Self-assembled monolayer hole transport material, preparation method and application thereof

Abstract

The application discloses a kind of self-assembly monolayer hole transport materials and its preparation method and application, it is related to solar cell technical field.Self-assembly monolayer hole transport material includes at least one of chemical structural formula shown in formula (I) or formula (II), by introducing pyrene and indole fused heterocyclic structure as the core functional group of self-assembly monolayer hole transport material, the energy level matching ability of material, self-assembly order and interface coverage integrity are improved, the charge transport and defect passivation effect of transparent conductive substrate / perovskite buried bottom interface are improved, the interface non-radiative recombination loss is reduced, so as to improve the photoelectric conversion efficiency and long-term running stability of perovskite solar cell.

Description

Technical Field

[0001] This invention relates to the field of solar cell technology, specifically to a self-assembled monolayer hole transport material, its preparation method, and its application. Background Technology

[0002] Currently, in the field of perovskite solar cells, self-assembled monolayers (SAMs) have become one of the most promising hole interface materials due to their advantages such as designable molecular structure, tunable interface energy levels, ultra-thin film, and low parasitic absorption loss. SAM molecules are mainly composed of anchoring groups, conjugated bridging units, and terminal functional groups. Among them, the conjugated bridging units not only affect the frontier orbital energy levels and interface dipoles of the molecule, but also play an important role in intermolecular interactions, self-assembly order, and surface coverage integrity.

[0003] Existing high-performance SAM materials mostly use traditional aromatic conjugated structures such as carbazole and triphenylamine as the core framework. Although such materials can achieve selective hole extraction and transport to a certain extent, their shortcomings are becoming increasingly prominent as tandem solar cells continue to develop towards higher efficiency and higher stability. On the one hand, the HOMO energy level tuning window of the existing classic core framework is limited, making it difficult to fully adapt to the higher requirements of hole selective contact for wide-bandgap perovskite absorber layers, which easily leads to interface energy level mismatch, hole accumulation, and open-circuit voltage loss. On the other hand, the existing conjugated framework has limited ability to regulate the arrangement on the transparent conductive oxide (TCO) surface, and the monolayer formed still has shortcomings in terms of orderliness, density, and coverage integrity, which easily causes local pinholes or defect areas, thereby aggravating nonradiative recombination at the interface.

[0004] Furthermore, under continuous thermal stress and light exposure, the molecular configuration or interfacial adsorption state of some traditional aromatic framework SAMs is prone to change, leading to weakened interfacial passivation and decreased carrier selectivity, thereby affecting the long-term operational stability of the device.

[0005] Therefore, there is an urgent need for a new type of SAM material that can achieve better interface energy level matching, stronger buried interface passivation effect, and higher structural stability. Summary of the Invention

[0006] One objective of the first aspect of this invention is to provide a self-assembled monolayer hole transport material that solves the technical problems of insufficient interface stability, limited passivation effect of interface defects, and unsatisfactory energy level matching in the prior art.

[0007] Another objective of the first aspect of the present invention is to further fine-tune the energy level positions and interface interaction strengths of the core framework.

[0008] The second aspect of this invention aims to provide a method for preparing the above-mentioned self-assembled monolayer hole transport material.

[0009] A third aspect of the present invention aims to provide a perovskite solar cell comprising a self-assembled monolayer hole transport material as described in any one of the preceding claims.

[0010] According to a first aspect of the present invention, the present invention provides a self-assembled monolayer hole transport material comprising at least one chemical structure of formula (I) or formula (II): or In formula (I), R is selected from alkylene groups; R1 is selected from at least one of phosphonic acid group, boric acid group, carboxylic acid group or sulfonic acid group; R2, R3, R4, and R5 are each independently selected from H, alkyl, alkoxy, or thiooxy groups; R6, R7, R8, R9, R 10 R 11 R 12 R 13 Each is independently selected from H; In formula (II), R is selected from alkylene groups; R 14 R 15 Selected from at least one of phosphonic acid group, carboxylic acid group or sulfonic acid group; R 16 R 17 R 18 R 19 R 20 R 21 R 22 R 23 Each is independently selected from H, alkyl, alkoxy, or thiooxy; R 24 R 25 R 26 R 27 R 28 R 29 Each is independently selected from H.

[0011] Optionally, R is selected from C1-C6 alkylene groups, and R1 and R2 are... 14 and R 15 All of them are phosphonic acid groups, namely R2, R3, R4, R5, and R6. 16 R 17 R 18 R 19 R 20 R 21 R 22 and R 23 Each is independently selected from H, methyl, methoxy, or C1-C6 alkylthio groups.

[0012] Optionally, the self-assembled monolayer hole transport material comprises at least one of the following compounds: .

[0013] According to a second aspect of the present invention, the present invention also provides a method for preparing the self-assembled monolayer hole transport material according to any one of the above claims, comprising the following steps: The compound shown in formula a is mixed with the compound shown in formula b to undergo a coupling reaction to generate the compound shown in formula 3, wherein the molar ratio of the compound shown in formula a to the compound shown in formula b is any value of (1-4):1. The compound shown in formula c is mixed with triphenylphosphine to undergo a cyclization reaction to generate the compound shown in formula d, wherein the molar ratio of the compound shown in formula c to triphenylphosphine is any value in the range of 1:(10-20). The compound shown in formula d is mixed with the compound shown in formula e to undergo a substitution reaction to generate the compound shown in formula f, wherein the molar ratio of the compound shown in formula d to the compound shown in formula e is any value in the range of 1:(1-4). The compound shown in formula f is mixed with bromotrimethylsilane and subjected to a hydrolysis reaction to generate the self-assembled monolayer hole transport material, wherein the molar ratio of the compound shown in formula f to bromotrimethylsilane is any value between 1:(10-20); wherein the general structural formula of the compound shown in formula f is: Wherein, R is selected from alkylene groups; R2, R3, R4, and R5 are each independently selected from H, methyl, methoxy, and thiooxy, and at least one of R2, R3, R4, and R5 is a first group, wherein the first group is at least one of alkyl, alkoxy, and aldehyde groups. R6, R7, R8, R9, R 10 R 11 R 12 R 13 Each is selected independently from H.

[0014] Optionally, the step of mixing the compound shown in formula a with the compound shown in formula b to undergo a coupling reaction further includes: The compounds shown in formula a and formula b were dissolved in a mixed solvent of toluene and water, followed by the addition of potassium phosphate and tetra(triphenylphosphine)palladium. The mixture was heated to 80°C-120°C under a nitrogen atmosphere and reacted for 24-72 h to obtain the compound shown in formula c.

