Preparation method and application of conjugated polymer donor material based on imidazo[1,2-a]pyrazine unit

Abstract

The application discloses a preparation method and application of a conjugated polymer donor material based on an imidazo[1,2-a]pyrazine unit, which is a polymer donor based on a benzodithiophene unit and an imidazo[1,2-a]pyrazine unit or a polymer donor based on a bithiophene unit and an imidazo[1,2-a]pyrazine unit; the polymer donor based on the benzodithiophene unit and the imidazo[1,2-a]pyrazine unit has a general structure as shown in BDT-IPZ; the polymer donor based on the bithiophene unit and the imidazo[1,2-a]pyrazine unit has a general structure as shown in BP-IPZ; the donor material has good crystallinity and thermal stability and has good compatibility with an acceptor material.

Description

Technical Field

[0001] The present invention belongs to the technical field of organic solar cell materials, and particularly relates to a preparation method and application of a conjugated polymer donor material based on imidazo[1,2-a]pyrazine units. Background Art

[0002] In recent years, photovoltaic power generation has become an effective solution to address energy shortages. Organic solar cells, due to their lightweight, easy-to-scale fabrication, and ability to be made into semi-transparent devices, have become a highly sought-after photovoltaic technology. Continuous breakthroughs in organic solar cells have garnered widespread attention from researchers, with the highest certified photovoltaic conversion efficiency currently exceeding 20%.

[0003] The active layer of high-efficiency organic photovoltaic devices is composed of donor materials and acceptor materials. However, there are still problems such as the crystallinity of the donor material itself and its miscibility with the acceptor material. Designing and synthesizing new donor materials to meet the requirements of solution processing of photovoltaic devices, and at the same time regulating the crystallinity of polymer donor materials to form an ideal morphology of the active layer, are the key to improving the photoelectric conversion efficiency of solar cells and are of great significance to promoting the progress of organic photovoltaics. Summary of the Invention

[0004] The purpose of the present invention is to provide a preparation method and application of a conjugated polymer donor material based on imidazo[1,2-a]pyrazine units, wherein the donor material has good crystallinity and thermal stability and good compatibility with an acceptor material.

[0005] The present invention adopts the following technical solution: a conjugated polymer donor material based on imidazo[1,2-a]pyrazine units, which is a polymer donor based on benzodithiophene units and imidazo[1,2-a]pyrazine units or a polymer donor based on bithiophene units and imidazo[1,2-a]pyrazine units;

[0006] The polymer donor based on benzodithiophene units and imidazo[1,2-a]pyrazine units has a general structure as shown in BDT-IPZ:

[0007]

[0008] The polymer donor based on bithiophene units and imidazo[1,2-a]pyrazine units has a general structure as shown in BP-IPZ:

[0009]

[0010] Furthermore, R1, R2, R3, R4, R5, and R6 are independently selected from any one of an alkyl group, an alkoxy group, and an alkylthio group; X and Y are independently selected from any one of a hydrogen atom, a fluorine atom, and a chlorine atom; and n is selected from any natural number from 2 to 2000.

[0011] Furthermore, the alkyl group, alkoxy group and alkylthio group are C4-C30 straight-chain alkyl group, C4-C30 alkoxy group and C4-C30 alkylthio group, respectively.

[0012] Furthermore, R1 and R2 are independently selected from any one of the following structures:

[0013]

[0014] Furthermore, R3, R4, R5, and R6 are independently selected from any one of the following structures:

[0015]

[0016] The present invention also provides a method for preparing the above-mentioned conjugated polymer donor material based on imidazo[1,2-a]pyrazine units, which is characterized by comprising the following steps:

[0017] Step 1, synthesis of compound of formula 3:

[0018]

[0019] Step 2, synthesis of the compound of formula 4: mixing the compound of formula 3 in step 1 with N-bromosuccinimide, N-bromosuccinimide is abbreviated as NBS:

[0020]

[0021] Step 3, synthesis of polymer donor BDT-IPZ: mixing the polymer monomer of formula 4 and the polymer monomer of formula 5 for reaction;

[0022]

[0023] Furthermore, in the step 1, the molar ratio of the compound of formula 1 to the compound of formula 2 is 1:2.4;

[0024] The solvent for the reaction of the compound of formula 1 with the compound of formula 2 is anhydrous toluene or tetrahydrofuran;

[0025] The catalyst for the reaction of the compound of Formula 1 with the compound of Formula 2 is tetrakistriphenylphosphine palladium, [1,3-bis(diphenylphosphino)propane]dichloronickel, [1,2-bis(diphenylphosphino)ethane]chloronickel, bis(dibenzylideneacetone)palladium, palladium chloride or palladium acetate;

[0026] In the step 2, the molar ratio of the compound of formula 3 to N-bromosuccinimide is 1:2.17, where N-bromosuccinimide is abbreviated as NBS;

[0027] The solvent for the reaction of the compound of formula 3 with N-bromosuccinimide is chloroform or tetrahydrofuran.

