High-efficiency perovskite solar cell and printing preparation method thereof

Abstract

The application discloses a kind of high-efficiency perovskite solar cells and printing preparation method thereof, belong to perovskite solar cell technical field.The method in FA 1‑x‑y C Sx MA y PbI 3‑x Br x (x is 0.05, y is 0.02-0.06) perovskite absorption layer preparation process is introduced in part DMAPbI3 Intermediate, effectively control the growth process of perovskite crystal, significantly increase the grain size of perovskite film, and realize in-situ passivation of film defect.This series of optimization measures, finally improves the FA 1‑x‑y C Sx MA y PbI 3‑x Br x filling factor and photoelectric conversion efficiency of perovskite solar cell prepared by scraping and coating in atmospheric environment.

Description

Technical Field

[0001] This invention belongs to the field of new energy materials technology, specifically relating to a high-efficiency perovskite solar cell and its printing preparation method. Background Technology

[0002] Perovskite solar cells (PSCs) have attracted widespread attention in the new energy field due to their high photoelectric conversion efficiency (PCE) and low-cost manufacturing potential. However, current FAs prepared by the blade coating method... 1-x-y C Sx MA y PbI 3-x Br x The photoelectric conversion efficiency of perovskite solar cells is still insufficient compared to traditional spin-coating methods. In roll-to-roll production, the cell's PCE becomes a key factor determining the cost of power generation, with improving the fill factor (FF) being particularly important.

[0003] According to the Shockley-Queisser (SQ) limit theory, for a specific bandgap, the performance parameters of a PSC have a theoretical upper limit. Currently, the FA coating... 1-x-y C Sx MA y PbI 3-x Br x After the formation of perovskite solar cells, the performance parameters of perovskite solar cells have not yet reached the SQ limit, especially the FF has a large room for improvement, but there is little research on this. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a high-efficiency perovskite solar cell and its printing preparation method, thereby addressing the issue that the performance of perovskite solar cells still has significant room for improvement in the existing technology. This method introduces a DMAPbI3 intermediate during the perovskite crystallization process to regulate perovskite crystal growth, effectively increasing the grain size of the perovskite thin film and reducing defects, thus improving the efficiency of FA (fiberglass reinforced plastic) fabrication under atmospheric conditions. 1-x-y C Sx MA y PbI 3-x Br x PSC's FF and PCE.

[0005] To achieve the above objectives, the present invention employs the following technical solution:

[0006] A method for printing and fabricating high-efficiency perovskite solar cells includes the following steps:

[0007] Step 1: Pre-treat the FTO glass substrate;

[0008] Step 2, FTO glass substrate is immersed into TiCl4 aqueous solution to grow TiO2, and TiO2 electron transport layer is prepared after annealing;

[0009] Step 3, FAI, CsBr, PbI2 and MACl are dissolved in a solvent according to a set molar ratio, the solvent is a mixed solution of N,N-dimethylformamide, dimethyl sulfoxide and 2-methyltetrahydrofuran, then (3,5-difluorophenyl) potassium trifluoroborate is added to prepare an intermediate perovskite solution, DMAPbI3 is added to the intermediate perovskite solution, and FA 1-x-y C Sx MA y PbI 3-x Br x Perovskite precursor solution, FA 1-x-y C Sx MA y PbI 3-x Br x x is 0.05, and y is in the range of 0.02-0.06;

[0010] Step 4, the perovskite precursor solution is added dropwise to the TiO2 electron transport layer, the perovskite precursor solution is scraped by a doctor blade, air blowing treatment is performed after scraping, and annealing treatment is performed after air blowing to prepare a perovskite absorption layer;

[0011] Step 5, a Spiro-OMeTAD hole transport layer is prepared on the perovskite absorption layer;

[0012] Step 6, a metal electrode is prepared on the hole transport layer.

[0013] Further improvement of the present application is that:

[0014] Preferably, in step 3, the molar amount of DMAPbI3 added is 1-30% of the molar amount of PbI2,

[0015] Preferably, in step 3, the volume ratio of N,N-dimethylformamide, dimethyl sulfoxide and 2-methyltetrahydrofuran is (5-8):1:(1-4).

[0016] Preferably, in step 3, the molar fraction of (3,5-difluorophenyl) potassium trifluoroborate in the perovskite precursor solution is 0.15-3%.

