A non-fullerene acceptor material, mixture and use thereof

Abstract

This invention relates to the field of organic photovoltaic cell technology, specifically to a non-fullerene acceptor material and a mixture containing the same. The molecular structure is optimized by limiting the side-chain alkyl chain configuration and the selection of electron-withdrawing ends of the non-fullerene acceptor material. When the non-fullerene acceptor material of this invention is applied to the photoactive layer of an organic photovoltaic device, it exhibits excellent photoelectric performance.

Description

Technical Field

[0001] This invention relates to the field of organic photovoltaic cell technology, specifically to a non-fullerene acceptor material, a mixture thereof, and its application. Background Technology

[0002] Organic photovoltaic (OPV) cells have attracted widespread attention over the past few decades due to their significant advantage of being able to fabricate large-area devices using low-cost solution coating technology. Thanks to the development of various new OPV materials, especially non-fullerene acceptors (NFAs) with ADA (acceptor-donor-acceptor) structures, the power conversion efficiency (PCE) of a single OPV cell has exceeded 20%, achieving rapid progress.

[0003] In 2015, Zhan Xiaowei's team at Peking University designed a novel fused NFA based on the ITIC configuration, achieving a photoelectric conversion efficiency of 6.8% when paired with the polymer donor material PTB7-TH, marking a new milestone in organic photovoltaic acceptor materials. The fused central unit is characterized by the absence of easily torsional C-C single bonds, thus maintaining good planarity and rigidity. This structure is beneficial for π-electron delocalization and intramolecular charge transport. In 2017, Hou Jianhui's team at the Chinese Academy of Sciences further designed the IT-4F structure based on ITIC, achieving a photoelectric conversion efficiency of 13.1% when paired with the donor material PBDB-T-SF.

[0004] In 2019, the team led by Yingping Zou at Central South University designed and synthesized a novel acceptor material, Y6, based on the Y-type (A-DA'DA) structure. Combined with the polymer donor material PM6, it achieved a photoelectric conversion efficiency of 15.7%, leading the development of organic photovoltaic acceptor materials to a new stage. Subsequent development based on Y-type acceptor materials has led to various structural modifications of derivatives, such as L8-BO, BTP-eC9, N3, and BTP-H2, among other high-efficiency novel acceptor materials. With innovations in active layer materials, especially Y-type acceptor materials, the device performance of organic solar cells has achieved continuous breakthroughs and has now reached the stage of industrialization.

[0005] Although existing technologies have laid a certain foundation for the research of non-fullerene acceptor materials, there are very few acceptor materials that can be used for indoor photovoltaics, especially Y-type acceptor materials. In order to further improve OPV indoor photovoltaic technology to meet market applications, it is still necessary to develop new non-fullerene acceptor materials. Summary of the Invention

[0006] To address these remaining needs in the field, this invention provides a novel non-fullerene acceptor material that can effectively improve the photoelectric performance of OPV devices containing this acceptor material.

[0007] The first aspect of this invention provides a non-fullerene acceptor material having a structure as shown in general formula (I):

[0008]

[0009] in: Selected from structural formula (A-1) or (A-2):

[0010]

[0011] Indicates the connection site;

[0012] Y is selected from S or Se;

[0013] Each time Z appears, it is independently selected from S or Se;

[0014] Each time R1 appears, it is independently selected from branched alkyl groups having 8-12 carbon atoms;

[0015] Each time R2 appears, it is independently selected from branched alkyl groups having 8-20 carbon atoms.

[0016] Furthermore, the non-fullerene acceptor material is selected from structures shown as in general formula (II-1) or (II-2):

[0017]

[0018] In one embodiment, R2 is selected from branched alkyl groups with 8-12 carbon atoms; further, R2 is selected from... In one embodiment, each occurrence of R1 is independently selected from... Specifically, the non-fullerene acceptor material according to the present invention is selected from, but is not limited to, the following structures:

[0019]

[0020] A second aspect of the invention relates to a mixture comprising a non-fullerene receptor material as shown in general formula (I). In one embodiment, the mixture comprises at least two non-fullerene receptor materials as shown in general formula (I).

