A type of small molecule receptor based on two-dimensional side chain substituted benzodithiophenedione and its preparation method and application

Abstract

The present invention relates to a small molecule receptor based on two-dimensional side chain substitution of benzodithiophenedione and a preparation method and application thereof. Through two-dimensional substitution of the side chain of benzodithiophenedione, thiophene, dithienocyclopentadiene and other bridge units are coupled, and electron-deficient units are connected to obtain the corresponding small molecule receptor material. The material provided by the present invention has good solution processability and self-assembly ability. It can be used to make optoelectronic functional devices, including organic photovoltaic cells.

Description

Technical Field

[0001] The present invention relates to a small molecule used in the field of optoelectronic materials and devices, and more specifically to a new type of small molecule receptor based on two-dimensional side chain substituted benzodithiophenedione that can be used in solar cells. Background Art

[0002] Organic solar cells have attracted much attention from researchers because they are expected to be industrially produced. In organic solar cells, the active material is the key factor that determines the efficiency of the cell. The donor material of the active layer is generally a conjugated polymer or a conjugated small molecule; while the acceptor material has gone through the fullerene era and ushered in the non-fullerene era. Although the condensed-ring non-fullerene acceptor material has excellent performance, it has many synthesis steps and high cost. The simple condensed-ring non-fullerene small molecule acceptor material provided by the present invention has low synthesis complexity and cost, and has good industrial prospects in terms of photovoltaic performance and cost.

[0003] In particular, the benzodithiophenedione unit, as a new type of electron-deficient unit, has good planarity, electron-withdrawing ability and self-assembly performance. It has received widespread attention in recent years, and the photovoltaic performance of related materials has also developed rapidly. Many high-performance DA alternating copolymer donor materials such as PM6 and PM7 are prepared with benzodithiophenedione as the electron-deficient unit. In addition, the benzodithiophenedione unit also has good performance in the field of non-fullerene acceptor materials. Chen Junwu's research group prepared new non-fullerene acceptors BDDEH-4F and BDDBO-4F by introducing the benzodithiophenedione unit as the central core of a simple condensed ring acceptor material. The non-covalent bonds inside the BDDHEH-4F molecule ensure good planarity and molecular stacking, which is beneficial to the active layer material to achieve good charge transfer and active layer morphology. Finally, when it is blended with PM6 to prepare organic solar cells, good battery device performance is achieved: open circuit voltage of 0.88 volts, short circuit current of 22.57 milliamperes per square centimeter, fill factor of 63.38%, and energy conversion efficiency of 12.59%.

[0004] For the active layer materials of organic solar cells, the introduction of two-dimensional conjugated aromatic side chains is an important molecular modification design method, which has a positive effect on the photovoltaic performance improvement of ITIC series receptors and Y series receptors. Generally speaking, the introduction of large two-dimensional conjugated aromatic side chains can improve the energy level of the material, improve the crystallization performance and active layer morphology, thereby effectively improving the exciton dissociation and charge transfer performance inside the active layer, and improving the device performance of organic solar cells. At the same time, the introduction of large aromatic side chains helps to limit the torsion inside the molecule to a certain extent, inhibit the generation of molecular isomers, and improve the filling factor and stability of the device. However, summarizing the relevant chemical modification designs of the benzodithiophene dione unit, it can be found that the current modification design for benzodithiophene dione is mainly the modification of ordinary alkyl side chains, and the two-dimensional conjugated aromatic side chains have not yet been applied to the benzodithiophene dione unit. This patent will fill this gap. Summary of the invention

[0005] The purpose of the present invention is to address the deficiencies of the prior art and provide a class of small molecule receptors based on two-dimensional side chain substituted benzodithiophenedione, which have good absorption and energy level properties and can be used to prepare high-efficiency optoelectronic functional devices.

[0006] The present invention also aims to provide a green preparation method for a class of small molecule receptors based on two-dimensional side chain substituted benzodithiophenedione.

