Adaptive multi-bandgap pin perovskite cell hole transport layer, preparation method and application thereof

Abstract

The application discloses a kind of adaptation multi-band gap pin perovskite battery hole transport layer and preparation method and application thereof.The adaptation multi-band gap pin perovskite battery hole transport layer is prepared by the following method: (1) preparing self-assembled monolayer as a hole transport layer on a transparent conductive substrate; (2) the hole transport layer is treated at high temperature to reduce residual, remove weakly bonded molecules and oligomers remaining in the SAM self-assembly process; (3) coating a solution containing a specific small molecule on the hole transport layer treated at high temperature, and performing dynamic coating treatment; (4) the hole transport layer after coating is heat treated to form a SAM optimized modification layer with uniformization and vacancy passivation functions, and a SAM optimized modification type hole transport layer with layer insertion structure is obtained.The application has strong universality, can adapt to normal band gap, wide band gap pin structure perovskite devices and perovskite / silicon stacked solar cells, significantly improves the photoelectric conversion efficiency and long-term stability of the device, and the preparation process is easy to operate.

Description

Technical Field

[0001] This invention belongs to the field of perovskite solar cell technology, specifically relating to a hole transport layer adapted for multi-bandgap pin perovskite solar cells, its preparation method, and its application. Background Technology

[0002] Among third-generation photovoltaic cells, perovskite solar cells (PSCs) have become a research hotspot in the photovoltaic field due to their high photoelectric conversion efficiency, low cost, and solution processability. Among these, pin-structured perovskite devices, with their clear charge transport paths and strong process compatibility, have not only achieved breakthroughs in normal bandgap (1.55eV) single-junction devices, but also play a crucial role as the top-layer light-absorbing unit in wide bandgap (1.65-1.8eV) perovskite / silicon tandem solar cells (silicon-calcium tandem), providing core support for breaking through the efficiency limits of single-junction devices. Their universal application value has become a focus of industry attention.

[0003] Self-assembled monolayers (SAMs), as interface modification materials, have been widely used in pin-structured perovskite devices with different bandgap structures due to their ability to precisely control the interfacial energy level matching between the charge transport layer and the perovskite light-absorbing layer, improve wettability, and passivate interface defects. However, existing SAM modification processes suffer from significant common problems: on the one hand, SAM molecules tend to aggregate at the interface, leading to uneven distribution and failing to achieve full interface coverage; on the other hand, weak bond interactions remaining during SAM self-assembly (such as unbound molecules adsorbed by van der Waals forces and incompletely assembled oligomers) introduce additional interface defects and insufficient coverage, especially in wide-bandgap perovskite and silicon-calcium tandem devices, where these defects are more sensitive to non-radiative recombination, directly resulting in increased open-circuit voltage loss and decreased stability. More importantly, existing SAM optimization methods are mostly designed for specific bandgap or single device structures, lacking universality and failing to simultaneously meet the differentiated interface modification requirements of normal bandgap single-junction, wide-bandgap, and silicon-calcium tandem devices. Furthermore, some methods suffer from complex processes and high costs, limiting their large-scale application.

[0004] Therefore, there is an urgent need in this field to develop a universal, efficient, stable, and simple SAM interface optimization strategy that can solve the core problems of uneven SAM distribution, weak bond residue, and insufficient coverage in perovskite devices and silicon-calcium stacked devices with different band gaps (normal band gap, wide band gap) and achieve precise passivation of interface vacancies, thereby comprehensively improving the photoelectric conversion efficiency and long-term stability of various pin-structured perovskite devices. Summary of the Invention

[0005] In view of the problems existing in the prior art (uneven distribution of SAM in perovskite devices with different bandgap pin structures and silicon-calcium stacked devices, many defects caused by weak bond residues, poor universality of existing methods, and complex processes), this invention is proposed.

[0006] Therefore, the purpose of this invention is to overcome the shortcomings of the prior art and provide a method and application for preparing a hole transport layer for multi-bandgap pin perovskite solar cells. This method is universal, efficient, stable, and simple in process. It can solve the problems of uneven SAM distribution, weak bond residue, and insufficient coverage in pin-structure perovskite devices and silicon-calcium stacked devices with different bandgap (normal bandgap, wide bandgap). It can also achieve precise passivation of interface vacancies, so that the obtained SAM-optimized hole transport layer material can be used in various pin-structure perovskite devices to improve their photoelectric conversion efficiency and long-term stability.

