WO2021147403A1 - 中间串联层、叠层光伏器件及生产方法 - Google Patents

中间串联层、叠层光伏器件及生产方法 Download PDF

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WO2021147403A1
WO2021147403A1 PCT/CN2020/122769 CN2020122769W WO2021147403A1 WO 2021147403 A1 WO2021147403 A1 WO 2021147403A1 CN 2020122769 W CN2020122769 W CN 2020122769W WO 2021147403 A1 WO2021147403 A1 WO 2021147403A1
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layer
nano
conductive
oxide
battery cell
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French (fr)
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吴兆
徐琛
李子峰
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隆基绿能科技股份有限公司
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Priority to US17/800,930 priority Critical patent/US20230083659A1/en
Priority to EP20915209.9A priority patent/EP4095929A4/en
Priority to AU2020425414A priority patent/AU2020425414B2/en
Publication of WO2021147403A1 publication Critical patent/WO2021147403A1/zh

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    • H—ELECTRICITY
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    • 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
    • H01L31/042—PV modules or arrays of single PV cells
    • H01L31/05—Electrical interconnection means between PV cells inside the PV module, e.g. series connection of PV cells
    • H01L31/0504—Electrical interconnection means between PV cells inside the PV module, e.g. series connection of PV cells specially adapted for series or parallel connection of solar cells in a module
    • H01L31/0512—Electrical interconnection means between PV cells inside the PV module, e.g. series connection of PV cells specially adapted for series or parallel connection of solar cells in a module made of a particular material or composition of materials
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    • 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
    • H01L31/0352—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 their shape or by the shapes, relative sizes or disposition of the semiconductor regions
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    • H01L31/035227—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 their shape or by the shapes, relative sizes or disposition of the semiconductor regions comprising a quantum structures the quantum structure being quantum wires, or nanorods
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    • H01L31/02—Details
    • H01L31/0236—Special surface textures
    • H01L31/02363—Special surface textures of the semiconductor body itself, e.g. textured active layers
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    • H01L31/0352—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 their shape or by the shapes, relative sizes or disposition of the semiconductor regions
    • H01L31/035209—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 their shape or by the shapes, relative sizes or disposition of the semiconductor regions comprising a quantum structures
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    • H01L31/18—Processes or apparatus specially adapted for the manufacture or treatment of these devices or of parts thereof
    • H—ELECTRICITY
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    • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L31/04—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices
    • H01L31/06—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices characterised by potential barriers
    • H01L31/072—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 potential barriers the potential barriers being only of the PN heterojunction type
    • H01L31/0725—Multiple junction or tandem solar cells
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    • H01L31/04—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices
    • H01L31/06—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices characterised by potential barriers
    • H01L31/078—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices characterised by potential barriers including different types of potential barriers provided for in two or more of groups H01L31/062 - H01L31/075

Definitions

  • the present invention relates to the field of solar photovoltaic technology, in particular to an intermediate tandem layer of a laminated photovoltaic device, a laminated photovoltaic device and a production method.
  • Stacked photovoltaic devices can divide sunlight into multiple wavelength bands. From front to back, battery cells with gradually decreasing band gaps are used to absorb sunlight of different energy in order to broaden the spectral response band to sunlight and reduce energy loss, so , Stacked photovoltaic devices have a wide range of application prospects.
  • an intermediate series layer is required to connect each battery cell in series.
  • one is metal
  • one is transparent conductive film
  • the other is tunnel junction.
  • the invention provides an intermediate series layer of a laminated photovoltaic device, a laminated photovoltaic device and a production method, and aims to solve the problem of power loss of the laminated photovoltaic device caused by the intermediate series layer.
  • an intermediate tandem layer of a stacked photovoltaic device having light transmittance
  • the intermediate tandem layer includes a longitudinal conductive layer
  • the longitudinal conductive layer is composed of longitudinally grown nano conductive pillars
  • the vertical conductive layer includes nano conductive units spaced apart from each other and an insulating barrier located between adjacent nano conductive units; the insulating barrier insulates each of the nano conductive units in the lateral direction.
  • the nano conductive column is one of columnar crystals, nano columns, nano rods, and nano tubes;
  • the lateral size of the nano conductive column is 0.5-500 nm
  • the material of the nano conductive column is selected from at least one of oxide semiconductor, selenide semiconductor, carbide, carbon, and conductive polymer.
  • the included angle between the nano conductive column and the longitudinal direction is less than or equal to 10°.
  • the shape of the nano conductive unit is: one of a linear shape, a column shape, a cone shape, or a rod shape;
  • the lateral dimension of the nano conductive unit is 0.5-500 nm
  • the material of the nano conductive unit is selected from at least one of metals, metal oxides, metal selenides, metal sulfides, carbon, and conductive polymers;
  • the material of the insulating barrier is selected from at least one of organic silicon, inorganic silicon, oxide dielectric, and polymer.
  • the metal is selected from at least one of gold, silver, platinum, aluminum, copper, tin, and titanium;
  • the metal oxide is selected from zinc oxide, tin oxide, titanium oxide, molybdenum oxide, copper oxide, vanadium oxide, thallium oxide, hafnium oxide, nickel oxide, tungsten oxide, indium oxide, gallium oxide, indium-doped tin oxide, and fluorine-doped At least one of tin oxide, aluminum-doped zinc oxide, and gallium-doped zinc oxide.
  • the included angle between the nano conductive unit and the longitudinal direction is less than or equal to 10°.
  • the average roughness of the light-facing surface of the intermediate tandem layer is less than or equal to 100 nm.
  • the intermediate tandem layer further includes a modification film on the backlight surface of the longitudinal conductive layer;
  • the material of the modified film is selected from the group consisting of metals, metal oxides, metal selenides, carbon, and carbides that have a catalytic effect, and the modified film serves as the seed layer of the nano conductive pillars or the nano conductive units;
  • the material of the modified film is selected from: electron selective contact materials.
  • the thickness of the modified film is 0.5-10 nm; the modified film is a continuous layer, or the modified film is densely packed with a plurality of lattice structures, and the lateral dimension of the lattice structure is 0.5-10nm.
  • the electron selective contact material is selected from at least one of fullerene, graphene, graphyne, calcium, lithium fluoride, and magnesium fluoride.
  • the average transmittance of the intermediate tandem layer in the 500-1300 nm band is greater than or equal to 85%.
  • the longitudinal dimension of the intermediate tandem layer is 10-1000 nm.
  • a stacked photovoltaic device comprising: at least two battery cells with different band gaps and the intermediate tandem layer as described above;
  • Each of the battery cells is sequentially stacked from top to bottom in the order of the band gap width energy of the absorption layer from top to bottom, and the intermediate series layer is located between adjacent battery cells.
  • the surface of the lower battery cell in contact with the middle tandem layer has a light trapping structure; the lower battery cell is a battery cell located on the backlight surface of the middle tandem layer.
  • a production method of a stacked photovoltaic device including:
  • a second battery cell is deposited on the light-receiving surface of the intermediate series layer; the band gap width of the second battery cell is greater than the band gap width of the first battery cell; the intermediate series layer is used to electrically interconnect the first battery cell A battery unit and the second battery unit.
  • the step of depositing an intermediate tandem layer includes:
  • each nano-conductive unit and insulating barrier using one of vacuum deposition, chemical method, chemical vapor deposition, and hot filament chemical vapor deposition to form each nano-conductive unit and insulating barrier.
  • the intermediate tandem layer includes a vertical conductive layer, and the vertical conductive layer is composed of vertically grown nano-conductive pillars.
  • the vertical conductive layer is composed of vertically grown nano-conductive pillars.
  • the conductivity is very strong, and further, the carriers are mainly transmitted vertically, and there is basically no lateral current, which is beneficial to reduce the power loss of the stacked photovoltaic device.
  • each nano-conductive unit breaks the conductive path in the lateral direction, so that the vertical conductive layer can basically only carry out the longitudinal transmission of carriers, and there is basically no lateral current, which is beneficial to reduce the stacking. Power loss of photovoltaic devices.
  • Figure 1 shows a schematic structural diagram of an intermediate tandem layer in an embodiment of the present invention
  • Figure 2 shows a schematic structural diagram of another intermediate tandem layer in an embodiment of the present invention
  • FIG. 3 shows a schematic diagram of the structure of an intermediate tandem layer and a lower-layer battery in an embodiment of the present invention
  • Figure 4 shows a schematic structural diagram of the first type of stacked photovoltaic device in an embodiment of the present invention
  • Figure 5 shows a schematic structural diagram of a second type of stacked photovoltaic device in an embodiment of the present invention
  • FIG. 6 shows a schematic structural diagram of a third type of laminated photovoltaic device in an embodiment of the present invention.
  • Fig. 7 shows a schematic structural diagram of a fourth type of stacked photovoltaic device in an embodiment of the present invention.
  • 1-Middle tandem layer 10-longitudinal conductive layer, 11-nanometer conductive column, 12-insulating barrier, 13-nanometer conductive unit, 21-upper battery cell, 22-lower battery cell, 14-modified film, 23-top layer Electrode, 24-bottom electrode.
  • the inventor of the present invention discovered during the process of studying the above-mentioned intermediate tandem layer that the reason for the power loss of the tandem photovoltaic device caused by the intermediate tandem layer lies in the fact that in the process of manufacturing the tandem photovoltaic device, the upper and lower battery cells are often in the lateral space area When the material properties appear uneven, the open circuit voltage or photocurrent in different regions will have a certain difference, and the existing intermediate series layer will have a lateral current, and the above-mentioned lateral current will eventually lead to the power loss of the laminated photovoltaic device.
  • the existing intermediate tandem layer will cause the carrier transport of the lower battery cell to concentrate on the leakage or invalidity.
  • the lateral position of the position is equivalent to reducing the overall parallel resistance of the device, which seriously causes the overall efficiency of the device to drop.
  • the intermediate series layer can be used to connect individual battery cells in series to form a stacked photovoltaic device.
  • each battery cell has a different band gap, and each battery cell is stacked from top to bottom in the order of band gap width energy from high to low.
  • the battery cell with the largest band gap is on the front, and the battery cell with the smallest band gap is on the back.
  • the middle tandem layer is light-transmissive and is used to pass through the upper battery cell to absorb the remaining waveband.
