A ferroelectric-multiple acid coupled long memory composite electrochromic film, a preparation method and application thereof

Abstract

The application provides a ferroelectric-polyacid coupled long memory composite electrochromic film and a preparation method and application thereof, and belongs to the technical field of electrochromic materials and devices. 17 The film is composed of FTO conductive glass, a TiO2 porous framework layer, a P2W 17 V polyacid layer deposited in the framework, and a P(VDF-TrFE) ferroelectric functional layer, wherein the built-in electric field generated by the polarization of the ferroelectric layer is deeply coupled with the polyacid redox process, the charge is effectively locked, the ion diffusion is inhibited, and the limitation of the traditional physical layer stacking is broken. The optical memory time of the prepared film is increased from 489.8 s to 2357.2 s, the bistable performance is significantly enhanced, and the process flow is simple.

Description

Technical Field

[0001] This invention belongs to the field of electrochromic materials and devices, and specifically relates to a ferroelectric-multiacid coupled long memory composite electrochromic thin film, its preparation method and application. Background Technology

[0002] Polyacids (such as P2W) 17 As an inorganic cluster material, polyacid electrochromic materials possess excellent redox activity and diverse color changes. However, traditional polyacid electrochromic materials generally suffer from insufficient optical memory, meaning the film fades rapidly after the applied voltage is removed. In existing technologies, the open-circuit memory time of pure polyacid films in liquid electrolytes is typically short, with transmittance changing significantly (e.g., attenuation exceeding 10%) within tens to 120 seconds after power failure, making it difficult to meet the requirements of low-power displays. Existing improvement methods mainly focus on chemical crosslinking or physical adsorption, which, while improving stability to some extent, have limited effectiveness in extending the optical memory time (i.e., the time it takes to maintain the colored state after power failure). Ferroelectric materials possess unique remanent polarization characteristics, and their built-in electric field is expected to continue acting on the color-changing material after power failure, thereby locking in the color state. Therefore, breaking through the single-structure limitations of traditional polyacid films and developing a ferroelectric-polyacid integrated coupled composite film, utilizing the ferroelectric polarization field between heterogeneous interfaces to regulate the redox state of the polyacid, is of great significance for realizing electrochromic devices with long memory and high stability. Summary of the Invention

[0003] To address the aforementioned problems, this invention provides a long-memory composite electrochromic thin film coupled with ferroelectricity and polyacids, and its preparation method. By constructing an integrated ferroelectricity-polyacid composite structure, the ferroelectric polymer P(VDF-TrFE) and the polyacid P2W are combined... 17 V is tightly bound at the nanoscale. Utilizing the strong built-in electric field generated by the ferropolar polarization characteristics at the interface, the redox of polyacid molecules is deeply coupled, thereby significantly extending the optical memory time of the electrochromic film. At the same time, the integrated and dense configuration effectively prevents ion loss and improves the cycling stability of the film.

[0004] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0005] A method for preparing a ferroelectric-multiacid coupled long-memory composite electrochromic thin film includes the following steps:

[0006] 1) Clean and dry the FTO conductive glass substrate.

[0007] 2) TiO2 paste is coated on the surface of FTO conductive glass by screen printing and then sintered at high temperature to form a porous TiO2 framework.

[0008] 3) Configuration includes P2W 17 Acidic aqueous solution of V was used to test P2W using cyclic voltammetry. 17 V is deposited in the porous TiO2 framework.

[0009] 4) Dissolve P(VDF-TrFE) powder in N,N-dimethylformamide (DMF) solvent to prepare a solution, and spin-coat it onto the FTO conductive glass surface after step 3).

[0010] 5) After spin coating, a graded heat treatment is performed to crystallize P(VDF-TrFE) and form a ferroelectric protective film, while simultaneously reacting with P2W. 17 V-TiO2 forms weak bonds.

