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

Abstract

The invention discloses a preparation method and application of a conjugated polymer donor material based on an imidazo [1, 2-a] pyrazine unit, and the conjugated polymer donor material is a polymer donor based on a benzodithiophene unit and the imidazo [1, 2-a] pyrazine unit or a polymer donor based on a bithiophene unit and the imidazo [1, 2-a] pyrazine unit. The general formula structure of the polymer donor based on the benzodithiophene unit and the imidazo [1, 2-a] pyrazine unit is shown as BDT-IPZ: # imgabs 0 #, the general formula structure of the polymer donor based on the bithiophene unit and the imidazo [1, 2-a] pyrazine unit is shown as BP-IPZ: # imgabs 1 #, and 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 in particular 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 way for humans to solve the problem of insufficient energy supply. Organic solar cells have become a photovoltaic technology that has attracted much attention in the photovoltaic field due to their characteristics of being light, easy to prepare on a large scale, and able to be made into semi-transparent devices. The continuous breakthroughs in the field of organic solar cells have attracted widespread attention from researchers, and the highest certified photoelectric conversion efficiency has exceeded 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 optoelectronic devices and 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 for 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 scheme: 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, or an alkylthio group; X and Y are independently selected from any one of a hydrogen atom, a fluorine atom, or 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: Mix the compound of formula 3 in step 1 with N-bromosuccinimide, which 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, and 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 polymer donor BP-IPZ is obtained by mixing the polymer monomer of formula 4 and the polymer monomer of formula 6:

[0030]

[0031] The present invention also discloses an organic solar cell, wherein the active layer of the organic solar cell 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, chlorobenzene, etc., so a solution processing method can be used when preparing devices. 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 is complementary to the absorption of the acceptor material Y6; the donor and acceptor blended layer can form a nano interpenetrating network structure of suitable size, improve the dissociation efficiency of carriers, and improve 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, and can be reused many 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. 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. 13 C NMR spectrum;

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

[0037] Figure 4 The polymerized monomer M1 of the conjugated polymer based on imidazo[1,2-a]pyrazine units of the present invention prepared in Example 1 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] Fig. 9 is the cyclic voltammetry curve of the conjugated polymer based on imidazo[1,2-a]pyrazine unit prepared in Example 1;

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

[0044] Fig.11 is a JV curve of the conjugated polymer based on imidazo[1,2-a]pyrazine unit prepared in Example 1 applied to an organic solar cell;

[0045] Fig.12 is a JV curve of the conjugated polymer based on imidazo[1,2-a]pyrazine unit prepared in Example 2 applied to an organic solar cell;

[0046] Fig.13EQE curve of the conjugated polymer based on imidazo[1,2-a]pyrazine unit prepared in Example 1 applied to an organic solar cell;

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

[0048] Fig.15 is a degradation efficiency curve diagram of the conjugated polymer based on imidazo[1,2-a]pyrazine units prepared in Example 1 applied to photocatalytic degradation of pollutants;

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

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

[0051] In the preparation method and application of the conjugated polymer donor material based on the imidazo[1,2-a]pyrazine unit of the present invention, pyrazine is a heterocyclic aromatic hydrocarbon core with strong electronegativity and a highly planar and symmetrical geometric structure, which helps to enhance the interaction between molecules and synergistically regulate the energy level, absorption spectrum and pre-aggregation behavior of the polymer. Pyrazine after various chemical modifications can be used as a unit of DA copolymerization to design polymer donor materials, and has great potential in the field of building 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 above polymer donor based on benzodithiophene unit and imidazo[1,2-a]pyrazine unit has a general structure as shown in 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] The X is selected from a hydrogen atom, a fluorine atom or a chlorine atom;

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

[0063] The polymer donor based on bithiophene unit and imidazo[1,2-a]pyrazine unit has a general structure as shown in BP-IPZ:

[0064]

[0065] Wherein, R3, R4, R5, and R6 are independently selected from any one of alkyl, alkoxy, and alkylthio; 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 unit and imidazo[1,2-a]pyrazine unit comprises the following steps:

[0073] Step 1, synthesis of the compound of formula 3: mixing 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: Mix the polymer monomer of formula 4 and the polymer monomer of formula 5 to obtain polymer donor BDT-IPZ:

[0080]

