A method for preparing a conductive polymer thin film of a benzodithiazole derivative and applications thereof

Abstract

The application belongs to the technical field of organic polymer chemistry and functional materials, and provides a preparation method and application of a conductive polymer film of a benzodithiazole derivative, the derivative being a symmetric D-A-D type conjugated structure, with benzene[1,2-c:4,5-c']bis([1,2,5]thiadiazo) as an electron-deficient acceptor unit, thiophene as a pi bridge connecting unit, and 3,4-ethylenedioxythiophene as an electron-rich donor unit. The application uses a D-A-D type monomer with benzodithiazole as a core and 3,4-ethylenedioxythiophene as an end group, and the strong intramolecular charge transfer effect reduces the optical band gap; the introduction of the 3,4-ethylenedioxythiophene unit endows the material with a low oxidation potential and high structural stability, and the driving voltage is as low as 1.2 V or below; the polymer film has good electrochemical reversibility, and after 1000 coloring-fading cycles, the optical contrast is maintained at about 60%, and the material has a good cycle life.

Description

Technical Field

[0001] This invention relates to the field of organic polymer chemistry and functional materials technology, and in particular to a method for preparing a conductive polymer film of a benzobisthiadiazole derivative and its application. Background Technology

[0002] Electrochromic materials refer to electroactive functional materials that undergo reversible and stable redox reactions under an applied electric field. This results in synchronous, reversible, and repeatable changes in the material's light absorption intensity and transmittance across a broad spectral range from visible to near-infrared. Macroscopically, this manifests as dynamic and reversible switching of color depth and light transmission transparency in thin-film devices. Compared to dimming technologies such as liquid crystal dimming and thermochromic dimming, electrochromic materials offer advantages such as low driving voltage, extremely low static power consumption, and a wide spectral adjustable range. In recent years, they have demonstrated enormous application potential and practical value in numerous military and civilian optoelectronic fields, including energy-saving smart dimming windows for buildings, anti-glare rearview mirrors for automobiles, flexible and rollable display panels, adaptive optical filters, and military infrared camouflage and stealth devices.

[0003] Based on the fundamental differences in chemical composition and molecular skeleton structure, the mainstream electrochromic materials developed by academia and industry are currently divided into four major systems: inorganic electrochromic materials, organic small molecule electrochromic materials, conjugated organic polymer electrochromic materials, and metal-organic chelate electrochromic materials. Each type of material has its advantages and disadvantages. Inorganic materials are stable during cycling but have poor processability and limited color options; small molecule materials offer rich colors but are difficult to form films and have insufficient cycle stability; metal chelates suffer from drawbacks such as easy hydrolysis and stringent device packaging requirements, limiting their application scenarios.

[0004] Therefore, providing a new generation of electrochromic functional materials with deep absorption properties, high contrast between light and dark, excellent electrochemical cycling stability, and near-infrared synchronous tunability has become an urgent problem to be solved. Summary of the Invention

[0005] The purpose of this invention is to overcome the deficiencies in the prior art and provide a method for preparing a conductive polymer film of a benzobisthiadiazole derivative and its application.

[0006] To achieve the above-mentioned objectives, the present invention provides the following technical solution: This invention provides a benzobisthiadiazole derivative, the structure of which is shown below: .

[0007] This invention provides a method for preparing the benzobisthiadiazole derivative, comprising the following steps: (1) Under a protective atmosphere, 4,8-dibromobenzo[1,2-c:4,5-c']bis([1,2,5]thiadiazole), 2-tributyltinylthiophene, palladium catalyst and solvent were mixed and coupled to obtain intermediate I; (2) Intermediate I, N-bromosuccinimide and solvent are mixed and subjected to bromination reaction to obtain intermediate II; (3) Under a protective atmosphere, intermediate II, tributyl(2,3-dihydrothiophene[3,4-b]-[1,4]dioxin-5-yl)tinane, palladium catalyst and solvent are mixed and coupled to obtain the benzobisthiadiazole derivative.

[0008] Preferably, the palladium catalyst in step (1) is bis(triphenylphosphine)palladium dichloride and / or tetra(triphenylphosphine)palladium; The solvent in step (1) is one or more of N,N-dimethylformamide, 1,4-dioxane, toluene and tetrahydrofuran; In step (1), the molar ratio of 4,8-dibromobenzo[1,2-c:4,5-c']bis([1,2,5]thiadiazole) to 2-tributyltinylthiophene is 1:2~2.1; In step (1), the molar ratio of 4,8-dibromobenzo[1,2-c:4,5-c']bis([1,2,5]thiadiazole) to palladium catalyst is 100:2~3; The coupling reaction in step (1) is carried out at a temperature of 90~100℃ for 8~12h. The structure of intermediate I in step (1) is as follows: .

