A non-fused ring thiophene polynuclear hole transport material and a preparation method and application thereof

Abstract

The application belongs to the technical field of organic synthesis, and discloses a non-fused ring thiophene polynuclear hole transport material and a preparation method and application thereof. The hole transport material takes a non-fused ring thiophene polynucleus as a central core and methoxytriphenylamine as a peripheral end group. The S and O atoms of the non-fused ring thiophene polynucleus are conducive to forming a non-covalent conformational lock, so as to make the material have excellent solubility and film-forming property, and effectively enhance molecular accumulation and improve hole transport performance. In addition, the central core polynuclear sulfur atom characteristics promote the interface action of the hole transport layer and the perovskite layer, are conducive to passivating the interface defects of the perovskite layer, and further improve the transport and separation efficiency of carriers. The non-fused ring thiophene polynuclear hole transport material is applied to a perovskite solar cell, the device open-circuit voltage is 1.130 V, the short-circuit photocurrent density is 24.07 mA cm ‑2 , the fill factor is 0.7860, and finally a high photoelectric conversion efficiency of 21.38% is obtained, which shows great commercial application value.

Description

Technical Field

[0001] This invention belongs to the field of organic synthesis technology, and relates to the synthesis of hole transport materials, specifically to a non-fused-ring thiophene multinuclear hole transport material, its preparation method, and its applications. Background Technology

[0002] As a next-generation photovoltaic technology, perovskite solar cells (PSCs) have advantages such as simple fabrication processes, easily modulated materials, and low cost. The latest certified efficiency has reached 26.2% (National Renewable Energy Laboratory, NREL, 2023). A typical PSC device mainly consists of conductive glass, an electron transport layer, a perovskite film, hole transport materials (HTMs), and metal electrodes. Among these, the hole transport materials primarily collect and transport photogenerated holes, suppress interfacial electron recombination, and achieve efficient electron-hole separation and transport. Therefore, high-performance HTMs are crucial to device performance. Organic small-molecule hole transport materials have attracted much attention due to their simple synthesis, flexible structural design, and high photoelectric conversion efficiency. Organic small-molecule HTMs typically employ a "central core + peripheral end groups" construction strategy. By regulating and optimizing the molecular central core, the performance of hole transport materials can be effectively improved. Among these, HTMs based on spirocyclic groups as the central core (such as Spiro-OMeTAD) exhibit excellent solubility and high-quality thin film morphology, attracting widespread attention. However, due to their non-planar three-dimensional configuration, these HTMs suppress intermolecular interactions, reducing hole transport efficiency. They require doping with additives such as lithium salts, cobalt salts, and tert-butylpyridine, leading to increased battery fabrication costs and reduced device stability. Furthermore, these materials are difficult to purify and expensive. Given the drawbacks of spirocyclic cores, researchers have successively developed HTMs based on planar cores. The introduction of a planar rigid core promotes electronic dipole interactions of hole molecules, effectively improving hole mobility. However, the high conjugation of the core also leads to reduced solubility and film-forming properties. Therefore, the trade-off effect between solubility and film-forming properties and hole mobility has become a bottleneck limiting further performance improvements in small molecule hole transport materials. In view of this, developing novel small molecule HTMs that combine excellent solubility and film-forming properties with high-efficiency hole transport performance is particularly important. Summary of the Invention

[0003] To address the shortcomings of existing technologies, the present invention aims to provide a non-fused-ring thiophene multinuclear hole transport material (HTMs), its preparation method, and its applications. The non-fused-ring thiophene central core in HTMs helps ensure excellent solubility in solvents, thereby improving the film quality of HTMs. Simultaneously, the S and O atoms in the central core can form non-covalent conformational locking, promoting the formation of a planar molecular spatial configuration during film formation, enhancing intermolecular interactions, and thus improving the hole transport and extraction performance of the hole transport material. Furthermore, the polysulfide atom characteristics of the central core promote the interfacial interaction between the hole transport layer and the perovskite layer, which helps passivate perovskite layer interface defects and improve electron-hole transport separation efficiency. The non-fused-ring thiophene multinuclear hole transport material of the present invention, when applied to perovskite solar cells, achieves a photoelectric conversion efficiency of up to 21.38% and exhibits high device stability, demonstrating significant commercial application value.

[0004] This invention is achieved through the following technical solution:

[0005] A non-fused-ring thiophene multinuclear hole transport material, with the molecular structure shown in FR01:

[0006] .