[0028] The present invention also provides a method for preparing the above-mentioned conjugated polymer donor material based on imidazo[1,2-a]pyrazine units, as follows:

[0029] The polymeric monomers of formula 4 and 6 are mixed and reacted to obtain the polymer donor BP-IPZ:

[0030]

[0031] The present invention also discloses an organic solar cell, wherein the active layer thereof comprises a donor material and an acceptor material, wherein the donor material is the above-mentioned conjugated polymer donor material based on imidazo[1,2-a]pyrazine units.

[0032] The present invention also discloses a photocatalyst based on the above-mentioned conjugated polymer donor material based on imidazo[1,2-a]pyrazine units, characterized in that it is used in photocatalytic degradation of pollutants, photocatalytic hydrogen production and photocatalytic sterilization.

[0033] The beneficial effects of the present invention are as follows: 1. The provided polymer donor material based on imidazo[1,2-a]pyrazine units has good crystallinity and good solubility in solvents used in the processing of organic solar cell devices, such as chloroform and chlorobenzene, so a solution processing method can be used when preparing the device. 2. The provided polymer donor material based on imidazo[1,2-a]pyrazine units exhibits a strong and wide absorption range in a thin film state, which complements the absorption of the acceptor material Y6; the donor and acceptor blend layer can form a nano-interpenetrating network structure of appropriate size, thereby improving the carrier dissociation efficiency and the morphology of the active layer of the polymer solar cell, thereby improving the photoelectric conversion efficiency. 3. When the polymer donor material based on imidazo[1,2-a]pyrazine units is used as an organic semiconductor photocatalyst, it has the advantages of stable performance, green environmental protection, and rapid and efficient degradation in the fields of photocatalytic degradation of pollutants, photocatalytic sterilization, and photocatalytic hydrogen evolution. It can also be reused multiple times and can still maintain good photocatalytic efficiency after recycling. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 The conjugated polymer based on imidazo[1,2-a]pyrazine units of the present invention is prepared in Example 1 of compound 1-3. 1 H NMR spectrum;

[0035] Figure 2 The conjugated polymer based on imidazo[1,2-a]pyrazine units of the present invention is prepared in Example 1 of compound 1-3. 13 C NMR spectrum;

[0036] Figure 3 The polymer monomer M1 prepared in Example 1 of the conjugated polymer based on imidazo[1,2-a]pyrazine units of the present invention is 1 H NMR spectrum;

[0037] Figure 4 The polymer monomer M1 prepared in Example 1 of the conjugated polymer based on imidazo[1,2-a]pyrazine units of the present invention is 13 C NMR spectrum;

[0038] Figure 5 is a thermogravimetric analysis curve of the conjugated polymer based on imidazo[1,2-a]pyrazine units prepared in Example 1;

[0039] Figure 6 is a thermogravimetric analysis curve of the conjugated polymer based on imidazo[1,2-a]pyrazine units prepared in Example 2;

[0040] Figure 7 is the UV-visible absorption spectrum of the conjugated polymer based on imidazo[1,2-a]pyrazine units prepared in Example 1;

[0041] Figure 8 is the UV-visible absorption spectrum of the conjugated polymer based on imidazo[1,2-a]pyrazine units prepared in Example 2;

[0042] Figure 9 is the cyclic voltammetry curve of the conjugated polymer based on imidazo[1,2-a]pyrazine units prepared in Example 1;

[0043] Figure 10 is the cyclic voltammetry curve of the conjugated polymer based on imidazo[1,2-a]pyrazine units prepared in Example 2;

[0044] Figure 11 The JV curve of the conjugated polymer based on imidazo[1,2-a]pyrazine units prepared in Example 1 applied to organic solar cells;

[0045] Figure 12 The JV curve of the conjugated polymer based on imidazo[1,2-a]pyrazine units prepared in Example 2 applied to organic solar cells;

[0046] Figure 13EQE curve of the conjugated polymer based on imidazo[1,2-a]pyrazine units prepared in Example 1 applied to organic solar cells;

[0047] Figure 14 EQE curve of the conjugated polymer based on imidazo[1,2-a]pyrazine units prepared in Example 2 applied to organic solar cells;

[0048] Figure 15 This is a graph showing the degradation efficiency of the conjugated polymer based on imidazo[1,2-a]pyrazine units prepared in Example 1 when applied to photocatalytic degradation of pollutants;

[0049] Figure 16 This is a degradation efficiency curve of the conjugated polymer based on imidazo[1,2-a]pyrazine units prepared in Example 2 when applied to photocatalytic degradation of pollutants. DETAILED DESCRIPTION

[0050] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0051] The present invention describes methods for preparing and applying conjugated polymer donor materials based on imidazo[1,2-a]pyrazine units. Pyrazine is a highly electronegative heterocyclic aromatic hydrocarbon core with a highly planar and symmetrical geometry. These properties enhance intermolecular interactions and synergistically regulate the energy levels, absorption spectra, and preaggregation behavior of polymers. Pyrazine, after various chemical modifications, can be used as a unit for DA copolymerization to design polymer donor materials, showing great potential in the construction of high-performance organic solar cells.

