Methylthio-containing self-assembled hole transport material, preparation method thereof and application of methylthio-containing self-assembled hole transport material in perovskite solar cell

Abstract

The invention discloses a methylthio-containing self-assembled hole transport material, a preparation method thereof and application of the methylthio-containing self-assembled hole transport material in a perovskite solar cell, and relates to the technical field of photovoltaic materials. According to the invention, carbazole is used as a core hole transport group, methylthio is introduced to the N atom para-position of carbazole, a phosphoric acid anchoring group is connected through an alkyl chain or a conjugated benzene ring, and three types of SAMs materials of MeS-2PACz, MeS-4PACz and MeS-rho PACz are designed and synthesized. S atom lone pair electrons in the material can form a strong coordinate bond with Pb < 2 + > in perovskite, and in combination with a methylthio steric hindrance effect, interface defects can be effectively passivated, and non-radiative recombination is reduced; in addition, MeS-rho PACz linked with the conjugated benzene ring can enhance intermolecular pi-pi accumulation, and energy level matching and charge transfer performance are further optimized. The material is applied to a trans-structure perovskite solar cell, the photoelectric conversion efficiency of a device based on MeS-rho PACz reaches 21.79%, the hysteresis factor is only 0.73%, the long-term stability is excellent, and key material and technical support are provided for efficient and stable perovskite solar cells.

Description

Technical Field

[0001] This invention belongs to the field of photovoltaic materials technology, specifically to methyl sulfide-based self-assembled hole transport materials, their preparation methods, and their application in perovskite solar cells. Background Technology

[0002] In recent years, organic-inorganic metal halide perovskite solar cells (PSCs) have attracted much attention due to their high photoelectric conversion efficiency, simple fabrication process, low cost, and tunable bandgap. The hole transport layer (HTL), as the core functional layer of PSCs, needs to achieve efficient hole extraction and transport, block electron-hole recombination, and modify interface defects, directly affecting the device efficiency and stability.

[0003] Traditional inorganic hole transport materials (such as NiOx) suffer from numerous interface defects and poor energy level matching with perovskites. Organic small molecule hole transport materials (such as Spiro-OMeTAD) require doping with lithium and cobalt salts, leading to decreased device stability and higher costs. Organic self-assembled molecular layers (SAMs), as novel hole transport materials, can form dense monolayers on substrate surfaces through molecular self-assembly, possessing both defect passivation and selective contact functions, and hold promise as a replacement for traditional HTLs.

[0004] However, the ideal state for SAMs is to form a dense, pinhole-free, monolayer-thick, uniform thin film on a conductive substrate (such as ITO). However, in actual fabrication, the choice of solvent, concentration, deposition time, temperature, and the cleanliness and hydrophilicity / hydrophobicity of the substrate all significantly affect the film quality of SAMs. Pinhole defects: If the film is uneven, with pinholes or uncovered areas, it can lead to: Local short circuits: The perovskite layer directly contacts the underlying electrode, forming a leakage channel, severely reducing the device's open-circuit voltage (Voc) and fill factor (FF). Interfacial recombination: Exposed substrate areas become non-radiative recombination centers for charge carriers, reducing device performance. SAMs themselves typically have poor conductivity; their hole extraction and transport functions heavily rely on the conductive substrate (such as ITO) in close contact with them. SAMs primarily function as "extraction" and "selective contact," rather than long-distance "transport." This requires the substrate to have extremely high flatness and work function matching.

[0005] Based on the shortcomings of the existing technology, the present invention aims to study a series of SAMs molecules with specific structures to improve some of the shortcomings of existing SAMs molecules in photovoltaic device applications. Summary of the Invention

[0006] To address the problems of poor film quality, numerous interface defects, poor energy level matching, and low device efficiency and stability of existing SAMs hole materials, this invention provides a methyl sulfide-based self-assembled hole transport material. By optimizing the interface interaction and charge transport performance through molecular structure design, this invention also provides its synthesis method and its application in perovskite solar cells, enabling efficient and stable device operation.

[0007] To achieve the above objectives, the first objective of this invention is to provide a methylthio-based self-assembled hole transport material.

[0008] The aforementioned methylthio-containing self-assembled hole transport material, with a carbazole group as the core hole transport group, has the following structural formula: ; In the formula, R is ethyl, n-butyl or phenyl, and the corresponding methyl thio-containing self-assembled hole transport materials are named MeS-2PACz, MeS-4PACz and MeS-ρPACz, respectively.

[0009] A second objective of this invention is to provide a method for preparing the aforementioned methyl sulfide-based self-assembled hole transport material.

[0010] The preparation method of the methyl sulfide-based self-assembled hole transport material includes the following steps: Synthesis of S1, methylthiocarbazole substrate (MeS-Cz): S11. Dissolve I-Cz in anhydrous tetrahydrofuran (THF), add sodium hydride (NaH) in an ice bath under nitrogen protection, stir for a period of time, add tert-butyldimethylchlorosilane (TBDMSCI), and react at room temperature. After the reaction is completed, I-CzTBDMSi is obtained by quenching, extraction, drying, and silica gel chromatography. S12. Dissolve the I-CzTBDMSi obtained in step S11 in anhydrous tetrahydrofuran (THF), add tert-butyllithium (tBuLi) dropwise under nitrogen protection at -70~-85℃, and after reacting for a period of time, add dimethyl disulfide (Me2S2). After reacting overnight at room temperature, the reaction is completed. After the reaction is completed, the product is quenched, extracted, washed, dried, concentrated under reduced pressure, and purified by column chromatography to obtain MeS-CzTBDMSi. S13. Dissolve the MeS-CzTBDMSi obtained in step S12 in anhydrous THF, add tetrabutylammonium fluoride (TBAF) and react at room temperature. After the reaction is completed, quench, extract, wash, dry and concentrate under reduced pressure to obtain MeS-Cz. S2. Synthesis of target SAMs materials: To synthesize MeS-2PACz: Dissolve MeS-Cz obtained in step S13, 1,2-dibromoethane, tripotassium phosphate, and tetrabutylammonium bromide in acetonitrile, react at 80 °C for 16 h, and quench, extract, dry, and purify by chromatography to obtain a brominated intermediate; react the brominated intermediate with triethyl phosphite at 80 °C for 16 h, and quench, extract, and prepare a phosphonate intermediate by HPLC; dissolve the phosphonate intermediate in anhydrous THF, add trimethylsilane bromide dropwise, react overnight at room temperature, add methanol and react for 2 h, and quench, extract, and purify by HPLC to obtain MeS-2PACz; To synthesize MeS-4PACz: The MeS-Cz obtained in step S13 is mixed with 1,4-dibromobutane, tetrabutylammonium bromide, and a 50% KOH aqueous solution. The mixture is reacted overnight at 60 °C. After extraction, drying, and chromatography purification, a brominated intermediate is obtained. The brominated intermediate is refluxed with triethyl phosphite at 140 °C for 16 h under nitrogen protection. After concentration and chromatography purification, a phosphonate intermediate is obtained. The phosphonate intermediate is dissolved in a mixture of THF and sodium hydroxide aqueous solution and reacted at 75 °C for 6 h. After extraction and chromatography purification, MeS-4PACz is obtained. If MeS-ρPACz is synthesized: S21. The MeS-Cz obtained in step S13 is dissolved in toluene (TOL) with diethyl 4-bromophenyl phosphate, cuprous iodide (CuI), diaminocyclohexane (DACH), and tripotassium phosphate (K3PO4). The reaction is carried out under nitrogen protection at a temperature of 90-110 °C. After the reaction is completed, the intermediate phosphonate (diethyl(4-(3,6-bis(methylthio)9H-carbazole-9-yl)phenyl)phosphonate is obtained by quenching, extraction, and column chromatography separation and purification. S22. Dissolve the phosphonate intermediate obtained in step S21 in anhydrous THF, add trimethylsilicon bromide (TMBS) dropwise, react at room temperature overnight, then add methanol (MeOH) to react. After the reaction is completed, quench, extract, wash, dry, concentrate and purify to obtain MeS-ρPACz, which is the sulfur-based SAMs hole material.

