Preparation method and application of selenium-containing asymmetric small molecule acceptor material

Abstract

The invention discloses a preparation method and application of a selenium-containing asymmetric small molecule acceptor material, and belongs to the technical field of organic solar cell materials. In order to solve the problem that the photoelectric conversion efficiency (PCE) reported by most selenium-containing SMAs-based binary OSCs still stays between 17% and 18% at present, the invention provides a selenium-containing asymmetric small molecule acceptor material which takes quinoxaline as a core unit, asymmetric selenophen as a unit structure and an electron withdrawing group structure at the tail end. The preparation method comprises the following steps: in a nitrogen atmosphere, taking 4, 7-dibromo-5, 6-dinitrobenzo [c] [1, 2, 5] thiadiazole as a raw material, and carrying out a Stille coupling reaction, a Vismeier-Haack reaction and a Knoevenagel condensation reaction, so as to obtain the 4, 7-dibromo-5, 6-dinitrobenzo [c] [1, 2, 5] thiadiazole derivative. According to the invention, the molecular structure of the selenium-containing SMAs is accurately adjusted, so that the synthesized small molecule receptors AQX-2F-SSe and AQX-2F-SeS have high open-circuit voltage which is more than 0.9 V, and the AQX-2F-SeS has high photoelectric conversion efficiency PCE which is equal to 18.2%.

Description

Technical Field

[0001] The invention belongs to the technical field of organic solar cell materials, and in particular relates to a preparation method of a selenium-containing asymmetric small molecule receptor material and application thereof. Background Art

[0002] Solar energy is one of the most powerful renewable energy sources that can be efficiently harvested by non-biological electronic devices such as solar cells. Organic solar cells (OPVs) have attracted much attention due to their low cost, flexibility, lightness, diverse material structures, and ease of fabrication. In 2015, Lin and Zhan et al. designed and synthesized small molecule acceptors (SMAs) ITICs with ADA structures, including a fused ring electron-donating (D) central unit and two strong electron-accepting (A) ICs (3-(1,1-dicyanomethylene)-1-indanone) end groups. These SMAs have narrow band gaps, strong absorption in the long-wavelength region, suitable aggregation properties, and appropriate energy levels. The PCE of SMA-based OSCs reached 10-14%. Then, Zou et al. designed and synthesized a series of A-DA′DA structured SMAs by inserting pyrrole-fused benzotriazole or benzothiadiazole units into the central fused ring D unit in 2017. The A-DA′DA-type SMA (Y6) showed further red-shifted absorption, enhanced absorbance in the long-wavelength region, and stronger intermolecular interactions. The PCE of OSCs based on A-DA′DA-type SMAs has rapidly increased from 15% in 2019 to over 19% recently. For A-DA′DA-type SMAs, the selection of the A′ unit is important for tuning its photovoltaic properties. Currently, the A′ units used in A-DA′DA-type SMAs are mostly phenyl electron-deficient aromatic rings, including benzothiadiazole (BT), benzotriazole (BTz), and quinoxaline (Qx). Their electron-withdrawing abilities are arranged in the order of BT>Qx>BTz, while Qx and BTz provide positions for introducing alkyl or aryl substituents to fine-tune their optical and electronic properties.

[0003] Quinoxaline-based acceptors have been applied in the fields of photovoltaics and photocatalysis. Compared with benzotriazole and benzothiadiazole units, the quinoxaline moiety can achieve powerful core functionalization in NFAs, providing a high degree of structural modification possibilities. In addition, it helps to construct efficient NFAs with unique molecular packing modes and low reorganization energy.

[0004] In terms of molecular design, the introduction of functional heteroatoms (such as F, Cl, O, S, and Se atoms) into the molecular backbone of organic semiconductors has been shown to effectively regulate the optoelectronic and stacking / aggregation properties of the molecules. Compared with S atoms, Se atoms exhibit stronger electron donor ability due to their larger atomic radius and richer external electrons, which makes them ideal for the simultaneous construction of near-infrared absorbing SMAs with stronger π-π stacking effects. In addition, asymmetric strategies have attracted great attention in recent years. Benefiting from the destruction of structural symmetry, asymmetric receptors can obtain larger dipole moments and stronger intermolecular interactions compared with symmetric receptors, resulting in better carrier transport and photovoltaic performance. The subtle changes brought about by asymmetric receptors make it possible to fine-tune the crystallinity, ππ stacking, and aggregation tendency, thereby achieving the ultimate morphology optimization. Summary of the invention

