WO2023274081A1 - 一种异质结太阳能电池及其制备方法 - Google Patents

一种异质结太阳能电池及其制备方法 Download PDF

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WO2023274081A1
WO2023274081A1 PCT/CN2022/101228 CN2022101228W WO2023274081A1 WO 2023274081 A1 WO2023274081 A1 WO 2023274081A1 CN 2022101228 W CN2022101228 W CN 2022101228W WO 2023274081 A1 WO2023274081 A1 WO 2023274081A1
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conductive film
transparent conductive
sub
grid line
gate line
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PCT/CN2022/101228
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English (en)
French (fr)
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辛科
周肃
龚道仁
王文静
徐晓华
梅志纲
杨龙
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安徽华晟新能源科技有限公司
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Priority to EP22831895.2A priority Critical patent/EP4345913A1/en
Publication of WO2023274081A1 publication Critical patent/WO2023274081A1/zh

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L31/02—Details
    • H01L31/0224—Electrodes
    • H01L31/022466—Electrodes made of transparent conductive layers, e.g. TCO, ITO layers
    • H01L31/022483—Electrodes made of transparent conductive layers, e.g. TCO, ITO layers composed of zinc oxide [ZnO]
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L31/02—Details
    • H01L31/0224—Electrodes
    • H01L31/022408—Electrodes for devices characterised by at least one potential jump barrier or surface barrier
    • H01L31/022425—Electrodes for devices characterised by at least one potential jump barrier or surface barrier for solar cells
    • H01L31/022441—Electrode arrangements specially adapted for back-contact 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
    • H01L31/0248—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 characterised by their semiconductor bodies
    • H01L31/0256—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 characterised by their semiconductor bodies characterised by the material
    • H01L31/0264—Inorganic materials
    • H01L31/028—Inorganic materials including, apart from doping material or other impurities, only elements of Group IV of the Periodic System
    • H01L31/0288—Inorganic materials including, apart from doping material or other impurities, only elements of Group IV of the Periodic System characterised by the doping material
    • 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 at least one potential-jump barrier or surface barrier
    • H01L31/072—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 at least one potential-jump barrier or surface barrier the potential barriers being only of the PN heterojunction type
    • H01L31/074—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 at least one potential-jump barrier or surface barrier the potential barriers being only of the PN heterojunction type comprising a heterojunction with an element of Group IV of the Periodic System, e.g. ITO/Si, GaAs/Si or CdTe/Si 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
    • H01L31/18—Processes or apparatus specially adapted for the manufacture or treatment of these devices or of parts thereof
    • H01L31/1804—Processes 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
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L31/18—Processes or apparatus specially adapted for the manufacture or treatment of these devices or of parts thereof
    • H01L31/1884—Manufacture of transparent electrodes, e.g. TCO, ITO
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L31/18—Processes or apparatus specially adapted for the manufacture or treatment of these devices or of parts thereof
    • H01L31/1884—Manufacture of transparent electrodes, e.g. TCO, ITO
    • H01L31/1888—Manufacture of transparent electrodes, e.g. TCO, ITO methods for etching transparent electrodes
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00—Energy generation through renewable energy sources
    • Y02E10/50—Photovoltaic [PV] energy
    • Y02E10/547—Monocrystalline silicon PV cells
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

Definitions

  • the present application relates to the technical field of photovoltaic cells, in particular to a heterojunction solar cell and a preparation method thereof.
  • Solar cells are a kind of clean energy cells, and solar cells are widely used in life and production. Adding a layer of transparent conductive film (TCO) between the electrode and the amorphous silicon layer of solar cells, especially heterojunction solar cells, can effectively increase the collection of carriers and improve the conversion efficiency of solar cells.
  • TCO transparent conductive film
  • the transparent conductive film includes a front transparent conductive film and a back transparent conductive film.
  • the setting of the transparent conductive film leads to the problems of poor photoelectric conversion efficiency and packaging performance of heterojunction solar cells.
  • the optimization of the comprehensive performance of the back transparent conductive film has always been a research hotspot for those skilled in the art.
  • the technical problem to be solved in the present application is to overcome the problems of poor photoelectric conversion efficiency and packaging performance of heterojunction solar cells in the prior art, so as to provide a heterojunction solar cell.
  • the present application provides a heterojunction solar cell, comprising: a semiconductor substrate layer; a back composite transparent conductive film located on one side of the semiconductor substrate layer; the back composite transparent conductive film includes: a first back transparent conductive film; The second back transparent conductive film on the surface of the first back transparent conductive film facing away from the semiconductor substrate layer; both the first back transparent conductive film and the second back transparent conductive film are doped with Group III heavy atoms, the concentration of group III heavy atoms in the second back transparent conductive film is less than the concentration of group III heavy atoms in the first back transparent conductive film.
  • the group III heavy atoms include gallium atoms; the material of the first back transparent conductive film includes gallium-doped zinc oxide; the material of the second back transparent conductive film includes gallium-doped zinc oxide.
  • the ratio of the mass percent concentration of gallium in the second back transparent conductive film to the mass percent concentration of gallium in the first back transparent conductive film is 1:2-1:4.
  • the mass percent concentration of gallium in the first back transparent conductive film is 1.5%-2%; the mass percent concentration of gallium in the second back transparent conductive film is 0.5%-1%.
  • the ratio of the thickness of the second back transparent conductive film to the thickness of the first back transparent conductive film is 1:4-1:3.
  • the thickness of the second back transparent conductive film is 10nm-20nm; the thickness of the first back transparent conductive film is 50nm-60nm.
  • the heterojunction solar cell further includes: an organic encapsulation layer located on a surface of the second back transparent conductive film facing away from the first back transparent conductive film.
  • the composite transparent conductive film on the back also includes: a third transparent conductive film on the back, the work function of the third transparent conductive film on the back is higher than that of the first transparent conductive film on the back and higher than that of the second transparent conductive film on the back.
  • the work function of the conductive film is higher than that of the first transparent conductive film on the back and higher than that of the second transparent conductive film on the back.
  • the mobility of the third back transparent conductive film is greater than the mobility of the first back transparent conductive film and greater than the mobility of the second back transparent conductive film; in the third back transparent conductive film
  • the concentration of dopant ions is lower than the concentration of group III heavy atoms in the first back transparent conductive film and lower than the concentration of group III heavy atoms in the second back transparent conductive film.
  • the material of the third back transparent conductive film includes tungsten-doped indium oxide.
  • the mass percent concentration of tungsten in the tungsten-doped indium oxide is 0.1%-0.3%.
  • the ratio of the thickness of the third back transparent conductive film to the thickness of the first back transparent conductive film is 1:5-1:6.
  • it also includes: a back gate line located on the back side of the composite transparent conductive film facing away from the semiconductor substrate layer; the back gate line includes a first sub-back gate line and a The second sub-back gate line on the surface of the semiconductor substrate layer; the conductivity of the first sub-back gate line is greater than the conductivity of the second sub-back gate line; the second sub-back gate line The melting point is lower than the melting point of the first sub-back gate line.
  • the material of the first sub-back gate line includes copper; the material of the second sub-back gate line includes tin.
  • the relationship between the thickness of the first sub-back gate line and the thickness of the second sub-back gate line is 5:1-9:1.
  • the aspect ratio of the back gate line is 0.8:2-1:2; the width of the back gate line is 9 ⁇ m-11 ⁇ m, and the height of the back gate line is 4 ⁇ m-6 ⁇ m.
  • it also includes: a first doped semiconductor layer located between the semiconductor substrate layer and the back composite transparent conductive film; the first doped semiconductor layer is in a nanocrystalline state; or, the first The doped semiconductor layer is microcrystalline.
  • the concentration of dopant ions in the first doped semiconductor layer is 2E19atom/cm 3 -8E19atom/cm 3 .
  • it also includes: a front composite transparent conductive film located on the side of the semiconductor substrate layer facing away from the back composite transparent conductive film; the material of the front composite transparent conductive film includes tungsten-doped indium oxide.
  • it also includes: a second doped semiconductor layer located between the semiconductor substrate layer and the front composite transparent conductive film; the second doped semiconductor layer is in a nanocrystalline state; or, the second The doped semiconductor layer is microcrystalline.
  • the heterojunction solar cell further includes: a positive grid line located on the side of the front composite transparent conductive film facing away from the semiconductor substrate layer; the positive grid line includes a first sub-positive grid line and The first sub-positive grid line faces away from the second sub-positive grid line on the surface of the semiconductor substrate layer; the conductivity of the first sub-positive grid line is greater than the conductivity of the second sub-positive grid line; The melting point of the second sub positive grid line is lower than that of the first sub positive grid line.
  • the material of the first sub-positive grid line includes copper; the material of the second sub-positive grid line includes tin.
  • the relationship between the thickness of the first sub-positive grid line and the thickness of the second sub-positive grid line is 5:1-9:1.
  • the aspect ratio of the positive grid line is 0.8:2-1:2; the width of the positive grid line is 4 ⁇ m-6 ⁇ m, and the height of the positive grid line is 2.5 ⁇ m-3.5 ⁇ m.
  • the present application also provides a method for preparing a heterojunction solar cell, comprising: providing a semiconductor substrate layer; forming a back composite transparent conductive film on one side of the semiconductor substrate layer; the method for forming the back composite transparent conductive film includes: A first back transparent conductive film is formed on one side of the semiconductor substrate layer; a second back transparent conductive film is formed on the surface of the first back transparent conductive film facing away from the semiconductor substrate layer; the first back Both the transparent conductive film and the second back transparent conductive film are doped with group III heavy atoms, and the concentration of group III heavy atoms in the second back transparent conductive film is lower than that of the group III heavy atoms in the first back transparent conductive film. concentration of atoms.
  • the method for forming the back composite transparent conductive film further includes: before forming the first back transparent conductive film, forming a third back transparent conductive film on one side of the semiconductor substrate layer; forming the second back transparent conductive film; After a back transparent conductive film, the third back transparent conductive film is located between the first back transparent conductive film and the semiconductor substrate layer; the work function of the third back transparent conductive film is higher than that of the first back transparent conductive film The work function of the conductive film is higher than the work function of the second back transparent conductive film.
  • the mobility of the third back transparent conductive film is greater than the mobility of the first back transparent conductive film and greater than the mobility of the second back transparent conductive film; in the third back transparent conductive film
  • the concentration of dopant ions is lower than the concentration of group III heavy atoms in the first back transparent conductive film and lower than the concentration of group III heavy atoms in the second back transparent conductive film.
  • it also includes: forming a back gate line on the side of the back compound transparent conductive film facing away from the semiconductor substrate layer; the step of forming the back gate line includes: forming a back gate line on the surface of the back compound transparent conductive film Forming a patterned first photoresist layer, the first photoresist layer has a first gate line opening; using an evaporation process to form a back gate line in the first gate line opening; using an evaporation process to form a back grid line After the back gate line is formed in the first gate line opening, the first photoresist layer is removed.
  • the step of forming a back gate line in the first gate line opening by using an evaporation process includes: forming a first sub-back gate line in the first gate line opening by an evaporation process; A second sub-back gate line located on the surface of the first sub-back gate line is formed in the opening of the first gate line; the conductivity of the first sub-back gate line is greater than that of the second sub-back gate line; The melting point of the second sub-back gate line is lower than the melting point of the first sub-back gate line.
  • the preparation method of the heterojunction solar cell further includes: forming a front composite transparent conductive film on the other side of the semiconductor substrate layer; the material of the front composite transparent conductive film includes tungsten-doped indium oxide.
  • the preparation method of the heterojunction solar cell further includes: forming a positive grid line on the side of the front composite transparent conductive film facing away from the semiconductor substrate layer; the step of forming the positive grid line includes: A patterned second photoresist layer is formed on the surface of the composite transparent conductive film on the front side, and a second grid line opening is formed in the second photoresist layer; an evaporation process is adopted in the second grid line opening Forming a positive gate line; removing the second photoresist layer after forming the positive gate line in the opening of the second gate line by using an evaporation process.
  • the step of forming a positive grid line in the second grid line opening by using an evaporation process includes: forming a first sub-positive grid line in the second grid line opening by an evaporation process; A second sub-positive grid line located on the surface of the first sub-positive grid line is formed in the opening of the second grid line; the conductivity of the first sub-positive grid line is greater than that of the second sub-positive grid line; The melting point of the second sub positive grid line is lower than that of the first sub positive grid line.
  • it also includes: forming a first doped semiconductor layer on one side of the semiconductor substrate layer; the first doped semiconductor layer is nanocrystalline; or, the first doped semiconductor layer is microcrystalline state; after forming the back composite transparent conductive film, the first doped semiconductor layer is located between the semiconductor substrate layer and the back composite transparent conductive film.