  • the light-transmitting wavelength band can be determined according to the wavelength band remaining after the upper-layer battery cell adjacent to it absorbs the wavelength band.
  • the light-transmitting light-transmitting waveband can be the waveband remaining after the upper-layer battery cell adjacent to it absorbs the waveband.
  • the average transmittance of the intermediate tandem layer in the 500-1300 nm band is greater than or equal to 85%. That is, the average transmittance of the intermediate tandem layer to the 500-1300nm wavelength band is greater than or equal to 85%, and furthermore, the light of the 500-1300nm wavelength band greater than or equal to 85% can be transmitted to the battery cells located on the backlight surface of the intermediate tandem layer , Which helps reduce optical loss.
  • FIG. 1 shows a schematic structural diagram of an intermediate tandem layer in an embodiment of the present invention.
  • the intermediate tandem layer includes a vertical conductive layer 10, and the vertical conductive layer 10 is composed of vertically grown nano conductive pillars 11.
  • the longitudinal direction refers to the direction perpendicular to the layer, that is, in the stacked photovoltaic device, the longitudinal direction is the direction in which each battery cell is stacked in the order of the band gap width energy from high to low, and from top to bottom. .
  • the nano-sized conductive pillars included in the vertical conductive layer are of nanometer scale and are evenly distributed in the entire vertical conductive layer.
  • each nano-conductive pillar is closely arranged, there are a large number of grain boundaries or interfaces between the nano-conductive pillars, or the lateral cross-linking between the nano-conductive pillars is less, making the lateral conductivity poorer, and further, the longitudinal
  • the conductive layer has weaker lateral conductivity.
  • the carriers are mainly transmitted longitudinally, and there is basically no lateral current, which is beneficial to reduce the power loss of the laminated photovoltaic device.
  • the shape of the nano conductive column is: one of columnar crystals, nano columns, nano rods, and nano tubes.
  • the lateral dimension of the nano conductive pillars is 0.5-500 nm.
  • the lateral dimension may be the width or diameter of the nano conductive pillars.
  • the lateral size of each nano-conductive column is smaller, and the distribution density of nano-conductive columns is higher.
  • the range of a single nano-conductive column to collect carriers is very small, which can be greatly improved.
  • the upper layer reduces the accumulation of carriers and can improve the longitudinal conductivity of the intermediate tandem layer.
  • the material of the nano conductive column is selected from at least one of oxide semiconductor, selenide semiconductor, carbide, carbon, and conductive polymer.
  • the intermediate tandem layer has better longitudinal conductivity.
  • carbide, carbon, and conductive polymers if the band gap of the intermediate tandem layer formed by oxide semiconductors and selenide semiconductors is generally greater than the band gap of the battery cells on the back side, the battery cells on the back side The light has almost no optical absorption.
  • the material of the nano conductive pillars may be: metal oxide materials such as copper oxide, molybdenum oxide, and related electrical doping materials.
  • the electrical doping materials may include: aluminum (Al), calcium (Ga) and other group III Metal doping.
  • the electrical doping material may also include halides such as fluorine (F) and bromine (Br)).
  • the material of the nano conductive column can also be metal selenide materials such as copper selenide and molybdenum selenide.
  • the material of the nano conductive column can also be: polyacetylene, polythiophene, polypyrrole, polyaniline, polyphenylene, polyphenylene vinylene, polydiacetylene and other intrinsically conductive conductive polymers and doped materials thereof.
  • the included angle between the nano conductive column and the longitudinal direction is less than or equal to 10°. That is, the angle between the nano-conductive pillar and the stacking direction of each layer of battery cells is less than or equal to 10°, which ensures a good vertical light transmittance.
  • the nano-conductive pillars in the intermediate tandem layer have refraction, scattering, etc., which increase the optical path.
  • the surface reflection of the lower battery unit is reduced, and it has a certain anti-reflection function.
  • FIG. 2 shows a schematic structural diagram of another intermediate tandem layer in an embodiment of the present invention.
  • the intermediate series layer includes a vertical conductive layer 10, and the vertical conductive layer 10 includes nano conductive units 13 spaced apart from each other, and an insulating barrier 12 located between adjacent nano conductive units 13.
  • the insulating barrier 12 insulates each nano-conductive unit 13 in the lateral direction. Since each nano-conductive unit 13 is insulated by the insulating barrier 12 in the lateral direction, the lateral conductivity of each nano-conductive unit 13 in the vertical conductive layer is interrupted by the insulating barrier 12, and further, the carriers are mainly transmitted longitudinally. There is basically no lateral current, which helps to reduce the power loss of stacked photovoltaic devices.
  • the shape of the nano-conductive unit is one of linear, columnar, cone-shaped, or rod-shaped.
  • the lateral size of the nano conductive unit is 0.5-500 nm.
  • the lateral dimension may be the width or diameter of the nano-conductive unit.
  • the lateral size of each nano-conductive unit is smaller, and the distribution density of the nano-conductive unit is higher, which is conducive to the collection of carriers.
  • the material of the nano conductive unit is selected from at least one of metal, metal oxide, metal selenide, metal sulfide, carbon, and conductive polymer.
  • the intermediate tandem layer has better vertical conductivity and light transmittance.
  • the above-mentioned semiconductor materials are used to form the intermediate layer.
  • the band gap of the tandem layer is generally larger than the band gap of the battery cell on the backlight side, and there is almost no optical absorption of the light from the battery cell on the backlight side.
  • the material of the insulating barrier is selected from at least one of organic silicon, inorganic silicon, oxide dielectric, and polymer.
  • the insulating barrier formed by the above-mentioned materials has a good insulating effect, and further reduces the lateral conductivity of the intermediate tandem layer. At the same time, the insulating barrier formed of the above-mentioned materials has good adhesion to the light-facing surface of the underlying battery cell.
  • metal can be selected from materials with low resistivity such as gold, silver, platinum, aluminum, copper, tin, and titanium.
  • the metal oxide can be selected from: zinc oxide, tin oxide, titanium oxide, molybdenum oxide, copper oxide, vanadium oxide, thallium oxide, hafnium oxide, nickel oxide, tungsten oxide, indium oxide, gallium oxide, and indium-doped tin oxide, doped Oxide conductive materials such as fluorine tin oxide, aluminum-doped zinc oxide, and gallium-doped zinc oxide. With the above materials, the intermediate conductive layer has good longitudinal conductivity.
  • the nano-conductive unit may be a graphene sheet that is vertically grown or arranged.
  • the material of the insulating barrier may be selected from: intrinsic amorphous silicon, silicon nitride, silicon carbide, silica gel, silica gel, alumina, epoxy resin, ethylene-vinyl acetate copolymer, and the like.
  • the included angle between the nano conductive unit and the longitudinal direction is less than or equal to 10°. That is, the angle between the stacking direction of the nano-conductive unit and each layer of battery unit is less than or equal to 10°, which ensures a good vertical light transmittance.
  • the nano-conductive units in the intermediate tandem layer have refraction, scattering, etc., which increase the optical path.
  • the surface reflection of the lower battery unit is reduced, and it has a certain anti-reflection function.
  • the average roughness of the light-facing surface of the intermediate tandem layer is less than or equal to 100 nm, and the light-facing surface of the intermediate tandem layer has better flatness, which is created for the deposition of battery cells located on the light-facing surface of the intermediate tandem layer.
  • the plane contact surface Specifically, ion etching or chemical etching can be used to planarize the light-facing surface of the intermediate tandem layer. For example, etch away excess insulating barriers, on the one hand, provide a relatively flat light-facing surface, and on the other hand, expose the nano-conductive unit, which facilitates subsequent electrical contact with the battery cell on the light-facing surface.
  • the intermediate tandem layer further includes a modification film on the backlight surface of the vertical conductive layer.
  • the material of the modified film is selected from the group consisting of metals, metal oxides, metal selenides, carbons, carbides with catalytic effect, and the modified film serves as the seed layer of the above-mentioned nano-conductive pillars or the above-mentioned nano-conductive unit.
  • the material of the modified film is selected from: electron selective contact materials.
  • the modified film can play the role of modifying the light-facing surface of the lower battery cell in contact with the intermediate tandem layer, and can reduce the contact resistance between the vertical conductive layer and the lower battery cell, or serve as a nano conductive column or nanometer in the vertical conductive layer.
  • the modified film and the lower battery cell in contact with the intermediate tandem layer have good adhesion to the light-facing surface.
  • the material of the modified film can be selected according to the material of the aforementioned nano-conductive pillar or the aforementioned nano-conductive unit.
  • the material of the modified film is selected from: catalytic metals, metal oxides, metal selenides, carbon, carbides ,
  • the modified film can be used as a seed layer of nano conductive pillars or nano conductive units.
  • a layer of silver nano-particles can be vapor-deposited on the smooth surface of the lower battery unit as a modified film in advance.
  • catalytic metal particles such as gold or zinc oxide nanoparticles can be deposited on the smooth surface of the lower battery unit in advance as a modified film.
  • carbon nanotubes are grown by chemical vapor deposition
  • catalytic metal particles such as platinum can be deposited on the smooth surface of the lower battery cell in advance as the modified film.
  • a thin layer of titanium oxide is used as a modified film on the smooth surface of the lower battery cell, which can play a role in surface field passivation, and at the same time, the thin layer of titanium oxide can play a role in reducing contact resistance.
  • the material of the modified film is selected from: electron selective contact materials.
  • the work function is the minimum energy required to move an electron from the inside of the solid to the surface of the object.
  • the low work function material may be a material whose minimum energy is less than or equal to 3.0 eV.
  • modified silver nanowires, zinc oxide nanowires, and carbon nanotubes can be low work function materials.
  • the electron selective contact material is usually a high work function material, and the high work function modified film can reduce the contact resistance with the light-facing surface of the underlying battery cell.
  • the high work function material may be the material with the minimum energy above 3.0 eV.
  • the thickness of the modified film is 0.5-10 nm.
  • the modified film is a continuous layer, or, the modified film is densely formed by a plurality of lattice structures, and the lateral dimension of the lattice structure is 0.5-10 nm.
  • a single lattice structure can be spherical or hemispherical, and the lateral dimension can be a diameter.
  • the electron selective contact material is selected from at least one of fullerene, graphene, graphyne, calcium, lithium fluoride, and magnesium fluoride.
