Self-assembled monomolecular layer material, self-assembled monomolecular layer and application of self-assembled monomolecular layer material

Abstract

The invention relates to the technical field of perovskite solar cells, and particularly discloses a self-assembled monomolecular layer material, a self-assembled monomolecular layer and application of the self-assembled monomolecular layer material. The self-assembled monomolecular layer material comprises a self-assembled material and halogenated benzene. The self-assembled monomolecular layer material provided by the invention can be used as a self-sacrifice molecular template, and halogenated benzene in the self-sacrifice molecular template can effectively inhibit self-polymerization of the self-assembled material in a solution, so that the self-assembled material is prevented from forming micelles and poor micropolymers in the solution, and the coverage degree and uniformity of the self-assembled monomolecular layer on a substrate are improved; therefore, the morphology, the photoelectric property and the mechanical toughness of the bottom-buried heterogeneous interface are improved. By adopting the self-assembled monomolecular layer material provided by the invention, the perovskite solar cell can have more uniform surface potential distribution, fewer defects, longer carrier lifetime and enhanced interface toughness.

Description

Self-assembled monolayer materials, self-assembled monolayers and their applications Technical Field

[0001] This invention relates to the field of perovskite solar cell technology, and in particular to a self-assembled monolayer material, a self-assembled monolayer, and its applications. Background Technology

[0002] Pin perovskite solar cells (PSCs) have become a highly promising photovoltaic technology for the coming decades due to their competitive power conversion efficiency (PCE), excellent long-term stability, low material costs, and compatibility with photovoltaic module manufacturing.

[0003] Self-assembled monolayers (SAMs) are a technique for spontaneously forming ordered monolayers in solution, often used to modify material surfaces to modulate their electronic, optical, or chemical properties. In devices such as perovskite solar cells, SAMs serve as a key method in interface engineering, providing well-aligned energy levels for efficient charge extraction. SAMs exhibit low nonradiative recombination losses, effectively improving the efficiency and stability of solar cell devices. Recent research indicates that applying SAMs as hole transport layers (HTLs) in perovskite solar cells can effectively improve their power conversion efficiency (PCE).

[0004] However, SAM molecules in solution, due to their molecular structure containing both hydrophilic (polar) and hydrophobic (nonpolar) regions, spontaneously aggregate to form ordered structures such as micelles and undesirable microaggregates. These ordered structures form clusters on the substrate surface, interfering with molecular diffusion and self-assembly processes. This results in uneven SAM coverage on the substrate, introducing leakage current and carrier recombination at the buried interface, thereby reducing the efficiency and stability of PSC devices. Furthermore, it shortens solution lifetime, hindering the large-scale manufacturing of pin perovskite solar cells.

[0005] To improve the coverage of SAM on substrates, various strategies have been proposed, including co-solvent dispersion, substrate modification, SAM thermal evaporation, SAM chemical structure optimization, and co-deposition. Among these, co-deposition is more widely used due to its low cost. It improves the dispersibility of SAM molecules by introducing external molecules. External molecules can also fill uncovered areas of the substrate, forming a more compact SAM layer. However, the integration of external molecules with SAM often exacerbates the chemical heterogeneity of the substrate surface, affecting the continuous crystallization of perovskites and the performance of buried heterogeneous interfaces. Summary of the Invention

[0006] The present invention aims to at least solve one of the aforementioned technical problems existing in the prior art. Therefore, a first objective of the present invention is to provide a self-assembled monolayer material. A second objective of the present invention is to provide a self-assembled monolayer formed from such a self-assembled monolayer material. A third objective of the present invention is to provide applications of such a self-assembled monolayer.

[0007] The technical concept of this invention is to provide a self-assembled monolayer material as a self-sacrificial molecular template (SSMT), comprising a self-assembled material and a halobenzene. The halobenzene in the SSMT can prevent the formation of micelles and undesirable microaggregates in the self-assembled material in solution, resulting in a self-assembled monolayer (SAM) layer mediated by the SSMT that exhibits higher coverage and uniformity on the substrate. Furthermore, the halobenzene in the SSMT can be completely volatilized through annealing, forming a pure, uniform, and dense self-assembled monolayer at the buried interface, thereby improving the morphology, photoelectric properties, and mechanical toughness of the buried heterostructure interface.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows: In a first aspect, the present invention provides a self-assembled monolayer material, comprising a self-assembled material and a halobenzene.

[0009] The self-assembled monolayer material of the present invention serves as a self-sacrificial molecular template (SSMT). The halogenated benzene in the SSMT can effectively inhibit the self-aggregation of the self-assembled material in solution, avoiding the formation of micelles and undesirable microaggregates in the solution. The self-assembled monolayer (SAM) mediated by the SSMT has higher coverage and uniformity on the substrate, thereby improving the morphology, photoelectric properties and mechanical toughness of the buried heterostructure interface.

[0010] Furthermore, unlike traditional co-deposition strategies, the halogenated benzenes in SSMT are completely volatilized after annealing. Therefore, this invention does not introduce external molecules into the final self-assembled monolayer, enabling the formation of a pure, uniform, and dense SAM layer at the buried interface. This invention provides a new perspective for optimizing the coverage of self-assembled monolayers on the substrate surface and reveals the crucial role of high-purity, high-coverage self-assembled monolayers in improving the performance and stability of perovskite solar cells.

[0011] Preferably, the halobenzene exhibits π–π stacking interactions with the self-assembled material. The halogen substituents in the halobenzene increase the polarizability of the π-electron system, enhancing the contribution of the London dispersion force to the π–π stacking interactions. The halogen atoms in the halobenzene can all extract electrons from the benzene ring π-conjugated system, resulting in a weakly negative overall electrostatic potential (ESP) of the molecule.

[0012] Preferably, the molar ratio of the self-assembled material to the halobenzene is 1:(0.5~4); more preferably, the molar ratio of the self-assembled material to the halobenzene is 1:(0.8~4); even more preferably, the molar ratio of the self-assembled material to the halobenzene is 1:(1~4); and even more preferably, the molar ratio of the self-assembled material to the halobenzene is 1:(1~2).

[0013] Preferably, the self-assembling material includes [2-(9H-carbazole-9-yl)ethyl]phosphonic acid (2PACz) and [2-(3,6-dimethyl-9H-carbazole-9-yl)ethyl]phosphonic acid (Me 2PACz), [2-(3,6-dimethoxy-9H-carbazole-9-yl)ethyl]phosphonic acid (MeO) 2PACz), [4-(3,6-dimethoxy-9H-carbazole-9-yl)butyl]phosphonic acid (4PACz), [4-(3,6-dimethyl-9H-carbazole-9-yl)butyl]phosphonic acid (Me 4PACz), [4-(3,6-dimethoxy-9H-carbazole-9-yl)butyl]phosphonic acid (MeO) At least one of 4PACz and [4-(7H-dibenzo[c,g]carbazole-7-yl)butyl]phosphonic acid (4PADCB); more preferably, the self-assembled material comprises 4PADCB.

[0014] Preferably, the halobenzene includes at least one of 1,3,5-trifluorobenzene, 1,3,5-trichlorobenzene, and 1,3,5-tribromobenzene.

[0015] Preferably, the self-assembled material comprises 4PADCB, and the halobenzene comprises at least one of 1,3,5-trifluorobenzene (TFB), 1,3,5-trichlorobenzene (TCB), and 1,3,5-tribromobenzene (TBB). In this invention, the halobenzene interacts with the self-assembled material via π–π stacking to form a dimer structure, thereby inhibiting the self-polymerization of the self-assembled material in solution.

