Composite electron transport layer, preparation method and application thereof

Abstract

The application provides a composite electron transport layer and a preparation method and application thereof, and the preparation method comprises the following steps: (1) providing an organic electron transport layer; (2) evaporating a metal element in a process atmosphere, and depositing a product formed by the reaction between the metal element and a gas in the process atmosphere on the surface of the organic electron transport layer to form an inorganic electron transport layer, thereby obtaining the composite electron transport layer. The inorganic electron transport layer is prepared by the evaporation method, damage of high-energy particles to a perovskite layer is avoided, the metal element is used as a raw material, the raw material is more easily obtained, and the production cost is effectively reduced. In addition, the construction of the organic / inorganic composite electron transport layer can greatly reduce the thickness of the organic layer, reduce the influence of the organic material on the stability of the battery, retain the advantages of the organic electron transport layer, and effectively improve the photoelectric conversion efficiency of the perovskite solar cell.

Description

Technical Field

[0001] This invention belongs to the field of solar cell technology, specifically relating to a composite electron transport layer, its preparation method, and its application. Background Technology

[0002] With rapid societal development, people's demand for energy is increasing. Fossil fuels are non-renewable energy sources; their reserves dwindle with continuous use and will eventually be exhausted. Therefore, the development and utilization of renewable energy sources is of great significance. Solar energy is an important component of the renewable energy field, possessing advantages such as abundant reserves, easy access, and no environmental pollution. Therefore, the development and utilization of solar energy is crucial and has received widespread attention worldwide.

[0003] In the current photovoltaic field, perovskite solar cells are the most cutting-edge new type of solar cell, characterized by high conversion efficiency, low manufacturing cost, and short manufacturing process. Achieving large-scale mass production of perovskite solar photovoltaic modules will be one of the important ways to achieve grid parity for photovoltaic power. Currently, perovskite solar cells still face some challenges in their industrialization process, such as the preparation of the electron transport layer in inverted perovskite cells. Currently, there are two main types of electron transport layers in inverted perovskite solar cells: one is a pure organic electron transport layer, and the other is a pure inorganic oxide electron transport layer. These two types of electron transport layers have the following shortcomings: (1) Pure organic electron transport layers require a thicker thickness, resulting in a large material consumption. At the same time, organic materials are expensive, leading to high manufacturing costs for batteries and modules; (2) Organic materials are highly unstable, affecting the stability of the module during subsequent power generation; (3) Pure inorganic oxide electron transport layers have high resistivity and poor bandgap matching with the preceding and following layers, resulting in low battery efficiency; (4) Inorganic oxide materials have high sublimation temperatures, making it difficult to deposit them using thermal evaporation. Therefore, magnetron sputtering deposition is often used. However, high-energy particles generated during magnetron sputtering continuously bombard the substrate, damaging the perovskite absorption layer and thus reducing battery efficiency.

[0004] Therefore, developing a new type of electron transport layer that can help improve battery efficiency is an urgent technical problem to be solved. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a composite electron transport layer, its preparation method, and its applications. This invention involves the thermal evaporation of a metallic element in a process atmosphere. An inorganic electron transport layer is deposited on the surface of an organic electron transport layer through the reaction of the metallic element and the process gas, thereby constructing an organic / inorganic composite electron transport layer. The use of thermal evaporation to prepare the inorganic electron transport layer avoids damage to the perovskite layer caused by high-energy particles. Furthermore, using a metallic element as the raw material makes the raw material more readily available and less expensive than compound targets, effectively reducing production costs. In addition, constructing an organic / inorganic composite electron transport layer can significantly reduce the thickness of the organic layer, mitigating the impact of organic materials on battery stability while retaining the advantages of the organic electron transport layer. This plays a crucial role in improving the efficiency of perovskite solar cells.

[0006] To achieve this objective, the present invention adopts the following technical solution:

[0007] In a first aspect, the present invention provides a method for preparing a composite electron transport layer, the method comprising the following steps:

[0008] (1) Provides an organic electron transport layer;

[0009] (2) The elemental metal is thermally evaporated in a process atmosphere, and the product formed by the reaction of the elemental metal with the gas in the process atmosphere is deposited on the surface of the organic electron transport layer to form an inorganic electron transport layer, thus obtaining the composite electron transport layer.