  • the modified film formed of the above-mentioned materials can further reduce the contact resistance with the light-facing surface of the lower battery cell.
  • the longitudinal dimension of the intermediate tandem layer is 10-1000 nm.
  • the longitudinal dimension of the middle tandem layer is small and has good light transmittance. Specifically, if the light-facing surface of the lower battery cell is a plane, the longitudinal dimension of the middle tandem layer is 10-1000 nm. If the light-facing surface of the lower battery cell has a light-trapping structure, the middle tandem layer fills the light-trapping structure of the light-facing surface of the lower battery cell, and the remaining longitudinal dimension of the middle tandem layer is 10-1000 nm.
  • FIG. 3 shows a schematic structural diagram of an intermediate tandem layer and a lower-layer battery in an embodiment of the present invention.
  • the light-facing surface of the lower battery cell 22 is a light-trapping structure, excluding the thickness of the light-trapping structure of the intermediate tandem layer 1 filling the light-facing surface of the lower battery cell 22, on the light-facing surface of the lower battery cell 22
  • the longitudinal dimension d of the intermediate tandem layer 1 is 10-1000 nm.
  • the longitudinal dimension of the nano conductive pillars in the longitudinal conductive layer is consistent with the thickness of the longitudinal conductive layer, that is, the longitudinal direction of the nano conductive pillars penetrates the entire longitudinal conductive layer, that is, the two ends of the nano conductive pillars are respectively located in the longitudinal conductive layer The two sides of the.
  • the direct longitudinal dimension of the nano-conductive unit in the longitudinal conductive layer or the longitudinal dimension after internal cross-linking is consistent with the thickness of the longitudinal conductive layer, that is, the nanowires in the nano-conductive unit directly penetrate the entire longitudinal conductive layer longitudinally.
  • the nanowires in the nano conductive unit can penetrate the longitudinal conductive layer longitudinally after cross-linking. That is, the two longitudinal ends of the nanowire and the like in the nano conductive unit are respectively located on both sides of the longitudinal conductive layer, or the two ends of the nanowire and the like in the nano conductive unit after cross-linking are respectively located on both sides of the longitudinal conductive layer.
  • the thickness of the intermediate tandem layer is greater than the size of the light-trapping structure of the lower battery unit toward the light side to fill the light-trapping structure.
  • the use of metal series connection will cause serious optical shielding of the lower battery cell.
  • Using a thicker transparent conductive film to realize series connection will introduce a certain optical loss and the transparent conductive film has a relatively high resistivity, and has a certain lateral conductivity, which will introduce additional series resistance in the device.
  • the open circuit voltage or photocurrent in different areas may have certain differences. If the middle series layer has strong lateral conductivity, there will be lateral currents, resulting in power loss .
  • the middle tandem layer when the upper battery cell area is poorly prepared and invalid or leakage occurs, if the middle tandem layer has a strong lateral conductivity, it will cause the lower layer carrier lateral transport to concentrate on the leakage or invalid position, resulting in a decrease in the overall efficiency of the device. More, resulting in greater overall electrical loss, manifested by higher series resistance and lower parallel resistance. If the passivation layer is opened and filled with metal for electrical series connection, the optical shielding loss caused by the series metal is reduced to a certain extent and the series resistance is reduced, but there is still a certain optical shielding, and reducing the shielding requires less The number of openings and the smaller pore size will cause carriers to accumulate at the openings of the underlying battery, resulting in an increase in the series resistance of the overall device. Alleviating the accumulation of carriers requires more openings or larger apertures, which will further increase the optical shielding.
  • the intermediate tandem layer includes a vertical conductive layer, and the vertical conductive layer is composed of vertically grown nano-conductive pillars.
  • the longitudinal conductive layer has weaker lateral conductivity.
  • the carriers are mainly transmitted longitudinally, and there is basically no lateral current, which minimizes the electrical internal consumption problems caused by the uneven material characteristics of the upper and lower battery cells, which is beneficial to reduce stacking.
  • the power loss of a layered photovoltaic device or, due to the insulation effect of the insulating barrier in the lateral direction of each nano-conductive unit, the longitudinal conductive layer has a weaker lateral conductivity.
  • the carriers are mainly transmitted longitudinally, and there is basically no lateral current, which minimizes the upper layer and
  • the electrical internal consumption problem of the lower battery unit due to the uneven material properties of the area is beneficial to reduce the power loss of the stacked photovoltaic device.
  • the intermediate tandem layer has good light transmittance, high conductivity and high recombination rate, and achieves high longitudinal conductivity. Under the condition of ensuring reduced or no carrier accumulation in the intermediate tandem layer, it minimizes Blocking of incident light.
  • Fig. 4 shows a schematic structural diagram of the first type of stacked photovoltaic device in an embodiment of the present invention.
  • the laminated photovoltaic device includes at least two battery cells with different band gaps and any of the above-mentioned intermediate series layers.
  • the number of battery cells included in the stacked photovoltaic device is not specifically limited.
  • the stacked photovoltaic device includes two battery cells.
  • each battery cell is stacked from top to bottom in the order of the band gap energy of the absorber layer from high to low, the middle series layer is located between adjacent battery cells, and the middle series layer is used for conductive interconnection Each battery unit.
  • the battery cell 21 located above may be a wide band gap battery cell.
  • the battery cell 22 located below may be a narrow band gap battery cell.
  • the band gap of the narrow band gap battery cell 22 is smaller than the band gap of the wide band gap battery cell 21.
  • the wide band gap battery cell 21 and the narrow band gap battery cell 22 are stacked from top to bottom in the order of the band gap width energy of the absorption layer, and the middle series layer 1 is arranged on the wide band gap battery cell 21 and the narrow band gap battery cell 22 In between, the intermediate series layer 1 is used to electrically interconnect the wide band gap battery cell 21 and the narrow band gap battery cell 22.
  • the light-facing surface of the lower battery unit may be a flat surface or a light-trapping structure, and the backlight surface of the middle tandem layer is adapted to the light-facing surface of the lower battery unit.
  • the light-facing surface of the lower battery cell 22 is flat
  • the backlight surface of the middle tandem layer 1 is also flat
  • the light-facing surface of the middle tandem layer 1 is flat, creating a plane for the deposition of the upper battery cell 21 Contact surfaces.
  • FIG. 5 shows a schematic structural diagram of a second type of stacked photovoltaic device in an embodiment of the present invention.
  • the light-facing surface of the lower battery unit 22 may be flat, and the middle tandem layer 1 includes a modified film 14.
  • the backlight surface of the modification film 14 is a flat surface adapted to it.
  • the light-facing surface of the modification film 14 is a plane
  • the backlight surface of the longitudinal conductive layer 10 is a plane that matches the light-facing surface of the modification film 14
  • the light-facing surface of the intermediate tandem layer 1 is a plane, which is created for the deposition of the upper battery cell 21 Plane contact surface.
  • the surface of the lower battery cell in contact with the middle tandem layer has a light trapping structure
  • the lower battery cell is a battery cell located on the backlight surface of the middle tandem layer.
  • the light-facing surface of the lower battery cell has a light-trapping structure
  • the light-trapping structure may be a nano-optical structure, a suede structure, or the like.
  • the nano optical structure is a regular nano light trapping structure.
  • the suede structure is a pyramid, an inverted pyramid and other structures.
  • the light-facing surface of the lower battery unit has a light-trapping structure, which is beneficial to increase the optical path.
  • the light-trapping structure of the lower battery cell has a light-trapping structure
  • chemical coating methods such as spraying, spin coating, and solution methods can be used to prepare the intermediate tandem layer on the light-facing surface of the lower battery cell, and the intermediate tandem layer can be filled in.
  • the light-trapping structure of the light-facing surface of the lower battery unit also creates a plane contact surface for the upper battery unit.
  • FIG. 6 shows a schematic structural diagram of a third type of laminated photovoltaic device in an embodiment of the present invention.
  • the light-facing surface of the lower battery cell 22 has a light-trapping structure
  • the middle tandem layer 1 fills the light-trapping structure of the light-facing surface of the lower battery cell 22
  • the light-facing surface of the middle tandem layer 1 is flat, which is the upper battery cell.
  • the deposition of 21 creates a flat contact surface.
  • FIG. 7 shows a schematic structural diagram of a fourth type of stacked photovoltaic device in an embodiment of the present invention.
  • the light-facing surface of the lower battery unit 22 has a light-trapping structure
  • the middle tandem layer 1 includes a modified film 14.
  • the modified film 14 of the middle tandem layer 1 and the longitudinal conductive layer 10 fill the light-trapping structure of the light-facing surface of the lower battery cell 22, and the light-facing surface of the middle tandem layer 1 is a flat surface, creating a creation for the deposition of the upper battery cell 21 Plane contact surface.
  • the thickness of the upper battery cell absorption layer located on the light-facing side of the intermediate tandem layer is adjusted according to its material bandwidth to enhance its absorption capacity in the short-wavelength range of visible light and reduce ineffective absorption in the long-wavelength range of visible light. Keep the output current as consistent as possible to reduce the overall current loss.
  • the upper battery cell and the lower battery cell on the backlight surface of the middle series layer need to be current-adapted.
  • the upper battery cells on the light-facing side of the middle tandem layer and the lower battery cells on the back light side of the middle tandem layer need to be electrically polarized to keep the majority carrier flowing in the same direction.
  • the upper layer of the lower battery cell is n-type
  • the lower layer of the upper battery cell is the hole transport layer
  • the upper layer is the electron transport layer.
  • the upper layer of the lower battery cell is p-type
  • the lower layer of the upper battery cell is the electron transport layer
  • the upper layer is the hole transport layer.
  • the band gap width of the lower battery cell located on the backlight surface of the intermediate tandem layer is smaller than the band gap width of the upper battery cell located on the light-facing surface of the intermediate tandem layer.
  • the lower battery cell can be a crystalline silicon solar cell, a crystalline silicon/non-silicon heterojunction cell, and the substrate silicon material doping type is not limited, and it can be amorphous silicon, copper indium gallium selenium, cadmium telluride, Thin film solar cells such as gallium arsenide.
  • the light-facing surface of the lower battery unit can be a planar structure, a nano-optical structure or a suede structure, and the top layer has no insulating material or dielectric material.
