Dimeric electron acceptor, preparation method thereof and organic photovoltaic device comprising dimeric electron acceptor

Abstract

The invention discloses a dimeric electron acceptor, which has one of the following structural formula: # imgabs0 #, in which R1 and R2 are respectively and independently selected from C1-C100 alkyl groups; x comprises H, F, Cl, I, NO2 or CN. According to the dimeric electron acceptor, a 3, 4-ethylenedioxythiophene or 3, 4-dimethoxythiophene unit serves as a connecting unit, an alkoxy side chain is connected to an outer side chain, the open-circuit voltage Voc of a solar cell device with the dimeric electron acceptor as an acceptor material can reach 1.02 V, the energy conversion efficiency PCE is 15.1%, and the dimeric electron acceptor is Vocgt reported at present; and the maximum value of PCE in a dimer acceptor system of 1V. The invention also provides a preparation method of the dimer electron acceptor and an organic photovoltaic device containing the dimer electron acceptor.

Description

Technical Field

[0001] The invention relates to the technical field of organic compound synthesis and organic solar cell device preparation, in particular to a dimeric electron acceptor, a preparation method thereof and an organic photovoltaic device comprising the dimeric electron acceptor. Background Art

[0002] In response to the energy crisis, organic solar cells have attracted much attention in recent years. With the continuous development and application of its active layer materials, new receptor materials have also become a research hotspot. Among them, non-fullerene receptors, especially the pioneering polycyclic electron receptors, have rapidly emerged, which is conducive to promoting the efficiency of organic solar cells to exceed 20%, which is close to the level of crystalline silicon solar cells, and pushing the field into the "non-fullerene era".

[0003] At present, the development of receptor molecules mainly focuses on three aspects: small molecules, dimers and polymers. Among them, polymers have good film-forming properties, but have disadvantages such as uncontrollable synthesis and large batch differences. Therefore, the repeatability of materials and devices is poor, which is a bottleneck in the commercialization process. Small molecules have a clear structure and are synthetically controllable, which solves the problem of batch differences. However, charge transport is strongly dependent on crystallinity, and the optimal active layer morphology is difficult to obtain, which affects the performance and stability of the device. The dimer material between the two has the advantages of both and has become a hot topic of research. At present, the opening voltage is mainly improved by introducing some groups that can weaken the charge transfer within the molecule into the molecular structure, so that the absorption spectrum is blue-shifted, but this usually reduces the filling and current while increasing the opening voltage.

[0004] In addition, since halogenated solvents have good solubility for materials, most photovoltaic devices in the past have been prepared using toxic halogenated solvents, such as chloroform, which limits the preparation of large-area devices in industry.

[0005] Therefore, it is urgent to invent a dimeric electron acceptor and organic photovoltaic device processed by non-toxic solvents with both high opening voltage and power conversion efficiency (PCE) to solve the problem of practical application. Summary of the invention

[0006] The purpose of the present invention is to combine high opening voltage characteristics with dimer advantages, and provide a high opening voltage dimer electron receptor, which is a new type of receptor material obtained by improving the existing non-fullerene receptor structure, with 3,4-ethylenedioxythiophene or 3,4-dimethoxythiophene units as connecting units, and alkoxy side chains connected to the outer chains. The solar cell device using the dimer electron receptor as the receptor material has an open circuit voltage V oc It can reach 1.02V, and the energy conversion efficiency PCE is 15.1%, which is the highest V oc The highest PCE value is found in the dimeric receptor system >1V.

[0007] One of the technical solutions adopted to achieve the purpose of the present invention is: a dimeric electron acceptor, which is a compound DYO-X1 or DYO-X2, wherein the chemical structure of the compound DYO-X1 is as follows (1), and the chemical structure of the compound DYO-X2 is as follows (2);

[0008]

[0009] Wherein: R1 and R2 are each independently selected from C1-C 100 Alkyl; X includes: H, F, Cl, I, NO2 or CN.

