Solar cell and preparation method thereof

Abstract

The invention provides a solar cell and a preparation method thereof, and belongs to the technical field of solar cells. The solar cell at least comprises a substrate layer, a first electrode layer, a first transmission layer, an active layer and a composite layer which are sequentially stacked from bottom to top, the first electrode layer comprises a first electrode material, the first transmission layer comprises a first carrier transmission material, and the active layer comprises a second carrier transmission material. The composite layer at least comprises a second electrode material and a second carrier transport material, one of the first carrier transport material and the second carrier transport material is a hole transport material, and the other carrier transport material is an electron transport material. The composite layer in the solar cell contains the electrode material and the carrier transport material, the charge transport efficiency is improved by combining the electrode layer and the transport layer, the interface defects of the electrode layer and the transport layer are reduced, and the photoelectric conversion efficiency of the cell is enhanced.

Description

Technical Field

[0001] The invention belongs to the technical field of solar cells, and in particular relates to a solar cell and a preparation method thereof. Background Art

[0002] Solar cells have been widely studied and applied in recent years because they can obtain clean and renewable energy. Transparent electrodes play a vital role in transparent solar cells. They not only need to have good conductivity and maintain high light transmittance, but also need to be careful not to damage the prepared transport layer and light absorption layer and form good contact with them. Traditional transparent electrode layers are usually prepared through multi-step processes such as physical vapor deposition (PVD) and solution method. These steps increase manufacturing costs and production time. There are often defects at the interface between the electrode layer and the transport layer, resulting in low charge transfer efficiency, thereby limiting the overall performance of the battery. Summary of the invention

[0003] In view of the above technical problems existing in the prior art, the present invention provides a solar cell and a preparation method thereof. The composite layer in the solar cell contains an electrode material and a carrier transport material, and the charge transfer efficiency is improved by combining the electrode layer with the transport layer, reducing the interface defects between the two, and enhancing the photoelectric conversion efficiency of the cell.

[0004] The technical solution adopted in the embodiment of the present invention is:

[0005] A solar cell, the solar cell comprising at least a substrate layer, a first electrode layer, a first transport layer, an active layer and a composite layer stacked in sequence from bottom to top, the first electrode layer comprising a first electrode material, the first transport layer comprising a first carrier transport material, the composite layer comprising at least a second electrode material and a second carrier transport material, one of the first carrier transport material and the second carrier transport material being a hole transport material, and the other being an electron transport material;

[0006] Or, the solar cell comprises at least a substrate layer, a composite layer, an active layer, a second transport layer and a second electrode layer stacked in sequence from bottom to top; the composite layer comprises at least a first electrode material and a first carrier transport material, the second transport layer comprises a second carrier transport material, the second electrode layer comprises a second electrode material, one of the first carrier transport material and the second carrier transport material is a hole transport material, and the other carrier transport material is an electron transport material;

[0007] Alternatively, the solar cell includes at least a substrate layer, a composite layer and an active layer, the composite layer includes a first composite layer and a second composite layer, the substrate layer, the first composite layer, the active layer and the second composite layer are stacked in sequence from bottom to top, the first composite layer includes at least a first electrode material and a first carrier transport material; the second composite layer includes at least a second electrode material and a second carrier transport material, one of the first carrier transport material and the second carrier transport material is a hole transport material, and the other carrier transport material is an electron transport material.

[0008] In some embodiments, the active layer includes at least one photoelectric conversion functional semiconductor material.

[0009] In some embodiments, the resistivity of the composite layer is lower than 30Ω / □, and the light transmittance of the composite layer in the visible light band is higher than 70%.

[0010] In some embodiments, the material of the base layer is a transparent material.

[0011] In some embodiments, the first electrode material and the second electrode material are both metal materials, metal oxides, or non-metal materials.

[0012] In some embodiments, the first carrier transport material and the second carrier transport material are metal oxides or organic semiconductor materials.

[0013] In some embodiments, the electrode material in the composite layer is at least any one of indium tin oxide, fluorine-doped tin oxide, transparent conductive oxide, silver nanowires, aluminum-doped zinc oxide, carbon nanotubes, graphene and conductive polymers;

[0014] The carrier material in the composite layer is at least any one of zinc oxide, tin oxide, barium titanate, fluorine-doped tin oxide, poly (3,4-ethylenedioxythiophene): polystyrene sulfonate, and poly (chlorotrifluoroethylene).

