Polymer and organic photovoltaic device

Abstract

The invention relates to the technical field of organic photovoltaic materials, in particular to a polymer and an organic photovoltaic device. The invention specifically provides a polymer, the polymer comprises a repeating unit shown as a formula (I): # imgabs0 #, and the polymer can be used as a donor material to be applied to an organic photovoltaic cell, and shows excellent device photoelectric properties by matching with a proper acceptor material.

Description

Technical Field

[0001] The present invention relates to the technical field of organic photovoltaic materials, and particularly relates to a polymer and an organic photovoltaic device. Background Art

[0002] Organic photovoltaic (OPV) cells are a new generation of photovoltaic technologies that use organic semiconductor materials to convert the absorbed sunlight energy into electrical energy. Compared with traditional silicon-based solar cells, they have unique advantages such as low preparation cost, flexibility, semi-transparency, color tunability, and solution printing processing, and have broad application and development prospects in indoor photovoltaics, building and equipment integration, automotive glass, and wearable devices.

[0003] An organic photovoltaic cell generally consists of five parts: a transparent substrate (such as glass, plastic, etc.), a transparent electrode (such as indium tin oxide (ITO), etc.), a photoactive layer, a metal electrode (such as Al, Ag, etc.), and an interfacial modification layer between the electrode and the photoactive layer. In the structure of an organic photovoltaic cell, the photoactive layer, as the core part of photoelectric conversion, is composed of an electron donor material and an electron acceptor material. It is required that the donor-acceptor materials have complementary light absorption ranges, matched orbital energy levels, high carrier mobilities, and a nano-blended film morphology, etc., so as to achieve efficient charge dissociation and transport to improve the photoelectric performance of the battery.

[0004] Currently, the widely used polymer donors are D-A copolymers obtained by alternating copolymerization of electron-donating (D) units and electron-withdrawing (A) units. However, the existing polymer donor materials still face problems such as poor solubility, too strong crystallinity, or the need for further improvement in photoelectric performance. Summary of the Invention

[0005] In order to solve the problems existing in the existing polymer donor materials and further improve the photoelectric performance of organic photovoltaic cell devices so as to promote the industrial application and development of OPV, the present invention has developed a new type of polymer material and applied it as a donor material in organic photovoltaic devices to improve the photoelectric performance of organic photovoltaic devices.

[0006] The present invention provides a polymer, and the polymer comprises a repeating unit shown in formula (I):

[0007]

[0008] Wherein:

[0009] R 1 Each occurrence independently selects from -CH 3 or -CD 3 ;

[0010] Each occurrence of X is independently selected from -H, -D, -F, -Cl, -CF 3 or -CN;

[0011] R 2 Each occurrence is independently selected from a straight-chain alkyl group having 1 to 20 carbon atoms or a branched-chain alkyl group having 3 to 20 carbon atoms;

[0012] R 3 Each occurrence is independently selected from -H, -D, a straight-chain alkyl group having 1 to 20 carbon atoms, or a branched-chain alkyl group having 3 to 20 carbon atoms;

[0013] Each occurrence is independently selected from a substituted or unsubstituted heteroaromatic group having 5 to 30 ring atoms;

[0014] The "substituted or unsubstituted" means that the defined group is unsubstituted or substituted by one or more substituents R, and each occurrence of the substituent R is independently selected from: -D, -F, -Cl, -Br, I, -CF 3 a straight-chain alkyl group having 1 to 20 carbon atoms, or a branched-chain alkyl group having 3 to 20 carbon atoms;

[0015] * represents the connection site.

[0016] Optionally, the Each occurrence is independently selected from

[0017] wherein: R 4 Each occurrence is independently selected from a straight-chain alkyl group having 1 to 20 carbon atoms, or a branched-chain alkyl group having 3 to 20 carbon atoms;

[0018] Each occurrence is independently selected from a substituted or unsubstituted heteroaromatic group having 5 to 6 ring atoms.

[0019] In one embodiment, the is selected from a heteroaromatic group having 5 ring atoms.

[0020] Furthermore, the is selected from wherein: Y is selected from O, S or Se.

[0021] In one embodiment, each occurrence of the R 2 is independently selected from a branched-chain alkyl group having 3 to 10 carbon atoms; specifically, the R 2 is selected from

[0022] In one embodiment, the R 1 is selected from -CH 3; Each occurrence of X is independently selected from -H, -D, -F, -Cl, -CF 3 or -CN.

[0023] In another embodiment, the R 1 is selected from -CD 3 ; Each occurrence of X is independently selected from -H, -D, -F, -Cl, -CF 3 or -CN.

[0024] Furthermore, the is selected from any one of the following groups:

[0025]

[0026] In a preferred embodiment, the repeating unit represented by formula (I) is selected from any one of the following structures, but not limited thereto:

[0027] In one embodiment, the polymer is selected from any one of the following structures:

[0028]

[0029]

[0030] Wherein: n is the number of repeating units, and n is selected from natural numbers greater than or equal to 2.

[0031] In one embodiment, each occurrence of the R 4 is independently selected from branched-chain alkyl groups having 3 to 10 carbon atoms. Specifically, the R 4 is selected from

[0032] In one embodiment, each occurrence of the R 3 is independently selected from -H, -D or branched-chain alkyl groups having 3 to 12 carbon atoms. Specifically, each occurrence of R 3 is independently selected from -H, -D or

[0033] Furthermore, the polymer represented by the general formula (II) is selected from the following structures:

[0034]

[0035] In one embodiment, in the general formula (II-1), R 1 is selected from -CH 3 ; X is selected from -H.

[0036] In another embodiment, in the general formula (II-1), R 1 is selected from -CH 3; Each occurrence of X is independently selected from -F.

[0037] In another embodiment, in the general formula (II-1), R 1 is independently selected from -CH 3 ; Each occurrence of X is independently selected from -Cl.

[0038] In one embodiment, in the general formula (II-1), R 1 is independently selected from -CD 3 ; X is selected from -H.

[0039] In another embodiment, in the general formula (II-1), R 1 is independently selected from -CD 3 ; Each occurrence of X is independently selected from -F.

[0040] In another embodiment, in the general formula (II-1), R 1 is independently selected from -CD 3 ; Each occurrence of X is independently selected from -Cl.

[0041] Further, in one embodiment, in the general formula (II-1), R 3 Each occurrence is independently selected from -H.

[0042] Further, the polymer represented by the general formula (III) is selected from the following structures:

[0043]

[0044] In one embodiment, in the general formula (III-1), R 1 is independently selected from -CH 3 ; X is selected from -H.

[0045] In another embodiment, in the general formula (III-1), R 1 is independently selected from -CH 3 ; Each occurrence of X is independently selected from -F.

[0046] In another embodiment, in the general formula (III-1), R 1 is independently selected from -CH 3 ; Each occurrence of X is independently selected from -Cl.

[0047] In one embodiment, in the general formula (III-1), R 1 is independently selected from -CD 3 ; X is selected from -H.

[0048] In another embodiment, in the general formula (III-1), R 1 is independently selected from -CD 3 ; Each occurrence of X is independently selected from -F.

[0049] In another embodiment, in the general formula (III-1), R 1 is selected from -CD 3 ; X is independently selected from -Cl each time it appears.

[0050] In one embodiment, in the general formula (III-1), R 3 each time it appears, is independently selected from branched alkyl groups having 3 to 20 carbon atoms.

