Preparation of Perovskite Solar Cells by One-Step Spin Coating of Self-Assembled Small Molecules

Abstract

Preparation of perovskite solar cells by one-step spin coating of self-assembled small molecules. The self-assembled small molecules are directly added to the perovskite precursor solution to simultaneously prepare the hole transport layer and the perovskite layer in one step. The synthesis steps of the used self-assembled small molecules are simple, and the overall preparation cost is low, enabling large-scale synthesis of materials. At the same time, the one-step spin coating process also avoids the influence of the wettability of the underlying hole transport layer on the growth of the perovskite film. The prepared inverted perovskite solar cells exhibit an efficiency exceeding 21%, and at the same time, they also have good stability, remaining more than 90% of the initial efficiency after being stored in a glove box for 1600 h, far superior to the devices prepared by traditional layer-by-layer spin coating. This shows that the present invention not only simplifies the device preparation process, but also improves the battery efficiency and stability, providing inspiration and reference for the commercial development of perovskite solar cells.

Description

Technical Field

[0001] The present invention relates to the technical field of the preparation of organic-inorganic lead halide perovskite solar cells, and particularly to the preparation of perovskite solar cells by one-step spin coating of self-assembled small molecules. Background Art

[0002] Converting light energy into electrical energy using solar cells is an important way to alleviate the energy crisis. Currently, the preparation process of mainstream silicon-based solar cells in the market has high energy consumption and great difficulty in improving efficiency, which has given rise to the research on a new generation of photovoltaic technologies. In the past decade, solar cells with perovskite as the light absorption layer have developed rapidly, and the single-junction efficiency has exceeded 25%. Simplifying the preparation process while improving the device efficiency and stability is of great significance for its commercialization process.

[0003] Among different perovskite solar cells (PSCs), inverted devices have received increasing attention due to their mild preparation process and suitability for tandem cells. A common inverted PSC consists of a conductive glass substrate (ITO), a hole transport layer (HTL), a perovskite layer, an electron transport layer, and a metal electrode. Among them, the hole transport layer is responsible for extracting and transporting photo-generated holes, and has an important impact on the device efficiency and stability. Currently, the commonly used hole transport material poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA) is expensive (>2000 yuan / gram) and has a low intrinsic hole mobility, which limits the development of inverted PSCs. On the other hand, currently, high-efficiency PSCs all use the method of spin coating layer by layer to prepare the HTL. This not only makes the preparation process more complicated, but also wastes a large amount of time and solvents (the preparation and spin coating of the HTL solution), increasing the equipment and time costs of industrial production. In addition, the poor surface wettability of the HTL during layer-by-layer spin coating makes it very difficult to grow a high-quality perovskite film, especially when the device size is enlarged (>1 cm 2 ). Seeking a simple method to solve these problems simultaneously is crucial for promoting the commercialization of PSCs.

[0004] In recent years, self-assembled hole transport materials with anchoring groups (such as acetate groups, borate groups, mercapto groups, phosphonic acid groups, etc.) have attracted much attention and have been widely used in single-junction organic solar cells (OSCs), PSCs, and tandem devices. They can be spontaneously and orderly anchored on the ITO surface by dehydration condensation of the anchoring group with the hydroxyl groups on the surface of the indium tin oxide (ITO) substrate, changing the ITO work function while enhancing the interfacial charge transport, thereby improving the device efficiency. However, such HTLs are still prepared by the method of spin coating layer by layer. On the one hand, there are problems such as poor solubility and difficult solution preparation; on the other hand, their poor surface wettability still restricts the growth of the upper perovskite. Therefore, reasonable molecular design combined with optimized device preparation processes is imperative. Summary of the Invention

[0005] The object of the present invention is to solve the above problems in the prior art, and provide a preparation method of a perovskite solar cell by one-step spin coating of self-assembled small molecules. A self-assembled small molecule containing an anchoring group (such as acetate group, borate group, mercapto group, phosphonic acid group, etc.) is added to the perovskite precursor solution to simultaneously prepare a hole transport layer and a perovskite layer in one step. This has important reference value for simplifying the preparation steps and improving the efficiency and stability of the device.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] 1. The self-assembled small molecule containing an anchoring group (such as acetate group, borate group, mercapto group, phosphonic acid group, etc.) has the following structural characteristics:

[0008]

