A d-a-d type conjugated organic compound and use thereof

Abstract

The application discloses a D-A-D type conjugated organic compound and application thereof, and relates to the technical field of organic compounds. n H 2n+1 ) m Wherein, A is a heteroatom of VA and VIA groups, n is 1-12, m is 1-2, and R2 is a benzofused heterocyclic bridging group. The D-A-D type conjugated organic compound is used as an organic small molecule dopant of a hole transport material in a perovskite solar cell. The application realizes optimized energy level matching and good film morphology and ordered molecular stacking, thereby improving photoelectric conversion efficiency and long-term stability of the device.

Description

Technical Field

[0001] This invention relates to the field of organic compound technology, and specifically to a DAD-type conjugated organic compound and its uses. Background Technology

[0002] With societal development, mineral resources such as coal, oil, and natural gas are becoming increasingly depleted, leading to energy crises and environmental pollution that urgently need to be addressed. Therefore, developing new alternative energy sources is of significant practical importance. Organic thin-film solar cells, including dye-sensitized solar cells, perovskite solar cells, and organic small-molecule solar cells, have attracted widespread attention. Among them, perovskite solar cells, with their excellent photoelectric properties, solution-processability, and unprecedented efficiency improvement speed, have become a leading next-generation photovoltaic technology. In traditional formal device structures, the hole transport layer, which is in direct contact with the perovskite layer and the back electrode, plays a decisive role in charge extraction and device lifetime. To date, 2,2',7,7'-tetratetra(N,N-di-p-methoxyaniline)-9,9'-spirodifluorene (Spiro-OMeTAD) remains the dominant hole transport layer material in record-breaking efficiency devices. However, its functionality heavily relies on p-type doping of lithium bis(trifluoromethanesulfonyl)imide (Li-TFSI) to achieve sufficient conductivity and hole mobility. However, this conventional doping method has a fundamental and unresolved drawback. Under operating conditions, small-sized Li... + Ions readily diffuse throughout the entire device structure, causing interfacial energy level shifts and perovskite lattice distortion, thus affecting long-term stability. Furthermore, the slow and air-sensitive oxidation process of Spiro-OMeTAD leads to poor reproducibility in device fabrication, and its tendency to crystallize at high temperatures can cause pinholes and morphological collapse in the hole transport layer. Despite significant research efforts, these alternative solutions often require trade-offs between efficiency and stability, or involve complex synthesis processes, hindering their widespread application (Science 377(2022): 495-501; Adv. Mater. 37 (2025): 2505115). Currently, no alternative doping system has been found that can fully replicate the high doping efficiency and mature process of the Li-TFSI system. Therefore, effectively stabilizing lithium ions in Li-TFSI, suppressing ion migration and aggregation, and thus improving device performance and long-term stability remains a key technical problem to be solved in this field. Summary of the Invention

[0003] The purpose of this invention is to provide a DAD-type conjugated organic compound and its uses, which can effectively stabilize lithium ions in Li-TFSI, inhibit ion migration and aggregation, thereby improving device performance and long-term stability.

[0004] The technical solution adopted to achieve the objective of this invention is as follows: A DAD-type conjugated organic compound having the structure shown in formula (I): (I) In formula (I): R1=A(C n H 2n+1 ) m , where A is a heteroatom of group VA and VIA, n=1~12, m=1~2, and R2 is a benzofused heterocyclic bridging group.

[0005] The structure of the R2 benzo-fused heterocyclic bridging group in formula (I) is as follows: .

[0006] In a preferred embodiment of the present invention, R1 is a C1-C8 alkyl or a C1-C8 alkyl heteroatom group; R2 is a benzothiadiazole or a benzoxadiazole or a benzotriazole or a quinoxaline.

[0007] More preferably, R1 is a C1-C6 alkyl or C1-C6 alkyl heteroatom group; R2 is benzothiadiazole or benzotriazole.

[0008] The optimal technical solution is: R1 is methoxy; R2 is benzothiadiazole.

[0009] The conjugated organic small molecule compound of the present invention is prepared by the following reaction formula:

[0010] In the reaction formula, the meanings of R1 and R2 are the same as those described in the preferred embodiment above.