[0007] A further improvement to the present invention is as follows:

[0008] A method for preparing a nonplanar thiophene multinuclear hole transport material includes the following steps:

[0009] (1) Cause compound 1 to undergo bromination to generate intermediate 2;

[0010] (2) To cause compound 3 to undergo a coupling reaction with compound 4 to generate intermediate 5;

[0011] (3) Cause intermediate 5 to undergo a substitution reaction to generate intermediate 6;

[0012] (4) Intermediate 2 and intermediate 6 undergo a Stille coupling reaction to generate compound FR01, which is a non-planar thiophene polynuclear hole transport material.

[0013] The reaction equation is shown below:

[0014] .

[0015] Further, the specific process of step (1) is as follows: compound 1 is reacted with N-bromosuccinimide (NBS) in the solvent tetrahydrofuran to generate intermediate 2; the molar ratio of compound 1 to NBS is 1:2~3.

[0016] Further, the specific process of step (2) is as follows: Compound 3 is mixed with Compound 4, potassium carbonate, pivalic acid, palladium acetate and tris(o-methylphenyl)phosphine and dissolved in N,N-dimethylformamide (DMF), and heated under a nitrogen atmosphere. After the reaction is completed, intermediate 5 is separated and purified. The molar ratio of Compound 3, Compound 4, palladium acetate, tris(o-methylphenyl)phosphine, pivalic acid and potassium carbonate is 1: 2~3: 0.1~0.2: 0.2~0.4: 0.2~1: 1~2.

[0017] Further, the specific process of step (3) is as follows: intermediate 5 is dissolved in anhydrous tetrahydrofuran, n-butyllithium in n-hexane solution is added dropwise under cooling conditions, and stirring is continued at low temperature. Then, tributyltin chloride is added, the reaction solution is heated to room temperature, and stirring is continued overnight. After the reaction is completed, the solution is quenched with water, extracted with organic solvent and dried, and the solvent is removed under reduced pressure to obtain intermediate 6. The molar ratio of intermediate 5, n-butyllithium and tributyltin chloride is 1:1.1~1.5:1.1~1.5.

[0018] Further, the specific process of step (4) is as follows: intermediate 2, intermediate 6, and Pd(PPh3)4 are mixed and dissolved in toluene, and heated under nitrogen atmosphere and refluxed. After the reaction is completed, the compound FR01 is separated and purified. The molar ratio of intermediate 2, intermediate 6 and Pd(PPh3)4 is 1:2~3:0.05~0.1.

[0019] Furthermore, the reaction temperature of step (1) is 25℃ and the time is 8 h; the reaction temperature of step (2) is 100℃ and the time is 36 h; the temperature of adding n-butyllithium and continuous stirring in step (3) is -78℃ and the continuous stirring time is 2 h; the reaction temperature of step (4) is 110℃ and the time is 12 h.

[0020] A further improvement of the present invention is as follows:

[0021] Application of the above-mentioned non-fused-ring thiophene multinuclear hole transport materials in perovskite solar cells

[0022] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0023] 1. This invention provides a non-fused-ring thiophene multinucleated hole transport material. The non-fused-ring multinucleated thiophene central core promotes the excellent solubility of HTMs molecules in solvents, effectively enhancing the film quality of the hole transport material. Secondly, the polysulfide atom characteristics improve the interfacial interaction between the hole transport layer and the perovskite layer, passivate perovskite layer interfacial defects, and improve the efficiency of interfacial carrier extraction and separation.

[0024] 2. In non-fused-ring thiophene polynuclear cells, S and O atoms facilitate the formation of non-covalent conformational locking, enabling HTMs to form planar molecular configurations during film formation, enhancing intermolecular dipole interactions, improving conductivity and hole mobility, and achieving compatibility between high-quality film morphology and efficient hole transport.

[0025] 3. The application of the hole material provided by this invention in perovskite solar cells: Test results show that the open-circuit voltage (Voc) is 1.130 V and the short-circuit photocurrent density (Jsc) is 24.07 mA cm⁻¹. -2 With a fill factor (FF) of 0.7860 and a photoelectric conversion efficiency of 21.38%, it has practical significance for improving the efficiency of perovskite solar cells. Attached Figure Description

[0026] Figure 1 The nuclear magnetic resonance spectrum of FR01, a non-fused-ring thiophene multinuclear hole transport material prepared in Example 1, is shown below.