[0009] 2. Taking the self-assembled molecule 4-(10-bromo-7H-benzo[c]carbazol-7-yl)butyl)phosphonic acid (BCB10Br-C4PA) containing a phosphonate group as an example, its synthesis method is as follows:

[0010]

[0011] (1) Under the catalytic action of an aqueous potassium hydroxide solution and tetrabutylammonium bromide, 10-bromo-7H-benzo[c]carbazole reacts with 1,4-dibromobutane to form 10-bromo-7-(4-bromobutyl)-7H-benzo[c]carbazole;

[0012]

[0013] (2) Under nitrogen protection, 10-bromo-7-(4-bromobutyl)-7H-benzo[c]carbazole reacts with triethyl phosphite to form diethyl (4-(10-bromo-7H-benzo[c]carbazol-7-yl)butyl)phosphonate;

[0014]

[0015] (3) Under nitrogen protection, using anhydrous 1,4-dioxane as the reaction solvent, diethyl (4-(10-bromo-7H-benzo[c]carbazol-7-yl)butyl)phosphonate reacts with trimethylsilyl bromide to form the target product 4-(10-bromo-7H-benzo[c]carbazol-7-yl)butyl)phosphonic acid;

[0016]

[0017] Preferably, in step (1), the molar equivalent of 1,4-dibromobutane relative to 10-bromo-7H-benzo[c]carbazole is 1 to 30 eq, more preferably 10 to 30 eq, and even more preferably 15 to 25 eq. The molar equivalents of potassium hydroxide in tetrabutylammonium bromide and aqueous potassium hydroxide solution relative to 10-bromo-7H-benzo[c]carbazole are 2.0 eq and 5 eq, respectively, wherein the mass concentration of the potassium hydroxide solution is 50%. In this step, 1,4-dibromobutane serves as both a reactant and a solvent, and tetrabutylammonium bromide serves as a phase transfer catalyst.

[0018] Preferably, in step (1), the reaction temperature is 70 °C, and the reaction time is 5 to 20 h, more preferably 5 to 15 h, and even more preferably 10 to 15 h.

[0019] Preferably, in step (1), after the reaction is completed, post-treatment is carried out. The specific method is as follows: naturally cool to room temperature, wash with water, extract with dichloromethane, dry with anhydrous magnesium sulfate, rotary evaporate to remove the solvent, and purify by silica gel column chromatography using a petroleum ether / dichloromethane mixed solution with a volume ratio of 3:1.

[0020] Preferably, in step (2), the molar equivalent of triethyl phosphite relative to 10-bromo-7-(4-bromobutyl)-7H-benzo[c]carbazole is 5 to 30 eq, more preferably 10 to 20 eq, and even more preferably 15 to 25 eq. In this step, triethyl phosphite serves as both a reactant and a solvent.

[0021] Preferably, in step (2), the reaction temperature is 160 °C, and the reaction time is 10 to 30 h, more preferably 10 to 20 h, and even more preferably 15 to 20 h.

[0022] Preferably, in step (2), after the reaction is completed, post-treatment is carried out. The specific method is as follows: naturally cool to room temperature, distill off the solvent under reduced pressure, and purify by silica gel column chromatography using a dichloromethane / ethyl acetate mixed solution with a volume ratio of 3:1.

[0023] Preferably, in step (3), the molar equivalent of trimethylsilyl bromide relative to diethyl (4-(10-bromo-7H-benzo[c]carbazol-7-yl)butyl)phosphonate is 1 to 20 eq, more preferably 5 to 15 eq, and even more preferably 10 to 15 eq.

[0024] Preferably, the specific method of step (3) is as follows: first, under a nitrogen atmosphere, dissolve diethyl (4-(10-bromo-7H-benzo[c]carbazol-7-yl)butyl)phosphonate in anhydrous 1,4-dioxane, and dropwise add trimethylsilyl bromide. Stir the reaction at room temperature for 24 h, then add methanol, and continue to stir at room temperature for 3 h to quench the reaction, followed by post-treatment.

[0025] More preferably, the specific post-treatment method is as follows: rotary evaporation is used to remove part of the solvent, then methanol is added, and then distilled water is added dropwise until the solution becomes opaque, stirred for 12 h, filtered to obtain the solid, and washed with water to obtain the product.