[0007] To solve the above technical problems, the present invention provides the following technical solution: a hole transport layer adapted for multi-bandgap pin perovskite solar cells, the preparation method of which includes the following steps: (1) preparing a self-assembled monolayer as a hole transport layer on a transparent conductive substrate; (2) subjecting the hole transport layer to high-temperature heat treatment to reduce residue and remove weak bond molecules and oligomers remaining in the SAM self-assembly process; (3) coating the hole transport layer after high-temperature heat treatment with a solution containing specific small molecules and performing dynamic coating treatment; (4) subjecting the coated hole transport layer to heat treatment to form a SAM optimized modification layer with both homogenization and vacancy passivation functions, and obtaining a novel intercalation structure hole transport layer.

[0008] In step (1), the material for the self-assembled monolayer is selected from one or more of carbazole, aniline, and pyridine self-assembled molecules; the solvent for preparing the self-assembled monolayer is an alcohol solvent with a concentration of 0.3~1 mg / mL; in step (2), the high-temperature heat treatment is performed by one of hot table heating, laser heating, or hot air heating, with a heat treatment temperature of 120~130℃ and a heat treatment time of 10~15 min; in step (3), the dynamic coating process is spin coating, with a spin coating speed of 4000~5000 rpm and a spin coating time of 30 s, and when 25 s remain in the spin coating time, the coating is applied to a 2×2 cm⁻¹ layer. 2 Substrate titration with 30-40 μL of a solution containing specific small molecules; the heat treatment temperature in step (4) is 100℃ and the heat treatment time is 5-10 min.

[0009] The mass ratio of the specific small molecule to the hole transport layer is (0.2~0.8):1.

[0010] The solvent of the solution containing the specific small molecule in step (3) is selected from one or more of low polarity solvents and weak polarity solvents; the specific small molecule is an organic small molecule containing a π-π conjugated structure and having protonated amino groups, halide ions or other defect passivating groups.

[0011] The small molecule is 4-aminobenzoamide dihydrochloride (4-ABA2).

[0012] The concentration of the specific small molecule in the low-polarity solvent is 0.1~0.4 mg / mL.

[0013] This invention also provides the application of intercalation structure SAM-optimized modified hole transport layer materials in pin-structured perovskite devices or perovskite / silicon tandem solar cells.

[0014] The pin-structured perovskite device includes a transparent conductive substrate, a hole transport layer, a perovskite light-absorbing layer, an electron transport layer, and a metal electrode. The fabrication of the pin-structured perovskite device includes the following steps: (1) the interface of the SAM hole transport layer is optimized using the above method to obtain a modified hole transport layer; (2) a perovskite light-absorbing layer is fabricated on the modified hole transport layer; (3) an electron transport layer and a metal electrode are fabricated sequentially on the perovskite light-absorbing layer to obtain the pin-structured perovskite device.

[0015] The transparent conductive substrate is ITO glass or FTO glass; the electron transport layer is a C material with a thickness of 18~22nm. 60 And in C 60 A BCP blocking layer with a thickness of ~7 nm is deposited on the layer; the metal electrode is Cu or Ag with a thickness of 100~120 nm; the perovskite light-absorbing layer is prepared by a one-step spin coating method combined with antisolvent engineering, the antisolvent is diethyl ether, and the solvent of the perovskite precursor solution is a mixture of N,N-dimethylformamide (DMF) and dimethyl sulfoxide (DMSO) in a volume ratio of 4:1.

