CN116799075A - Photovoltaic cell and preparation method thereof - Google Patents
Photovoltaic cell and preparation method thereof Download PDFInfo
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- CN116799075A CN116799075A CN202310957149.8A CN202310957149A CN116799075A CN 116799075 A CN116799075 A CN 116799075A CN 202310957149 A CN202310957149 A CN 202310957149A CN 116799075 A CN116799075 A CN 116799075A
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- 238000002360 preparation method Methods 0.000 title abstract description 4
- 229910021420 polycrystalline silicon Inorganic materials 0.000 claims abstract description 122
- 229920005591 polysilicon Polymers 0.000 claims abstract description 122
- 239000000758 substrate Substances 0.000 claims abstract description 93
- 238000002161 passivation Methods 0.000 claims abstract description 73
- 230000005641 tunneling Effects 0.000 claims abstract description 67
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims abstract description 33
- 229910052760 oxygen Inorganic materials 0.000 claims abstract description 33
- 239000001301 oxygen Substances 0.000 claims abstract description 33
- 238000000034 method Methods 0.000 claims description 28
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 claims description 22
- 239000002003 electrode paste Substances 0.000 claims description 17
- 238000005245 sintering Methods 0.000 claims description 13
- 229910002092 carbon dioxide Inorganic materials 0.000 claims description 11
- 239000001569 carbon dioxide Substances 0.000 claims description 11
- 238000000623 plasma-assisted chemical vapour deposition Methods 0.000 claims description 11
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 claims description 6
- 229910052698 phosphorus Inorganic materials 0.000 claims description 6
- 239000011574 phosphorus Substances 0.000 claims description 6
- 239000004973 liquid crystal related substance Substances 0.000 claims description 4
- 238000004519 manufacturing process Methods 0.000 claims description 3
- 238000010521 absorption reaction Methods 0.000 abstract description 12
- 230000003071 parasitic effect Effects 0.000 abstract description 12
- 239000010410 layer Substances 0.000 description 152
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 8
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 8
- 229910052710 silicon Inorganic materials 0.000 description 8
- 239000010703 silicon Substances 0.000 description 8
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 description 7
- 230000000052 comparative effect Effects 0.000 description 7
- 229910052709 silver Inorganic materials 0.000 description 7
- 239000004332 silver Substances 0.000 description 7
- 239000005388 borosilicate glass Substances 0.000 description 6
- 239000000463 material Substances 0.000 description 6
- 229910052814 silicon oxide Inorganic materials 0.000 description 6
- 229910052581 Si3N4 Inorganic materials 0.000 description 5
- 238000009792 diffusion process Methods 0.000 description 5
- HQVNEWCFYHHQES-UHFFFAOYSA-N silicon nitride Chemical compound N12[Si]34N5[Si]62N3[Si]51N64 HQVNEWCFYHHQES-UHFFFAOYSA-N 0.000 description 5
- 238000004140 cleaning Methods 0.000 description 4
- 238000000151 deposition Methods 0.000 description 4
- 230000008021 deposition Effects 0.000 description 4
- 238000005215 recombination Methods 0.000 description 4
- 230000006798 recombination Effects 0.000 description 4
- 239000004065 semiconductor Substances 0.000 description 4
- ZOXJGFHDIHLPTG-UHFFFAOYSA-N Boron Chemical compound [B] ZOXJGFHDIHLPTG-UHFFFAOYSA-N 0.000 description 3
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 3
- 229910052782 aluminium Inorganic materials 0.000 description 3
- 230000015572 biosynthetic process Effects 0.000 description 3
- 229910052796 boron Inorganic materials 0.000 description 3
- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- 238000002834 transmittance Methods 0.000 description 3
- 229910004205 SiNX Inorganic materials 0.000 description 2
- BLRPTPMANUNPDV-UHFFFAOYSA-N Silane Chemical compound [SiH4] BLRPTPMANUNPDV-UHFFFAOYSA-N 0.000 description 2
- 238000005229 chemical vapour deposition Methods 0.000 description 2
- 239000011267 electrode slurry Substances 0.000 description 2
- 238000005286 illumination Methods 0.000 description 2
- 239000011810 insulating material Substances 0.000 description 2
- 238000007747 plating Methods 0.000 description 2
- 238000007639 printing Methods 0.000 description 2
- 229910000077 silane Inorganic materials 0.000 description 2
- 239000002253 acid Substances 0.000 description 1
- 239000003513 alkali Substances 0.000 description 1
- 238000000137 annealing Methods 0.000 description 1
- 230000003667 anti-reflective effect Effects 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000008020 evaporation Effects 0.000 description 1
- 238000001704 evaporation Methods 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 230000001590 oxidative effect Effects 0.000 description 1
- 238000007650 screen-printing Methods 0.000 description 1
- 235000012239 silicon dioxide Nutrition 0.000 description 1
- 239000000377 silicon dioxide Substances 0.000 description 1
