WO2021106417A1 - Photovoltaic cell, photovoltaic cell module, and method for manufacturing photovoltaic cell - Google Patents

Photovoltaic cell, photovoltaic cell module, and method for manufacturing photovoltaic cell Download PDF

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Publication number
WO2021106417A1
WO2021106417A1 PCT/JP2020/039064 JP2020039064W WO2021106417A1 WO 2021106417 A1 WO2021106417 A1 WO 2021106417A1 JP 2020039064 W JP2020039064 W JP 2020039064W WO 2021106417 A1 WO2021106417 A1 WO 2021106417A1
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Prior art keywords
solar cell
electrode
semiconductor substrate
connection
main surface
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PCT/JP2020/039064
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French (fr)
Japanese (ja)
Inventor
訓太 吉河
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株式会社カネカ
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Priority to JP2021561214A priority Critical patent/JPWO2021106417A1/ja
Priority to CN202080077495.1A priority patent/CN114651336B/en
Publication of WO2021106417A1 publication Critical patent/WO2021106417A1/en

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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
    • H01L31/022433—Particular geometry of the grid contacts
    • 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
    • H01L31/0216—Coatings
    • H01L31/02161—Coatings for devices characterised by at least one potential jump barrier or surface barrier
    • H01L31/02167—Coatings 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

Definitions

  • the present invention relates to a solar cell, a solar cell module, and a method for manufacturing a solar cell.
  • a solar cell having a structure called PERC Passed Emitter and Real Cell
  • the PERC type solar cell is relatively expensive because a passivation film is formed on the back surface of the semiconductor substrate (the surface opposite to the light receiving surface) to prevent the generated carriers from recombining on the back surface of the semiconductor substrate.
  • the photoelectric conversion rate can be obtained.
  • the PERC type solar cell it is necessary to form an opening in the passivation film and extract electric power from a portion (base region) exposed from the opening of the semiconductor substrate. Therefore, the PERC type solar cell has a collection electrode that covers the back surface side of the passivation film, is filled inside the opening, and is connected to the semiconductor substrate.
  • the collection electrode has a main component of aluminum which has more holes by alloying with a semiconductor substrate and can form BSF (Back Surface Field) which suppresses carrier recombination. It is formed by a conductive paste (aluminum paste).
  • a conductive paste mainly composed of silver particles is used to provide a connection electrode having a relatively low electric resistance or a small electric resistance in the non-opening region of the passivation film.
  • connection electrode on the front surface side and the connection electrode on the back surface side are arranged so as to overlap in a plan view.
  • a conductivity called an interconnector is formed between a connection electrode on the front surface side of one solar cell and a connection electrode on the back surface side of an adjacent solar cell. Connected by members.
  • the connection electrodes on the front and back sides are arranged in the end region on the opposite side and directly connecting the connection electrodes on the back side of the solar cell adjacent to the connection electrodes on the front side of one solar cell, the connection electrodes are not exposed on the surface.
  • a solar cell module having a single ring structure that improves the overall photoelectric conversion efficiency in this way is also known.
  • the passivation film cannot be provided with an opening for current collection in the region where the connection electrode on the back surface side is provided, a region having low current collection efficiency is formed.
  • the photoelectric conversion efficiency cannot be sufficiently improved. Therefore, it is an object of the present invention to provide a solar cell, a solar cell module, and a method for manufacturing a solar cell having high photoelectric conversion efficiency.
  • the solar cell according to one aspect of the present invention is formed in a plate shape having a first main surface and a second main surface, and is spaced apart from each other along the first direction over the entire length of the second main surface.
  • a semiconductor substrate having a plurality of base regions arranged in parallel with each other, a plurality of first collecting electrodes arranged on the first main surface of the semiconductor substrate and extending in the first direction, and the first collecting electrode of the semiconductor substrate.
  • a first connecting electrode arranged in one end region of the first direction of the main surface and extending in a second direction intersecting the first direction so as to connect the plurality of first collecting electrodes, and a semiconductor substrate.
  • the second collection electrode may expose the ends of the passivation layer at both ends in the first direction.
  • the second collecting electrode may selectively cover the connection opening at both ends of the semiconductor substrate in the first direction.
  • the second connecting electrode may contain a plurality of silver particles and a binder
  • the second collecting electrode may contain a plurality of aluminum particles and a binder
  • the solar cell module according to another aspect of the present invention includes a plurality of the solar cells, and the second connection electrode of the other solar cell is directly connected to the first connection electrode of the solar cell.
  • a method for manufacturing a solar cell includes a step of laminating a passivation layer on the second main surface of a semiconductor substrate having a first main surface and a second main surface, and the first of the semiconductor substrates.
  • the passivation layer is subjected to the first direction over the entire length of the semiconductor substrate.
  • connection openings arranged in parallel with each other at intervals along the same direction, and in the end region of the passion layer in the first direction opposite to the first connection electrode, in the first direction.
  • a step of arranging a second collecting electrode that straddles and exposes the central portion of the second connecting electrode is provided.
  • the present invention it is possible to provide a solar cell, a solar cell module, and a method for manufacturing a solar cell having high photoelectric conversion efficiency.
  • FIG. 5 is a cross-sectional view taken along the line AA of the solar cell of FIG. It is sectional drawing BB of the solar cell of FIG. It is a flowchart which shows the procedure of the manufacturing method of the solar cell of FIG. It is a top view of the solar cell module including the solar cell of FIG. It is sectional drawing of the solar cell module of FIG. It is a back view of the solar cell which concerns on 2nd Embodiment of this invention.
  • FIG. 1 is a plan view of the solar cell 1
  • FIG. 2 is a back view of the solar cell 1 (showing a state of being turned inside out in the upper limit direction from FIG. 1)
  • FIG. 3 is a sectional view taken along line AA of FIG. 1 of the solar cell 1.
  • FIG. 4 is a sectional view taken along line BB in FIG. 1 of the solar cell 1.
  • the solar cell 1 of the present embodiment includes a plate-shaped semiconductor substrate 10 having a first main surface (light receiving surface) and a second main surface (back surface), and a plurality of first main surfaces arranged on the first main surface of the semiconductor substrate 10.
  • the antireflection layer 40 that covers the region between the 1 collection electrode 20, the first connection electrode 30 arranged on the first main surface of the semiconductor substrate 10, and the first collection electrode 20 on the first main surface of the semiconductor substrate 10.
  • the first collection electrode 20, the first connection electrode 30, and the second collection electrode 70 are hatched for the sake of clarity.
  • the semiconductor substrate 10 has a base material layer 11 showing a first conductive type, an emitter layer 12 formed on the first main surface side and showing a second conductive type different from the first conductive type, and a second main surface. It has a plurality of base regions 13 arranged on the side.
  • the semiconductor substrate 10 is made of a material constituting the base material layer 11, and can be formed from a base material showing a first conductive type.
  • the base material layer 11 (base material of the semiconductor substrate 10) can be composed of, for example, a polycrystalline silicon substrate or a single crystal silicon substrate containing boron, gallium, or the like.
  • the emitter layer 12 is formed on the entire first main surface of the semiconductor substrate 10.
  • the emitter layer 12 forms a pn junction with the base material layer 11 through which carriers pass. As a result, the emitter layer 12 is charged with a carrier.
  • the emitter layer 12 can be formed by doping the surface layer of the first main surface of the base material of the semiconductor substrate 10 with a dopant such as phosphorus. Specifically, the emitter layer 12 can be formed by diffusing a dopant in a thickness region of several ⁇ m from the surface of a crystalline silicon substrate by thermal diffusion. Further, the emitter layer 12 may be formed by forming an amorphous silicon layer or the like having a thickness of about 5 nm or more and 20 nm or less on the surface of the crystalline silicon substrate.
  • the base region 13 shows a first conductive type stronger than the base layer 11, and forms an electric field called BSF (Back Surface Field) having a charge opposite to that of the emitter layer 12.
  • BSF Back Surface Field
  • the base region 13 extends linearly along the first direction over the entire length of the semiconductor substrate 10 so as to cross the semiconductor substrate 10 on the second main surface of the semiconductor substrate 10, and is arranged in parallel with each other at intervals. Will be done. Preferably, they are arranged in a stripe shape arranged at regular intervals on the entire second main surface of the semiconductor substrate 10.
  • the term "linear” is not limited to the one that extends continuously with a constant width, and may have a break such as a broken line shape or a dotted line shape. Further, the width of the base region 13 does not have to be constant, and may have a shape such that the width formed as a set of circles, ellipses, etc. changes repeatedly.
  • the base region 13 can be formed by alloying the metal that is the main component of the second collecting electrode 70, which will be described later, by diffusing it on the surface layer of the second main surface of the base material of the semiconductor substrate 10, and is formed of, for example, aluminum silicide. Can be done.
  • the first collecting electrode 20 is a so-called finger electrode provided for collecting current from the emitter layer 12, and is formed on the first main surface of the semiconductor substrate 10 in a thin linear shape extending in the first direction.
  • the first collection electrodes 20 are preferably arranged parallel to each other at regular intervals.
  • the first collecting electrode 20 is preferably formed so as to be alternately arranged with the base region 13 in a plan view in order to improve the current collecting efficiency.
  • the first collection electrode 20 can be formed by printing and firing a conductive paste, and is preferably formed by a silver paste containing silver particles and a binder in order to reduce electrical resistance.
  • the width of the first collecting electrode 20 is preferably 30 ⁇ m or more and 100 ⁇ m or less.
  • the first connection electrode 30 extends in a second direction intersecting the first direction so as to connect the first collection electrode 20 to one end region of the first main surface of the semiconductor substrate 10 in the first direction. It is formed.
  • the first connection electrode 30 merges the currents collected by each first collection electrode 20 and connects to the adjacent solar cell 1 or an external circuit. Therefore, the first connection electrode 30 is formed in a band shape having a width larger than that of the first collection electrode 20.
  • the first connection electrode 30 is preferably formed so as to cross the semiconductor substrate 10 in the second direction so as to be connected to all the first collection electrodes 20.
  • the first connection electrode 30 can be formed by printing and firing a conductive paste such as silver paste, and is preferably formed integrally with the first collection electrode 20 when the first collection electrode 20 is molded.
  • the antireflection layer 40 suppresses the reflection of light on the surface of the solar cell 1 and increases the amount of light incident on the inside of the solar cell 1.
  • the antireflection layer 40 can be made of, for example, silicon nitride. Specifically, by subjecting the surface of the semiconductor substrate 10 to nitriding treatment, the surface of the semiconductor substrate 10 can be nitrided and modified into the antireflection layer 40. Further, by forming the first collecting electrode 20 and the first connecting electrode 30 on the surface of the semiconductor substrate 10 on which the antireflection layer 40 is formed by printing and firing an electric paste, the first collecting electrode 20 and the first connecting electrode 30 are formed.
  • the antireflection layer 40 can be left in a portion where the antireflection layer 40 penetrates the antireflection layer 40 and the first collection electrode 20 and the first connection electrode 30 are not formed.
  • the passivation layer 50 suppresses carrier recombination by chemically terminating the defect levels on the surfaces of the second main surfaces of the semiconductor substrate 10.
  • the passivation layer can be formed of silicon nitride, and a thin film of alumina that further improves the adhesiveness with the second collecting electrode 70 may be laminated on the back surface side of the thin film of silicon nitride.
  • connection openings 51 correspond to each base region 13 and extend linearly so as to cross the semiconductor substrate 10 along the first direction, and are arranged in parallel with each other. Therefore, the shape of the connection opening 51 is not limited to a continuous linear shape as in the shape of the base region 13, and may be a linear shape having a break such as a broken line shape or a dotted line shape. Further, the width of the connection opening 51 does not have to be constant, and may have a shape such that the width formed as a set of circles, ellipses, etc. changes repeatedly.