[0009] Preferably, the solvent in step (2) is one or more of N,N-dimethylformamide, 1,4-dioxane, toluene and tetrahydrofuran; In step (2), the molar ratio of intermediate I to N-bromosuccinimide is 1:1~1.2; The bromination reaction in step (2) takes 12-16 hours; The structure of intermediate II in step (2) is as follows: .

[0010] Preferably, the palladium catalyst in step (3) is bis(triphenylphosphine)palladium dichloride and / or tetra(triphenylphosphine)palladium; The solvent in step (3) is one or more of N,N-dimethylformamide, 1,4-dioxane, toluene and tetrahydrofuran; In step (3), the molar ratio of intermediate II to tributyl(2,3-dihydrothiopheno[3,4-b]-[1,4]dioxin-5-yl)stanane is 1:2~2.1; In step (3), the molar ratio of intermediate II to palladium catalyst is 100:2~3.1; The coupling reaction in step (3) is carried out at a temperature of 90~100℃ for 8~12h.

[0011] The present invention also provides the application of the benzobisthiadiazole derivative in electrochromic materials, smart dimming windows or electrochromic display devices.

[0012] The present invention provides an electrochromic film, wherein the polymer monomer of the electrochromic film is the benzobisthiadiazole derivative.

[0013] This invention provides a method for preparing the electrochromic thin film, comprising the following steps: (a) The benzobisthiadiazole derivative, supporting electrolyte, and solvent are mixed to obtain a polymer electrolyte; (b) The electrochromic film is obtained by electrochemically depositing the polymer electrolyte on the surface of a conductive substrate.

[0014] Preferably, the electrolyte used in step (a) is lithium perchlorate; In step (a), the solvent contains dichloromethane and acetonitrile, with a volume ratio of 1:2 to 2.5. In step (a), the concentration of the benzobisthiadiazole derivative in the polymerization electrolyte is 0.02~0.08 mol / L; In step (a), the concentration of the supporting electrolyte in the polymerization electrolyte is 0.1~0.2 mol / L.

[0015] Preferably, the applied potential for electrochemical deposition in step (b) is 1.4~1.5V.

[0016] This invention provides a benzobisthiadiazole derivative with a symmetrical DAD-type conjugated structure. The derivative uses benzo[1,2-c:4,5-c']bis([1,2,5]thiadiazole) as the electron-deficient acceptor unit, thiophene as the π-bridge unit, and 3,4-ethylenedioxythiophene as the electron-rich donor unit. The core design mechanism of this derivative is that the strongly electron-withdrawing benzobisthiadiazole acceptor and the electron-rich 3,4-ethylenedioxythiophene donor are connected via a thiophene bridge chain, which can construct a significant intramolecular charge transfer (ICT) effect, effectively narrowing the optical band gap of the material. The polymer film obtained by electropolymerization of this monomer exhibits broad and strong characteristic absorption in the visible light region under neutral conditions. When the film undergoes electrochemical oxidation doping, the electronic structure of the conjugated main chain changes, the original visible light absorption peak is attenuated, and the absorption spectrum simultaneously redshifts to the near-infrared band. Meanwhile, the 3,4-ethylenedioxythiophene unit introduced into the molecule can enhance the electrochemical activity and framework structure stability of the polymer film, reduce the device operating driving voltage, and significantly extend the electrochemical cycle life of the film.

