阅读说明：本技术 基于3-烷基并噻吩的七并稠杂环类共轭小分子及其制备方法与应用 (3-alkyl thiophene-based hepta-fused heterocyclic conjugated small molecule and preparation method and application thereof ) 是由 俞江升 唐卫华 张倬涵 刘鑫 周杰 耿仁勇 杨琳强 于 2019-07-24 设计创作，主要内容包括：本发明涉及一种基于3-烷基并噻吩的七并稠环单元的A-D-A共轭小分子受体材料的制备方法及其在有机太阳能电池中的应用。所述方法以2,5-二溴对苯二甲酸二乙酯为原料,经过一系列偶联、成环、缩合等反应步骤,合成了具有大的平面结构的小分子。本发明的基于3-烷基并噻吩的七并稠环单元的A-D-A共轭小分子具有良好的热稳定性、溶解性和成膜性；紫外-可见光吸收光谱和电化学测试表明该类化合物的光学带隙适中,在可见光和近红外光区有着很好的吸收；同时HOMO和LUMO能级较低。是一种具有潜力的有机太阳能电池受体材料或钙钛矿电池电子传输层材料。(The invention relates to a preparation method of an A-D-A conjugated micromolecule receptor material based on a hepta-condensed ring unit of 3-alkyl thiophene and application of the A-D-A conjugated micromolecule receptor material in an organic solar cell. According to the method, 2, 5-dibromo diethyl terephthalate is used as a raw material, and a series of reaction steps such as coupling, cyclization, condensation and the like are performed to synthesize the micromolecule with a large planar structure. The A-D-A conjugated micromolecule of the hepta-condensed ring unit based on the 3-alkyl bithiophene has good thermal stability, solubility and film-forming property; ultraviolet-visible light absorption spectrum and electrochemical tests show that the optical band gap of the compound is moderate, and the compound has good absorption in visible light and near infrared regions; while the HOMO and LUMO energy levels are lower. The material is a potential organic solar cell receptor material or perovskite cell electron transport layer material.)

1. The seven fused heterocyclic conjugated micromolecules based on the 3-alkyl thiophene are characterized by having the following structures:

R₁an aralkyl group having 1 to 10 carbon atoms;

R₂is a straight chain or branched chain alkyl with 1-20 carbon atoms;

a is an electron withdrawing unit selected from the following structures:

in the structure A, R₃The electron donating group comprises alkyl and alkoxy with 1-4 carbon atoms; r₄Is an electron-withdrawing group and comprises F, Cl, Br, I and CN.

2. The conjugated small molecule of claim 1, wherein R is₁Including alkylphenyl, alkoxyphenyl, alkylthienyl and alkoxythienyl.

3. The method for preparing the conjugated small molecule according to claim 1 or 2, comprising the following steps:

(1) a step of performing Stille coupling reaction on 2, 5-dibromo diethyl terephthalate and the compound 1 under the catalysis of tetratriphenyl phosphonium palladium to prepare a compound 2,

(2) the 4-alkyl-1-aryl lithium and the compound 2 are subjected to nucleophilic reaction to generate alcohol, and the alcohol is dehydrated under the catalysis of strong acid to prepare a compound 3,

(3) a step of carrying out Vilsmeier-Haake reaction on phosphorus oxychloride and N, N-dimethylformamide, carrying out substitution reaction on the reaction product and a compound 3 to prepare a compound 4,

(4) a step of performing Kenawenger condensation reaction on the compound 4 and the electron-withdrawing unit A under the catalysis of pyridine or beta-alanine to prepare a target product I,

4. the method according to claim 3, wherein in the step (1), the reaction is carried out under the protection of nitrogen, and the solvent of the reaction system is toluene which is dried and has oxygen removed; the temperature of Stile coupling reaction is 100-120 ℃, and the reaction time is 12-48 hours; in terms of mole ratios, diethyl 2, 5-dibromoterephthalate: compound 1: tetrakistriphenylphosphine palladium (1: 2:0.01: 0.1-1: 3:0.03: 0.3).