[0021] In one embodiment, the mixture comprises at least two non-fullerene acceptor materials as shown in general formula (II-1).

[0022] In one embodiment, the mixture comprises at least two non-fullerene acceptor materials as shown in general formula (II-2). Specifically, the mixture comprises at least two non-fullerene acceptor materials as shown in any of the structural formulas (N-1), (N-2), (N-3), (N-4), (N-5), (N-6), (N-7), (N-8), (N-9), (N-10), (N-11), and (N-12).

[0023] In one specific embodiment, the mixture according to the present invention comprises a non-fullerene acceptor material of general formula (I).

[0024] In another embodiment, the mixture according to the present invention comprises at least a first compound and a second compound, the first compound being selected from non-fullerene acceptor materials as described in general formula (I), and the second compound being selected from structures as described in general formula (III).

[0025]

[0026] in:

[0027] Y1 is selected from S or Se;

[0028] Each time Z1 appears, it is independently selected from S or Se;

[0029] Each time R3 appears, it is independently selected from branched alkyl groups having 8-12 carbon atoms;

[0030] Each time R4 appears, it is independently selected from branched alkyl groups having 8-20 carbon atoms.

[0031] In one embodiment, R4 is selected from branched alkyl groups with 8-12 carbon atoms.

[0032] Furthermore, the second compound is selected from the structure described in general formula (IV):

[0033]

[0034] In one embodiment, each occurrence of R3 is independently selected from...

[0035] Specifically, the second compound according to the present invention is selected from, but is not limited to, the following structures:

[0036]

[0037] In one embodiment, the mixture according to the present invention, wherein the first compound is selected from the structure of general formula (II-1).

[0038] In another embodiment, the mixture according to the present invention, wherein the first compound is selected from the structure described in general formula (II-2).

[0039] In one specific embodiment, the mixture according to the present invention, wherein the first compound is selected from compound (N-2) or (N-8); further, the second compound is selected from compound (S-2).

[0040] In one embodiment, the mass ratio of the non-fullerene acceptor material of general formula (I) to the compound of general formula (III) in the mixture according to the present invention is preferably from 0.01:0.99 to 1:1.

[0041] Furthermore, the mass ratio of the non-fullerene acceptor material of general formula (I) to the compound of general formula (III) is selected from 0.1:0.9-0.2:0.8.

[0042] In one specific embodiment, the mixture according to the present invention consists of a non-fullerene acceptor material of general formula (I) and a compound of general formula (III).

[0043] A third aspect of the present invention relates to an organic photovoltaic cell comprising a non-fullerene acceptor material as described in the first aspect or a mixture as described in the second aspect.

[0044] Furthermore, the organic photovoltaic cell according to the present invention comprises a cathode, an anode, and a photoactive layer located between the cathode and the anode, wherein the acceptor material of the photoactive layer is selected from the non-fullerene acceptor material as described in the first aspect or a mixture as described in the second aspect.

[0045] In one specific embodiment, the organic photovoltaic cell according to the present invention comprises, from bottom to top, an anode layer, an anode buffer layer, a photoactive layer, a cathode buffer layer, and a cathode layer; the photoactive layer acceptor material is selected from the non-fullerene acceptor material as described in the first aspect or a mixture as described in the second aspect.

[0046] The non-fullerene acceptor material described in this invention optimizes its molecular structure by limiting the alkyl chain configuration and electron-withdrawing ends of the compound. Specifically, modifications with appropriately long branched side chains reduce molecular packing, thereby facilitating charge migration. The single Br-substituted IC end enables fine-tuning of energy levels, thus exhibiting efficient charge separation. When used as a photoactive layer acceptor material in conjunction with a suitable polymer donor in indoor organic photovoltaic devices, it exhibits superior photoelectric performance.