  • the process of forming the first doped semiconductor layer includes a plasma chemical vapor deposition process
  • the parameters of the plasma chemical vapor deposition process include: the gas used includes H 2 , SiH 4 and B 2 H 6 , H 2
  • the flow ratio of SiH 4 and SiH 4 is 200:1.8-200:2.3
  • the flow ratio of B 2 H 6 and SiH 4 is 1:1-1:5
  • the chamber pressure is 0.3Pa-0.5Pa
  • the RF power density is 0.25mW /cm 2 -0.4mW/cm 2 .
  • the heterojunction solar cell comprises a composite transparent conductive film on the back side; the composite transparent conductive film on the back side comprises: a first transparent conductive film on the back side; the transparent conductive film located on the first back side faces away from the semiconductor substrate
  • the second back transparent conductive film on one side of the bottom layer, the first back transparent conductive film and the second back transparent conductive film are doped with group III heavy atoms. Due to the large atomic weight of group III heavy atoms, the density of the first back transparent conductive film doped with group III heavy atoms becomes larger, and the density of the second back transparent conductive film doped with group III heavy atoms becomes larger.
  • both the first back transparent conductive film and the second back transparent conductive film becomes larger, and the gallium atoms at the interface between the second back transparent conductive film and the organic encapsulation layer are covered by more C-H bonds of the organic encapsulation layer. That is, the gallium atoms at the interface can combine with more C-H bonds, thereby making the binding force between the second back transparent conductive film and the organic encapsulation layer stronger.
  • the concentration of group III heavy atoms in the second back transparent conductive film is less than the concentration of group III heavy atoms in the first back transparent conductive film, and the concentration of group III heavy atoms in the second back transparent conductive film is smaller, In this way, the surface defect state density of the second back transparent conductive film is reduced, and the binding force between the second back transparent conductive film and the organic encapsulation layer is enhanced.
  • the hardness of the first back transparent conductive film and the second back transparent conductive film are increased, which also makes the binding force between the first back transparent conductive film and the second back transparent conductive film larger. To sum up, the binding force between the back composite transparent conductive film and the organic encapsulation layer is enhanced, and the encapsulation performance of the heterojunction solar cell is improved.
  • the concentration of group III heavy atoms in the first back transparent conductive film is relatively large, the free carrier concentration in the first back transparent conductive film is more, and the conductivity of the first back transparent conductive film is better than that of the second back transparent conductive film.
  • the conductive ability of the conductive film makes the conductive ability of the back composite transparent conductive film better, and the ability of the back composite transparent conductive film to collect carriers is better, which is conducive to improving the photoelectric conversion efficiency of the heterojunction solar cell.
  • the group III heavy atoms include gallium atoms; the material of the first back transparent conductive film includes gallium-doped zinc oxide; the material of the second back transparent conductive film includes gallium-doped zinc oxide.
  • Gallium-doped zinc oxide not only has the advantage of lower price, which reduces the cost of heterojunction solar cells, but also has the advantage of high mobility, which can improve the transparent conductive film on the first back and the transparent conductive film on the second back. The conductivity of the film.
  • the back composite transparent conductive film also includes a third back transparent conductive film, the work function of the third back transparent conductive film is higher than the work function of the first back transparent conductive film and higher than the second back transparent conductive film The work function of the membrane. Since the work function of the third back transparent conductive film is relatively high, the bandgap mismatch between the third back transparent conductive film and the first doped semiconductor layer is reduced, that is, the back compound transparent conductive film and the first doped The bandgap mismatch between the semiconductor layers makes the valence band bending of the composite transparent conductive film on the back to the first doped semiconductor layer smaller, which facilitates tunneling of holes from the first doped semiconductor layer to the composite transparent conductive film on the back.
  • the Fermi energy level of the third back transparent conductive film will move up as the concentration of dopant ions in the third back transparent conductive film decreases, correspondingly, the work function of the third back transparent conductive film will decrease accordingly .
  • the concentration of dopant ions in the third back transparent conductive film is less than the concentration of group III heavy atoms in the first back transparent conductive film and lower than the concentration of group III heavy atoms in the second back transparent conductive film, so that The work function of the third rear transparent conductive film is relatively high.
  • the mobility of the third back transparent conductive film is greater than the mobility of the first back transparent conductive film and greater than the mobility of the second back transparent conductive film.
  • the third back transparent conductive film Since the mobility of the third back transparent conductive film is higher, even the third back transparent The concentration of doped ions in the conductive film is small, and the conductivity of the third back transparent conductive film will not be too small, that is to say, the third back transparent conductive film can still maintain good conductivity, and the third back transparent conductive film The contact resistance of the film to the first doped semiconductor layer is low.
  • the first doped semiconductor layer is a nanocrystalline state, or the first doped semiconductor layer is a microcrystalline state, and secondly, the concentration of doping ions in the first doped semiconductor layer is relatively high, so that the first doped semiconductor layer
  • the electrical conductivity of the semiconductor layer is improved, and the first doped semiconductor layer has a high doping concentration to improve field passivation, that is to say, the electric field intensity between the first doped semiconductor layer and the first intrinsic semiconductor layer becomes larger and more Good resistance to the diffusion of photogenerated electrons to the interface between the first doped semiconductor layer and the first intrinsic semiconductor layer allows more photogenerated electrons to diffuse to the front of the heterojunction solar cell, reducing the recombination probability of photogenerated carriers.
  • the volume resistance of the first doped semiconductor layer is reduced, reducing the contact resistance between the first doped semiconductor layer and the composite transparent conductive film on the back, improving the series resistance of the heterojunction solar cell, and improving the photoelectric conversion efficiency of the heterojunction solar cell .
  • FIG. 1 is a schematic structural diagram of a heterojunction solar cell provided by an embodiment of the present application.
  • FIG. 2 is a flow chart of a forming process of a heterojunction solar cell provided by an embodiment of the present application.
  • FIG. 3 to FIG. 7 are structural schematic diagrams of a manufacturing process of a heterojunction solar cell provided by another embodiment of the present application.
  • 100 semiconductor substrate layer; 110b, first intrinsic semiconductor layer; 110a, second intrinsic semiconductor layer; 130b, composite transparent conductive film on the back; 120b, first doped semiconductor layer; 120a, second doped semiconductor layer; 131, the first back transparent conductive film; 132, the second back transparent conductive film; 133, the third back transparent conductive film; 130a, the front composite transparent conductive film; 140b, the back grid line; 141b, the first sub-back grid line; 142b, the second sub-back grid line; 140a, the positive grid line; 141a, the first sub-positive grid line; 142a, the second sub-positive grid line.
  • connection should be understood in a broad sense, for example, it can be a fixed connection or a detachable connection. Connected, or integrally connected; it can be mechanically or electrically connected; it can be directly connected, or indirectly connected through an intermediary, or it can be the internal communication of two components, which can be wireless or wired connect. Those of ordinary skill in the art can understand the specific meanings of the above terms in this application in specific situations.
  • the heterojunction solar cell includes:
  • the back composite transparent conductive film 130b located on one side of the semiconductor substrate layer 100;
  • the back composite transparent conductive film 130b includes: a first back transparent conductive film 131; a second back transparent conductive film 132 located on the surface of the first back transparent conductive film 131 facing away from the semiconductor substrate layer 100; Both the first back transparent conductive film 131 and the second back transparent conductive film 132 are doped with group III heavy atoms, and the concentration of group III heavy atoms in the second back transparent conductive film 132 is lower than that of the first back transparent conductive film 132. concentration of Group III heavy atoms in the conductive film 131 .
  • the conductivity type of the semiconductor substrate layer 100 is N type. It should be noted that, in other embodiments, the conductivity type of the semiconductor substrate layer may also be P type.
  • the material of the semiconductor substrate layer 100 includes single crystal silicon.
  • Both the first back transparent conductive film 131 and the second back transparent conductive film 132 are doped with Group III heavy atoms. Due to the large atomic weight of group III heavy atoms, the density of the first back transparent conductive film 131 doped with group III heavy atoms becomes larger, and the density of the second back transparent conductive film 132 doped with group III heavy atoms becomes larger , the hardness of the first back transparent conductive film 131 and the second back transparent conductive film 132 becomes larger, and gallium atoms (Ga) at the interface between the second back transparent conductive film 132 and the organic encapsulation layer are absorbed by the organic encapsulation layer.
  • Ga gallium atoms
  • More C-H bond coverage means that gallium atoms at the interface can combine with more C-H bonds, thereby making the bonding force between the second back transparent conductive film 132 and the organic encapsulation layer stronger.
  • the concentration of group III heavy atoms in the second back transparent conductive film 132 is less than the concentration of group III heavy atoms in the first back transparent conductive film 131, and the concentration of group III heavy atoms in the second back transparent conductive film 132 is smaller, so that the surface defect state density of the second back transparent conductive film 132 is reduced, and the bonding force between the second back transparent conductive film 132 and the organic encapsulation layer is enhanced.
  • both the first back transparent conductive film 131 and the second back transparent conductive film 132 becomes larger, which also makes the binding force between the first back transparent conductive film 131 and the second back transparent conductive film 132 stronger.
  • the binding force between the composite transparent conductive film 130b on the back and the organic encapsulation layer is enhanced, and the encapsulation performance of the heterojunction solar cell is improved.
  • the concentration of group III heavy atoms in the first back transparent conductive film 131 is relatively large, the concentration of free carriers in the first back transparent conductive film 131 is relatively large, and the conductivity of the first back transparent conductive film 131 is excellent. Due to the conductive ability of the second back transparent conductive film 132, the conductive ability of the back composite transparent conductive film 130b is better, and the ability of the back composite transparent conductive film 130b to collect carriers is better, which is beneficial to improve the photoelectric conversion of the heterojunction solar cell efficiency.
  • the group III heavy atoms include gallium atoms. In this embodiment, the group III heavy atoms do not include aluminum atoms. The atomic weight of the group III heavy atoms is greater than or equal to the atomic weight of gallium atoms.
  • the material of the first back transparent conductive film 131 includes gallium-doped zinc oxide; the material of the second back transparent conductive film 132 includes gallium-doped zinc oxide.
  • the price of the zinc oxide-based materials is very cheap, which can significantly reduce the cost of the heterojunction solar cell.
  • the binding force between the gallium-doped zinc oxide and the organic packaging layer is relatively large.
  • the mobility of gallium-doped zinc oxide is greater than that of aluminum-doped zinc oxide.
  • Gallium-doped zinc oxide not only has the advantage of lower price, which reduces the cost of heterojunction solar cells, but also has the advantage of greater mobility.
  • the ratio of the mass percent concentration of gallium in the second back transparent conductive film 132 to the mass percent concentration of gallium in the first back transparent conductive film 131 is 1:2-1:4.
  • the advantage is that: the first back transparent conductive film 131 is heavily doped, and the conductivity of the first back transparent conductive film 131 is high; the second back transparent conductive film 132 is moderately doped, which is used to form a good connection with the organic packaging layer. combination.
  • the overall conductivity of the composite transparent conductive film 130 b on the back side is better and a good combination with the organic packaging layer is formed.
  • the mass percentage concentration of gallium in the first back transparent conductive film 131 is 1.5%-2%; the mass percentage concentration of gallium in the second back transparent conductive film 132 is 0.5%-1 %.
  • the ratio of the thickness of the second back transparent conductive film 132 to the thickness of the first back transparent conductive film 131 is 1:4-1:3.
  • the advantage of such a ratio range is: the thickness of the first back transparent conductive film 131 is relatively thick, so that the resistance of the first back transparent conductive film 131 is reduced, and the first back transparent conductive film 131 is used as the main conductive layer of the back composite transparent conductive film 130b
  • the thickness of the second back transparent conductive film 132 is relatively low, so that the thickness ratio of the moderately doped second back transparent conductive film 132 is relatively small relative to the heavily doped first back transparent conductive film 131 thickness, so that The conductivity of the composite transparent conductive film 130b on the back is improved.
  • the thickness of the second back transparent conductive film 132 is 10 nm-20 nm; the thickness of the first back transparent conductive film 131 is 50 nm-60 nm.
  • the heterojunction solar cell further includes: an organic encapsulation layer (not shown) located on the surface of the second back transparent conductive film 132 facing away from the first back transparent conductive film 131 .
  • the material of the organic encapsulation layer includes: polyethylene-olefin copolymer (POE), expandable polyethylene (EPE) or thermoplastic polyolefin elastomer (TPO).
  • the heterojunction solar cell further includes: a first doped semiconductor layer 120b located between the semiconductor substrate layer 100 and the back composite transparent conductive film 130b.
  • the back composite transparent conductive film 130b also includes: a third back transparent conductive film 133, the work function of the third back transparent conductive film 133 is higher than the work function of the first back transparent conductive film 131 and higher than the second back transparent conductive film.