[0051] In a specific embodiment, in the general formula (III-1), R 3 each time it appears, is independently selected from

[0052] Preferably, the polymers according to the present invention are selected from the following structures, but are not limited thereto:

[0053]

[0054]

[0055] In one embodiment, for the polymers according to the present invention, the number average molecular weight (Mn) of the polymer is selected from between 10,000 and 1,000,000. Further, the number average molecular weight (Mn) of the polymer is selected from between 20,000 and 1,000,000.

[0056] The present invention further relates to an organic photovoltaic device, which comprises the polymer as described above.

[0057] Further, the organic photovoltaic device comprises a cathode, an anode, and a photoactive layer located between the cathode and the anode, and the photoactive layer material comprises the polymer as described above.

[0058] In one embodiment, the photoactive layer material comprises a photoactive layer donor material and a photoactive layer acceptor material, and the photoactive layer donor material comprises the polymer as described above.

[0059] In one embodiment, the photoactive layer donor material comprises a first photoactive layer donor material and a second photoactive layer donor material. The first photoactive layer donor material is selected from the polymers as described above, and the second photoactive layer donor material is selected from PM6, PM7, PBDB-T, D18, PTQ10, PTQ11, PBQx-TCl, PBQx-TF, etc., but is not limited thereto.

[0060] In one embodiment, the photoactive layer acceptor material is selected from Y6, Y6-O, L8-BO, BTP-eC9, BTP-H2, IT-4F, FCC-Cl, etc., but is not limited thereto.

[0061] The preparation method of the photoactive layer material solution is as follows: dissolve the photoactive layer donor material and acceptor material in an organic solvent according to a certain mass ratio, and stir evenly to fully dissolve to obtain the photoactive layer solution.

[0062] The above solution is used to prepare the photoactive layer by a printing or coating preparation method. The printing or coating preparation method can be, but is not limited to, inkjet printing, gravure printing, spraying, letterpress printing, screen printing, dip coating, spin coating, blade coating, roller printing, reverse roller printing, lithography, flexography, rotary printing, spraying, brushing, pad printing, slot die coating, etc. Preferred are slot coating, spin coating and inkjet printing.

[0063] The preferred mass ratio of the photoactive layer donor material to the acceptor material in the organic solvent is: 1:0.8 to 1:1.5; further, the preferred mass ratio of the photoactive layer donor material to the acceptor material in the organic solvent is preferably: 1:1 to 1:1.5; the preferred mass ratio of the photoactive layer donor material to the acceptor material in the organic solvent is preferably: 1:1 to 1:1.2.

[0064] The concentration of the photoactive layer donor material in the organic solvent is preferably 3 to 15 mg / mL; further, the concentration of the photoactive layer donor material in the organic solvent is preferably 4 to 10 mg / mL.

[0065] The organic solvent is selected from: tetralin, 1,5-dimethyltetrahydrofuran, methyltetrahydrofuran, decalin, chlorobenzene, o-dichlorobenzene, 1,2,4-trichlorobenzene, 1,4-dimethylnaphthalene, toluene, o-xylene, m-xylene, p-xylene, mesitylene, o-diethylbenzene, m-diethylbenzene, p-diethylbenzene, 1,2,3,4-tetramethylbenzene, 1,2,3,5-tetramethylbenzene, 1,2,4,5-tetramethylbenzene, acetophenone, diphenyl ether, 2-methylthiophene, 3-methylthiophene, chloromethane, dichloromethane, chloroform, dichloroethylene, trichloroethylene, 1,2-trichlorotrifluoroethane, 1,2-dichloroethane, 1,1,1-trichloroethane, 1,1,2,2-tetrachloroethane, carbon tetrachloride, tetrahydrofuran, anisole, 2,4-dimethylanisole, 1-methylnaphthalene, morpholine, 1,4-dioxane, N-methylpyrrolidone, acetone, cyclopentanone, cyclohexanone, methyl ethyl ketone, ethyl acetate, n-butyl acetate, carbon disulfide, carbon tetrachloride, N,N-dimethylformamide, dimethylacetamide, dimethyl sulfoxide, indane, methyl benzoate, ethyl benzoate, acetonitrile, hexamethylphosphoramide, or a mixture of two or more thereof.

[0066] Furthermore, the photoactive layer material solution may further include additives for adjusting viscosity, film-forming properties, adhesion, etc. The additives may be selected from, but not limited to, 1,8-diiodooctane (DIO), diphenyl ether (DPE), anthracene, 1,4-diiodobenzene (DIB), 1,3-dibromo-5-chlorobenzene (DBCl), 3,5-dichlorobromobenzene (DCBB), 1-chloronaphthalene (1-CN), 1,3,5-tribromobenzene (TBB), etc., but not limited thereto.

[0067] At least one of the anode and the cathode is transparent or translucent to facilitate light incidence. The materials for preparing the electrodes may be selected from metals such as vanadium (V), chromium (Cr), zinc (Zn), silver (Ag), aluminum (Al), platinum (Pt), tungsten (W), copper (Cu), molybdenum (Mo), gold (Au), nickel (Ni), palladium (Pd), or alloys of the above metals, etc.; conductive nanomaterials such as metal nanowires, nanoparticle slurries, graphene, carbon nanotubes, etc.; metal oxides such as zinc oxide, indium oxide, indium tin oxide (ITO), indium zinc oxide (IZO), etc.; combinations of metals and oxides such as ZnO∶Al or SnO2∶Sb, etc.; and conductive polymers such as PEDOT:PSS, polypyrrole, and polyaniline, etc.; or materials with a multilayer structure such as LiF / Al, LiO2 / Al, LiF / Fe, MoO3 / Al, Al∶Li, Al∶BaF2, and Al∶BaF2∶Ba, etc., but not limited thereto.

[0068] In one embodiment, the organic photovoltaic cell sequentially stacks an anode, an anode buffer layer, a photoactive layer, a cathode buffer layer, and a cathode from bottom to top, and the photoactive layer contains the polymer as described above.

[0069] Preferably, the cathode buffer layer material may be selected from metal complexes with a low work function, metal oxides, metal salts, etc., such as metal complexes of 8-hydroxyquinoline, complexes containing Alq3, metal complexes containing Liq, LiF, Ca, titanium oxide (TiO x ), zinc oxide (ZnO), cesium carbonate (Cs 2 CO 3 ), etc.; it may also be a polymer material such as PFN-Br or PFN or PDINN or PDINO or PNDIT-F3N-Br or PNDIT-F3N, etc., but not limited thereto.

[0070] The anode buffer layer material is selected from PEDOT:PSS, molybdenum oxide (MoO x ), vanadium oxide (V 2 O 5 ), nickel oxide (NiO), tungsten oxide (WO x, preferably, x is selected from 2 or 3), small molecule self-assembled materials such as 2PACz, MeO-2PACz, etc., but not limited thereto.

[0071] It should be noted that in order to improve the performance of the organic photovoltaic cell device, the organic photovoltaic cell may further include other functional layers, including but not limited to charge blocking layers and charge transport layers.

[0072] Furthermore, the organic photovoltaic cell further includes a substrate. In one embodiment, the substrate is disposed on one side of the anode and on a different side from the photoactive layer. In another embodiment, the substrate is disposed on one side of the cathode and on a different side from the photoactive layer.

[0073] In one embodiment, as the substrate, a substrate having excellent transparency, surface smoothness, ease of operation, and waterproofness can be used. Specifically, a glass substrate, a thin film glass substrate, or a transparent plastic substrate can be used. The plastic substrate may include a film in a single-layer or multi-layer form, such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyether ether ketone (PEEK), polyimide (PI), parylene, etc., but not limited thereto, and a substrate commonly used for organic solar cells can also be used.

