Polymer and application thereof

Abstract

The invention relates to the technical field of organic photovoltaic cell materials, in particular to a polymer and application thereof. The present invention provides a copolymer comprising D-A wherein an electron-withdrawing A unit is selected from a first repeating unit and a second repeating unit and an electron-donating D unit is selected from a third repeating unit; by regulating and controlling the proportion of the two electron withdrawing units, on one hand, the energy level of the polymer is finely regulated, on the other hand, the molecular skeleton can be regulated and controlled according to the energy level, so that molecular accumulation is optimized, the polymer is used as a donor material in an organic photovoltaic device, and higher photoelectric conversion efficiency is realized by matching with a proper acceptor material.

Description

Technical Field

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

[0002] Organic photovoltaic cells (OPV) are a new type of photovoltaic technology that uses organic semiconductor materials (such as conjugated polymers or small molecule compounds) to convert light energy into electrical energy. Traditional solar cells use inorganic semiconductor materials such as silicon. Although their photoelectric conversion efficiency is high, the complex production process, high production cost, non-degradable inorganic semiconductor materials, and difficulty in flexible processing of traditional solar cells have greatly limited their application fields. Organic photovoltaic cells have advantages such as low cost, good processability, diverse and controllable material structures, light weight, flexible and bendable properties, and can be prepared by large-area printing, and have received wide attention.

[0003] The research on organic photovoltaic technology began in the 1970s, but it was not until 1986 that C.W. Tang et al. first proposed the bilayer heterojunction structure (Appl Phys Lett, 1986, 48, 183 - 185) that the device efficiency was significantly improved. After 2000, with the introduction of the bulk heterojunction (BHJ) structure, the development of new donor-acceptor materials, and the continuous optimization of the device structure, the efficiency of organic photovoltaic cells has made breakthrough progress. Currently, its laboratory efficiency has exceeded 20.8%, and it is at a critical node in the commercialization process.

[0004] However, with the rapid development of organic photovoltaic technology, the development of polymer donor materials still faces many problems. On the one hand, currently commonly used high-efficiency polymer donor materials (such as polymer donor materials PM6 and D18) face the problems of complex synthesis routes, long routes, and high costs. On the other hand, the device efficiency prepared by low-cost polymer donor materials cannot meet commercialization requirements and needs to be further improved. Therefore, the development of high-efficiency and low-cost polymer donor materials is of great significance for the commercial application of organic photovoltaic cells. Summary of the Invention

[0005] In order to overcome the defects existing in the above-mentioned prior art, the purpose of the present invention is to develop a high-efficiency and low-cost polymer donor material, thereby promoting the industrial development of organic photovoltaic technology.

[0006] The technical solution provided by the present invention is as follows:

[0007] A polymer, the polymer comprising a first repeating unit, a second repeating unit, and a third repeating unit; the first repeating unit has the structure shown in formula (A), the second repeating unit has the structure shown in formula (B), and the third repeating unit has the structure shown in formula (C):

[0008]

[0009] Wherein:

[0010] R1 is selected from -H, a straight-chain alkyl group having 1 to 10 carbon atoms, or a branched-chain alkyl group having 3 to 10 carbon atoms;

[0011] R2 is selected from branched-chain alkyl groups having 3 to 20 carbon atoms;

[0012] Z is selected from N or -COOR7;

[0013] R7 is 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;

[0014] R3 and R4 are independently selected from -H, -D, -F, or -Cl;

[0015] R5 and R6 are independently selected from -H, -D, -F, -Cl, a straight-chain alkyl group having 1 to 20 carbon atoms, or a branched-chain alkyl group having 3 to 20 carbon atoms;

[0016] * is a connection site.

[0017] In one embodiment, the polymer structure has the structure shown in formula (1):

[0018]

[0019] Wherein: a, b, and c are mole percentages, a is a real number where 0 < a < 1, b is a real number where 0 < b < 1, c is a real number where 0 < c < 1, and a + b + c = 1.

[0020] In one embodiment, a + b ≤ c.

[0021] In one of the embodiments, a + b = c.

[0022] In one of the embodiments, c = 0.5, a is a real number where 0.3 ≤ a < 0.5, and b is a real number where 0 < b ≤ 0.2.

[0023] In a specific embodiment, a = 0.4, b = 0.1, and c = 0.5.

[0024] In another specific embodiment, a = 0.45, b = 0.05, and c = 0.5.

