Application of pyrimidine-based additive in perovskite solar cell

Abstract

The invention relates to an application of a pyrimidine-based additive in a perovskite solar cell. A pyrimidine derivative with moderate Lewis alkalinity is selected as the additive and forms a moderate and stable coordination intermediate with a lead iodide precursor, so that nucleation of alpha-phase formamidine lead iodide can be accelerated and defect generation can be inhibited; the method is suitable for planar formal and trans-structure devices, the photoelectric conversion efficiency of 25% or above is achieved in the formal structure and the trans-structure, and excellent stability is kept under the long-time operation and storage conditions. The invention provides an additive design principle based on pyrimidine molecules, and provides a theoretical basis and a technical path for development of high-performance and long-life perovskite photovoltaic devices.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of perovskite solar cells, in particular to a method for optimizing perovskite film crystallization and defect passivation by adding pyrimidine molecules to prepare perovskite films, and its application in different device structures. BACKGROUND

[0002] In recent years, with the growing demand for clean energy, sustainable energy resources, especially photovoltaic technology, have been widely welcomed. However, organic-inorganic halide perovskite solar cells, with their excellent photophysical properties, such as low exciton binding energy, high light absorption coefficient, long carrier diffusion length, ideal energy band gap, good energy band alignment with charge transport layer, high carrier mobility, and doping, etc., have achieved a photovoltaic conversion efficiency of more than 26% in just over a decade. And in the case of low production cost, it has achieved a photovoltaic conversion efficiency leap, highlighting the great potential of perovskite solar cells in future photovoltaic technology.

[0003] The device structure of perovskite solar cells has a decisive influence on the performance of perovskite solar cells. According to the path of light into the perovskite layer, perovskite solar cells can be divided into two main structures: formal structure and reverse structure. In the prior art, the film quality is often improved by introducing Lewis base additives, but it is only suitable for a single device structure (such as a planar formal structure or a planar reverse structure). Therefore, there is an urgent need for an additive strategy for perovskite solar cells of different structures to achieve universal high-efficiency perovskite devices under different structures. SUMMARY

[0004] To solve the above technical problems, the present application provides a preparation method of perovskite solar cells with pyrimidine additives, which realizes rapid alpha phase nucleation and ordered grain growth by introducing pyrimidine additives, significantly reduces the defect density of the film, and reduces non-radiative recombination. Therefore, the method exhibits high photoelectric conversion efficiency in the preparation of perovskite solar cell devices with pyrimidine additives.

[0005] The technical problem to be solved by the present application is to provide a preparation method of perovskite solar cells based on pyrimidine additives, which has good film-forming property, high repeatability, and strong universality, can effectively balance the carrier transport in perovskite solar cells, and obtain a solar cell with high photoelectric conversion efficiency, characterized in that:

[0006] 1. A preparation method of formal and reverse perovskite solar cells based on pyrimidine additives, characterized in that the preparation method is as follows:

[0007] (1) coating an electron transport layer material or a hole transport layer material on the transparent substrate layer with a conductive layer to obtain an electron transport layer or a hole transport layer;

[0008] (2) coating an ABX3 perovskite solution doped with a pyrimidine additive on the surface of the electron transport layer or the hole transport layer obtained in step (1) and performing annealing treatment to obtain a perovskite thin film;

[0009] (3) coating an organic electron transport layer or an organic hole transport layer material solution on the surface of the perovskite thin film obtained in step (2);

[0010] (4) vacuum evaporation of a metal electrode on the surface of the electron transport layer or the hole transport layer obtained in step (3) to obtain a perovskite solar cell;

[0011] 2. The transparent substrate layer with a conductive layer according to 1 includes any one or several of a glass substrate, an FTO glass substrate, an ITO glass substrate, a PEN substrate or a PET substrate;