[0011] Furthermore, a DAD-type conjugated organic compound is used as an organic small molecule dopant in hole transport materials for perovskite solar cells.

[0012] The beneficial effects of this invention are: The conjugated organic small molecule compound of the present invention, namely the compound shown in formula (I), can be used as a dopant in the Spiro-OMeTAD hole transport layer in perovskite solar cells. Through rational molecular design, this compound has multiple lithium-ion complexation modes, which can effectively suppress the migration and aggregation of lithium ions in the device and promote the effective oxidation doping of Spiro-OMeTAD, achieving optimized energy level matching and good film morphology and ordered molecular stacking, thereby improving the photoelectric conversion efficiency and long-term stability of the device. Attached Figure Description

[0013] Figure 1This is a schematic diagram of the structure of the organic small molecule dopant 35 prepared in Example 4 complexed with lithium ions.

[0014] Figure 2 This is a schematic diagram of the formal planar perovskite solar cell devices prepared in Example 5 and Comparative Example 1.

[0015] Figure 2 In the middle: ITO -- conductive glass substrate; SnO2 -- tin dioxide electron transport layer; Perovskite -- perovskite layer; doped HTL -- the hole transport layer doped with organic small molecule dopant 35 and Li-TFSI as described in this invention; Ag -- counter electrode.

[0016] Figure 3 The electron paramagnetic resonance spectra of the organic small molecule dopant 35 prepared in Example 5 and the hole transport layer of Comparative Example 1 after being doped in chlorobenzene solution are shown.

[0017] Figure 4 The current-voltage curves of the organic small molecule dopant 35 prepared in Example 5 and the hole transport material dopant in Comparative Example 1 are shown.

[0018] Figure 5 The graph shows the long-term stability of the perovskite solar cells prepared in Example 5 and Comparative Example 1. Detailed Implementation

[0019] The present invention will be further illustrated below through examples, with the aim of providing a better understanding of its content. Therefore, the examples given do not limit the scope of protection of the present invention.

[0020] Example 1

[0021] Synthesis of Organic Small Molecule Dopant 11

[0022] In a 25 mL round-bottom flask, 1-bromo-2-fluoro-4-iodobenzene (0.30 g, 1.0 mmol), dimethyl disulfide (0.11 g, 1.2 mmol), potassium tert-butoxide (0.34 g, 3.0 mmol), and acetonitrile (2 mL) were added. The reaction mixture was stirred at 50 °C for 6 hours. After cooling to room temperature, the reaction mixture was extracted with water (5 mL) and ethyl acetate (4 × 10 mL). The extracts were combined, washed with brine (3 × 10 mL), dried over anhydrous magnesium sulfate, filtered, and the solvent was evaporated to dryness. The mixture was then purified by silica gel column chromatography using petroleum ether / ethyl acetate (v / v = 80:1) as the eluent to give colorless crystalline compound 3 (0.20 g, 62%). 1HNMR (400MHz, Chloroform-d, ppm): δ 7.35 (d, J = 8.5 Hz, 1H), 7.17 (d, J = 2.0Hz, 1H), 7.10 (dd, J = 8.5, 2.0 Hz, 1H), 2.47 (s, 3H).

[0023] Compound 3 (5.17 g, 15.7 mmol), compound 4 (3.29 g, 12.6 mmol), sodium tert-butoxide (1.89 g, 18.9 mmol), and 50 mL of toluene were added to a 250 mL round-bottom flask. After deoxygenation, catalysts Pd₂(dba)₃ (65 mg) and Pd(dppf)Cl₂ (56 mg, 0.10 mmol) were added, and the reaction system was heated to 120 °C and reacted for 6 h. The reaction solution was extracted with dichloromethane, the solvent was evaporated, and the mixture was separated by silica gel column chromatography with a petroleum ether to dichloromethane ratio of 10:1 to give a yellow solid compound 5 (4.95 g, 85% yield). 1 H NMR (400MHz, Chloroform-d, ppm): δ 7.28(d, J = 8.9 Hz, 1H), 7.17 (d, J = 8.9 Hz, 4H), 6.95 (d, J = 8.9 Hz, 4H), 6.74(d, J = 8.9 Hz, 1H), 6.70 (dd, J = 8.2, 1.9 Hz, 1H), 2.47 (s, 3H), 2.39 (s, 6H).