[0047] The mixture described in this invention comprises compounds of formula (I) and formula (III), which have similar structures and high miscibility. When used as photoactive layer acceptor materials in indoor organic photovoltaic devices, it greatly optimizes the phase separation morphology of the blend film and improves the exciton dissociation and charge transfer efficiency, thereby achieving excellent indoor photoelectric conversion efficiency. Attached Figure Description

[0048] Figure 1 This is a schematic diagram of the structure of an organic photovoltaic device as an example.

[0049] Figure 2 The JV curves are for device examples 5-6 and device comparative example 3. Specific Implementation

[0050] The present invention will now be described in conjunction with preferred embodiments, but the present invention is not limited to the following embodiments. It should be understood that the appended claims summarize the scope of the present invention. Under the guidance of the inventive concept, those skilled in the art should realize that any changes made to the various embodiments of the present invention will be covered by the spirit and scope of the claims of the present invention.

[0051] In the following text, unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. Terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning consistent with their meaning in the context of the relevant art and should not be interpreted in an idealized or overly formal sense unless expressly defined herein.

[0052] In the description of this invention, it should be understood that the terms "upper," "lower," "between layers," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship commonly used when organic electronic devices are in use, or the orientation or positional relationship commonly understood by those skilled in the art. They are only used to facilitate the description of this invention and to simplify the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting the invention.

[0053] The terms "and / or," "or / and," and "and / or" as used herein include any one of two or more of the related listed items, as well as any and all combinations of the related listed items. These arbitrary and all combinations include any two related listed items, any more related listed items, or a combination of all related listed items. It should be noted that when at least three items are connected by at least two conjunctions selected from "and / or," "or / and," and "and / or," it should be understood that in this application, the technical solution undoubtedly includes technical solutions connected by "logical AND," and also undoubtedly includes technical solutions connected by "logical OR." For example, "A and / or B" includes three parallel solutions: A, B, and A+B. For example, the technical solution of "A, and / or, B, and / or, C, and / or, D" includes any one of A, B, C, and D (that is, a technical solution that is connected by "logical OR"), as well as any and all combinations of A, B, C, and D, that is, combinations of any two or three of A, B, C, and D, and also combinations of all four of A, B, C, and D (that is, a technical solution that is connected by "logical AND").

[0054] In this invention, organic photovoltaic devices, organic solar cells, OPV, and OSC have the same meaning and can be used interchangeably.

[0055] In this invention, the terms "photoactive layer" and "active layer" have the same meaning and can be used interchangeably.

[0056] In this invention, the phrase "independently selected" means that when one or more groups appear simultaneously and in multiple places in the compound, they are all independently selected and can be the same or different.

[0057] In describing the structural elements of the present invention, the terms "comprising" or "including" or similar terms used in the present invention mean that the device or material preceding the word covers the device or material listed after the word and its equivalents, but does not exclude other devices or materials.

[0058] The present invention further provides a method for synthesizing the non-fullerene acceptor material, as detailed below:

[0059] The synthetic route for structural formula (II-1) is as follows:

[0060]

[0061] The synthetic route for structure (II-2) is as follows:

[0062]

[0063] This invention does not impose any particular restrictions on the source of the raw materials used in the above reactions; commercially available raw materials or preparation methods well known to those skilled in the art can be used. This invention also does not impose any particular restrictions on the above reactions; conventional reactions well known to those skilled in the art can be used.

[0064] Compound Synthesis Examples

[0065] The following embodiments are provided to facilitate a better understanding of the disclosure of this invention, but are not intended to limit it in any way. Unless otherwise specified, the experimental methods used in the following embodiments are conventional methods, and the materials and reagents used are prior art and commercially available unless otherwise specified.