[0017] Preferably, in step 4, before scraping, the FTO glass substrate and the TiO2 electron transport layer are preheated on a hot stage at 40-120℃.

[0018] Preferably, in step 4, during scraping, the distance between the doctor blade and the surface of the TiO2 electron transport layer is 10-500μm.

[0019] Preferably, in step 4, the temperature of the gas flow during the blowing process is 20-40℃, the flow rate is 10-100m / s, and the duration is 3-30s.

[0020] Preferably, in step 4, the annealing temperature is 150℃, and the annealing time is 15min.

[0021] Preferably, in step 5, a PEAI passivation layer is prepared before the preparation of the Spiro-OMeTAD hole transport layer.

[0022] A high-efficiency perovskite solar cell prepared by any of the above preparation methods, comprising, from bottom to top, an FTO glass substrate, a TiO2 electron transport layer, a FA 1-x-y C Sx MA y PbI 3-x Br x perovskite absorption layer, a Spiro-OMeTAD hole transport layer, and a metal electrode.

[0023] Compared with the prior art, the present application has the following beneficial effects:

[0024] The present application discloses a printing preparation method of a high-efficiency perovskite solar cell. 1-x-y C Sx MA y PbI 3-x Br x (x=0.05, y=0.02-0.06) is introduced into a precursor solution of a perovskite solar absorption layer FA + The structural formula is: (CH3)2NH2 + intermediate phase, which partially replaces PbI2 in the raw material, thereby introducing the DMAPbI3 intermediate phase in the perovskite crystallization process. Because the decomposition of the DMAPbI3 intermediate phase requires additional energy, the energy barrier of perovskite nucleation is increased, thereby prolonging the perovskite crystal nucleation window. From the perspective of material growth kinetics, the prolongation of the nucleation process is conducive to the transmission and diffusion of perovskite monomers, thereby promoting the increase of the grain size. At the same time, the DMAPbI3 intermediate phase can also repair defects in situ, achieving in-situ passivation of film defects. Through the DMAPbI3 intermediate phase, the perovskite film has a larger grain size, a higher carrier mobility, and a lower defect density. + and I -The ions effectively fill the vacancy defects in the crystallization process, reduce the non-radiation recombination loss and reduce the series resistance of the device. The DMA can also enter the perovskite lattice by occupying the position of the A-site ion of the perovskite, thereby reducing the defect state density of the perovskite and improving the structural stability. By the method of the application, the series resistance of the device is successfully reduced by 30%, the carrier transport is significantly improved, and the FF of the printed FA 1-x-y C Sx MA y PbI 3-x Br x PSC is improved from 73.88% to 81.42%, and the PCE is also improved accordingly. The method has important scientific guiding significance and potential application value for the future large-area commercial production of perovskite.

[0025] Further, the perovskite absorption layer, the passivation layer (PEAI) and the hole transport layer are all prepared by the doctor blade method. Benefiting from the regulation of the crystallization kinetics and the synergistic effect of defect passivation, the doctor blade steps of the perovskite absorption layer and other layers can be carried out in air environment at room temperature without additional inert atmosphere. This application provides important guidance and driving force for the commercial development of future perovskite photovoltaic technology. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 The crystallization schematic diagram of the perovskite thin film prepared by the method described in the application example 1 and the comparative example 1 before and after annealing.

[0027] Figure 2 The scanning electron microscope images of the perovskite thin film prepared by the method described in the application example 1 and the comparative example 1 before and after annealing.

[0028] Wherein, (a) is the comparative example 1 before annealing; (b) is the application example 1 before annealing; (c) is the comparative example 1 after annealing; (d) is the application example 1 after annealing.

[0029] Figure 3 The nuclear magnetic resonance 1 H spectrum of the perovskite thin film prepared by the method described in the application example 1 and the comparative example 1 before and after annealing.

[0030] Wherein, (a) is the comparative example 1 before annealing; (b) is the comparative example 1 after annealing; (c) is the application example 1 before annealing; (d) is the application example 1 after annealing.

[0031] Figure 4 The in-situ ultraviolet-visible (UV-vis) absorption spectrum of the perovskite thin film prepared by the method described in the application example 1 and the comparative example 1 during the doctor blade process.

[0032] wherein (a) is Figure for Comparative Example 1; (b) is Figure for Example 1.

[0033] Figure 5 In-situ photoluminescence (PL) spectra of perovskite films prepared by the method described in Example 1 and Comparative Example 1 during annealing process.