[0015] Optionally, the step of mixing the compound shown in formula c with triphenylphosphine to undergo a cyclization reaction further includes: The compound shown in formula c was mixed with triphenylphosphine in 1,2-dichlorobenzene, and a ring-closure reaction was carried out under a nitrogen atmosphere. The reaction was carried out at 140℃-200℃ for 24h-72h. After the reaction was completed, the compound shown in formula d was obtained by separation and purification.

[0016] Optionally, the step of mixing the compound shown in formula d with the compound shown in formula e to undergo a substitution reaction further includes: The compound shown in formula d was dissolved in N,N-dimethylformamide, and then the compound shown in formula e and sodium hydride were added. The reaction was carried out at 0℃-120℃ for 24h-72h to obtain the compound shown in formula f.

[0017] Optionally, the step of mixing the compound of formula f with bromotrimethylsilane to undergo a hydrolysis reaction further includes: The compound shown in formula f was mixed with bromotrimethylsilane in dichloromethane and hydrolyzed at 0℃-120℃ for 6h-24h. After the reaction was completed, methanol and water were added to quench the reaction, and the self-assembled monolayer hole transport material was obtained by filtration.

[0018] According to a third aspect of the present invention, the present invention also provides a perovskite solar cell, the perovskite solar cell comprising a hole transport layer, the hole transport layer comprising the self-assembled monolayer hole transport material described in any one of the preceding claims.

[0019] Optionally, the cell is a single-junction perovskite solar cell, a perovskite / crystalline silicon heterojunction tandem solar cell, or a perovskite / crystalline silicon TOPCon tandem solar cell.

[0020] The self-assembled monolayer hole transport material of this invention introduces a pyrene-indole fused heterocyclic structure as the core functional group. Compared with existing traditional aromatic conjugated frameworks such as carbazole and triphenylamine, this structure has a larger π-conjugated area and stronger rigid planar characteristics. The larger π-conjugated system makes the HOMO energy level tuning window of the material wider, which can more flexibly adapt to the energy level requirements of the wide-bandgap perovskite absorber layer for hole selective contact, reducing hole accumulation and open-circuit voltage loss caused by interfacial energy level mismatch. The stronger rigid structural characteristics endow the molecules with a more stable stacking mode, enhance the intermolecular interaction, thereby improving the self-assembly order, compactness and coverage integrity of the monolayer on the surface of a transparent conductive substrate, effectively eliminating local pinholes or defect regions. Meanwhile, the pyrene-indole structure enhances the interfacial interaction between the molecule and the transparent conductive substrate and perovskite layer, improves the charge transport and defect passivation effect at the buried interface, and reduces non-radiative recombination loss. Under continuous thermal stress and illumination, it maintains the stability of molecular configuration and interfacial adsorption state, avoiding weakening of interfacial passivation and decrease in carrier selectivity, thereby significantly improving the photoelectric conversion efficiency and long-term operational stability of perovskite solar cells.

[0021] Furthermore, in this invention, R is selected from C1-C6 alkylene groups, R1, R2 14 and R 15 All are phosphonic acid groups, R2, R3, R4, R5, R 16 R 17 R 18 R 19 R 20 R 21 R 22 and R 23 Each group is independently selected from H, methyl, methoxy, or C1-C6 alkylthio groups. By limiting the carbon chain length of the linking group and the specific type of anchoring group, the anchoring adsorption capacity and film uniformity of the molecule on the substrate surface are optimized. Furthermore, by limiting the specific types of substituents, the energy level positions of the core framework and the strength of interfacial interactions are further fine-tuned.

[0022] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, the preferred embodiments of the present invention are described in detail below with reference to the accompanying drawings. Attached Figure Description

[0023] The following sections will describe some specific embodiments of the invention in detail by way of example and not limitation, with reference to the accompanying drawings. The same reference numerals in the drawings denote the same or similar parts or portions. Those skilled in the art should understand that these drawings are not necessarily drawn to scale. In the drawings: Figure 1 This is a schematic flowchart of a method for preparing a self-assembled monolayer hole transport material according to an embodiment of the present invention; Figure 2 This is the 1H NMR spectrum of the self-assembled monolayer hole transport material according to Example 1 of the present invention; Figure 3 This is a schematic structural diagram of a single-junction perovskite solar cell according to Embodiment 2 of the present invention; Figure 4 This is a JV curve diagram of a single-junction perovskite solar cell according to Embodiment 2 of the present invention; Figure 5 This is a schematic structural diagram of a perovskite-crystalline silicon tandem solar cell according to Embodiment 3 of the present invention; Figure 6 This is a JV curve diagram of a perovskite-crystalline silicon tandem solar cell according to Embodiment 3 of the present invention; Figure 7 This is a schematic structural diagram of a perovskite / TOPCon tandem solar cell according to Embodiment 4 of the present invention; Figure 8This is a JV curve diagram of the perovskite / TOPCon tandem solar cell according to Embodiment 4 of the present invention.

[0024] Figure label: 200 - Single-junction perovskite solar cell; 201 - Conductive substrate; 202 - Hole transport layer; 203 - Perovskite light-absorbing layer; 204 - Electron transport layer; 205 - Buffer layer; 206 - Silver electrode; 300 - Perovskite-crystalline silicon tandem solar cell; 301 - n-type silicon substrate; 302 - Passivation layer; 303 - Back hole transport layer; 304 - Back transparent electrode; 305 - Back silver electrode; 306 - Front electron transport layer; 307 - ITO composite layer; 308 - Self-assembled molecular layer; 309 - Perovskite light-absorbing layer; 310 - Electron transport layer; 311 - Buffer layer; 312 - Front... 313 - Front transparent electrode, 314 - Antireflection layer, 400 - Perovskite / TOPCon tandem solar cell, 401 - n-type silicon substrate, 402 - Boron emitter layer, 403 - SiOx layer, 404 - Polycrystalline silicon layer, 405 - Passivation layer, 406 - Antireflection layer, 407 - Back silver electrode, 408 - IZO composite layer, 409 - NiOx hole transport layer, 410 - Self-assembled molecular layer, 411 - Perovskite light-absorbing layer, 412 - Electron transport layer, 413 - Buffer layer, 414 - Front transparent electrode, 415 - Antireflection layer, 416 - Front silver electrode. Detailed Implementation

[0025] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples. The following examples are for illustrative purposes only and are not intended to limit the scope of the invention.

[0026] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, the specific embodiments of this application will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of this application. Furthermore, it should be noted that, for ease of description, only the parts relevant to this application are shown in the accompanying drawings, not the entire structure. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without inventive effort are within the scope of protection of this application.