[0015] A method for preparing a solar cell, the method comprising:

[0016] Provides a base layer;

[0017] Depositing a first electrode layer on the base layer, wherein the first electrode layer comprises a first electrode material;

[0018] Depositing a first transport layer on the first electrode layer, wherein the first transport layer comprises a first carrier transport material;

[0019] depositing an active layer on the first transport layer;

[0020] depositing a composite layer on the active layer, the composite layer comprising a second carrier transport material and a second electrode material;

[0021] or,

[0022] Provides a base layer;

[0023] Depositing a composite layer on the base layer, wherein the composite layer includes a first carrier transport material and a first electrode material;

[0024] depositing an active layer on the composite layer;

[0025] Depositing a second transport layer on the active layer, wherein the second transport layer comprises a second carrier transport material;

[0026] depositing a second electrode layer on the second transmission layer, wherein the second electrode layer comprises a second electrode material;

[0027] or,

[0028] Provides a base layer;

[0029] Depositing a first composite layer on the base layer, wherein the first composite layer includes a first carrier transport material and a first electrode material;

[0030] depositing an active layer on the first composite layer;

[0031] A second composite layer is deposited on the active layer, wherein the second composite layer includes a second carrier transport material and a second electrode material.

[0032] In some embodiments, the composite layer is deposited on the active layer or the substrate layer by a coating process.

[0033] In some embodiments, the first carrier transport material and the first electrode material in the composite layer are formulated in the same solution;

[0034] Alternatively, the second carrier transport material and the second electrode material in the composite layer are prepared in the same solution.

[0035] Compared with the prior art, the embodiments of the present invention have the following beneficial effects:

[0036] The composite layer in the solar cell of the embodiment of the present invention contains an electrode material and a carrier transport material. By combining the electrode layer with the transport layer, not only the solar cell assembly process is simplified and the production steps are reduced, but also the charge transfer efficiency is improved, the interface defects of the two are reduced, and the photoelectric conversion efficiency of the battery is enhanced. And because the interface defects and charge recombination centers are reduced, the stability of the battery stored in the air is significantly improved, and the long-term service life of the battery is increased.

[0037] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In the drawings, which are not necessarily drawn to scale, the same reference numerals may describe similar parts in different views. The same reference numerals with letter suffixes or different letter suffixes may represent different instances of similar parts. The accompanying drawings generally illustrate various embodiments by way of example and not limitation, and together with the specification and claims, are used to illustrate the disclosed embodiments. When appropriate, the same reference numerals are used throughout the drawings to refer to the same or similar parts. Such embodiments are illustrative and are not intended to be exhaustive or exclusive embodiments of the present apparatus or method.

[0039] Figure 1 is a cross-sectional view of a solar cell according to a first embodiment of the present invention;

[0040] Figure 2 is a cross-sectional view of a solar cell according to a second embodiment of the present invention;

[0041] Figure 3 is a cross-sectional view of a solar cell according to a third embodiment of the present invention;

[0042] Figure 4 This is a flow chart of a method for preparing a solar cell according to a first embodiment of the present invention;

[0043] Figure 5 This is a flow chart of a method for preparing a solar cell according to a second embodiment of the present invention;

[0044] Figure 6 This is a flow chart of a method for preparing a solar cell according to Embodiment 3 of the present invention;

[0045] Figure 7 This is a schematic diagram of the square resistance and ideal factor of a solar cell when the addition amount is 3 mg / ml according to an embodiment of the present invention;

[0046] Figure 8 Schematic diagram of the square resistance of a solar cell according to an embodiment of the present invention;

[0047] Fig. 9 This is a comparison diagram of the efficiency of the solar cell of the embodiment of the present invention compared with the electrode without adding PDINO;

[0048] Fig.10 The photoelectric conversion efficiency and fill factor diagram of the solar cell according to the embodiment of the present invention;

[0049] Fig.11 The solar cell with an active area of ​​12 cm was prepared for the embodiment of the present invention. 2Efficiency diagram of solar cells;

[0050] Fig.12 This is a stability comparison diagram of the solar cell according to the embodiment of the present invention compared with the traditional ZnO / AgNWs electrode.

