Hole transport material, preparation method thereof, and perovskite solar cell

Abstract

The present invention discloses a hole transport material, a preparation method thereof, and a perovskite solar cell, belonging to the technical field of photovoltaic solar energy materials. A compound, the molecular structure of which is shown in formula (I) or formula (II). The present invention uses a quinoxaline moiety as an electron acceptor for extended conjugation modification, introduces multiple triphenylamine electron-donating groups, dihydroacenaphthene, dinaphthyloxy and other single donors, and constructs a hole transport material with a multi-donor structure. This hole transport material regulates the distribution of HOMO-LUMO, increases the charge transfer channel, improves the charge separation and transport capabilities, and thus improves the carrier mobility. Further, a tert-butyl unit is introduced outside the triphenylamine group. The hydrophobic properties of the tert-butyl group reduce the interfacial energy barrier between the hole transport layer and the perovskite precursor solution, promote the directional growth and defect passivation of the perovskite crystal, and improve the crystallization quality and device performance of the perovskite film.

Description

Technical Field

[0001] The present invention belongs to the technical field of photovoltaic solar materials, and in particular relates to a hole transport material and a preparation method thereof, and a perovskite solar cell. Background Art

[0002] Against the backdrop of the deep integration of new energy and semiconductor technologies, perovskite materials, as the core of third-generation semiconductor technology, have become a research hotspot in the photovoltaic field due to their unique organic-inorganic hybrid semiconductor properties (band gap tunable range of 1.2-2.3 eV and long exciton diffusion length). New energy industries (such as solar power generation) are increasingly in need of high-efficiency, low-cost semiconductor devices. Perovskite semiconductor materials, with their low-temperature solution-based fabrication process (<150°C) and high theoretical photoelectric conversion efficiency of 33% (significantly exceeding the 29.4% limit of crystalline silicon semiconductors), can significantly reduce the levelized cost of electricity (LCOE) of photovoltaic power generation by over 40%, and are considered a key path to breaking through the bottlenecks of traditional silicon-based semiconductor photovoltaic technology.

[0003] However, in the large-scale application of new energy, the rapid development of perovskites is also inseparable from the support of hole transport materials. Among them, the hole transport layer plays a vital role in the extraction and transport of holes, and hole transport materials are the main components of the hole transport layer. The most commonly used high-efficiency hole transport materials are spiro-OMeTAD and PTAA. Existing hole transport materials have problems such as poor wettability with perovskite precursor solutions and easy crystallization of molecules, which easily lead to poor morphology of perovskite films. In addition, the strong electron-absorbing ability of the acceptor and the mismatch between the donor and acceptor energy levels, as well as the high price of the materials, are also the reasons that hinder their commercial application. Summary of the Invention

[0004] In order to solve the problems existing in the above-mentioned prior art, the purpose of the present invention is to provide a compound.

[0005] Another object of the present invention is to provide use of the above compound as a hole transport material.

[0006] Another object of the present invention is to provide a hole transport material.

[0007] Another object of the present invention is to provide a hole transport layer.

[0008] Another object of the present invention is to provide a perovskite solar cell.

[0009] Another object of the present invention is to provide an application of the above-mentioned perovskite solar cell in the preparation of photovoltaic power generation equipment.

[0010] In order to achieve the above object, the present invention provides the following technical solutions:

[0011] A compound, the molecular structure of which is shown in formula (I) or formula (II):

[0012]

[0013] Formula (I)

[0014]

[0015] Formula (II).

[0016] This invention, based on the quinoxaline system, undergoes extended conjugation modification using the quinoxaline moiety as an electron acceptor. Single donors, such as triphenylamine, dihydroacenaphthyl, and binaphthyloxy, are introduced to create a multi-donor structure. This enhances intermolecular interactions, increases charge transfer channels, and modulates the HOMO-LUMO distribution. The two cyano groups (-C≡N) at the molecular termini are strong electron-withdrawing groups, attracting electrons through an inductive effect. The donor steric hindrance and intramolecular hydrogen bonding impart varying degrees of rigidity to the molecule, reducing bond rotation and vibration and inhibiting molecular relaxation. The rigid plane of the molecular acceptor helps reduce nonradiative transitions, achieve a deep LOMO level, and improve hole migration efficiency.