  • the upper battery unit can be exciton solar cells such as perovskite materials, organic materials, quantum dot materials, or wide band gap semiconductors such as amorphous silicon, amorphous silicon carbide, copper indium gallium selenium, cadmium telluride, gallium arsenide, etc.
  • the band gap width of the absorbing material can be 1.5eV-2.3eV, and it can include one or more buffer layers or matching layers required for contact with the middle series layer to reduce the resistance between the middle series layer and the upper battery cell. complex.
  • the light-facing surface of the top battery cell is also provided with an anti-reflection film.
  • the anti-reflection film is used to reduce the overall optical loss of the stacked photovoltaic device.
  • the top battery cell is the battery cell with the largest band gap in the stacked photovoltaic device. Referring to FIG. 4, FIG. 5, FIG. 6 or FIG. 7, the stacked photovoltaic device may further include a top electrode 23 and a bottom electrode 24. Electrodes are used to collect and export carriers
  • the lower battery cell can also be a homojunction silicon solar cell, which uses p-type silicon wafers to prepare an n-type layer through thermal diffusion or ion implantation to form a pn junction, and the pn junction is located on the light-facing surface of the lower battery cell.
  • a passivation layer and a perforated electrical derivation structure can be made on the backlight surface of the lower battery unit, and full or local redoping (PERT, PERL) can be further used on the backlight surface.
  • the shining surface can be a polished surface. In order to reduce optical loss, nano-optical structures or suede structures can be made on the shining surface.
  • An oxide tunneling passivation layer and an intermediate tandem layer can be deposited on its smooth surface.
  • No dielectric material or anti-reflection film is deposited on the light-facing surface of the lower battery unit, so as to make electrical contact with the middle in series.
  • the lower battery cell is made into an inverted pyramid suede structure facing the smooth surface.
  • the average side length of the structure can be 500nm, the average side distance is 5nm, and the structure depth is 250-500nm.
  • the inverted pyramid structure can be obtained by metal ion-assisted anisotropic etching. .
  • the lower battery unit can also be a narrow band gap thin film solar cell, and the material of the absorption layer can be a narrow band gap or adjustable band gap material such as CIGS, amorphous silicon, CdTe, GaAs, perovskite.
  • the lower battery cell is a CIGS thin film solar cell with a conventional structure, a substrate, a molybdenum back electrode, a CIGS absorber layer, a CdS buffer layer, a ZnO window layer, and AZO transparent conductive film.
  • the longitudinal surface roughness is about 20nm.
  • the intermediate tandem layer of the battery cell in the stacked photovoltaic device can refer to the relevant description in the foregoing embodiment, and can achieve the same or similar beneficial effects. In order to avoid repetition, details are not described herein again.
  • the embodiment of the present invention also provides a method for producing a stacked photovoltaic device.
  • the method includes the following steps:
  • Step 101 Provide a first battery unit.
  • the first battery cell may be the above-mentioned lower battery cell with a relatively narrow band gap.
  • Step 102 deposit any of the intermediate tandem layers on the light-receiving surface of the first battery unit.
  • Step 103 deposit a second battery cell on the light-receiving surface of the intermediate series layer; the band gap width of the second battery cell is greater than the band gap width of the first battery cell; the intermediate series layer is used for conductive interconnection.
  • the first battery unit and the second battery unit deposit a second battery cell on the light-receiving surface of the intermediate series layer; the band gap width of the second battery cell is greater than the band gap width of the first battery cell; the intermediate series layer is used for conductive interconnection.
  • the first battery unit and the second battery unit is used for conductive interconnection.
  • the foregoing step 102 may include: using one of vacuum deposition, chemical method, chemical vapor deposition, and hot filament chemical vapor deposition to form each nano-conductive pillar; or, using vacuum deposition, chemical method, or chemical vapor deposition , A type of hot filament chemical vapor deposition, which deposits to form various nano-conductive units and insulating barriers.
  • one of vacuum deposition, chemical method, chemical vapor deposition, and hot filament chemical vapor deposition is used to deposit and form a plurality of nano conductive pillars on the light-facing surface of the lower battery unit to form a longitudinal conductive layer.
  • one of vacuum deposition, chemical method, chemical vapor deposition, and hot filament chemical vapor deposition is to form a plurality of nano conductive units and insulating barriers on the smooth surface of the lower battery unit.
  • a plurality of nano-conductive units and insulating barriers are simultaneously deposited on the smooth surface of the lower battery unit to form a longitudinal conductive layer .
  • deposit an insulating barrier on the smooth surface of the lower battery cell and then use vacuum deposition, chemical method, or chemical vapor deposition.
  • the deposition sequence of the insulating barrier and the nano-conductive unit is not specifically limited.
  • vacuum deposition may be: PECVD (Plasma Enhanced Chemical Vapor Deposition), LPCVD (Low Pressure Chemical Vapor Deposition), PVD (Physical Vapor Deposition) , Physical Vapor Deposition) and so on.
  • Hot Wire Chemical Vapor Deposition is Hot Wire Chemical Vapor Deposition, or HWCVD.
  • Chemical vapor deposition is Chemical Vapor Deposition, or CVD.
  • intrinsic amorphous silicon silicon nitride, silicon carbide, aluminum oxide and other insulating barriers
  • sol-gel and other liquid treatment processes using the first coating and then curing program, which can be used to deposit organic Materials such as silicon, polymer, epoxy resin, ethylene-vinyl acetate copolymer.
  • a modified film can be deposited by vapor deposition, and the modified film can be a seed layer lattice structure.
  • the seed material can be zinc oxide ZnO, and the average diameter of the seed layer lattice can be 10 nm.
  • the seed point plane spacing is 200nm.
  • the background vacuum of the evaporation chamber is not more than 5 ⁇ 10-4Pa, and the evaporation rate is 0.1-0.5nm/s.
  • ZnO nanowires can be grown on the seed layer by CVD (Chemical Vapor Deposition), with an average length of 600nm, a wire diameter of 10-50nm, and an angle of 0° between the nanowire and the longitudinal direction.
  • CVD Chemical Vapor Deposition
  • argon can be used as a carrier gas to control the transport rate of the gas flow and the source, so that the growth rate of ZnO is about 2-3nm/s or 1-2nm/s.
  • LPCVD can be used to deposit an insulating barrier.
  • the material of the insulating barrier is intrinsic amorphous silicon, and the thickness is filled and covered with the inverted pyramid structure of the underlying solar cell and ZnO nanowires, and the deposition thickness is 600-800 nm.
  • Argon can be used as the carrier gas, the background vacuum of the evaporation chamber is not more than 5 ⁇ 10-5Pa, the system pressure is 100-1000Pa, and the deposition rate is about 10-20nm/min or 5-10nm/min.
  • the intermediate tandem layer can be deposited by the sol-gel method, and the precursor solution contains uniformly dispersed magnetic silver nanowires with an average wire diameter of 10-20 nm and an average length of 50 nm.
  • the precursor solution is coated on the surface of the lower battery cell, it is cured in a magnetic field to form a SiO2 mesoporous film.
  • the silver nanowires are arranged in a consistent longitudinal direction and are in contact with AZO, and the deviation of the average angle from the longitudinal direction is not more than 3 °.
  • the intermediate tandem layer is etched with an alkaline solution to expose Ag nanowires on the surface, and the thickness of the intermediate tandem layer is about 40-50 nm.
  • a modified film can be deposited by vapor deposition.
  • the modified film has a seed layer lattice structure, the seed material is a titanium oxide lattice, the average diameter of the seed layer lattice is 5nm, and the seed points are densely packed.
  • the close-packed titanium oxide nanowires are grown hydrothermally on the seed layer, with an average length of 50nm, a wire diameter of 5-10nm, and the deviation of the nanowire from the longitudinal angle of no more than 3°.
  • the organic titanium source is used in the precursor solution of the hydrothermal method, the hydrothermal temperature does not exceed 200°C, and the crystal growth is carried out in a neutral environment, and the growth rate is about 3-4nm/min.
  • the shape, size, material, etc. of the nano conductive column, the nano conductive unit, the insulating barrier, the longitudinal conductive layer, etc. can be referred to the aforementioned related content, and in order to avoid repetition, it will not be repeated here.
  • the production method of the intermediate tandem layer of the above-mentioned laminated photovoltaic device can also achieve the above-mentioned similar beneficial effects, and in order to avoid repetition, it will not be repeated here.
  • the second battery cell can be deposited in a non-vacuum manner.
  • the second battery unit may be the upper battery unit with the above-mentioned wide band gap.
  • the deposition for the above-mentioned second solar cell can be as follows:
  • spin-coating nano-conductive pillar material on the smooth surface of the upper battery cell to form a longitudinal conductive layer, and the average thickness of the nano-conductive pillar may be 50 nm. Then spin-coating and curing the perovskite material on the smooth surface of the longitudinal conductive layer, the curing temperature does not exceed 150 °C, the thickness of the perovskite material is 500-1000nm; deposit the hole transport layer and TCO film on the surface of the perovskite absorption layer .
  • the hole transport layer material Spiro-OMeTAD
  • the curing temperature does not exceed 150 °C, the thickness of the perovskite material It is 500-1000nm; the electron transport layer and TCO film are deposited on the surface of the perovskite absorption layer.
  • the first battery cell, the second battery cell, the intermediate series layer, etc. of the method can refer to the relevant records in the foregoing embodiment, and can achieve the same or similar beneficial effects. In order to avoid repetition, here No longer.
  • each device can be referred to each other.