[0051] In the figure: 1, substrate layer; 2, composite layer; 21, first composite layer; 22, second composite layer; 3, first electrode layer; 4, first transmission layer; 5, active layer; 6, second transmission layer; 7, second electrode layer. DETAILED DESCRIPTION

[0052] In order to enable those skilled in the art to better understand the technical solutions of the embodiments of the present invention, the present invention is described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0053] Unless otherwise defined, the technical terms or scientific terms used in the present disclosure should be understood by people with ordinary skills in the field to which the present disclosure belongs. The "first", "second" and similar words used in the present disclosure do not indicate any order, quantity or importance, but are only used to distinguish different components. "Include" or "comprise" and similar words mean that the elements or objects appearing before the word cover the elements or objects listed after the word and their equivalents, without excluding other elements or objects. "Connect" or "connected" and similar words are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0054] like Figure 1 As shown, an embodiment of the present invention provides a solar cell, which at least includes a substrate layer 1, a first electrode layer 3, a first transmission layer 4, an active layer 5 and a composite layer 2 stacked in sequence from bottom to top.

[0055] The first electrode layer 3 includes a first electrode material, the first transport layer 4 includes a first carrier transport material, and the composite layer 2 includes at least a second electrode material and a second carrier transport material. The carrier is a current carrier, and there are two types of carriers in a semiconductor, namely, electrons and holes. Therefore, the first carrier transport material can be an electron transport material, and the second carrier transport material can be a hole transport material; or, the first carrier transport material can be a hole transport material, and the second carrier can be an electron transport material.

[0056] or, as Figure 2As shown, the solar cell of the embodiment of the present invention comprises at least a substrate layer 1, a composite layer 2, an active layer 5, a second transmission layer 6 and a second electrode layer 7 which are stacked in sequence from bottom to top.

[0057] The composite layer 2 includes at least a first electrode material and a first carrier transport material, the second electrode layer 7 includes a second electrode material, and the second transport layer 6 includes a second carrier transport material. The carrier is a current carrier, and there are two types of carriers in a semiconductor, namely, electrons and holes. Therefore, the first carrier transport material can be an electron transport material, and the second carrier transport material can be a hole transport material; or, the first carrier transport material can be a hole transport material, and the second carrier can be an electron transport material.

[0058] or, as Figure 3 As shown, the solar cell of the embodiment of the present invention at least comprises a substrate layer 1, a composite layer 2 and an active layer 5. The composite layer 2 comprises a first composite layer 21 and a second composite layer 22.

[0059] The substrate layer 1, the first composite layer 21, the active layer 5 and the second composite layer 22 are stacked in sequence from bottom to top. The first composite layer 21 includes at least a first electrode material and a first carrier transport material; the second composite layer 22 includes at least a second electrode material and a second carrier transport material. The carrier is a current carrier, and there are two types of carriers in a semiconductor, namely electrons and holes. Therefore, the first carrier transport material can be an electron transport material, and the second carrier transport material can be a hole transport material; or, the first carrier transport material can be a hole transport material, and the second carrier can be an electron transport material.

[0060] The composite layer 2 in the solar cell of the embodiment of the present invention contains an electrode material and a carrier transport material. By combining the electrode layer with the transport layer, not only the solar cell assembly process is simplified and the production steps are reduced, but also the charge transfer efficiency is improved, the interface defects of the two are reduced, and the photoelectric conversion efficiency of the battery is enhanced. And because the interface defects and charge recombination centers are reduced, the stability of the battery stored in the air is significantly improved, and the long-term service life of the battery is increased.

[0061] In some embodiments, the active layer 5 is one of the most important parts of the solar cell, and its function is to absorb sunlight and generate current. Its performance directly affects the photoelectric conversion efficiency of the solar cell.

[0062] The active layer 5 includes at least one semiconductor material with photoelectric conversion function. The semiconductor material can be selected from any one of perovskite material, polymer material, fullerene material or their derivatives.

[0063] Furthermore, the semiconductor material is a combination of a donor material and an acceptor material, wherein the donor material includes at least chemical molecules such as PM6, P3HT, PCE10 and D18, and the acceptor material includes chemical molecules such as Y6, BTP-eC9, IEICO-4F, ITIC, L8-BO, PCBM, PC61BM and PC71BM.

