Oligomeric acceptors containing bithiazole spacers, methods of making and use thereof

Abstract

The application provides an oligomeric acceptor containing a bithiazole spacer and a preparation method and application thereof. The oligomeric acceptor is a small molecular acceptor with a bithiazole as a bridging spacer and outwardly connected to a benzothiadiazole (BTP) unit or a quinoxaline (Qx) unit or a phenazine (Pz) unit as a central core. The oligomeric acceptor containing the bithiazole spacer has good light capturing capacity, suitable electronic energy levels and strong molecular packing; as an electron acceptor material applied to an organic solar cell, the oligomeric acceptor has high photoelectric conversion efficiency.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of organic solar cell materials, in particular to an oligomeric acceptor containing a bithiazole spacer and a preparation method and application thereof. BACKGROUND

[0002] Organic solar cells (OSCs) with conjugated organic semiconductors as the active layer have unique advantages compared to inorganic photovoltaic cells, such as light weight, semi-transparency, and flexibility, making them have broad application prospects in the field of wearable and portable electronic devices facing future processing (J. Park, G. Kim, S. Lee, J. Lee, S. Li, J. Lee and B. Kim, Adv. Mater., 2022, 34, 2201623; J. Huang, Z. Lu, J. He, H. Hu, Q. Liang, K. Liu, Z. Ren, Y. Zhang, H. Yu, Z. Zheng and G. Li, Energy Environ. Sci., 2023, 16, 1251-1263; L. Zhu, M. Zhang, J. Xu, C. Li, J. Yan, G. Zhou, W. Zhong, T. Hao, J. Song, X. Xue, Z. Zhou, R. Zeng, H. Zhu, C. Chen, R. MacKenzie, Y. Zou, J. Nelson, Y. Zhang, Y. Sun and F. Liu, Nat. Mater., 2022, 21, 656-663.). In recent years, with the continuous development of new high-efficiency donor and acceptor materials, the energy conversion efficiency (PCE) of organic solar cells has broken through 20%, reaching the threshold of commercial application (J. Wu, G. Li, J. Fang, X. Guo, L. Zhu, B. Guo, Y. Wang, G. Zhang, L. Arunagiri, F. Liu, H. Yan, M. Zhang and Y. Li, Nat. Commun., 2020, 11, 4612; X. Guo, Q. Fan, J. Wu, G. Li, Z. Peng, W. Su, J. Lin, L. Hou, Y. Qin, H. Ade, L. Ye, M. Zhang and Y. Li, Angew. Chem. Int. Ed., 2021, 133, 2352-2359; J. Yuan, Y. Zhang, L. Zhou, G. Zhang, H. Yip, T-K. Lau, X. Lu, C. Zhu, H. Peng, Paul A. Johnson, M. Leclerc, Y. Cao, J. Ulanski, Y. Li, and Y. Zou, Joule, 2019, 3, 1; M. Zhang, X. Guo, W. Ma, H. Ade and J. Hou, Adv. Mater., 2015, 27, 4655.). However, in order to ensure the commercial feasibility of OSCs, it is necessary to meet both high PCE and long device stability. However, the long-term stability of organic solar cells is an important factor that restricts their practical application.