[0074] The organic photovoltaic cell according to the present invention is mainly used in the fields of indoor photovoltaics, wearable devices, intelligent Internet of Things, smart home, smart agriculture, building photovoltaics, new energy vehicles, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0075] Figure 1 is a schematic structural diagram of an embodiment of the organic photovoltaic device (OPV) of the present invention.

[0076] Figure 2 is the GPC spectrum of the polymer (P1) described in Polymer Synthesis Example 1.

[0077] Figure 3 is the GPC spectrum of the polymer (P10) described in Polymer Synthesis Example 7. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0078] To make the objectives, technical solutions, and effects of the present application clearer and more definite, the present application is further described in detail below. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application. All other embodiments obtained by those of ordinary skill in the art based on the described embodiments of the present invention without creative efforts shall fall within the scope of protection of the present invention.

[0079] The terms "and / or", "or / and", and "and / or" used in this article include any one of two or more related listed items, and also include any and all combinations of related listed items, and the 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 that are all connected by "logical and", and undoubtedly includes technical solutions that are all connected by "logical or". For example, "A and / or B" includes three parallel solutions of 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, the technical solution that is all connected by "logical OR"), and also includes any and all combinations of A, B, C, and D, that is, the combination of any two or any three of A, B, C, and D, and also includes the combination of four of A, B, C, and D (that is, the technical solution that is all connected by "logical AND").

[0080] In the present invention, organic photovoltaic device, organic solar cell, OPV and OSC have the same meaning and can be interchangeable.

[0081] In the present invention, photoactive layer and active layer have the same meaning and can be interchanged.

[0082] In the present invention, when a group contains multiple substituents with the same symbol, the substituents may be the same or different from each other. The six Rs on the benzene ring may be the same as or different from each other.

[0083] In the present invention, the "number of ring atoms" refers to the number of atoms constituting the ring itself of a structural compound (e.g., a monocyclic compound, a condensed ring compound, a cross-linked compound, a carbocyclic compound, a heterocyclic compound) in which atoms are bonded to form a ring. When the ring is substituted by a substituent, the atoms contained in the substituent are not included in the ring atoms. The same applies to the "number of ring atoms" described below unless otherwise specified. In an aromatic group, the number of ring atoms is the same as the number of carbon atoms; in a heteroaromatic group, the number of ring atoms is the number of carbon atoms plus the number of heteroatoms; for example, the number of ring atoms of a benzene ring is 6, the number of ring atoms of a naphthalene ring is 10, the number of ring atoms of a quinoline ring is 10, the number of ring atoms of a thienyl group is 5, and the number of ring atoms of a thienothiophene group is 8.

[0084] In the present invention, a "heteroaromatic group" refers to a heteroaromatic ring or its derivative in which the ring contains 1, 2, 3, 4, 5, 6 or more heteroatoms, and the heteroatoms can be at least one of B, O, N, P, Si, Se and S. The term "heteroaromatic group" as used herein also includes a group formed by the fusion of a heteroaromatic ring with one or more aromatic rings, cycloaliphatic rings or heterocyclic rings.

[0085] In the present invention, the expression that one or more groups are "independently selected from" means that when one or more groups appear simultaneously and at multiple positions in a compound, they are all independently selected and can be the same or different.

[0086] In the present invention, the single bond to which a substituent is attached passes through the corresponding ring, indicating that the substituent can be connected to an optional position of the ring. For example in which R is connected to any substitutable site of the benzene ring.

[0087] In the process of describing the structural elements of the present invention, words such as "comprising" or "including" used in the present invention mean that the devices or materials appearing before this word cover the devices or materials listed after this word and their equivalents, without excluding other devices or materials.

[0088] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by terms such as "upper", "lower", "between layers", etc. is based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which an organic solar cell device is usually placed during use, or the orientation or positional relationship commonly understood by those skilled in the art. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention.

[0089] In the present invention, "its combination", "any combination thereof", "any combination mode thereof", "combination", etc. include all suitable combination modes of any two, any three or any three or more items in the listed groups.

[0090] In the present invention, words such as "further", "even further", "especially", etc. are used for descriptive purposes and represent differences in content, but should not be construed as a limitation on the protection scope of the present invention.

[0091] In the present invention, "optionally", "optional", "option" mean that it can be either present or absent, that is, it refers to any one of two alternative schemes of "present" or "absent". If "optional" appears multiple times in a technical solution, without special instructions and without contradictions or mutual constraints, each "optional" is independent of each other.

[0092] In the present invention, among the technical features described in an open-ended manner, it includes a closed technical solution composed of the listed features, and also includes an open technical solution containing the listed features.

[0093] Polymer synthesis examples

[0094] The following examples facilitate a better understanding of the disclosure of the present invention and are not intended to limit it in any way. Unless otherwise specified, the experimental methods used in the following examples are all conventional methods, and the materials, reagents, etc. used, unless otherwise specified, are all prior art and can be obtained from commercial sources.

[0095] Monomer synthesis example 1: Synthesis of monomer M1

[0096]

[0097] Synthesis of compound 1-2:

[0098] Accurately weigh compound 1-1 (6.3 g, 30.0 mmol) and ultradry tetrahydrofuran (60 ml), and add them to a 250 mL three-necked flask in sequence. Replace nitrogen three times, cool to an internal temperature of 0 °C, and slowly add LDA (16.5 mL, 2.0 M) to the reaction system. After the addition is complete, keep the reaction at 0 °C for 5 min. Remove the ice bath, heat to an internal temperature of 50 °C and react for 0.5 h. While it is still hot, add benzo[1,2-B:4,5-B']dithiophene-4,8-dione (2.2 g, 10.0 mmol). After reacting for 2 h, cool the reaction solution to room temperature. Dissolve stannous chloride dihydrate (16.9 g, 75.0 mmol) in hydrochloric acid (37 mL, 10%), slowly add it to the reaction system, heat to an internal temperature of 50 °C, and react overnight. Quench with water the next day, extract with saturated brine and PE, dry the organic phase with anhydrous sodium sulfate, distill off the excess solvent under reduced pressure, mix with silica gel for column chromatography, and use n-hexane as the eluent to obtain about 4.1 g of compound 1-2, with a yield of 67.7%, MS: 607.47.

[0099] Synthesis of monomer M1:

[0100] Under anhydrous and anaerobic conditions, accurately weigh 1-2 (3.0 g, 5.0 mmol) and 30 mL of anhydrous tetrahydrofuran, and add them to a 100 mL three-necked flask in sequence. At -78 °C, add n-BuLi (8 mL, 2.5 M) dropwise. After reacting for two hours, add a solution of trimethyltin chloride (4.5 g, 22.5 mmol), transfer to room temperature, and react overnight. Add saturated potassium fluoride solution and stir for 2 hours, extract with petroleum ether 3 times, combine the organic phases, dry with anhydrous sodium sulfate, concentrate under vacuum, and recrystallize by heating to 70 °C with isopropanol to obtain about 3.8 g of monomer M1, with a yield of 81.2%, MS: 932.43.

[0101] Monomer Synthesis Example 2: Synthesis of Monomer M2

[0102]

[0103] Synthesis of Compound 2-2:

[0104] Accurately weigh Compound 2-1 (12.1 g, 120 mmol) and anhydrous tetrahydrofuran (120 mL), and add them to a 500 mL three-necked flask in sequence. Replace nitrogen three times. Cool down to -78 °C, and slowly add dropwise LDA (63 mL, 2.0 M), while maintaining the temperature below -75 °C during the addition. After the addition is complete, maintain this temperature and react for 2 h, then add TMSCl (14.3 g, 132 mmol), while maintaining the temperature below -65 °C during the addition. After the addition is complete, stop controlling the temperature and stir overnight. Quench with water the next day, extract with ethyl acetate, dry the organic phase with anhydrous sodium sulfate, concentrate under vacuum, load the sample on silica gel for column chromatography, and use n-hexane as the eluent to obtain about 16.7 g of Compound 2-2, with a yield of 80.2%, MS: 173.42.