[0027] The terms “comprising” and “having”, and any variations thereof, used in this application are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or apparatus that includes a series of steps or units is not limited to the steps or units listed, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to such process, method, product, or apparatus.

[0028] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0029] This invention provides a self-assembled monolayer hole transport material comprising at least one chemical structure of formula (I) or formula (II): or In formula (I), R is selected from alkylene groups; R1 is selected from at least one of phosphonic acid group, boric acid group, carboxylic acid group or sulfonic acid group; R2, R3, R4, and R5 are each independently selected from H, alkyl, alkoxy, or thiooxy groups; R6, R7, R8, R9, R 10 R 11 R 12 R 13 Each is independently selected from H; In formula (II), R is selected from alkylene groups; R 14 R 15 Selected from at least one of phosphonic acid group, carboxylic acid group or sulfonic acid group; R 16 R 17 R 18 R 19 R 20 R 21 R 22 R 23 Each is independently selected from H, alkyl, alkoxy, or thiooxy; R 24 R 25 R 26 R 27 R 28 R 29 Each is independently selected from H.

[0030] The self-assembled monolayer hole transport material in this embodiment introduces a pyrene-indole fused heterocyclic structure as the core functional group. Compared to existing traditional aromatic conjugated frameworks such as carbazole and triphenylamine, this structure has a larger π-conjugated area and stronger rigid planar characteristics. The larger π-conjugated system makes the material's HOMO energy level tuning window wider, which can more flexibly adapt to the energy level requirements of the wide-bandgap perovskite absorber layer for hole selective contact, reducing hole accumulation and open-circuit voltage loss caused by interfacial energy level mismatch. The stronger rigid structural characteristics give the molecules a more stable stacking mode, enhance intermolecular interactions, and thus improve the self-assembly order, density, and coverage integrity of the monolayer on the transparent conductive substrate surface, effectively eliminating local pinholes or defect regions. Meanwhile, the pyrene-indole structure enhances the interfacial interaction between the molecule and the transparent conductive substrate and perovskite layer, improves the charge transport and defect passivation effect at the buried interface, and reduces non-radiative recombination loss. Under continuous thermal stress and illumination, it maintains the stability of molecular configuration and interfacial adsorption state, avoiding weakening of interfacial passivation and decrease in carrier selectivity, thereby significantly improving the photoelectric conversion efficiency and long-term operational stability of perovskite solar cells.

[0031] In a further embodiment, R is selected from C1-C6 alkylene groups, R1, R 14 and R 15 All are phosphonic acid groups, R2, R3, R4, R5, R 16 R 17 R 18 R 19 R 20 R 21 R 22 and R 23 Each group is independently selected from H, methyl, methoxy, or C1-C6 alkylthio groups. In this embodiment, by limiting the carbon chain length of the linking group and the specific type of anchoring group, the anchoring adsorption capacity of the molecule on the substrate surface and the film formation uniformity are optimized. Simultaneously, by limiting the specific types of substituents, the energy level positions of the core framework and the interfacial interaction strength are further fine-tuned.

[0032] In a further embodiment, the self-assembled monolayer hole transport material includes at least one of the following compounds (1)-(11). By providing the specific compound structures described below, the self-assembled monolayer hole transport material is ensured to have optimal hole selective extraction, interface defect passivation and long-term operational stability in perovskite solar cells.

[0033] .

[0034] Figure 1 This is a schematic flowchart of a method for preparing a self-assembled monolayer hole transport material according to an embodiment of the present invention.

[0035] like Figure 1 As shown, the present invention also provides a method for preparing a self-assembled monolayer hole transport material according to any one of the above claims, comprising the following steps: Step S100: The compound shown in Formula a is mixed with the compound shown in Formula b to undergo a coupling reaction to generate the compound shown in Formula 3. The molar ratio of the compound shown in Formula a to the compound shown in Formula b is any value in (1-4):1. Step S200: The compound shown in formula c is mixed with triphenylphosphine to undergo a cyclization reaction to generate the compound shown in formula d. The molar ratio of the compound shown in formula c to triphenylphosphine is any value in the range of 1:(10-20). Step S300: Mix the compound shown in formula d with the compound shown in formula e to undergo a substitution reaction to generate the compound shown in formula f. The molar ratio of the compound shown in formula d to the compound shown in formula e is any value in (1-4). Step S400: The compound shown in formula f is mixed with bromotrimethylsilane and subjected to a hydrolysis reaction to generate a self-assembled monolayer hole transport material. The molar ratio of the compound shown in formula f to bromotrimethylsilane is any value in the range of 1:(10-20). The general structural formula of the compound shown in formula f is: Wherein, R is selected from alkylene groups; R2, R3, R4, and R5 are each independently selected from H, methyl, methoxy, and thiooxy, and at least one of R2, R3, R4, and R5 is a first group, wherein the first group is at least one of alkyl, alkoxy, and aldehyde groups. R6, R7, R8, R9, R 10 R 11 R 12 R 13 Each is selected independently from H.

[0036] In this embodiment, the preparation method of the self-assembled monolayer hole transport material includes coupling reaction, cyclization reaction, substitution reaction, and hydrolysis reaction. Specifically, an intermediate containing nitroaryl and pyrene segments is first constructed through a coupling reaction. Then, a pyrene-indole fused heterocyclic core is formed through a cyclization reaction. Next, a phosphonate-containing linking chain is introduced onto the nitrogen atom through a substitution reaction. Finally, the phosphonate is converted into phosphonic acid groups through a hydrolysis reaction to obtain a self-assembled monolayer hole transport material with the ability to anchor on a transparent conductive substrate.

[0037] In this embodiment, the step-by-step design of first constructing a fused conjugated framework, then introducing an anchoring group precursor, and finally hydrolyzing to generate the anchoring group avoids the problems of premature introduction of phosphonic acid groups, which could lead to excessively polar intermediates, decreased solubility, or interference with coupling / cyclization reactions. Simultaneously, the phosphonate intermediate exhibits good reactivity compatibility in organic solvents, facilitating its separation and purification. The final hydrolysis to generate the phosphonic acid group gives the product both a large π-conjugated pyrene-indole framework and substrate anchoring capability, thereby improving the controllability of the target SAM material synthesis, structural consistency, and subsequent self-assembly effect on a transparent conductive substrate.

[0038] In a further embodiment, the step of mixing the compound shown in formula a with the compound shown in formula b to undergo a coupling reaction further includes: The compounds shown in formula a and formula b were dissolved in a mixed solvent of toluene and water, followed by the addition of potassium phosphate and tetra(triphenylphosphine)palladium. The mixture was heated to 80°C-120°C under a nitrogen atmosphere and reacted for 24-72 h to obtain the compound shown in formula c.