[0003] Currently, the high-performance OSC active layer is a metastable structure formed by blending polymer donors and non-fullerene small molecule acceptors. Non-fullerene small molecule acceptors, due to their small molecular size, will rapidly diffuse under external stress (such as light and heat), leading to unfavorable evolution of their metastable morphology, and thus performance decay (M. Ghasemi, N. Balar, Z. Peng, H. Hu, Y. Qin, T. Kim, J. J. Rech, M. Bidwell, W. Mask, I. McCulloch, W. You, A. Amassian, C. Risko, B. T. O’Connor and H. Ade, Nat. Mater., 2021, 20, 525-532; Y. Qin, N. Balar, Z. Peng, A. Gadisa, I. Angunawela, A. Bagui, S. Kashani, J. Hou and H. Ade, Joule, 2021, 5, 2129-2147.). The He group first oligomerized non-fullerene small molecule acceptors and demonstrated the advantages of OSCs based on oligomeric acceptors in PCE and stability. Oligomeric acceptors with discrete chain lengths can be highly crystallized, resulting in good optoelectronic properties and achieving high PCE; and oligomeric acceptors with extended chain lengths significantly reduce diffusion dynamics, leading to higher device stability under light and heat stress (H. Wang, C. Cao, H. Chen, H. Lai, C. Ke, Y. Zhu, H. Li and F. He, Angew. Chem., Int. Ed., 2022, 61, e202201844.). The molecular design of oligomeric acceptors mainly consists of three parts: (1) non-fullerene acceptor conjugated backbone; (2) length and structure of side chains; (3) position and structure of spacers. Among them, the position and structure of spacers play an important role in the photophysical and chemical properties of materials and device performance.Researchers have fine-tuned the molecular conformation, solubility, crystallinity and intermolecular interaction of oligomeric acceptors by adjusting the structure and connection position of the oligomeric acceptor spacer, thereby optimizing the phase separation of the active layer, and achieving a substantial improvement in the performance of OSC photovoltaics (Y. Bai, Z. Zhang, Q. Zhou, H. Geng, Q. Chen, S. Kim, R. Zhang, C. Zhang, B. Chang, S. Li, H. Fu, L. Xue, H. Wang, W. Li, W. Chen, M. Gao, L. Ye, Y. Zhou, Y. Ouyang, C. Zhang, F. Gao, C. Yang, Y. Li and Z. Zhang, Nat. Commun., 2023, 14, 2926; C. Sun, J. Lee, C. Lee, D. Lee, S. Cho, S. Kwon, B. Kim and Y. Kim, Joule, 2023, 7, 416-430.). However, current research on oligomeric acceptor spacers mainly focuses on their electron-donating properties and non-covalent conformational locking, and there is a relative lack of research on the influence of the spacer itself on molecular packing. Therefore, it is of great significance to develop an efficient oligomeric acceptor containing a novel spacer and to explore its influence on multi-scale molecular packing. SUMMARY

[0004] In view of the deficiencies in the prior art, the present application provides an oligomeric acceptor containing a bithiazole-based spacer and a preparation method and application thereof. The oligomeric acceptor containing a bithiazole-based spacer has good light trapping ability, suitable electronic energy levels and strong molecular packing; as an electron acceptor material applied in organic solar cells, it has high photoelectric conversion efficiency.

[0005] The technical scheme of the present application is as follows:

[0006] An oligomeric acceptor containing a bithiazole-based spacer, the oligomeric acceptor is a small molecule acceptor with a bithiazole-based bridge spacer, externally connected to a small molecule acceptor with a benzothiadiazole (BTP) unit or a quinoxaline (Qx) unit or a phenazine (Pz) unit as the central core, having the following structure as shown in formula I, II or III:

[0007]

[0008] In formula I, formula II or formula III,

[0009] R1 is selected from hydrogen, C1-C6 alkyl, C1-C6 alkoxy, C1-C6 alkylthio, 30 C1-C6 alkylthio, 30 C1-C6 alkylthio, 30 C1-C6 alkylthio, one; wherein R3 is C1-C6 alkyl.30 any one of alkyl groups having 1 to 8 carbon atoms;

[0010] R2 is selected from any one of hydrogen, C1-C8 alkyl, C1-C8 alkoxy, C1-C8 alkylthio or C1-C8 alkylsulfanyl groups; 30 C1-C8 alkyl, C1-C8 alkoxy, C1-C8 alkylthio or C1-C8 alkylsulfanyl groups; 30 C1-C8 alkyl, C1-C8 alkoxy, C1-C8 alkylthio or C1-C8 alkylsulfanyl groups; 30 C1-C8 alkyl, C1-C8 alkoxy, C1-C8 alkylthio or C1-C8 alkylsulfanyl groups;

[0011] Electron-withdrawing group A is selected from one of the following structures:

[0012]

[0013] Electron-withdrawing group B is selected from one of the following structures:

[0014]

[0015] wherein R4 is any one of C1-C8 alkyl groups;

[0016] Bridge spacer C is selected from one of the following structures:

[0017]

[0018] wherein R5 is any one of C1-C8 alkyl groups. 10

[0019] According to the present application, preferably, the oligomeric acceptor containing a bithiazole-based spacer has the following structure shown in formula I-1:

[0020]

[0021] The preparation method of the above oligomeric acceptor containing a bithiazole-based spacer comprises the following steps:

[0022] (1) Compound 1 and tributyltin chloride are reacted in anhydrous tetrahydrofuran solvent under the action of n-butyllithium (n-BuLi) to obtain compound 2;

[0023]

[0024] wherein the substituent R1 is the same as R1 in formula I, formula II or formula III;

[0025] (2) Compound 2 and compound 3 are reacted in toluene under the catalysis of tetrakis(triphenylphosphine)palladium to obtain compound 4;

[0026]

[0027] (3) Compound 4 is reacted in o-dichlorobenzene under the catalysis of triphenylphosphine to obtain an intermediate; then compound R2X and the intermediate are reacted in DMF solvent under the action of K2CO3 and KI to obtain compound 5;​

