Three-dimensional stacking undoped hole transport material, preparation method and application thereof, and perovskite solar cell

Abstract

The application provides a three-dimensional stacking undoped hole transport material, a preparation method and application thereof, and a perovskite solar cell, and belongs to the technical field of solar cells. The hole transport material has a core of an extended helical orthogonal structure, and a peripheral capping group controls planarity, reduces steric hindrance of the peripheral capping group, realizes 3D multidirectional 'network' dense stacking, and realizes a multidirectional continuous carrier transport channel. When the hole transport material is applied to a perovskite solar cell as a hole transport layer, a high open-circuit voltage of >1.1 V and a photoelectric conversion efficiency of >19% can be obtained without a dopant, a high-efficiency and stable undoped material system is realized, and the application prospect is wide.

Description

Technical Field

[0001] This invention relates to the field of solar cell technology, and in particular to a three-dimensional stacked doped hole transport material, its preparation method and application, and perovskite solar cells. Background Technology

[0002] Perovskite solar cells (PSCs) are a next-generation photovoltaic technology with many advantages, including low cost, high efficiency, solution-processability, and large-area fabrication. The rapid development of perovskite photovoltaic technology demonstrates its enormous potential; combined with its cost-efficiency ratio, PSC technology is a very attractive future energy technology globally.

[0003] In 2009, Miyasaka pioneered the introduction of MAPbI3 as a sensitizer into fuel-sensitized solar cells (PSSCs), achieving a power conversion efficiency (PCE) of 3.8%. However, iodide solutions readily dissolve perovskite, resulting in a short device lifespan. In 2012, Park and Snaith replaced the liquid electrolyte with tetratetra[N,N-di(4-methoxyphenyl)amino]spirodifluorene (Spiro-OMeTAD) as the hole transport material (HTM), achieving PCEs of 9.7% and 10.9% for their respective all-solid-state devices. Following this, PSCs entered a period of rapid development. Within a decade, the PCE record for PSCs surpassed 25%.

[0004] As a significant milestone in the development of PSCs, the classic hole transport material Spiro-OMeTAD possesses advantages such as multidirectional exciton conduction and high film-forming properties. However, its compact helical orthogonal structure hinders the formation of tight π-π stacking, and the large steric hindrance of diphenylamine on the periphery leads to a large intermolecular distance. To improve hole mobility, dopants such as 4-tert-butylpyridine (t-BP) must be introduced. Although dopants suppress exciton recombination and improve mobility and conductivity, the introduction of dopants brings new problems: (1) the dopants volatilize slowly and have hydrophilic and ionic properties, corroding perovskite and HTM films, making the device thermally unstable; (2) the post-oxidation process of the doped Spiro-OMeTAD film results in poor device reproducibility, increasing the overall complexity and cost of fabrication. Therefore, the development of doped, efficient, stable, and low-cost HTM is essential for the commercialization of PSCs. Doped HTM can avoid the disadvantage of decreased stability caused by doping, simplify the device fabrication process, and reduce device production costs. Compared to polymeric HTMs, small molecule HTMs have precise chemical structures and batch-invariant molecular weights. Their molecular structure and energy levels are easily controlled, and their synthesis and purification processes are simple. Therefore, dopant-free organic small molecule HTMs have become a hot topic among researchers.

[0005] Currently, organic semiconductor design strategies such as extended π-conjugated systems, alkyl chain engineering, introduction of passivating groups, and DA molecular structures have been successfully applied to the design of doped HTMs. Several doped HTMs with linear, star-shaped, or two-dimensional planar structures have emerged, achieving excellent hole mobility and device efficiency. Sonar (Pham, HD, Yang, TCJ, Jain, SM, Wilson, GJ, & Sonar, P. (2020). Development of dopant-free organic hole transporting materials for perovskite solar cells. Advanced Energy Materials, 10(13), 1903326.) categorized and statistically analyzed reported novel dopant-free hydrogen-transporting materials (HTMs) based on different geometric structures. Most reported HTMs possess linear or star-shaped molecular structures, forming compact "linear" or "honeycomb" patterns through π-π stacking. This unidirectional molecular stacking results in a single exciton transport path, often leading to poor solubility, high crystallinity, and dense pinholes in the resulting films. This causes exciton interface recombination, frequently resulting in short circuits and low reproducibility in the devices. Therefore, one future development direction for dopant-free HTMs is to more precisely control molecular stacking, optimize exciton transport paths, and achieve continuous charge transport in both horizontal and vertical directions. Summary of the Invention

[0006] The purpose of this invention is to provide a three-dimensional stacked doped hole transport material, its preparation method and application, and perovskite solar cells. The hole transport material can form a three-dimensional stack, realize multidirectional exciton conduction, and has more balanced crystallinity and film-forming properties.