[0010] Another aspect of the present invention is to provide a method for preparing the above-mentioned dimeric electron acceptor, which method starts from the purchased raw materials and gradually synthesizes the dimer while ensuring the yield of the product in each step. In some embodiments, the method for preparing the above-mentioned dimeric electron acceptor, the organic synthesis reaction formula is as follows:

[0011] S1: Compound 1 is reacted to generate compound 2; in this step, N,N-dimethylformamide reacts with compound 1 under the catalysis of phosphorus oxychloride to undergo Vilsmeier-Haack reaction, and the reaction temperature is limited to 35-40°C, and the yield is above 80%. When the temperature exceeds 40°C, the yield of dialdehyde by-products increases significantly, and when the temperature is below 35°C, the reaction rate of the product compound 2 is too slow. In a preferred embodiment of the present invention, 1,2-dichloroethane with greater polarity is used as the solvent.

[0012]

[0013] As a feasible implementation method, S1 is to add compound 1 to a double-necked reaction bottle, use 1,2-dichloroethane as solvent, protect with argon, add N,N-dimethylformamide and phosphorus oxychloride, react at 35-40°C for 4h, and use TLC to determine whether the reaction endpoint is reached. After the reaction reaches the endpoint, add a saturated aqueous solution of sodium acetate and stir at room temperature for 2h, then extract the solution with dichloromethane, dry it with anhydrous sodium sulfate, and then elute with organic eluents of petroleum ether and dichloromethane to obtain the product, which is recorded as compound 2.

[0014] Furthermore, the feed ratio of the compound 1, phosphorus oxychloride and N,N-dimethylformamide is 1:(2.5-3):(2.5-3).

[0015] S2: Compound 2 is reacted with 5-bromocyanoindanone to generate compound 3; in this step, 5-bromocyanoindanone is introduced into the terminal group of compound 2. In some preferred embodiments, the solvent is chloroform, and the reactants are fully dissolved by chloroform, and the yield is as high as 85%. The boiling point of chloroform is 61.2°C, and the reaction temperature is set to 70°C to ensure that the solvent is refluxed.

[0016]

[0017] As a feasible implementation method, S2 is to weigh compound 2 and 5-bromocyanoindanone into a two-necked bottle, use chloroform as solvent, protect with argon, add pyridine, heat at 70°C for 12 hours, and use TLC to determine whether the reaction endpoint is reached. After the reaction is completed, the solid product, compound 3, is obtained after precipitation with methanol and purification by chromatography column.

[0018] Furthermore, the feed ratio of the compound 2 to 5-bromocyanoindanone is 1:(2-3).

[0019] S3: Compound 3 is reacted to form compound 4; the purpose of this step is to perform a formylation reaction at the end of the far electron-withdrawing terminal group of compound 3, the solvent for the formylation reaction is a halogenated hydrocarbon, and the reaction temperature is limited to 35-40°C to ensure that compound 3 is completely reacted by Vilsmeier-Haack reaction. In a preferred embodiment of the present invention, 1,2-dichloroethane with greater polarity is used as the solvent, and the yield exceeds 95%.

[0020]

[0021] As a feasible implementation method, S3 is to add compound 3 to a double-necked reaction bottle, use 1,2-dichloroethane as solvent, protect with argon, add N,N-dimethylformamide and phosphorus oxychloride, react at 40°C for 12 hours, and use TLC to determine whether the reaction endpoint has been reached. Then add a saturated aqueous solution of sodium acetate and stir at room temperature for 2 hours, then extract the solution with dichloromethane, dry it with anhydrous sodium sulfate, and then elute with organic eluents petroleum ether and dichloromethane to obtain a solid product, namely compound 4.

[0022] Furthermore, the feed ratio of the compound 3, phosphorus oxychloride and N,N-dimethylformamide is 1:(6-10):(6-10).

[0023] S4: Compound 4 is reacted to generate compound 5-1 / 5-2; in this step, zero-valent palladium is used as a catalyst, and the thiophene unit is bridged to two compounds 4 through Stillecoupling reaction. In a preferred embodiment of the present invention, tetrakis(triphenylphosphine)palladium is used as a catalyst and toluene is used as a solvent, and the yield is above 50%. The boiling point of toluene is 110.63°C, and the reaction temperature is set to 120°C to ensure that the solvent is refluxed.

[0024]

[0025]

[0026] As a feasible implementation method, S4 is to add compound 4 and the tin reagent of 3,4-ethylenedioxythiophene or the tin reagent of 3,4-dimethoxythiophene to a double-necked reaction bottle, protect with argon, use tetrakis(triphenylphosphine)palladium as a catalyst, use toluene as a solvent, heat to 120°C for 12h, and use TLC to determine whether the reaction end point has been reached. The obtained solution is extracted with dichloromethane and dried over anhydrous sodium sulfate, and the solid product, i.e., compound 5-1 or 5-2, is obtained after eluting with organic eluents, petroleum ether and dichloromethane.