[0034] wherein (a) is Figure for Comparative Example 1; (b) is Figure for Example 1.

[0035] Figure 6 PL lifetime mapping results of perovskite films prepared by the method described in Example 1 and Comparative Example 1.

[0036] wherein (a) is Figure for Comparative Example 1; (b) is Figure for Example 1.

[0037] Figure 7 Performance curves of perovskite solar cells prepared by the method described in Example 1 and Comparative Example 1.

[0038] wherein (a) is current density-voltage (J-V) curve; (b) is photovoltaic device performance parameter statistical distribution of photoelectric conversion efficiency (PCE); (c) is photovoltaic device performance parameter statistical distribution of fill factor (FF); (d) is photovoltaic device performance parameter statistical distribution of series resistance (Rs); (e) is photovoltaic device performance parameter statistical distribution of shunt resistance (Rsh). S ) photovoltaic device performance parameter statistical distribution. DETAILED DESCRIPTION

[0039] The application will be further described below in conjunction with the accompanying drawings:

[0040] To enable persons skilled in the art to better understand the features and effects of the present application, the following is a general description and definition of the terms and phrases mentioned in the specification and claims. Unless otherwise specified, all technical and scientific words used herein have their usual meanings to those skilled in the art of the present application, and in case of conflict, the definition in the specification shall prevail.

[0041] In this document, unless otherwise specifically stated, "comprise", "include", "contain", "have" or similar words are inclusive, and mean "consist of" and "consist essentially of", for example, "A comprises a" means "A comprises a and other" and "A comprises only a".

[0042] The present application will be further described below in conjunction with specific examples. It should be understood that these examples are only used to illustrate the present application and not intended to limit the scope of the present application. Furthermore, it should be understood that those skilled in the art can make various modifications or changes to the present application after reading the content taught by the present application, and these equivalent forms also fall within the scope of the appended claims.

[0043] The following examples use apparatus and equipment that are conventional in the art. The experimental methods in the following examples, unless otherwise specified, are generally conducted under conventional conditions, or under conditions recommended by the manufacturer. The following examples use various raw materials, unless otherwise specified, and conventional commercially available products are used, which are of conventional specifications in the art. In the specification of the present application and in the following examples, unless otherwise specified, "%" means weight percent, "parts" means weight parts, and the ratio means weight ratio.

[0044] As the problem raised in the background art, the doctor blade coating FA 1-x-y C Sx MA y PbI 3-x Br x After forming the perovskite solar cell, for the FA 1-x-y C Sx MA y PbI 3-x Br x The research on improving the FF and PCE performance of perovskite solar cells shows that the size of the improved FF is mainly affected by the charge extraction ability, the overall series resistance (R S ) and the non-radiative recombination loss in the device, among which the grain size and defect state of the perovskite thin film have a significant impact on FF and PCE.

[0045] In order to solve the above problems, the first aspect of the present application discloses a printing method for preparing a high-efficiency perovskite solar cell, which specifically comprises the following steps:

[0046] Step 1, clean and dry the fluorine-doped tin oxide (FTO) glass substrate as a conductive substrate;

[0047] Step 2, immerse the FTO / glass substrate into a TiCl aqueous solution, soak at 50-80°C for 50-80 min. Then rinse the grown TiO2 with deionized water to prevent the TiO2 on the surface from continuing to grow, and the too thick electron transport layer will hinder the charge transport, the thickness of the electron transport layer is 10-50 nm. After rinsing, the TiO2 substrate is blown dry with an air gun, and then placed on a hot stage at 150-300°C for annealing for 0.2-3h to remove the water on the surface of TiO2, and obtain a dense TiO2 electron transport layer.

[0048] Step 3, preparation of perovskite precursor solution: perovskite compounds FAI, CsBr, PbI2 and MACl are mixed according to FA 1-x-y C Sx MA y PbI 3-x Br xThe intermediate engineering perovskite solution is prepared by dissolving the molar ratio of the above-mentioned substances in 1 mL of a mixed solvent, and the concentration of the solute is 0.7-1.2 M, wherein the solvent composition is N,N-dimethylformamide: dimethyl sulfoxide: 2-methyltetrahydrofuran = (5-8): 1: (1-4), and 0.15%-3% by mole fraction of (3,5-difluorophenyl) potassium trifluoroborate is added to the perovskite solution. The intermediate engineering perovskite solution is prepared by adding DMAPbI3 to the intermediate engineering perovskite solution, and the molar amount of DMAPbI3 added is 1-30% of the molar amount of PbI2. After stirring, the FA 1-x-y C Sx MA y PbI 3-x Br x The perovskite precursor solution (Cl element is substantially evaporated); in this process, PbI2 is replaced by DMAPbI3 to adjust the perovskite crystal growth process.