[0026] 3. A method for simultaneously preparing a hole transport layer, a perovskite layer and a solar cell by adding the above-mentioned phosphonate self-assembled small molecule BCB10Br-C4PA to a perovskite precursor solution, the specific steps are as follows:

[0027] (1) Treat the cleaned ITO glass with ultraviolet-ozone to improve wettability;

[0028] (2) Prepare a perovskite Cs 0.07 FA 0.9 MA 0.03 Pb(I 0.92 Br 0.08 )3 precursor solution;

[0029] (3) Add the self-assembled small molecule to the perovskite precursor solution;

[0030] (4) Spin-coat the perovskite precursor solution containing the self-assembled small molecule on the ITO and anneal;

[0031] (5) Then thermally evaporate C60 (C60), 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP) and Ag electrodes in sequence on the prepared perovskite thin film.

[0032] Preferably, in step (1), the ultraviolet-ozone treatment time is 5-30 min, and the more preferred time is 10-20 min.

[0033] Preferably, in step (2), the precursor solvent is a mixed solution of DMF and DMSO.

[0034] Preferably, in step (3), the molar concentration of the added self-assembled small molecule is 0.1-5 M, and the more preferred molar concentration is 1-2 M.

[0035] Preferably, in step (4), the spin-coating speed is 1000-8000 r / min, and the duration is 15-50 s.

[0036] Preferably, in step (5), the thicknesses of C60, BCP and Ag electrodes are 10-60 nm, 2-8 nm, 10-100 nm respectively, and the more preferred thicknesses are 20-50 nm, 5-8 nm, 50-100 nm respectively.

[0037] Compared with the prior art, the beneficial effects obtained by the technical solution of the present invention are:

[0038] The self-assembled hole transport material containing anchoring groups (such as acetate group, borate group, mercapto group, phosphonic acid group, etc.) used in the present invention has simple synthesis steps and low overall preparation cost, and can realize the large-scale synthesis of the material. The hole transport material obtained in the present invention has good solubility in the perovskite precursor, and at the same time, the molecule has a large molecular volume and will not enter the crystal lattice during the crystallization of perovskite; in the present invention, the self-assembled small molecule is directly added to the perovskite precursor, and the hole transport layer and the perovskite layer are prepared by one-step spin coating, which solves the problem of poor surface wettability of the HTL during layer-by-layer spin coating; the inverted PSCs prepared thereby have better efficiency and stability than the devices prepared by traditional layer-by-layer spin coating. This innovation undoubtedly provides an important inspiration for improving the efficiency and stability of inverted PSCs, and at the same time, the simplified preparation steps are also beneficial to reducing the equipment and time costs of industrial production. Brief Description of the Drawings

[0039] Figure 1 It is the preparation flow chart of the organic-inorganic lead halide perovskite solar cell of the present invention.

[0040] Figure 2 It is the nuclear magnetic resonance hydrogen spectrum of BCB10Br-C4PA prepared by the present invention.

[0041] Figure 3 It is the nuclear magnetic resonance carbon spectrum of BCB10Br-C4PA prepared by the present invention.

[0042] Figure 4 It is the ultraviolet-visible absorption spectrum of the BCB10Br-C4PA material solution prepared by the present invention.

[0043] Figure 5 It is the time-of-flight secondary ion mass spectrum of the organic-inorganic lead halide perovskite solar cell prepared by the present invention using BCB10Br-C4PA as the self-assembled hole transport material.

[0044] Figure 6 It is the schematic diagram of the principle of BCB10Br-C4PA anchored on ITO and the one-step spin coating of the HTL and perovskite layer.

[0045] Figure 7 It is the J-V curve of the organic-inorganic lead halide perovskite solar cell prepared by the present invention using BCB10Br-C4PA as the self-assembled hole transport material.

[0046] Figure 8 It is the glove box storage stability of the organic-inorganic lead halide perovskite solar cell prepared by the present invention. Detailed Embodiments

[0047] The present invention will be further described below in conjunction with the drawings and embodiments. It should be noted that the following description is only for explaining the present invention and does not limit its content.

