Liquid crystal mixture, perovskite solar cell containing liquid crystal mixture and preparation method of perovskite solar cell

Abstract

The invention discloses a liquid crystal mixture, a perovskite solar cell containing the liquid crystal mixture and a preparation method of the perovskite solar cell, and belongs to the technical field of perovskite materials. The liquid crystal mixture is a mixture of 2, 2-dithiodiethanol diacrylate (2S) and 1, 4-bis-[4-(3-acryloyloxy propoxy) benzoyloxy]-2-methyl benzene (RM257), and in the preparation process of the perovskite solar cell, the liquid crystal mixture is spin-coated on the surface of the SnO2 electron transport layer to serve as a modification layer. S ions and C-O and C = O functional groups in the mixture are combined with uncoordinated Pb < 2 + > under the Lewis acid-base action to passivate Pb-based defects on the surface of the perovskite thin film, and the self-assembly characteristic of the liquid crystal material can promote preferred orientation growth of the perovskite thin film, so that the perovskite thin film with large grain size and high crystallinity is prepared. The photoelectric conversion efficiency and the operation stability of the perovskite device optimized by the liquid crystal mixture are remarkably improved, and the photoelectric conversion efficiency reaches 25.89%.

Description

Technical Field

[0001] This invention belongs to the field of perovskite material and device preparation technology, specifically relating to a liquid crystal mixture and a perovskite solar cell containing the mixture, and a method for preparing the same. Background Technology

[0002] Solar energy, as a green energy source, has become a global research hotspot in energy development due to its advantages such as large reserves, no pollution, and wide distribution. For decades, solar cell technology based on the photovoltaic effect has continuously advanced and been widely applied. Photovoltaic power generation provides a reliable approach for my country to solve its energy crisis and environmental problems, contributing to the achievement of the "carbon peak and carbon neutrality" goals and having a profound impact on the future development of human society. In recent years, perovskite solar cells (PSCs) have developed rapidly and achieved remarkable success. This is attributed to the advantages of these materials, such as low-cost raw materials and simple manufacturing processes.

[0003] Currently, high-performance power storage devices (PSCs) mostly use SnO2 as the electron transport layer (ETL), but its inherent defects severely limit further improvements in device performance. SnO2 is considered a more promising ETL candidate material due to its high electron mobility, wide bandgap, and low-temperature processability. However, the ubiquitous oxygen vacancies (V vacancy sites) in SnO2... O Defects and dangling Sn bonds can lead to interface charge trapping and increased electron injection barriers, thus severely limiting the development of perovskite solar cells. V OC Improved with FF. In addition, uncoordinated Pb at the perovskite buried interface. 2+ I - The synergistic effect of defects in the ETL and perovskite layers further exacerbates carrier recombination and lattice instability. Therefore, achieving simultaneous defect passivation and energy level optimization in both the ETL and perovskite layers through interface engineering is crucial for improving device performance. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a liquid crystal mixture and a perovskite solar cell containing the mixture and a method for preparing the mixture. This invention aims to solve the problem of low photoelectric conversion efficiency in existing perovskite solar cells due to numerous defects at the interface between the electron transport layer and the perovskite light-absorbing layer. The method for preparing this perovskite solar cell is simple to operate, has high device efficiency, and good repeatability.

[0005] To achieve the above objectives, the present invention employs the following technical solution: A liquid crystal mixture, wherein the liquid crystal mixture is a mixture of 2,2-dithiodiethanol diacrylate and 1,4-bis-[4-(3-acryloyloxypropoxy)benzoyloxy]-2-methylbenzene, has the following structural formula: .

[0006] A further improvement of the present invention is that: Preferably, the mass ratio of the 2-dithiodiethanol diacrylate and 1,4-bis-[4-(3-acryloyloxypropoxy)benzoyloxy]-2-methylbenzene is 5:95.

[0007] A method for preparing the above-mentioned liquid crystal mixture includes the following steps: using bis(2-hydroxyethyl) disulfide, triethylamine and dichloromethane as raw materials, acryloyl chloride is added dropwise under ice bath to react, and after post-treatment and column chromatography, 2,2-dithiodiethanol diacrylate is obtained; 2,2-dithiodiethanol diacrylate and 1,4-bis-[4-(3-acryloyloxypropoxy)benzoyloxy]-2-methylbenzene are dissolved in dichloromethane, mixed evenly and dried to obtain the liquid crystal mixture.

[0008] A method for fabricating a perovskite solar cell includes the following steps: S1. SnO2 colloidal aqueous solution is spin-coated onto FTO conductive glass to prepare a SnO2 electron transport layer; S2, dissolve the liquid crystal mixture of claim 1 in chlorobenzene to prepare a modification layer solution with a concentration of 0.05-0.40 mg / mL, spin-coat it onto the SnO2 electron transport layer, and anneal it to form a liquid crystal mixture layer; S3, FA 0.9 Cs 0.1 PbI3 perovskite precursor solution was spin-coated onto a liquid crystal mixture layer and annealed to obtain FA. 0.9 Cs 0.1 PbI3 perovskite light-absorbing layer; S4, in FA 0.9 Cs 0.1 Spiro fabrication on PbI3 perovskite light-absorbing layer OMeTAD hole transport layer; S5, in Spiro A metal layer was fabricated on the OMeTAD hole transport layer to obtain a perovskite solar cell.

[0009] Preferably, in S2, the spin coating speed is 2000-4000 rpm and the spin coating time is 30 s.

[0010] Preferably, in S2, the annealing temperature is 100 ℃ and the annealing time is 8-12 min.

[0011] Preferably, in S3, the perovskite precursor solution is a mixed solution formed by dissolving formamidinium hydroiodate, cesium iodide, and lead iodide in DMF and DMSO.

[0012] Preferably, in S3, the concentration of the perovskite precursor solution is 1.0 M.

[0013] Preferably, in S3, FA 0.9 Cs 0.1 The preparation process of the PbI3 perovskite absorber layer is divided into two stages. In the first stage, the spin coating speed is 1000-2000 rpm and the spin coating time is 10 s. In the second stage, the spin coating speed is 4000-5000 rpm and the spin coating time is 30 s.

[0014] A perovskite solar cell with an optimized electron transport layer prepared by any of the above methods includes, from bottom to top, a conductive glass, an electron transport layer, a liquid crystal mixture layer, a perovskite light-absorbing layer, a hole transport layer, and a metal electrode.