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Abstract

一种中间串联层（1）、叠层光伏器件及生产方法，涉及太阳能光伏技术领域。所述中间串联层（1）具有透光性；所述中间串联层（1）包括纵向导电层（10）；所述纵向导电层（10）由纵向生长的纳米导电柱（11）构成；或，所述纵向导电层（10）包括相互间隔分布的纳米导电单元（13）、以及位于相邻的纳米导电单元（13）之间的绝缘阻隔体（12）；所述绝缘阻隔体（12）在横向上绝缘各个所述纳米导电单元（13）。各个纳米导电柱（11）之间存在大量晶界或界面，横向导电性能较差，纵向导电层（10）具有较弱的横向导电能力，载流子主要纵向传输，基本没有横向电流。或，各个纳米导电单元（13）在横向上受到绝缘网格的绝缘作用，纵向导电层（10）具有较弱的横向导电能力，载流子主要纵向传输，基本没有横向电流，减少叠层光伏器件的功率损耗。

Description

中间串联层、叠层光伏器件及生产方法
本申请要求在2020年01月21日提交中国专利局、申请号为202010072789.7、发明名称为“中间串联层、叠层光伏器件及生产方法”的中国专利申请的优先权，其全部内容通过引用结合在本申请中。
技术领域
本发明涉及太阳能光伏技术领域，特别是涉及一种叠层光伏器件的中间串联层、叠层光伏器件及生产方法。
背景技术
叠层光伏器件可以将太阳光分成多个波段，从正面到背面，依次采用带隙逐渐减小的电池单元吸收不同能量的太阳光，以拓宽对太阳光的光谱响应波段，减少能量损失，因此，叠层光伏器件具有广泛的应用前景。
叠层光伏器件中需要采用中间串联层，将各个电池单元串联。目前，在叠层光伏器件的中间串联层主要有三种，一种是金属、一种是透明导电薄膜，还有一种是隧道结。
但是，上述中间串联层会导致叠层光伏器件的功率损耗。
发明内容
本发明提供一种叠层光伏器件的中间串联层、叠层光伏器件及生产方法，旨在解决中间串联层导致叠层光伏器件的功率损耗的问题。
根据本发明的第一方面，提供了一种叠层光伏器件的中间串联层，所述中间串联层具有透光性；
所述中间串联层包括纵向导电层；
所述纵向导电层由纵向生长的纳米导电柱构成；
或，
所述纵向导电层包括相互间隔分布的纳米导电单元、以及位于相邻的纳米导电单元之间的绝缘阻隔体；所述绝缘阻隔体在横向上绝缘各个所述纳米导电单元。
可选的，所述纳米导电柱为柱状晶体、纳米柱、纳米棒、纳米管中的一 种；
所述纳米导电柱的横向尺寸为0.5-500nm；
所述纳米导电柱的材料选自：氧化物半导体、硒化物半导体、碳化物、碳、导电聚合物中的至少一种。
可选的，所述纳米导电柱与纵向的夹角小于或等于10°。
可选的，所述纳米导电单元的形状为：线状、柱状、锥状或棒状中的一种；
所述纳米导电单元的横向尺寸为0.5-500nm；
所述纳米导电单元的材料选自：金属、金属氧化物、金属硒化物、金属硫化物、碳、导电聚合物中的至少一种；
所述绝缘阻隔体的材料选自：有机硅、无机硅、氧化物电介质、聚合物中的至少一种。
可选的，所述金属选自金、银、铂、铝、铜、锡、钛中的至少一种；
所述金属氧化物选自氧化锌、氧化锡、氧化钛、氧化钼、氧化铜、氧化钒、氧化铊、氧化铪、氧化镍、氧化钨、氧化铟、氧化镓、掺铟氧化锡、掺氟氧化锡、掺铝氧化锌、掺镓氧化锌中的至少一种。
可选的，所述纳米导电单元与纵向的夹角小于或等于10°。
可选的，所述中间串联层的向光面的平均粗糙度小于或等于100nm。
可选的，所述中间串联层还包括位于所述纵向导电层的背光面上的修饰膜；
所述修饰膜的材料选自：具有催化作用的金属、金属氧化物、金属硒化物，碳、碳化物，所述修饰膜作为所述纳米导电柱或所述纳米导电单元的种子层；
和/或，在所述纳米导电柱或所述纳米导电单元为低功函数材料的情况下，所述修饰膜的材料选自：电子选择性接触材料。
可选的，所述修饰膜的厚度为0.5-10nm；所述修饰膜为连续的一层，或，所述修饰膜由若干个点阵结构密布而成，所述点阵结构的横向尺寸为0.5-10nm。
可选的，所述电子选择性接触材料选自：富勒烯、石墨烯、石墨炔、钙、氟化锂、氟化镁中的至少一种。
可选的，所述中间串联层在500-1300nm波段的平均透过率大于或等于85％。
可选的，所述中间串联层的纵向尺寸为10-1000nm。
根据本发明的第二方面，提供了一种叠层光伏器件，包括：至少两个带隙不同的电池单元以及如前任一所述的中间串联层；
各个所述电池单元按照吸收层带隙宽度能量由高到低的顺序从上到下依次叠放，所述中间串联层位于相邻的电池单元之间。
可选的，下层电池单元与所述中间串联层接触的表面具有陷光结构；所述下层电池单元为位于所述中间串联层的背光面的电池单元。
根据本发明的第三方面，提供了一种叠层光伏器件的生产方法，包括：
提供第一电池单元；
在所述第一电池单元的受光面沉积前述任一所述的中间串联层；
在所述中间串联层的受光面沉积第二电池单元；所述第二电池单元的带隙宽度大于所述第一电池单元的带隙宽度；所述中间串联层用于导电互联所述第一电池单元和所述第二电池单元。
可选的，沉积中间串联层的步骤包括：
采用真空沉积、化学法、化学气相沉积、热丝化学气相沉积中的一种，沉积形成各个纳米导电柱；
或，采用真空沉积、化学法、化学气相沉积、热丝化学气相沉积中的一种，沉积形成各个纳米导电单元和绝缘阻隔体。
本发明实施例中，中间串联层包括纵向导电层，纵向导电层由纵向生长的纳米导电柱构成，各个纳米导电柱横向之间存在大量晶界或界面，使得其横向导电性能较差，而纵向导电能力很强，进而，载流子主要纵向传输，基本没有横向电流，利于减少叠层光伏器件的功率损耗。或，各个纳米导电单元由于在横向上受到绝缘阻隔体的绝缘作用，打断了横向上的导电通路，使得纵向导电层基本只能进行载流子纵向传输，基本没有横向电流，利于减少叠层光伏器件的功率损耗。
上述说明仅是本发明技术方案的概述，为了能够更清楚了解本发明的技术手段，而可依照说明书的内容予以实施，并且为了让本发明的上述和其它目的、特征和优点能够更明显易懂，以下特举本发明的具体实施方式。
附图说明
为了更清楚地说明本发明实施例的技术方案，下面将对本发明实施例的描述中所需要使用的附图作简单地介绍，显而易见地，下面描述中的附图仅 仅是本发明的一些实施例，对于本领域普通技术人员来讲，在不付出创造性劳动性的前提下，还可以根据这些附图获得其他的附图。
图1示出了本发明实施例中的一种中间串联层的结构示意图；
图2示出了本发明实施例中的另一种中间串联层的结构示意图；
图3示出了本发明实施例中的一种中间串联层与下层电池的结构示意图；
图4示出了本发明实施例中的第一种叠层光伏器件的结构示意图；
图5示出了本发明实施例中的第二种叠层光伏器件的结构示意图；
图6示出了本发明实施例中的第三种叠层光伏器件的结构示意图；
图7示出了本发明实施例中的第四种叠层光伏器件的结构示意图。
附图编号说明：
1-中间串联层，10-纵向导电层，11-纳米导电柱，12-绝缘阻隔体，13-纳米导电单元，21-上层电池单元，22-下层电池单元，14-修饰膜，23-顶层电极，24-底层电极。
具体实施例
下面将结合本发明实施例中的附图，对本发明实施例中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发明一部分实施例，而不是全部的实施例。基于本发明中的实施例，本领域普通技术人员在没有作出创造性劳动前提下所获得的所有其他实施例，都属于本发明保护的范围。
本发明的发明人在研究上述中间串联层的过程中发现，中间串联层导致叠层光伏器件的功率损耗的原因在于：在制作叠层光伏器件的过程中，往往上下层电池单元横向空间区域上材料特性出现不均匀的情况，此时不同区域开路电压或者光生电流就会出现一定的差异，现有的中间串联层则会存在横向电流，上述横向电流会最终导致叠层光伏器件的功率损耗。特别是，当上层电池单元为薄膜电池时，若制备薄膜质量较差，甚至出现无效或漏电的情况下，现有的中间串联层则会导致下层电池单元的载流子传输集中于漏电或无效位置的横向，相当于减小了器件整体的并联电阻，严重导致器件整体效率下降。
在本发明实施例中，该中间串联层可以用于串联各个电池单元以形成叠层光伏器件。其中，各个电池单元具有不同的带隙，各个电池单元按照 带隙宽度能量由高到低的顺序，从上到下依次叠放。带隙最大的电池单元位于正面，带隙最小的电池单元位于背面。
中间串联层具有透光性，用于透过上层电池单元吸收之后剩余的波段。该透光性的透光波段可以根据与其相邻的上层电池单元吸收波段之后剩余的波段确定。如，该透光性的透光波段即可以为与其相邻的上层电池单元吸收波段之后剩余的波段。
在本发明实施例中，可选的，中间串联层在500-1300nm波段的平均透过率大于或等于85％。即，中间串联层对500-1300nm波段的平均透过率大于或等于85％，进而，能够将500-1300nm波段大于或等于85％的光，透过给位于该中间串联层背光面的电池单元，利于减少光学损失。
参照图1，图1示出了本发明实施例中的一种中间串联层的结构示意图。参照图1所示，该中间串联层包括纵向导电层10，该纵向导电层10由纵向生长的纳米导电柱11构成。可以理解的是，纵向是指垂直于层的方向，也即，在叠层光伏器件中，纵向为各个电池单元按照带隙宽度能量由高到低的顺序，从上到下依次叠放的方向。
该纵向导电层包含的纳米导电柱为纳米尺度的，均匀分布在整个纵向导电层中。