[0048] The synthetic route of the self-assembled small molecule with a phosphonic acid anchoring group of the present invention is as follows:

[0049]

[0050] Synthesis of 4-(10-bromo-7H-benzo[c]carbazol-7-yl)butyl)phosphonic acid (BCB10Br-C4PA)

[0051] (1) Compound 10-bromo-7-(4-bromobutyl)-7H-benzo[c]carbazole (BCB10Br-C4Br)

[0052]

[0053] In a 100 mL reaction tube, the raw materials BCB10Br (1.2 g, 4.05 mmol), 1,2-dibromobutane 9.7 mL, tetrabutylammonium bromide (260.2 mg, 0.81 mmol), and 50% KOH aqueous solution 2.2 mL were added in sequence. Then the temperature was raised to 70 °C and the reaction was carried out overnight. After the reaction was complete by TLC, the reaction mixture was cooled to room temperature, washed with water, and extracted with dichloromethane. Dried over anhydrous magnesium sulfate, concentrated in vacuo, and purified by silica gel column chromatography (petroleum ether / dichloromethane, v / v, 3:1) to obtain BCB10Br-C4Br as a syrup (1.35 g, 77%). 1 H NMR (500 MHz, CDCl3): 8.68–8.62 (m, 2H), 7.99 (d, J = 8.1 Hz, 1H), 7.89 (d, J = 8.9 Hz, 1H), 7.72 (t, J = 7.6 Hz, 1H), 7.55 (m, J = 8.7, 2.2 Hz, 2H), 7.49 (t, J = 7.5 Hz, 1H), 7.35 (d, J = 8.6 Hz, 1H), 4.36 (t, J = 7.0 Hz, 2H), 3.34 (t, J = 6.5 Hz, 2H), 2.03 (m, J = 7.2 Hz, 2H), 1.86 (m, J = 13.2, 6.7 Hz, 2H). 13 C NMR (125 MHz, CDCl3): 138.32, 137.76, 129.78, 129.41, 129.04, 128.19, 127.45, 126.84, 125.12, 124.70, 123.37, 122.99, 114.12, 112.91, 110.58, 42.31, 33.11, 30.13, 28.06.

[0054] (2) Compound Diethyl (4-(10-bromo-7H-benzo[c]carbazol-7-yl)butyl)phosphonate (BCB10Br-C4P)

[0055]

[0056] In a 100 mL reaction tube, the reactants BCB10Br-C4Br (1.3 g, 3.02 mmol) and triethyl phosphite (10.4 mL) were added. The tube was evacuated and purged with nitrogen several times, and then refluxed at 160 °C in an iron sand bath for 16 h. After the reaction was complete as monitored by TLC, the mixture was cooled to room temperature. The reaction mixture was poured into 200 mL of petroleum ether and crystallized at low temperature. The solid was collected by filtration and then washed with petroleum ether to obtain the white solid BCB10Br-C4P (1.31 g, 89%). 1 1H NMR (500 MHz, CDCl3): δ 8.71–8.65 (m, 2H), 8.00 (d, J = 8.1 Hz, 1H), 7.92 (d, J = 8.9 Hz, 1H), 7.72 (t, J = 7.6 Hz, 1H), 7.62 (d, J = 8.9 Hz, 1H), 7.56 (m, J = 8.7, 1.8 Hz, 1H), 7.49 (t, J = 7.5 Hz, 1H), 7.41 (d, J = 8.7 Hz, 1H), 4.43 (t, J = 7.1 Hz, 2H), 4.06–3.96 (m, 4H), 2.01 (t, J = 7.6 Hz, 2H), 1.69 (d, J = 29.6 Hz, 4H), 1.23 (t, J = 7.1 Hz, 6H). 13 13C NMR (125 MHz, CDCl3): δ 138.47, 137.91, 129.86, 129.43, 129.09, 128.22, 127.45, 126.86, 125.19, 124.75, 123.37, 123.03, 114.19, 112.89, 110.71, 61.73, 61.68, 42.86, 30.29, 30.16, 26.08, 24.95, 20.55, 20.51, 16.59, 16.54.

[0057] (3) 4-(10-Bromo-7H-benzo[c]carbazol-7-yl)butyl)phosphonic acid (BCB10Br-C4PA)

[0058]