[0011] In the preferred embodiment, in step S11, the molar ratio of I-Cz, NaH and TBDMSCI is 12~13:18.5~19.5:13.5~14.5.

[0012] In the preferred embodiment, in step S11, the quenching specifically involves pouring ice-cold deionized water into the reaction solution after the reaction is completed to carry out the quenching reaction.

[0013] In the preferred embodiment, in steps S11, S12 and S22, the solvent used for extraction is dichloromethane (DCM).

[0014] In the preferred embodiment, in step S11, the eluent used for silica gel chromatography purification is a mixed solution of dichloromethane and n-hexane in a volume ratio of 1:4.

[0015] In the preferred embodiment, in step S12, the molar ratio of I-CzTBDMSi, tBuLi and Me2S2 is 2~3:5.5~6.5:9~10.

[0016] In the preferred embodiment, the quenching in steps S12, S21, and S22 of synthesizing MeS-ρPACz specifically involves adding deionized water to the reaction solution after the reaction is completed to carry out the quenching reaction.

[0017] In the preferred embodiment, in step S12 and step S22 of synthesizing MeS-ρPACz, the washing is performed using a saturated sodium chloride solution.

[0018] In the preferred embodiment, in step S13, the molar ratio of MeS-CzTBDMSi and TBAF is 0.5~1.5:1~2.

[0019] In the preferred embodiment, the quenching in step S13 specifically involves adding a saturated NH4Cl solution to the reaction solution after the reaction is completed to carry out the quenching reaction.

[0020] In the preferred embodiment, in step S13, the solvent for extraction is toluene.

[0021] In the preferred embodiment, in step S13, the washing process involves first washing with deionized water multiple times, and then washing with a saturated sodium chloride solution.

[0022] In the preferred embodiment, in step S13, the eluent used for silica gel chromatography purification is a mixed solution of dichloromethane and n-hexane in a volume ratio of 1:3.

[0023] In the preferred embodiment, in the synthesis of MeS-2PACz, the molar ratio of MeS-Cz, 1,2-dibromoethane, K3PO4, and tetrabutylammonium bromide is 3.5~4.5:7~8.5:6.5~7.5:0.1~0.5; the molar ratio of the brominated intermediate to triethyl phosphite is 1~3:65~75; and the molar ratio of the phosphonate intermediate to trimethylsilane bromide is 0.5~1.5:2.5~4.

[0024] In the preferred embodiment, in the synthesis of MeS-4PACz, the molar ratio of MeS-Cz, 1,4-dibromobutane, and tetrabutylammonium bromide is 2~3.5:0.02~0.08:0.1~0.5; the molar ratio of the brominated intermediate to triethyl phosphite is 0.5~1.5:11~13; and the molar ratio of the phosphonate intermediate to sodium hydroxide is 0.2~0.8:2~4.

[0025] In the preferred embodiment, in step S21 of synthesizing MeS-ρPACz, the molar ratio of MeS-Cz, diethyl 4-bromophenyl phosphate, cuprous iodide, diaminocyclohexane, and tripotassium phosphate is 3~4.5:2.5~3.5:0.3~0.5:0.7~0.9:6~7.5.

[0026] In the preferred embodiment, in step S21 of synthesizing MeS-ρPACz, the extraction solvent is ethyl acetate (EA).

[0027] In the preferred embodiment, in step S21 of synthesizing MeS-ρPACz, the eluent used for silica gel chromatography purification is a mixed solution of petroleum ether (PE) and ethyl acetate in a volume ratio of 10:7.

[0028] In the preferred embodiment, in step S22 of synthesizing MeS-ρPACz, the molar ratio of the phosphonate intermediate to trimethylsilane bromide is 2~4:3~5.

[0029] In the preferred embodiment, in step S22 of synthesizing MeS-ρPACz, the separation and purification are performed by high performance liquid chromatography (HPLC), and the eluent is a mixed solution of acetonitrile and formic acid aqueous solution with a volume ratio of 1:1 and a mass concentration of 0.1%.

[0030] In the preferred embodiment, the drying is performed using anhydrous magnesium sulfate.

[0031] A third objective of this invention is to provide a perovskite solar cell.

[0032] The perovskite solar cell adopts an inverted structure, and the device structure is ITO / NiOx / SAMs / PVKs / PEAI / PCBM / BCP / Ag, wherein the SAMs are selected from MeS-2PACz, MeS-4PACz or MeS-ρPACz.

[0033] The fourth objective of this invention is to provide a method for preparing the perovskite solar cell.

[0034] The method for preparing the perovskite solar cell includes the following steps: P1. Cleaning of conductive glass (ITO) substrate: Clean with soapy water, ultrapure water, anhydrous ethanol, acetone and isopropanol in sequence by ultrasonic cleaning, dry with nitrogen and then irradiate with ultraviolet ozone. P2, NiOx layer preparation: Dissolve nickel oxide (NiOx) powder in ultrapure water to prepare a 5~15 mg / mL solution, spin-coat it onto the ITO substrate described in step P1, and heat-anneal at 100~120 ℃ for 15~25 min; P3, SAMs layer preparation: Dissolve the SAMs in anhydrous ethanol to prepare a SAMs solution, spin-coat it onto the NiOx layer described in step P2, and heat-anneal at 10~15 ℃ for 10~20 min. P4. Preparation of the perovskite layer: Lead iodide (PbI2), lead bromide (PbBr2), formamidinium hydroiodide (FAI), cesium iodide (CsI), and methylamine hydrochloride (MACl) are dissolved in a mixed solvent of N,N-dimethylformamide / dimethyl sulfoxide (DMF / DMSO, v / v=4:1) to prepare a PVKs solution. The PVKs solution is then spin-coated onto the MeS-ρPACz layer described in step P3 using a two-step method: first, spin-coating at 1500~2500 rpm for 3~8 s, then spin-coating at 3500~4500 rpm for 25~35 s. Chlorobenzene with a volume of 2~2.5 times the volume of the PVKs solution is added at the 20~25 s of spin-coating. The mixture is then heat-annealed at 110~130 ℃ for 45~75 min. P5. Electron transport layer and electrode preparation: The perovskite layer described in step P4 is spin-coated sequentially with an isopropanol solution containing phenylethyl ammonium iodide (PEAI), a chlorobenzene solution containing methyl [6,6]-phenyl-C61-butyrate (PCBM), and an ethanol solution containing biphase calcium phosphate ceramic (BCP). Finally, an Ag electrode is deposited by vapor deposition.

[0035] In the preferred embodiment, in step P1, the duration of ultrasonic cleaning is 20-45 min, and the duration of ultraviolet ozone irradiation is 10-30 min.

[0036] In the preferred embodiment, in step P1, the solution is filtered through a 0.22 μm polytetrafluoroethylene (PTFE) filter head before spin coating.

