CN116314360A - Solar cell - Google Patents
Solar cell Download PDFInfo
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- CN116314360A CN116314360A CN202310328250.7A CN202310328250A CN116314360A CN 116314360 A CN116314360 A CN 116314360A CN 202310328250 A CN202310328250 A CN 202310328250A CN 116314360 A CN116314360 A CN 116314360A
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- 238000002161 passivation Methods 0.000 claims abstract description 207
- 239000000758 substrate Substances 0.000 claims abstract description 118
- 239000004065 semiconductor Substances 0.000 claims abstract description 26
- 229910052739 hydrogen Inorganic materials 0.000 claims abstract description 10
- 239000001257 hydrogen Substances 0.000 claims abstract description 10
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 claims abstract description 5
- 229910021420 polycrystalline silicon Inorganic materials 0.000 claims description 28
- 229920005591 polysilicon Polymers 0.000 claims description 28
- 230000005641 tunneling Effects 0.000 claims description 19
- 239000000463 material Substances 0.000 claims description 18
- 150000001875 compounds Chemical class 0.000 claims description 10
- 229910052782 aluminium Inorganic materials 0.000 claims description 9
- -1 aluminum compound Chemical class 0.000 claims description 9
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 8
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims description 8
- 229910052710 silicon Inorganic materials 0.000 claims description 8
- 239000010703 silicon Substances 0.000 claims description 8
- 229910052581 Si3N4 Inorganic materials 0.000 claims description 6
- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 claims description 6
- HQVNEWCFYHHQES-UHFFFAOYSA-N silicon nitride Chemical compound N12[Si]34N5[Si]62N3[Si]51N64 HQVNEWCFYHHQES-UHFFFAOYSA-N 0.000 claims description 6
- 229910052814 silicon oxide Inorganic materials 0.000 claims description 6
- 150000002259 gallium compounds Chemical class 0.000 claims description 5
- 150000003377 silicon compounds Chemical class 0.000 claims description 5
- AJNVQOSZGJRYEI-UHFFFAOYSA-N digallium;oxygen(2-) Chemical compound [O-2].[O-2].[O-2].[Ga+3].[Ga+3] AJNVQOSZGJRYEI-UHFFFAOYSA-N 0.000 claims description 4
- 229910001195 gallium oxide Inorganic materials 0.000 claims description 4
- HBMJWWWQQXIZIP-UHFFFAOYSA-N silicon carbide Chemical compound [Si+]#[C-] HBMJWWWQQXIZIP-UHFFFAOYSA-N 0.000 claims description 4
- 229910010271 silicon carbide Inorganic materials 0.000 claims description 4
- AZDRQVAHHNSJOQ-UHFFFAOYSA-N alumane Chemical class [AlH3] AZDRQVAHHNSJOQ-UHFFFAOYSA-N 0.000 claims 1
- 230000000694 effects Effects 0.000 abstract description 11
- 238000006243 chemical reaction Methods 0.000 description 8
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 5
- 238000006388 chemical passivation reaction Methods 0.000 description 5
- 238000005215 recombination Methods 0.000 description 5
- 230000006798 recombination Effects 0.000 description 5
- 230000000052 comparative effect Effects 0.000 description 4
- GYHNNYVSQQEPJS-UHFFFAOYSA-N Gallium Chemical compound [Ga] GYHNNYVSQQEPJS-UHFFFAOYSA-N 0.000 description 3
- 229910052733 gallium Inorganic materials 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- 230000007423 decrease Effects 0.000 description 2
- 230000003247 decreasing effect Effects 0.000 description 2
- 239000003989 dielectric material Substances 0.000 description 2
- 125000004435 hydrogen atom Chemical group [H]* 0.000 description 2
- 238000000034 method Methods 0.000 description 2
- 229910021421 monocrystalline silicon Inorganic materials 0.000 description 2
- 238000007650 screen-printing Methods 0.000 description 2
- 101001073212 Arabidopsis thaliana Peroxidase 33 Proteins 0.000 description 1
- 101001123325 Homo sapiens Peroxisome proliferator-activated receptor gamma coactivator 1-beta Proteins 0.000 description 1
- 102100028961 Peroxisome proliferator-activated receptor gamma coactivator 1-beta Human genes 0.000 description 1
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 description 1
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 1
- 239000000969 carrier Substances 0.000 description 1
- 239000013626 chemical specie Substances 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 230000005684 electric field Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- GPRLSGONYQIRFK-UHFFFAOYSA-N hydron Chemical compound [H+] GPRLSGONYQIRFK-UHFFFAOYSA-N 0.000 description 1
- 150000002500 ions Chemical class 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000007639 printing Methods 0.000 description 1
- 239000000377 silicon dioxide Substances 0.000 description 1