[0025] When a + b = c, the polymer of the present invention has the structure shown in formula (2):

[0026]

[0027] Wherein:

[0028] x and y are mole percentages, x is a real number where 0 < x < 1, y is a real number where 0 < y < 1, and x + y = 1;

[0029] n is selected from integers greater than or equal to 2.

[0030] In one embodiment, x is a real number where 0.5 ≤ x < 1.

[0031] Further, x is a real number where 0.6 ≤ x < 1.

[0032] Further, x is a real number where 0.7 ≤ x < 1.

[0033] Further, x is a real number where 0.8 ≤ x < 1.

[0034] Further, x is a real number where 0.8 ≤ x ≤ 0.9.

[0035] In one embodiment, R2 is selected from branched alkyl groups having 10 to 20 carbon atoms.

[0036] In a specific embodiment, R2 is selected from

[0037] In one embodiment, R1 is selected from -H or straight-chain alkyl groups having 1 to 5 carbon atoms.

[0038] Further, R1 is selected from -H or methyl.

[0039] In one embodiment, Z is selected from N.

[0040] In another embodiment, Z is selected from -COOR7.

[0041] Further, R7 is selected from straight-chain alkyl groups having 1 to 10 carbon atoms or branched alkyl groups having 3 to 10 carbon atoms.

[0042] In a certain specific embodiment, R7 is selected from methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl, and

[0043]

[0044] In a certain specific example, Z is selected from

[0045] In one embodiment, R3 and R4 are selected from the same group.

[0046] In one of the embodiments, R3 and R4 are selected from -H or -F.

[0047] In a specific embodiment, the is selected from

[0048] In one embodiment, R5 and R6 are independently selected from -H, -D, -F, -Cl, or a straight-chain alkyl group having 1 to 10 carbon atoms or a branched-chain alkyl group having 3 to 10 carbon atoms.

[0049] In a specific embodiment, R5 and R6 are selected from -H.

[0050] In one embodiment, the polymer has the structural formula shown below:

[0051]

[0052] In one embodiment, the definitions of x and y in formula (3-1), formula (3-2), formula (3-3), and formula (3-4) are the same as those defined above.

[0053] In one of the embodiments, in formula (3-1), formula (3-2), formula (3-3), and formula (3-4), x = 0.9 and y = 0.1.

[0054] In one of the embodiments, in formula (3-1), formula (3-2), formula (3-3), and formula (3-4), x = 0.85 and y = 0.15.

[0055] In one of the embodiments, in formula (3-1), formula (3-2), formula (3-3), and formula (3-4), x = 0.8 and y = 0.2.

[0056] In one of the embodiments, in formula (3-1), formula (3-2), formula (3-3), and formula (3-4), x = 0.7 and y = 0.3.

[0057] In the present invention, the ratio of x and y of the polymer is controlled by adjusting the feeding ratio of the reaction raw materials.

[0058] In one example, for the polymer 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 100,000.

[0059] The present invention further relates to an organic photovoltaic device, which includes a cathode, an anode, and a photoactive layer located between the cathode and the anode, and the photoactive layer includes the polymer described above.

[0060] Further, for the organic photovoltaic device according to the present invention, the photoactive layer further comprises an organic compound represented by formula (4):

[0061]

[0062] Wherein:

[0063] R8 and R9 are selected from straight-chain alkyl groups having 1 to 20 carbon atoms or branched-chain alkyl groups having 3 to 20 carbon atoms;

[0064] R 10 and R 11 are each independently selected from straight-chain alkyl groups having 1 to 20 carbon atoms, branched-chain alkyl groups having 3 to 20 carbon atoms, phenyl groups which are unsubstituted or substituted by R, pyridyl groups which are unsubstituted or substituted by R, and thiophenyl groups which are unsubstituted or substituted by R;

[0065] The R is selected from -D, straight-chain alkyl groups having 1 to 20 carbon atoms, branched-chain alkyl groups having 3 to 20 carbon atoms, straight-chain alkoxy groups having 1 to 20 carbon atoms, or branched-chain alkoxy groups having 3 to 20 carbon atoms;

[0066] R 12 Each occurrence is independently selected from -H, -D, methyl, methoxy, -F, -Cl, -Br, -I, -CN, or -CF3.