- 238000004544 sputter deposition Methods 0.000 description 1
- 239000002344 surface layer Substances 0.000 description 1
Classifications
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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
- H01L31/0216—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
- H01L31/022408—Electrodes for devices characterised by at least one potential jump barrier or surface barrier
- H01L31/022425—Electrodes for devices characterised by at least one potential jump barrier or surface barrier for solar cells
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L31/04—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 adapted as photovoltaic [PV] conversion devices
- H01L31/06—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 adapted as photovoltaic [PV] conversion devices characterised by potential barriers
-
- 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
- H01L31/18—Processes or apparatus specially adapted for the manufacture or treatment of these devices or of parts thereof
- H01L31/186—Particular post-treatment for the devices, e.g. annealing, impurity gettering, short-circuit elimination, recrystallisation
- H01L31/1868—Passivation
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- Engineering & Computer Science (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Physics & Mathematics (AREA)
- Condensed Matter Physics & Semiconductors (AREA)
- Electromagnetism (AREA)
- General Physics & Mathematics (AREA)
- Computer Hardware Design (AREA)
- Power Engineering (AREA)
- Sustainable Development (AREA)
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Abstract
The invention provides a photovoltaic cell and a preparation method thereof, belongs to the technical field of photovoltaic cells, and can at least partially solve the problems that the parasitic absorption of the existing photovoltaic cell is high, or a doped polysilicon layer is easy to burn through. The photovoltaic cell of the present invention comprises: a substrate; a passivation contact structure located on one side of the substrate; the passivation contact structure comprises a plurality of stacked substructures, each substructure comprises a tunneling sublayer and a doped polysilicon sublayer positioned on one side of the tunneling sublayer, which is away from the substrate, wherein the doped polysilicon sublayer contains oxygen; an insulating layer positioned on one side of the passivation contact structure away from the substrate; and a first electrode positioned on one side of the passivation contact structure away from the substrate, the first electrode passing through the insulating layer and a part of the passivation contact structure to be in contact with a tunneling sublayer closest to the substrate in the passivation contact structure.
Description
Technical Field
The invention belongs to the technical field of photovoltaic cells, and particularly relates to a photovoltaic cell and a preparation method thereof.
Background
The tunneling oxide layer passivation contact photovoltaic cell (TOPCon, tunnel Oxide Passivating Contacts) has the advantages of less indirect recombination (SHR recombination), low contact resistance, high efficiency and the like.
But the backlight side of TOPCon photovoltaic cells needs to be covered with a doped polysilicon layer (Poly-Si), which can lead to high parasitic absorption or to the doped polysilicon layer being prone to burn-through.
Disclosure of Invention
The invention at least partially solves the problems of high parasitic absorption or easy burning-through of a doped polysilicon layer of the existing photovoltaic cell, and provides a method for preparing the photovoltaic cell.
In a first aspect, embodiments of the present invention provide a photovoltaic cell comprising:
a substrate;
a passivation contact structure located on one side of the substrate; the passivation contact structure comprises a plurality of stacked substructures, each substructure comprises a tunneling sublayer and a doped polysilicon sublayer positioned on one side of the tunneling sublayer, which is away from the substrate, wherein the doped polysilicon sublayer contains oxygen;
an insulating layer positioned on one side of the passivation contact structure away from the substrate;
and a first electrode positioned on one side of the passivation contact structure away from the substrate, the first electrode passing through the insulating layer and a part of the passivation contact structure to be in contact with a tunneling sublayer closest to the substrate in the passivation contact structure.
Optionally, the mass percentage of oxygen in the doped polysilicon sub-layer is between 2% and 30%.
Optionally, in any two doped polysilicon sublayers, the content of oxygen in the doped polysilicon sublayers farther from the substrate is higher than the content of oxygen in the doped polysilicon sublayers closer to the substrate.
Optionally, the doped polysilicon sub-layer further contains phosphorus.
Optionally, the doped polysilicon sub-layer closest to the substrate has a thickness between 20nm and 40 nm; the total thickness of all the doped polysilicon sublayers is between 50nm and 120 nm.