[0010] This invention prepares an inorganic electron transport layer by reacting a thermally evaporated elemental metal with a gas in the process atmosphere, and then deposits it on an organic electron transport layer. This avoids damage to the perovskite thin film caused by high-energy ions, which would lead to a decrease in battery performance. Furthermore, using elemental metal as a raw material reduces production costs. In addition, constructing an organic / inorganic composite electron transport layer can fully utilize the advantages of both, improving the carrier transport rate and thus achieving higher battery efficiency, demonstrating good industrialization potential.

[0011] In this invention, the preparation of the organic electron transport layer is not limited. For example, the organic electron transport layer can be prepared by evaporation, sputtering, or spin coating of the precursor solution.

[0012] In this invention, the type of organic electron transport layer is not limited. For example, the organic electron transport layer can be copper bath (BCP), C... 60 Or [6,6]-phenyl-C61-butyric acid isomethyl ester (PCBM), etc.

[0013] Preferably, the thickness of the organic electron transport layer is 5 to 50 nm, such as 5 nm, 10 nm, 15 nm, 20 nm, 25 nm, 30 nm, 35 nm, 40 nm, 45 nm or 50 nm, and more preferably 5 to 20 nm.

[0014] In this invention, if the organic electron transport layer is too thick, it consumes a lot of material, and organic materials are expensive, thus increasing the manufacturing cost of the battery. Furthermore, organic materials are relatively unstable, and excessive thickness can affect battery stability. Conversely, if the organic electron transport layer is too thin, it cannot adequately cover the preceding perovskite film. This allows the subsequent inorganic electron transport layer to directly contact the perovskite layer through the pores in the organic electron transport layer, increasing interface mismatch and reducing the electron transport layer's ability to extract electrons, thus affecting battery efficiency. Preferably, the metallic element includes any one or a combination of at least two of Nb, Ti, Ni, Sb, Sn, Zn, or In, with Sn being the most preferred.

[0015] Preferably, the gas flow rate in the process atmosphere is 10 to 100 sccm, for example, it can be 10 sccm, 20 sccm, 30 sccm, 40 sccm, 50 sccm, 60 sccm, 70 sccm, 80 sccm, 90 sccm or 100 sccm, etc., and preferably 30 to 70 sccm.

[0016] In this invention, when the gas flow rate in the process atmosphere is too small, i.e. below 10 sccm, it is difficult to fully react with the thermally evaporated metal element, resulting in an excessively high molar ratio of metal atoms in the deposited inorganic electron transport layer, which leads to enhanced recombination of charge carriers and reduced battery performance.

[0017] Preferably, the gas in the process atmosphere includes oxygen, and more preferably a mixture of oxygen and a protective gas, wherein the protective gas includes argon and / or nitrogen.

[0018] In this invention, a mixture of oxygen and protective gas is used, which allows for better control of the oxygen content in the cavity during the process and better regulation of the gas pressure in the cavity during the process.

[0019] Preferably, the volume ratio of oxygen to protective gas in the mixture is (7-11):1, for example, it can be 7:1, 8:1, 9:1, 10:1 or 11:1, etc.

[0020] Preferably, the inorganic electron transport layer comprises a metal oxide.

[0021] In this invention, the metal oxide is a precursor for the inorganic electron transport layer, obtained by reacting thermally evaporated elemental metal with a gas in the process atmosphere.

[0022] Preferably, the metal oxide includes any one of SnO2, TiO2, NiO, ZnO, Nb2O5, Sb2O3 or tin-doped indium oxide, with SnO2 being the most preferred.

[0023] In one embodiment, using SnO2 as an inorganic electron transport layer can effectively reduce the energy barrier between the perovskite layer and the electron transport layer interface, improve charge transport and reduce charge accumulation at the interface, thereby enhancing electron extraction capability.

[0024] Preferably, the temperature of the thermal evaporation chamber is 25-300°C, for example, it can be 25°C, 50°C, 75°C, 100°C, 125°C, 150°C, 175°C, 200°C, 225°C, 250°C, 275°C or 300°C, and more preferably 50-100°C.

[0025] In this invention, if the temperature of the cavity is too high during thermal evaporation, it will damage the perovskite absorber layer. If the temperature of the cavity is too low during thermal evaporation, the particle energy will be too low during the film formation process, resulting in poor film quality. Both of these will cause a decrease in battery efficiency.