[0067] In one embodiment, the R8 and R9 are selected from

[0068] In one embodiment, the R 10 and R 11 are selected from any of the following structures:

[0069]

[0070] In one embodiment, the is selected from the following structures:

[0071]

[0072] In one specific embodiment, the organic compound represented by formula (4) is selected from the following structures, but is not limited thereto:

[0073]

[0074] In one specific embodiment, for the organic photovoltaic device according to the present invention, the photoactive layer comprises a photoactive layer donor material and a photoactive layer acceptor material, the photoactive layer donor material comprises the polymer as described above, and the active layer acceptor material is selected from the organic compounds represented by formula (4).

[0075] The method for preparing the photoactive layer is as follows: dissolving a photoactive layer donor material and an acceptor material in an organic solvent according to a certain mass ratio, and stirring evenly to fully dissolve to obtain a photoactive layer solution.

[0076] The organic solvent is preferably selected from one of 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 of them.

[0077] 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, lithographic printing, flexographic printing, rotary printing, spraying, brush coating, pad printing, slot die coating, etc. Preferred are slot coating, spin coating and inkjet printing.

[0078] The mass ratio of the photoactive layer donor material to the acceptor material in the organic solvent is preferably 1:0.8 to 1:1.5; further, the 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 mass ratio of the photoactive layer donor material to the acceptor material in the organic solvent is preferably 1:1 to 1:1.2.

[0079] 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 6 to 10 mg / mL.

[0080] In one embodiment, the above-mentioned photoactive layer solution may further include additives for adjusting viscosity, film-forming performance, adhesion improvement, 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.

[0081] In one embodiment, the organic photovoltaic device according to the present invention includes an anode, an anode buffer layer, a photoactive layer, a cathode buffer layer, and a cathode layer stacked in this order from bottom to top. The description of the photoactive layer material is the same as above.

[0082] At least one of the anode and the cathode is transparent or semi-transparent to facilitate the incidence of light. The materials used to prepare 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.

[0083] Preferably, the cathode buffer layer material may be selected from metal complexes with low work functions, 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 (Cs2CO3), 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.

[0084] The anode buffer layer material is selected from PEDOT:PSS, molybdenum oxide (MoO x ), vanadium oxide (V2O5), 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.

[0085] It should be noted that, in order to improve the device performance of the organic photovoltaic cell, the organic photovoltaic cell may further include other functional layers, including but not limited to a charge blocking layer, a charge transport layer, and a passivation layer.

[0086] 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.

[0087] In one embodiment, as the substrate, a substrate having excellent transparency, surface smoothness, ease of handling, and water resistance 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 is not limited thereto, and substrates commonly used in organic solar cells can also be used.

[0088] 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 homes, smart agriculture, building photovoltaics, new energy vehicles, etc.

[0089] Advantages of the present invention:

[0090] The present invention provides a polymer containing D-A copolymerization, wherein the electron-withdrawing A unit is selected from a first repeating unit and a second repeating unit, and the electron-donating D unit is selected from a third repeating unit; by regulating the ratio of the two electron-withdrawing units, on the one hand, the energy level of the polymer can be finely regulated, and on the other hand, the molecular skeleton of the polymer can be regulated by adjusting the ratio of the two electron-withdrawing units, thereby optimizing the molecular packing of the active layer. When used as a donor material in an organic photovoltaic device and combined with a suitable acceptor material, a relatively high power conversion efficiency is achieved.

[0091] Furthermore, the first repeating unit, the second repeating unit, and the third repeating unit in the polymer provided by the present invention have a relatively low synthesis cost, replacing the complex and costly repeating units (such as the substituted BDT unit containing thiophene) contained in most current high-efficiency polymers, thereby significantly reducing the cost, being suitable for industrial mass preparation, and promoting the industrial preparation and commercial promotion of organic photovoltaic cells. Description of the Drawings

[0092] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0093] Figure 1 It is a schematic structural diagram of a device embodiment of the present invention.

[0094] Figure 2 It is the GPC spectrum of the polymer (P2) described in Polymer Synthesis Example 2; Specific Embodiments

[0095] The following embodiments are provided to better further understand the present invention. They are not limited to the best embodiments, and do not constitute a limitation to the content and protection scope of the present invention. Any product that is the same as or similar to the present invention obtained by anyone under the inspiration of the present invention or by combining the features of the present invention with other prior art features falls within the protection scope of the present invention.