[0039] In this embodiment, by using a mixed solvent of toluene and water, the reaction environment of both the organic aromatic substrate and the inorganic base can be simultaneously considered, allowing the compound with the boric acid structure shown in Formula a to fully contact and undergo a coupling reaction with the compound with the bromine aromatic structure shown in Formula b. The addition of potassium phosphate provides a suitable weakly basic environment for the coupling reaction, promoting the participation of the boric acid substrate in the transmetalation process; the addition of tetrakis(triphenylphosphine)palladium catalyzes the coupling between the aryl halide and the arylboronic acid, thereby stabilizing the carbon-carbon bond between the pyrene fragment and the substituted nitroaryl fragment. Here, the heating temperature in a nitrogen atmosphere can be 80°C, 90°C, 100°C, 110°C, or 120°C, or any other value within the range of 80°C-120°C; the reaction time can be 24h, 36h, 48h, 60h, or 72h, or any other value within the range of 24h-72h, yielding the compound shown in Formula c.

[0040] In this embodiment, by controlling the reaction temperature at 80℃-120℃, the reaction time at 24h-72h, and conducting the reaction under a nitrogen atmosphere, the risk of palladium catalyst deactivation, aryl halide dehalogenation, or side reactions can be reduced while ensuring the coupling reaction proceeds fully. The compound of formula c obtained in this step provides the necessary precursor structure for the subsequent cyclization formation of the pyrene-indole fused framework, thus improving the accuracy of the core framework construction and the reaction yield of the target SAM material.

[0041] In a further embodiment, the step of mixing the compound shown in formula c with triphenylphosphine to undergo a cyclization reaction further includes: The compound shown in formula c was mixed with triphenylphosphine in 1,2-dichlorobenzene, and a ring-closure reaction was carried out under a nitrogen atmosphere. The reaction was carried out at 140℃-200℃ for 24h-72h. After the reaction was completed, the compound shown in formula d was obtained by separation and purification.

[0042] In this embodiment, by using triphenylphosphine as a reducing agent, the nitro group in the compound shown in formula c can participate in the reductive ring-closure process, thereby forming a nitrogen-containing fused heterocyclic structure between the pyrene and aryl segments, resulting in a pyrene-indole core skeleton. This ring-closure step is an important structural construction step that distinguishes this application from traditional carbazole and triphenylamine-based SAM materials, enabling the product to obtain a larger π-conjugated area and stronger rigid planar features. Here, the reaction temperature can be 140℃, 160℃, 180℃, or 200℃, or any other value between 140℃ and 200℃, and the reaction time can be 24h, 36h, 48h, 60h, or 72h, or any other value between 24h and 72h.

[0043] In this embodiment, using 1,2-dichlorobenzene as the reaction solvent allows for adaptation to the requirements of ring-closing reactions at higher temperatures, improving the efficiency of fused ring formation. Furthermore, conducting the reaction under a nitrogen atmosphere reduces intermediate oxidation and side reactions under high-temperature conditions. Additionally, controlling the temperature at 140℃-200℃ and reacting for 24h-72h improves the sufficiency of the ring-closing reaction and reduces the residue of unclosed intermediates. The compound of formula d obtained in this step possesses a stable pyrene-indole fused core, which is beneficial for the subsequent formation of SAM molecules with stable stacking structures and good hole transport capabilities.

[0044] In a further embodiment, the step of mixing the compound shown in formula d with the compound shown in formula e to undergo a substitution reaction further includes: The compound shown in formula d was dissolved in N,N-dimethylformamide, and then the compound shown in formula e and sodium hydride were added. The reaction was carried out at 0℃-120℃ for 24h-72h to obtain the compound shown in formula f.

[0045] In this embodiment, sodium hydride is used as a strong base to activate the nitrogen atom in the pyrene-indole intermediate shown in formula d, thereby enabling a substitution reaction with the compound containing a haloalkyl phosphonate structure shown in formula e, introducing an alkylene linker chain containing phosphonate end groups onto the pyrene-indole core. This step connects the fused conjugated core for hole transport and the phosphonic acid group precursor for substrate anchoring into the same molecule, which is a key step in the formation of SAM functional molecules. Here, the reaction temperature is 0℃, 20℃, 50℃, 100℃, or 120℃, or any other value within the range of 0℃-120℃, and the reaction time is 24h, 36h, 48h, 60h, or 72h, or any other value within the range of 24h-72h.

[0046] In this embodiment, using N,N-dimethylformamide as a polar aprotic solvent improves the dispersion and reaction efficiency of the intermediate shown in formula d, the halophosphonate shown in formula e, and the base, thus facilitating the smooth progress of the substitution reaction. By controlling the temperature at 0℃-120℃ and the time at 24h-72h, both reactivity and structural stability can be balanced, avoiding side reactions at the phosphonate end groups or degradation of the fused skeleton due to excessively high temperatures. The compound shown in formula f obtained in this step retains the phosphonate protected form, facilitating subsequent purification and providing a precursor for the final generation of the phosphonic acid anchoring group. In a further embodiment, the step of mixing the compound of formula f with bromotrimethylsilane to undergo a hydrolysis reaction further includes: The compound shown in formula f was mixed with bromotrimethylsilane in dichloromethane and hydrolyzed at 0℃-120℃ for 6h-24h. After the reaction was completed, methanol and water were added to quench the reaction, and the mixture was filtered to obtain a self-assembled monolayer hole transport material.

[0047] In this embodiment, by treating the phosphonate intermediate shown in formula f with trimethylbromosilane, the phosphonate end group can be converted into a phosphonic acid group, enabling the target molecule to acquire the anchoring ability to bind to a transparent conductive oxide substrate. Compared to directly introducing free phosphonic acid groups in the preceding steps, the method of first participating in the substitution reaction in the form of a phosphonate and then converting it into a phosphonic acid group can improve the organic solvent solubility and reaction operability of the intermediate, and enhance the stability of the synthetic route. Here, the reaction temperature can be 0℃, 20℃, 50℃, 100℃, or 120℃, or any other value within the range of 0℃-120℃, and the reaction time can be 6h, 12h, 18h, or 24h, or any other value within the range of 24h-72h.

[0048] In this embodiment, by using dichloromethane as the reaction solvent and controlling the reaction temperature between 0℃ and 120℃ and the reaction time between 6h and 24h, the risk of damage to the pyrene-indole fused conjugated backbone can be reduced while ensuring the full conversion of phosphonate. Quenching with methanol and water after the reaction promotes the further conversion of the silicon-based intermediate into a phosphonic acid structure and removes residual reaction reagents. The final molecule possesses both a pyrene-indole hole transport core and phosphonic acid anchoring end groups, enabling the formation of a stable SAM layer on the surface of transparent conductive oxides such as ITO, FTO, or IZO.