[0007] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0008] This invention provides a three-dimensional stacked doped hole transport material having the structure shown in Formula I:

[0009]

[0010] In Equation I, R is

[0011] This invention provides a method for preparing the three-dimensional stacked doped hole transport material described above, comprising the following steps:

[0012] Compound 1 with the structure shown in Formula II, potassium permanganate and the first solvent were mixed and subjected to a nitrogen-nitrogen coupling reaction to obtain compound 2 with the structure shown in Formula III.

[0013] Compound 2 with the structure shown in Formula III, pinacol diborate, 1,1'-bis(diphenylphosphine)ferrocene palladium dichloride, potassium acetate, and a second solvent were mixed and subjected to a Miyaura borylation reaction to obtain compound 3 with the structure shown in Formula IV.

[0014] The compound 3 with the structure shown in Formula IV, the end-capping compound, palladium acetate, phase transfer catalyst, potassium phosphate and the third solvent are mixed and end-capped to obtain the three-dimensional stacked doped hole transport material with the structure shown in Formula I.

[0015] The terminating compound is:

[0016]

[0017] Preferably, the molar ratio of compound 1 with the structure shown in Formula II to potassium permanganate is 1:(1-5); the first solvent is acetone, tetrahydrofuran, or 1,4-epoxyhexacyclohexane.

[0018] Preferably, the nitrogen-nitrogen coupling reaction is carried out at a temperature of 60°C for 12 hours.

[0019] Preferably, the molar ratio of compound 2 with the structure shown in Formula III, pinacol diborate, 1,1'-bis(diphenylphosphine)ferrocene palladium dichloride, and potassium acetate is 4.08:10.2:0.29:30.

[0020] Preferably, the Miyaura borylation reaction is carried out at a temperature of 60–120°C for a time of 12–36 h.

[0021] Preferably, the phase transfer catalyst includes sphos, XPhos, or Tbu3P; the molar ratio of compound 3 with the structure shown in Formula IV, the end-capping compound, palladium acetate, the phase transfer catalyst, and potassium phosphate is 0.60:1.30:0.03:0.06:4.8.

[0022] Preferably, the sealing temperature is 100°C and the time is 12 to 36 hours.

[0023] This invention provides the application of the three-dimensional stacked doped hole transport material described in the above technical solution or the three-dimensional stacked doped hole transport material prepared by the preparation method described in the above technical solution in perovskite solar cells.

[0024] This invention provides a perovskite solar cell, comprising a conductive substrate, an electron transport layer, a perovskite active layer, a hole transport layer, and a metal electrode stacked sequentially; the hole transport material used in the hole transport layer is the three-dimensional stacked doped hole transport material described in the above technical solution or the three-dimensional stacked doped hole transport material prepared by the preparation method described in the above technical solution.

[0025] This invention provides a three-dimensional stacked doped hole transport material.

[0026] In the three-dimensional stacked doped hole transport material of this invention, the core structural unit It possesses a certain rigid structure and multiple active sites; the peripheral capping groups (R) have different planar structures, extended π-conjugated systems, and good hole transport capabilities; and the hole transport material forms an orthogonal molecular conformation by vertically connecting two rigid π-conjugated systems (two core structural units connected), constructing a helical orthogonal 3D spatial geometry, expanding the core space while regulating the steric hindrance of the peripheral capping groups, and utilizing the π-conjugated system of the peripheral capping and intermolecular interactions (CH…O hydrogen bonds or F…S and π-π stacking) to form a three-dimensional dense network stack, increasing wave function overlap, optimizing the intermolecular charge jump path, realizing three-dimensional continuous hole transport, achieving a balance between material crystallinity and film-forming properties, reducing interface defects, and exhibiting a three-dimensional molecular stacking effect.