[0096] As used herein, the terms "and / or", "or / and", "and / or" include any one of two or more related listed items, and also include any and all combinations of the related listed items. The said any and all combinations include any two related listed items, any more related listed items, or the combination of all related listed items. It should be noted that when at least two conjunctions selected from "and / or", "or / and", "and / or" are used to connect at least three items, it should be understood that in this application, this technical solution undoubtedly includes the technical solution connected by "logical AND", and also undoubtedly includes the technical solution connected by "logical OR". For example, "A and / or B" includes three parallel solutions: A, B, and A + B. Another example, the technical solution of "A, and / or, B, and / or, C, and / or, D" includes any one of A, B, C, D (that is, the technical solution connected by "logical OR"), and also includes any and all combinations of A, B, C, D, that is, it includes the combination of any two or any three of A, B, C, D, and also includes the four-item combination of A, B, C, D (that is, the technical solution connected by "logical AND").

[0097] In the present invention, organic photovoltaic device, organic photovoltaic cell, organic solar cell, OPV, OSC have the same meaning and can be interchanged.

[0098] In the present invention, photoactive layer and active layer have the same meaning and can be interchanged.

[0099] In the present invention, when a group contains multiple substituents with the same symbol, the substituents may be the same as or different from each other. For example the six Rs on the benzene ring may be the same as or different from each other.

[0100] In the present invention, "substituted" means that one or more hydrogen atoms in the substituent are replaced by a substituent.

[0101] In the present invention, the number of carbon atoms in a straight-chain alkyl group may be C1-C20, C1-C16, C1-C10 or C1-C6. The number of carbon atoms in a branched-chain alkyl group may be C3-C20, C3-C16, C3-C10 or C3-C6. The number of carbon atoms in a cycloalkyl group may be C3-C20, C3-C16, C3-C10 or C3-C6. Non-limiting examples of straight-chain alkyl groups include methyl (-CH3), ethyl (-C2H5), n-propyl (-C3H7), n-butyl (-C4H9), n-pentyl (-C5H 11 ), n-hexyl (-C6H 13 ), n-heptyl (-C7H 15 ), n-octyl (-C8H 17 ), n-nonyl (-C9H 19 ), -C 10 H 21 , -C 11 H 23 , -C 12 H 25 , -C 13 H 27 , -C 14 H 29 , -C 15 H 31 , -C 16 H 33Non-limiting examples of branched alkyl groups include: isopropyl, branched alkyl groups having 4 carbon atoms, branched alkyl groups having 5 carbon atoms, branched alkyl groups having 6 carbon atoms, branched alkyl groups having 7 carbon atoms, branched alkyl groups having 8 carbon atoms, branched alkyl groups having 9 carbon atoms, branched alkyl groups having 10 carbon atoms, branched alkyl groups having 11 carbon atoms, branched alkyl groups having 12 carbon atoms, branched alkyl groups having 13 carbon atoms, branched alkyl groups having 14 carbon atoms, branched alkyl groups having 15 carbon atoms, branched alkyl groups having 16 carbon atoms. Non-limiting examples of cycloalkyl groups include: cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloalkyl groups having 7 carbon atoms, cycloalkyl groups having 8 carbon atoms, cycloalkyl groups having 9 carbon atoms, cycloalkyl groups having 10 carbon atoms (such as adamantyl), cycloalkyl groups having 11 carbon atoms, cycloalkyl groups having 12 carbon atoms, cycloalkyl groups having 13 carbon atoms, cycloalkyl groups having 14 carbon atoms, cycloalkyl groups having 15 carbon atoms, cycloalkyl groups having 16 carbon atoms.

[0102] In the present invention, when the connection site is not specified in the group, it means that any optional connection site in the group can be used as the connection site.

[0103] In the present invention, "independently selected from" for one or more groups means that when one or more groups appear simultaneously and at multiple positions in the compound, they are all independently selected and can be the same or different.

[0104] In the present invention, taking C3-C20 as an example, it means containing 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19 or 20 carbon atoms.

[0105] In the present invention, C3-C10 means containing 3, 4, 5, 6, 7, 8, 9 or 10 carbon atoms.

[0106] In the present invention, taking C1-C20 as an example, it means containing 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19 or 20 carbon atoms.

[0107] In the present invention, taking C1-C10 as an example, it means containing 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10 carbon atoms.

[0108] 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.

[0109] 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 the organic solar cell device is habitually 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 on the present invention.

[0110] In the present invention, words such as "further", "even further", "especially", etc. are used for descriptive purposes and indicate differences in content, but should not be construed as limiting the scope of protection of the present invention.

[0111] In the present invention, "optionally", "optional", "option" mean that it can be either present or absent, that is, it refers to any one of the two alternative schemes of "present" or "absent". If "optional" appears multiple times in a technical solution, and there is no special instruction, no contradiction or mutual restriction relationship, then each "optional" is independent of each other.

