Transparent conductive material, preparation method thereof and application of transparent conductive material in electrochromic device

Abstract

The invention provides a transparent conductive material, a preparation method thereof and application of the transparent conductive material in an electrochromic device. The transparent conductive material comprises a transparent conductive glass substrate and ITO nano conductive fibers deposited on the surface of the transparent conductive glass substrate; the ITO nano conductive fiber is obtained by reacting an indium source and a tin source through a spinning method and then calcining at high temperature; the preparation method of the ITO nano conductive fiber comprises the following steps: reacting a spinning solution containing an indium source and a tin source through a spinning method to obtain an ITO nano fiber precursor, and calcining at high temperature to obtain the ITO nano conductive fiber. The ITO nano conductive fiber with the advantages of high conductivity, high specific surface area, high electrochemical stability and the like is deposited on the surface of the transparent glass substrate through a spinning method, the obtained ITO nano fiber has the characteristics of transparency and conductivity, and a two-dimensional transparent glass substrate material is converted into a three-dimensional structure; therefore, the material can be directly applied to an electrochromic device as an electrode layer.

Description

Technical Field

[0001] The present invention relates to the technical field of conductive glass, and particularly to a transparent conductive material, a preparation method thereof, and an application thereof in an electrochromic device. Background Art

[0002] Electrochromism refers to the phenomenon that under the condition of applying a certain external electric field, through the co-injection and extraction of ions and electrons in the electrochromic layer, the optical properties of the material undergo stable and reversible changes. Electrochromic materials, as a type of intelligent material that can reversibly switch optical properties (such as color, transmittance, reflectance, etc.) under the action of an electric field, have shown important application values in fields such as dimming glass, light absorption display, smart wearables, energy storage, and military camouflage. Especially in the display field, the display module based on electrochromic materials almost has all the important characteristics of the next-generation displays (such as transparent display, flexible wearable display, etc.), such as rich colors, low energy consumption, flexible and bendable, transparent, ultra-thin, and wide viewing angle. Therefore, electrochromic display technology is regarded as an important candidate for future reflective (non-emissive) display technology, and the development of electrochromic displays has become an important development direction in the display field. However, although electrochromic-related technical problems, such as improving the purity and depth of color switching, increasing color diversity, and improving the device preparation process, have been gradually overcome, the problem of slow response speed of electrochromic display devices still plagues the development of electrochromic technology, and thus restricts its application in display products.

[0003] According to the optical switching principle of electrochromic materials, the redox characteristics of the material itself, the interfacial electron transfer efficiency between the electrode and the electrochromic material, and the ion transport efficiency are important factors affecting the response speed of the material. To improve the performance of electrochromic devices, the conventional method is generally to design and synthesize new high-performance electrochromic materials. However, this method usually involves complex structure design and long-term performance optimization, resulting in the complexity of the research process and the increase in development costs.

[0004] A typical electrochromic device consists of five layers, namely a bottom transparent conductive layer, an electrochromic layer, an ion transport layer, an ion storage layer, and a top transparent conductive layer. The two transparent conductive layers of the bottom transparent conductive layer and the top transparent conductive layer are usually ITO / FTO, nano metal wires, conductive polymers, carbon nanorods, etc.; the electrochromic layer materials are WO 3 、polythiophene compounds, etc.; the ion storage layer provides or accepts the ions migrating during the color change process to maintain the electrical balance inside the device, and the materials are NiO, TiO 2 -CeO 2Systems, etc.; an ion transport layer, also known as an electrolyte layer, is located between the electrochromic layer and the ion storage layer, which not only plays a role in ion transport but also acts as an electron insulator to prevent short circuits between the upper and lower electrodes.