[0049] This invention also provides a perovskite solar cell, comprising a hole transport layer containing the aforementioned self-assembled monolayer hole transport material. By placing the self-assembled monolayer hole transport material between a transparent conductive substrate and a perovskite light-absorbing layer, the anchoring stability of SAM molecules on the surface of the transparent conductive substrate can be improved using phosphonic acid groups, and the interface energy level and hole selective extraction capability can be adjusted using pyrene-indole fused cores. Due to the extremely thin thickness of the SAM layer, parasitic absorption and bulk transport losses can be reduced; simultaneously, its good coverage integrity can reduce the defect density at the buried interface and reduce non-radiative recombination, thereby improving the open-circuit voltage, fill factor, and photoelectric conversion efficiency of the perovskite solar cell.

[0050] In a further embodiment, the cell is a single-junction perovskite solar cell, a perovskite / crystalline silicon heterojunction tandem solar cell, or a perovskite / crystalline silicon TOPCon tandem solar cell.

[0051] In some embodiments, when the cell is a perovskite / crystalline silicon TOPCon tandem solar cell, the aforementioned SAM material can also serve as a hole transport layer for the perovskite top cell, working in conjunction with the transparent conductive composite layer on the TOPCon bottom cell to improve the film quality and energy level matching relationship at the buried interface of the perovskite top cell. Therefore, this material is applicable not only to single-junction cells but also to tandem devices with different crystalline silicon bottom cell structures, demonstrating the versatility and scalability of its interface material applications.

[0052] In some embodiments, when the cell is a single-junction perovskite solar cell, the above-mentioned SAM material can serve as a hole-selective contact layer between the transparent conductive substrate and the wide-bandgap perovskite light-absorbing layer, thereby improving the energy level matching and hole extraction efficiency of the buried interface and thus enhancing the photoelectric conversion efficiency of the single-junction device.

[0053] In some embodiments, when the cell is a perovskite / crystalline silicon heterojunction tandem solar cell, the aforementioned SAM material can be disposed between the crystalline silicon bottom cell composite layer or the transparent conductive composite layer and the perovskite top cell, serving as a hole transport layer for the perovskite top cell. Since tandem solar cells are more sensitive to interface parasitic absorption and series resistance, the ultrathin film characteristics and strong interface control capabilities of the SAM material are beneficial for reducing optical losses and interface recombination, improving current matching between the top and bottom cells, and enhancing overall output performance.

[0054] Figure 2 This is the 1H NMR spectrum of the self-assembled monolayer hole transport material according to Example 1 of the present invention. Figure 3 This is a schematic structural diagram of a single-junction perovskite solar cell according to Embodiment 2 of the present invention. Figure 4 This is a JV curve diagram of a single-junction perovskite solar cell according to Embodiment 2 of the present invention. Figure 5This is a schematic structural diagram of a perovskite-crystalline silicon tandem solar cell according to Embodiment 3 of the present invention. Figure 6 This is a JV curve diagram of the perovskite-crystalline silicon tandem solar cell according to Embodiment 3 of the present invention. Figure 7 This is a schematic structural diagram of a perovskite / TOPCon tandem solar cell according to Embodiment 4 of the present invention. Figure 8 This is a JV curve diagram of the perovskite / TOPCon tandem solar cell according to Embodiment 4 of the present invention.

[0055] The technical solutions involved in this application will be further described below with reference to specific embodiments.

[0056] Example 1

[0057] The preparation method of self-assembled monomolecular hole transport layer material Y4A includes the following steps: Step S100: Add a (1.66 g, 10 mmol), 2 (1.64 g, 7.5 mmol), tetrakis(triphenylphosphine)palladium (0.886 g, 0.75 mmol), potassium phosphate (7.95 g, 37.5 mmol), toluene (150 mL), and water (40 mL) sequentially to a 250 mL two-necked flask. The reaction mixture was stirred at 100 °C for 24 h under a nitrogen atmosphere. After the reaction solution cooled to room temperature, it was washed with water and extracted with dichloromethane. This process was repeated three times. The solution was dried over anhydrous magnesium sulfate and filtered. The solvent was removed by rotary evaporation to obtain the crude product. The crude product was separated by column chromatography using petroleum ether / dichloromethane as the eluent to obtain a yellow solid c, with a yield of 79%.

[0058] Step S200: Add c (1.62 g, 5 mmol) and triphenylphosphine (13.1 g, 50 mmol) dissolved in 1,2-dichlorobenzene solution (150 mL) to a 250 mL two-necked flask. Stir the reaction mixture at 160 °C for 48 h. After the reaction solution cools to room temperature, wash with water and extract with dichloromethane. Repeat three times, dry with anhydrous magnesium sulfate, filter, and remove the solvent using a rotary evaporator to obtain the crude product. Separate the crude product by column chromatography using petroleum ether / dichloromethane / methanol as eluent to obtain a yellow solid d, with a yield of 81%.

[0059] Step S300: Add d (0.879 g, 3 mmol) and diethyl(3-bromopropyl)phosphonate (1.94 g, 7.5 mmol) dissolved in DMF solution (50 mL) sequentially to a 250 mL two-necked flask. Then add sodium hydride (0.24 g, 10 mmol), and stir the reaction mixture at room temperature for 24 h. After the reaction solution cools to room temperature, wash with water and extract with dichloromethane, repeating this process three times. Dry the mixture with anhydrous magnesium sulfate and filter. Remove the solvent using a rotary evaporator to obtain the crude product. Separate the crude product using a chromatographic column with petroleum ether / dichloromethane as the eluent to obtain a yellow solid e, with a yield of 74%.

[0060] Step S400: Add e (1.17 g, 2.5 mmol) sequentially to a 250 mL two-necked flask. Dissolve trimethylbromosilane (TMSBr) (4.59 g, 30 mmol) in dichloromethane solution (50 mL). Stir the reaction mixture at room temperature for 6 h. Then add methanol (30 mL) to the flask. Filter the reaction mixture and wash with water. Dissolve the filter cake again in tetrahydrofuran, precipitate it in petroleum ether, and filter. Repeat this process three times to obtain green solid Y4A with a yield of 69%.

[0061] Here, the specific synthesis path of Example 1 is as follows: .