[0007] The present invention also aims to provide the application of the small molecule receptor based on two-dimensional side chain substituted benzodithiophenedione in organic photovoltaic cells.

[0008] A class of small molecule receptors based on two-dimensional side chain substituted benzodithiophenedione of the present invention has the following structure:

[0009]

[0010] Among them, Ar1 is an electron-donating aromatic ring such as a benzene ring, Ar2 is a bridge unit aromatic ring such as dithienylcyclopentadiene, and Ar3 is an electron-deficient aromatic ring such as dicyanoindanone.

[0011] The preparation method of the small molecule receptor based on two-dimensional side chain substituted benzodithiophenedione is to obtain the key raw material of two-dimensional side chain substituted benzodithiophenedione, couple it with different electron bridge units, and then connect it with electron-deficient units to prepare it.

[0012] The structure of the small molecule receptor used is based on two-dimensional side chain substituted benzodithiophenedione:

[0013]

[0014] Among them, Ar1 is an electron-donating aromatic ring such as a benzene ring, Ar2 is a bridge unit aromatic ring such as dithienylcyclopentadiene, and Ar3 is an electron-deficient aromatic ring such as dicyanoindanone.

[0015] Ar1 is:

[0016]

[0017] Ar2 is:

[0018]

[0019] Ar3 is:

[0020]

[0021] R 1 -R 7 For: C 1 -C 24 An alkyl chain (including branched side chains) of 3 ,CH 3 O,CH 3 ; Y is selected from: F, Cl, Br, I, CF 3 ,CH 3 O,CH 3。

[0022] A class of small molecule receptors based on two-dimensional side chain substituted benzodithiophenedione can be used to prepare organic photovoltaic cells. Due to the good solution processability and self-assembly ability provided by the present invention, it can be used to make optoelectronic functional devices, including organic photovoltaic cells.

[0023] A method for preparing a small molecule receptor based on two-dimensional side chain substituted benzodithiophene dione, wherein the method for preparing the two-dimensional side chain substituted benzodithiophene dione is to obtain a small molecule raw material of two-dimensional side chain substituted benzodithiophene dione, couple it with different electron bridge units, and then connect it with an electron-deficient unit to prepare it.

[0024] In the above method, the two-dimensional side chain substituted benzodithiophenedione is obtained by selective Friedel-Crafts acylation reaction at room temperature, and the reaction adopts an inert atmosphere, which is argon or high-purity nitrogen.

[0025] In the above method, the coupling reaction of the two-dimensional side chain substituted benzodithiophenedione and the bridge unit is obtained by a direct aromatization coupling reaction using carbon-hydrogen activation at 110°C for 12 hours. The reaction adopts an inert atmosphere, which is argon or high-purity nitrogen. No toxic tin reagents are required, and the reaction method adopted has a high degree of green chemistry.

[0026] In the above method, the material is obtained by reacting with the terminal compound through a classical condensation reaction at 65°C, and the reaction adopts an inert atmosphere, which is argon or high-purity nitrogen. Small molecule receptor materials containing two-dimensional side chain substituted benzodithiophenedione, including brominated small molecule materials (which can be used for polymer material preparation), are prepared efficiently and greenly.

[0027] Compared with the prior art, the present invention has the following advantages and technical effects:

[0028] The present invention provides a novel method for preparing a class of small molecule receptors based on two-dimensional side chain substituted benzodithiophene dione, which is original and greatly enriches the small molecule receptor materials based on two-dimensional side chain substituted benzodithiophene dione, and such materials have high green synthesis degree and green solvent processing potential, thereby providing more material selection and processing methods for the application of these materials in optoelectronic devices. In addition, the class of small molecule receptors based on two-dimensional side chain substituted benzodithiophene dione provided by the present invention has a high photoelectric conversion efficiency in photovoltaic devices, and is also expected to achieve industrial production through the Roll to Roll process. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is the NMR image of BDDPHC4-4F;

[0030] Figure 2 This is the BDDPH-4F NMR image;

[0031] Figure 3 It is the absorption diagram of BDDPH-4F solution and film;

[0032] Figure 4 This is the electrochemical curve of BDDPHC4-4F;

[0033] Figure 5 It is the electrochemical curve of BDDPH-4F;

[0034] Figure 6 This is the device current-voltage curve. DETAILED DESCRIPTION

[0035] The following is a further description of the preparation of a type of small molecule receptor based on two-dimensional side chain substituted benzodithiophenedione and the preparation of a device using the small molecule receptor as an optically active layer of a solar cell in conjunction with specific examples. However, the scope of protection claimed by the present invention is not limited to the scope of the examples.

[0036] Example 1

[0037] The preparation of compound BDDPHC4-4F, the reaction formula is as follows:

[0038]

[0039] Synthesis route of compound 2:

[0040] Under nitrogen protection, 1 (3.18 g, 15 mmol) and thiophene-2,5-diboronic acid dipinacol ester (2.0 g, 6 mmol) were dissolved in ultra-dry o-xylene, cesium carbonate (9.77 g, 30 mmol) was added, and tetrakis(triphenylphosphine)palladium (0.31 g, 0.26 mmol) was added after sufficient stirring, and the temperature was raised to 110 ° C overnight in the dark. After the reaction was completed, water was added to quench the reaction, and after extraction with dichloromethane three times, anhydrous sodium sulfate was added to the organic phase, filtered, and the solvent was removed by rotary evaporator. Petroleum ether was used as the eluent, and further purified by silica gel chromatography to obtain white solid C (1.68 g, 3.6 mmol) with a yield of 60%. 1H NMR (400MHz, CDCl3) δ (ppm): 7.54 (d, J = 8.0Hz, 2H), 7.23 (s, 1H), 7.20 (d, J = 8.0Hz, 2H), 2.64-2.60 (m, 2H), 1.65-1.58 (m, 2H), 1.42-1.33 (m, 2H), 0.96-0.92(m,3H).

[0041] Synthesis route of compound 3:

[0042] Under nitrogen protection, 2,5-dibromothiophene-3,4-dicarboxylic acid (1.19 g, 3.6 mmol) was dissolved in 30 ml of dichloromethane, 1 ml of ultra-dry DMF was added, and after sufficient stirring, oxalyl chloride (1.83 g, 14.4 mmol) was added dropwise at room temperature. After overnight reaction at room temperature, the reactant was desolvated with a rotary evaporator, and the next step was directly performed without further treatment. The intermediate product was dissolved in 30 ml of ultra-dry dichloromethane, compound 2 (1.68 g, 3.6 mmol) was added, and then aluminum chloride (1.92 g, 14.4 mmol) was added in batches under ice bath conditions. After the addition was completed, it was slowly returned to room temperature and reacted overnight. After the reaction was completed, the reactant was slowly added to ice water to quench the reaction, and after extraction with dichloromethane three times, the solvent was desolvated with a rotary evaporator. The product was further purified by silica gel chromatography using dichloromethane and petroleum ether as eluents to obtain a yellow solid 3 (1.5 g, 2.34 mmol) with a yield of 65%. 1H NMR (400 MHz, CDCl3) δ (ppm): 7.56 (d, J = 6.4 Hz, 4H), 7.29 (d, J = 6.8 Hz, 4H), 2.69-2.66 (m, 4H), 1.69-1.63 (m, 4H), 1.45-1.38 (m, 4H), 0.98-0.95 (m, 4H)

[0043] Synthesis route of compound 4:

[0044] Under nitrogen protection, 3 (0.5 g, 0.8 mmol) and 4,4-di(2-ethylhexyl)-dithienocyclopentadiene-1-carboxaldehyde (0.94 g, 2.2 mmol) were dissolved in 25 ml of ultra-dry o-xylene, and then cesium carbonate (2.1 g, 6.4 mmol), pivalic acid (0.08 g, 0.8 mmol), tris(dibenzylideneacetone dipalladium) (0.07 g, 0.08 mmol) and tris(2-methoxyphenyl)phosphine (0.06 g, 0.16 mmol) were added in sequence. After sufficient stirring, the temperature was raised to 110 ° C and reacted overnight. After the reaction was completed, the reactant was poured into water to quench, extracted three times with dichloromethane, and the solvent was removed by rotary evaporator. Dichloromethane and petroleum ether were used as eluents, and further purified by silica gel chromatography to obtain red solid 4 (0.73 g, 0.54 mmol) with a yield of 68%. 1H NMR (400MHz, CDCl3) δ (ppm): 9.865 (s, 2H), 7.74-7.72 (m, 2H), 7.62 (d, J = 8Hz, 4H), 7.59 (d, J = 4Hz, 2H), 7.29 (d, J = 8Hz, 4H), 2.73-2.69(m,4H),1.99-1.90(m,8H),1.73-1.65(m,4H), 1.47-1.41(m,4H)1.00-0.96(m,36H),0.77-0.73(m,12H), 0.98-0.95(m,12H)

[0045] Synthesis route of compound 5:

[0046] Under nitrogen protection, 4 (0.15 g, 0.11 mmol) was dissolved in 30 ml of chloroform, and then 5,6-difluoro-3-(dicyanomethylene)indone (75.96 mg, 0.33 mmol) and 1 ml of pyridine were added, and the temperature was raised to 60 ° C and refluxed for 4 hours in the dark. After the reaction, the reactant was poured into ice methanol for recrystallization, and then the crude product was obtained by suction filtration, and then a mixed solution of dichloromethane and petroleum ether was used as an eluent, and further purified by a silica gel chromatography column, and the product was recrystallized in methanol, ethanol, and isopropanol as solvents, and finally a blue-black solid product (158 mg, 0.09 mmol) was obtained with a yield of 82%. 1H NMR (400MHz, CDCl3) δ (ppm): 8.92 (s, 2H), 8.558-8.525 (m, 2H), 7.78-7.75 (d, J = 8Hz, 2H), 7.69 (d, J = 4Hz, 4H), 7.65 (d, J = 4Hz, 4H), 7.35 (d, J = 4Hz, 4H), 2.77-2.74 (m, 4H), 2.03-1.96 (m, 8H), 1.75-1.70 (m, 4H), 1.50-1.43 (m, 4H) 1.02-0.98 (m, 38H), 0.75-0.74 (m, 16H), 0.65-0.62 (m, 12H). The specific NMR diagram is as follows Figure 1 shown.

[0047] We used ferrocene as a reference to conduct an electrochemical energy level test on the small molecule prepared in Example 1. The specific test diagram is shown in FIG. Figure 4 As shown, the electrochemical energy levels HOMO and LUMO are calculated by formula to be -5.59 eV and -3.89 eV respectively.

[0048] Example 2

[0049] The preparation of small molecule BDDPH-4F, the reaction formula is as follows:

[0050]

[0051] Synthesis route of compound 2:

[0052] Under nitrogen protection, 1 (2.34 g, 15 mmol) and thiophene-2,5-diboronic acid dipinacol ester (2.0 g, 6 mmol) were dissolved in ultra-dry o-xylene, cesium carbonate (9.77 g, 30 mmol) was added, and tetrakis(triphenylphosphine)palladium (0.31 g, 0.26 mmol) was added after sufficient stirring, and the temperature was raised to 110 ° C overnight in the dark. After the reaction was completed, water was added to quench the reaction, and after three extractions with dichloromethane, anhydrous sodium sulfate was added to the organic phase, filtered, and the solvent was removed by rotary evaporator. Petroleum ether was used as the eluent, and further purification was carried out by silica gel chromatography to obtain a white solid 2 (0.82 g, 3.48 mmol) with a yield of 58%. 1H NMR(400MHz, CDCl3) δ(ppm):7.64-7.62(m,4H),7.48-7.47(m,6H),7.30(s,2H)