[0081] Wherein, the definitions of R3, R4, R5, R6, X and Y are the same as those of 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 all 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), which can be 1:2, 1:2.4, 1:4 or 1:5, and is 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 reacts with N-bromosuccinimide, and the solvent for the reaction is chloroform or tetrahydrofuran, 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 three, 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, and most of the solvent is removed from the chloroform extract by rotary evaporation, and the chloroform extract is added dropwise to methanol for suction filtration, and 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 polymer donor BP-IPZ is obtained by mixing the polymer monomer of formula 4 and the polymer monomer of formula 6:

[0101]

[0102] The present invention also provides an application 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 above-mentioned conjugated polymer donor material based on imidazo[1,2-a]pyrazine units is used in the preparation of the following devices: photovoltaic devices, optoelectronic 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 comprises 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] The application of the conjugated polymer donor material based on the imidazo[1,2-a]pyrazine unit in the field of photocatalysis includes but is not limited to photocatalytic degradation of pollutants, industrial wastewater purification, photocatalytic sterilization, photocatalytic hydrogen production, etc. The polymer can be used as an organic semiconductor catalyst for photocatalysis and applied in the above fields.

[0108] Example 1

[0109] This embodiment provides a conjugated polymer donor material BDT-IPZ-1 based on imidazo[1,2-a]pyrazine units, and 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] 5mmol of the compound 6,8-dibromoimidazo[1,2-a]pyrazine of formula 1 and 12mmol of the compound tributyl(4-(2-butyloctyl)thiophen-2-yl)stannane of formula 1-2 and 0.25mmol of the catalyst tetratriphenylphosphine palladium were added to a dry two-necked round-bottom flask, and 25ml of anhydrous toluene was added after evacuation and nitrogen replacement, and the mixture was heated to 110°C in an oil bath, stirred at 400rpm, and reacted for 12 hours; after the reaction, the mixture solution was cooled to room temperature, extracted with water (70mL) and dichloromethane (70mL×3), the lower organic phase was taken, dried with anhydrous sodium sulfate and filtered, and the crude product was purified by column chromatography after vacuum concentration to obtain a light yellow solid, which is the compound of formula 1-3, with a yield of 72%. The solid was tested, such as Figure 1 As shown, it is the 1H NMR spectrum of the compound of formula 1-3 measured, 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 As shown, it is the 13C NMR spectrum of the compound of formula 1-3 measured, and it can be known 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, and after vacuuming and replacing with nitrogen, 50 ml of ultra-dry tetrahydrofuran was added to the two-necked flask, and 6.5 mmol of N-bromosuccinimide (NBS) was slowly added in batches and reacted at room temperature for 6 hours; after the reaction, 100 ml of methanol was added dropwise to the mixed solution, and 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, such as Figure 3 As shown, it is the 1HNMR spectrum of the polymerized monomer of formula M1 measured,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 is 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 the polymerized monomer of formula M1 and 1 mmol of the polymerized monomer of formula M2 were added to a 50 mL two-necked round-bottom flask, 20 mL of anhydrous toluene was added, the reaction flask was purged with nitrogen for 20 minutes, 50 mg of the catalyst tetrakistriphenylphosphine palladium was added, and then the reaction mixture was purged with nitrogen for 30 minutes, and heated to reflux in an oil bath at 115°C for 22 hours; after the polymerization was completed, the reaction mixture was cooled to room temperature, vacuum concentrated and then dripped into 100 mL of methanol, the solid was collected by suction filtration, and the solid was Soxhlet extracted with methanol, n-hexane and chloroform in turn, the chloroform extract was vacuum concentrated, and dripped into HPLC methanol to precipitate to obtain a solid polymer BDT-IPZ-1, which was sealed and stored for use after vacuum drying. The number average molecular weight (Mn) of the polymer BDT-IPZ-1 was 16.2K and the dispersion (PDI) was 1.83 as measured by gel permeation chromatography.