  • connection opening 51 can be formed by removing a part of the passivation layer 50 laminated on the entire second main surfaces of the semiconductor substrate 10 by laser irradiation or the like, as will be described in detail later.
  • the second connection electrode 60 is laminated side by side in the second direction so as not to overlap the connection opening 51 when viewed in the first direction, in the end region of the passivation layer 50 opposite to the first connection electrode 30 in the first direction. Will be done.
  • the plurality of second connection electrodes 60 are divided into a plurality of portions by removing a region overlapping the base region 13 from a single connection electrode (bus bar) in a conventional solar cell.
  • the increase in electrical resistance due to the removal of the base region 13 portion of the second connection electrode 60 can be compensated for by increasing the width of the second connection electrode 60 in the first direction.
  • the second connection electrode 60 does not overlap with the first connection electrode 30 in a plan view. That is, the first connection electrode 30 is not arranged on the front surface side of the end region on the side where the second connection electrode 60 is arranged on the semiconductor substrate 10, but the first collection electrode 20 is arranged and the back surface thereof. A base region 13 is formed on the side. As a result, the solar cell 1 can perform photoelectric conversion even in the end region on the side where the second connection electrode 60 is arranged.
  • the second connection electrode 60 can be formed by printing and firing a conductive paste.
  • the second connection electrode 60 contains silver particles and a binder, and is preferably formed by using a silver paste having excellent conductivity. It is preferable to provide a margin between the second connection electrode 60 and the connection opening 51 so that the second connection electrode 60 does not overlap with the connection opening 51 even if there is an error in printing the conductive paste.
  • the second collection electrode 70 is laminated so as to expose the central portion of the second connection electrode 60 across the base region 13, the passivation layer 50, and the second connection electrode 60 exposed in the connection opening 51.
  • the second collection electrode 70 connects between the base region 13 of the semiconductor substrate 10 and the second connection electrode 60.
  • the second collecting electrode 70 can reduce the electrical resistance between the base region 13 and the second connecting electrode 60 and make it difficult for the second collecting electrode 70 to be peeled off. it can.
  • the second collecting electrode 70 exposes the ends of the passivation layer 50 at both ends in the first direction.
  • the risk of a short circuit between the second collecting electrode 70 and the first collecting electrode 20 or the first connecting electrode 30 can be reduced.
  • the second collecting electrode 70 selectively covers the connection opening 51 at both ends of the semiconductor substrate 10. As a result, current can be collected from the end of the semiconductor substrate 10 in the first direction while reducing the risk of a short circuit between the second collecting electrode 70 and the first collecting electrode 20 or the first connecting electrode 30.
  • the overlapping width of the second collecting electrode 70 with the second connecting electrode 60 is on the side of the first connecting electrode 30 of the second connecting electrode 60 (the side where the distance to the end of the semiconductor substrate 10 in the first direction is large). It is preferably set to the maximum. As a result, the joint area between the second connecting electrode 60 and the second collecting electrode 70 becomes larger on the side where the current density of the second collecting electrode 70 is large, so that the portion where the current flows in the second collecting electrode 70 is large. It is possible to reduce the electric resistance of the current and collect current more efficiently.
  • the second collecting electrode 70 can be formed by printing and firing a conductive paste. It is preferable that the second collecting electrode 70 is mainly made of a metal capable of forming a base region by diffusing into the base material of the semiconductor substrate 10 and increasing the first conductivity. Specifically, the second collecting electrode 70 is preferably formed by using an aluminum paste containing aluminum particles and a binder.
  • the base region 13 is also formed in the end region where the second connection electrode 60 is arranged, and the electric power generated in the surface side region of the second connection electrode 60 of the semiconductor substrate 10 can also be recovered. it can. Therefore, the solar cell 1 has high photoelectric conversion efficiency. Further, in the solar cell 1, since the second connection electrode 60 is arranged between the connection openings 51, the electric resistance without lowering the photoelectric conversion efficiency by increasing the width of the second connection electrode 60 in the first direction. Can be reduced.
  • the solar cell 1 can be manufactured by the method for manufacturing a solar cell according to the present invention.
  • an embodiment of the method for manufacturing a solar cell according to the present invention will be described by taking the manufacturing of the solar cell 1 as an example with reference to FIG.
  • the solar cell 1 includes a step of forming the emitter layer 12 on the semiconductor substrate 10 (step S1: emitter layer forming step) and a step of laminating the antireflection layer 40 on the semiconductor substrate 10 (step S2: antireflection layer laminating step).
  • step S3 A step of laminating the passivation layer 50 on the second main surface of the semiconductor substrate 10 (step S3: passivation layer laminating step) and a step of arranging the first collecting electrode 20 on the first main surface of the semiconductor substrate 10 (step S4: The first collecting electrode laminating step), the step of arranging the first connecting electrode 30 on the first main surface of the semiconductor substrate 10 (step S5: the first connecting electrode laminating step), and the connection opening to the passion layer 50 by irradiation with a laser.
  • step S6 connection opening forming step
  • step S7 a second connection electrode laminating step
  • step S7 a second connection electrode laminating step
  • step S8 second collecting electrode laminating step
  • the emitter layer 12 is formed by doping the surface of the base material of the semiconductor substrate 10 with a dopant that exhibits conductivity different from that of the base material. Further, in the emitter layer forming step, the emitter layer 12 may be formed by laminating a layer of a material having a conductivity different from that of the base material on the surface of the base material of the semiconductor substrate 10 by a film forming technique.
  • the antireflection layer 40 can be formed by nitriding the semiconductor substrate 10. Further, the antireflection layer 40 may be formed by laminating a material for forming the antireflection layer 40 on the surface of the semiconductor substrate 10.
  • the passivation layer 50 is laminated on the second main surface of the semiconductor substrate 10 by a well-known film forming technique.
  • the first collecting electrode 20 is formed on the first main surface of the semiconductor substrate 10 by printing and firing the conductive paste.
  • a printing method of the conductive paste for example, screen printing can be adopted.
  • the first connection electrode 30 extending in the second direction so as to connect the first collection electrode 20 to the first main surface of the semiconductor substrate 10 is formed by printing and firing the conductive paste. Form.
  • This first connection electrode laminating step is preferably performed at the same time as the first collecting electrode laminating step of step S4. That is, the first collecting electrode 20 and the first connecting electrode 30 are integrally formed by printing the conductive paste on the surface of the semiconductor substrate 10 in a pattern including the first collecting electrode 20 and the first connecting electrode 30 and firing the paste. It is preferable to do so.
  • connection opening 51 can be formed by partially removing the passivation layer 50 by irradiating the laser.
  • the accuracy of the laser irradiation position in the first direction is generally lower than the accuracy in the second direction.
  • the connection opening 51 may be in the shape of a dotted line, which is intermittently irradiated with a laser pulse. In this case, the distance between the points forming the dotted line is determined by the pulse period and the laser scanning speed, and can be, for example, 0.1 mm or more and 1 mm or less.
  • connection electrode laminating process In the second connection electrode laminating step of step S7, the conductive paste having a small electric resistance is printed and fired in the first direction of the passivation layer 50 in the end region opposite to the first connection electrode 30 in the first direction.
  • a plurality of second connection electrodes 60 are laminated side by side in the second direction so as not to overlap with the connection opening 51. Even when the connection opening 51 is a dotted line, the connection opening 51 is arranged so as not to overlap the linear or band-shaped region in which the connection opening 51 line is formed, as in the case where the connection opening 51 is a continuous line.
  • the second connection electrode 60 is not arranged between the points.
  • each point on the dotted line (laser pulse timing) is not strictly controlled, it is technically difficult to match with the printing plate, and there is little merit.
  • the position of the point can be improved, but the productivity is lowered and the cost is increased.
  • one laser pulse forms one aperture, so that it becomes easy to control the influence of the laser on the semiconductor substrate 10.
  • the semiconductor substrate 10 that is, the base region 13 exposed in the connection opening 51 by printing and firing of the conductive paste having excellent connectivity with the base region 13, the passivation layer 50,
  • the second collecting electrode 70 is laminated so as to straddle the second connecting electrode 60 and expose the central portion of the second connecting electrode 60.
  • the laminated width of the second connection electrode 60 and the second collection electrode 70 is preferably 0.05 mm or more and 0.4 mm or less from the viewpoint of material use efficiency and connection resistance between the two electrodes.
  • the second collecting electrode 70 is at least in the vicinity of the connection opening 51 of the region where the semiconductor substrate 10 is cut to separate the individual solar cells 1 (both ends of the semiconductor substrate 10 of the solar cell 1 after separation in the first direction). It is preferable to expose the part other than the region. By doing so, the connection opening 51 can be completely covered with the second collecting electrode 70, and the second collecting electrode 70 covering the vicinity of the end portion can be minimized.
  • the metal of the conductive paste diffuses into the exposed region from the connection opening 51 of the semiconductor substrate 10 and alloys.
  • the second collecting electrode 70 By forming the second collecting electrode 70 with an aluminum paste, the second main surface of the semiconductor substrate 10 can be locally modified to aluminum silicide to form the base region 13.
  • the solar cell module 100 is an embodiment of the solar cell module according to the present invention.
  • the solar cell module 100 includes a plurality of solar cells 1 of FIGS. 1 to 4.
  • the solar cell module 100 includes a plurality of solar cell strings 110 formed by connecting a plurality of solar cells 1, a front side protective member 120 arranged on the front surface side of the solar cell string 110, and a back surface of the solar cell string 110. It includes a back side protective member 130 arranged on the side, a sealing material 140 filled in a gap between the front side protective member 120 and the back side protective member 130, and a connecting member 150 for connecting between the solar cell strings.
  • the solar cell string 110 is formed by connecting a plurality of solar cells 1 by a single ring method in which the ends in the first direction are overlapped.
  • the first connection electrode 30 of one solar cell 1 and the second connection electrode 60 of the other solar cell 1 are connected to a conductive adhesive, solder, or the like. It is directly connected using the connection material 99 of.
  • the connection opening 51 is the second collecting electrode. It is preferably completely covered with 70.
  • the connecting material 99 on the first connecting electrode 30 protrudes and reaches the main surface on the opposite side, the short circuit does not occur unless the second collecting electrode 70 is touched, so that the back surface side of the first connecting electrode 30 is formed. It is preferable that the covering area of the second collecting electrode 70 in the end region of is as small as possible.
  • the solar cell 1 has an opposite end portion that contributes to photoelectric conversion of another solar cell 1 in an end region provided with a first connection electrode 30 that inhibits light from entering the semiconductor substrate 10. Areas overlap. Therefore, the entire surface of the solar cell string 110 contributes to photoelectric conversion.
  • the solar cell string 110 is a portion where the photoelectric conversion efficiency is low by using the solar cell 1 in which the base region 13 is evenly arranged in the region where the second connection electrode 60 is provided on the back surface side of the semiconductor substrate 10. Since there is no such thing, the photoelectric conversion efficiency is high.
  • the front side protective member 120 protects the solar cell 1 by covering the solar cell string 110, that is, the first main surface of the solar cell 1 via the sealing material 140.
  • the front side protective member 120 can be formed from a plate-shaped or sheet-shaped material, and is preferably excellent in translucency and weather resistance.
  • a transparent resin such as an acrylic resin or a polycarbonate resin, glass, or the like can be mentioned.