[0027] Furthermore, the feed ratio of the compound 4, the organotin reagent and the zero-valent palladium is 1:(0.45-0.50):(0.15-0.2).

[0028] S5: Compound 5-1 or 5-2 is reacted to generate the corresponding compound DYO-X1 or DYO-X2; the purpose of this step is to introduce terminal groups under the catalysis of acetic anhydride and boron trifluoride etherate. In a preferred embodiment of the present invention, toluene is used as the solvent.

[0029]

[0030] As a feasible implementation method, S5 is to add compound 5-1 or 5-2 and the end group to a single-mouth reaction bottle, toluene is used as a solvent, acetic anhydride and boron trifluoride ether solution are added, react at room temperature for 0.5h, and use TLC to determine whether the reaction end point has been reached. After the reaction is completed, the solid product, i.e., the final product DYO-X1 or DYO-X2, is obtained by eluting with organic eluents petroleum ether and dichloromethane.

[0031] Furthermore, the feed ratio of the compound 5-1 or 5-2 to the terminal group is 1:(4-6).

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] 1. The present invention provides a dimeric electron acceptor, which is a novel acceptor material obtained by improving the existing non-fullerene acceptor structure. The 3,4-ethylenedioxythiophene or 3,4-dimethoxythiophene unit is used as a connecting unit, and an alkoxy side chain is connected to the outer chain to weaken the intramolecular charge transfer (ICT) effect, improve the lowest unoccupied orbital energy level (LUMO), and achieve an open-circuit voltage increase on the basis of ensuring efficiency. The open-circuit voltage V of a solar cell device using the dimeric electron acceptor as an acceptor material and in combination with a donor PM6 and a non-halogen solvent xylene is oc It can reach 1.02V and PCE is 15.1%, which is the highest V reported so far. oc The highest PCE value in the dimeric receptor system >1 V achieves a good balance between open circuit voltage and efficiency.

[0034] 2. The dimer electronic body of the present invention has a clear structure, precise molecular weight, stable performance, controllable structure, and is easy to purify, which effectively avoids problems such as instability between batches, and provides a reference method for achieving high-efficiency, high open-circuit voltage, good stability, flexibility, and large-area high-performance organic solar cells.

[0035] 3. In the dimeric electron acceptor of the present invention, 3,4-ethylenedioxythiophene or 3,4-dimethoxythiophene connecting units and outer chain oxygen atoms are simultaneously introduced, which greatly reduces the current drop caused by the introduction of alkoxy groups in existing non-fullerene acceptors.

[0036] 4. In the solar cell containing the above-mentioned dimeric electron acceptor of the present invention, the active layer solution containing the acceptor material and the donor material uses high-boiling non-toxic xylene as solvent, which can effectively avoid the toxic effects of traditional halogenated solvents on artificial and environmental pollution in actual industrial production.

[0037] 5. The present invention provides a method for preparing the above-mentioned dimeric electron acceptor, comprising a two-step formylation reaction and bridging of thiophene units by Stille coupling reaction, wherein each step cooperates with each other to obtain a dimeric electron acceptor, and has the characteristics of high intermediate process yield and easy product purification. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 This is the TLC chart of the reaction endpoint of step S1 in Example 1 of the present invention;

[0039] Figure 2 This is the TLC chart of the reaction endpoint of step S2 in Example 1 of the present invention;

[0040] Figure 3 This is the TLC chart of the reaction endpoint of step S3 in Example 1 of the present invention;

[0041] Figure 4 This is the TLC chart of the reaction endpoint of step S4 in Example 1 of the present invention;

[0042] Figure 5 This is the TLC chart of the reaction endpoint of step S5 in Example 1 of the present invention;

[0043] Figure 6 The product of step S1 in Example 1 of the present invention 1 H NMR spectrum;

[0044] Figure 7 The product of step S1 in Example 1 of the present invention 13 C NMR spectrum;

[0045] Figure 8 The product of step S2 in Example 1 of the present invention 1 H NMR spectrum;

[0046] Fig. 9 The product of step S2 in Example 1 of the present invention 13 C NMR spectrum;