[0049] In the above process, the addition of 2-methyltetrahydrofuran and (3,5-difluorophenyl) potassium trifluoroborate can reduce the interaction between the perovskite solute and the solvent, and thus enable the solvent to be fully volatilized in the subsequent annealing heat treatment process, reducing the influence of the solvent on the crystallization of the perovskite absorption layer. However, because the solvent volatilizes too quickly, it can accelerate the perovskite crystallization process, causing the perovskite to crystallize too quickly, the perovskite particles to be too small, and the quality of the perovskite to be reduced. By adding a small amount of DMAPbI3 to the perovskite, it can be ensured that the solvent is fully removed while the crystallization of the perovskite is delayed, forming a high-quality perovskite absorption layer.

[0050] Step 4: The FTO / TiO2 substrate is preheated on a hot stage at 40-120°C for 3 min, and the preheated substrate can promote the nucleation and crystallization of the perovskite; then 6-20 μL of the peroviskite precursor solution is dropped on the TiO2 / FTO substrate, and the doctor blade is used to scrape and coat at a speed of 0.2-50 m / min, and the distance between the doctor blade and the substrate is 10-500 μm. The distance between the doctor blade and the substrate affects the thickness of the scraped peroviskite, and ultimately affects the crystallization quality of the peroviskite film. Generally speaking, the thicker the scraped peroviskite, the slower the crystallization speed. The scraped peroviskite film is immediately treated with air blowing to accelerate the evaporation of the solvent, thereby reducing moisture erosion and promoting peroviskite crystallization. The air blowing process uses room temperature air flow, the air flow temperature is 20-30°C, the flow rate is 10-100 m / s, and the duration is 3-30 s. The scraped peroviskite film is immediately transferred to a hot stage at 150°C for heating for 10-25 min to promote the subsequent growth of the peroviskite.

[0051] Step 5, preparation of the perovskite passivation agent solution: 0.0005-0.0200 mg phenethylammonium iodide (PEAI) was dissolved in 1 mL isopropanol, and shaken for 12 h at 25 °C in air.

[0052] Step 6, the prepared perovskite was preheated on a hot stage at 30-100 °C for 3 min, and 3.0-100 μL of PEAI solution was dropped on the perovskite thin film at room temperature. The doctor blade was used to forwardly coat at a speed of 1.5 m / min, and the distance between the doctor blade and the substrate was 10-500 μm.

[0053] Step 7, preparation of the hole transport layer solution: 90 mg Spiro-OMeTAD, 22 μL Li-TFSI solution (520 mg dissolved in 1 mL acetonitrile), 20 μL Co-TFSI solution (375 mg Co-TFSI dissolved in 1 mL acetonitrile) and 30 μL 4-tert-butylpyridine were added to 1 mL chlorobenzene, and shaken for 12 h at 25 °C in air.

[0054] Step 8, the prepared perovskite was preheated on a hot stage at 30-100 °C for 3 min, and 3.0-100 μL of Spiro-OMeTAD solution was dropped on the perovskite thin film at room temperature. The doctor blade was used to forwardly coat at a speed of 1.5 m / min, and the distance between the doctor blade and the substrate was 10-500 μm.

[0055] Step 9, a gold top electrode with a thickness of about 70 nm was deposited on the hole transport layer by thermal evaporation, and the vacuum degree was 9x10 –4 Pa. The evaporation started at about 0.05 nm / s, and after the evaporation was completed, the battery was cooled in the vacuum chamber for 30 min and then taken out. The effective area of each individual battery was 0.09 cm 2 .

[0056] The substrate, the electron transport layer, the perovskite light-absorbing layer, the perovskite passivation layer, the hole transport layer and the metal electrode were sequentially stacked from bottom to top.

[0057] The following further illustrates with specific examples.