- 229910052709 silver Inorganic materials 0.000 description 1
- 239000004332 silver Substances 0.000 description 1
- 238000005245 sintering Methods 0.000 description 1
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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
- H01L31/04—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
- H01L31/068—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 the potential barriers being only of the PN homojunction type, e.g. bulk silicon PN homojunction solar cells or thin film polycrystalline silicon PN homojunction solar cells
- H01L31/0682—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 the potential barriers being only of the PN homojunction type, e.g. bulk silicon PN homojunction solar cells or thin film polycrystalline silicon PN homojunction solar cells back-junction, i.e. rearside emitter, solar cells, e.g. interdigitated base-emitter regions back-junction cells
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- Engineering & Computer Science (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Sustainable Development (AREA)
- Physics & Mathematics (AREA)
- Condensed Matter Physics & Semiconductors (AREA)
- Electromagnetism (AREA)
- General Physics & Mathematics (AREA)
- Computer Hardware Design (AREA)
- Life Sciences & Earth Sciences (AREA)
- Power Engineering (AREA)
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- Chemical & Material Sciences (AREA)
- Crystallography & Structural Chemistry (AREA)
- Photovoltaic Devices (AREA)
Abstract
The invention provides a solar cell, belongs to the technical field of photovoltaics, and can at least partially solve the problem that the passivation effect of the front side of the existing solar cell is poor. The solar cell of the present invention comprises: a substrate having opposite front and back sides; the front side is arranged towards sunlight; a passivation structure provided at least at a partial position of the front side of the substrate; the contact position of the substrate and the passivation structure is a P-type semiconductor; the passivation structure comprises a first passivation layer in contact with the substrate, and a second passivation layer which is positioned on one side of the first passivation layer away from the substrate and in contact with the first passivation layer; the density of negative charges in the first passivation layer is greater than 1e12cm ‑2 The positive charge density in the second passivation layer is greater than 1e11cm ‑2 The hydrogen content is greater than 7at%.
Description
Technical Field
The invention belongs to the technical field of photovoltaics, and particularly relates to a solar cell.
Background
The passivation technology can reduce carrier recombination in the solar cell and improve open-circuit voltage and conversion efficiency.
However, the passivation requirement of the front side (light incident side) of the solar cell is very high in the prior art, so that the passivation of the front surface becomes an important factor for restricting the development of the efficient solar cell.
Disclosure of Invention
The invention at least partially solves the problem of poor passivation effect of the front side of the existing solar cell, and provides the solar cell which can realize good passivation effect on the front side.
In a first aspect, an embodiment of the present invention provides a solar cell, including:
a substrate having opposite front and back sides; the front side is arranged towards sunlight;
a passivation structure provided at least at a partial position of the front side of the substrate; the contact position of the substrate and the passivation structure is a P-type semiconductor; the passivation structure comprises a first passivation layer in contact with the substrate, and a second passivation layer which is positioned on one side of the first passivation layer away from the substrate and in contact with the first passivation layer; the density of negative charges in the first passivation layer is greater than 1e12cm -2 The second step ofThe positive charge density in the passivation layer is greater than 1e11cm -2 The hydrogen content is greater than 7at%.
Optionally, the material of the first passivation layer includes a compound of aluminum and/or a compound of gallium;
the material of the second passivation layer includes a compound of silicon.
Optionally, the aluminum compound comprises aluminum oxide;
the gallium compound comprises gallium oxide;
the silicon compound comprises one or more of silicon nitride, silicon oxynitride, silicon oxide and silicon carbide.