[0047] Fig.10 The product of step S3 in Example 1 of the present invention 1 H NMR spectrum;

[0048] Fig.11 The product of step S3 in Example 1 of the present invention 13 C NMR spectrum;

[0049] Fig.12 The product of step S4 in Example 1 of the present invention 1 H NMR spectrum;

[0050] Fig.13 The product of step S4 in Example 1 of the present invention 13 C NMR spectrum;

[0051] Fig.14 is the mass spectrum of the final product DYO-1 in Example 1 of the present invention;

[0052] Fig.15 The UV-visible absorption spectra of the solution and the film of the final product DYO-1 in Example 1 of the present invention;

[0053] Fig.16 The current density-voltage (JV) curve of the final product DYO-1 in Example 1 of the present invention under the optimal conditions of processing with xylene;

[0054] Fig.17 This is the external quantum efficiency (EQE) curve of DYO-1 processed with xylene under optimal conditions in Example 1 of the present invention. DETAILED DESCRIPTION

[0055] The technical solutions in the embodiments of the present application will be described clearly and completely below in combination with the embodiments of the present application and the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0056] In the following description, the term "and / or" is used to describe the association relationship of associated objects, indicating that there may be three relationships. For example, A and / or B can represent: A exists alone, B exists alone, and A and B exist at the same time. A and B can be singular or plural.

[0057] In the following description, the terms "include", "comprising", "having" and "containing" are open-ended terms, meaning including but not limited to.

[0058] Those skilled in the art will appreciate that the numerical ranges in the embodiments of the present application are to be understood as each intermediate value between the upper and lower limits of the scope also specifically disclosed. Each smaller range between the intermediate value in any stated value or stated range and any other stated value or intermediate value in the described range is also included in the present application. The upper and lower limits of these smaller ranges may be independently included or excluded in the scope.

[0059] Unless otherwise specified, the technical / scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present application belongs. Although the present application describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the practice or testing of the present application.

[0060] Unless otherwise stated, the starting materials used herein are commercially available.

[0061] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0062] The present invention provides a dimeric electron acceptor, the general chemical structure of which is as follows (1) or (2):

[0063]

[0064] Wherein: R1 and R2 are each independently selected from C1-C 100 Alkyl; X includes: H, F, Cl, I, NO2 or CN.

[0065] The present invention provides a dimeric electron acceptor, which is a novel acceptor material obtained by improving the structure of an existing non-fullerene acceptor. The 3,4-ethylenedioxythiophene or 3,4-dimethoxythiophene unit is used as a connecting unit, and an alkoxy side chain is connected to the outer chain, so that the intramolecular charge transfer (ICT) effect can be weakened, the lowest unoccupied orbital energy level (LUMO) can be improved, and the open-circuit voltage can be improved on the basis of ensuring the efficiency. The open-circuit voltage V oc It can reach 1.02V and PCE is 15.1%, which is the highest V reported so far. oc The highest PCE value in the dimeric receptor system >1V achieves a good balance between the two.

[0066] The present invention has been subjected to a series of experiments before the application is filed. A part of the experimental results are now cited to further describe the invention in detail, and the following is a detailed description in conjunction with the embodiments.

[0067] Example 1

[0068] This embodiment provides a dimeric electron acceptor and a preparation method thereof. The structure of the dimeric electron acceptor DYO-1 is as follows:

[0069]

[0070] The preparation method of the dimeric electron acceptor is shown in S1 to S5:

[0071] S1: reacting compound 1 to generate compound 2;

[0072]

[0073] Specifically: 1.5 g of compound 1 was added to a two-necked reaction bottle, 35 mL of 1,2-dichloroethane was added as solvent, 0.3 mL (3 eq) of N,N-dimethylformamide and phosphorus oxychloride were added in an argon protective atmosphere, and the mixture was reacted at 40 °C for 4 h. Thin layer chromatography (TLC) was used to determine whether the reaction endpoint was reached. Figure 1 As shown, after confirming that the reaction is complete, 100 mL of saturated aqueous sodium acetate solution is added and stirred at room temperature for 2 h to obtain solution A;

[0074] Solution A was extracted with dichloromethane, dried over anhydrous sodium sulfate, and eluted with an organic eluent to obtain the product, i.e., compound 2. 1 H NMR spectra and 13 C NMR spectra are shown in Figure 6 and Figure 7 As shown, the yield is 80%; the organic eluent is petroleum ether and dichloromethane in a volume ratio of 4:1.

