CN113224182A - Heterojunction solar cell and preparation method thereof - Google Patents

Heterojunction solar cell and preparation method thereof Download PDF

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Publication number
CN113224182A
CN113224182A CN202110596804.2A CN202110596804A CN113224182A CN 113224182 A CN113224182 A CN 113224182A CN 202110596804 A CN202110596804 A CN 202110596804A CN 113224182 A CN113224182 A CN 113224182A
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tco
layer
silicon substrate
solar cell
heterojunction solar
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Inventor
张海川
袁强
石建华
孟凡英
刘正新
程琼
周华
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Tongwei Solar Chengdu Co Ltd
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Zhongwei New Energy Chengdu Co ltd
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Priority to CN202110596804.2A priority Critical patent/CN113224182A/en
Publication of CN113224182A publication Critical patent/CN113224182A/en
Priority to PCT/CN2022/089454 priority patent/WO2022247570A1/en
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    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01LSEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L31/00Semiconductor 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
    • H01L31/02Details
    • H01L31/0224Electrodes
    • H01L31/022466Electrodes made of transparent conductive layers, e.g. TCO, ITO layers
    • H01L31/022475Electrodes made of transparent conductive layers, e.g. TCO, ITO layers composed of indium tin oxide [ITO]
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01LSEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L31/00Semiconductor 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
    • H01L31/04Semiconductor 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
    • H01L31/06Semiconductor 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 at least one potential-jump barrier or surface barrier
    • H01L31/072Semiconductor 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 at least one potential-jump barrier or surface barrier the potential barriers being only of the PN heterojunction type
    • H01L31/0745Semiconductor 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 at least one potential-jump barrier or surface barrier the potential barriers being only of the PN heterojunction type comprising a AIVBIV heterojunction, e.g. Si/Ge, SiGe/Si or Si/SiC solar cells
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01LSEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L31/00Semiconductor 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
    • H01L31/18Processes or apparatus specially adapted for the manufacture or treatment of these devices or of parts thereof
    • H01L31/1804Processes or apparatus specially adapted for the manufacture or treatment of these devices or of parts thereof comprising only elements of Group IV of the Periodic System
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01LSEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L31/00Semiconductor 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
    • H01L31/18Processes or apparatus specially adapted for the manufacture or treatment of these devices or of parts thereof
    • H01L31/1884Manufacture of transparent electrodes, e.g. TCO, ITO
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02EREDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00Energy generation through renewable energy sources
    • Y02E10/50Photovoltaic [PV] energy
    • Y02E10/547Monocrystalline silicon PV cells
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02PCLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50Manufacturing or production processes characterised by the final manufactured product

Abstract

The embodiment of the application provides a heterojunction solar cell and a preparation method thereof, and relates to the field of heterojunction solar cells. The heterojunction solar cell comprises a silicon substrate, wherein a front passivation layer, an n-type doping layer, a front TCO layer and a front electrode are sequentially stacked on the front surface of the silicon substrate, a back passivation layer, a p-type doping layer, a back TCO layer and a back electrode are sequentially stacked on the back surface of the silicon substrate, the front TCO layer and/or the back TCO layer comprise at least two TCO films, the TCO films with the middle number of layers are low-doped TCO films with the doping concentration of 0-5 wt%, and the TCO films with the part of layers are high-doped TCO films with the doping concentration of 8-15 wt%. The heterojunction solar cell and the preparation method thereof can effectively improve the reliability of the heterojunction solar cell and slow down the aging attenuation of the heterojunction solar cell while ensuring the cost and efficiency of the cell.

Description

Heterojunction solar cell and preparation method thereof
Technical Field
The application relates to the field of heterojunction solar cells, in particular to a heterojunction solar cell and a preparation method thereof.
Background
In the current society, environmental protection is a major topic, the vigorous development of clean energy is imperative, solar energy is clean and pollution-free energy with huge reserves, and has wide application prospects, and the solar energy is mainly used for converting the solar cell into electric energy. At present, crystalline silicon solar cells occupy more than 90% of the market, and mainly adopt PERC (Passivated Emitter and reactor Cell) cells as main cells, but the efficiency improvement of the PERC cells is in a bottleneck period and is difficult to improve. Meanwhile, the heterojunction solar cell has the advantages of symmetrical structure, high open circuit voltage, good temperature characteristic, thin silicon chip, low-temperature preparation process and the like, is entering the industrialization stage, and becomes one of the target products in the industry.