  • the work function of the conductive film 132 Since the work function of the third back transparent conductive film 133 is relatively high, the bandgap mismatch between the third back transparent conductive film 133 and the first doped semiconductor layer 120b is reduced, that is, the relationship between the back composite transparent conductive film 130b and the first doped semiconductor layer 120b is reduced.
  • the bandgap mismatch between the first doped semiconductor layers 120b makes the valence band bending amount of the back compound transparent conductive film 130b to the first doped semiconductor layer 120b smaller, which facilitates hole tunneling from the first doped semiconductor layer 120b. Pass through to the back composite transparent conductive film 130b.
  • the mobility of the third back transparent conductive film 133 is greater than the mobility of the first back transparent conductive film 131 and greater than the mobility of the second back transparent conductive film 132; the third back transparent conductive film
  • the concentration of dopant ions in 133 is lower than the concentration of group III heavy atoms in the first back transparent conductive film 131 and lower than the concentration of group III heavy atoms in the second back transparent conductive film 132 .
  • the Fermi energy level of the third back transparent conductive film 133 will move up as the concentration of dopant ions in the third back transparent conductive film 133 decreases, and correspondingly, the work function of the third back transparent conductive film 133 will follow. reduce.
  • the concentration of dopant ions in the third back transparent conductive film 133 is lower than the concentration of group III heavy atoms in the first back transparent conductive film 131 and lower than the concentration of group III heavy atoms in the second back transparent conductive film 132 concentration, so that the work function of the third back transparent conductive film 133 is higher.
  • the mobility of the third back transparent conductive film 133 is greater than the mobility of the first back transparent conductive film 131 and greater than the mobility of the second back transparent conductive film 132, because the mobility of the third back transparent conductive film 133 is higher, Therefore, even if the concentration of dopant ions in the third back transparent conductive film 133 is small, the conductivity of the third back transparent conductive film 133 will not be too small, that is to say, the third back transparent conductive film 133 can still maintain a good conductivity, the contact resistance between the third back transparent conductive film 133 and the first doped semiconductor layer 120b is relatively low.
  • the material of the third back transparent conductive film 133 includes tungsten-doped indium oxide. The mobility of tungsten-doped indium oxide is greater than that of indium tin oxide, and the work function of tungsten-doped indium oxide is higher than that of indium tin oxide.
  • the mobility of the third rear transparent conductive film 133 is 70 ⁇ S/cm 2 -90 ⁇ S/cm 2 , such as 80 ⁇ S/cm 2 .
  • the mass percent concentration of tungsten oxide in tungsten-doped indium oxide is 0.1%-0.3%.
  • the ratio of the thickness of the third back transparent conductive film 133 to the thickness of the first back transparent conductive film 131 is 1:5-1:6.
  • the advantage is that: since the conductivity of the third back transparent conductive film 133 is smaller than that of the first back transparent conductive film 131, it is necessary to make the thickness of the third back transparent conductive film 133 as thin as possible, so as to ensure that the back composite transparent conductive film 130b overall better conductivity.
  • the thickness of the third back transparent conductive film 133 is relatively thin, which is beneficial to maintain the built-in electric field of the PN junction and maintain a high open circuit voltage.
  • the thickness of the third back transparent conductive film 133 is 5 nm-12 nm, such as 10 nm.
  • the conductivity of the first back transparent conductive film 131 is greater than that of the second back transparent conductive film 132.
  • the conductivity of the third back transparent conductive film 133 is lower than that of the first back transparent conductive film 131 and greater than that of the second back transparent conductive film 132 .
  • the doping concentration in the first back transparent conductive film 131 is greater than the doping concentration in the second back transparent conductive film 132, and the material of the first back transparent conductive film 131 and the second back transparent conductive film 132 The materials are the same, so the mobility of the second back transparent conductive film 132 is greater than that of the first back transparent conductive film 131 .
  • the mobility of the second back transparent conductive film 132 is 35 ⁇ S/cm 2 -38 ⁇ S/cm 2
  • the mobility of the first back transparent conductive film 131 is 33 ⁇ S/cm 2 -35 ⁇ S/cm 2 .
  • the back composite transparent conductive film 130 b only includes the first back transparent conductive film 131 and the second back transparent conductive film 132 , but does not include the third back transparent conductive film 133 .
  • the thickness of the back composite transparent conductive film 130b is 70nm-80nm, the square resistance of the back composite transparent conductive film 130b is 30 ⁇ /square-60 ⁇ /square, and the transmittance of the back composite transparent conductive film 130b is greater than 82%.
  • the transmittance of the composite transparent conductive film 130b on the back side for light with a wavelength of 350nm-1100nm is greater than 82%.
  • the heterojunction solar cell further includes: a back gate line 140b located on the side of the back composite transparent conductive film 130b facing away from the semiconductor substrate layer 100 .
  • the back gate line 140b includes a first sub-back gate line 141b and a second sub-back gate line 142b located on the surface of the first sub-back gate line 141b facing away from the semiconductor substrate layer 100;
  • the electrical conductivity of the line 141b is greater than that of the second sub-back gate line 142b; the melting point of the second sub-back gate line 142b is lower than the melting point of the first sub-back gate line 141b.
  • the material of the first sub-back gate line 141b includes copper; the material of the second sub-back gate line 142b includes tin.
  • the material of the first sub-back gate line 141b is copper so that the first sub-back gate line 141b has better electrical conductivity and at the same time lowers the price.
  • the material of the second sub-back grid line 142b is tin, and the melting point of tin is relatively low, so that the bonding force between the second sub-back grid line 142b and the solder strip is improved, ensuring the bonding force between the second sub-back grid line 142b and the solder strip. welding effect.
  • the back gate line 140b maintains the advantages of low cost and good soldering effect at the same time.
  • the relationship between the thickness of the first sub-back gate line 141b and the thickness of the second sub-back gate line 142b is 5:1-9:1.
  • the thickness of the first sub-back gate line 141b is 4 ⁇ m-4.5 ⁇ m
  • the thickness of the second sub-back gate line 142b is 0.5 ⁇ m-1 ⁇ m.
  • the total thickness of the back gate line 140b is 4 ⁇ m-6 ⁇ m, such as 5 ⁇ m.
  • the aspect ratio of the back gate line 140b is 0.8:2-1:2.
  • the width of the back gate line is 9 ⁇ m-11 ⁇ m, and the height of the back gate line is 4 ⁇ m-6 ⁇ m.
  • the first doped semiconductor layer 120b is in a nanocrystalline state, or the first doped semiconductor layer 120b is in a microcrystalline state, and secondly, the concentration of dopant ions in the first doped semiconductor layer 120b is relatively low.
  • the first doped semiconductor layer 120b has a high doping concentration to improve field passivation, that is, the first doped semiconductor layer 120b and the first intrinsic.
  • the electric field strength between the semiconductor layers 110b becomes larger, which better prevents the photogenerated electrons from diffusing to the interface between the first doped semiconductor layer 120b and the first intrinsic semiconductor layer 110b, so that more photogenerated electrons diffuse to the heterojunction
  • the front side of the solar cell reduces the recombination probability of photogenerated carriers.
  • the volume resistance of the first doped semiconductor layer 120b is reduced, the contact resistance between the first doped semiconductor layer 120b and the back composite transparent conductive film 130b is reduced, the series resistance of the heterojunction solar cell is improved, and the performance of the heterojunction solar cell is improved.
  • the grain size in the first doped semiconductor layer 120b is 1 nm-10 nm.
  • the material of the first doped semiconductor layer 120b is nanocrystalline silicon, or the material of the first doped semiconductor layer 120b is microcrystalline silicon.
  • the concentration of dopant ions in the first doped semiconductor layer 120b is 2E19atom/cm 3 -8E19atom/cm 3 .
  • the dopant ions in the first doped semiconductor layer 120b are P-type ions, such as boron ions.
  • the crystallization rate of the first doped semiconductor layer 120b is 20%-80%.
  • the thickness of the first doped semiconductor layer 120b is 7nm-14nm.
  • the conductivity of the first doped semiconductor layer 120b is 2x10 -1 S/cm-8x10 -1 S/cm.
  • the heterojunction solar cell also includes: a front composite transparent conductive film 130a located on the side of the semiconductor substrate layer 100 facing away from the back composite transparent conductive film 130b; the material of the front composite transparent conductive film 130a includes tungsten-doped indium oxide.
  • the front composite transparent conductive film 130a has a single-layer structure, and the material of the front composite transparent conductive film 130a is tungsten-doped indium oxide, and the mobility of tungsten-doped indium oxide is greater than that of indium tin oxide, so
  • the doping concentration in the front composite transparent conductive film 130a can be reduced, less doping concentration reduces the recombination of free carriers, and secondly, less doping
  • the impurity concentration increases the transmittance of the front composite transparent conductive film 130a, specifically increases the transmittance of light of 700nm-1100nm, the heterojunction solar cell absorbs more sunlight, and improves the short-circuit current of the heterojunction solar cell , to improve the photoelectric conversion efficiency of heterojunction solar cells.
  • the thickness of the front composite transparent conductive film 130a is 70nm-80nm
  • the square resistance of the front composite transparent conductive film 130a is 60 ⁇ /square-100 ⁇ /square
  • the transmittance of the front composite transparent conductive film 130a is greater than 85%.
  • the transmittance of the front composite transparent conductive film 130a for light with a wavelength of 350nm-1100nm is greater than 85%.
  • the heterojunction solar cell further includes: a second doped semiconductor layer 120 a located between the front composite transparent conductive film 130 a and the semiconductor substrate layer 100 .
  • the conductivity type of the second doped semiconductor layer 120a is opposite to that of the first doped semiconductor layer 120b. In this embodiment, it is taken as an example that the conductivity type of the second doped semiconductor layer 120 a is N type.
  • the second doped semiconductor layer 120a is in a nanocrystalline state; or, the second doped semiconductor layer 120a is in a microcrystalline state.
  • the second doped semiconductor layer 120a is in a nanocrystalline state, or the second doped semiconductor layer 120a is in a microcrystalline state, and secondly, the concentration of dopant ions in the second doped semiconductor layer 120a is relatively high, so that the second doped semiconductor layer 120a is in a microcrystalline state.
  • the conductivity of the second doped semiconductor layer 120a is improved, and the second doped semiconductor layer 120a has a high doping concentration to improve field passivation, that is, the gap between the second doped semiconductor layer 120a and the second intrinsic semiconductor layer 110a
  • the electric field intensity becomes larger, better hindering the diffusion of photogenerated holes to the interface between the second doped semiconductor layer 120a and the second intrinsic semiconductor layer 110a, so that more photogenerated holes can diffuse to the heterojunction solar cell On the positive side, it reduces the recombination probability of photogenerated carriers.
  • the volume resistance of the second doped semiconductor layer 120a is reduced, the contact resistance between the second doped semiconductor layer 120a and the front composite transparent conductive film 130a is reduced, the series resistance of the heterojunction solar cell is improved, and the performance of the heterojunction solar cell is improved.
  • the grain size in the second doped semiconductor layer 120a is 1 nm-10 nm.
  • the concentration of dopant ions in the second doped semiconductor layer 120a is 2E19atom/cm 3 -8E19atom/cm 3 .
  • the heterojunction solar cell further includes: a positive grid line 140a located on the side of the front composite transparent conductive film 130a facing away from the semiconductor substrate layer 100; the positive grid line 140a includes a first sub-positive grid line 141a and The second sub-positive grid line 142a located on the surface of the first sub-positive grid line 141a facing away from the semiconductor substrate layer 100; the conductivity of the first sub-positive grid line 141a is greater than that of the second sub-positive grid line 142a The electrical conductivity; the melting point of the second sub-positive grid line 142a is lower than the melting point of the first sub-positive grid line 141a.
  • the material of the first sub-positive grid line 141a includes copper; the material of the second sub-positive grid line 142a includes tin.
  • the material of the first sub-positive grid line 141a is copper so that the first sub-positive grid line 141a has better electrical conductivity and at the same time lowers the price.
  • the material of the second sub-positive grid line 142a is tin, and the melting point of tin is relatively low, so that the bonding force between the second sub-positive grid line 142a and the welding strip is improved, and the bonding force between the second sub-positive grid line 142a and the welding strip is guaranteed. welding effect.
  • the positive grid line 140a maintains the advantages of low cost and good welding effect at the same time.
  • the relationship between the thickness of the first sub-positive gate line 141a and the thickness of the second sub-positive gate line 142a is 5:1-9:1.
  • the thickness of the first sub-positive grid line 141a is 2 ⁇ m-2.5 ⁇ m
  • the thickness of the second sub-positive grid line 142a is 0.5 ⁇ m-1 ⁇ m.