[0058] Comparative Example 1

[0059] Step 1, clean and dry fluorine-doped tin oxide (FTO) glass substrate as conductive substrate for use;

[0060] Step 2, FTO / glass substrate was immersed into TiCl aqueous solution and soaked at 70 °C for 1 h. Then the grown TiO2 was rinsed with deionized water to prevent the further growth of TiO2 on the surface, which would hinder the charge transport due to the thick electron transport layer with a thickness of 20 nm. The rinsed TiO2 substrate was blown dry with air gun and then annealed on a hot plate at 200 °C for 0.5 h to remove the water on the surface of TiO2 and obtain a compact TiO2 electron transport layer.

[0061] Step 3, Perovskite precursor solution was prepared by dissolving 0.7 M of perovskite compounds FAI, CsBr, PbI2 and MACl with a molar ratio of 0.95:0.05:1:0.3 in 1 mL of mixed solvents, in which the solvent composition was N,N-dimethylformamide: dimethyl sulfoxide: 2-methyltetrahydrofuran = 8:1:1, and 0.15% molar ratio of (3,5-difluorophenyl)potassium trifluoroborate was added to the perovskite solution.

[0062] Step 4, FTO / TiO2 substrate was preheated on a hot plate at 60 °C for 3 min, and then 8.5 μL of FAPbI3 precursor solution was dropped on the TiO2 / FTO substrate, which was forwardly coated by a doctor blade at a speed of 1.5 m / min with a distance of 80 μm between the blade and the substrate. The coated perovskite film was immediately treated by air blowing to accelerate the evaporation of the solvent, thereby reducing the moisture erosion and promoting the perovskite crystallization. The air blowing process was performed at a flow temperature of 30 °C, a flow rate of 20 m / s, and a duration of 8 s. The coated perovskite film was immediately transferred to a hot plate at 150 °C for 15 min to promote the subsequent growth of perovskite.

[0063] Step 5, Perovskite passivation agent solution was prepared by dissolving 0.0030 mg of phenethylammonium iodide (PEAI) in 1 mL of isopropanol, which was shaken at 25 °C in the air for 12 h.

[0064] Step 6, The prepared perovskite was preheated on a hot plate at 40 °C for 3 min, and then 6.0 μL of PEAI solution was dropped on the perovskite film, which was forwardly coated by a doctor blade at a speed of 1.5 m / min with a distance of 60 μm between the blade and the substrate.

[0065] Step 7, Hole transport layer solution was prepared by adding 90 mg of Spiro-OMeTAD, 22 μL of Li-TFSI solution (520 mg dissolved in 1 mL of acetonitrile), 20 μL of Co-TFSI solution (375 mg of Co-TFSI dissolved in 1 mL of acetonitrile), and 30 μL of 4-tert-butylpyridine into 1 mL of chlorobenzene, which was shaken at 25 °C in the air for 12 h.

[0066] Step 8, the prepared perovskite was placed on a 40 °C hot stage for preheating for 3 min, 6.0 μL of Spiro-OMeTAD solution was dropped on the perovskite film, and was forwardly coated at a speed of 1.5 m / min under the action of a doctor blade, the distance between the doctor blade and the substrate was 60 μm.

[0067] Step 9, a gold top electrode with a thickness of about 70 nm was deposited on the hole transport layer by thermal evaporation, the vacuum degree was 9 x 10 –4 Pa, evaporation started at about 0.05 nm / s, after the evaporation was completed, the battery was cooled in the vacuum chamber for 30 min and then taken out. The effective area of each individual battery was 0.09 cm 2 .

[0068] Example 1

[0069] FA 1-x-y C Sx MA y PbI 3-x Br x The specific steps of the perovskite solar cell are as follows:

[0070] Step 1, a fluorine-doped tin oxide (FTO) glass substrate was cleaned and dried, and was used as a conductive substrate;

[0071] Step 2, the FTO / glass substrate was immersed in a TiCl aqueous solution, and was soaked at 70 °C for 1 h. Subsequently, the grown TiO2 was washed with deionized water to prevent the TiO2 on the surface from continuing to grow, and an excessively thick electron transport layer would hinder the charge transport, and the thickness of the electron transport layer was 20 nm. The washed TiO2 substrate was blown dry with an air gun, and was then placed on a hot stage at 200 °C for annealing for 0.5 h to remove the water on the surface of the TiO2, and a dense TiO2 electron transport layer was obtained.