[0112] In the present invention, for the technical features described in an open-ended manner, it includes a closed technical solution composed of the listed features, as well as an open-ended technical solution containing the listed features.

[0113] For those not specifying specific experimental steps or conditions in the examples, the operations or conditions of the conventional experimental steps described in the literature in this field can be followed. For the reagents or instruments not specifying the manufacturer, they are all conventional reagent products that can be obtained through commercial channels.

[0114] Polymer synthesis examples

[0115] The following examples facilitate a better understanding of the disclosure of the present invention and are not intended to limit it in any way. The experimental methods used in the following examples are all conventional methods unless otherwise specified, and the materials, reagents, etc. used are all prior art and can be obtained from commercial sources unless otherwise specified.

[0116] Synthesis of monomer M1:

[0117]

[0118] Synthesis of compound 1-2:

[0119] Accurately weigh Compound 1-1 (3.7 g, 25.0 mmol), triethylamine (7.6 g, 75.0 mmol), and 50 mL of dichloromethane and add them to a 250 mL three-necked flask in sequence. Replace nitrogen three times, cool down to 0 °C, and add 2-ethylhexyl 2-chloro-2-oxoacetate (6.6 g, 30.0 mmol) dropwise while controlling the temperature. After the reaction is completed, add saturated brine to quench the reaction, extract with ethyl acetate three times, combine the organic phases, dry with anhydrous sodium sulfate, and concentrate under reduced pressure. Finally, about 7.3 g of Compound 1-2 is obtained, with a yield of 88.1%, MS: 331.42.

[0120] Synthesis of Compound 1-3:

[0121] Accurately weigh Compound 1-2 (6.6 g, 20.0 mmol) and 100 mL of xylene and add them to a 250 mL three-necked flask in sequence. Replace nitrogen three times, add Lawesson's reagent (4.8 g, 12.0 mmol), and react at 110 °C. Monitor the reaction by LCMS. After the reaction is completed, cool it to room temperature naturally and directly use it for the next step.

[0122] Synthesis of Compound 1-4:

[0123] Accurately weigh cesium carbonate (13.0 g, 40.0 mmol) and add it to the reaction solution of the previous step. Replace nitrogen three times and react at 160 °C. After the reaction is completed, add saturated brine to quench the reaction, add ethyl acetate and stir for another 10 min. Filter the mixture, extract the filtrate, combine the organic phases, dry with anhydrous sodium sulfate, concentrate under reduced pressure to remove the excess solvent, and perform silica gel column chromatography with the eluent of PE:EA = 6:1 (volume ratio). Finally, about 1.8 g of Compound 1-4 is obtained, with a yield of 27.5% for the two-step consecutive reaction, MS: 327.81.

[0124] Synthesis of Monomer M1:

[0125] Accurately weigh Compound 1-4 (1.7 g, 5.2 mmol) and 20 mL of acetonitrile and add them to a 100 mL three-necked flask in sequence. Stir at room temperature and add NBS (2.8 g, 15.6 mmol) in batches. Heat up to 50 °C and react overnight. After the reaction is completed, add water to quench the reaction, extract with ethyl acetate three times, combine the organic phases, dry with anhydrous sodium sulfate, concentrate under reduced pressure, and perform silica gel column chromatography with the eluent of PE:DCM = 2:1 (volume ratio). Finally, about 2.1 g of Monomer M1 is obtained, with a yield of 83.2%, MS: 485.67.

[0126] Synthesis Example 1 of Polymer: Synthesis of Polymer (P1)

[0127]

[0128] Accurately weigh the monomers 2-1 (410 mg, 1.0 mmol), 2-2 (452 mg, 0.8 mmol), and M1 (97 mg, 0.2 mmol) and add them successively to a 100 mL thick-walled pressure-resistant tube. Add 30 mL of ultra-dry o-xylene. After purging with nitrogen for 10 min, add tris(o-tolyl)phosphine (49 mg, 0.16 mmol) and tris(dibenzylideneacetone)dipalladium(0) (18 mg, 0.02 mmol). Continue purging with nitrogen for 10 min, and then stop heating after reacting at 120 °C for 15 h. Cool the reaction solution to room temperature, dilute it with chloroform and drop it into methanol to precipitate a solid. Filter it by suction. The filter cake is thoroughly washed successively with n-hexane, acetone, and dichloromethane in a Soxhlet extractor. The residue is dissolved in chloroform, chromatographed on a silica gel column with a mesh size of 60-100, concentrated, dropped into methanol to precipitate a solid, filtered by suction. After vacuum drying the filter cake, about 344 mg of polymer (P1) is obtained, with a yield of 72.9%, Mn: 31.4 KDa, and PDI: 2.49.