[0026] Preferably, the background vacuum degree of the thermal evaporation is ≤5×10⁻⁶. -4 Pa, for example, could be 5 × 10 -5 Pa, 4×10 -4 Pa, 3×10 -4 Pa, 2×10 -4 Pa, 1×10 -4 Pa or 9×10 -5 Pa, etc.

[0027] Preferably, the evaporation rate of the thermal evaporation is For example, it could be or etc., preferably

[0028] As a preferred technical solution of the present invention, the preparation method includes the following steps:

[0029] (1) Deposition of an organic electron transport layer;

[0030] (2) In ≤5×10 -4 Gas with a flow rate of 10–100 sccm is introduced into the reaction chamber at pressure Pa, and... The thermal evaporation rate deposits an inorganic electron transport layer on the organic electron transport layer, and the cavity temperature during thermal evaporation is 25–300 °C.

[0031] In a second aspect, the present invention provides a composite electron transport layer prepared by the preparation method described in the first aspect, the composite electron transport layer comprising an organic electron transport layer and an inorganic electron transport layer located on the surface of the organic electron transport layer.

[0032] This invention uses a combination of organic and inorganic electron transport layers as the composite electron transport layer of perovskite solar cells. This can significantly reduce the thickness of the organic electron transport layer, thereby reducing the impact of organic materials on the stability of the module and lowering production costs. Furthermore, by leveraging the advantages of both, high-performance perovskite solar cells can be obtained.

[0033] Preferably, the thickness of the inorganic electron transport layer is 5 to 50 nm, such as 5 nm, 10 nm, 15 nm, 20 nm, 25 nm, 30 nm, 35 nm, 40 nm, 45 nm or 50 nm, and more preferably 10 to 30 nm.

[0034] Thirdly, the present invention provides a perovskite solar cell, the perovskite solar cell comprising the composite electron transport layer as described in the second aspect.

[0035] The numerical range described in this invention includes not only the point values ​​listed above, but also any point values ​​within the numerical ranges not listed above. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific point values ​​included in the range.

[0036] Compared with the prior art, the present invention has the following beneficial effects:

[0037] (1) The present invention uses a thermal evaporation process to prepare an inorganic electron transport layer, which avoids damage to the perovskite layer by high-energy particles and ensures that the perovskite solar cell can achieve higher efficiency.

[0038] (2) In the thermal evaporation process, the present invention uses elemental metals as raw materials, which makes the raw materials easier to obtain and the price is lower than that of compound targets, thus effectively reducing production costs.

[0039] (3) The present invention constructs an organic / inorganic composite electron transport layer, which can not only significantly reduce the thickness of the organic layer and effectively reduce the adverse effects of organic materials on battery stability, but also simultaneously utilize the advantages of organic and inorganic electron transport layers to improve the performance of perovskite solar cells. Attached Figure Description

[0040] Figure 1 This is a schematic diagram of the fabrication equipment for the composite electron transport layer provided in Embodiment 1 of the present invention.

[0041] Figure 2This is a schematic diagram of the structure of a perovskite solar cell provided in Application Example 1 of the present invention.

[0042] Among them, 1-conductive glass; 2-hole transport layer; 3-perovskite absorber layer; 4-organic electron transport layer; 5-inorganic electron transport layer; 6-back electrode.

[0043] Figure 3 This is a schematic diagram of the structure of the perovskite solar cell provided in Comparative Example 2 of the present invention.

[0044] Among them, 1-conductive glass; 2-hole transport layer; 3-perovskite absorber layer; 4-organic electron transport layer; 6-back electrode. Detailed Implementation

[0045] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0046] Example 1

[0047] This embodiment provides a method for preparing a composite electron transport layer, specifically including the following steps:

[0048] (1) Organic electron transport layer C 60 Preparation: at 1×10 -4 Pa will C 60 by The deposition rate was increased to 10 nm, and then the rate was increased to... Evaporation to 20 nm yields C 60 Electron transport layer;

[0049] (2) C described in step (1) 60 Depositing a SnO2 electron transport layer on the electron transport layer, first at 1×10 -4 Oxygen gas at a flow rate of 50 sccm is introduced into the reaction chamber at pressure Pa. After the pressure stabilizes, Thermal evaporation of metallic tin involves the reaction of metallic tin with oxygen to generate a SnO2 electron transport layer with a thickness of 20 nm. The temperature of the cavity during thermal evaporation is 50 °C.