[0015] Compared with the prior art, the present invention has the following beneficial effects: This invention discloses a liquid crystal mixture, a perovskite solar cell containing the mixture, and a method for preparing the same. The method involves modifying the surface of the SnO2 electron transport layer of the perovskite solar cell with a layer of liquid crystal mixture (2S+RM257) at concentrations ranging from 0.05 to 0.40 mg / mL. The process of coating the electron transport layer with 2S+RM257 requires no additional complex operations to prepare the liquid crystal mixture layer. The entire method for preparing the perovskite solar cell is simple to operate and has good reproducibility. This method can simultaneously improve the efficiency and stability of perovskite solar cells.

[0016] This invention also discloses a liquid crystal mixture, a perovskite solar cell containing the mixture, and a method for preparing the mixture. This material can interact not only with the electron transport layer but also with the perovskite. On one hand, the S atoms in the liquid crystal mixture interact with the Sn atoms in SnO2. 4+ Bonding occurs, passivating uncoordinated Sn on the SnO2 surface. 4+ Modification with liquid crystal mixtures can also improve the electrical properties of SnO2, enhancing its charge extraction and transfer capabilities at the interface. On the other hand, the S atoms and oxygen-containing functional groups (CO, C=O) in the liquid crystal mixture can interact with uncoordinated Pb atoms in the perovskite. 2+ The Lewis acid-base interaction between ions effectively reduces the concentration of lead vacancy defects on the perovskite surface, achieving effective passivation of the buried interface of the perovskite solar cell. Simultaneously, the self-assembly characteristics of the liquid crystal material induce crystallization during the perovskite film growth process, improving the crystallinity quality of the perovskite film. Ultimately, the perovskite solar cell regulated by the 2S+RM257 hybrid system achieved a photoelectric conversion efficiency of 25.89%. The unencapsulated device maintained 95% of its initial photoelectric conversion efficiency after 3000 hours of storage in a room temperature RH~30% environment, demonstrating excellent environmental stability.

[0017] This invention introduces a liquid crystal mixture. The self-assembly properties of the liquid crystal material play a role in inducing crystallization during the growth of perovskite films. Its rich dynamic phase transition behavior allows for reversible switching between different phase states through temperature control, further optimizing the order and directionality of self-assembly. During heating, liquid crystal molecules gradually transform from ordered stacking to a fluid liquid crystal state, providing a uniform and regular template for perovskite precursor molecules and guiding perovskite grains to grow along specific directions. During cooling, the reverse phase transition can be further refined through fine-tuning of intermolecular forces, suppressing disordered agglomeration and defect formation of perovskite grains, ultimately effectively improving the crystallinity and morphological uniformity of the perovskite film. Attached Figure Description

[0018] Figure 1 The XRD pattern of the liquid crystal mixture; Figure 2 This is a schematic diagram of the structure of a perovskite solar cell with an optimized electron transport layer as described in Embodiment 1 of the present invention; In the diagram: from bottom to top, they are FTO conductive glass, SnO2 electron transport layer, 2S+RM257 mixture layer, and FA. 0.9 Cs 0.1 PbI3 perovskite light-absorbing layer, Spiro-OMeTAD hole transport layer, and gold electrode.

[0019] Figure 3 These are SEM scan comparison images of perovskite films before and after modification of the SnO2 electron transport layer surface with 2S and 2S+RM257, respectively, as described in Example 1 of this invention. Among them, (a) is unmodified, (b) is modified 2S, and (c) is modified 2S+RM257.

[0020] Figure 4 The PL spectra of the perovskite films after unmodified SnO2 electron transport layer surface and after respectively modified with 2S and 2S+RM257 as described in Example 1 of the present invention; Figure 5 The TRPL spectra of the perovskite films with no modification and modified with 2S and 2S+RM257 respectively on the surface of the SnO2 electron transport layer as described in Example 1 of the present invention; Figure 6 The XPS spectra of 2S and 2S+RM257 reacting with PbI2 as described in Embodiment 1 of the present invention; Figure 7 The UPS are the unmodified SnO2 films and the SnO2 films modified with 2S and 2S+RM257 respectively, as described in Example 1 of this invention; Figure 8The dark state of the perovskite solar cell described in Example 1 of this invention is shown after unmodified SnO2 electron transport layer surface and after modification with 2S and 2S+RM257 respectively. JV curve; Figure 9 This refers to the perovskite solar cells described in Example 1 of the present invention, after unmodified SnO2 electron transport layer surface and after modification with 2S and 2S+RM257 respectively. JV curve; Figure 10 This relates to the stability of perovskite solar cells after unmodified SnO2 electron transport layer surface and after modification with 2S and 2S+RM257 respectively, as described in Example 1 of the present invention. Detailed Implementation

[0021] The present invention will now be described in further detail with reference to the accompanying drawings: To enable those skilled in the art to understand the features and effects of the present invention, the terms and expressions used in the specification and claims are explained and defined in general below. Unless otherwise specified, all technical and scientific terms used herein have the ordinary meaning understood by those skilled in the art regarding the present invention, and in case of conflict, the definitions in this specification shall prevail.

[0022] In this article, unless otherwise specified, “contains,” “includes,” “containing,” “has,” or similar terms cover the meanings of “composed of” and “mainly composed of,” for example, “A contains a” covers the meanings of “A contains a and others” and “A contains only a.”

[0023] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0024] The following examples use instruments and equipment conventional in the art. Experimental methods in the following examples, unless otherwise specified, are generally performed under conventional conditions or as recommended by the manufacturer. All raw materials used in the following examples are conventional commercially available products with specifications conventional in the art. In this specification and the following examples, unless otherwise specified, "%" refers to weight percentage, "parts" refers to parts by weight, and "ratio" refers to weight proportion.

[0025] A liquid crystal mixture, wherein the liquid crystal mixture is a mixture of 2,2-dithiodiethanol diacrylate (I) and 1,4-bis-[4-(3-acryloyloxypropoxy)benzoyloxy]-2-methylbenzene (II), has the following structural formula: .

[0026] In the above mixture, the mixing ratio of 2,2-dithiodiethanol diacrylate (I) and 1,4-bis-[4-(3-acryloyloxypropoxy)benzoyloxy]-2-methylbenzene (II) is 5:95; the liquid crystal mixture is a milky white solid.