The general preparation process of the heterojunction solar cell is to take N-type crystalline silicon as a substrate, form a light trapping structure in a pyramid form by cleaning and texturing, then respectively deposit an intrinsic amorphous silicon passivation layer, a p-type doping layer, an intrinsic amorphous silicon passivation layer and an N-type doping layer on two sides of the substrate, respectively deposit Transparent Conductive Oxide (TCO) films on two sides, and finally prepare a silver electrode. However, the reliability of the current heterojunction solar cell is poor, and the current heterojunction solar cell is mainly characterized by rapid attenuation in a sodium resistance test, a damp heat test (DH) and a thermal cycle Test (TC); if the specific material is adopted for preparation so as to improve the reliability of the heterojunction solar cell, the cost is increased.
Disclosure of Invention
An object of the embodiment of the application is to provide a heterojunction solar cell and a preparation method thereof, which can effectively improve the reliability of the heterojunction solar cell and slow down the aging attenuation of the heterojunction solar cell while ensuring the cost and efficiency of the cell.
In a first aspect, an embodiment of the present application provides a heterojunction solar cell, which includes a silicon substrate, a front passivation layer, an n-type doping layer, a front TCO layer, and a front electrode are sequentially stacked on a front surface of the silicon substrate, a back passivation layer, a p-type doping layer, a back TCO layer, and a back electrode are sequentially stacked on a back surface of the silicon substrate, the front TCO layer and/or the back TCO layer includes at least two TCO films, a TCO film at a middle part of the front TCO films is a low-doped TCO film with a doping concentration of 0 to 5 wt%, and a TCO film at a part of the layers is a high-doped TCO film with a doping concentration of 8 to 15 wt%.
In the implementation process, at least one of the Transparent Conductive Oxide (TCO) films on the front surface and the back surface of the heterojunction solar cell adopts a laminated structure combining a high-doped TCO film and a low-doped TCO film, so that the reliability and the photoelectric conversion efficiency of the heterojunction solar cell can be improved, the aging attenuation of the heterojunction solar cell is slowed down, and the cost, the efficiency and the reliability of the heterojunction solar cell are considered by the heterojunction solar cell.
In one possible implementation, the thickness of the low-doped TCO film is 10-80 nm; the thickness of the highly doped TCO film is 20-80 nm.
In one possible implementation manner, the front TCO layer comprises at least two TCO films, and the doping concentration of each TCO film is reduced in sequence from the adjacent direction to the direction far away from the silicon substrate;
or the front TCO layer comprises even TCO films, every two TCO films form a group along the direction from the adjacent position to the position far away from the silicon substrate, and the doping concentration of the TCO film close to the silicon substrate in each group is larger than that of the TCO film far away from the silicon substrate.
In the implementation process, the high-doped TCO film has high conductivity, the low-doped TCO film has good light transmittance, and the TCO films with the doping concentrations decreasing from high to low in sequence are arranged on the front surface of the light receiving surface, so that different performances of the high-doped TCO film and the low-doped TCO film on light transmittance and conductivity can be fully utilized, the short-circuit current of the heterojunction cell is improved, and the photoelectric conversion efficiency is improved.
In one possible implementation manner, the back TCO layer comprises at least two TCO films, and the doping concentration of each TCO film is increased in sequence from the adjacent direction to the direction far away from the silicon substrate;
or the back TCO layer comprises even TCO films, every two TCO films form a group along the direction from the adjacent position to the position far away from the silicon substrate, and the doping concentration of the TCO film close to the silicon substrate in each group is smaller than that of the TCO film far away from the silicon substrate.
In the implementation process, the high-doped TCO film is high in conductivity, the low-doped TCO film is good in light transmittance, the TCO films with doping concentrations sequentially increasing from low to high are arranged on the back surface of the backlight surface, different performances of the high-doped TCO film and the low-doped TCO film on light transmittance and conductivity can be fully utilized, long-wave reflection of light on the back surface can be enhanced due to the arrangement of the TCO film lamination, short-circuit current of the heterojunction cell is improved, and photoelectric conversion efficiency is improved.
In one possible implementation, the front passivation layer and/or the back passivation layer is an intrinsic silicon passivation layer, and the thickness of the front passivation layer and/or the back passivation layer is 4-10 nm.
In one possible implementation mode, the n-type doped layer is an n-type doped amorphous silicon or microcrystalline silicon layer, the doping concentration is 0.5-5 wt%, and the thickness of the n-type doped layer is 5-15 nm;
and/or the p-type doped layer is a p-type doped amorphous silicon or microcrystalline silicon layer, the doping concentration is 0.5-5 wt%, and the thickness of the p-type doped layer is 8-20 nm.