  • the total thickness of the positive gate line 140a is 2.5 ⁇ m-3.5 ⁇ m, such as 3 ⁇ m.
  • the width of the front gate line is 4 ⁇ m-6 ⁇ m, and the height of the back gate line is 2.5 ⁇ m-3.5 ⁇ m.
  • the thickness of the first sub-front gate line 141a is smaller than the thickness of the first sub-back gate line 141b. The purpose of this is to increase the transmittance of the front gate line 140a and make the The solar front receives more sunlight.
  • the aspect ratio of the positive gate line 140a is 0.8:2-1:2.
  • the heterojunction solar cell further includes: a first intrinsic semiconductor layer 110b located between the first doped semiconductor layer 120b and the semiconductor substrate layer 100; a first intrinsic semiconductor layer 110b located between the second doped semiconductor layer 120a and the The second intrinsic semiconductor layer 110 a between the above semiconductor substrate layers 100 .
  • another embodiment of the present application also provides a method for preparing a heterojunction solar cell, referring to FIG. 2 , including the following steps:
  • S2 Forming a back composite transparent conductive film 130b on one side of the semiconductor substrate layer 100.
  • the method for forming the composite transparent conductive film 130b on the back side includes:
  • S22 Form a second back transparent conductive film 132 on the surface of the first back transparent conductive film 131 facing away from the semiconductor substrate layer 100; the first back transparent conductive film 131 and the second back transparent conductive film 131
  • the films 132 are all doped with group III heavy atoms, and the concentration of group III heavy atoms in the second back transparent conductive film 132 is lower than the concentration of group III heavy atoms in the first back transparent conductive film 131 .
  • the method for forming the back composite transparent conductive film 130b further includes: before forming the first back transparent conductive film 131, forming a third back transparent conductive film 133 on one side of the semiconductor substrate layer 100; forming the first back transparent conductive film 133; After a back transparent conductive film 131 , the third back transparent conductive film 133 is located between the first back transparent conductive film 131 and the semiconductor substrate layer 100 .
  • the back composite transparent conductive film 130b includes the first back transparent conductive film 131, the second back transparent conductive film 132 and the third back transparent conductive film 133 as an example. In other embodiments, The back composite transparent conductive film 130b may not include the third back transparent conductive film 133 .
  • a semiconductor substrate layer 100 is provided.
  • a first intrinsic semiconductor layer 110 b is formed on one side of the semiconductor substrate layer 100
  • a second intrinsic semiconductor layer 110 a is formed on the other side of the semiconductor substrate layer 100 .
  • a first doped semiconductor layer 120b is formed on the side of the first intrinsic semiconductor layer 110b facing away from the semiconductor substrate layer 100;
  • a second doped semiconductor layer 120a is formed on one side of the bottom layer 100 .
  • the process of forming the first doped semiconductor layer 120b includes a plasma chemical vapor deposition process
  • the parameters of the plasma chemical vapor deposition process include: the gas used includes H 2 , SiH 4 and B 2
  • the flow ratio of H 6 , H 2 and SiH 4 is 200:1.8-200:2.3
  • the flow ratio of B 2 H 6 and SiH 4 is 1:1-1:5
  • the chamber pressure is 0.3Pa-0.5Pa
  • the power density is 0.25mW/cm 2 -0.4mW/cm 2 .
  • the concentration of dopant ions in the first doped semiconductor layer 120b is 2E19atom/cm 3 -8E19atom/cm 3 .
  • the first doped semiconductor layer 120b is in a nanocrystalline state; or, the first doped semiconductor layer 120b is in a microcrystalline state. Secondly, the concentration of dopant ions in the first doped semiconductor layer 120b higher.
  • the material of the first doped semiconductor layer 120b is nanocrystalline silicon, or the material of the first doped semiconductor layer 120b is microcrystalline silicon.
  • the second doped semiconductor layer 120a is in a nanocrystalline state; or, the second doped semiconductor layer 120a is in a microcrystalline state, and secondly, the concentration of doping ions in the second doped semiconductor layer 120a is relatively high .
  • the material of the second doped semiconductor layer 120a is nanocrystalline silicon, or the material of the second doped semiconductor layer 120a is microcrystalline silicon.
  • the formation process of the second doped semiconductor layer 120a includes a plasma chemical vapor deposition process.
  • a back compound transparent conductive film 130b is formed on the side of the first doped semiconductor layer 120b facing away from the semiconductor substrate layer 100; on the second doped semiconductor layer 120a facing away from the semiconductor substrate layer One side of the 100 forms a composite transparent conductive film 130a on the front side.
  • the method for forming the back composite transparent conductive film 130b includes: forming a third back transparent conductive film 133 on the side of the first doped semiconductor layer 120b facing away from the semiconductor substrate layer 100; A first back transparent conductive film 131 is formed on the side surface of the conductive film 133 facing away from the semiconductor substrate layer 100; a second back surface is formed on the side surface of the first back transparent conductive film 131 facing away from the semiconductor substrate layer 100 Transparent conductive film 132; both the first back transparent conductive film 131 and the second back transparent conductive film 132 are doped with group III heavy atoms, and the group III heavy atoms in the second back transparent conductive film 132 The concentration is lower than the concentration of group III heavy atoms in the first back transparent conductive film 131 .
  • the mobility of the third back transparent conductive film 133 is greater than the mobility of the first back transparent conductive film 131 and greater than the mobility of the second back transparent conductive film 132; the mobility of the third back transparent conductive film 133
  • the work function is higher than the work function of the first back transparent conductive film 131 and higher than the work function of the second back transparent conductive film 132 .
  • the process of forming the first back transparent conductive film 131 includes a deposition process, such as a plasma chemical vapor deposition process; the process of forming the second back transparent conductive film 132 includes a deposition process, such as a plasma chemical vapor deposition process; The process of the three-back transparent conductive film 133 includes a deposition process, such as a plasma chemical vapor deposition process.
  • the process of forming the front composite transparent conductive film 130a includes a deposition process, such as a plasma chemical vapor deposition process.
  • the material of the front composite transparent conductive film 130a includes tungsten-doped indium oxide.
  • a back gate line 140b is formed on the side of the back composite transparent conductive film 130b facing away from the semiconductor substrate layer 100; on the side of the front composite transparent conductive film 130a facing away from the semiconductor substrate layer 100 A positive gate line 140a is formed.
  • the step of forming the back gate line 140b includes: forming a patterned first photoresist layer on the surface of the back composite transparent conductive film 130b, the first photoresist layer has a first gate line opening; An evaporation process forms the back gate line 140b in the first gate line opening; after the evaporation process is used to form the back gate line 140b in the first gate line opening, the first photoresist layer is removed.
  • the step of forming the first photoresist layer includes: coating a first photoresist film; after coating the first photoresist film, curing the first photoresist film; after curing the first photoresist film, exposing the first photoresist film; after exposing the first photoresist film, developing the first photoresist film to form a first photoresist layer.
  • the process of removing the first photoresist layer includes a release process.
  • the step of forming the back gate line 140b in the first gate line opening by using an evaporation process includes: forming a first sub-back gate line 141b in the first gate line opening by an evaporation process; forming the first sub-back gate line 141b; After the back gate line 141b, a second sub-back gate line 142b located on the surface of the first sub-back gate line 141b is formed in the opening of the first gate line by an evaporation process; the conductivity of the first sub-back gate line 141b is greater than the specified The electrical conductivity of the second sub-back gate line 142b; the melting point of the second sub-back gate line 142b is lower than the melting point of the first sub-back gate line 141b.
  • the step of forming the positive gate line 140a includes: forming a patterned second photoresist layer on the surface of the front composite transparent conductive film 130a, the second photoresist layer has a second gate line opening; The positive gate line 140a is formed in the second gate line opening by an evaporation process; after the positive gate line 140a is formed in the second gate line opening by the evaporation process, the second photoresist layer is removed.
  • the step of forming the second photoresist layer includes: coating a second photoresist film; after coating the second photoresist film, curing the second photoresist film; after curing the second photoresist film, exposing the second photoresist film; after exposing the second photoresist film, developing the second photoresist film to form a second photoresist layer.
  • the process of removing the second photoresist layer includes a demolding process.
  • the step of forming the positive gate line 140a in the second gate line opening by using an evaporation process includes: forming a first sub-positive gate line 141a in the second gate line opening by using an evaporation process; forming the first sub-gate line 141a; After the positive grid line 141a, a second sub-positive grid line 142a located on the surface of the first sub-positive grid line 141a is formed in the opening of the second grid line by an evaporation process; the conductivity of the first sub-positive grid line 141a is greater than the specified The electrical conductivity of the second sub-positive grid line 142a; the melting point of the second sub-positive grid line 142a is lower than the melting point of the first sub-positive grid line 141a.
  • the bonding force between the positive grid lines 140a and the front composite transparent conductive film 130a is better, further reducing the bonding force between the positive grid lines 140a and the front composite transparent conductive film 130a. 130a contact resistance.
  • the vapor deposition process is used in the process of forming the back gate line 140b, so that the bonding force between the back gate line 140b and the back composite transparent conductive film 130b is better, and further reduces the number of back gate lines 140b and the back composite transparent conductive film 130b. contact resistance.
  • the preparation method of the heterojunction solar cell further includes: curing the front grid line 140a and the back grid line 140b; after curing the front grid line 140a and the back grid line 140b, performing photo Injection annealing.
  • the light injection annealing treatment refers to: while the annealing treatment is being performed, the front grid line 140a and the back grid line 140b are irradiated with infrared light, so that the heat shock to the front grid line 140a and the back grid line 140b is strengthened.