  • the surface of the front side protective member 120 may be processed into an uneven shape or coated with an antireflection coating layer in order to suppress the reflection of light.
  • the back side protective member 130 covers the back surface of the solar cell string 110 via the sealing material 140 to protect the solar cell 1.
  • the back side protective member 130 can be formed of a plate-like or sheet-like material, and is preferably excellent in water-shielding property.
  • the back side protective member 130 is a laminate of, for example, a resin film such as polyethylene terephthalate (PET), polyethylene (PE), an olefin resin, a fluorine-containing resin, or a silicone resin, and a metal foil such as aluminum foil. Is preferably used.
  • the sealing material 140 seals and protects the solar cell string 110, that is, the solar cell 1, is between the light receiving side surface of the solar cell 1 and the front side protective member 120, and the back surface of the solar cell 1. It is interposed between the back side protective member 130 and the back side protective member 130.
  • the sealing material 140 protects the solar cell 1 by adhering the solar cell string 110 to the front side protective member 120 and the back side protective member 130 and eliminating the gap around the solar cell string 110. Therefore, examples of the sealing material 140 include ethylene / vinyl acetate copolymer (EVA), ethylene / ⁇ -olefin copolymer, ethylene / vinyl acetate / triallyl isocyanurate (EVAT), and polyvinyl butyral (PVB). ), Acrylic resin, urethane resin, or a translucent thermoplastic resin such as silicone resin is preferably used.
  • EVA ethylene / vinyl acetate copolymer
  • EVAT ethylene / vinyl acetate / triallyl isocyanurate
  • PVB polyvinyl butyral
  • Acrylic resin, urethane resin, or a translucent thermoplastic resin such as silicone resin is preferably used.
  • the connecting member 150 connects between the first connection electrodes 30 of the solar cell 1 at one end of the solar cell string 110 and between the second connection electrodes 60 of the solar cell 1 at the other end of the solar cell string 110, respectively.
  • the connecting member 150 extends outward from between the front side protective member 120 and the back side protective member 130 so that it can be connected to the external circuit of the solar cell module 100.
  • the solar cell module 100 includes a solar cell string 110 using the solar cell 1 having high photoelectric conversion efficiency, the photoelectric conversion efficiency is high.
  • FIG. 8 shows the solar cell 1A according to the second embodiment of the present invention.
  • the solar cell 1A of FIG. 8 can be used for the solar cell module 100 of FIG. 7 instead of the solar cell 1 of FIG. Regarding the solar cell 1A of FIG. 8, the same components as those of the solar cell 1 of FIG. 1 are designated by the same reference numerals, and redundant description will be omitted.
  • the solar cell 1A of FIG. 8 includes a second collecting electrode 70A having a planar shape different from that of the second collecting electrode 70 of the solar cell 1 of FIG. That is, in the solar cell 1A of FIG. 8, the second collecting electrode 70 of the solar cell 1 of FIG. 1 is replaced with a second collecting electrode 70A having a different planar shape.
  • the second collection electrode 70A is selectively laminated so as to cover the base region 13, the second connection electrode 60, and the region near the second connection electrode 60 of the passivation layer 50 exposed in the connection opening 51.
  • the portion of the second collecting electrode 70A that covers the base region 13 covers the region near the connection opening 51 of the passivation layer 50 to the extent that the base region 13 in the connection opening 51 is not exposed in consideration of manufacturing errors.
  • the solar cell 1A can take in light even from the portion where the second collection electrode 70A on the back surface side is not arranged, the output can be improved depending on the environment in which it is used. Further, the solar cell 1A can be provided at low cost because the amount of the material used to form the second collection electrode 70A is relatively small.

Abstract

A photovoltaic cell (1) according to the present invention comprises: a semiconductor substrate having a second major surface with a plurality of base regions arranged thereon in parallel and at an interval from each other, the plurality of base regions extending along a first direction throughout the length of the second major surface; a plurality of first collecting electrodes arranged on a first major surface of the semiconductor substrate and extending in the first direction; a first connecting electrode arranged in an end region of the first major surface of the semiconductor substrate on one side in the first direction, and extending in a second direction transverse to the first direction so as to connect the plurality of first collecting electrodes; a passivation layer (50) stacked on the second major surface of the semiconductor substrate and having a plurality of connection openings (51) formed therein exposing the base regions; a plurality of second connecting electrodes (60) arranged in an end region of the passivation layer (50) opposite to the first connecting electrodes in the first direction, side by side in the second direction so as not to overlap the connection openings (51); and a second collecting electrode (70) arranged over the base regions exposed in the connection openings (51), the passivation layer (50), and the second connecting electrodes (60), and exposing a central portion of each of the second connecting electrodes (60).

Description

太陽電池、太陽電池モジュール及び太陽電池の製造方法Manufacturing method of solar cells, solar cell modules and solar cells
　本発明は、太陽電池、太陽電池モジュール及び太陽電池の製造方法に関する。 The present invention relates to a solar cell, a solar cell module, and a method for manufacturing a solar cell.
　比較的光電変換効率が高い太陽電池として、ＰＥＲＣ（Ｐａｓｓｉｂａｔｅｄ　Ｅｍｉｔｔｅｒ　ａｎｄ　Ｒｅａｒ　Ｃｅｌｌ）と呼ばれる構造を有する太陽電池が知られている。ＰＥＲＣ型太陽電池は、半導体基板の裏面（受光面と反対側の面）にパッシベーション膜が形成されることにより、生成されたキャリアが半導体基板の裏面で再結合することを抑制して比較的高い光電変換率が得られる。ＰＥＲＣ型太陽電池では、パッシベーション膜に開口を形成し、半導体基板の開口から露出する部分（ベース領域）から電力を取り出す必要がある。このため、ＰＥＲＣ型太陽電池は、パッシベーション膜の裏面側を覆い、開口の内部に充填されて半導体基板と接続された収集電極を有する。 As a solar cell having a relatively high photoelectric conversion efficiency, a solar cell having a structure called PERC (Passed Emitter and Real Cell) is known. The PERC type solar cell is relatively expensive because a passivation film is formed on the back surface of the semiconductor substrate (the surface opposite to the light receiving surface) to prevent the generated carriers from recombining on the back surface of the semiconductor substrate. The photoelectric conversion rate can be obtained. In a PERC type solar cell, it is necessary to form an opening in the passivation film and extract electric power from a portion (base region) exposed from the opening of the semiconductor substrate. Therefore, the PERC type solar cell has a collection electrode that covers the back surface side of the passivation film, is filled inside the opening, and is connected to the semiconductor substrate.
　通常、ＰＥＲＣ型太陽電池において、収集電極は、半導体基板と合金化することによってより多くの正孔を有し、キャリアの再結合を抑制するＢＳＦ（Ｂａｃｋ　Ｓｕｒｆａｃｅ　Ｆｉｅｌｄ）を形成できるアルミニウムを主成分とする導電性ペースト（アルミニウムペースト）によって形成される。しかしながら、アルミニウムペーストだけでは電気抵抗が大きくなりやすいため、パッシベーション膜の非開口領域に銀粒子を主体とする導電性ペースト（銀ペースト）によって比較的電気抵抗か小さい接続電極を設ける構成が知られている（例えば特許文献１参照）。 Normally, in a PERC type solar cell, the collection electrode has a main component of aluminum which has more holes by alloying with a semiconductor substrate and can form BSF (Back Surface Field) which suppresses carrier recombination. It is formed by a conductive paste (aluminum paste). However, since the electric resistance tends to increase only with the aluminum paste, it is known that a conductive paste (silver paste) mainly composed of silver particles is used to provide a connection electrode having a relatively low electric resistance or a small electric resistance in the non-opening region of the passivation film. (See, for example, Patent Document 1).
特許第６５２５５８３号公報Japanese Patent No. 6525583
　一般的なＰＥＲＣ型太陽電池では、特許文献１に記載されるように、表面側の接続電極と裏面側の接続電極とが平面視で重複するよう配置される。このような太陽電池を複数接続して太陽電池モジュールを形成する場合には、１つの太陽電池の表面側の接続電極と隣接する太陽電池の裏面側の接続電極との間がインターコネクタと呼ばれる導電部材によって接続される。一方、表裏の接続電極を反対側の端部領域に配置し、１つの太陽電池の表側の接続電極に隣接する太陽電池の裏側の接続電極を直接接続することで、表面に接続電極が露出しないようにして総合的な光電変換効率を向上するシングリング構造の太陽電池モジュールも知られている。しかしながら、上述のようなＰＥＲＣ型太陽電池では、裏面側の接続電極を設ける領域には、パッシベーション膜に集電のための開口を設けることができないので集電効率が低い領域が形成されるため、光電変換効率を十分に向上することができない。そこで、本発明は、光電変換効率が高い太陽電池、太陽電池モジュール及び太陽電池の製造方法を提供することを課題とする。 In a general PERC type solar cell, as described in Patent Document 1, the connection electrode on the front surface side and the connection electrode on the back surface side are arranged so as to overlap in a plan view. When a plurality of such solar cells are connected to form a solar cell module, a conductivity called an interconnector is formed between a connection electrode on the front surface side of one solar cell and a connection electrode on the back surface side of an adjacent solar cell. Connected by members. On the other hand, by arranging the connection electrodes on the front and back sides in the end region on the opposite side and directly connecting the connection electrodes on the back side of the solar cell adjacent to the connection electrodes on the front side of one solar cell, the connection electrodes are not exposed on the surface. A solar cell module having a single ring structure that improves the overall photoelectric conversion efficiency in this way is also known. However, in the PERC type solar cell as described above, since the passivation film cannot be provided with an opening for current collection in the region where the connection electrode on the back surface side is provided, a region having low current collection efficiency is formed. The photoelectric conversion efficiency cannot be sufficiently improved. Therefore, it is an object of the present invention to provide a solar cell, a solar cell module, and a method for manufacturing a solar cell having high photoelectric conversion efficiency.
　本発明の一態様に係る太陽電池は、第１主面及び第２主面を有する板状に形成され、前記第２主面にその全長に亘ってそれぞれ第１方向に沿うよう互いに間隔を空けて平行に配置された複数のベース領域を有する半導体基板と、前記半導体基板の前記第１主面に配置され、前記第１方向に延びる複数の第１収集電極と、前記半導体基板の前記第１主面の前記第１方向の一方の端部領域に配置され、前記複数の第１収集電極を接続するよう前記第１方向に交差する第２方向に延びる第１接続電極と、前記半導体基板の前記第２主面に積層され、前記ベース領域をそれぞれ露出する複数の接続開口が形成されたパッシベーション層と、前記パッシベーション層の前記第１方向に前記第１接続電極と反対側の端部領域に、前記第１方向に見て前記接続開口と重複しないよう前記第２方向に並んで配置される複数の第２接続電極と、前記接続開口内に露出する前記ベース領域、前記パッシベーション層、及び前記第２接続電極に跨って配置され、前記第２接続電極の中央部を露出する第２収集電極と、を備える。 The solar cell according to one aspect of the present invention is formed in a plate shape having a first main surface and a second main surface, and is spaced apart from each other along the first direction over the entire length of the second main surface. A semiconductor substrate having a plurality of base regions arranged in parallel with each other, a plurality of first collecting electrodes arranged on the first main surface of the semiconductor substrate and extending in the first direction, and the first collecting electrode of the semiconductor substrate. A first connecting electrode arranged in one end region of the first direction of the main surface and extending in a second direction intersecting the first direction so as to connect the plurality of first collecting electrodes, and a semiconductor substrate. A passivation layer laminated on the second main surface and formed with a plurality of connection openings each exposing the base region, and an end region of the passivation layer opposite to the first connection electrode in the first direction. A plurality of second connection electrodes arranged side by side in the second direction so as not to overlap the connection opening when viewed in the first direction, the base region exposed in the connection opening, the passion layer, and the above. It is provided with a second collecting electrode, which is arranged so as to straddle the second connecting electrode and exposes the central portion of the second connecting electrode.