[0072] Step 3, the preparation of the perovskite precursor solution was as follows: 0.7 M of perovskite compounds FAI, CsBr, PbI2 and MACl were dissolved in 1 mL of a mixed solvent according to a molar ratio of 0.95:0.05:1:0.3, wherein the solvent composition was N,N-dimethylformamide: dimethyl sulfoxide: 2-methyltetrahydrofuran = 8:1:1, and 0.15% mole fraction of (3,5-difluorophenyl) potassium trifluoroborate was added to the perovskite solution to form an intermediate engineering perovskite solution, 5% mole ratio of DMAPbI3 was added to the perovskite solution to replace PbI2 to adjust the perovskite crystal growth process.

[0073] Step 4, the FTO / TiO2 substrate was preheated on a 60 °C hot stage for 3 min, then 8.5 μL of FAPbI3 precursor solution was dropped on the TiO2 / FTO substrate, and was forwardly coated by a doctor blade at a speed of 1.5 m / min with a distance of 80 μm between the blade and the substrate. The perovskite film after the coating was immediately treated by air blowing to accelerate the evaporation of the solvent, so as to reduce the moisture erosion and promote the perovskite crystallization. The air blowing process was performed at a temperature of 30 °C with a flow rate of 20 m / s for a duration of 8 s. The perovskite film after the coating was immediately transferred to a hot stage at 150 °C for heating for 15 min to promote the subsequent growth of the perovskite, thereby obtaining the perovskite film.

[0074] Step 5, preparation of the passivation agent solution of the perovskite: 0.0030 mg of phenethylammonium iodide (PEAI) was dissolved in 1 mL of isopropanol, and was shaken at 25 °C in the air for 12 h for standby use.

[0075] Step 6, the prepared perovskite was preheated on a 40 °C hot stage for 3 min, and 6.0 μL of PEAI solution was dropped on the perovskite film at room temperature. The solution was forwardly coated by a doctor blade at a speed of 1.5 m / min with a distance of 60 μm between the blade and the substrate.

[0076] Step 7, preparation of the hole transport layer solution: 90 mg of Spiro-OMeTAD, 22 μL of Li-TFSI solution (520 mg dissolved in 1 mL of acetonitrile), 20 μL of Co-TFSI solution (375 mg of Co-TFSI dissolved in 1 mL of acetonitrile) and 30 μL of 4-tert-butylpyridine were added into 1 mL of chlorobenzene, and were shaken at 25 °C in the air for 12 h.

[0077] Step 8, the prepared perovskite was preheated on a 40 °C hot stage for 3 min, and 6.0 μL of Spiro-OMeTAD solution was dropped on the perovskite film. The solution was forwardly coated by a doctor blade at a speed of 1.5 m / min with a distance of 60 μm between the blade and the substrate.

[0078] Step 9, a gold top electrode with a thickness of about 70 nm was deposited on the hole transport layer by thermal evaporation, and the vacuum degree was 9 x 10 –4 Pa. The evaporation started at a speed of about 0.05 nm / s, and after the evaporation was completed, the battery was cooled in the vacuum chamber for 30 min and then taken out. The effective area of each individual battery was 0.09 cm 2 .

[0079] Figure 1Schematic diagram of crystallization of perovskite films prepared by the method described in Example 1 and Comparative Example 1 of the present application before and after annealing. DMAPbI3 was introduced into the perovskite precursor solution. In the film after doctor blading, DMAPbI3 forms intermediate phases. After high-temperature annealing (150°C) treatment, these intermediate phases decompose, fill in the vacancy defects and occupy the perovskite lattice positions, and transform into cubic phase FA 1-x-y C Sx MA y PbI 3-x Br x perovskite phase, thereby in-situ filling in the lattice defects during perovskite growth.

[0080] Figure 2 Scanning electron microscope images of perovskite films prepared by the method described in Example 1 and Comparative Example 1 of the present application before and after annealing. Before annealing treatment, the perovskite film of Comparative Example 1 shows relatively small FAPbI3 grain size. In contrast, the film of Example 1 has significantly increased grain size due to the addition of DMAPbI3. This result fully demonstrates the important role of DMAPbI3 in delaying crystal growth and enlarging crystal size. In addition, it is also observed that there are needle-like 1D DMAPbI3 intermediate phases in the film of the optimized group. The formation of this intermediate phase is common in the processing of CsPbI3, mainly due to its lower formation energy, which can effectively optimize crystal growth and passivate defects.