[0028] In the compound R2X, the substituent X is bromine or iodine, and the substituent R2 is selected from any one of hydrogen, C1-C30 alkyl, C1-C30 alkoxy, or C1-C30 alkylthio;

[0029] (4) POCl3 is dispersed in DMF, and a 1,2-dichloroethane solution of compound 5 is added, and compound 6 is obtained by reaction;

[0030] (5) Compound 6 and compound A are reacted in toluene in the presence of acetic anhydride and boron trifluoride etherate to obtain compound 7;

[0031] wherein compound A is selected from one of the following:

[0032]

[0033] (6) POCl3 is dispersed in DMF, and a 1,2-dichloroethane solution of compound 7 is added, and compound 8 is obtained by reaction;

[0034] (7) Compound 8 and compound B are reacted in toluene in the presence of acetic anhydride and boron trifluoride etherate to obtain compound 9;

[0035] wherein compound B is selected from one of the following:

[0036]

[0037] wherein R4 is any one of C1-C8 alkyl;

[0038] (8) Compound 9 and compound C are reacted in toluene in the presence of tetrakis(triphenylphosphine)palladium to obtain an oligomeric acceptor containing a bithiazole spacer;

[0039] The compound C is selected from one of the following:

[0040]

[0041] wherein R5 is any one of C1-C8 alkyl. 10

[0042] According to the present application, compound 1, compound 2, compound 3, compound 4, compound 5, compound 6, compound 7, compound 8, and compound 9 respectively have the following structures:

[0043]

[0044] ​According to the application, preferably, the compound R2X is 1-bromo-2-octyldodecane, the compound A is 2-(5-bromo-3-oxo-2,3-dihydro-1H-inden-1-ylidene)malononitrile, the compound B is 2-(5,6-difluoro-3-oxo-2,3-dihydro-1H-inden-1-ylidene)malononitrile, and the compound C is 4,4'-dinonyl-5,5'-di(thiophen-2-yl)-2,2'-bithiazole.

[0045] According to the application, preferably, in step (1), the molar ratio of compound 1 to anhydrous tetrahydrofuran is 0.1-1 mol / L; the molar ratio of n-butyllithium (n-BuLi), tributyltin chloride and compound 1 is 1-1.07:1-1.1:1; the reaction conditions are as follows: reaction at-78℃ for 0.5-2 hours, and then reaction at room temperature for 20-24 hours, and the reaction is carried out under stirring.

[0046] According to the application, preferably, in step (1), the reaction liquid obtained in the reaction is treated as follows: adding deionized water to quench the reaction, extracting the organic phase with ethyl acetate, and removing the solvent from the organic phase under reduced pressure to obtain compound 2.

[0047] According to the application, preferably, in step (2), the molar ratio of compound 3 to toluene is 0.05-1 mol / L; the molar ratio of tetrakis(triphenylphosphine)palladium, compound 1 in step (1) and compound 3 is 0.01-0.1:2.3-2.7:1; the reaction temperature is 100-120℃, and the reaction time is 10-15 hours, and the reaction is carried out under reflux stirring.

[0048] According to the application, preferably, in step (2), the reaction liquid obtained in the reaction is treated as follows: extracting the reaction liquid with dichloromethane, and purifying the organic phase by column chromatography to obtain compound 4.

[0049] According to the application, preferably, in step (3), the molar ratio of compound 3 in step (2) to o-dichlorobenzene is 0.01-0.1 mol / L; the molar ratio of triphenylphosphine to compound 3 in step (2) is 6-10:1; the reaction temperature of compound 4 is 150-200℃, and the reaction time is 10-15 hours, and the reaction is carried out under stirring; and the reaction liquid of compound 4 is subjected to solvent removal to obtain an intermediate.

[0050] According to the application, preferably, in step (3), the molar ratio of compound 3 of step (2) to DMF is 0.03-0.5 mol / L; the molar ratio of K2CO3, KI, compound R2X and compound 3 of step (2) is 10-24:10-24:10-24:1; the reaction temperature of compound R2X and intermediate is 60-100℃, the reaction time is 10-14 h, and the reaction is carried out under stirring; the reaction liquid obtained is extracted with dichloromethane, and compound 5 is obtained after the organic phase is purified by column chromatography.

[0051] According to the application, preferably, in step (4), the concentration of compound 5 in 1,2-dichloroethane solution is 0.02-0.5 mol / L; the molar ratio of POCl3 and compound 3 of step (2) is 0.7-0.9:1; the volume ratio of compound 5 in 1,2-dichloroethane solution to DMF is 15-25:1; the reaction temperature is -5-5℃, the reaction time is 4-8 h, and the reaction is carried out under stirring; the reaction liquid obtained is extracted with dichloromethane, and compound 6 is obtained after the organic phase is purified by column chromatography.