[0037] In the preferred embodiment, in step P2, the spin coating speed is 3500~5000 rpm and the time is 20~45 s.

[0038] In the preferred embodiment, in step P3, the concentration of the SAMs solution is 0.5~2 mg / mL.

[0039] In the preferred embodiment, in step P3, the spin coating speed is 2500~3500 rpm and the time is 20~45 s.

[0040] In the preferred embodiment, in step P4, the mass concentration of lead iodide is 0.45~0.55 g / mL.

[0041] In the preferred embodiment, in step P4, the mass concentration of lead bromide is 0.15~0.25 g / mL.

[0042] In the preferred embodiment, in step P4, the mass concentration of formamidin hydroiodate is 0.15~0.25 g / mL.

[0043] In the preferred embodiment, in step P4, the mass concentration of cesium iodide is 0.05~0.1 g / mL.

[0044] In the preferred embodiment, in step P4, the mass concentration of the methylamine hydrochloride is 0.02~0.06 g / mL.

[0045] In the preferred embodiment, in step P4, the volume ratio of N,N-dimethylformamide to dimethyl sulfoxide in the N,N-dimethylformamide / dimethyl sulfoxide mixed solvent is 4:1.

[0046] In the preferred embodiment, in step P5, the mass concentration of the phenylethyl ammonium iodide is 2~5 mg / mL.

[0047] In the preferred embodiment, in step P5, the mass concentration of the [6,6]-phenyl-C61-butyrate methyl ester is 15~25 mg / mL.

[0048] In the preferred embodiment, in step P5, the mass concentration of the biphase calcium phosphate ceramic is 0.3~0.7 mg / mL.

[0049] In the preferred embodiment, in step P5, the spin coating speed of the isopropanol solution containing phenylethyl ammonium iodide is 3500~5000 rpm, and the time is 20~45 s; the spin coating speed of the chlorobenzene solution containing methyl [6,6]-phenyl-C61-butyrate is 3500~5000 rpm, and the time is 20~45 s; the spin coating speed of the ethanol solution containing biphasic calcium phosphate ceramic (BCP) is 2500~3500 rpm, and the time is 20~45 s.

[0050] In the preferred embodiment, in step P5, the evaporation rate is 0.5~1 A / s.

[0051] In the preferred embodiment, in step P5, the thickness of the Ag electrode is 90~110 nm.

[0052] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) In this invention, a methylthio group is introduced at the para-position of the N atom in the core of carbazole, and the lone pair electrons of its S atom can interact with the Pb in the perovskite layer. 2+ The formation of strong coordination bonds, coupled with the steric hindrance effect of the methylthio group hindering the exposure of defect sites, results in a significant reduction in the defect state density at the perovskite / hole transport layer interface. XPS analysis confirms that SAMs and Pb... 2+ The formation of stable Pb-S coordination bonds enables Pb 2+ The increased binding energy effectively passivates defects such as surface dangling bonds, significantly reducing nonradiative recombination losses and laying the foundation for improving the device's open-circuit voltage (Voc) and fill factor (FF).

[0053] (2) This invention achieves synergistic optimization of energy levels and charge transport performance through structural regulation of molecular linking groups (alkyl chains or conjugated benzene rings): MeS-ρPACz linked by conjugated benzene rings enhances intermolecular π-π stacking, and its highest occupied molecular orbital (HOMO) energy level (-5.66 eV) almost perfectly matches the perovskite valence band (≈-5.4 eV), minimizing the hole extraction barrier; at the same time, π-π stacking forms a continuous charge transport channel, significantly improving hole mobility. Tests show that the photoelectric conversion efficiency (PCE) of the device based on MeS-ρPACz reaches 21.79%, and the hysteresis factor is only 0.73%, demonstrating more stable charge extraction and transport capabilities.

[0054] (3) This invention optimizes film formation performance through molecular structure design: In particular, MeS-ρPACz forms a denser and more uniform film due to the π-π stacking effect of its conjugated structure. Water contact angle tests show that its hydrophobicity is significantly better than that of MeS-4PACz with alkyl chains, which can effectively suppress the damage of the SAMs film by the solvent during the perovskite preparation process and block subsequent water vapor intrusion. Thermal analysis confirms that the 5% weight loss temperature of MeS-ρPACz reaches 272.5 ℃, the melting point is 252.9 ℃, and the thermal stability far exceeds the highest annealing temperature (120 ℃) ​​for battery preparation. Moreover, it does not require doping with any metal salts, avoiding interface degradation caused by dopants. Long-term stability tests show that the unencapsulated MeS-ρPACz device can maintain high performance for a long time in a nitrogen environment, and its stability is significantly better than that of existing SAMs materials and traditional HTL devices.

[0055] (4) The SAMs material of the present invention can be synthesized in a two-step process to obtain a high-purity product without the need for expensive catalysts or harsh reaction conditions. In device fabrication, the SAMs layer can be formed into a dense monolayer by simple spin coating and low-temperature annealing without the need for high-temperature treatment, and it is highly compatible with existing perovskite device processes. At the same time, the material does not need to be doped with precious metal compounds such as lithium salts and cobalt salts, which greatly reduces the raw material cost and fabrication complexity of the device, and provides feasibility for large-scale application.

[0056] (5) Due to the stronger intermolecular forces, the film formation of the MeS-ρPACz of the present invention is more consistent. The standard deviation of the distribution of key parameters such as PCE, Voc, and FF of the device based on this material is significantly lower than that of similar SAMs devices, indicating that its preparation is more reproducible. This solves the technical pain points of unstable performance and large batch differences of existing SAMs devices, and provides a guarantee for quality control in industrial production. Attached Figure Description

[0057] Figure 1 The general molecular structural formula of the SAMs hole material provided by this invention.

[0058] Figure 2 For MeS-Cz 1 1H NMR spectrum (a) and HRMS spectrum (b).

[0059] Figure 3 For MeS-ρPACz 1 1H NMR spectrum (a) and HRMS spectrum (b).

[0060] Figure 4 For MeS-2PACz 1 1H NMR spectrum (a) and HRMS spectrum (b).

[0061] Figure 5 For MeS-4PACz 1 1H NMR spectrum (a) and HRMS spectrum (b).

[0062] Figure 6 Figure 1 shows the structural schematics of perovskite solar cell devices and their HOMO and LUMO energy level diagrams. Specifically, Figure 1(a) shows the structural schematics of the perovskite device, Figure 2(b) shows the optimized structures of MeS-4PACz and MeS-ρPACz and their molecular interactions, Figure 3(c) shows the HOMO energy level diagram of MeS-4PACz, Figure 4(d) shows the LUMO energy level diagram of MeS-4PACz, Figure 5(e) shows the HOMO energy level diagram of MeS-ρPACz, and Figure 6(f) shows the LUMO energy level diagram of MeS-ρPACz.

[0063] Figure 7 Figure 1 shows the surface electrostatic potential simulation and adsorption structure schematic diagram; Figure (a) shows the surface electrostatic potential and dipole moment of MeS-4PACz, Figure (b) shows the optimized adsorption structure schematic diagram of MeS-4PACz, Figure (c) shows the surface electrostatic potential and dipole moment of MeS-ρPACz, and Figure (d) shows the optimized adsorption structure schematic diagram of MeS-ρPACz.

[0064] Figure 8The water contact angle diagrams are shown for MeS-4PACz and MeS-ρPACz deposited on ITO / NiOx substrates.