[0024]

[0025] Compound 5 (1.39 g, 3.00 mmol), pinacol diborate (1.91 g, 7.50 mmol), potassium acetate (0.88 g, 9.00 mmol), and 50 mL of toluene solution were deoxygenated. Then, Pd(dppf)Cl2 catalyst (0.25 g, 0.31 mmol) was added to the solution, and the mixture was refluxed at 120 °C for 16 h. The reaction solution was poured into water, extracted with dichloromethane, and purified using a silica gel column (petroleum ether: dichloromethane = 1:2) to give a yellow solid compound 7 (1.15 g, yield: 75%). 1H NMR (400MHz, Chloroform-d, ppm): δ 7.44 (d, J = 7.7 Hz, 1H), 7.07 (d, J= 8.5 Hz, 4H), 6.85 (d, J = 8.5 Hz, 4H), 6.73 (d, J = 8.9 Hz, 1H), 6.52 (dd,J = 8.2, 1.9 Hz, 1H), 2.46 (s, 3H), 2.38 (s, 6H), 1.29 (s, 12H).

[0026]

[0027] Compound 8 (4.40 g, 25.6 mmol) and CH3SNa (3.90 g, 56.3 mmol) were dissolved in 10 mL DMF and 20 mL THF and stirred at room temperature for 1 h, followed by extraction with dichloromethane and water. After solvent removal, the product was purified by silica gel column chromatography with petroleum ether:dichloromethane = 1:1 as the eluent to give a pale yellow solid, compound 9 (3.15 g, yield: 54%). 1 H NMR (400MHz, Chloroform-d, ppm): δ 7.50 (s, 2H), 2.56 (s, 6H).

[0028]

[0029] Compound 9 (3.19 g, 14.0 mmol) was dissolved in a mixed solvent of dichloromethane (20 mL) and acetic acid (5 mL), and bromine (7.2 mL, 140 mmol) was slowly added to the solution. The resulting mixture was stirred overnight at room temperature in the dark. The reaction mixture was extracted with water and dichloromethane, and the solvent was removed under reduced pressure. The product was purified by silica gel column chromatography with petroleum ether:dichloromethane = 1:1 as the eluent to give compound 10 (4.76 g, yield: 88%) as a yellow solid. 1 H NMR (400MHz, Chloroform-d, ppm): δ 2.58 (s, 6H).

[0030]

[0031] Compound 10 (0.26 g, 0.68 mmol), compound 7 (0.76 g, 1.5 mmol), cesium carbonate (1.3 g, 4 mmol), 2.5 mL of water, 25 mL of xylene solution, and catalyst Pd(dppf)Cl2 (0.06 g, 0.07 mmol) were sequentially added to a 100 mL round-bottom flask. The reaction system was heated to 150 °C and refluxed for 20 h. The mixture was extracted with 70 mL of water and CHCl2, and purified by silica gel column chromatography (dichloromethane:methanol = 200:1). The crude product was recrystallized in a two-component solvent of dichloromethane and petroleum ether to give compound 11 as an orange powder (0.41 g, yield 61%). 1 H NMR (400 MHz, Acetone-d6, ppm): δ 7.47(t, J = 7.0 Hz, 10H), 7.36 (d, J = 8.9 Hz, 8H), 6.93 (s, 2H), 6.63 (d, J =8.3 Hz, 2H), 3.53 (s, 12H), 2.38 (s, 12H).