[0027] This invention utilizes two rigid building units (peripheral capping groups) fused into a helical orthogonal structure, endowing the molecule with rigidity and amorphousness. By controlling the planarity of the peripheral capping groups, the crystallinity and film-forming properties of the material are balanced, excessive molecular aggregation is inhibited, and high-quality hole transport materials are prepared.

[0028] The hole transport material provided by this invention extends the π-conjugated system by using peripheral end-capping groups and introduces fluorine and sulfur atoms, which can increase the intermolecular interaction force. In addition, the contained heteroatoms (S, F) can passivate perovskite surface defects, suppress carrier interface recombination, promote charge conduction, and improve the photoelectric conversion efficiency of PSCs.

[0029] This invention provides a method for preparing the aforementioned three-dimensional stacked dopant-free hole transport material. The invention utilizes a nitrogen-nitrogen coupling reaction to extend the core of the helical orthogonal structure, while simultaneously controlling the planarity of the peripheral end-capping groups to reduce their steric hindrance, thereby achieving dense 3D multidirectional "network" stacking and multidirectional continuous carrier transport channels. The synthesis method of this invention is simple, the material cost is low, and the prepared material can achieve three-dimensional molecular stacking and three-dimensional charge conduction, exhibiting good film-forming properties and passivating perovskite interfaces. When this hole transport material is applied as a hole transport layer in perovskite solar cells, it can achieve a high open-circuit voltage of >1.1V and a photoelectric conversion efficiency of >19% without dopants, realizing a highly efficient and stable dopant-free material system with broad application prospects. Attached Figure Description

[0030] Figure 1 The image shows the 1H NMR spectrum of compound 2.

[0031] Figure 2The image shows the 1H NMR spectrum of compound 3.

[0032] Figure 3 The 1H NMR spectrum of compound BCzOPA;

[0033] Figure 4 The 1H NMR spectrum of compound BCzSPA;

[0034] Figure 5 Thermogravimetric curves of BCzOPA prepared in Example 1 and BCzSPA prepared in Example 2 are shown.

[0035] Figure 6 The schematic diagrams are of the planar heterojunction perovskite solar cell structures in Examples 1 and 2.

[0036] Figure 7 The IV curves are for the perovskite solar cells prepared using Examples 1-2. Detailed Implementation

[0037] This invention provides a three-dimensional stacked doped hole transport material having the structure shown in Formula I:

[0038]

[0039] In Equation I, R is

[0040] The three-dimensional stacked doped hole transport material provided by this invention is specifically as follows:

[0041]

[0042] This invention fundamentally alters the geometry of the Spiro-core, preparing a helical orthogonal core with an extended spatial structure. Two rigid π-conjugated systems are vertically connected via a nitrogen-nitrogen coupling reaction to form an orthogonal molecular conformation, constituting a 3D molecular structural framework. Adjusting the spatial structure of the helical orthogonal core while reducing the steric hindrance of the peripheral end-capping groups achieves dense 3D multidirectional "network" stacking and multidirectional continuous carrier transport channels. Furthermore, by controlling the planar rigidity of the peripheral end-capping groups, the crystallinity and film-forming properties of the material are balanced. The 3D stacked doped-free HTM in this invention is not only of significant research importance for improving the efficiency and stability of PSCs, but also provides valuable reference for controlling the crystalline domains of non-fullerene 3D acceptor materials.

[0043] This invention provides a method for preparing the three-dimensional stacked doped hole transport material described above, comprising the following steps:

[0044] Compound 1 with the structure shown in Formula II, potassium permanganate and the first solvent were mixed and subjected to a nitrogen-nitrogen coupling reaction to obtain compound 2 with the structure shown in Formula III.

[0045] Compound 2 with the structure shown in Formula III, pinacol diborate, 1,1'-bis(diphenylphosphine)ferrocene palladium dichloride, potassium acetate, and a second solvent were mixed and subjected to a Miyaura borylation reaction to obtain compound 3 with the structure shown in Formula IV.

[0046] The compound 3 with the structure shown in Formula IV, the end-capping compound, palladium acetate, phase transfer catalyst, potassium phosphate and the third solvent are mixed and end-capped to obtain the three-dimensional stacked doped hole transport material with the structure shown in Formula I.