Optionally, the tunneling sublayer closest to the substrate has a thickness between 1nm and 2nm; the total thickness of all the tunneling sublayers is between 2nm and 7 nm.
Optionally, the number of the substructures is two; wherein, the liquid crystal display device comprises a liquid crystal display device,
in the substructure closer to the substrate, the doped polysilicon sub-layer has a thickness of 20nm to 30nm and the tunneling sub-layer has a thickness of 1nm to 2nm;
in the substructure further from the substrate, the doped polysilicon sub-layer has a thickness of 30nm to 60nm and the tunneling sub-layer has a thickness of between 1nm and 5nm.
Optionally, the photovoltaic cell is a tunneling oxide passivation contact photovoltaic cell;
the passivation contact structure is located on a backlight side of the substrate.
In a second aspect, embodiments of the present invention provide a method of preparing a photovoltaic cell, comprising:
forming a passivation contact structure on one side of the substrate; the passivation contact structure comprises a plurality of stacked substructures, each substructure comprises a tunneling sublayer and a doped polysilicon sublayer arranged on one side of the tunneling sublayer, which is far away from the substrate, wherein the doped polysilicon sublayer contains oxygen;
forming an insulating layer on the passivation contact structure;
disposing an electrode paste on the insulating layer;
sintering is performed to form the electrode paste into a first electrode that passes through the insulating layer and a portion of the passivation contact structure to contact a tunneling sublayer of the passivation contact structure closest to the substrate.
Optionally, the forming the passivation contact structure on the substrate side includes:
the doped polysilicon sub-layer is formed by plasma enhanced chemical vapor deposition, wherein the process atmosphere used contains carbon dioxide.
In the embodiment of the invention, the doped polysilicon sub-layer contains oxygen, so that the light transmittance of the doped polysilicon sub-layer is improved, the parasitic absorption can be reduced, and meanwhile, the burn-through resistance of the doped polysilicon sub-layer is also improved, so that the doped polysilicon sub-layer is less prone to being burnt through, and the sintering time and the sintering temperature of the electrode slurry have larger windows; by arranging the doped polysilicon sublayers and the tunneling sublayers, the total thickness of the doped polysilicon sublayers can be further reduced under the condition that the doped polysilicon sublayers closest to the substrate are not burnt, parasitic absorption is better reduced, and the battery efficiency is improved.
Drawings
FIG. 1 is a schematic cross-sectional view of a photovoltaic cell of the related art;
fig. 2 is a schematic cross-sectional view of a photovoltaic cell according to an embodiment of the present invention;
fig. 3 is a schematic cross-sectional structural view of another photovoltaic cell according to an embodiment of the present invention;
fig. 4 is a schematic flow chart of a method for preparing a photovoltaic cell according to an embodiment of the present invention.
Wherein, the reference numerals are as follows: 1. passivating the contact structure; 11. a substructure; 111. tunneling sublayers; 112. doping the polysilicon sub-layer; 2. an insulating layer; 31. a first electrode; 32. a second electrode; 41. a lightly doped region; 42. a heavily doped region; 5. a passivation layer; 71. a tunneling layer; 72. a doped polysilicon layer; 9. a substrate.
Detailed Description
The present invention will be described in further detail below with reference to the drawings and detailed description for the purpose of better understanding of the technical solution of the present invention to those skilled in the art.
It is to be understood that the specific embodiments and figures described herein are merely illustrative of the invention, and are not limiting of the invention.
It is to be understood that the various embodiments of the invention and the features of the embodiments may be combined with each other without conflict.
It is to be understood that, for convenience of description, only portions related to the embodiments of the present invention are shown in the drawings, and portions unrelated to the embodiments of the present invention are not shown in the drawings.
The photovoltaic cell (solar cell) is a device for converting illumination into electric energy, has the advantages of cleanness, safety, abundant resources and the like, and is one of important modes for utilizing renewable energy.
Referring to fig. 1, one of the photovoltaic cells is a tunneling oxide passivation contact photovoltaic cell (TOPCon, tunnel Oxide Passivating Contacts), the back light side of the substrate 9 of the TOPCon photovoltaic cell is sequentially provided with a tunneling layer 71 (such as a silicon oxide layer), a doped polysilicon layer 72 (Poly-Si), an insulating layer 2 (such as a silicon nitride anti-reflection layer), and a first electrode 31 (a gate line, such as a negative electrode) formed by sintering an electrode paste (such as silver paste, aluminum paste) on the insulating layer 2, wherein the first electrode 31 needs to be burned through the insulating layer 2 to contact the doped polysilicon layer 72; the structure forms selective passivation contact, thereby reducing indirect recombination (SHR recombination) and contact resistance, and improving battery efficiency (the highest efficiency can reach more than 26.8 percent, and the mass production efficiency can reach more than 24.5 percent).