　本発明の太陽電池において、前記第２収集電極は、前記第１方向の両端部において、前記パッシベーション層の端部を露出してもよい。 In the solar cell of the present invention, the second collection electrode may expose the ends of the passivation layer at both ends in the first direction.
　本発明に係る太陽電池において、前記第２収集電極は、前記半導体基板の前記第１方向の両端部において、前記接続開口を選択的に被覆してもよい。 In the solar cell according to the present invention, the second collecting electrode may selectively cover the connection opening at both ends of the semiconductor substrate in the first direction.
　本発明に係る太陽電池において、前記第２接続電極は複数の銀粒子とバインダとを含み、前記第２収集電極は複数のアルミニウム粒子とバインダとを含んでもよい。 In the solar cell according to the present invention, the second connecting electrode may contain a plurality of silver particles and a binder, and the second collecting electrode may contain a plurality of aluminum particles and a binder.
　本発明の別の態様に係る太陽電池モジュールは、前記太陽電池を複数備え、前記太陽電池の前記第１接続電極に他の前記太陽電池の前記第２接続電極が直接接続されている。 The solar cell module according to another aspect of the present invention includes a plurality of the solar cells, and the second connection electrode of the other solar cell is directly connected to the first connection electrode of the solar cell.
　本発明の別の態様に係る太陽電池の製造方法は、第１主面及び第２主面を有する半導体基板の前記第２主面にパッシベーション層を積層する工程と、前記半導体基板の前記第１主面に、第１方向に延びる複数の第１収集電極を配置する工程と、前記半導体基板の前記第１主面の前記第１方向の一方の端部領域に、前記複数の第１収集電極を接続するよう前記第１方向に交差する第２方向に延びる第１接続電極を配置する工程と、レーザーの照射により、前記パッシベーション層に、前記半導体基板の全長に亘ってそれぞれ前記第１方向に沿うよう互いに間隔を空けて平行に配置される複数の接続開口を形成する工程と、前記パッシベーション層の前記第１方向に前記第１接続電極と反対側の端部領域に、前記第１方向に見て前記接続開口と重複しないよう前記第２方向に並んで複数の第２接続電極を配置する工程と、前記接続開口内に露出する前記半導体基板、前記パッシベーション層、及び前記第２接続電極に跨り、前記第２接続電極の中央部を露出する第２収集電極を配置する工程と、を備える。 A method for manufacturing a solar cell according to another aspect of the present invention includes a step of laminating a passivation layer on the second main surface of a semiconductor substrate having a first main surface and a second main surface, and the first of the semiconductor substrates. A step of arranging a plurality of first collecting electrodes extending in the first direction on the main surface, and the plurality of first collecting electrodes in one end region of the first main surface of the semiconductor substrate in the first direction. In the step of arranging the first connection electrode extending in the second direction intersecting the first direction so as to connect the semiconductor substrate, and by irradiating the laser, the passivation layer is subjected to the first direction over the entire length of the semiconductor substrate. In the step of forming a plurality of connection openings arranged in parallel with each other at intervals along the same direction, and in the end region of the passion layer in the first direction opposite to the first connection electrode, in the first direction. A step of arranging a plurality of second connection electrodes side by side in the second direction so as not to overlap with the connection opening, and on the semiconductor substrate, the passion layer, and the second connection electrode exposed in the connection opening. A step of arranging a second collecting electrode that straddles and exposes the central portion of the second connecting electrode is provided.
　本発明によれば、光電変換効率が高い太陽電池、太陽電池モジュール及び太陽電池の製造方法を提供することができる。 According to the present invention, it is possible to provide a solar cell, a solar cell module, and a method for manufacturing a solar cell having high photoelectric conversion efficiency.
本発明の第１実施形態に係る太陽電池の平面図である。It is a top view of the solar cell which concerns on 1st Embodiment of this invention. 図１の太陽電池の裏面図である。It is a back view of the solar cell of FIG. 図１の太陽電池のＡ－Ａ線断面図である。FIG. 5 is a cross-sectional view taken along the line AA of the solar cell of FIG. 図１の太陽電池のＢ－Ｂ線断面図である。It is sectional drawing BB of the solar cell of FIG. 図１の太陽電池の製造方法の手順を示すフローチャートである。It is a flowchart which shows the procedure of the manufacturing method of the solar cell of FIG. 図１の太陽電池を備える太陽電池モジュールの平面図である。It is a top view of the solar cell module including the solar cell of FIG. 図６の太陽電池モジュールの断面図である。It is sectional drawing of the solar cell module of FIG. 本発明の第２実施形態に係る太陽電池の裏面図である。It is a back view of the solar cell which concerns on 2nd Embodiment of this invention.
　以下、本発明の実施形態について、図面を参照しながら説明する。なお、便宜上、ハッチングや部材符号等を省略する場合もあるが、かかる場合、他の図面を参照するものとする。また、図面における種々部材の寸法は、便宜上、見やすいように調整されている。 Hereinafter, embodiments of the present invention will be described with reference to the drawings. For convenience, hatching, member codes, etc. may be omitted, but in such cases, other drawings shall be referred to. Further, the dimensions of the various members in the drawings are adjusted for convenience so that they can be easily seen.
＜太陽電池＞
　図１乃至図４に、本発明の第１実施形態に係る太陽電池１を示す。図１は太陽電池の平面図１、図２は太陽電池１の裏面図（図１から上限方向に裏返した状態を示す）、図３は太陽電池１の図１におけるＡ－Ａ線断面図、図４は太陽電池１の図１におけるＢ－Ｂ線断面図である。 <Solar cell>
1 to 4 show the solar cell 1 according to the first embodiment of the present invention. 1 is a plan view of the solar cell 1, FIG. 2 is a back view of the solar cell 1 (showing a state of being turned inside out in the upper limit direction from FIG. 1), and FIG. 3 is a sectional view taken along line AA of FIG. 1 of the solar cell 1. FIG. 4 is a sectional view taken along line BB in FIG. 1 of the solar cell 1.
　本実施形態の太陽電池１は、第１主面（受光面）及び第２主面（裏面）を有する板状の半導体基板１０と、半導体基板１０の第１主面に配置される複数の第１収集電極２０と、半導体基板１０の第１主面に配置される第１接続電極３０と、半導体基板１０の第１主面の第１収集電極２０間の領域を覆う反射防止層４０と、半導体基板１０の第２主面に積層されるパッシベーション層５０と、パッシベーション層５０の裏面に配置される複数の第２接続電極６０と、パッシベーション層５０の裏面に配置される第２収集電極７０と、を備える。なお、図１及び図２では、分かりやすくするために、第１収集電極２０、第１接続電極３０及び第２収集電極７０にはハッチングを付している。 The solar cell 1 of the present embodiment includes a plate-shaped semiconductor substrate 10 having a first main surface (light receiving surface) and a second main surface (back surface), and a plurality of first main surfaces arranged on the first main surface of the semiconductor substrate 10. The antireflection layer 40 that covers the region between the 1 collection electrode 20, the first connection electrode 30 arranged on the first main surface of the semiconductor substrate 10, and the first collection electrode 20 on the first main surface of the semiconductor substrate 10. A passion layer 50 laminated on the second main surface of the semiconductor substrate 10, a plurality of second connection electrodes 60 arranged on the back surface of the passion layer 50, and a second collection electrode 70 arranged on the back surface of the passion layer 50. , Equipped with. In addition, in FIGS. 1 and 2, the first collection electrode 20, the first connection electrode 30, and the second collection electrode 70 are hatched for the sake of clarity.
　半導体基板１０は、第１の導電型を示す基材層１１と、第１主面側に形成され、第１の導電型と異なる第２の導電型を示すエミッタ層１２と、第２主面側に配置された複数のベース領域１３と、を有する。半導体基板１０は、基材層１１を構成する材料からなり、第１の導電型を示す基材から形成することができる。 The semiconductor substrate 10 has a base material layer 11 showing a first conductive type, an emitter layer 12 formed on the first main surface side and showing a second conductive type different from the first conductive type, and a second main surface. It has a plurality of base regions 13 arranged on the side. The semiconductor substrate 10 is made of a material constituting the base material layer 11, and can be formed from a base material showing a first conductive type.
　基材層１１（半導体基板１０の基材）は、例えばボロン、ガリウム等を含有する多結晶シリコン基板又は単結晶シリコン基板によって構成することができる。 The base material layer 11 (base material of the semiconductor substrate 10) can be composed of, for example, a polycrystalline silicon substrate or a single crystal silicon substrate containing boron, gallium, or the like.
　エミッタ層１２は、半導体基板１０の第１主面全体に形成される。エミッタ層１２は、基材層１１との間にキャリアを通過するｐｎ接合を形成する。これにより、エミッタ層１２は、キャリアに対応する電荷を帯びる。 The emitter layer 12 is formed on the entire first main surface of the semiconductor substrate 10. The emitter layer 12 forms a pn junction with the base material layer 11 through which carriers pass. As a result, the emitter layer 12 is charged with a carrier.
　エミッタ層１２は、半導体基板１０の基材の第１主面の表層に例えばリン等のドーパントをドープすることによって形成することができる。具体的には、エミッタ層１２は、熱拡散によって結晶シリコン基板の表面から数μｍの厚み領域にドーパントを拡散させることによって形成することができる。また、エミッタ層１２は、結晶シリコン基板の表面に５ｎｍ以上２０ｎｍ以下程度の厚みを有する非晶質シリコン層等を製膜することによって形成されてもよい。 The emitter layer 12 can be formed by doping the surface layer of the first main surface of the base material of the semiconductor substrate 10 with a dopant such as phosphorus. Specifically, the emitter layer 12 can be formed by diffusing a dopant in a thickness region of several μm from the surface of a crystalline silicon substrate by thermal diffusion. Further, the emitter layer 12 may be formed by forming an amorphous silicon layer or the like having a thickness of about 5 nm or more and 20 nm or less on the surface of the crystalline silicon substrate.
　ベース領域１３は、基材層１１よりも強い第１の導電型を示し、エミッタ層１２とは反対の電荷を帯びるＢＳＦ（Ｂａｃｋ　Ｓｕｒｆａｃｅ　Ｆｉｅｌｄ）と呼ばれる電場を形成する。これにより、ベース領域１３は、多数キャリアを引き付け、少数キャリアをエミッタ層１２側に追い返すことで、キャリアライフタイムを増大させる。 The base region 13 shows a first conductive type stronger than the base layer 11, and forms an electric field called BSF (Back Surface Field) having a charge opposite to that of the emitter layer 12. As a result, the base region 13 attracts a large number of carriers and repels the minority carriers to the emitter layer 12 side, thereby increasing the carrier lifetime.