[0032] Example 2

[0033] Synthesis of Organic Small Molecule Dopant 19

[0034] Anhydrous potassium carbonate (5.00 g, 36.18 mmol) was added to a DMF (12 mL) solution of 2-bromo-5-iodoaniline (1.19 g, 3.98 mmol) under an argon atmosphere. 1.2 mL of iodomethane (20 mmol) was added to the solution, and the reaction was carried out at 100 °C for 48 h. After the reaction was complete, the mixture was extracted with water and dichloromethane. The organic phase was dried over anhydrous sodium sulfate, the solvent was removed under reduced pressure, and the mixture was purified by column chromatography (petroleum ether: ethyl acetate = 20:1) to give an oily compound 13 (1.26 g, yield: 97%). 1 H NMR (400MHz, Chloroform-d, ppm): δ 7.35 (d, J = 8.8 Hz, 1H), 7.14 (d, J = 2.4Hz, 1H), 6.96 (dd, J = 8.8, 2.4 Hz, 1H), 2.76 (s, 6H).

[0035]

[0036] Compound 13 (5.12 g, 15.7 mmol), compound 14 (3.21 g, 12.6 mmol), sodium tert-butoxide (1.89 g, 18.9 mmol), and 50 mL of toluene were added to a 250 mL round-bottom flask. After deoxygenation, catalysts Pd₂(dba)₃ (65 mg) and Pd(dppf)Cl₂ (56 mg, 0.1 mmol) were added, and the reaction system was heated to 110 °C and reacted for 15 h. The reaction solution was extracted with dichloromethane, the solvent was evaporated, and the mixture was separated by silica gel column chromatography with a petroleum ether to ethyl acetate ratio of 5:1 to give a yellow solid compound 15 (2.11 g, yield 37%). 1 H NMR (400MHz, Chloroform-d, ppm): δ 7.28(d, J = 8.9 Hz, 1H), 7.17 (d, J = 8.9 Hz, 4H), 6.95 (d, J = 8.9 Hz, 4H), 6.74(d, J = 8.9 Hz, 1H), 6.70 (dd, J = 8.2, 1.9 Hz, 1H), 2.47 (s, 18H).

[0037]

[0038] Compound 15 (1.36 g, 3 mmol), pinacol diborate (1.91 g, 7.5 mmol), potassium acetate (0.88 g, 9 mmol), and 50 mL of toluene solution were deoxygenated, and then Pd(dppf)Cl2 catalyst (0.25 g, 0.31 mmol) was added to the solution. The mixture was then refluxed at 120 °C for 16 h. The reaction solution was poured into water, extracted with dichloromethane, and purified using a silica gel column (petroleum ether: dichloromethane = 1:2) to give a yellow solid, compound 16 (1.13 g, yield: 75%). 1 H NMR (400MHz, Chloroform-d, ppm): δ 7.38 (d, J = 8.9 Hz, 1H), 7.14 (d, J = 8.9 Hz, 4H), 6.85 (d, J = 8.9 Hz, 4H), 6.52 (d, J = 8.9 Hz, 1H), 6.38 (dd, J = 8.2,1.9 Hz, 1H), 3.02 (s, 18H), 1.27 (s, 12H).

[0039]

[0040] A mixture of 10 mL of 35% HCHO aqueous solution and 15 mL of 3 M sulfuric acid solution was added dropwise to a solution of 30 mL of tetrahydrofuran containing NaBH4 (5.23 g, 135 mmol) and compound 17 (2.92 g, 9.0 mmol). After the reaction was complete, the solution was adjusted to alkaline. Extraction was performed with water and dichloromethane, and the solvent was removed under reduced pressure. The mixture was then subjected to dichloromethane chromatography on an alumina column and recrystallized from methanol to give a red solid, compound 18 (3.42 g, yield: 63%). 1 H NMR (400MHz, Chloroform-d, ppm): δ 3.00 (s, 12H).

[0041]

[0042] Compound 18 (0.26 g, 0.68 mmol), compound 16 (0.75 g, 1.5 mmol), cesium carbonate (1.3 g, 4 mmol), 2.5 mL of water, 25 mL of xylene solution, and catalyst Pd(dppf)Cl2 (0.06 g, 0.07 mmol) were sequentially added to a 100 mL round-bottom flask. The reaction system was heated to 150 °C and refluxed for 20 h. The mixture was extracted with 70 mL of water and CHCl2 and purified by silica gel column chromatography (DMC:MeOH = 150:1). The crude product was recrystallized in a two-component solvent of dichloroethylene and petroleum ether to give compound 19 as an orange powder (0.40 g, yield 61%). 1 H NMR (400 MHz, Acetone-d6, ppm): δ 7.57 (t, J= 7.0 Hz, 10H), 7.26 (d, J = 8.9 Hz, 8H), 7.03 (s, 2H), 6.57 (d, J = 8.3 Hz,2H), 3.02 (s, 36H), 2.86 (s, 12H).

