Conjugated polymer materials containing helicene in the main chain and their applications in optoelectronic devices

Abstract

The present invention relates to conjugated polymer material technology, and aims to provide a conjugated polymer material containing helicene in the main chain and its application in optoelectronic devices. The preparation method includes: adding dibromo-substituted helicene, 3,7-bis(3,4-ethylenedioxythiophene-5-yl)-10-(2-octyldodecyl)-10H-phenoxazine, palladium acetate, tricyclohexylphosphine tetrafluoroborate, and potassium carbonate to N,N-dimethylacetamide; under argon protection, heating to 130°C while stirring, reacting for 3 hours; standing and cooling to room temperature, filtering out the organic solvent to obtain a crude product; then separating and purifying by column chromatography to obtain a conjugated polymer material containing helicene in the main chain. The conjugated polymer material has properties such as a high HOMO energy level, a high glass transition temperature, high electrical conductivity, a high hole mobility, and solution processability, and can be used as a hole transport layer to prepare a perovskite solar cell with high energy conversion efficiency and good thermal stability. For example, as a hole transport layer of a perovskite solar cell, the energy conversion efficiency of the device can be improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of conjugated polymer materials, and more specifically relates to several conjugated polymer materials containing helicene in the main chain. The conjugated polymer materials have high glass transition temperature, high electrical conductivity and hole mobility, and can be used for preparing photoelectric devices. Background Art

[0002] As the leader in third-generation solar cell technology, the energy conversion efficiency of single-junction devices of perovskite solar cells has exceeded 25.7%. However, the long-term tolerance of perovskite solar cells in high temperature and humid environments remains a major difficulty in their practical application. The high sensitivity of organic-inorganic hybrid perovskites to heat and humidity is an important source of cell degradation. Through various methods such as component engineering and interface engineering, the stability of perovskite solar cells can be improved to a certain extent. In addition, the hole transport layer plays an important role in high-performance perovskite solar cells. It not only needs to quickly extract the photogenerated holes generated from the perovskite layer and transport them to the metal electrode, but also needs to inhibit the diffusion of permeable substances inside and outside, thereby protecting the perovskite layer.

[0003] Among various organic semiconductors, 2,2′,7,7′-tetrakis(N,N-di-p-methoxyaniline)-9,9′-spirobifluorene (spiro-OMeTAD) is the most commonly used small molecule hole transport material and has been used many times as the hole transport layer to create record efficiency devices for perovskite solar cells. For spiro-OMeTAD films, their intrinsic hole concentration and mobility are not high enough, and they must be increased through oxidative doping. However, the glass transition temperature of spiro-OMeTAD is low, which is further reduced after doping, resulting in severe degradation of the device performance at 85°C. Interestingly, for poly(3-hexylthiophene) (P3HT), which has a shallow highest occupied molecular orbital (HOMO) energy level, unintentional air doping actually exhibits a fairly high hole density and conductivity (10-30μS cm -1 However, the glass transition temperature of P3HT is very low, only 38°C, and the thermal stability of P3HT-based perovskite solar cells has not yet been reported. Another commonly used polymer semiconductor material in the hole transport layer of perovskite solar cells is poly(bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA). Due to its deeper HOMO energy level, it faces challenges in achieving sufficient conductivity through air doping and rapid hole extraction, and its energy conversion efficiency is lower than that of spiro-OMeTAD.