[0012] 3. The electron transport layer material according to 1 includes any one or several of doped or undoped inorganic electron transport layer materials (such as TiO2, SnO2, ZnO, Zn2SnO4, Cs2CO3, BaTiO3, SrTiO3, MgTiO3, BaSnO3 or CdS) and doped or undoped organic electron transport layer materials (such as fullerene and derivatives, non-fullerene electron transport materials); the hole transport layer material includes doped or undoped organic hole transport materials (such as aniline, carbazole, phthalocyanine, phenothiazine, phenoxazine or thiophene materials) and doped or undoped inorganic hole transport materials (such as NiO, Cu2O, PbS, V2O5, MoO3, CuSCN, CuI, etc.);

[0013] 4. The perovskite layer material according to 1 is of the type ABX3, A includes any one or several of potassium ions (K + ), cesium ions (Cs + ), methylamine ions (CH3NH3 + ) and formamidine ions (NH2CH=NH2 + ); B includes any one or several of lead ions (Pb 2+ ), tin ions (Sn 2+ ) and germanium ions (Ge 2+ ); X includes any one or several of iodine ions (I - ), bromine ions (Br - ), chlorine ions (Cl - ) and fluorine ions (F - );

[0014] 5. The pyrimidine additive organic molecular material according to 1, including but not limited to 2-aminopyrimidine, 2-cyanopyrimidine, 2-mercapto pyrimidine and pyrimidine-2-carboxylic acid, and molecules based on one or several functional groups of pyrimidine derivatives;

[0015] 6. The solvent used in the organic electron transport layer or organic hole transport layer material solution according to 1 is benzene and ester solvent which does not dissolve the underlying perovskite film, including any one or several of chlorobenzene, toluene, xylene, benzene, dichlorobenzene, ethyl acetate, butyl acetate, isopropanol, n-butanol;

[0016] 7. The perovskite solar cell prepared based on the pyrimidine additive perovskite film according to 1.

[0017] The present application has the following beneficial effects:

[0018] 1) The additive engineering based on pyrimidine molecules in the present application prepares high-efficiency perovskite films. The perovskite films prepared by the preparation method realize rapid α-phase nucleation and ordered grain growth through the introduction of pyrimidine additives, and the preparation method is simple and has high repeatability, which can be realized in a general laboratory;

[0019] 2) The present application provides a general perovskite film preparation method based on additive engineering, which shows good universality in formal and inverse perovskite solar cells. The perovskite film prepared by the preparation method is applied to solar cells, which significantly reduces the defect density of the film and reduces non-radiative recombination. The same additive shows high efficiency and high stability in the formal and inverse structures. The device operating life is significantly prolonged, and has commercialization potential. BRIEF DESCRIPTION OF DRAWINGS

[0020] The accompanying drawings are included to provide a further understanding of the present application, and constitute a part of the specification, which together with the examples of the present application, serve to explain the present application, and do not constitute a limitation on the present application.

[0021] Figure 1 Pyrimidine molecule schematic diagram based on pyrimidine molecule additive;

[0022] Figure 2 Device structure schematic diagram of formal and inverse perovskite solar cells based on pyrimidine additive;

[0023] Figure 3 Current-voltage curve of perovskite solar cell device based on pyrimidine additive;

[0024] Figure 4 Stability of perovskite solar cell device based on pyrimidine additive. DETAILED DESCRIPTION

[0025] In order to make the objects, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the accompanying drawings and examples. It should be understood that "comprising" or "including" mentioned throughout the specification and claims is an open term, which should be interpreted as "including but not limited to". The specific examples described in the specification are only used to explain the present application and should not be used to limit the present application. The protection scope of the present application should be defined by the appended claims.

[0026] Example 1: Preparation method of formal perovskite solar cell based on imidazole additive

[0027] The preparation method is as follows:

[0028] The formal device using the imidazole additive described in the present application has the following device structure: FTO / tin dioxide (SnO2) / perovskite layer (FAPbI3) 0.95 (MAPbBr3) 0.05 / Au, and the specific preparation steps are as follows:

[0029] 1) Cleaning: first, clean the surface of the FTO glass substrate attached with dust and other pollutants with a detergent, then ultrasonically clean with 200 mL of 1% surfactant solution, water and ethanol respectively to remove organic pollutants, and the cleaned FTO glass substrate is blown dry with nitrogen, so as to obtain a transparent conductive substrate with clean surface required for the experiment, and then treated with ultraviolet-ozone for 20 min to ensure the surface is clean and clean;