[0052] The present invention discloses a conjugated polymer donor material based on imidazo[1,2-a]pyrazine units, which is a polymer donor based on benzodithiophene units and imidazo[1,2-a]pyrazine units or a polymer donor based on bithiophene units and imidazo[1,2-a]pyrazine units.

[0053] The general structure of the polymer donor based on benzodithiophene units and imidazo[1,2-a]pyrazine units is shown as BDT-IPZ:

[0054]

[0055] Wherein, R1, R2, R3, R4, R5, and R6 are independently selected from any one of alkyl, alkoxy, and alkylthio groups; X and Y are independently selected from any one of hydrogen, fluorine, and chlorine atoms; and n is selected from any natural number from 2 to 2000.

[0056] The above-mentioned alkyl group, alkoxy group and alkylthio group are respectively a C4-C30 straight-chain alkyl group, a C4-C30 alkoxy group and a C4-C30 alkylthio group.

[0057] Preferably, R1 and R2 are independently selected from any one of the following structures:

[0058]

[0059] Preferably, R3, R4, R5, and R6 are independently selected from any one of the following structures:

[0060]

[0061] Said X is selected from a hydrogen atom, a fluorine atom or a chlorine atom;

[0062] Said Y is selected from hydrogen atom, fluorine atom or chlorine atom;

[0063] The general structure of the polymer donor based on bithiophene units and imidazo[1,2-a]pyrazine units is shown in BP-IPZ:

[0064]

[0065] Wherein, R3, R4, R5, and R6 are independently selected from any one of alkyl, alkoxy, and alkylthio groups; X and Y are independently selected from any one of hydrogen, fluorine, and chlorine atoms; and n is selected from any natural number from 2 to 2000.

[0066] The R3, R4, R5, and R6 are the same or different and are independently selected from any one of a C4-C30 straight-chain alkyl group, a C4-C30 branched-chain alkyl group, a C4-C30 alkoxy group, and a C4-C30 alkylthio group.

[0067] Preferably, R3, R4, R5, and R6 are selected from any one of the following structures:

[0068]

[0069] The polymer donor containing bithiophene units and imidazo[1,2-a]pyrazine units is selected from one of the following structures:

[0070]

[0071]

[0072] The preparation method of the polymer donor based on benzodithiophene units and imidazo[1,2-a]pyrazine units comprises the following steps:

[0073] Step 1: Synthesis of the compound of formula 3: Mix the compound of formula 1 with the compound of formula 2.

[0074]

[0075] The definitions of R3, R4, R5 and R6 are the same as those of polymer BDT-IPZ.

[0076] Step 2, synthesis of the compound of formula 4: the compound of formula 3 in step 1 is mixed with N-bromosuccinimide for reaction; the compound of formula 4 is a polymerization monomer;

[0077]

[0078] Wherein, the definitions of R3, R4, R5, and R6 are the same as those of the polymer donor BDT-IPZ.

[0079] Step 3, synthesis of polymer donor BDT-IPZ: The polymer monomer of formula 4 and the polymer monomer of formula 5 are mixed and reacted to obtain the polymer donor BDT-IPZ:

[0080]

[0081] Wherein, the definitions of R3, R4, R5, R6, X, and Y are the same as those of the polymer BDT-IPZ.

[0082] In the present invention, the unmarked reaction conditions of each step in the synthesis route of the above-mentioned compound or polymer are conventional in the art.

[0083] In the present invention, in step 1, the molar ratio of the compound of formula 1 to the compound of formula 2 is 1:(2-5), optionally 1:2, 1:2.4, 1:4 or 1:5, preferably 1:2.4.

[0084] In step 1, the solvent for the reaction of the compound of formula 1 with the compound of formula 2 is anhydrous toluene or tetrahydrofuran, preferably anhydrous toluene.

[0085] In step 1, the catalyst for the reaction of the compound of Formula 1 with the compound of Formula 2 is tetrakistriphenylphosphine palladium, [1,3-bis(diphenylphosphino)propane]dichloronickel, [1,2-bis(diphenylphosphino)ethane]chloronickel, bis(dibenzylideneacetone)palladium, palladium chloride or palladium acetate, preferably tetrakistriphenylphosphine palladium.

[0086] In step 1, the temperature for reacting the compound of formula 1 with the compound of formula 2 is 90-120°C, for example, 90°C, 100°C, 120°C, preferably 110°C.

[0087] In step 1, the reaction time of the compound of formula 1 and the compound of formula 2 is 5-24 hours, for example, 5 hours, 6 hours, 9 hours, 12 hours, 15 hours or 18 hours, preferably 12 hours.

[0088] In step 1, the post-treatment method of the compound of formula 3 is column chromatography purification, and the mobile phase used is petroleum ether: dichloromethane = (1-5): 1, and the preferred ratio is petroleum ether: dichloromethane = 2:1.