[0004] For perovskite solar cells that utilize oxide electron transport layers (such as TiO2 or SnO2), designing organic semiconductors with sufficiently high HOMO energy levels is crucial to ensure efficient hole extraction within the device. An ideal hole transport layer should also have good film-forming ability, hole conduction, resistance to morphological degradation under heating, and effective mitigation of internal and external species diffusion. Compared with small molecule organic semiconductors, polymer semiconductors with molecular weights in the range of 10 4 to 10 7 The extended main chain of the polymer exhibits a random conformation and chain entanglement occurs. In addition to exhibiting typical elastic deformation, the polymer material also exhibits high elastic deformation when heated above its glass transition temperature, resulting in films with enhanced mechanical strength and improved fracture resistance. In 2015, Yang et al. used PTAA as a hole transport layer in perovskite solar cells and achieved an energy conversion efficiency of 20.2%. In 2016, Kim et al. prepared a conjugated polymer RCP containing benzodithiophene and benzothiadiazole units. The device achieved an energy conversion efficiency of 17.3% and had an efficiency retention rate of nearly 100% after storage at 75% humidity and room temperature for 1400 hours. In 2018, Kim et al. reported several fluorinated polytriarylamine materials and found that fluorination significantly affected the polymer's HOMO energy level and cell performance. PTAA substituted with a single fluorine atom achieved an energy conversion efficiency of 21.2%. In 2022, Huang et al. linked benzodithiophene and dithiophene imide units via thiophene to form the polymer PFDTI. They were able to fabricate a device with an energy conversion efficiency of 23.1%. The device retained 80% efficiency after 500 hours of storage at room temperature and 40% humidity. In the same year, Liu et al. systematically studied the conjugated polymers PTB7, PTB7-Th, PBDB-T, and PM6, achieving energy conversion efficiencies of 18.9%, 19.6%, 22.5%, and 24.0%, respectively. The optimized PM6 device retained 89% efficiency after 1632 hours of storage at room temperature and 30±5% humidity. Despite exhaustive experiments with various polymer semiconductors in perovskite solar cells, none has yet achieved both an energy conversion efficiency exceeding 24% and durability at 85°C.

[0005] Based on the above situation, a new conjugated polymer material with high glass transition temperature, high conductivity and high hole mobility is proposed, which meets the actual needs for improving the performance of optoelectronic devices. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to overcome the deficiencies in the prior art and provide several conjugated polymer materials containing helicene in the main chain. The several conjugated polymer materials containing helicene in the main chain provided by the present invention have properties such as a high HOMO energy level, a high glass transition temperature, a high electrical conductivity, a high hole mobility, and solution processability. They can be used as hole transport layers to prepare perovskite solar cells with high energy conversion efficiency and good thermal stability.

[0007] To solve the technical problem, the solution of the present invention is:

[0008] Provided is a conjugated polymer material containing helicene in the main chain. The general structural formula of the conjugated polymer material is shown in formula (I):

[0009]

[0010] In the formula, X is O, S or N-CH3; R is an alkyl group, and the degree of polymerization n ranges from 85 to 634.

[0011] As a preferred embodiment of the present invention, the conjugated polymer material is copolymerized by oxa[5]helicene and 3,7-bis(3,4-ethylenedioxythiophene-5-yl)-10-(2-octyldodecyl)-10H-phenoxazine, and its general structural formula is shown in Formula (IA):

[0012]

[0013] Where n is 634.

[0014] As a preferred embodiment of the present invention, the conjugated polymer material is copolymerized by thia[5]helicene and 3,7-bis(3,4-ethylenedioxythiophene-5-yl)-10-(2-octyldodecyl)-10H-phenoxazine, and its general structural formula is shown in Formula (IB):

[0015]

[0016] Where n is 440.

[0017] As a preferred embodiment of the present invention, the conjugated polymer material is copolymerized by methylated aza[5]helicene and 3,7-bis(3,4-ethylenedioxythiophene-5-yl)-10-(2-octyldodecyl)-10H-phenoxazine, and its general structural formula is shown in Formula (IC):

[0018]

[0019] Where n is 85.

[0020] The present invention further provides a method for preparing the aforementioned conjugated polymer material containing helicene in the main chain, and the chemical reaction formula thereof is shown below:

[0021]

[0022] Wherein, X is O, S or N-CH3, and the value range of n is 85-634.

[0023] The specific preparation process includes:

[0024] (1) Dibromo-substituted helicene, 3,7-bis(3,4-ethylenedioxythiophene-5-yl)-10-(2-octyldodecyl)-10H-phenoxazine, palladium acetate, tricyclohexylphosphine tetrafluoroborate, and potassium carbonate were weighed in a molar ratio of 1:1:0.1:0.2:3, and then added together to N,N-dimethylacetamide; wherein the mass ratio of potassium carbonate to N,N-dimethylacetamide was 4.02 mmol:300 mL;

[0025] (2) Under argon protection, the mixture was heated to 130°C while stirring and reacted for 3 hours; the mixture was allowed to stand and cool to room temperature, and the organic solvent was filtered out to obtain a crude product; the crude product was then separated and purified by column chromatography to obtain a conjugated polymer material containing helicene in the main chain.