In one possible implementation, the front electrode and/or the back electrode is a silver grid electrode with a thickness of 2-50 μm.
In a second aspect, an embodiment of the present application provides a method for preparing a heterojunction solar cell provided in the first aspect, which includes the following steps:
sequentially depositing a front passivation layer, an n-type doping layer and a front TCO layer on the front side of the silicon substrate, and sequentially depositing a back passivation layer, a p-type doping layer and a back TCO layer on the back side of the silicon substrate;
and preparing a front electrode on the surface of the front TCO layer, and preparing a back electrode on the surface of the back TCO layer.
In one possible implementation, the deposition method of the TCO film is: radio frequency sputtering, direct current sputtering or pulse sputtering; the target is a plane target or a rotary target;
the deposition method of the TCO film comprises the following steps: the pressure of the process cavity is 0.1-1 Pa; the argon flow is 400-; the oxygen flow is 5-50 sccm; the temperature of the silicon substrate is 100-220 ℃; the power is 5-20 kW.
In one possible implementation manner, the front electrode and the back electrode are respectively prepared by the following steps: screen printing, evaporation, magnetron sputtering or ink jet printing;
and/or the front passivation layer, the n-type doped layer, the back passivation layer and the p-type doped layer are deposited respectively according to the following steps: PECVD, cat.cvd or HWCVD; the temperature of the silicon substrate in the deposition method is 150-250 ℃; the pressure of the process chamber is 10-100 Pa.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are required to be used in the embodiments of the present application will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present application and therefore should not be considered as limiting the scope, and that those skilled in the art can also obtain other related drawings based on the drawings without inventive efforts.
Fig. 1 is a schematic structural diagram of a heterojunction solar cell according to a first embodiment of the present application;
fig. 2 is a schematic structural diagram of a heterojunction solar cell according to a second embodiment of the present application.
Icon: 100-heterojunction solar cells; 110-a silicon substrate; 120-front side passivation layer; a 130-n type doped layer; 141-first front TCO film; 142-a second front TCO film; 150-front electrode; 160-back passivation layer; 170-p type doped layer; 181 — first backside TCO film; 182-a second back TCO film; 190 — back electrode; 200-heterojunction solar cells; 211 — first front side TCO film; 212-second front TCO film; 213-third front TCO film; 214-fourth front-side TCO film; 221-a first backside TCO film; 222-second back side TCO film; 223-third backside TCO film; 224-fourth backside TCO film.
Detailed Description
In the process of implementing the application, the applicant finds that: the TCO film plays an important role in the heterojunction solar cell as follows: 1. as a surface antireflection window layer, the surface antireflection window layer needs to have excellent optical transmittance, low parasitic absorption and appropriate optical refractive index, so that incident light can enter the silicon absorption layer to the maximum extent; 2. as a carrier collection and transmission layer, the amorphous silicon film layer has excellent transverse and longitudinal conductivity and can effectively collect and transmit the carrier to reach low conductivity; 3. as the protective layer, it is required to have good chemical inertness and ion barrier property to effectively protect the amorphous silicon thin film layer.
The TCO film in the heterojunction solar cell is usually prepared by a magnetron sputtering method (PVD) based on the important role of the TCO film in the heterojunction solar cell, and the widely used TCO target is indium oxide (9010 target for short) with tin doping concentration of about 10 wt%. However, the heterojunction solar cell obtained by using the 9010 target material has poor reliability, and is mainly reflected in severe attenuation in a sodium resistance test, a damp heat test (DH) and a thermal cycle Test (TC). The applicant analyzes the reason and speculates that the TCO target material with high tin doping concentration has more defects formed inside the film and poor compactness when the TCO target material is prepared into the TCO film by the PVD technology, and particles which damage the cell structure cannot be effectively prevented from entering the cell. The applicant further speculates that the target with low doping concentration is adopted, the content of impurity ions is low, the defects formed inside the TCO film prepared by the PVD technology are few, the compactness of the film is good, and particles damaging the structure of the cell can be effectively prevented from entering the cell, so that the reliability of the cell is improved, and the aging attenuation of the cell is reduced. However, the indium oxide ceramic target with a low tin doping concentration is difficult to prepare, so the cost is high, and the efficiency of the formed heterojunction solar cell is reduced. The applicant has explored a heterojunction solar cell with a novel structure by comprehensively considering the cost, efficiency and reliability of the heterojunction solar cell.