[0062] Example 2

[0063] Example 2 provides a self-assembled monomolecular hole transport layer material Y4A as a single-junction perovskite solar cell 200 (refer to). Figure 3 The structure of the hole transport layer and its preparation method are as follows: The patterned ITO conductive glass was ultrasonically cleaned sequentially with acetone, isopropanol and ethanol, and then dried with nitrogen to obtain conductive substrate 201. A self-assembled monomolecular hole transport layer was prepared by spin coating. The material was the molecule Y4A from Example 1, which served as the hole transport layer 202 of the wide-bandgap perovskite solar cell. Wide-bandgap Cs were prepared by spin coating. 0.05 MA 0.15 FA 0.8 PbI 2.25 Br 0.75 The perovskite light-absorbing layer 203 has a band gap of approximately 1.68 eV; A C60 electron transport layer 204 with a thickness of 20 nm was deposited on the perovskite light-absorbing layer 203 by high-temperature thermal evaporation. A SnO2 buffer layer 205 with a thickness of 15 nm was deposited on the C60 electron transport layer 204 using atomic layer deposition. A silver electrode 206 was prepared on a SnO2 buffer layer 205 by high-temperature thermal evaporation, and a single-cell perovskite solar cell 200 was obtained.

[0064] Example 3

[0065] Example 3 provides a perovskite-crystalline silicon tandem solar cell 300 having the self-assembled single-molecule hole transport layer material Y4A (see reference). Figure 5 The structure and preparation method of the perovskite-crystalline silicon tandem solar cell are described below. Specifically, a thin film of the hole transport layer material described in Example 1 is prepared by spin-coating onto the composite layer, and a wide-bandgap perovskite top cell is then stacked on top. A grid-like silver electrode is used on the back of the cell. The preparation method of the perovskite-crystalline silicon tandem solar cell 300 is as follows: n-type single crystal silicon was selected, and the damaged layer of the silicon wafer was removed by polishing and etching with 10wt%-NaOH aqueous solution. Then, a pyramid textured surface and single-sided alkaline polishing process were prepared using 2wt%-NaOH solution. Finally, the silicon wafer was cleaned by RCA method to obtain n-type silicon substrate 301. A PECVD process was used to deposit a-Si:H(i) passivation layers 302 with a thickness of 5 nm on the front and back sides of an n-type silicon substrate 301, respectively, at a deposition temperature of 400 °C. A boron-doped nc-Si:H(p) layer 303 with a thickness of 25 nm was deposited on the back side using PECVD process at a deposition temperature of 170 °C, forming a full-area hole transport layer on the back side. A phosphorus-doped nc-SiOx:H(n) layer 306 with a thickness of 40 nm was deposited on the front side using PECVD process at a deposition temperature of 170℃, forming a full-area electron transport layer. An ITO transparent electrode 304 with a thickness of 110 nm was deposited on the back side by magnetron sputtering. Silver electrodes 305 are printed on the back using a low-temperature silver paste screen printing process, and then dried in air at 400°C to form the final product. An ITO composite layer 307 with a thickness of 15 nm was deposited on the front phosphorus-doped nc-SiOx:H(n) layer 306 by magnetron sputtering to form the composite layer; Using the material Y4A from Example 1, a self-assembled molecular layer 308 was prepared on the ITO composite layer 307 by spin coating as a hole transport layer for the top battery. Wide-bandgap Cs were prepared by spin coating. 0.05 MA 0.15 FA 0.8 PbI 2.25 Br 0.75 The perovskite light-absorbing layer 309 has a band gap of approximately 1.68 eV; A C60 electron transport layer 310 with a thickness of 10 nm was deposited on the perovskite light-absorbing layer by high-temperature thermal evaporation. A SnO2 buffer layer 311 was deposited on the C60 electron transport layer by atomic layer deposition at a deposition temperature of 100℃ and a thickness of 15nm. Indium-doped IZO transparent electrode 312 with a thickness of 45 nm was deposited on SnO2 buffer layer by magnetron sputtering. A silver electrode 313 with a thickness of 500 nm was prepared on an IZO transparent electrode 312 by high-temperature thermal evaporation. A perovskite / crystalline silicon tandem solar cell 300 with a hole transport layer structure was prepared by depositing magnesium fluoride antireflection 314 with a thickness of 120 nm on an IZO transparent electrode 312 using high-temperature thermal evaporation.

[0066] Example 4

[0067] Example 4 provides a self-assembled monomolecular hole transport layer material Y4A as a perovskite / TOPCon tandem solar cell 400 (refer to). Figure 7 The structure and preparation method of the hole transport layer are described below. Specifically, the hole transport layer material film described in Example 1 is spin-coated onto the intermediate composite layer. The bottom cell uses a TOPCon cell structure, and a wide-bandgap perovskite top cell is stacked on top. A grid-like silver electrode is used on the back of the cell. The specific preparation method of the perovskite / TOPCon tandem solar cell 400 is as follows: n-type monocrystalline silicon was selected, and the damaged layer of the silicon wafer was removed by polishing and etching with 10wt%-KOH aqueous solution. Then, a pyramid textured surface and a single-sided alkaline polishing process were prepared using 2wt%-KOH solution. Finally, the silicon wafer was cleaned using the RCA method to obtain n-type silicon substrate 401. In a boron diffusion furnace, a boron emitter c-Si:B(p+) layer 402 with a thickness of 150 nm is formed using a BBr3 source; The diffusion layer on the front side was removed using an industrial HF / HNO3 etching process, and a thin SiOX403 layer with a thickness of 1.5 nm was deposited on the front side. Intrinsic polysilicon was deposited at 550°C by low-pressure chemical vapor deposition, and then the intrinsic polysilicon was doped in a POCl3 diffusion furnace to form a polysilicon Poly-Si:(n+) layer 404 with a thickness of 100nm. The polysilicon poly-Si:(n+) layer 404 surrounding the back side was removed using a single-sided KOH etching process. The borosilicate glass (BSG) layer on the front side and the phosphorosilicate glass (PSG) layer on the back side were removed using HF. The surface was then cleaned in RCA cleaning agent and deionized water. An Al2O3 passivation layer 405 with a thickness of 3 nm was formed by atomic layer deposition (ALD) to passivate the textured surface. A SiNx antireflection layer 406 with a thickness of 80 nm was prepared on the Al2O3 passivation layer 405 of the battery by plasma-enhanced chemical vapor deposition (PECVD). A silver electrode 407 was fabricated on the back side using a screen printing machine. The electrode contacts the c-Si:B(p+) layer 402 with a thickness of 1 μm. A layer of indium zinc oxide (IZO) was sputtered on the poly-Si:(n+) layer 404 on the front side as a composite layer 408 with a thickness of 15 nm using magnetron sputtering. A NiOx hole transport layer 409 with a thickness of 10 nm was sputtered onto the IZO composite layer by magnetron sputtering. Using the self-assembled monomolecular hole transport material Y4A from Example 1, a hole transport layer 410 was prepared on the NiOx hole transport layer 409 by spin coating. Wide-bandgap Cs were prepared by spin coating. 0.05 MA 0.15 FA 0.8 PbI 2.25 Br 0.75 The perovskite light-absorbing layer 411 has a band gap of approximately 1.68 eV; A C60 electron transport layer 412 with a thickness of 10 nm was deposited on perovskite by high-temperature thermal evaporation. A SnO2 buffer layer 413 was deposited on the C60 electron transport layer 410 by atomic layer deposition at a deposition temperature of 100℃ and a thickness of 15nm. A zinc-doped IZO transparent electrode 414 with a thickness of 45 nm was deposited on a SnO2 buffer layer by magnetron sputtering. A silver grid line electrode 416 with a thickness of 500 nm was prepared on an IZO transparent electrode 414 by high-temperature thermal evaporation. A magnesium fluoride antireflection layer 415 with a thickness of 100 nm was deposited on an IZO transparent electrode 414 using high-temperature thermal evaporation. A perovskite / crystalline silicon TOPCon solar cell 400 with the hole transport layer structure described above was then fabricated.