[0027] The second aspect of the present invention discloses a method for preparing a liquid crystal mixture, comprising the following steps: adding bis(2-hydroxyethyl) disulfide, triethylamine and dichloromethane to a two-necked reaction flask, stirring in an ice-water bath for 20 min, slowly adding acryloyl chloride, continuing stirring, then extracting, drying, rotary evaporating, and separating and purifying by column chromatography to obtain a brown oily 2,2-dithiodiethanol diacrylate (2S), which needs to be stored away from light; when preparing the liquid crystal mixture (2S+RM257), 2S and RM257 are added to dichloromethane, such that the mass percentages of 2S and RM257 are 5% and 95% respectively, stirring and shaking, drying to obtain a milky white sample. The common structural feature of these two substances is the presence of an acryloyloxy group, whose carbon-carbon double bond has photosensitive activity and can undergo free radical photopolymerization reaction of the acryloyl double bond under ultraviolet light.

[0028] The mixture contained 2.0 g of bis(2-hydroxyethyl) disulfide and a volume ratio of 15 mL:40 mL:4.2 mL for triethylamine, dichloromethane and acryloyl chloride.

[0029] An embodiment of the present invention discloses a method for preparing the above-mentioned liquid crystal mixture. The preparation method is as follows: 2.0 g of bis(2-hydroxyethyl) disulfide is added to a two-necked reaction flask, 15 mL of triethylamine is added as a catalyst and 40 mL of dichloromethane is added as a solvent. The mixture is placed in an ice-water bath and stirred for 20 min. Acryloyl chloride (4.7 g, 4.2 mL) is slowly added dropwise. The mixture is stirred at 30°C for 24 h. The resulting solution is repeatedly extracted and dried with anhydrous MgSO4. The extracted solution is then subjected to rotary evaporation to remove the solvent dichloromethane and the remaining triethylamine. The product is separated and purified by column chromatography to obtain a brown oily 2,2-dithiodiethanol diacrylate (2S), which is stored in the dark. Preparation of 2S+RM257: 5% 2S and 95% RM257 are added to dichloromethane and stirred until well mixed. The solution is placed in an oven at 60 °C for more than 24 h to remove the dichloromethane and obtain a milky white sample.

[0030] XRD details of the liquid crystal mixture prepared by this embodiment are shown in [reference needed]. Figure 1 ,from Figure 1 It can be seen from Figure 1 The image shows the 1H NMR spectrum of the synthesized 2S. The quintet at δ=2.50 ppm is attributed to the methyl signal peak of the solvent deuterated dimethyl sulfoxide, and the singlet at δ=3.33 ppm is the water peak. The triplet in the region of δ=3.02-3.05 ppm is attributed to the methylene proton signal connected to S, with an integrated area of ​​4, corresponding to 4 protons. The proton signal peak in the region of δ=4.34-4.37 ppm is the methylene signal peak connected to O, with an integrated area of ​​4, indicating that there are 4 protons in this region. The proton signals at both ends of the double bond are located in the region of δ=5.95-6.37 ppm. The integrated area ratio of the three sets of peaks is 2:2:2.

[0031] An embodiment of the present invention discloses a method for preparing a perovskite solar cell with optimized liquid crystal mixture interface material, comprising the following steps: Step 1: Clean the FTO glass substrate; Cut the FTO glass to a size of 2.5 × 2.5 cm, place it in an ultrasonic cleaner, and clean it with glass cleaner and ultrapure water (glass cleaner: ultrapure water = 1:100) for 30 minutes. Then change the ultrapure water every 30 minutes, and repeat this step 3 times. After cleaning, dry the FTO glass with compressed air for later use.

[0032] Step 2: Prepare a SnO2 electron transport layer precursor solution and a 2S+RM257 mixed solution; The SnO2 electron transport layer precursor solution is prepared by dissolving SnO2 colloidal nanoparticles in deionized water (V / V=1:6) and stirring for 4-8 h. The 2S+RM257 mixed solution is prepared by dissolving 0.05-0.40 mg of 2S+RM257 solid in 1 mL of chlorobenzene, wherein the mass ratio of 2S to RM257 is 5:95, stirring at room temperature for 30-60 min to obtain a 2S+RM257 mixed solution with a concentration of 0.05-0.40 mg / mL, and filtering with a 0.45 μm filter before use.

[0033] Step 3: Prepare the SnO2 electron transport layer; After treating the cleaned FTO glass from step 1 with ultraviolet ozone for 10-15 min, the SnO2 colloidal nanoparticle solution prepared in step 2 is spin-coated onto the FTO substrate surface at a spin speed of 2500-4000 rpm for 40 s. Following this, annealing is performed at 100 ℃ for 30-40 min to obtain the SnO2 electron transport layer. Before spin-coating the 2S + RM257 mixed solution, the FTO / SnO2 substrate is treated with ultraviolet ozone for 10-15 min.

[0034] Step 4: Prepare a 2S+RM257 mixture layer; The 2S+RM257 mixed solution prepared in step 2 was spin-coated onto the surface of the SnO2 electron transport layer obtained in step 3. The spin-coating speed was 2000-4000 rpm, and the spin-coating time was 30 s. Annealing was then performed at 100 ℃ for 8-12 min to obtain the 2S+RM257 mixed layer. Before spin-coating the perovskite precursor solution, the FTO / SnO2 / 2S+RM257 substrate was treated with UV ozone for 10-15 min.

[0035] Step 5, prepare FA 0.9 Cs 0.1 PbI3 perovskite precursor solution; A 1.0 M formamidin hydroiodide (FAI), cesium iodide (CsI), and lead iodide (PbI2) (molar ratio = 0.9:0.1:1.0) was dissolved in a mixed solvent of DMF and DMSO (V / V = 8.5:1.5) to prepare FAI solution. 0.9 Cs 0.1 PbI3 perovskite precursor solution: Stir the perovskite precursor solution for 6-12 h, then filter it using a 0.45 μm filter cartridge for later use.

[0036] Step 6, Prepare FA 0.9 Cs 0.1 PbI3 perovskite light-absorbing layer; The perovskite precursor solution prepared in step 5 was spin-coated onto the surface of an FTO / SnO2 / 2S+RM257 substrate. The spin-coating process consisted of two stages: the first stage involved a spin speed of 1000-2000 rpm for 10 seconds; the second stage involved a spin speed of 4000-5000 rpm for 30 seconds. Annealing was then performed at a temperature of 120°C. o C, annealing time is 30-40 min. After annealing, FTO / SnO2 / 2S+RM257 / FA is formed. 0.9 Cs 0.1 The perovskite light-absorbing layer prepared by PbI3 is 500-550 nm.