[0027] Figure 2 The thin film morphology of a non-fused-ring thiophene multinuclear hole transport material prepared in Example 1;

[0028] Figure 3 This is a schematic diagram of a perovskite solar cell structure; in the diagram: 1. Metal electrode, 2. Hole transport layer, 3. Perovskite photosensitive layer, 4. Electron transport layer, 5. Conductive glass;

[0029] Figure 4 A non-fused-ring thiophene multinuclear hole transport material prepared in Example 1 JV Cyclic voltammetry curve; Detailed Implementation

[0030] The present invention will now be described in detail with reference to the accompanying drawings.

[0031] Example 1:

[0032] This embodiment provides a non-fused-ring thiophene multinuclear hole transport material, the chemical formula of which is shown below:

[0033]

[0034] The preparation method of the above-mentioned hole transport material (as shown in FR01) is as follows:

[0035] S1: Causes compound 1 and NBS to undergo a bromination reaction to generate intermediate 2;

[0036]

[0037] This step is to be specific as follows:

[0038] 2.97 g of compound 1 and 25 mL of tetrahydrofuran were added to a 100 mL single-necked round-bottom flask and cooled in an ice bath. Then, 1.96 g of N-bromosuccinimide was added in portions to the system. The reaction mixture was reacted at 25 °C in the dark for 6 h. The reaction was quenched with water, extracted with ethyl acetate, dried over anhydrous magnesium sulfate, and the solvent was removed by vacuum distillation. The crude product was purified by column chromatography (eluent: petroleum ether / dichloromethane = 10 / 1~3 / 1) to give 2.89 g of intermediate 2 as a yellow solid, with a yield of 77%. The structural characterization data of intermediate 2 are as follows: 1 H NMR (400 MHz, CDCl3): δ 7.11 (d, J = 8.4 Hz, 8H), 6.86 (d, J = 8.4Hz, 8H), 3.82 (s, 12H).

[0039] S2: Causes a coupling reaction between compound 3 and compound 4 to generate intermediate 5;

[0040]

[0041] This step is to be specific as follows:

[0042] Under argon protection, compound 3 (3 mmol, 1.15 g), compound 4 (1.31 g, 4.5 mmol), potassium carbonate (0.62 g, 4.5 mmol), palladium acetate (108 mg, 0.45 mmol), tris(o-methylphenyl)phosphine (298 mg, 0.9 mmol), pentylamino acid (186 mg, 1.8 mmol), and anhydrous N,N-dimethylformamide (10 mL) were added sequentially to a 25 mL sealed high-pressure reaction flask. The reaction mixture was heated to 100 °C and stirred continuously for 36 h. The reaction was quenched with water, extracted with dichloromethane, washed three times with water, dried over anhydrous magnesium sulfate, and the solvent was removed by vacuum distillation. The crude product was purified by column chromatography (eluent: petroleum ether / dichloromethane = 15 / 1~1 / 1) to give 645 mg of intermediate 5, a yellow solid, with a yield of 36%. The structural characterization data of intermediate 5 are as follows: 1 H NMR (400 MHz, CDCl3): δ 7.46 (d, J = 8.2 Hz, 2H), 7.12-7.10 (m, 6H), 6.99-6.96 (m, 3H), 6.86 (d, J = 8.4 Hz, 4H), 4.07 (t, J= 6.4Hz, 2H), 3.83(s, 6H), 1.40-1.29 (m, 9H), 0.93-0.91 (m, 6H).

[0043] S3: Causes intermediate 5 to undergo a substitution reaction to generate intermediate 6;

[0044]

[0045] This step is to be specific as follows:

[0046] Under argon protection and at -78 °C, 594 mg of intermediate 5 and anhydrous tetrahydrofuran were added to a round-bottom reaction flask, followed by dropwise addition of n-butyllithium (2.5 mol / L). After the addition was complete, the reaction mixture was allowed to react at -78 °C for 2 h. Tributyltin chloride was then added to the reaction mixture, with the molar ratio of intermediate 5, n-butyllithium, and tributyltin chloride being 1:1.2:1.2. The reaction mixture was slowly heated to room temperature and allowed to react for another 12 h. The reaction was then quenched with ice water, extracted with ethyl acetate, dried over anhydrous magnesium sulfate, and the solvent was removed by vacuum distillation to obtain crude intermediate 6, which did not require purification and was used directly in the next reaction step.

[0047] S4: Intermediate 2 and intermediate 6 undergo a Stille coupling reaction to generate compound FR01, which is a nonplanar thiophene multinuclear hole transport material.