[0026] As a preferred embodiment of the present invention, the dibromo-substituted helicene is any one of the following: 5,9-dibromo-dinaphtho[2,1-b:1',2'-d]furan, 5,9-dibromo-dinaphtho[2,1-b:1',2'-d]thiophene, or 5,9-dibromo-7-methyl-7H-dibenzo[c,g]carbazole.

[0027] As a preferred embodiment of the present invention, the chemical reaction formula for the preparation of 3,7-bis(3,4-ethylenedioxythiophene-5-yl)-10-(2-octyldodecyl)-10H-phenoxazine is as follows:

[0028]

[0029] The specific preparation process includes:

[0030] (1) 3,7-dibromo-10-(2-octyldodecyl)-10H-phenoxazine, 2-(3,4-ethylenedioxythiophene-5-yl)-4,4,5,5-tetramethyl-1,3,2-dioxaborolane, palladium acetate, 2-dicyclohexylphosphine-2',6'-dimethoxybiphenyl, and potassium phosphate were weighed in a molar ratio of 1:2.5:0.05:0.05:5, and then added together into a mixed solvent of 1,4-dioxane and water; the volume ratio of 1,4-dioxane to water in the mixed solvent was 5:1; the mass ratio of potassium phosphate to the volume of the mixed solvent was 16 mmol:240 mL;

[0031] (2) Under argon protection, the mixture was heated to 60° C. while stirring and reacted for 24 hours; the mixture was allowed to stand and cool to room temperature, and purified by column chromatography to obtain 3,7-bis(3,4-ethylenedioxythiophene-5-yl)-10-(2-octyldodecyl)-10H-phenoxazine as an intermediate product.

[0032] The present invention also provides the use of the aforementioned conjugated polymer material containing helicene in the main chain as a hole transport layer in the preparation of perovskite solar cells.

[0033] The present invention further provides a method for making a perovskite solar cell using the aforementioned conjugated polymer material containing helicene in the main chain, comprising: making the conjugated polymer material into a hole transport layer, and then assembling it with other components into a perovskite solar cell; the structure of the perovskite solar cell is: ITO conductive glass / SnO2 electron transport layer / perovskite light absorption layer / hole transport layer / metal electrode.

[0034] Description of the invention principle:

[0035] Helicenes are polycyclic aromatic hydrocarbons with ortho-fused aromatic rings and a helical structure. They exhibit chirality due to the steric repulsion of the terminal rings. Compared to planar molecules, helicenes have better solution processability. Publicly available data indicate that some helicene-based polymers have been applied in fields such as field-effect transistors, organic light-emitting diodes, and thermally activated delayed fluorescence. However, no reports have been published in the field of perovskite solar cells.

[0036] Unlike the prior art applications of helicene-based polymers for specific purposes or methods, the present invention focuses on the application of several conjugated polymer materials containing helicenes in their backbones (e.g., oxa[5]helicene, O5H, thia[5]helicene, T5H, and methylated aza[5]helicene, A5H) in perovskite solar cells, primarily as hole transport layers. Therefore, the prior art's use of helicenes does not constitute a technical revelation, while the present invention's application of helicenes breaks through conventional technical thinking and represents an innovative approach.

[0037] For example, the conjugated polymer p-O5H-E-POZ-E is obtained by copolymerizing O5H with 3,7-bis(3,4-ethylenedioxythiophene-5-yl)-10-(2-octyldodecyl)-10H-phenoxazine. This polymer has a higher highest occupied molecular orbital (HOMO) energy level and a significantly higher glass transition temperature than PTAA. Under the same material processing conditions, p-O5H-E-POZ-E exhibits higher conductivity and hole mobility. Perovskite solar cells prepared with p-O5H-E-POZ-E as the hole transport layer have an average energy conversion efficiency of 24.9% and exhibit excellent tolerance to 85°C.