[0089] In step 2, the molar ratio of the compound of formula 3 to N-bromosuccinimide is 1:(2-5), such as 1:2, 1:2.17, 1:4 or 1:5, preferably 1:2.17. N-bromosuccinimide is abbreviated as NBS.

[0090] In the present invention, in step 2, the compound of formula 3 and N-bromosuccinimide are reacted in a solvent of chloroform or tetrahydrofuran, where N-bromosuccinimide is abbreviated as NBS; preferably tetrahydrofuran.

[0091] In the present invention, in step 2, the temperature for the reaction of the compound of formula 3 with N-bromosuccinimide is 0-50°C, such as 0°C, 20°C, 40°C, etc., preferably room temperature 25°C.

[0092] In the present invention, in step 2, the reaction time of the compound of formula 3 and N-bromosuccinimide is 2-10 hours, such as 2 hours, 4 hours, 6 hours or 8 hours, preferably 6 hours.

[0093] In the present invention, in step 2, the post-treatment method of the compound of formula 4 is column chromatography purification, and the mobile phase used is petroleum ether: dichloromethane = (1-5): 1, and the preferred ratio is petroleum ether: dichloromethane = 4:1.

[0094] In the present invention, in step 3, the solvent for reacting the polymerizable monomer of formula 4 with the polymerizable monomer of formula 5 is anhydrous toluene or tetrahydrofuran, preferably anhydrous toluene.

[0095] In the present invention, in step 3, the catalyst for the reaction of the polymerizable monomer of formula 4 and the polymerizable monomer of formula 5 is tetrakistriphenylphosphine palladium, [1,3-bis(diphenylphosphino)propane]dichloronickel, [1,2-bis(diphenylphosphino)ethane]chloronickel, bis(dibenzylideneacetone)palladium, palladium chloride or palladium acetate, preferably tetrakistriphenylphosphine palladium.

[0096] In the present invention, in step 3, the temperature for reacting the polymerizable monomer of formula 4 and the polymerizable monomer of formula 5 is 80-150°C, for example, 80°C, 115°C, 120°C or 140°C, preferably 115°C.

[0097] In the present invention, in step 3, the reaction time of the polymerizable monomer of formula 4 and the polymerizable monomer of formula 5 is 12-24 hours, for example, 12 hours, 15 hours, 22 hours, 24 hours, etc., preferably 22 hours.

[0098] In the present invention, in step 3, the post-treatment method after the polymerization reaction is completed is Soxhlet extraction, and the polymerization product is subjected to Soxhlet extraction using methanol, n-hexane and chloroform in sequence. The chloroform extract is subjected to rotary evaporation to remove most of the solvent, and the extract is added dropwise to methanol for filtration. The obtained polymerization product is vacuum dried for use.

[0099] The present invention also provides a method for preparing the above-mentioned conjugated polymer donor material based on imidazo[1,2-a]pyrazine units, as follows:

[0100] The polymeric monomers of formula 4 and 6 are mixed and reacted to obtain the polymer donor BP-IPZ:

[0101]

[0102] The present invention also provides a use of the polymer donor or the polymer donor prepared by the preparation method in an organic solar cell.

[0103] Preferably, an organic solar cell is provided, wherein the active layer thereof comprises a donor material and an acceptor material, wherein the donor material is the above-mentioned polymer donor or a polymer donor based on benzodithiophene units and imidazo[1,2-a]pyrazine units prepared by the above-mentioned preparation method, and the acceptor material is a non-fullerene acceptor material Y6.

[0104] The mass ratio of the donor material to the acceptor material is 1:(1.0-1.2).

[0105] The application of the above-mentioned conjugated polymer donor material based on imidazo[1,2-a]pyrazine units in the preparation of the following devices: photovoltaic devices, photoelectric devices, thin-film semiconductor devices and electrochemical devices; the device is specifically an organic solar cell device, and the solar cell device is further a polymer solar cell device comprising a bulk heterojunction structure.

[0106] When the conjugated polymer donor material based on imidazo[1,2-a]pyrazine units is used in a photovoltaic device, the photovoltaic device includes a hole transport layer, an electron transport layer, and a photovoltaic active layer between the hole transport layer and the electron transport layer, wherein the photovoltaic active layer contains the conjugated polymer.

[0107] Applications of the conjugated polymer donor material based on imidazo[1,2-a]pyrazine units in the field of photocatalysis include, but are not limited to, photocatalytic degradation of pollutants, industrial wastewater purification, photocatalytic sterilization, and photocatalytic hydrogen production. The polymer can be used as an organic semiconductor catalyst for photocatalysis and is applicable in the aforementioned fields.