[0052] According to the application, preferably, in step (5), the molar ratio of compound 3 of step (2) to toluene is 0.01-0.5 mol / L; the molar ratio of acetic anhydride, boron trifluoride etherate and compound 3 of step (2) is 0.2-0.4:2-4:1; the molar ratio of compound 3 of step (2) to compound A is 1.6-1.8:1; the reaction temperature is 40-80℃, the reaction time is 5-15 min, and the reaction is carried out under stirring; the reaction liquid obtained is added into methanol, the precipitate is filtered, the precipitate is dissolved in dichloroethane solvent, and compound 7 is obtained after purification by column chromatography.

[0053] According to the application, preferably, in step (6), the concentration of compound 7 in 1,2-dichloroethane solution is 0.02-0.5 mol / L; the molar ratio of POCl3 and compound 3 of step (2) is 0.7-0.9:1; the volume ratio of compound 7 in 1,2-dichloroethane solution to DMF is 15-25:1; the reaction temperature is -5-5℃, the reaction time is 4-8 h, and the reaction is carried out under stirring; the reaction liquid obtained is extracted with dichloromethane, and compound 8 is obtained after the organic phase is purified by column chromatography.

[0054] According to the application, preferably, in step (7), the molar amount of compound 3 in step (2) and the volume of toluene are in a ratio of 0.01-0.5 mol / L; the molar ratio of acetic anhydride, boron trifluoride ether and compound 3 in step (2) is 0.1-0.3:1-3:1; the molar ratio of compound 3 in step (2) and compound B is 2-2.4:1; the reaction temperature is 40-80 DEG C, the reaction time is 5-15 min, and the reaction is carried out under stirring; the reaction liquid obtained is added into methanol, the precipitate is collected by filtration, the precipitate is dissolved in dichloromethane, and column chromatography purification is carried out to obtain compound 9.

[0055] According to the application, preferably, in step (8), the molar amount of compound C and the volume of toluene are in a ratio of 0.02-0.5 mol / L; the molar ratio of tetrakis(triphenylphosphine)palladium, compound 3 in step (2) and compound C is 0.005-0.05:1:0.1-0.3; the reaction temperature is 100-120 DEG C, the reaction time is 10-20 h, and the reaction is carried out under stirring; the reaction liquid obtained is added into methanol and settled, the precipitate is collected and dissolved in chloroform, and column chromatography purification is carried out to obtain the oligomeric acceptor containing a bithiazole type spacer.

[0056] The oligomeric acceptor containing a bithiazole type spacer is applied to an organic solar cell as an electron acceptor material of a photon capture active layer.

[0057] According to the application, preferably, the solar cell comprises, from bottom to top, an indium tin oxide substrate, a PEDOT:PSS layer, an active layer, a PDINN layer and an Ag layer; the active layer is composed of the oligomeric acceptor containing a bithiazole type spacer and a donor material, and the mass ratio of the oligomeric acceptor containing a bithiazole type spacer and the donor material is 1-1.5:1; the donor material is PBDB-TF, and has the following structure.

[0058]

[0059] The preparation route of the oligomeric acceptor containing a bithiazole type spacer shown in formula I is as follows:

[0060]

[0061] The technical features and beneficial effects of the application are as follows:

[0062] 1. The oligomeric acceptor containing a bithiazole type spacer can be processed by a solution method, can be dissolved in chloroform, chlorobenzene and other organic solvents, and has good film-forming property.

[0063] 2、The oligomeric acceptor with bithiazole spacers of the present application, taking bithiazole as a bridging spacer, outwardly connecting A-DA’D-A type small molecule acceptor with BTP unit or Qx unit or Pz unit as the central core, a series of novel, good solubility, good thermal stability, with bithiazole and its derivatives as spacers, conjugated molecules are designed and synthesized. The introduction of bithiazole spacer enhances the intermolecular interaction, which helps to improve the molecular packing and crystallinity. Secondly, the introduction of S…N non-covalent interaction is conducive to reducing the torsion angle between monomer and spacer, and enhancing the planarity of the main chain conformation. In addition, bithiazole and its derivatives have weak electron-withdrawing property, which can appropriately adjust the energy level. Therefore, this kind of molecule has strong visible light absorption capacity, good light trapping ability, suitable electronic energy level and strong molecular packing, which is suitable for being used as electron acceptor material and applied to the preparation of organic solar cells; the oligomeric acceptor of the present application has high photoelectric conversion efficiency when applied to organic solar cells. BRIEF DESCRIPTION OF DRAWINGS

[0064] Figure 1 UV-visible-near infrared absorption spectrum of the oligomeric acceptor with bithiazole spacers prepared for example 1 in thin film and solution state;

[0065] Figure 2 Cyclic voltammogram of the oligomeric acceptor with bithiazole spacers prepared for example 1;

[0066] Figure 3 J-V curve of the oligomeric acceptor with bithiazole spacers prepared for example 1 applied to organic solar cells. DETAILED DESCRIPTION

[0067] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the technical solutions of the present application will be further described below in combination with the drawings and examples. However, the present application is not limited to the listed examples, and any known changes within the scope of the claimed rights of the present application should also be included.