[0065] Figure 9 Figure 1 shows the thermal analysis curves of MeS-4PACz and MeS-ρPACz. Figure 2 shows the thermogravimetric analysis (TGA) curve of MeS-4PACz, Figure 3 shows the differential scanning calorimetry (DSC) curve of MeS-4PACz, Figure 4 shows the thermogravimetric analysis (TGA) curve of MeS-ρPACz, and Figure 5 shows the differential scanning calorimetry (DSC) curve of MeS-ρPACz.

[0066] Figure 10 Figure 1 shows the electrical performance of MeS-4PACz and MeS-ρPACz. Figure 2 shows the JV characteristic curves of devices fabricated with different concentrations of MeS-4PACz; Figure 3 shows the JV characteristic curves of devices fabricated with different concentrations of MeS-ρPACz; Figure 4 shows the JV characteristic curves of the champion devices of MeS-4PACz and MeS-ρPACz; Figure 5 shows the EQE curves of the champion devices of MeS-4PACz and MeS-ρPACz; Figure 6 shows the steady-state output of the champion devices of MeS-4PACz and MeS-ρPACz; and Figure 7 shows the EIS spectrum of the champion devices of MeS-4PACz and MeS-ρPACz.

[0067] Figure 11 The XPS spectra of MeS-4PACz and MeS-ρPACz are shown in Figures (a) and (b), which are XPS spectra of the C 1s signal of the MeS-4PACz and MeS-ρPACz films, respectively, and Figures (c) and (d) are XPS spectra of the P 2p signal of the MeS-4PACz and MeS-ρPACz films, respectively.

[0068] Figure 12 The figures show the XPS spectra of NiOx, NiOx / MeS-4PACz, NiOx / MeS-ρPACz and perovskite films. Figures (a), (b) and (c) show the XPS spectra of the Ni 2p signal of NiOx, NiOx / MeS-4PACz and NiOx / MeS-ρPACz films, respectively. Figure (d) shows the XPS spectra of the Pb 4f signal of the perovskite film and the perovskite films based on MeS-4PACz and MeS-ρPACz.

[0069] Figure 13Figure 1 shows the UV-Vis absorption and transmission spectra, UV photoelectron spectra, and energy level distribution of MeS-4PACz and MeS-ρPACz. Figure 2 shows the UV-Vis absorption spectra of MeS-4PACz and MeS-ρPACz molecules, Figures 3 (b) and 4 (c) show the wavelengths of the UV-Vis absorption band edges of MeS-4PACz and MeS-ρPACz, respectively, Figure 5 (d) shows the UV-Vis transmission spectra of different SAMs substrates, Figure 6 (e) shows the UPS diagrams of MeS-4PACz and MeS-ρPACz films, and Figure 7 (f) shows the energy level distribution of MeS-4PACz and MeS-ρPACz films.

[0070] Figure 14 Long-term stability plots for the MeS-4PACz and MeS-ρPACz champion devices.

[0071] Figure 15 Figure 1 shows the JSC, VOC, FF, and PCE distributions of the MeS-4PACz and MeS-ρPACz champion devices. Figure 2 shows the JSC distribution, Figure 3 shows the VOC distribution, Figure 4 shows the FF distribution, and Figure 5 shows the PCE distribution.

[0072] Figure 16 Figure 1 shows the performance of perovskite thin films on MeS-4PACz and MeS-ρPACz substrates. Figure 2 shows the PL plot; Figure 3 shows the TRPL plot; Figure 4 shows the PL mapping plot of MeS-4PACz; Figure 5 shows the PL mapping plot of MeS-ρPACz; and Figure 6 shows the PL intensity distribution. Detailed Implementation

[0073] The technical solution of the present invention will be further described and illustrated below through examples. All raw materials used in the examples are commercially available or prepared using conventional methods.

[0074] Example 1 A sulfur-based SAMs hole material, with a carbazole group as the hole transport core group, has the following structural formula: .

[0075] The sulfur-based SAMs hole material is prepared by the following steps: Synthesis of S1, methylthiocarbazole substrate (MeS-Cz): S11. Dissolve I-Cz (5.33 g, 12.72 mmol) in anhydrous THF (35 mL), purging with nitrogen several times to maintain the system under nitrogen protection. Add sodium hydride (60%, 0.76 mg, 19.08 mmol) under ice bath conditions (0 °C), stir for 30 min, then add tert-butyldimethylchlorosilane (2.1 g, 14 mmol) at 0 °C. Stir at room temperature for 20 h, monitoring the reaction by thin-layer chromatography. After the reaction is complete, carefully pour the reaction solution into ice-cold deionized water (100 mL), extract twice with dichloromethane (DCM) (75 mL), and dry the organic phase with anhydrous MgSO4 to obtain a grayish-white solid. Next, purify and separate by silica gel chromatography using a dichloromethane (DCM):n-hexane mixture (v / v) of 1:4 as the eluent to obtain the product, a white solid (I-CzTBDMSi) 1.3. g, yield 24.4%, the reaction formula for the formation of I-CzTBDMSi from I-Cz is shown below: ; S12. Dissolve the I-CzTBDMSi (1.3 g, 2.44 mmol) obtained in step S11 in anhydrous THF (15 mL), evacuate and purge with nitrogen several times, seal the system, and cool the solution to -78°C in a cryogenic reactor under nitrogen protection. Slowly add tert-butyllithium (1.3 M in pentane, 4.7 mL, 6.1 mmol) dropwise using a syringe for 10 min. The solution changes from colorless to yellow. After the addition is complete, continue stirring at -78°C for 2 h. Then slowly add dimethyl disulfide (0.9 mL, 9.56 mmol). The solution changes from yellow to colorless. React overnight at room temperature. Monitor the reaction progress by thin-layer chromatography. After the reaction is complete, quench the reaction solution in deionized water (75 mL), extract twice with DCM (50 mL), and then extract with saturated sodium chloride solution (75 mL). Wash twice with MgSO4 (mL), dry the organic phase with anhydrous MgSO4, concentrate under reduced pressure to obtain a thick, grayish-white oil, purify by column chromatography, elute with DCM:n-hexane (1:3) to obtain a colorless oil, and slowly solidify in vacuum to form 0.362 g of white solid (MeS-CzTBDMSi), yield 40%. The reaction formula for the formation of MeS-CzTBDMSi from I-CzTBDMSi is shown below:

[0076] S13. Dissolve the MeS-CzTBDMSi (0.362 g, 0.97 mmol) obtained in step S12 in anhydrous THF (7.2 mL), stir at room temperature, add TBAF (1.0 M in water, 1.4 mL, 1.4 mmol), and continue stirring for 30 min. Monitor the reaction progress by thin-layer chromatography. After the reaction is complete, quench the reaction with saturated NH4Cl(aq) (50 mL), extract three times with toluene (25 mL), wash three times with deionized water (50 mL), and continue washing with saturated brine (50 mL). Dry the organic phase with anhydrous MgSO4, concentrate under reduced pressure, and obtain 0.238 g of white solid (MeS-Cz), with a yield of 95%. The reaction formula for the formation of MeS-Cz from MeS-CzTBDMSi is shown below: ; The prepared MeS-Cz 1H NMR spectrum and 1H NMR mass spectrum, such as Figure 2 As shown; Synthesis of S2 and MeS-ρPACz: S21. The MeS-Cz (1 g, 3.86 mmol), diethyl 4-bromophenyl phosphate (824 mg, 2.82 mmol), CuI (70.1 mg, 0.37 mmol), DACH (88 mg, 0.77 mmol), and K3PO4 (1.45 g, 6.83 mmol) obtained in step S13 were placed in a 50 mL single-necked flask. Toluene (7 mL) was added, and the flask was quickly sealed tightly. The air inside the flask was replaced with nitrogen. The reaction mixture was heated to 100 °C and stirred for 16 h under nitrogen atmosphere. The reaction was monitored by LCMS (liquid chromatography-mass spectrometry) until completion. Deionized water (20 mL) was slowly added to quench the reaction. The mixture was extracted three times with ethyl acetate (100 mL), purified by silica gel chromatography, and eluted with a mixed solution of PE and EA (volume ratio 10:7) to obtain a white solid (phosphonate intermediate) 1.4 g. g, yield 77.8%, the reaction formula for the formation of phosphonate intermediate from MeS-Cz is shown below: ; S22. Weigh 1.4 g (2.97 mmol) of the phosphonate intermediate obtained in step S21 into a single-necked flask, add anhydrous THF (10 mL), and slowly add trimethylsilane bromide (609 mg, 3.98 mmol) dropwise. React overnight at room temperature. After the reaction is complete as monitored by LCMS, add 2 mL of methanol and continue the reaction at room temperature for 2 h. Quench the reaction by slowly adding deionized water (20 mL), extract three times with ethyl acetate (100 mL), wash with saturated sodium chloride solution (100 mL), and after separation, dry the organic phase with anhydrous NaSO4, concentrate under reduced pressure, and purify by HPLC (50% acetonitrile: 0.1% formic acid water) to obtain the final product, a white solid, which is MeS-ρPACz, with a yield of 760 mg and a yield of 63.3%. The reaction formula for the formation of MeS-ρPACz from the phosphonate intermediate is shown below: .

[0077] The nuclear magnetic resonance spectrum of the prepared MeS-ρPACz is as follows: Figure 3 As shown, its 1H NMR spectrum is 1H NMR (400 MHz, DMSO-d6) δ 8.32 (d, J = 1.5 Hz, 2H), 7.96 (dd, J = 12.5, 7.9 Hz, 2H), 7.72 (dd, J = 7.9, 2.5 Hz, 2H), 7.41 (s, 4H), 2.59 (d, J = 1.3 Hz, 6H), which indicates that the preparation method provided by this invention can successfully prepare MeS-ρPACz.

[0078] Example 2 A sulfur-based SAMs hole material, with a carbazole group as the hole transport core group, has the following structural formula: .

[0079] The sulfur-based SAMs hole material is prepared by the following steps: S1, Synthesis of methylthiocarbazole substrate (MeS-Cz): Consistent with Example 1; Synthesis of S2 and MeS-2PACz: S21. Weigh MeS-Cz (1 g, 3.86 mmol), 1,2-dibromoethane (1.43 g, 7.72 mmol), tripotassium phosphate (K3PO4) (1.45 g, 6.83 mmol), and tetrabutylammonium bromide (111.28 g, 0.35 mmol) into a 50 mL single-necked flask. Add acetonitrile (CH3CN) (10 mL), heat to 80 °C, and stir for 16 h. Monitor the reaction completion by LCMS. Slowly add deionized water (50 mL) to quench the reaction. Extract three times with ethyl acetate (100 mL), wash with saturated brine (100 mL), dry the organic phase with anhydrous NaSO4, concentrate under reduced pressure, and purify by silica gel chromatography. Elute with PE:EA = 10:1 to obtain 700 mg of white solid (brominated intermediate), yield 50%. The equation for the synthesis of the brominated intermediate from MeS-Cz is shown below: ; S22. Weigh 700 mg (1.92 mmol) of the brominated intermediate obtained in step S21 into a 100 mL single-necked flask, add 12 mL (69.55 mmol) of triethyl phosphite, heat to 80 °C and stir for 16 h. Monitor the reaction completion by LCMS. Slowly add 50 mL of water to quench the reaction, extract with ethyl acetate (100 mL × 3), wash with saturated brine (100 mL), dry the organic phase with anhydrous NaSO4, concentrate under reduced pressure, and prepare by HPLC (eluting buffer is a mixture of acetonitrile and 0.1% formic acid aqueous solution at a volume ratio of 1:1). Finally, 500 mg of white solid phosphonate intermediate is obtained, with a yield of 61.6%. The equation for the synthesis of phosphonate intermediate from the brominated intermediate is shown below: ; S23. Weigh the phosphonate intermediate (500 mg, 1.18 mmol) prepared in step S22 into a single-necked flask, add anhydrous THF (8 mL), and slowly add trimethylsilane bromide (488 mg, 3.19 mmol) dropwise. React overnight at room temperature. After the reaction is complete, add methanol (2 mL) and react at room temperature for 2 h. Slowly add water (50 mL) to quench the reaction. Extract three times with ethyl acetate (100 mL), wash with saturated brine (100 mL), dry the organic phase with anhydrous NaSO4, concentrate under reduced pressure, and prepare by HPLC (a mixed solution of acetonitrile and 0.1% formic acid aqueous solution with a volume ratio of 1:1). The final product is a white solid (250 mg, yield 57.6%), which is MeS-2PACz. The equation for synthesizing MeS-2PACz from the phosphonate intermediate is shown below: .

[0080] The nuclear magnetic resonance spectrum of the prepared MeS-2PACz is as follows: Figure 4 As shown, the preparation method provided by the present invention can successfully prepare MeS-2PACz.

[0081] Example 3 A sulfur-based SAMs hole material, with a carbazole group as the hole transport core group, has the following structural formula: .

[0082] The sulfur-based SAMs hole material is prepared by the following steps: S1, Synthesis of methylthiocarbazole substrate (MeS-Cz): Consistent with Example 1; Synthesis of S2 and MeS-4PACz: S21. In a 25 mL reaction flask, MeS-Cz (700 mg, 2.70 mmol), 1,4-dibromobutane (5.6 mL, 0.047 mmol), tetrabutylammonium bromide (103.5 mg, 0.32 mmol), and 1.14 mL of 50% KOH aqueous solution were added sequentially. The mixture was then heated to 60 °C and reacted overnight. After the reaction was monitored by thin-layer chromatography to ensure complete reaction, the reaction mixture was cooled to room temperature. Water (50 mL) and ethyl acetate (100 mL) were slowly added, and the mixture was extracted three times. The mixture was washed with saturated brine (100 mL), and the organic phase was dried over anhydrous NaSO4. The mixture was concentrated under reduced pressure and purified by silica gel chromatography. The elution was performed with PE:EA (v / v = 10:1) to give a white solid (330 mg, yield 41%), which is the brominated intermediate (9-(4-bromobutyl)-3,6-bis(methylthio)-9H-carbazole). The equation for the synthesis of the brominated intermediate from MeS-Cz is shown below: ; S22. Add the brominated intermediate (350 mg, 0.89 mmol) obtained in step S21 and triethyl phosphite (2.06 mL, 11.9 mmol) to a 25 mL reaction flask. Vacuum the mixture several times with nitrogen, seal the system, and reflux at 140 °C for 16 h under nitrogen protection. After the reaction is complete (TLC), cool the mixture to room temperature, concentrate under reduced pressure, distill to remove the solvent, and purify by silica gel column chromatography (DCM:methanol (v / v) = 50:1) to obtain a white solid (350 mg, yield 87%), which is the phosphonate intermediate (diethyl(4-(3,6-bis(methylthio)-9H-carbazole-9-yl)butyl)phosphonate). The equation for synthesizing the phosphonate intermediate from the brominated intermediate is shown below: ; S23. Weigh the phosphonate intermediate (200 mg, 0.458 mmol) obtained in step S22 and dissolve it in deionized water (15 mL). Transfer the solution to a 25 mL reaction flask, add sodium hydroxide (117.5 mg, 2.94 mmol) and anhydrous tetrahydrofuran (THF) (2.5 mL), evacuate under nitrogen several times, and react at 75 °C for 6 h. After the reaction is complete as monitored by thin-layer chromatography, cool the mixture to room temperature, slowly add water (20 mL) to quench the reaction, extract three times with a dichloromethane-methanol system (50 mL), and purify by silica gel column chromatography (DCM:methanol volume ratio 1:10) to obtain a milky white flocculent powder (350 mg, yield 58%), which is MeS-4PACz. The equation for synthesizing MeS-4PACz from the phosphonate intermediate is shown below: .