Optionally, the thickness of the first passivation layer is between 0.5nm and 20 nm;
the second passivation layer has a thickness between 20nm and 200 nm.
Optionally, the second passivation layer includes a plurality of stacked second sub-passivation layers;
and sequentially reducing the refractive indexes of the plurality of second sub-passivation layers along the direction away from the substrate.
Optionally, the refractive index of the second sub-passivation layer closest to the substrate is between 2.1 and 2.4;
the refractive index of the second sub-passivation layer furthest from the substrate is between 1.3 and 2.1.
Optionally, the refractive index of the first passivation layer is less than the refractive index of the second sub-passivation layer closest to the substrate.
Optionally, the solar cell of the embodiment of the invention further includes a first electrode and a second electrode disposed on the back side of the substrate;
the substrate is a P-type semiconductor;
the passivation structure completely covers the front side of the substrate.
Optionally, the front side of the substrate is a suede structure.
Optionally, the solar cell according to the embodiment of the present invention further includes:
the tunneling passivation layer is arranged on the back side of the substrate;
the doped polysilicon layer is arranged on one side of the tunneling passivation layer, which is away from the substrate, of the N-type semiconductor;
the medium layer is arranged on one side of the doped polysilicon layer, which is away from the substrate;
the first electrode and the second electrode are arranged on one side of the dielectric layer, which is away from the substrate;
the first electrode is positioned in a groove region, the tunneling passivation layer and the doped polysilicon layer are grooved at the groove region, and the first electrode passes through the dielectric layer to be in contact with the substrate;
the second electrode is located in the passivation contact area, and the second electrode penetrates through the dielectric layer to be in contact with the doped polysilicon layer.
The front side of the solar cell provided by the embodiment of the invention is provided with the first passivation layer and the second passivation layer which are sequentially arranged, and the first passivation layer and the second passivation layer respectively contain a large amount of negative charges and positive charges (also comprise a large amount of free hydrogen ions), so that good field passivation and chemical passivation effects can be respectively achieved, and the front side of the solar cell can be well passivated through the combination of the first passivation layer and the second passivation layer, and the open-circuit voltage and the conversion efficiency of the solar cell can be improved.
Drawings
Fig. 1 is a schematic cross-sectional structure of a solar cell according to an embodiment of the present invention;
fig. 2 is a schematic cross-sectional structure of another solar cell according to an embodiment of the present invention;
fig. 3 is a schematic cross-sectional structure of another solar cell according to an embodiment of the present invention;
fig. 4 is a schematic cross-sectional structure of a solar cell according to the related art;
wherein, the reference numerals are as follows: 1. a substrate; 19. a suede structure; 2. a passivation structure; 21. a first passivation layer; 22. a second passivation layer; 221. a second sub-passivation layer; 51. tunneling the passivation layer; 52. a doped polysilicon layer; 53. a dielectric layer; 61. a first electrode; 611. a back surface field; 62. a second electrode; 91. a trench region; 92. the contact region is passivated.
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.
In a first aspect, referring to fig. 1 to 3, an embodiment of the present invention provides a solar cell.
Among them, a solar cell is a device capable of converting light irradiated thereto into electric energy.
The solar cell of the embodiment of the invention comprises:
a substrate 1, the substrate 1 having opposite front and back sides; wherein the front side is for being arranged towards sunlight.
A passivation structure 2 provided at least in part on the front side of the substrate 1.
Wherein, the contact position of the substrate 1 and the passivation structure 2 is a P-type semiconductor; the passivation structure 2 includes a first passivation layer 21 in contact with the substrate 1, and a second passivation layer 22 located on a side of the first passivation layer 21 away from the substrate 1 and in contact with the first passivation layer 21; the density of negative charges in the first passivation layer is greater than 1e12cm -2 The positive charge density in the second passivation layer is greater than 1e11cm -2 The hydrogen content is greater than 7at%.