However, referring to fig. 1, the doped polysilicon layer 72 has poor light transmittance and severe parasitic absorption, thus limiting further improvement in cell efficiency; although parasitic absorption of the doped polysilicon layer 72 can be reduced by reducing the thickness thereof, since the first electrode 31 needs to burn through the insulating layer 2 to be in contact with the doped polysilicon layer 72, if the doped polysilicon layer 72 is too thin, burn-through resistance is insufficient, and the first electrode 31 is easily burned through by high-temperature electrode paste during sintering, resulting in incorrect cell structure passing through the doped polysilicon layer 72 to be in contact with the tunneling layer 71 or the substrate 9.
In a first aspect, referring to fig. 2, an embodiment of the present invention provides a photovoltaic cell, comprising:
a substrate 9;
a passivation contact structure 1 located on one side of the substrate 9; the passivation contact structure 1 comprises a plurality of stacked sub-structures 11, each sub-structure 11 comprising a tunneling sub-layer 111 and a doped polysilicon sub-layer 112 located on the side of the tunneling sub-layer 111 facing away from the substrate 9, the doped polysilicon sub-layer 112 containing oxygen;
an insulating layer 2 on the side of the passivation contact structure 1 facing away from the substrate 9;
the first electrode 31, which is located on the side of the passivation contact structure 1 facing away from the substrate 9, is in contact with the tunneling sublayer 111 of the passivation contact structure 1 closest to the substrate 9, through the insulating layer 2 and a part of the passivation contact structure 1.
Among them, photovoltaic cells, also called solar cells, are devices capable of converting illumination into electrical energy.
The main body of the photovoltaic cell is a substrate 9 of semiconductor material (such as an N-type silicon wafer); while the substrate 9 has two opposite main surfaces, for example a light entry side for being arranged towards sunlight and a backlight side facing away from the light entry side.
In the embodiment of the present invention, a specific passivation contact structure 1 is provided on one side (the lower side in fig. 2, for example) of the substrate 9, and the passivation contact structure 1 includes a plurality of stacked sub-structures 11, and each sub-structure 11 includes a stacked tunneling sub-layer 111 and a doped polysilicon sub-layer 112, where the tunneling sub-layer 111 is closer to the substrate 9, and thus, there are a plurality of tunneling sub-layers 111 and doped polysilicon sub-layers 112 that are "arranged in turn" on one side of the substrate 9.
The tunneling sub-layer 111 is made of an insulating oxide material, but has a thin thickness so as to be conductive by a tunneling effect, for example, the tunneling sub-layer 111 may be a silicon oxide (SiOx) layer.
The doped polysilicon sub-layer 112 is made of polysilicon (Poly-Si) material doped into P-type or N-type semiconductor, and the doped polysilicon sub-layer 112 further contains oxygen (O) element.
It should be appreciated that due to the oxygen content, a portion of the silicon element in the doped polysilicon sub-layer 112 may actually be present in the form of silicon oxide (SiOx), i.e., the doped polysilicon sub-layer 112 may also be considered to contain a certain amount of silicon oxide.
An insulating layer 2 is also provided on the side of the passivation contact 1 facing away from the substrate 9, which insulating layer 2 is composed of an insulating material, for example an anti-reflective layer of silicon nitride (SiNx) material.
The insulating layer 2 is provided with a first electrode 31 (a gate line, e.g. a negative electrode) on the side facing away from the substrate 9. The first electrode 31 is formed by sintering an electrode paste (e.g. silver paste, aluminum paste) provided on the insulating layer 2, which electrode paste during sintering passes through the insulating layer 2 and part of the sub-layers in the passivation contact structure 1 above, so that the finally formed first electrode 31 is located on the insulating layer 2 but passes through both the insulating layer 2 and part of the sub-layers of the passivation contact structure 1 and is in contact with the doped polysilicon sub-layer 112 closest to the substrate 9 (but does not pass through the doped polysilicon sub-layer 112).