Abstract

本申请提供一种异质结太阳能电池及其制备方法，该异质结太阳能电池包括：半导体衬底层；位于所述半导体衬底层一侧的背面复合透明导电膜；所述背面复合透明导电膜包括：第一背面透明导电膜；位于所述第一背面透明导电膜背向所述半导体衬底层一侧表面的第二背面透明导电膜；所述第一背面透明导电膜和所述第二背面透明导电膜中均掺杂有Ⅲ族重原子，所述第二背面透明导电膜中Ⅲ族重原子的浓度小于所述第一背面透明导电膜中Ⅲ族重原子的浓度。通过该技术方案，所述异质结太阳能电池的光电转换效率和封装性能均得到提高。

Description

一种异质结太阳能电池及其制备方法
相关申请的交叉引用
本申请要求在2021年6月30日提交中国专利局、申请号为202110735832.8、发明名称为“一种异质结太阳能电池及其制备方法”的中国专利申请的优先权，其全部内容通过引用的方式并入本文中。
技术领域
本申请涉及光伏电池技术领域，具体涉及一种异质结太阳能电池及其制备方法。
背景技术
太阳能电池是一种清洁能源电池，太阳能电池广泛的应用在生活和生产中。在太阳能电池，尤其是异质结太阳能电池的电极和非晶硅层之间加一层透明导电膜(TCO)可以有效地增加载流子的收集，提高太阳能电池的转换效率。
透明导电膜包括正面透明导电膜和背面透明导电膜。目前，透明导电膜的设置导致异质结太阳能电池存在光电转换效率和封装性能较差的问题。对于异质结太阳能电池，背面透明导电膜的综合性能的优化一直是本领域技术人员研究的热点。
发明内容
因此，本申请要解决的技术问题在于克服现有技术中异质结太阳能电池的光电转换效率和封装性能较差的问题，从而提供一种异质结太阳能电池。
本申请提供一种异质结太阳能电池，包括：半导体衬底层；位于所述半导体衬底层一侧的背面复合透明导电膜；所述背面复合透明导电膜包括：第一背面透明导电膜；位于所述第一背面透明导电膜背向所述半导体衬底层一侧表面的第二背面透明导电膜；所述第一背面透明导电膜和所述第二背面透明导电膜中均掺杂有Ⅲ族重原子，所述第二背面透明导电膜中Ⅲ族重原子的浓度小于所述第一背面透明导电膜中Ⅲ族重原子的浓度。
可选的，所述Ⅲ族重原子包括镓原子；所述第一背面透明导电膜的材料包括掺镓的氧化锌；所述第二背面透明导电膜的材料包括掺镓的氧化锌。
可选的，所述第二背面透明导电膜中镓的质量百分比浓度与所述第一背面透明导电膜中镓的质量百分比浓度的比值为1:2-1:4。
可选的，所述第一背面透明导电膜中镓的质量百分比浓度为1.5％-2％；所述第二背 面透明导电膜中镓的质量百分比浓度为0.5％-1％。
可选的，所述第二背面透明导电膜的厚度与所述第一背面透明导电膜的厚度的比值为1:4-1:3。
可选的，所述第二背面透明导电膜的厚度为10nm-20nm；所述第一背面透明导电膜的厚度为50nm-60nm。
可选的，所述异质结太阳能电池还包括：位于所述第二背面透明导电膜背向所述第一背面透明导电膜一侧表面的有机封装层。
可选的，所述背面复合透明导电膜还包括：第三背面透明导电膜，所述第三背面透明导电膜的功函数高于第一背面透明导电膜的功函数且高于第二背面透明导电膜的功函数。
可选的，所述第三背面透明导电膜的迁移率大于所述第一背面透明导电膜的迁移率且大于所述第二背面透明导电膜的迁移率；所述第三背面透明导电膜中掺杂离子的浓度小于所述第一背面透明导电膜中Ⅲ族重原子的浓度且小于第二背面透明导电膜中Ⅲ族重原子的浓度。
可选的，所述第三背面透明导电膜的材料包括掺钨氧化铟。
可选的，所述掺钨氧化铟中钨的质量百分比浓度为0.1％-0.3％。
可选的，所述第三背面透明导电膜的厚度与第一背面透明导电膜的厚度的比值为1:5-1:6。
可选的，还包括：位于所述背面复合透明导电膜背向所述半导体衬底层一侧的背栅线；所述背栅线包括第一子背栅线和位于第一子背栅线背向所述半导体衬底层一侧表面的第二子背栅线；所述第一子背栅线的电导率大于所述第二子背栅线的电导率；所述第二子背栅线的熔点小于所述第一子背栅线的熔点。
可选的，所述第一子背栅线的材料包括铜；所述第二子背栅线的材料包括锡。
可选的，所述第一子背栅线的厚度与所述第二子背栅线的厚度的关系是5:1-9:1。
可选的，所述背栅线的高宽比为0.8:2-1:2；所述背栅线的宽度为9μm-11μm，所述背栅线的高度为4μm-6μm。
可选的，还包括：位于所述半导体衬底层和所述背面复合透明导电膜之间的第一掺杂半导体层；所述第一掺杂半导体层为纳米晶态；或，所述第一掺杂半导体层为微晶态。
可选的，所述第一掺杂半导体层中掺杂离子的浓度为2E19atom/cm 3-8E19atom/cm 3。
可选的，还包括：位于所述半导体衬底层背向所述背面复合透明导电膜一侧的正面复合透明导电膜；所述正面复合透明导电膜的材料包括掺钨氧化铟。
可选的，还包括：位于所述半导体衬底层和所述正面复合透明导电膜之间的第二掺 杂半导体层；所述第二掺杂半导体层为纳米晶态；或，所述第二掺杂半导体层为微晶态。
可选的，所述异质结太阳能电池还包括：位于所述正面复合透明导电膜背向所述半导体衬底层一侧的正栅线；所述正栅线包括第一子正栅线和位于第一子正栅线背向所述半导体衬底层一侧表面的第二子正栅线；所述第一子正栅线的电导率大于所述第二子正栅线的电导率；所述第二子正栅线的熔点小于所述第一子正栅线的熔点。
可选的，所述第一子正栅线的材料包括铜；所述第二子正栅线的材料包括锡。
可选的，所述第一子正栅线的厚度与所述第二子正栅线的厚度的关系是5:1-9:1。
可选的，所述正栅线的高宽比为0.8:2-1:2；所述正栅线的宽度为4μm-6μm，所述正栅线的高度为2.5μm-3.5μm。
本申请还提供一种异质结太阳能电池的制备方法，包括：提供半导体衬底层；在所述半导体衬底层的一侧形成背面复合透明导电膜；形成所述背面复合透明导电膜的方法包括：在所述半导体衬底层的一侧形成第一背面透明导电膜；在所述第一背面透明导电膜背向所述半导体衬底层的一侧表面形成第二背面透明导电膜；所述第一背面透明导电膜和所述第二背面透明导电膜中均掺杂有Ⅲ族重原子，所述第二背面透明导电膜中Ⅲ族重原子的浓度小于所述第一背面透明导电膜中Ⅲ族重原子的浓度。
可选的，形成所述背面复合透明导电膜的方法还包括：在形成所述第一背面透明导电膜之前，在所述半导体衬底层的一侧形成第三背面透明导电膜；形成所述第一背面透明导电膜之后，所述第三背面透明导电膜位于所述第一背面透明导电膜和所述半导体衬底层之间；所述第三背面透明导电膜的功函数高于第一背面透明导电膜的功函数且高于第二背面透明导电膜的功函数。
可选的，所述第三背面透明导电膜的迁移率大于所述第一背面透明导电膜的迁移率且大于所述第二背面透明导电膜的迁移率；所述第三背面透明导电膜中掺杂离子的浓度小于所述第一背面透明导电膜中Ⅲ族重原子的浓度且小于第二背面透明导电膜中Ⅲ族重原子的浓度。
可选的，还包括：在所述背面复合透明导电膜背向所述半导体衬底层的一侧形成背栅线；形成所述背栅线的步骤包括：在所述背面复合透明导电膜的表面形成图形化的第一光刻胶层，所述第一光刻胶层中具有第一栅线开口；采用蒸镀工艺在所述第一栅线开口中形成背栅线；采用蒸镀工艺在所述第一栅线开口中形成背栅线之后，去除所述第一光刻胶层。
可选的，采用蒸镀工艺在所述第一栅线开口中形成背栅线的步骤包括：采用蒸镀工艺在所述第一栅线开口中形成第一子背栅线；采用蒸镀工艺在第一栅线开口中形成位于第一子背栅线表面的第二子背栅线；所述第一子背栅线的电导率大于所述第二子背栅线的电导率；所述第二子背栅线的熔点小于所述第一子背栅线的熔点。
可选的，所述异质结太阳能电池的制备方法还包括：在所述半导体衬底层的另一侧形成正面复合透明导电膜；所述正面复合透明导电膜的材料包括掺钨氧化铟。
可选的，所述异质结太阳能电池的制备方法还包括：在所述正面复合透明导电膜背向所述半导体衬底层的一侧形成正栅线；形成所述正栅线的步骤包括：在所述正面复合透明导电膜的表面形成图形化的第二光刻胶层，所述第二光刻胶层中具有第二栅线开口；采用蒸镀工艺在所述第二栅线开口中形成正栅线；采用蒸镀工艺在所述第二栅线开口中形成正栅线之后，去除所述第二光刻胶层。
可选的，采用蒸镀工艺在所述第二栅线开口中形成正栅线的步骤包括：采用蒸镀工艺在所述第二栅线开口中形成第一子正栅线；采用蒸镀工艺在第二栅线开口中形成位于第一子正栅线表面的第二子正栅线；所述第一子正栅线的电导率大于所述第二子正栅线的电导率；所述第二子正栅线的熔点小于所述第一子正栅线的熔点。
可选的，还包括：在所述半导体衬底层的一侧形成第一掺杂半导体层；所述第一掺杂半导体层为纳米晶态；或，所述第一掺杂半导体层为微晶态；形成所述背面复合透明导电膜之后，所述第一掺杂半导体层位于所述半导体衬底层和所述背面复合透明导电膜之间。
可选的，形成所述第一掺杂半导体层的工艺包括等离子体化学气相沉积工艺，等离子体化学气相沉积工艺的参数包括：采用的气体包括H 2、SiH 4和B 2H 6，H 2和SiH 4的流量比例为200:1.8-200:2.3，B 2H 6和SiH 4的流量比为1:1-1:5，腔室压强为0.3Pa-0.5Pa，射频功率密度为0.25mW/cm 2-0.4mW/cm 2。
本申请的技术方案具有以下有益效果：
1.本申请提供的异质结太阳能电池，包括背面复合透明导电膜；所述背面复合透明导电膜包括：第一背面透明导电膜；位于所述第一背面透明导电膜背向所述半导体衬底层一侧表面的第二背面透明导电膜，所述第一背面透明导电膜和所述第二背面透明导电膜中均掺杂有Ⅲ族重原子。由于Ⅲ族重原子的原子量较大，因此使得掺杂有Ⅲ族重原子的第一背面透明导电膜的密度变大，掺杂有Ⅲ族重原子的第二背面透明导电膜密度变大，第一背面透明导电膜和第二背面透明导电膜的硬度均变大，第二背面透明导电膜与有机封装层之间的界面处的镓原子被有机封装层的更多的C-H键包覆，也就是界面处的镓原子能与更多的C-H键结合，进而使得第二背面透明导电膜与有机封装层之间的结合力较大。其次，所述第二背面透明导电膜中Ⅲ族重原子的浓度小于所述第一背面透明导电膜中Ⅲ族重原子的浓度，第二背面透明导电膜中Ⅲ族重原子的浓度较小，这样使得第二背面透明导电膜的表面缺陷态密度降低，增强第二背面透明导电膜与有机封装层之间的结合力。再次，第一背面透明导电膜和第二背面透明导电膜的硬度均变大，也使得第一背面透明导电膜和第二背面透明导电膜之间的结合力较大。综上，增强背面复合透明导电膜与有机封装层之间的结合力，提高异质结太阳能电池的封装性能。
由于第一背面透明导电膜中Ⅲ族重原子的浓度较大，这样使得第一背面透明导电膜中的自由载流子浓度较多，第一背面透明导电膜的导电能力优于第二背面透明导电膜的导电能力，使得背面复合透明导电膜的导电能力较好，背面复合透明导电膜收集载流子的能力较好，利于提高异质结太阳能电池的光电转换效率。
2.进一步，所述Ⅲ族重原子包括镓原子；所述第一背面透明导电膜的材料包括掺镓的氧化锌；所述第二背面透明导电膜的材料包括掺镓的氧化锌。掺镓的氧化锌不仅具有价格较低的优势，降低异质结太阳能电池的成本，且掺镓的氧化锌具有迁移率较大的优势，能提高第一背面透明导电膜和第二背面透明导电膜的导电能力。
3.进一步，所述背面复合透明导电膜还包括第三背面透明导电膜，所述第三背面透明导电膜的功函数高于第一背面透明导电膜的功函数且高于第二背面透明导电膜的功函数。由于第三背面透明导电膜的功函数较高，因此降低第三背面透明导电膜与第一掺杂半导体层之间的带隙失配，也就是降低背面复合透明导电膜和与第一掺杂半导体层之间的带隙失配，使得背面复合透明导电膜对第一掺杂半导体层的价带弯曲量较小，利于空穴从第一掺杂半导体层隧穿至背面复合透明导电膜。
进一步，第三背面透明导电膜的费米能级会随着第三背面透明导电膜中掺杂离子的浓度的降低而上移，相应的，第三背面透明导电膜的功函数会随之降低。本申请中采用第三背面透明导电膜中掺杂离子的浓度小于所述第一背面透明导电膜中Ⅲ族重原子的浓度且小于第二背面透明导电膜中Ⅲ族重原子的浓度，这样使得第三背面透明导电膜的功函数较高。第三背面透明导电膜的迁移率大于第一背面透明导电膜的迁移率且大于第二背面透明导电膜的迁移率，由于第三背面透明导电膜的迁移率更加高，因此即使第三背面透明导电膜中掺杂离子的浓度较小，也不会使得第三背面透明导电膜的导电率过小，也就是说第三背面透明导电膜依然能维持较好的导电性，第三背面透明导电膜与第一掺杂半导体层的接触电阻较低。