　ベース領域１３は、半導体基板１０の第２主面に、それぞれ半導体基板１０を横断するよう半導体基板１０の全長に亘って第１方向に沿って線状に延び、互いに間隔を空けて平行に配置される。好ましくは、半導体基板１０の第２主面の全体に一定の間隔で並んだストライプ状に配置される。なお、「線状」とは、一定の幅で連続して延びるものに限られず、例えば破線状乃至点線状等、切れ目を有してもよい。また、ベース領域１３の幅は一定でなくてもよく、例えば円、楕円等の集合として形成される幅が繰り返し変化するような形状を有してもよい。 The base region 13 extends linearly along the first direction over the entire length of the semiconductor substrate 10 so as to cross the semiconductor substrate 10 on the second main surface of the semiconductor substrate 10, and is arranged in parallel with each other at intervals. Will be done. Preferably, they are arranged in a stripe shape arranged at regular intervals on the entire second main surface of the semiconductor substrate 10. The term "linear" is not limited to the one that extends continuously with a constant width, and may have a break such as a broken line shape or a dotted line shape. Further, the width of the base region 13 does not have to be constant, and may have a shape such that the width formed as a set of circles, ellipses, etc. changes repeatedly.
　ベース領域１３は、後述する第２収集電極７０の主体となる金属を半導体基板１０の基材の第２主面の表層に拡散させて合金化したものとすることができ、例えばアルミシリサイドによって形成され得る。 The base region 13 can be formed by alloying the metal that is the main component of the second collecting electrode 70, which will be described later, by diffusing it on the surface layer of the second main surface of the base material of the semiconductor substrate 10, and is formed of, for example, aluminum silicide. Can be done.
　第１収集電極２０は、エミッタ層１２から集電するために設けられるいわゆるフィンガー電極であり、半導体基板１０の第１主面にそれぞれ第１方向に延びる細い線状に形成される。第１収集電極２０は、好ましくは一定の間隔を空けて、互いに平行に配置される。第１収集電極２０は、集電効率を向上するために、平面視でベース領域１３と交互に配置されるよう形成されることが好ましい。第１収集電極２０は、導電性ペーストの印刷及び焼成により形成することができ、電気抵抗を小さくするために、銀粒子とバインダとを含む銀ペーストによって形成することが好ましい。 The first collecting electrode 20 is a so-called finger electrode provided for collecting current from the emitter layer 12, and is formed on the first main surface of the semiconductor substrate 10 in a thin linear shape extending in the first direction. The first collection electrodes 20 are preferably arranged parallel to each other at regular intervals. The first collecting electrode 20 is preferably formed so as to be alternately arranged with the base region 13 in a plan view in order to improve the current collecting efficiency. The first collection electrode 20 can be formed by printing and firing a conductive paste, and is preferably formed by a silver paste containing silver particles and a binder in order to reduce electrical resistance.
　第１収集電極２０は、半導体基板１０への光の入射を阻害するため、導電性を確保できる範囲内で幅をできるだけ小さくすることが望ましい。具体的には、第１収集電極２０の幅は、３０μｍ以上１００μｍ以下とすることが好ましい。 Since the first collecting electrode 20 hinders the incident of light on the semiconductor substrate 10, it is desirable that the width of the first collecting electrode 20 be as small as possible within a range in which conductivity can be ensured. Specifically, the width of the first collecting electrode 20 is preferably 30 μm or more and 100 μm or less.
　第１接続電極３０は、半導体基板１０の第１主面の第１方向の一方の端部領域に、第１収集電極２０を接続するよう、第１方向に交差する第２方向に延びるように形成される。第１接続電極３０は、各第１収集電極２０が集めた電流を合流させて、隣接する太陽電池１又は外部の回路に接続する。このため、第１接続電極３０は、第１収集電極２０よりも幅が大きい帯状に形成される。第１接続電極３０は、全ての第１収集電極２０に接続されるよう、半導体基板１０を第２方向に横断するように形成されることが好ましい。第１接続電極３０は、例えば銀ペースト等の導電性ペーストの印刷及び焼成により形成することができ、第１収集電極２０の成形時に第１収集電極２０と一体に形成することが好ましい。 The first connection electrode 30 extends in a second direction intersecting the first direction so as to connect the first collection electrode 20 to one end region of the first main surface of the semiconductor substrate 10 in the first direction. It is formed. The first connection electrode 30 merges the currents collected by each first collection electrode 20 and connects to the adjacent solar cell 1 or an external circuit. Therefore, the first connection electrode 30 is formed in a band shape having a width larger than that of the first collection electrode 20. The first connection electrode 30 is preferably formed so as to cross the semiconductor substrate 10 in the second direction so as to be connected to all the first collection electrodes 20. The first connection electrode 30 can be formed by printing and firing a conductive paste such as silver paste, and is preferably formed integrally with the first collection electrode 20 when the first collection electrode 20 is molded.
　反射防止層４０は、太陽電池１の表面における光の反射を抑制し、太陽電池１の内部に入射する光量を増大させる。反射防止層４０は、例えば窒化ケイ素によって構成することができる。具体的には、半導体基板１０の表面に窒化処理を施すことにより、半導体基板１０の表面を窒化して反射防止層４０に変性することができる。また、反射防止層４０を形成した半導体基板１０の表面に電性ペーストの印刷及び焼成により第１収集電極２０及び第１接続電極３０を形成することで、第１収集電極２０及び第１接続電極３０が反射防止層４０を貫通し、第１収集電極２０及び第１接続電極３０が形成されない部分に反射防止層４０を残すことができる。 The antireflection layer 40 suppresses the reflection of light on the surface of the solar cell 1 and increases the amount of light incident on the inside of the solar cell 1. The antireflection layer 40 can be made of, for example, silicon nitride. Specifically, by subjecting the surface of the semiconductor substrate 10 to nitriding treatment, the surface of the semiconductor substrate 10 can be nitrided and modified into the antireflection layer 40. Further, by forming the first collecting electrode 20 and the first connecting electrode 30 on the surface of the semiconductor substrate 10 on which the antireflection layer 40 is formed by printing and firing an electric paste, the first collecting electrode 20 and the first connecting electrode 30 are formed. The antireflection layer 40 can be left in a portion where the antireflection layer 40 penetrates the antireflection layer 40 and the first collection electrode 20 and the first connection electrode 30 are not formed.
　パッシベーション層５０は、半導体基板１０の第２両主面の表面の欠陥準位を化学的に終端することにより、キャリアの再結合を抑制する。パッシベーション層は、窒化ケイ素によって形成することができ、窒化ケイ素の薄膜の裏面側にさらに第２収集電極７０との接着性を向上するアルミナの薄膜を積層した構成としてもよい。 The passivation layer 50 suppresses carrier recombination by chemically terminating the defect levels on the surfaces of the second main surfaces of the semiconductor substrate 10. The passivation layer can be formed of silicon nitride, and a thin film of alumina that further improves the adhesiveness with the second collecting electrode 70 may be laminated on the back surface side of the thin film of silicon nitride.
　パッシベーション層５０は、それぞれベース領域１３を露出するよう形成された複数の接続開口５１を有する。このため、接続開口５１は、各ベース領域１３に対応し、それぞれ第１方向に沿って半導体基板１０を横断するよう線状に延び、互いに平行に配設される。したがって、接続開口５１の形状は、ベース領域１３の形状と同様に、連続した線状のものに限られず、例えば破線状乃至点線状等、切れ目を有する線状であってもよい。また、接続開口５１の幅は一定でなくてもよく、例えば円、楕円等の集合として形成される幅が繰り返し変化するような形状を有してもよい。 Each of the passivation layers 50 has a plurality of connection openings 51 formed so as to expose the base region 13. Therefore, the connection openings 51 correspond to each base region 13 and extend linearly so as to cross the semiconductor substrate 10 along the first direction, and are arranged in parallel with each other. Therefore, the shape of the connection opening 51 is not limited to a continuous linear shape as in the shape of the base region 13, and may be a linear shape having a break such as a broken line shape or a dotted line shape. Further, the width of the connection opening 51 does not have to be constant, and may have a shape such that the width formed as a set of circles, ellipses, etc. changes repeatedly.
　接続開口５１は、後で詳しく説明するように、半導体基板１０の第２両主面全体に積層したパッシベーション層５０の一部をレーザー照射等によって除去することによって形成することができる。 The connection opening 51 can be formed by removing a part of the passivation layer 50 laminated on the entire second main surfaces of the semiconductor substrate 10 by laser irradiation or the like, as will be described in detail later.
　第２接続電極６０は、パッシベーション層５０の第１方向の第１接続電極３０と反対側の端部領域に、第１方向に見て、接続開口５１と重複しないよう第２方向に並んで積層される。この複数の第２接続電極６０は、従来の太陽電池における単一の接続電極（バスバー）からベース領域１３と重複する領域を除去することにより複数に分割したものである。第２接続電極６０のベース領域１３部分の除去による電気抵抗の増加は、第２接続電極６０の第１方向の幅を大きくすることで補完することができる。 The second connection electrode 60 is laminated side by side in the second direction so as not to overlap the connection opening 51 when viewed in the first direction, in the end region of the passivation layer 50 opposite to the first connection electrode 30 in the first direction. Will be done. The plurality of second connection electrodes 60 are divided into a plurality of portions by removing a region overlapping the base region 13 from a single connection electrode (bus bar) in a conventional solar cell. The increase in electrical resistance due to the removal of the base region 13 portion of the second connection electrode 60 can be compensated for by increasing the width of the second connection electrode 60 in the first direction.
　第２接続電極６０は、平面視において第１接続電極３０とは重複しない。つまり、半導体基板１０の第２接続電極６０が配設される側の端部領域の表面側には第１接続電極３０が配置されておらず、第１収集電極２０が配設され、その裏面側にはベース領域１３が形成されている。これにより、太陽電池１は、第２接続電極６０が配設される側の端部領域においても光電変換を行うことができる。 The second connection electrode 60 does not overlap with the first connection electrode 30 in a plan view. That is, the first connection electrode 30 is not arranged on the front surface side of the end region on the side where the second connection electrode 60 is arranged on the semiconductor substrate 10, but the first collection electrode 20 is arranged and the back surface thereof. A base region 13 is formed on the side. As a result, the solar cell 1 can perform photoelectric conversion even in the end region on the side where the second connection electrode 60 is arranged.
　第２接続電極６０は、導電性ペーストの印刷及び焼成により形成することができる。第２接続電極６０は、銀粒子とバインダとを含み、導電性に優れる銀ペーストを用いて形成されることが好ましい。第２接続電極６０と接続開口５１との間には、導電性ペーストの印刷に誤差があっても第２接続電極６０が接続開口５１と重ならないようにマージンを設けることが好ましい。 The second connection electrode 60 can be formed by printing and firing a conductive paste. The second connection electrode 60 contains silver particles and a binder, and is preferably formed by using a silver paste having excellent conductivity. It is preferable to provide a margin between the second connection electrode 60 and the connection opening 51 so that the second connection electrode 60 does not overlap with the connection opening 51 even if there is an error in printing the conductive paste.
　第２収集電極７０は、接続開口５１内に露出するベース領域１３、パッシベーション層５０、及び第２接続電極６０に跨って、第２接続電極６０の中央部を露出するよう積層される。この第２収集電極７０は、半導体基板１０のベース領域１３と第２接続電極６０との間を接続する。第２収集電極７０は、パッシベーション層５０の裏面を広く覆うことによって、ベース領域１３と第２接続電極６０との間の電気抵抗を低減すると共に、第２収集電極７０を剥離し難くすることができる。 The second collection electrode 70 is laminated so as to expose the central portion of the second connection electrode 60 across the base region 13, the passivation layer 50, and the second connection electrode 60 exposed in the connection opening 51. The second collection electrode 70 connects between the base region 13 of the semiconductor substrate 10 and the second connection electrode 60. By widely covering the back surface of the passivation layer 50, the second collecting electrode 70 can reduce the electrical resistance between the base region 13 and the second connecting electrode 60 and make it difficult for the second collecting electrode 70 to be peeled off. it can.