[0017] The present invention also provides a method for preparing the derivative, wherein 4,8-dibromobenzo[1,2-c:4,5-c']bis([1,2,5]thiadiazole), 2-tributyltinylthiophene, palladium catalyst and solvent are mixed in a protective atmosphere and coupled to obtain intermediate I; intermediate I, N-bromosuccinimide and solvent are mixed and bromination reaction is carried out to obtain intermediate II; intermediate II, tributyl(2,3-dihydrothiaphene[3,4-b]-[1,4]dioxin-5-yl)tinane, palladium catalyst and solvent are mixed in a protective atmosphere and coupled to obtain the benzobisthiadiazole derivative. The three-step synthesis route provided by this invention suppresses byproducts such as monobromination and excessive tinning by precisely controlling the molar ratio of raw materials, reaction temperature, and reaction time. After each reaction, intermediates are purified by water washing, drying, and gradient elution using silica gel column chromatography, which can efficiently obtain high-purity EDOT-T-BTD target monomers. This segmented process solves the industry pain points of direct coupling easily generating multi-substituted impurities and difficult product separation. Intermediates I and II can be stably separated and characterized. The raw materials are readily available, the reaction conditions are mild, the overall yield is stable, and the prepared monomer has excellent solubility, making it suitable for subsequent constant potential electrochemical polymerization processes. It can uniformly grow well-structured, porous, and stable DAD conjugated electrochromic films on ITO conductive substrates.

[0018] The beneficial effects of this invention are as follows: 1. Novel molecular structure design and precise performance regulation: A DAD-type monomer with benzobisthiadiazole as the core and 3,4-ethylenedioxythiophene as the end group is constructed. The strong intramolecular charge transfer effect can significantly reduce the optical band gap.

[0019] 2. Excellent electrochemical performance: The introduction of 3,4-ethylenedioxythiophene units endows the material with low oxidation potential and high structural stability, with a driving voltage as low as 1.2V; the resulting polymer film has good electrochemical reversibility, and after 1000 coloring-fading cycles, the optical contrast is maintained at about 60%, and the material has good cycle life.

[0020] 3. Excellent overall performance and wide range of applications: The electrochromic film has an optical contrast of about 30% at a wavelength of 1225 nm, a coloring time of 2 s, and a fading time of 1.9 s; it can be widely used in energy-saving building dual-band smart windows, short-wave infrared dynamic camouflage, infrared encrypted steganography / security display, energy storage color-changing integrated devices and other fields.

[0021] 4. The preparation process is simple and reproducible: the monomer synthesis adopts the classic Stille coupling reaction, which is mild and has a stable yield; the film preparation adopts a one-step electrochemical polymerization method, which produces uniform film with strong adhesion to the substrate. Attached Figure Description

[0022] Figure 1 The images show the UV-Vis absorption spectra of the benzobisthiadiazole derivative electrochromic film in Example 1 at different voltages. Figure 2 The image shows the colorimetric diagrams of the benzobisthiadiazole derivative electrochromic film in Example 1 at different voltages. Figure 3 This is a cyclic stability graph of the benzobisthiadiazole derivative electrochromic film in Example 1, measured at 462 nm under a step voltage. Figure 4 The response time diagram of the benzobisthiadiazole derivative electrochromic film in Example 1 was measured at 462 nm under a step voltage. Figure 5 This is a cyclic stability graph of the benzobisthiadiazole derivative electrochromic film in Example 1, measured at 1225 nm under a step voltage. Figure 6 The image shows the response time of the benzobisthiadiazole derivative electrochromic film in Example 1, measured at 1225 nm under a step voltage. Detailed Implementation

[0023] This invention provides a benzobisthiadiazole derivative, the structure of which is shown below: .

[0024] This invention provides a method for preparing the benzobisthiadiazole derivative, comprising the following steps: (1) Under a protective atmosphere, 4,8-dibromobenzo[1,2-c:4,5-c']bis([1,2,5]thiadiazole), 2-tributyltinylthiophene, palladium catalyst and solvent were mixed and coupled to obtain intermediate I; (2) Intermediate I, N-bromosuccinimide and solvent are mixed and subjected to bromination reaction to obtain intermediate II; (3) Under a protective atmosphere, intermediate II, tributyl(2,3-dihydrothiophene[3,4-b]-[1,4]dioxin-5-yl)tinane, palladium catalyst and solvent are mixed and coupled to obtain the benzobisthiadiazole derivative.

[0025] In this invention, the protective atmosphere in step (1) is nitrogen, helium or argon.

[0026] In this invention, the palladium catalyst in step (1) is bis(triphenylphosphine)palladium dichloride and / or tetra(triphenylphosphine)palladium.

[0027] In this invention, the solvent in step (1) is one or more of N,N-dimethylformamide, 1,4-dioxane, toluene and tetrahydrofuran.

[0028] In this invention, the molar ratio of 4,8-dibromobenzo[1,2-c:4,5-c']bis([1,2,5]thiadiazole) and 2-tributyltin-thiophene in step (1) is preferably 1:2 to 2.1, more preferably 1:2.02 to 2.08, and even more preferably 1:2.04 to 2.06.