[0047] The terminating compound is:

[0048]

[0049]

[0050] In this invention, unless otherwise specified, all raw materials required for preparation are commercially available products well known to those skilled in the art.

[0051] In this invention, compound 1 with the structure shown in Formula II, potassium permanganate, and a first solvent are mixed and subjected to a nitrogen-nitrogen coupling reaction to obtain compound 2 with the structure shown in Formula III.

[0052] In this invention,

[0053] In this invention, the molar ratio of compound 1 with the structure shown in Formula II to potassium permanganate is preferably 1:(1-5), more preferably 1:2.5; the first solvent is preferably acetone, tetrahydrofuran, or 1,4-epoxyhexacyclohexane; this invention does not have a special limitation on the amount of the first solvent, and adjustments can be made according to actual needs to ensure the smooth progress of the reaction. This invention utilizes potassium permanganate as a catalyst to construct a helical orthogonal core through NN coupling, thereby constructing a novel 3D spatial structure core, extending the core spatial structure, and reducing the steric hindrance of the core.

[0054] The present invention does not have any particular limitation on the mixing process of compound 1 with the structure shown in Formula II, potassium permanganate and the first solvent. The materials can be mixed evenly according to a process known in the art.

[0055] In this invention, the temperature of the nitrogen-nitrogen coupling reaction is preferably 60°C, and the time is preferably 12 hours; the nitrogen-nitrogen coupling reaction is preferably carried out under nitrogen protection conditions.

[0056] After completing the nitrogen-nitrogen coupling reaction, the present invention preferably cools the obtained material to room temperature, removes the solvent, extracts, and then washes, dries, evaporates, and separates the obtained organic phase to obtain compound 2 with the structure shown in Formula III. In the present invention, the reagent used for extraction is preferably dichloromethane; the reagent used for washing is preferably a saturated sodium chloride solution, and the number of washings is preferably three; the drying method is preferably anhydrous sodium sulfate drying, and the separation method is preferably dichloromethane silica gel column separation; the present invention does not have any special limitations on the amount of reagents used for extraction, washing, drying, evaporation, and separation, or the specific operation process, and can be carried out according to procedures well known in the art.

[0057] After obtaining compound 2 with the structure shown in Formula III, the present invention mixes compound 2 with the structure shown in Formula III, pinacol diborate, 1,1'-bis(diphenylphosphine)ferrocene palladium dichloride, potassium acetate, and a second solvent to carry out a Miyaura borylation reaction to obtain compound 3 with the structure shown in Formula IV.

[0058] In this invention, the preferred molar ratio of compound 2 (of Formula III), pinacol diborate, 1,1'-bis(diphenylphosphine)ferrocene palladium dichloride, and potassium acetate is 4.08:10.2:0.29:30. This invention utilizes 1,1'-bis(diphenylphosphine)ferrocene palladium dichloride as a catalyst for the coupling reaction, and potassium acetate provides an alkaline environment.

[0059] In this invention, the second solvent is preferably 1,4-dioxane; the 1,4-dioxane is preferably anhydrous and oxygen-free; this invention does not have a special limitation on the amount of the second solvent, and it can be adjusted according to actual needs to ensure that the reaction proceeds smoothly.

[0060] The present invention does not have any particular limitation on the mixing process of compound 2 with the structure shown in Formula III, pinacol diboronate, 1,1'-bis(diphenylphosphine)ferrocene palladium dichloride, potassium acetate, and the second solvent. The materials can be mixed evenly according to a process known in the art.

[0061] In this invention, the Miyaura borylation reaction is preferably carried out under nitrogen protection; the temperature of the Miyaura borylation reaction is preferably 60-120°C, more preferably 110°C, and the time is preferably 12-36 h, more preferably 24 h.

[0062] After completing the Miyaura borylation reaction, the present invention preferably quenches the obtained material with water, extracts it with ethyl acetate, washes the resulting organic phase three times with saturated sodium chloride solution, dries it with anhydrous sodium sulfate, and then evaporates it to dryness. The resulting solid is then passed through a silica gel column in dichloromethane to obtain compound 3 with the structure shown in Formula IV. The present invention does not impose any special limitations on the amount of reagents used in the quenching, extraction, washing, drying, evaporation, and silica gel column chromatography, nor on the specific operational procedures; procedures well known in the art can be followed.