[0037] Step 7: Prepare the hole transport layer; The hole transport layer was prepared using Spiro-OMeTAD. Spiro-OMeTAD powder (90 mg), lithium salt (22 μL), and t-BP (36 μL) were dissolved in 1 mL of chlorobenzene to obtain a Spiro-OMeTAD solution. The Spiro-OMeTAD solution was spin-coated onto the perovskite film prepared in step 6 at 5000 rpm for 30 s to form the hole transport layer, yielding FTO / SnO2 / 2S+RM257 / FA. 0.9 Cs 0.1 PbI3 / Spiro-OMeTAD.

[0038] Step 8: Prepare the metal electrode; In step 7, a gold electrode with a thickness of approximately 80 nm is deposited on the surface of the hole transport layer to obtain a structure of FTO / SnO2 / 2S+RM257 / FA. 0.9 Cs 0.1 PbI3 / Spiro-OMeTAD / Au perovskite solar cells.

[0039] A second aspect of the present invention discloses an FA prepared by the above method. 0.9 Cs 0.1 PbI3 perovskite solar cell structure, see Figure 2 From bottom to top: FTO conductive glass, SnO2 electron transport layer, 2S+RM257 mixture layer, FA 0.9 Cs 0.1 PbI3 perovskite light-absorbing layer, Spiro-OMeTAD hole transport layer, and metal electrode.

[0040] The invention will be further described in detail below with reference to specific examples: Example 1 Step 1, Cleaning the FTO glass substrate: Cut the FTO glass to a size of 2.5 × 2.5 cm, place it in an ultrasonic cleaner, and clean it with glass cleaner and ultrapure water (glass cleaner: ultrapure water = 1:100) for 30 minutes. Then change the ultrapure water every 30 minutes, repeating this step 3 times. After cleaning, dry the FTO glass with compressed air, and then treat it with ultraviolet ozone for 15 minutes before use.

[0041] Step 2: Prepare the SnO2 electron transport layer precursor solution and the 2S+RM257 mixed solution. The SnO2 electron transport layer precursor solution is prepared by dissolving SnO2 colloidal nanoparticles in deionized water (V / V=1:6) and stirring for 4-8 h. The 2S+RM257 mixed solution is prepared by dissolving 0.20 mg of 2S+RM257 solid in 1 mL of chlorobenzene and stirring at room temperature for 30-60 min to obtain a 0.20 mg / mL 2S+RM257 solution. Filter the solution with a 0.45 μm filter before use.

[0042] Step 3, Preparation of the SnO2 electron transport layer: The SnO2 colloidal nanoparticle solution prepared in Step 2 was spin-coated onto the surface of the FTO substrate at a spin speed of 3000 rpm for 40 s. Following this, annealing was performed at 100℃ for 40 min to obtain the SnO2 electron transport layer. Before spin-coating the 2S + RM257 mixed solution, the FTO / SnO2 substrate was treated with UV ozone for 15 min.

[0043] Step 4, Preparation of the 2S+RM257 mixed layer: The 2S+RM257 mixed solution prepared in Step 2 was spin-coated onto the surface of the SnO2 electron transport layer obtained in Step 3. The spin-coating speed was 3000 rpm and the spin-coating time was 30 s. Subsequently, annealing was performed at a temperature of 100 ℃ for 10 min to obtain the 2S+RM257 mixed layer. Before spin-coating the perovskite precursor solution, the FTO / SnO2 / 2S+RM257 substrate was treated with ultraviolet ozone for 15 min.

[0044] Step 5, prepare FA 0.9 Cs 0.1 PbI3 perovskite precursor solution: A 1.0 M FA solution was prepared by dissolving formamidinium hydroiodate (FAI), cesium iodide (CsI), and lead iodide (PbI2) (molar ratio = 0.9:0.1:1.0) in a mixed solvent of DMF and DMSO (V / V = 8.5:1.5). 0.9 Cs 0.1 PbI3 perovskite precursor solution: Stir the perovskite precursor solution for 6-12 h, then filter it using a 0.45 μm filter cartridge for later use.

[0045] Step 6, Prepare FA 0.9 Cs 0.1PbI3 perovskite light-absorbing layer: The perovskite precursor solution prepared in step 5 was spin-coated onto the surface of an FTO / SnO2 / 2S+RM257 substrate. The spin-coating process consisted of two stages: the first stage was at 1000 rpm for 10 s; the second stage was at 5000 rpm for 30 s. Annealing was then performed at 120°C. o C, annealing time is 30 min. After annealing, FTO / SnO2 / 2S+RM257 / FA is formed. 0.9 Cs 0.1 PbI3 perovskite light-absorbing layer.

[0046] Step 7, Preparation of the hole transport layer: The hole transport layer was prepared using Spiro-OMeTAD. Spiro-OMeTAD powder (90 mg), lithium salt (22 μL), and t-BP (36 μL) were dissolved in 1 mL of chlorobenzene to obtain a Spiro-OMeTAD solution. The Spiro-OMeTAD solution was spin-coated onto the perovskite film prepared in Step 6 at 5000 rpm for 30 s to form the hole transport layer, yielding FTO / SnO2 / 2S+RM257 / FA. 0.9 Cs 0.1 PbI3 / Spiro-OMeTAD.

[0047] Step 8, fabrication of the metal electrode: Gold with a thickness of approximately 80 nm is deposited on the surface of the hole transport layer prepared in step 7 as the metal electrode, resulting in a structure of FTO / SnO2 / 2S+RM257 / FA. 0.9 Cs 0.1 A PbI3 / Spiro-OMeTAD / Au perovskite solar cell. The effective active area of ​​the cell is 0.09 cm². 2 The effective area is 0.09 cm². 2 Devices are fabricated using photomasks.

[0048] In this example, a SnO2-based perovskite solar cell modified with 0.20 mg / mL 2S+RM257 was prepared.

[0049] like Figure 2 The diagram shows a perovskite solar cell modified with a liquid crystal mixture, where, from bottom to top, the layers are: FTO conductive glass, SnO2 electron transport layer, 2S+RM257 mixture layer, and FA... 0.9 Cs 0.1 The structure consists of a PbI3 perovskite light-absorbing layer, a Spiro-OMeTAD hole transport layer, and a gold electrode. The concentration of 2S+RM257 is 0.20 mg / mL.