[0050] Figure 1 The apparatus used to prepare composite electron transport layers is shown, wherein the organic electron transport layer is prepared by thermal evaporation, and the inorganic electron transport layer is prepared by thermal evaporation of a metallic element reacting with a gas.

[0051] Example 2

[0052] This embodiment provides a method for preparing a composite electron transport layer, specifically including the following steps:

[0053] (1) Fabrication of organic electron transport layer PCBM: in 5×10 -5 Pa will use PCBM with The deposition rate was increased to 5 nm, and then the rate was increased to... The PCBM electron transport layer was obtained by vapor deposition to 15nm.

[0054] (2) Deposit a TiO2 electron transport layer on the PCBM electron transport layer described in step (1), firstly on a 5×10 -5 Oxygen gas at a flow rate of 30 sccm is introduced into the reaction chamber at pressure Pa. After the pressure stabilizes, Metallic Ti is thermally evaporated, and the metallic Ti reacts with oxygen to form a TiO2 electron transport layer with a thickness of 10 nm. The temperature of the cavity during thermal evaporation is 80 °C.

[0055] Example 3

[0056] This embodiment provides a method for preparing a composite electron transport layer, specifically including the following steps:

[0057] (1) Fabrication of organic electron transport layer PCBM: in 8×10 -5 Pa will use PCBM with The deposition rate was increased to 5 nm, and then the rate was increased to... The PCBM electron transport layer was obtained by vapor deposition to 10 nm.

[0058] (2) Deposit a SnO2 electron transport layer on the PCBM electron transport layer described in step (1), first on an 8×10 -5 Oxygen gas at a flow rate of 70 sccm is introduced into the reaction chamber at pressure Pa. After the pressure stabilizes, it is then... Thermal evaporation of metallic tin involves the reaction of metallic tin with oxygen in a mixed gas to generate a SnO2 electron transport layer with a thickness of 30 nm. The temperature of the cavity during thermal evaporation is 100 °C.

[0059] Example 4

[0060] This embodiment provides a method for preparing a composite electron transport layer, specifically including the following steps:

[0061] (1) Organic electron transport layer C 60 Preparation of C 60 Dissolve in chlorobenzene to prepare a solution. Use a pipette to apply 20 μL of the solution to the sample to be coated each time, and turn on the spin coater to prepare C. 60 The film was spin-coated at a speed of 4000 r / min, and the resulting C 60 The thickness is approximately 15nm;

[0062] (2) C described in step (1)60 Depositing a SnO2 electron transport layer on the electron transport layer, first on a 2×10⁻⁶ layer... -4 Oxygen gas at a flow rate of 10 sccm is introduced into the reaction chamber at pressure Pa. After the pressure stabilizes, it is then... Metallic tin is thermally evaporated, and the metallic tin reacts with the mixed gas to form a SnO2 electron transport layer with a thickness of 5 nm. The thermal evaporation temperature is 25℃.

[0063] Example 5

[0064] This embodiment provides a method for preparing a composite electron transport layer, specifically including the following steps:

[0065] (1) Organic electron transport layer C 60 Preparation: Magnetron sputtering was employed. First, 300 sccm of argon gas was introduced into the sputtering chamber to ignite the target. Then, the gas flow rate was adjusted to 100 sccm, and the deposition rate was adjusted to... Deposition to 5 nm yielded C 60 Electron transport layer;

[0066] (2) C described in step (1) 60 Depositing a SnO2 electron transport layer on the electron transport layer, first at 5 × 10⁻⁶ Å. -4 Oxygen gas at a flow rate of 100 sccm is introduced into the reaction chamber at pressure Pa. After the pressure stabilizes, it is then... Thermal evaporation of metallic tin involves the reaction of metallic tin with oxygen to form a SnO2 electron transport layer with a thickness of 50 nm. The temperature of the cavity during thermal evaporation is 300 °C.

[0067] Example 6

[0068] This embodiment provides a method for preparing a composite electron transport layer, specifically including the following steps:

[0069] (1) Organic electron transport layer C 60 Preparation: at 5×10 -5 Pa will C 60 by The deposition rate was increased to 10 nm, and then the rate was increased to... Evaporation to 20 nm yields C 60 Electron transport layer;

[0070] (2) C described in step (1) 60 Depositing a SnO2 electron transport layer on the electron transport layer, first at 5 × 10⁻⁶ Å. -5 Oxygen gas at a flow rate of 10 sccm is introduced into the reaction chamber at pressure Pa. After the pressure stabilizes, it is then... Thermal evaporation of metallic tin involves the reaction of metallic tin with oxygen to generate a SnO2 electron transport layer with a thickness of 20 nm. The temperature of the cavity during thermal evaporation is 50 °C.