[0016] In some embodiments of the present invention, the self-assembly material is 4PADCB and the halogenated benzene is 1,3,5-trifluorobenzene.

[0017] In some embodiments of the present invention, the self-assembly material is 4PADCB and the halobenzene is 1,3,5-trichlorobenzene.

[0018] In some embodiments of the present invention, the self-assembly material is 4PADCB and the halobenzene is 1,3,5-tribromobenzene.

[0019] TFB, TCB, or TBB exhibit strong π–π stacking interactions with 4PADCB. The halogen substituents on TFB, TCB, or TBB increase the polarizability of the π-electron system, enhancing the contribution of the London dispersion force to the π–π stacking interaction. The halogen atoms in all three molecules can extract electrons from the benzene ring π-conjugated system, resulting in a weakly negative overall electrostatic potential (ESP). Simultaneously, the carbazole core of 4PADCB acts as a strong electron-donating group, forming complementary charge characteristics with each of the three molecules. All three molecules form a conjugated planar conformation with 4PADCB, where the benzene ring plane is parallel to the carbazole plane of 4PADCB. Therefore, TFB, TCB, and TBB can effectively disperse 4PADCB in perovskite precursor solutions.

[0020] In a second aspect, the present invention provides a self-assembled monolayer formed from the self-assembled monolayer material described in the first aspect.

[0021] A self-assembled monolayer formed from a self-assembled monolayer material including the material described in the first aspect.

[0022] The present invention also provides a method for preparing a self-assembled monolayer, wherein the self-assembled monolayer material is prepared into a solution and then spin-coated onto a substrate to form the self-assembled monolayer on the substrate.

[0023] Preferably, the preparation method involves adding a self-assembled monolayer material to a perovskite precursor solution and then spin-coating it onto a substrate.

[0024] Thirdly, the present invention provides the application of the self-assembled monolayer described in the second aspect.

[0025] The present invention provides a hole transport layer comprising a self-assembled monolayer formed of the self-assembled monolayer material described in the first aspect.

[0026] The present invention provides a perovskite precursor solution comprising the self-assembled monolayer material described in the first aspect, a precursor salt, and a solvent.

[0027] Preferably, the precursor salt material has the general structural formula ABX3; wherein the cation at the A site is a monovalent cation, such as methylamine ion (CH3NH3). + ), dimethylamine ion ((CH3)2NH2) + Formamidinium ion (CH3NH2) + Acetamidinium ion (C2H5NH3) + ), cesium ions (Cs) + ), rubidium ions (Rb + ), guanidine ion (C(NH2)3) +One or more of the following; the B-site cation is a divalent metal cation, such as lead ion (Pb). 2+ ), tin ions (Sn) 2+ ) and germanium ions (Ge 2+ One or more of the following; the X position is an anion, such as a halide anion, which can be selected from a bromide ion (Br). ), iodide ions (I ), chloride ions (Cl) ), thiocyanate ions (SCN) ), tetrafluoroborate ion (BF4) ) and hexafluoroborate ions (BF6) One or more of the following.

[0028] More preferably, the precursor salt material includes at least one selected from formamidinium iodide (FAI), cesium iodide (CsI), methylamine iodide (MAI), lead iodide (PbI2), stannous iodide (SnI2), methylamine bromide (MABr), formamidinium bromide (FABr), and lead bromide (PbBr2); even more preferably, the precursor salt material includes at least one selected from formamidinium iodide (FAI), cesium iodide (CsI), methylamine iodide (MAI), and lead iodide (PbI2); even more preferably, the precursor salt material includes formamidinium iodide (FAI), cesium iodide (CsI), methylamine iodide (MAI), and lead iodide (PbI2).

[0029] Preferably, the solvent includes at least one of N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), N-methylpyrrolidone (NMP), and a ternary cosolvent system; more preferably, the solvent of the solution includes DMF and DMSO.

[0030] In some embodiments of the present invention, the solvent is DMF and DMSO, and the volume ratio of DMF to DMSO is 1:(0.1~1); in some specific embodiments of the present invention, the solvent is DMF and DMSO, and the volume ratio of DMF to DMSO is 1:(0.2~0.8); in some examples of the present invention, the solvent is DMF and DMSO, and the volume ratio of DMF to DMSO is 1:(0.25~0.4).

[0031] Preferably, the total concentration of precursor salts in the perovskite precursor solution is 1.0~2.0 mol / L; more preferably, the total concentration of precursor salts in the perovskite precursor solution is 1.2~1.8 mol / L; and even more preferably, the total concentration of precursor salts in the perovskite precursor solution is 1.4~1.6 mol / L.

[0032] In some embodiments of the present invention, the perovskite precursor solution further includes at least one of a defect passivating agent and a crystallization regulator; in some specific embodiments of the present invention, the defect passivating agent includes at least one of PbI2, 1,3-propanediamine dihydroiodate (PDADI), polymethyl methacrylate (PMMA), and phenethylamine iodine (PEAI), and / or, the crystallization regulator includes at least one of methylammonium chloride (MACl) and formamidine acetate (FAAc); in some examples of the present invention, the perovskite precursor solution further includes PbI2 and MACl.

[0033] In some embodiments of the present invention, the concentration (mol / L) of the defect passivating agent in the perovskite precursor solution is 2-5%; in some specific embodiments of the present invention, the concentration (mol / L) of the defect passivating agent in the perovskite precursor solution is 3-5%; in some examples of the present invention, the concentration (mol / L) of the defect passivating agent in the perovskite precursor solution is 4-5%.

[0034] In some embodiments of the present invention, the concentration (mol / L) of the crystallization regulator in the perovskite precursor solution is 5-10%; in some specific embodiments of the present invention, the concentration (mol / L) of the crystallization regulator in the perovskite precursor solution is 7-10%; in some examples of the present invention, the concentration (mol / L) of the crystallization regulator in the perovskite precursor solution is 8-10%.

[0035] Preferably, the concentration of the self-assembled material in the perovskite precursor solution is 0.1~0.5 mg / mL; more preferably, the concentration of the self-assembled material in the perovskite precursor solution is 0.15~0.45 mg / mL; and even more preferably, the concentration of the self-assembled material in the perovskite precursor solution is 0.2~0.4 mg / mL.

[0036] Preferably, the concentration of halobenzene in the perovskite precursor solution is 0.1~0.5 mg / mL; more preferably, the concentration of halobenzene in the perovskite precursor solution is 0.15~0.45 mg / mL; and even more preferably, the concentration of halobenzene in the perovskite precursor solution is 0.2~0.4 mg / mL.

[0037] This invention provides a method for preparing a perovskite precursor solution, wherein a self-assembled monolayer material and a precursor salt are dissolved in a solvent.

[0038] The present invention also provides a method for preparing a perovskite precursor solution, comprising the following steps: (1) dissolving a precursor salt in a solvent according to a stoichiometric ratio to obtain a first solution; (2) dissolving a self-assembled monolayer material in a solvent to obtain a second solution; and (3) mixing the second solution with the first solution to obtain the perovskite precursor solution.

[0039] In some embodiments of the present invention, the perovskite precursor solution further includes a defect passivator and a crystallization regulator; in some specific embodiments of the present invention, the defect passivator and the crystallization regulator are added in step (1) to form a first solution.

[0040] Preferably, the solvents used in steps (1) and (2) of the method for preparing the perovskite precursor solution are the same.