[0050] like Figure 3 As shown, SEM testing of the perovskite film modified with 2S+RM257 on the surface of the SnO2 electron transport layer reveals that the crystallinity of the perovskite film is enhanced, the average grain size is significantly increased, and the surface is smoother after modification with 2S+RM257. This indicates a reduction in grain boundaries, which is beneficial for suppressing the formation of grain boundary defect sites in the perovskite film.

[0051] like Figure 4 As shown, after modifying the surface of the SnO2 electron transport layer with 2S+RM257, the intensity of the PL peak of the perovskite film is significantly reduced, indicating that the extraction efficiency of photogenerated electrons from the perovskite layer to the electron transport layer is improved, and the defects and non-radiative recombination inside the perovskite film are reduced.

[0052] like Figure 5 As shown, the average carrier lifetime of the film was shortened after modifying the SnO2 electron transport layer surface with 2S+RM257. The optimized film successfully suppressed the non-radiative recombination channel at the interface, further demonstrating that the 2S+RM257 modification helps the extraction and transport of electrons from the perovskite to the electron transport layer.

[0053] like Figure 6 The figure illustrates the interaction between 2S+RM257 and PbI2. As can be seen from the figure, Pb 4f in the mixed sample of 2S+RM257 and PbI2... 5 / 2 and Pb 4f 7 / 2 The shift of both peaks towards lower binding energies indicates a change in the chemical environment surrounding Pb 4f, suggesting that 2S+RM257 binds to uncoordinated Pb via a Lewis acid-base reaction. 2+ They interact with each other, passivating defects on the surface of the perovskite thin film.

[0054] like Figure 7 As shown, the conduction band and Fermi level of the SnO2 film are improved after modification with 2S+RM257, which helps to reduce the potential barrier for electron transfer, reduce nonradiative recombination loss at the interface, significantly enhance the charge transport and extraction efficiency of the device, and thus improve the open-circuit voltage of the device.

[0055] like Figure 8 As shown, the trap fill limit voltage of the perovskite solar cell device after modification with 2S+RM257 is ( V TFL The 2S+RM257 optimization significantly reduces defects in perovskite films, exhibiting the lowest defect state density in the electron transport path. This indicates that the optimization of 2S+RM257 significantly reduces defects in perovskite films, which is beneficial for suppressing defect-assisted nonradiative recombination processes.

[0056] like Figure 9As shown, after modifying the SnO2 electron transport layer surface with 2S+RM257, the fill factor and open-circuit voltage of the perovskite solar cell increased significantly, reaching 83.72% and 1.21 V, respectively, and the photoelectric conversion efficiency of the fabricated device reached as high as 25.89%.

[0057] like Figure 10 As shown, the stability of the perovskite solar cell device modified with 2S+RM257 in air was tested. The device modified with 2S+RM257 can still maintain 95% of the initial photoelectric conversion efficiency after 3000 h of aging, showing excellent environmental stability.

[0058] Comparative Example 1 Compared with Example 1, Comparative Example 1 differs in the operation of steps 2 and 4. Specifically, in step 2, the 2S + RM257 mixed solution was not prepared in Comparative Example 1, and in step 4, the 2S + RM257 modification layer was not spin-coated; all other steps and parameters were the same.

[0059] Figure 3 This paper presents a comparison of SEM scans of perovskite films before and after modification with 2S+RM257 on the surface of the SnO2 electron transport layer. After modification, the grain size of the film increases and the grain boundaries decrease. This is due to the ordered crystal orientation induced by the self-assembly characteristics of the liquid crystal material during film growth.

[0060] Figure 4 The steady-state photoluminescence (PL) spectra of perovskite films before and after modification with 2S+RM257 on the surface of the SnO2 electron transport layer are presented. The modified sample exhibits a significant fluorescence quenching effect, with a lower PL peak intensity compared to the unmodified system, significantly improving the cross-interface transport efficiency of photogenerated electrons.

[0061] Figure 5 The TRPL spectra of perovskite films before and after modification with 2S+RM257 on the surface of the SnO2 electron transport layer are shown. The 2S+RM257 modification optimizes the interfacial contact between the SnO2 electron transport layer and the perovskite, reduces interfacial defects, and enables electrons to transfer more quickly from the perovskite layer to SnO2, thereby reducing the residence time of charge carriers in the perovskite layer, which is manifested as accelerated TRPL decay.

[0062] Figure 7 The comparison of UPS before and after SnO2 film modification with 2S+RM257 is shown. After modification with 2S+RM257, SnO2 film has higher conduction band and Fermi level. At the same time, the optimized SnO2 film also has a more matching energy level arrangement with perovskite, which is conducive to reducing the electron transfer barrier and improving the open circuit voltage of the device.

[0063] Figure 8The dark state of perovskite solar cells before and after modification of the SnO2 electron transport layer surface with 2S+RM257 is shown. JV The curve, compared to the unmodified device, shows that after modification with 2S+RM257, the device's... V TFL The density of defect states is reduced, effectively suppressing nonradiative recombination.

[0064] Figure 9 This demonstrates perovskite solar cells before and after surface modification with 2S+RM257 on the SnO2 electron transport layer. JV The curves and specific parameters are shown in Table 1. After modification with 2S+RM257, the fill factor and open-circuit voltage of the perovskite solar cell both increased to 83.72% and 1.21 V, respectively, and the photoelectric conversion efficiency of the device reached 25.89%.

[0065] Table 1

[0066] Figure 10 The stability of device efficiency between unmodified and modified 2S+RM257 devices was demonstrated at an air temperature of 25 ℃ and a humidity of approximately 25-30%. Compared with the unmodified device, the device modified with 2S+RM257 still retains 95% of its initial efficiency after 3000 h.

[0067] Comparative Example 2 Comparative Example 2 differs from Example 1 in the operations of steps 2 and 4. Specifically, in Comparative Example 2, a 2S solution was prepared in step 2, and a 2S modified layer was spin-coated in step 4; all other steps and parameters were the same.

[0068] Figure 3 The SEM scans of perovskite films before and after modification with 2S on the SnO2 electron transport layer are shown. After modification, the grain size of the film increases, but is smaller than that of the film modified with 2S+RM257. Similarly, the number of grain boundaries decreases, weakening the non-radiative recombination channels at the grain boundaries.