[0105] Synthesis of Compound 2-3:

[0106] Accurately weigh Compound 2-2 (15.6 g, 90 mmol) and anhydrous tetrahydrofuran (90 mL), and add them to a 250 mL three-necked flask in sequence. Replace nitrogen three times. Cool down to -78 °C, and slowly add dropwise LDA (49.5 mL, 2.0 M), while maintaining the temperature below -75 °C during the addition. After the addition is complete, maintain this temperature and react for 1 h, then slowly add 2-ethylhexyl bromide (21.7 g, 112.5 mmol), while maintaining the temperature below -65 °C during the addition. After the addition is complete, stop controlling the temperature and stir overnight. Quench with water the next day, add saturated brine and extract with ethyl acetate, dry the organic phase with anhydrous sodium sulfate, concentrate under vacuum, and rectify to obtain about 11.7 g of Compound 2-3, with a yield of 45.6%, MS: 285.26.

[0107] Synthesis of Compound 2-4:

[0108] Accurately weigh Compound 2-3 (11.4 g, 40 mmol) and chloroform (100 mL), and add them to a 250 mL three-necked flask in sequence. Replace nitrogen three times. Add trifluoroacetic acid (18.2 g, 160 mmol) to the system and stir overnight at room temperature. Quench with ice water the next day, extract with dichloromethane, dry the organic phase with anhydrous sodium sulfate, concentrate under vacuum, and rectify to obtain about 7.2 g of Compound 2-4, with a yield of 84.4%, MS: 213.56.

[0109] Synthesis of Compound 2-5:

[0110] Accurately weigh compound 2-4 (6.4 g, 30.0 mmol), and add anhydrous tetrahydrofuran (60 mL) to a 250 mL three-necked flask in sequence. Replace nitrogen three times, cool down to an internal temperature of 0 °C, and slowly add LDA (16.5 mL, 2.0 M) dropwise to the reaction system. After the addition is complete, maintain the reaction at 0 °C for 5 min. Remove the ice bath, heat to an internal temperature of 50 °C and react for 0.5 h, and then add benzo[1,2-b:4,5-b']dithiophene-4,8-dione (2.2 g, 10.0 mmol) while it is hot. After reacting for 2 h, cool the reaction solution to room temperature. Dissolve stannous chloride dihydrate (16.9 g, 75.0 mmol) in hydrochloric acid (37 mL, 10%), slowly add it to the reaction system, heat to an internal temperature of 50 °C, and react overnight. Quench with water the next day, extract with saturated brine and PE, dry the organic phase with anhydrous sodium sulfate, distill off the excess solvent under reduced pressure, mix with silica gel for column chromatography, and use n-hexane as the eluent to obtain about 3.8 g of compound 2-5, with a yield of 61.9%, MS: 613.21.

[0111] Synthesis of monomer M2:

[0112] Under anhydrous and anaerobic conditions, accurately weigh 2-5 (3.1 g, 5.0 mmol), and add anhydrous tetrahydrofuran (30 mL) to a 250 mL three-necked flask in sequence. At -78 °C, add n-BuLi (8 mL, 2.5 M) dropwise. After reacting for two hours, add a solution of trimethyltin chloride (4.5 g, 22.5 mmol), transfer to room temperature, and react overnight. Add saturated potassium fluoride solution and stir for 2 h, extract with petroleum ether three times, combine the organic phases, dry with anhydrous sodium sulfate, concentrate under vacuum, and recrystallize by heating with isopropanol to 70 °C to obtain about 3.4 g of monomer M2, with a yield of 72.5%, MS: 939.30.

[0113] Synthesis example 3 of monomer: Synthesis of monomer M3

[0114]

[0115] Synthesis of compound 3-2:

[0116] Accurately weigh compound 3-1 (13.9 g, 120 mmol), and add anhydrous tetrahydrofuran (120 mL) into a 500 mL three-necked flask in sequence. Replace nitrogen three times. Cool down to -78 °C, and slowly add dropwise LDA (63 mL, 2.0 M), while maintaining the temperature below -75 °C. After the addition is completed, maintain this temperature and react for 2 h, then add TMSCl (14.3 g, 132 mmol), while maintaining the temperature below -65 °C. After the addition is completed, stop controlling the temperature and stir overnight. The next day, quench with water, extract with ethyl acetate, dry the organic phase with anhydrous sodium sulfate, concentrate under vacuum, mix with silica gel and perform column chromatography. The eluent is n-hexane to obtain about 17.9 g of compound 3-2, with a yield of 79.1%, MS: 188.51.

[0117] Synthesis of compound 3-3:

[0118] Accurately weigh compound 3-2 (17.0 g, 90 mmol), and add anhydrous tetrahydrofuran (90 mL) into a 250 mL three-necked flask in sequence. Replace nitrogen three times. Cool down to -78 °C, and slowly add dropwise LDA (49.5 mL, 2.0 M), while maintaining the temperature below -75 °C. After the addition is completed, maintain this temperature and react for 1 h, then slowly add isooctyl bromide (21.7 g, 112.5 mmol), while maintaining the temperature below -65 °C. After the addition is completed, stop controlling the temperature and stir overnight. The next day, quench with water, add saturated brine and extract with ethyl acetate. Dry the organic phase with anhydrous sodium sulfate, concentrate under vacuum, and perform rectification to obtain about 12.5 g of compound 3-3, with a yield of 46.2%, MS: 300.67.

[0119] Synthesis of compound 3-4:

[0120] Accurately weigh compound 3-3 (12.0 g, 40 mmol), and add chloroform (100 mL) into a 250 mL three-necked flask in sequence. Replace nitrogen three times. Add trifluoroacetic acid (18.2 g, 160 mmol) to the system and stir overnight at room temperature. The next day, quench with ice water, extract with dichloromethane, dry the organic phase with anhydrous sodium sulfate, concentrate under vacuum, and perform rectification to obtain about 7.4 g of compound 3-4, with a yield of 80.9%, MS: 228.71.

[0121] Synthesis of compound 3-5:

[0122] Accurately weigh compound 3-4 (6.9 g, 30.0 mmol), add ultra-dry tetrahydrofuran (60 ml) into a 250 mL three-necked flask, replace nitrogen three times, cool to 0 ° C, slowly add LDA (16.5 mL, 2.0 M) to the reaction system, keep 0 ° C for 5 min after the addition is complete. Remove the ice bath, heat to 50 ° C for 0.5 h, add benzo [1,2-B: 4,5-B'] dithiophene-4,8-dione (2.2 g, 10.0 mmol) while hot. After 2 h of reaction, cool the reaction solution to room temperature, dissolve stannous chloride dihydrate (16.9 g, 75.0 mmol) in hydrochloric acid (37 mL, 10%), slowly add to the reaction system, heat to 50 ° C for 5 min, and react overnight. The next day, water was added to quench the mixture, and saturated brine and PE were used for extraction. The organic phase was dried over anhydrous sodium sulfate, and the excess solvent was removed by vacuum distillation. The sample was mixed with silica gel and column chromatography was performed with n-hexane as the eluent to obtain about 4.1 g of compound 3-5 with a yield of 63.7% and MS: 643.01.