4.进一步，第一掺杂半导体层为纳米晶态，或第一掺杂半导体层为微晶态，其次，第一掺杂半导体层中掺杂离子的浓度较高，这样使得第一掺杂半导体层的电导率提高，第一掺杂半导体层具有高的掺杂浓度提高场钝化，也就是说，第一掺杂半导体层与第一本征半导体层之间的电场强度变大，更好的阻碍光生电子扩散至第一掺杂半导体层与第一本征半导体层之间的界面，使得光生电子更多的扩散至异质结太阳能电池的正面，降低光生载流子的复合几率。同时，第一掺杂半导体层的体电阻降低，降低第一掺杂半导体层和背面复合透明导电膜的接触电阻，改善异质结太阳能电池的串联电阻，提高异质结太阳能电池的光电转换效率。
附图说明
为了更清楚地说明本申请具体实施方式或现有技术中的技术方案，下面将对具体实施方式或现有技术描述中所需要使用的附图作简单地介绍，显而易见地，下面描述中的附图是本申请的一些实施方式，对于本领域普通技术人员来讲，在不付出创造性劳动的前提下，还可以根据这些附图获得其他的附图。
图1为本申请一实施例提供的异质结太阳能电池的结构示意图。
图2为本申请一实施例提供的异质结太阳能电池形成过程的流程图。
图3至图7为本申请另一实施例提供的异质结太阳能电池制备过程的结构示意图。
附图标记：
100、半导体衬底层；110b、第一本征半导体层；110a、第二本征半导体层；130b、背面复合透明导电膜；120b、第一掺杂半导体层；120a、第二掺杂半导体层；131、第一背面透明导电膜；132、第二背面透明导电膜；133、第三背面透明导电膜；130a、正面复合透明导电膜；140b、背栅线；141b、第一子背栅线；142b、第二子背栅线；140a、正栅线；141a、第一子正栅线；142a、第二子正栅线。
具体实施方式
下面将结合附图对本申请的技术方案进行清楚、完整地描述，显然，所描述的实施例是本申请一部分实施例，而不是全部的实施例。基于本申请中的实施例，本领域普通技术人员在没有做出创造性劳动前提下所获得的所有其他实施例，都属于本申请保护的范围。
在本申请的描述中，需要说明的是，术语“中心”、“上”、“下”、“左”、“右”、“竖直”、“水平”、“内”、“外”等指示的方位或位置关系为基于附图所示的方位或位置关系，仅是为了便于描述本申请和简化描述，而不是指示或暗示所指的装置或元件必须具有特定的方位、以特定的方位构造和操作，因此不能理解为对本申请的限制。此外，术语“第一”、“第二”、“第三”仅用于描述目的，而不能理解为指示或暗示相对重要性。
在本申请的描述中，需要说明的是，除非另有明确的规定和限定，术语“安装”、“相连”、“连接”应做广义理解，例如，可以是固定连接，也可以是可拆卸连接，或一体地连接；可以是机械连接，也可以是电连接；可以是直接相连，也可以通过中间媒介间接相连，还可以是两个元件内部的连通，可以是无线连接，也可以是有线连接。对于本领域的普通技术人员而言，可以具体情况理解上述术语在本申请中的具体含义。
此外，下面所描述的本申请不同实施方式中所涉及的技术特征只要彼此之间未构成冲突就可以相互结合。
本申请一实施例提供一种异质结太阳能电池，请参考图1，该异质结太阳能电池包括：
半导体衬底层100；
位于所述半导体衬底层100一侧的背面复合透明导电膜130b；
所述背面复合透明导电膜130b包括：第一背面透明导电膜131；位于所述第一背面透明导电膜131背向所述半导体衬底层100一侧表面的第二背面透明导电膜132；所述第一背面透明导电膜131和所述第二背面透明导电膜132中均掺杂有Ⅲ族重原子，所述第二背面透明导电膜132中Ⅲ族重原子的浓度小于所述第一背面透明导电膜131中Ⅲ族重原子的浓度。
本实施例中，所述半导体衬底层100的导电类型为N型。需要说明的是，在其他实施例中，所述半导体衬底层的导电类型还可以为P型。
所述半导体衬底层100的材料包括单晶硅。
由于所述第一背面透明导电膜131和所述第二背面透明导电膜132中均掺杂有Ⅲ族 重原子。由于Ⅲ族重原子的原子量较大，因此使得掺杂有Ⅲ族重原子的第一背面透明导电膜131的密度变大，掺杂有Ⅲ族重原子的第二背面透明导电膜132密度变大，第一背面透明导电膜131和第二背面透明导电膜132的硬度均变大，第二背面透明导电膜132与有机封装层之间的界面处的镓原子(Ga)被有机封装层的更多的C-H键包覆，也就是界面处的镓原子能与更多的C-H键结合，进而使得第二背面透明导电膜132与有机封装层之间的结合力较大。其次，所述第二背面透明导电膜132中Ⅲ族重原子的浓度小于所述第一背面透明导电膜131中Ⅲ族重原子的浓度，第二背面透明导电膜132中Ⅲ族重原子的浓度较小，这样使得第二背面透明导电膜132的表面缺陷态密度降低，增强第二背面透明导电膜132与有机封装层之间的结合力。再次，第一背面透明导电膜131和第二背面透明导电膜132的硬度均变大，也使得第一背面透明导电膜131和第二背面透明导电膜132之间的结合力较大。综上，增强背面复合透明导电膜130b与有机封装层之间的结合力，提高异质结太阳能电池的封装性能。
其次，由于第一背面透明导电膜131中Ⅲ族重原子的浓度较大，这样使得第一背面透明导电膜的131中自由载流子浓度较多，第一背面透明导电膜131的导电能力优于第二背面透明导电膜132的导电能力，使得背面复合透明导电膜130b的导电能力较好，背面复合透明导电膜130b收集载流子的能力较好，利于提高异质结太阳能电池的光电转换效率。
本实施例中，所述Ⅲ族重原子包括镓原子。本实施例中，Ⅲ族重原子不包括铝原子。所述Ⅲ族重原子的原子量大于等于镓原子的原子量。
在一个实施例中，第一背面透明导电膜131的材料包括掺镓的氧化锌；所述第二背面透明导电膜132的材料包括掺镓的氧化锌。
当第一背面透明导电膜131和第二背面透明导电膜132选择氧化锌系的材料时，氧化锌系的材料的价格非常便宜，能显著的降低异质结太阳能电池的成本。
需要说明的是，尽管掺铝(Al)的氧化锌的价格较低，但是掺铝的氧化锌的迁移率较低，会降低太阳能电池的光电转换效率，且掺铝的氧化锌中铝的原子量较小，掺铝的氧化锌的硬度较小，会导致铝的氧化锌与有机封装层之间的结合力较小，不能满足太阳能电池的封装性能要求。
本实施例中，掺镓的氧化锌与有机封装层之间的结合力较大。其次，掺镓的氧化锌的迁移率大于掺铝的氧化锌的迁移率。掺镓的氧化锌不仅具有价格较低的优势，降低异质结太阳能电池的成本，且具有迁移率较大的优势。
在一个实施例中，所述第二背面透明导电膜132中镓的质量百分比浓度与所述第一背面透明导电膜131中镓的质量百分比浓度的比值为1:2-1:4。好处在于：第一背面透明导电膜131为重掺杂，第一背面透明导电膜131的导电率高；第二背面透明导电膜132为中度掺杂，用于和有机封装层之间形成良好的结合。在上述比值范围内，使得背面复合透明导电膜130b的整个导电性较好且与有机封装层之间形成良好的结合。
在一个具体的实施例中，所述第一背面透明导电膜131中镓的质量百分比浓度为1.5％-2％；所述第二背面透明导电膜132中镓的质量百分比浓度为0.5％-1％。
在一个实施例中，所述第二背面透明导电膜132的厚度与所述第一背面透明导电膜131的厚度的比值为1:4-1:3。这样的比值范围的好处在于：第一背面透明导电膜131的厚度比较厚，使得第一背面透明导电膜131的电阻降低，第一背面透明导电膜131作为背面复合透明导电膜130b的主要导电层；第二背面透明导电膜132的厚度较低，使得中度掺杂的第二背面透明导电膜132的厚度占比相对于重掺杂的第一背面透明导电膜131厚度占比较小，这样使得背面复合透明导电膜130b的导电能力提高。
在一个具体的实施例中，所述第二背面透明导电膜132的厚度为10nm-20nm；所述第一背面透明导电膜131的厚度为50nm-60nm。所述异质结太阳能电池还包括：位于所述第二背面透明导电膜132背向所述第一背面透明导电膜131一侧表面的有机封装层(未图示)。所述有机封装层的材料包括：聚乙烯-烯烃共聚物(POE)、可发性聚乙烯(EPE)或热塑性聚烯烃弹性体(TPO)。
所述异质结太阳能电池还包括：位于所述半导体衬底层100和所述背面复合透明导电膜130b之间的第一掺杂半导体层120b。
所述背面复合透明导电膜130b还包括：第三背面透明导电膜133，所述第三背面透明导电膜133的功函数高于第一背面透明导电膜131的功函数且高于第二背面透明导电膜132的功函数。由于第三背面透明导电膜133的功函数较高，因此降低第三背面透明导电膜133与第一掺杂半导体层120b之间的带隙失配，也就是降低背面复合透明导电膜130b和与第一掺杂半导体层120b之间的带隙失配，使得背面复合透明导电膜130b对第一掺杂半导体层120b的价带弯曲量较小，利于空穴从第一掺杂半导体层120b隧穿至背面复合透明导电膜130b。
进一步，所述第三背面透明导电膜133的迁移率大于所述第一背面透明导电膜131的迁移率且大于所述第二背面透明导电膜132的迁移率；所述第三背面透明导电膜133中掺杂离子的浓度小于所述第一背面透明导电膜131中Ⅲ族重原子的浓度且小于第二背面透明导电膜132中Ⅲ族重原子的浓度。
第三背面透明导电膜133的费米能级会随着第三背面透明导电膜133中掺杂离子的浓度的降低而上移，相应的，第三背面透明导电膜133的功函数会随之降低。本申请实施例中采用第三背面透明导电膜133中掺杂离子的浓度小于所述第一背面透明导电膜131中Ⅲ族重原子的浓度且小于第二背面透明导电膜132中Ⅲ族重原子的浓度，这样使得第三背面透明导电膜133的功函数较高。其次，第三背面透明导电膜133的迁移率大于第一背面透明导电膜131的迁移率且大于第二背面透明导电膜132的迁移率，由于第三背面透明导电膜133的迁移率更加高，因此即使第三背面透明导电膜133中掺杂离子的浓度较小，也不会使得第三背面透明导电膜133的导电率过小，也就是说第三背面透明导电膜133依然能维持较好的导电性，第三背面透明导电膜133与第一掺杂半导体层120b的接触电阻较低。在一个实施例中，所述第三背面透明导电膜133的材料包括掺钨氧化铟。掺钨氧化铟的迁移率大于氧化铟锡的迁移率，掺钨氧化铟的功函数高于氧化铟锡的功函数。
在一个实施例中，所述第三背面透明导电膜133的迁移率为70μS/cm 2-90μS/cm 2，如 80μS/cm 2。
在一个具体的实施例中，所述第三背面透明导电膜133的材料为掺钨氧化铟时，掺钨氧化铟中氧化钨的质量百分比浓度为0.1％-0.3％。
在一个实施例中，所述第三背面透明导电膜133的厚度与第一背面透明导电膜131的厚度的比值为1:5-1:6。好处在于：由于第三背面透明导电膜133的导电率小于第一背面透明导电膜131的导电率，因此需要使得第三背面透明导电膜133的厚度尽可能的薄，这样保证背面复合透明导电膜130b的整体较好的导电性。其次，第三背面透明导电膜133的厚度较薄，有利于维持PN结的内建电场，维持高的开路电压。
在一个具体的实施例中，所述第三背面透明导电膜133的厚度为5nmm-12nm，如10nmm。
需要说明的是，本实施例中，由于第一背面透明导电膜131中的掺杂浓度大于第二背面透明导电膜132中的掺杂浓度，因此第一背面透明导电膜131的导电率大于第二背面透明导电膜132的导电率。第三背面透明导电膜133的导电率小于第一背面透明导电膜131的导电率且大于第二背面透明导电膜132的导电率。
需要说明的是，由于第一背面透明导电膜131中的掺杂浓度大于第二背面透明导电膜132中的掺杂浓度，且第一背面透明导电膜131的材料和第二背面透明导电膜132的材料相同，因此第二背面透明导电膜132的迁移率大于第一背面透明导电膜131的迁移率。在一个具体的实施例中，第二背面透明导电膜132的迁移率为35μS/cm 2-38μS/cm 2，第一背面透明导电膜131的迁移率为33μS/cm 2-35μS/cm 2。
需要说明的是，掺钨氧化铟的功函数比氧化铟锡(ITO)的功函数高。
需要说明的是，在其他实施例中，所述背面复合透明导电膜130b仅包括第一背面透明导电膜131和第二背面透明导电膜132，而不包括第三背面透明导电膜133。