[0063] In this invention, the compound with the structure shown in Formula IV is

[0064] After obtaining compound 3 with the structure shown in Formula IV, the present invention mixes compound 3 with the structure shown in Formula IV, end-capping compound, palladium acetate, phase transfer catalyst, potassium phosphate and third solvent, and performs end-capping to obtain a three-dimensional stacked doped hole transport material with the structure shown in Formula I.

[0065] In this invention, the capping compound is:

[0066] (denoted as OPA) or (Recorded as SPA).

[0067] In this invention, the phase transfer catalyst preferably comprises sphos, XPhos, or Tbu3P; the third solvent is preferably 1,4-dioxane; and the molar ratio of compound 3 with the structure shown in Formula IV, the end-capping compound, palladium acetate, the phase transfer catalyst, and potassium phosphate is preferably 0.60:1.30:0.03:0.06:4.8. This invention utilizes palladium acetate as a catalyst to catalyze coupling reactions; utilizes a phase transfer catalyst to accelerate the reaction rate; and utilizes potassium phosphate to provide an alkaline environment.

[0068] The present invention does not have any particular limitation on the mixing process of compound 3 with the structure shown in Formula IV, the end-capping compound, palladium acetate, phase transfer catalyst, potassium phosphate and the third solvent. The materials can be mixed evenly according to a process known in the art.

[0069] In this invention, the sealing is preferably carried out under nitrogen protection; the sealing temperature is preferably 100°C, and the sealing time is preferably 12 to 36 hours, more preferably 24 hours.

[0070] After the end-capping is completed, the present invention preferably extracts the obtained product with dichloromethane, washes it with saturated brine, dries it with anhydrous sodium sulfate, and then passes the obtained solid through a silica gel column to obtain a three-dimensional stacked doped hole transport material; the eluent used for passing the silica gel column is preferably petroleum ether and ethyl acetate; the volume ratio of petroleum ether to ethyl acetate is preferably 4:1.

[0071] In this invention, the preparation process of the three-dimensional stacked doped hole transport material is as follows:

[0072]

[0073] This invention provides the application of the three-dimensional stacked doped hole transport material described in the above technical solution or the three-dimensional stacked doped hole transport material prepared by the preparation method described in the above technical solution in perovskite solar cells.

[0074] This invention provides a perovskite solar cell, comprising a conductive substrate, an electron transport layer, a perovskite active layer, a hole transport layer, and a metal electrode stacked sequentially; the hole transport material used in the hole transport layer is the three-dimensional stacked doped hole transport material described in the above technical solution or the three-dimensional stacked doped hole transport material prepared by the preparation method described in the above technical solution.

[0075] In this invention, the conductive substrate is preferably FTO or ITO.

[0076] In this invention, the material used for the electron transport layer preferably includes one or more of titanium dioxide, tin dioxide, zinc oxide, and zinc tin oxide; the thickness of the electron transport layer is preferably 5-30 nm, more preferably 15-20 nm.

[0077] This invention does not impose any specific limitation on the composition of the perovskite active layer; any material well-known in the art can be used. In this invention, the thickness of the perovskite active layer is preferably 100–800 nm, more preferably 400–650 nm. In an embodiment of this invention, the material of the perovskite active layer is specifically (CsI). 0.05 (FAPbI3) 0.79 (MAPbBr3) 0.16 .

[0078] The present invention does not impose any particular limitation on the metal electrode; any metal electrode known in the art may be used.

[0079] In this invention, the preferred method for fabricating the perovskite solar cell includes: cleaning the conductive substrate using a semiconductor process and then drying it with N2; fabricating an electron transport layer on the conductive substrate; fabricating a perovskite active layer on the electron transport layer; fabricating a hole transport layer on the perovskite active layer; and evaporating and depositing a metal electrode on the hole transport layer. This invention does not impose any specific limitations on the specific operational process for fabricating the perovskite solar cell; any process well-known in the art can be followed.

[0080] In an embodiment of the present invention, the method for preparing the perovskite solar cell is specifically as follows:

[0081] 1) Cleaning the conductive substrate:

[0082] The etched conductive substrate was ultrasonically treated in cleaning agent, deionized water, anhydrous ethanol, acetone and isopropanol for 15 min in sequence, then removed and dried with nitrogen (N2), placed in an oven and dried at 120℃ for 8 h, and treated with ultraviolet / ozone for 30 min.