[0123] Synthesis of monomer M3:

[0124] Under anhydrous and oxygen-free conditions, accurately weigh 3-5 (3.2 g, 5.0 mmol) and anhydrous tetrahydrofuran (30 mL) were added to a 250 mL three-necked flask in sequence. At -78°C, n-BuLi (8 mL, 2.5 M) was added dropwise. After two hours of reaction, trimethyltin chloride (4.5 g, 22.5 mmol) solution was added, and the mixture was moved to room temperature and reacted overnight. Saturated potassium fluoride solution was added and stirred for 2 hours, and petroleum ether was extracted three times. The organic phases were combined and dried over anhydrous sodium sulfate, concentrated in vacuo, and recrystallized by heating to 70°C with isopropanol to obtain about 3.6 g of monomer M3, with a yield of 74.3% and MS: 968.94.

[0125] Monomer Synthesis Example 4: Synthesis of Monomer M4

[0126]

[0127] Synthesis of compound 4-2:

[0128] In a 500 mL three-necked flask, add ultra-dry tetrahydrofuran (220 mL), cool to -20 °C, add lithium aluminum deuteride (15.7 g, 375 mmol). After the addition is complete, cool to -10 °C, and add 4-1 (21.9 g, 150 mmol). During the addition, maintain the internal temperature at -5 °C. After the addition is complete, restore to room temperature and react overnight. Cool the reaction solution to 0 - 10 °C, add deuterated water (11 mL) to quench the reaction, add 10% sodium hydroxide solution (22 mL), and complete the addition. Stir the mixture at room temperature for 30 minutes, and sprinkle in an appropriate amount of diatomaceous earth. Filter the mixture, and wash the filter cake with dichloromethane. Extract the filtrate with dichloromethane, combine the organic phases, dry over anhydrous sodium sulfate, and concentrate in vacuo to obtain approximately 15.2 g of compound 4-2, with a yield of 84.9%, MS: 119.34.

[0129] Synthesis of compound 4-3:

[0130] Accurately weigh compound 4-2 (14.3 g, 120 mmol) and anhydrous tetrahydrofuran (120 mL), and add them successively to a 500 mL three-necked flask. Replace the nitrogen three times. Cool to -78 °C, and slowly add LDA (63 mL, 2.0 M), maintaining the temperature below -75 °C during the addition. After the addition is complete, maintain this temperature and react for 2 h, then add TMSCl (14.3 g, 132 mmol), maintaining the temperature below -65 °C during the addition. After the addition is complete, stop controlling the temperature and stir overnight. Quench with water the next day, extract with ethyl acetate, dry the organic phase over anhydrous sodium sulfate, concentrate in vacuo, and perform silica gel column chromatography with n-hexane as the eluent to obtain approximately 18.3 g of compound 4-3, with a yield of 79.6%, MS: 191.68.

[0131] Synthesis of compound 4-4:

[0132] Accurately weigh compound 4-3 (17.2 g, 90 mmol) and anhydrous tetrahydrofuran (90 mL), and add them successively to a 250 mL three-necked flask. Replace the nitrogen three times. Cool to -78 °C, and slowly add LDA (49.5 mL, 2.0 M), maintaining the temperature below -75 °C during the addition. After the addition is complete, maintain this temperature and react for 1 h, then slowly add 2-ethylhexyl bromide (21.7 g, 112.5 mmol), maintaining the temperature below -65 °C during the addition. After the addition is complete, stop controlling the temperature and stir overnight. Quench with water the next day, add saturated brine and extract with ethyl acetate. Dry the organic phase over anhydrous sodium sulfate, concentrate in vacuo, and perform distillation to obtain approximately 13.2 g of compound 4-4, with a yield of 48.3%, MS: 303.48.

[0133] Synthesis of compound 4-5:

[0134] Accurately weigh compound 4-4 (12.1 g, 40 mmol) and chloroform (100 mL) were added to a 250 mL three-necked flask, and nitrogen was replaced three times. Trifluoroacetic acid (18.2 g, 160 mmol) was added to the system and stirred overnight at room temperature. The next day, ice water was added to quench, dichloromethane was used for extraction, and the organic phase was dried with anhydrous sodium sulfate, vacuum concentrated, and distilled to obtain about 7.6 g of compound 4-5, with a yield of 82.0%, MS: 231.76.

[0135] Synthesis of compound 4-6:

[0136] Accurately weigh compound 4-5 (7.0 g, 30.0 mmol), add ultra-dry tetrahydrofuran (60 ml) into a 250 mL three-necked flask, replace nitrogen three times, cool to 0 ° C, slowly add LDA (16.5 mL, 2.0 M) to the reaction system, keep 0 ° C for 5 min after the addition is complete. Remove the ice bath, heat to 50 ° C for 0.5 h, add benzo [1,2-B: 4,5-B'] dithiophene-4,8-dione (2.2 g, 10.0 mmol) while hot. After 2 h of reaction, cool the reaction solution to room temperature, dissolve stannous chloride dihydrate (16.9 g, 75.0 mmol) in hydrochloric acid (37 mL, 10%), slowly add to the reaction system, heat to 50 ° C for 5 min, and react overnight. The next day, water was added to quench the mixture, and saturated brine and PE were used for extraction. The organic phase was dried over anhydrous sodium sulfate, and the excess solvent was removed by vacuum distillation. The sample was mixed with silica gel and column chromatography was performed with n-hexane as the eluent to obtain about 3.9 g of compound 4-6 with a yield of 60.1% and MS: 649.36.

[0137] Synthesis of monomer M4:

[0138] Under anhydrous and oxygen-free conditions, accurately weigh 4-6 (3.2 g, 5.0 mmol) and anhydrous tetrahydrofuran (30 mL) were added to a 100 mL three-necked flask in sequence. At -78°C, n-BuLi (8 mL, 2.5 M) was added dropwise. After two hours of reaction, trimethyltin chloride (4.5 g, 22.5 mmol) solution was added, and the mixture was moved to room temperature and reacted overnight. Saturated potassium fluoride solution was added and stirred for 2 hours, and petroleum ether was extracted three times. The organic phases were combined and dried over anhydrous sodium sulfate, concentrated in vacuo, and recrystallized by heating to 70°C with isopropanol to obtain about 3.7 g of monomer M4 with a yield of 75.9%, MS: 975.12.

[0139] Monomer Synthesis Example 5: Synthesis of Monomer M5

[0140]

[0141] Synthesis of compound 5-2:

[0142] In a 500 mL three-necked flask, add ultra-dry tetrahydrofuran (220 mL), cool down to -20 °C, add lithium aluminum deuteride (15.7 g, 375 mmol). After dropping addition, cool to -10 °C, and dropwise add 5-1 (24.4 g, 150 mmol). During the dropping process, maintain the internal temperature at -5 °C. After the dropping is complete, restore to room temperature and react overnight. Cool the reaction solution to 0 - 10 °C, add deuterium water (11 mL) to quench the reaction, add 10% sodium hydroxide solution (22 mL), and complete the dropping. Stir the mixture at room temperature for 30 minutes, and sprinkle in an appropriate amount of diatomaceous earth. Filter the mixture, and wash the filter cake with dichloromethane. Extract the filtrate with dichloromethane, combine the organic phases, dry with anhydrous sodium sulfate, and concentrate under vacuum to obtain about 18.5 g of compound 5-2, with a yield of 90.7%, MS: 135.73.