[0071] Example 7

[0072] This embodiment provides a method for preparing a composite electron transport layer, specifically including the following steps:

[0073] (1) Organic electron transport layer C 60 Preparation: at 5×10 -5 Pa will C 60 by The deposition rate was increased to 10 nm, and then the rate was increased to... Evaporation to 20 nm yields C 60 Electron transport layer;

[0074] (2) C described in step (1) 60 Depositing a SnO2 electron transport layer on the electron transport layer, first at 5 × 10⁻⁶ Å. -5 Oxygen gas at a flow rate of 30 sccm is introduced into the reaction chamber at pressure Pa. After the pressure stabilizes, Thermal evaporation of metallic tin involves the reaction of metallic tin with oxygen to generate a SnO2 electron transport layer with a thickness of 20 nm. The temperature of the cavity during thermal evaporation is 50 °C.

[0075] Example 8

[0076] This embodiment provides a method for preparing a composite electron transport layer, specifically including the following steps:

[0077] (1) Organic electron transport layer C 60 Preparation: at 5×10 -5 Pa will C 60 by The deposition rate was increased to 10 nm, and then the rate was increased to... C was obtained by vapor deposition to 50 nm. 60 Electron transport layer;

[0078] (2) C described in step (1) 60 Depositing a SnO2 electron transport layer on the electron transport layer, first at 5 × 10⁻⁶ Å. -5 Oxygen gas at a flow rate of 70 sccm is introduced into the reaction chamber at pressure Pa. After the pressure stabilizes, it is then... The thermal evaporation rate is such that metallic tin is thermally evaporated, and metallic tin reacts with oxygen to form a SnO2 electron transport layer with a thickness of 20 nm. The temperature of the cavity during thermal evaporation is 50 °C.

[0079] Example 9

[0080] The difference between this embodiment and Embodiment 1 is that, C60 The thickness of the electron transport layer is 3 nm.

[0081] The remaining preparation methods and parameters are consistent with those in Example 1.

[0082] Example 10

[0083] The difference between this embodiment and Embodiment 1 is that, C 60 The thickness of the electron transport layer is 52 nm.

[0084] The remaining preparation methods and parameters are consistent with those in Example 1.

[0085] Example 11

[0086] The difference between this embodiment and Embodiment 1 is that the oxygen flow rate is 5 sccm.

[0087] The remaining preparation methods and parameters are consistent with those in Example 1.

[0088] Example 12

[0089] The difference between this embodiment and Embodiment 1 is that the oxygen flow rate is 105 sccm.

[0090] The remaining preparation methods and parameters are consistent with those in Example 1.

[0091] Example 13

[0092] The difference between this embodiment and Embodiment 1 is that the gas introduced is a mixture of oxygen and argon with a volume ratio of 9:1.

[0093] The remaining preparation methods and parameters are consistent with those in Example 1.

[0094] Application Example 1

[0095] This application example provides a method for fabricating a perovskite solar cell, the specific steps of which are as follows:

[0096] (A) Preparation of hole transport layer (HTL): Tin-doped tin oxide (ITO) was selected as the conductive glass (TCO). The precursor solution of NiO was spin-coated on the surface of ITO at a speed of 3000 r / min for 40 s to obtain a hole transport layer NiO with a thickness of 30 nm.

[0097] (B) Preparation of perovskite absorber layer (PVSK): The MAPbI3 precursor solution was spin-coated onto the surface of the hole transport layer at a speed of 4000 r / min for 40 s to obtain a perovskite absorber layer with a thickness of 600 nm.

[0098] (C) Preparation of electron transport layer: A composite electron transport layer was prepared on the surface of PVSK using the preparation method of Example 1;

[0099] (D) Fabrication of the back electrode: Magnetron sputtering was used, with argon gas at 300 sccm introduced, and the target power density was 1.3 W / cm². 2 At a pressure of 0.3 Pa and a deposition rate of 5 nm / min, ITO / Cu / ITO was deposited as an electrode layer with a thickness of 200 nm.

