Monomer, polymer, preparation method of monomer and polymer, and application of monomer and polymer in electrochromic material

Abstract

The invention discloses a monomer, a polymer, a preparation method thereof and application of the monomer and the polymer in an electrochromic material. Relates to the technical field of electrochromic materials. The monomer has the following specific structural formula: # imgabs0, in the formula, R is selected from alkyl with the carbon atom number of C1-C18, aryl or substituted aryl; d is selected from thiophene or 3, 4-ethylenedioxythiophene; and pi is selected from any one of the following structures: # imgabs 1 #. The monomer disclosed by the invention is an electrochromic monomer which is low in driving voltage, high in contrast ratio, short in switching time and good in stability.

Description

Technical Field

[0001] The present invention relates to the technical field of electrochromic materials, and particularly to a monomer, a polymer, a preparation method thereof, and an application in electrochromic materials. Background Art

[0002] Electrochromism (EC) refers to the phenomenon that the color, absorbance, and transmittance of a material change reversibly under the action of an electric field. Materials with electrochromic properties are widely used in fields such as smart windows, electronic displays, and wearable devices, and have become one of the research hotspots in the fields of optoelectronics, materials science, and intelligent technology in recent years. Electrochromic materials can rapidly change color under voltage drive and can maintain good stability during repeated operations, which provides a theoretical basis and technical support for various applications such as intelligent dimming, reflective optics, and intelligent visual display.

[0003] With the continuous development of green buildings, energy conservation, and intelligent systems, the research on electrochromic materials has gradually progressed towards high performance, low energy consumption, and multi-functionality. Among them, electrochromic conjugated polymers, as a class of materials with remarkable optoelectronic properties, have attracted extensive attention due to their excellent electrochromic characteristics. Compared with traditional metal oxide or inorganic semiconductor electrochromic materials, conjugated polymers have a broader absorption spectrum, covering the absorption range from ultraviolet light, visible light to the infrared region, and have a higher optical contrast and faster color switching speed. Therefore, they show broad prospects in various application fields such as smart windows, solar mirrors, anti-glare mirrors, smart displays, and wearable devices.

[0004] The working principle of electrochromic conjugated polymers involves an oxidation-reduction process. Essentially, it is to regulate the oxidation state or reduction state of the polymer through voltage, causing changes in the electron cloud in the polymer main chain, thereby leading to changes in its optical properties. When a voltage is applied, electrons are injected or removed from the electrochromic conjugated polymer, and these processes are respectively called p-doping (oxidation) and n-doping (reduction). By removing or injecting electrons, charge carriers such as polarons and bipolarons in the polymer molecular chain are excited or disappear, ultimately resulting in changes in the color and transmittance of the polymer.

[0005] However, despite the significant electrochromic effect of electrochromic conjugated polymers, their performance in practical applications still faces some challenges. First, the driving voltage of electrochromic conjugated polymers is relatively high. Usually, dozens of volts or even higher voltages are required to achieve color changes, which will cause additional energy consumption in some application scenarios and reduce the overall efficiency of the intelligent system. Second, the optical contrast of these materials still cannot be compared with that of inorganic electrochromic materials. Although their broad absorption spectral range enables them to have good contrast in certain specific wavelength bands, their overall performance still needs to be improved in practical applications to meet more stringent requirements.

[0006] In addition, the switching speed and stability of electrochromic conjugated polymers are also problems that need to be solved urgently. Although some new conjugated polymers have improved switching speed, there are still problems such as long reaction time and slow response time, which limit their application in fast-switching intelligent displays and dimming systems. During long-term use, electrochromic conjugated polymers may degrade due to repeated redox processes, resulting in a gradual decline in their performance, which is also one of the main bottlenecks in the application of electrochromic conjugated polymers currently.

[0007] In addition, the poor solubility of conjugated polymers often affects their subsequent processing and applications. Many traditional conjugated polymers are prone to aggregation into macromolecules due to the strong intermolecular forces between polymer chains, resulting in poor solubility and difficulty in further processing or forming thin films, which limits their application in large-scale production.

[0008] Therefore, there is an urgent need to provide an electrochromic polymer with a low driving voltage, high contrast, fast switching time, and good stability. Summary of the Invention

[0009] The purpose of the present invention is to provide an electrochromic polymer monomer and polymer with a low driving voltage, high contrast, fast switching time, and good stability.

[0010] The first aspect of the present invention lies in:

[0011] Providing a monomer.

[0012] The second aspect of the present invention lies in:

[0013] Providing a preparation method of the monomer.

[0014] The third aspect of the present invention lies in:

[0015] Providing a polymer.

[0016] The present invention also proposes a preparation method of the polymer.

[0017] The present invention also proposes an electrochromic material.

[0018] The present invention also provides an electrochromic device.

[0019] Specifically, the technical solution adopted according to the first aspect of the present invention is as follows:

[0020] A monomer, with the following structural formula:

[0021]

[0022] Wherein, R is selected from alkyl, aryl or substituted aryl with 1 to 18 carbon atoms;

[0023] D is selected from thiophene or 3,4-ethylenedioxythiophene;

[0024] π is selected from any of the following structures:

[0025]

[0026] According to an embodiment of the present invention, at least one of the following advantages or beneficial effects is achieved by one of the technical solutions in the above technical solution:

[0027] The monomer of the present invention uses benzo[1,2-b:4,5-b']dithiophene-4,8-dione with good planarity as the acceptor, thiophene or 3,4-ethylenedioxythiophene and its dimer as the π-bridge, and thiophene derivatives as the donor. Through the selection of groups, a unique D-π-A-π-D structure is formed, so that the monomer is an electrochromic monomer with low driving voltage, high contrast, fast switching time and good stability.

[0028] For the monomer of the present invention, after being prepared into a polymer, the transmittance change of the polymer in the neutral state can reach 1.2 - 5.9%, and the transmittance in the doped state can reach 3.1 - 6.2%, indicating that the polymer has a good short-term memory effect. Since the short-term memory is used to measure the stability of the polymer when a voltage is applied for a short time, the polymer based on the monomer of the present invention has excellent stability.

[0029] In addition, for the monomer of the present invention, after being prepared into a polymer, the polymer exhibits good optical contrast, high coloring efficiency and excellent optical stability, and can reach an optical contrast of 33.24 - 50.93% in different wavelength ranges.

[0030] According to an embodiment of the present invention, in the monomer structure of the present invention, 3,4-ethylenedioxythiophene, as a strong electron-donating group, can reduce the initial oxidation potential of the monomer, reduce the optical band gap of the conjugated polymer, and improve the electrochromic performance. Benzo[1,2-b:4,5-b']dithiophene-4,8-dione has strong electron-withdrawing ability, which can enhance the intramolecular charge transfer of the D-A-D conjugated polymer.

[0031] According to an embodiment of the present invention, R is selected from alkyl, aryl, and / or substituted aryl having 4 to 15 carbon atoms.

[0032] According to an embodiment of the present invention, the substituted aryl includes aryl substituted by halogen, nitro, amino, hydroxyl, or carboxyl.

[0033] According to an embodiment of the present invention, D is thiophene, and π is selected from the structures containing thiophene among Structure I to Structure VI. In the monomer structure of the present invention, the thiophene group is more beneficial to improving the coloring efficiency of the polymer prepared from this monomer than the 3,4-ethylenedioxythiophene group.

[0034] According to an embodiment of the present invention, when both π and D are thiophene groups, the number of thiophene groups is less than 6, which is more beneficial to improving the coloring efficiency of the polymer prepared from this monomer. Preferably, when both π and D are thiophene groups, when the number of thiophene groups is 4, the corresponding coloring efficiency is optimal.

[0035] According to an embodiment of the present invention, π is selected from one of Structure I, Structure II, and Structure IV. In the monomer structure of the present invention, excessive extension of the conjugated structure has an adverse effect on the coloring efficiency of the polymer prepared from this monomer. For example, when D is 3,4-ethylenedioxythiophene and π is selected from Structure V, the coloring efficiency is worse than when selected from Structure IV.

[0036] Preferably, in the monomer structure of the present invention, when both D and π are thiophene groups, the combination of four thiophene groups is more beneficial to improving the coloring efficiency. For the polymer prepared from this monomer, the coloring efficiency can reach 570.84 cm2 C -1 , which is 519.58% higher than that of the existing polymer (the coloring efficiency is 92.19 cm 2 C-1 ).

[0037] Specifically, the technical solution adopted in the second aspect of the present invention is as follows:

[0038] A method for preparing the monomer, comprising the following steps:

[0039] Under a protective gas atmosphere, compound A, a catalyst, tributyl(2,3-dihydro[3,4-b][1,4]dioxin-5-yl)stannane or tributyl(2-thienyl)stannane are mixed in a solvent, and through reaction, the monomer is obtained;

[0040] The structural formula of the compound A is:

[0041]

[0042] Among them, X is a halogen group.

[0043] The function of tributyl(2,3-dihydro[3,4-b][1,4]dioxin-5-yl)stannane or tributyl(2-thienyl)tin is to connect the EDOT group in compound a and the thiophene group in tributyl(2,3-dihydro[3,4-b][1,4]dioxin-5-yl)stannane or tributyl(2-thienyl)tin, serving as a donor to generate the monomer with low driving voltage, high contrast, fast switching time and good stability.

[0044] According to an embodiment of the present invention, the mass ratio of the compound A to the tributyl(2,3-dihydro[3,4-b][1,4]dioxin-5-yl)stannane is 0.1 - 0.12:0.1 - 0.5.

[0045] According to an embodiment of the present invention, the mass ratio of the compound A to the catalyst is 0.1 - 0.12:0.003 - 0.00625.