[0043] Example 3

[0044] Synthesis of Organic Small Molecule Dopant 29

[0045] Compound 20 (0.30 g, 1.00 mmol), K₂CO₃ (0.60 g, 4.01 mmol), KI (0.02 g, 0.10 mmol), and IC₄H₈ (0.23 g, 1.25 mmol) were suspended in dry DMF (15 mL) under an argon atmosphere and stirred at 60 °C for 24 hours. After cooling the reaction mixture to room temperature, it was diluted with dichloromethane and water, and the organic phase was separated. The organic phase was washed successively with water and saturated brine, dried over MgSO₄, and the solvent was removed under reduced pressure. Purification was performed by silica gel column chromatography using petroleum ether and dichloromethane (2:1) as eluent to give a colorless solid compound 22 (0.31 g, 87% yield). 1 H NMR (400 MHz, DMSO-d6, ppm): δ 7.24 (d, J = 8.2 Hz, 1H), 7.20 (d, J = 1.8 Hz, 1H), 7.15 (dd, J = 8.2, 1.9 Hz, 1H), 3.99 (t, J = 6.5 Hz, 2H), 1.98-1.64 (m, 2H), 1.56-1.42 (m, 2H), 0.88 (t, J = 6.7 Hz, 3H).

[0046] Under argon protection, toluene (50 mL), 4-n-butoxyaniline (0.84 g, 5.1 mmol), and 1-bromo-4-n-butoxybenzene (1.16 g, 5 mmol) were added to a 100 mL round-bottom flask. Pd₂dba₃ (0.05 g, 0.05 mmol), 1,1'-bis(diphenylphosphine)ferrocene (0.06 g, 0.1 mmol), and sodium tert-butoxide (0.6 g, 6.2 mmol) were then added. A reflux condenser was fitted, and the reaction mixture was heated to 120 °C and refluxed for 6 hours. The reaction mixture was then quenched with distilled water and extracted with ethyl acetate. The organic phase was collected, and the solvent was removed by rotary evaporation. The crude product was purified by column chromatography (petroleum ether:ethyl acetate = 5:1) to give a light brown solid compound 25 (1.14 g, yield: 73%). 1H NMR (400MHz, DMSO-d6, ppm): δ 7.47 (s, 1H), 6.89 (d, J=8.9Hz, 4H), 6.79 (d, J=8.9Hz, 4H), 3.87 (t, J=6.5Hz, 4H), 1.69-1.62 (m, 4H), 1.47-1.37 (m, 4H), 0.92 (t, J=7.4Hz, 6H).

[0047]

[0048] Compound 25 (1.91 g, 6.1 mmol), compound 22 (2.84 g, 8.0 mmol), sodium tert-butoxide (0.95 g, 9.5 mmol), and 50 mL of toluene were added to a two-necked round-bottom flask to remove oxygen. Then, catalysts Pd₂(dba)₃ (0.03 g) and Pd(dppf)Cl₂ (0.03 g, 0.05 mmol) were added, and the reaction mixture was heated to 120 °C and reacted for 12 h. The reaction solution was extracted with dichloromethane, the solvent was evaporated, and the mixture was separated by silica gel column chromatography at a petroleum ether:ethyl acetate ratio of 25:1 to obtain a colorless oily compound 26 (3.06 g, 93% yield). 1 H NMR (400 MHz, Acetone-d6, ppm): δ 7.28(d, J = 8.9 Hz, 1H), 7.04 (d, J = 8.9 Hz, 4H), 6.90 (d, J = 8.9 Hz, 4H), 6.74(d, J = 8.9 Hz, 1H), 6.70 (dd, J = 8.2, 1.9 Hz, 1H), 3.97 (t, J = 6.4 Hz, 6H), 1.74-1.63 (m, 6H), 1.49-1.39 (m, 6H), 0.97 (t, J = 7.4 Hz, 9H).