[0011] Furthermore, in step 1), the specific cleaning process is as follows: the FTO conductive glass is sequentially immersed in acetone, deionized water and ethanol for ultrasonic cleaning for 30 minutes each, and then dried with nitrogen gas after cleaning.

[0012] Furthermore, in step 2), the coating is applied using a screen printing process, with two printing layers; the specific procedure for the high-temperature sintering is as follows: first, dry at 80°C for 3 minutes, then heat to 450°C and sinter for 30 minutes.

[0013] Furthermore, in step 3), the P2W-containing 17 The method for preparing an acidic aqueous solution of V is as follows: according to 0.1g P2W 17 The solution was mixed with 25 ml of deionized water at a ratio of V, ultrasonically dispersed for 1 minute, then magnetically stirred. Finally, concentrated hydrochloric acid was added dropwise until the solution turned yellow, clear, and transparent. The parameters for the cyclic voltammetry were set as follows: voltage range 0.3 V to -1.0 V, scan rate 100 mV / s, and 30 scan cycles.

[0014] Furthermore, in step 4), the preparation conditions of the P(VDF-TrFE) solution are as follows: magnetic stirring at 80°C for 2 hours until completely dissolved; the mass concentration of the solution is 0.1wt% to 6wt%.

[0015] Furthermore, the spin coating speed and time are set according to the solution concentration as follows: when the solution concentration is 0.1wt%~2wt%, the spin coating speed is 2000r / min and the spin coating time is 30s; when the solution concentration is 4wt%~6wt%, the spin coating speed is 3000r / min and the spin coating time is 30s.

[0016] Furthermore, in step 5), the graded heat treatment specifically includes: after spin coating, pre-drying on a hot plate at 80°C for 5 minutes, and then annealing in an oven at 140°C for 2 hours. The annealing process adopts the method of heating and cooling with the furnace.

[0017] The beneficial effects of this invention are:

[0018] 1. This invention constructs a composite structure with integrated ferroelectric-polyacid coupling. This structure utilizes the unique ferroelectric remanent polarization characteristics of P(VDF-TrFE) as its core mechanism. When a voltage is applied and the color changes, polarization occurs within the composite film; when the external voltage is removed, the strong remanent polarization electric field (built-in electric field) retained within it interacts with the polyacid P2W at the interface. 17 V generates deep coupling. This interfacial coupling can replace an external power source, continuously acting on the polyacid system, effectively increasing the energy barrier, hindering spontaneous electron reflow and oxidative fading of the polyacids, thus acting as an electron lock within the system. Compared to the optical memory time of less than 200 seconds for unmodified polyacid films in the prior art, the composite film of this invention increases the memory time to over 2000 seconds (e.g., 2357.2 s in Example 2), achieving a performance improvement of approximately 10 times. This integrated mechanism fundamentally overcomes the defect of traditional polyacid films fading upon power failure, endowing the film with the ability to maintain its colored state for a long time in the power-off state.

[0019] 2. Benefiting from the ultra-long optical memory brought about by the aforementioned integrated coupling mechanism, the electrochromic composite film prepared in this invention does not require continuous power supply to maintain its colored state; only extremely low-frequency pulse voltages are needed to refresh the state. Compared with traditional films that require continuous pressure to maintain color, this significantly reduces energy consumption and has a remarkable energy-saving advantage. Furthermore, in this integrated configuration, due to the excellent light transmittance and extremely thin thickness of the P(VDF-TrFE) ferroelectric phase, this composite structure significantly enhances the memory effect while still maintaining the high optical contrast and vibrant color change characteristics of the original polyoxometalate material.