[0066] Synthesis of compound (A-1)

[0067]

[0068] Preparation of compound (A-1-1):

[0069] 2,4-Dibromobenzaldehyde (2.6 g, 10.0 mmol), dimethyl itaconic acid (1.7 g, 11.0 mmol), Pd(OAc)₂ (112.3 mg, 0.5 mmol), PPh₃ (262.3 mg, 1.0 mmol), NaOAc (2.5 g, 30.0 mmol), and THF (60 mL) were added to a 250 mL three-necked flask. The mixture was purged with nitrogen three times and heated to 110 °C overnight. After cooling to room temperature, the mixture was rapidly washed through a short silica gel column using petroleum ether as the eluent. The collected solution was concentrated and recrystallized from toluene to give compound (A-1-1) (2.2 g, yield 68.3%). MS: 323.42.

[0070] Preparation of compound (A-1-2):

[0071] Compound (A-1-1) (1.9 g, 6.0 mmol), LiOH (718.5 mg, 30.0 mmol), THF (30 mL), and H₂O (10 mL) were placed in a 100 mL round-bottom flask and stirred for 24 hours. After the reaction was complete, the reaction mixture was poured into approximately 100 mL of 1 M HCl, and then extracted with ethyl acetate and saturated brine. The organic phase was dried over Na₂SO₄, filtered, and concentrated to give compound (A-1-2) (1.7 g, 95.0%), which did not require further purification. MS: 294.80.

[0072] Preparation of compound (A-1-3):

[0073] Compound (A-1-2) (1.5 g, 5.0 mmol), acetic anhydride (12.5 mL), and THF (50 mL) were added to a reaction flask and heated to reflux for 2 hours. After cooling to room temperature, THF was removed under reduced pressure. The crude product was cooled to -20 °C, at which point a solid precipitated. This solid was rapidly filtered to give compound (A-1-3) (1.1 g, yield 76.9%). MS: 277.45.

[0074] Preparation of compound (A-1-4):

[0075] Compound (A-1-3) (832 mg, 3.0 mmol), ethyl acetoacetate (1.2 mg, 9.0 mmol), triethylamine (1.66 mL), and acetic anhydride were added to a 100 mL dried round-bottom flask and heated to 40 °C overnight. The reaction mixture was then poured into 30 mL of 1 MCl and heated to 80 °C overnight. After cooling to room temperature, the mixture was filtered, and the solid was washed repeatedly with water until the mother liquor was clear. The filter cake was dried under vacuum to give compound (A-1-4) (0.65 g, 78.5%). MS: 274.92.

[0076] Preparation of compound (A-1):

[0077] In a round-bottom flask, compound (A-1-4) (550 mg, 2.0 mmol) and malononitrile (158 mg, 2.4 mmol) were added. Acetic acid (1.6 mL), piperidine (0.6 mL), and DMF (10 mL) were added under a nitrogen atmosphere, and the mixture was stirred overnight. After the reaction was complete, 1 M HCl solution was added, and the mixture was stirred for two hours. The obtained solid was filtered and purified by column chromatography using dichloromethane as the eluent to give compound (A-1) (435 mg, yield 67.4%). MS: 322.85.

[0078] Synthesis of compound (A-2)

[0079]

[0080] Compound A-2-1 (450 mg, 2 mmol) and 8 mL of ethanol were added to a round-bottom flask and stirred until dissolved. Then, malononitrile (158 mg, 2.4 mmol) was added, and the mixture was purged three times. Sodium acetate (328 mg, 4 mmol) was added under nitrogen atmosphere, and the mixture was stirred. The reaction was allowed to proceed for 3 hours at room temperature until it was essentially complete. The reaction was stopped, and 50 mL of 10% hydrochloric acid diluted with ice water was added to precipitate the product. A large amount of dark black solid was observed. The crude product was purified by column chromatography to give approximately 418 mg of compound (A-2), yield: 76.3%. MS: 273.94.