[0005] In view of the problem that the photoelectric conversion efficiency (PCE) reported by most binary OSCs based on selenium-containing SMAs remains between 17% and 18%, the present invention provides a method for preparing a selenium-containing asymmetric small molecule acceptor material and its application.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A selenium-containing asymmetric small molecule receptor material, wherein the selenium-containing asymmetric small molecule receptor material has quinoxaline as a core unit, an asymmetric selenophene as a unit structure, and an electron-withdrawing group structure at the end, and the chemical structure thereof is as follows:

[0008]

[0009] Wherein, when X is Se, Y is S; the small molecule receptor is named: AQX-2F-SeS, and the chemical structure is:

[0010]

[0011] Wherein, when X is S, Y is Se; the small molecule receptor is named: AQX-2F-SSe, and the chemical structure is:

[0012]

[0013] A method for preparing a selenium-containing asymmetric small molecule receptor material comprises the following steps:

[0014] Step 1, under a nitrogen atmosphere, using 4,7-dibromo-5,6-dinitrobenzo[c][1,2,5]thiadiazole as a raw material, subjecting it to a Stille coupling reaction, and then separating it by column chromatography to obtain a red solid compound 1; the conditions of the Stille coupling reaction are: using toluene as a solvent, using Pd[P(C6H5)3]4 (tetrakistriphenylphosphine palladium) as a catalyst, and performing a reflux reaction with a tin reagent at a temperature of 110 to 130°C;

[0015]

[0016] Step 2, under nitrogen protection, using triphenylphosphine as a reducing agent and o-dichlorobenzene as a solvent, reducing the red solid compound 1 to form a ring; reflux reaction at a temperature of 160-180° C. to obtain a yellow solid compound 2;

[0017]

[0018] Step 3, under nitrogen protection, potassium carbonate and potassium iodide are used as catalysts, DMF is used as solvent, and yellow solid compound 2 and isooctane bromide are refluxed at 140° C. for 4 to 6 hours to obtain yellow oily compound 3;

[0019]

[0020] Step 4, under nitrogen protection, using tetrahydrofuran (THF) as solvent, the yellow oily compound 3 is reduced by LiAlH4, oxidized by DDQ, and then condensed with 4,5-difluoro-1,2-phenylenediamine to obtain a purple-red solid compound 4;

[0021]

[0022] Step 5, under the protection of anhydrous and oxygen-free nitrogen, the purple solid compound 4 is dissolved in 1,2-dichloroethane and then added to a mixed solution of phosphorus oxychloride and dimethylformamide to carry out Vismeier-Haack reaction, stirred at 90° C. overnight, and separated by column chromatography to obtain a red solid compound 5;

[0023]

[0024] Step 6, under nitrogen protection, red solid compound 5 and 2-(5,6-difluoro-3-oxo-2,3-dihydro-1H-inden-1-yl)malononitrile are dissolved in toluene, and then acetic anhydride and trifluoroborane ethyl ether are added to carry out Knoevenagel condensation reaction, and a black solid compound is obtained by column chromatography separation; a solid crude product is obtained by suction filtration, the crude product is dissolved in dichloromethane, the crude product is dry-loaded, and eluted through a silica gel column to obtain a dark solid compound 6;

[0025]

[0026] Wherein, R is an alkyl group; X is selected from: Se, S; Y is selected from: S, Se; and when X is Se, Y is S, the compound 6 is AQX-2F-SeS; when X is S, Y is Se, the compound 6 is AQX-2F-SSe.

[0027] Further, further, in the step 1, the tin reagent is tributyl(6-(2-butyloctyl)thieno[3,2-b]thiophene-2-yl)stannane and tributyl(6-(2-butyloctyl)selenobenzo[3,2-b]thiophene-2-yl)tin, or tributyl(6-(2-butyloctyl)thieno[3,2-b]thiophene-2-yl)stannane and tributyl(3-(2-butyloctyl)selenobenzo[3,2-b]thiophene-5-yl)tin;

[0028] Further, in the step 1, the molar ratio of 4,7-dibromo-5,6-dinitrobenzo[c][1,2,5]thiadiazole, bis(triphenylphosphine)palladium dichloride, tributyl(6-(2-butyloctyl)thieno[3,2-b]thiophene-2-yl)tin ane and tributyl(6-(2-butyloctyl)selenobenz[3,2-b]thiophene-2-yl)tin or tributyl(3-(2-butyloctyl)selenobenz[3,2-b]thiophene-5-yl)tin is 2:0.4:1:1

[0029] Furthermore, in step 2, the molar ratio of the red solid compound 1, triphenylphosphine and o-dichlorobenzene is 1:10:2. The o-dichlorobenzene solvent is anhydrous o-dichlorobenzene.

[0030] Furthermore, in step 3, the molar ratio of the yellow solid compound 2, potassium carbonate, potassium iodide, DMF and isooctane bromide is 1:20:0.2:5:5. The potassium carbonate is anhydrous potassium carbonate; and the DMF is anhydrous DMF.