[0017] The present invention also protects the use of the above compound as a hole transport material.

[0018] Preferably, the molecular structural formula of the compound is:

[0019]

[0020] Formula (I).

[0021] Further introduction of tert-butyl units around the triphenylamine group provides good solubility for the hole transport material, which is beneficial to the spreading of the hole material and the coating of the perovskite precursor solution, improves the crystallization quality of the perovskite layer, and can also maintain a synergistic electron-donating and electron-withdrawing effect with the cyanide group.

[0022] A hole transport material comprising a compound of the following molecular formula:

[0023]

[0024] Formula (I)

[0025]

[0026] Formula (II).

[0027] A hole transport layer comprising a compound of the following molecular formula:

[0028]

[0029] Formula (I)

[0030]

[0031] Formula (II).

[0032] The present invention protects the use of the above hole transport material in the preparation of perovskite solar cells.

[0033] A perovskite solar cell comprises, from bottom to top, a conductive glass layer, a hole transport layer, a perovskite layer, an electron transport layer and an electrode layer, wherein the hole transport layer comprises the above-mentioned compound or the above-mentioned hole transport material.

[0034] Specifically, the hole transport layer further includes NiO x , PTAA, MeO-2PACz, Me-2PACz.

[0035] Preferably, the hole transport layer includes a first hole transport layer and a second hole transport layer in order from bottom to top, and the second hole transport layer includes the above compound or the above hole transport material.

[0036] Specifically, the hole transport layer is prepared from the above compound or a solution of the above hole transport material.

[0037] More specifically, in the solution, the concentration of the compound or the hole transport material is 0.1-0.3 mg / ml.

[0038] Preferably, in the solution, the concentration of the compound or the hole transport material is 0.1 mg / ml.

[0039] More specifically, the solvent in the solution is one or more of DMF, DMSO, THF, acetone, isopropanol, toluene or chlorobenzene.

[0040] Specifically, the method for preparing the hole transport layer is as follows: spin coating a solution containing the above compound or the above hole transport material on the surface of the conductive glass, and heating and annealing to obtain the hole transport layer.

[0041] More preferably, the mass ratio of the first hole transport layer to the second hole transport layer is (100-150):(1-10).

[0042] More preferably, the preparation method of the second hole transport layer is specifically: spin coating a solution containing the above compound or the above hole transport material on the first hole transport layer, heating and annealing, to obtain the second hole transport layer.

[0043] More preferably, the first hole transport layer is NiO x .

[0044] More preferably, the spin coating speed is 3000-5000 rpm.

[0045] More preferably, the spin coating time is 25 to 45 seconds.

[0046] More preferably, the heating annealing temperature is 100-180°C.

[0047] More preferably, the heating annealing time is 10 to 50 minutes.

[0048] Specifically, the conductive glass layer is one of ITO conductive glass and FTO conductive glass.

[0049] Specifically, the perovskite layer includes formamidine hydrohalide, alkylammonium halide, cesium halide and lead halide.

[0050] More specifically, the formamidine halide salt is at least one of formamidine hydrochloride, formamidine bromide, and formamidine iodate.

[0051] More specifically, the alkylammonium halide is at least one of methylammonium iodide, methylammonium chloride, and methylammonium bromide.

[0052] More specifically, the cesium halide is at least one of cesium iodide, cesium chloride or cesium bromide.

[0053] More specifically, the lead halide is at least one of lead iodide, lead chloride or lead bromide.

[0054] Preferably, the perovskite layer comprises formamidine hydroiodide, methylammonium chloride, methylammonium iodide, cesium iodide and lead iodide.