[0100] Figure 2 The diagram shows the structure of the perovskite solar cell provided in this application example, which, in the order of deposition, consists of TCO, HTL, PVSK, composite electron transport layer (organic ETL / inorganic ETL), and back electrode.

[0101] Application Example 2

[0102] This application example provides a method for fabricating a perovskite solar cell, the specific steps of which are as follows:

[0103] (A) Preparation of HTL: Fluorine-doped tin oxide (FTO) was selected as TCO. The precursor solution of poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA) was spin-coated on the surface of FTO at a speed of 3000 r / min for 40 s to obtain a hole transport layer PTAA with a thickness of 40 nm.

[0104] (B) Preparation of PVSK: The MAPbI3 perovskite solution required for each coating was added by a blade coating method. The blade moving speed was 40 mm / min during the coating process, and a PVSK with a thickness of 800 nm was obtained.

[0105] (C) Preparation of electron transport layer: A composite electron transport layer was prepared on the surface of PVSK using the preparation method of Example 2;

[0106] (D) Preparation of back electrode: Ag was deposited as the electrode layer by thermal evaporation, with an evaporation current of approximately 120A. Evaporation rate to 10 nm, then at The vapor deposition is 90nm thick, with a thickness of 100nm.

[0107] Application Example 3

[0108] This application example provides a method for fabricating a perovskite solar cell, the specific steps of which are as follows:

[0109] (A) Preparation of HTL: FTO was selected as the TCO, and thermal evaporation was used with an evaporation current of about 200A to control the evaporation rate. MoO3 was deposited on the surface of FTO to obtain a hole transport layer MoO3 with a thickness of 15 nm.

[0110] (B) Preparation of PVSK: 50 μL of MAPbI3 perovskite solution was injected each time using screen printing, and the scraper moving at a speed of 50 mm / min to obtain PVSK with a thickness of 200 nm.

[0111] (C) Preparation of electron transport layer: A composite electron transport layer was prepared on the surface of PVSK using the preparation method of Example 3;

[0112] (D) Preparation of back electrode: Al was deposited as an electrode layer by thermal evaporation with a thickness of 50 nm.

[0113] Application Example 4

[0114] This application example provides a method for fabricating a perovskite solar cell, the specific steps of which are as follows:

[0115] (A) Preparation of HTL: ITO was selected as the TCO, and sputtering was used with argon gas at 150 sccm. The target power density was 0.5 W / cm³. 2 At an air pressure of 0.15 Pa and a velocity of 2 nm / min, PTAA was deposited on the surface of ITO to obtain a hole transport layer PTAA with a thickness of 50 nm.

[0116] (B) Preparation of PVSK: The solution was sprayed at a rate of 30 μL / min and the chamber temperature was maintained at 120 °C to obtain a MAPbI3 perovskite absorber layer with a thickness of 100 nm.

[0117] (C) Preparation of electron transport layer: A composite electron transport layer was prepared on the surface of PVSK using the preparation method of Example 4;

[0118] (D) Fabrication of the back electrode: ITO / Cu / ITO was deposited as the electrode by magnetron sputtering, with argon gas at 300 sccm and a target power density of 1.3 W / cm³. 2 At a pressure of 0.3 Pa and a deposition rate of 5 nm / min, ITO / Cu / ITO was deposited as an electrode layer with a thickness of 300 nm.

[0119] Application Example 5

[0120] This application example provides a method for fabricating a perovskite solar cell, the specific steps of which are as follows:

[0121] (A) Preparation of HTL: FTO was selected as the TCO. Chemical bath deposition method was used. First, poly(3-hexylthiophene-2,5-dimethyl) (P3HT) mother liquor was prepared. Then, the mother liquor was placed on a heating plate and heated to 80°C and kept at a constant temperature. The FTO glass substrate to be coated was placed in the mother liquor and P3HT was deposited on the surface of FTO. The deposition time was 60 min, and a hole transport layer P3HT with a thickness of 25 nm was obtained.

[0122] (B) Preparation of PVSK: The slit coating method is adopted. First, the perovskite solution required for coating is prepared. During the coating process, 50 μL of MAPbI3 perovskite solution is taken with a pipette and evenly dropped onto the roller. The roller moves forward in close contact with the surface of the sample to be coated. The moving speed is 20 mm / min, and a PVSK with a thickness of 1000 nm is obtained.