参照图1所示，各个纳米导电柱是紧密排列的，纳米导电柱之间存在大量晶界或界面，或者，纳米导电柱之间横向交联较少，使得横向导电性能较差，进而，纵向导电层具有较弱的横向导电能力。同时，各个纳米导电柱之间纵向联系或导电路径较多，中间串联层具有良好的纵向导电能力，进而，载流子主要纵向传输，基本没有横向电流，利于减少叠层光伏器件的功率损耗。
可选的，纳米导电柱的形状为：柱状晶体、纳米柱、纳米棒、纳米管中的一种。纳米导电柱的横向尺寸为0.5-500nm。该横向尺寸可以为纳米导电柱的宽度或直径等。相对于金属开孔的中间串联层的方式，各个纳米导电柱的横向尺寸较小，同时纳米导电柱的分布密度较高，单个纳米导电柱收集载流子的范围很小，能够从很大程度上减少载流子堆积，能够提升中间串联层的纵向导电能力。
可选的，纳米导电柱的材料选自：氧化物半导体、硒化物半导体、碳化物、碳、导电聚合物中的至少一种。采用上述材料，中间串联层具有较好的纵向导电性。同时，除了碳化物、碳、导电聚合物之外，若采用氧化 物半导体、硒化物半导体形成的中间串联层的带隙通常大于与其背光面的电池单元的带隙，对其背光面的电池单元的光几乎无光学吸收。
例如，纳米导电柱的材料可以为：氧化铜、氧化钼等金属氧化物材料，以及与其相关的电学掺杂材料，该电学掺杂材料可以包括：铝(Al)、钙(Ga)等III族金属掺杂。该电学掺杂材料还可以包括：氟(F)、溴(Br)等卤化物)。该纳米导电柱的材料还可以为：硒化铜、硒化钼等金属硒化物材料。该纳米导电柱的材料还可以为：聚乙炔、聚噻吩、聚吡咯、聚苯胺、聚苯撑、聚苯撑乙烯和聚双炔等本征导电型导电聚合物及其掺杂材料。
可选的，纳米导电柱与纵向的夹角小于或等于10°。即，纳米导电柱与各层电池单元叠放的方向的夹角小于或等于10°，这样保证了良好的垂直光线透过率。当光线斜射时，该中间串联层中各个纳米导电柱之间具有折射、散射等，增加了光程，通过上述几何光学原理，降低了下层电池单元表面反射，具备一定的减反射功能。
或者，参照图2，图2示出了本发明实施例中的另一种中间串联层的结构示意图。参照图2所示，该中间串联层包括纵向导电层10，该纵向导电层10包括相互间隔分布的纳米导电单元13、以及位于相邻的纳米导电单元13之间的绝缘阻隔体12。该绝缘阻隔体12在横向上绝缘各个纳米导电单元13。各个纳米导电单元13由于在横向上受到绝缘阻隔体12的绝缘作用，纵向导电层中的各个纳米导电单元13的横向导电能力被绝缘阻隔体12所打断，进而，载流子主要纵向传输，基本没有横向电流，利于减少叠层光伏器件的功率损耗。
可选的，纳米导电单元的形状为：线状、柱状、锥状或棒状中的一种。纳米导电单元的横向尺寸为0.5-500nm。该横向尺寸可以为纳米导电单元的宽度或直径等。各个纳米导电单元的横向尺寸较小，同时纳米导电单元的分布密度较高，有利于载流子的收集。
可选的，纳米导电单元的材料选自：金属、金属氧化物、金属硒化物、金属硫化物、碳、导电聚合物中的至少一种。采用上述材料，中间串联层具有较好的纵向导电性和透光性，同时，除了上述金属、金属氧化物、金属硒化物、金属硫化物、碳材料之外，若采用上述半导体材料形成的中间串联层，其带隙通常大于其背光面的电池单元的带隙，对其背光面的电池单元的光几乎无光学吸收。绝缘阻隔体的材料选自：有机硅、无机 硅、氧化物电介质、聚合物中的至少一种。上述材料形成的绝缘阻隔体具有良好的绝缘作用，进一步减小中间串联层的横向导电能力。同时，上述材料形成的绝缘阻隔体与下层电池单元的向光面具有良好的附着性。
可选的，纳米导电单元的材料中：金属可以选自：金、银、铂、铝、铜、锡、钛等电阻率较低的材料。金属氧化物可以选自：氧化锌、氧化锡、氧化钛、氧化钼、氧化铜、氧化钒、氧化铊、氧化铪、氧化镍、氧化钨、氧化铟、氧化镓，以及掺铟氧化锡、掺氟氧化锡、掺铝氧化锌、掺镓氧化锌等氧化物导电材料。采用上述材料，中间导电层具有良好的纵向导电能力。
例如，纳米导电单元可以为纵向生长或排布的石墨烯片。例如，绝缘阻隔体的材料可以选自：本征非晶硅、氮化硅、碳化硅、氧化硅胶体、硅胶、氧化铝、环氧树脂、乙烯-醋酸乙烯共聚物等。
可选的，纳米导电单元与纵向的夹角小于或等于10°。即，纳米导电单元与各层电池单元叠放的方向的夹角小于或等于10°，保证了良好的垂直光线透过率。当光线斜射时，该中间串联层中各个纳米导电单元之间具有折射、散射等，增加了光程，通过上述几何光学原理，降低了下层电池单元表面反射，具备一定的减反射功能。
可选的，中间串联层的向光面的平均粗糙度小于或等于100nm，进而中间串联层的向光面具有较好的平整度，为位于中间串联层的向光面的电池单元的沉积创造了平面接触面。具体的，可以采用离子刻蚀或化学刻蚀等方式，对中间串联层的向光面进行平整化处理。例如，刻蚀掉多余的绝缘阻隔体，一方面提供较为平整的向光面，另一方面暴露出纳米导电单元，利于后续与向光面的电池单元进行电学接触。
在一优选实施方式中，中间串联层还包括位于上述纵向导电层的背光面上的修饰膜。该修饰膜的材料选自：具有催化作用的金属、金属氧化物、金属硒化物、碳、碳化物，该修饰膜作为上述纳米导电柱或上述纳米导电单元的种子层。和/或，在上述纳米导电柱或上述纳米导电单元为低功函数材料的情况下，上述修饰膜的材料选自：电子选择性接触材料。
具体的，修饰膜可以起到修饰与中间串联层接触的下层电池单元的向光面的作用，可以降低纵向导电层与下层电池单元的接触电阻，或，作为纵向导电层中纳米导电柱或纳米导电单元的生长点，以及，与中间串联层接触的下层电池单元的向光面等作用。修饰膜和与中间串联层接触的下层 电池单元的向光面有良好的附着性。可以依据上述纳米导电柱或上述纳米导电单元的材料选择修饰膜的材料。
当纵向导电层中纳米导电柱或纳米导电单元需要在下层电池单元的向光面生长得到时，修饰膜的材料选自：具有催化作用的金属、金属氧化物、金属硒化物，碳、碳化物，该修饰膜可以作为纳米导电柱或纳米导电单元的种子层。
如，采用水热法生长银纳米线的纳米导电单元时，可以提前在下层电池单元的向光面蒸镀一层银纳米颗粒作为修饰膜。采用化学气相沉积法生长氧化锌纳米线的纳米导电单元时，可以提前在下层电池单元的向光面沉积金等催化金属颗粒或氧化锌纳米颗粒作为修饰膜。再例如，采用化学气相沉积法生长碳纳米管时，可以提前在下层电池单元的向光面沉积铂等催化金属颗粒作为修饰膜。
此外，还可以依据下层电池单元的向光面钝化的需求，修饰膜可以选择具备钝化性能的材料。如，在下层电池单元的向光面采用氧化钛薄层作为修饰膜，可以起到表面场钝化作用，同时氧化钛薄层可以起到降低接触电阻的作用。
在纳米导电柱或纳米导电单元为低功函数材料的情况下，修饰膜的材料选自：电子选择性接触材料。功函数(work function)为：把一个电子从固体内部刚刚移到此物体表面所需的最少的能量。低功函数材料可以为上述最少的能量小于或等于3.0eV的材料。如，改性银纳米线、氧化锌纳米线、碳纳米管可以为低功函数材料。在纳米导电柱或纳米导电单元为低功函数材料的情况下，低功函数导电能力好，但是对电子的亲和能力差，收集电子能力差，接触电阻大，使得纵向导电层与下层电池单元的向光面的接触电阻大。而，电子选择性接触材料通常为高功函数材料，高功函数的修饰膜可以降低与下层电池单元的向光面的接触电阻。该高功函数材料可以为上述最少的能量大于3.0eV的材料。
可选的，修饰膜的厚度为0.5-10nm。修饰膜为连续的一层，或，修饰膜由若干个点阵结构密布而成，该点阵结构的横向尺寸为0.5-10nm。单个点阵结构可以为球形或半球形，该横向尺寸可以为直径。
可选的，上述修饰膜的材料中：电子选择性接触材料选自：富勒烯、石墨烯、石墨炔、钙、氟化锂、氟化镁中的至少一种。上述材料形成的修饰膜，可以进一步降低与下层电池单元的向光面的接触电阻。
可选的，中间串联层的纵向尺寸为10-1000nm。中间串联层的纵向尺寸较小，具有良好的透光性。具体的，若下层电池单元的向光面为平面，则，中间串联层的纵向尺寸即为10-1000nm。若下层电池单元的向光面为陷光结构，则，中间串联层在填充满下层电池单元的向光面的陷光结构的基础上，中间串联层的剩余纵向尺寸为10-1000nm。
如，参照图3所示，图3示出了本发明实施例中的一种中间串联层与下层电池的结构示意图。图3中，下层电池单元22的向光面为陷光结构，不算中间串联层1在填充满下层电池单元22的向光面的陷光结构的厚度，在下层电池单元22的向光面的陷光结构的顶点之上，中间串联层1的纵向尺寸d为10-1000nm。
可选的，纵向导电层中的纳米导电柱的纵向尺寸与纵向导电层的厚度一致，也即纳米导电柱的纵向贯穿整个纵向导电层，也就是说，纳米导电柱的两头分别位于纵向导电层的两面。
或，纵向导电层中的纳米导电单元的直接的纵向尺寸或内部交联后的纵向尺寸与纵向导电层的厚度一致，也即纳米导电单元中的纳米线等直接纵向贯穿整个纵向导电层，亦或纳米导电单元中的纳米线等交联之后可以纵向贯穿纵向导电层。也就是说，纳米导电单元中的纳米线等纵向两头分别位于纵向导电层的两面，亦或纳米导电单元中的纳米线等交联之后的两头分别位于纵向导电层的两面。
在本发明实施例中，在下层电池单元向光面为陷光结构的情况下，中间串联层的厚度大于下层电池单元向光面的陷光结构的尺寸，以填充该陷光结构。