When the TCO film is prepared by PVD, the oxygen partial pressure also has certain influence on the reliability of the battery, mainly by adjusting the oxygen vacancy defect in the TCO film; generally, the oxygen vacancy concentration in the TCO film is low under the high oxygen condition, and the reliability of the cell is good; the oxygen vacancy concentration in the TCO film is higher under the low oxygen condition, and the reliability of the battery is poorer.
The technical solutions in the embodiments of the present application will be described below with reference to the drawings in the embodiments of the present application.
In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are some embodiments of the present application, but not all embodiments. The components of the embodiments of the present application, generally described and illustrated in the figures herein, can be arranged and designed in a wide variety of different configurations.
Thus, the following detailed description of the embodiments of the present application, as presented in the figures, is not intended to limit the scope of the claimed application, but is merely representative of selected embodiments of the application. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.
It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, it need not be further defined and explained in subsequent figures.
In the description of the present application, it should be noted that the terms "upper", "lower", "inner", "outer", and the like indicate orientations or positional relationships based on orientations or positional relationships shown in the drawings or orientations or positional relationships conventionally found in use of products of the application, and are used only for convenience in describing the present application and for simplification of description, but do not indicate or imply that the referred devices or elements must have a specific orientation, be constructed in a specific orientation, and be operated, and thus should not be construed as limiting the present application. Furthermore, the terms "first," "second," "third," and the like are used solely to distinguish one from another and are not to be construed as indicating or implying relative importance.
In the description of the present application, it is also to be noted that, unless otherwise explicitly specified or limited, the term "disposed" is to be understood broadly, for example, as being fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meaning of the above terms in the present application can be understood in a specific case by those of ordinary skill in the art.
First embodiment
Referring to fig. 1, the heterojunction solar cell 100 provided in the present embodiment includes a silicon substrate 110, the silicon substrate 110 has two surfaces, which are a front surface (a direct light surface) and a back surface (an opposite surface to the direct light surface), the front surface of the silicon substrate 110 is sequentially stacked with a front passivation layer 120, an n-type doping layer 130, a front TCO layer and a front electrode 150, the back surface of the silicon substrate 110 is sequentially stacked with a back passivation layer 160, a p-type doping layer 170, a back TCO layer and a back electrode 190, the front TCO layer and/or the back TCO layer includes at least two stacked TCO films, wherein the TCO films at a middle part of the layers are low-doped TCO films, and the TCO films at a part of the layers are high-doped TCO films.
In this embodiment, the silicon substrate 110 is an n-type single crystal silicon substrate.
In the embodiment of the present application, the front passivation layer 120 is an intrinsic silicon passivation layer, such as an intrinsic amorphous silicon passivation layer or an intrinsic microcrystalline silicon passivation layer, and the thickness of the front passivation layer 120 is 4-10 nm. The back passivation layer 160 is an intrinsic silicon passivation layer, such as an intrinsic amorphous silicon passivation layer or an intrinsic microcrystalline silicon passivation layer, and the thickness of the back passivation layer 160 is 4-10 nm. In this embodiment, the front passivation layer 120 is an intrinsic amorphous silicon passivation layer a-Si with a thickness of 8nm H (i).
In the embodiment of the present application, the n-type doped layer 130 is an n-type doped amorphous silicon layer or an n-type doped microcrystalline silicon layer, the doping concentration is 0.5-5 wt%, and the thickness of the n-type doped layer 130 is 5-15 nm. In this embodiment, the n-type doped layer 130 is an n-type doped amorphous silicon layer a-Si of 10nm in thickness, H (i) < n > film.
In the embodiment of the present application, the p-type doped layer 170 is a p-type doped amorphous silicon layer or a p-type doped microcrystalline silicon layer, the doping concentration is 0.5-5 wt%, and the thickness of the p-type doped layer 170 is 8-20 nm. In this embodiment, the p-type doped layer 170 is a p-type doped amorphous silicon layer a-Si with a thickness of 12nm, H (i) < p > film.
In the embodiment of the application, the highly doped TCO film with relatively high doping concentration and the lowly doped TCO film with relatively low doping concentration are combined and matched together, so that the cost, the efficiency and the reliability of the heterojunction solar cell 100 are considered. TCO films are tin-doped or undoped indium oxide-based or zinc oxide-based films, e.g. tin-doped indium oxide (ITO, In)2O3: sn), aluminum-doped zinc oxide (AZO, ZnO: al), fluorine-doped tin oxide (FTO, SnO)2: F) antimony doped tin oxide (ATO, Sn)2O: sb) with the doping concentration of 0-20 wt%, wherein the doping concentration of the low-doped TCO film is 0-5 wt% (low doping range), and the doping concentration of the high-doped TCO film is 8-15 wt% (high doping range). The thickness of the TCO film is 10-80nm, wherein the thickness of the low-doped TCO film is 10-80nm, and the thickness of the high-doped TCO film is 20-80 nm.