[0069] Figure 4 The steady-state photoluminescence (PL) spectra of perovskite films before and after modification with 2S on the surface of the SnO2 electron transport layer are presented. The modified sample exhibits a lower PL intensity, but it is slightly stronger than that of the 2S+RM257 modified film, indicating that the radiative recombination probability of the system decreases or the non-radiative recombination probability increases.

[0070] Figure 5 TRPL spectra of perovskite films before and after 2S modification on the SnO2 electron transport layer surface are shown. Compared with the unmodified film, the 2S-modified perovskite film exhibits a reduced carrier lifetime and weakens defect-assisted nonradiative recombination.

[0071] Figure 7 The comparison of UPS before and after 2S modification of SnO2 film is shown. After 2S modification, the conduction band and Fermi level of SnO2 film are improved, which is conducive to electron transfer and helps to improve the open circuit voltage of the device.

[0072] Figure 8 The dark state of perovskite solar cells before and after modification of the SnO2 electron transport layer surface with 2S is shown. JV The curve, compared to the unmodified device, shows that after 2S modification, the device's... V TFL It also decreased, but was higher than that of the 2S+RM257 modified device, with a similar reduction in defect state density.

[0073] Figure 9 This demonstrates perovskite solar cells before and after surface modification with 2S on the SnO2 electron transport layer. JV The curves show that the fill factor and open-circuit voltage of the perovskite solar cell after 2S modification both increased to 81.98% and 1.19 V, respectively, and the photoelectric conversion efficiency of the device was 24.97%.

[0074] Figure 10 The stability of device efficiency between unmodified and 2S-modified devices was demonstrated at a temperature of 25 °C and a humidity of approximately 25-30%. Compared with the unmodified device, the 2S-modified device still retained 89% of its initial efficiency after 3000 h.

[0075] Example 2 In this embodiment, a 0.05 mg / mL 2S+RM257 mixed solution was spin-coated onto the surface of an FTO / SnO2 substrate. The perovskite solar cell modified with 0.05 mg / mL 2S+RM257 achieved an open-circuit voltage of 1.18 V, a fill factor of 81.73%, and a capacitance of 25.24 mA / cm². 2 The current density is 24.35%, and the photoelectric conversion efficiency is 24.35%. Parameters and steps not involved in this embodiment are the same as in Embodiment 1.

[0076] Example 3 In this embodiment, a 0.10 mg / mL 2S+RM257 mixed solution was spin-coated onto the surface of an FTO / SnO2 substrate. The perovskite solar cell modified with 0.10 mg / mL 2S+RM257 achieved an open-circuit voltage of 1.20 V, a fill factor of 82.94%, and a capacitance of 25.37 mA / cm². 2 The current density is 25.26%, and the photoelectric conversion efficiency is 25.26%. Parameters and steps not involved in this embodiment are the same as in Embodiment 1.

[0077] Example 4 In this embodiment, a 0.40 mg / mL 2S+RM257 mixed solution was spin-coated onto the surface of an FTO / SnO2 substrate. The perovskite solar cell modified with 0.40 mg / mL 2S+RM257 achieved an open-circuit voltage of 1.19 V, a fill factor of 83.27%, and a capacity of 25.56 mA / cm². 2 The current density is 25.33%, and the photoelectric conversion efficiency is 25.33%. Parameters and steps not involved in this embodiment are the same as in Embodiment 1.

[0078] Example 5 In this embodiment, the spin coating speed for the 2S+RM257 mixed solution was 2000 rpm and the spin coating time was 30 s. All parameters and steps not involved in this embodiment were the same as those in Example 1.

[0079] Example 6 In this embodiment, the spin coating speed for the 2S+RM257 mixed solution is 4000 rpm and the spin coating time is 30 s. All parameters and steps not involved in this embodiment are the same as those in Example 1.

[0080] Example 7 In this embodiment, after spin-coating the 2S+RM257 mixed solution, annealing is performed at a temperature of 100 ℃ for 8 min. Parameters and steps not involved in this embodiment are the same as in Example 1.

[0081] Example 8 In this embodiment, after spin-coating the 2S+RM257 mixed solution, annealing is performed at a temperature of 100 ℃ for 12 min. Parameters and steps not involved in this embodiment are the same as in Example 1.

[0082] Example 9 In this embodiment, 2S+RM257 is added directly to the perovskite precursor solution as an additive.

[0083] Step 1, Cleaning the FTO glass substrate: Cut the FTO glass to a size of 2.5 × 2.5 cm, place it in an ultrasonic cleaner, and clean it with glass cleaner and ultrapure water (glass cleaner: ultrapure water = 1:100) for 30 minutes. Then change the ultrapure water every 30 minutes, repeating this step 3 times. After cleaning, dry the FTO glass with compressed air, and then treat it with ultraviolet ozone for 15 minutes before use.

[0084] Step 2, Preparation of SnO2 electron transport layer precursor solution: Method for preparing SnO2 electron transport layer precursor solution: Dissolve an appropriate amount of SnO2 colloidal nanoparticles (V / V=1:6) in deionized water, stir at room temperature for 6-8 h to ensure uniform mixing, and then set aside.

[0085] Step 3, Preparation of the SnO2 electron transport layer: The SnO2 colloidal nanoparticle solution prepared in Step 2 was spin-coated onto the surface of the FTO substrate at a spin speed of 3000 rpm for 40 s. Following this, annealing was performed at 100℃ for 40 min to obtain the SnO2 electron transport layer. Before spin-coating the perovskite precursor solution, the FTO / SnO2 substrate was treated with UV ozone for 15 min.

[0086] Step 4, prepare FA 0.9 Cs 0.1 PbI3 perovskite precursor solution: Formamidinium hydroiodate (FAI), cesium iodide (CsI), lead iodide (PbI2) (molar ratio = 0.9:0.1:1.0) and 0.5 mg of 2S+RM257 solid were dissolved in a mixed solvent of DMF and DMSO (V / V = 8.5:1.5) to prepare a 1.0 M FAI solution. 0.9 Cs 0.1 The PbI3 bulk doped perovskite precursor solution was stirred at room temperature for 6-12 h, and then filtered using a 0.45 μm filter cartridge for later use.

[0087] Step 5, Prepare FA 0.9 Cs 0.1 PbI3 perovskite light-absorbing layer: The bulk-doped perovskite precursor solution prepared in step 4 was spin-coated onto the surface of an FTO / SnO2 substrate. The spin-coating process was completed in two stages: the first stage was at a spin speed of 1000 rpm for 10 s; the second stage was at a spin speed of 5000 rpm for 30 s. Annealing was then performed at a temperature of 120°C. o C, annealing time is 30 min. After annealing, FTO / SnO2 / FA is formed. 0.9 Cs 0.1 PbI3 (2S+RM257) thin film.