[0123] (C) Preparation of electron transport layer: A composite electron transport layer was prepared on the surface of PVSK using the preparation method of Example 5;

[0124] (D) Preparation of back electrode: Cu was deposited as the electrode layer by thermal evaporation, with an evaporation current of approximately 120A. Evaporation rate to 20 nm, then at The vapor deposition is 130nm thick, with a thickness of 150nm.

[0125] Application Example 6

[0126] The difference between this application example and application example 1 is that step (C) involves preparing a composite electron transport layer on the surface of PVSK using the preparation method of example 6.

[0127] The remaining preparation methods and parameters are consistent with those in Application Example 1.

[0128] Application Example 7

[0129] The difference between this application example and application example 1 is that step (C) involves preparing a composite electron transport layer on the surface of PVSK using the preparation method of example 7.

[0130] The remaining preparation methods and parameters are consistent with those in Application Example 1.

[0131] Application Example 8

[0132] The difference between this application example and application example 1 is that step (C) involves preparing a composite electron transport layer on the surface of PVSK using the preparation method of example 8.

[0133] The remaining preparation methods and parameters are consistent with those in Application Example 1.

[0134] Application Example 9

[0135] The difference between this application example and application example 1 is that step (C) involves preparing a composite electron transport layer on the surface of PVSK using the preparation method of example 9.

[0136] The remaining preparation methods and parameters are consistent with those in Application Example 1.

[0137] Application Example 10

[0138] The difference between this application example and application example 1 is that step (C) involves preparing a composite electron transport layer on the surface of PVSK using the preparation method of example 13.

[0139] The remaining preparation methods and parameters are consistent with those in Application Example 1.

[0140] Comparative Example 1

[0141] The difference between this comparative example and Example 1 is that the electron transport layer is only SnO2.

[0142] The remaining preparation methods and parameters are consistent with those in Example 1.

[0143] Comparative Example 2

[0144] The difference between this comparative example and Example 1 is that the electron transport layer is only C. 60 .

[0145] The remaining preparation methods and parameters are consistent with those in Example 1.

[0146] Comparative Example 3

[0147] The difference between this comparative example and Example 1 is that the SnO2 electron transport layer was prepared by magnetron sputtering, with a sputtering power density of 1.3 W / cm². 2 The deposition pressure was 0.5 Pa, the deposition oxygen content was 1%, and the film thickness was 20 nm.

[0148] The remaining preparation methods and parameters are consistent with those in Example 1.

[0149] Application Comparative Example 1

[0150] The difference between this comparative example and Application Example 1 is that the electron transport layer in step (C) does not contain C. 60 It is only SnO2.

[0151] The remaining preparation methods and parameters are consistent with those in Application Example 1.

[0152] Application Comparative Example 2

[0153] The difference between this comparative example and Application Example 1 is that the electron transport layer in step (C) contains no SnO2, only C. 60 .

[0154] The remaining preparation methods and parameters are consistent with those in Application Example 1.

[0155] Figure 3 The diagram shows the structure of the perovskite solar cell provided in the comparative example of this application, in which the deposition order is TCO, HTL, PVSK, organic ETL and back electrode.

[0156] Application Comparative Example 3

[0157] The difference between this comparative example and Application Example 1 is that the SnO2 electron transport layer was prepared by magnetron sputtering with a sputtering power density of 1.3 W / cm². 2 The deposition pressure was 0.5 Pa, the deposition oxygen content was 1%, and the film thickness was 20 nm.

[0158] The remaining preparation methods and parameters are consistent with those in Application Example 1.

[0159] Performance testing

[0160] Photovoltaic performance tests were conducted on the perovskite solar cells provided in corresponding use cases 1-10 and application comparison examples 1-3.

[0161] Test conditions: AM1.5, 1000W / m 2 25±2℃, relative humidity (RH): 18±2%.

[0162] The test results are shown in Table 1.