[0055] Specifically, the method for preparing the perovskite layer is as follows: spin-coating a perovskite solution prepared from the materials of the perovskite layer on the surface of the hole transport layer to obtain the perovskite layer.

[0056] Specifically, the material of the electron transport layer is a carbon 60 derivative.

[0057] More specifically, the C60 derivative is at least one of [6,6]-phenyl C61 butyric acid methyl ester, [6,6]-thienyl C61 butyric acid methyl ester, [6,6]-phenyl-C61-butyric acid n-octyl ester or [6,6]-phenyl-C61-butyric acid dodecyl ester.

[0058] Preferably, the material of the electron transport layer is [6,6]-phenyl C61 butyric acid methyl ester.

[0059] Specifically, the electrode layer is one or more of Pt, Au, Ni, Cu, Ag, In, Ru, Pd, Rh, Ir, Os, C and a conductive polymer.

[0060] Preferably, the electrode layer is Ag.

[0061] The present invention also protects the use of the above-mentioned perovskite solar cell in the preparation of photovoltaic power generation equipment.

[0062] Compared with the prior art, the present invention has the following beneficial effects:

[0063] This invention uses the quinoxaline moiety as an electron acceptor and undergoes extended conjugation modification, introducing multiple triphenylamine electron-donating groups, dihydroacenaphthylene, and binaphthyloxy groups as single donors to construct a multi-donor hole transport material. This hole transport material modulates the HOMO-LUMO distribution, increases charge transfer channels, and enhances charge separation and transport capabilities, thereby improving carrier mobility. Furthermore, the introduction of tert-butyl units around the triphenylamine groups significantly improves the hole transport material's solubility in organic solvents, making the solution easier to spread evenly into a film. Furthermore, the hydrophobic nature of the tert-butyl groups reduces the interfacial energy barrier between the hole transport layer and the perovskite precursor solution, promoting the directional growth of perovskite crystals and defect passivation, thereby improving the crystallization quality and device performance of the perovskite film. BRIEF DESCRIPTION OF THE DRAWINGS

[0064] Figure 1 This is the hydrogen nuclear magnetic resonance spectrum of Example 1.

[0065] Figure 2 This is the hydrogen nuclear magnetic resonance spectrum of Example 2.

[0066] Figure 3 JV curves of the perovskite solar cells of Examples 3 to 6 and Comparative Examples 1 and 2.

[0067] Figure 4 Steady-state photoluminescence (PL) spectra of the perovskite layers of Examples 3 and 6 and Comparative Examples 1 and 2.

[0068] Figure 5 Time-resolved steady-state photoluminescence (TRPL) spectra of the perovskite layers of Examples 3 and 6 and Comparative Examples 1 and 2.

[0069] Figure 6 2 are XRD patterns of the perovskite layers of Example 3 and Comparative Example 1.

[0070] Figure 7 The synthetic route diagram of Example 1 is shown in FIG. DETAILED DESCRIPTION

[0071] The present invention is further described below with reference to the examples. These examples are intended to illustrate the present invention only and are not intended to limit the scope of the present invention. Experimental methods in the following examples where specific conditions are not specified are generally performed in accordance with conventional conditions in the art or the conditions recommended by the manufacturer; the raw materials and reagents used, unless otherwise specified, are all commercially available from conventional markets. Any non-substantial changes and substitutions made by those skilled in the art based on the present invention fall within the scope of protection claimed in the present invention.

[0072] Example 1

[0073] This embodiment provides a compound or a hole transport material, the molecular structure of which is:

[0074]

[0075] Formula (I).

[0076] The synthetic routes of the above compounds are as follows Figure 7 shown.