[0143] Synthesis of compound 5-3:

[0144] Accurately weigh compound 5-2 (16.3 g, 120 mmol) and anhydrous tetrahydrofuran (120 mL), and add them to a 500 mL three-necked flask in sequence, and displace nitrogen three times. Cool down to -78 °C, slowly dropwise add LDA (63 mL, 2.0 M), and maintain the temperature below -75 °C during this period. After the dropping is complete, maintain this temperature and react for 2 h, then add TMSCl (14.3 g, 132 mmol), and maintain the temperature below -65 °C during this period. After the dropping is complete, stop controlling the temperature and stir overnight. Quench with water the next day, extract with ethyl acetate, dry the organic phase with anhydrous sodium sulfate, concentrate under vacuum, and perform silica gel sample mixing column chromatography. The eluent is n-hexane to obtain about 19.1 g of compound 5-3, with a yield of 76.6%, MS: 207.94.

[0145] Synthesis of compound 5-4:

[0146] Accurately weigh compound 5-3 (18.7 g, 90 mmol) and anhydrous tetrahydrofuran (90 mL), and add them to a 250 mL three-necked flask in sequence, and displace nitrogen three times. Cool down to -78 °C, slowly dropwise add LDA (49.5 mL, 2.0 M), and maintain the temperature below -75 °C during this period. After the dropping is complete, maintain this temperature and react for 1 h, then slowly add 2-ethylhexyl bromide (21.7 g, 112.5 mmol), and maintain the temperature below -65 °C during this period. After the dropping is complete, stop controlling the temperature and stir overnight. Quench with water the next day, add saturated brine and extract with ethyl acetate. Dry the organic phase with anhydrous sodium sulfate, concentrate under vacuum, and perform rectification to obtain about 13.1 g of compound 5-4, with a yield of 45.5%, MS: 320.10.

[0147] Synthesis of compound 5-5:

[0148] Accurately weigh compound 5-4 (12.8 g, 40 mmol) and chloroform (100 mL) were added to a 250 mL three-necked flask, and nitrogen was replaced three times. Trifluoroacetic acid (18.2 g, 160 mmol) was added to the system and stirred overnight at room temperature. The next day, ice water was added to quench, dichloromethane was used for extraction, and the organic phase was dried with anhydrous sodium sulfate, vacuum concentrated, and distilled to obtain about 8.4 g of compound 5-5, with a yield of 84.8%, MS: 247.59.

[0149] Synthesis of compound 5-6:

[0150] Accurately weigh compound 5-5 (7.4 g, 30.0 mmol), add ultra-dry tetrahydrofuran (60 ml) into a 250 mL three-necked flask, replace nitrogen three times, cool the internal temperature to 0 ° C, slowly add LDA (16.5 mL, 2.0 M) to the reaction system, keep 0 ° C for 5 min after the addition is complete. Remove the ice bath, heat to an internal temperature of 50 ° C for 0.5 h, and add benzo [1,2-B: 4,5-B'] dithiophene-4,8-dione (2.2 g, 10.0 mmol) while hot. After 2 h of reaction, cool the reaction solution to room temperature, dissolve stannous chloride dihydrate (16.9 g, 75.0 mmol) in hydrochloric acid (37 mL, 10%), slowly add it to the reaction system, heat to an internal temperature of 50 ° C, and react overnight. The next day, water was added to quench the reaction, and the mixture was extracted with saturated brine and PE. The organic phase was dried over anhydrous sodium sulfate and the excess solvent was removed by distillation under reduced pressure. The mixture was subjected to silica gel column chromatography with n-hexane as the eluent to obtain about 4.8 g of compound 5-5 with a yield of 70.8% and MS: 681.43.

[0151] Synthesis of monomer M5:

[0152] Under anhydrous and oxygen-free conditions, accurately weigh 5-6 (3.4 g, 5.0 mmol) and anhydrous tetrahydrofuran (30 mL) were added to a 100 mL three-necked flask in sequence. At -78°C, n-BuLi (8 mL, 2.5 M) was added dropwise. After two hours of reaction, trimethyltin chloride (4.5 g, 22.5 mmol) solution was added, and the mixture was moved to room temperature and reacted overnight. Saturated potassium fluoride solution was added and stirred for 2 hours, and petroleum ether was extracted three times. The organic phases were combined and dried over anhydrous sodium sulfate, concentrated in vacuo, and recrystallized by heating to 70°C with isopropanol to obtain about 3.5 g of monomer M5, with a yield of 69.5% and MS: 1007.87.

[0153] Polymer Synthesis Example 1: Synthesis of Polymer (P1)

[0154]

[0155] Accurately weigh monomer M1 (933 mg, 1.0 mmol) and 6-1 (767 mg, 1.0 mmol), and sequentially add them into a 100 mL thick-walled pressure-resistant tube. Add 30 mL of ultra-dry o-xylene, and after purging with nitrogen for 5 min, add palladium tetrakis(triphenylphosphine) (58 mg, 0.05 mmol). Continue purging with nitrogen for 10 min, and stop heating after reacting at 130 °C for 30 h. Cool the reaction solution to room temperature, drop it into methanol to precipitate a solid, filter by suction. The filter cake is thoroughly washed successively with n-hexane, ethyl acetate, and dichloromethane in a Soxhlet extractor. The remaining solid is dissolved in chloroform, dropped into methanol to precipitate a solid, filter by suction. After the filter cake is dried in vacuo, about 1002 mg of polymer (P1) is obtained, with a yield of 82.6%, Mn: 25.6 KDa, and PDI: 3.1. The GPC chromatogram of polymer (P1) is as shown in Figure 2 shown.

[0156] Synthesis Example 2 of Polymer: Synthesis of Polymer (P2)

[0157]

[0158] Accurately weigh monomer M2 (939 mg, 1.0 mmol) and 6-1 (767 mg, 1.0 mmol), and sequentially add them into a 100 mL thick-walled pressure-resistant tube. Add 30 mL of ultra-dry o-xylene, and after purging with nitrogen for 5 min, add palladium tetrakis(triphenylphosphine) (58 mg, 0.05 mmol). Continue purging with nitrogen for 10 min, and stop heating after reacting at 130 °C for 30 h. Cool the reaction solution to room temperature, drop it into methanol to precipitate a solid, filter by suction. The filter cake is thoroughly washed successively with n-hexane, ethyl acetate, and dichloromethane in a Soxhlet extractor. The remaining solid is dissolved in chloroform, dropped into methanol to precipitate a solid, filter by suction. After the filter cake is dried in vacuo, about 989 mg of polymer (P2) is obtained, with a yield of 81.2%, Mn: 27.1 KDa, and PDI: 3.3.

[0159] Synthesis Example 3 of Polymer: Synthesis of Polymer (P3)

[0160]

[0161] Accurately weigh monomer M3 (969 mg, 1.0 mmol) and 6-1 (767 mg, 1.0 mmol), and sequentially add them into a 100 mL thick-walled pressure-resistant tube. Add 30 mL of ultra-dry o-xylene, and after purging with nitrogen for 5 min, add palladium tetrakis(triphenylphosphine) (58 mg, 0.05 mmol). Continue purging with nitrogen for 10 min, and stop heating after reacting at 130 °C for 30 h. Cool the reaction solution to room temperature, drop it into methanol to precipitate a solid, filter by suction. The filter cake is successively washed thoroughly with n-hexane, ethyl acetate, and dichloromethane in a Soxhlet extractor. The remaining solid is dissolved in chloroform and dropped into methanol to precipitate a solid. Filter by suction, and after vacuum drying the filter cake, about 995 mg of polymer (P3) is obtained, with a yield of 79.7%, Mn: 29.5 KDa, PDI: 3.0.