[0129] Synthesis Example 2 of Polymer: Synthesis of Polymer (P2):

[0130]

[0131] Accurately weigh the monomers 2-1 (410 mg, 1.0 mmol), 2-2 (508 mg, 0.9 mmol), and M1 (49 mg, 0.1 mmol) and add them successively to a 100 mL thick-walled pressure-resistant tube. Add 30 mL of ultra-dry o-xylene. After purging with nitrogen for 10 min, add tris(o-tolyl)phosphine (49 mg, 0.16 mmol) and tris(dibenzylideneacetone)dipalladium(0) (18 mg, 0.02 mmol). Continue purging with nitrogen for 10 min, and then stop heating after reacting at 120 °C for 15 h. Cool the reaction solution to room temperature, dilute it with chloroform and drop it into methanol to precipitate a solid. Filter it by suction. The filter cake is thoroughly washed successively with n-hexane, acetone, and dichloromethane in a Soxhlet extractor. The residue is dissolved in chloroform, chromatographed on a silica gel column with a mesh size of 60-100, concentrated, dropped into methanol to precipitate a solid, filtered by suction. After vacuum drying the filter cake, about 305 mg of polymer (P2) is obtained, with a yield of 63.6%, Mn: 33.2 KDa, and PDI: 2.17. The GPC chromatogram is shown in Figure 2 .

[0132] Synthesis Example 3 of Polymer: Synthesis of Polymer (P3):

[0133]

[0134] Accurately weigh monomer 2-1 (410 mg, 1.0 mmol), 4-1 (463 mg, 0.8 mmol), and M1 (97 mg, 0.2 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 10 min, add tris(o-tolyl)phosphine (49 mg, 0.16 mmol) and tris(dibenzylideneacetone)dipalladium (18 mg, 0.02 mmol). Continue purging with nitrogen for 10 min, and then stop heating after reacting at 120 °C for 15 h. Cool the reaction solution to room temperature, dilute it with chloroform and drop it into methanol to precipitate a solid. Filter it by suction. The filter cake is thoroughly washed successively with n-hexane, acetone, and dichloromethane in a Soxhlet extractor. The residue is dissolved in chloroform, chromatographed on a silica gel column with 60-100 mesh, concentrated and dropped into methanol to precipitate a solid. Filter it by suction. After vacuum drying the filter cake, about 347 mg of polymer (P3) is obtained, with a yield of 71.9%, Mn: 28.5 KDa, and PDI: 2.28.

[0135] Synthesis Example 4 of Polymer: Synthesis of Polymer (P4):

[0136]

[0137] Accurately weigh monomer 2-1 (410 mg, 1.0 mmol), 4-1 (492 mg, 0.85 mmol), and M1 (73 mg, 0.15 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 10 min, add tris(o-tolyl)phosphine (49 mg, 0.16 mmol) and tris(dibenzylideneacetone)dipalladium (18 mg, 0.02 mmol). Continue purging with nitrogen for 10 min, and then stop heating after reacting at 120 °C for 15 h. Cool the reaction solution to room temperature, dilute it with chloroform and drop it into methanol to precipitate a solid. Filter it by suction. The filter cake is thoroughly washed successively with n-hexane, acetone, and dichloromethane in a Soxhlet extractor. The residue is dissolved in chloroform, chromatographed on a silica gel column with 60-100 mesh, concentrated and dropped into methanol to precipitate a solid. Filter it by suction. After vacuum drying the filter cake, about 371 mg of polymer (P4) is obtained, with a yield of 76.1%, Mn: 34.8 KDa, and PDI: 2.06.

[0138] Synthesis Example 5 of Polymer: Synthesis of Polymer (P5):

[0139]

[0140] Accurately weigh monomer 2-1 (410 mg, 1.0 mmol), 2-2 (508 mg, 0.9 mmol), and 6-1 (33 mg, 0.1 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 10 min, add tris(o-tolyl)phosphine (49 mg, 0.16 mmol) and tris(dibenzylideneacetone)dipalladium(0) (18 mg, 0.02 mmol). Continue purging with nitrogen for 10 min, and then stop heating after reacting at 120 °C for 15 h. Cool the reaction solution to room temperature, dilute it with chloroform and drop it into methanol to precipitate a solid. Filter it by suction. The filter cake is thoroughly washed successively with n-hexane, acetone, and dichloromethane in a Soxhlet extractor. The residue is dissolved in chloroform, chromatographed on a silica gel column with 60 - 100 mesh, concentrated and dropped into methanol to precipitate a solid. Filter it by suction. After vacuum drying the filter cake, about 319 mg of polymer (P5) is obtained, with a yield of 68.8%, Mn: 30.6 KDa, and PDI: 2.73.

[0141] Synthesis Example 6 of Polymer: Synthesis of Polymer (P6):

[0142]

[0143] Accurately weigh monomer 2-1 (410 mg, 1.0 mmol), 4-1 (463 mg, 0.8 mmol), and 6-1 (66 mg, 0.2 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 10 min, add tris(o-tolyl)phosphine (49 mg, 0.16 mmol) and tris(dibenzylideneacetone)dipalladium(0) (18 mg, 0.02 mmol). Continue purging with nitrogen for 10 min, and then stop heating after reacting at 120 °C for 15 h. Cool the reaction solution to room temperature, dilute it with chloroform and drop it into methanol to precipitate a solid. Filter it by suction. The filter cake is thoroughly washed successively with n-hexane, acetone, and dichloromethane in a Soxhlet extractor. The residue is dissolved in chloroform, chromatographed on a silica gel column with 60 - 100 mesh, concentrated and dropped into methanol to precipitate a solid. Filter it by suction. After vacuum drying the filter cake, about 295 mg of polymer (P6) is obtained, with a yield of 65.3%, Mn: 26.1 KDa, and PDI: 2.58.

[0144] Preparation and Characterization of Organic Photovoltaic Devices (OPV)

[0145] This example is given according to the preparation implementation method and characterization of the organic photovoltaic device (OPV) provided by the present invention, but the present invention is not limited to the following examples.

[0146] Device Example 1

[0147] Reference Figure 1, Device Embodiment 1 includes a substrate, an anode, an anode buffer layer, a photoactive layer, a cathode buffer layer, and a cathode layer stacked in sequence; among them, the materials of the anode, anode buffer layer, photoactive layer, cathode buffer layer, and cathode layer are: indium tin oxide ITO / 2PACz / photoactive layer material / PDINN / Ag

[0148] Its preparation method includes the following steps:

[0149] 1) Cleaning of ITO substrate

[0150] Clean the ITO conductive glass with detergent, rinse it thoroughly, then ultrasonically clean it with deionized water, acetone, and isopropanol for 15 minutes, and then dry it with nitrogen and treat it in a plasma cleaner for 5 minutes to further clean the surface and improve wettability.

[0151] 2) Preparation of anode buffer layer

[0152] Subsequently, spin-coat the anode buffer layer material 2PACz (0.2 mg / mL, methanol solution) on the ITO substrate at a speed of 3000 rpm for 30 seconds, and then anneal it at 100 °C for 10 minutes to obtain the anode buffer layer.

[0153] 3) Preparation of photoactive layer

[0154] In a glove box (inert gas atmosphere), spin-coat the photoactive layer material solvent 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.

[0155] The preparation method of the active layer material solvent is: dissolve the donor material and the acceptor material in chloroform, with a total concentration of 18 mg / mL, and add 0.5% by volume of chloronaphthalene as an additive. Among them, the donor material in the photoactive layer material is selected from polymer (P1), the acceptor material is selected from compound (A - 9), and the mass ratio of polymer (P1):compound (A - 9) is 1:1.2.

[0156] 4) Preparation of cathode buffer layer

[0157] Spin-coat the cathode buffer layer material PDINN (dissolve PDINN in methanol to prepare a solution with a concentration of 1.0 mg / mL) uniformly on the photoactive layer at a speed of 3000 rpm for 30 seconds to obtain the cathode buffer layer.

[0158] 5) Preparation of cathode layer

[0159] In 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.

[0160] 6) Encapsulation

[0161] The device is encapsulated with a UV-curable resin in a nitrogen glove box.

[0162] Device Examples 2-6:

[0163] The preparation method of Device Examples 2-6 refers to the preparation method of Device Example 1, and the difference lies in: 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), polymer (P3), polymer (P4), polymer (P5), and polymer (P6) respectively. Specifically as shown in Table 1.

[0164] Device Comparative Examples 1-2

[0165] The preparation method of Device Comparative Examples 1-2 refers to the preparation method of Device Example 1, and the difference lies in: 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 PTQ10 and PTQ11 respectively. Specifically as shown in Table 1.

[0166]

[0167] The prepared organic photovoltaic devices are subjected to performance tests. Under standard light irradiation of a solar simulator (AM 1.5G), the current-voltage curves of the cells are tested, and the photoelectric conversion efficiency is calculated; as shown in Table 1.

[0168] Table 1

[0169]

[0170]

[0171] From the data in Table 1, it can be seen that the polymer according to the present invention used as a donor material in an organic photovoltaic cell achieves better photoelectric conversion efficiency compared to Device Comparative Examples 1-2. The reason is that: the present invention provides a polymer containing D-A copolymerization, wherein the electron-withdrawing A unit is selected from the first repeating unit and the second repeating unit, and the electron-donating D unit is selected from the third repeating unit. By regulating the ratio of the two electron-withdrawing units, on the one hand, the energy level of the polymer is finely adjusted, and on the other hand, the molecular backbone structure can be regulated accordingly, so as to optimize the molecular packing of the active layer and achieve the improvement of the photoelectric performance of the device.

[0172] Obviously, the above embodiments are merely examples for clear illustration and not limitations on the implementation manners. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to enumerate all implementation manners here. And the obvious changes or modifications derived therefrom still fall within the protection scope of the present invention.

Claims

1. A polymer, characterized in that, The polymer comprises a first repeating unit, a second repeating unit, and a third repeating unit; the first repeating unit has the structure shown in formula (A), the second repeating unit has the structure shown in formula (B), and the third repeating unit has the structure shown in formula (C): Wherein: R1 is selected from -H, a straight-chain alkyl group having 1 to 10 carbon atoms, or a branched-chain alkyl group having 3 to 10 carbon atoms; R2 is selected from branched-chain alkyl groups having 3 to 20 carbon atoms; Z is selected from N or -COOR7; R7 is 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 and R4 are independently selected from -H, -D, -F, or -Cl; R5 and R6 are independently selected from -H, -D, -F, -Cl, a straight-chain alkyl group having 1 to 20 carbon atoms, or a branched-chain alkyl group having 3 to 20 carbon atoms; * is the linking site in the polymer.

2. The polymer according to claim 1, wherein The polymer structure has the structure shown in formula (1): Wherein: a, b, and c are mole percentages, 0 < a < 1, 0 < b < 1, 0 < c < 1, and a + b + c = 1.

3. The polymer according to claim 2, wherein a + b ≤ c.

4. The polymer according to claim 1, wherein The polymer has the structure shown in formula (2): Wherein: x and y are mole percentages, x is a real number where 0 < x < 1, y is a real number where 0 < y < 1, and x + y = 1; n is selected from integers greater than or equal to 2.

5. The polymer according to claim 4, wherein x is a real number where 0.5 ≤ x < 1; preferably, x is a real number where 0.8 ≤ x < 1.

6. The polymer according to claim 2 or 4, characterized in that, The R2 is selected from branched-chain alkyl groups having 10 to 20 carbon atoms; Preferably, the R2 is selected from 7. The polymer according to claim 2 or 4, characterized in that, The R1 is selected from -H or methyl.

8. The polymer according to claim 2 or 4, characterized in that, The R7 is selected from a straight-chain alkyl group having 1 to 10 carbon atoms or a branched-chain alkyl group having 3 to 10 carbon atoms; Preferably, the R7 is selected from methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl or 9. The polymer according to claim 4, wherein The structure of the polymer is selected from the following structural formulas:

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

11. The organic photovoltaic device according to claim 10, characterized in that, The photoactive layer further comprises an organic compound shown in formula (4): Wherein: R8 and R9 are 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; R 10 、R 11 selected from a straight-chain alkyl group having 1 to 20 carbon atoms, a branched-chain alkyl group having 3 to 20 carbon atoms, a phenyl group which is unsubstituted or substituted by R, a pyridyl group which is unsubstituted or substituted by R, and a thiophenyl group which is unsubstituted or substituted by R; The R is selected from -D, a straight-chain alkyl group having 1 to 20 carbon atoms, a branched-chain alkyl group having 3 to 20 carbon atoms, a straight-chain alkoxy group having 1 to 20 carbon atoms, or a branched-chain alkoxy group having 3 to 20 carbon atoms; R 12 Each occurrence is independently selected from -H, -D, methyl, methoxy, -F, -Cl, -Br, -I, -CN or -CF3.

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