[0077] The preparation method of the above compound comprises the following steps:

[0078] S1: Preparation of 1,4-dibromo-2,3-difluoro-5,6-dinitrobenzene:

[0079] Place a three-necked flask (250 mL), a spherical condenser, a normal pressure dropping funnel, a glass stopper, and a stirrer in an oven and dry at 100°C for 30 min. Remove the dried three-necked flask and dropwise add 50 mL of trifluoromethanesulfonic acid, then slowly add 2.5 mL of nitric acid and stir in an ice bath for 30 min. Then, add 5 g of 1,4-dibromo-2,3-difluorobenzene (18.4 mmol) over 30 min. Stir at room temperature for 2 h, then cool the mixture to 0°C, slowly add 2.5 mL of nitric acid, heat to 70°C, and react for 30 h. Finally, adjust the pH to neutral by adding sodium hydroxide in an ice bath. Filter and collect the resulting light yellow solid, 4.2 g (yield 68%).

[0080] The molar ratio of 1,4-dibromo-2,3-difluorobenzene, nitric acid and trifluoromethanesulfonic acid is 1:8:50.

[0081] S2: Preparation of 3,6-dibromo-4,5-difluoro-1,2-phenylenediamine:

[0082] 1,4-Dibromo-2,3-difluoro-5,6-dinitrobenzene (3 g) and iron powder (7.8 g) were added to a 250 mL two-necked round-bottom flask and evacuated with nitrogen. Then, acetic acid (70 mL) was added and the temperature was raised to 45°C while stirring. The reaction was carried out for 6 h, cooled to room temperature, and the reaction solution was poured into a 5 wt% NaOH solution (180 mL). The mixture was extracted three times with ethyl acetate. Finally, the ethyl acetate layer was washed with a saturated sodium bicarbonate solution and dried over anhydrous sodium sulfate. The ethyl acetate was removed by distillation under reduced pressure to obtain a black solid. The black solid was washed three times with petroleum ether and filtered to obtain a black residue with a mass of 1.9 g (yield 87%).

[0083] The molar ratio of 1,4-dibromo-2,3-difluoro-5,6-dinitrobenzene, iron powder and glacial acetic acid is 1:15:150.

[0084] S3. Preparation of formula (IV):

[0085] 3,6-Dibromo-4,5-difluoro-1,2-phenylenediamine (0.265 g), 1,2-dioxo-acenaphthene-5,6-dicarbonitrile (0.232 g), and acetic acid (12 mL) were added to a 50 mL round-bottom flask and reacted at 120°C under nitrogen for 12 h. After cooling, the mixture was poured into water and vacuum filtered to obtain the crude product. The residue was then washed with ethanol to obtain 0.31 g (yield 67%) of the compound (IV) as a solid.

[0086] The molar ratio of 1,2-dioxo-acenaphthene-5,6-dicarbonitrile and 3,6-dibromo-4,5-difluoro-1,2-phenylenediamine is 1:1.

[0087] S4. Preparation of formula (V):

[0088] The compound of formula (IV) (0.5 g), [1,1'-binaphthyl]-2,2'-diol (0.25 g) and potassium carbonate (0.3 g) were added to a 100 mL double-necked round-bottom flask, and 50 mL of dimethyl sulfoxide was added. The mixture was stirred and heated to 140°C for 12 h. After the reaction, the reaction solution was poured into 200 mL of water, and then extracted three times with dichloromethane. The organic phase was collected. The dichloromethane in the organic phase was removed by vacuum distillation, and finally silica gel column chromatography was performed using dichloromethane and petroleum ether as developing solvents to obtain a solid compound of formula (V), which had a mass of 0.4 g (yield 62%).

[0089] The molar ratio of the compound of formula (IV), potassium carbonate and the donor group [1,1'-binaphthyl]-2,2'-diol is 1:40:3.