In the embodiment of the invention, the doped polysilicon sub-layer 112 contains oxygen, so that the light transmittance is improved, the parasitic absorption can be reduced, and meanwhile, the burn-through resistance of the doped polysilicon sub-layer 112 is also improved, so that the doped polysilicon sub-layer is less prone to burn through, and the sintering time and the sintering temperature of the electrode paste have larger windows; by providing a plurality of doped polysilicon sublayers 112 and tunneling sublayers 111, the total thickness of the doped polysilicon sublayers 112 can be further reduced, parasitic absorption can be better reduced, and battery efficiency can be improved under the condition that the doped polysilicon sublayers 112 closest to the substrate 9 are not burnt through.
Optionally, the photovoltaic cell is a tunneling oxide passivation contact photovoltaic cell; the passivation contact structure 1 is located on the backlight side of the substrate 9.
As a way of embodiment of the invention, referring to fig. 3, the above photovoltaic cell may be in particular in the form of a TOPCon photovoltaic cell, and correspondingly, the passivation contact structure 1 is provided on the backlight side of the substrate 9.
It should be understood that other structures may also be included in the TOPCon photovoltaic cell.
For example, referring to fig. 3, the light-entering side of the substrate 9 may be textured by texturing; the surface layer of the substrate 9 on the light incident side may be a lightly doped region 41 (e.g., a P-type lightly doped region) to form a PN junction with other portions of the substrate 9; the substrate 9 is covered with a passivation layer 5, for example, a layer of insulating material such as silicon nitride (SiNx) or aluminum oxide (AlOx), on the light incident side; a second electrode 32 (e.g., a positive electrode) is formed outside the passivation layer 5, the second electrode 32 is burnt through the passivation layer 5 to contact the surface of the substrate 9, and a local area of the surface of the substrate 9 contacting the second electrode 32 is a heavily doped region 42 (e.g., a P-type heavily doped region).
Optionally, the mass percentage of oxygen in the doped polysilicon sub-layer 112 is between 2% and 30%.
As a way of implementing embodiments of the present invention, the oxygen content in the optionally doped polysilicon sub-layer 112 may be in the range of 2 to 30wt%, and further may be in the range of 5 to 20wt%.
Optionally, in any two doped polysilicon sublayers 112, the oxygen content in the doped polysilicon sublayers 112 farther from the substrate 9 is higher than the oxygen content in the doped polysilicon sublayers 112 closer to the substrate 9.
As a way of implementing an embodiment of the invention, it may be that the more "outer (away from the substrate 9)" the higher the oxygen content in the doped polysilicon sub-layer 112. It has been found that such oxygen distribution can further improve the burn-through resistance of the doped polysilicon sub-layer 112 as a whole, thereby allowing the overall thickness of the doped polysilicon sub-layer 112 to be further reduced to further reduce parasitic absorption and improve cell efficiency.
Optionally, the doped polysilicon sub-layer 112 also contains phosphorus.
As a way of implementing the embodiment of the present invention, the doped polysilicon sub-layer 112 may be specifically phosphorus (P) -doped, and thus be an N-type semiconductor (i.e., the same type of semiconductor as the substrate 9).
Optionally, the doped polysilicon sub-layer 112 closest to the substrate 9 has a thickness between 20nm and 40 nm; the total thickness of all doped polysilicon sublayers 112 is between 50nm and 120 nm.
As a way of embodiment of the present invention, the thickness of the innermost doped polysilicon sub-layer 112 may be 20-40 nm, and may further be 25-35 nm; the total thickness of all doped polysilicon sublayers 112 may be 50-120 nm, and further may be 60-100 nm.
The doped polysilicon sub-layer 112 in the above thickness range can ensure good burn-through resistance, and has lower total thickness and less parasitic absorption.
Optionally, the tunneling sublayer 111 closest to the substrate 9 has a thickness between 1nm and 2nm; the total thickness of all tunneling sublayers 111 is between 2nm and 7 nm.
As a way of the embodiment of the present invention, the thickness of the innermost tunneling sublayer 111 may be 1-2 nm, and further may be 1.2-1.7 nm, so as to ensure that tunneling may be achieved; the total thickness of each tunneling sublayer 111 may be 2-7 nm, and further may be 3-6 nm.
Alternatively, the number of the substructures 11 is two; wherein, in the substructure 11 closer to the substrate 9, the doped polysilicon sub-layer 112 has a thickness of 20nm to 30nm, and the tunneling sub-layer 111 has a thickness of 1nm to 2nm; in the substructure 11 further from the substrate 9, the doped polysilicon sub-layer 112 has a thickness of 30nm to 60nm and the tunneling sub-layer 111 has a thickness of between 1nm and 5nm.