[0038] Compared with the prior art, the present invention has the following beneficial effects:

[0039] 1. The several conjugated polymer materials containing helicene in the main chain provided by the present invention have properties such as high HOMO energy level, high glass transition temperature, high conductivity, high hole mobility, and solution processability. They can be used as hole transport layers to prepare perovskite solar cells with high energy conversion efficiency and good thermal stability.

[0040] 2. Using several helicene-containing conjugated polymer materials prepared in this invention as hole-transport layers in perovskite solar cells, the resulting devices achieved an average energy conversion efficiency of 24.9%, and maintained an energy conversion efficiency of greater than 90% after 1000 hours of thermal aging at 85°C. Therefore, compared to existing conjugated polymer materials, the products of this invention have greater application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 The DSC curves of several conjugated polymer materials containing helicene in the main chain (Formula (IA), Formula (IB) and Formula (IC)) were measured by differential scanning calorimetry (DSC).

[0042] Figure 2 The measured thin film cyclic voltammetry curves of several conjugated polymer materials containing helicene in the main chain (Formula (IA), Formula (IB) and Formula (IC)) and the calculated highest occupied molecular orbital energy levels are shown.

[0043] Figure 3 This is a schematic diagram of the device structure of the perovskite solar cell provided by the present invention.

[0044] Figure 4 The voltage-current curves of the perovskite solar cell prepared using the product of formula (IA) before and after aging at 85°C for 1000 hours.

[0045] Figure 5 The voltage-current curves of the perovskite solar cell prepared in Comparative Example 1 before and after aging at 85° C. for 1000 hours.

[0046] Figure 6 The voltage-current curves of the perovskite solar cell prepared in Comparative Example 2 before and after aging at 85° C. for 1000 hours. DETAILED DESCRIPTION

[0047] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0048] Example 1

[0049] Synthesis of the target compound of formula (IA);

[0050]

[0051] (1) 3,7-Dibromo-10-(2-octyldodecyl)-10H-phenoxazine (2000 mg, 3.2 mmol), 2-(3,4-ethylenedioxythiophen-5-yl)-4,4,5,5-tetramethyl-1,3,2-dioxaborolane (2155.0 mg, 8.04 mmol), palladium acetate (36.1 mg, 0.16 mmol), 2-dicyclohexylphosphino-2',6'-dimethoxybiphenyl (66.0 mg, 0.16 mmol) and potassium phosphate (3396.3 mg, 16 mmol) were added to 1,4-dioxane and water. The reaction mixture was added to a mixed solvent (240 mL) with a volume ratio of 5 to 1; under argon protection, the reaction system was heated to 60°C while stirring for 24 hours; after the reaction was completed, the mixture was allowed to stand and cool to room temperature, and the reaction solvent was removed by rotary evaporation under reduced pressure to obtain a crude product; after column chromatography separation and purification, a mixed solvent of petroleum ether and tetrahydrofuran with a volume ratio of 5:1 was used as a developing solvent to obtain a yellow-green solid compound 3,7-bis(3,4-ethylenedioxythiophene-5-yl)-10-(2-octyldodecyl)-10H-phenoxazine with a yield of about 86% (2058.2 mg).

[0052] (2) 5,9-dibromo-dinaphtho[2,1-b:1',2'-d]furan (572.9 mg, 1.34 mol), the compound 3,7-bis(3,4-ethylenedioxythiophene-5-yl)-10-(2-octyldodecyl)-10H-phenoxazine (1000 mg, 1.34 mmol) obtained in step (1), palladium acetate (30.1 mg, 0.134 mmol), tricyclohexylphosphine tetrafluoroborate (98.7 mg, 0.322 mmol) and potassium carbonate (554.8 mg, 4.02 mmol) were added to N,N-dimethylacetamide (300 mL); under argon protection, the above mixture was stirred. The reaction system was heated to 130° C. and reacted for 3 hours; the mixture was allowed to stand and cool to room temperature, and the reaction solvent was removed by rotary evaporation under reduced pressure; 200 mL of distilled water was then added to the system, and extraction was performed using dichloromethane (extraction was performed three times, with 200 mL of dichloromethane added each time), the organic phases were combined, and dichloromethane was removed by rotary evaporation under reduced pressure to obtain a crude product, which was separated and purified by column chromatography; the purified crude product was dissolved in 50 mL of tetrahydrofuran, and 300 mL of methanol was added to a glass beaker. The crude product solution was slowly added to the beaker while stirring; the mixture was filtered under reduced pressure and dried under vacuum to obtain a brown solid compound (IA) (1177.9 mg, 87%).