Referring to fig. 1, a solar cell according to an embodiment of the present invention includes a substrate 1, wherein the substrate 1 is made of a semiconductor material, such as polysilicon, monocrystalline silicon, or the like; the substrate 1 is plate-shaped as a whole, and two main surfaces of the plate are respectively a front side and a back side, wherein the front side is arranged towards sunlight for sunlight to enter, so the front side is also called as an incident light side; the back side is directed away from the sunlight and is also referred to as the backlight side.
At least part of the front side of the substrate 1 is provided with a passivation structure 2 for passivation, and the front side of the substrate 1 is in contact with the passivation structure 2 in a P-type semiconductor.
The passivation structure 2 is composed of a dielectric material that is not conductive, which is a laminated structure of two layers, in which a first passivation layer 21 is in direct contact with the front side (P-type semiconductor) of the substrate 1, and a second passivation layer 22 is farther from the substrate 1 than the first passivation layer 21 and is in direct contact with the first passivation layer 21.
Wherein the first passivation layer 21 contains a large amount of negative fixed charges, specifically at least 1×10 of the first passivation layer 21 per square centimeter area at the interface 12 Further may contain at least 5 x 10 of negative charges 12 The negative charges can form a built-in electric field on the front side of the substrate 1 after contacting the front side of the substrate 1 (P-type semiconductor), so as to reduce the probability of carrier meeting and recombination on the front side, i.e. reduce the surface recombination rate, thereby playing a role of field passivation.
The second passivation layer 22 contains a large amount of fixed positive charges and free hydrogen ions, specifically at least 1×10 per square centimeter of area of the second passivation layer 22 at the interface 11 And further may contain at least 5 x 10 positive charges 11 The number of hydrogen atoms in the second passivation layer 22 is at least 7%, and further may be at least 10%, and the hydrogen atoms may diffuse through the first passivation layer 21 at a high temperature to passivate dangling bonds on the front side of the substrate 1, thereby further reducing the surface recombination rate, that is, performing a chemical passivation function; meanwhile, the second passivation layer 22 may also function to protect the first passivation layer 21.
It should be understood that other structures, such as the first electrode 61 and the second electrode 62 (positive and negative electrodes) for outputting current, and structural layers serving other functions, etc., may be included in the solar cell of the embodiment of the present invention in addition to the passivation structure 2 and the substrate 1.
It should be appreciated that the solar cell should also have a PN junction formed therein to form a base and an emitter, respectively; the PN junction may be formed inside the substrate 1 (i.e., different locations of the substrate 1 are doped with different types of semiconductors), or may be formed between the substrate 1 and other structures (e.g., the doped polysilicon layer 52) with reference to fig. 3.
It should be understood that the semiconductor type at other locations of the substrate 1 is varied, except that the front side of the substrate 1 must be P-type semiconductor where it contacts the passivation structure 2. For example, referring to fig. 3, the substrate 1 as a whole is a P-type semiconductor; alternatively, most of the substrate 1 may be P-type semiconductor, and the local position not contacting the passivation structure 2 may be N-type semiconductor; alternatively, most of the substrate 1 may be an N-type semiconductor, and the front side of the substrate 1 may be partially an N-type semiconductor at a position contacting the passivation structure 2.
Optionally, the material of the first passivation layer 21 includes a compound of aluminum and/or a compound of gallium; the material of the second passivation layer 22 comprises a compound of silicon.
Alternatively, the aluminum compound includes aluminum oxide; gallium compounds include gallium oxide; the silicon compound comprises one or more of silicon nitride, silicon oxynitride, silicon oxide and silicon carbide.
As a way of an embodiment of the present invention, the material of the first passivation layer 21 may be selected from a compound of aluminum, a compound of gallium, and more specifically, one or more selected from aluminum oxide, gallium oxide. While the material of the second passivation layer 22 may be selected from a compound of silicon, more specifically one or more selected from silicon nitride, silicon oxynitride, silicon oxide, silicon carbide.
It should be understood that the concentration of the various ions may be different for the same chemical species (e.g., alumina or silica) based on the manufacturing process, material density, etc. That is, not all of the gallium compound and the aluminum compound necessarily satisfy the density requirement of the negative charge of the first passivation layer 21; nor is it necessary that all silicon compounds meet the hydrogen ion density requirements of the second passivation layer 22. The first passivation layer 21 and the second passivation layer 22 of the embodiment of the present invention must meet the corresponding density requirements.