[0108] Example 1

[0109] This embodiment provides a conjugated polymer donor material BDT-IPZ-1 based on imidazo[1,2-a]pyrazine units. The synthesis route is as follows:

[0110]

[0111] The preparation method comprises the following steps:

[0112] 1. Synthesis of compounds of formula 1-3:

[0113] 5 mmol of the compound 6,8-dibromoimidazo[1,2-a]pyrazine of formula 1 and 12 mmol of the compound tributyl(4-(2-butyloctyl)thiophen-2-yl)stannane of formula 1-2 and 0.25 mmol of the catalyst tetrakistriphenylphosphine palladium were added to a dry two-necked round-bottom flask. After evacuation and replacement with nitrogen, 25 ml of anhydrous toluene was added and the mixture was heated in an oil bath at 110°C and stirred at 400 rpm for 12 hours. After the reaction, the mixture solution was cooled to room temperature and extracted with water (70 mL) and dichloromethane (70 mL×3). The organic phase was removed, dried over anhydrous sodium sulfate and filtered. After vacuum concentration, the crude product was purified by column chromatography to obtain a light yellow solid, which is the compound of formula 1-3 with a yield of 72%. The solid was tested, as shown in FIG. Figure 1 As shown, it is the measured 1H NMR spectrum of the compound of formula 1-3, HNMR (600MHz, CDCl3) δ=8.50–8.42(m,1H),8.18–8.09(m,1H),7.74–7.66(m,1H),7.69(d,J=14.5,1H),7.56(d,J=14.1,1H),7.07(d,J=16.3,1H),6.86–6.78(m,1H),2.62–2.37(m,4H),1.61–1.51(m,2H),1.28–1.12(m,32H),0.82–0.74(m,12H); Figure 2 The figure shows the 13C NMR spectrum of the compound of formula 1-3. It can be seen that the prepared compound is the compound of formula 1-3.

[0114] 2. Synthesis of polymerizable monomer of formula M1:

[0115] 3 mmol of the compound of formula 1-3 was added to a dry two-necked round-bottom flask. After vacuuming and replacing the atmosphere with nitrogen, 50 ml of ultra-dry tetrahydrofuran was added to the two-necked flask. 6.5 mmol of N-bromosuccinimide (NBS) was slowly added in batches and reacted at room temperature for 6 h. After the reaction, 100 ml of methanol was added dropwise to the mixture. The solid obtained by filtration was dried and then purified by column chromatography to obtain a yellow solid with a yield of 88%. The yellow solid was tested, as shown in FIG. Figure 3 As shown, it is the 1HNMR spectrum of the measured polymer monomer of formula M1,1 H NMR (600MHz, CDCl3) δ = 8.24 (s, 1H), 7.64 (s, 1H), 7.55 (s, 1H), 5.23 (s, 2H), 2.49 ( dd,J=17.9,7.2,4H),1.74–1.58(m,2H),1.43–0.98(m,32H),0.94–0.62(m,12H); Figure 4 The measured polymer monomer of formula M1 13 C NMR spectrum, it can be seen that the yellow solid is the polymerized monomer of formula M1 in this example.

[0116] 3. Synthesis of polymer BDT-IPZ-1:

[0117] 1 mmol of monomer (Formula M1) and 1 mmol of monomer (Formula M2) were added to a 50 mL two-necked round-bottom flask, followed by 20 mL of anhydrous toluene. After purging the reaction flask with nitrogen for 20 minutes, 50 mg of tetrakistriphenylphosphine palladium catalyst was added. The reaction mixture was then purged with nitrogen for another 30 minutes and heated under reflux in an oil bath at 115°C for 22 hours. After the polymerization, the reaction mixture was cooled to room temperature, concentrated under vacuum, and then added dropwise to 100 mL of methanol. The solid was collected by filtration and Soxhlet extraction with methanol, n-hexane, and chloroform. The chloroform extract was concentrated under vacuum and added dropwise to HPLC methanol to precipitate the solid polymer BDT-IPZ-1. The solid was vacuum-dried and sealed for later use. Gel permeation chromatography determined the number average molecular weight (Mn) of the polymer BDT-IPZ-1 to be 16.2K and the dispersion index (PDI) to be 1.83.

[0118] Example 2

[0119] This embodiment provides a conjugated polymer donor material BDT-IPZ-2 based on imidazo[1,2-a]pyrazine units. The synthesis route is as follows:

[0120]

[0121] 1. Prepare the polymer monomer of formula M1 by the same method as in Example 1;

[0122] 2. Synthesis of polymer BDT-IPZ-2:

[0123] 1 mmol of monomer (Formula M1) and 1 mmol of monomer (Formula M3) were added to a 50 mL two-necked round-bottom flask, followed by 20 mL of anhydrous toluene. After purging the reaction flask with nitrogen for 20 minutes, 50 mg of tetrakistriphenylphosphine palladium catalyst was added. The reaction mixture was then purged with nitrogen for another 30 minutes and heated under reflux in an oil bath at 115°C for 22 hours. After the polymerization, the reaction mixture was cooled to room temperature, concentrated under vacuum, and then added dropwise to 100 mL of methanol. The solid was collected by filtration and Soxhlet extraction with methanol, n-hexane, and chloroform. The chloroform extract was concentrated under vacuum and added dropwise to HPLC methanol to precipitate the solid polymer BDT-IPZ-2. The solid was vacuum-dried and sealed for later use. Gel permeation chromatography determined the number average molecular weight (Mn) of the polymer BDT-IPZ-2 to be 18.6K and the dispersion index (PDI) to be 2.07.