[0016] Compared with the prior art, the advantages of this invention are as follows: 1. The technical solution provided by this invention is applicable to most pin-structured perovskite devices with SAM as the HTL, and the fabrication process is highly operable and has very strong universality. 2. The 4-ABA2 small molecule provided in this invention is in the normal bandgap perovskite material FA. x MA 1-x PbI y Cl 3-y The system, a 1.67 eV wide-bandgap perovskite material, is a FA 0.73 MA 0.22 Cs 0.05 PbI 2.3 Br0.7 The ternary cation system, with a wide bandgap perovskite material of 1.77 eV, is FA. 0.8 Cs 0.2 PbI 1.8 Br 1.2 The system has significant improvement effects, mainly reflected in the following aspects: (1) 4-ABA2, as a small molecule material of the aniline series, has a benzene ring as the main body that can generate π-π conjugation with the carbazole ring in SAM, and due to its small steric hindrance, it can be well embedded in the SAM vacancy, improving the coverage; (2) The coating of 4-ABA2 can effectively improve the potential uniformity of SAM, and regulate the energy level matching between HTL and perovskite from the whole; the concentration of 4-ABA2 can also be adjusted to suit the SAM layer and perovskite of different systems; (3) The protonated amino group in 4-ABA2 can effectively passivate the A-site vacancy defects at the lower interface of perovskite, Cl - It can effectively passivate the X-site defects of the perovskite lower interface, improve the quality of the perovskite film at the lower interface and the charge transport performance between it and HTL. (4) The new structure formed by the intercalation of 4-ABA2 (~SAM~small molecule~SAM~small molecule~) helps stabilize the interface, and the protonated amino groups on the small molecule provide in-situ sites for subsequent crystallization of perovskite. Thus, by reducing residuals through high-temperature heat treatment and filling defects through dynamic washing of 4-ABA2 small molecules, the potential uniformity and coverage of HTL are improved, the defects of the perovskite lower interface are passivated and the energy level matching between HTL and perovskite is regulated, thereby significantly improving the device efficiency and stability of perovskite. (5) Compared with molecules such as ABABr anchored on the NiOx interface, 4-ABA2 has a shorter chain length and less steric hindrance, which is more conducive to intercalation into various types of SAM vacancies. Even when most of the -OH on the surface of ITO is anchored by SAM, it can achieve uniform distribution through π-π conjugation and hydrogen bonding with SAM molecules, thereby improving the interface. Attached Figure Description

[0017] Appendix Figure 1 This is a diagram illustrating the structure and working mechanism of the perovskite solar cell of the present invention.

[0018] Appendix Figure 2 These are the surface elemental analysis diagrams of HTL before and after treatment with 4-ABA2.

[0019] Appendix Figure 3 These are SEM comparison images of the perovskite bottom interface before and after 4-ABA2 treatment.

[0020] Appendix Figure 4 These are AFM and KPFM images of the perovskite bottom interface before and after 4-ABA2 treatment.

[0021] Appendix Figure 5This is the JV curve of a 1.55eV perovskite device.

[0022] Appendix Figure 6 This is the JV curve of a 1.67 eV perovskite device.

[0023] Appendix Figure 7 This is the JV curve of a 1.77 eV perovskite device.

[0024] Appendix Figure 8 This is the JV curve for testing calcium / silicon stacked devices. Detailed Implementation

[0025] To make the objectives, technical solutions, and beneficial effects of this invention clearer, the technical solutions of this invention will be clearly and completely described below in conjunction with specific embodiments and accompanying drawings. The same reference numerals in the drawings correspond to the same or similar components. It should be noted that the described embodiments are only some preferred embodiments of this invention, and not all embodiments. All other related embodiments obtained by those skilled in the art based on the embodiments disclosed in this invention without creative effort are within the protection scope of this invention.

[0026] like Figure 1 As shown, the present invention relates to a universal pin-structure perovskite device based on SAM-optimized modification, comprising: a transparent conductive anode ITO, a hole transport layer, a SAM-optimized modification layer SAMs, a perovskite light-absorbing layer, and an electron transport layer C. 60 +BCP and a metal conductive cathode Cu; wherein, a SAM-optimized modification layer is disposed between the hole transport layer and the perovskite light-absorbing layer, and the novel intercalated hole transport layer is composed of a self-assembled monolayer (SAM) treated with high temperature annealing and a low-polarity solvent small molecule filling layer; the high temperature annealing is used to remove weakly bonded molecules and oligomers remaining during the SAM self-assembly process; the low-polarity solvent contains specific small molecules, which have the dual functions of cleaning residual impurities on the SAM surface and filling SAM vacancy defects, and realize energy level regulation, optimize the energy level matching between the hole transport layer and the perovskite, and improve film uniformity, etc.; the device is suitable for perovskite devices with normal bandgap (~1.55 eV) single-junction pin structure, perovskite devices with wide bandgap (~1.65-1.77 eV) pin structure, and perovskite / silicon tandem (silicon-calcium tandem) solar cells.