In this embodiment, the front TCO layer and the back TCO layer are respectively and simultaneously provided with the low-doped TCO film and the high-doped TCO film, that is, the low-doped TCO film and the high-doped TCO film in the front TCO layer and the back TCO layer are respectively and sequentially or alternately arranged according to the gradual change of the doping concentration. In other embodiments, it is also possible to use the above design for the front TCO layer only, and the back TCO layer in a conventional design, i.e. a single TCO film, or the design for the back TCO layer and the front TCO layer in a conventional design, i.e. a single TCO film.
For the case that the low-doped TCO film and the high-doped TCO film of the front TCO layer are sequentially disposed according to the gradual change of the doping concentration, as an embodiment, the front TCO layer includes at least two layers of TCO films, and the doping concentrations of the TCO films of the layers are sequentially decreased in the direction from the vicinity to the direction away from the silicon substrate 110.
In another embodiment, the front TCO layer includes an even number of TCO films, all TCO films are grouped in pairs in a direction from adjacent to far from the silicon substrate 110, and the doping concentration of the TCO film adjacent to the silicon substrate 110 in each group is greater than the doping concentration of the TCO film far from the silicon substrate 110.
In any case, in the front TCO layer, there must be a highly doped TCO film, a low doped TCO film, and a TCO film that is not a highly doped TCO film or a low doped TCO film (i.e., the doping concentration is not in the highly doped range or in the low doped range) in the TCO film.
In this embodiment, the front-side TCO layer includes two TCO films, which are respectively a first front-side TCO film 141 and a second front-side TCO film 142 arranged in a direction from adjacent to a direction away from the silicon substrate 110, where the first front-side TCO film 141 is an indium oxide-based TCO film (highly doped TCO film) having a thickness of 20nm and a tin doping concentration of 10 wt%, and the second front-side TCO film 142 is an indium oxide-based TCO film (lowly doped TCO film) having a thickness of 70nm and a tin doping concentration of 3 wt%. In other embodiments, the front-side TCO layer includes n TCO films, n > 3, respectively labeled TCO1, TCO2, TCO3, … …, and TCOn, all of which have decreasing doping concentrations in the direction from adjacent to away from the silicon substrate 110 (in deposition order), and the doping concentrations of TCO1, TCO2, TCO3, … …, and TCOn decrease from 20 wt% to 1 wt%, respectively.
For the case that the low-doped TCO film and the high-doped TCO film of the back TCO layer are sequentially disposed according to the gradual change of the doping concentration, as an embodiment, the back TCO layer includes at least two TCO films, and the doping concentrations of the TCO films of the respective layers are sequentially increased in the direction from the vicinity to the direction away from the silicon substrate 110.
For the case that the low-doped TCO film and the high-doped TCO film of the back TCO layer are alternately disposed, as another embodiment, the back TCO layer includes even number of TCO films, all TCO films are grouped in pairs in a direction from adjacent to far from the silicon substrate 110, and the doping concentration of the TCO film adjacent to the silicon substrate 110 in each group is less than the doping concentration of the TCO film far from the silicon substrate 110.
In any case, in the back TCO layer, there must be a highly doped TCO film, a low doped TCO film, and a TCO film that is not a highly doped TCO film or a low doped TCO film (i.e., the doping concentration is not within the high doping range or the low doping range) in the TCO film.
In this embodiment, the back TCO layer includes two TCO films, which are respectively a first back TCO film 181 and a second back TCO film 182 arranged in a direction from adjacent to a direction away from the silicon substrate 110, where the first back TCO film 181 is an indium oxide-based TCO film (low-doped TCO film) having a thickness of 20nm and a tin doping concentration of 3 wt%, and the second back TCO film 182 is an indium oxide-based TCO film (high-doped TCO film) having a thickness of 70nm and a tin doping concentration of 10 wt%. In other embodiments, the back TCO layer may further include n TCO films, where n > 3, which are respectively labeled as TCO1, TCO2, TCO3, … …, and TCOn, where doping concentrations of all the TCO films increase sequentially from adjacent to far from the silicon substrate 110 (in the deposition sequence), and doping concentrations of TCO1, TCO2, TCO3, … …, and TCOn increase sequentially from 1 wt% to 20 wt%, respectively.
In the embodiment of the present application, the front electrode 150 is a silver grid line electrode, and the thickness is 2-50 μm. The back electrode 190 is a silver grid line electrode with a thickness of 2-50 μm. In this embodiment, the front electrode 150 and the back electrode 190 are both metal silver grating lines with a thickness of 20 μm.
