジウム、酸化インジウムおよび酸化亜鉛のいずれか１種であること、
    　を特徴とする請求項１乃至８のいずれか１つに記載の光電変換装置。     The material of the lower transparent electrode is any one of indium oxide added with tin, indium oxide and zinc oxide,
    The photoelectric conversion device according to claim 1, wherein:
  10. 　隣接する光電変換装置同士が配線により電気的に接続された複数の前記光電変換装置と、
    　前記光電変換装置の受光面側に配置された透光性の受光面保持基板と
    　前記光電変換装置の受光面と反対側に配置された裏面保持基板と、
    　前記受光面保持基板と前記裏面保持基板との間に挟持されて前記複数の光電変換装置を封止する封止層と、
    　を備え、
    　前記光電変換装置が請求項１乃至９のいずれか１つに記載の光電変換装置であること、
    　を特徴とする光電変換モジュール。     A plurality of the photoelectric conversion devices in which adjacent photoelectric conversion devices are electrically connected by wiring; and
    A translucent light receiving surface holding substrate disposed on the light receiving surface side of the photoelectric conversion device, and a back surface holding substrate disposed on the opposite side of the light receiving surface of the photoelectric conversion device,
    A sealing layer that is sandwiched between the light receiving surface holding substrate and the back surface holding substrate to seal the plurality of photoelectric conversion devices;
    With
    The photoelectric conversion device is the photoelectric conversion device according to any one of claims 1 to 9,
    A photoelectric conversion module characterized by the above.
  11. 　結晶性半導体基板の少なくとも一面側に半導体層を形成する工程と、
    　前記半導体層上に透明電極膜からなる下層透明電極を形成する工程と、
    　前記下層透明電極上に前記下層透明電極に接触する集電極を形成する工程と、
    　透明電極膜からなり前記集電極の一部および前記下層透明電極の一部と電気的に接触する上層透明電極を前記集電極の上を覆うように形成する工程と、
    　を含むことを特徴とする光電変換装置の製造方法。     Forming a semiconductor layer on at least one side of the crystalline semiconductor substrate;
    Forming a lower transparent electrode comprising a transparent electrode film on the semiconductor layer;
    Forming a collector electrode in contact with the lower transparent electrode on the lower transparent electrode;
    Forming a transparent electrode film so as to cover a part of the collector electrode and an upper transparent electrode in electrical contact with a part of the lower transparent electrode so as to cover the collector electrode;
    A process for producing a photoelectric conversion device comprising:
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