[0053] The structure of the target product (IA) was characterized by nuclear magnetic resonance analysis.

[0054] The NMR characterization data are as follows:

[0055] 1 H NMR(400MHz,THF-d8)δ:9.27-9.13(m,2H),8.47-8.36(m,2H),7.96(s,2H),7.80-7.70(m,2H),7.64-7.54(m,2H),7 .35-7.14(m,4H),6.73-6.58(m,2H),4.41(s,4H),4.28(s,4H),3.53(s,2H),2.02(br,1H),1.53-1.20(m,32H),and 0.92–0.83(m,6H)ppm.

[0056] 13 C NMR(100MHz,THF-d8)δ:155.10,145.84,140.70,138.86,133.28,131.86,130.99,129. 95,129.63,129.46,129.41,127.32,127.24,126.67,126.63,125.66,125.57,121.81,1 20.15,117.89,115.79,113.95,113.92,113.32,113.28,111.93,65.93,65.64,48.62, 36.51,33.07,32.78,31.23,30.83,30.82,30.75,30.71,30.52,30.50,27.82,23.77and 14.61ppm.

[0057] High temperature gel permeation chromatography determined that the target product (IA) had a number average molecular weight of 392 kDa, a weight average molecular weight of 641 kDa, a polydispersity index of 1.6, and a degree of polymerization n of 634.

[0058] The glass transition temperature of the prepared target product (IA) was measured to be 221°C.

[0059] The conductivity of the prepared target product (IA) was measured and found to be 0.40 μS cm when naturally doped with air oxidation. -1 , after the introduction of the doping promoter, it was 74.9 μS cm -1 .

[0060] Example 2

[0061] Synthesis of target compound formula (IB);

[0062] Compared with Example 1, in this example, 5,9-dibromo-dinaphtho[2,1-b:1',2'-d]furan was replaced with 5,9-dibromo-dinaphtho[2,1-b:1',2'-d]thiophene, and the rest of the reaction process, reagent names, and reagent amounts remained the same as in Example 1.

[0063] The synthetic route and the structure of the target compound (IB) are shown below:

[0064]

[0065] The structure of the target compound (IB) was characterized by nuclear magnetic resonance analysis.

[0066] The NMR characterization data are as follows:

[0067] 1 H NMR(400MHz,THF-d8)δ:8.42(s,2H),7.84(s,2H),7.72–7.55(m,2H),7.38–7.21(m,4H),7.14–6.87(m ,4H),6.55(s,2H),4.32(s,4H),4.18(s,4H),3.46(s,2H),2.00–1.88(m,1H),1.38–1.04(m,32H),and 0.71(d,J=5.3Hz,6H)ppm.

[0068] 13 C NMR(100MHz,THF-d8)δ:145.87,140.66,139.31,138.91,133.28,132.02,131.80 ,131.76,131.39,131.18,130.87,128.74,127.38,127.03,126.35,125.88,123.9 7,121.85,117.74,113.92,113.34,112.94,112.87,111.87,65.95,65.65,48.63, 36.48,33.07,32.76,31.22,30.81,30.74,30.70,30.51,30.50,27.79,23.77,and 14.67ppm.

[0069] High temperature gel permeation chromatography determined that the target product (IB) had a number average molecular weight of 226 kDa, a weight average molecular weight of 452 kDa, a polydispersity index of 2.0, and a degree of polymerization n of 440.