[0059] Under a nitrogen atmosphere, BCB10Br-C4P (1.10 g, 2.25 mmol) was dissolved in anhydrous 1,4-dioxane (15 mL), and trimethylsilyl bromide (3.0 mL, 22.52 mmol) was added dropwise. The reaction was carried out at room temperature for 24 h. Then, methanol (~2 mL) was added and stirring was continued for 3 h. Part of the solvent was removed by rotary evaporation, then 8 mL of methanol was added, and finally distilled water (15 mL) was added dropwise until the solution became opaque, and the mixture was stirred overnight. The product was filtered out, washed with water, and dried to obtain a white solid BCB10Br-C4PA (0.65 g, 67%). 1 1H NMR (500 MHz, DMSO-d6): 8.75 (t, J = 4.4 Hz, 2H), 8.08 (d, J = 8.1 Hz, 1H), 8.02 (d, J = 8.9 Hz, 1H), 7.96 (d, J = 8.9 Hz, 1H), 7.79 (d, J = 8.7 Hz, 1H), 7.73 (t, J = 7.6 Hz, 1H), 7.61 (d, J = 8.7 Hz, 1H), 7.50 (t, J = 7.5 Hz, 1H), 4.57 (t, J = 7.1 Hz, 2H), 1.88 (m, J = 7.2 Hz, 2H), 1.53 (m, J = 5.6, 3.9 Hz, 4H). 13 13C NMR (125 MHz, DMSO-d6): 138.35, 137.62, 129.22, 129.01, 128.56, 128.04, 127.49, 126.56, 124.17, 123.71, 123.20, 122.91, 112.89, 112.17, 112.10, 111.74, 42.30, 30.09, 29.96, 27.81, 26.72, 20.38, 20.35. MALDI-TOF MS: m / z = 431.0293. [M + , calcd. for C 24 H 22 NO3P: 431.0286.

[0060] The structure of the final product was determined by nuclear magnetic resonance and high-resolution mass spectrometry ( Figures 2-3 ), and the ultraviolet-visible absorption spectrum showed that the optical band gap of BCB10Br-C4PA was 3.22 eV, showing an onset absorption wavelength at about 385 nm ( Figure 4 );

[0061] See Figure 1 , and the preparation steps of the organic-inorganic lead halide perovskite solar cell in this example are as follows:

[0062] The ITO glass substrate was ultrasonically treated successively in deionized water, glass cleaning solution, acetone, and isopropyl alcohol, and then dried with dry compressed air. The cleaned ITO glass was treated with ultraviolet-ozone for 15 min to improve wettability. To prepare the Cs 0.07 FA 0.9 MA 0.03 Pb(I 0.92 Br 0.08 )3 precursor solution, 191.4 mg of FAI, 13.5 mg of FABr, 24.6 mg of CsI, 31.9 mg of MACl, 39.6 mg of PbBr2, 0.64 mg of MAI, and 591.2 mg of PbI2 were added to 1 mL of a DMF / DMSO (v / v, 1:4) solution. Then, BCB10Br-C4PA was mixed with the perovskite precursor solution at a molar concentration of 2.0 M. 40 μL of the perovskite precursor solution containing BCB10Br-C4PA was directly spin-coated onto the ITO substrate, first at a speed of 1500 r / min for 10 s, and then at a speed of 4000 r / min for 30 s. Then the obtained film was transferred to a hot stage and heated at 120 °C for 30 min. Finally, 35 nm thick C60, 7 nm BCP, and 70 nm Ag electrodes were thermally evaporated successively onto the prepared perovskite film. The fabricated device is denoted as "adding precursor" in Figure 7 and Figure 8 .

[0063] Meanwhile, a device with traditional layer-by-layer spin-coated BCB10Br-C4PA perovskite was also fabricated in this example for comparison, and the fabrication steps are as follows:

[0064] The ITO glass substrate was ultrasonically treated successively in deionized water, glass cleaning solution, acetone, and isopropyl alcohol, and then dried with dry compressed air. The cleaned ITO glass was treated with ultraviolet-ozone for 15 min to improve wettability. A 0.8 mg / mL ethanol solution of BCB10Br-C4PA was prepared, and then spin-coated at a speed of 3000 r / min for 30 s and annealed on a hot stage at 120 °C for 30 min. To prepare the Cs 0.07 FA 0.9 MA 0.03 Pb(I 0.92 Br 0.08) 3 precursor solution. Add 191.4 mg of FAI, 13.5 mg of FABr, 24.6 mg of CsI, 31.9 mg of MACl, 39.6 mg of PbBr2, 0.64 mg of MAI, and 591.2 mg of PbI2 into 1 mL of DMF / DMSO (v / v, 1:4) solution. Spin-coat 40 μL of the perovskite precursor solution onto the annealed BCB10Br-C4PA film, first at a speed of 1500 r / min for 10 s, and then at a speed of 4000 r / min for 30 s. Then transfer the obtained film to a hot stage and heat it at 120 °C for 30 min. Finally, thermally evaporate 35 nm thick C60, 7 nm BCP, and 70 nm Ag electrodes onto the prepared perovskite film in sequence. The prepared battery device is Figure 7 and Figure 8 is denoted as "layer-by-layer spin-coating" in

[0065] Use time-of-flight secondary ion mass spectrometry to determine the distribution of the self-assembled small molecule added to the perovskite precursor in the perovskite film after film formation ( Figure 5 ), and the results show that the self-assembled small molecule is mainly distributed between the perovskite and the ITO substrate. It shows that during spin-coating, the self-assembled small molecule in the solution automatically migrates towards the ITO, anchors on the ITO surface by bonding with the hydroxyl groups on the ITO surface, and becomes the hole transport layer ( Figure 6 ).