[0029] In this invention, the molar ratio of 4,8-dibromobenzo[1,2-c:4,5-c']bis([1,2,5]thiadiazole) to palladium catalyst in step (1) is preferably 100:2~3, more preferably 100:2.2~2.8, and even more preferably 100:2.4~2.6.

[0030] In this invention, the solvent is used in excess in step (1).

[0031] In this invention, the temperature of the coupling reaction in step (1) is preferably 90~100℃, more preferably 92~98℃, and even more preferably 94~96℃; the time is preferably 8~12h, more preferably 9~11h, and even more preferably 9.5~10h; the coupling reaction is carried out under stirring conditions.

[0032] In this invention, after the coupling reaction in step (1) is completed, the mixture is naturally cooled to room temperature, and the organic phase is collected by extraction with dichloromethane and saturated brine. The organic phase is dried with anhydrous sodium sulfate, and the filtrate is collected by vacuum filtration. After the filtrate is dried by rotary evaporation, the components are separated and purified by silica gel column chromatography. A mixed solvent of petroleum ether and dichloromethane (1:2 v / v) is selected as the eluent to finally obtain intermediate I.

[0033] In this invention, the structure of intermediate I in step (1) is as follows: .

[0034] In this invention, the solvent in step (2) is one or more of N,N-dimethylformamide, 1,4-dioxane, toluene and tetrahydrofuran.

[0035] In this invention, the molar ratio of intermediate I and N-bromosuccinimide in step (2) is preferably 1:1 to 1.2, more preferably 1:1.12 to 1.18, and even more preferably 1:1.14 to 1.16.

[0036] In this invention, the solvent is used in excess in step (2).

[0037] In this invention, the bromination reaction time in step (2) is preferably 12-16 h, more preferably 13-15 h, and even more preferably 13.5-14 h; the temperature is preferably 20-30 °C, more preferably 22-28 °C, and even more preferably 24-26 °C; the bromination reaction is carried out under light-protected and stirred conditions.

[0038] In this invention, after the bromination reaction in step (2) is completed, the organic phase is collected by extraction with dichloromethane and deionized water, dried with anhydrous sodium sulfate, and the filtrate is collected by vacuum filtration. After the filtrate is dried by rotary evaporation, the components are separated and purified by silica gel column chromatography. A mixed solvent of petroleum ether and dichloromethane (3:2 v / v) is selected as the eluent. Finally, an orange-red solid powder is obtained, which is intermediate II.

[0039] In this invention, the structure of intermediate II in step (2) is as follows: .

[0040] In this invention, the protective atmosphere in step (3) is nitrogen, helium, or argon.

[0041] In this invention, the palladium catalyst in step (3) is bis(triphenylphosphine)palladium dichloride and / or tetra(triphenylphosphine)palladium.

[0042] In this invention, the solvent in step (3) is one or more of N,N-dimethylformamide, 1,4-dioxane, toluene and tetrahydrofuran.

[0043] In this invention, the molar ratio of intermediate II and tributyl(2,3-dihydrothiopheno[3,4-b]-[1,4]dioxin-5-yl)stanane in step (3) is preferably 1:2 to 2.1, more preferably 1:2.02 to 2.08, and even more preferably 1:2.04 to 2.06.

[0044] In this invention, the molar ratio of intermediate II and palladium catalyst in step (3) is preferably 100:2~3.1, more preferably 100:2.2~2.8, and even more preferably 100:2.4~2.6.

[0045] In this invention, the solvent is used in excess in step (3).

[0046] In this invention, the temperature of the coupling reaction in step (3) is preferably 90~100℃, more preferably 92~98℃, and even more preferably 94~96℃; the time is preferably 8~12h, more preferably 9~11h, and even more preferably 9.5~10h.

[0047] In this invention, after the reaction in step (3) is completed, the system is naturally cooled to room temperature. The organic phase is collected after extraction with dichloromethane and saturated brine, dried with anhydrous sodium sulfate, and the filtrate is collected by vacuum filtration. After the filtrate is evaporated to dryness, the components are separated and purified by silica gel column chromatography. A mixed solvent of petroleum ether and dichloromethane (1:3 v / v) is used as the eluent to obtain the benzobisthiadiazole derivative.