[0081] Synthesis Example 1: Synthesis of Compound (N-1)

[0082]

[0083] Preparation of compounds (1-2):

[0084] Compound (1-1) (211 mg, 0.2 mmol) and compound (A-2) (55 mg, 0.2 mmol) were dissolved in 40 mL of chloroform, and 0.4 mL of pyridine was added. The mixture was heated under reflux for 4 h. The reaction mixture was cooled to room temperature, poured into methanol, filtered, and the solid was purified by silica gel column chromatography with PE:DCM = 1:2 (v / v) to give compound (1-2) (167 mg, 63.8%). MALDI-TOF-MS: 1310.62.

[0085] Preparation of compound (N-1):

[0086] Compounds (1-2) (131 mg, 0.1 mmol) and (A-1) (33 mg, 0.1 mmol) were dissolved in 30 mL of chloroform, and 0.3 mL of pyridine was added. The mixture was heated under reflux for 4 h. The reaction mixture was cooled to room temperature, poured into methanol, filtered, and the solid was purified by silica gel column chromatography with PE:DCM = 1:1 (v / v) to give compound (N-1) (122 mg, 75.3%). MALDI-TOF-MS: 1615.84.

[0087] Synthesis Example 2: Synthesis of Compound (N-2)

[0088]

[0089] Preparation of compound (2-2):

[0090] Compound (2-1) (234 mg, 0.2 mmol) and compound (A-2) (55 mg, 0.2 mmol) were dissolved in 40 mL of chloroform, and 0.4 mL of pyridine was added. The mixture was heated under reflux for 4 h. The reaction mixture was cooled to room temperature, poured into methanol, filtered, and the solid was purified by silica gel column chromatography with PE:DCM = 1:2 (v / v) to give compound (2-2) (187 mg, 65.6%). MALDI-TOF-MS: 1423.15.

[0091] Preparation of compound (N-2):

[0092] Compound (2-2) (143 mg, 0.1 mmol) and compound (A-1) (33 mg, 0.1 mmol) were dissolved in 30 mL of chloroform, and 0.3 mL of pyridine was added. The mixture was heated under reflux for 4 h. The reaction mixture was cooled to room temperature, poured into methanol, filtered, and the solid was purified by silica gel column chromatography with PE:DCM = 1:1 (v / v) to give compound (N-2) (138 mg, 79.7%). MALDI-TOF-MS: 1728.29.

[0093] Synthesis Example 3: Synthesis of Compound (N-8)

[0094]

[0095] Preparation of compound (N-8):

[0096] Compound (2-1) (117 mg, 0.1 mmol) and compound (A-1) (97 mg, 0.3 mmol) were dissolved in 30 mL of chloroform, and 0.3 mL of pyridine was added. The mixture was heated under reflux for 4 h. The reaction mixture was cooled to room temperature, poured into methanol, filtered, and the solid was purified by silica gel column chromatography with PE:DCM = 1:1 (v / v) to give compound (N-8) (133 mg, 74.6%). MALDI-TOF-MS: 1778.38.

[0097] Synthesis Example 4: Synthesis of Compound (N-10)

[0098]

[0099] Preparation of compound (4-2):

[0100] Compound tributyl(6-(2-butyloctyl)thieno[3,2-b]thieno-2-yl)stanane (2.6 g, 4.4 mmol), compound (4-1) (862 mg, 2.0 mmol), and Pd(PPh3)Cl2 (70.2 mg, 0.1 mmol) were dissolved in 100 mL of dry toluene and reacted overnight at 80 °C with stirring. After cooling to room temperature, the reaction mixture was extracted with dichloromethane and saturated brine. The organic phase was dried over anhydrous Na2SO4 and concentrated under reduced pressure. The crude product was purified by silica gel column chromatography with PE:DCM = 3:1 (v / v) to give compound (4-2) (1.3 g, 75.9%). MS: 886.78.

[0101] Preparation of compound (4-3):

[0102] Compound (4-2) (0.89 g, 1.0 mmol) and triethyl phosphate (5 mL) were dissolved in o-dichlorobenzene (10 mL). The mixture was purged with nitrogen three times and heated to 180 °C overnight. After cooling to room temperature, the reaction was extracted with dichloromethane and saturated brine. The organic phase was dried over anhydrous Na₂SO₄ and concentrated under reduced pressure to obtain the crude product. Without further purification, the crude product was added to a reaction flask along with 2-butyl-1-bromooctane (373.8 mg, 1.5 mmol), potassium hydroxide (196.4 mg, 3.5 mmol), and DMF (10 mL). The mixture was purged with nitrogen three times and heated to 110 °C for 12 h. DMF was removed by extraction with a large amount of water and ethyl acetate. The organic phase was dried over anhydrous Na₂SO₄ and concentrated under reduced pressure. The crude product was purified by silica gel column chromatography with PE:DCM = 6:1 (v / v) to obtain compound (4-3) (535 mg, 46.2%). MALDI-TOF-MS: 1158.73.

[0103] Preparation of compound (4-4):

[0104] Compound (4-3) (232 mg, 0.2 mmol) was dissolved in anhydrous POCl3 (613.3 mg, 4.0 mmol) under a nitrogen atmosphere, followed by the addition of DMF (73.1 mg, 1.0 mmol). The reaction mixture was heated to 90 °C and stirred overnight. After the reaction was complete, the mixture was cooled to room temperature, and the reaction solution was slowly added to ice water and extracted with ethyl acetate. The organic phase was dried over anhydrous Na2SO4 and concentrated under reduced pressure. The crude product was purified by silica gel column chromatography with PE:DCM = 1:2 (v / v) as the eluent to give solid compound (4-4) (147 mg, 60.4%). MALDI-TOF-MS: 1214.67.

[0105] Preparation of compound (N-10):

[0106] Compound (4-4) (122 mg, 0.1 mmol) and compound (A-1) (97 mg, 0.3 mmol) were dissolved in 30 mL of chloroform, and 0.3 mL of pyridine was added. The mixture was heated under reflux for 4 h. The reaction mixture was cooled to room temperature, poured into methanol, filtered, and the solid was purified by silica gel column chromatography with PE:DCM = 1:1 (v / v) to give compound (N-10) (137 mg, 75.1%). MALDI-TOF-MS: 1825.29.

[0107] Organic photovoltaic device fabrication examples

[0108] The fabrication process of the OPV device comprising the above-mentioned compounds is described in detail below through specific embodiments. The OPV device structure is as follows: Indium Tin Oxide (ITO) / ZnO / photoactive layer / MoO3 / Ag

[0109] The fabrication steps of device example 1 are as follows:

[0110] 1) ITO substrate cleaning:

[0111] Clean the ITO conductive glass with detergent, rinse it thoroughly, and then ultrasonically clean it for 15 minutes with deionized water, acetone, and isopropanol. After that, dry it with nitrogen and treat it in a plasma cleaner for 5 minutes to further clean the surface and improve wettability.

[0112] 2) Preparation of cathode buffer layer

[0113] The ZnO precursor solution (prepared by dissolving 100 mg of zinc acetate in 1.0 mL of 2-methoxyethanol and then adding 28 μL of ethanolamine) was uniformly spin-coated onto ITO in air at a speed of 4000 rpm for 30 s, and then dried at 220 °C for 30 min to obtain the cathode buffer layer.

[0114] 3) Preparation of photoactive layer

[0115] In a glove box (inert gas atmosphere), the photoactive layer material solution is uniformly spin-coated onto the cathode buffer layer at a rotation speed of 1800-4000 rpm to obtain an active material layer with a total thickness of approximately 100 nm; wherein the donor material in the photoactive layer material solution is selected from polymer D18; the acceptor material is selected from compound (N-1); polymer D18:compound (N-1) is added to chloroform solution at a mass ratio of 1:1.2, with a total concentration of 10 mg / mL.

[0116] 4) Preparation of the anode buffer layer

[0117] In high vacuum (1×10 -6 MoO3 was deposited onto the photoactive layer in millibars to obtain an anode buffer layer with a thickness of approximately 10 nm.

[0118] 5) Anode layer preparation

[0119] In high vacuum (1×10 -6 Ag is deposited onto the anode buffer layer in millibars to form an anode layer with a thickness of approximately 100 nm.

[0120] 6) Packaging

[0121] The device is encapsulated in a nitrogen glove box using UV-cured resin.

[0122] Device Examples 2-4:

[0123] The preparation methods of devices in Examples 2-4 are the same as those in Example 1, except that the acceptor material in the photoactive layer is different. Specifically, the acceptor material compound (N-1) in Example 1 is replaced with compound (N-2), compound (N-8), and compound (N-10), respectively. See Table 1 for details.

[0124] Comparative Examples of Devices 1-2

[0125] The preparation methods of Comparative Examples 1-2 are the same as those of Example 1, except that the acceptor material in the photoactive layer is different. Specifically, the acceptor material compound (N-1) in Example 1 is replaced with compound (Ref-1) and compound (Ref-2), respectively. See Table 1 for details.

[0126]

[0127] The organic photovoltaic device was tested under indoor light. The battery current-voltage curve was tested under a 3000K LED light source (1000 lux) simulator, and the photoelectric conversion efficiency was calculated, as shown in Table 1.

[0128] Table 1

[0129] Device Examples Photoactive layer for acceptor material Photoelectric conversion efficiency (%) Device Example 1 D18: Compound (N-1) 26.35 Device Example 2 D18: Compound (N-2) 26.84 Device Example 3 D18: Compound (N-8) 27.61 Device Example 4 D18: Compound (N-10) 27.23 Device Comparison Example 1 D18: Compound (Ref-1) 24.55 Device Comparison Example 2 D18: Compound (Ref-2) 22.39

[0130] According to the data in Table 1, the reason why the device embodiment 3 and device embodiment 4 are better than device embodiment 1 and device embodiment 2 is that the NFA described in general formula (II-2) can form more charge transfer channels in its blend with the polymer donor compared with the NFA described in general formula (II-1), which is beneficial to charge transport.

[0131] The reason why the device in Comparative Example 2 has low efficiency is that the branched alkyl group connected to N is too long. The excessively long branched alkyl group will cause the molecular plane of the small molecule acceptor material to be distorted, thereby affecting the molecular morphology and stacking of the acceptor.

[0132] The reason why the device performance of Examples 1-4 is better than that of Comparative Examples 1-2 is that the non-fullerene acceptor material and polymer donor material described in this invention have a more suitable energy level match in the active layer, forming a more suitable nanoscale aggregation and a more favorable face-up molecular stacking orientation, thereby achieving better device performance under indoor light conditions.

[0133] Device Example 5

[0134] The preparation method of device example 5 is the same as that of device example 1, except that the photoactive layer material solution is different. Specifically, the photoactive layer material solution is prepared as follows: the donor material in the photoactive layer material solution is selected from polymer PM6; the acceptor material is selected from compound (N-2) and compound (S-2); polymer PM6:compound (N-2):compound (S-2) is added to chloroform solution at a mass ratio of 1:0.2:1, and the total concentration is 16.5 mg / mL. See Table 2 for details.

[0135] Device Example 6

[0136] The preparation method of the device embodiment is the same as that of device embodiment 5, the difference being the photoactive layer material solution. Specifically, the photoactive layer material solution is prepared as follows: the donor material in the photoactive layer material solution is selected from polymer PM6; the acceptor material is selected from compound (N-8) and compound (S-2); polymer PM6:compound (N-8):compound (S-2) is added to chloroform solution at a mass ratio of 1:0.2:1, with a total concentration of 16.5 mg / mL. See Table 2 for details.

[0137] Device Comparison Example 3:

[0138] The preparation method of the device in Comparative Example 3 is the same as that in Device Example 5, except that the photoactive layer material solution is different. Specifically, the photoactive layer material solution is prepared as follows: the donor material in the photoactive layer material solution is selected from polymer PM6; the acceptor material is selected from compound (S-2); polymer PM6 and compound (S-2) are added to chloroform solution at a mass ratio of 1:1.2, with a total concentration of 16.5 mg / mL. See Table 2 for details.

[0139] The organic photovoltaic device was tested under indoor light. The battery current-voltage curve was tested under a 3000K LED light source (1000 lux) simulator, and the photoelectric conversion efficiency was calculated, as shown in Table 2.

[0140] Table 2

[0141]

[0142] According to the data in Table 2, the device embodiment 5 and device embodiment 6 are better than the device comparison embodiment 3. The reason is that the mixture described in this invention contains a first compound and a second compound, wherein the first compound and the second compound have the same core fused ring skeleton and are very miscible. This is very beneficial for achieving efficient synergy in balancing crystallization kinetics, changing phase separation and charge carrier transport behavior, thereby exhibiting stronger exciton dissociation ability, higher carrier mobility and more efficient charge extraction in OPV battery devices.

[0143] from Figure 2 As can be seen from the JV curve, the multi-element OPV device prepared by adding the first compound of this application to the PM6:compound (S-2) system has a significantly improved fill factor (FF) and thus achieves better photoelectric performance.

[0144] The preferred embodiments of this application have been described in detail above. However, this application is not limited to the specific details of the above embodiments. Within the scope of the technical concept of this application, various simple modifications can be made to the technical solution of this application, and these simple modifications all fall within the protection scope of this application.

Claims

1. A non-fullerene acceptor material, characterized in that: It has a structure as shown in general formula (I): （I） in: Select from structural formula (A-1) or (A-2): ; Indicates the connection site; Y is selected from S or Se; Each time Z appears, it is independently selected from S or Se; Each time R1 appears, it is independently selected from branched alkyl groups having 8-12 carbon atoms; R2 is selected from .

2. The non-fullerene acceptor material according to claim 1, characterized in that: The non-fullerene acceptor material is selected from structures as shown in general formula (II-1) or (II-2): 。 3. The non-fullerene acceptor material according to claim 2, characterized in that: Each occurrence of R1 is independently selected from... or .

4. The non-fullerene acceptor material according to claim 1, characterized in that: The non-fullerene acceptor material is selected from the following structures: 。 5. A mixture, characterized in that: The mixture comprises the non-fullerene acceptor material as described in any one of claims 1-4.

6. The mixture according to claim 5, wherein the mixture comprises at least a first compound and a second compound, characterized in that: The first compound is selected from the non-fullerene acceptor material as described in any one of claims 1-4, and the second compound is selected from the structure described in general formula (III): (III) in: Y1 is selected from S or Se; Each time Z1 appears, it is independently selected from S or Se; Each occurrence of R3 is independently selected from branched alkyl groups having 8-12 carbon atoms; Each time R4 appears, it is independently selected from branched alkyl groups having 8-20 carbon atoms.

7. The mixture according to claim 6, characterized in that: The second compound is selected from the structure described in general formula (IV): (IV)。 8. The mixture according to claim 7, characterized in that: The second compound is selected from the following structures: 。 9. The mixture according to claim 8, characterized in that: The first compound is selected from compound (N-2) or (N-8); the second compound is selected from compound (S-2).

10. An organic photovoltaic cell, characterized in that: The organic photovoltaic cell comprises a non-fullerene acceptor material as described in any one of claims 1-4 or a mixture as described in any one of claims 5-9.

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