[0083] The nuclear magnetic resonance spectrum of the prepared MeS-4PACz is as follows: Figure 5 As shown, its 1H NMR spectrum is 1H NMR (500 MHz, Chloroform-d) δ 8.00 (d, J = 68.7 Hz, 2H), 7.30 (s, 2H), 7.11 (s, 2H), 3.98 (s, 1H), 3.78 (s, 1H), 2.47 (s, 6H), 1.56 (s, 2H), 1.27 (d, J = 23.6 Hz, 2H), 1.02 (s, 3H), indicating that the preparation method provided by this invention can successfully prepare MeS-4PACz.

[0084] Example 4 A perovskite solar cell based on the hole transport material prepared in Example 1 adopts an inverted structure, with NiOx and SAMs as the double hole transport layer, and the device is configured as ITO / NiOx / MeS-ρPACz / PVKs / PEAI / PCBM / BCP / Ag.

[0085] The method for preparing the perovskite solar cell includes the following steps: P1. Cleaning of ITO (conductive glass) substrate: First, place the ITO substrate on a cleaning rack and put it into a beaker. Pour soapy water into the beaker until the substrate is submerged. Place it in an ultrasonic cleaner for 30 minutes. Then, clean it with ultrapure water for 30 minutes several times until there is no foam in the beaker. After that, continue to clean the ITO substrate with anhydrous ethanol, acetone and isopropanol for 30 minutes each. Finally, store the ITO substrate in isopropanol. Before each use, use a nitrogen gun to blow the liquid off the surface of the ITO substrate. The dried ITO substrate was placed in a UV ozone cleaner and irradiated for 20 minutes to remove residual solvent from the surface of the ITO substrate and improve its wettability. P2. NiOx layer preparation: The NiOx solution for the hole transport layer is prepared by weighing an appropriate amount of NiOx using an electronic balance and placing it in a small bottle. Ultrapure water is added to prepare a solution with a concentration of 10 mg / mL. The solution is then sonicated for 3-5 min. The prepared NiOx dispersion is filtered through a 0.22 μm polytetrafluoroethylene (PTFE) filter. 50 μL of NiOx solution is evenly spread on the ITO substrate described in step P1. The spin coater is set to a speed of 4000 rpm and a spin coating time of 30 s. Finally, the substrate is placed on a hot plate and heat-annealed at 110 ℃ for 20 min. The treated substrate is then transferred to an argon-filled glove box for later use. P3. Preparation of MeS-ρPACz layer: The method for preparing the hole transport layer SAMs solution is to weigh 1 mg of MeS-ρPACz prepared in Example 1 using an electronic balance and put it into a small bottle, then add anhydrous ethanol to prepare a 1.0 mg / mL SAMs solution. Place the substrate from step P2 on a spin coater, take 40 mL of the SAMs solution and spread it evenly on the NiOx layer of the substrate treated in step P2. Set the spin coater speed to 3000 rpm and the spin coating time to 30 s. Finally, place the substrate on a hot plate and heat anneal at 120 ℃ for 15 min. Then transfer the treated substrate to an argon-filled glove box for later use. P4. Preparation of PVKs (perovskite) layer: 527.6 mg of lead iodide, 180 mg of lead bromide, 206.4 mg of formamidinium hydroiodate, 78 mg of cesium iodide, and 40 mg of methylamine hydrochloride were dissolved in 1 mL of N,N-dimethylformamide / dimethyl sulfoxide (DMF / DMSO, v / v=4:1) mixed solvent and stirred in a glove box for 8 h to obtain a PVKs solution. 50 μL of the PVKs solution was evenly spread onto the MeS-ρPACz layer of the substrate prepared in step P3. A two-step spin coating method was used, with the spin coater set to the following parameters: first step spin speed 2000 rpm, time 5 s; second step spin speed 4000 rpm, time 30 s. 110 μL of chlorobenzene was added dropwise 20-25 s into the spin coater. Finally, the substrate was placed on a hot plate and heat-annealed at 120 ℃ for 60 minutes. All of the above operations were performed in a glove box filled with argon gas. P5. Electron transport layer and electrode preparation: Dissolve 3 mg of PEAI in 1 mL of isopropanol (IPA) to prepare a 3 mg / mL PEAI solution. Take 30 μL of the filtered PEAI solution and spin-coat it onto the PVKs layer of the substrate prepared in step P4 at 4000 rpm for 30 s to obtain the PEAI layer. 40 mg of PCBM was dissolved in 2 mL of chlorobenzene (CB) to prepare a 20 mg / mL PCBM solution. The prepared PCBM solution was stirred in a glove box for 12 h. 30 μL of the filtered PCBM solution was spin-coated onto the PEAI layer at 4000 rpm for 30 s to obtain the PCBM layer. BCP was dissolved in ethanol to prepare a 0.5 mg / mL BCP solution. 40 μL of the filtered BCP solution was spin-coated onto the PCBM layer at 3000 rpm for 30 s to obtain the BCP layer. After the electron transport layer is coated, 100 nm of Ag is deposited at a rate of 0.5~1 A / s.

[0086] Example 5 The method is basically the same as in Example 4, except that in step P3, the hole transport layer SAMs solution is prepared by weighing 0.5 mg of MeS-ρPACz prepared in Example 1 into a small bottle using an electronic balance, and then adding anhydrous ethanol to prepare a 0.5 mg / mL SAMs solution.

[0087] Example 6 The method is basically the same as in Example 4, except that in step P3, the hole transport layer SAMs solution is prepared by weighing 2 mg of MeS-ρPACz prepared in Example 1 into a small bottle using an electronic balance, and then adding anhydrous ethanol to prepare a 2 mg / mL SAMs solution.

[0088] Example 7 It is basically the same as Example 4, except that the SAMs material is MeS-2PACz with the structure shown in the following formula.

[0089] Example 8 It is basically the same as Example 4, except that the SAMs material is MeS-4PACz with the structure shown in the following formula.

[0090] Testing and Analysis Examples 4-6 show how different concentrations of self-assembled molecular monolayers (SAMs) were screened to optimize the interfacial properties of the modified perovskite solar cells and improve their photoelectric conversion efficiency (PCE). During the experiments, SAMs were prepared at concentrations of 0.5 mg / mL, 1.0 mg / mL, and 2.0 mg / mL, and the PCE of the modified perovskite solar cells was tested. The results showed that the highest PCE of 21.73% was achieved at a concentration of 1.0 mg / mL (Example 2), followed by 19.63% at 0.5 mg / mL (Example 3), and 20.93% at 2 mg / mL (Example 4). This may be because at 0.5 mg / mL, the low concentration may prevent the formation of a continuous and uniform film; at 2 mg / mL, SAMs molecules may accumulate, increasing the surface roughness of the film and reducing charge transport efficiency, thus lowering the PCE.