[0027] The device structure of the present invention, from bottom to top, consists of a transparent conductive substrate, a hole transport layer (self-assembled monolayer), a small molecule passivation layer, a perovskite layer, an electron transport layer, and an electrode layer.

[0028] The transparent conductive substrate is ITO glass or FTO glass; The material of the self-assembled monolayer (SAM) is selected from any one of MeO-2PACz, 4-PADCB, and Me-4PACz. The solvent for preparing the SAM is ethanol with a concentration of 0.3~0.5 mg / mL.

[0029] The low-polarity solvent is selected from either isopropanol or ethanol; the specific small molecule is selected from p-aniline hydrochloride (e.g., 4-aminophenylamidine dihydrochloride), and the concentration of the small molecule in the low-polarity solvent is 0.1~0.4 mg / mL.

[0030] The perovskite light-absorbing layer is made of a perovskite material selected according to the band gap requirement: the perovskite material for normal band gap is Cs. 0.1 FA 0.85 MA 0.05 The PbI3 system, a 1.67 eV wide-bandgap perovskite material, is a FA 0.73 MA 0.22 Cs 0.05 PbI 2.3 Br 0.7 The ternary cation system, with a wide bandgap perovskite material of 1.77 eV, is FA. 0.8 Cs 0.2 PbI 1.8 Br 1.2 All systems were prepared using a one-step spin coating method combined with antisolvent engineering.

[0031] The electron transport layer is a C60 with a thickness of 18~22nm; subsequently, a BCP of ~7nm is deposited as a barrier layer.

[0032] The metal conductive cathode is either Cu or Ag, and is prepared by vacuum thermal evaporation.

[0033] The specific preparation method includes the following steps: (1) The conductive substrate ITO / FTO was ultrasonically cleaned for 15 minutes each with dish soap water, deionized water, acetone and ethanol in sequence. (2) After the substrate is dried with nitrogen, it is placed in an ultraviolet ozone generator for 15 minutes and then transferred to a glove box filled with nitrogen for subsequent preparation. (3) Spin-coat a 0.5 mg / mL ethanol solution of MeO-2PACz onto the prepared ITO substrate at a spin speed of 3000~4000 rpm for 30 s. (4) Further, the substrate is subjected to high-temperature heat treatment to reduce residue, specifically one of hot stage heating, laser heating, or hot air heating, with a treatment temperature of 120~130℃ and a time of 10min; (5) Further, after the substrate cools to room temperature, the SAM layer covering the ITO is subjected to dynamic spin-coating of 4-ABA2 small molecules. The spin-coating speed is 4000~5000 rpm and the time is 30s. When the remaining time is 25s, the coating is applied to a 2×2cm layer. 2 Titrate 30-40 μl of small molecule solution onto the substrate, then anneal it on a hot plate at 100 °C for 5 min; (6) Further, after the substrate has cooled to room temperature, spin-coating of a 1.6 mm wide-bandgap PSK (FA) is continued. 0.73 MA 0.22 Cs 0.05 PbI 2.3 Br 0.7 The precursor solution (a mixture of N,N-dimethylformamide (DMF) and dimethyl sulfoxide (DMSO) in a ratio of 4–9:1) was prepared. The spin coating process consisted of two steps: Step 1: 1000 rpm for 5–10 s, Step 2: 4500 rpm for 30–50 s. In Step 2, 0.3–0.5 ml of diethyl ether antisolvent was titrated onto the center of the film 10–25 s before the end of the spin coating process. The film was then placed on a hot plate at 100 °C for annealing for 10 min. This process was used to prepare the perovskite layer. (7) Further, an electron transport layer C60 of 18~22nm and a barrier layer BCP of 7nm were prepared by vacuum evaporation. (8) Finally, a metal electrode (Cu / Ag) with a diameter of 100~120 nm was prepared by vacuum evaporation.