[0048] The present invention also provides the application of the benzobisthiadiazole derivative in electrochromic materials, smart dimming windows or electrochromic display devices.

[0049] The present invention provides an electrochromic film, wherein the polymer monomer of the electrochromic film is the benzobisthiadiazole derivative.

[0050] This invention provides a method for preparing the electrochromic thin film, comprising the following steps: (a) The benzobisthiadiazole derivative, supporting electrolyte, and solvent are mixed to obtain a polymer electrolyte; (b) The electrochromic film is obtained by electrochemically depositing the polymer electrolyte on the surface of a conductive substrate.

[0051] In this invention, the electrolyte supported in step (a) is lithium perchlorate.

[0052] In this invention, the solvent in step (a) comprises dichloromethane and acetonitrile, and the volume ratio of dichloromethane to acetonitrile is preferably 1:2 to 2.5, more preferably 1:2.1 to 2.4, and even more preferably 1:2.2 to 2.3.

[0053] In this invention, the concentration of the benzobisthiadiazole derivative in the polymerization electrolyte in step (a) is preferably 0.02~0.08 mol / L, more preferably 0.03~0.07 mol / L, and even more preferably 0.04~0.06 mol / L.

[0054] In this invention, the concentration of the supporting electrolyte in the polymerization electrolyte in step (a) is preferably 0.1~0.2 mol / L, more preferably 0.12~0.18 mol / L, and even more preferably 0.14~0.16 mol / L.

[0055] In this invention, the applied potential for electrochemical deposition in step (b) is preferably 1.4~1.5V, more preferably 1.42~1.48V, and even more preferably 1.44~1.46V.

[0056] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0057] Example 1

[0058] The synthetic steps of the benzobisthiadiazole thiophene derivative EDOT-T-BTD are as follows.

[0059] Synthesis of intermediate I:

[0060] Synthetic steps: 1.06 g (3 mmol) of 4,8-dibromobenzo[1,2-c:4,5-c']bis([1,2,5]thiadiazole), 0.86 g (6 mmol) of 2-tributyltinylthiophene, and 80 mg (0.069 mmol) of tetra(triphenylphosphine)palladium were weighed and added to a two-necked round-bottom flask. 25 mL of deoxygenated and dehydrated anhydrous DMF was added under a nitrogen atmosphere. The reaction mixture was stirred continuously at 90 °C for 8 h. After the reaction was complete, the system was allowed to cool naturally to room temperature. The organic phase was extracted three times with dichloromethane and saturated brine, dried thoroughly with anhydrous sodium sulfate, and then filtered under reduced pressure to collect the filtrate. After rotary evaporation, the filtrate was purified by silica gel column chromatography using a mixture of petroleum ether and dichloromethane (1:2 v / v) as the eluent, with a yield of 83%.

[0061] Synthesis of Intermediate II

[0062] Synthetic steps: Intermediate I (1.08 g, 3 mmol) and N-bromosuccinimide (0.44 g, 3 mmol) were weighed separately and added to a two-necked round-bottom flask. 30 mL of tetrahydrofuran was added under light-protected conditions, and the mixture was stirred continuously at room temperature in the dark for 12 h. After the reaction was complete, the organic phase was extracted three times with dichloromethane and deionized water. The organic phase was collected, dried with anhydrous sodium sulfate, and then filtered under reduced pressure to collect the filtrate. The filtrate was evaporated to dryness and then purified by silica gel column chromatography using a mixed solvent of petroleum ether and dichloromethane (3:2 v / v). Finally, an orange-red solid powder was obtained, with a yield of 91%.

[0063] Synthesis of EDOT-T-BTD

[0064] Synthetic steps: Intermediate II (1.04 g, 2 mmol), tributyl(2,3-dihydrothieno[3,4-B]-[1,4]dioxin-5-yl)stanane (1.73 g, 4 mmol), and tetrakis(triphenylphosphine)palladium (71 mg, 0.061 mmol) were weighed and added to a two-necked round-bottom flask. Under a nitrogen atmosphere, 25 mL of anhydrous DMF that had been thoroughly deoxygenated and dehydrated was added. The reaction system was stirred continuously at 90 °C for 10 h. After the reaction was completed, the system was allowed to cool naturally to room temperature. The organic phase was collected after three extractions with dichloromethane and saturated brine. After drying with anhydrous sodium sulfate, the filtrate was collected by vacuum filtration. After the filtrate was evaporated to dryness, the components were separated and purified by silica gel column chromatography. A mixed solvent of petroleum ether and dichloromethane (1:3 v / v) was used as the eluent, and the yield was 85%.