[0046] According to an embodiment of the present invention, the catalyst includes a palladium catalyst and dimethylformamide.

[0047] The use of the palladium catalyst can ensure the reaction between the compound A and the tributyl(2,3-dihydro[3,4-b][1,4]dioxin-5-yl)stannane.

[0048] The use of dimethylformamide can improve the reaction efficiency and product purity as a catalyst.

[0049] According to an embodiment of the present invention, the solvent includes at least one of N,N-dimethylformamide, toluene, benzene, acetone, and ethanol.

[0050] According to an embodiment of the present invention, the protective gas includes at least one of nitrogen or noble gases.

[0051] According to an embodiment of the present invention, the temperature of the reaction is 70 - 130 °C. Preferably, the temperature of the reaction is 90 - 120 °C.

[0052] According to an embodiment of the present invention, the reaction time is 8 - 24 hours. Preferably, the reaction time is 12 - 24 hours.

[0053] According to an embodiment of the present invention, the reaction is a Stille coupling reaction.

[0054] According to an embodiment of the present invention, after the Stille coupling reaction, it further includes a washing step.

[0055] According to an embodiment of the present invention, the reagent used for washing includes a sodium chloride solution.

[0056] According to an embodiment of the present invention, after the washing, a step of chromatographic separation and purification is further included.

[0057] According to an embodiment of the present invention, the separation column used for chromatographic separation and purification is a silica gel column.

[0058] Another aspect of the present invention further provides a polymer. The raw materials of the polymer include the monomers as described in the embodiments of the first aspect above. Since this application adopts all the technical solutions of the above monomers, it has at least all the beneficial effects brought by the technical solutions of the above embodiments.

[0059] According to an embodiment of the present invention, the structural formula of the polymer is as shown in formula (III):

[0060]

[0061] wherein, n is greater than 0;

[0062] Among them, in the structural formula of the polymer, the selections of R, π and D are the same as those in the R, π and D in the monomer.

[0063] According to the embodiments of the present invention, one of the technical solutions in the technical solutions has at least the following advantages or beneficial effects:

[0064] The polymer of the present invention has good electrochromic properties, can achieve reversible color switching at a low driving voltage, and under the action of an applied voltage, a stable reversible color change from dark blue to blue-gray, or from blue-black to gray can be observed visually, and it has good electrochromic properties such as high contrast, high coloring efficiency, and fast switching time, and has great application prospects in the commercial electrochromic field.

[0065] In addition, in the structure of the polymer of the present invention, benzodithiophene-4,8-dione has good planarity and strong electron-withdrawing ability, which makes the conjugated degree of the polymer high and the quality of the film formed by the polymer good, thereby further promoting the high contrast, fast switching time and good stability of the polymer.

[0066] According to an embodiment of the present invention, n represents the average degree of polymerization, and n is 10 - 5000.

[0067] According to an embodiment of the present invention, n is 10 - 3000.

[0068] According to an embodiment of the present invention, the method for preparing the polymer comprises the following steps: mixing an electrolyte and the monomer in a solvent to obtain an electrolyte solution, adding the electrolyte solution into an electrode system, and depositing the polymer through an electrochemical polymerization reaction.

[0069] According to an embodiment of the present invention, the electrolyte comprises at least one of tetrabutylammonium hexafluorophosphate, tetrabutylammonium tetrafluoroborate, and lithium perchlorate.

[0070] According to an embodiment of the present invention, adding the electrolyte solution into the electrode system comprises the following steps: adding the electrolyte solution into an electrolytic cell of a three-electrode system.

[0071] According to an embodiment of the present invention, the electrochemical polymerization reaction comprises performing the electrochemical polymerization reaction on the working electrode of a three-electrode system by using a constant potential method.

[0072] According to an embodiment of the present invention, for the electrochemical polymerization reaction, the polymerization potential is 0.3 - 1.05 V, and the polymerization time is 30 - 80 s.

[0073] According to an embodiment of the present invention, for the electrochemical polymerization reaction, the polymerization potential is 0.3 V, 0.45 V, 0.5 V, 0.65 V, 0.7 V, 0.85 V, 0.95 V, or 1.05 V.

[0074] According to an embodiment of the present invention, for the electrochemical polymerization reaction, the polymerization time is 30 s, 40 s, 45 s, 50 s, 55 s, 60 s, or 80 s.

[0075] According to an embodiment of the present invention, for the electrochemical polymerization reaction, the polymerization potential is 0.95 V, and the polymerization time is 50 s.

[0076] According to an embodiment of the present invention, for the electrochemical polymerization reaction, the polymerization potential is 0.45 V, and the polymerization time is 45 s.

[0077] According to an embodiment of the present invention, for the electrochemical polymerization reaction, the polymerization potential is 1.05 V, and the polymerization time is 60 s.

[0078] According to an embodiment of the present invention, for the electrochemical polymerization reaction, the polymerization potential is 0.65 V, and the polymerization time is 60 s.

[0079] According to an embodiment of the present invention, for the electrochemical polymerization reaction, the polymerization potential is 0.3 V, and the polymerization time is 30 s.

[0080] According to an embodiment of the present invention, in the electrochemical polymerization reaction, the polymerization potential is 0.5 V and the polymerization time is 40 s.

[0081] According to an embodiment of the present invention, in the electrochemical polymerization reaction, the polymerization potential is 0.7 V and the polymerization time is 80 s.

[0082] According to an embodiment of the present invention, in the three - electrode system, an Ag / AgCl electrode is used as the reference electrode, a platinum wire is used as the counter electrode, and a Pt / ITO conductive glass is used as the working electrode.

[0083] According to an embodiment of the present invention, the potentiostatic method includes the galvanostatic method or cyclic voltammetry.

[0084] According to an embodiment of the present invention, in the electrolyte, the solvent includes at least one of dichloromethane (CH2Cl2), chloroform (CHCl3), or acetonitrile (MeCN).

[0085] According to an embodiment of the present invention, in the electrolyte, the concentration of the monomer is 1 - 12 mmol·L -1 . Preferably, the concentration of the monomer is 1 - 10 mmol·L -1 .

[0086] According to an embodiment of the present invention, in the electrolyte, the concentration of the electrolyte is 0.05 - 0.3 mol·L -1 . Preferably, the concentration of the electrolyte is 0.06 - 0.1 mol·L -1 .

[0087] According to an embodiment of the present invention, the electrochemical polymerization reaction has the following reaction process:

[0088]

[0089] Another aspect of the present invention further provides an electrochromic material, and the electrochromic material includes the polymer described above.

[0090] Another aspect of the present invention further provides an electrochromic device, and the electrochromic device includes the electrochromic material described above.

[0091] According to an embodiment of the present invention, the electrochromic device includes at least one of a display, electrochromic glass, a smart window, or a rearview mirror.

[0092] According to an embodiment of the present invention, the smart window has great advantages in energy conservation, emission reduction and comfort. Through the electrochromic regulation of the polymer described in the present invention, the dynamic adjustment of the light transmittance and heat transmittance of the window can be realized, so as to effectively control the indoor light intensity and temperature, and reduce the energy consumption of air conditioning and lighting systems.

[0093] According to an embodiment of the present invention, the lens used in the rearview mirror is an anti-glare lens. Through the electrochromic regulation of the polymer described in the present invention, the automatic adjustment of light can be realized, improving visual comfort, and it is especially suitable for occasions such as driver glasses and photographic lenses.

[0094] Other features and advantages of the present invention will be described in the subsequent specification, and, in part, will be obvious from the specification, or will be understood by implementing the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0095] The above and / or additional aspects and advantages of the present invention will become obvious and easy to understand from the description of the embodiments in conjunction with the following drawings, wherein:

[0096] Figure 1 Test chart of the electrochromic performance of the polymer prepared for Example 1.

[0097] Figure 2 Test chart of the electrochromic performance of the polymer prepared for Example 2.

[0098] Figure 3 Test chart of the electrochromic performance of the polymer prepared for Example 3.

[0099] Figure 4 Test chart of the electrochromic performance of the polymer prepared for Example 4.

[0100] Figure 5 Test chart of the electrochromic performance of the polymer prepared for Example 5.

[0101] Figure 6 Test chart of the electrochromic performance of the polymer prepared for Example 6.

[0102] Figure 7 Test chart of the electrochromic performance of the polymer prepared for Example 7.

[0103] Figure 8 Test chart of the electrochromic performance of the polymer prepared for Example 8.

[0104] Figure 9 Test chart of the electrochromic performance of the polymer prepared for the comparative example. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0105] The terms "preferably", "more preferably", etc. in the present invention refer to embodiments of the present invention that can provide certain beneficial effects under certain circumstances. However, in the same circumstances or other circumstances, other embodiments may also be preferred. In addition, the description of one or more preferred embodiments does not imply that other embodiments are not available, nor is it intended to exclude other embodiments from the scope of the present invention.

[0106] When a numerical range is disclosed herein, the above range is considered continuous and includes the minimum and maximum values of the range, as well as each value therebetween. Further, when the range refers to integers, it includes each integer between the minimum and maximum values of the range. In addition, when multiple ranges are provided to describe features or characteristics, the ranges may be combined. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all sub-ranges subsumed therein.

[0107] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the scope of the present invention.

[0108] In order to make those skilled in the art more clearly understand the technical solutions described in the present invention, the following embodiments are listed for illustration. There are many data parameters in the laboratory stage of electrochromic materials to evaluate their performance. For example, ultraviolet absorbance, transmittance, coloring efficiency, response time, and open-circuit memory effect are all important parameters for evaluating whether the material is suitable for application in real life.