The front side of the solar cell in the embodiment of the invention is provided with the first passivation layer 21 and the second passivation layer 22 which are sequentially arranged, and the first passivation layer and the second passivation layer respectively contain a large amount of negative charges and positive charges (also comprise a large amount of free hydrogen ions), so that good field passivation and chemical passivation effects can be respectively achieved, and the front side of the solar cell can be well passivated through the combination of the first passivation layer and the second passivation layer, and the open-circuit voltage and the conversion efficiency of the front side of the solar cell can be improved.
Optionally, the thickness of the first passivation layer 21 is between 0.5nm and 20 nm; the thickness of the second passivation layer 22 is between 20nm and 200 nm.
As a way of an embodiment of the invention, the second passivation layer 22 may be thicker than the first passivation layer 21, so that the thicker second passivation layer 22 may act as an anti-reflection in addition to the chemical passivation.
Wherein, the thickness of the first passivation layer 21 can be specifically 0.5-20 nm, and further can be 2-10 nm; the thickness of the second passivation layer 22 may be 20-200 nm, and further may be 50-150 nm.
Optionally, the second passivation layer 22 includes a plurality of stacked second sub-passivation layers 221; the refractive index of the plurality of second sub-passivation layers 221 sequentially decreases in a direction away from the substrate 1.
Optionally, the refractive index of the second sub-passivation layer 221 closest to the substrate 1 is between 2.0 and 2.4; the refractive index of the second sub-passivation layer 221 furthest from the substrate 1 is between 1.3 and 2.1.
Referring to fig. 2, as a way of embodiment of the present invention, the second passivation layer 22 may be divided into a plurality of stacked sub-layers (second sub-passivation layers 221), and the refractive index of each second sub-passivation layer 221 is sequentially decreased in a direction away from the substrate 1, thereby forming an antireflection structure with a graded refractive index.
Further, the refractive index of the second sub-passivation layer 221 closest to the substrate 1 may be 2.0 to 2.4, and may be 2.15 to 2.35; the refractive index of the second sub-passivation layer 221 furthest from the substrate 1 may be reduced to 1.3-2.1, and further may be 1.5-1.8.
When there are a plurality of second sub-passivation layers 221, the density of hydrogen ions in each second sub-passivation layer 221 should meet the requirement of the density of hydrogen ions in the second passivation layer 22.
Where there are a plurality of second sub-passivation layers 221, the material of each second sub-passivation layer 221 may be selected from the candidate materials (silicon compounds) for the second passivation layer 22, and the material selection for each second sub-passivation layer 221 is relatively independent, i.e., the materials of different second sub-passivation layers 221 may be the same or different (provided of course that the refractive index relationship is met).
Where there are a plurality of second sub-passivation layers 221, then the thickness of all of the second sub-passivation layers 221 (i.e., the second passivation layer 22 as a whole) may be in the range of 20-200 nm above.
Alternatively, the refractive index of the first passivation layer 21 is smaller than that of the second sub-passivation layer 221 closest to the substrate 1.
As a way of embodiment of the present invention, referring to fig. 2, the first passivation layer 21 is located below the second sub-passivation layer 221 closest to the substrate 1, but the refractive index thereof may be smaller than that of the second sub-passivation layer 221 closest to the substrate 1, i.e. the refractive index variation rule of each second sub-passivation layer 221 is not met.
It should be understood that the first passivation layer 21 may be divided into a plurality of first sub-passivation layers (not shown), and the refractive index of each first sub-passivation layer may also decrease sequentially in a direction away from the substrate 1; further, it may be that the refractive indices of all the first sub-passivation layer and the second sub-passivation layer 221 are sequentially decreased in a direction away from the substrate 1.
Optionally, the solar cell of the embodiment of the present invention further includes a first electrode 61 and a second electrode 62 disposed on the back side of the substrate 1; the substrate 1 is a P-type semiconductor; the passivation structure 2 completely covers the front side of the substrate 1.