[0163] Table 1

[0164]

[0165]

[0166] analyze:

[0167] The comparison of battery data from various application examples shows that using SnO2 deposited via reaction with process gas as the second electron transport layer results in higher efficiency for integrated perovskite solar cells compared to second electron transport layers prepared by electron beam or magnetron sputtering methods. When the organic electron transport layer is too thin, it cannot adequately cover the perovskite film, causing the inorganic electron transport layer to directly contact the perovskite layer through the pores in the organic layer. This increases interface mismatch, weakens the electron transport layer's ability to extract electrons, and consequently affects battery efficiency, leading to a significant decrease in efficiency. Replacing the introduced process gas (oxygen) with an oxygen-argon mixture can further improve battery performance, and research has found the optimal oxygen-argon volume ratio to be 9:1. Application comparison examples 1-2 show that if the electron transport layer is only C... 60The layer may be only a SnO2 layer. The electron transport effect of a single electron transport layer is worse than that of a composite electron transport layer, so the efficiency of the battery will decrease significantly. As can be seen from Comparative Example 3, the battery obtained by preparing a SnO2 layer by magnetron sputtering is significantly less efficient than the method of the present invention. This is because high-energy particles damage the perovskite layer, thereby reducing the performance of the battery.

[0168] The applicant declares that the present invention is illustrated by the above embodiments, but the present invention is not limited to the above process steps, that is, it does not mean that the present invention must rely on the above process steps to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions of the raw materials used in the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for preparing a composite electron transport layer, characterized in that, The preparation method includes the following steps: (1) Provides an organic electron transport layer; (2) The elemental metal is thermally evaporated in a process atmosphere, and the product formed by the reaction of the elemental metal with the gas in the process atmosphere is deposited on the surface of the organic electron transport layer to form an inorganic electron transport layer, thereby obtaining the composite electron transport layer. The metallic element is any one or a combination of at least two of Ti, Ni, Nb, Sb, Sn, Zn or In; The gas in the process atmosphere includes oxygen; the gas flow rate in the process atmosphere is 10~100 sccm; the evaporation rate of the thermal evaporation is 0.1~1 Å / s.

2. The preparation method according to claim 1, characterized in that, The thickness of the organic electron transport layer is 5~50nm.

3. The preparation method according to claim 2, characterized in that, The thickness of the organic electron transport layer is 5~20nm.

4. The preparation method according to claim 1, characterized in that, The metallic element is Sn.

5. The preparation method according to claim 1, characterized in that, The gas flow rate in the process atmosphere is 30~70 sccm.

6. The preparation method according to claim 1, characterized in that, The gas in the process atmosphere is a mixture of oxygen and a protective gas, wherein the protective gas includes argon and / or nitrogen.

7. The preparation method according to claim 6, characterized in that, The volume ratio of oxygen to protective gas in the mixture is (7~11):

1.

8. The preparation method according to claim 1, characterized in that, The inorganic electron transport layer comprises a metal oxide; The metal oxide includes any one of SnO2, TiO2, NiO, ZnO, Nb2O5, Sb2O3, or tin-doped indium oxide.

9. The preparation method according to claim 8, characterized in that, The metal oxide is SnO2.

10. The preparation method according to claim 1, characterized in that, The temperature of the cavity for thermal evaporation is 25~300℃.

11. The preparation method according to claim 10, characterized in that, The temperature of the cavity for thermal evaporation is 50~100℃.

12. The preparation method according to claim 1, characterized in that, The background vacuum degree of the thermal evaporation is ≤5×10⁻⁶. - 4 Pa.

13. The preparation method according to claim 1, characterized in that, The evaporation rate of the thermal evaporation is 0.4~0.7 Å / s.

14. The preparation method according to any one of claims 1-13, characterized in that, The preparation method includes the following steps: (1) Deposition of an organic electron transport layer; (2) In ≤5×10 -4 Gas with a flow rate of 10~100 sccm is introduced into the reaction chamber at Pa, and an inorganic electron transport layer is deposited on the organic electron transport layer at a thermal evaporation rate of 0.1~1 Å / s. The chamber temperature during thermal evaporation is 25~300℃.

15. A composite electron transport layer prepared by the preparation method according to any one of claims 1-14, characterized in that, The composite electron transport layer includes an organic electron transport layer and an inorganic electron transport layer located on the surface of the organic electron transport layer.

16. The composite electronic transport layer according to claim 15, characterized in that, The thickness of the inorganic electron transport layer is 5~50nm.

17. The composite electronic transport layer according to claim 16, characterized in that, The thickness of the inorganic electron transport layer is 10~30nm.

18. A perovskite solar cell, characterized in that, The perovskite solar cell includes a composite electron transport layer as described in any one of claims 15-17.

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