[0090] S5. Preparation of the above compound:

[0091] 4',4'-di-tert-butyl-4-boronic acid pinacol ester triphenylamine (0.665 g), the compound of formula (V) (0.462 g), K2CO3 (0.635 g), Pd(PPh3)4 (115 mg), and 50 mL of toluene / H2O / ethanol (mass ratio 4:2:1) were added to a three-necked flask (250 mL) under nitrogen. The mixture was then stirred at 110 °C for 16 h. After the reaction was complete, distilled water was poured into the mixture and extracted three times with CH2Cl2 (50 mL x 3). The organic solvent was removed under reduced pressure, and the crude product was purified by silica gel column chromatography using CH2Cl2 / petroleum ether (5:1, v:v) as the eluent. The product was further purified by sublimation to obtain the aforementioned compound (0.56 g, 70%). 1 H NMR (400 MHz, CDCl3) δ 8.41 (d, J = 7.3 Hz, 2H), 8.32 (d, J = 7.3 Hz, 2H), 7.97 (s, 2H), 7.74 (d, J = 8.6 Hz, 4H), 7.33 (t, J = 7.8 Hz, 8H), 7.25(d, J = 7.7 Hz, 12H), 7.09 (t, J = 7.3 Hz, 4H). Anal. Calcd for C 92 H 76 N6O2: C, 85.15; H, 5.90; N, 6.48; O, 2.47.

[0092] Specific nuclear magnetic resonance hydrogen spectrum is as follows Figure 1 shown.

[0093] The molar ratio of the compound of formula (V), K2CO3, palladium-containing coupling agent and 4'.4'-di-tert-butyl-4-boronic acid pinacol ester triphenylamine is 1:40:0.12:2.3.

[0094] Example 2

[0095] This embodiment provides a compound or a hole transport material, the molecular structure of which is:

[0096]

[0097] Formula (II).

[0098] Steps S1 to S4 in the preparation method of the above compound are the same as those in Example 1, except that:

[0099] S5. 4-Pinacol boronic acid triphenylamine (0.61 g), the compound of formula (V) (0.462 g), K2CO3 (0.635 g), Pd(PPh3)4 (115 mg), and 50 mL of toluene / H2O / ethanol (4:2:1) were added to a three-necked flask (250 mL) under nitrogen. The mixture was then stirred at 110°C for 16 h. After the reaction was complete, distilled water was poured into the mixture and extracted three times with CH2Cl2 (50 mL x 3). The organic solvent was removed under reduced pressure, and the crude product was purified by silica gel column chromatography using CH2Cl2 / petroleum ether (5:1, v:v) as the eluent. The product was further purified by sublimation to obtain the aforementioned compound (0.53 g, 65%). 1 H NMR (400 MHz, Chloroform-d) δ 8.32 (d, J = 7.3 Hz, 2H), 8.25 (dd, J = 7.4, 1.4 Hz, 2H), 7.92 (dd, J = 8.7, 2.9 Hz, 4H), 7.58 (d, J = 8.5 Hz, 2H), 7.52 (d, J = 8.3Hz, 4H), 7.49 – 7.44 (m, 3H), 7.37 (dd, J = 8.4, 6.8 Hz, 3H), 7.27 – 7.23 (m,7H), 7.22 – 7.16 (m, 15H), 7.03 (td, J = 7.2, 1.4 Hz, 5H). Anal. Calcd forC 76 H 44 N6O2: C, 85.06; H, 4.13; N, 7.83; O, 2.98.

[0100] Specific nuclear magnetic resonance hydrogen spectrum is as follows Figure 2 shown.

[0101] Example 3

[0102] This embodiment provides a perovskite solar cell, using the compound in Example 1 as a hole transport material, and the hole transport layer includes the compound in Example 1. The preparation method thereof includes the following steps:

[0103] S1: The ITO conductive glass substrate was cleaned with detergent and deionized water, dried, and then treated with UV ozone for 15 minutes. After the treatment, 40 μL 15 mg / mL NiO was spin-coated on the surface of the conductive glass layer in air. x The solution was spin-coated at a speed of 4000 rpm for 30 seconds. After spin coating, the solution was transferred to a heating platform and heated at 150°C for 30 minutes to obtain the first hole transport layer.