[0020] 3. This invention provides a simple and precisely controllable preparation method for the coupling interface. Utilizing the excellent solubility of P(VDF-TrFE) in organic solvents (DMF), the thickness of the ferroelectric functional layer in the composite film can be precisely controlled at the nanometer scale within the range of 5nm to 80nm by adjusting the solution concentration (0.1wt%~4wt%) and the spin-coating process. This thickness control of the integrated structure ensures sufficient coercive voltage (V0) at the interface. c This maintains the strong coupling memory effect while avoiding the problem of excessively high overall driving voltage due to excessively thick insulation layer, thus achieving the optimal balance of comprehensive performance. Attached Figure Description

[0021] Figure 1 This is the UV-Vis spectrum of the ferroelectric-polyacid composite electrochromic film prepared in Example 1 after applying an excitation voltage of 5V for 1s and then turning off the power.

[0022] Figure 2 This is the UV-Vis spectrum of the ferroelectric-polyacid composite electrochromic film prepared in Example 2 after applying an excitation voltage of 5V for 1s and then disconnecting the power.

[0023] Figure 3 This is the UV-Vis spectrum of the ferroelectric-polyacid composite electrochromic film prepared in Example 3 after applying an excitation voltage of 5V for 1s and then disconnecting the power.

[0024] Figure 4 This is the UV-Vis spectrum of the ferroelectric-polyacid composite electrochromic film prepared in Example 4 after applying an excitation voltage of 5V for 1s and then disconnecting the power.

[0025] Figure 5 This is the UV-Vis spectrum of the ferroelectric-polyacid composite electrochromic film prepared in Example 5 after applying an excitation voltage of 5V for 1s and then disconnecting the power.

[0026] Figure 6 This is a test graph showing the long-term cycling stability of the ferroelectric-polyacid composite electrochromic film prepared in Example 1 under UV-Vis light at 600 nm and a two-electrode system with an applied voltage of -1.8V to 1.8V.

[0027] Figure 7 This is a schematic diagram of a long-memory composite electrochromic thin film coupled with ferroelectric and polyacid coupling. Detailed Implementation

[0028] Example 1

[0029] 1. A ferroelectric-multi-acid coupled long-memory composite electrochromic thin film material, with the structure as follows: Figure 7 As shown, it includes an FTO conductive glass substrate, a TiO2 porous framework layer, and a P2W layer. 17 The V-polyacid color-changing layer and the P(VDF-TrFE) ferroelectric functional layer are prepared by a 0.5 wt% P(VDF-TrFE) / DMF solution.

[0030] 2. A method for preparing a ferroelectric-multi-acid coupled long-memory composite electrochromic thin film, specifically including the following steps:

[0031] 1) Cut the FTO glass into 2×3cm pieces, and ultrasonically clean it with acetone, deionized water and ethanol for 30 minutes in sequence, and then blow it dry with N2.

[0032] 2) A TiO2 paste with a purity ≥99.5% was coated on the cleaned FTO glass surface using screen printing technology. Two layers were printed, dried at 80℃ for 3 min, and then sintered at 450℃ for 30 min to obtain a TiO2 porous framework layer.

[0033] 3) Add 0.1g P2W17 Dissolve V in 25 ml of deionized water, sonicate for 1 min, stir magnetically for 20 min, and add concentrated hydrochloric acid dropwise until the solution is yellow, clear, and transparent; immerse the TiO2 porous framework layer in P2W. 17 In an acidic aqueous solution of V, cyclic voltammetry was used with a deposition voltage of 0.3V to -1.0V, a scan rate of 100mV / s, and 30 cycles to deposit P2W. 17 V was deposited in the TiO2 layer, then cleaned and dried;

[0034] 4) Dissolve 0.047g of P(VDF-TrFE) powder in 10mL of DMF, and spin-coat the resulting 0.5wt% solution onto the FTO glass surface loaded with multi-acids. The spin-coating parameters are 2000r / min and 30s.

[0035] 5) After spin coating, pre-dry at 80°C for 5 min, then anneal at 140°C for 2 h to obtain an electrochromic film on the FTO glass surface.

[0036] 3. Performance testing: The FTO glass loaded with the electrochromic film was used as the working electrode and placed in an electrolytic cell containing LiClO4 / PC electrolyte (1M). Ag / AgCl was used as the reference electrode and Pt wire was used as the counter electrode. The three-electrode system was used for testing.