[0065] Preparation of electrochromic thin films

[0066] The target monomer EDOT-T-BTD (0.63 g, 1 mmol) and the supporting electrolyte lithium perchlorate (0.53 g, 5 mmol) were weighed and placed in a 50 mL volumetric flask. A 1:2 volume ratio of dichloromethane / acetonitrile mixed solvent was used as the electrolyte system solvent. The volume was adjusted to the mark, and then ultrasonically dispersed for 30 min until the solid was completely dissolved to prepare a homogeneous electropolymerization electrolyte. A three-electrode system was used to carry out constant potential electrochemical polymerization, in which a 0.9 cm × 4 cm ITO conductive glass was used as the working electrode, a platinum wire as the counter electrode, and an Ag / AgCl saturated electrode as the reference electrode. The constant potential range was controlled at 1.4–1.5 V, and the polymerization deposition time was 20 s.

[0067] After electropolymerization is completed, the ITO substrate with the attached polymer film is removed and thoroughly immersed in pure acetonitrile solvent to rinse it completely, removing unreacted monomers, oligomers and residual lithium salt electrolytes from the film surface. After rinsing, it is placed in room temperature air environment to air dry naturally, and finally a uniform and stable electrochromic functional film is obtained.

[0068] Electrochromic thin film optical performance testing

[0069] Weigh 1.064 g of lithium perchlorate and place it in a 100 mL volumetric flask. Add chromatographic grade acetonitrile to dilute to volume to prepare a blank supporting electrolyte solution. Using a three-electrode testing system, the polymer electrochromic film prepared above was used as the working electrode, a platinum wire electrode as the counter electrode, and an Ag / AgCl electrode as the reference electrode. The UV-Vis absorption spectra and chromaticity coordinates of the film were collected sequentially at different applied potentials from 0 to 1.2 V. The UV-Vis absorption spectra at different voltages are shown below. Figure 1 As shown, the chromaticity diagrams under different voltages are as follows: Figure 2 As shown, from Figure 1 and Figure 2 As can be seen from the spectral data, when the applied potential reaches 1.2 V, the polymer film exhibits characteristic absorption peaks in both the 462 nm visible light band and the 1225 nm near-infrared band, and the color changes from neutral gray to oxidized blue.

[0070] Electrochromic thin film kinetic property testing

[0071] Weigh 1.064 g of lithium perchlorate and place it in a 100 mL volumetric flask. Add chromatographic grade acetonitrile to dilute to volume to prepare a blank supporting electrolyte solution. Using a three-electrode testing system, the polymer electrochromic film prepared above was used as the working electrode, a platinum wire electrode as the counter electrode, and an Ag / AgCl electrode as the reference electrode. The transmittance curves of the polymer film were collected sequentially at different applied potentials from 0 to 1.2 V. The cycling stability measured at 462 nm under a step voltage is as follows: Figure 3 As shown, the response time measured at 462 nm under a step voltage is as follows: Figure 4 As shown, the cycling stability measured at 1225 nm under a step voltage is as follows: Figure 5 As shown, the response time measured at 1225 nm under a step voltage is as follows: Figure 6 As shown, from Figures 3-6 It can be seen that when the applied potential reaches 1.2 V, the polymer film can maintain 64.5% of the original optical contrast after 1000 cycles in the 462 nm visible light band, with a response time of 1.3 s for both coloring and fading. The polymer film can maintain 62% of the original optical contrast after 1000 cycles in the 1225 nm near-infrared band, with a response time of 2 s for coloring and 1.9 s for fading. Therefore, the electrochromic film has good cycling stability and a fast response time.

[0072] As demonstrated by the above embodiments, this invention prepares the target monomer product via Stille coupling reaction, and then prepares an electrochromic film via potentiostatic electrochemical polymerization. This material achieves reversible color change from gray to blue at 1.2 V, and also exhibits a significant absorption peak in the near-infrared region. At a wavelength of 1225 nm, the optical contrast is nearly 30%, with a coloring time of 2 s, a fading time of 1.9 s, and 62% optical contrast remaining after 1000 cycles. At a wavelength of 462 nm, the optical contrast is approximately 15%, with a coloring time of 1.3 s, a fading time of 1.3 s, and 64.5% optical contrast remaining after 1000 cycles. This is a high-performance electrochromic material with promising applications in fields such as smart windows, dynamic anti-counterfeiting, encryption, and energy storage color-changing devices.