Referring to fig. 2, as a way of implementing the embodiment of the present invention, the sub-structure 11 may be specifically two, that is, the passivation contact structure 1 includes two doped polysilicon sub-layers 112 and two tunneling sub-layers 111 in total.
Further, in this case, the thickness of the doped polysilicon sub-layer 112 on the inner side (near the substrate 9) may be 20-30 nm, the oxygen content thereof may be low, 2-10 wt%, and the thickness of the tunneling sub-layer 111 may be 1-2 nm; in contrast, the thickness of the doped polysilicon sub-layer 112 and the tunneling sub-layer 111 on the outer side (farther from the substrate 9) may be slightly larger, the thickness of the doped polysilicon sub-layer 112 may be 30-60 nm, the oxygen content thereof may be higher, 15-30 wt%, and the thickness of the tunneling sub-layer 111 may be 1-5 nm.
In a second aspect, referring to fig. 2 to 4, an embodiment of the present invention provides a method for manufacturing a photovoltaic cell.
The method of the embodiment of the invention is used for preparing any one of the photovoltaic cells of the embodiment of the invention.
Referring to fig. 4, a method for preparing a photovoltaic cell according to an embodiment of the present invention includes:
s201, forming passivation contact structure 1 on the substrate 9 side.
The passivation contact structure 1 includes a plurality of stacked sub-structures 11, each sub-structure 11 includes a tunneling sub-layer 111 and a doped polysilicon sub-layer 112 disposed on a side of the tunneling sub-layer 111 facing away from the substrate 9, and the doped polysilicon sub-layer 112 contains oxygen.
S202, an insulating layer 2 is formed on the passivation contact structure 1.
And S203, disposing electrode slurry on the insulating layer 2.
S204, sintering is performed to form the electrode paste into the first electrode 31 passing through the insulating layer 2 and a portion of the passivation contact structure 1 to be in contact with the tunneling sublayer 111 closest to the substrate 9 in the passivation contact structure 1.
When the photovoltaic cell of the embodiment of the present invention is manufactured, the passivation contact structure 1 is formed on one side (such as the backlight side) of the substrate 9, that is, a plurality of tunneling sublayers 111 and doped polysilicon sublayers 112 are sequentially formed on the substrate 9 in turn; thereafter, an insulating layer 2 is formed on the doped polysilicon sub-layer 112 on the outermost side of the passivation contact structure 1; electrode paste (such as silver paste and aluminum paste) is arranged on the insulating layer 2 at the position where the first electrode 31 needs to be formed; thereafter, the substrate 9 is sintered, so that the electrode paste burns through the insulating layer 2 and part of the sub-layers in the passivation contact structure 1, and is solidified to form the first electrode 31 contacting the innermost doped polysilicon sub-layer 112 in the passivation contact structure 1 (but not passing through the doped polysilicon sub-layer 112).
It should be understood that the specific processes employed for each step in the method of the embodiments of the present invention are various.
For example, the passivation contact structure 1, the insulating layer 2, etc. may be formed by a Chemical Vapor Deposition (CVD), sputtering, evaporation, etc. process; for another example, the doping element in the doped polysilicon sub-layer 112 may be added during formation of the sub-layer, or may be added subsequently by a diffusion process or the like; for another example, the electrode paste may be directly formed at a desired position by a screen printing process or the like, or the electrode paste may be removed at an unnecessary position after forming a complete electrode paste layer.
It should be appreciated that the method of embodiments of the present invention may also include the step of forming other structures in the light Fu Di-electrode 31.
For example, a pile structure may also be formed on the substrate 9 by the pile forming liquid; for another example, lightly doped region 41 may also be formed on the light incident side of substrate 9 by boron diffusion; for another example, the heavily doped region 42 may also be formed by laser propulsion at a position corresponding to the first electrode 32 on the light incident side of the substrate 9; for another example, the passivation layer 5 may be formed on the light incident side of the substrate 9 by deposition or the like; for another example, the second electrode 32 on the light incident side of the substrate 9 may be formed by sintering an electrode paste; for another example, operations such as removal of the bypass plating, oxidation to form borosilicate glass (BSG), removal of excess BSG, and chemical cleaning may be performed.
Optionally, forming the passivation contact structure 1 on the substrate 9 side (S201) includes:
s2011, forming a doped polysilicon sub-layer 112 by plasma enhanced chemical vapor deposition, wherein the used process atmosphere contains carbon dioxide.