[0104] S2: Dissolve the compound from Example 1 as a hole transport material in isopropanol to obtain a 0.1 mg / mL solution. In a nitrogen-filled glove box, add 40 μL of this 0.1 mg / mL solution dropwise onto the first hole transport layer and spin-coat at 4000 rpm for 30 seconds. Then, transfer the sample to a heating plate and heat-anneal at 100°C for 10 minutes to obtain the second hole transport layer.

[0105] S3: Dissolve formamidine hydroiodide, methylammonium chloride, methylammonium iodide, cesium iodide, and lead iodide in DMF and DMSO to obtain a perovskite solution. In a nitrogen-filled glove box, spin-coat 68 μL of the perovskite solution onto the second hole transport layer at 1000 rpm for 10 seconds, then at 5000 rpm for 30 seconds. Chlorobenzene is added dropwise during the remaining 10 seconds. The layer is then transferred to a heating plate and heated at 100°C for 30 minutes to obtain the perovskite layer.

[0106] S4: In a nitrogen atmosphere glove box, 23 mg of the electron transport layer material [6,6]-phenyl C61 butyric acid methyl ester (PC61BM) was dissolved in 1 mL of chlorobenzene to prepare a PC61BM electron transport layer solution, and 28 μL of the PC61BM electron transport layer solution was spin-coated on the surface of the perovskite modified layer at a spin-coating speed of 3000 rpm for 30 s. After the spin-coating, the layer was transferred to a heating table and heated at 65°C for 10 min. Subsequently, 35 μL of 2.5 mg / mL bathocuproine (BCP) was spin-coated at a spin-coating speed of 5000 rpm for 30 s to obtain the electron transport layer.

[0107] S5: Place the device coated with the electron transport layer into a vacuum coating machine, evacuate the vacuum, place the silver metal source into a tungsten boat, and evaporate the silver electrode to obtain a perovskite solar cell.

[0108] Example 4

[0109] This example provides a perovskite solar cell, which differs from Example 3 in that: S2: The compound of Example 1 was dissolved in isopropanol as a hole transport material to obtain a 0.2 mg / mL solution. In a nitrogen-filled glove box, 40 μL of the 0.2 mg / mL solution was dropwise added onto the first hole transport layer. The remainder of the process was the same as in Example 3.

[0110] Example 5

[0111] This example provides a perovskite solar cell, which differs from Example 3 in that: S2: The compound of Example 1 was dissolved in isopropanol as a hole transport material to obtain a 0.3 mg / mL solution. In a nitrogen-filled glove box, 40 μL of the 0.3 mg / mL solution was dropwise added onto the first hole transport layer. The remainder of the process was the same as in Example 3.

[0112] Example 6

[0113] This example provides a perovskite solar cell. This differs from Example 3 in that, in step S2, the compound of Example 2 was dissolved in isopropanol as a hole transport material to obtain a 0.1 mg / mL solution. In a nitrogen-filled glove box, 40 μL of the 0.1 mg / mL solution was dropwise added onto the first hole transport layer. The remainder of the process was the same as in Example 3.

[0114] Comparative Example 1

[0115] This comparative example provides a perovskite solar cell, which differs from Example 3 in that the hole transport layer does not include the compound of Example 1 (i.e., there is no second hole transport layer). Step S2 is omitted from the preparation method, and the rest is the same as Example 3.

[0116] Comparative Example 2

[0117] This comparative example provides a perovskite solar cell, wherein the hole transport layer comprises a diazine benzofluoranthene compound represented by the following formula (III):

[0118]

[0119] Formula (III).

[0120] The preparation method thereof is different from that of Example 3 in that the compound of Example 1 is replaced by the diazobenzene fluoranthene compound. The rest is the same as that of Example 3.

[0121] Performance Testing

[0122] 1 HNMR test: measured using a Bruker-400 nuclear magnetic resonance spectrometer, with deuterated chloroform as the solvent;

[0123] Current density-voltage (JV) characteristic curve test: The performance of the device is evaluated by measuring the JV characteristic curve. The experiment uses a solar simulator to provide AM 1.5G, 100 mWcm -2 The JV characteristic curve can be obtained by applying a bias voltage to the two ends of the test cell and measuring the current of its external circuit using a Keithley 2400C digital source meter. The effective area of ​​the device is 0.04cm 2 .