[0068] Example 1

[0069] A synthesis route of the oligomeric acceptor DY-Tz with bithiazole spacers is as follows:

[0070]

[0071] The synthesis steps are as follows:

[0072] Step 1) Synthesis of compound 2;

[0073] Compound 1, 3-undecylthieno[3,2-B]thiophene (5 g, 16.98 mmol) was dissolved in 120 mL of anhydrous tetrahydrofuran under argon protection, n-butyllithium (7.07 mL, 16.98 mmol) was slowly added under acetone liquid nitrogen bath (-78 °C), after 2 hours of incubation and stirring, tributyltin chloride (5.53 g, 16.98 mmol) was added, after 1 hour of stirring at -78 °C, the reaction was stirred at room temperature for 24 h, deionized water was added to quench the reaction, the organic phase was extracted with ethyl acetate, the solvent was removed under reduced pressure to obtain compound 2.

[0074] Step 2) synthesis of compound 4;

[0075] Compound 2, compound 3 (4,7-dibromo-5,6-dinitrobenzo[c][1,2,5]thiadiazole) (2.6 g, 6.8 mmol) and tetrakis(triphenylphosphine)palladium (230 mg, 0.33 mmol) were stirred at 110 °C under reflux in 80 mL of toluene for 12 hours, the reaction was recovered to room temperature, extracted with dichloromethane, and the organic phase was purified by column chromatography to obtain compound 4.

[0076] Step 3) synthesis of compound 5;

[0077] Compound 4 and triphenylphosphine (PPh3) (14.4 g, 55 mmol) were stirred at 180 °C in 10 mL of o-dichlorobenzene for 12 hours, and the solvent was removed while hot. After removing the solvent, compound 1- bromo-2-octyldodecane (39.7 g, 110 mmol), K2CO3(15.5 g, 110 mmol) and KI (18.3 g, 110 mmol) were added, and the reaction was stirred at 80 °C in 40 mL of DMF solvent for 12 h, extracted with dichloromethane, and the organic phase was purified by column chromatography to obtain compound 5.

[0078] Step 4) synthesis of compound 6;

[0079] POCl3(0.9 g, 5.9 mmol) was slowly injected into 1.5 mL of DMF at 0 °C under argon protection, and stirred for 2 hours, then 30 mL of compound 5 dissolved in 1,2-dichloroethane was added, and the reaction was stirred for 6 hours, then extracted with dichloromethane, and the organic phase was purified by column chromatography to obtain compound 6.

[0080] Step 5) synthesis of compound 7;

[0081] Compound 6, 2-(5-bromo-3-oxo-2,3-dihydro-lH-inden-l-yl)propanedinitrile (1.1 g, 3.9 mmol), acetic anhydride (2 mmol) and boron trifluoride etherate (20 mmol) were stirred in 50 mL of anhydrous toluene at 60 °C for 10 min, cooled to room temperature, and the reaction solution was slowly added to methanol. The precipitate was collected by filtration, dissolved in dichloromethane, and purified by column chromatography to obtain compound 7.

[0082] Step 6) Synthesis of compound 8;

[0083] POCl3(0.83 g, 5.4 mmol) was slowly injected into 1.2 mL of DMF under argon protection at 0 °C, and stirred for 2 h. Then 25 mL of compound 7 dissolved in 1,2-dichloroethane was added, and stirred for 6 h. The reaction solution was extracted with dichloromethane, and the organic phase was purified by column chromatography to obtain compound 8.

[0084] Step 7) Synthesis of compound 9;

[0085] Compound 8, 2-(5,6-difluoro-3-oxo-2,3-dihydro-lH-inden-l-yl)propanedinitrile (0.7 g, 3 mmol), acetic anhydride (1.2 mmol) and boron trifluoride etherate (15 mmol) were stirred in 45 mL of anhydrous toluene at 60 °C for 10 min, cooled to room temperature, and the reaction solution was slowly added to methanol. The precipitate was collected by filtration, dissolved in dichloromethane, and purified by column chromatography to obtain compound 9.