　但し、第２収集電極７０は、第１方向の両端部においては、パッシベーション層５０の端部を露出することが好ましい。第２収集電極７０がパッシベーション層５０の端部を露出することによって、第２収集電極７０と第１収集電極２０又は第１接続電極３０との短絡のリスクを低減することができる。より好ましくは、第２収集電極７０は、半導体基板１０の両端部において、接続開口５１を選択的に被覆する。これにより、第２収集電極７０と第１収集電極２０又は第１接続電極３０との短絡のリスクを小さくしながら、半導体基板１０の第１方向の端部からも集電することができる。 However, it is preferable that the second collecting electrode 70 exposes the ends of the passivation layer 50 at both ends in the first direction. By exposing the end portion of the passivation layer 50 by the second collecting electrode 70, the risk of a short circuit between the second collecting electrode 70 and the first collecting electrode 20 or the first connecting electrode 30 can be reduced. More preferably, the second collecting electrode 70 selectively covers the connection opening 51 at both ends of the semiconductor substrate 10. As a result, current can be collected from the end of the semiconductor substrate 10 in the first direction while reducing the risk of a short circuit between the second collecting electrode 70 and the first collecting electrode 20 or the first connecting electrode 30.
　第２収集電極７０の第２接続電極６０との重複幅は、第２接続電極６０の前記第１接続電極３０の側（第１方向の半導体基板１０の端部までの距離が大きい側）において最大とされることが好ましい。これにより、第２接続電極６０と第２収集電極７０との接合面積が第２収集電極７０の電流密度が大きい側においてより大きくなるので、電流が第２収集電極７０内を流れる距離が大きい部分の電気抵抗を小さくして、より効率よく集電することができる。 The overlapping width of the second collecting electrode 70 with the second connecting electrode 60 is on the side of the first connecting electrode 30 of the second connecting electrode 60 (the side where the distance to the end of the semiconductor substrate 10 in the first direction is large). It is preferably set to the maximum. As a result, the joint area between the second connecting electrode 60 and the second collecting electrode 70 becomes larger on the side where the current density of the second collecting electrode 70 is large, so that the portion where the current flows in the second collecting electrode 70 is large. It is possible to reduce the electric resistance of the current and collect current more efficiently.
　第２収集電極７０は、導電性ペーストの印刷及び焼成により形成することができる。第２収集電極７０は、半導体基板１０の基材に拡散して第１の導電性を増大することによってベース領域を形成できる金属を主体とすることが好ましい。具体的には、第２収集電極７０は、アルミニウム粒子とバインダとを含むアルミニウムペーストを用いて形成することが好ましい。 The second collecting electrode 70 can be formed by printing and firing a conductive paste. It is preferable that the second collecting electrode 70 is mainly made of a metal capable of forming a base region by diffusing into the base material of the semiconductor substrate 10 and increasing the first conductivity. Specifically, the second collecting electrode 70 is preferably formed by using an aluminum paste containing aluminum particles and a binder.
　太陽電池１は、第２接続電極６０が配設される端部領域にもベース領域１３が形成され、半導体基板１０の第２接続電極６０の表面側領域において生成される電力も回収することができる。このため、太陽電池１は、光電変換効率が高い。また、太陽電池１は、第２接続電極６０が接続開口５１の間に配置されるので、第２接続電極６０の第１方向の幅を大きくすることによって光電変換効率を低下させることなく電気抵抗を低減することができる。 In the solar cell 1, the base region 13 is also formed in the end region where the second connection electrode 60 is arranged, and the electric power generated in the surface side region of the second connection electrode 60 of the semiconductor substrate 10 can also be recovered. it can. Therefore, the solar cell 1 has high photoelectric conversion efficiency. Further, in the solar cell 1, since the second connection electrode 60 is arranged between the connection openings 51, the electric resistance without lowering the photoelectric conversion efficiency by increasing the width of the second connection electrode 60 in the first direction. Can be reduced.
＜太陽電池の製造方法＞
　太陽電池１は、本発明に係る太陽電池の製造方法によって製造することができる。以下、本発明に係る太陽電池の製造方法の一実施形態について、図５を参照しながら、太陽電池１の製造を例にとって説明する。 <Solar cell manufacturing method>
The solar cell 1 can be manufactured by the method for manufacturing a solar cell according to the present invention. Hereinafter, an embodiment of the method for manufacturing a solar cell according to the present invention will be described by taking the manufacturing of the solar cell 1 as an example with reference to FIG.
　太陽電池１は、半導体基板１０にエミッタ層１２を形成する工程（ステップＳ１：エミッタ層形成工程）と、半導体基板１０に反射防止層４０を積層する工程（ステップＳ２：反射防止層積層工程）と、半導体基板１０の第２主面にパッシベーション層５０を積層する工程（ステップＳ３：パッシベーション層積層工程）と、半導体基板１０の第１主面に第１収集電極２０を配置する工程（ステップＳ４：第１収集電極積層工程）と、半導体基板１０の第１主面に第１接続電極３０を配置する工程（ステップＳ５：第１接続電極積層工程）と、レーザーの照射によりパッシベーション層５０に接続開口５１を形成する工程（ステップＳ６：接続開口形成工程）と、パッシベーション層５０に第２接続電極６０を配置する工程（ステップＳ７：第２接続電極積層工程）と、接続開口５１内に露出する半導体基板１０、パッシベーション層５０、及び第２接続電極６０に跨って第２収集電極７０を配置する工程（ステップＳ８：第２収集電極積層工程）と、を備える、製造方法によって製造することができる。なお、一部の工程は、その順番を入れ替えたり、他の工程と同時に行ったりすることができる。 The solar cell 1 includes a step of forming the emitter layer 12 on the semiconductor substrate 10 (step S1: emitter layer forming step) and a step of laminating the antireflection layer 40 on the semiconductor substrate 10 (step S2: antireflection layer laminating step). , A step of laminating the passivation layer 50 on the second main surface of the semiconductor substrate 10 (step S3: passivation layer laminating step) and a step of arranging the first collecting electrode 20 on the first main surface of the semiconductor substrate 10 (step S4: The first collecting electrode laminating step), the step of arranging the first connecting electrode 30 on the first main surface of the semiconductor substrate 10 (step S5: the first connecting electrode laminating step), and the connection opening to the passion layer 50 by irradiation with a laser. A step of forming the 51 (step S6: connection opening forming step), a step of arranging the second connection electrode 60 on the passion layer 50 (step S7: a second connection electrode laminating step), and a semiconductor exposed in the connection opening 51. It can be manufactured by a manufacturing method including a step of arranging the second collecting electrode 70 across the substrate 10, the passivation layer 50, and the second connecting electrode 60 (step S8: second collecting electrode laminating step). It should be noted that some steps can be changed in order or can be performed at the same time as other steps.
（エミッタ層形成工程）
　ステップＳ１のエミッタ層形成工程では、半導体基板１０の基材の表面に、基材と異なる導電性を発現させるドーパントをドープすることによりエミッタ層１２を形成する。また、エミッタ層形成工程では、成膜技術により半導体基板１０の基材の表面に基材と異なる導電性を有する材料の層を積層することによってエミッタ層１２を形成してもよい。 (Emitter layer forming process)
In the emitter layer forming step of step S1, the emitter layer 12 is formed by doping the surface of the base material of the semiconductor substrate 10 with a dopant that exhibits conductivity different from that of the base material. Further, in the emitter layer forming step, the emitter layer 12 may be formed by laminating a layer of a material having a conductivity different from that of the base material on the surface of the base material of the semiconductor substrate 10 by a film forming technique.
（反射防止層積層工程）
　ステップＳ２の反射防止層積層工程では、半導体基板１０の窒化を行うことにより、反射防止層４０を形成することができる。また、半導体基板１０の表面に反射防止層４０を形成する材料を積層することによって反射防止層４０を形成してもよい。 (Anti-reflection layer laminating process)
In the antireflection layer laminating step of step S2, the antireflection layer 40 can be formed by nitriding the semiconductor substrate 10. Further, the antireflection layer 40 may be formed by laminating a material for forming the antireflection layer 40 on the surface of the semiconductor substrate 10.
（パッシベーション層積層工程）
　ステップＳ３のパッシベーション層積層工程では、周知の成膜技術により半導体基板１０の第２主面にパッシベーション層５０を積層する。 (Passivation layer laminating process)
In the passivation layer laminating step of step S3, the passivation layer 50 is laminated on the second main surface of the semiconductor substrate 10 by a well-known film forming technique.
（第１収集電極積層工程）
　ステップＳ４の第１収集電極積層工程では、導電性ペーストの印刷及び焼成により、半導体基板１０の第１主面に第１収集電極２０を形成する。導電性ペーストの印刷方法としては、例えばスクリーン印刷を採用することができる。 (1st collection electrode laminating process)
In the first collecting electrode laminating step of step S4, the first collecting electrode 20 is formed on the first main surface of the semiconductor substrate 10 by printing and firing the conductive paste. As a printing method of the conductive paste, for example, screen printing can be adopted.
（第１接続電極積層工程）
　ステップＳ５の第１接続電極積層工程では、導電性ペーストの印刷及び焼成により、半導体基板１０の第１主面に、第１収集電極２０を接続するよう第２方向に延びる第１接続電極３０を形成する。この第１接続電極積層工程は、ステップＳ４の第１収集電極積層工程と同時に行うことが好ましい。つまり、導電性ペーストを第１収集電極２０と第１接続電極３０を含むパターンで半導体基板１０の表面に印刷し、焼成することにより、第１収集電極２０及び第１接続電極３０を一体に形成することが好ましい。 (First connection electrode laminating process)
In the first connection electrode laminating step of step S5, the first connection electrode 30 extending in the second direction so as to connect the first collection electrode 20 to the first main surface of the semiconductor substrate 10 is formed by printing and firing the conductive paste. Form. This first connection electrode laminating step is preferably performed at the same time as the first collecting electrode laminating step of step S4. That is, the first collecting electrode 20 and the first connecting electrode 30 are integrally formed by printing the conductive paste on the surface of the semiconductor substrate 10 in a pattern including the first collecting electrode 20 and the first connecting electrode 30 and firing the paste. It is preferable to do so.
（接続開口形成工程）
　ステップＳ６の接続開口形成工程では、レーザーの照射により、パッシベーション層５０を部分的に除去することで、接続開口５１を形成することができる。レーザーを第１方向に走査してストライプ状の接続開口５１を形成する場合、一般に、レーザー照射位置の第１方向の精度は、第２方向の精度と比べて低くなる。しかしながら、太陽電池１では接続開口５１が第１方向に連続して半導体基板１０の全長に亘って形成されるため、レーザー照射の第１方向の精度を考慮する必要がない。この接続開口５１はレーザーパルスが断続的に照射された、点線状であっても良い。この場合、点線を構成する点同士の間隔は、パルス周期とレーザー走査速度によって決定され、例えば０．１ｍｍ以上１ｍｍ以下とすることができる。 (Connection opening forming process)
In the connection opening forming step of step S6, the connection opening 51 can be formed by partially removing the passivation layer 50 by irradiating the laser. When the laser is scanned in the first direction to form the striped connection opening 51, the accuracy of the laser irradiation position in the first direction is generally lower than the accuracy in the second direction. However, in the solar cell 1, since the connection opening 51 is continuously formed in the first direction over the entire length of the semiconductor substrate 10, it is not necessary to consider the accuracy of the laser irradiation in the first direction. The connection opening 51 may be in the shape of a dotted line, which is intermittently irradiated with a laser pulse. In this case, the distance between the points forming the dotted line is determined by the pulse period and the laser scanning speed, and can be, for example, 0.1 mm or more and 1 mm or less.