[0124] Steady-state fluorescence emission (PL) spectral characterization testing: Fluorescence emission characterization uses a quartz or glass substrate to prepare the sample. The test sample is spin-coated with a perovskite layer on transparent conductive glass to create a complete sample. Steady-state PL testing uses a xenon lamp as the excitation light source. Transient PL testing uses a different excitation light source. A biexponential fitting method is used to fit the transient PL lifetime, ensuring that the fitting exponent χ is 1 / 4 of the original value. 2 The test structure of Examples 3 to 6 is ITO / NiO x / hole transport material / perovskite layer, the test structure of comparative example 1 is ITO / NiO x / Perovskite layer.

[0125] X-ray diffraction (XRD) characterization: Fluorescence emission characterization uses a quartz or glass substrate as the sample preparation. A hole transport layer is applied to a transparent conductive glass substrate, followed by spin coating of the perovskite layer to create a complete sample. The scanning angle ranges from 10 to 45°.

[0126] Figure 3 The JV curves of the perovskite solar cells of the embodiment and the comparative example are shown in Table 1.

[0127] Table 1 JV test results of perovskite solar cells of Example and Comparative Example

[0128]

[0129] As can be seen from Table 1, the photoelectric conversion efficiency of the perovskite solar cell device using the hole transport material provided by Example 1 or 2 as the hole transport layer of the perovskite solar cell is generally better than that of the perovskite solar cell device without the addition of the hole transport material (i.e., Comparative Example 1), and is also better than the perovskite solar cell device using the diazolobenzofluoranthene compound as the hole transport material (i.e., Comparative Example 2). This shows that the hole transport material provided by the present invention plays a role in promoting carrier transport and has a significant effect on improving the photoelectric conversion efficiency of the perovskite device.

[0130] Figure 4 Steady-state photoluminescence (PL) spectra of the perovskite layers of Examples 3 and 6 and Comparative Examples 1 and 2 are shown. As can be seen, the peak fluorescence intensity of Examples 3 and 6 is lower than that of Comparative Examples 1 and 2. This decrease in fluorescence intensity indicates a reduction in non-radiative recombination of photogenerated carriers in the perovskite layer. The hole transport material provided in Example 1 was introduced into the HTL, optimizing the energy level match between this hole transport material and the perovskite, forming a more efficient charge transfer channel. This effectively facilitates the rapid extraction of holes from the perovskite layer to the electrode and reduces carrier accumulation and recombination within the perovskite.

[0131] Figure 4The time-resolved photoluminescence (TRPL) spectra of the perovskite layers of Examples 3 and 6 and Comparative Examples 1 and 2 are shown. As can be seen from the figure, the fluorescence lifetime curves of the perovskite layers of Examples 3 and 6 are lower than those of Comparative Examples 1 and 2, indicating that the average carrier lifetime of the perovskite films in Examples 3 and 6 is shortened. This is because the hole transport material provided in Example 1 as the hole transport layer of the perovskite solar cell can improve the hole migration efficiency and effectively reduce the non-radiative recombination and loss of photogenerated carriers.

[0132] Table 2 Double exponential fitting results of TRPL spectra of Examples 3, 6 and Comparative Examples 1, 2

[0133]

[0134] The TRPL spectrum was fitted to calculate the ITO / NiO x The hole mobility and diffusion length of the hole transport material perovskite layer structure are shown in Table 3.