[0081] Figure 3 Nuclear magnetic resonance 1 H spectra of perovskite films prepared by the method described in Example 1 and Comparative Example 1 of the present application before and after annealing. The optimized film has a nuclear magnetic resonance peak at chemical shift δ = 8.17 ppm related to the –NH2 group in DMA + . After annealing, the signal of DMA still exists, which indicates that there is DMA residue in the final perovskite film. The residue of DMA is due to the fact that part of DMA occupies the lattice positions of atoms in the perovskite film.

[0082] Figure 4 In-situ ultraviolet-visible (UV-vis) absorption spectra of perovskite films prepared by the method described in Example 1 and Comparative Example 1 of the present application during doctor blading. The nucleation window of perovskite in Example 1 is significantly prolonged compared to the control group (Stage II). This is because the decomposition of DMAPbI3 intermediate phase requires additional energy, which increases the energy barrier for perovskite nucleation.

[0083] Figure 5 In-situ photoluminescence (PL) spectra of perovskite films prepared by the method described in Example 1 and Comparative Example 1 of the present application during annealing. This result shows that DMAPbI3 can in-situ repair defects. This mechanism is mainly due to the fact that DMA+ and I - The ions effectively fill the vacancy defects during the crystal growth, thereby improving the quality of the perovskite film.

[0084] Figure 6 The PL lifetime mapping results of the perovskite film prepared by the method described in Example 1 and Comparative Example 1 of the present application further prove that the non-radiative recombination is effectively and uniformly inhibited in the film of Example 1.

[0085] Figure 7 The current density-voltage (J-V) curves and photovoltaic device performance parameter statistical distribution (photoelectric conversion efficiency (PCE), fill factor (FF) and series resistance (R S )) of the perovskite solar cells prepared by the method described in Example 1 and Comparative Example 1 of the present application are shown in Table 1. The PCE of the device of Comparative Example 1 is 21.57%, of which the fill factor (FF) is 73.88%. In contrast, the device of Example 1 exhibits a superior PCE of 23.13%, and the FF is 81.42%, which is significantly improved. Since the intermediate optimization strategy effectively improves the crystalline quality of the perovskite film and can in-situ passivate the vacancy defects in the film, the charge extraction capability is significantly enhanced. By fitting the J-V parameters, the R S is reduced from 78.23 Ω to 52.87 Ω, with a reduction of 30%.

[0086] Table 1. FAPbI3 best performance PSC photovoltaic parameters of Example 1 and Example 1

[0087]

[0088] Example 2

[0089] In this example, the molar amount of DMAPbI3 added is 1% of the molar amount of PbI2, and the rest of the uninvolved part is the same as Example 1.

[0090] Example 3

[0091] In this example, the molar amount of DMAPbI3 added is 10% of the molar amount of PbI2, and the rest of the uninvolved part is the same as Example 1.

[0092] Example 4

[0093] In this example, the molar amount of DMAPbI3 added is 20% of the molar amount of PbI2, and the rest of the uninvolved part is the same as Example 1.

[0094] Example 5

[0095] In this embodiment, the added molar amount of DMAPbI3 is 30% of the molar amount of PbI2, and the rest is the same as in Embodiment 1.

[0096] Embodiment 6

[0097] In this embodiment, the FTO / TiO2 substrate is preheated on a 40°C hot stage for 3 min before the perovskite precursor solution is blade-coated, and the rest is the same as in Embodiment 1.

[0098] Embodiment 7

[0099] In this embodiment, the FTO / TiO2 substrate is preheated on a 80°C hot stage for 3 min before the perovskite precursor solution is blade-coated, and the rest is the same as in Embodiment 1.

[0100] Embodiment 8

[0101] In this embodiment, the FTO / TiO2 substrate is preheated on a 120°C hot stage for 3 min before the perovskite precursor solution is blade-coated, and the rest is the same as in Embodiment 1.

[0102] Embodiment 9

[0103] In this embodiment, the distance between the blade and the surface of the TiO2 electron transport layer is 10 μm during the blade-coating of the perovskite precursor solution, and the rest is the same as in Embodiment 1.

[0104] Embodiment 10

[0105] In this embodiment, the distance between the blade and the surface of the TiO2 electron transport layer is 50 μm during the blade-coating of the perovskite precursor solution, and the rest is the same as in Embodiment 1.