（第２接続電極積層工程）
　ステップＳ７の第２接続電極積層工程では、電気抵抗が小さい導電性ペーストの印刷及び焼成により、パッシベーション層５０の第１方向に第１接続電極３０と反対側の端部領域に、第１方向に見て接続開口５１と重複しないよう第２方向に並んで複数の第２接続電極６０を積層する。前述の接続開口５１が点線状であった場合も、接続開口５１が連続線である場合と同様に、接続開口５１線が形成された線状乃至帯状の領域と重複しないように配置され、点線の点と点の間に第２接続電極６０が配置されることはない。点線における各点の位置（レーザーパルスのタイミング）は、厳密に制御されておらず、印刷版と整合させることは技術的に困難であり、またメリットも少ない。レーザー走査速度を低減することで、点の位置を向上させることは出来るが、生産性が悪くなりコスト増となってしまう。点線状にすることで、一つのレーザーパルスが一つの開口を形成することになるので、レーザーによる半導体基板１０への影響を制御することが容易になる。 (Second connection electrode laminating process)
In the second connection electrode laminating step of step S7, the conductive paste having a small electric resistance is printed and fired in the first direction of the passivation layer 50 in the end region opposite to the first connection electrode 30 in the first direction. A plurality of second connection electrodes 60 are laminated side by side in the second direction so as not to overlap with the connection opening 51. Even when the connection opening 51 is a dotted line, the connection opening 51 is arranged so as not to overlap the linear or band-shaped region in which the connection opening 51 line is formed, as in the case where the connection opening 51 is a continuous line. The second connection electrode 60 is not arranged between the points. The position of each point on the dotted line (laser pulse timing) is not strictly controlled, it is technically difficult to match with the printing plate, and there is little merit. By reducing the laser scanning speed, the position of the point can be improved, but the productivity is lowered and the cost is increased. By making it a dotted line, one laser pulse forms one aperture, so that it becomes easy to control the influence of the laser on the semiconductor substrate 10.
（第２収集電極積層工程）
　ステップＳ８の第２収集電極積層工程では、ベース領域１３との接続性に優れる導電性ペーストの印刷及び焼成により、接続開口５１内に露出する半導体基板１０（つまりベース領域１３）、パッシベーション層５０、及び第２接続電極６０に跨り、第２接続電極６０の中央部を露出するよう第２収集電極７０を積層する。第２接続電極６０と第２収集電極７０の積層幅は０．０５ｍｍ以上０．４ｍｍ以下であることが、材料使用効率及び両電極間の接続抵抗の観点から好ましい。第２収集電極７０は、個々の太陽電池１を分離するために半導体基板１０を切断する領域（分離後の太陽電池１の半導体基板１０の第１方向の両端部）の少なくとも接続開口５１の近傍領域以外の部分を露出することが好ましい。こうすることで、接続開口５１を第２収集電極７０で完全に被覆しつつ、端部近傍を被覆する第２収集電極７０を最小限にすることができる。 (Second collection electrode laminating process)
In the second collection electrode laminating step of step S8, the semiconductor substrate 10 (that is, the base region 13) exposed in the connection opening 51 by printing and firing of the conductive paste having excellent connectivity with the base region 13, the passivation layer 50, The second collecting electrode 70 is laminated so as to straddle the second connecting electrode 60 and expose the central portion of the second connecting electrode 60. The laminated width of the second connection electrode 60 and the second collection electrode 70 is preferably 0.05 mm or more and 0.4 mm or less from the viewpoint of material use efficiency and connection resistance between the two electrodes. The second collecting electrode 70 is at least in the vicinity of the connection opening 51 of the region where the semiconductor substrate 10 is cut to separate the individual solar cells 1 (both ends of the semiconductor substrate 10 of the solar cell 1 after separation in the first direction). It is preferable to expose the part other than the region. By doing so, the connection opening 51 can be completely covered with the second collecting electrode 70, and the second collecting electrode 70 covering the vicinity of the end portion can be minimized.
　印刷された導電性ペーストを焼成する際、導電性ペーストの金属が半導体基板１０の接続開口５１から露出する領域に拡散して合金化する。第２収集電極７０をアルミニウムペーストにより形成することで、半導体基板１０の第２主面を局所的にアルミシリサイドに変性してベース領域１３を形成することができる。 When the printed conductive paste is fired, the metal of the conductive paste diffuses into the exposed region from the connection opening 51 of the semiconductor substrate 10 and alloys. By forming the second collecting electrode 70 with an aluminum paste, the second main surface of the semiconductor substrate 10 can be locally modified to aluminum silicide to form the base region 13.
＜太陽電池モジュール＞
　続いて、図６及び７を参照しながら、太陽電池１を用い太陽電池モジュール１００について説明する。太陽電池モジュール１００は、本発明に係る太陽電池モジュールの一実施形態である。 <Solar cell module>
Subsequently, the solar cell module 100 will be described using the solar cell 1 with reference to FIGS. 6 and 7. The solar cell module 100 is an embodiment of the solar cell module according to the present invention.
　太陽電池モジュール１００は、図１乃至図４の太陽電池１を複数備える。太陽電池モジュール１００は、それぞれ複数の太陽電池１を接続して形成される複数の太陽電池ストリング１１０と、太陽電池ストリング１１０の表面側に配置される表側保護部材１２０と、太陽電池ストリング１１０の裏面側に配置される裏側保護部材１３０と、表側保護部材１２０及び裏側保護部材１３０間の隙間に充填される封止材１４０と、太陽電池ストリング間を接続する接続部材１５０と、を備える。 The solar cell module 100 includes a plurality of solar cells 1 of FIGS. 1 to 4. The solar cell module 100 includes a plurality of solar cell strings 110 formed by connecting a plurality of solar cells 1, a front side protective member 120 arranged on the front surface side of the solar cell string 110, and a back surface of the solar cell string 110. It includes a back side protective member 130 arranged on the side, a sealing material 140 filled in a gap between the front side protective member 120 and the back side protective member 130, and a connecting member 150 for connecting between the solar cell strings.
　太陽電池ストリング１１０は、複数の太陽電池１を第１方向の端部を重ねるシングリング方式で接続したものである。太陽電池ストリング１１０において、隣接し合う２つの太陽電池１間において、一方の太陽電池１の第１接続電極３０に、他方の太陽電池１の第２接続電極６０が、導電性接着剤、半田等の接続材料９９を用いて直接接続されている。太陽電池ストリング１１０を形成する際にＡｇを主材料とする接続材料９９がベース領域１３に直接触れると、暗電流が増加して性能が低下することがあるので、接続開口５１は第２収集電極７０で完全に覆われていることが好ましい。また、第１接続電極３０上の接続材料９９がはみだして反対側の主面に到達した場合であっても、第２収集電極７０に触れなければ短絡しないので、第１接続電極３０の裏面側の端部領域における第２収集電極７０の被覆面積はなるべく小さいことが好ましい。 The solar cell string 110 is formed by connecting a plurality of solar cells 1 by a single ring method in which the ends in the first direction are overlapped. In the solar cell string 110, between two adjacent solar cells 1, the first connection electrode 30 of one solar cell 1 and the second connection electrode 60 of the other solar cell 1 are connected to a conductive adhesive, solder, or the like. It is directly connected using the connection material 99 of. When the connecting material 99 containing Ag as the main material comes into direct contact with the base region 13 when forming the solar cell string 110, the dark current may increase and the performance may deteriorate. Therefore, the connection opening 51 is the second collecting electrode. It is preferably completely covered with 70. Further, even if the connecting material 99 on the first connecting electrode 30 protrudes and reaches the main surface on the opposite side, the short circuit does not occur unless the second collecting electrode 70 is touched, so that the back surface side of the first connecting electrode 30 is formed. It is preferable that the covering area of the second collecting electrode 70 in the end region of is as small as possible.
　太陽電池ストリング１１０において、太陽電池１は、半導体基板１０への光の入射を阻害する第１接続電極３０が設けられる端部領域に他の太陽電池１の光電変換に寄与する反対側の端部領域が重ねられる。このため、太陽電池ストリング１１０は、その全面が光電変換に寄与する。とりわけ、太陽電池ストリング１１０は、半導体基板１０の裏面側に第２接続電極６０が設けられる領域にも均等にベース領域１３が配設されている太陽電池１を用いることにより光電変換効率が低い部分がないので光電変換効率が高い。 In the solar cell string 110, the solar cell 1 has an opposite end portion that contributes to photoelectric conversion of another solar cell 1 in an end region provided with a first connection electrode 30 that inhibits light from entering the semiconductor substrate 10. Areas overlap. Therefore, the entire surface of the solar cell string 110 contributes to photoelectric conversion. In particular, the solar cell string 110 is a portion where the photoelectric conversion efficiency is low by using the solar cell 1 in which the base region 13 is evenly arranged in the region where the second connection electrode 60 is provided on the back surface side of the semiconductor substrate 10. Since there is no such thing, the photoelectric conversion efficiency is high.
　表側保護部材１２０は、封止材１４０を介して、太陽電池ストリング１１０、すなわち太陽電池１の第１主面を覆うことにより、太陽電池１を保護する。表側保護部材１２０は、板状またはシート状の材料から形成することができ、透光性及び対候性に優れることが好ましい。具体的には、表側保護部材１２０の材質としては、例えばアクリル樹脂若しくはポリカーボネート樹脂等の透明樹脂、ガラスなどを挙げることができる。また、表側保護部材１２０の表面は、光の反射を抑制するために、凹凸状に加工されたり、反射防止コーティング層で被覆されてもよい。 The front side protective member 120 protects the solar cell 1 by covering the solar cell string 110, that is, the first main surface of the solar cell 1 via the sealing material 140. The front side protective member 120 can be formed from a plate-shaped or sheet-shaped material, and is preferably excellent in translucency and weather resistance. Specifically, as the material of the front side protective member 120, for example, a transparent resin such as an acrylic resin or a polycarbonate resin, glass, or the like can be mentioned. Further, the surface of the front side protective member 120 may be processed into an uneven shape or coated with an antireflection coating layer in order to suppress the reflection of light.
　裏側保護部材１３０は、封止材１４０を介して、太陽電池ストリング１１０の裏面を覆って、太陽電池１を保護する。裏側保護部材１３０は、表側保護部材１２０と同様に、板状またはシート状の材料から形成することができ、遮水性に優れることが好ましい。具体的には、裏側保護部材１３０としては、例えばポリエチレンテレフタレート（ＰＥＴ）、ポリエチレン（ＰＥ）、オレフィン系樹脂、含フッ素樹脂、シリコーン樹脂等の樹脂フィルムと、アルミニウム箔等の金属箔との積層体が好適に用いられる。 The back side protective member 130 covers the back surface of the solar cell string 110 via the sealing material 140 to protect the solar cell 1. Like the front side protective member 120, the back side protective member 130 can be formed of a plate-like or sheet-like material, and is preferably excellent in water-shielding property. Specifically, the back side protective member 130 is a laminate of, for example, a resin film such as polyethylene terephthalate (PET), polyethylene (PE), an olefin resin, a fluorine-containing resin, or a silicone resin, and a metal foil such as aluminum foil. Is preferably used.
　封止材１４０は、太陽電池ストリング１１０、すなわち太陽電池１を封止して保護するもので、太陽電池１の受光側の面と表側保護部材１２０との間、及び太陽電池１の裏側の面と裏側保護部材１３０との間に介在する。 The sealing material 140 seals and protects the solar cell string 110, that is, the solar cell 1, is between the light receiving side surface of the solar cell 1 and the front side protective member 120, and the back surface of the solar cell 1. It is interposed between the back side protective member 130 and the back side protective member 130.