[0037] 4. Test Results: The electrochromic thin film prepared in Example 1 was tested for its memory time after being excited by 5V and then de-energized for 1 second. Figure 1 As shown, the thin film prepared in Example 1 exhibits a relatively long optical memory time after power is turned off, with a memory time of 2357.2 s. Figure 6 As shown, the electrolyte exhibits good cycling stability in LiClO4 / PC electrolyte.

[0038] Example 2

[0039] 1. A ferroelectric-multi-acid coupled long-memory composite electrochromic thin film material, comprising an FTO conductive glass substrate, a TiO2 porous framework layer, and a P2W layer. 17 The V-polyacid color-changing layer and the P(VDF-TrFE) ferroelectric functional layer; the preparation solution of the P(VDF-TrFE) ferroelectric layer is a P(VDF-TrFE) / DMF solution with a mass concentration of 0.1 wt%.

[0040] 2. A method for preparing a ferroelectric-multi-acid coupled long-memory composite electrochromic thin film, specifically including the following steps:

[0041] 1) Cut the FTO glass into 2×3cm pieces, and ultrasonically clean it with acetone, deionized water and ethanol for 30 minutes in sequence, and then blow it dry with N2.

[0042] 2) A TiO2 slurry with a purity of ≥99.5% was coated on the cleaned FTO glass surface using screen printing technology, dried at 80℃ for 3 min, and then sintered at 450℃ for 30 min to obtain a TiO2 porous framework layer.

[0043] 3) Add 0.1g P2W 17 Dissolve V in 25 ml of deionized water, sonicate for 1 min, stir magnetically for 20 min, and add concentrated hydrochloric acid dropwise until the solution is yellow, clear, and transparent; immerse the TiO2 porous framework layer in P2W. 17 In an acidic aqueous solution of V, cyclic voltammetry was used with a deposition voltage of 0.3V to -1.0V, a scan rate of 100mV / s, and 30 cycles to deposit P2W. 17 V was deposited in the TiO2 layer, then cleaned and dried;

[0044] 4) Dissolve 0.01g of P(VDF-TrFE) powder in 10mL of DMF, and spin-coat the resulting 0.1wt% solution onto the FTO glass surface loaded with multiple acids. The spin-coating parameters are 2000r / min and 30s.

[0045] 5) After spin coating, pre-dry at 80°C for 5 min, then anneal at 140°C for 2 h to obtain an electrochromic film on the FTO glass surface.

[0046] 3. Performance testing: The FTO glass loaded with the electrochromic film was used as the working electrode and placed in an electrolytic cell containing LiClO4 / PC electrolyte (1M). Ag / AgCl was used as the reference electrode and Pt wire was used as the counter electrode. The three-electrode system was used for testing.

[0047] 4. Test Results: The electrochromic thin film prepared in Example 2 was tested for its memory time after being excited by 5V and then de-energized for 1 second. Figure 2 As shown, the film prepared in Example 2 has a memory time of 1633.8s after power failure.

[0048] Example 3

[0049] 1. A ferroelectric-multi-acid coupled long-memory composite electrochromic thin film material, comprising an FTO conductive glass substrate, a TiO2 porous framework layer, and a P2W layer. 17 The V-polyacid color-changing layer and the P(VDF-TrFE) ferroelectric functional layer; the preparation solution of the P(VDF-TrFE) ferroelectric layer is a 1wt% P(VDF-TrFE) / DMF solution.

[0050] 2. A method for preparing a ferroelectric-multi-acid coupled long-memory composite electrochromic thin film, specifically including the following steps:

[0051] 1) Cut the FTO glass into 2×3cm pieces, and ultrasonically clean it with acetone, deionized water and ethanol for 30 minutes in sequence, and then blow it dry with N2.