As a specific manner of the embodiment of the present invention, the doped polysilicon sub-layer 112 in the passivation contact structure 1 may be specifically formed by a Plasma Enhanced Chemical Vapor Deposition (PECVD) process, and carbon dioxide (CO) may be added in the process atmosphere used in the PECVD process 2 ) Thereby introducing a desired level of oxygen into the doped polysilicon sub-layer 112.
It should be appreciated that the oxygen content in the heteropolycrystalline silicon sub-layer may be specifically adjusted by varying the carbon dioxide content in the process atmosphere.
Thus, both the tunneling sublayer 111 and the doped polysilicon sublayer 112 may actually be formed by a continuous PECVD process, except for the different carbon dioxide levels used therein.
For example, the process atmosphere used in the PECVD process may include silane (SiH 4 ) And carbon dioxide (CO) 2 ) And the flow ratio of silane to carbon dioxide may be in the range of (5-1) to 1 during the formation of the doped polysilicon sub-layer 112.
It should be appreciated that other parameters in the above PECVD process (e.g., process temperature, deposition rate, deposition time, etc.) may also be selected as desired.
It should be appreciated that the specific process of forming the tunneling sublayer 111 and the doped polysilicon sublayer 112 is also not limited to PECVD.
Examples:
referring to fig. 3, the photovoltaic cell of the present invention was prepared by the following method:
a101, providing an N-type silicon wafer (substrate 9).
A102, texturing the silicon wafer, and forming a textured structure on the light incident side of the silicon wafer.
And A103, performing boron diffusion (boron diffusion) on the silicon wafer in a diffusion furnace, and forming a lightly doped region 41 (emitter) on the surface of the silicon wafer.
And A104, using a laser to irradiate the position of the anode (the second electrode 32) to be formed on the light incident side, so as to form a local heavily doped region 42.
A105, oxidizing to convert the outermost layer of the substrate 9 into borosilicate glass (BSG).
A107, removing BSG on the backlight side, and performing chemical cleaning (such as alkali cleaning and acid cleaning) on the backlight side.
And A108, forming a passivation contact structure 1 on the backlight side by using a PECVD process.
Wherein the oxygen content in the formed structure, i.e. the formation of the silicon dioxide layer (tunneling sub-layer 111) or the oxygen-containing polysilicon layer (doped polysilicon sub-layer 112) can be controlled by adjusting the carbon dioxide content in the process atmosphere.
Specifically, the passivation contact structure 1 comprises two sub-structures 11, i.e. two tunneling sub-layers 111 and two doped polysilicon sub-layers 112.
Wherein in the substructure 11 closer to the substrate 9, the tunneling sublayer 111 has a thickness of 1.5nm and the doped polysilicon sublayer 112 has a thickness of 20nm, wherein the oxygen content is 5wt%; in the substructure 11 further from the substrate 9, the tunneling sublayer 111 had a thickness of 1.5nm and the doped polysilicon sublayer 112 had a thickness of 30nm, with an oxygen content of 20wt%.
A109, removing the polysilicon around plating at the light incident side.
And A110, annealing, and performing phosphorus source deposition to increase the concentration of phosphorus in the doped polysilicon sub-layer 112, crystallize the doped polysilicon sub-layer 112 and activate doping.
A111, a layer of a silicon nitride/aluminum oxide mixed material (passivation layer 5) is formed on the light incident side, and an antireflection layer of a silicon nitride material (insulating layer 2) is formed on the backlight side.
And a112, printing silver paste (electrode paste) at a position corresponding to the positive electrode on the light incident side, and printing silver paste at a position corresponding to the negative electrode (first electrode 31) on the backlight side.
A113, sintering, wherein the silver paste on the light incidence side burns through the passivation layer 5 to form an anode contacted with the heavily doped region 42, and the silver paste on the backlight side burns through the insulating layer 2, the doped polysilicon sub-layer 112 on the outer side and the tunneling sub-layer 111 on the outer side to form a cathode contacted with the doped polysilicon sub-layer 112 on the inner side.
Comparative example:
referring to fig. 1, the present comparative example prepares a photovoltaic cell in the related art.
The photovoltaic cell in this comparative example is similar to the above embodiment except that in step a108, only one tunneling layer 71 and one doped polysilicon layer 72 are formed, and the doped polysilicon layer 72 is substantially free of oxygen.
Specifically, the thickness of the tunneling layer 71 in this comparative example was 1.5nm, the thickness of the doped polysilicon layer 72 was 100nm, and the oxygen content was 0.