The embodiment also provides a method for manufacturing the heterojunction solar cell 100, which includes the following steps:
first, a front passivation layer 120, an n-type doped layer 130 and a front TCO layer are sequentially deposited on the front surface of the silicon substrate 110, and a back passivation layer 160, a p-type doped layer 170 and a back TCO layer are sequentially deposited on the back surface of the silicon substrate 110.
The deposition method of the TCO film comprises the following steps: radio frequency sputtering, direct current sputtering or pulse sputtering; corresponding PVD comprises vertical PVD, inclined PVD, horizontal PVD and the like; the target is a plane target or a rotary target; the pressure of a deposition process cavity of the TCO film is 0.1-1 Pa; the argon flow is 400-; the oxygen flow is 5-50 sccm; the temperature of the silicon substrate 110 is 100-220 ℃; the power is 5-20 kW.
The front passivation layer 120, the n-type doped layer 130, the back passivation layer 160, and the p-type doped layer 170 may respectively adopt PECVD, cat.cvd, HWCVD, or other chemical vapor deposition methods; the temperature of the silicon substrate 110 is 150-250 ℃; the pressure of the process chamber is 10-100 Pa.
Next, a front electrode 150 is formed on the surface of the front TCO layer, and a back electrode 190 is formed on the surface of the back TCO layer.
The front electrode 150 and the back electrode 190 may be prepared by the following steps: and the method adopts screen printing, evaporation, magnetron sputtering or ink-jet printing and the like.
Specifically, the preparation method of the heterojunction solar cell 100 of the present embodiment is as follows:
the n-type monocrystalline silicon is used as the silicon substrate 110, and the cleaning and texturing are performed to form the pyramid-shaped light trapping structure.
Then, an a-Si H (i) film with a thickness of 8nm is deposited on both sides as the front passivation layer 120 and the back passivation layer 160 by using a chemical vapor deposition method such as PECVD, Cat. CVD, HWCVD, etc., and an a-Si H (i) film with a thickness of 10nm is deposited in sequence as the n-type doped layer 130 and an a-Si H (i) film with a thickness of 12nm is deposited as the p-type doped layer 170.
And sequentially depositing an indium oxide-based TCO film (a first back TCO film 181) with the thickness of 20nm and the tin doping concentration of 3 wt% and an indium oxide-based TCO film (a second back TCO film 182) with the thickness of 70nm and the tin doping concentration of 10 wt% on a-Si: H (i) < p > under the conditions that the power is adjusted to be 13KW, the argon flow is 800sccm, and the oxygen flow is 35sccm and 10sccm respectively by using a pulse magnetron sputtering method.
And then, sequentially depositing an indium oxide-based TCO film (a first front TCO film 141) with the thickness of 20nm and the tin doping concentration of 10 wt% and depositing an indium oxide-based TCO film (a second front TCO film 142) with the thickness of 70nm and the tin doping concentration of 3 wt% on the conditions that the power is adjusted to be 13KW, the argon flow is 800sccm and the oxygen flow is 12sccm and 30sccm respectively by using a-Si (H) (i) < n >.
Finally, metal silver grid lines with the thickness of 20 microns are printed on the second front TCO film 142 and the second back TCO film 182 respectively through a screen printing method to serve as the front electrode 150 and the back electrode 190.
The heterojunction solar cell 100 manufactured by the conventional process passes a sodium resistance test, a damp heat test (DH), and a thermal cycle Test (TC), and has an aging degradation of 8% in the first test, 9% in the second test, and 8% in the third test. The heterojunction solar cell 100 of the present example had an aging degradation of 1.5% in the first test, 2.5% in the second test, and 2% in the third test.
Therefore, compared with the conventional heterojunction solar cell 100, the heterojunction solar cell 100 of the embodiment improves the conductivity of the TCO layer, improves the carrier collection efficiency, enhances the current collection, and can effectively reduce the aging degradation and improve the reliability.
Second embodiment
Referring to fig. 2, the heterojunction solar cell 200 provided in this embodiment includes a silicon substrate 110, a front passivation layer 120, an n-type doping layer 130, a front TCO layer, and a front electrode 150 are sequentially stacked on the front surface of the silicon substrate 110, a back passivation layer 160, a p-type doping layer 170, a back TCO layer, and a back electrode 190 are sequentially stacked on the back surface of the silicon substrate 110, the front TCO layer and the back TCO layer respectively include four stacked TCO films, two TCO films are low-doped TCO films with a doping concentration of 0-5 wt%, and two TCO films are high-doped TCO films with a doping concentration of 8-15 wt%.