　封止材１４０は、太陽電池ストリング１１０と表側保護部材１２０及び裏側保護部材１３０とを接着すると共に、太陽電池ストリング１１０の周囲の隙間をなくすことで、太陽電池１を保護する。このため、封止材１４０としては、例えば、エチレン／酢酸ビニル共重合体（ＥＶＡ）、エチレン／α－オレフィン共重合体、エチレン／酢酸ビニル／トリアリルイソシアヌレート（ＥＶＡＴ）、ポリビニルブチラート（ＰＶＢ）、アクリル樹脂、ウレタン樹脂、または、シリコーン樹脂等の透光性を有する熱可塑性樹脂が好適に用いられる。 The sealing material 140 protects the solar cell 1 by adhering the solar cell string 110 to the front side protective member 120 and the back side protective member 130 and eliminating the gap around the solar cell string 110. Therefore, examples of the sealing material 140 include ethylene / vinyl acetate copolymer (EVA), ethylene / α-olefin copolymer, ethylene / vinyl acetate / triallyl isocyanurate (EVAT), and polyvinyl butyral (PVB). ), Acrylic resin, urethane resin, or a translucent thermoplastic resin such as silicone resin is preferably used.
　接続部材１５０は、太陽電池ストリング１１０の一端の太陽電池１の第１接続電極３０間と、太陽電池ストリング１１０の他端の太陽電池１の第２接続電極６０間をそれぞれ接続する。接続部材１５０は、太陽電池モジュール１００の外部の回路に接続可能に、表側保護部材１２０及び裏側保護部材１３０の間から外側に延出している。 The connecting member 150 connects between the first connection electrodes 30 of the solar cell 1 at one end of the solar cell string 110 and between the second connection electrodes 60 of the solar cell 1 at the other end of the solar cell string 110, respectively. The connecting member 150 extends outward from between the front side protective member 120 and the back side protective member 130 so that it can be connected to the external circuit of the solar cell module 100.
　太陽電池モジュール１００は、光電変換効率が高い太陽電池１を用いた太陽電池ストリング１１０を備えるため、光電変換効率が高い。 Since the solar cell module 100 includes a solar cell string 110 using the solar cell 1 having high photoelectric conversion efficiency, the photoelectric conversion efficiency is high.
　続いて、図８に、本発明の第２実施形態に係る太陽電池１Ａを示す。図８の太陽電池１Ａは、図１の太陽電池１に換えて図７の太陽電池モジュール１００に用いることができる。図８の太陽電池１Ａについて、図１の太陽電池１と同様の構成要素には同じ符号を付して重複する説明を省略する。 Subsequently, FIG. 8 shows the solar cell 1A according to the second embodiment of the present invention. The solar cell 1A of FIG. 8 can be used for the solar cell module 100 of FIG. 7 instead of the solar cell 1 of FIG. Regarding the solar cell 1A of FIG. 8, the same components as those of the solar cell 1 of FIG. 1 are designated by the same reference numerals, and redundant description will be omitted.
　図８の太陽電池１Ａは、図１の太陽電池１の第２収集電極７０とは異なる平面形状を有する第２収集電極７０Ａを備える。つまり、図８の太陽電池１Ａは、図１の太陽電池１の第２収集電極７０を平面形状が異なる第２収集電極７０Ａに置き換えたものである。 The solar cell 1A of FIG. 8 includes a second collecting electrode 70A having a planar shape different from that of the second collecting electrode 70 of the solar cell 1 of FIG. That is, in the solar cell 1A of FIG. 8, the second collecting electrode 70 of the solar cell 1 of FIG. 1 is replaced with a second collecting electrode 70A having a different planar shape.
　第２収集電極７０Ａは、接続開口５１内に露出するベース領域１３、第２接続電極６０及びパッシベーション層５０の第２接続電極６０近傍領域を覆うよう選択的に積層されている。第２収集電極７０Ａのベース領域１３を覆う部分は、製造誤差を考慮して、接続開口５１内のベース領域１３を露出させない程度に、パッシベーション層５０の接続開口５１近傍領域を覆っている。 The second collection electrode 70A is selectively laminated so as to cover the base region 13, the second connection electrode 60, and the region near the second connection electrode 60 of the passivation layer 50 exposed in the connection opening 51. The portion of the second collecting electrode 70A that covers the base region 13 covers the region near the connection opening 51 of the passivation layer 50 to the extent that the base region 13 in the connection opening 51 is not exposed in consideration of manufacturing errors.
　太陽電池１Ａは、裏面側の第２収集電極７０Ａが配置されていない部分からも光を取り込むことができるので、使用する環境によっては出力を向上することができる。また、太陽電池１Ａは、第２収集電極７０Ａを形成する材料の使用量が比較的少ないため、安価に提供することができる。 Since the solar cell 1A can take in light even from the portion where the second collection electrode 70A on the back surface side is not arranged, the output can be improved depending on the environment in which it is used. Further, the solar cell 1A can be provided at low cost because the amount of the material used to form the second collection electrode 70A is relatively small.
　以上、本発明の実施形態について説明したが、本発明は上述した実施形態に限定されることなく、種々の変更及び変形が可能である。 Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications and modifications can be made.
　１，１Ａ　太陽電池
　１０　半導体基板
　１１　基材層
　１２　エミッタ層
　１３　ベース領域
　２０　第１収集電極
　３０　第１接続電極
　４０　反射防止層
　５０　パッシベーション層
　５１　接続開口
　６０　第２接続電極
　７０，７０Ａ　第２収集電極
　１００　太陽電池モジュール
　１１０　太陽電池ストリング
　１２０　表側保護部材
　１３０　裏側保護部材
　１４０　封止材
　１５０　接続部材 1,1A Solar cell 10 Semiconductor substrate 11 Base material layer 12 Emitter layer 13 Base region 20 First collection electrode 30 First connection electrode 40 Anti-reflection layer 50 Passivation layer 51 Connection opening 60 Second connection electrode 70, 70A Second collection electrode 100 Solar cell module 110 Solar cell string 120 Front side protective member 130 Back side protective member 140 Encapsulant 150 Connection member

Claims (6)

  1. 　第１主面及び第２主面を有する板状に形成され、前記第２主面にその全長に亘ってそれぞれ第１方向に沿うよう互いに間隔を空けて平行に配置された複数のベース領域を有する半導体基板と、
    　前記半導体基板の前記第１主面に配置され、前記第１方向に延びる複数の第１収集電極と、
    　前記半導体基板の前記第１主面の前記第１方向の一方の端部領域に配置され、前記複数の第１収集電極を接続するよう前記第１方向に交差する第２方向に延びる第１接続電極と、
    　前記半導体基板の前記第２主面に積層され、前記ベース領域をそれぞれ露出する複数の接続開口が形成されたパッシベーション層と、
    　前記パッシベーション層の前記第１方向に前記第１接続電極と反対側の端部領域に、前記第１方向に見て前記接続開口と重複しないよう前記第２方向に並んで積層される複数の第２接続電極と、
    　前記接続開口内に露出する前記ベース領域、前記パッシベーション層、及び前記第２接続電極に跨って積層され、前記第２接続電極の中央部を露出する第２収集電極と、
    を備える、太陽電池。     A plurality of base regions formed in a plate shape having a first main surface and a second main surface, and arranged in parallel with each other at intervals along the first direction over the entire length of the second main surface. With the semiconductor substrate
    A plurality of first collecting electrodes arranged on the first main surface of the semiconductor substrate and extending in the first direction,
    A first connection arranged in one end region of the first main surface of the semiconductor substrate in the first direction and extending in a second direction intersecting the first direction so as to connect the plurality of first collection electrodes. With electrodes
    A passivation layer laminated on the second main surface of the semiconductor substrate and formed with a plurality of connection openings each exposing the base region.
    A plurality of second layers of the passivation layer are laminated side by side in the second direction in the end region opposite to the first connection electrode in the first direction so as not to overlap with the connection opening when viewed in the first direction. 2 connection electrodes and
    A second collecting electrode that is laminated over the base region exposed in the connection opening, the passivation layer, and the second connecting electrode and exposes the central portion of the second connecting electrode.
    With a solar cell.
  2. 　前記第２収集電極は、前記第１方向の両端部において、前記パッシベーション層の端部を露出する、請求項１に記載の太陽電池。 The solar cell according to claim 1, wherein the second collecting electrode exposes the ends of the passivation layer at both ends in the first direction.
  3. 　前記第２収集電極は、前記半導体基板の前記第１方向の両端部において、前記接続開口を選択的に被覆する、請求項２に記載の太陽電池。 The solar cell according to claim 2, wherein the second collecting electrode selectively covers the connection opening at both ends of the semiconductor substrate in the first direction.
  4. 　前記第２接続電極は複数の銀粒子とバインダとを含み、前記第２収集電極は複数のアルミニウム粒子とバインダとを含む、請求項１から３のいずれかに記載の太陽電池。 The solar cell according to any one of claims 1 to 3, wherein the second connecting electrode contains a plurality of silver particles and a binder, and the second collecting electrode contains a plurality of aluminum particles and a binder.
  5. 　請求項１から４のいずれかに記載の太陽電池を複数備え、
    　前記太陽電池の前記第１接続電極に他の前記太陽電池の前記第２接続電極が直接接続されている、太陽電池モジュール。     A plurality of solar cells according to any one of claims 1 to 4 are provided.
    A solar cell module in which the second connection electrode of another solar cell is directly connected to the first connection electrode of the solar cell.
  6. 　第１主面及び第２主面を有する半導体基板の前記第２主面にパッシベーション層を積層する工程と、
    　前記半導体基板の前記第１主面に、第１方向に延びる複数の第１収集電極を積層する工程と、
    　前記半導体基板の前記第１主面の前記第１方向の一方の端部領域に、前記複数の第１収集電極を接続するよう前記第１方向に交差する第２方向に延びる第１接続電極を積層する工程と、
    　レーザーの照射により、前記パッシベーション層に、前記半導体基板の全長に亘って、それぞれ前記第１方向に沿うよう、互いに間隔を空けて平行に配置される複数の接続開口を形成する工程と、
    　前記パッシベーション層の前記第１方向に前記第１接続電極と反対側の端部領域に、前記第１方向にみて前記接続開口と重複しないよう前記第２方向に並んで複数の第２接続電極を積層する工程と、
    　前記接続開口内に露出する前記半導体基板、前記パッシベーション層、及び前記第２接続電極に跨り、前記第２接続電極の中央部を露出する第２収集電極を積層する工程と、
    を備える、太陽電池の製造方法。     A step of laminating a passivation layer on the second main surface of a semiconductor substrate having a first main surface and a second main surface, and
    A step of laminating a plurality of first collecting electrodes extending in the first direction on the first main surface of the semiconductor substrate, and
    A first connection electrode extending in a second direction intersecting the first direction so as to connect the plurality of first collection electrodes to one end region of the first main surface of the semiconductor substrate in the first direction. The process of laminating and
    A step of forming a plurality of connection openings arranged in parallel with each other at intervals along the first direction over the entire length of the semiconductor substrate in the passivation layer by irradiating the laser.
    A plurality of second connection electrodes are arranged in the second direction so as not to overlap with the connection opening in the first direction in the end region opposite to the first connection electrode in the first direction of the passivation layer. The process of laminating and
    A step of laminating a second collecting electrode that exposes a central portion of the second connection electrode straddling the semiconductor substrate, the passivation layer, and the second connection electrode exposed in the connection opening.
    A method of manufacturing a solar cell.
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