[0162] Polymer Synthesis Example 4: Synthesis of Polymer (P6)

[0163]

[0164] Accurately weigh monomer M5 (1008 mg, 1.0 mmol) and 6-1 (767 mg, 1.0 mmol), and sequentially add them into a 100 mL thick-walled pressure-resistant tube. Add 30 mL of ultra-dry o-xylene, and after purging with nitrogen for 5 min, add palladium tetrakis(triphenylphosphine) (58 mg, 0.05 mmol). Continue purging with nitrogen for 10 min, and stop heating after reacting at 130 °C for 30 h. Cool the reaction solution to room temperature, drop it into methanol to precipitate a solid, filter by suction. The filter cake is successively washed thoroughly with n-hexane, ethyl acetate, and dichloromethane in a Soxhlet extractor. The remaining solid is dissolved in chloroform and dropped into methanol to precipitate a solid. Filter by suction, and after vacuum drying the filter cake, about 905 mg of polymer (P6) is obtained, with a yield of 70.3%, Mn: 27.9 KDa, PDI: 3.2.

[0165] Polymer Synthesis Example 5: Synthesis of Polymer (P8)

[0166]

[0167] Accurately weigh monomer M2 (939 mg, 1.0 mmol) and 10-1 (907 mg, 1.0 mmol) and add them successively into a 100 mL thick-walled pressure-resistant tube. Add 30 mL of ultra-dry o-xylene. After purging with nitrogen for 5 min, add palladium tetrakis(triphenylphosphine) (58 mg, 0.05 mmol), and continue purging with nitrogen for 10 min. Stop heating after reacting at 130 °C for 30 h. Cool the reaction solution to room temperature, drop it into methanol, precipitate a solid, filter it by suction. The filter cake is thoroughly washed successively with n-hexane, ethyl acetate, and dichloromethane in a Soxhlet extractor. The remaining solid is dissolved in chloroform, dropped into methanol to precipitate a solid, filtered by suction. After the filter cake is dried under vacuum, about 1021 mg of polymer (P8) is obtained, with a yield of 75.2%, Mn: 32.7 KDa, and PDI: 3.4.

[0168] Polymer Synthesis Example 6: Synthesis of Polymer (P9)

[0169]

[0170] Accurately weigh monomer M3 (969 mg, 1.0 mmol) and 10-1 (907 mg, 1.0 mmol) and add them successively into a 100 mL thick-walled pressure-resistant tube. Add 30 mL of ultra-dry o-xylene. After purging with nitrogen for 5 min, add palladium tetrakis(triphenylphosphine) (58 mg, 0.05 mmol), and continue purging with nitrogen for 10 min. Stop heating after reacting at 130 °C for 30 h. Cool the reaction solution to room temperature, drop it into methanol, precipitate a solid, filter it by suction. The filter cake is thoroughly washed successively with n-hexane, ethyl acetate, and dichloromethane in a Soxhlet extractor. The remaining solid is dissolved in chloroform, dropped into methanol to precipitate a solid, filtered by suction. After the filter cake is dried under vacuum, about 896 mg of polymer (P9) is obtained, with a yield of 64.5%, Mn: 28.1 KDa, and PDI: 2.9.

[0171] Polymer Synthesis Example 7: Synthesis of Polymer (P10)

[0172]

[0173] Accurately weigh monomer M4 (975 mg, 1.0 mmol) and 10-1 (907 mg, 1.0 mmol), and sequentially add them into a 100 mL thick-walled pressure-resistant tube. Add 30 mL of ultra-dry o-xylene, blow nitrogen for 5 min, then add palladium tetrakis(triphenylphosphine) (58 mg, 0.05 mmol), continue to blow nitrogen for 10 min, and stop heating after reacting at 130 °C for 30 h. Cool the reaction solution to room temperature, drop it into methanol, precipitate a solid, filter by suction. The filter cake is successively washed thoroughly with n-hexane, ethyl acetate, and dichloromethane in a Soxhlet extractor. The remaining solid is dissolved in chloroform, dropped into methanol to precipitate a solid, filtered by suction. After the filter cake is dried in vacuo, about 1026 mg of polymer (P10) is obtained, with a yield of 73.6%, Mn: 25.3 KDa, and PDI: 3.2. The GPC spectrum of polymer (P10) is as Figure 3 shown.

[0174] Preparation and Characterization of Organic Photovoltaic Devices (OPV)

[0175] This example is given according to the preparation implementation method and characterization of the OPV device provided by the present invention, but the present invention is not limited to the following examples.

[0176] The structure of the organic photovoltaic device (OPV) is ITO / PEDOT:PSS / photoactive layer / PDINN / Ag (as Figure 1 shown), and its preparation method includes the following steps:

[0177] 1) Cleaning of ITO substrate

[0178] Clean the ITO conductive glass with detergent, rinse it thoroughly, and then ultrasonically clean it with deionized water, acetone, and isopropanol for 15 minutes. Then dry it with nitrogen and treat it in a plasma cleaner for 5 minutes to further clean the surface and improve wettability.

[0179] 2) Preparation of anode buffer layer

[0180] In air, spin-coat PEDOT:PSS (Clevios TM P VP Al 4083) uniformly on ITO at a spinning speed of 3000 rpm for 30 s, and dry it at 150 °C for 15 min to obtain the anode buffer layer.

[0181] 3) Preparation of photoactive layer

[0182] In a glove box (inert gas atmosphere), spin-coat the photoactive layer material solution uniformly on the anode buffer layer at a speed of 1800 - 4000 rpm to obtain a photoactive layer with a total thickness of about 100 nm.

[0183] The preparation method of the active layer material solvent is as follows: Dissolve the donor material and the acceptor material in chloroform, with a total concentration of 16.5 mg / mL; among them, the donor material in the photoactive layer material is selected from polymer (P1), the acceptor material is selected from NFA-1, and the mass ratio of polymer (P1):NFA-1 is 1:1.2.

[0184]

[0185] 4) Preparation of the cathode buffer layer

[0186] Spin-coat the cathode buffer layer material PDINN (dissolve PDINN in methanol to prepare a solution with a concentration of 1.5 mg / mL) uniformly on the photoactive layer at a rotation speed of 3000 rpm for 20 s to obtain the cathode buffer layer.

[0187] 5) Preparation of the cathode layer

[0188] In a high vacuum (1×10 -6 mbar), evaporate Ag onto the cathode buffer layer to form a cathode layer with a thickness of about 100 nm.

[0189] 6) Encapsulation

[0190] The device is encapsulated with an ultraviolet-curing resin in a nitrogen glove box.

[0191] Device Example 2:

[0192] The preparation method of Device Example 2 refers to the preparation method of Device Example 1, and the difference is that the selection of the donor material in the photoactive layer is different. Specifically, the donor material polymer (P1) in Device Example 1 is replaced with polymer (P2).

[0193] Device Example 3:

[0194] The preparation method of Device Example 3 refers to the preparation method of Device Example 1, and the difference is that the selection of the donor material in the photoactive layer is different. Specifically, the donor material polymer (P1) in Device Example 1 is replaced with polymer (P3).

[0195] Device Example 4:

[0196] The preparation method of Device Example 4 refers to the preparation method of Device Example 1, and the difference is that the selection of the donor material in the photoactive layer is different. Specifically, the donor material polymer (P1) in Device Example 1 is replaced with polymer (P6).

[0197] Device Comparative Example 1:

[0198] The preparation method of Device Comparative Example 1 refers to the preparation method of Device Example 1, with the difference being: the choice of donor material in the photoactive layer is different. Specifically, the donor material polymer (P1) in Device Example 1 is replaced with polymer PBDB-T.

[0199]

[0200] Device Comparative Example 2:

[0201] The preparation method of Device Comparative Example 2 refers to the preparation method of Device Example 1, with the difference being: the choice of donor material in the photoactive layer is different. Specifically, the donor material polymer (P1) in Device Example 1 is replaced with polymer Px.