[0070] The glass transition temperature of the prepared target organic semiconductor material (Formula (IB)) was measured and the result was 218°C.

[0071] The conductivity of the prepared target organic semiconductor material formula (IB) was measured, and the conductivity was 0.35 μS cm when naturally doped with air oxidation. -1 , after the introduction of the doping promoter, it was 70.2 μS cm -1 .

[0072] Example 3

[0073] Synthesis of target compound formula (IC):

[0074] Compared with Example 1, in this example, 5,9-dibromo-naphtho[2,1-b:1',2'-d]furan was replaced with 5,9-dibromo-7-methyl-7H-dibenzo[c,g]carbazole, and the rest of the reaction process, reagent names, and reagent amounts remained the same as in Example 1.

[0075] The synthetic route and the structure of the target compound formula (IC) are shown below:

[0076]

[0077] The structure of the target compound (IC) was characterized by nuclear magnetic resonance, mass spectrometry and elemental analysis.

[0078] The NMR characterization data are as follows:

[0079] 1 H NMR(400MHz,THF-d8)δ:9.23(s,2H),8.29(dd,J=17.6,8.6Hz,2H),7.94(d,J=17.7Hz,2H),7.64(s,2H),7.47(s,2H),7.30–7.16(m,3 H),6.96–6.45(m,3H),4.40(s,4H),4.26(s,4H),4.13(s,3H),3.47(s,2H),1.97(s,1H),1.34(d,J=41.9Hz,32H),and0.89(s,6H)ppm.

[0080] 13C NMR(100MHz,THF-d8)δ:146.89,145.88,145.72,138.22,129.60,124.17,122.14,121.78,119.27,118.13,117.10,116.78,114.61,113.9 0,113.55,113.33,112.71,110.84,66.29,65.99,65.75,65.57,48.67,36.24,33.06,32.78,32.65,30.69,29.78,27.81,27.70,23.75,and 14.66ppm.

[0081] High temperature gel permeation chromatography determined that the target product (IC) had a number average molecular weight of 3.6 kDa, a weight average molecular weight of 8.7 kDa, a polydispersity index of 2.4, and a degree of polymerization n of 85.

[0082] The glass transition temperature of the prepared target product (IC) was measured to be 230°C.

[0083] The conductivity of the prepared target product (IC) was measured and found to be 0.51 μS cm when naturally doped with air oxidation. -1 , after the introduction of the doping promoter, it was 121.3 μS cm -1 .

[0084] Example 4 Preparation of perovskite solar cells

[0085] The conjugated polymer materials represented by formula (IA), formula (IB), and formula (IC) prepared in Examples 1-3 were used to prepare perovskite solar cells in the following manner.

[0086] Laser-etched indium tin oxide (ITO) glass was ultrasonically cleaned for 10 minutes using detergent, deionized water, acetone, and ethanol, respectively. The cleaned ITO substrate was treated with UV ozone for 15 minutes before use. For the electron transport layer, a 15wt% SnO2 colloidal dispersion was diluted to 2.67wt% with deionized water. Subsequently, the diluted SnO2 colloidal dispersion was spin-coated onto the ITO substrate and annealed at 150°C in air for 30 minutes. Next, 691.5mg of PbI2 and 9.1mg of RbCl were dissolved in 1mL of DMF:DMSO (9:1 by volume) solvent, spin-coated onto the SnO2, and annealed at 70°C for 1 minute. After cooling to room temperature, a solution of formamidinium iodine (FAI): methylamine chloride (MACl) (90 mg: 13.5 mg in 1 ml isopropanol) was spin-coated onto PbI2 and annealed at 150°C for 20 minutes to obtain a FAPbI3 perovskite layer. For the passivation layer, 5 mg of phenylethylamine iodine was dissolved in 1 mL of isopropanol and spin-coated onto the perovskite surface. For the hole transport layer, 40 mg mL -1 Conjugated polymer materials, 4.94 mg mL -1 Lithium bis(trifluoromethanesulfonyl)imide and 132 mM 4-tert-butylpyridine were added to 1 mL of chlorobenzene to prepare a hole transport layer solution, which was then deposited on the perovskite layer. -4 Thermally evaporated gold electrode (about 120nm) under Pa. The structure of perovskite solar cell is shown as follows Figure 3 As shown, the effective area of ​​the battery is 0.258cm 2 .