[0106] Embodiment 11

[0107] In this embodiment, the distance between the blade and the surface of the TiO2 electron transport layer is 500 μm during the blade-coating of the perovskite precursor solution, and the rest is the same as in Embodiment 1.

[0108] Embodiment 12

[0109] In this embodiment, the temperature of the air flow after the blade-coating of the perovskite precursor solution is 20°C, the flow rate of the air flow is 10 m / s, and the duration is 30 s.

[0110] Embodiment 13

[0111] In this embodiment, the temperature of the air flow after the blade-coating of the perovskite precursor solution is 30°C, the flow rate of the air flow is 50 m / s, and the duration is 15 s.

[0112] Embodiment 14

[0113] In this embodiment, after the perovskite precursor solution is scraped, the temperature of the air flow is 40°C, the flow rate of the air flow is 100 m / s, and the duration is 3 s.

[0114] Example 15

[0115] In this embodiment, x is 0.05, y is 0.02, and the perovskite absorption layer is FA 0.93 Cs 0.05 MA 0.02 PbI 2.95 Br 0.05 .

[0116] Example 16

[0117] In this embodiment, x is 0.05, y is 0.06, and the perovskite absorption layer is FA 0.89 Cs 0.05 MA 0.06 PbI 2.95 Br 0.05 .

[0118] The above description is merely the preferred embodiment of this application, and is not intended to limit the application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the application shall be included in the protection scope of the application.

Claims

1. A method for the printing preparation of high efficiency perovskite solar cells, characterized in that, The method comprises the following steps: Step 1, pretreating the FTO glass substrate; Step 2, immersing the FTO glass substrate into a TiCl4 aqueous solution to grow TiO2, and annealing to obtain a TiO2 electron transport layer; Step 3, dissolving FAI, CsBr, PbI2 and MACl in a solvent according to a set molar ratio, the solvent is a mixed solution of N,N-dimethylformamide, dimethyl sulfoxide and 2-methyltetrahydrofuran, then adding (3,5-difluorophenyl)potassium trifluoroborate to prepare an intermediate engineering perovskite solution, adding DMAPbI3 in the intermediate engineering perovskite solution, and preparing FA 1-x-y Cs x MA y PbI 3-x Br x perovskite precursor solution, FA 1-x-y Cs x MA y PbI 3-x Br x x is 0.05, and y ranges from 0.02 to 0.06; Step 4, dropping the perovskite precursor solution onto the TiO2 electron transport layer, and coating the perovskite precursor solution by using a doctor blade, and then performing air blowing treatment, and then performing annealing treatment to obtain a perovskite absorption layer; Step 5, preparing a Spiro-OMeTAD hole transport layer on the perovskite absorption layer; Step 6, preparing a metal electrode on the hole transport layer.

2. The printing preparation method of a high-efficiency perovskite solar cell according to claim 1, characterized in that, In step 3, the molar amount of DMAPbI3 is 1-30% of the molar amount of PbI2.

3. The method according to claim 1, wherein In step 3, the volume ratio of N,N-dimethylformamide, dimethyl sulfoxide and 2-methyltetrahydrofuran is (5-8):1:(1-4). 4.The method according to claim 1, wherein, In step 3, the molar fraction of (3,5-difluorophenyl)potassium trifluoroborate in the perovskite precursor solution is 0.15-3%. 5.The method of claim 1, wherein In step 4, before coating, the FTO glass substrate and the TiO2 electron transport layer are preheated on a hot stage at 40-120℃.

6. The method according to claim 1, wherein In step 4, during the coating process, the distance between the doctor blade and the surface of the TiO2 electron transport layer is 10-500μm. 7.The method according to claim 1, wherein, In step 4, during the air blowing process, the airflow temperature is 20-40℃, the flow rate is 10-100m / s, and the duration is 3-30s. 8.The method according to claim 1, wherein, In step 4, the annealing temperature is 150℃, and the annealing time is 15min. 9.The method according to claim 1, wherein, In step 5, before preparing the Spiro-OMeTAD hole transport layer, a PEAI passivation layer is prepared.

10. A high efficiency perovskite solar cell prepared by the method of any one of claims 1-9, characterized in that, comprises a FTO glass substrate, a TiO2electron transport layer, a FA 1-x-y Cs x MA y PbI 3-x Br x perovskite absorption layer, a Spiro-OMeTAD hole transport layer, and a metal electrode.

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