[0034] Example 1: Fabrication of perovskite devices with normal bandgap (~1.55 eV) pin structure 1. Substrate pretreatment (1) Take an ITO glass substrate (2×2 cm) 2 The surface is ultrasonically cleaned for 15 minutes each with dish soap, deionized water, acetone, and ethanol in sequence to remove oil and impurities. (2) After drying with nitrogen, the substrate is placed in an ultraviolet ozone generator for 15 min to improve the hydrophilicity of the substrate surface, and then transferred to a glove box filled with nitrogen for later use.

[0035] 2. Fabrication of SAM hole transport layer (1) Prepare a 0.5 mg / mL MeO-2PACz ethanol solution and shake and stir for 1 h until completely dissolved; (2) Spin-coat the above solution onto the pretreated ITO substrate at 4000 rpm for 30 s to form a basic SAM layer.

[0036] 3. High-temperature heat treatment to reduce residues The substrate coated with SAM layer was heated on a hot stage at 130°C for 10 minutes to remove weakly bonded molecules remaining during the SAM self-assembly process, and then naturally cooled to room temperature.

[0037] 4. Dynamic Coating and Curing of 4-ABA2 Small Molecules (1) Prepare a 0.2 mg / mL solution of 4-ABA2 isopropanol and shake and stir for 20 min; (2) Place the SAM layer substrate on a spin coater, set the rotation speed to 5000 rpm and the time to 30 s. When there are 25 s left in the spin coating, drop 40 μL of 4-ABA2 solution onto the center of the substrate. (3) After spin coating, the substrate is placed on a hot stage at 100°C for annealing for 5 min to form an optimized modified hole transport layer, and then cooled to room temperature.

[0038] 5. Preparation of perovskite light-absorbing layer (1) Configure Cs 0.1 FA 0.85 MA 0.05 PbI3 perovskite precursor solution (solvent DMF:DMSO=9:1, volume ratio), shake and stir for 3 h, then heat on a hot table at 60℃ for 30 min; (2) Spin-coat the precursor solution onto the optimized hole transport layer. The spin coating is divided into two steps: Step 1 (1000 rpm, 5 s) and Step 2 (4000 rpm, 30 s). 0.4 mL of diethyl ether antisolvent is titrated 10 s before the end of Step 2. (3) After spin coating, anneal at 100°C for 15 min to form a perovskite light-absorbing layer, and then cool to room temperature. Then, apply 0.5 mg / mL of EDAI2 IPA solution for post-treatment, anneal for 5 min, and then cool to room temperature.

[0039] 6. Electron transport layer and electrode fabrication (1) Vacuum evaporation of 22nm thick C 60 An electron transport layer was then deposited, followed by the deposition of a 7nm thick BCP blocking layer. (2) Continue vacuum evaporation to deposit a 110 nm thick Cu electrode to complete the fabrication of a normal bandgap pin structure perovskite device.

[0040] Example 2: Fabrication of wide-bandgap (1.67 eV) pin-structured perovskite devices Steps 1-4: Same as in Example 1 (the hole transport layer uses an IPA solution of 0.5 mg / mL 4-PADCB). 5. Preparation of perovskite light-absorbing layer (1) Configure FA 0.73 MA 0.22Cs 0.05 PbI 2.3 Br 0.7 The perovskite precursor solution (solvent DMF:DMSO=4:1, volume ratio) was shaken and stirred for 3 hours, followed by heating at 60°C for 30 minutes on a hot plate.

[0041] (2) Spin-coating the precursor solution onto the optimized hole transport layer. The spin-coating is divided into two steps: Step 1 (1000 rpm, 10 s) and Step 2 (4500 rpm, 50 s). 15 seconds before the end of Step 2, 0.35 mL of diethyl ether antisolvent is titrated and annealed at 100℃ for 10 min to form a 1.67 eV wide-bandgap perovskite layer.

[0042] 6. Electron transport layer and electrode fabrication: Vacuum evaporation of 20nm thick C 60 An electron transport layer was deposited, followed by the deposition of a 7 nm thick BCP blocking layer and a 100 nm Cu electrode to obtain a 1.67 eV wide-bandgap pin-structured perovskite device.