[0052] 2) A TiO2 slurry with a purity of ≥99.5% was coated on the cleaned FTO glass surface using screen printing technology, dried at 80℃ for 3 min, and then sintered at 450℃ for 30 min to obtain a TiO2 porous framework layer.

[0053] 3) Add 0.1g P2W 17 Dissolve V in 25 ml of deionized water, sonicate for 1 min, stir magnetically for 20 min, and add concentrated hydrochloric acid dropwise until the solution is yellow, clear, and transparent; immerse the TiO2 porous framework layer in P2W. 17 In an acidic aqueous solution of V, cyclic voltammetry was used with a deposition voltage of 0.3V to -1.0V, a scan rate of 100mV / s, and 30 cycles to deposit P2W. 17 V was deposited in the TiO2 layer, then cleaned and dried;

[0054] 4) Dissolve 0.095g of P(VDF-TrFE) powder in 10mL of DMF, and spin-coat the resulting 1wt% solution onto the FTO glass surface loaded with multi-acids. The spin-coating parameters are 2000r / min and 30s.

[0055] 5) After spin coating, pre-dry at 80°C for 5 min, then anneal at 140°C for 2 h to obtain an electrochromic film on the FTO glass surface.

[0056] 3. Performance testing: The FTO glass loaded with the electrochromic film was used as the working electrode and placed in an electrolytic cell containing LiClO4 / PC electrolyte (1M). Ag / AgCl was used as the reference electrode and Pt wire was used as the counter electrode. The three-electrode system was used for testing.

[0057] 4. Test Results: The electrochromic thin film prepared in Example 3 was tested for its memory time after being excited by 5V and then de-energized for 1 second. Figure 3 As shown, the film prepared in Example 3 has a memory time of 1505s after power failure.

[0058] Example 4

[0059] 1. A ferroelectric-multi-acid coupled long-memory composite electrochromic thin film material, comprising an FTO conductive glass substrate, a TiO2 porous framework layer, and a P2W layer. 17 The V-polyacid color-changing layer and the P(VDF-TrFE) ferroelectric functional layer; the preparation solution of the P(VDF-TrFE) ferroelectric layer is a 2wt% P(VDF-TrFE) / DMF solution.

[0060] 2. A method for preparing a ferroelectric-multi-acid coupled long-memory composite electrochromic thin film, specifically including the following steps:

[0061] 1) Cut the FTO glass into 2×3cm pieces, and ultrasonically clean it with acetone, deionized water and ethanol for 30 minutes in sequence, and then blow it dry with N2.

[0062] 2) A TiO2 slurry with a purity of ≥99.5% was coated on the cleaned FTO glass surface using screen printing technology, dried at 80℃ for 3 min, and then sintered at 450℃ for 30 min to obtain a TiO2 porous framework layer.

[0063] 3) Add 0.1g P2W 17 Dissolve V in 25 ml of deionized water, sonicate for 1 min, stir magnetically for 20 min, and add concentrated hydrochloric acid dropwise until the solution is yellow, clear, and transparent; immerse the TiO2 porous framework layer in P2W. 17 In an acidic aqueous solution of V, cyclic voltammetry was used with a deposition voltage of 0.3V to -1.0V, a scan rate of 100mV / s, and 30 cycles to deposit P2W. 17 V was deposited in the TiO2 layer, then cleaned and dried;

[0064] 4) Dissolve 0.193g of P(VDF-TrFE) powder in 10mL of DMF, and spin-coat the resulting 2wt% solution onto the FTO glass surface loaded with multiple acids. The spin-coating parameters are 2000r / min and 30s.

[0065] 5) After spin coating, pre-dry at 80°C for 5 min, then anneal at 140°C for 2 h to obtain an electrochromic film on the FTO glass surface.

[0066] 3. Performance testing: The FTO glass loaded with the electrochromic film was used as the working electrode and placed in an electrolytic cell containing LiClO4 / PC electrolyte (1M). Ag / AgCl was used as the reference electrode and Pt wire was used as the counter electrode. The three-electrode system was used for testing.