[0041] Preferably, in step (3), the mixing method includes stirring; more preferably, the stirring time is 18~30h; even more preferably, the stirring time in step (3) is 20~28h; even more preferably, the stirring time in step (3) is 22~26h.

[0042] The present invention also provides a perovskite thin film comprising a self-assembled monolayer and a perovskite light-absorbing layer as described in the second aspect of the present invention, which are stacked on a conductive substrate.

[0043] The present invention also provides another perovskite thin film, comprising a hole transport layer and a perovskite light-absorbing layer stacked on a conductive substrate; the hole transport layer comprises the self-assembled monolayer described in the second aspect of the present invention.

[0044] The present invention also provides a method for preparing a perovskite thin film: coating a perovskite precursor solution onto a conductive substrate, annealing the solution, and forming the perovskite thin film on the conductive substrate; wherein, the self-assembled monolayer material in the perovskite precursor solution forms a self-assembled monolayer on the conductive substrate, and the precursor salt in the perovskite precursor solution forms a perovskite light-absorbing layer.

[0045] The present invention also provides a perovskite solar cell comprising the self-assembled monolayer described in the second aspect of the present invention.

[0046] The present invention also provides a perovskite solar cell, including a hole transport layer; the hole transport layer includes the self-assembled monolayer described in the second aspect of the present invention.

[0047] The present invention also provides a perovskite solar cell, comprising a perovskite thin film; the perovskite thin film comprising a self-assembled monolayer and a perovskite light-absorbing layer as described in the second aspect of the present invention, stacked on a conductive substrate.

[0048] The present invention also provides another perovskite solar cell, comprising a conductive substrate, a perovskite thin film, an electron transport layer and an electrode layer stacked sequentially; the perovskite thin film includes a self-assembled monolayer and a perovskite light-absorbing layer as described in the second aspect of the present invention, stacked on the conductive substrate.

[0049] Preferably, the conductive substrate includes at least one of fluorine-doped tin oxide (FTO) conductive glass and indium tin oxide (ITO) conductive glass.

[0050] Preferably, the thickness of the conductive substrate is 10nm~100nm; more preferably, the thickness of the conductive substrate is 10nm~80nm; even more preferably, the thickness of the conductive substrate is 15nm~70nm; even more preferably, the thickness of the conductive substrate is 20nm~60nm.

[0051] Preferably, the material of the electron transport layer includes at least one of C60, titanium dioxide (TiO2), tin dioxide (SnO2), zinc oxide (ZnO), and methyl [6,6]-phenyl-C61-butyrate (PCBM).

[0052] Preferably, the thickness of the electron transport layer is 20nm~60nm; more preferably, the thickness of the electron transport layer is 25nm~55nm; and even more preferably, the thickness of the electron transport layer is 30nm~50nm.

[0053] Preferably, the material of the electrode layer includes at least one of silver, gold, copper, and bismuth.

[0054] Preferably, the thickness of the electrode layer is 50 nm to 1 μm; more preferably, the thickness of the electrode layer is 60 nm to 800 nm; and even more preferably, the thickness of the electrode layer is 80 nm to 500 nm.

[0055] The present invention also provides a method for preparing a perovskite solar cell, comprising coating a perovskite precursor solution onto a conductive substrate, annealing it to form a perovskite thin film; and sequentially preparing an electron transport layer and an electrode layer on the side of the perovskite thin film away from the conductive substrate to obtain the perovskite solar cell.

[0056] The present invention provides a photovoltaic module comprising the self-assembled monolayer described in the second aspect of the present invention.

[0057] The present invention also provides another photovoltaic module, including a hole transport layer, said hole transport layer comprising the self-assembled monolayer described in the second aspect of the present invention.

[0058] The present invention also provides another photovoltaic module, including a perovskite thin film, said perovskite thin film comprising a self-assembled monolayer and a perovskite light-absorbing layer as described in the second aspect of the present invention, stacked on a conductive substrate.

[0059] The present invention also provides another photovoltaic module, including a perovskite solar cell, wherein the perovskite solar cell comprises a conductive substrate, a perovskite thin film, an electron transport layer and an electrode layer stacked sequentially; the perovskite thin film comprises a self-assembled monolayer and a perovskite light-absorbing layer as described in the second aspect of the present invention, stacked on the conductive substrate.

[0060] Preferably, the photovoltaic module has a size of 200×600 mm. 2 More preferably, the photovoltaic module has a size of 250×500 mm. 2 More preferably, the photovoltaic module has a size of 250×500 mm. 2 .

[0061] The beneficial effects of this invention are as follows: 1. The self-assembled monolayer material provided by this invention includes a self-assembled material and a halobenzene, which can serve as a self-sacrificing molecular template. The halobenzene in the self-sacrificing molecular template can effectively inhibit the self-aggregation of the self-assembled material in solution, avoiding the formation of micelles and undesirable microaggregates in solution. The self-assembled monolayer mediated by the self-sacrificing molecular template improves the coverage and uniformity of the substrate, thereby improving the morphology, photoelectric properties, and mechanical toughness of the buried heterostructure interface. Furthermore, unlike traditional co-deposition strategies, the halobenzene in the self-sacrificing molecular template is completely volatilized after annealing. Therefore, this invention does not introduce external molecules into the final self-assembled monolayer, and can form a pure, uniform, and dense self-assembled monolayer at the buried interface.

[0062] 2. This invention provides a perovskite solar cell using a pure, dense, and uniformly covered SAM layer as the hole transport layer. This results in a more uniform surface potential distribution, fewer defects, longer carrier lifetime, and enhanced interfacial toughness in the perovskite solar cell, ultimately achieving a high PCE of 26.15%. Based on this, a device with dimensions of 300 × 400 mm is fabricated. 2 The photoelectric conversion efficiency of solar cell modules can reach 20.86%. Attached Figure Description

[0063] Figure 1 shows the electrostatic potential distribution of TFB, TCB, and TBB, as well as schematic diagrams of the 4PADCB@TFB dimer, 4PADCB@TCB dimer, and 4PADCB@TBB dimer structures; Figure 2 shows the binding energy diagrams of the 4PADCB@TFB, 4PADCB@TCB, and 4PADCB@TBB dimers; Figure 3 shows the 1H NMR spectra of 4PADCB and self-assembled monolayer materials from Examples 3-6 in deuterated DMSO; Figure 4 shows the two-dimensional nuclear Overhauser effect spectra of 4PADCB alone and self-assembled monolayer material from Example 4 in deuterated DMSO; Figure 5 shows the particle size distribution of 4PADCB and self-assembled monolayer material from Example 4 in different solvents, and a schematic diagram of TBB disrupting the large micelles of 4PADCB; Figure 6 shows the equilibrium molecular structure of different materials adsorbed on the ITO surface. Figure 7 shows the residual distribution of ITO surface after chemically exfoliating different perovskite films; Figure 8 shows the schematic diagram of different self-assembled monolayer materials forming SAM layers on the ITO surface; Figure 9 shows the bottom surface morphology of different perovskite films, Rq and Ra of the bottom surface of different perovskite films, and grain size of different perovskite films; Figure 10 shows the contact potential difference distribution of different perovskite films, steady-state photoluminescence (PL) spectra of different perovskite films, time-resolved photoluminescence (TRPL) spectra of different perovskite films, and interface toughness of different perovskite films; Figure 11 shows the load-displacement Δ curve of different DCB samples; Figure 12 shows the performance of different perovskite solar cells and the performance of perovskite solar cell modules. Detailed Implementation

[0064] To enable those skilled in the art to better understand this application, the present invention will be further described in detail below with reference to embodiments. However, it should be understood that the following embodiments are merely preferred embodiments of the present invention, and the scope of protection of the present invention should be determined by the scope defined in the claims.