[0048]

[0049] This step is to be specific as follows:

[0050] Under argon protection, intermediate 6, 300 mg of intermediate 2, 28 mg of tetrakis(triphenylphosphine)palladium, and 15 mL of toluene were sequentially added to a three-necked round-bottom flask. The reaction system was heated to 110 °C and reacted for 8 h. After cooling to room temperature, the solvent was removed by vacuum distillation. The crude product was purified by column chromatography (eluent: petroleum ether / dichloromethane = 5 / 1~1:2) to obtain 370 mg of compound FR01, a yellow solid. Compound FR01 is a nonplanar thiophene multinuclear hole transport material. The overall yield of the two-step reaction (S3 and S4) was 52%. The structural characterization data of compound FR01 are as follows: 1 H NMR (400 MHz, CDCl3): δ 8.21 (s, 4H), 7.72 (m,4H), 7.05-7.01 (m, 20H), 6.87-6.85 (m, 16H), 4.22 (m, 4H), 3.84 (s, 24H), 1.42-1.37 (m, 8H), 1.33-1.29 (m, 10H), 0.98-0.93 (m, 12H).

[0051] Example 2:

[0052] This embodiment is largely the same as Embodiment 1, with the main difference being:

[0053] S1: Synthesis of intermediate 2;

[0054] 2.97 g of compound 1 and 25 mL of tetrahydrofuran were added to a 100 mL single-necked round-bottom flask and cooled in an ice bath. Then, 2.23 g of N-bromosuccinimide was added in portions to the system, and the reaction mixture was reacted at 25 °C in the dark for 6 h. The reaction was quenched with water, extracted with ethyl acetate, dried over anhydrous magnesium sulfate, and the solvent was removed by vacuum distillation. The crude product was purified by column chromatography (eluent: petroleum ether / dichloromethane = 10 / 1~3 / 1) to give 3.08 g of intermediate 2 as a yellow solid, with a yield of 82%.

[0055] S2: Synthesis of intermediate 5;

[0056] Under argon protection, compound 3 (3 mmol, 1.15 g), compound 4 (1.75 g, 6 mmol), potassium carbonate (0.62 g, 4.5 mmol), palladium acetate (108 mg, 0.45 mmol), tris(o-methylphenyl)phosphine (298 mg, 0.9 mmol), pentylamino acid (186 mg, 1.8 mmol), and anhydrous N,N-dimethylformamide (10 mL) were added sequentially to a 25 mL sealed high-pressure reaction flask. The reaction mixture was heated to 100 °C and stirred continuously for 48 h. The reaction was quenched with water, extracted with dichloromethane, washed three times with water, dried over anhydrous magnesium sulfate, and the solvent was removed by vacuum distillation. The crude product was purified by column chromatography (eluent: petroleum ether / dichloromethane = 15 / 1~1 / 1) to give 699 mg of intermediate 3, a yellow solid, with a yield of 39%.

[0057] S3: Synthesis of intermediate 6;

[0058] Under argon protection and at -78 °C, 594 mg of intermediate 5 and anhydrous tetrahydrofuran were added to a round-bottom reaction flask, followed by dropwise addition of n-butyllithium (2.5 mol / L). After the addition was complete, the reaction mixture was allowed to react at -78 °C for 2 h. Tributyltin chloride was then added to the reaction mixture, with the molar ratio of intermediate 5, n-butyllithium, and tributyltin chloride being 1:1.2:1.2. The reaction mixture was slowly heated to room temperature and allowed to react for another 12 h. The reaction was then quenched with ice water, extracted with ethyl acetate, dried over anhydrous magnesium sulfate, and the solvent was removed by vacuum distillation to obtain crude intermediate 6, which did not require purification and was used directly in the next reaction step.

[0059] S4: Synthesis of compound FR01;

[0060] Under argon protection, intermediate 6, 300 mg of intermediate 2, 46 mg of tetrakis(triphenylphosphine)palladium, and 15 mL of toluene were added sequentially to a three-necked round-bottom flask. The reaction system was heated to 110 °C and reacted for 8 h. After cooling to room temperature, the solvent was removed by vacuum distillation. The crude product was purified by column chromatography (eluent: petroleum ether / dichloromethane = 5 / 1~1:2) to obtain 398 mg of compound FR01, a yellow solid. Compound FR01 is a nonplanar thiophene polynuclear hole transport material. The total yield of the two-step reaction (S3 and S4) was 56%. Example

[0061] Figure 2 The morphology of the thin film of this material was tested by scanning electron microscopy (SEM) and atomic force microscopy (AFM), which showed that the material formed a uniform and smooth hole transport layer film on the perovskite surface, which is beneficial to the extraction and separation of holes at the interface.

