An EDOT-based compound, its preparation method and application in the preparation of electrochromic materials

Abstract

The present invention discloses an EDOT compound, a preparation method thereof, and an application thereof in the preparation of an electrochromic material. The EDOT compound provided by the present invention can be used to prepare high-performance cyan-transparent, magenta-transparent, and yellow-transparent electrochromic films, respectively, through cyclic voltammetry. The EDOT compounds have low color change voltages and can retain 98%, 97%, and 79% of the initial optical contrast after 600 cycles. This not only enriches the color library of polymers prepared by electrochemical polymerization, but also provides a theoretical basis for the subsequent color regulation of electrochromic polymers.

Description

(1) Technical field

[0001] The invention relates to an EDOT compound, a preparation method thereof and application of the EDOT compound in preparing an electrochromic material. (2) Background technology

[0002] Electrochromic materials are a new class of functional materials that undergo a reversible color change under the influence of an applied voltage. They are considered a new generation of display materials due to their environmental friendliness and low energy consumption. However, since electrochromic materials themselves do not emit light, non-emissive displays must use the subtractive primary color method (CMY) to produce various colors.

[0003] However, in the prior art, there is no material that can achieve full-color display based on the three primary colors of CMY, which limits the application of electrochromic materials.

[0004] Based on this, the present invention designed and synthesized three monomers: DAD-type monomer, D-π-D-π-D-type monomer, and pure D-type monomer, and prepared high-performance electrochromic films by cyclic voltammetry, which are cyan, magenta, and yellow in the neutral state and highly transparent when oxidized. It is expected that their application will be further expanded in future development. (3) Summary of the invention

[0005] The present invention aims to provide an EDOT compound, a preparation method thereof, and an application thereof in the preparation of an electrochromic material. The present invention provides EDOT compounds with D, A, and π structures. The prepared electrochromic materials respectively exhibit cyan, magenta, and yellow in a neutral state, exhibit high transparency when oxidized, and achieve the purpose of full-color display based on a three-primary-color electrochromic film.

[0006] The technical solution adopted in the present invention is:

[0007] The present invention provides an EDOT compound, wherein the EDOT compound is one of the following:

[0008]

[0009]

[0010] The compound represented by formula (I) is a DAD type monomer; the compound represented by formula (II) is a D-π-D-π-D type monomer; and the compound represented by formula (III) is a pure D type monomer.

[0011] The present invention also provides a method for preparing the EDOT compound. The compound (I) is prepared as follows: under nitrogen protection, the compound represented by formula (IV) (i.e., tributyl(3,3-dimethyl-3,4-dihydro-2H-thieno[3,4-b][1,4]dioxane-6-yl)stannane) and 4,7-dibromobenzothiadiazole represented by formula (V) are reacted in the presence of tetrakis(triphenylphosphine)palladium (Pd(PPh3)4) and ultra-dry N,N-dimethylformamide (DMF). After the reflux reaction is complete, the reaction solution is post-treated to obtain the compound represented by formula (I), which is recorded as Bt. The molar ratio of the compound represented by formula (IV) to the 4,7-dibromobenzothiadiazole represented by formula (V) is 2 to 4:1 (preferably 3:1); the added volume of the ultra-dry DMF is 50 to 100 mL / g (preferably 70 mL / g) based on the mass of 4,7-dibromobenzothiadiazole; the molar ratio of the Pd(PPh3)4 to the total amount of the compound represented by formula (IV) and 4,7-dibromobenzothiadiazole is 0.001 to 0.1:1, preferably 0.03:1;

[0012]

[0013] The post-treatment method of the reaction liquid is as follows: the reaction liquid is cooled to room temperature, the reaction mixture is extracted with dichloromethane, the organic phase is washed three times with saturated brine, and then dried with anhydrous Na2SO4, and the sample is concentrated and mixed under vacuum using 200-300 mesh silica gel until the solvent is completely removed, and the sample is loaded on a chromatography column, wherein the upper layer of the chromatography column is quartz sand and the bottom layer is 300-400 mesh silica gel, and dichloromethane / petroleum ether with a volume ratio of 1:2 is used as an eluent, and natural elution is performed, and all the effluent is collected, and concentrated to dryness under reduced pressure to obtain the compound represented by formula (I).

[0014] The compound (II) of the present invention is prepared by the following method: under nitrogen protection, the compound represented by formula (IV) (i.e., tributyl (3,3-dimethyl-3,4-dihydro-2H-thieno [3,4-b] [1,4] dioxane-6-yl) stannane) and the compound represented by formula (VI) (i.e., 5,5'-dibromo-2,2":5',2"-terthiophene) are reacted under reflux in the presence of Pd (PPh3)4 and ultra-dry DMF until the reaction is complete, and the reaction solution is separated and purified to obtain the compound represented by formula (II). ), denoted as Q3TQ; the molar ratio of the compound represented by formula (IV) to the compound represented by formula (VI) is 2-4:1 (preferably 3:1); the added volume of the ultra-dry DMF is 50-100 mL / g (preferably 70 mL / g) based on the mass of the compound represented by formula (VI); the molar ratio of the Pd(PPh3)4 to the compound represented by formula (VI) and the total molar ratio of the compound represented by formula (VI) is 0.001-0.1:1, preferably 0.03:1;

[0015]

[0016] The method for separating and purifying the reaction liquid is as follows: the reaction liquid is cooled to room temperature, the reaction mixture is extracted with dichloromethane, the organic phase is washed three times with saturated brine, and then dried over anhydrous Na2SO4, 200-300 mesh silica gel is added, and the sample is concentrated and mixed under vacuum to remove the solvent, and the sample is loaded on a chromatography column, wherein the upper layer of the chromatography column is quartz sand and the bottom layer is 300-400 mesh silica gel, and dichloromethane / petroleum ether with a volume ratio of 1:1 is used as an eluent, and natural elution is performed, all the effluent is collected, and it is concentrated to dryness under reduced pressure to obtain the compound represented by formula (II).

[0017] The compound (III) of the present invention is prepared according to the following steps:

[0018] (1) Under nitrogen protection, 3,4-dimethoxythiophene represented by formula (VII) and 2,2-bis(bromomethyl)propane-1,3-diol are refluxed in the presence of p-toluenesulfonic acid and ultra-dry toluene to generate a compound represented by formula (VIII) (i.e., 3,3-bis(bromomethyl)-3,4-dihydro-2H-thieno[3,4-b][1,4]dioxetane); the ratio of the amount of the 2,2-bis(bromomethyl)propane-1,3-diol to the amount of the 3,4-dimethoxythiophene is 1 to 2:1 (preferably 1.1:1); the ratio of the amount of the p-toluenesulfonic acid to the amount of the 3,4-dimethoxythiophene is 0.1 to 0.3:1 (preferably 0.1:1); the volume of the ultra-dry toluene added is 80 to 130 mL / g (preferably 100 mL / g) based on the mass of 3,4-dimethoxythiophene;

[0019] (2) Under nitrogen protection, the compound represented by formula (VIII) and 2-ethylhexanol are reacted under reflux reaction in the presence of sodium hydride and ultra-dry DMF to produce the compound represented by formula (IX) (i.e., 3,3-bis-(2-ethylhexyloxy)methyl)-3,4-dihydro-2H-thieno[3,4-b][1,4]dioxetane); the ratio of the amount of sodium hydride to the compound represented by formula (VIII) is 0.4-0.7:1 (preferably 0.5:1); the ratio of the amount of 2-ethylhexanol to the compound represented by formula (VIII) is 0.3-0.5:1 (preferably 0.3:1); the volume of the ultra-dry DMF added is 1.8-3 mL / g (preferably 1.9 mL / g) based on the mass of the compound represented by formula (VIII);

[0020] (3) At -78°C under nitrogen protection, the compound represented by formula (IX) and ultra-dry tetrahydrofuran (i.e., anhydrous and oxygen-free tetrahydrofuran) are added to a flask, and n-butyllithium (n-BuLi) in n-hexane solution is added dropwise thereto. After stirring at this temperature for 30-45 minutes, tributyltin chloride is added thereto to react and generate the compound represented by formula (X) (i.e., tributyltin 3,3-bis-(2-ethylhexyloxy)methyl)-3,4-dihydro-2H-thieno[3,4-b][1,4] dioxetane); the added volume of the ultra-dry tetrahydrofuran is 10-20 mL / g (preferably 14 mL / g) based on the mass of the compound represented by formula (IX); the concentration of the n-BuLi n-hexane solution is 1.6-2.4 M, the ratio of the amount of n-BuLi to the compound represented by formula (IX) is 1-1.5:1 (preferably 1.05:1); the ratio of the amount of tributyltin chloride to the compound represented by formula (IX) is 1-1.5:1 (preferably 1.1:1);

[0021] (4) Under nitrogen protection, 5,5-dibromo-3,4-ethylenedioxythiophene shown in formula (XI) and phenylboronic acid react in the presence of Pd(PPh3)4 and ultra-dry tetrahydrofuran in a K2CO3 aqueous solution to generate 2,5-diphenyl-3,4-ethylenedioxythiophene shown in formula (XII); the ratio of the amount of phenylboronic acid to the amount of 5,5-dibromo-3,4-ethylenedioxythiophene is 2 to 2.3:1; the ultra-dry tetrahydrofuran is added The volume is 2 to 2.5 mL / g based on the mass of 5,5-dibromo-3,4-ethylenedioxythiophene; the concentration of the K2CO3 aqueous solution is 2 M, and the added volume is 1.4 to 1.6 mL / g based on the mass of 5,5-dibromo-3,4-ethylenedioxythiophene; the ratio of the amount of Pd(PPh3)4 to the total amount of 5,5-dibromo-3,4-ethylenedioxythiophene and phenylboric acid is 0.01-0.1:1, preferably 0.03:1;

[0022] (5) Under the condition of 0°C, 2,5-diphenyl-3,4-ethylenedioxythiophene represented by formula (XII) reacts with liquid bromine diluted with chloroform in chloroform to produce the compound represented by formula (i) (i.e., 2,5-bis(4'-bromophenyl)-3,4-ethylenedioxythiophene); the volume of chloroform added is 4 to 8 mL / g based on the mass of 2,5-diphenyl-3,4-ethylenedioxythiophene; the volume of chloroform added to dilute the liquid bromine is 18 to 25 mL / g based on the mass of 2,5-diphenyl-3,4-ethylenedioxythiophene; the ratio of the amount of liquid bromine to the amount of 2,5-diphenyl-3,4-ethylenedioxythiophene is 2 to 2.5:1;

[0023] (6) Under nitrogen protection, the compound represented by formula (i) and the compound represented by formula (X) react in the presence of Pd(PPh3)4 and ultra-dry DMF to produce the compound represented by formula (III), which is denoted as proBEBpro; the molar ratio of the compound represented by formula (X) to the compound represented by formula (i) is 2 to 4:1, preferably 3:1; the added volume of the ultra-dry DMF is 40 to 100 mL / g, preferably 44 mL / g, based on the mass of the compound represented by formula (i); the molar ratio of Pd(PPh3)4 to the total molar ratio of the compound represented by formula (i) and the compound represented by formula (X) is 0.01-0.1:1, preferably 0.03:1;

[0024]

[0025]

[0026] Preferably, step (1) is carried out as follows: under nitrogen protection, 3,4-dimethoxythiophene, 2,2-bis(bromomethyl)propane-1,3-diol, p-toluenesulfonic acid, and ultra-dry toluene are added to a flask, heated under reflux for 18 hours, cooled to room temperature, extracted with dichloromethane, the organic phase is washed three times with saturated brine, dried over anhydrous Na2SO4, 200-300 mesh silica gel is added, concentrated and mixed under vacuum, and loaded onto a chromatography column, wherein the upper layer of the chromatography column is quartz sand and the bottom layer is 300-400 mesh silica gel; dichloromethane / petroleum ether with a volume ratio of 1:3 is used as an eluent, eluted naturally, all the effluent is collected, and concentrated to dryness under reduced pressure to obtain 3,3-bis(bromomethyl)-3,4-dihydro-2H-thieno[3,4-b][1,4]dioxetane represented by formula (VIII).

[0027] Preferably, step (2) is carried out as follows: under nitrogen protection, sodium hydride is added to a flask, 2-ethylhexanol is added dropwise thereto, ultra-dry DMF is added after stirring at room temperature for 30 minutes, and reflux is maintained for 2.5 hours, and 3,3-bis(bromomethyl)-3,4-dihydro-2H-thieno[3,4-b][1,4]dioxetane is added, and the reaction is continued for 24 hours, cooled to room temperature, and the reaction mixture is extracted with dichloromethane. The organic phase is washed three times with saturated brine and washed with anhydrous N The mixture was dried over a2SO4, added with 200-300 mesh silica gel, concentrated and mixed under vacuum, and loaded onto a chromatography column, wherein the upper layer of the chromatography column was quartz sand and the bottom layer was 300-400 mesh silica gel; dichloromethane / petroleum ether with a volume ratio of 2:3 was used as the eluent, and natural elution was performed. All the effluent was collected, and concentrated under reduced pressure until no liquid effluent was obtained to obtain the target product 3,3-bis-(2-ethylhexyloxymethyl)-3,4-dihydro-2H-thieno[3,4-b][1,4]dioxetane (IX).

[0028] Preferably, step (3) is carried out as follows: at -78°C under nitrogen protection, the compound represented by formula (IX) and ultra-dry tetrahydrofuran (i.e., anhydrous and oxygen-free tetrahydrofuran) are added to a flask, and a n-hexane solution of n-BuLi is added dropwise thereto; after stirring at this temperature for 30-45 minutes, tributyltin chloride is added thereto, the reaction mixture is naturally warmed to room temperature, stirred overnight, and loaded onto a separation column with anhydrous alumina as the stationary phase, and rapidly eluted with dichloromethane as the eluent, and all the effluent is collected and the solvent is removed by spin drying to obtain the compound represented by formula (X).

[0029] Preferably, step (4) is carried out as follows: under nitrogen protection, 5,5-dibromo-3,4-ethylenedioxythiophene, phenylboric acid, Pd(PPh3)4, ultra-dry tetrahydrofuran, and K2CO3 aqueous solution are added to a flask, heated to reflux for 18 hours, cooled to room temperature, and the reaction mixture is extracted with dichloromethane. The organic phase is washed three times with saturated brine, dried over anhydrous Na2SO4, and spin-dried; the crude product is recrystallized with methanol to obtain the target product 2,5-diphenyl-3,4-ethylenedioxythiophene (Ⅻ).

[0030] Preferably, step (5) is carried out as follows: 2,5-diphenyl-3,4-ethylenedioxythiophene and chloroform are added to a flask at 0°C, liquid bromine diluted with chloroform is added dropwise thereto, and after stirring at room temperature for 20-40 minutes, the solution is washed with a 3% mass concentration NaOH aqueous solution, a saturated NaHSO3 aqueous solution and deionized water in sequence, the organic layer is dried over anhydrous Na2SO4 and spin-dried; the crude product is recrystallized from petroleum ether to obtain 2,5-bis(4'-bromophenyl)-3,4-ethylenedioxythiophene (i).

[0031] Preferably, step (6) is carried out as follows: under nitrogen protection, the compound represented by formula (i), the compound represented by formula (X), Pd(PPh3)4, and ultra-dry DMF are added to a flask, heated to reflux for 18 hours, cooled to room temperature, and the reaction mixture is extracted with dichloromethane. The organic phase is washed three times with saturated brine, dried over anhydrous Na2SO4, 200-300 mesh silica gel is added, and the sample is concentrated and mixed under vacuum to remove the solvent and loaded onto a chromatography column, wherein the upper layer of the chromatography column is quartz sand and the bottom layer is 300-400 mesh silica gel; dichloromethane / petroleum ether with a volume ratio of 1:1 is used as the eluent, and natural elution is performed, all the effluent is collected, and concentrated under reduced pressure until no liquid flows out to obtain the compound represented by formula (III).

[0032] The present invention also provides an application of the EDOT compound in the preparation of a transparent electrochromic material, wherein the compound represented by formula (I) is used to prepare a cyan-transparent electrochromic film, the compound represented by formula (II) is used to prepare a magenta-transparent electrochromic film, and the compound represented by formula (III) is used to prepare a yellow-transparent electrochromic film.

[0033] Preferably, the application method is as follows: dissolving the compound represented by formula (I), formula (II) or formula (III) in a mixed solvent of dichloromethane and acetonitrile containing tetrabutylammonium hexafluorophosphate (TBAPF6), ultrasonicating at 50kHz for 5min, and after complete dissolution, performing electrochemical polymerization; using ITO glass (0.9*4cm) as the working electrode, platinum wire as the counter electrode, and Ag / AgCl electrode as the reference electrode, polymerizing the film by cyclic voltammetry, with a voltage range of -0.3~1.2V (preferably 0~1.1V) and a scanning speed of 100mV / s. After the completion of electropolymerization, the ITO covered with the polymer film is The glass is cleaned in a mixed cleaning agent of dichloromethane and acetonitrile to remove unpolymerized monomers or oligomers and residual electrolyte on the film surface, and then naturally dried in air to obtain an ITO glass with a transparent electrochromic film on the surface; the concentration of the compound represented by formula (I), formula (II) or formula (III) is 0.01 to 1.5 mmol / L (preferably 0.01 mmol / L), and the concentration of tetrabutylammonium hexafluorophosphate is 0.1 to 0.12 mol / L (preferably 0.1 mol / L); the volume ratio of dichloromethane to acetonitrile in the mixed solvent and the mixed cleaning agent is 2-4:1. The volume ratio of dichloromethane to acetonitrile corresponding to the compound represented by formula (I) is 4:1; the volume ratio of dichloromethane to acetonitrile corresponding to the compound represented by formula (II) or formula (III) is 7:3.

[0034] Compared with the prior art, the beneficial effects of the present invention are mainly reflected in that the EDOT compounds provided by the present invention can be used to prepare high-performance cyan-transparent (pBt), magenta-transparent (pQ3TQ), and yellow-transparent (pproBEBpro) electrochromic films by cyclic voltammetry. Among them, the cyan-transparent (pBt) electrochromic film has a lower color-changing voltage (<0.7V). At 770nm, the coloring time is 0.63s, the fading time is 0.49s, and after 600 cycles, it can still retain an optical contrast of 98% of the initial value; the magenta-transparent (pQ3TQ) electrochromic film has a lower color-changing voltage (<1V). At 531nm, the coloring time is 0.63s, the fading time is 0.29s, and after 600 cycles, it can still retain an optical contrast of 96.9% of the initial value; the yellow-transparent (p(proBEBpro)) electrochromic film has a lower color-changing voltage (<1V). At 444nm, the coloring time is 1.58s, the fading time is 0.59s, and after 600 cycles, it can still retain an optical contrast of 79.2% of the initial value. The above three monomers not only enrich the color library of polymers prepared by electrochemical polymerization, but also provide a theoretical basis for the subsequent regulation of the color of electrochromic polymers. (IV) Description of the accompanying drawings

[0035] Figure 1 This is a synthetic route for the compounds represented by formula (I), formula (II) and formula (III).

[0036] Figure 2 The cyclic voltammetry polymerization curves of the thin films prepared from the compounds represented by formula (I), formula (II) and formula (III) are shown.

[0037] Figure 3 The UV-visible absorption spectra of electrochromic films prepared from compounds represented by formula (I), formula (II), and formula (III) at different voltages.

[0038] Figure 4 The response time of the electrochromic film prepared from the compounds represented by formula (I), formula (II) and formula (III) in different wavelength bands.

[0039] Figure 5 The optical contrast of the electrochromic films prepared from the compounds represented by formula (I), formula (II) and formula (III) under different cycle numbers.

[0040] Figure 6 The compound represented by formula (I), formula (II) or formula (III) 1 H NMR spectrum. (V) Specific implementation methods

[0041] The present invention is further described below with reference to specific examples, but the scope of protection of the present invention is not limited thereto: The ultra-dry toluene used in the examples of the present invention refers to anhydrous and oxygen-free toluene; the ultra-dry DMF solution used refers to anhydrous and oxygen-free N,N-dimethylformamide. The chromatography column of the example of the present invention has a height of 70 cm and a diameter of 5 cm. The upper layer of the chromatography column is quartz sand, with a packing height of 1-2 cm to prevent the silica gel used for sample mixing from being dispersed. The middle layer is silica gel used for sample mixing, with a packing height of 1-2 cm; the bottom layer is 300-400 mesh fine silica gel, with a packing height of 50 cm.

[0042] Example 1. Synthesis of compound Bt of formula (I):

[0043] 4,7-Dibromobenzothiadiazole (V, 0.29 g, 1 mmol), tributyl(3,3-dimethyl-3,4-dihydro-2H-thieno[3,4-b][1,4]dioxane-6-yl)stannane (IV, 1.42 g, 3 mmol), and 0.12 mmol of Pd(PPh3)4 were weighed into a 100 mL two-necked round-bottom flask. Under nitrogen, 20 mL of ultra-dry DMF (N,N-dimethylformamide) solution was added. The mixture was heated under reflux for 18 hours and then cooled to room temperature. The reaction mixture was extracted with dichloromethane. The organic phase was washed three times with saturated brine and dried over anhydrous Na2SO4. 200-300 mesh silica gel was added and the sample was concentrated under vacuum to remove the solvent before loading onto a chromatography column. The mixture was naturally eluted with dichloromethane / petroleum ether (volume ratio 1:2) as the eluent, and all the effluent was collected and concentrated to dryness under reduced pressure to remove the eluent to obtain an orange solid (0.45 g, yield 90%), which is the compound of formula (I), recorded as Bt.

[0044] The H-NMR spectrum characterization is as follows: 1 H NMR (600MHz, CDCl3) δ8.27(s,2H),6.70(s,2H),3.93(s,4H),3.85(s,4H),1.10(s,12H).

[0045] Example 2, Synthesis of Compound Q3TQ represented by Formula (II):

[0046] 5,5"-Dibromo-2,2':5',2"-terthiophene (VI, 0.41 g, 1 mmol), tributyl(3,3-dimethyl-3,4-dihydro-2H-thieno[3,4-b][1,4]dioxane-6-yl)stannane (IV, 1.42 g, 3 mmol), and 0.12 mmol of Pd(PPh3)4 were weighed and added to a 100 mL two-necked round-bottom flask. Under nitrogen protection, 20 mL of ultra-dry DMF solution was added, and the mixture was heated under reflux for 18 h and cooled to room temperature. The reaction mixture was extracted with dichloromethane, and the organic phase was washed three times with saturated brine, dried over anhydrous Na2SO4, and 200-300 mesh silica gel was added. The sample was concentrated under vacuum to remove the solvent and loaded onto a chromatography column. The mixture was naturally eluted with dichloromethane / petroleum ether (volume ratio 1:1), and all the effluent was collected and concentrated to dryness under reduced pressure to obtain an orange solid (0.4 g, yield 65.3%), which is the compound represented by formula (II), denoted as Q3TQ.

[0047] The H-NMR spectrum characterization is as follows: 1 H NMR (600MHz, CDCl3) δ7.12 (d, J = 3.8 Hz, 2H), 7.10 (d, J = 7.6 Hz, 2H), 7.08 (d, J = 3.8 Hz, 2H), 6.41 (s, 2H), 3.85 (d, J = 21.4 Hz, 8H), 1.10 (s, 12H).

[0048] Example 3. Preparation of the compound proBEBpro represented by formula (III)

[0049] 1. Synthesis of 3,3-bis(bromomethyl)-3,4-dihydro-2H-thieno[3,4-b][1,4]dioxetane (VIII):

[0050] 3,4-Dimethoxythiophene (VII, 2.11 g, 15 mmol), 2,2-bis(bromomethyl)propane-1,3-diol (4.21 g, 16 mmol), and p-toluenesulfonic acid (0.278 g, 1.5 mmol) were weighed and added to a 250 mL two-necked round-bottom flask. Under nitrogen, 200 mL of ultra-dry toluene was added and the mixture was heated under reflux for 18 hours. The mixture was then cooled to room temperature. The reaction mixture was extracted with dichloromethane. The organic phase was washed three times with saturated brine, dried over anhydrous Na2SO4, and filled with 200-300 mesh silica gel. The sample was concentrated under vacuum to remove the solvent and applied to a chromatography column. The product was naturally eluted with dichloromethane / petroleum ether (volume ratio 1:3) and all the effluent was collected and concentrated to dryness under reduced pressure to obtain a white solid (4.51 g, yield 88%), which was 3,3-bis(bromomethyl)-3,4-dihydro-2H-thieno[3,4-b][1,4]dioxetane (VIII).

[0051] The product was characterized by H NMR spectrum as follows: 1 H NMR (600MHz, CDCl3) δ6.47 (s, 2H), 4.08 (s, 4H), 3.59 (s, 4H).

[0052] 2. Synthesis of 3,3-bis-(2-ethylhexyloxy)methyl)-3,4-dihydro-2H-thieno[3,4-b][1,4]dioxetane (IX):

[0053] Weigh sodium hydride (6.5 g, 270 mmol) and add 2-ethylhexanol (17.7 g, 150 mmol, 2.13 mL) dropwise under a nitrogen atmosphere. Stir at room temperature for 30 min, then add 30 mL of ultra-dry DMF solution. Heat under reflux for 2.5 h. Add 3,3-bis(bromomethyl)-3,4-dihydro-2H-thieno[3,4-b][1,4]dioxetane (VIII, 15.5 g, 500 mmol) and continue heating for 24 h. Cool to room temperature. Extract the reaction mixture with dichloromethane, and wash the organic phase three times with saturated brine. Dry over anhydrous Na2SO4, add 200-300 mesh silica gel, concentrate under vacuum, and apply to a chromatography column. The mixture was naturally eluted with dichloromethane / petroleum ether (volume ratio 2:3) as the eluent, and all the effluent was collected and concentrated under reduced pressure until no liquid flowed out to obtain a colorless liquid (13.7 g, yield 80%), which was 3,3-bis-(2-ethylhexyloxymethyl)-3,4-dihydro-2H-thieno[3,4-b][1,4]dioxetane (IX).

[0054] The product was characterized by H NMR spectrum as follows: 1 H NMR (600MHz, CDCl3) δ6.42 (s, 2H), 4.02 (s, 4H), 3.49 (s, 4H), 3.33 (d, J = 5.6Hz, 4H), 1.57-1.29 (m, 18H), 0.94 (m, 12H).

[0055] 3. Synthesis of tributyltin 3,3-bis-(2-ethylhexyloxy)methyl)-3,4-dihydro-2H-thieno[3,4-b][1,4]dioxetane (X):

[0056] Weigh 3,3-bis-(2-ethylhexyloxymethyl)-3,4-dihydro-2H-thieno[3,4-b][1,4]dioxetane (IX, 2.13 g, 4.83 mmol) into a 100 mL eggplant-shaped flask. Under nitrogen, add 30 mL of anhydrous, oxygen-free tetrahydrofuran solution. Cool to -78°C, and add a 2.4 M n-BuLi (5.94 mmol) solution in n-hexane dropwise. Stir at this temperature for 30 minutes, then add tributyltin chloride (1.95 g, 6 mmol). Remove from the cooling tank, allow the reaction mixture to warm to room temperature, and stir overnight. The sample was loaded onto a separation column (50 cm high, 5 cm in diameter, and 50 cm packed height) with 300-400 mesh anhydrous alumina as the stationary phase. Using dichloromethane as the eluent, rapid elution was performed. The entire effluent was collected and concentrated to dryness under reduced pressure to obtain 3.5 g of a slightly yellow oily substance, namely tributyltin 3,3-bis-(2-ethylhexyloxy)methyl)-3,4-dihydro-2H-thieno[3,4-b][1,4]dioxetane (X). Because the product readily decomposed upon heating, no further purification was performed.

[0057] 4. Synthesis of 2,5-diphenyl-3,4-ethylenedioxythiophene (XII):

[0058] 5,5-Dibromo-3,4-ethylenedioxythiophene (Ⅺ), 12.7 g, 42.4 mmol, phenylboronic acid (11.4 g, 93.2 mmol), and Pd(PPh₃)₄ (0.392 g, 4.068 mmol) were weighed and added to a 100 mL two-necked round-bottom flask. Under nitrogen, 30 mL of ultra-dry tetrahydrofuran and 20 mL of a 2M aqueous solution of K₂CO₃ were added. The mixture was heated to reflux for 18 hours and then cooled to room temperature. The reaction mixture was extracted with dichloromethane, and the organic phase was washed three times with saturated brine. The mixture was dried over anhydrous Na₂SO₄ and concentrated to dryness under reduced pressure. The crude product was recrystallized from methanol to obtain yellow needle-shaped crystals (7.91 g, 63% yield), namely 2,5-diphenyl-3,4-ethylenedioxythiophene (Ⅻ).

[0059] The product was characterized by H NMR spectrum as follows: 1 H NMR (600MHz, CDCl3) δ7.79 (d, J = 7.2 Hz, 4H), 7.41 (t, J = 7.2 Hz, 4H), 7.26 (t, J = 7.2 Hz, 2H), 4.36 (s, 4H).

[0060] 5. Synthesis of 2,5-bis(4'-bromophenyl)-3,4-ethylenedioxythiophene (i):

[0061] 2,5-Diphenyl-3,4-ethylenedioxythiophene (XII, 9.50 g, 32.3 mmol) was weighed and added to a 250 mL two-necked round-bottom flask with 50 mL of chloroform. 200 mL of chloroform-diluted bromine (3.31 mL, 64.6 mmol) was added dropwise at 0°C. After stirring at room temperature for 6 h, the mixture was washed sequentially with a 3% aqueous NaOH solution (aq), a saturated aqueous NaHSO₃ solution (aq), and deionized water. The organic layer was dried over anhydrous Na₂SO₄ and concentrated to dryness under reduced pressure. The crude product was recrystallized from petroleum ether to obtain yellow needle-shaped crystals (14.1 g, 97%), namely 2,5-bis(4'-bromophenyl)-3,4-ethylenedioxythiophene (i).

[0062] The product was characterized by H NMR spectrum as follows: 1 H NMR (600MHz, CDCl3) δ7.61 (d, J = 8.4 Hz, 4H), 7.48 (d, J = 8.4 Hz, 4H), 4.37 (s, 4H).

[0063] 6. Synthesis of proBEBpro represented by formula (III):

[0064] 2,5-Bis(4'-bromophenyl)-3,4-ethylenedioxythiophene (i, 0.452 g, 1 mmol), tributyltin 3,3-bis(2-ethylhexyloxymethyl)-3,4-dihydro-2H-thieno[3,4-b][1,4]dioxetane (X, 2.19 g, 3 mmol), and 0.12 mmol of Pd(PPh3)4 were added to a 100 mL two-necked round-bottom flask. Under nitrogen, 20 mL of ultra-dry DMF solution was added, and the mixture was heated under reflux for 18 hours before cooling to room temperature. The reaction mixture was extracted with dichloromethane, and the organic phase was washed three times with saturated brine. The mixture was dried over anhydrous Na2SO4, added with 200-300 mesh silica gel, and concentrated under vacuum to remove the solvent before loading onto a chromatography column. Using dichloromethane / petroleum ether (volume ratio 1:1) as eluent, natural elution was performed, all the effluent was collected, and concentrated under reduced pressure until no liquid effluent, and finally 1.35 g of yellow oil was obtained, which was proBEBpro represented by formula (III).

[0065] The product was characterized by H NMR spectrum as follows: 1 H NMR (600MHz, CDCl3) δ7.78-7.70 (m, 8H), 6.44 (d, J = 3.9Hz, 2H), 4.37 (s, 4H), 4.0 2(s,8H),3.49(s,8H),3.33(d,J=5.6Hz,8H),1.57-1.29(m,36H),0.94(m,24H).

[0066] Example 4: Preparation of pBt Thin Film by Cyclic Voltammetry

[0067] The monomer Bt (5 mg, 1 mmol) prepared by the method of Example 1 and tetrabutylammonium hexafluorophosphate (0.387 g, 1 mmol) were added to a 10 mL volumetric flask with a mixture of dichloromethane and acetonitrile (V / V = 8:2) and the volume was adjusted to 10 mL. Ultrasonication was applied at 50 kHz for 5 minutes to completely dissolve the mixture. The mixture was then poured into a 10 mL beaker for electrochemical polymerization. Cyclic voltammetry was used to form a film using an ITO glass (0.9 x 4 cm) working electrode, a platinum wire as the counter electrode, and an Ag / AgCl electrode as the reference electrode. The voltage range was -0.3 to 1.2 V, a scan rate of 100 mV / s, and 6 scans. After the electropolymerization is completed, the ITO glass covered with the polymer film is cleaned in a mixed cleaning agent of dichloromethane and acetonitrile (V / V=8:2) to remove the monomers or oligomers that have not been polymerized on the surface of the film and the residual electrolyte, and then dried naturally in the air for use. The ITO glass covered with the electrochromic film is obtained. The cyclic voltammetry polymerization curve is shown in FIG. Figure 2 As shown in a.

[0068] Example 5: Preparation of pQ3TQ Thin Films by Cyclic Voltammetry

[0069] The monomer Q3TQ (6.12 mg, 1 mmol) prepared by the method of Example 2 and tetrabutylammonium hexafluorophosphate (0.387 g, 1 mmol) were added to a 10 mL volumetric flask and the solvent was a mixture of dichloromethane and acetonitrile (V / V = 7:3). The volume was adjusted to 10 mL. Ultrasonication was performed at 50 kHz for 5 minutes to completely dissolve the mixture. The mixture was then poured into a 10 mL beaker for electrochemical polymerization. Polymerization films were formed by cyclic voltammetry using an ITO glass (0.9 x 4 cm) working electrode, a platinum wire as the counter electrode, and an Ag / AgCl electrode as the reference electrode. The voltage range was -0.3 to 1.1 V, a scan rate of 100 mV / s, and 5 scans. After the electropolymerization is completed, the ITO glass covered with the polymer film is cleaned in a mixed cleaning agent of dichloromethane and acetonitrile (V / V=7:3) to remove the monomers or oligomers that have not been polymerized on the surface of the film and the residual electrolyte, and then dried naturally in the air for use. The ITO glass covered with the electrochromic film is obtained. The cyclic voltammetry polymerization curve is shown in FIG. Figure 2 As shown in b.

[0070] Example 6: Preparation of p(proBEBpro) Thin Film by Cyclic Voltammetry

[0071] The monomer proBEBpro (11.7 mg, 1 mmol) prepared by the method of Example 3 and tetrabutylammonium hexafluorophosphate (0.387 g, 1 mmol) were added to a 10 mL volumetric flask and the solvent was a mixed solvent of dichloromethane and acetonitrile (V / V = 7:3). The volume was adjusted to 10 mL. Ultrasonication was performed at 50 kHz for 5 minutes. After complete dissolution, the mixed solution was poured into a 10 mL beaker for electrochemical polymerization. Cyclic voltammetry was used to polymerize the film using ITO glass (0.9*4 cm) as the working electrode, platinum wire as the counter electrode, and an Ag / AgCl electrode as the reference electrode. The voltage range was 0-1.1 V, the scan rate was 100 mV / s, and the scan was 8 cycles. After the electropolymerization is completed, the ITO glass covered with the polymer film is cleaned in a mixed cleaning agent of dichloromethane and acetonitrile (V / V=7:3) to remove the monomers or oligomers that have not been polymerized on the surface of the film and the residual electrolyte, and then dried naturally in the air for use. The ITO glass covered with the electrochromic film is obtained. The cyclic voltammetry polymerization curve is shown in FIG. Figure 2 As shown in c.

[0072] Example 7: Performance test of high-performance CMY primary color electrochromic material

[0073] The electrochemical, optical and electrochromic performance tests were carried out using a Chenhua 660 electrochemical workstation in conjunction with a UV-visible spectrophotometer. The specific process was as follows: tetrabutylammonium hexafluorophosphate (0.387 g, 1 mmol) was added to a 10 mL volumetric flask and diluted to volume with chromatographic grade dichloromethane to serve as a blank solution. Two portions of blank solution and two portions of blank ITO glass were placed in two cuvettes, and the cuvettes were placed in a UV-visible spectrophotometer to scan the baseline. After the scan, one of the blank ITO glasses was replaced with an ITO glass covered with a polymer film prepared in Example 4-6, and a platinum sheet was placed therein as a counter electrode, and an Ag / AgCl electrode was used as a reference electrode. Different voltages were applied for 30 seconds using a Chenhua 660 electrochemical workstation, and then the UV-visible spectrophotometer was used to complete the scan in the wavelength range of 300 to 1100 nm to obtain the spectrum of the polymer film at different voltages.

[0074] 1. UV-visible absorption spectra of electrochromic films at different voltages

[0075] The UV-visible spectrophotometer was scanned at -0.3, -0.2, -0.1, 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, and 0.9 V, respectively. Figure 3 As shown, Figure 3It shows that the pBt electrochromic film can switch between cyan and transparent at -0.3~0.8V; the pQ3TQ electrochromic film can switch between magenta and transparent at -0.3~0.7V; and the p(proBEBpro) electrochromic film can switch between yellow and transparent at 0~0.9V.

[0076] 2. Response time of electrochromic films in different wavelengths

[0077] according to Figure 3 The data determined that the coloring time and fading time of the electrochromic film prepared by the compounds represented by formula (I), formula (II) and formula (III) were detected by corresponding complete color change voltage step detection at 687nm, 532nm and 444nm, respectively. The results are shown in Figure 4 As shown, Figure 4 It shows that the coloring time of the pBt electrochromic film at 770nm is 0.63s, and the fading time is 0.49s; the coloring time of the pQ3TQ electrochromic film at 531nm is 0.63s, and the fading time is 0.29s; the coloring time of the p(proBEBpro) electrochromic film at 444nm is 1.58s, and the fading time is 0.59s.

[0078] 3. Optical contrast of electrochromic films under different cycle numbers

[0079] according to Figure 4 The optical contrast of the electrochromic films prepared by the compounds represented by formula (I), formula (II) and formula (III) was detected at 687nm, 532nm and 444nm respectively. The results are shown in Figure 5 As shown, Figure 5 It shows that the pBt electrochromic film can still retain 98% of the initial optical contrast after 600 cycles at 770nm; the pQ3TQ electrochromic film can still retain 96.9% of the initial optical contrast after 600 cycles at 531nm; and the p(proBEBpro) electrochromic film can still retain 79.2% of the initial optical contrast after 600 cycles at 444nm.

[0080] The results showed that: the pBt electrochromic film has a low color change voltage (<0.7V) and can switch between cyan and transparent. At 770nm, the coloring time is 0.63s and the fading time is 0.49s. After 600 cycles, it can still retain 98% of the initial optical contrast; the pQ3TQ electrochromic film has a low color change voltage (<1V) and can switch between magenta and transparent. At 531nm, the coloring time is 0.63s and the fading time is 0.29s. After 600 cycles, it can still retain 96.9% of the initial optical contrast; the p(proBEBpro) electrochromic film has a low color change voltage (<1V) and can switch between yellow and transparent. At 444nm, the coloring time is 1.58s and the fading time is 0.59s. After 600 cycles, it can still retain 79.2% of the initial optical contrast.

[0081] The above three conductive polymers not only enrich the color library of polymers prepared by electrochemical polymerization, but also provide a theoretical basis for the subsequent regulation of the color of electrochromic polymers.

Claims

1. An EDOT compound for preparing an electrochromic material, characterized in that: The EDOT compound is one of the following: In formula III, R2 is 2. A method for preparing the EDOT compound according to claim 1, characterized in that: The compound (II) was prepared as follows: under nitrogen protection, the compound represented by formula (IV) and the compound represented by formula (VI) were refluxed to complete reaction in the presence of Pd(PPh3)4 and ultra-dry DMF, the reaction solution was cooled to room temperature, the reaction mixture was extracted with dichloromethane, the organic phase was washed three times with saturated brine, dried over anhydrous Na2SO4, 200-300 mesh silica gel was added, the sample was concentrated and mixed under vacuum to remove the solvent, the sample was loaded onto a chromatography column, and the solution was naturally eluted using dichloromethane / petroleum ether in a volume ratio of 1:1 as the eluent. All the effluent was collected and concentrated to dryness under reduced pressure to obtain the compound represented by formula (II); 3. The method according to claim 2, wherein The ratio of the amount of the compound represented by formula (IV) to the amount of the compound represented by formula (VI) is 2 to 4:1; the added volume of the ultra-dry DMF is 50 to 100 mL / g based on the mass of the compound represented by formula (VI); the ratio of the amount of Pd(PPh3)4 to the total amount of the compound represented by formula (IV) and the compound represented by formula (VI) is 0.03:

1.

4. A method for preparing the EDOT compound according to claim 1, characterized in that: The compound (III) is prepared according to the following steps: (1) Under nitrogen protection, 3,4-dimethoxythiophene represented by formula (VII) and 2,2-bis(bromomethyl)propane-1,3-diol are refluxed in the presence of p-toluenesulfonic acid and ultra-dry toluene to generate a compound represented by formula (VIII); the ratio of the amount of the 2,2-bis(bromomethyl)propane-1,3-diol to the amount of 3,4-dimethoxythiophene is 1 to 2:1; the ratio of the amount of the p-toluenesulfonic acid to the amount of 3,4-dimethoxythiophene is 0.1 to 0.3:1; the volume of the ultra-dry toluene added is 80 to 130 mL / g based on the mass of 3,4-dimethoxythiophene; (2) Under nitrogen protection, the compound represented by formula (VIII) and 2-ethylhexanol are refluxed in the presence of sodium hydride and ultra-dry DMF to produce the compound represented by formula (IX); the ratio of the amount of sodium hydride to the compound represented by formula (VIII) is 0.4 to 0.7:1; the ratio of the amount of 2-ethylhexanol to the compound represented by formula (VIII) is 0.3 to 0.5:1; the volume of the ultra-dry DMF added is 1.8 to 3 mL / g based on the mass of the compound represented by formula (VIII); (3) At -78°C under nitrogen protection, the compound represented by formula (IX) and ultra-dry tetrahydrofuran are added to a flask, and a n-hexane solution of n-BuLi is added dropwise thereto. After stirring at this temperature for 30-45 minutes, tributyltin chloride is added thereto to react and generate the compound represented by formula (X); the volume of the ultra-dry tetrahydrofuran added is 10-20 mL / g based on the mass of the compound represented by formula (IX); the concentration of the n-hexane solution of n-BuLi is 1.6-2.4 M, the ratio of the amount of n-BuLi to the compound represented by formula (IX) is 1-1.5:1; the ratio of the amount of tributyltin chloride to the compound represented by formula (IX) is 1-1.5:1; (4) Under nitrogen protection, 5,5-dibromo-3,4-ethylenedioxythiophene shown in formula (XI) and phenylboric acid react in the presence of Pd(PPh3)4 and ultra-dry tetrahydrofuran in a K2CO3 aqueous solution to generate 2,5-diphenyl-3,4-ethylenedioxythiophene shown in formula (XII); the ratio of the amount of phenylboric acid to the amount of 5,5-dibromo-3,4-ethylenedioxythiophene is 2 to 2.3:1; the ultra-dry tetrahydrofuran is used. The added volume of hydrofuran is 2 to 2.5 mL / g based on the mass of 5,5-dibromo-3,4-ethylenedioxythiophene; the concentration of the K2CO3 aqueous solution is 2 M, and the added volume is 1.4 to 1.6 mL / g based on the mass of 5,5-dibromo-3,4-ethylenedioxythiophene; the molar ratio of the Pd(PPh3)4 to the total amount of 5,5-dibromo-3,4-ethylenedioxythiophene and phenylboric acid is 0.03:1; (5) Under the condition of 0°C, 2,5-diphenyl-3,4-ethylenedioxythiophene represented by formula (XII) reacts with liquid bromine diluted with chloroform in chloroform to generate a compound represented by formula (i); the volume of the chloroform added is 4 to 8 mL / g based on the mass of 2,5-diphenyl-3,4-ethylenedioxythiophene; the volume of the chloroform added to dilute the liquid bromine is 18 to 25 mL / g based on the mass of 2,5-diphenyl-3,4-ethylenedioxythiophene; the ratio of the amount of the liquid bromine to the amount of the 2,5-diphenyl-3,4-ethylenedioxythiophene fed is 2 to 2.5:1; (6) Under nitrogen protection, the compound represented by formula (i) and the compound represented by formula (X) react in the presence of Pd(PPh3)4 and ultra-dry DMF to generate the compound represented by formula (III); the molar ratio of the compound represented by formula (X) to the compound represented by formula (i) is 2 to 4:1; the volume of the ultra-dry DMF added is 40 to 100 mL / g based on the mass of the compound represented by formula (i); and the molar ratio of Pd(PPh3)4 to the total molar ratio of the compound represented by formula (i) and the compound represented by formula (X) is 0.01 to 0.1:1; 5. The preparation method according to claim 4, wherein The compound (III) is prepared according to the following steps: (1) Under nitrogen protection, 3,4-dimethoxythiophene, 2,2-bis(bromomethyl)propane-1,3-diol, p-toluenesulfonic acid, and ultra-dry toluene were added to a flask, heated under reflux for 18 hours, cooled to room temperature, extracted with dichloromethane, and the organic phase was washed three times with saturated brine, dried over anhydrous Na2SO4, added with 200-300 mesh silica gel, concentrated and mixed under vacuum, and loaded onto a chromatography column; using dichloromethane / petroleum ether in a volume ratio of 1:3 as the eluent, eluted naturally, collected all the effluent, and concentrated to dryness under reduced pressure to obtain 3,3-bis(bromomethyl)-3,4-dihydro-2H-thieno[3,4-b][1,4]dioxetane represented by formula (VIII); (2) Under nitrogen protection, sodium hydride was added to a flask, 2-ethylhexanol was added dropwise thereto, and ultra-dry DMF was added after stirring at room temperature for 30 minutes. The mixture was heated under reflux for 2.5 hours, and 3,3-bis(bromomethyl)-3,4-dihydro-2H-thieno[3,4-b][1,4]dioxetane was added. The reaction was continued for 24 hours, and the mixture was cooled to room temperature. The reaction mixture was extracted with dichloromethane, and the organic phase was cleaned with saturated brine. Wash three times, dry with anhydrous Na2SO4, add 200-300 mesh silica gel, concentrate and mix the sample under vacuum, and load it onto a chromatography column; use dichloromethane / petroleum ether (volume ratio 2:3) as eluent, elute naturally, collect all the effluent, and concentrate under reduced pressure until no liquid effluent, to obtain the target product 3,3-bis-(2-ethylhexyloxy)methyl)-3,4-dihydro-2H-thieno[3,4-b][1,4]dioxetane (IX); (3) At -78°C under nitrogen protection, the compound represented by formula (IX) and ultra-dry tetrahydrofuran are added to a flask, and a n-hexane solution of n-BuLi is added dropwise thereto; after stirring at this temperature for 30-45 minutes, tributyltin chloride is added thereto, the reaction mixture is naturally warmed to room temperature, stirred overnight, and loaded onto a separation column with anhydrous alumina as the stationary phase and rapidly eluted with dichloromethane as the eluent, and the entire effluent is collected and the solvent is removed by spin drying to obtain the compound represented by formula (X); (4) Under nitrogen protection, 5,5-dibromo-3,4-ethylenedioxythiophene, phenylboric acid, Pd(PPh3)4, ultra-dry tetrahydrofuran, and K2CO3 aqueous solution were added to a flask, heated under reflux for 18 hours, cooled to room temperature, and the reaction mixture was extracted with dichloromethane. The organic phase was washed three times with saturated brine, dried over anhydrous Na2SO4, and spin-dried; the crude product was recrystallized from methanol to obtain the target product 2,5-diphenyl-3,4-ethylenedioxythiophene (XII); (5) At 0°C, 2,5-diphenyl-3,4-ethylenedioxythiophene and chloroform were added to a flask, and bromine diluted with chloroform was added dropwise thereto. After stirring at room temperature for 20-40 minutes, the mixture was washed with a 3% aqueous solution of NaOH, a saturated aqueous solution of NaHSO3, and deionized water in sequence. The organic layer was dried over anhydrous Na2SO4 and spin-dried. The crude product was recrystallized from petroleum ether to obtain 2,5-bis(4'-bromophenyl)-3,4-ethylenedioxythiophene (i). (6) Under nitrogen protection, the compound represented by formula (i), the compound represented by formula (X), Pd(PPh3)4, and ultra-dry DMF were added to a flask, heated under reflux for 18 hours, cooled to room temperature, and the reaction mixture was extracted with dichloromethane. The organic phase was washed three times with saturated brine, dried over anhydrous Na2SO4, and 200-300 mesh silica gel was added. The sample was concentrated and mixed under vacuum to remove the solvent and loaded onto a chromatography column. The upper layer of the chromatography column was quartz sand and the bottom layer was 300-400 mesh silica gel. Dichloromethane / petroleum ether in a volume ratio of 1:1 was used as the eluent, and the elution was carried out naturally. All the effluent was collected and concentrated under reduced pressure until no liquid effluent, thereby obtaining the compound represented by formula (III).

6. Use of the EDOT compound according to claim 1 in preparing a transparent electrochromic material.

7. The use according to claim 6, characterized in that The application method comprises the following steps: dissolving the compound represented by formula (II) or formula (III) in a mixed solvent of dichloromethane and acetonitrile containing tetrabutylammonium hexafluorophosphate, subjecting the compound to ultrasonic treatment at 50 kHz for 5 minutes, and performing electrochemical polymerization after the compound is completely dissolved; using ITO glass as a working electrode, a platinum wire as a counter electrode, and an Ag / AgCl electrode as a reference electrode, polymerizing the compound into a film by cyclic voltammetry, with a voltage range of -0.3 to 1.2 V and a scanning speed of 100 mV / s; after the electropolymerization is completed, cleaning the ITO glass covered with the polymer film in a mixed cleaning agent of dichloromethane and acetonitrile to remove unpolymerized monomers or oligomers on the surface of the film and residual electrolyte, and then naturally drying the film in air to obtain an ITO glass with a surface covered with a transparent electrochromic film.

8. The use according to claim 7, characterized in that The concentration of the compound represented by formula (II) or formula (III) is 0.01-1.5 mmol / L, the concentration of tetrabutylammonium hexafluorophosphate is 0.1-0.12 mol / L; the volume ratio of dichloromethane to acetonitrile in the mixed solvent and the mixed cleaning agent is 2-4:1.

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