[0064] In some embodiments, the resistivity of the composite layer 2 in the solar cell is lower than 30Ω / □, and the light transmittance of the composite layer 2 in the visible light band is higher than 70%.

[0065] In some embodiments, the material of the base layer 1 in the solar cell may be a transparent material, including glass, plastic film, polyethylene terephthalate (PET), polyetheretherketone (PEEK), polyimide (PI), polyethylene naphthalate (PEN) and other transparent materials suitable for solar cells.

[0066] In some embodiments, the first electrode material and the second electrode material are both metal materials, metal oxides, or non-metal materials, and may be any one of indium tin oxide (ITO), fluorine-doped tin oxide (FTO), aluminum-doped zinc oxide (AZO), silver nanowires (AgNW), conductive polymers (such as PEDOT), metals or their alloys (such as Ag, Cu), etc.

[0067] In some embodiments, the first carrier transport material and the second carrier material may be metal oxides or organic semiconductor materials.

[0068] For example, the first carrier transport material and the second carrier material can be any one of zinc oxide (ZnO), tin oxide (SnO2), barium titanate (BaTiO3), fluorine-doped tin oxide (FTO), poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate (PEDOT:PSS), polytrifluorochloroethylene (PFCB), PDINO and PDINN.

[0069] In some embodiments, the electrode material in the composite layer 2 is at least any one of indium tin oxide, fluorine-doped tin oxide, transparent conductive oxide, silver nanowires, aluminum-doped zinc oxide, carbon nanotubes, graphene, and conductive polymers;

[0070] The carrier material in the composite layer 2 is at least any one of zinc oxide (ZnO), tin oxide (SnO2), barium titanate (BaTiO3), fluorine-doped tin oxide (FTO), poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate (PEDOT:PSS), polytrifluorochloroethylene (PFCB), PDINO and PDINN.

[0071] The present invention provides a method for preparing a solar cell. Figure 4 As shown, the preparation method comprises the following process:

[0072] Step S100: providing a base layer 1.

[0073] In step S100, the substrate layer 1 may be a transparent material, so as to allow sunlight to pass through, so as to absorb sunlight to the maximum extent and convert it into electrical energy. The material of the substrate layer 1 may be any one of glass, plastic film, polyester (PET), polyimide (PI), etc.

[0074] Step S200: depositing a first electrode layer 3 on the substrate layer 1, wherein the first electrode layer 3 comprises a first electrode material.

[0075] In step S200, the first electrode material is a metal material selected from any one of indium tin oxide (ITO), fluorine-doped tin oxide (FTO), aluminum-doped zinc oxide (AZO), and silver nanowire (AgNW).

[0076] Step S300: depositing a first transport layer 4 on the first electrode layer 3, wherein the first transport layer 4 comprises a first carrier transport material.

[0077] Step S400: depositing an active layer 5 on the first transmission layer 4.

[0078] In step S400 , the active layer 5 includes an organic semiconductor material, which may be selected from any one of a perovskite material, a polymer material, a fullerene material or a derivative thereof.

[0079] Step S500: depositing a composite layer 2 on the active layer 5, wherein the composite layer 2 includes a second carrier transport material and a second electrode material.

[0080] In step S500, the second carrier transport material and the second electrode material can be configured by the same solution method and coated on the active layer 5 together by a coating process, thereby reducing the process steps. The coating process can include spin coating, blade coating, spray coating, printing or dipping.

[0081] Or, if Figure 5 As shown, the preparation method comprises the following process:

[0082] Step S100: providing a base layer 1.

[0083] In step S100, the substrate layer 1 may be a transparent material, so as to allow sunlight to pass through, so as to absorb sunlight to the maximum extent and convert it into electrical energy. The material of the substrate layer 1 may be any one of glass, plastic film, polyester (PET), polyimide (PI), etc.

[0084] Step S200: depositing a composite layer 2 on the base layer 1, wherein the composite layer 2 includes a first carrier transport material and a first electrode material.

[0085] In step 200, the first carrier transport material and the first electrode material in the composite layer 2 can be prepared from the same solution and coated on the base layer 1 together through a coating process. The coating process can include spin coating, blade coating, spray coating, printing or dipping.