[0135] Table 3 Charge diffusion length and mobility results of Examples 3, 6 and Comparative Examples 1, 2

[0136]

[0137] TRPL analysis can reveal the carrier recombination rate and dominant mechanism by analyzing the decay behavior of the photoluminescence intensity over time. The fitting results are shown in Table 2. As shown in Table 2, the average carrier lifetimes of the perovskite films of Comparative Examples 1 and 2 are 196.35 ns and 193.19 ns, respectively, while the average carrier lifetimes of the perovskite films of Examples 6 and 3 are 150.39 ns and 110.45 ns, respectively. τ1 represents the dominant process of surface / grain boundary recombination. The τ1 of Comparative Example 1 is 36.48 ns, the τ1 of Comparative Example 2 is 39.83 ns, and the τ1 of Example 3 is extended to 43.77 ns, indicating that the hole transport material provided by the present invention improves the surface recombination lifetime. τ2 represents the bulk phase recombination process. The τ2 of comparative example 1 is 210.21 ns, the τ2 of comparative example 2 is 196.48 ns, and the τ2 of embodiment 3 decreases to 127.90 ns. The bulk phase lifetime decreases but the surface lifetime increases, indicating that the bulk phase defects are greatly reduced after the surface optimization of this hole transport material.

[0138] From Table 3, we can see that the hole mobility of the perovskite films of Comparative Example 1 and Comparative Example 2 is 27.27 cm 2 V -1 s -1 and 27.89 cm 2 V -1 s -1The lifetimes of the perovskite films of Example 6 and Example 3 are 38.90 cm 2 V -1 s -1 and 56.88cm 2 V -1 s -1 , which shows that compared with Comparative Examples 1 and 2, the hole transport materials of Examples 3 and 6 not only optimize the molecular stacking, but also reduce the transport barrier through energy level matching (HOMO is aligned with the perovskite valence band), optimize the transport path, and achieve efficient carrier transport.

[0139] Figure 5 The XRD patterns of Example 3 and Comparative Example 1 are shown. In the XRD patterns, the diffraction peak at 14.4° represents the (110) crystal plane of the perovskite. As can be seen from the figure, the diffraction angle of Example 3 did not change significantly, indicating that the hole transport material provided in Example 1 did not change the perovskite structure. Compared with Comparative Example 1, the diffraction peak intensity corresponding to the (110) crystal plane of Example 3 increased, indicating that the hole transport material provided in Example 1, as a hole transport layer, enhanced the preferential orientation of the perovskite grains and improved the crystallization quality of the perovskite layer.

[0140] Obviously, the above embodiments of the present invention are merely examples for the purpose of clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. Those skilled in the art will appreciate that other variations or modifications can be made based on the above description. It is not necessary and impossible to enumerate all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the claims of the present invention.

Claims

1. A compound, characterized in that The molecular structure of the compound is shown in formula (I) or formula (II): Formula (I) Formula (II).

2. Use of the compound according to claim 1 as a hole transport material.

3. The application according to claim 2, characterized in that: The molecular structural formula of the compound is: Formula (I).

4. A hole transport material, characterized in that Including compounds with the following molecular formula: Formula (I) Formula (II).

5. A hole transport layer, characterized in that: Including compounds with the following molecular formula: Formula (I) Formula (II).

6. A perovskite solar cell comprising, from bottom to top, a conductive glass layer, a hole transport layer, a perovskite layer, an electron transport layer, and an electrode layer, characterized in that: The hole transport layer comprises the compound according to claim 1 or the hole transport material according to claim 4.

7. The perovskite solar cell according to claim 6, characterized in that: The hole transport layer includes a first hole transport layer and a second hole transport layer in order from bottom to top, and the second hole transport layer includes the compound according to claim 1 or the hole transport material according to claim 4.

8. The perovskite solar cell according to claim 6, characterized in that: The hole transport layer is prepared from the compound according to claim 1 or the solution of the hole transport material according to claim 4.

9. The perovskite solar cell according to claim 8, characterized in that: In the solution, the concentration of the compound according to claim 1 or the hole transport material according to claim 4 is 0.1-0.3 mg / ml.

10. Use of the perovskite solar cell according to any one of claims 6 to 9 in the preparation of photovoltaic power generation equipment.

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