[0091] Depend on Figure 6 It can be seen that the highest occupied molecular orbital (HOMO) energy levels of MeS-4PACz and MeS-ρPACz are -5.59 eV and -5.66 eV, respectively, while the lowest unoccupied molecular orbital (LUMO) energy levels are -1.26 eV and -1.36 eV, respectively. The energy levels are highly matched with those of perovskite materials, which reduces defects in the contact layer and improves the interfacial charge transfer efficiency.

[0092] Depend on Figure 7 Electrostatic surface potential (ESP) analysis revealed that sulfur (S) atoms in both SAM molecules have high electron densities, indicating that they are mediated through S-Pb. 2+ The interaction has the potential to form an interfacial bond with the upper perovskite layer. This interfacial interaction can effectively enhance charge transfer efficiency, alleviate interfacial defect problems, and significantly improve the operational stability of photovoltaic devices.

[0093] Depend on Figure 8 It can be seen that MeS-ρPACz has stronger hydrophobicity in film formation, which can suppress the damage of SAMs film by solvent during the perovskite layer preparation process, while reducing subsequent water vapor intrusion and improving device stability.

[0094] Depend on Figure 9It can be seen that the 5% weight loss temperature of MeS-4PACz is about 258.2 ℃, and that of MeS-ρPACz is about 272.5 ℃. The melting point of MeS-4PACz is about 210.2 ℃, and that of MeS-ρPACz is about 252.9 ℃. Both materials meet the requirements for battery preparation (maximum annealing temperature 120 ℃), but MeS-ρPACz has better thermal stability (higher weight loss temperature / melting point). This is attributed to the enhanced intermolecular forces due to the π-π stacking of the conjugated benzene rings, which reduces molecular aggregation or decomposition at high temperatures.

[0095] Depend on Figure 10 It can be seen that the champion device based on MeS-4PACz (also known as the best device, referring to the one with the best performance among a large group of devices) has forward and reverse scan efficiencies of 20.65% and 20.93%, respectively, while the champion device based on MeS-ρPACz has forward and reverse scan efficiencies of 21.63% and 21.79%, respectively. This shows that when the linking group of the SAM molecule is a planar conjugated aromatic benzene ring (MeS-ρPACz), the device's photoelectric conversion efficiency (PCE) is superior to that of the device with a butylalkyl chain linking group (MeS-4PACz). Furthermore, we calculated the hysteresis index (HI) of the two devices, as shown in Table 1. The hysteresis factor of the device based on MeS-4PACz is 1.96%, while that of the device based on MeS-ρPACz is only 0.92%. These data indicate that the MeS-ρPACz molecule exhibits superior performance in terms of interface modification. The low hysteresis factor indicates better defect passivation capability and more stable charge extraction and transport capabilities, demonstrating a significant advantage in optimizing device performance.

[0096] Table 1 Performance data of each battery

[0097] These molecules are designed to enhance interfacial passivation by introducing two methylthio (-SCH3) substituents onto the N atom pairs in the carbazole core. This design aims to reduce interfacial defects in the perovskite layer, thereby reducing voids and cracks in the microstructure and effectively passivating defects. Furthermore, MeS-ρPACz exhibits the best performance because the introduction of conjugated joints in MeS-ρPACz significantly enhances intermolecular or intramolecular π-π stacking effects, as well as improving the molecular dipole moment and stability.

[0098] Depend on Figures 11-12 It can be seen that the elemental composition and structure of the SAMs material prepared by this invention are consistent, the phosphate groups are not reduced (P is in the +5 valence), and can stably bind to the PO-Ni bond of NiOx, ensuring unobstructed hole transport channels; SAMs and NiOx undergo electronic interaction (electron transfer of the PO-Ni bond), making Ni 2+The binding energy is increased, the work function of NiOx is optimized, and the hole extraction capability is enhanced; the methylthio group of SAMs and Pb 2+ Formation of Pb-S coordinate bonds (lone pair electrons of S are transferred to Pb) 2+ ), making Pb 2+ The increased binding energy effectively passivates Pb on the perovskite surface. 2+ Defects, reduce non-radiative recombination.

[0099] Depend on Figure 13 It can be seen that the redshift of the absorption band edge proves that the conjugated system of MeS-ρPACz is wider (benzene ring extended conjugation), which is more conducive to hole transport; the high transmittance ensures that the perovskite layer can fully absorb sunlight without the light shading loss of the SAMs layer; the measured energy level of UPS is consistent with the DFT simulation, proving that the energy level design is reliable; the HOMO of MeS-ρPACz is almost perfectly matched with the perovskite valence band (≈-5.4 eV), with the smallest hole extraction barrier and the highest charge extraction efficiency.

[0100] Depend on Figure 14 It can be seen that the stability of MeS-ρPACz is significantly better than that of MeS-4PACz.

[0101] Depend on Figure 15 It can be seen that the perovskite device based on MeS-ρPACz exhibits a higher average PCE, with a lower standard deviation of PCE than the device based on MeS-4PACz, and a narrower distribution of other performance parameters. This result indicates that using MeS-ρPACz as the substrate material can not only improve the overall photovoltaic performance of the device, but also enhance the uniformity of device performance and the reproducibility of fabrication.

[0102] Depend on Figure 16 It can be seen that the perovskite film without SAM self-assembled molecule modification has the strongest PL peak, with the peak position stable at 735 nm, indicating that the perovskite band gap is 1.68 eV. Compared with MeS-4PACz, the perovskite film modified with MeS-ρPACz has a lower PL intensity, exhibiting the strongest PL quenching, indicating that the perovskite film has fewer defect states and improved interface quality, thus avoiding nonradiative recombination of charge carriers at defect states. More photogenerated charge carriers are effectively extracted to the HTL, exhibiting higher hole mobility and faster hole extraction capability. The average carrier lifetime (τave = 51.58 ns) of the perovskite film modified with MeS-ρPACz is much lower than that of the perovskite film based on MeS-4PACz modification, exhibiting a shorter fluorescence lifetime, indicating faster carrier extraction at the interface. This may be attributed to the better molecular configuration of MeS-ρPACz, which is conducive to molecular stacking and obtaining higher hole mobility.

[0103] This experimental study demonstrates that MeS-ρPACz, as a novel self-assembled molecular hole transport material, possesses significant interface modification capabilities and performance advantages. It provides new ideas for the design and optimization of novel self-assembled hole transport materials and offers new directions and technical support for the design of efficient and stable perovskite solar cells.

[0104] It should be understood that the above embodiments are for illustrative purposes only and are not intended to limit the scope of protection of the present 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.

Claims

1. A methylthio-based self-assembled hole transport material, characterized in that, With the carbazole group as the hole transport core group, the structural formula is shown below: ； In the formula, R is ethyl, n-butyl or phenyl, and the corresponding methyl thio-containing self-assembled hole transport materials are named MeS-2PACz, MeS-4PACz and MeS-ρPACz, respectively.