5. The method according to claim 3, wherein in the step (2), the reaction is carried out under the protection of nitrogen, the temperature of the nucleophilic reaction is 0-30 ℃, and the reaction time is 8-16 hours; the strong acid is concentrated sulfuric acid or concentrated hydrochloric acid; the temperature of catalytic dehydration is between room temperature and 80 ℃, and the reaction time is 0.5 to 10 hours; compound 2: 4-alkyl-1-aryl lithium: the strong acid is 1:4: 0.05-1: 6: 0.2.

6. The method of claim 3, wherein in the step (3), the reaction is carried out under the protection of nitrogen, the temperature of the Vilsmeier-Haake reaction is-10 to 0 ℃, and the reaction time is 0.1 to 3 hours; the temperature of the substitution reaction is 40-90 ℃, and the reaction time is 4-20 hours; in terms of mole ratios, compound 3: phosphorus oxychloride: n, N-dimethylformamide is 1:2:2 to 1:20: 100.

7. The method according to claim 3, wherein in the step (4), the reaction is carried out under the protection of nitrogen, the temperature of the Kernenwell condensation reaction is 65-85 ℃, and the reaction time is 8-48 hours; in terms of mole ratios, compound 4: an electron-withdrawing unit A: pyridine or beta-alanine is 1:2: 0.05-1: 10: 0.2.

8. Use of the conjugated small molecule of claim 1 or 2 as an electron acceptor material in an organic solar cell device.

Technical Field

The invention relates to a 3-alkyl thiophene-based hepta-condensed ring A-D-A conjugated molecule, a preparation method thereof and application of a small molecule as an electron acceptor in an organic solar cell (OPV), belonging to the field of preparation of organic solar materials.

Background

The development and application of renewable energy technology are regarded as the best solution to the problems of greenhouse effect, environmental pollution and energy. The solar energy is inexhaustible. Therefore, how to utilize solar energy and convert the solar energy into clean energy convenient for storage and application is a problem to be solved urgently at present. Silicon-based inorganic photovoltaic devices have already formed mature industrial applications, and because a large amount of electric energy is consumed in the silicon reduction process, the production process is complex, and the unit electric quantity cost is far higher than that of the traditional coal electricity in the life cycle. The organic solar cell has the advantages of easy chemical structure design and synthesis, good flexibility, simple device preparation process and the like, and is widely concerned by domestic and foreign research workers. At present, the photoelectric conversion efficiency of a single-layer organic solar cell breaks through 15% [ Yuan J, Zhang Y, Zhou L, et al.Single-Junction organic solar cell with 15% effect using fused-ring acceptor with electron-concentration core [ J ]. Joule, 2019 ].

In recent years, the photoelectric conversion efficiency of organic solar cells has been actively increased due to the continuous emergence of non-fullerene acceptor materials having excellent properties. The design and development of non-fullerene acceptor materials also become important driving force for the rapid development of organic solar cells. Among the abundant non-fullerene acceptor materials, A-D-A type small molecule materials are most successfully applied. Due to the rigid planar structure, the A-D-A type molecules containing the condensed ring structure have strong intermolecular pi-pi interaction. Alkyl or aralkyl substitution on the fused ring can suppress intermolecular self-aggregation effect to obtain a suitable phase separation size. From the device result, high open-circuit voltage and high short-circuit current are difficult to be obtained, and how to design a material with moderate energy level and wide absorption is still the focus of research on the organic solar cell.

Disclosure of Invention

The invention aims to provide a class of A-D-A conjugated molecules of 3-alkyl thiophene-based hepta-condensed rings, which have strong absorption and proper energy level.

The second purpose of the present invention is to provide a method for synthesizing an A-D-A conjugated molecule based on 3-alkylthiophene hepta-condensed rings.