[0124] 3. Thermal stability test:

[0125] Thermogravimetric analysis (TGA) curves of the polymer donor materials prepared in Examples 1 and 2 were measured under a nitrogen atmosphere using a synchronous thermal analyzer. 13.84 mg of each polymer from Example 1 and Example 2 was placed in an 80 μL alumina crucible. The TGA curves were measured over a temperature range of 25°C to 400°C at a heating rate of 10°C / min.

[0126] like Figure 5 The thermogravimetric analysis curve of the polymer BDT-IPZ-1 is shown in FIG. Figure 5 It can be seen that the decomposition temperature of the polymer donor material BDT-IPZ-1 is 335° C. when the weight loss is 5%, indicating that the polymer donor material has good thermal stability.

[0127] like Figure 6 The thermogravimetric analysis curve of the polymer BDT-IPZ-2 is shown in FIG. Figure 6 The decomposition temperature of polymer BDT-IPZ-2 at 5% weight loss is 344°C, indicating that polymer BDT-IPZ-2 is more thermally stable than polymer BDT-IPZ-1. Both polymers have good thermal stability, meeting the stability requirements of common optoelectronic device processing.

[0128] 4. Optical performance test:

[0129] The UV-visible absorption spectra of the polymer donor materials prepared in Example 1 and Example 2 in the thin film state were measured using a UV-visible spectrophotometer, and the empirical formula (Eg = 1240 / λ 吸收边际) calculated the optical band gaps of the two polymer donor materials. 3 mg of each polymer donor material, BDT-IPZ-1 and BDT-IPZ-2, was dissolved in 1 ml of chloroform. Heat and stir to prepare a 3 mg / ml solution. A portion of this solution was spin-coated onto a pre-cleaned quartz wafer to form a uniform thin film.

[0130] Figure 7 The UV-visible absorption spectrum of polymer BDT-IPZ-1 was measured. Figure 7 It shows that the maximum absorption peak of the polymer BDT-IPZ-1 film is located at 543nm, the absorption edge is 642nm, and the calculated optical band gap is 1.90eV. Therefore, the absorption range of the polymer BDT-IPZ-1 is wide and the absorption capacity is strong.

[0131] Figure 8 The measured UV-visible absorption spectrum of polymer BDT-IPZ-2 is shown in Table 1. The optical performance parameters of the polymer donor materials BDT-IPZ-1 and BDT-IPZ-2 prepared in Examples 1 and 2 are shown in Table 1. As can be seen, the maximum absorption peak of the BDT-IPZ-2 film is located at 556 nm, the absorption edge is at 650 nm, and the calculated optical band gap is 1.94 eV. This indicates that these two polymers have strong absorption capacity and high crystallinity.

[0132] Table 1 Test results

[0133] Donor material Maximum absorption (nm) Absorption onset (nm) <![CDATA[E g opt (eV)]]> BDT-IPZ-1 543 642 1.90 BDT-IPZ-2 556 650 1.94

[0134] 4. Electrical performance test:

[0135] The cyclic voltammetry curves of the polymer donor materials prepared in Example 1 and Example 2 were measured using a Zahner IM6e electrochemical workstation. A chloroform solution of BDT-IPZ-1 and BDT-IPZ-2 (concentration of 5 mg / ml) was evenly applied on a platinum electrode. After the solvent evaporated naturally and the film formed, the platinum electrode was immersed in the electrolyte. A platinum plate was used as the working electrode, a platinum wire was used as the counter electrode, and Ag / Ag was used. + Cyclic voltammetry (CV) measurements were performed in a conventional three-electrode cell using a reference electrode and a 0.1 M acetonitrile solution of tetrabutylammonium hexafluorophosphate (Bu4NPF6). The initial oxidation potential and initial reduction potential were obtained according to the formula (EHOMO / LUMO = -e(E ox / red The HOMO and LUMO energy levels of the thin film state were calculated using the onset + 4.71) (eV).

[0136] Figure 9 The cyclic voltammetry curve of polymer BDT-IPZ-1 was measured. Figure 10The cyclic voltammetry curve of polymer BDT-IPZ-2 was measured.

[0137] Depend on Figure 9 and 10 Both polymers exhibit p-type characteristics, characterized by an irreversible oxidation peak and a negligible reduction peak. The corresponding HOMO / LUMO energy levels and electrochemical band gaps (Eg) for BDT-IPZ-1 and BDT-IPZ-2 were calculated based on the onset oxidation and reduction potentials in the CV curves, as shown in Table 2. This indicates that the energy levels of the donor and acceptor are well matched, enabling effective charge separation at the interface and improving photoelectric conversion efficiency.