2. A method for preparing the methylthio-based self-assembled hole transport material as described in claim 1, characterized in that, Includes the following steps: S1, Synthesis of methylthiocarbazole substrate: S11. Dissolve I-Cz in anhydrous tetrahydrofuran, add sodium hydride in an ice bath under nitrogen protection, stir for a period of time, add tert-butyldimethylchlorosilane, and react at room temperature. After the reaction is completed, I-CzTBDMSi is obtained by quenching, extraction, drying, and silica gel chromatography. S12. Dissolve the I-CzTBDMSi obtained in step S11 in anhydrous tetrahydrofuran, add tert-butyllithium dropwise under nitrogen protection at -70~-85℃, add dimethyl disulfide after reacting for a period of time, react overnight at room temperature, and after the reaction is completed, quench, extract, wash, dry, concentrate under reduced pressure, and separate and purify by column chromatography to obtain MeS-CzTBDMSi. S13. Dissolve the MeS-CzTBDMSi obtained in step S12 in anhydrous THF, add tetrabutylammonium fluoride and react at room temperature. After the reaction is completed, quench, extract, wash, dry and concentrate under reduced pressure to obtain MeS-Cz. S2. Synthesis of target SAMs materials: To synthesize MeS-2PACz: Dissolve MeS-Cz obtained in step S13, 1,2-dibromoethane, tripotassium phosphate, and tetrabutylammonium bromide in acetonitrile, react at 80 °C for 16 h, and quench, extract, dry, and purify by chromatography to obtain a brominated intermediate; react the brominated intermediate with triethyl phosphite at 80 °C for 16 h, and quench, extract, and prepare a phosphonate intermediate by HPLC; dissolve the phosphonate intermediate in anhydrous THF, add trimethylsilane bromide dropwise, react overnight at room temperature, add methanol and react for 2 h, and quench, extract, and purify by HPLC to obtain MeS-2PACz; To synthesize MeS-4PACz: The MeS-Cz obtained in step S13 is mixed with 1,4-dibromobutane, tetrabutylammonium bromide, and a 50% KOH aqueous solution. The mixture is reacted overnight at 60 °C. After extraction, drying, and chromatography purification, a brominated intermediate is obtained. The brominated intermediate is refluxed with triethyl phosphite at 140 °C for 16 h under nitrogen protection. After concentration and chromatography purification, a phosphonate intermediate is obtained. The phosphonate intermediate is dissolved in a mixture of THF and sodium hydroxide aqueous solution and reacted at 75 °C for 6 h. After extraction and chromatography purification, MeS-4PACz is obtained. If MeS-ρPACz is synthesized: S21. The MeS-Cz obtained in step S13 is dissolved in toluene with diethyl 4-bromophenyl phosphate, cuprous iodide, diaminocyclohexane and tripotassium phosphate, and reacted at 90~110 ℃ under nitrogen protection. After the reaction is completed, the phosphonate intermediate is obtained by quenching, extraction and column chromatography separation and purification. S22. Dissolve the phosphonate intermediate obtained in step S21 in anhydrous THF, add trimethylsilane bromide dropwise, react at room temperature overnight, then add methanol to react. After the reaction is completed, quench, extract, wash, dry, concentrate and purify to obtain MeS-ρPACz, which is the sulfur-based SAMs hole material.

3. The method for preparing the methylthio-based self-assembled hole transport material according to claim 2, characterized in that, In step S11, the molar ratio of I-Cz, NaH, and TBDMSCI is 12~13:18.5~19.5:13.5~14.5; in step S12, the molar ratio of I-CzTBDMSi, tBuLi, and Me2S2 is 2~3:5.5~6.5:9~10; in step S13, the molar ratio of MeS-CzTBDMSi and TBAF is 0.5~1.5:1~2.

4. The method for preparing the methylthio-based self-assembled hole transport material according to claim 2, characterized in that, In the synthesis of MeS-2PACz, the molar ratio of MeS-Cz, 1,2-dibromoethane, K3PO4, and tetrabutylammonium bromide is 3.5~4.5:7~8.5:6.5~7.5:0.1~0.5; the molar ratio of the brominated intermediate to triethyl phosphite is 1~3:65~75; and the molar ratio of the phosphonate intermediate to trimethylsilane bromide is 0.5~1.5:2.5~4.

5. The method for preparing the methylthio-based self-assembled hole transport material according to claim 2, characterized in that, In the synthesis of MeS-4PACz, the molar ratio of MeS-Cz, 1,4-dibromobutane, and tetrabutylammonium bromide is 2~3.5:0.02~0.08:0.1~0.

5.

6. The method for preparing the methylthio-based self-assembled hole transport material according to claim 2, characterized in that, In the synthesis of MeS-4PACz, the molar ratio of the brominated intermediate to triethyl phosphite is 0.5~1.5:11~13; the molar ratio of the phosphonate intermediate to sodium hydroxide is 0.2~0.8:2~4.

7. The method for preparing the methylthio-based self-assembled hole transport material according to claim 2, characterized in that, In the synthesis of MeS-ρPACz, the molar ratio of MeS-Cz, diethyl 4-bromophenyl phosphate, cuprous iodide, diaminocyclohexane, and tripotassium phosphate in step S21 is 3~4.5:2.5~3.5:0.3~0.5:0.7~0.9:6~7.5; in step S22, the molar ratio of the phosphonate intermediate and trimethylsilane bromide is 2~4:3~5.

8. A perovskite solar cell, characterized in that, The device adopts an inverse structure, and the device structure is ITO / NiOx / SAMs / PVKs / PEAI / PCBM / BCP / Ag, wherein the SAMs are selected from MeS-2PACz, MeS-4PACz or MeS-ρPACz as described in claim 1.

9. A method for preparing a perovskite solar cell as described in claim 8, characterized in that, Includes the following steps: P1, ITO substrate cleaning: sequentially ultrasonically cleaned with soapy water, ultrapure water, anhydrous ethanol, acetone, and isopropanol, dried with nitrogen, and then irradiated with ultraviolet ozone. P2, NiOx layer preparation: Dissolve nickel oxide powder in ultrapure water to prepare a 5~15 mg / mL solution, spin-coat it onto the ITO substrate described in step P1, and heat-anneal at 100~120 ℃ for 15~25 min; P3, SAMs layer preparation: Dissolve the SAMs in anhydrous ethanol to prepare a SAMs solution, spin-coat it onto the NiOx layer described in step P2, and heat-anneal at 10~15 ℃ for 10~20 min. P4. Preparation of the perovskite layer: Lead iodide, lead bromide, formamidinium hydroiodate, cesium iodide, and methylamine hydrochloride are dissolved in a mixed solvent of N,N-dimethylformamide / dimethyl sulfoxide to prepare a PVKs solution. The PVKs solution is then spin-coated onto the MeS-ρPACz layer described in step P3 using a two-step method: first, spin-coating at 1500-2500 rpm for 3-8 s, then at 3500-4500 rpm for 25-35 s. During the 20-25 s spin-coating, chlorobenzene with a volume of 2-2.5 times the volume of the PVKs solution is added. The mixture is then heat-annealed at 110-130 ℃ for 45-75 min. P5. Electron transport layer and electrode preparation: The perovskite layer described in step P4 is spin-coated sequentially with an isopropanol solution containing phenylethyl ammonium iodide, a chlorobenzene solution containing methyl [6,6]-phenyl-C61-butyrate, and an ethanol solution containing BCP. Finally, an Ag electrode is deposited by vapor deposition.

10. The method for preparing a perovskite solar cell according to claim 9, characterized in that, In step P3, the concentration of the SAMs solution is 0.5~2 mg / mL.

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