若上述中间串联层采用金属、透明导电薄膜或隧道结，采用金属串联会对下层电池单元造成较严重的光学遮挡。采用较厚的透明导电薄膜实现串联，会引入一定的光学损失且透明导电薄膜电阻率仍然相对较高，且具有一定的横向导电能力，会在器件中引入额外的串联电阻。当上下层电池单元横向空间区域材料特性出现不均匀的情况下，不同区域开路电压或者光生电流可能会出现一定的差异，如果中间串联层横向导电能力较强，则会存在横向电流，造成功率损耗。此外，当上层电池单元区域制备质量较差出现无效或漏电的情况时，如果中间串联层横向导电能力较强，则会导致下层载流子横向传输集中于漏电或无效位置，导致器件整体效率下降较多，造成整体电学损失较大，表现为串联电阻较高及并联电阻较小。若用 钝化层开孔并填充金属的方式进行电学串联，在一定程度上减少了串联金属造成的光学遮挡损失并降低了串联电阻，但是仍存在一定的光学遮挡，且降低遮挡需要较少的开孔数量及较小的孔径，此时会导致底层电池在开孔处的载流子堆积，造成整体器件串联电阻增大。缓解载流子堆积需要较多的开孔或较大的孔径，又会进一步提高光学遮挡。
而在本发明实施例中，中间串联层包括纵向导电层，纵向导电层由纵向生长的纳米导电柱构成，各个纳米导电柱之间存在大量晶界或界面，使得，横向导电性能较差，进而纵向导电层具有较弱的横向导电能力，进而，载流子主要纵向传输，基本没有横向电流，最大限度的减少了上层和下层电池单元由于区域材料特性不均匀导致的电学内耗问题，利于减少叠层光伏器件的功率损耗。或，各个纳米导电单元由于在横向上受到绝缘阻隔体的绝缘作用，纵向导电层具有较弱的横向导电能力，进而，载流子主要纵向传输，基本没有横向电流，最大限度的减少了上层和下层电池单元由于区域材料特性不均匀导致的电学内耗问题，利于减少叠层光伏器件的功率损耗。同时，该中间串联层具备良好的透光性、高导电率和高复合速率，实现了纵向的高导电率，在保证减少或无载流子在中间串联层堆积的情况下，最大程度减少了对入射光的遮挡。
参照图4，图4示出了本发明实施例中的第一种叠层光伏器件的结构示意图。
该叠层光伏器件包括至少两个带隙不同的电池单元以及上述任一中间串联层。叠层光伏器件中包括的电池单元的个数不作具体限定。如，参照图4所示，图4中，叠层光伏器件中包括了2个电池单元。
在叠层光伏器件中：各个电池单元按照吸收层带隙宽度能量由高到低的顺序从上到下依次叠放，中间串联层位于相邻的电池单元之间，中间串联层用于导电互联各个电池单元。
如，参照图4，2个电池单元中，位于上方的电池单元21可以为宽带隙电池单元。位于下方的电池单元22可以为窄带隙电池单元。窄带隙电池单元22的带隙小于宽带隙电池单元21的带隙。宽带隙电池单元21和窄带隙电池单元22，按照吸收层带隙宽度能量由高到低的顺序由上至下依次叠放，中间串联层1设置在宽带隙电池单元21和窄带隙电池单元22之间，中间串联层1用于导电互联宽带隙电池单元21和窄带隙电池单元22。
在本发明实施例中，下层电池单元的向光面可以为平面或陷光结构， 中间串联层的背光面与下层电池单元的向光面相适配。例如，参照图4所示，下层电池单元22的向光面为平面，中间串联层1的背光面也为平面，中间串联层1的向光面为平面，为上层电池单元21的沉积创造平面接触面。
再例如，参照图5所示，图5示出了本发明实施例中的第二种叠层光伏器件的结构示意图。下层电池单元22的向光面可以为平面，中间串联层1包括有修饰膜14。修饰膜14的背光面为与之适配的平面。修饰膜14的向光面为平面，纵向导电层10的背光面为与修饰膜14的向光面适配的平面，中间串联层1的向光面为平面，为上层电池单元21的沉积创造平面接触面。
可选的，下层电池单元与中间串联层接触的表面具有陷光结构，该下层电池单元为位于中间串联层的背光面的电池单元。即，下层电池单元的向光面具有陷光结构，该陷光结构可以为纳米光学结构、绒面结构等。纳米光学结构为规则的纳米陷光结构。绒面结构为金字塔、倒金字塔等结构。下层电池单元的向光面具有陷光结构，利于增加光程。在下层电池单元的向光面具有陷光结构的情况下，可以采用喷涂、旋涂等化学涂敷法及溶液法在下层电池单元的向光面制备上述中间串联层，上述中间串联层填平下层电池单元的向光面的陷光结构，同样为上层电池单元创造了平面接触面。
例如，参照图6所示，图6示出了本发明实施例中的第三种叠层光伏器件的结构示意图。下层电池单元22的向光面具有陷光结构，中间串联层1在填充下层电池单元22的向光面的陷光结构的基础上，中间串联层1的向光面为平面，为上层电池单元21的沉积创造平面接触面。
再例如，参照图7所示，图7示出了本发明实施例中的第四种叠层光伏器件的结构示意图。图7中，下层电池单元22的向光面具有陷光结构，中间串联层1包括有修饰膜14。中间串联层1的修饰膜14和纵向导电层10在填充下层电池单元22的向光面的陷光结构的基础上，中间串联层1的向光面为平面，为上层电池单元21的沉积创造平面接触面。
在本发明实施例中，位于中间串联层的向光面的上层电池单元吸收层厚度依据其材料带宽进行调节，增强其在可见光短波段吸收能力，降低在可见光长波段的无效吸收，上层电池单元输出电流尽可能保持一致以降低整体电流损失。上层电池单元和位于中间串联层的背光面的下层电池单元需要进行电流适配。
位于中间串联层的向光面的上层电池单元和位于中间串联层的背光面的下层电池单元需进行电学极性适配，保持多数载流子流向一致。如，下层电池单元的上层为n型，则，上层电池单元的下层为空穴传输层，上层为电子传输层。反之，如下层电池单元的上层为p型，则上层电池单元的下层为电子传输层，上层为空穴传输层。
位于中间串联层的背光面的下层电池单元的带隙宽度小于位于中间串联层的向光面的上层电池单元的带隙宽度。下层电池单元可以为可为晶体硅太阳电池，可为晶体硅/非硅异质结电池，其衬底硅材料掺杂类型不限，可为非晶硅、铜铟镓硒、碲化镉、砷化镓等薄膜太阳电池。下层电池单元的向光面可为平面结构、纳米光学结构或绒面结构，顶层无绝缘材料或电介质材料。上层电池单元可为钙钛矿材料、有机材料、量子点材料等激子太阳电池，也可为非晶硅、非晶碳化硅、铜铟镓硒、碲化镉、砷化镓等宽带隙半导体太阳电池，其吸收材料带隙宽度可以为1.5eV-2.3eV，可包含一层或多层与中间串联层接触所需的缓冲层或匹配层，以减少中间串联层与上层电池单元间电阻或复合。
在叠层光伏器件，顶层电池单元的向光面还设置有减反射膜。该减反射膜用于降低叠层光伏器件的整体光学损失。该顶层电池单元为叠层光伏器件中，带隙最大的电池单元。参照图4、图5、图6或图7所示，该叠层光伏器件还可以包括顶层电极23和底层电极24。电极用于收集并导出载流子
下层电池单元还可以为同质结硅太阳电池，采用p型硅片，通过热扩散或离子注入的形式制备出n型层形成pn结，pn结位于下层电池单元的向光面。为了提高下层电池单元的光电转换效率，可在下层电池单元背光面制作钝化层及开孔的电学导出结构(PERC)，可在背光面进一步采用全面或局域重掺(PERT、PERL)，向光面可为抛光面，为减少光学损失，可在其向光面制作纳米光学结构或绒面结构。可在其向光面沉积氧化物隧穿钝化层及中间串联层。下层电池单元的向光面不沉积介电材料或减反射薄膜，以便于与中间串联进行电学接触。此处，下层电池单元向光面制作倒金字塔绒面结构，结构平均边长可以为500nm，平均边距5nm，结构深度250-500nm，倒金字塔结构可以采用金属离子辅助的各向异性刻蚀获得。
下层电池单元还可以为窄带隙薄膜太阳电池，吸收层材料可以为CIGS、非晶硅、CdTe、GaAs、钙钛矿等窄带隙或可调带隙材料。下层电池 单元为CIGS薄膜太阳电池，具备常规结构，衬底、钼背电极、CIGS吸收层、CdS缓冲层、ZnO窗口层、AZO透明导电薄膜，该下层电池单元具备较平整向光面，作为与中间串联层的接触，表面纵向粗糙度约20nm。
在本发明实施例中，叠层光伏器件中的电池单元中间串联层等可以参照前述实施例中的相关记载，且能达到相同或相似的有益效果，为了避免重复，此处不再赘述。
本发明实施例还提供一种叠层光伏器件的生产方法。该方法包括如下步骤：
步骤101，提供第一电池单元。
在本发明实施例中，该第一电池单元可以为上述带隙较窄的下层电池单元。
步骤102，在所述第一电池单元的受光面沉积任一所述的中间串联层。
步骤103，在所述中间串联层的受光面沉积第二电池单元；所述第二电池单元的带隙宽度大于所述第一电池单元的带隙宽度；所述中间串联层用于导电互联所述第一电池单元和所述第二电池单元。
可选的，上述步骤102可以包括：采用真空沉积、化学法、化学气相沉积、热丝化学气相沉积中的一种，沉积形成各个纳米导电柱；或，采用真空沉积、化学法、化学气相沉积、热丝化学气相沉积中的一种，沉积形成各个纳米导电单元和绝缘阻隔体。
具体的，采用真空沉积、化学法、化学气相沉积、热丝化学气相沉积中的一种，在下层电池单元的向光面，沉积形成多个纳米导电柱，以形成纵向导电层。或者，真空沉积、化学法、化学气相沉积、热丝化学气相沉积中的一种，在下层电池单元的向光面，沉积形成多个纳米导电单元和绝缘阻隔体。
例如，采用真空沉积、化学法、化学气相沉积、热丝化学气相沉积中的一种，在下层电池单元的向光面，同时沉积形成多个纳米导电单元和绝缘阻隔体，以形成纵向导电层。或者，采用真空沉积、化学法、化学气相沉积、热丝化学气相沉积中的一种，先在下层电池单元的向光面，沉积形成绝缘阻隔体，然后，采用真空沉积、化学法、化学气相沉积、热丝化学气相沉积中的一种，在绝缘阻隔体之间沉积形成多个纳米导电单元，以形成纵向导电层。在本发明实施例中，对绝缘阻隔体和纳米导电单元的沉积顺序，不作具体限定。