[0138] Table 2 Test results

[0139] Donor material HOMO(eV) LUMO(eV) <![CDATA[E g (eV)]]> BDT-IPZ-1 -5.33 -3.62 1.71 BDT-IPZ-2 -5.42 -3.45 1.97

[0140] 5. Photovoltaic performance test:

[0141] An inverted structure organic solar cell was prepared using polymer donors BDT-IPZ-1 and BDT-IPZ-2 as donor materials and Y6 as acceptor material using ITO / PEDOT:PSS / active layer / PDINO / Ag.

[0142] The structure of the small molecule receptor material Y6 used in the present invention is as follows:

[0143]

[0144] The specific process of preparing organic solar cells is as follows: the ITO-coated glass substrate is ultrasonically treated in soapy water, deionized water, acetone and isopropanol for 15 minutes in sequence and dried in an oven overnight. The PEDOT:PSS aqueous solution is filtered through a 0.45mm filter and pre-coated on the pre-cleaned ITO glass at 5000rpm for 30 seconds, followed by annealing at 150°C in air for 30 minutes. The active layer materials BDT-IPZ-1:Y6 and BDT-IPZ-2:Y6 (D:A = 1:1.2, concentration 18 mg mL -1 ) was dissolved in chloroform and 1-chlorodiphenyl (CN) (0.7%, v / v) was added as an additive. The mixed solution was spin-coated on the PEDOT:PSS layer at 3000 rpm for 30 seconds. It was then annealed at 110°C for 10 minutes. Then, a concentration of 0.3 mg mL -1 The PDINO cathode modification layer was formed by depositing a methanol solution of PNDIT-F3N on the active layer at 3000 rpm for 30 seconds. After cooling to room temperature, the sample was transferred to an evaporation chamber. -5 Ag electrodes with a thickness of approximately 100 nm were deposited by evaporation at a pressure of Pa. The device area was 4.0 mm2 , effective area is 4.0mm 2 .

[0145] A Keithley 2400 source-measurement instrument was used under an AM 1.5G solar simulator at 100 mW cm -2 Under light intensity, the current density-voltage (JV) characteristics of the devices made of the polymer donor materials prepared in Example 1 and Example 2 were measured in a N2 atmosphere.

[0146] The QEX10 solar cell external quantum efficiency measurement system was used to measure the external quantum efficiency (EQE) of the devices made from the polymer donor materials prepared in Example 1 and Example 2. The light intensity at each wavelength was calibrated using a standard single crystal silicon photovoltaic cell.

[0147] like Figure 11 As shown in the figure, it is the measured current-voltage curve of polymer BDT-IPZ-1 applied to organic solar cells. Figure 12 Shown is the measured current-voltage curve of polymer BDT-IPZ-2 applied to organic solar cells.

[0148] The photovoltaic performance parameters of the polymer donor materials BDT-IPZ-1 and BDT-IPZ-2 prepared in Test Example 1 and Example 2 are shown in the following table:

[0149] Table 3 Test results

[0150]

[0151] Figure 11 Jinhe Figure 12 As shown in Table 33, organic solar cells based on the polymer donor materials BDT-IPZ-1:Y6 and BDT-IPZ-2:Y6 exhibit high open-circuit voltage, short-circuit current density, and fill factor. This is due to the excellent matching of the donor and acceptor in the active layer, which enables more efficient exciton dissociation and free charge transfer, resulting in high photoelectric conversion efficiency.

[0152] Figure 13 The measured external quantum efficiency (EQE) curve of polymer BDT-IPZ-1 applied to organic solar cells.

[0153] Figure 14 The measured external quantum efficiency (EQE) curve of polymer BDT-IPZ-2 applied to organic solar cells.

[0154] Figure 13 and Figure 14The results show that the photoresponse of organic solar devices based on BDT-IPZ-1:Y6 is higher than that of devices based on BDT-IPZ-2:Y6, especially in the range of ≈400-800nm, and the EQE value even reaches a maximum of 82.87% at 510nm. Therefore, we can conclude that compared with devices based on BDT-IPZ-1:Y6, devices based on BDT-IPZ-2:Y6 show a larger photoresponse area, indicating that the EQE response contributes more to the photocurrent and is more efficient in collecting photons, thereby generating a higher short-circuit current value and achieving higher photoelectric conversion efficiency.

[0155] 6. Photocatalytic degradation of pollutants performance test:

[0156] In the present invention, a donor / acceptor is blended in proportion and dissolved in a solvent to form a liquid heterojunction. The liquid heterojunction is then loaded onto a substrate material with adsorption properties to increase the heterojunction's photocatalytic stability and catalytic efficiency. The polymer donors synthesized in Examples 1 and 2 and the acceptor Y6 are used as photocatalysts. The substrate material and the organic heterojunction can cause organic pollutants to rapidly accumulate on the catalyst surface. Subsequently, the organic pollutants react rapidly with the photogenerated free radicals generated by the organic heterojunction, improving the pollutant removal efficiency through the synergistic effect of adsorption and photocatalysis.