[0053] Synthesis route of compound 3:

[0054] Under nitrogen protection, 2,5-dibromothiophene-3,4-dicarboxylic acid (1.15g, 3.48mmol) was dissolved in 30ml of dichloromethane, 1ml of ultra-dry DMF was added, and after sufficient stirring, oxalyl chloride (1.77g, 14mmol) was added dropwise at room temperature. After overnight reaction at room temperature, the reactant was desolvated by rotary evaporator, and the next step was directly carried out without further treatment. The intermediate product was dissolved in 30ml of ultra-dry dichloromethane, 2 (0.82g, 3.48mmol) was added, and then aluminum chloride (1.86g, 14mmol) was added in batches under ice bath conditions. After the addition was completed, the mixture was slowly returned to room temperature and reacted overnight. After the reaction was completed, the reactant was slowly added to ice water to quench the reaction, extracted three times with dichloromethane, and then desolvated by rotary evaporator. The product was further purified by silica gel chromatography using dichloromethane and petroleum ether as eluents to obtain a yellow solid 3 (1.11 g, 2.1 mmol) with a yield of 60%. 1H NMR (400 MHz, CDCl3) δ (ppm): 7.64-7.63 (m, 4H), 7.48-7.47 (m, 6H)

[0055] Synthesis route of compound 4

[0056] Under nitrogen protection, 3 (0.43 g, 0.8 mmol) and 4,4-di(2-ethylhexyl)-dithienocyclopentadiene-1-carboxaldehyde (0.94 g, 2.2 mmol) were dissolved in 25 ml of ultra-dry o-xylene, and then cesium carbonate (2.1 g, 6.4 mmol), pivalic acid (0.08 g, 0.8 mmol), tris(dibenzylideneacetone dipalladium) (0.07 g, 0.08 mmol) and tris(2-methoxyphenyl)phosphine (0.06 g, 0.16 mmol) were added in sequence. After sufficient stirring, the temperature was raised to 110 ° C and reacted overnight. After the reaction was completed, the reactant was poured into water to quench, extracted three times with dichloromethane, and the solvent was removed by rotary evaporator. Dichloromethane and petroleum ether were used as eluents, and further purified by silica gel chromatography to obtain red solid 4 (0.68 g, 0.54 mmol) with a yield of 70%. 1H NMR (400MHz, CDCl3) δ (ppm): 9.86 (s, 2H), 7.76-7.74 (m, 2H), 7.69-7.67 (m, 4H), 7.59-7.58 (m, 2H), 7.49-7.48 (m, 6H),2.01-1.93(m,8H),0.99-0.93(m,36H),0.77-0.73(m,16H), 0.65-0.60(m,12H)

[0057] Synthesis route of compound 5:

[0058] Under nitrogen protection, 4 (0.18 g, 0.15 mmol) was dissolved in 30 ml of chloroform, and then 5,6-difluoro-3-(dicyanomethylene)indone (0.1 g, 0.45 mmol) and 1 ml of pyridine were added, and the temperature was raised to 60 ° C and refluxed for 4 hours in the dark. After the reaction, the reactant was poured into ice methanol for recrystallization, and then the crude product was obtained by suction filtration, and then a mixed solution of dichloromethane and petroleum ether was used as an eluent, and further purified by a silica gel chromatography column, and the product was successively recrystallized by methanol, ethanol, and isopropanol as solvents, and finally a blue-black solid product (190 mg, 0.12 mmol) was obtained with a yield of 80%. 1H NMR (400MHz, CDCl3) δ (ppm): 8.92 (s, 2H), 8.56-8.52 (m, 2H), 7.78 (d, J = 8Hz, 2H), 7.71-7.68 (m, 8H), 7.54-7.53 (m, 6H), 2.01-1.99 (m, 8H), 1.02-0.93 (m, 32H), 0.76-0.69 (m, 16H), 0.64-0.62 (m, 12H). The specific NMR diagram is as follows Figure 1 shown.

[0059] We also conducted absorption tests and electrochemical energy level tests on the small molecules prepared in Example 2. The specific test diagrams are shown in FIG. Figure 3 as well as Figure 5 As shown. Figure 3 It can be seen that the maximum absorption peaks of the small molecule solution and film obtained in Example 2 are 705 nm and 692 nm respectively. In addition, the electrochemical energy levels HOMO and LUMO calculated by the formula using ferrocene as a reference are -5.59 eV and -3.89 eV respectively.

[0060] Example 3

[0061] Preparation and performance of organic photovoltaic cell devices with ITO as cathode

[0062] The structure of the organic photovoltaic cell device with ITO as the cathode is: ITO / ZnO / polymer donor PM6: small molecule acceptor based on two-dimensional side chain substituted benzodithiophenedione prepared in Example 1 = 1:1 / MoO 3 / Al. The device manufacturing process is as follows: pre-cleaned ITO glass is used as the cathode, and a layer of ZnO with a thickness of 30 nanometers is spin-coated on the ITO glass as the cathode buffer layer. After vacuum drying, a photovoltaic active layer of about 120 nanometers is spin-coated (PM6: small molecule receptor based on two-dimensional side chain substituted benzodithiophenedione prepared in Example 1 = 1:1, weight ratio). After drying at 170°C for 10 minutes, a layer of MoO with a thickness of 5 nanometers is vacuum evaporated. 3 As the anode modification layer. Then vacuum evaporate 100 nanometers of Al metal anode. A negative bias is applied between the ITO and Al metal electrodes, and the battery characteristics are measured under the irradiation of 100 milliwatts per square centimeter AM1.5 simulated sunlight. The open circuit voltage of the battery device is 0.88 volts, the short circuit current is 23.39 milliamperes per square centimeter, the fill factor is 57.12%, and the energy conversion efficiency is 10.26%. The specific JV curve is as follows Figure 6 shown.

[0063] The small molecule receptor based on two-dimensional side chain substituted benzodithiophenedione prepared in Example 2 was used to prepare an organic photovoltaic cell device according to the same process as above. The performance of the cell device was: open circuit voltage of 0.87 volts, short circuit current of 23.11 milliamperes per square centimeter, fill factor of 65.08%, and energy conversion efficiency of 13.10%. The specific JV curve is shown in the figure below: Figure 6 shown.

[0064] Table 1. Summary of photovoltaic performance of small molecule receptors based on two-dimensional side chain substituted benzodithiophenedione prepared in Examples 1 and 2 and small molecule receptors based on one-dimensional alkyl side chain substituted benzodithiophenedione reported in the literature

[0065]

[0066]

[0067] As shown in Table 1, we have summarized the relevant photovoltaic performance parameters of organic photovoltaic cells prepared by blending small molecule receptors based on two-dimensional side chain substituted benzodithiophene dione and small molecule receptors based on one-dimensional alkyl side chain substituted benzodithiophene dione reported in the literature with PM6. It can be seen that the small molecule receptors based on two-dimensional side chain substituted benzodithiophene dione prepared in Examples 1 and 2 have higher energy conversion efficiency, mainly because the related devices have higher short-circuit current and filling factor, which may be due to the introduction of large-volume two-dimensional conjugated aromatic side chains, thereby improving the crystallization properties of the active layer material and the active layer morphology, and improving the dissociation and carrier transport inside the active layer.

Claims

1. A class of small molecule receptors based on two-dimensional side chain substituted benzodithiophenedione, characterized in that: It has the following chemical structure: 。 2. Application of a class of small molecule receptors based on two-dimensional side chain substituted benzodithiophenedione as described in claim 1 in solar cells.

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