[0065] Furthermore, to better illustrate the present invention, numerous specific details are provided in the following detailed embodiments. Those skilled in the art should understand that the present invention can be practiced even without certain specific details. In some embodiments, raw materials, methods, and means well-known to those skilled in the art are not described in detail, in order to highlight the main points of the present invention. In the description of the present invention, it should be noted that conditions not specifically specified in the embodiments are performed under conventional conditions or conditions recommended by the manufacturer. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0066] The raw materials and instruments used in this invention are as follows: lead iodide (PbI2, purity 99.999%), purchased from Liaoning Youxuan New Energy Technology Co., Ltd.; formamidinium iodide (FAI, 99.5%), methylamine iodide (MAI, 99.5%), methylammonium chloride (MACl, 99.5%), cesium iodide (CsI, 99.99%), piperazine hydroiodide (PI, 99.5%), and fullerene C60, all purchased from Xi'an Yuri Solar Energy Technology Co., Ltd.; [4-(7H-dibenzo[c,g]carbazole-7-yl)butyl]phosphonic acid (4PADCB, 99.0%) and 1,3,5-tribromobenzene (TBB) were purchased from Tokyo Chemical Industry Co., Ltd.; N,N-dimethylformamide (DMF, anhydrous 99.8%), dimethyl sulfoxide (DMSO, anhydrous 99.9%), isopropanol (IPA, anhydrous 99.9%), and ethyl acetate (EA, anhydrous 99.8%) were purchased from Sigma-Aldrich; ethanol (EtOH, 99.5%) was purchased from Sinopharm Chemical Reagent Co., Ltd.; XRD pattern: Smartlab. 9kW, RIGAKU, Japan; X-ray source: Cu Kα radiation (λ = 1.5406Å), θ-2θ scanning mode, acquisition range: 3-50°, scanning speed: 20° / min; Video optical contact angle meter: Theta Flex, Biolin Scientific, Sweden; UV-Vis / NIR spectrophotometer: Model U-4100, Hitachi, Japan; Fluorescence spectrometer: inVia Qontor, Renishaw Ltd, UK, excitation wavelength: 325nm; Scanning electron microscope: Gemini SEM360, Zeiss, Germany, operating voltage: 2 kV; AFM microscope: Cypher ES, Oxford Instruments; AFM probe: silicon cantilever with Ti / Ir coating; Nano-infrared microscope: Anasys nanoIR3, Bruker; Time-resolved single-photon counting system: HORIBA Nanolog; Green laser diode (λ = 450 nm) as excitation source, excitation power density: 5 mW / cm², slit width: 2... nm, collection timescale of 400 nanoseconds; AXIS SUPRA+ photoelectron spectrometer: Thermo Fisher Scientific, USA; XPS measurements used an aluminum target Kα-ray source (energy 1486.6 eV, power 150 W, voltage 15 kV, current 10 mA). UPS measurements used an ultraviolet light source generated by a helium discharge lamp (energy 21.22 eV). Clean gold foil was used as the energy reference standard. The sampling depth was 1-10 nm, and the scanning area was 500 × 500 square micrometers.

[0067] The following examples further illustrate the present invention in detail. It should also be understood that the following examples are only for further explanation of the present invention and should not be construed as limiting the scope of protection of the present invention. Any non-essential improvements and adjustments made by those skilled in the art based on the above description of the present invention are within the scope of protection of the present invention. The specific process parameters, etc., in the following examples are merely examples within a suitable range; that is, those skilled in the art can make appropriate selections within the appropriate range based on the description herein, and are not intended to be limited to the specific values ​​in the examples below.

[0068] Example 1: A self-assembled monolayer material comprising 4PADCB and TFB; the molar ratio of TFB to 4PADCB is 1:1.

[0069] Example 2: A self-assembled monolayer material comprising 4PADCB and TCB; the molar ratio of TCB to 4PADCB is 1:1.

[0070] Example 3: A self-assembled monolayer material comprising 4PADCB and TFB; the molar ratio of TFB to 4PADCB is 1:2.

[0071] Example 4: A self-assembled monolayer material comprising 4PADCB and TFB; the molar ratio of TFB to 4PADCB is 1:1.

[0072] Example 5: A self-assembled monolayer material comprising 4PADCB and TFB; the molar ratio of TFB to 4PADCB is 2:1.

[0073] Example 6: A self-assembled monolayer material comprising 4PADCB and TFB; the molar ratio of TFB to 4PADCB is 4:1.

[0074] Example 1: A perovskite thin film comprising a self-assembled monolayer and a perovskite light-absorbing layer stacked together; the perovskite light-absorbing layer is composed of (FA... 0.95 MA 0.05 ) 0.95 Cs 0.05PbI3 (band gap: 1.55 eV) was prepared as follows: 1. Precursor salts FAI, CsI, MAI, and PbI2 were dissolved in 950 μL of a mixed solvent of DMF / DMSO (v / v, 4:1) to prepare a 1.5 M precursor salt solution according to the stoichiometric ratio; 5 mol% PbI2 and 10 mol% MACl were added to the solution to obtain the first solution; 2. The self-assembled monolayer material from Example 1 was added to a mixed solvent of DMF / DMSO (v / v, 4:1), wherein the concentrations of 4PADCB and TFB were both 6 mg / mL, to obtain the second solution; 3. 50 µL of the second solution was added to the first solution and stirred overnight to obtain a perovskite precursor solution; 4. 70 µL of the perovskite precursor solution was spin-coated onto an ITO conductive substrate; the spin-coating was performed in two steps, the first step at 2000 rpm for 10 seconds, and the second step at 5000 rpm. Spin-coating was performed at rpm for 40 seconds, followed by drop-coating of 250 μL of EA at a uniform speed 15 seconds before the end of the second step. The film was then annealed at 100 °C for 30 minutes to obtain a perovskite film.

[0075] Example 2 of the perovskite thin film differs from Example 1 of the perovskite thin film in that step 2 of this example uses a self-assembled monolayer material, while the rest is the same as Example 1 of the perovskite thin film.

[0076] Example 3 of the perovskite film differs from Example 1 of the perovskite film in that step 2 of this example uses a self-assembled monolayer material. Example 4 is otherwise the same as Example 1 of the perovskite film.

[0077] The difference between Comparative Example 1 and Example 1 of Perovskite Thin Film is that the self-assembled monolayer material in step 2 is only 4PADCB, which does not contain halobenzene. That is, step 2 is to add 4PADCB to a mixed solvent of DMF / DMSO (v / v, 4:1). The rest is the same as that of Example 1 of Perovskite Thin Film.