[0157] like Figure 15 As shown in the figure, it is the degradation efficiency curve of the polymer BDT-IPZ-1 used in photocatalytic degradation of pollutants. Figure 16 The figure below shows the measured degradation efficiency curve of the polymer BDT-IPZ-2 for photocatalytic degradation of pollutants. When the catalyst is added and the pollutant solution is stirred under light, the concentration of the pollutants decreases significantly over time, demonstrating the remarkable effectiveness of this new photocatalyst in both adsorption and photocatalysis.

[0158] The present invention discloses a method for preparing and applying a conjugated polymer donor material based on imidazo[1,2-a]pyrazine units, which yields a conjugated polymer based on imidazo[1,2-a]pyrazine units that is easy to synthesize, has a high yield, low cost, good solubility, and good thermal stability. The polymers disclosed herein have good crystallinity and thermal stability, excellent solubility in common organic solvents, and good compatibility with acceptor materials. The organic solar cell device prepared by the present invention exhibits suitable phase separation and ordered molecular stacking in its active layer, has good sunlight capture and hole transport capabilities, and can achieve a high photoelectric conversion efficiency. The conjugated polymer donor material based on imidazo[1,2-a]pyrazine units in the present invention is applied to the photocatalytic degradation of pollutants, which can significantly reduce electron-phonon coupling in the material, thereby promoting exciton delocalization and achieving higher photocatalytic activity.

Claims

1. A conjugated polymer donor material based on imidazo[1,2-a]pyrazine units, characterized in that It is a polymer donor based on benzodithiophene units and imidazo[1,2-a]pyrazine units or a polymer donor based on bithiophene units and imidazo[1,2-a]pyrazine units; The polymer donor based on benzodithiophene units and imidazo[1,2-a]pyrazine units has a general structure as shown in BDT-IPZ: ； The polymer donor based on bithiophene units and imidazo[1,2-a]pyrazine units has a general structure as shown in BP-IPZ: ； R1, R2, R3, R4, R5, and R6 are independently selected from any one of an alkyl group, an alkoxy group, and an alkylthio group; X and Y are independently selected from any one of a hydrogen atom, a fluorine atom, and a chlorine atom; and n is selected from any natural number from 2 to 2000.

2. The conjugated polymer donor material based on imidazo[1,2-a]pyrazine units according to claim 1, characterized in that: The alkyl group, alkoxy group and alkylthio group are respectively a C4-C30 straight-chain alkyl group, a C4-C30 alkoxy group and a C4-C30 alkylthio group.

3. The conjugated polymer donor material based on imidazo[1,2-a]pyrazine units according to claim 2, characterized in that: The R1 and R2 are independently selected from any one of the following structures: 。 4. The conjugated polymer donor material based on imidazo[1,2-a]pyrazine units according to claim 3, characterized in that: The R3, R4, R5, and R6 are independently selected from any one of the following structures: 。 5. The method for preparing a conjugated polymer donor material based on imidazo[1,2-a]pyrazine units according to any one of claims 1 to 4, characterized in that: The steps include: Step 1, synthesis of compound of formula 3: ； Step 2, synthesis of the compound of formula 4: mixing the compound of formula 3 in step 1 with N-bromosuccinimide, N-bromosuccinimide is abbreviated as NBS: ； Step 3: Mix the polymer monomers of formula 4 and 5 to react and synthesize the polymer donor BDT-IPZ: ； Alternatively, the polymeric monomer of formula 4 and the polymeric monomer of formula 6 are mixed and reacted to obtain the polymer donor BP-IPZ: 。 6. The method for preparing a conjugated polymer donor material based on imidazo[1,2-a]pyrazine units according to claim 5, characterized in that: In the step 1, the molar ratio of the compound of formula 1 to the compound of formula 2 is 1:2.4; The solvent for the reaction of the compound of formula 1 with the compound of formula 2 is anhydrous toluene or tetrahydrofuran; The catalyst for the reaction of the compound of Formula 1 with the compound of Formula 2 is tetrakistriphenylphosphine palladium, [1,3-bis(diphenylphosphino)propane]dichloronickel, [1,2-bis(diphenylphosphino)ethane]chloronickel, bis(dibenzylideneacetone)palladium, palladium chloride or palladium acetate; In the step 2, the molar ratio of the compound of formula 3 to N-bromosuccinimide is 1:2.17, where N-bromosuccinimide is abbreviated as NBS; The solvent for the reaction of the compound of formula 3 with N-bromosuccinimide is chloroform or tetrahydrofuran.

7. An organic solar cell, characterized in that: The active layer comprises a donor material and an acceptor material, wherein the donor material is the conjugated polymer donor material based on imidazo[1,2-a]pyrazine units as claimed in any one of claims 1 to 4.

8. A photocatalyst based on the conjugated polymer donor material based on imidazo[1,2-a]pyrazine units according to any one of claims 1 to 4, characterized in that: Its application in photocatalytic degradation of pollutants, photocatalytic hydrogen production or photocatalytic sterilization.

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