The invention also aims to provide application of the A-D-A conjugated molecule of the hepta-condensed ring based on the 3-alkyl thiophene in the aspect of polymer solar cells.

The A-D-A conjugated molecule based on 3-alkyl thiophene hepta-condensed ring units has the following general structure:

wherein R is₁An aralkyl group having 1 to 10 carbon atoms, preferably a 4-hexylphenyl group;

R₂is a linear or branched alkyl group having 1 to 20 carbon atoms, preferably a linear alkyl group having 6 carbon atoms;

the group A represents an electron withdrawing unit, the group A being selected from the following structures:

in the structure A, R₃The electron-donating group comprises alkyl and alkoxy with 1-4 carbon atoms, preferably methyl; r₄Is an electron-withdrawing group, including F, Cl, Br, I, CN, preferably F, Cl.

The preparation method of the conjugated molecule compound comprises the following steps:

(1) a step of performing Stille coupling reaction on 2, 5-dibromo diethyl terephthalate and the compound 1 under the catalysis of tetratriphenyl phosphonium palladium to prepare a compound 2,

(2) the 4-alkyl-1-aryl lithium and the compound 2 are subjected to nucleophilic reaction to generate alcohol, and the alcohol is dehydrated under the catalysis of strong acid to prepare a compound 3,

(3) a step of carrying out Vilsmeier-Haake reaction on phosphorus oxychloride and N, N-dimethylformamide, carrying out substitution reaction on the reaction product and a compound 3 to prepare a compound 4,

(4) a step of performing Kenawenger condensation reaction on the compound 4 and the electron-withdrawing unit A under the catalysis of pyridine or beta-alanine to prepare a target product I,

further, in the step (1), the reaction is carried out under the protection of nitrogen, and the solvent of the reaction system is dry and deoxygenated toluene; the temperature of Stile coupling reaction is 100-120 ℃, and the reaction time is 12-48 hours; in terms of mole ratios, diethyl 2, 5-dibromoterephthalate: compound 1: tetrakistriphenylphosphine palladium (1: 2:0.01: 0.1-1: 3:0.03: 0.3).

Further, in the step (2), the reaction is carried out under the protection of nitrogen, the temperature of nucleophilic reaction is 0-30 ℃, and the reaction time is 8-16 hours; the strong acid is concentrated sulfuric acid or concentrated hydrochloric acid; the temperature of catalytic dehydration is between room temperature and 80 ℃, and the reaction time is 0.5 to 10 hours; compound 2: 4-alkyl-1-aryl lithium: the strong acid is 1:4: 0.05-1: 6: 0.2.

Further, in the step (3), the reaction is carried out under the protection of nitrogen, the temperature of the Vilsmeier-Haake reaction is-10-0 ℃, and the reaction time is 0.1-3 hours; the temperature of the substitution reaction is 40-90 ℃, and the reaction time is 4-20 hours; in terms of mole ratios, compound 3: phosphorus oxychloride: n, N-dimethylformamide is 1:2:2 to 1:20: 100.

Further, in the step (4), the reaction is carried out under the protection of nitrogen, the temperature of the Kenawenger condensation reaction is 65-85 ℃, and the reaction time is 8-48 hours; in terms of mole ratios, compound 4: an electron-withdrawing unit A: pyridine or beta-alanine is 1:2: 0.05-1: 10: 0.2.

The seven fused heterocyclic A-D-A conjugated molecule based on the 3-alkyl thiophene has stronger absorption, higher charge transmission performance and proper electronic energy level, and can be used as an active layer electron acceptor material for light capture to be applied to an organic solar cell.

Compared with the prior art, the invention has the remarkable advantages that:

1. the synthesized hepta-fused ring conjugated molecule has moderate alkyl chain length, ensures that the hepta-fused ring conjugated molecule is easy to dissolve in organic solvents such as dichloromethane, chloroform, chlorobenzene and the like, and is convenient for spin coating.