[0109] Ultraviolet absorbance refers to the change in the performance of the polymer during the processes of doping and dedoping of the material, which macroscopically manifests as a change in absorbance in the ultraviolet-visible light spectrum. With different applied voltages, the doping degree of the polymer is different, and the chromaticity and brightness of the film will also change accordingly. However, this performance can only qualitatively analyze and test whether the material has electrochromic performance, rather than subjectively judge and quantitatively analyze the quality of the electrochromic performance of the material.

[0110] Transmittance refers to the change in the optical performance of the material under the condition of an applied voltage, and the specific change in the light transmittance of the material is quantitatively detected in an ultraviolet spectrometer, denoted by ΔT.

[0111] The coloring efficiency is to quantitatively analyze the amount of charge flowing through the polymer when the material changes color and transmittance under an applied voltage, which also indicates the energy loss of the material during application. The higher the coloring efficiency, the higher the energy utilization rate of the material and the more energy loss is saved. The coloring efficiency, i.e., the CE value, is calculated by the ratio of the change in optical density (ΔOD) during the doping and dedoping processes of the material and the charge amount Qd flowing through the potential area of the material. The calculation formula is as follows:

[0112] CE = ΔOD / Qd;

[0113] Among them, ΔOD is the logarithm of the ratio of transmittance values of the material in different states at a specified wavelength. The calculation formula is as follows:

[0114] ΔOD = log(Tox / Tred);

[0115] Tox and Tred are the transmittance values of the material in the oxidized state and the reduced state, respectively.

[0116] The response time refers to the time required for the transmittance of the material to change by 95% in the transmittance-time curve when the potential of the square-wave voltage changes and causes the transmittance of the material to change under the condition of an applied voltage. The shorter the time, the faster the conversion time of the material, which better meets the requirements in practical applications. However, this value is related to various factors. The conductivity of the substrate, the self-performance of the material, the conductivity of the system, the concentration of free ions in the system, and the moving speed of the ions have a great impact on the conversion time. And in applications, different working environments also have different requirements for the conversion time.

[0117] The memory effect refers to the performance of the material to maintain its doped or dedoped state to a certain extent under the condition of an open-circuit applied voltage. After applying a fully doped voltage or a fully dedoped voltage to the material and then disconnecting the applied voltage, observe the time-transmittance curve of the material in the ultraviolet spectrometer. Normally, due to the absence of binding of the doped ions in the material under the open-circuit condition, they will automatically dissociate into the solution in the system, resulting in changes in the color and transmittance of the material, thereby indicating the change degree of the memory effect of the material.

[0118] Unless otherwise specified, the raw materials, reagents or devices used in the following examples can all be obtained from conventional commercial channels or can be obtained by existing known methods.

[0119] The polymer is obtained by an electropolymerization method using ETBD, EEBD, TTBD, TEBD, EEEBD, TTTBD, TEEBD, and ETTBD as monomers respectively at different constant potential values. The benzodithiophene-4,8-dione polymer film has good electrochromic properties, enabling reversible color switching and high contrast changes at low driving voltages, and thus has great application prospects in the commercial electrochromic field.

[0120] In the examples and comparative examples, TOL is toluene and DMF is dimethylformamide.

[0121] Example 1

[0122] A monomer (denoted as ETBD), with the following specific structural formula:

[0123]

[0124] The method for preparing the above monomer includes the following steps:

[0125]

[0126] Specifically:

[0127] Under a nitrogen atmosphere, 1,3-bis(5-bromothiophen-2-yl)-5,7-bis(2-ethylhexyl)-4H,8H-benzo[1,2-c:4,5-c']dithiophene-4,8-dione (0.08 g, 0.105 mmol), tributyl(2,3-dihydro[3,4-b][1,4]dioxin-5-yl)stannane (0.114 g, 0.263 mmol), and the catalyst Pd(PPh3)4 (0.005 g, 0.0042 mmol) are placed in a 250 mL single-neck flask, TOL (32 mL) and DMF (8 mL) are added and stirred evenly, and the mixture is heated to 120 °C for reflux reaction for 48 hours. After the reaction system is cooled, the product is obtained;

[0128] The obtained product is poured into saturated brine, extracted 5 times with dichloromethane, the organic layer is washed with water, and then the solvent is removed by vacuum distillation and rotary evaporation. It is separated by a silica gel chromatography column, and the eluent is a mixture of dichloromethane and petroleum ether in a volume ratio of 1:3. 35.4 mg of a brown-red blocky product (monomer) is obtained by purification, and the yield is 37.9%.

[0129] The nuclear magnetic resonance hydrogen spectrum characterization results of the product (monomer) are as follows: 11H NMR (400 MHz, Chloroform-d) δ 7.71 (d, J = 4.1 Hz, 2H), 7.16 (s, 2H), 6.23 (s, 2H), 4.26 (d, J = 46.6 Hz, 8H), 3.30 (dd, J = 15.5, 6.8 Hz, 2H), 3.22 (d, J = 6.5 Hz, 2H), 1.71 (s, 2H), 1.36–1.14 (m, 19H), 0.93–0.73 (m, 13H).

[0130] A polymer (denoted as P(ETBD)), the structural formula is as follows:

[0131]

[0132] To prepare the above polymer, the following steps are included:

[0133]

[0134] Specifically:

[0135] Electrochemical polymerization is used to prepare the polymer. The electrochemical polymerization is carried out in a one-compartment three-electrode system. The working electrode is ITO conductive glass, the counter electrode is a platinum sheet, and the reference electrode is an Ag / AgCl electrode (a silver wire forms an AgCl coating on the surface by electrolysis at a constant potential of 1.5 V for 100 s in a 6 moL / L HCl solution).

[0136] Using 10 mL of dichloromethane as the electrolyte, the monomer (ETBD) (0.01 moL / L) as the polymerization monomer, and tetrabutylammonium hexafluorophosphate (0.1 moL / L) as the supporting electrolyte, polymerization is carried out by the constant potential method. The polymerization potential is 0.95 V, and the polymerization time is 50 s. The polymer film obtained by electrodeposition is rinsed with acetonitrile to remove the electrolyte solution and the oligomers produced in the polymer.

[0137] Example 2

[0138] A monomer (denoted as EEBD), the specific structural formula is as follows:

[0139]

[0140] The method for preparing the above monomer includes the following steps:

[0141]

[0142] Specifically:

[0143] Under a nitrogen atmosphere, 1,3-bis(7-bromo-2,3-dihydrothieno[3,4-b][1,4]dioxin-5-yl)-5,7-bis(2-ethylhexyl)-4H,8H-benzo[1,2-c:4,5-c']dithiophene-4,8-dione (0.238 g, 0.27 mmol), tributyl(2,3-dihydro[3,4-b][1,4]dioxin-5-yl)stannane (0.28 g), and the catalyst Pd(PPh3)4 (0.03 g, 0.027 mmol) were placed in a 250 mL single-necked flask. TOL (toluene, 32 mL) and DMF (N,N-dimethylacetamide, 8 mL, the volume ratio of TOL to DMF was 4:1) were added and stirred evenly. The mixture was heated to 120 °C and refluxed for 48 hours. After the reaction system was cooled, the product was obtained;

[0144] The product was poured into saturated brine and extracted 4 times with dichloromethane. Then water was added to wash the organic layer. After that, the solvent was removed by vacuum distillation and rotary evaporation, and separation was carried out using a silica gel chromatography column. The eluent was a mixture of dichloromethane and petroleum ether in a volume ratio of 1:5. 73.5 mg of a red powder product (monomer) was obtained by purification, and the yield was 27%.

[0145] The characterization results of the 1H NMR spectrum of the product (monomer) were as follows: 1 H NMR (400 MHz, Chloroform-d) δ 6.27 (s, 2H), 4.25 (dd, J = 49.1, 4.5 Hz, 16H), 3.37–3.09 (m, 4H), 1.73 (s, 2H), 1.41–1.09 (m, 19H), 0.83 (dt, J = 26.7, 7.2 Hz, 13H).

[0146] A polymer (denoted as P(EEBD)), the structural formula is as follows:

[0147]

[0148] To prepare the above polymer, the following steps are included:

[0149]

[0150] Specifically:

[0151] Electrochemical polymerization was used to prepare the polymer. The electrochemical polymerization was carried out in a one-compartment three-electrode system. The working electrode was ITO conductive glass, the counter electrode was a platinum sheet, and the reference electrode was an Ag / AgCl electrode (a silver wire was electrolyzed on the surface at a constant potential of 1.5 V for 100 s in a 6 moL / L HCl solution to form an AgCl coating).

[0152] Using 10 mL of dichloromethane as the electrolyte, EEBD (0.01 moL / L) as the monomer, and tetrabutylammonium hexafluorophosphate (0.1 moL / L) as the supporting electrolyte, electrochemical polymerization was carried out by the potentiostatic method. The polymerization potential was 0.45 V and the polymerization time was 45 s. The polymer P(EEBD) film electrodeposited on the surface of the ITO conductive glass was rinsed with acetonitrile to remove the electrolyte solution and the generated oligomers in the polymer.

[0153] Example 3

[0154] A monomer (denoted as TTBD), with the following specific structural formula:

[0155]

[0156] The method for preparing the above monomer includes the following steps:

[0157]

[0158] Specifically:

[0159] Under a nitrogen atmosphere, 1,3-bis(5-bromothiophen-2-yl)-5,7-bis(2-ethylhexyl)-4H,8H-benzo[1,2-c:4,5-c']dithiophene-4,8-dione (0.31 g, 0.416 mmol), tributyl(thiophen-2-yl)stannane (0.372 g, 0.998 mmol), and the catalyst Pd(PPh3)4 (0.048 g, 0.042 mmol) were placed in a 250 mL single-necked flask. TOL (toluene, 32 mL) and DMF (N,N-dimethylacetamide, 8 mL, the volume ratio of TOL to DMF is 4:1) were added and stirred evenly, and the mixture was heated to 120 °C and refluxed for 48 hours. After the reaction system was cooled, the product was obtained;

[0160] The product was poured into saturated brine, extracted 4 times with dichloromethane, and then the organic layer was washed with water. After that, the solvent was removed by vacuum distillation and rotary evaporation, and separation was carried out using a silica gel chromatography column. The eluent was formed by mixing dichloromethane and petroleum ether in a volume ratio of 1:5. 24.9 mg of the purified red powder product (monomer) was obtained, and the yield was 77.4%.

[0161] The 1H NMR characterization results of the product (monomer) are as follows: 11H NMR (400 MHz, Chloroform-d) δ 7.63 (d, J = 4.0 Hz, 2H), 7.22 (dd, J = 8.4, 4.3 Hz, 4H), 7.11 (d, J = 3.9 Hz, 2H), 7.03–6.95 (m, 2H), 3.26 (d, J = 7.0 Hz, 4H), 1.76–1.66 (m, 2H), 1.40–1.16 (m, 17H), 0.84 (dt, J = 21.3, 7.2 Hz, 12H).

[0162] A polymer (denoted as P(TTBD)), with the structural formula as follows:

[0163]

[0164] The preparation of the above polymer includes the following steps:

[0165]

[0166] Specifically:

[0167] Electrochemical polymerization is carried out in a one-compartment three-electrode system. The working electrode is ITO conductive glass, the counter electrode is a platinum sheet, and the reference electrode is an Ag / AgCl electrode (AgCl coating is formed on the surface of a silver wire by electrolysis at a constant potential of 1.5 V for 100 s in a 6 moL / L HCl solution).

[0168] Using 10 mL of dichloromethane as the electrolyte, TTBD (0.01 moL / L) as the monomer, and tetrabutylammonium hexafluorophosphate (0.1 moL / L) as the supporting electrolyte, electrochemical polymerization is carried out by the constant potential method. The polymerization potential is 1.05 V, and the polymerization time is 60 s. The polymer P(TTBD) film electrodeposited on the surface of ITO conductive glass is rinsed with acetonitrile to remove the electrolyte solution and the generated oligomers in the polymer.

[0169] Example 4

[0170] A monomer (denoted as TEBD), with the specific structural formula as follows:

[0171]

[0172] The method for preparing the above monomer includes the following steps:

[0173]

[0174] Specifically:

[0175] Under a nitrogen atmosphere, 1,3-bis(7-bromo-2,3-dihydrothieno[3,4-b][1,4]dioxin-5-yl)-5,7-bis(2-ethylhexyl)-4H,8H-benzo[1,2-c:4,5-c']dithiophene-4,8-dione (0.068 g, 0.077 mmol), tributyl(thiophen-2-yl)stannane (0.069 g, 0.185 mmol), and the catalyst Pd(PPh3)4 (0.07 g, in excess) were placed in a 250 mL single-necked flask. TOL (32 mL) and DMF (8 mL) were added and stirred evenly. The mixture was heated to 120 °C and refluxed for 48 hours. After the reaction system was cooled, the product was obtained;

[0176] The obtained product was poured into saturated brine and extracted 5 times with dichloromethane. Then water was added to wash the organic layer. After that, the solvent was removed by vacuum distillation and rotary evaporation, and separation was carried out using a silica gel chromatography column. The eluent was a mixture of dichloromethane and petroleum ether in a volume ratio of 1:5. 37.4 mg of a red-black powdery product (monomer) was obtained by purification, and the yield was 54.6%.

[0177] A polymer (denoted as P(TEBD)), with the structural formula as follows:

[0178]

[0179] To prepare the above polymer, the following steps are included:

[0180]

[0181] Specifically:

[0182] The above polymer was prepared by electrochemical polymerization. The electrochemical polymerization was carried out in a one-compartment three-electrode system. The working electrode was ITO conductive glass, the counter electrode was a platinum sheet, and the reference electrode was an Ag / AgCl electrode (a silver wire was electrolyzed on the surface at a constant potential of 1.5 V for 100 s in a 6 moL / L HCl solution to form an AgCl coating).

[0183] Using 10 mL of dichloromethane as the electrolyte, the monomer (TEBD) (0.01 moL / L) as the polymerization monomer, and tetrabutylammonium hexafluorophosphate (0.1 moL / L) as the supporting electrolyte, polymerization was carried out by the constant potential method. The polymerization potential was 0.65 V, and the polymerization time was 60 s. The polymer film obtained by electrodeposition was rinsed with acetonitrile to remove the electrolyte solution and the oligomers generated in the polymer.

[0184] Example 5

[0185] A monomer (denoted as EEEBD), with the specific structural formula as follows:

[0186]

[0187] A method for preparing the above monomer, comprising the following steps:

[0188]

[0189] Specifically:

[0190] Under a nitrogen atmosphere, 1,3-bis(7'-bromo-2,2',3,3'-tetrahydro-[5,5'-bithieno[3,4-b][1,4]dioxin]-7-yl)-5,7-bis(2-ethylhexyl)-4H,8H-benzo[1,2-c:4,5-c']dithiophene-4,8-dione (0.156 g, 0.134 mmol), tributyl(2,3-dihydro[3,4-b][1,4]dioxin-5-yl)stannane (0.139 g, 0.322 mmol), and the catalyst Pd(PPh3)4 (0.07 g, in excess) were refluxed for 48 hours. After the reaction system was cooled, the product was obtained;

[0191] The obtained product was poured into saturated brine, extracted 5 times with dichloromethane, then the organic layer was washed with water. After that, the solvent was removed by vacuum distillation and rotary evaporation, and separated by silica gel column chromatography. The eluent was a mixture of dichloromethane and petroleum ether in a volume ratio of 3:1. 26.4 mg of a black powdery product (monomer) was obtained by purification, and the yield was 15.3%.

[0192] The characterization result of the nuclear magnetic resonance hydrogen spectrum of the product (monomer) is as follows: 1 H NMR(400MHz,Chloroform-d)δ6.25(d,J=17.6Hz,2H),4.26(d,J=57.8Hz,24H),3.33(dd,J=14.9,7.5Hz,2H),3.15(dd,J=15.9,6.0Hz,2H),1.74(s,2H),1.41–1.20(m,16H),0.84(dt,J=28.6,7.2Hz,13H).

[0193] A polymer (denoted as P(EEEBD)), the structural formula is as follows:

[0194]

[0195] A method for preparing the above polymer, comprising the following steps:

[0196]

[0197] Specifically:

[0198] The above polymer is prepared by electrochemical polymerization, which is carried out in a one-compartment three-electrode system. The working electrode is ITO conductive glass, the counter electrode is a platinum sheet, and the reference electrode is an Ag / AgCl electrode (a silver wire is electrolyzed on the surface at a constant potential of 1.5 V for 100 s in a 6 moL / L HCl solution to form an AgCl coating).

[0199] Using 10 mL of dichloromethane as the electrolyte, the monomer (EEEBD) (0.01 moL / L) as the polymerization monomer, and tetrabutylammonium hexafluorophosphate (0.1 moL / L) as the supporting electrolyte, the polymerization is carried out by the constant potential method. The polymerization potential is 0.3 V, and the polymerization time is 30 s. The polymer film obtained by electrodeposition is rinsed with acetonitrile to remove the electrolyte solution and the oligomers generated in the polymer.

[0200] Example 6

[0201] A monomer (denoted as TTTBD), with the specific structural formula as follows:

[0202]

[0203] The method for preparing the above monomer includes the following steps:

[0204]

[0205] Specifically:

[0206] Under a nitrogen atmosphere, 1,3-bis(5'-bromo-[2,2'-bithiophen]-5-yl)-5,7-bis(2-ethylhexyl)-4H,8H-benzo[1,2-c:4,5-c'-]dithiophene-4,8-dione (0.3 g, 0.322 mmol), tributyl(thiophen-2-yl)stannane (0.289 g, 0.773 mmol), and the catalyst Pd(PPh3)4 (0.08 g, in excess) are placed in a 250 mL single-neck flask. TOL (32 mL) and DMF (8 mL) are added and stirred evenly, and the mixture is heated to 120 °C and refluxed for 48 hours. After the reaction system is cooled, the product is obtained;

[0207] The obtained product is poured into saturated brine, extracted 5 times with dichloromethane, and then the organic layer is washed with water. After that, the solvent is removed by vacuum distillation and rotary evaporation, and separated by a silica gel chromatography column. The eluent is a mixture of dichloromethane and petroleum ether in a volume ratio of 1:3. 239 mg of a black powdery product (monomer) is obtained by purification, and the yield is 80.3%.

[0208] The characterization results of the nuclear magnetic resonance hydrogen spectrum of the product (monomer) are as follows: 11H NMR (400 MHz, Chloroform-d) δ 7.63 (s, 2H), 7.18–6.89 (m, 12H), 3.26 (d, J = 7.1 Hz, 4H), 1.71 (s, 2H), 1.24 (d, J = 44.3 Hz, 18H), 0.85 (d, J = 20.4 Hz, 13H).

[0209] A polymer (denoted as P(TTTBD)) has the following structural formula:

[0210]

[0211] The preparation of the above polymer includes the following steps:

[0212]

[0213] Specifically:

[0214] The above polymer is prepared by electrochemical polymerization, which is carried out in a one-compartment three-electrode system. The working electrode is ITO conductive glass, the counter electrode is a platinum sheet, and the reference electrode is an Ag / AgCl electrode (a silver wire forms an AgCl coating on its surface by electrolysis at a constant potential of 1.5 V for 100 s in a 6 moL / L HCl solution).

[0215] Using 10 mL of dichloromethane as the electrolyte, monomer (TTTBD) (0.01 moL / L) as the polymerization monomer, and tetrabutylammonium hexafluorophosphate (0.1 moL / L) as the supporting electrolyte, polymerization is carried out by the constant potential method. The polymerization potential is 0.85 V, and the polymerization time is 55 s. The polymer film obtained by electrodeposition is rinsed with acetonitrile to remove the electrolyte solution and the generated oligomers in the polymer.

[0216] Example 7

[0217] A monomer (denoted as TEEBD) has the following specific structural formula:

[0218]

[0219] The method for preparing the above monomer includes the following steps:

[0220]

[0221] Specifically:

[0222] Under a nitrogen atmosphere, 1,3-bis(7'-bromo-2,2',3,3'-tetrahydro-[5,5'-bithieno[3,4-b][1,4]dioxin]-7-yl)-5,7-bis(2-ethylhexyl)-4H,8H-benzo[1,2-c:4,5-c']dithiophene-4,8-dione (0.064 g, 0.055 mmol), tributyl(thiophen-2-yl)stannane (0.049 g, 0.131 mmol), and the catalyst Pd(PPh3)4 (0.08 g, in excess) were placed in a 250 mL single-necked flask. TOL (32 mL) and DMF (8 mL) were added and stirred evenly. The mixture was heated to 120 °C and refluxed under condensation for 48 hours. After the reaction system was cooled, the product was obtained;

[0223] The obtained product was poured into saturated brine, extracted 5 times with dichloromethane, and then the organic layer was washed with water. After that, the solvent was removed by vacuum distillation and rotary evaporation, and separated by a silica gel chromatography column. The eluent was a mixture of dichloromethane and petroleum ether in a volume ratio of 1:2. 32.5 mg of a black powdery product (monomer) was obtained by purification, and the yield was 50.9%.

[0224] The 1H NMR characterization results of the product (monomer) were as follows: 1 H NMR (400 MHz, Chloroform-d) δ 7.18 (s, 2H), 7.14 (s, 2H), 6.95 (s, 2H), 4.33 (s, 16H), 3.24 (d, J = 64.9 Hz, 4H), 1.73 (s, 2H), 1.42–1.08 (m, 20H), 0.99–0.67 (m, 14H).

[0225] A polymer (denoted as P(TEEBD)), the structural formula is as follows:

[0226]

[0227] To prepare the above polymer, the following steps are included:

[0228]

[0229] Specifically:

[0230] The above polymer was prepared by electrochemical polymerization. The electrochemical polymerization was carried out in a one-compartment three-electrode system. The working electrode was ITO conductive glass, the counter electrode was a platinum sheet, and the reference electrode was an Ag / AgCl electrode (a silver wire was electrolyzed on the surface at a constant potential of 1.5 V for 100 s in a 6 moL / L HCl solution to form an AgCl coating).

[0231] Using 10 mL of dichloromethane as the electrolyte, monomer (TEEBD) (0.01 moL / L) as the polymerization monomer, tetrabutylammonium hexafluorophosphate (0.1 moL / L) as the supporting electrolyte, the polymerization was carried out by the potentiostatic method. The polymerization potential was 0.5 V and the polymerization time was 40 s. The polymer film obtained by electrodeposition was rinsed with acetonitrile to remove the electrolyte solution and the oligomers produced in the polymer.

[0232] Example 8

[0233] A monomer (denoted as ETTBD), with the specific structural formula as follows:

[0234]

[0235] The method for preparing the above monomer includes the following steps:

[0236]

[0237] Specifically:

[0238] Under a nitrogen atmosphere, 1,3-bis(5'-bromo-[2,2'-bithiophen]-5-yl)-5,7-bis(2-ethylhexyl)-4H,8H-benzo[1,2-c:4,5-c'-]dithiophene-4,8-dione (0.25 g, 0.269 mmol), tributyl(2,3-dihydro[3,4-b][1,4]dioxin-5-yl)stannane (0.279 g, 0.646 mmol), and the catalyst Pd(PPh3)4 (0.08 g, in excess) were placed in a 250 mL single-necked flask. TOL (32 mL) and DMF (8 mL) were added and stirred evenly, and the mixture was heated to 120 °C and refluxed for 48 hours. After the reaction system was cooled, the product was obtained;

[0239] The obtained product was poured into saturated brine, extracted 5 times with dichloromethane, then the organic layer was washed with water, and then the solvent was removed by vacuum distillation and rotary evaporation. It was separated by a silica gel chromatography column, and the eluent was formed by mixing dichloromethane and petroleum ether in a volume ratio of 1:4. 38.3 mg of a black powdery product (monomer) was obtained by purification, and the yield was 13.5%.

[0240] The 1H NMR characterization results of the product (monomer) are as follows: 11H NMR (400 MHz, Chloroform-d) δ 7.61 (d, J = 4.0 Hz, 2H), 7.11 (d, J = 3.8 Hz, 2H), 7.06 (d, J = 4.0 Hz, 4H), 6.17 (s, 2H), 4.33–4.14 (m, 8H), 3.24 (d, J = 7.0 Hz, 4H), 1.71 (s, 3H), 1.39–1.20 (m, 18H), 0.85 (dt, J = 21.0, 7.2 Hz, 13H).

[0241] A polymer (denoted as P(ETTBD)), with the structural formula as follows:

[0242]

[0243] To prepare the above polymer, the following steps are included:

[0244]

[0245] Specifically:

[0246] The above polymer is prepared by electrochemical polymerization, which is carried out in a one-compartment three-electrode system. The working electrode is ITO conductive glass, the counter electrode is a platinum sheet, and the reference electrode is an Ag / AgCl electrode (AgCl coating is formed on the surface of a silver wire by electrolysis at a constant potential of 1.5 V for 100 s in 6 moL / L HCl solution).

[0247] Using 10 mL of dichloromethane as the electrolyte, monomer (ETTBD) (0.01 moL / L) as the polymerization monomer, tetrabutylammonium hexafluorophosphate (0.1 moL / L) as the supporting electrolyte, the polymerization is carried out by the constant potential method. The polymerization potential is 0.7 V, and the polymerization time is 80 s. The polymer film obtained by electrodeposition is rinsed with acetonitrile to remove the electrolyte solution and the oligomers generated in the polymer.

[0248] Comparative Example

[0249] The difference between the comparative example and Example 1 is only that: in Comparative Example 1, 0.13 mmol of asymmetric 5,7-bis(5-bromothiophen-2-yl)-2,3-bis(2-ethylhexyl)benzo[1,2-b:4,5-c]dithiophene-4,8-dione is used as the acceptor to replace 1,3-bis(5-bromothiophen-2-yl)-5,7-bis(2-ethylhexyl)-4H,8H-benzo[1,2-c:4,5-c']dithiophene-4,8-dione in Example 1.

[0250] A monomer (denoted as ETTD), with the specific structural formula as follows:

[0251]

[0252] A method for preparing the above monomer, comprising the following steps:

[0253]

[0254] Specifically:

[0255] Under a nitrogen atmosphere, 5,7-bis(5-bromothiophen-2-yl)-2,3-bis(2-ethylhexyl)benzo[1,2-b:4,5-c']dithiophene-4,8-dione (0.1 g, 0.13 mmol), tributyl(2,3-dihydro[3,4-b][1,4]dioxin-5-yl)stannane (0.2 g, in excess), and the catalyst Pd(PPh3)4 (0.006 g, 0.0052 mmol) were placed in a 250 mL single-necked flask, TOL (32 mL) and DMF (8 mL) were added and stirred evenly, heated to 120 °C and refluxed for 48 hours. After the reaction system was cooled, the product was obtained;

[0256] It was poured into saturated brine, extracted with dichloromethane 4-5 times, a small amount of water was added to wash the organic layer, and then the solvent was removed by vacuum distillation and rotary evaporation. It was separated by a silica gel chromatography column, and the eluent was (DCM:PE = 1:5). 45 mg of a black block product was purified, and the yield was 38.9%.

[0257] The nuclear magnetic 1 The 1H NMR spectrum data of the product is as follows: 1 1H NMR (400 MHz, Chloroform-d) δ 7.79 (dd, J = 21.4, 4.1 Hz, 2H), 7.17 (t, J = 3.5 Hz, 2H), 6.24 (s, 2H), 4.35–4.19 (m, 8H), 2.86 (dq, J = 38.0, 6.6 Hz, 2H), 2.68 (d, J = 7.1 Hz, 2H), 1.59 (dd, J = 12.8, 6.1 Hz, 2H), 1.35–1.16 (m, 19H), 0.84 (ddd, J = 19.3, 12.2, 7.0 Hz, 13H).

[0258] A polymer (denoted as P(ETTD)), the structural formula is as follows:

[0259]

[0260] A method for preparing the above polymer, comprising the following steps:

[0261]

[0262] Specifically:

[0263] The polymer was prepared by electrochemical polymerization, which was carried out in a one-compartment three-electrode system. The working electrode was ITO conductive glass, the counter electrode was a platinum sheet, and the reference electrode was an Ag / AgCl electrode (AgCl coating was formed on the surface of a silver wire by electrolysis at a constant potential of 1.5 V for 100 s in 6 moL / L HCl solution).

[0264] Using 10 mL of dichloromethane as the electrolyte, the monomer (ETTD) (0.01 moL / L) as the polymerization monomer, and tetrabutylammonium hexafluorophosphate (0.1 moL / L) as the supporting electrolyte, polymerization was carried out by the constant potential method. The polymerization potential was 0.85 V, and the polymerization time was 40 s. The polymer film obtained by electrodeposition was rinsed with acetonitrile to remove the electrolyte solution and the generated oligomers in the polymer.

[0265] Performance test:

[0266] The electrochromic performance of the polymer (P(ETBD)) prepared in Example 1 was tested, and the test results are as Figure 1 follows. Specifically:

[0267] (1) The spectroelectrochemical diagram of the polymer P(ETBD) prepared in Example 1 in the MeCN-Bu4NPF6 (0.1 moL / L) system was tested, and the results are as Figure 1 shown in (a) of Figure 1 . In (a) of Figure 1 , Wavelength is the wavelength and Absorbance is the absorbance. As shown in (a) of

[0268] and combined with the naked-eye observation of the color change of the polymer, it can be seen that as the potential increases, the color of the polymer changes from blue-black to gray (it is blue-black in the fully de-doped state. Due to the good optical transmittance of the polymer P(ETBD), the optical transmittance has a great influence on the color change of the polymer. The polymer material can change from blue-black in the fully de-doped state to gray in the doped state, with a large color span). This is because the neutral polymer has an absorption peak in the ultraviolet region and the red region respectively. The color of the neutral polymer appears blue-black; after the polymer is oxidized, the absorption peaks in the ultraviolet region and the red region gradually weaken and finally disappear completely, and an absorption peak in the near-infrared region appears and gradually rises, and the color also changes to gray.

[0269] Table 1: Electrochromic parameters of the polymer P(ETBD)

[0270]

[0271] The optical transmittance of polymer P(ETBD) was studied by chronoabsorption method at wavelengths of 1100 nm, 830 nm, 630 nm and 430 nm. During the experiment, the time interval of the potential step change was 5 s, as Figure 1 shown in (b). At the four wavelengths, the polymer showed good optical contrast and good optical stability. In particular, the optical contrast reached 50.93% at 830 nm. In addition, the optical transmittance had a great influence on the color change of the polymer. The polymer material could change from blue-black in the fully de-doped state to gray in the doped state.

[0272] (3) The short-term memory effect of polymer P(EBDD) was tested at a wavelength of 830 nm. Voltages of -0.3 V and 1.1 V were applied respectively, and the transmittance changes of the polymer in the neutral state and the doped state were recorded, as Figure 1 shown in (c). It was found that the transmittance change of the polymer in the neutral state was 4.3%, and the transmittance change in the doped state was 3.7%. This indicated that the polymer had a good short-term memory effect.

[0273] The electrochromic properties of the polymer (P(EEBD)) prepared in Example 2 were tested. The test results are as Figure 2 follows:

[0274] (1) The polymer thin film deposited on the surface of ITO conductive glass was placed in a three-electrode electrolytic cell. The electrolyte in the cell was a 0.1 moL / L solution of tetrabutylammonium hexafluorophosphate in dichloromethane. The working electrode was the ITO conductive glass with the polymer thin film attached, the counter electrode was a platinum sheet, and the reference electrode was an Ag / AgCl electrode. By using the potentiostatic method, the voltage applied to the working electrode was adjusted through an electrochemical workstation, and at the same time, the change trend of the absorption spectrum of the polymer thin film at different voltages was recorded with a UV-visible spectrometer, thus obtaining the spectroelectrochemical map of the polymer.

[0275] The spectroelectrochemical map of polymer P(EEBD) in the MeCN-Bu4NPF6 (0.1 moL / L, i.e., the acetonitrile solution of tetrabutylammonium hexafluorophosphate) system was tested, as Figure 2 ( Figure 2In "(Absorbance represents absorbance and Wavelength represents wavelength)", as shown in (a), and combined with the visual observation of the color change of the polymer, it can be seen that as the potential increases, the color of the polymer changes from dark blue to purple and finally to purple-gray (dark blue in the fully de-doped state). This is because the neutral polymer has an absorption peak in the violet and red regions, and the color of the neutral polymer appears dark blue; after the polymer is oxidized, the absorption peaks in the violet and red regions gradually weaken, the absorption peak in the near-infrared region appears and gradually rises, and the color also changes to purple and finally to purple-gray.

[0276] Use a UV-visible spectrophotometer to measure the transmittance of the polymer film in the doped and neutral states at a specific wavelength under a square-wave potential, so as to calculate the optical contrast, response time, etc.; the UV-visible spectrophotometer records the time-transmittance curve, and the electrochemical workstation records the time-current curve. The coloring efficiency can also be calculated based on these two curves.

[0277] (2) Test the transmittance-time curves of polymer P(EEBD) at 1100 nm, 990 nm, 660 nm, and 440 nm. The response time and coloring efficiency calculated from the time-transmittance curves are shown in Table 2 respectively.

[0278] As can be seen from Table 2, the polymer P(EEBD) has a fast response time and a general coloring efficiency.

[0279] Table 2: Electrochromic parameters of polymer P(EEBD)

[0280]

[0281] The chronoabsorption method was used to study the optical transmittance of polymer P(EEBD) at wavelengths of 1100 nm, 990 nm, 660 nm, and 440 nm. During the experiment, the time interval of the potential step change was 5 s, as Figure 2 ( Figure 2 In "(Transmittance represents transmittance and Time represents time)", as shown in (b). At the four wavelengths, the polymer P(EEBD) showed a certain optical contrast and good optical stability. In addition, the optical transmittance has a great influence on the color change of the polymer, and the polymer can change from dark blue in the fully de-doped state to purple in the doped state.

[0282] Using the constant potential method, a 10 s voltage was applied to the working electrode through an electrochemical workstation and a 2 s voltage was applied every 100 s. At the same time, a UV-visible spectrometer was used to record the change trend of the transmittance of the polymer in the oxidized and reduced states at the maximum absorption peak, and the short-term memory effect map of the polymer was obtained.

[0283] (3) The short-term memory effect of the polymer P(EEBD) was tested at a wavelength of 660 nm. Voltages of -0.5 V and 1.1 V were applied respectively, and the transmittance changes of the polymer in the neutral state and the doped state were recorded. As Figure 2 ( Figure 2 shown in (c) of

[0284] where "Transmittance" represents transmittance and "Time" represents time, it was found that the transmittance change of the polymer in the neutral state was 5.9%, and the transmittance change in the doped state was 3.1%. This indicates that the polymer has a good short-term memory effect. Figure 3 The electrochromic properties of the polymer (P(TTBD)) prepared in Example 3 were tested. The test results are as

[0285] (1) The polymer thin film deposited on the surface of ITO conductive glass was placed in a three-electrode electrolytic cell. The electrolyte in the electrolytic cell was a 0.1 moL / L solution of tetrabutylammonium hexafluorophosphate in dichloromethane. The working electrode was the ITO conductive glass with the polymer thin film attached, the counter electrode was a platinum sheet, and the reference electrode was an Ag / AgCl electrode. Using the potentiostatic method, the voltage applied to the working electrode was adjusted through an electrochemical workstation, and at the same time, the change trend of the absorption spectrum of the polymer thin film at different voltages was recorded using a UV-visible spectrometer, thus obtaining the spectroelectrochemical spectrum of the polymer.

[0286] The spectroelectrochemical diagram of the polymer P(TTBD) in the MeCN-Bu4NPF6 (0.1 moL / L, that is, an acetonitrile solution of tetrabutylammonium hexafluorophosphate) system was tested, as Figure 3 ( Figure 3 shown in (a) of

[0287] The ultraviolet-visible spectrophotometer is used to measure the transmittance of the polymer film in the doped state and the neutral state at a specific wavelength under square-wave potential, so as to calculate the optical contrast, response time, etc.; the ultraviolet-visible spectrophotometer records the time-transmittance curve, and the electrochemical workstation records the time-current curve. The coloring efficiency can also be calculated based on these two curves.

[0288] (2) Test the transmittance-time curves of polymer P(TTBD) at 1100 nm, 735 nm, 560 nm and 410 nm. The response time and coloring efficiency calculated from the time-transmittance curve are shown in Table 3 respectively.

[0289] As can be seen from Table 3, the polymer P(TTBD) has a fast response time and a high coloring efficiency.

[0290] Table 3: Electrochromic parameters of polymer P(TTBD)

[0291]

[0292] The chronoabsorption method was used to study the optical transmittance of polymer P(TTBD) at wavelengths of 1100 nm, 735 nm, 560 nm and 410 nm. During the experiment, the time interval of the potential step change was 5 s, as Figure 3 ( Figure 3 in which "Transmittance" represents transmittance and "Time" represents time) shown in (b). At the four wavelengths, the polymer P(TTBD) showed a certain optical contrast and good optical stability. In addition, the optical transmittance has a great influence on the color change of the polymer, and the polymer can change from purple in the fully de-doped state to light gray in the doped state.

[0293] Using the potentiostatic method, a voltage of 10 s was applied to the working electrode by an electrochemical workstation and a voltage of 2 s was applied every 100 s. At the same time, the ultraviolet-visible spectrometer was used to record the change trend of the transmittance of the polymer in the oxidized state and the reduced state under the maximum absorption peak, and thus the short-term memory effect map of the polymer was obtained.

[0294] (3) The short-term memory effect of polymer P(TTBD) was tested at a wavelength of 1100 nm. Voltages of 0 V and 1.2 V were applied respectively, and the transmittance changes of the polymer in the neutral state and the doped state were recorded, as Figure 3 ( Figure 3 in which "Transmittance" represents transmittance and "Time" represents time) shown in (c). It was found that the transmittance change of the polymer in the neutral state was 0.1%, and the transmittance change in the doped state was 5.2%. This indicates that the polymer has a good short-term memory effect.

[0295] The electrochromic properties of the polymer (P(TEBD)) prepared in Example 4 were tested, and the test results are as follows. Figure 4 Specifically:

[0296] (1) The spectroelectrochemical diagram of the polymer P(TEBD) in the MeCN - Bu4NPF6 (0.1 moL / L) system was tested, as shown in (a) of Figure 4 . Combining with the naked - eye observation of the color change of the polymer, it can be seen that as the potential increases, the color of the polymer changes from blue - violet to light blue (it is blue - violet in the fully de - doped state. Since the optical transmittance of the polymer P(TEBD) is average, the color span of the polymer material changes from blue - violet in the fully de - doped state to light blue in the doped state is general). This is because the neutral polymer has an absorption peak in the blue - light region, and the color of the neutral polymer is blue - violet; after the polymer is oxidized, the absorption peak in the blue - light region gradually weakens, the absorption peaks in the red - light region and near - infrared region appear and gradually rise, and the color also changes to light blue.

[0297] (2) The transmittance - time curves of the polymer P(TEBD) at 1100 nm, 730 nm and 485 nm were tested. The response time and coloring efficiency calculated from the time - transmittance curves are shown in Table 4 respectively.

[0298] Table 4: Electrochromic parameters of the polymer P(TEBD)

[0299]

[0300] The optical transmittance of the polymer P(TEBD) was studied by chronoabsorption method at wavelengths of 1100 nm, 730 nm, 560 nm and 485 nm. During the experiment, the time interval of the potential step change was 5 s, as shown in (b) of Figure 4 ( Figure 4 In it, "Transmittance" represents transmittance, and "Time" represents time). At the four wavelengths, the polymer P(TEBD) all showed a certain optical contrast and good optical stability; in addition, the optical transmittance has a great influence on the color change of the polymer, and the polymer material can change from blue - violet in the fully de - doped state to light blue in the doped state.

[0301] (3) The short - term memory effect of the polymer P(TEDD) was tested at a wavelength of 1100 nm. Voltages of 0.1 V and 1.3 V were applied respectively, and the transmittance changes of the polymer in the neutral state and doped state were recorded, as shown in (c) of Figure 4 . It was found that the transmittance change of the polymer in the neutral state was 0.1%, and the transmittance change in the doped state was 12%, and the short - term memory effect was general.

[0302] The electrochromic properties of the polymer (P(EEEBD)) prepared in Example 5 were tested, and the test results are as Figure 5 , specifically:

[0303] (1) The spectroelectrochemical diagram of the polymer P(EEEBD) in the MeCN - Bu4NPF6 (0.1 moL / L) system was tested, as shown in Figure 5 (a). Combining with the visual observation of the color change of the polymer, it can be seen that as the potential increases, the color of the polymer changes from purple to blue (it is purple in the fully de-doped state. Due to the good optical transmittance of the polymer P(EEEBD), the optical transmittance has a great influence on the color change of the polymer, and the polymer material can change from purple in the fully de-doped state to blue in the doped state, with a large color span). This is because the neutral polymer has an absorption peak in the violet and green regions respectively. The color of the neutral polymer appears purple; after the polymer is oxidized, the absorption peaks in the violet and green regions gradually weaken, an absorption peak appears in the near-infrared region and gradually rises, and the color also changes to blue.

[0304] (2) The transmittance-time curves of the polymer P(EEEBD) at 1100 nm, 800 nm, 543 nm and 390 nm were tested. The response time and coloring efficiency calculated from the time-transmittance curves are shown in Table 5 respectively.

[0305] Table 5: Electrochromic parameters of the polymer P(EEEDD)

[0306]

[0307] The optical transmittance of the polymer P(EEEBD) at 1100 nm, 800 nm, 543 nm and 390 nm wavelengths was studied by chronoabsorption method. During the experiment, the time interval of the potential step change was 5 s, as shown in Figure 5 ( Figure 5 in (b), where "Transmittance" represents transmittance and "Time" represents time). At the four wavelengths, the polymer P(EEEBD) showed a certain optical contrast and good optical stability.

[0308] (3) The short-term memory effect of the polymer P(EEEBD) was tested at 1100 nm wavelength. Voltages of -0.3 V and 1.1 V were applied respectively, and the transmittance changes of the polymer in the neutral state and doped state were recorded, as shown in Figure 5 (v). It was found that the transmittance change of the polymer in the neutral state was 1.2%, and the transmittance change in the doped state was 3.9%. This indicates that the polymer has a good short-term memory effect.

[0309] The electrochromic performance of the polymer (P(TTTBD)) prepared in Example 6 was tested, and the test results are as follows: Figure 6 Specifically:

[0310] (1) The spectroelectrochemical diagram of the polymer P(TTTBD) in the MeCN-Bu4NPF6 (0.1 moL / L) system was tested, as shown in (a) of Figure 6 . Combining with the visual observation of the color change of the polymer, it can be seen that as the potential increases, the color of the polymer changes from purple to blue-black (it is purple in the fully de-doped state. Due to the good optical transmittance of the polymer P(TTTBD) and the large influence of the optical transmittance on the color change of the polymer, the polymer material can change from purple in the fully de-doped state to blue-black in the doped state, with a large color span). This is because the neutral polymer has an absorption peak in the green light region and the yellow light region respectively, and the color of the neutral polymer appears purple; after the polymer is oxidized, the absorption peaks in the green light region and the yellow light region gradually weaken, and absorption peaks in the red light region and the near-infrared region appear and gradually increase, and the color also changes to blue-black.

[0311] (2) The transmittance-time curves of the polymer P(TTTBD) at 1100 nm, 765 nm, 535 nm and 420 nm were tested. The response time and coloring efficiency calculated from the time-transmittance curves are shown in Table 6 respectively.

[0312] Table 6: Electrochromic parameters of the polymer P(TTTBD)

[0313]

[0314] The optical transmittance of the polymer P(TTTBD) at 1100 nm, 765 nm, 535 nm and 420 nm wavelengths was studied by chronoabsorption method. During the experiment, the time interval of the potential step change was 5 s, as shown in (b) of Figure 6 ( Figure 6 In it, "Transmittance" represents transmittance and "Time" represents time). At the four wavelengths, the polymer P(TTTBD) showed a certain optical contrast and good optical stability.

[0315] (3) The short-term memory effect of the polymer P(TTTBD) was tested at 1100 nm wavelength. Voltages of 0.4 V and 1.4 V were applied respectively, and the transmittance changes of the polymer in the neutral state and the doped state were recorded, as shown in (c) of Figure 6 . It was found that the transmittance change of the polymer in the neutral state was 0.5%, and the transmittance change in the doped state was 12.7%. This indicates that the short-term memory effect of this polymer is general.

[0316] The electrochromic properties of the polymer (P(TEEBD)) prepared in Example 7 were tested, and the test results are as follows: Figure 7 Specifically:

[0317] (1) The spectroelectrochemical diagram of the polymer P(TEEBD) in the MeCN-Bu4NPF6 (0.1 moL / L) system was tested, as shown in (a) of Figure 7 . Combining with the visual observation of the color change of the polymer, it can be seen that as the potential increases, the color of the polymer changes from purplish red to light blue (it is purplish red in the fully de-doped state. Due to the good optical transmittance of the polymer P(TEEBD), the optical transmittance has a great influence on the color change of the polymer, and the polymer material can change from the purplish red in the fully de-doped state to the light blue in the doped state, with a large color span). This is because the neutral polymer has an absorption peak in the ultraviolet region and the green region respectively, and the color of the neutral polymer appears purplish red; after the polymer is oxidized, the absorption peaks in the ultraviolet region and the green region gradually weaken, the absorption peak in the near-infrared region appears and gradually rises, and the color also changes to light blue.

[0318] (2) The transmittance-time curves of the polymer P(TEEBD) at 1100 nm, 650 nm, 525 nm and 380 nm were tested. The response time and coloring efficiency calculated from the time-transmittance curves are shown in Table 7 respectively. It can be seen from Table 7 that the polymer P(TEEBD) has a relatively high optical contrast and a relatively high coloring efficiency.

[0319] Table 7: Electrochromic parameters of the polymer P(TEEBD)

[0320]

[0321] The optical transmittance of the polymer P(TEEBD) at 1100 nm, 650 nm, 525 nm and 380 nm wavelengths was studied by chronoabsorption method. During the experiment, the time interval of the potential step change was 5 s, as shown in (b) of Figure 7 ( Figure 7 In it, "Transmittance" represents transmittance and "Time" represents time). At the four wavelengths, the polymer P(TEEBD) showed a certain optical contrast and good optical stability.

[0322] (3) The short-term memory effect of the polymer P(TEEBD) was tested at 1100 nm wavelength. Voltages of -0.1 V and 1.1 V were applied respectively, and the transmittance changes of the polymer in the neutral state and the doped state were recorded, as shown in (c) of Figure 7 . It was found that the transmittance change of the polymer in the neutral state was 0.2%, and the transmittance change in the doped state was 6.2%. This indicates that the polymer has a good short-term memory effect.

[0323] The electrochromic properties of the polymer (P(ETTBD)) prepared in Example 8 were tested, and the test results are as follows Figure 8 Specifically:

[0324] (1) The spectroelectrochemical diagram of the polymer P(ETTBD) in the MeCN - Bu4NPF6 (0.1 moL / L) system was tested, as shown in Figure 8 (a). Combining with the visual observation of the color change of the polymer, it can be seen that as the potential increases, the color of the polymer changes from light gray to blue (it is light gray in the fully de-doped state. Due to the good optical transmittance of the polymer P(ETTBD) and the great influence of the optical transmittance on the color change of the polymer, the polymer material can change from light gray in the fully de-doped state to blue in the doped state, with a large color span). This is because the neutral polymer has an absorption peak in the green light region and the yellow light region, and the color of the neutral polymer appears as light gray; after the polymer is oxidized, the absorption peaks in the green light region and the yellow light region gradually weaken, an absorption peak appears in the near-infrared region and gradually rises, and the color also changes to blue.

[0325] (2) The transmittance-time curves of the polymer P(ETTBD) at 1100 nm, 800 nm, 600 nm, and 480 nm were tested. The response time and coloring efficiency calculated from the time-transmittance curves are shown in Table 8. It can be seen from Table 8 that the polymer P(ETTBD) has a relatively high optical contrast and a relatively high coloring efficiency.

[0326] Table 8: Electrochromic parameters of the polymer P(ETTBD)

[0327]

[0328]

[0329] The optical transmittance of the polymer P(ETTBD) at 1100 nm, 800 nm, 600 nm, and 480 nm wavelengths was studied by chronoabsorption method. During the experiment, the time interval of the potential step change was 5 s, as shown in Figure 8 ( Figure 8 In (b), "Transmittance" represents transmittance and "Time" represents time). It shows that at the four wavelengths, the polymer P(ETTBD) exhibits a certain optical contrast and good optical stability.

[0330] (3) The short-term memory effect of the polymer P(ETTBD) was tested at 800 nm wavelength. Voltages of -0.1 V and 1.3 V were applied respectively, and the transmittance changes of the polymer in the neutral state and the doped state were recorded, as shown in Figure 8As shown in Fig. (c), it is found that the transmittance change of the polymer in the neutral state is 1.1%, and that in the doped state is 3.2%, indicating that the polymer has a good short-term memory effect.

[0331] The electrochromic properties of the polymer (P(ETTD)) prepared in the comparative example were tested, and the test results are as Figure 9 , specifically:

[0332] (1) The spectroelectrochemical diagram of the polymer P(ETTD) prepared in the comparative example in the MeCN-Bu4NPF6 (0.1 moL / L) system was tested, and the results are as Figure 9 shown in Fig. (a), Figure 9 In Fig. (a), Wavelength is the wavelength and Absorbance is the absorbance. As Figure 9 shown in Fig. (a), and combined with the naked-eye observation of the color change of the polymer, it can be seen that as the potential increases, the color of the polymer changes from dark blue to blue-gray (it is dark blue in the fully de-doped state. Since the optical transmittance of the polymer P(ETTD) is not good, the polymer material can change from the dark blue in the fully de-doped state to the blue-gray in the doped state, with a small color span). This is because the polymer in the neutral state has an absorption peak in the ultraviolet region and the red region respectively, and the color of the polymer in the neutral state is dark blue; after the polymer is oxidized, the absorption peaks in the ultraviolet region and the red region gradually weaken and finally disappear completely, and an absorption peak in the near-infrared region appears and gradually rises, and the color also changes to blue-gray.

[0333] (2) The transmittance-time curves of the polymer P(ETTD) at 1100 nm, 900 nm, 678 nm and 420 nm were tested. The response time and coloring efficiency calculated from the time-transmittance curves are shown in Table 9 respectively. It can be seen from Table 9 that the response time of the polymer P(ETBD) is relatively fast and the coloring efficiency is average. Compared with Example 1, the comparative example uses an asymmetric acceptor, resulting in a change in the electron-withdrawing ability of the acceptor in the D-A structure, affecting the change in the band gap, and finally affecting the coloring efficiency.

[0334] Table 9: Electrochromic parameters of the polymer P(ETTD)

[0335]

[0336] The optical transmittance of the polymer P(ETTD) at 1100 nm, 900 nm, 678 nm and 420 nm wavelengths was studied by chronoabsorption method. During the experiment, the time interval of the potential step change was 5 s, as Figure 9As shown in Fig. (b). At four wavelengths, the polymer material exhibited certain optical contrast and good optical stability; in addition, the optical transmittance had a great influence on the color change of the polymer, and the polymer material could change from dark blue in the fully de-doped state to blue-gray in the doped state.

[0337] (3) The short-term memory effect of P(ETTD) was tested at a wavelength of 1100 nm. Voltages of -0.3 V and 1.1 V were applied respectively, and the transmittance changes of the polymer in the neutral state and the doped state were recorded. As Figure 9 shown in Fig. (c), it was found that the transmittance change of the polymer in the neutral state was 1.5%, and the transmittance change in the doped state was 5.2%. This indicated that the polymer had a good short-term memory effect.

[0338] The response times and coloring efficiencies of the polymers prepared in Examples 1-8 at a wavelength of 1100 nm were statistically analyzed to obtain Table 10.

[0339] Table 10

[0340]

[0341] In the polymer structures of Example 1 and Example 2, π was different and D was the EDOT group; among them, π in Example 1 was the thiophene group, π in Example 2 was the EDOT group, and the coloring efficiency CE of Example 1 was 129.79 cm 2 C -1 , and the coloring efficiency CE of Example 2 was 158.33 cm 2 C -1 , indicating that when D was the EDOT group, when the π structure was EDOT, it was more conducive to improving the coloring efficiency;

[0342] In the polymer structure of Example 3, both π and D were thiophene groups. The polymer of Example 3 with four thiophene groups had the highest coloring efficiency among Examples 1-8. This showed that the combination of four thiophene groups was more conducive to improving the coloring efficiency, and the thiophene group was more conducive to improving the coloring efficiency than the EDOT group;

[0343] In the polymer structures of Example 4 and Example 3, π was different. Among them, π in Example 3 was the thiophene group and π in Example 4 was the EDOT group. Compared with Example 3, the coloring efficiency of Example 4 was worse, which was attributed to the energy level difference between thiophene and EDOT, which might lead to local interruption of the conjugated chain, hinder electron delocalization, and require more charge compensation to achieve the same ΔOD;

[0344] Example 5 contained three EDOT groups, Example 2 contained two EDOT groups, and the coloring efficiency CE of Example 5 was lower than that of Example 2, indicating that excessive extension of the conjugated structure had an impact on the coloring efficiency;

[0345] In the polymer structure of Example 6, both π and D are thiophene groups, and there are a total of six thiophene groups, which is two more thiophene groups than in Example 3. The coloring efficiency of Example 6 has decreased compared to Example 3. The deterioration of the polymer coloring performance in Example 6 may be attributed to the influence of the extension of its conjugated structure on the coloring efficiency.

[0346] Based on Example 2, Example 7 introduced a thiophene group. Although the conjugated structure was extended, since D is a thiophene group, the coloring efficiency was instead improved, indicating that the thiophene group is more beneficial for improving the coloring efficiency than the EDOT group.

[0347] Compared with Example 6, in Example 8, the thiophene group in D of Example 6 was replaced with an EDOT group, resulting in a decrease in the coloring efficiency.

[0348] The coloring efficiency of the comparative example is the worst. Among them, the coloring efficiency of the comparative example is 92.19 cm 2 C -1 , and that of Example 1 is 129.79 cm 2 C -1 . The reason is that the comparative example contains asymmetric thiophene, which also proves that symmetric receptors are more beneficial for improving the coloring efficiency.

[0349] The above are only the embodiments of the present invention, and do not limit the patent scope of the present invention accordingly. All equivalent transformations made using the content of the specification of the present invention, directly or indirectly applied in the relevant technical fields, are equally included in the patent protection scope of the present invention.

Claims

1. A monomer, characterized in that, The specific structural formula is as follows: Among them, R is selected from an alkyl group, an aryl group or a substituted aryl group having C1-C 18 carbon atoms; D is selected from thiophene or 3,4-ethylenedioxythiophene; π is selected from any of the following structures:

2. The monomer according to claim 1, wherein The substituted aryl group includes an aryl group substituted with a halogen, nitro group, amino group, hydroxyl group or carboxyl group.

3. A monomer according to claim 1, characterized in that, When D is thiophene, π is selected from the structures containing thiophene among Structure I to Structure VI.

4. A monomer according to claim 1, characterized in that, π is selected from one of Structure I, Structure II and Structure IV.

5. A method for preparing a monomer as described in any one of claims 1 to 4, characterized in that, It includes the following steps: Under a protective gas atmosphere, compound A, a catalyst, tributyl(2,3-dihydro[3,4-b][1,4]dioxin-5-yl)stannane or tributyl(2-thienyl)stannane are mixed in a solvent, and through reaction, the monomer is obtained; The structural formula of compound A is: Wherein, X is a halogen group.

6. The method according to claim 3, characterized in that, The mass ratio of compound A to tributyl(2,3-dihydro[3,4-b][1,4]dioxin-5-yl)stannane is 0.1 - 0.12:0.1 - 0.

5.

7. A polymer, characterized in that, The raw material of the polymer includes the monomer according to any one of claims 1 to 4.

8. A method for preparing a polymer as claimed in claim 7, characterized in that, It includes the following steps: An electrolyte and the monomer are mixed in a solvent to obtain an electrolyte solution, and the electrolyte solution is added to an electrode system, and through an electrochemical polymerization reaction, the polymer is deposited.

9. An electrochromic material, characterized in that, It includes the polymer according to claim 7.

10. An electrochromic device, characterized in that, It includes the electrochromic material according to claim 9.

Images