[0083] 3) Preparation of tin dioxide (SnO2) electron transport layer

[0084] Prepare a 0.1M stannous chloride (SnCl2·2H2O) ethanol solution, spin-coat the resulting solution onto a conductive substrate at 3000 rpm for 40 s, and anneal the resulting film in air at 180 °C for 1 h.

[0085] 4) Preparation of perovskite light-absorbing layer

[0086] The perovskite solution was prepared by mixing FAI (1 mol / L), PbI2 (1.1 mol / L), MABr (0.2 mol / L), and PbBr2 (0.22 mol / L) in DMF:DMSO = 4:1 (v:v), and was then spin-coated in two steps: 1000 rpm for 10 s and 6000 rpm for 20 s. When there were 5 seconds remaining, chlorobenzene was distributed in the middle of the substrate, and the film was annealed at 100 °C for 1 h.

[0087] 4) Fabrication of the hole transport layer

[0088] Dissolve 30 mg of hole transport material in 1 mL of chlorobenzene to obtain a hole transport layer solution, drop it onto a perovskite film, spin coat it at 4000 rpm for 30 s, and then place it in air for 12 h.

[0089] 5) Fabrication of gold electrodes

[0090] Gold electrodes were fabricated on the surface of the hole transport layer using a high-vacuum thermal evaporation method, at a depth of 1×10⁻⁶. -6 Under a vacuum of Pa, Gold electrodes were prepared by rate evaporation deposition, with the electrode thickness controlled to be 100 nm.

[0091] The technical solutions of this invention will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0092] Example 1

[0093] Compound 1 (246 mg, 1 mmol), 10 mL of acetone, and potassium permanganate (395 g, 2.5 mmol) were added to a 250 mL two-necked flask. The flask was sealed, cooled with condenser, and protected with nitrogen. The reaction was carried out at 60 °C for 12 h. After cooling to room temperature, the acetone was removed, and the mixture was extracted with dichloromethane (50 mL × 3). The organic phase was washed three times with saturated sodium chloride solution, dried over anhydrous sodium sulfate, and the solid was purified by rotary evaporation. The solid was then passed through a silica gel column in dichloromethane to give 160 mg of compound 2, with a yield of 65%.

[0094] Compound 2 (2 g, 4.08 mmol), pinacol diborate (2.59 g, 10.2 mmol), 1,1'-bis(diphenylphosphine)ferrocene palladium dichloride (234 mg, 0.29 mmol), and methyl acetate (2.9 g, 30 mmol) were added to a 250 mL three-necked flask. The flask was sealed, cooled with condenser, and protected with nitrogen. 100 mL of anhydrous and oxygen-free 1,4-dioxane was then measured using a syringe. The mixture was reacted at 110 °C for 24 h. The resulting product was quenched with water and extracted with ethyl acetate (60 mL × 3). The resulting organic phase was washed three times with saturated sodium chloride solution, dried over anhydrous sodium sulfate, and the solid was purified by rotary evaporation. The solid was then passed through a silica gel column in dichloromethane to give 2.13 g of compound 3, with a yield of 89%.

[0095] Take a 50 mL reaction flask, add compound 3 (350 mg, 0.60 mmol), compound OPA (522.6 mg, 1.30 mmol), palladium acetate (6.7 mg, 0.03 mmol), phase transfer catalyst sphos (C AS:657408-07-6, 24.6 mg, 0.06 mmol), potassium phosphate (1.03 g, 4.8 mmol), nitrogen protection, condensation, inject 12 mL of 1,4-dioxane using a syringe, react at 100 °C for 24 h, extract with dichloromethane, wash with saturated brine, dry with anhydrous sodium sulfate, evaporate to dryness, pass the solid through a silica gel column, and elute with petroleum ether and ethyl acetate (volume ratio 4:1) to obtain 445.5 mg of compound BCzOPA, yield 76%; 1 HNMR(400MHz, CDCl3)δ8.29-8.10(m,4H),7.59-7.48(m,2H),7.38-7.28(m,4H),7.14-7.00(m,12 H), 6.93-6.87 (m, 2H), 6.81 (d, J = 9.0Hz, 8H), 6.57 (ddd, J = 15.7, 10.9, 2.3Hz, 4H), 3.78 (s, 12H).