[0043] Example 3: Fabrication of a wide-bandgap (1.77 eV) pin-structured perovskite device Steps 1-4: Same as in Example 1 (the hole transport layer uses an IPA solution of 0.4 mg / mL 4-PACz). 5. Preparation of perovskite light-absorbing layer (1) Configure FA 0.8 Cs 0.2 PbI 1.8 Br 1.2 The perovskite precursor solution (solvent DMF:DMSO=4:1, volume ratio) was shaken and stirred for 3 hours, followed by heating at 60°C for 30 minutes on a hot stage. (2) The spin coating parameters were the same as in Example 2. The antisolvent was added in a volume of 0.45 mL and the mixture was annealed at 100°C for 10 min to form a 1.77 eV wide-bandgap perovskite layer.

[0044] 6. Vacuum evaporation of 18nm thick C 60 An electron transport layer was deposited, followed by the deposition of a 7 nm thick BCP blocking layer and a 100 nm Cu electrode to obtain a 1.77 eV wide-bandgap pin-structured perovskite device.

[0045] Example 4: Fabrication of perovskite / silicon tandem solar cells Steps 1-4: Completely consistent with Example 2 (the substrate is replaced with a silicon-based composite substrate, and the pretreatment method is adapted to the requirements of silicon-based substrates, with only 5 minutes of ethanol rinsing). 5. Preparation of perovskite light-absorbing layer: The top light-absorbing layer was formed using the 1.67 eV wide-bandgap perovskite material and preparation process described in Example 2; 6. Electron transport layer fabrication: Vacuum evaporation of 20nm C 60 Subsequently, 20nm of SnO2 was deposited using atomic force deposition.

[0046] 7. Top electrode fabrication: 80nm ITO layer was sputtered by magnetron sputtering, followed by vacuum evaporation of a 500nm silver gate electrode.

[0047] As attached Figure 2 As shown, XPS tests on the hole transport layer before and after the treatment in Example 2 revealed that the Cl and N1s peaks directly demonstrate that the 4-ABA2 small molecule is well coated on the bottom interface and can effectively passivate the X vacancies on the perovskite bottom interface. The low binding energy -OH peak in the O1s peak showed a significant decrease in intensity after 4-ABA2 coating, indicating a significant improvement in overall coverage. The high binding energy in the O1s peak corresponds to the In-O peak, whose relative intensity remained almost unchanged, indicating that the effective SAM was not eliminated by dynamic washing. Furthermore, the Cl2p peak position was significantly different, indicating that the presence of Cl- on the lower interface provides sites for perovskite nucleation and has a very positive effect on the passivation of the lower interface.

[0048] Subsequently, after the perovskite film was coated, a peeling operation was performed, and the perovskite subsurface interface was tested as shown in the attached figure. Figure 3 and attached Figure 4 As shown, the SEM image of the buried interface in the control group was very rough, which was due to the poor film quality caused by SAM accumulation. After washing with EtOH, the film at the bottom interface was very smooth, but due to excessive polarity, over-washing occurred, resulting in the removal of most SAM molecules and the formation of pores in the perovskite. Washing with IPA yielded results somewhere in between. Subsequently, washing with an IPA solution containing 4-ABA2 resulted in the bottom interface retaining a uniform SAM distribution while maintaining film integrity. AFM testing showed that the Rq value of the film at the bottom interface was significantly reduced, becoming smoother, and the potential uniformity was significantly reflected in the KPFM image, which is crucial for interface transport and stability. This is distinctly different from the mechanism by which 4-aminobenzylamine hydroiodate forms a two-dimensional phase in tin-based perovskites through bulk doping.

[0049] Control group (pin structure device without optimized SAM hole transport layer) Except for omitting the "high-temperature heat treatment for residue reduction" and "4-ABA2 small molecule coating" steps, the remaining preparation processes, materials, and parameters are consistent with those in Examples 1-4, resulting in four groups of unoptimized control group devices (see appendix). Figure 5-8As clearly seen from the JV curves, the devices with different bandgap values ​​after treatment all show varying degrees of improvement in open-circuit voltage, short-circuit current, and fill factor. Furthermore, compared to NiOx modification with ABABr, where the highest PCE for the CsFAMA system with a normal bandgap is 21.60, the PCE of the 1.55 eV bandgap device of this invention exceeds 24%, the PCE of the 1.67 eV device exceeds 23%, and the PCE of the calcium / silicon multilayer device exceeds 30%, demonstrating significant advantages.