[0118] Example 2

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

[0120]

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

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

[0123] 1 mmol of the polymerized monomer of formula M1 and 1 mmol of the polymerized monomer of formula M3 were added to a 50 mL two-necked round-bottom flask, 20 mL of anhydrous toluene was added, the reaction flask was purged with nitrogen for 20 minutes, 50 mg of the catalyst tetrakistriphenylphosphine palladium was added, and then the reaction mixture was purged with nitrogen for 30 minutes, and heated to reflux in an oil bath at 115°C for 22 hours; after the polymerization, the reaction mixture was cooled to room temperature, vacuum concentrated and then dripped into 100 mL of methanol, the solid was collected by suction filtration, and the solid was Soxhlet extracted with methanol, n-hexane and chloroform in turn, the chloroform extract was vacuum concentrated, and dripped into HPLC methanol to precipitate to obtain a solid polymer BDT-IPZ-2, which was sealed and stored for use after vacuum drying. The number average molecular weight (Mn) of the polymer BDT-IPZ-2 was 18.6K and the dispersion (PDI) was 2.07 as measured by gel permeation chromatography.

[0124] 3. Thermal stability test:

[0125] The thermogravimetric analysis curves of the polymer donor materials prepared in Example 1 and Example 2 under a nitrogen atmosphere were tested using a synchronous thermal analyzer. 13.84 mg of the polymers of Example 1 and Example 2 were placed in 80 μL alumina crucibles, and the thermogravimetric curves were measured in the 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 polymer BDT-IPZ-2 is shown in FIG. Figure 6 It can be seen that the decomposition temperature of polymer BDT-IPZ-2 at 5% weight loss is 344°C, indicating that polymer BDT-IPZ-2 has better thermal stability than polymer BDT-IPZ-1. Both polymers have good thermal stability and can meet the stability requirements in the processing of common optoelectronic devices.

[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 tested using a UV-visible spectrophotometer, and the empirical formula (Eg = 1240 / λ 吸收边际) The optical band gaps of the two polymer donor materials were calculated. 3 mg of polymer donor materials BDT-IPZ-1 and BDT-IPZ-2 were weighed and dissolved in 1 ml of chloroform, heated and stirred to prepare a solution with a concentration of 3 mg / ml, and part of the solution was spin-coated on a pre-cleaned quartz plate to prepare a uniform 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. The optical performance parameters of polymer donor materials BDT-IPZ-1 and BDT-IPZ-2 prepared in Example 1 and Example 2 are shown in Table 1; it can be seen that the maximum absorption peak of polymer BDT-IPZ-2 film is located at 556nm, the absorption edge is 650nm, and the calculated optical band gap is 1.94eV. This shows that the two polymers have strong absorption capacity and strong 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 tested using a Zahner IM6e electrochemical workstation. The chloroform solution (concentration of 5 mg / ml) of BDT-IPZ-1 and BDT-IPZ-2 was evenly applied on a platinum electrode. After the solvent evaporated naturally and the film was formed, the platinum electrode was immersed in the electrolyte. The platinum plate was used as the working electrode, the platinum wire was used as the counter electrode, and the Ag / Ag + Cyclic voltammetry (CV) measurements were performed in a conventional three-electrode cell using tetrabutylammonium hexafluorophosphate (Bu4NPF6) (0.1 M) acetonitrile solution as the reference electrode and electrolyte. The initial oxidation potential and initial reduction potential were obtained according to the formula (EHOMO / LUMO = -e(E ox / red onset+4.71)(eV) to calculate the HOMO and LUMO energy levels of the thin film state.

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

[0137] Depend on Fig. 9 and 10 It can be seen that both polymers show p-type characteristics with irreversible oxidation peaks and negligible reduction peaks. According to the initial oxidation potential and reduction potential in the CV curve, the HOMO / LUMO energy levels and electrochemical band gaps (Eg) corresponding to BDT-IPZ-1 and BDT-IPZ-2 are calculated respectively as shown in Table 2. It can be seen that the energy level of the donor can be well matched with the energy level of the acceptor, so that effective charge separation can occur at the interface, improving the 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 ITO / PEDOT:PSS / active layer / PDINO / Ag, using polymer donors BDT-IPZ-1 and BDT-IPZ-2 as donor materials and Y6 as acceptor material.

[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 0.45 mm filter, pre-coated on the pre-cleaned ITO glass at 5000 rpm for 30 seconds, and then annealed 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-chlorobiphenyl (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 s. Then it was annealed at 110 °C for 10 min. Then, a concentration of 0.3 mg mL -1 The PNDIT-F3N methanol solution was deposited on the active layer at 3000 rpm for 30 seconds to form a PDINO cathode modification layer. After cooling to room temperature, the sample was transferred to an evaporation chamber. -5 Ag electrode with a thickness of about 100 nm was evaporated and deposited at a pressure of Pa. The device area is 4.0 mm2 , effective area is 4.0mm 2 .