[0075] S2: reacting compound 2 with 5-bromocyanoindanone to generate compound 3;

[0076]

[0077] Specifically: 1.07 g of compound 2 and 0.4 g (4 eq) of 5-bromocyanoindanone were placed in a two-necked bottle, 40 mL of chloroform was added as solvent, 1 mL of pyridine was added under argon protection atmosphere, and then heated to 70 ° C for 12 h. The TLC method was used to determine whether the reaction reached the end point, such as Figure 2 As shown, after confirming that the reaction is complete, the product is obtained by methanol precipitation and purification (elution) by chromatography column. 1 H NMR spectra and 13 C NMR spectra are shown in Figure 8 and Fig. 9 As shown, compound 3 has a mass of 1.07 g and a yield of 85%. The eluent used for chromatography column purification is a mixture of petroleum ether and dichloromethane in a volume ratio of 3:1.

[0078] S3: reacting compound 3 to form compound 4;

[0079]

[0080] Specifically: 1 g of compound 3 was added to a two-necked reaction bottle, 35 mL of 1,2-dichloroethane was added as solvent, 0.4 mL (6 eq) of N,N-dimethylformamide and phosphorus oxychloride were added in an argon protective atmosphere, and the mixture was reacted at 40 °C for 12 h. The TLC method was used to determine whether the reaction endpoint was reached. Figure 3 As shown, after confirming that the reaction is complete, 100 mL of saturated aqueous sodium acetate solution is added and stirred at room temperature for 2 h to obtain solution C;

[0081] Solution C was extracted with dichloromethane, dried over anhydrous sodium sulfate, and eluted with an organic eluent to obtain 0.98 g of a solid product. 1 H NMR spectra and 13 C NMR spectra are shown in Fig.10 and Fig.11 As shown, compound 4 has a yield of 96%; the organic eluent is petroleum ether and dichloromethane in a volume ratio of 2:1.

[0082] S4: reacting compound 4 to generate compound 5-1;

[0083]

[0084] Specifically: 1 g of compound 4 and 0.12 g of the organotin reagent (0.45 eq) as shown in the above structure were added to a double-necked reaction bottle, and 0.15 g of tetrakis(triphenylphosphine)palladium (0.2 eq) and 35 mL of toluene solvent were quickly added under an argon protective atmosphere and reacted at 120° C. for 12 h. The TLC method was used to determine whether the reaction endpoint was reached. Figure 4 As shown, after confirming that the reaction is complete, solution D is obtained;

[0085] The solution D was extracted with dichloromethane, dried over anhydrous sodium sulfate, and then eluted with an organic eluent to obtain 0.5 g of a solid product. 1 H NMR spectra and 13 C NMR spectra are shown in Fig.12 and Fig.13 As shown, compound 5-1 has a yield of 50%. The organic eluent is obtained by mixing petroleum ether and dichloromethane in a volume ratio of 1:1.

[0086] S5: reacting compound 5-1 to generate the corresponding compound DYO-1;

[0087]

[0088] Specifically: 0.11 g of compound 5-1 and 30 mg of 5,6-difluorocyanoindanone were added to a single-mouth reaction bottle, 15 mL of toluene was added as solvent, 0.12 mL of acetic anhydride and 0.12 mL of boron trifluoride ether solution were added, and the reaction was carried out at room temperature for 0.5 h. The TLC method was used to determine whether the reaction endpoint was reached. Figure 5 As shown, after confirming that the reaction is complete, it is eluted with an organic eluent, the eluted solid phase is dissolved with chloroform, methanol is added to precipitate the solid, and the filter cake is obtained by filtration. The filter cake is dissolved with chloroform, concentrated and spun to obtain a recrystallized solid, the recrystallized solid is dissolved with chloroform and mixed with methanol, a solid phase is precipitated, and the precipitated solid phase is no longer increased, and the filter cake is obtained. The filter cake is washed with methanol and n-hexane for several times in sequence, and then dried after being pumped dry to obtain a solid product, i.e., the final product. The mass spectrum of the final product is shown as follows Fig.14 As shown, it is recorded as the final product DYO-1; the organic eluent is obtained by mixing petroleum ether and dichloromethane in a volume ratio of 1:1.