[0050] Those skilled in the art should understand that the foregoing specific embodiments are merely illustrative and not restrictive. Various modifications, combinations, partial combinations, and substitutions can be made to the embodiments of the present invention in combination with design requirements and other practical factors. As long as such embodiments fall within the scope defined by the appended claims and their equivalent technical solutions, they should be included in the protection scope of the present invention.

Claims

1. A method for fabricating a hole transport layer for multi-bandgap pin perovskite solar cells, characterized in that, Includes the following steps: (1) Prepare a self-assembled monolayer as a hole transport layer on a transparent conductive substrate; (2) Perform high-temperature heat treatment on the hole transport layer to reduce residue and remove weak bond molecules and oligomers remaining during the SAM self-assembly process; (3) Coat the hole transport layer after high-temperature heat treatment with a solution containing specific small molecules and perform dynamic coating treatment; (4) Heat treat the coated hole transport layer to form a SAM optimized modification layer with both homogenization and vacancy passivation functions, and obtain a hole transport layer with an intercalation structure of small molecules and SAM spaced apart.

2. The preparation method according to claim 1, characterized in that, In step (1), the material for the self-assembled monolayer is selected from one or more of carbazole, aniline, and pyridine self-assembled molecules; the solvent for preparing the self-assembled monolayer is an alcohol solvent with a concentration of 0.3~1 mg / mL; in step (2), the high-temperature heat treatment method is one of hot table heating, laser heating, and hot air heating, with a heat treatment temperature of 120~130℃ and a heat treatment time of 10~15 min; in step (3), the dynamic coating treatment is spin coating, with a spin coating speed of 4000~5000 rpm and a spin coating time of 30 s, and when there are 25 s remaining in the spin coating time, the coating is applied to a 2×2 cm⁻¹ layer. 2 Substrate titration with 30-40 μL of a solution containing specific small molecules; the heat treatment temperature in step (4) is 100℃ and the heat treatment time is 5-10 min.

3. The preparation method according to claim 1, characterized in that, The mass ratio of the specific small molecule to the hole transport layer is (0.2~0.8):

1.

4. The preparation method according to claim 1, characterized in that, The solvent of the solution containing the specific small molecule in step (3) is selected from one or more of low polarity solvents and weak polarity solvents; the specific small molecule is an organic small molecule containing a π-π conjugated structure and having protonated amino groups, halide ions or other defect passivating groups.

5. The preparation method according to claim 1, characterized in that, The specific small molecule is 4-aminobenzoic acid dihydrochloride.

6. The preparation method according to claim 1, 2, 3, 4 or 5, characterized in that, The concentration of the specific small molecule in the low-polarity solvent is 0.1~0.4 mg / mL.

7. A hole transport layer material with a layered structure of small molecules and SAM spaced apart, obtained by the preparation method according to any one of claims 1 to 6.

8. The application of the hole transport layer of the intercalation structure of small molecules and SAM spaced apart as described in claim 7 in pin-structured perovskite devices or perovskite / silicon tandem solar cells.

9. The application according to claim 8, characterized in that, The pin-structured perovskite device includes a transparent conductive substrate, a hole transport layer, a perovskite light-absorbing layer, an electron transport layer, and a metal electrode. The fabrication of the pin-structured perovskite device includes the following steps: (1) optimizing the interface of the SAM hole transport layer using the method described in any one of claims 1 to 8 to obtain a modified hole transport layer; (2) fabricating a perovskite light-absorbing layer on the modified hole transport layer; (3) sequentially fabricating an electron transport layer and a metal electrode on the perovskite light-absorbing layer to obtain a pin-structured perovskite device.

10. The application according to claim 9, characterized in that, The transparent conductive substrate is ITO glass or FTO glass; the electron transport layer is a C material with a thickness of 18~22nm. 60 And in C 60 A BCP blocking layer with a thickness of ~7 nm is deposited on the layer; the metal electrode is Cu or Ag with a thickness of 100~120 nm; the perovskite light-absorbing layer is prepared by a one-step spin coating method combined with antisolvent engineering, the antisolvent is diethyl ether, and the solvent of the perovskite precursor solution is a mixture of N,N-dimethylformamide and dimethyl sulfoxide in a volume ratio of 4:1.

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