[0067] 4. Test Results: The electrochromic thin film prepared in Example 4 was tested for its memory time after being excited by 5V and then de-energized for 1 second. Figure 4 As shown, the film prepared in Example 4 has a memory time of 785.2 s after power failure.

[0068] Example 5

[0069] 1. A ferroelectric-multi-acid coupled long-memory composite electrochromic thin film material, comprising an FTO conductive glass substrate, a TiO2 porous framework layer, and a P2W layer. 17The V-polyacid color-changing layer and the P(VDF-TrFE) ferroelectric functional layer are prepared by a 4wt% P(VDF-TrFE) / DMF solution.

[0070] 2. A method for preparing a ferroelectric-multi-acid coupled long-memory composite electrochromic thin film, specifically including the following steps:

[0071] 1) Cut the FTO glass into 2×3cm pieces, and ultrasonically clean it with acetone, deionized water and ethanol for 30 minutes in sequence, and then blow it dry with N2.

[0072] 2) A TiO2 slurry with a purity of ≥99.5% was coated on the cleaned FTO glass surface using screen printing technology, dried at 80℃ for 3 min, and then sintered at 450℃ for 30 min to obtain a TiO2 porous framework layer.

[0073] 3) Add 0.1g P2W 17 Dissolve V in 25 ml of deionized water, sonicate for 1 min, stir magnetically for 20 min, and add concentrated hydrochloric acid dropwise until the solution is yellow, clear, and transparent; immerse the TiO2 porous framework layer in P2W. 17 In an acidic aqueous solution of V, cyclic voltammetry was used with a deposition voltage of 0.3V to -1.0V, a scan rate of 100mV / s, and 30 cycles to deposit P2W. 17 V was deposited in the TiO2 layer, then cleaned and dried;

[0074] 4) Dissolve 0.393g of P(VDF-TrFE) powder in 10mL of DMF, and spin-coat the resulting 4wt% solution onto the FTO glass surface loaded with multi-acids. The spin-coating parameters are 2000r / min and 30s.

[0075] 5) After spin coating, pre-dry at 80°C for 5 min, then anneal at 140°C for 2 h to obtain an electrochromic film on the FTO glass surface.

[0076] 3. Performance testing: The FTO glass loaded with the electrochromic film was used as the working electrode and placed in an electrolytic cell containing LiClO4 / PC electrolyte (1M). Ag / AgCl was used as the reference electrode and Pt wire was used as the counter electrode. The three-electrode system was used for testing.

[0077] 4. Test Results: The electrochromic thin film prepared in Example 5 was tested for its memory time after being excited by 5V and then de-energized for 1 second. Figure 5 As shown, the film prepared in Example 5 has a memory time of 562.4 s after power failure.

[0078] As can be seen from the above examples, Example 1 (0.5wt% P(VDF-TrFE)) exhibits a longer optical memory time compared to Examples 2-5. Specifically, the memory time of pure polyacid films reported in existing literature is typically between 60 and 200 seconds; the memory time has been increased to 489.8 s through the physical adsorption effect of the TiO2 porous framework; and after further introducing a ferroelectric layer in Example 1, the memory time is remarkably extended to 2357.2 s. This indicates that by utilizing the physical encapsulation of the P(VDF-TrFE) ferroelectric layer surface and the internal residual polarization electric field locking mechanism, not only has the bottleneck of short memory time in polyacid materials in the industry been significantly overcome, but the P2W of polyacids can also be prevented. 17 V detaches during cycling and maintains its reduced state, thereby improving the cycling stability and memory effect of the electrochromic film.

Claims

1. A ferroelectric-multiacid coupled long-memory composite electrochromic thin film, characterized in that, The thin film has an integrated structure, comprising, in sequence, an FTO conductive glass substrate, a TiO2 porous framework layer, and P2W deposited in the framework. 17 The V polyacid color-changing layer and the P(VDF-TrFE) ferroelectric functional layer that forms a polarization coupling interface with it.