[0086] Step 8) Synthesis of oligomeric acceptor DY-Tz;

[0087] Compound 9, 4,4'-dinonyl-5,5'-di(thiophen-2-yl)-2,2'-bithiazole (0.75 g, 0.82 mmol) and tetrakis(triphenylphosphine)palladium (0.08 mmol) were stirred in 5 mL of toluene at 110 °C for 12 h under argon protection. The reaction solution was cooled to room temperature, slowly added to methanol, and the precipitate was collected by filtration, dissolved in chloroform, and purified by column chromatography to obtain the oligomeric acceptor containing a bithiazole spacer.

[0088] The nuclear magnetic resonance data of the product are as follows:

[0089] 1H NMR(300MHz,Chloroform-d)δ9.19(s,2H),9.14(s,2H),8.81(dd,2H),8.62-8.57(m,2H),8.04(m,2H),7.94(m,2H),7.73(s,2H),7.5 6(s,2H),7.32(s,2H),4.81(s,8H),3.22(s,4H),3.05(s,8H),2.03(s,8H),1.36-0.84(m,274H).MS(MALDI-TOF)m / z:[MH]calculated for C 248 H 320 F4N 18 O4S 14 ,found:4139.49.

[0090] UV-Vis-NIR absorption spectroscopy: The absorption spectra of the material were measured using a SHIMADZU UV-1900i Spectrophotometer (Japan). The thin film absorption sample was prepared by spin-coating a 10 mg / mL oligomer acceptor chloroform solution onto a quartz plate at 3000 rpm. For the absorption spectrum of the solution, chloroform was used as the solvent, and the oligomer acceptor material was prepared into 1×10⁻⁶ samples. -5 mol L -1 The solution. For example... Figure 1 As shown, it exhibits strong absorption in the 600-850nm range, and the thin film absorption has a maximum absorption peak at 785nm, indicating that it has good light-harvesting ability.

[0091] The energy levels of the material were obtained using cyclic voltammetry with an Admiral Squidstat Plus electrochemical workstation. (0.1 mol L...) -1 An acetonitrile solution of Bu4NPF6 was used as the electrolyte. A platinum wire electrode, a glassy carbon electrode, and an Ag / Ag+ electrode were used as the auxiliary electrode, working electrode, and reference electrode, respectively. The reference electrode was calibrated using the redox potential of ferrocene (Fc / Fc+). Figure 2 As shown, the initial oxidation potential (φ) of the oligomer was measured. ox The value is 0.97 eV vs Ag / Ag. + Initial reduction potential (φ) re The value is -0.93 eV vs Ag / Ag. + The formula HOMO = -(E ox +4.70)(eV) and LUMO = -(E reThe HOMO and LUMO energy levels of DY-Tz can be calculated as -5.67 eV and -3.77 eV, respectively, which can be matched with efficient polymer donors.

[0092] Test Example

[0093] Preparation and performance test of solar photovoltaic device:

[0094] A commercially available indium tin oxide (ITO) glass was first washed with acetone, and then sequentially washed with detergent, water, deionized water, acetone, and isopropanol by ultrasonic cleaning. After drying, a 30 nm thick PEDOT:PSS layer was spin-coated as an anode modification layer for standby. A chloroform solution of polymer donor material PBDB-TF and oligomeric acceptor containing bithiazole-based spacer prepared in Example 1 (weight ratio of 1:1.2) and additive chloronaphthalene (0.75 vol% of chloroform) was spin-coated on the PEDOT:PSS anode modification layer to form an active layer (105 nm) of the device. Finally, a layer of PDINN with a thickness of about 10 nm was spin-coated as a cathode modification layer, and Ag (100 nm) was used as the cathode of the device to obtain a solar cell device. The effective area of the photovoltaic device was 0.049 cm 2 The energy conversion efficiency of the solar cell was tested using LSS-55 (Light Sky Technology CO., Ltd.) as a solar simulator under an intensity of 100 mW / cm 2 The photovoltaic performance of the device was tested under an intensity of 100 mW / cm OC The J-V curve was measured using Keithley 2400. The open-circuit voltage, short-circuit current, and fill factor of the solar cell device were tested.

[0095] The J-V curve of the solar cell device is shown in Figure 3 , wherein the open-circuit voltage V OC = 0.97 V, the short-circuit current J SC = 21.4 mA / cm 2 , the fill factor FF = 65.8%, and the conversion efficiency PCE = 13.7%.