[0087] Example 5 Energy conversion efficiency test

[0088] The energy conversion efficiency of the perovskite solar cell prepared in Example 5 was tested, and the results are shown in the following table:

[0089] polymer materials Energy conversion efficiency Formula (IA) 24.9％ Formula (IB) 23.8％ Formula (IC) 23.2％

[0090] Example 6 Aging test of perovskite solar cells

[0091] The unpackaged battery was placed in an oven at 85°C to evaluate the device's thermal stability. The relative humidity outside the oven was 45% to 85%. The battery was removed and measured at regular intervals.

[0092] At an irradiance of 100 mW cm -2 The voltage-current curve of the battery was measured under AM1.5G simulated sunlight. The results are as follows Figure 4-6 shown. Figure 4The voltage-current curves of the perovskite solar cell prepared using the target product in Example 1 before and after aging at 85°C for 1000 hours. Before aging, the open circuit voltage of the cell was 1.170 V and the short-circuit current density was 26.0 mA cm -2 , the fill factor is 81.8%, the energy conversion efficiency is 24.9%; after aging at 85℃ for 1000 hours, the open circuit voltage of the battery is 1.155V and the short circuit current density is 25.6cm -2 , the fill factor is 78.3%, the energy conversion efficiency is 23.2%, and the device energy conversion efficiency retention rate is 93%.

[0093] Comparative Example 1

[0094] Commercially available spiro-OMeTAD was used as the hole transport material. Perovskite solar cells were prepared according to the steps in Example 4, and performance tests were performed under the same conditions as in Example 6. The results showed that the open circuit voltage of the spiro-OMeTAD-based cell before aging was 1.165 V and the short-circuit current density was 26.0 mA cm -2 , the fill factor is 80.1%, the energy conversion efficiency is 24.3%; after aging at 85℃ for 1000 hours, the open circuit voltage of the battery is 0.820V, and the short circuit current density is 13.7mA cm -2 , the fill factor is 52.4%, the energy conversion efficiency is 5.9%, and the device energy conversion efficiency retention rate is 24.0%. Figure 5 The voltage-current curves of the perovskite solar cell prepared in Comparative Example 1 before and after aging at 85°C for 1000 hours.

[0095] Comparative Example 2

[0096] Commercially available PTAA was used as the hole transport material. Perovskite solar cells were prepared according to the steps in Example 4, and performance tests were performed under the same conditions as in Example 6. The results showed that the open circuit voltage of the PTAA-based cell before aging was 1.120 V and the short-circuit current density was 25.8 mA cm -2 , the fill factor is 74.5%, the energy conversion efficiency is 21.5%; after aging at 85℃ for 1000 hours, the open circuit voltage of the battery is 1.080V, and the short circuit current density is 24.3mA cm -2 , the fill factor is 63.6%, the energy conversion efficiency is 16.7%, and the device energy conversion efficiency retention rate is 78%. Figure 6 The voltage-current curves of the perovskite solar cell prepared in Comparative Example 2 before and after aging at 85°C for 1000 hours.

[0097] From the above test results, it can be seen that the conjugated polymer containing helicene in the main chain of the present invention is used as the hole transport layer of perovskite solar cells, and has the properties of high glass transition temperature, high conductivity, and high hole mobility. It far exceeds the existing polymer hole transport materials or existing technical solutions in terms of long-term stability at 85°C for perovskite solar cells.

[0098] The above embodiments are provided to help understand the method and core concept of the present invention. It should be noted that, without departing from the principles of the present invention, a number of improvements and modifications may be made to the present invention by a person skilled in the art, and such improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

1. A conjugated polymer material containing helicene in the main chain, characterized in that: The general structural formula of the conjugated polymer material is shown in formula (I): In the formula, X is O, S or N-CH3; R is an alkyl group, and the degree of polymerization n ranges from 85 to 634.