在本发明实施例中，真空沉积可以为：PECVD(Plasma Enhanced Chemical Vapor Deposition，等离子体增强化学气相沉积法)、LPCVD(Low Pressure Chemical Vapor Deposition，低压力化学气相沉积法)、PVD(Physical Vapor Deposition，物理气相沉积)等。热丝化学气相沉积为Hot Wire Chemical Vapor Deposition，即HWCVD。化学气相沉积为Chemical Vapor Deposition，即CVD。
如，针对本征非晶硅、氮化硅、碳化硅、氧化铝等绝缘阻隔体，可以基于化学法：溶胶-凝胶等液态处理工艺，采用先涂敷后固化的方案，可用于沉积有机硅、聚合物、环氧树脂、乙烯-醋酸乙烯共聚物等材料。
可选的，在下层电池单元的向光面，可以采用蒸镀沉积修饰膜，修饰膜可以为种子层点阵结构，如，种子材料可以为氧化锌ZnO，种子层点阵平均直径可以10nm，种子点平面间距200nm。蒸镀腔本底真空度不大于5×10-4Pa，蒸镀速率为0.1-0.5nm/s。
可以在种子层上采用气相沉积CVD(Chemical Vapor Deposition，化学气相沉积)生长ZnO纳米线，平均长度600nm，线径10-50nm，纳米线与纵向的夹角为0°。CVD法中，可以采用氩气作为载气，控制气流与源的输运速率，使ZnO生长速率约2-3nm/s或1-2nm/s。
再例如，可以采用LPCVD沉积绝缘阻隔体，如，绝缘阻隔体的材料为本征非晶硅，厚度填充并覆盖下层太阳电池倒金字塔结构与ZnO纳米线，沉积厚度600-800nm。可以使用氩气为载气，蒸镀腔本底真空不大于5×10-5Pa，系统气压100-1000Pa，沉积速率约10-20nm/min或5-10nm/min。沉积后使用离子刻蚀或化学刻刻蚀方式对表面进行平整化处理，刻蚀掉多余的绝缘阻隔体并暴露出ZnO纳米线与上层电池单元进行电学接触，表面粗糙度控制在纵向平均粗糙度不大于10nm。
再例如，可以采用溶胶-凝胶法沉积中间串联层，前驱体溶液中包含均匀分散的磁性银纳米线，纳米线平均线径10-20nm，平均长度50nm。前驱体溶液涂敷于下层电池单元表面后，在磁场中进行固化，固化后形成SiO2介孔薄膜，其中银纳米线获得一致的纵向排布并于AZO接触，平均角度与纵向的偏差不大于3°。随后用碱溶液刻蚀中间串联层，露出表面Ag纳米线，中间串联层厚度约40-50nm。
再例如，在下层电池单元的向光面，可以采用蒸镀沉积修饰膜，修饰膜为种子层点阵结构，种子材料为氧化钛点阵，种子层点阵平均直径 5nm，种子点密排。在种子层上水热法生长密排氧化钛纳米线，平均长度50nm，线径5-10nm，纳米线与纵向角度偏离不大于3°。水热法前驱体溶液中选用有机钛源，水热温度不超过200℃，采用中性环境进行结晶生长，生长速率约3-4nm/min。
在本发明实施例中，纳米导电柱、纳米导电单元、绝缘阻隔体、纵向导电层等的形状、尺寸、材料等，可以参照前述相关内容，为了避免重复，此处不再赘述。上述叠层光伏器件的中间串联层的生产方法同样能够达到上述类似的有益效果，为了避免重复，此处不再赘述。
第二电池单元可以采用非真空方式沉积。该第二电池单元可以为上述带隙较宽的上层电池单元。如，针对上述第二太阳能电池的沉积可以如下：
首先在上述上层电池单元的向光面旋涂纳米导电柱材料形成纵向导电层，纳米导电柱的平均厚度可以为50nm。然后在纵向导电层的向光面旋涂并固化钙钛矿材料，固化温度不超过150℃，钙钛矿材料厚度为500-1000nm；在钙钛矿吸收层表面沉积空穴传输层及TCO薄膜。或者，首先在上述中间串联层的向光面沉积空穴传输层材料，Spiro-OMeTAD，平均厚度为30nm；后旋涂并固化钙钛矿材料，固化温度不超过150℃，钙钛矿材料厚度为500-1000nm；在钙钛矿吸收层表面沉积电子传输层及TCO薄膜。
在本发明实施例中，该方法的第一电池单元、第二电池单元、中间串联层等可以参照前述实施例中的相关记载，且能达到相同或相似的有益效果，为了避免重复，此处不再赘述。
需要说明的是，对于方法实施例，为了简单描述，故将其都表述为一系列的动作组合，但是本领域技术人员应该知悉，本发明实施例并不受所描述的动作顺序的限制，因为依据本发明实施例，某些步骤可以采用其他顺序或者同时进行。其次，本领域技术人员也应该知悉，说明书中所描述的实施例均属于优选实施例，所涉及的动作并不一定都是本发明实施例所必须的。
本发明实施例中，关于中间串联层、叠层光伏器件及其生产方法，各个器件等均可以相互参照。
上面结合附图对本发明的实施例进行了描述，但是本发明并不局限于上述的具体实施方式，上述的具体实施方式仅仅是示意性的，而不是限制 性的，本领域的普通技术人员在本发明的启示下，在不脱离本发明宗旨和权利要求所保护的范围情况下，还可做出很多形式，这些均属于本发明的保护之内。

Claims (16)

  1. 一种叠层光伏器件的中间串联层，其特征在于，所述中间串联层具有透光性；
    所述中间串联层包括纵向导电层；
    所述纵向导电层由纵向生长的纳米导电柱构成；
    或，
    所述纵向导电层包括相互间隔分布的纳米导电单元、以及位于相邻的纳米导电单元之间的绝缘阻隔体；所述绝缘阻隔体在横向上绝缘各个所述纳米导电单元。
  2. 根据权利要求1所述的中间串联层，其特征在于，所述纳米导电柱为柱状晶体、纳米柱、纳米棒、纳米管中的一种；
    所述纳米导电柱的横向尺寸为0.5-500nm；
    所述纳米导电柱的材料选自：氧化物半导体、硒化物半导体、碳化物、碳、导电聚合物中的至少一种。
  3. 根据权利要求1所述的中间串联层，其特征在于，所述纳米导电柱与纵向的夹角小于或等于10°。
  4. 根据权利要求1所述的中间串联层，其特征在于，所述纳米导电单元的形状为：线状、柱状、锥状或棒状中的一种；
    所述纳米导电单元的横向尺寸为0.5-500nm；
    所述纳米导电单元的材料选自：金属、金属氧化物、金属硒化物、金属硫化物、碳、导电聚合物中的至少一种；
    所述绝缘阻隔体的材料选自：有机硅、无机硅、氧化物电介质、聚合物中的至少一种。
  5. 根据权利要求4所述的中间串联层，其特征在于，所述金属选自：金、银、铂、铝、铜、锡、钛中的至少一种；
    所述金属氧化物选自氧化锌、氧化锡、氧化钛、氧化钼、氧化铜、氧化钒、氧化铊、氧化铪、氧化镍、氧化钨、氧化铟、氧化镓、掺铟氧化锡、掺氟氧化锡、掺铝氧化锌、掺镓氧化锌中的至少一种。
  6. 根据权利要求1所述的中间串联层，其特征在于，所述纳米导电单元与纵向的夹角小于或等于10°。
  7. 根据权利要求1所述的中间串联层，其特征在于，所述中间串联层的向光面的平均粗糙度小于或等于100nm。
  8. 根据权利要求1所述的中间串联层，其特征在于，所述中间串联层还包括位于所述纵向导电层的背光面上的修饰膜；
    所述修饰膜的材料选自：具有催化作用的金属、金属氧化物、金属硒化物，碳、碳化物，所述修饰膜作为所述纳米导电柱或所述纳米导电单元的种子层；
    和/或，在所述纳米导电柱或所述纳米导电单元为低功函数材料的情况下，所述修饰膜的材料选自：电子选择性接触材料。
  9. 根据权利要求8所述的中间串联层，其特征在于，所述修饰膜的厚度为0.5-10nm；
    所述修饰膜为连续的一层，或，所述修饰膜由若干个点阵结构密布而成，所述点阵结构的横向尺寸为0.5-10nm。
  10. 根据权利要求8所述的中间串联层，其特征在于，所述电子选择性接触材料选自：富勒烯、石墨烯、石墨炔、钙、氟化锂、氟化镁中的至少一种。
  11. 根据权利要求1所述的中间串联层，其特征在于，所述中间串联层在500-1300nm波段的平均透过率大于或等于85％。
  12. 根据权利要求1所述的中间串联层，其特征在于，所述中间串联层的纵向尺寸为10-1000nm。
  13. 一种叠层光伏器件，其特征在于，包括：至少两个带隙不同的电池单元以及权利要求1至12中任一所述的中间串联层；
    各个所述电池单元按照吸收层带隙宽度能量由高到低的顺序从上到下依次叠放，所述中间串联层位于相邻的电池单元之间。
  14. 根据权利要求13所述的叠层光伏器件，其特征在于，
    下层电池单元与所述中间串联层接触的表面具有陷光结构；所述下层电池单元为位于所述中间串联层的背光面的电池单元。
  15. 一种叠层光伏器件的生产方法，其特征在于，包括：
    提供第一电池单元；
    在所述第一电池单元的受光面沉积权利要求1至12中任一所述的中间串联层；
    在所述中间串联层的受光面沉积第二电池单元；所述第二电池单元的带隙宽带大于所述第一电池单元的带隙宽度；所述中间串联层用于导电互联所述第一电池单元和所述第二电池单元。
  16. 根据权利要求15所述的方法，其特征在于，沉积中间串联层的步骤包括：
    采用真空沉积、化学法、化学气相沉积、热丝化学气相沉积中的一种，沉积形成各个纳米导电柱；
    或，采用真空沉积、化学法、化学气相沉积、热丝化学气相沉积中的一种，沉积形成各个纳米导电单元和绝缘阻隔体。
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