[0066] Use a xenon lamp solar simulator, the test light source intensity is AM 1.5G, 100 mW cm -2 Test the open-circuit voltage, short-circuit current, and fill factor of the prepared battery device. Its J-V curve is shown in Figure 7 , where the open-circuit voltage V oc of the device with the self-assembled small molecule added to the perovskite precursor is 1.07 V, the short-circuit current J sc is 24.6 mA / cm 2 , the fill factor FF is 80.4%, and the photoelectric conversion efficiency is 21.2%. Moreover, the prepared device still maintains more than 90% of the initial efficiency after being stored in the glove box for 1600 h ( Figure 8 ). In comparison, for the PSCs with the BCB10Br-C4PA and perovskite layers spin-coated layer by layer, its V oc is 1.04 V, the short-circuit current J sc is 24.4 mA / cm 2 , the fill factor FF is 75.1%, and the photoelectric conversion efficiency is 19.0%. After being stored under the same conditions, the efficiency drops to 72% of the initial efficiency. The above results show that this method simultaneously improves the device efficiency and stability.

[0067] Although the specific implementation manners of the present invention have been described above in conjunction with the accompanying drawings, it is not a limitation on the protection scope of the present invention. Based on the technical solutions of the present invention, various modifications or deformations that can be made by those skilled in the art without creative efforts are still within the protection scope of the present invention.

Claims

1. Preparation of perovskite solar cells by one-step spin coating of self-assembled small molecules, characterized in that, It includes the following steps: 1) Treat the cleaned ITO glass with ultraviolet-ozone to improve wettability; 2) Prepare the perovskite Cs 0.07 FA 0.9 MA 0.03 Pb(I 0.92 Br 0.08 )3 precursor solution; 3) Add the self-assembled small molecule to the perovskite precursor solution; the self-assembled small molecule is a self-assembled small molecule containing an anchoring group, and the anchoring group includes at least one of an acetate group, a borate group, a mercapto group, and a phosphonic acid group; 4) Spin-coat the perovskite precursor solution containing the self-assembled small molecule on ITO and anneal; 5) Thermally evaporate C60, BCP, and Ag electrodes sequentially on the prepared perovskite thin film; The self-assembled small molecule containing an anchoring group has the following structure: ； The synthesis route of the self-assembled small molecule containing a phosphonate group is as follows: 。 2. Preparation of the perovskite solar cell based on one-step spin coating of self-assembled small molecules according to claim 1, characterized in that: In step 1), the time of ultraviolet-ozone treatment is 5 - 30 min.

3. The preparation of the perovskite solar cell based on one-step spin coating of self-assembled small molecules according to claim 1, wherein: In step 2), the solvent used for the perovskite Cs 0.07 FA 0.9 MA 0.03 Pb(I 0.92 Br 0.08 )3 precursor solution is a mixed solution of DMF and DMSO.

4. The preparation of the perovskite solar cell based on one-step spin coating of self-assembled small molecules as claimed in claim 1, wherein: In step 3), the molar concentration of the added self-assembled small molecule is 0.1 - 5 M.

5. The preparation of the perovskite solar cell based on one-step spin coating of self-assembled small molecules according to claim 1, characterized in that: In step 4), the spin-coating speed is 1000 - 8000 r / min, and the duration is 15 - 50 s.

6. The preparation of the perovskite solar cell based on one-step spin coating of self-assembled small molecules according to claim 1, wherein: The thicknesses of the C60, BCP, and Ag electrodes are 10 - 60 nm, 2 - 8 nm, and 10 - 100 nm respectively.

7. The preparation of the perovskite solar cell based on one-step spin coating of self-assembled small molecules as claimed in claim 6, wherein: The thicknesses of the C60, BCP, and Ag electrodes are 20 - 50 nm, 5 - 8 nm, and 50 - 100 nm respectively.

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