[0030] 2) Preparation of electron transport layer of formal device structure: tin dioxide is deposited by chemical bath method, 140 μL of mercaptoacetic acid, 2.5 mL of HCl (37 wt%), 2.5 g of urea and 0.55 g of SnCl2·2H2O are dissolved in 200 mL of ice pure water and shaken well. After diluting the solution 5 times, the cleaned FTO is immersed in the solution, heated in a 90°C oven for 2 hours, then the substrate is taken out and ultrasonically cleaned with pure water for 5 minutes, this process is repeated twice, then ultrasonically cleaned with IPA for 5 minutes, blown dry, and annealed in air at 170°C for 1 hour to prepare the SnO2 layer;

[0031] 3) Preparation of formal perovskite layer of imidazole additive: FAI, PbI2, MACl, MABr and PbBr2 are mixed in DMF / DMSO (8:1 v / v) to prepare 1.5 mol / L methylamine lead bromide (FAPbI3) 0.95 (MAPbBr3) 0.05A perovskite precursor solution is prepared, and a perovskite layer is prepared on the electron transport layer by a spin-coating method, with a spin-coating speed of 1000 rpm for 10 s, followed by 5000 rpm for 60 s, and with ethyl acetate anti-solvent added in the last 10 s of spin-coating. Subsequently, the substrate is annealed on a hot stage at 100°C for 1 hour to obtain a perovskite thin film. The perovskite precursor solution is doped with a pyrimidine additive organic molecular material, and the pyrimidine additive organic molecular material is 2-aminopyrimidine, 2-cyanopyrimidine, 2-mercapto pyrimidine, and pyrimidine-2-carboxylic acid.

[0032] 4) Preparation of the hole transport layer of the formal device: 73 mg of Spiro-OMeTAD powder is weighed, 1 ml of chlorobenzene is added, and then 18 μl of Li-TFSI (520 mg / ml dissolved in acetonitrile) and 29 μl of FK209 (300 mg / ml dissolved in acetonitrile) and 30 μL of 4-tert-butylpyridine are added, and the mixture is stirred for 1 h to fully dissolve. A hole transport layer is prepared on the perovskite thin film by a spin-coating method, with a spin-coating speed of 3000 rpm for 30 s;

[0033] 5) Preparation of the electrode of the formal device: the substrate is placed in a vacuum evaporation chamber, and a gold electrode is evaporated onto the surface of the hole transport layer by a vacuum evaporation method to obtain a formal perovskite solar cell device of the pyrimidine additive.

[0034] Example 2: Preparation method of a trans perovskite solar cell based on a pyrimidine additive

[0035] The trans device of the pyrimidine additive described in the present application has the following device structure: ITO / hole transport layer (MeO-2PACz) / perovskite layer (FAPbI3) 0.95 (MAPbBr3) 0.05 / electron transport layer (PC 61 BM) / BCP / Ag, and the specific preparation steps are as follows:

[0036] 1) Cleaning: first, the surface of the ITO glass substrate is cleaned with a detergent to remove dust and other contaminants, and then 200 mL of 1% surfactant solution, water and ethanol are used for ultrasonic cleaning to remove organic contaminants, and the cleaned ITO glass substrate is blown dry with nitrogen to obtain a clean transparent conductive substrate required for the experiment, and then it is treated with ultraviolet-ozone for 20 min to ensure that the surface is clean and clean;

[0037] 2) Preparation of hole transport layer of trans device: 0.5 mg of [2-(3,6-dimethoxy-9H-carbazol-9-yl)ethyl] phosphonic acid (MeO-2PACz) powder was weighed, 1 ml of ethanol was added, and it was stirred for 2 hours to fully dissolve. The hole transport layer was prepared on the ITO substrate by spin coating at a speed of 3000 rpm for 30 s, and then the substrate was annealed on a hot stage at 100°C for 10 minutes;