2. The conjugated polymer material according to claim 1, characterized in that The conjugated polymer material is copolymerized by oxa[5]helicene and 3,7-bis(3,4-ethylenedioxythiophene-5-yl)-10-(2-octyldodecyl)-10H-phenoxazine, and its general structural formula is shown in Formula (IA): Where n is 634.

3. The conjugated polymer material according to claim 1, characterized in that The conjugated polymer material is copolymerized by thia[5]helicene and 3,7-bis(3,4-ethylenedioxythiophene-5-yl)-10-(2-octyldodecyl)-10H-phenoxazine, and its general structural formula is shown in Formula (IB): Where n is 440.

4. The conjugated polymer material according to claim 1, characterized in that The conjugated polymer material is copolymerized by methylated aza[5]helicene and 3,7-bis(3,4-ethylenedioxythiophene-5-yl)-10-(2-octyldodecyl)-10H-phenoxazine, and its general structural formula is shown in Formula (IC): Where n is 85.

5. The method for preparing the conjugated polymer material containing helicene in the main chain according to claim 1, characterized in that: The chemical reaction formula is as follows: Wherein, X is O, S or N-CH3, and the value of n ranges from 85 to 634; The specific preparation process includes: (1) Dibromo-substituted helicene, 3,7-bis(3,4-ethylenedioxythiophene-5-yl)-10-(2-octyldodecyl)-10H-phenoxazine, palladium acetate, tricyclohexylphosphine tetrafluoroborate, and potassium carbonate were weighed in a molar ratio of 1:1:0.1:0.2:3, and then added together to N,N-dimethylacetamide; wherein the mass ratio of potassium carbonate to N,N-dimethylacetamide was 4.02 mmol:300 mL; (2) Under argon protection, the mixture was heated to 130°C while stirring and reacted for 3 hours; the mixture was allowed to stand and cool to room temperature, and the organic solvent was filtered out to obtain a crude product; the crude product was then separated and purified by column chromatography to obtain a conjugated polymer material containing helicene in the main chain.

6. The method according to claim 5, characterized in that The dibromo-substituted helicene is any one of the following: 5,9-dibromo-dinaphtho[2,1-b:1',2'-d]furan, 5,9-dibromo-dinaphtho[2,1-b:1',2'-d]thiophene, or 5,9-dibromo-7-methyl-7H-dibenzo[c,g]carbazole.

7. The method according to claim 5, characterized in that The chemical reaction formula for the preparation of the 3,7-bis(3,4-ethylenedioxythiophene-5-yl)-10-(2-octyldodecyl)-10H-phenoxazine is as follows: The specific preparation process includes: (1) 3,7-dibromo-10-(2-octyldodecyl)-10H-phenoxazine, 2-(3,4-ethylenedioxythiophene-5-yl)-4,4,5,5-tetramethyl-1,3,2-dioxaborolane, palladium acetate, 2-dicyclohexylphosphine-2',6'-dimethoxybiphenyl, and potassium phosphate were weighed in a molar ratio of 1:2.5:0.05:0.05:5, and then added together into a mixed solvent of 1,4-dioxane and water; the volume ratio of 1,4-dioxane to water in the mixed solvent was 5:1; the mass ratio of potassium phosphate to the volume of the mixed solvent was 16 mmol:240 mL; (2) Under argon protection, the mixture was heated to 60° C. while stirring and reacted for 24 hours; the mixture was allowed to stand and cool to room temperature, and purified by column chromatography to obtain 3,7-bis(3,4-ethylenedioxythiophene-5-yl)-10-(2-octyldodecyl)-10H-phenoxazine as an intermediate product.

8. Use of the conjugated polymer material containing helicene in the main chain according to claim 1 as a hole transport layer in the preparation of perovskite solar cells.

9. A method for producing a perovskite solar cell using the conjugated polymer material containing helicene in the main chain according to claim 1, characterized in that: include: The conjugated polymer material is made into a hole transport layer, and then assembled with other components into a perovskite solar cell; The structure of the perovskite solar cell is ITO conductive glass / SnO2 electron transport layer / perovskite light absorption layer / hole transport layer / metal electrode.

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