所述背面复合透明导电膜130b的厚度为70nm-80nm，背面复合透明导电膜130b的方阻为30Ω/square-60Ω/square，所述背面复合透明导电膜130b的透过率大于82％，所述背面复合透明导电膜130b针对波长为350nm-1100nm的光的透过率大于82％。
所述异质结太阳能电池还包括：位于所述背面复合透明导电膜130b背向所述半导体衬底层100一侧的背栅线140b。
所述背栅线140b包括第一子背栅线141b和位于第一子背栅线141b背向所述半导体衬底层100一侧表面的第二子背栅线142b；所述第一子背栅线141b的电导率大于所述第二子背栅线142b的电导率；所述第二子背栅线142b的熔点小于所述第一子背栅线141b的熔点。
在一个具体的实施例中，所述第一子背栅线141b的材料包括铜；所述第二子背栅线142b的材料包括锡。所述第一子背栅线141b的材料为铜使得第一子背栅线141b具有较好的导电率的同时价格降低。第二子背栅线142b的材料为锡，锡的熔点较低，使得第二子背栅线142b与焊带之间的结合力提高，保证第二子背栅线142b与焊带之间的焊接效果。综上，使得背栅线140b同时保持成本低的优势和良好的焊接效果。
在一个实施例中，所述第一子背栅线141b的厚度与所述第二子背栅线142b的厚度 的关系是5:1-9:1。在一个具体的实施例中，第一子背栅线141b的厚度为4μm-4.5μm，第二子背栅线142b的厚度为0.5μm-1μm。背栅线140b的总厚度为4μm-6μm，如5μm。
在一个实施例中，所述背栅线140b的高宽比为0.8:2-1:2。所述背栅线的宽度为9μm-11μm，所述背栅线的高度为4μm-6μm。
本实施例中，所述第一掺杂半导体层120b为纳米晶态，或所述第一掺杂半导体层120b为微晶态，其次，第一掺杂半导体层120b中掺杂离子的浓度较高，这样使得第一掺杂半导体层120b的电导率提高，第一掺杂半导体层120b具有高的掺杂浓度提高场钝化，也就是说，第一掺杂半导体层120b与第一本征半导体层110b之间的电场强度变大，更好的阻碍光生电子扩散至第一掺杂半导体层120b与第一本征半导体层110b之间的界面，使得光生电子更多的扩散至异质结太阳能电池的正面，降低光生载流子的复合几率。同时，第一掺杂半导体层120b的体电阻降低，降低第一掺杂半导体层120b和背面复合透明导电膜130b的接触电阻，改善异质结太阳能电池的串联电阻，提高异质结太阳能电池的光电转换效率。第一掺杂半导体层120b中的晶粒尺寸为1nm-10nm。
本实施例中，所述第一掺杂半导体层120b的材料为纳米晶态硅，或所述第一掺杂半导体层120b的材料为微晶态硅。
在一个实施例中，所述第一掺杂半导体层120b中的掺杂离子的浓度为2E19atom/cm 3-8E19atom/cm 3。当第一掺杂半导体层120b的导电类型为P型时，第一掺杂半导体层120b中的掺杂离子为P型离子，例如硼离子。
第一掺杂半导体层120b的晶化率为20％-80％。
在一个具体的实施例中，第一掺杂半导体层120b的厚度为7nm-14nm。
在一个具体的实施例中，第一掺杂半导体层120b的导电率为2x10 -1S/cm-8x10 -1S/cm。
所述异质结太阳能电池还包括：位于所述半导体衬底层100背向所述背面复合透明导电膜130b一侧的正面复合透明导电膜130a；所述正面复合透明导电膜130a的材料包括掺钨氧化铟。
本实施例中，所述正面复合透明导电膜130a为单层结构，所述正面复合透明导电膜130a的材料为掺钨氧化铟，掺钨氧化铟的迁移率大于氧化铟锡的迁移率，因此在保持正面复合透明导电膜130a的电阻一定的情况下，正面复合透明导电膜130a中的掺杂浓度可以降低，更少的掺杂浓度降低对自由载流子的复合，其次，更少的掺杂浓度使得正面复合透明导电膜130a的透过率提高，具体的增加对700nm-1100nm的光的透过率，异质结太阳能电池更多的吸收太阳光，提高异质结太阳能电池的短路电流，提高异质结太阳能电池的光电转换效率。
在一个具体的实施例中，正面复合透明导电膜130a的厚度70nm-80nm，正面复合透明导电膜130a的方阻为60Ω/square-100Ω/square，正面复合透明导电膜130a透过率大于85％，具体的，正面复合透明导电膜130a针对波长为350nm-1100nm的光的透过率大于85％。
所述异质结太阳能电池还包括：位于所述正面复合透明导电膜130a和所述半导体衬底层100之间的第二掺杂半导体层120a。所述第二掺杂半导体层120a的导电类型和所述 第一掺杂半导体层120b的导电类型相反。本实施例中，以所述第二掺杂半导体层120a的导电类型为N型作为示例。
所述第二掺杂半导体层120a为纳米晶态；或，所述第二掺杂半导体层120a为微晶态。
所述第二掺杂半导体层120a为纳米晶态，或所述第二掺杂半导体层120a为微晶态，其次，第二掺杂半导体层120a中掺杂离子的浓度较高，这样使得第二掺杂半导体层120a的电导率提高，第二掺杂半导体层120a具有高的掺杂浓度提高场钝化，也就是说，第二掺杂半导体层120a与第二本征半导体层110a之间的电场强度变大，更好的阻碍光生空穴扩散至第二掺杂半导体层120a与第二本征半导体层110a之间的界面，使得光生空穴更多的扩散至异质结太阳能电池的正面，降低光生载流子的复合几率。同时，第二掺杂半导体层120a的体电阻降低，降低第二掺杂半导体层120a和正面复合透明导电膜130a的接触电阻，改善异质结太阳能电池的串联电阻，提高异质结太阳能电池的光电转换效率。第二掺杂半导体层120a中的晶粒尺寸为1nm-10nm。
所述第二掺杂半导体层120a中掺杂离子的浓度为2E19atom/cm 3-8E19atom/cm 3。
所述异质结太阳能电池还包括：位于所述正面复合透明导电膜130a背向所述半导体衬底层100一侧的正栅线140a；所述正栅线140a包括第一子正栅线141a和位于第一子正栅线141a背向所述半导体衬底层100一侧表面的第二子正栅线142a；所述第一子正栅线141a的电导率大于所述第二子正栅线142a的电导率；所述第二子正栅线142a的熔点小于所述第一子正栅线141a的熔点。
在一个实施例中，所述第一子正栅线141a的材料包括铜；所述第二子正栅线142a的材料包括锡。第一子正栅线141a的材料为铜使得第一子正栅线141a具有较好的导电率的同时价格降低。第二子正栅线142a的材料为锡，锡的熔点较低，使得第二子正栅线142a与焊带之间的结合力提高，保证第二子正栅线142a与焊带之间的焊接效果。综上，使得正栅线140a同时保持成本低的优势和良好的焊接效果。
在一个实施例中，所述第一子正栅线141a的厚度与所述第二子正栅线142a的厚度的关系是5:1-9:1。在一个具体的实施例中，第一子正栅线141a的厚度为2μm-2.5μm，第二子正栅线142a的厚度为0.5μm-1μm。正栅线140a的总厚度为2.5μm-3.5μm，如3μm。所述正栅线的宽度为4μm-6μm，所述背栅线的高度为2.5μm-3.5μm。
需要说明的是，本实施例中，第一子正栅线141a的厚度小于第一子背栅线141b的厚度，这样的目的是为了使得正栅线140a的透过率提高，使得异质结太阳能的正面能接收更多的太阳光。
在一个实施例中，所述正栅线140a的高宽比为0.8:2-1:2。
所述异质结太阳能电池还包括：位于所述第一掺杂半导体层120b和所述半导体衬底层100之间的第一本征半导体层110b；位于所述第二掺杂半导体层120a和所述半导体衬底层100之间的第二本征半导体层110a。
相应的，本申请另一实施例还提供一种异质结太阳能电池的方法的制备方法，参考图2，包括以下步骤：
S1:提供半导体衬底层100；
S2:在所述半导体衬底层100的一侧形成背面复合透明导电膜130b。
形成所述背面复合透明导电膜130b的方法包括：
S21：在所述半导体衬底层100的一侧形成第一背面透明导电膜131；
S22：在所述第一背面透明导电膜131背向所述半导体衬底层100的一侧表面形成第二背面透明导电膜132；所述第一背面透明导电膜131和所述第二背面透明导电膜132中均掺杂有Ⅲ族重原子，所述第二背面透明导电膜132中的Ⅲ族重原子的浓度小于所述第一背面透明导电膜131中的Ⅲ族重原子的浓度。
形成所述背面复合透明导电膜130b的方法还包括：在形成所述第一背面透明导电膜131之前，在所述半导体衬底层100的一侧形成第三背面透明导电膜133；形成所述第一背面透明导电膜131之后，所述第三背面透明导电膜133位于所述第一背面透明导电膜131和所述半导体衬底层100之间。需要说明的是，本实施例中，以背面复合透明导电膜130b包括第一背面透明导电膜131、第二背面透明导电膜132和第三背面透明导电膜133为示例，在其他实施例中，背面复合透明导电膜130b可以不包括第三背面透明导电膜133。
下面结合图3至图7对异质结太阳能电池的方法的制备方法进行详细的说明。
参考图3，提供半导体衬底层100。
参考图4，在所述半导体衬底层100的一侧表面形成第一本征半导体层110b，在所述半导体衬底层100的另一侧表面形成第二本征半导体层110a。
参考图5，在所述第一本征半导体层110b背向所述半导体衬底层100的一侧形成第一掺杂半导体层120b；在所述第二本征半导体层110a背向所述半导体衬底层100的一侧形成第二掺杂半导体层120a。
在一个具体的实施例中，形成所述第一掺杂半导体层120b的工艺包括等离子体化学气相沉积工艺，等离子体化学气相沉积工艺的参数包括：采用的气体包括H 2、SiH 4和B 2H 6，H 2和SiH 4的流量比例为200:1.8-200:2.3，B 2H 6和SiH 4的流量比为1:1-1:5，腔室压强为0.3Pa-0.5Pa，射频功率密度为0.25mW/cm 2-0.4mW/cm 2。
所述第一掺杂半导体层120b中的掺杂离子的浓度为2E19atom/cm 3-8E19atom/cm 3。
本实施例中，所述第一掺杂半导体层120b为纳米晶态；或，所述第一掺杂半导体层120b为微晶态，其次，第一掺杂半导体层120b中掺杂离子的浓度较高。
在一个具体的实施例中，所述第一掺杂半导体层120b的材料为纳米晶态硅，或所述第一掺杂半导体层120b的材料为微晶态硅。
本实施例中，第二掺杂半导体层120a为纳米晶态；或，所述第二掺杂半导体层120a为微晶态，其次，第二掺杂半导体层120a中掺杂离子的浓度较高。在一个具体的实施例中，所述第二掺杂半导体层120a的材料为纳米晶态硅，或所述第二掺杂半导体层120a的材料为微晶态硅。
所述第二掺杂半导体层120a的形成工艺包括等离子体化学气相沉积工艺。
参考图6，在所述第一掺杂半导体层120b背向所述半导体衬底层100的一侧形成背面复合透明导电膜130b；在所述第二掺杂半导体层120a背向所述半导体衬底层100的一 侧形成正面复合透明导电膜130a。
形成所述背面复合透明导电膜130b的方法包括：在所述第一掺杂半导体层120b背向所述半导体衬底层100的一侧形成第三背面透明导电膜133；在所述第三背面透明导电膜133背向所述半导体衬底层100的一侧表面形成第一背面透明导电膜131；在所述第一背面透明导电膜131背向所述半导体衬底层100的一侧表面形成第二背面透明导电膜132；所述第一背面透明导电膜131和所述第二背面透明导电膜132中均掺杂有Ⅲ族重原子，所述第二背面透明导电膜132中的Ⅲ族重原子的浓度小于所述第一背面透明导电膜131中的Ⅲ族重原子的浓度。
所述第三背面透明导电膜133的迁移率大于所述第一背面透明导电膜131的迁移率且大于所述第二背面透明导电膜132的迁移率；所述第三背面透明导电膜133的功函数高于第一背面透明导电膜131的功函数且高于第二背面透明导电膜132的功函数。
形成所述第一背面透明导电膜131的工艺包括沉积工艺，如等离子体化学气相沉积工艺；形成第二背面透明导电膜132的工艺包括沉积工艺，如等离子体化学气相沉积工艺；形成所述第三背面透明导电膜133的工艺包括沉积工艺，如等离子体化学气相沉积工艺。
形成所述正面复合透明导电膜130a的工艺包括沉积工艺，如等离子体化学气相沉积工艺。