[0038] 3) Preparation of trans perovskite layer of pyrimidine additive: 1.63 mol / L of methylamine lead bromide (FAPbI3) was prepared by mixing FAI, PbI2, MACl, MABr, and PbBr2 in DMF / DMSO (8:1 v / v); 0.95 (MAPbBr3) 0.05 The perovskite precursor solution was prepared on the electron transport layer by spin coating at a speed of 1000 rpm for 10 s, followed by 5000 rpm for 60 s, and ethyl acetate antisolvent was added dropwise during the last 10 s of spin coating. Then, the substrate was annealed on a hot stage at 100°C for 30 minutes to obtain a perovskite film. The pyrimidine additive organic molecular material, which is 2-aminopyrimidine, 2-cyanopyrimidine, 2-mercapto pyrimidine, and pyrimidine-2-carboxylic acid, was doped in the perovskite precursor solution.

[0039] 4) Preparation of electron transport layer of trans device: 20 mg of PC 61 BM powder was weighed, 1 ml of chlorobenzene was added, and it was stirred at 60°C for 1 hour to fully dissolve. 0.5 mg of BCP powder was weighed, 1 ml of isopropanol was added, and it was stirred for 3 hours to fully dissolve. The hole transport layer was prepared on the perovskite film by spin coating at a speed of 2000 rpm for 30 s for PC 61 BM and at a speed of 4000 rpm for 30 s for BCP. Then, the substrate was annealed on a hot stage at 70°C for 5 minutes;

[0040] 5) Preparation of electrode of trans device: the substrate was placed in a vacuum evaporation chamber, and a silver electrode was evaporated onto the surface of the electron transport layer by vacuum evaporation to obtain a pyrimidine additive trans perovskite solar cell device.

Claims

1. A method for preparing formal and trans-perovskite solar cells based on pyrimidine additives, characterized in that, The preparation method is as follows: (1) On a transparent substrate with a conductive layer, an electron transport layer material or a hole transport layer material is coated to obtain an electron transport layer or a hole transport layer. (2) Coat the surface of the electron transport layer or hole transport layer obtained in step (1) with an ABX3 perovskite solution doped with pyrimidine additive organic molecular material, and perform annealing treatment to obtain a perovskite film. (3) Coat the surface of the perovskite thin film obtained in step (2) with an organic electron transport layer or an organic hole transport layer material solution; (4) Vacuum evaporation of metal electrodes on the surface of the electron transport layer or hole transport layer obtained in step (3) to obtain a perovskite solar cell; The pyrimidine-based additive organic molecular material is 2-aminopyrimidine, 2-cyanopyrimidine, 2-mercaptopyrimidine, or pyrimidine-2-carboxylic acid; the solvent used in the organic electron transport layer or organic hole transport layer material solution is any one or more of chlorobenzene, toluene, xylene, benzene, dichlorobenzene, ethyl acetate, butyl acetate, isopropanol, and n-butanol, which do not dissolve the underlying perovskite film.

2. The preparation method according to claim 1, wherein the transparent substrate with the conductive layer comprises any one or more of a glass substrate, an FTO glass substrate, an ITO glass substrate, a PEN substrate, or a PET substrate.

3. The preparation method according to claim 1, wherein the electron transport layer material comprises any one or more of doped or undoped inorganic electron transport layer materials and doped or undoped organic electron transport layer materials; and the hole transport layer material comprises any one or more of doped or undoped organic hole transport materials and doped or undoped inorganic hole transport materials.

4. In the preparation method according to claim 1, A in the ABX3 perovskite includes formamidinium ions (NH2CH=NH2). + ), methylamine ions (CH3NH3) + ), cesium ions (Cs) + ), rubidium ions (Rb + ), potassium ions (K) + ), ammonium ions (NH4) + B includes any one or more of the following: lead ions (Pb). 2+ ), tin ions (Sn) 2+ germanium ions (Ge) 2+ X includes any one or more of the following: X includes iodide ions (I0). - ), bromide ions (Br) - ), chloride ions (Cl) - ) and fluoride ions (F - Any one or more of the following.

5. The perovskite solar cell prepared by the method for preparing a perovskite solar cell based on a pyrimidine additive according to claim 1.

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