[0089] Example 2

[0090] This embodiment provides a dimeric electron acceptor and a preparation method thereof. The structure of the dimeric electron acceptor DYO-2 is as follows:

[0091]

[0092] This embodiment also provides a method for preparing the above-mentioned electron acceptor, which is the same as that of embodiment 1, except that:

[0093] S4: Compound 4 is reacted to generate compound 5-2, which is different from S4 in Example 1 in that the organotin compound is an organotin compound with the structure described below;

[0094]

[0095] S5: Compound 5-2 is reacted to generate the corresponding compound DYO-2, which is the same as S5 in Example 1.

[0096]

[0097] Example 3

[0098] This embodiment provides a dimeric electron acceptor and a preparation method thereof. The structure of the dimeric electron acceptor DYO-3 is as follows:

[0099]

[0100] This embodiment also provides a method for preparing the above-mentioned electron acceptor, which is the same as that of embodiment 2, except that:

[0101] S5: Compound 5-2 is reacted to generate compound DYO-3 which differs from S5 in Example 2 in that the terminal group has the following structure;

[0102] S5: Compound 5-2 is reacted to generate the corresponding compound DYO-3, which is the same as S5 in Example 2.

[0103]

[0104] Performance evaluation:

[0105] The final product DYO-1 was measured by UV-visible absorption spectroscopy. Fig.15 As shown, the test method includes:

[0106] The final products were prepared to a concentration of 10 -5 mol / L and 10 -2 mol / L xylene solution, the former is used to measure the UV absorption of the solution, and the latter is used to measure the UV absorption of the film by spinning the film on a quartz plate at 1200rpm.

[0107] In the UV-visible absorption spectrum measurement, the scanning range is 300-1000 nanometers, and the measuring instrument is Cary 5000 UV-vis spectrophotometer.

[0108] according to Fig.15 It can be seen that the solution has good absorption in the range of 300-800 nanometers, with the maximum absorption peak at 713 nanometers. The film has an obvious red shift relative to the solution and has a wider absorption range, with the maximum absorption peak at 758 nanometers, indicating that the film containing the dimeric electron acceptor of the present invention is conducive to obtaining a higher photoelectric conversion efficiency.

[0109] In each embodiment, the testing equipment for nuclear magnetic resonance is Bruker AV400 Spectrometer, and the testing equipment for mass spectrometry is Bruker Daltonics (AutoflexIII LRF200-CID).

[0110] Application Example 1:

[0111] The final product DYO-1 is used as an electron acceptor in the preparation of solar cell devices:

[0112] The device structure is ITO / PEDOT:PSS / donor material:acceptor material / PNDIT-F3N / Ag. The specific preparation process of the device is as follows: first, the ITO glass is ultrasonically cleaned with detergent, deionized water, acetone, and isopropanol solvent for 20 minutes each, blown dry with a nitrogen gun after being taken out, and UV-Ozone pretreated for 20 minutes, then PEDOT:PSS (Clevios P ​​VP Al4083) and deionized water are mixed in a volume ratio of 1:1 in the air, and spin-coated on the UV-Ozone pretreated ITO glass at 4400rpm / 20s by a coating machine to form an anode modification layer with a thickness of about 15nm, and then the substrate is placed on a 160℃ hot stage for thermal annealing for 15 minutes, and immediately transferred to a glove box for cooling before the next step. In a glove box, the donor material PM6 was mixed with the final product DYO-1 prepared in Example 1 at a donor concentration of 8 mg / mL and a donor-acceptor mass ratio of 1:1.2. In addition, 2-methoxynaphthalene (2-MN) was added as a solid additive at a total mass of 100% of the total mass of the donor and the acceptor, dissolved in o-xylene, heated and stirred on a hot plate at 100°C for 3 hours, and then cooled to 80°C to obtain an active layer solution, in which the donor concentration of the active layer solution was 8 mg / mL. The active layer solution was spin-coated at 3000 rpm / 20s by a homogenizer to form a film and placed on a hot plate at 90°C for thermal annealing for 5 minutes to form an active layer of about 100 nm thickness. After the substrate was cooled to room temperature, a methanol solution of PNDIT-F3N (concentration of 1 mg / mL, with 0.3% volume fraction of glacial acetic acid added as a cosolvent) was dissolved at room temperature for 3 h and spin-coated at 3300 rpm / 20 s to form a cathode interface with a thickness of about 12 nm. Finally, a metal top electrode Ag with a thickness of 120 nm was evaporated, and the vacuum degree was kept below 2×10 -4 Pa.