所述正面复合透明导电膜130a的材料包括掺钨氧化铟。
参考图7，在所述背面复合透明导电膜130b背向所述半导体衬底层100的一侧形成背栅线140b；在所述正面复合透明导电膜130a背向所述半导体衬底层100的一侧形成正栅线140a。
形成所述背栅线140b的步骤包括：在所述背面复合透明导电膜130b的表面形成图形化的第一光刻胶层，所述第一光刻胶层中具有第一栅线开口；采用蒸镀工艺在所述第一栅线开口中形成背栅线140b；采用蒸镀工艺在所述第一栅线开口中形成背栅线140b之后，去除所述第一光刻胶层。
形成所述第一光刻胶层的步骤包括：涂覆第一光刻胶膜；涂覆第一光刻胶膜之后，固化第一光刻胶膜；固化第一光刻胶膜之后，对第一光刻胶膜进行曝光；对第一光刻胶膜进行曝光之后，对第一光刻胶膜进行显影，形成第一光刻胶层。
去除所述第一光刻胶层的工艺包括脱模工艺。
采用蒸镀工艺在所述第一栅线开口中形成背栅线140b的步骤包括：采用蒸镀工艺在所述第一栅线开口中形成第一子背栅线141b；形成所述第一子背栅线141b之后，采用蒸镀工艺在第一栅线开口中形成位于第一子背栅线141b表面的第二子背栅线142b；所述第一子背栅线141b的电导率大于所述第二子背栅线142b的电导率；所述第二子背栅线142b的熔点小于所述第一子背栅线141b的熔点。
形成所述正栅线140a的步骤包括：在所述正面复合透明导电膜130a的表面形成图形化的第二光刻胶层，所述第二光刻胶层中具有第二栅线开口；采用蒸镀工艺在所述第二栅线开口中形成正栅线140a；采用蒸镀工艺在所述第二栅线开口中形成正栅线140a 之后，去除所述第二光刻胶层。
形成所述第二光刻胶层的步骤包括：涂覆第二光刻胶膜；涂覆第二光刻胶膜之后，固化第二光刻胶膜；固化第二光刻胶膜之后，对第二光刻胶膜进行曝光；对第二光刻胶膜进行曝光之后，对第二光刻胶膜进行显影，形成第二光刻胶层。
去除所述第二光刻胶层的工艺包括脱模工艺。
采用蒸镀工艺在所述第二栅线开口中形成正栅线140a的步骤包括：采用蒸镀工艺在所述第二栅线开口中形成第一子正栅线141a；形成所述第一子正栅线141a之后，采用蒸镀工艺在第二栅线开口中形成位于第一子正栅线141a表面的第二子正栅线142a；所述第一子正栅线141a的电导率大于所述第二子正栅线142a的电导率；所述第二子正栅线142a的熔点小于所述第一子正栅线141a的熔点。
本实施例中，由于形成正栅线140a的过程中采用蒸镀工艺，因此使得正栅线140a与正面复合透明导电膜130a的结合力较好，进一步降低正栅线140a与正面复合透明导电膜130a的接触电阻。
本实施例中，形成背栅线140b的过程中采用蒸镀工艺，因此使得背栅线140b和背面复合透明导电膜130b的结合力较好，进一步降低背栅线140b和背面复合透明导电膜130b的接触电阻。
本实施例中，该异质结太阳能电池的方法的制备方法还包括：对正栅线140a和背栅线140b进行固化处理；对正栅线140a和背栅线140b进行固化处理之后，进行光注入退火处理。
光注入退火处理指的是：在进行退火处理的同时，采用红外光对所述正栅线140a和背栅线140b进行照射，使得对正栅线140a和背栅线140b的热激加强。
关于制备方法中涉及到的各膜层的参数均参照前一实施例对应的内容，不再详述。
显然，上述实施例仅仅是为清楚地说明本申请技术要点所作的举例，而并非对实施方式的限定。对于所属领域的普通技术人员来说，在上述说明的基础上还可以做出其它不同形式的变化或变动。这里无需也无法对所有的实施方式予以穷举，而由此所引伸出的显而易见的变化或变动仍处于本发明创造的保护范围之中。

Claims (10)

  1. 一种异质结太阳能电池，其特征在于，包括：
    半导体衬底层；
    位于所述半导体衬底层一侧的背面复合透明导电膜；所述背面复合透明导电膜包括：
    第一背面透明导电膜；
    位于所述第一背面透明导电膜背向所述半导体衬底层一侧表面的第二背面透明导电膜；
    其中，所述第一背面透明导电膜和所述第二背面透明导电膜中均掺杂有Ⅲ族重原子，所述第二背面透明导电膜中Ⅲ族重原子的浓度小于所述第一背面透明导电膜中Ⅲ族重原子的浓度。
  2. 根据权利要求1所述的异质结太阳能电池，其特征在于，所述Ⅲ族重原子包括镓原子；所述第一背面透明导电膜的材料包括掺镓的氧化锌；所述第二背面透明导电膜的材料包括掺镓的氧化锌；
    优选的，所述第二背面透明导电膜中镓的质量百分比浓度与所述第一背面透明导电膜中镓的质量百分比浓度的比值为1:2-1:4；
    优选的，所述第一背面透明导电膜中镓的质量百分比浓度为1.5％-2％；所述第二背面透明导电膜中镓的质量百分比浓度为0.5％-1％；
    优选的，所述第二背面透明导电膜的厚度与所述第一背面透明导电膜的厚度的比值为1:4-1:3；
    优选的，所述第二背面透明导电膜的厚度为10nm-20nm；所述第一背面透明导电膜的厚度为50nm-60nm；
    优选的，所述异质结太阳能电池还包括：位于所述第二背面透明导电膜背向所述第一背面透明导电膜一侧表面的有机封装层。
  3. 根据权利要求1所述的异质结太阳能电池，其特征在于，所述背面复合透明导电膜还包括：第三背面透明导电膜，所述第三背面透明导电膜的功函数高于第一背面透明导电膜的功函数且高于第二背面透明导电膜的功函数；
    优选的，所述第三背面透明导电膜的迁移率大于所述第一背面透明导电膜的迁移率 且大于所述第二背面透明导电膜的迁移率；所述第三背面透明导电膜中掺杂离子的浓度小于所述第一背面透明导电膜中Ⅲ族重原子的浓度且小于第二背面透明导电膜中Ⅲ族重原子的浓度；
    优选的，所述第三背面透明导电膜的材料包括掺钨氧化铟；
    优选的，所述掺钨氧化铟中钨的质量百分比浓度为0.1％-0.3％；
    优选的，所述第三背面透明导电膜的厚度与第一背面透明导电膜的厚度的比值为1:5-1:6。
  4. 根据权利要求1所述的异质结太阳能电池，其特征在于，还包括：位于所述背面复合透明导电膜背向所述半导体衬底层一侧的背栅线；
    所述背栅线包括第一子背栅线和位于第一子背栅线背向所述半导体衬底层一侧表面的第二子背栅线；所述第一子背栅线的电导率大于所述第二子背栅线的电导率；所述第二子背栅线的熔点小于所述第一子背栅线的熔点；
    优选的，所述第一子背栅线的材料包括铜；所述第二子背栅线的材料包括锡；
    优选的，所述第一子背栅线的厚度与所述第二子背栅线的厚度的关系是5:1-9:1；
    优选的，所述背栅线的高宽比为0.8:2-1:2；所述背栅线的宽度为9μm-11μm，所述背栅线的高度为4μm-6μm。
  5. 根据权利要求1至4任意一项所述的异质结太阳能电池，其特征在于，还包括：位于所述半导体衬底层和所述背面复合透明导电膜之间的第一掺杂半导体层；所述第一掺杂半导体层为纳米晶态；或，所述第一掺杂半导体层为微晶态；
    优选的，所述第一掺杂半导体层中掺杂离子的浓度为2E19atom/cm 3-8E19atom/cm 3。
  6. 根据权利要求1至4任意一项所述的异质结太阳能电池，其特征在于，还包括：位于所述半导体衬底层背向所述背面复合透明导电膜一侧的正面复合透明导电膜；所述正面复合透明导电膜的材料包括掺钨氧化铟；
    优选的，还包括：位于所述半导体衬底层和所述正面复合透明导电膜之间的第二掺杂半导体层；所述第二掺杂半导体层为纳米晶态；或，所述第二掺杂半导体层为微晶态；
    优选的，所述异质结太阳能电池还包括：位于所述正面复合透明导电膜背向所述半导体衬底层一侧的正栅线；所述正栅线包括第一子正栅线和位于第一子正栅线背向所述半导体衬底层一侧表面的第二子正栅线；所述第一子正栅线的电导率大于所述第二子正 栅线的电导率；所述第二子正栅线的熔点小于所述第一子正栅线的熔点；
    优选的，所述第一子正栅线的材料包括铜；所述第二子正栅线的材料包括锡；
    优选的，所述第一子正栅线的厚度与所述第二子正栅线的厚度的关系是5:1-9:1；
    优选的，所述正栅线的高宽比为0.8:2-1:2；所述正栅线的宽度为4μm-6μm，所述正栅线的高度为2.5μm-3.5μm。
  7. 一种异质结太阳能电池的制备方法，其特征在于，包括：
    提供半导体衬底层；
    在所述半导体衬底层的一侧形成背面复合透明导电膜；形成所述背面复合透明导电膜的方法包括：
    在所述半导体衬底层的一侧形成第一背面透明导电膜；
    在所述第一背面透明导电膜背向所述半导体衬底层的一侧表面形成第二背面透明导电膜；
    其中，所述第一背面透明导电膜和所述第二背面透明导电膜中均掺杂有Ⅲ族重原子，所述第二背面透明导电膜中Ⅲ族重原子的浓度小于所述第一背面透明导电膜中Ⅲ族重原子的浓度。
  8. 根据权利要求7所述的异质结太阳能电池的制备方法，其特征在于，形成所述背面复合透明导电膜的方法还包括：在形成所述第一背面透明导电膜之前，在所述半导体衬底层的一侧形成第三背面透明导电膜；
    形成所述第一背面透明导电膜之后，所述第三背面透明导电膜位于所述第一背面透明导电膜和所述半导体衬底层之间；
    所述第三背面透明导电膜的功函数高于第一背面透明导电膜的功函数且高于第二背面透明导电膜的功函数；
    优选的，所述第三背面透明导电膜的迁移率大于所述第一背面透明导电膜的迁移率且大于所述第二背面透明导电膜的迁移率；所述第三背面透明导电膜中掺杂离子的浓度小于所述第一背面透明导电膜中Ⅲ族重原子的浓度且小于第二背面透明导电膜中Ⅲ族重原子的浓度。
  9. 根据权利要求7所述的异质结太阳能电池的制备方法，其特征在于，还包括：在所述背面复合透明导电膜背向所述半导体衬底层的一侧形成背栅线；
    形成所述背栅线的步骤包括：在所述背面复合透明导电膜的表面形成图形化的第一光刻胶层，所述第一光刻胶层中具有第一栅线开口；采用蒸镀工艺在所述第一栅线开口中形成背栅线；采用蒸镀工艺在所述第一栅线开口中形成背栅线之后，去除所述第一光刻胶层；
    优选的，采用蒸镀工艺在所述第一栅线开口中形成背栅线的步骤包括：采用蒸镀工艺在所述第一栅线开口中形成第一子背栅线；采用蒸镀工艺在第一栅线开口中形成位于第一子背栅线表面的第二子背栅线；所述第一子背栅线的电导率大于所述第二子背栅线的电导率；所述第二子背栅线的熔点小于所述第一子背栅线的熔点；
    优选的，所述异质结太阳能电池的制备方法还包括：在所述半导体衬底层的另一侧形成正面复合透明导电膜；所述正面复合透明导电膜的材料包括掺钨氧化铟；
    优选的，所述异质结太阳能电池的制备方法还包括：在所述正面复合透明导电膜背向所述半导体衬底层的一侧形成正栅线；
    形成所述正栅线的步骤包括：在所述正面复合透明导电膜的表面形成图形化的第二光刻胶层，所述第二光刻胶层中具有第二栅线开口；采用蒸镀工艺在所述第二栅线开口中形成正栅线；采用蒸镀工艺在所述第二栅线开口中形成正栅线之后，去除所述第二光刻胶层；
    优选的，采用蒸镀工艺在所述第二栅线开口中形成正栅线的步骤包括：采用蒸镀工艺在所述第二栅线开口中形成第一子正栅线；采用蒸镀工艺在第二栅线开口中形成位于第一子正栅线表面的第二子正栅线；所述第一子正栅线的电导率大于所述第二子正栅线的电导率；所述第二子正栅线的熔点小于所述第一子正栅线的熔点。
  10. 根据权利要求7所述的异质结太阳能电池的制备方法，其特征在于，还包括：在所述半导体衬底层的一侧形成第一掺杂半导体层；所述第一掺杂半导体层为纳米晶态；或，所述第一掺杂半导体层为微晶态；
    形成所述背面复合透明导电膜之后，所述第一掺杂半导体层位于所述半导体衬底层和所述背面复合透明导电膜之间；
    优选的，形成所述第一掺杂半导体层的工艺包括等离子体化学气相沉积工艺，等离子体化学气相沉积工艺的参数包括：采用的气体包括H 2、SiH 4和B 2H 6，H 2和SiH 4的流量比例为200:1.8-200:2.3，B 2H 6和SiH 4的流量比为1:1-1:5，腔室压强为0.3Pa-0.5Pa，射频功率密度为0.25mW/cm 2-0.4mW/cm 2。
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