[0049]

[0050] Compound 26 (1.62 g, 3 mmol), pinacol diborate (1.91 g, 7.5 mmol), potassium acetate (0.88 g, 9 mmol), and 50 mL of toluene solution were deoxygenated, and then Pd(dppf)Cl2 catalyst (0.25 g, 0.31 mmol) was added to the solution. The mixture was then refluxed at 120 °C for 16 h. The reaction solution was poured into water, extracted with dichloromethane, and purified using a silica gel column (petroleum ether: ethyl acetate = 10:1) to give a pale yellow oily compound 27 (1.39 g, yield: 79%). 1 HNMR (400 MHz, Acetone-d6, ppm): δ 7.30 (d, J = 8.9 Hz, 1H), 7.01 (d, J = 8.9Hz, 4H), 6.91 (d, J = 8.9 Hz, 4H), 6.54 (d, J = 8.9 Hz, 1H), 6.73 (dd, J =8.2, 1.9 Hz, 1H), 3.96 (t, J = 6.4 Hz, 6H), 1.63-1.54 (m, 6H), 1.43-1.33 (m,6H), 1.22 (s, 12H), 0.87 (t, J = 7.4 Hz, 9H).

[0051]

[0052] 4,7-Dibromo-5,6-dibutoxybenzo[c][1,2,5]thiadiazole (0.30 g, 0.68 mmol), compound 27 (0.88 g, 1.5 mmol), cesium carbonate (1.3 g, 4 mmol), 2.5 mL of water, 25 mL of xylene solution, and catalyst Pd(dppf)Cl2 (0.06 g, 0.07 mmol) were sequentially added to a 100 mL round-bottom flask. The reaction system was heated to 150 °C and refluxed for 20 h. The mixture was extracted with 70 mL of water and CHCl2 and purified by silica gel column chromatography (dichloromethane:methanol = 200:1). The crude product was recrystallized in a two-component solvent of dichloromethane and petroleum ether to give compound 29 as a yellow powder (0.79 g, yield 44%). 1 HNMR (400 MHz, Acetone-d6, ppm): 1H NMR (400 MHz, Acetone-d6, ppm): δ 7.21 (t, J= 8.9 Hz, 10H), 6.95 (d, J = 8.9 Hz, 8H), 6.74 (s, 2H), 6.63 (d, J = 8.2 Hz,2H), 4.06 (t, J = 6.4 Hz, 16H), 1.73-1.67 (m, 16H), 1.47-1.39 (m, 16H), 0.99 (t, J = 7.4 Hz, 24H).

[0053] Example 4

[0054] Synthesis of Organic Small Molecule Dopant 35

[0055] 4,4′-dimethoxydiphenylamine (2.88 g, 12.6 mmol), 2-bromo-5-iodoanisole (4.92 g, 15.7 mmol), and sodium tert-butoxide (1.89 g, 18.9 mmol) were added to 50 mL of toluene to remove oxygen. Then, catalysts Pd₂(dba)₃ (65 mg) and Pd(dppf)Cl₂ (56 mg, 0.1 mmol) were added, and the reaction mixture was heated to 120 °C and reacted for 12 h. The reaction mixture was extracted with dichloromethane, the solvent was evaporated, and the mixture was separated by silica gel column chromatography at a petroleum ether:ethyl acetate ratio of 200:1 to give a white solid compound 32 (4.73 g, 71% yield). 1 H NMR (400 MHz, DMSO-d6, ppm): δ 7.30(d, J = 8.7 Hz, 1H), 7.04 (d, J = 8.9 Hz, 4H), 6.91 (d, J = 8.9 Hz, 4H), 6.43(d, J = 2.6 Hz, 1H), 6.21 (dd, J = 8.7, 2.5 Hz, 1H), 3.73 (s, 6H), 3.59 (s, 3H).