[0096] Example 2

[0097] Compound 3 was prepared according to the method of Example 1;

[0098] Take a 50 mL reaction flask, add compound 3 (350 mg, 0.60 mmol), compound SPA (565 mg, 1.30 mmol), palladium acetate (6.7 mg, 0.03 mmol), phase transfer catalyst sphos (24.6 mg, 0.06 mmol), potassium phosphate (1.03 g, 4.8 mmol), nitrogen protection, condensation, inject 1,4-dioxane (12 mL) with a syringe, react at 100 °C for 24 h, extract with dichloromethane, wash with saturated brine, dry with anhydrous sodium sulfate, evaporate to dryness, pass the solid through a silica gel column, eluent with petroleum ether and ethyl acetate (4:1), to give compound BCzSPA 486 mg, yield 78%. 1 HNMR (400MHz, CDCl3) δ8.26-8.17(m,4H),7.54(d,J=8.1Hz,2H),7.38-7.31(m,4H),7.15(d,J=8.6Hz,10H ),7.08(s,2H),7.00(d,J=8.5Hz,8H),6.91(t,J=4.3Hz,2H),6.71(dd,J=13.5,10.7Hz,4H),2.45(s,12H).

[0099] Characterization and performance testing

[0100] 1) Figure 1 The image shows the 1H NMR spectrum of compound 2. Figure 2 The image shows the 1H NMR spectrum of compound 3. Figure 3 The 1H NMR spectrum of compound BCzOPA; Figure 4 The 1H NMR spectrum of compound BCzSPA; by Figures 1-4 It can be seen that the nitrogen-nitrogen coupling reaction catalyzed by potassium permanganate was successfully achieved, and the peripheral end capping groups were successfully coupled with the helical orthogonal core, resulting in a relatively pure target compound.

[0101] 2) The thermal stability of the hole transport materials prepared in Examples 1 and 2 was tested (nitrogen atmosphere, heating rate 10℃ / min, test temperature range: room temperature to 900℃). The obtained thermogravimetric curves are shown in the figure. Figure 5 ;Depend on Figure 5 It is known that the hole transport material prepared by this invention has good thermal stability and is suitable for use in optoelectronic semiconductor devices.

[0102] Application Example 1

[0103] according to Figure 6 The structure shown is used to fabricate a perovskite solar cell: (1) a transparent conductive substrate FTO; (2) a tin dioxide (SnO2) electron transport layer; and (3) a perovskite active layer (CsI). 0.05 (FAPbI3)0.79 (MAPbBr3) 0.16 (4) Hole transport layer; (5) Gold electrode;

[0104] 1) Cleaning the conductive substrate:

[0105] The etched conductive substrate was ultrasonically treated in cleaning agent, deionized water, anhydrous ethanol, acetone and isopropanol for 15 min in sequence, then removed and dried with nitrogen (N2), placed in an oven and dried at 120℃ for 8 h, and treated with ultraviolet / ozone for 30 min.

[0106] 3) Preparation of tin dioxide (SnO2) electron transport layer

[0107] Prepare a 0.1 mol / L stannous chloride (SnCl2·2H2O) ethanol solution, spin-coat the resulting solution onto a conductive substrate at 3000 rpm for 40 s, and anneal the resulting film in air at 180 °C for 1 h.

[0108] 4) Preparation of perovskite active layer

[0109] The perovskite solution was prepared by mixing FAI (1 mol / L), PbI2 (1.1 mol / L), MABr (0.2 mol / L), and PbBr2 (0.22 mol / L) in DMF:DMSO = 4:1 (v:v). The concentrations in parentheses represent the concentrations of each material in the mixed solvent. A two-step spin coating process was performed: 1000 rpm for 10 s and 6000 rpm for 20 s. With 5 seconds remaining, chlorobenzene was applied to the center of the substrate, and the film was annealed at 100 °C for 1 h.

[0110] 4) Fabrication of the hole transport layer

[0111] 30 mg of the hole transport material BCzOPA prepared in Example 1 was dissolved in 1 mL of chlorobenzene to obtain a hole transport layer solution, which was then dropped onto a perovskite film and spin-coated at 4000 rpm for 30 s and left in air for 12 h.