[0078] Example 1 of a perovskite solar cell: A perovskite solar cell, comprising, from bottom to top, sequentially stacked ITO conductive glass, a perovskite thin film, an electron transport layer, and an electrode layer; wherein the electron transport layer is C60 / SnO2, and the electrode layer is Ag; the perovskite thin film includes a stacked self-assembled monolayer and a perovskite light-absorbing layer; the self-assembled monolayer serves as a hole transport layer; the preparation method of the perovskite solar cell is as follows: the pre-patterned ITO conductive glass is ultrasonically cleaned for 30 minutes each in detergent solution, deionized water, and ethanol; then the ITO conductive glass is subjected to ultraviolet ozone cleaning for 15 minutes, and finally transferred to a glove box filled with nitrogen for later use; following the preparation process of the perovskite thin film in Example 3, the perovskite precursor solution is dropped onto the ITO conductive glass to obtain the perovskite thin film; to achieve surface passivation, PI (dissolved in isopropanol, concentration 1 mg / mL) is spin-coated onto the surface of the perovskite thin film at a speed of 5000 rpm for 25 seconds, and then coated at 100°C. Annealing at ℃ for 10 minutes; then, a 25 nm thick C60 layer was deposited at a rate of 0.2 Å / s via thermal evaporation, followed by a 15 nm thick SnO2 layer on the C60 layer via atomic layer deposition, and finally, a 100 nm thick silver electrode layer was deposited at a rate of 1.5 Å / s via thermal evaporation. Research and Verification I. Verification of the Elimination of Self-Assembled Material Self-Assemblies in Self-Assembled Monolayer Materials 1. Verification of the Interaction between Halogenated Benzenes and Self-Assembled Materials Figures 1a-c show the electrostatic potential distributions of TFB, TCB, and TBB, respectively; Figures 1d-f show the schematic diagrams of the 4PADCB@TFB dimer structure, the 4PADCB@TCB dimer structure, and the 4PADCB@TBB dimer structure, respectively. As shown in Figure 1, TFB, TCB, and TBB can exhibit strong π–π interactions with 4PADCB. The halogen substituents in the three molecules increase the polarizability of the π-electron system and enhance the contribution of London dispersion to the π-π stacking interaction. The halogen atoms in all three molecules extract electron density from the benzene π system, resulting in a slightly negative overall molecular ESP. Simultaneously, the carbazolium core of 4PADCB acts as a strong electron-donating group, forming complementary charge characteristics with these three molecules. The optimized dimer structure (Figures 1d-f) shows that all three molecules exhibit a conjugated planar conformation with 4PADCB, where the benzene ring plane is parallel to the carbazolium plane of 4PADCB. Therefore, TFB, TCB, and TBB each act as spacer molecules, effectively dispersing 4PADCB.

[0079] Figure 2 shows the binding energy diagrams of the dimers 4PADCB@TFB (SAM: TFB in Figure 2), 4PADCB@TCB (SAM: TCB in Figure 2), and 4PADCB@TBB (SAM: TBB in Figure 2). As shown in Figure 2, among the three molecules TFB, TCB, and TBB, TBB has the lowest binding energy at -74.72 kJ mol.- ¹ This is because bromine has the largest atomic radius and the highest polarizability, which significantly enhances the London dispersion force and π–π stacking interaction. 2. Testing the interaction between self-assembled materials and halobenzenes at different molar ratios. Figure 3 shows the 1H NMR spectra of 4PADCB (SAM in Figure 3), self-assembled monolayer material Example 3 (TBB:SAM=1:2 in Figure 3), self-assembled monolayer material Example 4 (TBB:SAM=1:1 in Figure 3), self-assembled monolayer material Example 5 (TBB:SAM=2:1 in Figure 3), and self-assembled monolayer material Example 6 (TBB:SAM=4:1 in Figure 3) in deuterated DMSO. In Figure 3a, the 1H NMR spectra of 4PADCB and self-assembled monolayer materials Examples 3-6 in deuterated DMSO are shown, and the magnified view of the 1H NMR spectra of 4PADCB and self-assembled monolayer materials Examples 3-6 in deuterated DMSO is shown at 8.00 ppm. As shown in Figure 3, when TBB is introduced into the self-assembled monolayer material, its proton peak appears at δ = 7.9 ppm. Furthermore, due to the aromatic proton demagnetization effect, the aromatic protons of 4PADCB shift to the low-field region by approximately 0.01 ppm, confirming that 4PADCB and TBB in Examples 3-6 of the self-assembled monolayer materials have intermolecular interactions.

[0080] Figure 4 shows the two-dimensional nuclear Overhauser effect spectra of isolated 4PADCB (Figure 4a) and the self-assembled monolayer of Example 4 (Figure 4b) in deuterated DMSO. In the figure, SAM represents the self-assembled material, i.e., 4PADCB. As shown in Figure 4, multiple new cross-peaks (purple circles) appear in the carbazole region of 4PADCB (F1, δ = 7.4-8.1 ppm), with a gradually increasing signal. Calculations and analysis show that the proton-proton distance decreases from 3.64 in the isolated SAM to 3.01 between the TBB aromatic protons and the carbazole unit in the SAM, indicating a very strong π-π packing and a more compact packing interaction between the TBB and the carbazole plane.

[0081] 3. Dynamic light scattering (DLS) was used to detect the particle size of 4PADCB and the self-assembled monolayer material from Example 4 in different solvents. The detection results are shown in Figure 5.

[0082] Figure 5 shows the particle size distribution of 4PADCB in DMF:DMSO (4:1 v:v) solvent (a, b, c, d, e, f). Figure 5 also shows the particle size distribution of 4PADCB in DMF:DMSO (4:1 v:v) solvent (a, b, c, d, e, f). Figure 5 also shows the particle size distribution of self-assembled monolayer material Example 4 in DMF:DMSO (4:1 v:v) solvent (e, f, f). In Figure 5, g illustrates the disruption of 4PADCB self-aggregating macromicelles by TBB. In Figure 5, "control" indicates that the self-assembled monolayer material contains only 4PADCB, and "SSMT" represents self-assembled monolayer material Example 4.

[0083] As shown in Figure 5, 4PADCB exists in two main aggregation states: large micelles with an average diameter of 114.07 nm and small micro-aggregates of 1.61 nm. These large micelles with outward-facing phosphate groups are the main factors limiting SAM diffusion and uniform adsorption. After the introduction of TBB, the electrostatic interaction and π-π stacking between TBB and 4PADCB generate structured molecular units, disrupting the large micelle assemblies (as shown in Figure 5g, where Perovskite, SAM, and Precursor collectively represent the dissolution of self-assembled monolayer materials in the perovskite precursor solution; Micellar structure represents micelles formed by the self-aggregation of a portion of the self-assembled materials; Intermediate state represents the intermediate state in which TBB inhibits the formation of micelles from the self-assembled materials; and Micelles disassemble represents micelle dissociation). The micelle size gradually decreases to 79.72 nm, while the intercalation of TBB between the aromatic planes of the four PADCBs to form scaffold-like units only causes slight expansion of the remaining micelle structure. Therefore, due to the π-π interaction with 4PADCB, TBB can effectively eliminate microaggregates and micelles and disperse 4PADCB in solution.

[0084] 4. The adsorption kinetics of SAM molecules (self-assembled monolayer materials) on the ITO surface are driven by the top-down crystallization of the perovskite film. Most SAM molecules spontaneously separate to the buried interface, and their phosphate ends bind to the hydroxyl groups in the ITO substrate. Molecular dynamics (MD) simulations were used to study the adsorption kinetics of SAM molecules on the ITO surface. The simulation results are shown in Figures 6a-6d. The adsorption model was constructed on a Sn-doped In2O3(111) ITO surface using a supercell with dimensions of 101.17 Å × 101.17 Å × 45.00 Å. In the top surface region, four molecular assemblies were constructed using Packmol: a) 135 4PADCB molecules; b) 135 4PADCB molecules and 135 TFB molecules; c) 135 4PADCB molecules and 135 TCB molecules; d) 135 4PADCB molecules and 135 TBB molecules. For all binary systems, the molar ratio of 4PADCB to co-adsorbed molecules was set to 1:1, consistent with experimental conditions. Classical molecular dynamics simulations were performed using the LAMMPS software package. The equations of motion were integrated using the Velocity Verlet algorithm with a time step of 1 fs. Simulations were conducted under a canonical ensemble (NVT) with temperature controlled using a Nosé-Hoover thermostat with a characteristic time constant of 0.1 ps. Periodic boundary conditions were set for the system in the x and y directions, with the bottom atomic layer fixed. The initial velocity was set at 298.15 K, followed by a 0.1 ns equilibrium phase. Subsequently, 1 ns sampling simulations were performed, with configuration samples acquired every 0.1 ns. Surface adsorption characteristics were analyzed using a custom script, calculating surface coverage by dividing SAM molecules into adjacent surface regions and identifying SAM atoms within a 3.5 Å range from the surface. For force field parameter settings, organic molecules were described using the OPLS-AA force field, and the ITO surface was modeled using the INTERFACE force field. The cross-interactions between molecules and the surface were obtained using geometric mixing rules. The atomic charge required for the OPLS-AA force field is determined based on the confined electrostatic potential (RESP) method, and this charge is calculated using Gaussian 16 software at the B3LYP / def2-TZVP theoretical level.