[0056]

[0057] Compound 32 (1.25 g, 3 mmol), pinacol diborate (1.91 g, 7.5 mmol), potassium acetate (0.88 g, 9 mmol), and 50 mL of toluene solution were deoxygenated, and then Pd(dppf)Cl2 catalyst (0.25 g, 0.31 mmol) was added to the solution. The mixture was then refluxed at 120 °C for 16 h. The reaction solution was poured into water, extracted with dichloromethane, and purified using a silica gel column (petroleum ether: ethyl acetate = 120: 1) to give a pale yellow oily compound 33 (1.13 g, yield: 81%). 1 HNMR (400 MHz, DMSO-d6, ppm): δ 7.34 (d, J = 8.1 Hz, 1H), 7.06 (d, J = 8.6 Hz, 4H), 6.92 (d, J = 8.7 Hz, 4H), 6.22 (d, J = 9.6 Hz, 1H), 3.74 (s, 6H), 3.47(s, 3H), 1.22(s, 12H).

[0058]

[0059] 4,7-Dibromo-5,6-dimethoxybenzo[c][1,2,5]thiadiazole (0.24 g, 0.68 mmol), compound 33 (0.69 g, 1.5 mmol), cesium carbonate (1.3 g, 4 mmol), 2.5 mL of water, 25 mL of xylene solution, and catalyst Pd(dppf)Cl2 (0.06 g, 0.07 mmol) were sequentially added to a 100 mL round-bottom flask. The reaction system was heated to 150 °C and refluxed for 20 h. The mixture was extracted with 70 mL of water and CHCl2 and purified by silica gel column chromatography (dichloromethane:ethyl acetate = 1:1). The crude product was recrystallized in a two-component solvent of dichloromethane and petroleum ether. Compound 35 was a yellow powder (0.33 g, yield 46%). 1 HNMR (400 MHz, Acetone-d6, ppm): δ 7.17 (t, J = 7.0 Hz, 10H), 6.96 (d, J = 8.9Hz, 8H), 6.65 (s, 2H), 6.50 (d, J = 8.3 Hz, 2H), 3.81 (s, 12H), 3.77 (d, J =2.7 Hz, 6H), 3.53 (d, J = 5.4 Hz, 6H).

[0060] Figure 1This is a schematic diagram of the structure of the organic small molecule dopant 35 prepared in Example 4 complexed with lithium ions. Through rational molecular design, multi-site and multi-mode lithium ion complexation can be achieved, thereby effectively suppressing ion migration.

[0061] Example 5

[0062] The triphenylamine-based small organic molecule compound 35 described in this invention was used as a dopant for hole transport materials in perovskite solar cells, and its photovoltaic performance was tested. Perovskite solar cell devices were fabricated using compound 35 prepared in Example 4 as a hole transport material dopant. A schematic diagram of the formal planar perovskite solar cell involved in this example is shown below. Figure 2 As shown, the specific device fabrication steps are as follows: (1) The transparent conductive glass substrate ITO was ultrasonically cleaned in cleaning agent, deionized water, acetone and isopropanol for 20 min in sequence, and then dried with nitrogen for later use. (2) Prepare an electron transport layer precursor solution by mixing tin dioxide dispersion with deionized water at a volume ratio of 1:3. Spin coat the obtained solution onto the ozone-treated conductive glass ITO at a spin speed of 3000 rpm for 45 s. Anneal at 150 °C for 30 min to obtain the electron transport layer. After the conductive glass substrate ITO cools to room temperature, ozone treat the conductive glass substrate ITO containing the dense electron transport layer for 10 min for later use.