Specifically, the silicon substrate 110 is an n-type single crystal silicon substrate.
The front passivation layer 120 and the back passivation layer 160 are intrinsic amorphous silicon passivation layers a-Si h (i) having a thickness of 8 nm.
The n-type doped layer 130 is an n-type doped amorphous silicon layer a-Si of 10nm in thickness, H (i) < n > film.
The p-type doped layer 170 is a p-type doped amorphous silicon layer a-Si of 12nm thickness H (i) < p > film.
The front-side TCO layer comprises four TCO films, the two TCO films are respectively a first front-side TCO film 211, a second front-side TCO film 212, a third front-side TCO film 213 and a fourth front-side TCO film 214 which are arranged in the direction from the adjacent direction to the far direction away from the silicon substrate 110, the first front-side TCO film 211 is an indium oxide-based TCO film (high-doped TCO film) with the thickness of 10nm and the tin doping concentration of 10 wt%, the second front-side TCO film 212 is an indium oxide-based TCO film (low-doped TCO film) with the thickness of 20nm and the tin doping concentration of 3 wt%, the third front-side TCO film 213 is an indium oxide-based TCO film (high-doped TCO film) with the thickness of 30nm and the tin doping concentration of 10 wt%, and the fourth front-side TCO film 214 is an indium oxide-based TCO film (low-doped TCO film) with the thickness of 30nm and the tin doping concentration of 3 wt%.
The back-side TCO layer includes four TCO films, which are respectively a first back-side TCO film 221, a second back-side TCO film 222, a third back-side TCO film 223, and a fourth back-side TCO film 224 arranged in a direction from adjacent to a direction away from the silicon substrate 110, the first back-side TCO film 221 is an indium oxide-based TCO film (low-doped TCO film) having a thickness of 10nm and a tin doping concentration of 3 wt%, the second back-side TCO film 222 is an indium oxide-based TCO film (high-doped TCO film) having a thickness of 20nm and a tin doping concentration of 10 wt%, the third back-side TCO film 223 is an indium oxide-based TCO film (low-doped TCO film) having a thickness of 30nm and a tin doping concentration of 3 wt%, and the fourth back-side TCO film 224 is an indium oxide-based TCO film (high-doped TCO film) having a thickness of 30nm and a tin doping concentration of 10 wt%.
The front electrode 150 and the back electrode 190 are metal silver grid lines with a thickness of 20 μm.
The preparation method of the heterojunction solar cell 200 is as follows:
the n-type monocrystalline silicon is used as the silicon substrate 110, and the cleaning and texturing are performed to form the pyramid-shaped light trapping structure.
Then, an a-Si h (i) film with a thickness of 8nm is deposited on both sides as the front passivation layer 120 and the back passivation layer 160 by using a chemical vapor deposition method such as PECVD, cat.cvd, HWCVD, etc., and a-Si h (i) n > film with a thickness of 10nm and a-Si h (i) p > film with a thickness of 12nm are sequentially deposited as the n-doped layer 130 and the p-doped layer 170.
And then, sequentially depositing an indium oxide-based TCO film (a first front TCO film 211) with tin doping concentration of 10nm being 3 wt%, an indium oxide-based TCO film (a second front TCO film 212) with tin doping concentration of 20nm being 10 wt%, an indium oxide-based TCO film (a third front TCO film 213) with tin doping concentration of 30nm being 3 wt%, and an indium oxide-based TCO film (a fourth front TCO film 214) with tin doping concentration of 30nm being 10 wt% on the a-Si: H (i) < p > under the conditions that the power is adjusted to be 13KW, the argon flow is 800sccm, and the oxygen flow is 35sccm, 20sccm, 10sccm and 5sccm respectively.
And then, sequentially depositing an indium oxide-based TCO film (a first back TCO film 221) with 10 wt% of tin doping concentration of 10nm, an indium oxide-based TCO film (a second back TCO film 222) with 3 wt% of tin doping concentration of 20nm, an indium oxide-based TCO film (a third back TCO film 223) with 10 wt% of tin doping concentration of 30nm and an indium oxide-based TCO film (a fourth back TCO film 224) with 3 wt% of tin doping concentration of 30nm by using a pulse magnetron sputtering method under the conditions that the power is adjusted to be 13KW, the argon flow is 800sccm, and the oxygen flow is 5sccm, 10sccm, 15sccm and 25sccm respectively.