[0112] 5) Fabrication of gold electrodes

[0113] Gold electrodes were fabricated on the surface of the hole transport layer using a high-vacuum thermal evaporation method, at a depth of 1×10⁻⁶. -6 Under a vacuum of Pa, Gold electrodes were prepared by rate evaporation deposition, with the electrode thickness controlled to be 100 nm.

[0114] Application Example 2

[0115] The only difference from Application Example 1 is that the hole transport material BCzSPA prepared in Example 2 is used in step 4), otherwise it is the same as Application Example 1.

[0116] Performance testing

[0117] The effective area of ​​the planar heterojunction perovskite solar cells used in Examples 1 and 2 is 0.1 cm². 2 Test conditions: spectral distribution AM1.5G, illuminance 100mW / cm² 2 The AAA solar simulator (Beijing Zhuoli Hanguang Company) was used. The IV curve was measured using a Keithly 2400 digital source meter. The voltage test range for the IV curve was 0V-1.3V, and the scan rate was 0.1V / s. The results are shown below. Figure 7 , Figure 7 The data obtained from the IV curve are shown in Table 1.

[0118] Table 1. Device performance of perovskite solar cells fabricated in Application Examples 1-2

[0119]

[0120] From Table 1 and Figure 7 It is evident that perovskite solar cells based on the doped hole transport material of the present invention can achieve excellent device performance.

[0121] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A three-dimensional stacked, doped-free hole transport material, characterized in that, It has the structure shown in Equation I: In Equation I, R is or .

2. The preparation method of the three-dimensional stacked doped hole transport material according to claim 1, characterized in that, Includes the following steps: Compound 1 with the structure shown in Formula II, potassium permanganate and the first solvent were mixed and subjected to a nitrogen-nitrogen coupling reaction to obtain compound 2 with the structure shown in Formula III. Compound 2 with the structure shown in Formula III, pinacol diborate, 1,1'-bis(diphenylphosphine)ferrocene palladium dichloride, potassium acetate, and a second solvent were mixed and subjected to a Miyaura borylation reaction to obtain compound 3 with the structure shown in Formula IV. Compound 3 with the structure shown in Formula IV, the end-capping compound, palladium acetate, phase transfer catalyst, potassium phosphate, and a third solvent are mixed and end-capped to obtain a three-dimensional stacked doped-free hole transport material with the structure shown in Formula I; the phase transfer catalyst is sphos, XPhos, or Tbu3P. The terminating compound is: 。 3. The preparation method according to claim 2, characterized in that, The molar ratio of compound 1 with the structure shown in Formula II to potassium permanganate is 1:(1~5); the first solvent is acetone, tetrahydrofuran or 1,4-epoxyhexacyclohexane.

4. The preparation method according to claim 2, characterized in that, The nitrogen-nitrogen coupling reaction was carried out at a temperature of 60°C for 12 hours.

5. The preparation method according to claim 2, characterized in that, The molar ratio of compound 2 with the structure shown in Formula III, pinacol diborate, 1,1'-bis(diphenylphosphine)ferrocene palladium dichloride, and potassium acetate is 4.08:10.2:0.29:

30.

6. The preparation method according to claim 2, characterized in that, The Miyaura borylation reaction is carried out at a temperature of 60~120℃ for a time of 12~36h.

7. The preparation method according to claim 2, characterized in that, The molar ratio of compound 3 with the structure shown in Formula IV, the end-capping compound, palladium acetate, the phase transfer catalyst, and potassium phosphate is 0.60:1.30:0.03:0.06:4.

8.

8. The preparation method according to claim 2, characterized in that, The sealing temperature is 100℃, and the time is 12~36h.

9. The application of the three-dimensional stacked doped hole transport material of claim 1 or the three-dimensional stacked doped hole transport material prepared by the preparation method of any one of claims 2 to 8 in perovskite solar cells.

10. A perovskite solar cell, characterized by, It includes a conductive substrate, an electron transport layer, a perovskite active layer, a hole transport layer, and a metal electrode stacked sequentially; the hole transport material used in the hole transport layer is the three-dimensional stacked doped hole transport material of claim 1 or the three-dimensional stacked doped hole transport material prepared by the preparation method of any one of claims 2 to 8.

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