It can be seen that the total thickness of the two doped polysilicon sublayers 112 in the above example is 50nm, while the thickness of the doped polysilicon layer 72 in the comparative example is 100nm; moreover, the first electrode 31 in the above embodiment passes through the other layers to be in contact with the innermost doped polysilicon sub-layer 112, but is not burned through.
This shows that the invention can reduce the total thickness of the doped polysilicon sub-layer and reduce parasitic absorption under the condition that the doped polysilicon layer is not burnt through.
Meanwhile, the short circuit current and the open circuit voltage of the photovoltaic cell of the above example were detected, and the results were 14.47A and 711mV, respectively; the current and open voltage of the photovoltaic cells of the above comparative examples were measured and found to be 14.33A and 693mV, respectively.
It can be seen that the short circuit current and the open circuit voltage of the photovoltaic cell of the present invention (examples) are significantly improved over those of the related art (comparative examples), indicating that the present invention can improve the cell efficiency.
It is to be understood that the above embodiments are merely illustrative of the application of the principles of the present invention, but not in limitation thereof. Various modifications and improvements may be made by those skilled in the art without departing from the spirit and substance of the invention, and are also considered to be within the scope of the invention.
Claims (10)
1. A photovoltaic cell, comprising:
a substrate;
a passivation contact structure located on one side of the substrate; the passivation contact structure comprises a plurality of stacked substructures, each substructure comprises a tunneling sublayer and a doped polysilicon sublayer positioned on one side of the tunneling sublayer, which is away from the substrate, wherein the doped polysilicon sublayer contains oxygen;
an insulating layer positioned on one side of the passivation contact structure away from the substrate;
and a first electrode positioned on one side of the passivation contact structure away from the substrate, the first electrode passing through the insulating layer and a part of the passivation contact structure to be in contact with a tunneling sublayer closest to the substrate in the passivation contact structure.
2. The photovoltaic cell of claim 1, wherein the photovoltaic cell,
the mass percentage of oxygen in the doped polysilicon sub-layer is between 2% and 30%.
3. The photovoltaic cell of claim 1, wherein the photovoltaic cell,
in any two doped polysilicon sublayers, the content of oxygen in the doped polysilicon sublayers farther from the substrate is higher than the content of oxygen in the doped polysilicon sublayers closer to the substrate.
4. The photovoltaic cell of claim 1, wherein the photovoltaic cell,
the doped polysilicon sub-layer also contains phosphorus.
5. The photovoltaic cell of claim 1, wherein the photovoltaic cell,
the doped polysilicon sub-layer closest to the substrate has a thickness between 20nm and 40 nm;
the total thickness of all the doped polysilicon sublayers is between 50nm and 120 nm.
6. The photovoltaic cell of claim 1, wherein the photovoltaic cell,
the tunneling sublayer closest to the substrate has a thickness between 1nm and 2nm;
the total thickness of all the tunneling sublayers is between 2nm and 7 nm.
7. The photovoltaic cell of claim 1, wherein the number of substructures is two; wherein, the liquid crystal display device comprises a liquid crystal display device,
in the substructure closer to the substrate, the doped polysilicon sub-layer has a thickness of 20nm to 30nm and the tunneling sub-layer has a thickness of 1nm to 2nm;
in the substructure further from the substrate, the doped polysilicon sub-layer has a thickness of 30nm to 60nm and the tunneling sub-layer has a thickness of between 1nm and 5nm.
8. The photovoltaic cell of claim 1, wherein the photovoltaic cell,
the photovoltaic cell is a tunneling oxide passivation contact photovoltaic cell;
the passivation contact structure is located on a backlight side of the substrate.
9. A method of making a photovoltaic cell, comprising:
forming a passivation contact structure on one side of the substrate; the passivation contact structure comprises a plurality of stacked substructures, each substructure comprises a tunneling sublayer and a doped polysilicon sublayer arranged on one side of the tunneling sublayer, which is far away from the substrate, wherein the doped polysilicon sublayer contains oxygen;
forming an insulating layer on the passivation contact structure;
disposing an electrode paste on the insulating layer;
sintering is performed to form the electrode paste into a first electrode that passes through the insulating layer and a portion of the passivation contact structure to contact a tunneling sublayer of the passivation contact structure closest to the substrate.
10. The method of claim 9, wherein forming a passivation contact structure on a side of the substrate comprises:
the doped polysilicon sub-layer is formed by plasma enhanced chemical vapor deposition, wherein the process atmosphere used contains carbon dioxide.
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