[0068] First, the self-assembled monomolecular hole transport layer material Y4A from Example 1 was characterized by 1H NMR spectroscopy, yielding the following results: Figure 2 The test results are shown.

[0069] like Figure 2 As shown, 1H NMR (400 MHz, DMSO) δ 9.24 (d, J = 9.1 Hz, 1H), 8.94 (d,J = 8.0 Hz, 1H), 8.63 (s, 1H), 8.48 (d, J = 9.1 Hz, 1H), 8.38 (d, J = 7.6 Hz,1H), 8.29 (t, J = 8.0 Hz, 2H), 8.17 (d, J = 9.0 Hz, 1H), 8.04 (t, J = 7.6 Hz,1H), 7.94 (d, J = 8.2 Hz, 1H), 7.65 (t, J = 7.6 Hz, 1H), 7.47 (t, J = 7.5 Hz,1H), 4.81 (t, J = 7.1 Hz (2H), 2.22-2.08 (m, 2H), 1.72-1.58 (m, 2H). That is, the Y4A prepared in Example 1... 1 In the 1H NMR spectrum, multiple sets of aromatic hydrogen characteristic peaks appeared in the range of δ 9.24-7.47 ppm, indicating the presence of a pyrene-indole fused aromatic conjugated skeleton in the product. The triplet at δ 4.81 ppm corresponds to the methylene hydrogen bonded to the nitrogen atom, and the multiplets at δ 2.22-2.08 ppm and δ 1.72-1.58 ppm correspond to the methylene hydrogen in the phosphonic acid propyl linkage chain, indicating that the alkylene chain containing the phosphonic acid anchoring end group has been successfully introduced into the pyrene-indole core structure. Meanwhile, no obvious phosphonate ethoxy residual characteristic peaks were observed in the spectrum, indicating that the phosphonate group in the precursor has been converted into a phosphonic acid group after hydrolysis. The positions, splitting patterns, and integrated hydrogen numbers of the above NMR signals are basically consistent with the molecular structure of the target compound Y4A, proving that Example 1 successfully synthesized a self-assembled monolayer hole transport material Y4A with a pyrene-indole fused core and phosphonic acid anchoring groups.

[0070] Next, the performance of the single-junction perovskite solar cell 200 of Example 2 was characterized, and the results were as follows: Figure 4 The JV curves shown are illustrated in Figure 1, and the performance test results are shown in Table 1.

[0071] Table 1. Performance test results of the batteries prepared in Examples 2-3 like Figure 4 As shown in Table 1, the single-junction perovskite solar cell 200 prepared in Example 2 using Y4A as the self-assembled monomolecular hole transport layer material exhibits good photovoltaic output performance. According to the JV curve, the device has approximately 21.13 mA / cm² in the short-circuit state. 2The current density is approximately 1.25 V near the open-circuit state, and the curve exhibits good rectangularity, indicating smooth interface charge extraction and relatively low series resistance and interface recombination losses. The table data shows that the open-circuit voltage Voc of this device is 1.25 V, and the short-circuit current density Jsc is 21.13 mA / cm². 2 The fill factor (FF) was 83.38%, and the photoelectric conversion efficiency (PCE) was 22.12%. The higher Voc indicates that Y4A can improve the energy level matching between the ITO conductive substrate and the wide-bandgap perovskite light-absorbing layer, and reduce non-radiative recombination at the buried interface. The higher Jsc indicates that the self-assembled monolayer formed by Y4A is thin and has low parasitic absorption, which is beneficial for the generation and extraction of photogenerated carriers. The 83.38% FF indicates that Y4A has good hole-selective transport capability and interfacial contact performance. These results show that Y4A, as a hole transport layer in a single-junction wide-bandgap perovskite solar cell, can effectively improve the quality of the buried interface, promote hole extraction and transport, and reduce interfacial recombination losses, thereby enabling the device to achieve a photoelectric conversion efficiency of 22.12%.

[0072] The performance of the perovskite / crystalline silicon tandem solar cell 300 in Example 3 was characterized, and the results were as follows: Figure 6 The JV curves shown are illustrated in Figure 1, and the performance test results are shown in Table 1.

[0073] like Figure 6 As shown in Table 1, when Y4A prepared in Example 1 was used as a self-assembled monolayer hole transport material and applied to a perovskite / crystalline silicon tandem solar cell 300, the resulting device exhibited an open-circuit voltage Voc of 1.95V and a short-circuit current density Jsc of 20.61mA / cm². 2 The fill factor (FF) is 80.24%, and the photoelectric conversion efficiency (PCE) reaches 32.30%. The relatively high open-circuit voltage indicates that Y4A can improve the energy level matching relationship between the transparent conductive composite layer and the wide-bandgap perovskite light-absorbing layer, and reduce the non-radiative recombination loss at the buried interface; 20.61 mA / cm². 2 The short-circuit current density indicates that the self-assembled monolayer formed by Y4A is thin and has low parasitic absorption, which is beneficial for photogenerated carrier transport and current matching in the tandem solar cell. The fill factor of 80.24% indicates that the interface layer has good hole selective extraction capability and low interface transport impedance. The above results demonstrate that Y4A, as the hole transport layer of the perovskite top cell, can effectively improve the buried interface quality of the perovskite / crystalline silicon tandem solar cell 300, promote hole extraction and transport, reduce interface recombination loss, and thus enable the device to achieve a high photoelectric conversion efficiency of 32.30%.