[0063] (3) 1.5M lead iodide was added to N,N-dimethylformamide and dimethyl sulfoxide (volume ratio 9:1) to obtain a lead iodide precursor solution; then, the lead iodide precursor solution was spin-coated onto an ITO substrate containing a dense electron transport layer at a speed of 1500 rpm for 30 s, and annealed at 70 °C for 40 s to obtain a lead iodide layer; finally, an ammonium salt precursor solution dissolved in isopropanol was spin-coated onto the lead iodide layer at a speed of 1700 rpm for 25 s, and annealed at 150 °C for 15 min to obtain a perovskite layer; the ammonium salt solution was prepared by dissolving 90 mg formamidin hydroiodide FAI and 15 mg methylamine hydrochloride MACCl in 1 mL of isopropanol; (4) Add 5 mol% organic small molecule dopant 35 to the prepared 30 mM Spiro-OMeTAD hole transport material solution containing Li-TFSI (520 mg / mL acetonitrile solution), spin-coat it onto the perovskite layer at a spin speed of 3000 rpm for 30 s. (5) In 5×10 -4Under Torr vacuum conditions, a 100 nm thick layer of metallic Ag was deposited on the hole transport layer at a rate of 0.5–1 Å / s to obtain the counter electrode layer, thus completing the fabrication of the perovskite solar cell.

[0064] Comparative Example 1 Li-TFSI was used as a hole transport material dopant in perovskite solar cells, and its photovoltaic performance was tested. Compared with Example 5, Comparative Example 1 differs in that the hole transport layer precursor solution prepared on the perovskite light-absorbing layer in step 4 is a 30 mM Spiro-OMeTAD hole transport material solution containing Li-TFSI (520 mg / mL acetonitrile solution).

[0065] Electron paramagnetic resonance spectroscopy was performed on the hole transport layer precursor solutions from Example 5 and Comparative Example 1. Figure 3 As shown, in Example 5, the introduction of organic small molecule dopant 35 resulted in a stronger radical signal peak than in Comparative Example 1, indicating that organic small molecule dopant 35 promoted efficient doping of the hole transport material.

[0066] 100mW / cm² in solar simulator -2 Under illumination, the photocurrent and photovoltage curves of Example 5 and Comparative Example 1 were measured using a Keysight B2901BL digital source meter. The test results are shown in [Figure number missing]. Figure 4 The battery device prepared in Example 5 had an open-circuit voltage of 1.173 V and a short-circuit current of 26.39 mA cm⁻¹. -2 The fill factor was 0.841, and the photoelectric conversion efficiency was 26.03%. This is significantly higher than the performance of the battery prepared in Comparative Example 1. Figure 5 This study tested the long-term stability of the perovskite solar cells prepared in Example 5 and Comparative Example 1. After continuous irradiation under sunlight for 40 days, the cell prepared in Example 5 maintained 90% of its initial photoelectric conversion efficiency; while the cell prepared in Comparative Example 1 showed that its photoelectric conversion efficiency decreased to 90% of its initial value after 3 days. In summary, compared with traditional doping processes, the triphenylamine-based organic small molecule dopant described in this invention can effectively suppress lithium-ion migration and promote effective doping. Its application as a hole transport material in perovskite solar cells can generate higher short-circuit current and a higher fill factor, ultimately achieving a high-efficiency and long-term stable perovskite solar cell.

[0067] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings, but the present invention is not limited to the described embodiments. For those skilled in the art, various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and these variations still fall within the protection scope of the present invention.

Claims

1. A DAD-type conjugated organic compound, characterized in that, It has the structure shown in equation (I): ( I ) In formula (I): R1=A(C n H 2n+1 ) m Where A is a heteroatom of Group VA and VIA, n=1~12, m=1~2, and R2 is a benzofused heterocyclic bridging group; The structure of the R2 benzo[i] fused heterocyclic bridging group in formula (I) is as follows: 。 2. The DAD-type conjugated organic compound according to claim 1, characterized in that: R1 is a C1-C8 alkyl or C1-C8 alkyl heteroatom group; R2 is benzothiadiazole, benzoxadiazole, benzotriazole or quinoxaline.

3. The DAD-type conjugated organic compound according to claim 1, characterized in that: R1 is a C1-C6 alkyl or C1-C6 alkyl heteroatom group; R2 is benzothiadiazole or benzotriazole.

4. A DAD-type conjugated organic compound according to claim 1, characterized in that: R1 is methoxy; R2 is benzothiadiazole.

5. The use of a DAD-type conjugated organic compound according to any one of claims 1 to 4, characterized in that: Organic small molecule dopants used as hole transport materials in perovskite solar cells.

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