[0062] This embodiment provides an application of FR01, a non-planar thiophene multinuclear hole transport material prepared in Example 1, in the fabrication of perovskite solar cells. For example... Figure 3 This is a schematic diagram of the perovskite solar cell fabricated in Example 1. The specific method of use is the same as in the literature B. Wu, Q. Fu, L. Sun, et al. Conjugation Engineering of Spiro-Based Hole Transport Materials for Efficient and Stable Perovskite Solar Cells. ACS Energy Lett. 2022, 7, 2667-2676. The test light source was AM1.5 (solar simulator-Oriel 91160-1000, 300W), and data acquisition was performed using a Keithley 2400 digital source meter. The test results are shown below. Figure 4 The open-circuit voltage (Voc) is 1.130 V, and the short-circuit photocurrent density (Jsc) is 24.07 mA cm⁻¹. -2 The fill factor (FF) is 0.7860 and the photoelectric conversion efficiency is 21.38%.

[0063] The above embodiments are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be construed as limiting the scope of protection of the present invention. All equivalent transformations or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A non-fused-ring thiophene multinuclear hole transport material, characterized in that, The molecular structure is shown in FR01: 。 2. The method for preparing a nonplanar thiophene multinuclear hole transport material as described in claim 1, characterized in that, Includes the following steps: (1) Cause compound 1 to undergo bromination to generate intermediate 2; (2) To cause compound 3 to undergo a coupling reaction with compound 4 to generate intermediate 5; (3) Cause intermediate 5 to undergo a substitution reaction to generate intermediate 6; (4) Intermediate 2 and intermediate 6 undergo a Stille coupling reaction to generate compound FR01, which is a non-planar thiophene polynuclear hole transport material. The reaction equation is shown below: 。 3. The method for preparing a nonplanar thiophene multinuclear hole transport material according to claim 2, characterized in that: The specific process of step (1) is as follows: Compound 1 is reacted with N-bromosuccinimide (NBS) in the solvent tetrahydrofuran to generate intermediate 2; the molar ratio of compound 1 to NBS is 1:2~3.

4. The method for preparing a non-fused-ring thiophene multinuclear hole transport material according to claim 2, characterized in that: The specific process of step (2) is as follows: Compound 3 and Compound 4, potassium carbonate, pivalic acid, palladium acetate and tris(o-methylphenyl)phosphine are mixed and dissolved in N,N-dimethylformamide (DMF), and heated and reacted under a nitrogen atmosphere. After the reaction is completed, intermediate 5 is separated and purified. The molar ratio of Compound 3, Compound 4, palladium acetate, tris(o-methylphenyl)phosphine, pivalic acid and potassium carbonate is 1: 2~3: 0.1~0.2: 0.2~0.4: 0.2~1: 1~2.

5. The method for preparing a nonplanar thiophene multinuclear hole transport material according to claim 2, characterized in that: The specific process of step (3) is as follows: intermediate 5 is dissolved in anhydrous tetrahydrofuran, n-butyllithium in n-hexane solution is added dropwise under cooling conditions, and stirring is continued at low temperature. Then, tributyltin chloride is added, the reaction solution is heated to room temperature, and stirring is continued overnight. After the reaction is completed, the solution is quenched with water, extracted with organic solvent and dried, and the solvent is removed under reduced pressure to obtain intermediate 6. The molar ratio of intermediate 5, n-butyllithium and tributyltin chloride is 1:1.1~1.5:1.1~1.

5.

6. The method for preparing a nonplanar thiophene multinuclear hole transport material according to claim 2, characterized in that: The specific process of step (4) is as follows: intermediate 2, intermediate 6, and Pd(PPh3)4 are mixed and dissolved in toluene, and heated under nitrogen atmosphere and refluxed. After the reaction is completed, the compound FR01 is separated and purified. The molar ratio of intermediate 2, intermediate 6 and Pd(PPh3)4 is 1:2~3:0.05~0.

1.

7. The method for preparing a non-fused-ring thiophene multinuclear hole transport material according to claim 5, characterized in that: The reaction temperature in step (1) is 25℃ and the time is 8 h; the reaction temperature in step (2) is 100℃ and the time is 36 h; the temperature for adding n-butyllithium and continuous stirring in step (3) is -78℃ and the stirring time is 2 h; the reaction temperature in step (4) is 110℃ and the time is 12 h.

8. The application of the non-fused-ring thiophene multinuclear hole transport material as described in claim 1 in perovskite solar cells.

Images