[0074] The performance of the perovskite / crystalline silicon TOPCon solar cell 400 in Example 4 was characterized, and the results were as follows: Figure 8 The JV curves shown are illustrated in Figure 1, and the performance test results are shown in Table 1.

[0075] like Figure 8 As shown in Table 1, the JV curve of this device exhibits good rectangularity and can maintain approximately 20.24 mA / cm² under short-circuit conditions. 2 The current density output is high, and it drops rapidly near the open-circuit voltage, indicating that the internal series resistance of the device is low, and the interface charge extraction and transport are relatively smooth. The data in the table show that the open-circuit voltage Voc of Example 4 is 1.98V, and the short-circuit current density Jsc is 20.24mA / cm². 2 The fill factor (FF) is 81.24%, and the photoelectric conversion efficiency (PCE) reaches 32.55%. These results demonstrate that applying self-assembled single-molecule hole transport materials to the perovskite / TOPCon tandem solar cell 400 can effectively integrate with IZO composite layers and NiO. x The hole transport layer and the wide-bandgap perovskite light-absorbing layer form a good interfacial contact relationship, reducing non-radiative recombination and transmission losses at the buried interface, thereby enabling the device to obtain higher open-circuit voltage, fill factor and photoelectric conversion efficiency.

[0076] In summary, self-assembled single-molecule hole transport materials can achieve high device output performance in single-junction, crystalline silicon tandem, and TOPCon tandem solar cells by improving the energy level matching of the buried interface, reducing interfacial recombination loss, and optimizing the perovskite film quality, demonstrating their good interface control capability and cross-device structure applicability.

[0077] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0078] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A self-assembled monolayer hole transport material, characterized in that, Including at least one of the chemical structural formulas shown in formula (I) or formula (II): or In formula (I), R is selected from alkylene groups; R1 is selected from at least one of phosphonic acid group, boric acid group, carboxylic acid group or sulfonic acid group; R2, R3, R4, and R5 are each independently selected from H, alkyl, alkoxy, or thiooxy groups; R6, R7, R8, R9, R 10 R 11 R 12 R 13 Each is independently selected from H; In formula (II), R is selected from alkylene groups; R 14 R 15 Selected from at least one of phosphonic acid group, carboxylic acid group or sulfonic acid group; R 16 R 17 R 18 R 19 R 20 R 21 R 22 R 23 Each is independently selected from H, alkyl, alkoxy, or thiooxy; R 24 R 25 R 26 R 27 R 28 R 29 Each is independently selected from H.

2. The self-assembled monolayer hole transport material according to claim 1, characterized in that, R is selected from C1-C6 alkylene groups, and R1 and R2 are... 14 and R 15 All of them are phosphonic acid groups, namely R2, R3, R4, R5, and R 16 R 17 R 18 R 19 R 20 R 21 R 22 and R 23 Each is independently selected from H, methyl, methoxy, or C1-C6 alkylthio groups.

3. The self-assembled monolayer hole transport material according to claim 2, characterized in that, Includes at least one of the following compounds: 。 4. A method for preparing a self-assembled monolayer hole transport material according to any one of claims 1-3, characterized in that, Includes the following steps: The compound shown in formula a is mixed with the compound shown in formula b to undergo a coupling reaction to generate the compound shown in formula 3, wherein the molar ratio of the compound shown in formula a to the compound shown in formula b is any value of (1-4):

1. The compound shown in formula c is mixed with triphenylphosphine to undergo a cyclization reaction to generate the compound shown in formula d, wherein the molar ratio of the compound shown in formula c to triphenylphosphine is any value in the range of 1:(10-20). The compound shown in formula d is mixed with the compound shown in formula e to undergo a substitution reaction to generate the compound shown in formula f, wherein the molar ratio of the compound shown in formula d to the compound shown in formula e is any value in the range of 1:(1-4). The compound shown in formula f is mixed with bromotrimethylsilane and subjected to a hydrolysis reaction to generate the self-assembled monolayer hole transport material, wherein the molar ratio of the compound shown in formula f to bromotrimethylsilane is any value between 1:(10-20); wherein the general structural formula of the compound shown in formula f is: Wherein, R is selected from alkylene groups; R2, R3, R4, and R5 are each independently selected from H, methyl, methoxy, and thiooxy, and at least one of R2, R3, R4, and R5 is a first group, wherein the first group is at least one of alkyl, alkoxy, and aldehyde groups. R6, R7, R8, R9, R 10 R 11 R 12 R 13 Each is selected independently from H.

5. The method for preparing the self-assembled monolayer hole transport material according to claim 4, characterized in that, The step of mixing the compound shown in formula a with the compound shown in formula b to undergo a coupling reaction further includes: The compounds shown in formula a and formula b were dissolved in a mixed solvent of toluene and water, followed by the addition of potassium phosphate and tetra(triphenylphosphine)palladium. The mixture was heated to 80°C-120°C under a nitrogen atmosphere and reacted for 24-72 h to obtain the compound shown in formula c.

6. The method for preparing the self-assembled monolayer hole transport material according to claim 4, characterized in that, The step of mixing the compound shown in formula c with triphenylphosphine to undergo a cyclization reaction further includes: The compound shown in formula c was mixed with triphenylphosphine in 1,2-dichlorobenzene, and a ring-closure reaction was carried out under a nitrogen atmosphere. The reaction was carried out at 140℃-200℃ for 24h-72h. After the reaction was completed, the compound shown in formula d was obtained by separation and purification.

7. The method for preparing the self-assembled monolayer hole transport material according to claim 4, characterized in that: The step of mixing the compound shown in formula d with the compound shown in formula e to undergo a substitution reaction further includes: The compound shown in formula d was dissolved in N,N-dimethylformamide, and then the compound shown in formula e and sodium hydride were added. The reaction was carried out at 0℃-120℃ for 24h-72h to obtain the compound shown in formula f.

8. The method for preparing the self-assembled monolayer hole transport material according to claim 4, characterized in that: The step of mixing the compound shown in formula f with bromotrimethylsilane to undergo a hydrolysis reaction further includes: The compound shown in formula f was mixed with bromotrimethylsilane in dichloromethane and hydrolyzed at 0℃-120℃ for 6h-24h. After the reaction was completed, methanol and water were added to quench the reaction, and the self-assembled monolayer hole transport material was obtained by filtration.

9. A perovskite solar cell, characterized in that, The perovskite solar cell includes a hole transport layer, which comprises a self-assembled monolayer hole transport material as described in any one of claims 1-3.

10. The perovskite solar cell according to claim 9, characterized in that, The battery is a single-junction perovskite solar cell, a perovskite / crystalline silicon heterojunction tandem solar cell, or a perovskite / crystalline silicon TOPCon tandem solar cell.

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