Referring to fig. 3, as a way of an embodiment of the present invention, both the positive and negative electrodes (first electrode 61 and second electrode 62) of the solar cell may be provided on the back side (backlight side) of the substrate 1, i.e., a "full back contact structure" is adopted; accordingly, the front side of the substrate 1 is electrode-free.
Meanwhile, the whole substrate 1 is a P-type semiconductor (i.e. base), and the passivation structure 2 completely covers the front side of the substrate 1, so as to passivate the whole front side of the substrate 1.
Compared with the related art that the front side of the substrate is provided with the electrode, in the full back contact structure, the front side (light incident side) of the substrate 1 is not provided with the electrode which can shield sunlight, so that the utilization rate of light is improved, and the short-circuit current and the conversion efficiency are higher.
Meanwhile, if the front side of the substrate is provided with an electrode, the front side also has a doped emitter, a surface field and the like, so that the requirement on passivation effect is not high; when the full back contact structure is adopted, the passivation effect is very dependent on the property of the passivation structure 2 because the front side is free from an emitter, a surface field and the like, and the requirement on the passivation effect is higher, so that the full back contact structure is more suitable for the passivation structure 2 adopting the embodiment of the invention.
Moreover, since the front side of the substrate 1 of the all-back contact structure has no electrode, the problems of contact recombination and the like are not considered, so that the light trapping and the surface passivation of the front side can be optimized to the greatest extent, and the open-circuit voltage and the conversion efficiency of the solar cell can be further improved.
Optionally, the solar cell according to the embodiment of the present invention further includes:
a tunneling passivation layer 51 provided on the back side of the substrate 1;
a doped polysilicon layer 52 of N-type semiconductor provided on a side of the tunnel passivation layer 51 facing away from the substrate 1;
a dielectric layer 53 provided on a side of the doped polysilicon layer 52 facing away from the substrate 1;
the first electrode 61 and the second electrode 62 are arranged on the side of the dielectric layer 53 facing away from the substrate 1;
the first electrode 61 is located in the trench region 91, the tunneling passivation layer 51 and the doped polysilicon layer 52 are slotted at the trench region 91, and the first electrode 61 is contacted with the substrate 1 through the dielectric layer 53;
the second electrode 62 is located in the passivation contact region 92, and the second electrode 62 is in contact with the doped polysilicon layer 51 through the dielectric layer 53.
For example, referring to fig. 3, the solar cell according to the embodiment of the present invention may be an inter-digital back contact (IBC, interdigitated Back Contact) cell.
In the IBC cell, the substrate 1 is a P-type semiconductor as a base, and the front side thereof covers the passivation structure 2 according to the embodiment of the present invention.
The back side of the substrate 1 can be polished and provided with an ultrathin tunneling passivation layer 51, and the tunneling passivation layer 51 is made of a dielectric material with very thin thickness, so that the tunneling passivation layer has carrier tunneling and interface passivation effects; for example, the tunneling passivation layer 51 may be made of aluminum oxide, silicon oxide, or the like, and may have a thickness of 0.5-5 nm.
The tunneling passivation layer 51 is a doped polysilicon layer 52 of an N-type semiconductor on the side far away from the substrate 1, and the semiconductor type of the doped polysilicon layer 52 is opposite to that of the substrate 1, so that the doped polysilicon layer serves as an emitter; for example, the doped polysilicon layer 52 may have a thickness of 5-300 nm and a surface doping concentration of greater than 1e19cm -3 。
The doped polysilicon layer 52 is a dielectric layer 53 on the side far from the substrate 1, and a first electrode 61 and a second electrode 62 are formed on the side of the dielectric layer 53 far from the substrate 1.
The first electrode 61 (e.g., positive electrode) is disposed in the trench region 91, and the tunneling passivation layer 51 and the doped polysilicon layer 52 of the trench region 91 are removed to form a trench, so that the first electrode 61 passes through the dielectric layer 53 to form ohmic contact with the substrate 1 of the trench region 91, and forms a back field 611 at the interface contacting with the substrate 1, so as to improve the collection efficiency of photo-generated carriers.