[0088] Step 6, Preparation of the hole transport layer: The hole transport layer was prepared using Spiro-OMeTAD. Spiro-OMeTAD powder (90 mg), lithium salt (22 μL), and t-BP (36 μL) were dissolved in 1 mL of chlorobenzene and stirred at room temperature in the dark for 12 h to prepare a Spiro-OMeTAD solution. The Spiro-OMeTAD solution was spin-coated onto the perovskite film prepared in step 5 at 5000 rpm for 30 s to form the hole transport layer, resulting in a structure of FTO / SnO2 / FA. 0.9 Cs 0.1 Thin film of PbI3(2S+RM257) / Spiro-OMeTAD.

[0089] Step 7, fabrication of metal electrode: Gold with a thickness of approximately 80 nm is deposited on the surface of the hole transport layer prepared in step 6 as the metal electrode, resulting in a structure of FTO / SnO2 / FA. 0.9 Cs 0.1 A perovskite solar cell using PbI3(2S+RM257) / Spiro-OMeTAD / Au. The effective active area of ​​the cell is 0.09 cm². 2 The effective area is 0.09 cm². 2 Devices are fabricated using photomasks.

[0090] In this example, a 0.5 mg / mL 2S+RM257 perovskite bulk-phase doped perovskite solar cell was obtained.

[0091] Example 10 1.0 mg of 2S+RM257 was used as an additive in the perovskite precursor solution, and the preparation method was the same as step 4 in Example 9. The resulting perovskite bulk-phase doped perovskite solar cell had a concentration of 1.0 mg / mL 2S+RM257. Parameters and steps not mentioned in this example were the same as in Example 9.

[0092] Example 11 3.0 mg of 2S+RM257 was used as an additive in the perovskite precursor solution, and the preparation method was the same as step 4 in Example 9. The resulting perovskite bulk-phase doped perovskite solar cell had a concentration of 3.0 mg / mL 2S+RM257. Parameters and steps not mentioned in this example were the same as in Example 9.

[0093] Example 12 5.0 mg of 2S+RM257 was used as an additive in the perovskite precursor solution, and the preparation method was the same as step 4 in Example 9. The resulting perovskite bulk-phase doped perovskite solar cell had a concentration of 5.0 mg / mL 2S+RM257. Parameters and steps not mentioned in this example were the same as in Example 9.

[0094] Example 13 In this embodiment, SnO2 is no longer used as the electron transport layer; instead, TiO2 is used.

[0095] Step 1, Cleaning the FTO glass substrate: Cut the FTO glass to a size of 2.5 × 2.5 cm, place it in an ultrasonic cleaner, and clean it with glass cleaner and ultrapure water (glass cleaner: ultrapure water = 1:100) for 30 minutes. Then change the ultrapure water every 30 minutes, repeating this step 3 times. Dry the cleaned FTO glass with an air compressor and place it in a dried petri dish. Test its conductive side with a multimeter, and fix it in the petri dish with the conductive side facing up for later use.

[0096] Step 2, Preparation of the TiO2 electron transport layer: The FTO glass cleaned in Step 1 was treated with ultraviolet ozone for 15 min. TiO2 was deposited by chemical deposition. 4.5 mL of TiCl4 was dropped onto 200 mL of ice. After the ice melted to the size of a little finger, it was placed in a 70 ℃ oven for 60 min for deposition, followed by annealing. The thickness of the prepared TiO2 electron transport layer was approximately 40-50 nm. It was treated with ultraviolet ozone for 15 min before use.

[0097] Step 3, prepare a 2S+RM257 mixed solution: Dissolve 0.20 mg of 2S+RM257 solid in 1 mL of chlorobenzene, stir at room temperature for 30-60 min to obtain a 2S+RM257 solution with a concentration of 0.20 mg / mL, and filter it with a 0.45 μm filter before use.

[0098] Step 4, Preparation of the 2S+RM257 mixed layer: The 2S+RM257 mixed solution prepared in Step 3 was spin-coated onto the surface of the TiO2 electron transport layer obtained in Step 2. The spin-coating speed was 3000 rpm and the spin-coating time was 30 s. Subsequently, annealing was performed at a temperature of 100 ℃ for 10 min to obtain the 2S+RM257 mixed layer. Before spin-coating the perovskite precursor solution, the FTO / TiO2 / 2S+RM257 substrate was treated with ultraviolet ozone for 15 min.

[0099] Step 5, prepare FA 0.9 Cs 0.1PbI3 perovskite precursor solution: A 1.0 M FA solution was prepared by dissolving formamidinium hydroiodate (FAI), cesium iodide (CsI), and lead iodide (PbI2) (molar ratio = 0.9:0.1:1.0) in a mixed solvent of DMF and DMSO (V / V = 8.5:1.5). 0.9 Cs 0.1 PbI3 perovskite precursor solution: Stir the perovskite precursor solution for 6-12 h, then filter it using a 0.45 μm filter cartridge for later use.

[0100] Step 6, Prepare FA 0.9 Cs 0.1 PbI3 perovskite light-absorbing layer: The perovskite precursor solution prepared in step 5 was spin-coated onto the surface of an FTO / TiO2 / 2S+RM257 substrate. The spin-coating process consisted of two stages: the first stage was at 1000 rpm for 10 s; the second stage was at 5000 rpm for 30 s. Annealing was then performed at 120°C. o C, annealing time is 30 min. After annealing, FTO / TiO2 / 2S+RM257 / FA is formed. 0.9 Cs 0.1 PbI3 perovskite light-absorbing layer.

[0101] Step 7, Preparation of the hole transport layer: The hole transport layer was prepared using Spiro-OMeTAD. Spiro-OMeTAD powder (90 mg), lithium salt (22 μL), and t-BP (36 μL) were dissolved in 1 mL of chlorobenzene to obtain a Spiro-OMeTAD solution. The Spiro-OMeTAD solution was spin-coated onto the perovskite film prepared in Step 6 at 5000 rpm for 30 s to form the hole transport layer, yielding FTO / TiO2 / 2S+RM257 / FA. 0.9 Cs 0.1 PbI3 / Spiro-OMeTAD.