[0096] The structure of the polymer donor PBDB-TF used above is as follows (which can be prepared by the method of reference “M. Zhang, X. Guo, W. Ma, H. Ade and J. Hou, Adv. Mater., 2015, 27, 4655.”):

[0097]

[0098] It should be noted that the above examples are only used to illustrate the technical solutions of the present application but not limit the present application. Although the present application is described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application can be modified or equivalently replaced, without departing from the spirit and scope of the technical solutions of the present application, which should be covered in the scope of the claims of the present application.

Claims

1. An oligomeric receptor containing a bithiazole spacer group, characterized in that, The oligomeric receptor is a small molecule receptor with a benzothiadiazole unit as the central core, using a bithiazol class as the bridging spacer. It has the structure shown in Formula I. In Equation I, R1 is selected from hydrogen, C1~C1. 30 Alkyl groups, C1-C 30 alkoxy groups, C1-C 30 alkylthio, One of them; where R3 is C1 to C 30 Any one of the alkyl groups; R2 is selected from hydrogen, C1 to C2. 30 Alkyl groups, C1-C 30 alkoxy or C1-C 30 Any one of the alkylthio groups; Electron-withdrawing group A is selected from one of the following structures: Electron-withdrawing group B is selected from one of the following structures: Wherein, R4 is any one of the alkyl groups from C1 to C8; The bridging spacer C is selected from one of the following structures: Among them, R5 is C1 to C 10 Any one of the alkyl groups.

2. The oligomer acceptor containing a bithiazole spacer group according to claim 1, characterized in that, The oligomer acceptor containing a bithiazole spacer group has the structure shown in Formula I-1:

3. The method for preparing the oligomer acceptor containing a bithiazole spacer group as described in claim 1 or 2, comprising the steps of: (1) Compound 1 and tributyltin chloride reacted in anhydrous tetrahydrofuran solvent under the action of n-butyllithium (n-BuLi) to obtain compound 2; in, Substituent R1 is the same as R1 in Formula I; (2) In toluene, under the catalysis of tetra(triphenylphosphine)palladium, compounds 2 and 3 react to give compound 4; (3) Compound 4 was reacted in o-dichlorobenzene under the catalysis of triphenylphosphine to obtain an intermediate; then, in DMF solvent, under the action of K2CO3 and KI, compound R2X and the intermediate were reacted to obtain compound 5. In compounds 4 and 5, the substituents R1 and R2 are the same as those in formula I; In compound R2X, substituent X is bromine or iodine, and substituent R2 is selected from any one of hydrogen, C1-C30 alkyl, C1-C30 alkoxy or C1-C30 alkylthio. (4) POCl3 was fully dispersed in DMF, and a 1,2-dichloroethane solution of compound 5 was added. The reaction yielded compound 6. In compound 6, the substituents R1 and R2 are the same as those in formula I; (5) In toluene, under the action of acetic anhydride and boron trifluoride diethyl ether, compound 6 and compound A react to give compound 7; In compound 7, the substituents R1 and R2 are the same as those in formula I; Compound A is selected from one of the following: (6) POCl3 was fully dispersed in DMF, and a 1,2-dichloroethane solution of compound 7 was added. The reaction yielded compound 8. In compound 8, the substituents R1 and R2 are the same as those in formula I; (7) In toluene, under the action of acetic anhydride and boron trifluoride diethyl ether, compound 8 and compound B react to give compound 9; In compound 9, the substituents R1 and R2 are the same as those in formula I; Compound B is selected from one of the following: (8) In toluene, under the action of tetra(triphenylphosphine)palladium, compound 9 and compound C react to obtain an oligomer acceptor containing a bithiazole spacer group; Compound C is selected from one of the following: Among them, R5 is C1 to C 10 Any one of the alkyl groups.

4. The method for preparing the oligomer acceptor containing a bithiazole spacer group according to claim 3, characterized in that, Compounds 1, 2, 3, 4, 5, 6, 7, 8, and 9 have the structures shown below:

5. The method for preparing the oligomerized acceptor containing a bithiazole spacer group according to claim 3, characterized in that, Compound R2X is 1-bromo-2-octyldodecane, compound A is 2-(5-bromo-3-oxo-2,3-dihydro-1H-indene-1-yl)malononitrile, compound B is 2-(5,6-difluoro-3-oxo-2,3-dihydro-1H-indene-1-yl)malononitrile, and compound C is 4,4'-dinonyl-5,5'-bis(thiophen-2-yl)-2,2'-bisthiazole.