[0031] Furthermore, in step 4, the molar ratio of LiAlH4, yellow oily compound 3, DDQ and 4,5-difluoro-1,2-phenylenediamine is 20:1:2:5.

[0032] Furthermore, in step 5, the molar ratio of the purple solid compound 4, phosphorus oxychloride, and DMF is 1:10:12.

[0033] Furthermore, in step 6, the molar ratio of the red solid compound 5, 2-(5,6-difluoro-3-oxo-2,3-dihydro-1H-inden-1-yl)malononitrile, acetic anhydride and trifluoroborane ethyl ether (1 mL) is 1:2.5:0.1:0.1.

[0034] Application of a selenium-containing asymmetric small molecule acceptor material in organic solar cells.

[0035] Compared with the prior art, the present invention has the following advantages:

[0036] The present invention precisely adjusts the molecular structure of selenium-containing SMAs, and the synthesized small molecule receptors AQX-2F-SSe and AQX-2F-SeS have high open circuit voltages above (0.9V), wherein AQX-2F-SeS has a high photoelectric conversion efficiency PCE=18.2%. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 Shown is the NMR spectrum of AQX-2F-SeS.

[0038] Figure 2 This is the NMR spectrum of AQX-2F-SSe.

[0039] Figure 3 Ultraviolet absorption spectra of AQX-2F-SSe and AQX-2F-SeS films.

[0040] Figure 4 The UV absorption spectra of AQX-2F-SSe and AQX-2F-SeS solutions.

[0041] Figure 5 JV curves of AQX-2F-SSe and AQX-2F-SeS devices.

[0042] Figure 6 This is the device structure diagram of AQX-2F-SSe and AQX-2F-SeS. DETAILED DESCRIPTION

[0043] In order to gain a deeper understanding of the present invention, we will provide a comprehensive and detailed description of the present invention. However, the present invention has multiple implementations and is not limited to the specific examples listed herein. The presentation of these examples is intended to deepen the comprehensive understanding of the disclosure of the present invention.

[0044] (I) Synthesis of tin reagent

[0045] Example 1

[0046]

[0047] Synthesis of compound 1-1: In a 500mL round-bottom flask, ethyl 2-(thiophene-3-ylselenoyl)acetate (18.429g, 73.957mmol), freshly distilled CH2Cl2 (150mL) and 3-butylnonanoyl chloride (18.399g, 73.957mmol) were added in sequence, and then AlCl3 (9.861g, 73.957mmol) was added. After addition, the resulting reaction mixture was stirred at room temperature for 4h. The mixture was quenched with a saturated aqueous solution of ammonium chloride and then extracted with dichloromethane. The organic layers were combined, washed with a saturated saline solution, and dried over anhydrous Na2SO4. After removing the solvent, a crude brown oil was obtained, and a light yellow oily compound 1-1 was obtained with petroleum ether / dichloromethane (4:1).

[0048] Synthesis of compound 1-2: Compound 1-1 (6.8 g, 15.4 mmol), potassium tert-butoxide (3.8 g, 34 mmol) and THF (50 mL) were added to a dry 250 mL round-bottom culture bottle under N2 protection. The mixture was stirred at 0 ° C for 2 h and then at 60 ° C for 12 h. After cooling to room temperature, lithium hydroxide aqueous solution (16 mL, 2 M) was added to the mixture and further reacted at 80 ° C for 12 h. After the reaction was completed, 1 M hydrochloric acid aqueous solution was added to pH = 1. The mixture was extracted with dichloromethane (DCM), the organic layer was collected, washed with water, and dried over anhydrous Na2SO4. After removing the solvent under reduced pressure, a mixed solvent was used as an eluent (hexane / dichloromethane, v / v=1 / 2), and the residue was purified by column chromatography on silica gel to obtain compound 1-2 (3.1 g, 59%).

[0049] Synthesis of compound 1-3: In a 100 mL round-bottom flask, a mixture of compound 1-2 (1.721 g, 4.310 mmol) and copper powder (206 mg, 3.219 mmol) in quinoline (45 mL) was stirred at 240 ° C for 2 h. After cooling to room temperature, the mixture was acidified with hydrochloric acid and extracted with ethyl acetate. The organic layers were combined, washed with saturated saline solution, dried over anhydrous Na2SO4, and then filtered. After removing the solvent, the crude product was purified by silica gel column chromatography and eluted with petroleum ether to obtain colorless oily compound 1-3 (2.355 g, 65.0%).

[0050] Synthesis of compound 1-4: Compound 1-3 (1.8 g, 6 mmol) and dry THF (20 mL) were added to a dry 100 mL round-bottom flask under N2 protection. The mixture was stirred at -78 ° C for a period of time, and then LDA (6.6 mmol) was added dropwise. After stirring at -78 ° C for 1 h, tributyltin chloride (2.15 g, 6.6 mmol) was added by injection. The mixture was stirred at room temperature for 2 h. Water was then added to the solution, extracted with hexane, the organic layer was collected, washed with water, and dried over anhydrous Na2SO4. Compound 1-4 was obtained after removing the solvent under reduced pressure and was used directly in the next step without further purification.

[0051] Example 2

[0052]

[0053] Synthesis of compound 2-1: To a mixture of 3,4-dibromothiophene (1.0 equiv.) in dry ether, n-BuLi (1.6 M solution in n-hexane, 1.1 equiv.) was added dropwise at -78 °C. After the addition was complete, the resulting mixture was stirred for another 2 h, and then 2-butyloctanal (1.2 equiv.) was quickly added. The final mixture was heated to rt and stirred for 2 h. The reaction was then quenched with water and extracted with ethyl acetate. The combined extracts were dried over anhydrous MgSO4, filtered, and the solvent was distilled under reduced pressure to give a crude product. The residue was purified by chromatography on silica gel (eluent: petroleum ether) to give the target compound 2-1 as a colorless oil (2.53 g, 78%).

[0054] Synthesis of compound 2-2: Compound 2-1 (1.0 eq.) and triethylsilane (4.0 eq.) in anhydrous CH2Cl2 round-bottom flask were cooled to 0°C, and then TFA (6.0 eq.) was added via syringe. The solution was stirred at rt for 2 h and quenched with saturated NaHCO3. The mixture was extracted with CH2Cl2, dried over anhydrous MgSO4, and concentrated. The residue was purified by chromatography on silica gel (eluent: petroleum ether) to give the target compound 2-2 as a colorless oil (1.90 g, 80%).

[0055] Synthesis of compound 2-3: A stirred solution of 2-2 (1.0 eq.) in Et2O was cooled to -78°C and n-BuLi (1.6 M hexane solution, 1.1 eq.) was added dropwise over 60 minutes. After stirring for 2 hours, selenium powder (1.2 eq.) was added in portions. The solution was stirred for another 1 hour at -78°C and then heated to -30°C and stirred for 4 hours. Ethyl bromoacetate (1.2 eq.) was then added and stirred overnight at rt. The mixture was extracted with ether, the combined organic layers were dried over anhydrous magnesium sulfate, and the solvent was evaporated under vacuum. The residue was purified by chromatography on silica gel (ethyl acetate: petroleum ether) to give the target compound 2-3 as a yellow oil (1.40 g, 80%).

[0056] Synthesis of compound 2-4: DMF (3eq) and POCl3 (1.5eq) were added to the reaction bottle under anhydrous oxygen-free nitrogen atmosphere, stirred for 1h in an ice-water bath, then the reaction bottle was restored to room temperature, and then transferred to an oil bath, 2-3 (1eq) was dissolved in anhydrous 1,2-dichloroethane, added to the reaction bottle and reacted at 80°C overnight. After the reaction was completed, the reaction solution was restored to room temperature, saturated Na2HCO3 was added to the reaction solution and stirred for 30min, then DCM was added for extraction, and the organic phase was dried with anhydrous Na2SO4. The residue was purified by chromatography on silica gel (ethyl acetate: petroleum ether) to obtain the target compound 2-4 as a yellow oil (1.40g, 80%)

[0057] Synthesis of compound 2-5: In a 50 mL round bottom culture bottle, dissolve 2-4 (1.0 eq) with anhydrous DMF and add K2CO3 (3.0 eq). Stir the mixture at 70 ° C under a nitrogen atmosphere for 24 h. Add H2O to quench and extract the compound with dichloromethane. The organic phase is washed several times with H2O, dried over anhydrous magnesium sulfate, and evaporated in vacuo. The residue is purified by chromatography on silica gel (eluent: hexane / DCM=4 / 1) to obtain the target compound 2-5 as a yellow oil (0.94 g, 94%).

[0058] Synthesis of compound 2-6: A THF solution of 2.5 (1.0 eq.), LiOH (0.5 eq. 10 wt%) and EtOH (1 / 4, v / v) was heated at 85°C under reflux for 5 h. After evaporating the solvent under reduced pressure, the mixture was acidified with concentrated HCl and then extracted with EtOAc. The combined organic phases were dried and the solvent was evaporated under reduced pressure. The crude target compound 2-6 was used directly in the next reaction without further purification.

[0059] Synthesis of compound 2-7: A mixture of crude precursor compound 2-6 and copper powder (0.65 eq.) in quinoline was stirred at 250 ° C for 4 h. After cooling to rt, the mixture was added to hexane and then washed with 2M HCl. The organic phase was dried over anhydrous magnesium sulfate and the solvent was evaporated under reduced pressure. The residue was purified by chromatography on silica gel (eluent: petroleum ether) to obtain the target compound 2-7 as a colorless solid (0.69 g, 82%).

[0060] Synthesis of compound 2-8: Compound 2-7 (1.8 g, 6 mmol) and dry THF (20 mL) were added to a dry 100 mL round-bottom flask under N2 protection. The mixture was stirred at -78 ° C for a period of time, and then LDA (6.6 mmol) was added dropwise. After stirring at -78 ° C for 1 h, tributyltin chloride (2.15 g, 6.6 mmol) was added by injection. The mixture was stirred at room temperature for 2 h. Water was then added to the solution, extracted with hexane, the organic layer was collected, washed with water, and dried over anhydrous Na2SO4. Compound 2-8 was obtained after removing the solvent under reduced pressure and used directly in the next step without further purification.

[0061] (II) Synthesis of AQX-2F-SSe and AQX-2F-SeS

[0062] Example 3

[0063]

[0064] Synthesis of compound 1: 4,7-dibromo-5,6-dinitro[2,1,3]benzothiadiazole (1.893 g, 4.958 mmol), tributyl(6-undecylthieno[3,2-b]thiophene-2-yl)tin (1.448 g, 2.479 mmol), tributyl(6-(2-butyloctyl)seleniumbenzo[3,2-b]thiophene-2-yl)tin (1.597 g, 2.479 mmol), Pd(PPh3)2Cl2 (139 mg, 0.198 mmol, 4%) were added to a 100 mL two-necked round-bottom flask. The mixture was evacuated and backfilled with N2 3 times, and then anhydrous toluene (20 mL) was injected into the mixture. The resulting reaction mixture was reacted at 60 ° C for 12 h under N2 atmosphere. The mixture was quenched with a saturated aqueous solution of ammonium chloride and then extracted with ethyl acetate. The organic layers were combined, washed with saturated saline solution, and dried over anhydrous Na2SO4. After removing the solvent, the crude product was purified by silica gel column chromatography using petroleum ether / dichloromethane (2:1) as eluent to obtain red solid compound 1 (2 g, 60%).

[0065] Synthesis of compound 2: Compound 1 (1.382 g, 1.56 mmol), triphenylphosphine (4.0 g, 15.6 mmol) and anhydrous o-dichlorobenzene (20 mL) were added to a dry 100 mL round-bottom flask under N2 protection. The mixture was heated to 180 ° C and stirred for 6 h. After cooling to room temperature, the solvent was evaporated under reduced pressure to obtain compound 2 (1 g) as a yellow solid without further purification.

[0066] Synthesis of compound 3: Under nitrogen atmosphere, compound 2 (1.56mmol), anhydrous potassium carbonate (4.3g, 30mmol), potassium iodide (3mg, 0.016mmol) were dissolved in anhydrous DMF, and then bromoisooctane (1.5g, 4.0mmol) was added to the reaction bottle, and the oil bath was reacted at 145°C for 4h. After the reaction was completed, the reaction mixture was restored to room temperature, H2O was added to the reaction solution, and then DCM was added for extraction, and the organic phase was dried with anhydrous Na2SO4. The crude product was dry-loaded, eluted through a silica gel column, and DCM / PE (1 / 10, v / v) was used as a developing solvent to obtain a yellow oil, namely compound 3 (1g, yield 60%).

[0067] Synthesis of compound 4: Under nitrogen protection, LiAlH4 (119 mg, 3.14 mmol, 5.0 eq.) was added to a tetrahydrofuran (THF, 60 mL) solution of compound 3 (659 mg, 0.63 mmol, 1.0 eq.). The resulting mixture was stirred and heated to reflux for 10 h. After cooling to 0 ° C, water (20 mL) was slowly dripped into the reaction and extracted with dichloromethane. The organic layer was dried over anhydrous Na2SO4 for 0.5 h. After removing the solvent, the crude product was dissolved in chloroform (45 mL), and then 3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ, 285 mg, 1.26 mmol, 2.0 eq.) and 4,5-difluorobenzene-1,2-diamine (452 ​​mg, 3.14 mmol, 5.0 eq.) were added to the solution in sequence. The reaction was stirred at room temperature for 6 h, and the solvent was removed under vacuum. Finally, purification by column chromatography gave compound 4 as a purple solid (615 mg, 76%).

[0068] Synthesis of compound 5: In an anhydrous and oxygen-free nitrogen atmosphere, DMF (0.3 mL) was added to the reaction bottle, and POCl3 (0.2 mL) was added to the reaction bottle, and stirred for 1 h in an ice-water bath. The reaction bottle was then restored to room temperature and transferred to an oil bath. Compound 4 (540 mg, 0.44 mmol) was dissolved in anhydrous 1,2-dichloroethane and added to the reaction bottle to react overnight at 80 ° C. After the reaction was completed, the reaction solution was restored to room temperature, saturated Na2HCO3 was added to the reaction solution and stirred for 30 min, and then DCM was added for extraction, and the organic phase was dried with anhydrous Na2SO4. The crude product was dry-loaded, eluted through a silica gel column, and DCM / PE (1 / 3, v / v) was used as the developing solvent to obtain a red solid, namely compound 5 (364 mg, yield 70%).

[0069] Synthesis of compound 6: Compound 5 (295 mg, 0.25 mmol) and 2-(5,6-difluoro-3-oxo-2,3-dihydro-1H-inden-1-yl)malononitrile (61 mg, 0.3 mmol) were dissolved in toluene. Then acetic anhydride (1 mL) was added, stirred at room temperature and trifluoroborane ethyl ether (1 mL) was slowly added dropwise. The reaction was continued for 30 min until the reaction was completed. Anhydrous methanol was added to the reaction solution to obtain a black solid precipitate, which was filtered to obtain a solid crude product. The crude product was dissolved in dichloromethane, and the crude product was dry-loaded and eluted through a silica gel column to obtain a black solid, i.e., compound 6.

[0070] Wherein, R is an alkyl group; X is selected from the group consisting of Se and S; Y is selected from the group consisting of S and Se;

[0071] When X is Se and Y is S, the compound 6 is AQX-2F-SeS, and the chemical structure is:

[0072]

[0073] When X is S and Y is Se, the compound 6 is AQX-2F-SSe; the chemical structure is:

[0074]

[0075] The NMR spectrum of AQX-2F-SeS is shown in Figure 1 As shown;

[0076] 1H NMR(400MHz,Chloroform-d)δ9.16(d,J=5.7Hz,2H),8.57(dd,J=9.8,6.4Hz,2H),8.21–8.12(m,2H),7.75–7.68(m,2H),4.85(dd,J=21.6,7.8Hz ,4H),3.22(dd,J=13.0,7.7Hz,4H),2.18(d,J=14.1Hz,6H),1.46–1.22( m,34H),1.14(d,J=19.3Hz,12H),0.93–0.77(m,18H),0.70–0.65(m,5H).

[0077] The NMR spectrum of AQX-2F-SSe is as follows Figure 2 As shown:

[0078] 1 H NMR(300MHz,Chloroform-d)δ9.27(s,1H),9.17(s,1H),8.55(dt,J=9.9,6.7Hz,2H),8.18(t,J=9.4Hz,2H),7.77–7.66(m,2H),4.79(d d,J=17.1,7.8Hz,4H),3.25(t,J=7.1Hz,4H),2.27–1.90(m,6H),1.53–1.01(m,45H),0.84(tt,J=19.6,6.8Hz,20H),0.72–0.55(m,6H).

[0079] Example 4 Test of Absorption Coefficient of AQX-2F-SSe and AQX-2F-SeS Thin Films

[0080] Spin-coat a sample solution of chloroform with an appropriate concentration onto a quartz plate and measure the absorption coefficient of the sample in a thin film state. Figure 3 The UV absorption spectra of AQX-2F-SSe and AQX-2F-SeS films show that the maximum absorption peaks of AQX-2F-SSe and AQX-2F-SeS films are located at 814nm. This forms a good complementary absorption with D18 in the visible near-infrared region, which is conducive to making full use of sunlight collection, thus ensuring that the device achieves a high J SC .

[0081] Example 5 Determination of extinction coefficients of AQX-2F-SSe and AQX-2F-SeS in chloroform solution

[0082] Preparation 10 -5 mol / l chloroform sample solution, add the sample solution into the cuvette, and measure the extinction coefficient of the sample in the chloroform solution at room temperature. Figure 4 From the ultraviolet absorption spectra of AQX-2F-SSe and AQX-2F-SeS solutions, it can be seen that compounds AQX-2F-SSe, AQX-2F-SSe and AQX-2F-SeS have strong absorption in the visible light-near infrared range (550-900nm). This wide and strong light absorption is conducive to making full use of the solar spectrum, thereby greatly improving the short-circuit current of organic photovoltaic devices.

[0083] Example 6 JV curve test of organic photovoltaic device

[0084] The analysis was performed using a Keithley 2400 spectrometer under N2 protection. Figure 5 The JV curves of AQX-2F-SSe and AQX-2F-SeS devices are shown. The photoelectric conversion efficiency of the D18:AQX-2F-SSe blended thin film device is 14.8%, its VOC is 0.91V, and Jsc is 24.26mA / cm 2 , FF is 67%. The photoelectric conversion efficiency of the D18:AQX-2F-SeS blended thin film device is 18.2%, its VOC is 0.93V, and Jsc is 25.8mA / cm 2 , FF is 75.2%.

[0085] Example 7

[0086] The solar cell structure adopts a forward device structure of ITO / PEDOT:PSS / acceptor:D18 / PDINN / Ag. Figure 6 The schematic diagram of the structure of AQX-2F-SSe and AQX-2F-SeS devices is as follows: The ITO-coated glass substrate is ultrasonically cleaned with detergent, deionized water and ethanol in sequence. It is dried in an oven at 60°C for 5 hours and then treated with a UV ozone meter for 10 minutes. PEDOT:PSS is spin-coated on the cleaned ITO at a rotation rate of 3000rpm and a thickness of about 20nm. It is then dried in an oven at 150°C for 10min, cooled to room temperature, and the dried substrate is transferred to a glove box. The active material is dissolved in chloroform solution with donor and acceptor (D:A=1:1.2), stirred at room temperature for 3h, and 0.5% 1,8-diiodooctane (DIO) is added 30min before spin coating the active layer, and spin coated on the PEDOT:PSS layer at 2500rpm, annealed at 100°C for 10min to prepare a donor-acceptor mixed active layer. Finally, the Ag film was deposited on the active layer by vacuum evaporation, and the effective area of ​​the device was 4 mm 2 .

[0087] The contents not described in detail in the specification of the present invention belong to the prior art known to the professional and technical personnel in the field. Although the illustrative specific embodiments of the present invention are described above to facilitate the understanding of the present invention by the technical personnel in the field, it should be clear that the present invention is not limited to the scope of the specific embodiments. For the ordinary technical personnel in the field, as long as various changes are within the spirit and scope of the present invention defined and determined by the attached claims, these changes are obvious, and all inventions and creations using the concept of the present invention are protected.

Claims

1. A selenium-containing asymmetric small molecule receptor material, characterized in that: The selenium-containing asymmetric small molecule receptor material has quinoxaline as the core unit, asymmetric selenophene as the unit structure, and an electron-withdrawing group structure at the end. Its chemical structure is as follows: Wherein, when X is Se, Y is S; the small molecule receptor is named: AQX-2F-SeS, and the chemical structure is: Wherein, when X is S, Y is Se; the small molecule receptor is named: AQX-2F-SSe, and the chemical structure is:

2. The method for preparing a selenium-containing asymmetric small molecule receptor material according to claim 1, characterized in that: The following steps are involved: Step 1, under a nitrogen atmosphere, using 4,7-dibromo-5,6-dinitrobenzo[c][1,2,5]thiadiazole as a raw material, undergoing Stille coupling reaction, and then separating by column chromatography to obtain a red solid compound 1; the conditions of the Stille coupling reaction are: using toluene as a solvent, using Pd[P(C6H5)3]4 as a catalyst, and performing a reflux reaction with a tin reagent at a temperature of 110 to 130°C; Step 2, under nitrogen protection, using triphenylphosphine as a reducing agent and o-dichlorobenzene as a solvent, reducing the red solid compound 1 to form a ring; reflux reaction at a temperature of 160-180° C. to obtain a yellow solid compound 2; Step 3, under nitrogen protection, potassium carbonate and potassium iodide are used as catalysts, DMF is used as solvent, and yellow solid compound 2 and isooctane bromide are refluxed at 140° C. for 4 to 6 hours to obtain yellow oily compound 3; Step 4, under nitrogen protection, using tetrahydrofuran as solvent, the yellow oily compound 3 is reduced by LiAlH4, oxidized by DDQ, and then condensed with 4,5-difluoro-1,2-phenylenediamine to obtain a purple-red solid compound 4; Step 5, under the protection of anhydrous and oxygen-free nitrogen, the purple solid compound 4 is dissolved in 1,2-dichloroethane and then added to a mixed solution of phosphorus oxychloride and dimethylformamide to carry out Vismeier-Haack reaction, stirred at 90° C. overnight, and separated by column chromatography to obtain a red solid compound 5; Step 6, under nitrogen protection, red solid compound 5 and 2-(5,6-difluoro-3-oxo-2,3-dihydro-1H-inden-1-yl)malononitrile are dissolved in toluene, and then acetic anhydride and trifluoroborane ethyl ether are added to carry out Knoevenagel condensation reaction, and a black solid compound is obtained by column chromatography separation; a solid crude product is obtained by suction filtration, the crude product is dissolved in dichloromethane, the crude product is dry-loaded, and eluted through a silica gel column to obtain a dark solid compound 6; Wherein, R is an alkyl group; X is selected from: Se, S; Y is selected from: S, Se; and when X is Se, Y is S, the compound 6 is AQX-2F-SeS; when X is S, Y is Se, the compound 6 is AQX-2F-SSe.

3. The method for preparing a selenium-containing asymmetric small molecule receptor material according to claim 2, characterized in that: In the step 1, the tin reagent is tributyl(6-(2-butyloctyl)thieno[3,2-b]thiophene-2-yl)stannane and tributyl(6-(2-butyloctyl)selenobenzo[3,2-b]thiophene-2-yl)tin, or tributyl(6-(2-butyloctyl)thieno[3,2-b]thiophene-2-yl)stannane and tributyl(3-(2-butyloctyl)selenobenzo[3,2-b]thiophene-5-yl)tin; In the step 1, the molar ratio of 4,7-dibromo-5,6-dinitrobenzo[c][1,2,5]thiadiazole, Pd[P(C6H5)3]4 and tributyl(6-(2-butyloctyl)thieno[3,2-b]thiophen-2-yl)stannane to the precursor is 2:0.4:1:

1.

4. The method for preparing a selenium-containing asymmetric small molecule receptor material according to claim 3, characterized in that: The preparation method of tributyl(6-(2-butyloctyl)selenobenzo[3,2-b]thiophen-2-yl)tin is specifically as follows: ethyl 2-(thiophen-3-ylselenoyl)acetate is used as a raw material and 3-butylnonanoyl chloride is subjected to Friedel-Crafts acylation, followed by potassium tert-butoxide cyclization, lithium hydroxide hydrolysis, and copper quinoline decarboxylation, and then LDA is used to form a lithium reagent and react with tributyltin chloride to prepare the product.

5. The method for preparing a selenium-containing asymmetric small molecule receptor material according to claim 4, characterized in that: In the step, the molar ratio of ethyl 2-(thiophene-3-ylselenoyl)acetate, 3-butylnonanoyl chloride, potassium tert-butoxide, lithium hydroxide, copper, quinoline, LDA, and tributyltin chloride is 1:1:2:2:1:0.5:1:

1.

6. The method for preparing a selenium-containing asymmetric small molecule receptor material according to claim 3, characterized in that: The preparation method of tributyl(3-(2-butyloctyl)selenobenzo[3,2-b]thiophene-5-yl)tin is specifically as follows: 3,4-dibromothiophene is used as a raw material, reacted with n-butyl lithium to form a lithium reagent, and then reacted with 2-butyloctanal, and then reduced with triethylsilane and trifluoroacetic acid, and then reacted with n-butyl lithium to form a lithium reagent, and then reacted with selenium powder and ethyl bromoacetate, and then reacted with phosphorus oxychloride and DMF to undergo Vismeier-Haack reaction and cyclization under alkaline conditions of potassium carbonate; after hydrolysis with lithium hydroxide and decarboxylation with copper quinoline, LDA is used to form a lithium reagent and reacts with tributyltin chloride for preparation.

7. The method for preparing a selenium-containing asymmetric small molecule receptor material according to claim 6, characterized in that: In the step, the molar ratio of 3,4-dibromothiophene, n-butyl lithium, 2-butyloctanal, triethylsilane, trifluoroacetic acid, n-butyl lithium, selenium powder, ethyl bromoacetate, phosphorus oxychloride, DMF, potassium carbonate, lithium hydroxide, copper, quinoline, LDA, and tributyltin chloride is 1:1:1.2:4:6:1.2:1.2:1.5:3:3:0.5:1:0.5:1:

1.

8. The method for preparing a selenium-containing asymmetric small molecule receptor material according to claim 2, characterized in that: In the step 2, the molar ratio of the red solid compound 1, triphenylphosphine and o-dichlorobenzene is 1:10:2; In step 3, the molar ratio of the yellow solid compound 2, potassium carbonate, potassium iodide, DMF and isooctane bromide is 1:20:0.2:5:5; In step 4, the molar ratio of LiAlH4, yellow oil compound 3, DDQ and 4,5-difluoro-1,2-phenylenediamine is 20:1:2:5; In the step 5, the molar ratio of the purple solid compound 4, phosphorus oxychloride and DMF is 1:10:

12.

9. The method for preparing a selenium-containing asymmetric small molecule receptor material according to claim 2, characterized in that: In step 6, the molar ratio of the red solid compound 5, 2-(5,6-difluoro-3-oxo-2,3-dihydro-1H-inden-1-yl)malononitrile, acetic anhydride and trifluoroborane ethyl ether is 1:2.5:0.1:0.

1.

10. Use of a selenium-containing asymmetric small molecule acceptor material prepared according to the preparation method according to any one of claims 2 to 9 in an organic solar cell.

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