[0085] In Figure 6, a represents the equilibrium molecular configuration of 4PADCB adsorbed on the ITO (111) surface, b represents 4PADCB@TFB adsorbed on the ITO surface, c represents 4PADCB@TCB adsorbed on the ITO surface, and d represents 4PADCB@TBB adsorbed on the ITO surface. 4PADCB molecules are represented in gray, while TFB, TCB, and TBB are represented in cyan, orange, and red, respectively. As shown in Figures 6a-d, all three halobenzenes (TFB, TCB, and TBB) can alleviate the self-polymerization of 4PADCB on ITO, increasing the surface coverage from 65.8% to 70.6%, 71.2%, and 77.0%, respectively, with TBB exhibiting the highest molecular dispersibility.

[0086] Subsequently, the coverage of the self-assembled monolayer on the ITO surface was evaluated using atomic force microscopy-infrared spectroscopy (AFM-IR). Different ITO / perovskite film structures were prepared using the methods of Examples 1-3 and Comparative Example 1. The perovskite film deposited on the ITO surface was removed by DMF dynamic spin coating to expose the ITO surface, and then the P=O vibration band (1160 cm⁻¹) was mapped. - ¹) The distribution of residual 4PADCB on the ITO surface was analyzed, and the results are shown in Figures 6e–h.

[0087] In Figure 6, e represents the distribution of residual 4PADCB on the ITO surface in Comparative Example 1 of the perovskite film, f represents the distribution of residual 4PADCB on the ITO surface in Example 1 of the perovskite film, g represents the distribution of residual 4PADCB on the ITO surface in Example 2 of the perovskite film, and h represents the distribution of residual 4PADCB on the ITO surface in Example 3 of the perovskite film. As shown in Figures 6e-f, the distribution of 4PADCB on the exposed ITO surface in Comparative Example 1 of the perovskite film (a self-assembled monolayer formed only by 4PADCB) is highly uneven. In contrast, Example 3 of the perovskite film (introducing a TBB-mediated self-assembled monolayer) exhibits the most compact and uniform SAM coverage, superior to Example 1 of the perovskite film (introducing a TFB-mediated self-assembled monolayer) and Example 2 of the perovskite film (introducing a TCB-mediated self-assembled monolayer), confirming the MD simulation results.

[0088] In addition to the method of removing perovskite films using chemical solvents, this invention also employs mechanical delamination as a comparative method. The perovskite films in Comparative Example 1 and Example 3 were removed by mechanical peeling to expose ITO. The distribution of residual 4PADCB on the ITO surface was analyzed using the same method, and the results are shown in Figure 7. In Figure 7, a shows the distribution of residual 4PADCB on the ITO surface in Comparative Example 1 (control), and b shows the distribution of residual 4PADCB on the ITO surface in Example 3 (SSMT). As can be seen from Figure 7, the distribution of 4PADCB on the exposed ITO surface in Comparative Example 1 is highly uneven, while Example 3 exhibits a compact and uniform SAM coverage, consistent with the findings after chemical solvent removal of the perovskite film.

[0089] 5. Verification of the purity of the self-assembled monolayer: To confirm complete volatilization of TBB after annealing, X-ray photoelectron spectroscopy (XPS) was performed on the residual ITO surface after mechanical exfoliation of the perovskite film. The quantitative results are shown in Table 1. Table 1 shows that the P / In ratio of the perovskite film in Example 3 (including the SSMT-mediated self-assembled monolayer) is 2.37 × 10⁻⁶. -2 The value was significantly higher than that of the perovskite film comparative example 1 (1.46 × 10⁻⁶). -2 This indicates that the density of phosphate groups anchored on the ITO surface in the self-assembled monolayer formed via SSMT is higher. Importantly, no residual bromine signal was detected after annealing, confirming that TBB was completely removed from the SSMT.

[0090] Table 1. Detection data of residual atoms on the ITO surface after removing different perovskite films.

[0091] The surface coverage of the SAM layer formed after annealing and crystallization using only self-assembled material (4PADCB) is incomplete, as shown in Figure 8a. The above research and testing indicate that TFB, TCB, and TBB in Examples 1-6 of the self-assembled monolayer materials can suppress the inherent tendency of 4PADCB to self-aggregate into micro-aggregates and micelles in the perovskite precursor solution, effectively dispersing 4PADCB. The suppression process is shown in Figure 8b. In Figure 8, Perovskite Precursor Solution represents the perovskite precursor solution.

[0092] Therefore, in the self-assembled monolayer material provided by the embodiments of the present invention, the halobenzene and the self-assembled material can preferentially form a conjugated planar structure, thereby suppressing the formation of micro-aggregates and micelles. During the top-down crystallization process, these structures migrate to the buried heterostructure interface. After removing the halobenzene during annealing, a dense and uniform SAM layer is obtained at the ITO / perovskite film interface.

[0093] II. Study on the Surface Morphology of the Bottom of the Perovskite Film 1. Evaluation of the Influence of Self-Assembled Monolayers on the Bottom Surface Morphology of the Perovskite Film The perovskite films in Comparative Example 1 and Example 3 were mechanically peeled off to expose the bottom surface of the perovskite films. Subsequently, high-resolution atomic force microscopy (AFM) was used to acquire height distribution data for analysis, and the results are shown in Figures 9a-b. The root mean square roughness (Rq) and average roughness (Ra) values ​​of the bottom surface of the perovskite film are shown in Figure 9c.

[0094] Figure 9a shows the bottom surface morphology of the perovskite film in Comparative Example 1, Figure 9b shows the bottom surface morphology of the perovskite film in Example 3, Figure 9c shows the bottom surface of the perovskite film in Comparative Example 1, and Rq and Ra of the bottom surface of the perovskite film in Example 3. In the figures, control represents Comparative Example 1, and SSMT represents Example 3.

[0095] As shown in Figures 9a-b, compared with Comparative Example 1, the bottom surface of the perovskite film in Example 3 exhibits significantly fewer voids and lower surface undulations. This is quantitatively verified by the simultaneous decrease in both Rq and Ra values ​​of the bottom surface of Example 3 (Figure 9c). The significant reduction in Rq value confirms that the bottom surface of Example 3 has fewer voids and lower undulations. This is because the self-assembled material 4PADCB can effectively reduce the surface energy of ITO. The dense and uniform 4PADCB monolayer can make the surface energy of the ITO surface highly uniformly distributed. This chemical homogeneity homogenizes nucleation and grain growth, thereby giving the bottom surface of the perovskite film a more uniform morphological characteristic. In addition, the elimination of micelles and micro-aggregates also helps to reduce surface undulations, thus avoiding the problem of depressions on the bottom surface of the perovskite film caused by such undulations. In contrast, in Comparative Example 1, the SAM layer of the perovskite film is not completely covered on the ITO surface, resulting in a random and disordered surface energy distribution. The hydroxyl groups on the uncovered ITO regions create localized areas of low surface energy, inducing premature nucleation and generating more nucleation sites. This exacerbates the structural heterogeneity of the grain surface, thereby increasing the overall height variation of the film. Furthermore, the large micelles aggregated at the bottom interface also leave depressions and voids on the bottom surface of the perovskite film. 2. Evaluation of the Influence of Self-Assembled Monolayers on the Grain Size of Perovskite Films. The grain size of the perovskite film was observed using scanning electron microscopy (SEM), and the results are shown in Figures 9d-e. Figure 9d is the SEM image of the bottom surface of the perovskite film in Comparative Example 1, and Figure 9e is the SEM image of the bottom surface of the perovskite film in Example 3. As shown in Figures 9d-e, compared to Comparative Example 1, the perovskite film in Example 3 has a larger grain size. This is because the SAM layer mediated by SSMT can completely and uniformly cover the ITO substrate. This complete coverage forms a uniform ITO surface, reduces the ITO surface energy, lowers the density of heterogeneous nucleation sites, and achieves sufficient lateral grain growth. The reduced porosity observed in the SEM images is also consistent with the conclusions drawn from the AFM morphology images in Figures 9a-b.

[0096] III. Study on the bottom surface properties of perovskite films To evaluate the influence of the self-assembled monolayer formed by SSMT on the bottom surface properties of perovskite films, different perovskite films were mechanically peeled from ITO substrates to expose their bottom surfaces. The contact potential difference (CPD) distribution of the perovskite films was then mapped using Kelvin probe force microscopy (KPFM), and the mapping results are shown in Figures 10a-c.

[0097] Figure 10a shows the contact potential difference distribution of the perovskite film in Comparative Example 1, Figure 10b shows the contact potential difference distribution of the perovskite film in Example 3, and Figure 10c shows the CPD statistical distribution. In Figure 10c, "control" represents Comparative Example 1, and "SSMT" represents Example 3. As shown in Figures 10a-c, Example 3 (including the self-assembled monolayer mediated by SSMT) exhibits a more uniform CPD distribution. This is because SSMT eliminates voids and large surface undulations in the self-assembled monolayer, avoiding the problem of such defects introducing additional electronic defect states. Furthermore, the grains in Example 3 have a homogenized structure, which promotes a uniform distribution of electronic states, thereby achieving a uniform CPD distribution.

[0098] Steady-state photoluminescence (PL) and time-resolved photoluminescence (TRPL) spectra were measured on the bottom surfaces of different perovskite films. The test results are shown in Figures 10d-e. In Figure 10, d represents the steady-state photoluminescence (PL) spectrum, and e represents the time-resolved photoluminescence (TRPL) spectrum. In the figures, control represents perovskite film comparative example 1, and SSMT represents perovskite film example 3.

[0099] As shown in Figures 10d-e, the perovskite thin film of Example 3 exhibits a stronger PL intensity, with the carrier lifetime extending from 160 nanoseconds to 240 nanoseconds. This indicates that nonradiative recombination on the bottom surface of the perovskite thin film is suppressed. The elimination of structural defects and the reduction of surface undulations make the surface structure of the perovskite thin film more homogeneous, thereby effectively reducing the defect state density and extending the carrier lifetime.

[0100] The interfacial toughness G of the ITO / perovskite thin film structure was further quantitatively determined using the sandwich double cantilever beam (DCB) method. C The test results are shown in Figure 10f. In Figure 10f, the bar chart and error bars represent the average and standard deviation obtained from four independent measurements under each condition, respectively.

[0101] The testing method was as follows: DCB samples containing a glass / ITO / perovskite thin film / PMMA / epoxy resin / ITO / glass structure were fabricated, wherein the perovskite thin film was a SAM layer / perovskite light-absorbing layer, and the sample size was 37.5 × 12.5 × 1 cubic millimeter. Different samples were prepared using perovskite thin film Example 3 and Perovskite thin film Comparative Example 1, respectively. Then, a PMMA layer (800 nm) was deposited on the perovskite light-absorbing layer of different samples. The deposition method was a spin-coating deposition of PMMA solution (8 wt%, dissolved in CB) at a speed of 3000 rpm, followed by storage in dry air for 24 hours. A thin epoxy resin film (approximately 2 μm) was then coated on the PMMA surface, and a Glass / ITO substrate was bonded to it. Before coating the epoxy resin film, a notch of approximately 5 mm was made at the short edge using tape. The DCB samples were then stored in dry air for 24 hours, after which excess epoxy resin was carefully removed from other edges before mechanical testing. Before testing, a fine blade was inserted into the notch to introduce a planar pre-crack. Aluminum plates were then mounted on both sides of the substrate at the crack tip. An initial preload of 0.2 Newtons was applied to ensure proper contact between the sample and the test fixture. The test was performed using a layered testing system (DTS, USA) at 1 micrometer per second. -1 A displacement rate was applied to apply a tensile load to the notched DCB sample until stable planar crack propagation was achieved at the ITO / perovskite film interface within the sample. The load (P)-displacement (Δ) response was recorded throughout the process. The sample was then partially unloaded and reloaded, and the crack length α was estimated using the stiffness method and correlated with the following relationship: Where B (12.5 mm) and E (70 GPa) are the width and Young's modulus of the glass substrate, respectively, and h (1 mm) is the half-thickness of the DCB sample. Toughness G C It is calculated using the following formula: ;where P C This is the load at the nonlinear starting point of the load (P)-displacement (Δ) curve during the loading cycle. The loading and unloading cycle was repeated four times, and G was calculated for all four cycles. C (Excluding the initial "placement" loading period).

[0102] The P-Δ curves of different DCB samples are shown in Figure 11. In Figure 11, a is the DCB sample of Comparative Example 1, which includes a perovskite film, and b is the DCB sample of Example 3, which includes a perovskite film.

[0103] In Figure 10f, "control" represents Comparative Example 1 of the perovskite film, and "SSMT" represents Example 3 of the perovskite film. As shown in Figures 10f and 11, compared to Comparative Example 1, the ITO / perovskite film in Example 3 (after SSMT treatment) exhibits higher interfacial toughness, increasing from 0.424 J·m. -² Increased to 0.474 J·m - ² This is because the self-assembled monolayer mediated by SSMT treatment eliminates voids at the interface, thereby eliminating areas with weak adhesion, which are prone to interfacial delamination under external stress.

[0104] IV. Performance Study of Perovskite Solar Cells A perovskite solar cell fabricated with a SAM layer formed by self-assembled material (4PADCB) was used as a blank control. The current density-voltage (JV) curves, steady-state power output, external quantum efficiency, and photoelectric conversion efficiency of the perovskite solar cell Example 1 were tested. The test results are shown in Figure 12. In Figure 12, control represents the blank control, and SSMT represents perovskite solar cell Example 1. In Figure 12, a is the current density-voltage (JV) curve of different perovskite solar cells, with a mask aperture of 0.09 cm²; b is the steady-state power output (SPO) at the maximum power point of different perovskite solar cells; c is the external quantum efficiency (EQE) spectrum of different perovskite solar cells; d is the statistical distribution of photoelectric conversion efficiency (PCE) values ​​of different perovskite solar cells; and e is the analysis of open-circuit voltage loss of different perovskite solar cells.

[0105] The JV curves of the perovskite solar cells were measured using a source meter (2400, Keithley, USA) under AM 1.5G standard sunlight irradiation (100 mW·cm²) generated by a solar simulator (Oriel Sol3A Class AAA, Newport, USA). - ²). The typical effective area of ​​the cell is 0.09 cm², defined by a metal mask. Standard solar AM 1.5G intensity was calibrated using a silicon reference cell certified by the National Renewable Energy Laboratory (NREL). External quantum efficiency (EQE) data were measured using a solar cell quantum efficiency testing system (QE-R3011, Enlitech) in AC mode with a chopping frequency of 210 Hz.

[0106] As shown in Figures 12a-d, the perovskite solar cell of Example 1 achieved a high PCE of 26.15% (VOC = 1.186V, JSC = 25.61 mA cm², FF = 86.03%), which is superior to the performance of the blank control cell (24.93%; VOC = 1.173V, JSC = 25.07 mA cm², FF = 84.78%). This indicates that the dense and uniform 4PADCB monolayer structure effectively passivates the interface between the ITO surface and the bottom of the perovskite film. This structure can also significantly suppress interfacial nonradiative recombination, thereby improving the open-circuit voltage (VOC) and fill factor (FF).

[0107] The main loss mechanisms of perovskite solar cells include radiative and nonradiative recombination, as well as energy level mismatch within the device. The photoluminescent quantum yield (PLQY) of different perovskite thin films was measured using a photoluminescence quantum yield testing system (LQ-100X, Enlitech). The test results are shown in Figure 12e. In Figure 12e, bandgap represents the bandgap reference; No rad. Limit represents the theoretical or limiting open-circuit voltage; SQ limit represents the theoretical maximum photoelectric conversion efficiency achievable by a single-junction solar cell under sunlight; Voc measured represents the measured open-circuit voltage; nonradiative recombination represents nonradiative recombination; Energetic mismatch represents energy level mismatch; and Thermodynamic and radiative recombination represents thermodynamic and radiative recombination.

[0108] As shown in Figure 12e, based on the photoluminescent quantum yield (PLQY) measurement, the nonradiative recombination loss decreased from 79 mV to 68 mV, while the loss caused by energy level mismatch decreased by about 3 mV.

[0109] Based on Example 1 of the perovskite solar cell, a perovskite solar cell module with an area of ​​300 × 400 mm² was fabricated on a larger scale using the same structure and fabrication method. The performance of the solar cell module (SSMT in Figure 12f) was then tested. The test results are shown in Figure 12f, where the two curves represent the reverse current density J-voltage V scan curve and the output power curve, respectively. As shown in Figure 12f, the solar cell module achieved a photoelectric conversion efficiency of 20.86%, demonstrating the excellent compatibility of this invention with the manufacturing process of large-area perovskite solar cell modules.

[0110] The operational stability of the perovskite solar cell module prepared in Example 1 was evaluated using maximum power point tracking (MPPT) under continuous standard solar intensity. A control group was prepared using a perovskite solar cell module with a SAM layer formed by a single self-assembled material (4PADCB). The test light source consisted of a constant-current driven array of white LEDs (MG-A200A-AE, emission spectrum range 400-750 nm), and the test environment was a nitrogen atmosphere. The test followed the ISOS-L-1 standard protocol, and continuous MPPT was performed in a nitrogen-filled glove box without active cooling (measured device temperature 25 ± 5 °C).

[0111] The test results are shown in Figure 12f. As can be seen from Figure 12f, the cell module based on perovskite solar cell Example 1 (SSMT in Figure 12e) exhibits excellent stability, maintaining 80% of its initial photoelectric conversion efficiency after 1024 hours of continuous operation. In contrast, the cell module of the blank control group (control in Figure 12e) only operated for 600 hours under the same conditions, and its photoelectric conversion efficiency dropped to 80% of the initial photoelectric conversion efficiency. With the extension of operating time, the photoelectric conversion efficiency continued to decrease.

[0112] In summary, this invention proposes using a self-assembled monolayer material as the SSMT. The halobenzene in the SSMT effectively suppresses the self-aggregation of the self-assembled material in solution through conjugated π-π interactions. The halobenzene forms a conjugated planar structure with the self-assembled material (e.g., 4PADCB), which completely volatilizes after annealing, depositing a pure, uniform, and compact SAM layer at the bottom interface. This invention enables more uniform SAM surface energy and perovskite film crystallization, reduces voids and undulations on the bottom surface of the perovskite film, achieves uniform potential distribution, suppresses deep defects, and improves the interfacial toughness of the buried interface. The pin-type perovskite solar cell prepared by the SSMT-mediated self-assembled monolayer achieves an excellent photoelectric conversion efficiency of 26.15%. Furthermore, the SSMT-mediated self-assembled monolayer also exhibits significant performance in a 300×400 mm² perovskite solar cell module, and its operational stability is significantly improved during maximum power point tracking testing according to the international standardized testing protocol ISOS-L-1l.

[0113] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A self-assembled monolayer material, characterized in that, This includes self-assembling materials and halogenated benzenes.

2. The self-assembled monolayer material according to claim 1, characterized in that, The halobenzene interacts with the self-assembled material via a π–π stacking interaction.

3. The self-assembled monolayer material according to claim 1 or 2, characterized in that, The molar ratio of the self-assembled material to the halobenzene is 1:(0.5~4).

4. The self-assembled monolayer material according to claim 1 or 2, characterized in that, The self-assembly materials include 2PACz and Me. 2PACz、MeO 2PACz、4PACz、Me 4PACz、MeO At least one of 4PACz and 4PADCB.

5. The self-assembled monolayer material according to claim 1 or 2, characterized in that, The halobenzene includes at least one of 1,3,5-trifluorobenzene, 1,3,5-trichlorobenzene, and 1,3,5-tribromobenzene.

6. A self-assembled monolayer, characterized in that, It is formed from a self-assembled monolayer material including any one of claims 1-5.

7. A hole transport layer, characterized in that, Includes the self-assembled monolayer as described in claim 6.

8. A perovskite precursor solution, characterized in that, Includes the self-assembled monolayer material, precursor salt, and solvent as described in any one of claims 1-5.

9. A perovskite thin film, characterized in that, It includes the self-assembled monolayer and perovskite light-absorbing layer as described in claim 6, which are stacked on a conductive substrate.

10. A method for preparing a perovskite thin film, characterized in that, The perovskite precursor solution of claim 8 is coated onto a conductive substrate and annealed to form the perovskite film on the conductive substrate; wherein, the self-assembled monolayer material in the perovskite precursor solution forms a self-assembled monolayer on the conductive substrate, and the precursor salt in the perovskite precursor solution forms a perovskite light-absorbing layer.

11. A perovskite solar cell, characterized in that, It includes at least one of the self-assembled monolayer of claim 6, the hole transport layer of claim 7, and the perovskite thin film of claim 9.

12. A method for fabricating a perovskite solar cell, characterized in that, The perovskite precursor solution of claim 8 is coated onto a conductive substrate and annealed to form a perovskite thin film; an electron transport layer and an electrode layer are sequentially prepared on the side of the perovskite thin film away from the conductive substrate to obtain the perovskite solar cell.

13. A photovoltaic module, characterized in that, It includes at least one of the self-assembled monolayer of claim 6, the hole transport layer of claim 7, the perovskite thin film of claim 9, and the perovskite solar cell of claim 11.

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