2. The synthesized conjugated molecules of the hepta-condensed rings have good thermal stability, and the decomposition temperature (weight loss 5%) exceeds 300 ℃.

3. The initial absorption wavelength of the synthesized conjugated molecules of the hepta-fused ring exceeds 800nm, and the synthesized conjugated molecules can be well complemented with the spectrum of the wide-band gap polymer.

4. The synthesized conjugated molecule of the hepta-condensed ring has proper energy level and is suitable for an electron acceptor material in an organic solar cell.

5. The synthesized conjugated molecule of the hepta-condensed ring is used as an electron acceptor material to show good photoelectric property in an organic solar cell.

Drawings

FIG. 1 shows the NMR spectrum of 3-alkylthiophene-based hepta-fused ring conjugated molecule ITC6-IC of example 2 of the present invention.

FIG. 2 is a carbon nuclear magnetic resonance spectrum of 3-alkylthiophene-based hepta-fused ring conjugated molecule ITC6-IC of example 2 of the present invention.

FIG. 3 is a high resolution mass spectrum of 3-alkylthiophene based hepta-fused ring conjugated molecule ITC6-IC of example 2 of the present invention.

FIG. 4 is a NMR spectrum of 3-alkylthiophene-based hepta-fused ring conjugated molecule ITC6-4F of example 4 of the present invention.

FIG. 5 is a carbon nuclear magnetic resonance spectrum of 3-alkylthiophene-based hepta-fused ring conjugated molecule ITC6-4F of example 4 of the present invention.

FIG. 6 is a nuclear magnetic resonance fluorine spectrum of 3-alkylthiophene-based hepta-fused ring conjugated molecule ITC6-4F of example 4 of the present invention.

FIG. 7 is a high resolution mass spectrum of 3-alkylthiophene based hepta-fused ring conjugated molecule ITC6-4F of example 4 of the present invention.

FIG. 8 is a NMR spectrum of 3-alkylthiophene-based hepta-fused ring conjugated molecule ITC6-Cl of example 4 of the present invention.

FIG. 9 is a carbon nuclear magnetic resonance spectrum of 3-alkylthiophene-based hepta-fused ring conjugated molecule ITC6-Cl of example 4 of the present invention.

FIG. 10 is a high resolution mass spectrum of 3-alkylthiophene based hepta-fused ring conjugated molecule ITC6-Cl of example 4 of the present invention.

FIG. 11 shows UV-VIS absorption spectra of 3-alkylthiophene-based hepta-fused ring conjugated molecules ITC6-IC and ITC6-4F according to examples 2 and 4 of the present invention.

FIG. 12 shows cyclic voltammograms of 3-alkylthiophene-based hepta-fused ring conjugated molecules ITC6-IC and ITC6-4F according to examples 2 and 4 of the present invention.

FIG. 13 shows the thermogravimetric curves of 3-alkylthiophene-based hepta-fused ring conjugated molecules ITC6-IC and ITC6-4F in examples 2 and 4 of the present invention.

FIG. 14 is a J-V curve for a solar cell based on 3-alkylthiophene hepta-fused ring conjugated molecules ITC6-4F of example 2 of the present invention.

Detailed Description

The invention provides a synthesis method of two A-D-A conjugated molecules of a hepta-fused heterocycle based on 3-alkyl thiophene. In describing embodiments of the invention, specific terminology is employed for the sake of clarity. However, the invention is not intended to be limited to the specific terminology so selected. It is to be understood that each specific element includes all technical equivalents which operate in a similar manner to accomplish a similar purpose.

The chemical structure of the A-D-A conjugated molecule is represented by 500M nuclear magnetic resonance and high resolution mass spectrum, the electrochemical property is represented by cyclic voltammetry, and the photophysical property is researched by ultraviolet absorption spectrum.

The preparation method of the nine-membered fused ring unit conjugated molecule based on the pyrrolodithiophene comprises the following steps: