A cyan-transparent electrochromic polymer and a preparation method and application thereof

Abstract

This invention provides a cyan-transparent electrochromic polymer, its preparation method, and its applications, belonging to the field of electrochromic polymer technology. The invention uses 6,6'-(2,6-dibromo-4H-cyclopentano[2,1-b:3,4-b']dithiophene-4,4-diyl)bis(hexyl-1-ol), 2,6-di(trimethyltin)-4,4-di(2-ethylhexyl)-dithiophenecyclopentadiene, and 4,7-dibromobenzo[c][1,2,5]thiadiazole as main raw materials, reacting them under the action of a catalyst to obtain a cyan-transparent electrochromic polymer. The film made from the cyan-transparent electrochromic polymer of this invention has an optical contrast ratio of 47.01% in the 719 nm wavelength range, a coloring time of 0.81 s, and a fading time of 0.32 s.

Description

Technical Field

[0001] This invention relates to the field of electrochromic polymer technology, and more particularly to a cyan-transparent electrochromic polymer, its preparation method, and its applications. Background Technology

[0002] Solution-processable electrochromic materials, as a type of organic electrochromic material, have attracted widespread attention due to their diverse and simple film-forming methods. Currently, solution-processable electrochromic material systems capable of switching between cyan and transparent states are still under development, while materials exhibiting high contrast, low response time, and high stability in switching between cyan and transparent states are relatively rare. Therefore, researching a cyan-transparent electrochromic polymer, its preparation method, and its applications is of great significance. Summary of the Invention

[0003] The purpose of this invention is to provide a cyan-transparent electrochromic polymer and its preparation method, so as to solve the problems of low contrast, high response time and poor stability of cyan-transparent electrochromic materials in the prior art.

[0004] To achieve the above-mentioned objectives, the present invention provides the following technical solution: This invention provides a cyan-transparent electrochromic polymer, the structure of which is shown in formula (I):

[0005] (I)

[0006] Where x and y are independently selected from any integer from 5 to 25.

[0007] The present invention also provides a method for preparing the above-mentioned cyan-transparent electrochromic polymer, comprising the following steps: in a protective atmosphere, 6,6'-(2,6-dibromo-4H-cyclopenta[2,1-b:3,4-b']dithiophene-4,4-diyl)bis(hexyl-1-ol), 2,6-di(trimethyltin)-4,4-di(2-ethylhexyl)-dithiophenecyclopentadiene, and 4,7-dibromobenzo[c][1,2,5]thiadiazole are reacted under the action of a catalyst to obtain the cyan-transparent electrochromic polymer.

[0008] Preferably, the catalyst is Pd2(dba)3 and P(o-tol)3.

[0009] Preferably, the molar ratio of 6,6'-(2,6-dibromo-4H-cyclopentano[2,1-b:3,4-b']dithiophene-4,4-diyl)bis(hexyl-1-ol) and 4,7-dibromobenzo[c][1,2,5]thiadiazole is 1:3~5.

[0010] Preferably, the molar ratio of 6,6'-(2,6-dibromo-4H-cyclopentano[2,1-b:3,4-b']dithiophene-4,4-diyl)bis(hexyl-1-ol) and 2,6-di(trimethyltin)-4,4-di(2-ethylhexyl)-dithiophenecyclopentadiene is 1:4~6.

[0011] Preferably, the molar ratio of Pd2(dba)3 to 6,6'-(2,6-dibromo-4H-cyclopentano[2,1-b:3,4-b']dithiophene-4,4-diyl)bis(hexyl-1-ol) is 0.01~0.1:1.

[0012] Preferably, the molar ratio of P(o-tol)3 to 6,6'-(2,6-dibromo-4H-cyclopentano[2,1-b:3,4-b']dithiophene-4,4-diyl)bis(hexane-1-ol) is 0.01~0.1:1.

[0013] Preferably, the reaction temperature is 100~120℃ and the time is 15~17h.

[0014] Preferably, the reaction is followed by post-processing, which involves mixing the reacted solution with methanol and then filtering the mixture. The resulting filter cake is then extracted and the solvent is removed to obtain a cyan-transparent electrochromic polymer.

[0015] The present invention also provides an application of the above-described cyan-transparent electrochromic polymer in electronic shelf labels.

[0016] The beneficial effects of this invention are: This invention prepares a solution-processable electrochromic material by Stille coupling polymerization of 6,6'-(2,6-dibromo-4H-cyclopenta[2,1-b:3,4-b']dithiophene-4,4-diyl)bis(hexyl-1-ol) and 2,6-di(trimethyltin)-4,4-di(2-ethylhexyl)-dithiophenecyclopentadiene with 4,7-dibromobenzo[c][1,2,5]thiadiazole.

[0017] The cyan-transparent electrochromic polymer film prepared by this invention has an optical contrast ratio of 47.01% in the 719 nm wavelength range, a coloring time of 0.81 s, and a fading time of 0.32 s.

[0018] The electrochromic film of this invention exhibits a cyan color in the neutral state, and eventually becomes transparent as the applied voltage increases. After 1000 cycles at step voltages of 0V and 1.0V, the optical contrast of the HWQ-OH electrochromic film can maintain 85.19% of the initial contrast. It is a high-performance solution-processable electrochromic material that can switch between cyan and transparent colors, and is expected to be applied in the field of electronic shelf labels. Attached Figure Description

[0019] Figure 1 The synthetic route for the cyan-transparent electrochromic polymer of the present invention is as follows; Figure 2 This is the CV curve of the HWB-OH electrochromic thin film in Application Example 1 of the present invention; Figure 3 The following are the UV-Vis absorption spectra of the HWB-OH electrochromic thin film of Application Example 1 of the present invention at different voltages; Figure 4 The response time diagram of the HWB-OH electrochromic thin film in Application Example 1 of the present invention at 719 nm wavelength is shown. Figure 5 This is a stability test diagram of the HWB-OH electrochromic thin film of Application Example 1 of the present invention at 719 nm. Figure 6 The colorimetric properties of the HWB-OH electrochromic film in Application Example 1 of this invention under different voltages. Detailed Implementation

[0020] This invention provides a cyan-transparent electrochromic polymer, the structure of which is shown in formula (I):

[0021] (I)

[0022] Where x and y are independently selected from any integer from 5 to 25.

[0023] In this invention, x:y = 1:3~5, specifically 1:3, 1:4, 1:5.

[0024] The present invention also provides a method for preparing the above-mentioned cyan-transparent electrochromic polymer, comprising the following steps: in a protective atmosphere, 6,6'-(2,6-dibromo-4H-cyclopenta[2,1-b:3,4-b']dithiophene-4,4-diyl)bis(hexyl-1-ol), 2,6-di(trimethyltin)-4,4-di(2-ethylhexyl)-dithiophenecyclopentadiene, and 4,7-dibromobenzo[c][1,2,5]thiadiazole are reacted under the action of a catalyst to obtain the cyan-transparent electrochromic polymer.

[0025] In this invention, the protective atmosphere is preferably nitrogen.

[0026] In this invention, the structure of 6,6'-(2,6-dibromo-4H-cyclopentano[2,1-b:3,4-b']dithiophene-4,4-diyl)bis(hexane-1-ol) is shown in Formula (II):

[0027] (II).

[0028] In this invention, the preparation method of 6,6'-(2,6-dibromo-4H-cyclopentano[2,1-b:3,4-b']dithiophene-4,4-diyl)bis(hexane-1-ol) comprises the following steps: ① In a protective atmosphere, cyclopentothiophene and 2-(6-bromohexoxy)tetrahydro-2H-pyran were reacted with a catalyst to give 4,4-bis(8-((tetrahydro-2H-pyran-2-yl)oxy)octyl)-4H-cyclopento[2,1-b:3,4-b']dithiophene; ② Under a protective atmosphere, 4,4-bis(8-((tetrahydro-2H-pyran-2-yl)oxy)octyl)-4H-cyclopentano[2,1-b:3,4-b']dithiophene and pyridinium 4-methylbenzenesulfonate were reacted in anhydrous ethanol to give 6,6'-(4H-cyclopentano[2,1-b:3,4-b']dithiophene-4,4-diyl)di(hexane-1-ol); ③ Under a protective atmosphere, 6,6'-(4H-cyclopentano[2,1-b:3,4-b']dithiophene-4,4-diyl)bis(hexane-1-ol) and N-bromosuccinimide are mixed and reacted in tetrahydrofuran to obtain 6,6'-(2,6-dibromo-4H-cyclopentano[2,1-b:3,4-b']dithiophene-4,4-diyl)bis(hexane-1-ol).

[0029] In this invention, the catalyst in step ① is preferably potassium iodide, and the mass ratio of the catalyst to cyclopentylthiophene is 15~30mg:1g, preferably 20~25mg:1g; The molar ratio of cyclopentylthiophene and 2-(6-bromohexyloxy)tetrahydro-2H-pyran in step ① is 1:2~5, preferably 1:3~4.

[0030] In this invention, the solvent used in step ① is dimethyl sulfoxide, and the volume-to-mass ratio of dimethyl sulfoxide to cyclopentylthiophene is 10~100mL:1g, specifically 10mL / g, 20mL / g, 30mL / g, 40mL / g, 50mL / g, 60mL / g, 70mL / g, 80mL / g, 90mL / g, or 100mL / g.

[0031] In this invention, the reaction temperature in step ① is 10~33℃, preferably 15~30℃, and more preferably 20~25℃; the reaction time is 22~24h, preferably 23h.

[0032] In this invention, the structural formula of 4,4-bis(8-((tetrahydro-2H-pyran-2-yl)oxy)octyl)-4H-cyclopentano[2,1-b:3,4-b']dithiophene in step ① is as follows: .

[0033] In this invention, the molar ratio of 4,4-bis(8-((tetrahydro-2H-pyran-2-yl)oxy)octyl)-4H-cyclopenta[2,1-b:3,4-b']dithiophene and pyridinium 4-methylbenzenesulfonate in step ② is 1:2~5, more preferably 1:3~4; The volume-to-mass ratio of the anhydrous ethanol to 4,4-bis(8-((tetrahydro-2H-pyran-2-yl)oxy)octyl)-4H-cyclopenta[2,1-b:3,4-b']dithiophene is 10~100mL:1g, specifically 10mL / g, 20mL / g, 30mL / g, 40mL / g, 50mL / g, 60mL / g, 70mL / g, 80mL / g, 90mL / g, and 100mL / g.

[0034] In this invention, the reaction temperature in step ② is 10~33℃, preferably 15~30℃, and more preferably 20~25℃; the reaction time is 22~24h, preferably 23h.

[0035] In this invention, the structural formula of 6,6'-(4H-cyclopentano[2,1-b:3,4-b']dithiophene-4,4-diyl)di(hexane-1-ol) in step ② is as follows: .

[0036] In this invention, the molar ratio of 6,6'-(4H-cyclopenta[2,1-b:3,4-b']dithiophene-4,4-diyl)di(hexyl-1-ol) and N-bromosuccinimide in step ③ is 1:1~4, preferably 1:2~3; The volume-to-mass ratio of the tetrahydrofuran and 6,6'-(4H-cyclopenta[2,1-b:3,4-b']dithiophene-4,4-diyl)di(hexyl-1-ol) is 10~100mL:1g, specifically 10mL / g, 20mL / g, 30mL / g, 40mL / g, 50mL / g, 60mL / g, 70mL / g, 80mL / g, 90mL / g, or 100mL / g.

[0037] In this invention, the reaction temperature in step ③ is 10~33℃, preferably 15~30℃, and more preferably 20~25℃; the reaction time is 22~24h, preferably 23h.

[0038] In this invention, the structure of 2,6-bis(trimethyltin)-4,4-bis(2-ethylhexyl)-dithiophenecyclopentadiene is shown in formula (III):

[0039] (III).

[0040] In this invention, the structure of the 4,7-dibromobenzo[c][1,2,5]thiadiazole is shown in formula (Ⅳ):

[0041] (Ⅳ).

[0042] In this invention, the catalyst is Pd2(dba)3 and P(o-tol)3.

[0043] In this invention, the molar ratio of 6,6'-(2,6-dibromo-4H-cyclopentano[2,1-b:3,4-b']dithiophene-4,4-diyl)bis(hexyl-1-ol) and 4,7-dibromobenzo[c][1,2,5]thiadiazole is 1:3 to 5, specifically 1:3, 1:4, or 1:5.

[0044] In this invention, the molar ratio of 6,6'-(2,6-dibromo-4H-cyclopentano[2,1-b:3,4-b']dithiophene-4,4-diyl)bis(hexyl-1-ol) and 2,6-di(trimethyltin)-4,4-di(2-ethylhexyl)-dithiophenecyclopentadiene is 1:4 to 6, specifically 1:4, 1:5, or 1:6.

[0045] In this invention, the molar ratio of Pd2(dba)3 to 6,6'-(2,6-dibromo-4H-cyclopentano[2,1-b:3,4-b']dithiophene-4,4-diyl)bis(hexyl-1-ol) is 0.01~0.1:1.

[0046] In this invention, the molar ratio of P(o-tol)3 to 6,6'-(2,6-dibromo-4H-cyclopentano[2,1-b:3,4-b']dithiophene-4,4-diyl)bis(hexyl-1-ol) is 0.01~0.1:1.

[0047] In this invention, the solvent preferably used for preparing the cyan-transparent electrochromic polymer is toluene; based on the mass of 6,6'-(2,6-dibromo-4H-cyclopentano[2,1-b:3,4-b']dithiophene-4,4-diyl)bis(hexyl-1-ol), the volume of toluene added is 40~200 mL / g, specifically 40 mL / g, 50 mL / g, 60 mL / g, 70 mL / g, 80 mL / g, 100 mL / g, 120 mL / g, 150 mL / g, 180 mL / g, or 200 mL / g.

[0048] In this invention, the reaction temperature is 100~120℃, specifically 100℃, 105℃, 110℃, 115℃, or 120℃, and the reaction time is 15~17h, specifically 15h, 16h, or 17h.

[0049] In this invention, a post-processing step is required after the reaction. The post-processing steps are as follows: the solution after the reaction is mixed with methanol and then filtered. The resulting filter cake is extracted and the solvent is removed to obtain a cyan-transparent electrochromic polymer.

[0050] In this invention, the solvents used during extraction are methanol, acetone, petroleum ether, and chloroform.

[0051] In this invention, the solvents are used in the following order: methanol, acetone, petroleum ether, and chloroform.

[0052] The present invention also provides an application of the above-described cyan-transparent electrochromic polymer in the preparation of electronic shelf labels.

[0053] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0054] Example 1

[0055] In a nitrogen atmosphere, cyclopentylthiophene and 2-(6-bromohexoxy)tetrahydro-2H-pyran were mixed in a molar ratio of 1:3, and dimethyl sulfoxide (dimethyl sulfoxide to cyclopentylthiophene in a molar ratio of 50 mL:1 g) and potassium iodide (potassium iodide to cyclopentylthiophene in a molar ratio of 20 mg:1 g) were added. The mixture was reacted at 20 °C for 24 h. After the reaction, the reaction solution was dispersed in deionized water, extracted with dichloromethane, and the organic phase was collected. The organic phase was dried with anhydrous sodium sulfate, and the solvent was removed by rotary evaporation. The product was purified by column chromatography using ethyl acetate as the eluent. The obtained product was 4,4-bis(8-((tetrahydro-2H-pyran-2-yl)oxy)octyl)-4H-cyclopentano[2,1-b:3,4-b']dithiophene. The NMR data of the product are as follows: 1H NMR (400 MHz, CDCl3) δ7.14 (d, J = 4.9 Hz, 1H), 6.91 (d, J = 4.9 Hz, 1H), 4.52 (t, J = 3.6 Hz, 1H), 3.88 – 3.78 (m, 1H), 3.65 (dt, J = 9.6, 6.9 Hz, 1H), 3.51 – 3.43 (m, 1H), 3.30 (dt, J = 9.6, 6.7 Hz, 1H), 1.82 (d, J = 16.5 Hz, 3H), 1.74 – 1.64 (m,1H), 1.44 (d, J = 7.0 Hz, 2H), 1.26 (d, J = 3.7 Hz, 2H), 1.25 – 1.09 (m, 4H), 0.99 – 0.84 (m, 3H).

[0056] In a nitrogen atmosphere, 4,4-bis(8-((tetrahydro-2H-pyran-2-yl)oxy)octyl)-4H-cyclopentano[2,1-b:3,4-b']dithiophene and pyridinium 4-methylbenzenesulfonate were mixed in a molar ratio of 1:3, and anhydrous ethanol was added (the ratio of anhydrous ethanol to 4,4-bis(8-((tetrahydro-2H-pyran-2-yl)oxy)octyl)-4H-cyclopentano[2,1-b:3,4-b']dithiophene was 50 mL: 1 g), and the mixture was reacted at 20 °C for 24 h. After the reaction was completed, the reaction solution was dispersed in deionized water, extracted with dichloromethane, the organic phase was collected, dried with anhydrous sodium sulfate, the solvent was removed by rotary evaporation, and column chromatography was performed using ethyl acetate as the eluent to purify the product, which was 6,6'-(4H-cyclopentano[2,1-b:3,4-b']dithiophene-4,4-diyl)di(hexyl-1-ol). The NMR data of the product are as follows: ¹H NMR (400 MHz, CDCl₃) δ 7.15 (d, J = 4.8 Hz, 3H), 6.92 (d, J = 4.9 Hz, 3H), 3.56 (t, J = 6.6 Hz, 6H), 1.87 – 1.78 (m, 6H), 1.42 (s, 13H), 1.28 (s, 1H), 1.26 – 1.09 (m, 15H), 1.00 – 0.87 (m, 7H).

[0057] Under nitrogen protection, 6,6'-(4H-cyclopenta[2,1-b:3,4-b']dithiophene-4,4-diyl)di(hexane-1-ol) and N-bromosuccinimide were mixed in a molar ratio of 1:2, and tetrahydrofuran was added (the molar ratio of tetrahydrofuran to 6,6'-(4H-cyclopenta[2,1-b:3,4-b']dithiophene-4,4-diyl)di(hexane-1-ol was 50 mL: 1 g), and the reaction was carried out at 25 °C for 22 h. After the reaction was complete, the reaction solution was dispersed in deionized water, extracted with dichloromethane, and the organic phase was collected. The organic phase was dried with anhydrous sodium sulfate, and the solvent was removed by rotary evaporation. The product was purified by column chromatography using ethyl acetate as the eluent, yielding 6,6'-(2,6-dibromo-4H-cyclopentano[2,1-b:3,4-b']dithiophene-4,4-diyl)bis(hexane-1-ol). The NMR data of the product are as follows: 1 H NMR (400 MHz, CDCl3) δ 6.92 (s, 1H), 3.58 (t, J = 6.6 Hz, 2H).

[0058] Weigh 6,6'-(2,6-dibromo-4H-cyclopentano[2,1-b:3,4-b']dithiophene-4,4-diyl)bis(hexyl-1-ol) (100 mg, 0.186 mmol), 2,6-di(trimethyltin)-4,4-di(2-ethylhexyl)-dithiophenecyclopentadiene (678.9 mg, 0.932 mmol), and 4,7-dibromobenzo[c][1,2,5]thiadiazole (219.22 mg, 0.746 mmol) and add them to a 15 mL Schlenk tube. Under nitrogen protection, add 15 mL of anhydrous toluene, Pd2(dba)3 (18.31 mg, 0.02 mmol), and P(o-tol)3 (6.09 mg, 0.02 mmol). React at 110 °C for 15 h and cool to room temperature. The reaction solution was added to 300 mL of methanol, filtered using a Buchner funnel, and the filter cake was washed with methanol. The filter cake was then wrapped in filter paper and extracted using a Soxhlet extractor to extract polymers of different degrees of polymerization. During extraction, solvents with different solubilities were used in the following order: methanol, acetone, petroleum ether, and chloroform. Finally, the chloroform-extracted portion was removed by rotary evaporation to obtain a cyan-transparent electrochromic polymer, denoted as HWB-OH (where x:y = 1:4). The NMR data are as follows: 1 H NMR (400 MHz, CDCl3) δ 8.13 (s,1H), 7.88 (s, 1H), 5.34 (s, 1H), 3.60 (s, 1H), 2.08 – 2.00 (m, 3H), 1.63 (d, J= 8.8 Hz, 1H), 1.25 (s, 5H), 1.03 (s, 9H), 0.76 (s, 2H), 0.68 (s, 11H), 0.07 (s, 9H).

[0059] Application Example 1

[0060] Add 45 mg of HWB-OH to a 10 mL beaker, then add 3 mL of chloroform to each beaker. Shake to mix thoroughly, then filter using a 0.45 μm microporous filter. Finally, spin coat the mixture at 25°C. HWB-OH electrochromic thin films were prepared by spin-coating a film onto the conductive surface of a 40 mm ITO glass layer (parameter settings: 1000 rpm, spin-coating time 1 min).

[0061] Performance verification: (1) Electrochemical testing of HWB-OH electrochromic thin film Electrochemical tests were performed using a Chenhua 660 electrochemical workstation with the following parameter settings: CV mode, scan rates of 50 mV / s, 100 mV / s, 200 mV / s, 300 mV / s, and 500 mV / s, and scan ranges of 1.0 V and 0 V. Figure 2 As shown, the HWB-OH electrochromic film exhibits an electrochemical response within the scanning range, and its CV curve shows quasi-reversible redox behavior.

[0062] (2) Optical and electrochromic properties testing of HWB-OH electrochromic thin film

[0063] Optical and electrochromic properties were tested using a Chenhua 660 electrochemical workstation coupled with a Shimadzu UV1800 UV-Vis spectrophotometer. The test results are as follows: Figure 3 , 4 As shown in Figure 5.

[0064] from Figure 3 It can be seen that the maximum absorption peak of the film in the neutral state (0.0 V) is 719 nm; as the voltage increases, the original absorption peak gradually disappears and exhibits double absorption characteristics in the visible light region (the absorption curve trough appears between 500 and 800 nm); as the voltage increases further, the absorption curve of the film in the visible light region has no obvious absorption peak.

[0065] Figure 4 and Figure 5The optical contrast and cycling stability of the film at the maximum absorption peak were demonstrated. The results showed that the HWB-OH electrochromic film exhibited an optical contrast of 47.01% in the 719 nm wavelength range, with a coloring time of 0.81 s and a fading time of 0.32 s. After 1000 cycles at step voltages of 0V and 1.0V, the material retained 85.19% of its initial optical contrast.

[0066] (3) Colorimetric test of HWB-OH electrochromic thin film

[0067] like Figure 6 As shown, at 0 V, the HWB-OH electrochromic film appears cyan, and as the voltage increases, the film eventually becomes transparent.

[0068] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A cyan-transparent electrochromic polymer, characterized in that, The structure of the cyan-transparent electrochromic polymer is shown in formula (I): （Ⅰ） Where x and y are independently selected from any integer from 5 to 25.

2. The method for preparing the cyan-transparent electrochromic polymer according to claim 1, characterized in that, The process includes the following steps: In a protective atmosphere, 6,6'-(2,6-dibromo-4H-cyclopenta[2,1-b:3,4-b']dithiophene-4,4-diyl)bis(hexyl-1-ol), 2,6-di(trimethyltin)-4,4-di(2-ethylhexyl)-dithiophenecyclopentadiene, and 4,7-dibromobenzo[c][1,2,5]thiadiazole react in the presence of a catalyst to prepare a blue-transparent electrochromic polymer.

3. The method for preparing the cyan-transparent electrochromic polymer according to claim 2, characterized in that, The catalysts are Pd2(dba)3 and P(o-tol)3.

4. The method for preparing the cyan-transparent electrochromic polymer according to claim 2 or 3, characterized in that, The molar ratio of 6,6'-(2,6-dibromo-4H-cyclopentano[2,1-b:3,4-b']dithiophene-4,4-diyl)bis(hexyl-1-ol) and 4,7-dibromobenzo[c][1,2,5]thiadiazole is 1:3~5.

5. The method for preparing the cyan-transparent electrochromic polymer according to claim 4, characterized in that, The molar ratio of 6,6'-(2,6-dibromo-4H-cyclopentano[2,1-b:3,4-b']dithiophene-4,4-diyl)bis(hexyl-1-ol) and 2,6-di(trimethyltin)-4,4-di(2-ethylhexyl)-dithiophenecyclopentadiene is 1:4~6.

6. The method for preparing the cyan-transparent electrochromic polymer according to claim 3 or 5, characterized in that, The molar ratio of Pd2(dba)3 to 6,6'-(2,6-dibromo-4H-cyclopentano[2,1-b:3,4-b']dithiophene-4,4-diyl)bis(hexyl-1-ol) is 0.01~0.1:

1.

7. The method for preparing the cyan-transparent electrochromic polymer according to claim 6, characterized in that, The molar ratio of P(o-tol)3 to 6,6'-(2,6-dibromo-4H-cyclopentano[2,1-b:3,4-b']dithiophene-4,4-diyl)bis(hexyl-1-ol) is 0.01~0.1:

1.

8. The method for preparing the cyan-transparent electrochromic polymer according to claim 5 or 7, characterized in that, The reaction is carried out at a temperature of 100-120°C for 15-17 hours.

9. The method for preparing the cyan-transparent electrochromic polymer according to claim 8, characterized in that, The reaction requires post-processing, which involves mixing the reacted solution with methanol and then filtering the mixture. The resulting filter cake is then extracted and the solvent is removed to obtain a cyan-transparent electrochromic polymer.

10. The application of the cyan-transparent electrochromic polymer of claim 1 in the preparation of electronic shelf labels.

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