The second electrode 62 (e.g. the negative electrode) is located in the passivation contact region 92 (because the tunneling passivation layer 51 and the doped polysilicon layer 52 at this location still can perform passivation function), so that the second electrode 62 forms an ohmic contact with the doped polysilicon layer 52 (emitter) through the dielectric layer 53, but does not directly contact the substrate 1.
Each electrode may be in the form of an "finger," i.e., each electrode includes a main gate line and sub-gate lines extending from the main gate line to both sides, with the main gate lines of different electrodes being parallel to each other, and the sub-gate lines being "inserted" into the spaces of the sub-gate lines of the other electrode.
Optionally, the front side of the substrate 1 is a pile structure 19.
Referring to fig. 3, as a way of embodiment of the present invention, the front side of the substrate 1 may be a pile structure 19, that is, a plurality of pyramid-shaped small protrusions may be formed on the surface of the front side of the substrate 1 as the pile structure 19 by chemical pile forming or the like; the texturing 19 reduces reflection and thereby increases light utilization.
It should be appreciated that since the first passivation layer 21 and the second passivation layer 22 are formed on the front side of the substrate 1, referring to fig. 3, when the front side of the substrate 1 has the textured structure 19, the respective first passivation layer 21 and second passivation layer 22 are actually also structures that undulate with the textured structure 19.
It should be understood that the specific form of the solar cell in the embodiments of the present invention is not limited to the above specific form.
For example, some or all of the electrodes of the solar cell of the embodiments of the present invention may be located on the front side of the substrate 1; for another example, the emitter of the solar cell may be doped to form an N-type semiconductor in a partial region of the substrate 1 (of course, this region cannot be released from the passivation structure 2) instead of a separate doped polysilicon layer; for another example, the back side of the substrate 1 may not be polished, but may be provided with a textured structure or the like as well.
Specifically, the solar cell according to the embodiments of the present invention may be not an IBC cell, but other forms such as a passivated emitter back contact (PERC, passivated Emitter and Rear Contact) cell, a tunnel oxide passivation contact (TOPCon, tunnel Oxide Passivated Contact) cell, a Heterojunction (HJT) cell, and the like, which will not be described in detail herein.
Example 1:
referring to fig. 3, the present embodiment provides a solar cell of the present invention, which includes a substrate 1 of P-type monocrystalline silicon, the substrate 1 having a thickness of 150±10um.
The front side (light entrance side) of the substrate 1 is formed with a pyramidal pile structure 19 by chemical pile.
On the textured structure 19 on the front side of the substrate 1, a first passivation layer 21 is deposited, which has a field passivation effect, the first passivation layer 21 being made of an aluminum oxide material and having a thickness of 5nm, wherein the density of negative charges is 1.3e13cm -2 。
A second passivation layer 22 having a chemical passivation effect is deposited on the first passivation layer 21, and the second passivation layer 22 is made of a silicon nitride material and has a thickness of 70nm, wherein the positive charge density is 1e12cm-2 and the hydrogen content is 15at%.
The back side (backlight side) of the substrate 1 is polished, and then an ultra-thin tunneling passivation layer 51 is deposited, wherein the tunneling passivation layer 51 is made of silicon oxide material, and the thickness is 1.5nm.
An N-type doped polysilicon layer 52 (emitter) is deposited on the tunneling passivation layer 51, the thickness of the doped polysilicon layer 52 is 180nm, and the surface doping concentration is 1.2e20cm -3 。
Part of the substrate 1 is a patterned trench region 91, and the position of the trench region 91 is a passivation contact region 92; the tunnel passivation layer 51 and the doped polysilicon layer 52 in the trench region 91 are removed by laser grooving, while the tunnel passivation layer 51 and the doped polysilicon layer 52 remain in the passivation contact region 92.
A dielectric layer 53 of silicon nitride is deposited on the doped polysilicon layer 52 to a thickness of 80nm.
On the dielectric layer 53, a first electrode 61 (e.g., positive electrode) of aluminum is formed at the trench region 91 by a screen printing process (including printing, sintering, etc.); and a second electrode 62 of silver (e.g., a negative electrode) is formed at the passivation contact region 92 by a screen printing process.
Wherein the first electrode 61 penetrates the dielectric layer 53, contacts the back side of the substrate 1 (base) at the trench region 91, and forms a back field 611 (aluminum back field) at the contact interface; and a second electrode 62 penetrates the dielectric layer 53 and forms an ohmic contact with the doped polysilicon layer 52 (emitter).
The performance parameters of the solar cell of this embodiment are detected as follows: the open circuit voltage is higher than 726mV, and the conversion efficiency is more than 24.8%.
Comparative example 1:
referring to fig. 4, the present comparative example provides a solar cell in the related art, which has a similar structure, material, parameters, etc. to the solar cell of the present invention of example 1, except that the front side of the solar cell of the present comparative example has no passivation structure (first passivation layer and second passivation layer).
The performance parameters of the solar cell of the comparative example were detected as follows: the open circuit voltage is lower than 725mV, and the conversion efficiency is lower than 24%.
It can be seen that by forming the passivation structure 2 according to the embodiment of the invention on the front side of the solar cell, the performances of the solar cell such as open circuit voltage and conversion efficiency can be effectively improved.
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 solar cell, comprising:
a substrate having opposite front and back sides; the front side is arranged towards sunlight;
a passivation structure provided at least at a partial position of the front side of the substrate; the contact position of the substrate and the passivation structure is a P-type semiconductor; the passivation structure comprises a first passivation layer in contact with the substrate, and a second passivation layer which is positioned on one side of the first passivation layer away from the substrate and in contact with the first passivation layer; the density of negative charges in the first passivation layer is greater than 1e12cm -2 The positive charge density in the second passivation layer is greater than 1e11cm -2 The hydrogen content is greater than 7at%.
2. The solar cell according to claim 1, wherein,
the material of the first passivation layer comprises aluminum compounds and/or gallium compounds;
the material of the second passivation layer includes a compound of silicon.
3. The solar cell according to claim 2, wherein,
the aluminum compound includes aluminum oxide;
the gallium compound comprises gallium oxide;
the silicon compound comprises one or more of silicon nitride, silicon oxynitride, silicon oxide and silicon carbide.
4. The solar cell according to claim 1, wherein,
the thickness of the first passivation layer is between 0.5nm and 20 nm;
the second passivation layer has a thickness between 20nm and 200 nm.
5. The solar cell according to claim 1, wherein,
the second passivation layer comprises a plurality of stacked second sub-passivation layers;
and sequentially reducing the refractive indexes of the plurality of second sub-passivation layers along the direction away from the substrate.
6. The solar cell according to claim 5, wherein,
the refractive index of the second sub-passivation layer closest to the substrate is between 2.0 and 2.4;
the refractive index of the second sub-passivation layer furthest from the substrate is between 1.3 and 2.1.
7. The solar cell according to claim 5, wherein,
the first passivation layer has a refractive index less than a refractive index of a second sub-passivation layer closest to the substrate.
8. The solar cell of any one of claims 1 to 7, further comprising a first electrode and a second electrode disposed on a back side of the substrate;
the substrate is a P-type semiconductor;
the passivation structure completely covers the front side of the substrate.
9. The solar cell of claim 8, further comprising:
the tunneling passivation layer is arranged on the back side of the substrate;
the first electrode and the second electrode are arranged on one side of the dielectric layer, which is away from the substrate;
the first electrode is positioned in a groove region, the tunneling passivation layer and the doped polysilicon layer are grooved at the groove region, and the first electrode passes through the dielectric layer to be in contact with the substrate;
the second electrode is located in the passivation contact area, and the second electrode penetrates through the dielectric layer to be in contact with the doped polysilicon layer.
10. The solar cell according to any one of claims 1 to 7, wherein,
the front side of the substrate is of a suede structure.
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|---|---|---|---|
| CN202310328250.7A CN116314360A (en) | 2023-03-30 | 2023-03-30 | Solar cell |
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| CN202310328250.7A CN116314360A (en) | 2023-03-30 | 2023-03-30 | Solar cell |
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