2. A method for preparing a long-memory composite electrochromic thin film with ferroelectric-polyacid coupling as described in claim 1, characterized in that, Includes the following steps: 1) Clean and dry the FTO conductive glass substrate; 2) A TiO2 slurry is coated on the surface of FTO conductive glass and then sintered at high temperature to form a porous TiO2 framework layer; 3) Configuration includes P2W 17 Acidic aqueous solution of V was used to test P2W using cyclic voltammetry. 17 V is deposited in the porous TiO2 framework to form P2W 17 V-polyacid color-changing layer; 4) Dissolve P(VDF-TrFE) powder in N,N-dimethylformamide solvent to prepare a solution, and spin-coat it onto the FTO conductive glass surface treated in step 3); 5) After spin coating, graded heat treatment is performed to crystallize P(VDF-TrFE) and construct a ferroelectric coupling functional layer that is tightly bonded to the polyacid layer, thus obtaining a long memory composite electrochromic film with ferroelectric-polyacid coupling.

3. The method for preparing a ferroelectric-multiacid coupled long-memory composite electrochromic thin film according to claim 2, characterized in that, In step 1), the specific cleaning process is as follows: the FTO conductive glass is immersed in acetone, deionized water and ethanol in sequence and ultrasonically cleaned for 30 minutes each. After cleaning, it is dried with nitrogen gas.

4. The method for preparing a ferroelectric-multiacid coupled long-memory composite electrochromic thin film according to claim 2, characterized in that, In step 2), the TiO2 coating slurry is printed using a screen printing process, with two layers printed. The specific procedure for the high-temperature sintering is as follows: first, dry at 80°C for 3 minutes, then heat to 450°C and sinter for 30 minutes.

5. The method for preparing a ferroelectric-multiacid coupled long-memory composite electrochromic thin film according to claim 2, characterized in that, In step 3), the P2W-containing 17 The method for preparing an acidic aqueous solution of V is as follows: according to 0.1g P2W 17 Mix V with 25ml of deionized water, sonicate for 1 minute, stir magnetically, and finally add concentrated hydrochloric acid until the solution turns yellow, clear and transparent.

6. The method for preparing a ferroelectric-multiacid coupled long-memory composite electrochromic thin film according to claim 2, characterized in that, In step 3), the parameters of the cyclic voltammetry are set as follows: voltage range 0.3V to -1.0V, scan speed 100mV / s, and number of scans 30.

7. The method for preparing a ferroelectric-multiacid coupled long-memory composite electrochromic thin film according to claim 2, characterized in that, In step 4), the preparation conditions for the P(VDF-TrFE) solution are as follows: magnetic stirring at 80°C for 2 hours. Dissolved completely; the mass concentration of the solution is from 0.1 wt% to 6 wt%.

8. The method for preparing a ferroelectric-multiacid coupled long-memory composite electrochromic thin film according to claim 7, characterized in that, In step 4), the spin coating speed and time are set according to the solution concentration as follows: when the solution concentration is 0.1wt%~2wt%, the spin coating speed is 2000r / min and the spin coating time is 30s; when the solution concentration is 4wt%~6wt%, the spin coating speed is 3000r / min and the spin coating time is 30s.

9. The method for preparing a ferroelectric-multiacid coupled long-memory composite electrochromic thin film according to claim 2, characterized in that, In step 5), the graded heat treatment specifically includes: after spin coating, pre-drying on a hot plate at 80°C for 5 minutes, and then annealing in an oven at 140°C for 2 hours. The annealing process adopts the method of heating and cooling with the furnace.

10. The application of the ferroelectric-polyacid coupled long-memory composite electrochromic thin film of claim 1 in the preparation of long-time photoelectric electrochromic devices.

Images