[0145] A Keithley 2400 source-measurement instrument was used with 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 of the polymer donor materials prepared in Example 1 and Example 2. The light intensity of each wavelength was calibrated using a standard single crystal silicon photovoltaic cell.

[0147] like Fig.11 As shown in the figure, it is the current-voltage curve of the polymer BDT-IPZ-1 applied to organic solar cells. Fig.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] Fig.11 Jinhe Fig.12 As shown in Table 33, the organic solar devices based on polymer donor materials BDT-IPZ-1:Y6 and BDT-IPZ-2:Y6 have higher open circuit voltage, short circuit current density and fill factor. This is because the donor and acceptor in the active layer can be well matched, which makes the excitons more effectively dissociated and the free charges more efficiently transmitted, thus achieving higher photoelectric conversion efficiency.

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

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

[0154] Fig.13 and Fig.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 effective in collecting photons, which in turn produces a higher short-circuit current value to obtain a higher photoelectric conversion efficiency.

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

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

[0157] like Fig.15 As shown in FIG. 1 , it is a graph showing the degradation efficiency of the polymer BDT-IPZ-1 used in photocatalytic degradation of pollutants. Fig.16 The figure shows the degradation efficiency curve of the polymer BDT-IPZ-2 used in photocatalytic degradation of pollutants. When the catalyst is added and the pollutant solution is stirred under light, the concentration of the pollutant decreases significantly over time, proving that this new type of photocatalyst has significant effects in adsorption and photocatalysis.

[0158] The preparation method and application of the conjugated polymer donor material based on imidazo[1,2-a]pyrazine units of the present invention obtains a conjugated polymer based on imidazo[1,2-a]pyrazine units that is easy to synthesize, has high yield, low cost, good solubility and good thermal stability. The polymer involved in the present invention has good crystallinity and thermal stability, has good solubility in common organic solvents, and has good compatibility with acceptor materials; the organic solar cell device prepared by the present invention has an active layer that exhibits suitable phase separation and orderly molecular stacking, has good sunlight capture ability and hole transport ability, and can obtain a higher 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 the electron-phonon coupling in the material, thereby promoting the delocalization of excitons 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:

2. The conjugated polymer donor material based on imidazo[1,2-a]pyrazine units according to claim 1, characterized in that: The R1, R2, R3, R4, R5 and R6 are independently selected from any one of an alkyl group, an alkoxy group or an alkylthio group; X and Y are independently selected from any one of a hydrogen atom, a fluorine atom or a chlorine atom; and n is selected from any natural number of 2-2000.

3. The conjugated polymer donor material based on imidazo[1,2-a]pyrazine units according to claim 2, 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.

4. The conjugated polymer donor material based on imidazo[1,2-a]pyrazine units according to claim 3, characterized in that: The R1 and R2 are independently selected from any one of the following structures:

5. The conjugated polymer donor material based on imidazo[1,2-a]pyrazine units according to claim 4, characterized in that: The R3, R4, R5, and R6 are independently selected from any one of the following structures:

6. 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 5, characterized in that: The steps include: Step 1, synthesis of compound of formula 3: Step 2, synthesis of the compound of formula 4: Mix the compound of formula 3 in step 1 with N-bromosuccinimide, which is abbreviated as NBS: Step 3, synthesis of polymer donor BDT-IPZ: mixing the polymer monomer of formula 4 and the polymer monomer of formula 5 for reaction; 7. The method for preparing a conjugated polymer donor material based on imidazo[1,2-a]pyrazine units according to claim 6, 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, and N-bromosuccinimide is abbreviated as NBS; The solvent for the reaction of the compound of formula 3 with N-bromosuccinimide is chloroform or tetrahydrofuran.

8. The method for preparing a conjugated polymer donor material based on imidazo[1,2-a]pyrazine units according to claim 6, characterized in that: The polymer donor BP-IPZ is obtained by mixing the polymer monomer of formula 4 and the polymer monomer of formula 6:

9. An organic solar cell, characterized in that: The active layer comprises a donor material and an acceptor material, wherein the donor material is a conjugated polymer donor material based on imidazo[1,2-a]pyrazine units as described in any one of claims 1 to 5.

10. 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 5, characterized in that: Its applications in photocatalytic degradation of pollutants, photocatalytic hydrogen production, and photocatalytic sterilization.

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