[0086] Step S300: depositing an active layer 5 on the composite layer 2.

[0087] In step S300 , the active layer 5 includes an organic semiconductor material, which may be selected from any one of a perovskite material, a polymer material, a fullerene material or a derivative thereof.

[0088] Step S400: depositing a second transport layer 6 on the active layer 5, wherein the second transport layer 6 comprises a second carrier transport material.

[0089] Step S500: depositing a second electrode layer 7 on the second transmission layer 6, wherein the second electrode layer 7 comprises a second electrode material.

[0090] In the step S500, the second electrode material is a metal material, which may be any one of indium tin oxide (ITO), fluorine-doped tin oxide (FTO), aluminum-doped zinc oxide (AZO), silver nanowire (AgNW), etc.

[0091] or, as Figure 6 As shown, the preparation method comprises the following process:

[0092] Step S100: providing a base layer 1.

[0093] In step S100, the substrate layer 1 may be a transparent material, so as to allow sunlight to pass through, so as to absorb sunlight to the maximum extent and convert it into electrical energy. The material of the substrate layer 1 may be any one of glass, plastic film, polyester (PET), polyimide (PI), etc.

[0094] Step S200: depositing a first composite layer 21 on the substrate layer 1, wherein the first composite layer 21 includes a first carrier transport material and a first electrode material.

[0095] In the step S200, the first carrier transport material and the first electrode material can be prepared from the same solution and coated on the base layer 1 together through a coating process. The coating process can include spin coating, blade coating, spray coating, printing or dipping.

[0096] Step S300: depositing an active layer 5 on the first composite layer 21.

[0097] Step S400: depositing a second composite layer 22 on the active layer 5, wherein the second composite layer 22 includes a second carrier transport material and a second electrode material.

[0098] In step 400, the second carrier transport material and the second electrode material may be prepared from the same solution and coated together on the active layer 5 by a coating process. The coating process may include spin coating, blade coating, spray coating, printing or dipping.

[0099] It should be noted that, in this embodiment, the first carrier may be an electron transport material, and the second carrier may be a hole transport material; or, the first carrier may be a hole transport material, and the second carrier may be an electron transport material.

[0100] In the method for preparing a solar cell according to an embodiment of the present invention, the composite layer 2 contains the second carrier and the second electrode material, and the composite layer 2 is directly deposited on the active layer 5 to act as the second electrode, thereby overcoming the complexity and performance loss caused by the multi-step process in the prior art. This method not only simplifies the process flow and reduces the production steps, but also significantly improves the photoelectric performance and stability of the device.

[0101] Below we will use a specific implementation example:

[0102] PDINO methanol solutions (i.e., electrode materials) with different concentrations were added to the IPA dispersion of silver nanowires (i.e., carrier transport materials). The mixed solution was prepared into a composite electrode by a one-step spin coating method. The square resistance of the composite electrode was measured, and the ideal factor (Figure of Merit, FoM) of the composite electrode was calculated, as shown in FIG. Figure 7 As shown in the figure, when the addition amount is 3mg / ml, the square resistance of the composite electrode is less than 30Ω / □, and the ideal factor is higher than 30, which meets the standard of transparent electrode application in industry. At the same time, the square resistance stability of the composite electrode in air was measured. Compared with the electrode without PDINO, the square resistance stability of the composite electrode in air has been greatly improved, as shown in the figure. Figure 8 shown.

[0103] The solar cells prepared using composite electrodes with the structure of Glass / ITO / PEDOT:PSS / PM6:Y6 / PDINO:AgNWs have achieved good results. Fig. 9 Compared with the electrode without PDINO, the efficiency is increased by more than five times.

[0104] like Fig.10As shown in the figure, the composite electrode was further optimized to achieve the highest efficiency among transparent organic solar cells using solution-based transparent electrodes, with a photoelectric conversion efficiency of 13.2% and a fill factor of 77.4%. Fig.11 As shown, an active area of ​​12 cm 2 The large-area components have an efficiency of 9.64%.

[0105] In addition, if Fig.12 As shown, the stability of the encapsulated battery in air was monitored, and the results showed that the battery based on the composite electrode exhibited good stability compared with the traditional ZnO / AgNWs electrode.