[0102] Step 8, fabrication of the metal electrode: Gold with a thickness of approximately 80 nm is deposited on the surface of the hole transport layer prepared in step 7 as the metal electrode, resulting in a structure of FTO / TiO2 / 2S+RM257 / FA. 0.9 Cs 0.1 A PbI3 / Spiro-OMeTAD / Au perovskite solar cell. The effective active area of ​​the cell is 0.09 cm². 2 The effective area is 0.09 cm². 2 Devices are fabricated using photomasks.

[0103] In this example, a TiO2-based perovskite solar cell modified with 0.20 mg / mL 2S+RM257 was prepared. The prepared perovskite solar cell achieved an open-circuit voltage of 1.19 V, a fill factor of 82.16%, and a capacity of 25.51 mA / cm². 2 The current density is 24.86%, and the photoelectric conversion efficiency is 24.86%.

[0104] Comparative Example 3 Comparative Example 3 differs slightly from Example 13 in that it does not include the spin-coating of the 2S+RM257 modification layer; all other steps and parameters are the same. The prepared perovskite solar cell achieved an open-circuit voltage of 1.16 V, a fill factor of 79.43%, and a flux density of 24.92 mA / cm². 2 The current density is 22.96%, and the photoelectric conversion efficiency is 22.96%. Comparing the results of Example 13 and Comparative Example 3, it can be seen that all data in Example 13 are superior to those in Comparative Example 3.

[0105] Example 14 In this embodiment, a 0.05 mg / mL 2S+RM257 mixed solution was spin-coated onto the surface of an FTO / TiO2 substrate. The perovskite solar cell modified with 0.05 mg / mL 2S+RM257 achieved an open-circuit voltage of 1.17 V, a fill factor of 80.78%, and a capacitance of 25.16 mA / cm². 2 The current density is 23.74%, and the photoelectric conversion efficiency is 23.74%. Parameters and steps not involved in this embodiment are the same as in Embodiment 13.

[0106] Example 15 In this embodiment, a 0.10 mg / mL 2S+RM257 mixed solution was spin-coated onto the surface of an FTO / TiO2 substrate. The perovskite solar cell modified with 0.10 mg / mL 2S+RM257 achieved an open-circuit voltage of 1.17 V, a fill factor of 81.66%, and a capacitance of 25.54 mA / cm². 2 The current density is 24.42%, and the photoelectric conversion efficiency is 24.42%. Parameters and steps not involved in this embodiment are the same as in Embodiment 13.

[0107] Example 16 In this embodiment, a 0.40 mg / mL 2S+RM257 mixed solution was spin-coated onto the surface of an FTO / TiO2 substrate. The perovskite solar cell modified with 0.40 mg / mL 2S+RM257 achieved an open-circuit voltage of 1.17 V, a fill factor of 81.55%, and a capacitance of 25.80 mA / cm². 2 The current density is 24.65%, and the photoelectric conversion efficiency is 24.65%. Parameters and steps not involved in this embodiment are the same as in Embodiment 13.

[0108] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A liquid crystal mixture, characterized in that, The liquid crystal mixture is a mixture of 2,2-dithiodiethanol diacrylate and 1,4-bis-[4-(3-acryloyloxypropoxy)benzoyloxy]-2-methylbenzene, with the following structural formula: 。 2. The liquid crystal mixture according to claim 1, characterized in that, The mixing ratio of 2-dithiodiethanol diacrylate and 1,4-bis-[4-(3-acryloyloxypropoxy)benzoyloxy]-2-methylbenzene is 5:

95.

3. A method for preparing a liquid crystal mixture according to claim 1, characterized in that, Includes the following steps: Using bis(2-hydroxyethyl) disulfide, triethylamine, and dichloromethane as raw materials, acryloyl chloride was added dropwise under ice bath conditions. After post-treatment and column chromatography, 2,2-dithiodiethanol diacrylate was obtained. 2,2-dithiodiethanol diacrylate and 1,4-bis-[4-(3-acryloyloxypropoxy)benzoyloxy]-2-methylbenzene were dissolved in dichloromethane, mixed evenly, and dried to obtain a liquid crystal mixture.

4. A method for preparing a perovskite solar cell, characterized in that, Includes the following steps: S1. SnO2 colloidal aqueous solution is spin-coated onto FTO conductive glass to prepare a SnO2 electron transport layer; S2, dissolve the liquid crystal mixture of claim 1 in chlorobenzene to prepare a modification layer solution with a concentration of 0.05-0.40 mg / mL, spin-coat it onto the SnO2 electron transport layer, and anneal it to form a liquid crystal mixture layer; S3, FA 0.9 Cs 0.1 PbI3 perovskite precursor solution was spin-coated onto a liquid crystal mixture layer and annealed to obtain FA. 0.9 Cs 0.1 PbI3 perovskite light-absorbing layer; S4, in FA 0.9 Cs 0.1 Spiro fabrication on PbI3 perovskite light-absorbing layer OMeTAD hole transport layer; S5, in Spiro A metal layer was fabricated on the OMeTAD hole transport layer to obtain a perovskite solar cell.

5. The method for preparing a perovskite solar cell according to claim 4, characterized in that, In S2, the spin coating speed is 2000-4000 rpm and the spin coating time is 30 s.

6. The method for preparing a perovskite solar cell according to claim 4, characterized in that, In S2, the annealing temperature is 100 ℃ and the annealing time is 8-12 min.

7. The method for preparing a perovskite solar cell according to claim 4, characterized in that, In S3, the perovskite precursor solution is a mixed solution formed by dissolving formamidine hydroiodate, cesium iodide, and lead iodide in DMF and DMSO.

8. The method for preparing a perovskite solar cell according to claim 4, characterized in that, In S3, the concentration of the perovskite precursor solution is 1.0 M.

9. The method for preparing a perovskite solar cell according to claim 4, characterized in that, In S3, FA 0.9 Cs 0.1 The preparation process of the PbI3 perovskite absorber layer is divided into two stages. In the first stage, the spin coating speed is 1000-2000 rpm and the spin coating time is 10 s. In the second stage, the spin coating speed is 4000-5000 rpm and the spin coating time is 30 s.

10. A perovskite solar cell with an optimized electron transport layer prepared by any one of claims 5-9, characterized in that, It includes, from bottom to top, a conductive glass layer, an electron transport layer, a liquid crystal mixture layer, a perovskite light-absorbing layer, a hole transport layer, and a metal electrode.

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