[0073] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A benzobisthiadiazole derivative, characterized in that, The structure of the benzobisthiadiazole derivative is shown below: 。 2. The method for preparing the benzobisthiadiazole derivative according to claim 1, characterized in that, Includes the following steps: (1) Under a protective atmosphere, 4,8-dibromobenzo[1,2-c:4,5-c']bis([1,2,5]thiadiazole), 2-tributyltinylthiophene, palladium catalyst and solvent were mixed and coupled to obtain intermediate I; (2) Intermediate I, N-bromosuccinimide and solvent are mixed and subjected to bromination reaction to obtain intermediate II; (3) Under a protective atmosphere, intermediate II, tributyl(2,3-dihydrothiophene[3,4-b]-[1,4]dioxin-5-yl)tinane, palladium catalyst and solvent are mixed and coupled to obtain the benzobisthiadiazole derivative.

3. The method for preparing the benzobisthiadiazole derivative as described in claim 2, characterized in that, In step (1), the palladium catalyst is bis(triphenylphosphine)palladium dichloride and / or tetra(triphenylphosphine)palladium; The solvent in step (1) is one or more of N,N-dimethylformamide, 1,4-dioxane, toluene and tetrahydrofuran; In step (1), the molar ratio of 4,8-dibromobenzo[1,2-c:4,5-c']bis([1,2,5]thiadiazole) to 2-tributyltinylthiophene is 1:2~2.1; In step (1), the molar ratio of 4,8-dibromobenzo[1,2-c:4,5-c']bis([1,2,5]thiadiazole) to palladium catalyst is 100:2~3; The coupling reaction in step (1) is carried out at a temperature of 90~100℃ for 8~12h. The structure of intermediate I in step (1) is as follows: .

4. The method for preparing the benzobisthiadiazole derivative as described in claim 3, characterized in that, The solvent in step (2) is one or more of N,N-dimethylformamide, 1,4-dioxane, toluene and tetrahydrofuran; In step (2), the molar ratio of intermediate I to N-bromosuccinimide is 1:1~1.2; The bromination reaction in step (2) takes 12-16 hours; The structure of intermediate II in step (2) is as follows: .

5. The method for preparing the benzobisthiadiazole derivative as described in claim 4, characterized in that, In step (3), the palladium catalyst is bis(triphenylphosphine)palladium dichloride and / or tetra(triphenylphosphine)palladium; The solvent in step (3) is one or more of N,N-dimethylformamide, 1,4-dioxane, toluene and tetrahydrofuran; In step (3), the molar ratio of intermediate II to tributyl(2,3-dihydrothiopheno[3,4-b]-[1,4]dioxin-5-yl)stanane is 1:2~2.1; In step (3), the molar ratio of intermediate II to palladium catalyst is 100:2~3.1; The coupling reaction in step (3) is carried out at a temperature of 90~100℃ for 8~12h.

6. The application of the benzobisthiadiazole derivative of claim 1 in electrochromic materials, smart dimming windows, or electrochromic display devices.

7. An electrochromic thin film, characterized in that, The polymer monomer of the electrochromic film is the benzobisthiadiazole derivative as described in claim 1.

8. The method for preparing the electrochromic thin film according to claim 7, characterized in that, Includes the following steps: (a) The benzobisthiadiazole derivative, supporting electrolyte, and solvent are mixed to obtain a polymer electrolyte; (b) The electrochromic film is obtained by electrochemically depositing the polymer electrolyte on the surface of a conductive substrate.

9. The method for preparing the electrochromic thin film as described in claim 8, characterized in that, In step (a), lithium perchlorate is supported as the electrolyte; In step (a), the solvent contains dichloromethane and acetonitrile, with a volume ratio of 1:2 to 2.

5. In step (a), the concentration of the benzobisthiadiazole derivative in the polymerization electrolyte is 0.02~0.08 mol / L; In step (a), the concentration of the supporting electrolyte in the polymerization electrolyte is 0.1~0.2 mol / L.

10. The method for preparing the electrochromic thin film as described in claim 9, characterized in that, In step (b), the applied potential for electrochemical deposition is 1.4~1.5V.

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