6. The method for preparing the oligomeric acceptor containing a bithiazole spacer group according to claim 3, characterized in that, Includes one or more of the following conditions: i. In step (1), the molar ratio of compound 1 to anhydrous tetrahydrofuran is 0.1-1 mol / L; the molar ratio of n-butyllithium (n-BuLi), tributyltin chloride and compound 1 is 1-1.07:1-1.1:1; the reaction conditions are: react at -78℃ for 0.5-2 hours, then react at room temperature for 20-24 hours, and the reaction is carried out under stirring conditions. ii. In step (2), the molar ratio of compound 3 to toluene is 0.05-1 mol / L; the molar ratio of tetra(triphenylphosphine)palladium, compound 1 and compound 3 in step (1) is 0.01-0.1:2.3-2.7:1; the reaction temperature is 100-120℃, the reaction time is 10-15h, and the reaction is carried out under reflux stirring conditions; iii. In step (3), the molar ratio of compound 3 in step (2) to the volume ratio of o-dichlorobenzene is 0.01-0.1 mol / L; the molar ratio of triphenylphosphine to compound 3 in step (2) is 6-10:1; the reaction temperature of compound 4 is 150-200℃, the reaction time is 10-15h, and the reaction is carried out under stirring conditions; the reaction solution obtained from the reaction of compound 4 is used to remove the solvent to obtain an intermediate. iv. In step (3), the molar ratio of compound 3 in step (2) to the volume ratio of DMF is 0.03-0.5 mol / L; the molar ratio of K2CO3, KI, compound R2X and compound 3 in step (2) is 10-24:10-24:10-24:1; the reaction temperature of compound R2X and the intermediate is 60-100℃, the reaction time is 10-14h, and the reaction is carried out under stirring conditions; the reaction solution obtained is extracted with dichloromethane, and the organic phase is purified by column chromatography to obtain compound 5. v. In step (4), the concentration of the 1,2-dichloroethane solution of compound 5 is 0.02-0.5 mol / L; the molar ratio of POCl3 to compound 3 in step (2) is 0.7-0.9:1; the volume ratio of the 1,2-dichloroethane solution of compound 5 to DMF is 15-25:1; the reaction temperature is -5-5℃, the reaction time is 4-8h, and the reaction is carried out under stirring conditions; the reaction solution obtained is extracted with dichloromethane, and the organic phase is purified by column chromatography to obtain compound 6. vi. In step (5), the molar ratio of compound 3 in step (2) to the volume ratio of toluene is 0.01-0.5 mol / L; the molar ratio of acetic anhydride, boron trifluoride ether and compound 3 in step (2) is 0.2-0.4:2-4:1; the molar ratio of compound 3 in step (2) to compound A is 1.6-1.8:1; the reaction temperature is 40-80℃, the reaction time is 5-15 min, and the reaction is carried out under stirring conditions; the reaction solution obtained is added to methanol, filtered to obtain the precipitate, the precipitate is dissolved in dichloroethane solvent, and purified by column chromatography to obtain compound 7; vii. In step (6), the concentration of the 1,2-dichloroethane solution of compound 7 is 0.02-0.5 mol / L; the molar ratio of POCl3 to compound 3 in step (2) is 0.7-0.9:1; the volume ratio of the 1,2-dichloroethane solution of compound 7 to DMF is 15-25:1; the reaction temperature is -5-5℃, the reaction time is 4-8h, and the reaction is carried out under stirring conditions; the reaction solution obtained is extracted with dichloromethane, and the organic phase is purified by column chromatography to obtain compound 8; viii. In step (7), the molar ratio of compound 3 in step (2) to the volume ratio of toluene is 0.01-0.5 mol / L; the molar ratio of acetic anhydride, boron trifluoride ether and compound 3 in step (2) is 0.1-0.3:1-3:1; the molar ratio of compound 3 in step (2) to compound B is 2-2.4:1; the reaction temperature is 40-80℃, the reaction time is 5-15 min, and the reaction is carried out under stirring conditions; the reaction solution obtained is added to methanol, filtered to obtain the precipitate, the precipitate is dissolved in dichloromethane solvent, and purified by column chromatography to obtain compound 9; ix. In step (8), the molar ratio of compound C to toluene is 0.02-0.5 mol / L; the molar ratio of tetra(triphenylphosphine)palladium, compound 3 in step (2), and compound C is 0.005-0.05:1:0.1-0.3; the reaction temperature is 100-120℃, the reaction time is 10-20h, and the reaction is carried out under stirring conditions; the reaction solution obtained is added to methanol to precipitate, the precipitate is collected and dissolved in chloroform, and purified by column chromatography to obtain an oligomer acceptor containing a bithiazole spacer group.

7. The application of the oligomer acceptor containing a bithiazole spacer group as described in claim 1 or 2, characterized in that, Electron acceptor materials used as photon-trapping active layers are applied in organic solar cells.

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