[0202]

[0203] The prepared organic photovoltaic devices were tested for performance under indoor light. The current-voltage curves of the cells were tested under a 3000K LED light source (1000 lux) simulator, and the photoelectric conversion efficiency was calculated, as shown in Table 1.

[0204] Table 1

[0205] Device Embodiment Active Layer Donor-Acceptor Material Photovoltaic Conversion Efficiency (%) Device Embodiment 1 Polymer (P1): NFA-1 24.61 Device Embodiment 2 Polymer (P2): NFA-1 24.79 Device Embodiment 3 Polymer (P3): NFA-1 25.25 Device Embodiment 4 Polymer (P6): NFA-1 25.81 Device Comparative Example 1 Polymer PBDB-T: NFA-1 22.74 Device Comparative Example 2 Polymer Px: NFA-1 18.49

[0206] As can be seen from Table 1, the photoelectric conversion efficiencies of Device Examples 1-4 are better than those of Device Comparative Examples 1-2. The reasons are as follows: First, in the present invention, by introducing methyl or deuterated methyl at specific sites of the thiophene unit in the BDT side chain, the energy levels of the polymer are adjusted. When applied to indoor photovoltaics, the energy levels are more matched with the paired acceptor material, thus improving the charge separation. Second, the introduction of small-sized methyl groups does not have a negative impact on molecular packing, while the introduction of long-chain alkyl chains will increase the entanglement between polymers, resulting in a worse morphology.

[0207] In summary, the polymer according to the present invention by introducing methyl or deuterated methyl at specific sites of the thiophene unit in the BDT side chain has a more suitable energy level matching in the active layer, forming better nano-phase separation and π-π stacking. Therefore, the device exhibits more effective exciton dissociation, faster carrier transport, and less charge recombination. Therefore, the polymer described in the present invention shows more excellent indoor photoelectric conversion efficiency when used as a donor material in organic photovoltaic cells.

[0208] Device Example 5:

[0209] The preparation method of Device Example 5 refers to the preparation method of Device Example 1, with the difference being: the preparation method of the photoactive layer is different, specifically:

[0210] In a glove box (inert gas atmosphere), the photoactive layer material solvent was spin-coated uniformly on the anode buffer layer at a speed of 1800 - 4000 rpm to obtain a photoactive layer with a total thickness of about 100 nm.

[0211] The preparation method of the active layer material solvent is as follows: The donor material and the acceptor material are dissolved in chloroform with a total concentration of 10 mg / mL. Among them, the donor material in the photoactive layer material is selected from polymer (P8), the acceptor material is selected from NFA-2, and the mass ratio of polymer (P8):NFA-2 is 1:1.2.

[0212]

[0213] Device Example 6:

[0214] The preparation method of Device Example 6 refers to the preparation method of Device Example 1, and the difference lies in: The preparation method of the photoactive layer is different, specifically:

[0215] In a glove box (inert gas atmosphere), the photoactive layer material solvent was spin-coated uniformly on the anode buffer layer at a speed of 1800 - 4000 rpm to obtain a photoactive layer with a total thickness of about 100 nm.

[0216] The preparation method of the active layer material solvent is as follows: The donor material and the acceptor material are dissolved in chloroform with a total concentration of 10 mg / mL. Among them, the donor material in the photoactive layer material is selected from polymer (P9), the acceptor material is selected from NFA-2, and the mass ratio of polymer (P9):NFA-2 is 1:1.2.

[0217] Device Example 7:

[0218] The preparation method of Device Example 7 refers to the preparation method of Device Example 1, and the difference lies in: The preparation method of the photoactive layer is different, specifically:

[0219] In a glove box (inert gas atmosphere), the photoactive layer material solvent was spin-coated uniformly on the anode buffer layer at a speed of 1800 - 4000 rpm to obtain a photoactive layer with a total thickness of about 100 nm.

[0220] The preparation method of the active layer material solvent is as follows: The donor material and the acceptor material are dissolved in chloroform with a total concentration of 10 mg / mL. Among them, the donor material in the photoactive layer material is selected from polymer (P10), the acceptor material is selected from NFA-2, and the mass ratio of polymer (P10):NFA-2 is 1:1.2.

[0221] The prepared organic photovoltaic devices were tested for performance under indoor light. The current-voltage curves of the cells were tested under a 3000K LED light source (1000 lux) simulator, and the photoelectric conversion efficiency was calculated, as shown in Table 2.

[0222] Table 2

[0223] Device Embodiment Active Layer Donor-Acceptor Material Photovoltaic Conversion Efficiency (%) Device Embodiment 5 Polymer (P8): NFA-2 27.22 Device Embodiment 6 Polymer (P9): NFA-2 28.46 Device Embodiment 7 Polymer (P10): NFA-2 28.55

[0224] As can be seen from Table 2, the polymer described in the present invention, when used as a donor material in indoor organic photovoltaic cells, exhibits an excellent photoelectric conversion efficiency of over 27%.

[0225] The preferred embodiments of the present application have been described in detail above. However, the present application is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present application, various simple modifications can be made to the technical solutions of the present application, and these simple modifications all fall within the protection scope of the present application.

Claims

1. A polymer, characterized in that: The polymer comprises a repeating unit as shown in formula (I): in: Each occurrence of R1 is independently selected from -CH3 or -CD3; Each occurrence of X is independently selected from -H, -D, -F, -Cl, -CF3 or -CN; R2, at each occurrence, is independently selected from a straight chain alkyl group having 1 to 20 carbon atoms, or a branched chain alkyl group having 3 to 20 carbon atoms; R3, at each occurrence, is independently selected from -H, -D, a straight chain alkyl group having 1 to 20 carbon atoms, or a branched chain alkyl group having 3 to 20 carbon atoms; Each occurrence is independently selected from a substituted or unsubstituted heteroaromatic group having 5 to 30 ring atoms; The "substituted or unsubstituted" means that the defined group is unsubstituted or substituted by one or more substituents R, each occurrence of which is independently selected from: -D, -F, -Cl, -Br, I, -CF3, a straight-chain alkyl group having 1 to 20 carbon atoms, or a branched-chain alkyl group having 3 to 20 carbon atoms; * indicates the attachment site.

2. The polymer according to claim 1, characterized in that: Said Each occurrence is independently selected from Wherein: R4, each occurrence, is independently selected from a straight chain alkyl group having 1 to 20 carbon atoms, or a branched chain alkyl group having 3 to 20 carbon atoms; Each occurrence is independently selected from substituted or unsubstituted heteroaromatic groups having 5-6 ring atoms.

3. The polymer according to claim 2, characterized in that: Said Selected from Wherein: Y is selected from O, S or Se.

4. The polymer according to claim 1, characterized in that: Said Selected from the following groups:

5. The polymer according to claim 2, characterized in that: The repeating unit represented by the formula (I) is selected from any of the following structures:

6. The polymer according to claim 2, characterized in that: The polymer is selected from the following general structure: Wherein: n is the number of repeating units, and n is selected from a natural number greater than or equal to 2.

7. The polymer according to claim 6, characterized in that: Each occurrence of R3 is independently selected from -H, -D, or a branched alkyl group having 3 to 12 carbon atoms.

8. The polymer according to claim 1, characterized in that: The polymer is selected from the following structures:

9. An organic photovoltaic device, characterized in that: The organic photovoltaic device comprises the polymer according to any one of claims 1 to 8.

10. The organic photovoltaic device according to claim 9, characterized in that: The organic photovoltaic device comprises a cathode, an anode, and a photoactive layer located between the cathode and the anode, wherein the photoactive layer material comprises the polymer according to any one of claims 1 to 8.

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