[0113] Under standard sunlight (AM 1.5G) irradiation conditions, the device was tested for JV using a computer-controlled Keithley 2400 digital source meter and for EQE using a QE-R solar cell spectral response measurement system. The results are shown in Tables 1 and 2. The light intensity was 100 mW cm -2 , AM 1.5G irradiation conditions.

[0114] Table 1: Comparison of device performance parameters of DYO-1 acceptor material and PM6 donor material prepared at different mass ratios.

[0115]

[0116] Table 2: Comparison of device performance parameters prepared by mixing donor material PM6 and acceptor material DYO-1 in a mass ratio of 1:1.2 and adding different mass fractions of solid additives (2-MN).

[0117]

[0118] In Table 2, the specific preparation process of the device is the same as that of Application Example 1, except that the amount of the solid additive 2-methoxynaphthalene (2-MN) is adjusted.

[0119] Fig.16 and Fig.17 They are the current density-voltage curve and external quantum efficiency curve of the device, Fig.16 and Fig.17 It shows that the V oc is 1.02V, short-circuit current density (J sc ) is 19.8 mA cm -2 , the fill factor (FF) is 74.8%, and the PCE is 15.1%. It can be seen that the bulk heterojunction solar cell device prepared using the compound of the present invention as a novel acceptor material has an outstanding V oc , and its highest PCE can reach 15.1%.

Claims

1. A dimeric electron acceptor, characterized in that: The dimeric electron acceptor is a compound DYO-X1 or DYO-X2, wherein the chemical structure of the compound DYO-X1 is as follows (1), and the chemical structure of the compound DYO-X2 is as follows (2): in: R1 and R2 are each independently selected from C1-C 100 Alkyl; X includes: H, F, Cl, I, NO2 or CN.

2. A method for preparing the dimeric electron acceptor as claimed in claim 1, characterized in that: include: S1: reacting compound 1 to generate compound 2; S2: reacting compound 2 with 5-bromocyanoindanone to generate compound 3; S3: reacting compound 3 to form compound 4; S4: reacting compound 4 to generate compound 5-1 or 5-2; S5: reacting compound 5-1 or 5-2 to generate the corresponding compound DYO-X1 or DYO-X2; Where R1 is C n H 2n+1 , wherein n = 1-100; R2 is C n H 2n+1 , wherein n=1-100; X is one of H, F, Cl, I, NO2 and CN.

3. The method according to claim 2, characterized in that S1 to S4 are all reacted under an inert gas protective atmosphere.

4. The method according to claim 3, characterized in that S1 comprises reacting compound 1, phosphorus oxychloride and N,N-dimethylformamide at 35-40° C.; and / or, in S1, the molar mass ratio of compound 1, phosphorus oxychloride and N,N-dimethylformamide is 1:(2.5-3):(2.5-3).

5. The method according to claim 3, characterized in that: S3 comprises reacting compound 3, phosphorus oxychloride and N,N-dimethylformamide at 35-40° C.; and / or, in S3, the molar mass ratio of compound 3, phosphorus oxychloride and N,N-dimethylformamide is 1:(6-10):(6-10).

6. The method according to claim 3, characterized in that: S4 is a Stille coupling reaction, and the catalyst is zero-valent palladium; and / or, in S4, the molar mass ratio of the compound 4, the organotin reagent and the zero-valent palladium is 1:(0.45-0.50): (0.15～0.2)。 7. The method according to claim 3, characterized in that In S2, the molar mass ratio of the compound 2 to 5-bromocyanoindanone is 1:(2-3); and / or, in S5, the molar mass ratio of the compound 5-1 or 5-2 to the terminal group is 1:(2-3). (4～6)。 8. An organic photovoltaic device, characterized in that: Comprising the dimeric electron acceptor as claimed in claim 1.

9. The organic photovoltaic device according to claim 8, characterized in that: The acceptor material is the dimeric electron acceptor, the donor material is PM6, and the solvent used to prepare the active layer solution containing the donor material and the acceptor material is xylene.

10. The organic photovoltaic device according to claim 9, characterized in that: The active layer solution also includes a solid additive 2-methoxynaphthalene.

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