Finally, metal silver grid lines with the thickness of 20 microns are printed on the fourth front-surface TCO film 214 and the fourth back-surface TCO film 224 respectively through a silk-screen printing method to serve as the front-surface electrode 150 and the back-surface electrode 190.
In summary, the heterojunction solar cell 200 and the preparation method thereof according to the embodiment of the present application effectively improve the reliability of the heterojunction solar cell 200 and slow down the aging degradation of the heterojunction solar cell 200 while ensuring the cost and efficiency of the cell.
The above description is only an example of the present application and is not intended to limit the scope of the present application, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, improvement and the like made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims (10)

1. The heterojunction solar cell is characterized by comprising a silicon substrate, wherein a front passivation layer, an n-type doping layer, a front TCO layer and a front electrode are sequentially stacked on the front surface of the silicon substrate, a back passivation layer, a p-type doping layer, a back TCO layer and a back electrode are sequentially stacked on the back surface of the silicon substrate, the front TCO layer and/or the back TCO layer comprise at least two layers of TCO films, the TCO films with the middle layer number are low-doped TCO films with the doping concentration of 0-5 wt%, and the TCO films with the partial layer number are high-doped TCO films with the doping concentration of 8-15 wt%.
2. The heterojunction solar cell of claim 1, wherein the thickness of the low doped TCO thin film is 10-80 nm; the thickness of the highly doped TCO film is 20-80 nm.
3. The heterojunction solar cell of claim 1, wherein the front-side TCO layer comprises at least two TCO films, each of the TCO films having a doping concentration that decreases in a direction from adjacent to away from the silicon substrate;
or the front TCO layer comprises even TCO films, every two TCO films form a group along the direction from the adjacent position to the position far away from the silicon substrate, and the doping concentration of the TCO film close to the silicon substrate in each group is larger than that of the TCO film far away from the silicon substrate.
4. The heterojunction solar cell of claim 1, wherein the back TCO layer comprises at least two TCO films, each of the TCO films having doping concentrations that increase sequentially from proximal to distal to the silicon substrate;
or the back TCO layer comprises even TCO films, every two TCO films form a group along the direction from the adjacent position to the position far away from the silicon substrate, and the doping concentration of the TCO film close to the silicon substrate in each group is smaller than that of the TCO film far away from the silicon substrate.
5. A heterojunction solar cell according to claim 1, wherein the front-side passivation layer and/or the back-side passivation layer is an intrinsic silicon passivation layer, the thickness of the front-side passivation layer and/or the back-side passivation layer being 4-10 nm.
6. The heterojunction solar cell of claim 1, wherein the n-type doped layer is an n-type doped amorphous silicon or microcrystalline silicon layer, the doping concentration is 0.5-5 wt%, and the thickness of the n-type doped layer is 5-15 nm;
and/or the p-type doped layer is a p-type doped amorphous silicon or microcrystalline silicon layer, the doping concentration is 0.5-5 wt%, and the thickness of the p-type doped layer is 8-20 nm.
7. A heterojunction solar cell according to claim 1, wherein the front electrode and/or the back electrode is a silver grid electrode having a thickness of 2-50 μm.
8. A method of manufacturing a heterojunction solar cell as claimed in any of claims 1 to 7, comprising the steps of:
depositing and forming the front passivation layer, the n-type doping layer and the front TCO layer on the front side of the silicon substrate in sequence, and depositing and forming the back passivation layer, the p-type doping layer and the back TCO layer on the back side of the silicon substrate in sequence;
and preparing the front electrode on the surface of the front TCO layer, and preparing the back electrode on the surface of the back TCO layer.
9. The method for preparing a heterojunction solar cell according to claim 8, wherein the deposition method of the TCO film is as follows: radio frequency sputtering, direct current sputtering or pulse sputtering; the target is a plane target or a rotary target;
the TCO film deposition method comprises the following steps: the pressure of the process cavity is 0.1-1 Pa; the argon flow is 400-; the oxygen flow is 5-50 sccm; the temperature of the silicon substrate is 100-220 ℃; the power is 5-20 kW.
10. The method of claim 8, wherein the front electrode and the back electrode are prepared by: screen printing, evaporation, magnetron sputtering or ink jet printing;
and/or the front passivation layer, the n-type doped layer, the back passivation layer and the p-type doped layer are deposited by the following methods: PECVD, cat.cvd or HWCVD; the temperature of the silicon substrate in the deposition method is 150-250 ℃; the pressure of the process chamber is 10-100 Pa.
CN202110596804.2A 2021-05-28 2021-05-28 Heterojunction solar cell and preparation method thereof Pending CN113224182A (en)

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