[0106] The above embodiments are only exemplary embodiments of the present invention and are not intended to limit the present invention. The protection scope of the present invention is defined by the claims. Those skilled in the art may make various modifications or equivalent substitutions to the present invention within the essence and protection scope of the present invention, and such modifications or equivalent substitutions shall also be deemed to fall within the protection scope of the present invention.

Claims

1. A solar cell, characterized in that: The solar cell comprises at least a substrate layer, a first electrode layer, a first transport layer, an active layer and a composite layer stacked in sequence from bottom to top, the first electrode layer comprises a first electrode material, the first transport layer comprises a first carrier transport material, the composite layer comprises at least a second electrode material and a second carrier transport material, one of the first carrier transport material and the second carrier transport material is a hole transport material, and the other carrier transport material is an electron transport material; Or, the solar cell comprises at least a substrate layer, a composite layer, an active layer, a second transport layer and a second electrode layer stacked in sequence from bottom to top; the composite layer comprises at least a first electrode material and a first carrier transport material, the second transport layer comprises a second carrier transport material, the second electrode layer comprises a second electrode material, one of the first carrier transport material and the second carrier transport material is a hole transport material, and the other carrier transport material is an electron transport material; Alternatively, the solar cell includes at least a substrate layer, a composite layer and an active layer, the composite layer includes a first composite layer and a second composite layer, the substrate layer, the first composite layer, the active layer and the second composite layer are stacked in sequence from bottom to top, the first composite layer includes at least a first electrode material and a first carrier transport material; the second composite layer includes at least a second electrode material and a second carrier transport material, one of the first carrier transport material and the second carrier transport material is a hole transport material, and the other carrier transport material is an electron transport material.

2. A solar cell according to claim 1, characterized in that: The active layer includes at least one photoelectric conversion functional semiconductor material.

3. A solar cell according to claim 1, characterized in that: The resistivity of the composite layer is lower than 30Ω / □, and the light transmittance of the composite layer is higher than 70% in the visible light band.

4. A solar cell according to claim 1, characterized in that: The material of the base layer is a transparent material.

5. A solar cell according to claim 1, characterized in that: The first electrode material and the second electrode material are both metal materials, metal oxides, or non-metallic conductive materials.

6. A solar cell according to claim 1, characterized in that: The first carrier transport material and the second carrier transport material are metal oxides or organic semiconductor materials.

7. A solar cell according to claim 1, characterized in that: The electrode material in the composite layer is at least any one of indium tin oxide, fluorine-doped tin oxide, transparent conductive oxide, silver nanowire, aluminum-doped zinc oxide, carbon nanotube, graphene and conductive polymer; The carrier material in the composite layer is at least any one of zinc oxide, tin oxide, barium titanate, fluorine-doped tin oxide, poly (3,4-ethylenedioxythiophene): polystyrene sulfonate, and poly (chlorotrifluoroethylene).

8. A method for preparing a solar cell, characterized in that: include: Provides a base layer; Depositing a first electrode layer on the base layer, wherein the first electrode layer comprises a first electrode material; Depositing a first transport layer on the first electrode layer, wherein the first transport layer comprises a first carrier transport material; depositing an active layer on the first transport layer; depositing a composite layer on the active layer, the composite layer comprising a second carrier transport material and a second electrode material; or, Provides a base layer; Depositing a composite layer on the base layer, wherein the composite layer includes a first carrier transport material and a first electrode material; depositing an active layer on the composite layer; Depositing a second transport layer on the active layer, wherein the second transport layer comprises a second carrier transport material; depositing a second electrode layer on the second transmission layer, wherein the second electrode layer comprises a second electrode material; or, Provides a base layer; Depositing a first composite layer on the base layer, wherein the first composite layer includes a first carrier transport material and a first electrode material; depositing an active layer on the first composite layer; A second composite layer is deposited on the active layer, wherein the second composite layer includes a second carrier transport material and a second electrode material.

9. A method for preparing a solar cell according to claim 8, characterized in that: The composite layer is deposited on the active layer or the substrate layer by a coating process.

10. The method for preparing a solar cell according to claim 8, characterized in that: The first carrier transport material and the first electrode material in the composite layer are prepared in the same solution; Alternatively, the second carrier transport material and the second electrode material in the composite layer are prepared in the same solution.

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