Conjugated polymer material for optimizing electrochromic performance by regulating and controlling cyano content and preparation method of conjugated polymer material

Abstract

The invention discloses a conjugated polymer material for optimizing electrochromic performance by regulating and controlling cyano content and a preparation method, the conjugated polymer material with cyano content difference is prepared by direct arylation polycondensation reaction, the structural formula of the conjugated polymer material is shown in the specification, m is a natural number of 0-4, and n is a natural number of 1-10000. The series of conjugated polymers can reduce the optical band gap of the polymer due to introduction of a strong electron withdrawing group cyano group, so that the absorption spectrum moves towards a long wave direction, the lowest unoccupied molecular orbital energy level of the polymer is remarkably improved, the electron affinity of the polymer is enhanced, and the molecular arrangement and charge transfer path of the polymer are optimized; according to the present invention, the prepared electrochromic material has characteristics of excellent electrochromic function layer material, excellent thermal stability and excellent chemical stability, and the charge mobility is improved so as to improve the electrochromic optical contrast ratio and the color developing efficiency, such that the electrochromic material is the excellent electrochromic function layer material.

Description

Technical Field

[0001] The present invention relates to the field of organic optoelectronic materials and devices, in particular to the application of a series of conjugated polymers with different cyanide contents in the field of electrochromism. Background Art

[0002] Electrochromic materials refer to materials whose doping degree can be regulated by changing the applied external voltage, causing changes in the energy band structure of the materials, thereby leading to changes in their optical absorption properties, which are visually manifested as changes in the color of the material film. With the increase in the doping (oxidation) degree, electrochromic materials can form polaron and bipolaron energy levels with lower band gaps between the valence band and the conduction band. The formation of these new energy levels changes the energy required for valence electron transitions, which is spectroelectrochemically manifested as changes in absorption peaks. Such materials have been commercially applied in the fields of electronic displays, building energy conservation, military security, aerospace, 3C products, etc. It is expected that by 2030, the global market size of electrochromic materials and devices will reach 22.51 billion yuan, with a compound annual growth rate of 7.14% (DIResaerch). The field of electrochromism is full of great opportunities and challenges.

[0003] On the one hand, scientific researchers improve the electron conduction performance (carrier mobility, conductivity, electron conduction rate, etc.) of electrochromic materials through strategies such as chemical structure design, doping, and thin film morphology optimization. On the other hand, they improve the ion transport performance (ion diffusion coefficient, material stability during ion transport, etc.) of electrochromic materials by constructing crosslinks and preparing intrinsically porous materials. The improvement of electron conduction and ion transport performance can effectively improve the response speed of electrochromic materials and devices on the one hand, and on the other hand, it also means higher charge utilization efficiency and lower kinetic decay during the transport process, which can further improve other key performance such as coloring efficiency and cycle stability, thereby improving the overall performance of the device. The introduction of cyanide groups can optimize the molecular arrangement and charge transport path of polymers, improve the charge mobility, but there are not many related studies based on this, and the structure-activity relationship between the structure of the material and its electrochromic performance is not clear, and relevant research is urgently needed. Summary of the Invention

[0004] In view of the deficiencies of the prior art, the present invention conducts research on conjugated polymer materials for regulating the cyanide content to optimize electrochromic performance and their preparation methods. Due to the introduction of the strong electron-withdrawing group cyanide in this series of conjugated polymers, the optical band gap of the polymer can be reduced, thereby shifting its absorption spectrum towards the long-wavelength direction, significantly increasing the lowest unoccupied molecular orbital energy level of the polymer, enhancing the electron affinity of the polymer, optimizing the molecular arrangement and charge transport path of the polymer, increasing the charge mobility, and thus improving the optical contrast and color display efficiency of electrochromism. It is an excellent electrochromic functional layer material and has excellent thermal stability and chemical stability.

[0005] The present invention is achieved through the following technical solutions: In the first aspect of the present invention, a conjugated polymer material with different cyanide contents is provided, which is characterized by having the following structure:

[0006] Among them, m is a natural number from 0 to 4, and n is a natural number from 1 to 10,000.

[0007] According to the differences in m and the substitution positions, it has the following structures: .

[0008] In the second aspect of the present invention, a preparation method for the above-mentioned conjugated polymer material with different cyanide contents is provided, including the following steps: Carry out direct arylation polycondensation reaction on a cyanide-substituted dibromobenzene monomer, 3,4-propylenedioxythiophene, and a certain proportion of pivalic acid, tris(dibenzylideneacetone)dipalladium-chloroform adduct, cesium carbonate, tris(2-methoxyphenyl)phosphine, and dimethylacetamide to obtain a conjugated polymer.

[0009] Preferably, in the above steps, the molar ratio of the cyanide-substituted dibromobenzene monomer to 3,4-propylenedioxythiophene is 1:1.

[0010] Preferably, in the above steps, the direct arylation polycondensation reaction is as follows: under nitrogen protection, the cyanide-substituted dibromobenzene monomer, 3,4-propylenedioxythiophene, and a certain proportion of pivalic acid, tris(dibenzylideneacetone)dipalladium-chloroform adduct, cesium carbonate, tris(2-methoxyphenyl)phosphine are dissolved in dimethylacetamide, and heated to 110 °C and refluxed for 6 hours.

[0011] In the third aspect of the present invention, the application of the above-mentioned conjugated polymer in the field of electrochromism is provided. Description of the Drawings

[0012] Figure 1 1H NMR spectra of pCN0, pCN1, and pCN2-3.

[0013] Figure 2 It is a spectroelectrochemical diagram. Detailed implementation manners

[0014] It should be noted that the following detailed description is illustrative and aims to provide further explanation for this application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which this application belongs.

[0015] In order to enable those skilled in the art to more clearly understand the technical solution of this application, the technical solution of this application will be described in detail below in conjunction with specific embodiments. If the specific experimental conditions are not specified in the embodiments, they are usually in accordance with conventional conditions or in accordance with the conditions recommended by the reagent company; the reagents, consumables, etc. used in the following embodiments, unless otherwise specified, can be obtained through commercial channels. Embodiment

[0016] Preparation of conjugated polymer materials with different cyano contents (structure pCN0) The chemical reaction process is as shown below, and the specific reaction steps and reaction conditions are as follows:

[0017] Under the condition of nitrogen protection, 1,4-dibromobenzene (236 mg, 1 mmol), 3,4-propylenedioxythiophene (244 mg, 1 mmol), pivalic acid (15.15 mg, 0.15 mmol), palladium catalyst (22.23 mg, 0.025 mmol), cesium carbonate (407.50 mg, 1.25 mmol) were added to a pressure-resistant bottle, N,N-dimethylacetamide (10 mL) was added and stirred evenly, and the mixture was heated under reflux at 110 °C for 6 h. After cooling to room temperature, it was washed and precipitated with absolute ethanol, and then the polymer was extracted successively with absolute ethanol, n-hexane and chloroform in a Soxhlet extractor. Finally, the excess solvent was removed by rotary evaporation to obtain the chloroform component polymer with a yield of 58%. Analyzed by nuclear magnetic resonance hydrogen spectrum ( Figure 1 )), it is pCN0 polymer. 1 H NMR (400 MHz, CDCl3, ppm), δ7.76 (s, 4H), 4.20 (m, 4H), 3.58 (m, 4H), 3.34 (m, 4H), 1.30 (m, 16H), 0.91(m, 12H). Embodiment

[0018] Preparation of conjugated polymer materials with different cyano contents (structure pCN1) The chemical reaction process is as shown below, and the specific reaction steps and reaction conditions are as follows:

[0019] Under nitrogen protection, 2,5-dibromo-1-cyanobenzene (261 mg, 1 mmol), 3,4-propylenedioxythiophene (244 mg, 1 mmol), pivalic acid (15.15 mg, 0.15 mmol), palladium catalyst (22.23 mg, 0.025 mmol), and cesium carbonate (407.50 mg, 1.25 mmol) were added to a pressure-resistant bottle. N,N-dimethylacetamide (10 mL) was added and stirred evenly, and then heated under reflux at 110 °C for 6 h. After cooling to room temperature, it was washed and precipitated with absolute ethanol, and then the polymer was successively extracted with absolute ethanol, n-hexane, and chloroform in a Soxhlet extractor. Finally, the excess solvent was removed by rotary evaporation to obtain the chloroform-component polymer with a yield of 62%. Analyzed by nuclear magnetic resonance hydrogen spectrum ( Figure 1 ), it was the pCN1 polymer. 1 H NMR (400 MHz, CDCl3, ppm), δ8.18 (m, 1H), 7.87 (m, 1H), 7.56 (m, 1H), 4.27 (m, 4H), 3.56 (m, 4H), 3.33(m, 4H), 1.34 (m, 16H), 0.90 (m, 12H). Example

[0020] Preparation of Conjugated Polymer Materials with Different Cyano Contents (Structure pCN12-3) The chemical reaction process is as shown below, and the specific reaction steps and reaction conditions are as follows:

[0021] Under nitrogen protection, 2,4-dibromo-1,5-dicyanobenzene (286 mg, 1 mmol), 3,4-propylenedioxythiophene (244 mg, 1 mmol), pivalic acid (15.15 mg, 0.15 mmol), palladium catalyst (22.23 mg,0.025 mmol), and cesium carbonate (407.50 mg, 1.25 mmol) were added to a pressure-resistant bottle. N,N-dimethylacetamide (10 mL) was added and stirred evenly, and then heated under reflux at 110 °C for 6 h. After cooling to room temperature, it was washed and precipitated with absolute ethanol, and then the polymer was successively extracted with absolute ethanol, n-hexane, and chloroform in a Soxhlet extractor. Finally, the excess solvent was removed by rotary evaporation to obtain the chloroform-component polymer with a yield of 62%. Analyzed by nuclear magnetic resonance hydrogen spectrum ( Figure 1 ), it was the pCN2-3 polymer. 11H NMR (400 MHz, CDCl3, ppm), δ 7.65 (m, 1H), 7.42 (m, 1H), 4.00 (m, 4H), 3.49 (m, 4H), 3.29 (m, 4H), 1.31 (m, 16H), 0.89 (m, 12H). Example

[0022] Taking the polymer materials obtained in Examples 1, 2, and 3 as examples, they are applied in the field of electrochromics. The following examples will illustrate the conjugated polymers with different cyanide contents provided by the present invention and their application processes in the field of electrochromics. However, the present invention is not limited to the examples given.

[0023] (1) Spectroelectrochemistry Spray the polymer materials obtained in Examples 1, 2, and 3 on ITO conductive glass to form a polymer film. Place the ITO conductive glass coated with the polymer film in a three-electrode electrolytic cell. The electrolytic cell contains an acetonitrile solution dissolved with tetrabutylammonium hexafluorophosphate. Among them, the working electrode is the ITO conductive glass attached with the polymer film, the counter electrode is a platinum sheet, and the reference electrode is an Ag / AgCl electrode. By using the potentiostatic method, adjust the voltage applied to the working electrode through an electrochemical workstation, and at the same time record the change trend of the absorption spectrum of the polymer at different voltages with a UV-visible spectrometer, and then the spectroelectrochemical spectrum of the polymer can be obtained, as shown in Figure 2 .

[0024] (2) Kinetics Use a UV-visible spectrophotometer to measure the transmittance of the polymer film in the oxidized state and the reduced state 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.

[0025] The above description is only the preferred embodiments of the present application and is not used to limit the present application. For those skilled in the art, the present application can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A conjugated polymer material with different cyanide group contents, characterized in that, It has the following structure: ， Wherein, m is a natural number from 0 to 4, and n is a natural number from 1 to 10,000.

2. The conjugated polymer according to claim 1, wherein According to the differences in m and the substitution positions, it has the following structure: 。 3. The preparation method of claim 1 or the conjugate polymer as described, characterized in that, It includes the following steps: (1) A direct arylation polycondensation reaction is carried out on a cyano-substituted dibromobenzene monomer with a certain molar ratio, 3,4-propylenedioxythiophene, and a certain proportion of pivalic acid, tris(dibenzylideneacetone)dipalladium-chloroform adduct, cesium carbonate, tris(2-methoxyphenyl)phosphine, and dimethylacetamide to obtain a conjugated polymer.

4. The conjugated polymer based on the difference in cyano content according to any one of claims 1-2 is applied in the field of electrochromism.

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