[0005] Improving the interfacial electron transfer efficiency between the electrode and the electrochromic material is an effective method to enhance the response speed of electrochromic devices. Shortening the distance of electron / ion transport is also a key factor in optimizing the interfacial electron transfer efficiency and improving the device response speed. For traditional two-dimensional conductive transparent thin film electrodes (such as ITO and FTO), electrons first transport from the electrode surface to the surface of the solid electrochromic thin film and then to the electrochromic material inside the functional thin film. The long electron transport distance limits the electron transfer efficiency and restricts the device response speed. In recent years, conductive materials with nanostructures have unique advantages when applied to electrochromic devices due to their high conductivity, large specific surface area, excellent transparency, as well as advantages such as low-cost preparation and easy modification. Especially one-dimensional nanofiber-like conductive materials, which have characteristics such as a large specific surface area and high porosity, are beneficial to increasing the contact area between the transparent electrode and the electrochromic material when applied to electrochromic devices. At the same time, they shorten the transport distance of electrons and ions, promote the progress of electrochemical reactions, and thus improve the response speed of electrochromic devices. For example, Chinese Patent CN105174303A discloses a method for preparing ITO hollow micro-nanofibers. The mixture of In(NO 3 ) 3 ·4.5H 2 O and SnCl 4 ·5H 2 O is added to water and dissolved, and then polyvinylpyrrolidone is added to make a spinning solution for spinning. The obtained composite fibers are placed in a muffle furnace and heated to 600 - 800 °C at a rate of 1 °C / min for calcination to obtain ITO hollow micro-nanofibers. The prepared micro-nanofibers have the characteristics of high throughput and are applied in fields such as sensors. However, due to the resulting hollow structure, their conductivity is extremely poor and they cannot be applied to the field of electrochromic devices. Another example is that Chinese Patent CN103484974A discloses a method for preparing indium tin oxide with a nanofiber and nano-octahedron bipolar structure. A spinning solution containing an indium source and a tin source is prepared into composite nanofibers by electrospinning, and then indium tin oxide with a nanofiber and nano-octahedron bipolar structure is obtained through high-temperature calcination. The indium tin oxide fiber is used as the backbone, and indium tin oxide nano-octahedron particles are attached to the surface. The nano-octahedron particles have a perfect crystal structure and fast optoelectronic transport properties.

[0006] Based on this, the present invention proposes a fast-response electrochromic device on the basis of the prior art. Based on the spinning technology of the prior art, a high-performance conductive nanofiber is deposited on the surface of transparent conductive glass and applied to the electrochromic device, thereby effectively shortening the distance of electron transmission and improving the response speed of the device. It is expected to break through the technical bottleneck of existing electrochromic devices that are difficult to apply in the display field due to their slow response speed. Summary of the invention

[0007] In order to solve the above problems, the present invention provides a fast-response electrochromic device and a preparation method thereof.

[0008] In order to achieve the above object, the present invention provides a transparent conductive material, which is a transparent glass substrate on which ITO nano-conductive fibers are deposited; the ITO nano-conductive fibers are a transparent conductive three-dimensional electrode deposited from an indium source and a tin source.

[0009] Preferably, the preparation method of the ITO nano conductive fiber includes: adding an indium source and a tin source to an organic mixed solvent, dissolving and mixing them evenly, and then adding polyvinyl pyrrolidone to obtain a spinning solution; reacting the spinning solution by a spinning method to obtain an ITO nanofiber precursor, and depositing it on the surface of a transparent substrate glass; and finally obtaining the transparent conductive material after high-temperature calcination.

[0010] Preferably, the indium source is indium nitrate; the tin source is stannous chloride;

[0011] Preferably, the molar ratio of indium atoms in the indium source to tin atoms in the tin source is 7:3 to 9:1.

[0012] Most preferably, the molar ratio of indium atoms in the indium source to tin atoms in the tin source is 9:1.

[0013] Preferably, the organic mixed solvent is a mixed solution of N,N-dimethylformamide and a low boiling point organic solvent.

[0014] More preferably, the volume ratio of N,N-dimethylformamide to the low boiling point organic solvent is 2:1 to 1:2; most preferably, the volume ratio of N,N-dimethylformamide to the low boiling point organic solvent is 7:9.

[0015] Preferably, the transparent substrate material is any one of ITO glass, FTO glass or PET-ITO glass.

[0016] Preferably, the spinning technology includes any one of electrospinning, wet spinning and melt spinning.

[0017] Preferably, the conditions for the high-temperature calcination include using a programmed temperature increase method; first, the temperature is increased to 180 - 220°C at a rate of 1 - 3°C / min, maintained at this temperature for 0.5 - 1.5 hours, then the temperature is increased to 500 - 550°C at a rate of 1 - 3°C / min and maintained for 1.5 - 2.5 hours; finally, it is naturally cooled to room temperature; sufficient calcination is carried out above 500 degrees to obtain the ITO structure.

[0018] Preferably, after high-temperature calcination, the obtained indium tin oxide nanofibers have lengths ranging from a few micrometers to several meters, and the fiber diameters are 100 - 800 nanometers.

[0019] Preferably, the area of the ITO nano-conductive fiber is 4.5 - 70 square centimeters.

[0020] More preferably, the area of the ITO nano-conductive fiber is 4.5 - 12 square centimeters.

[0021] As one of the objects of the invention, the present invention also provides a fast-response electrochromic device, comprising: a five-layer structure consisting of a first transparent conductive layer - an electrochromic layer - an ion conduction layer - an ion storage layer - a second transparent conductive layer; both the first transparent conductive layer and the second transparent conductive layer are transparent conductive three-dimensional electrodes; the first transparent conductive layer and the second transparent conductive layer are the transparent conductive materials described above.

[0022] Preferably, the thickness of the nanofibers deposited on the surface of the transparent substrate material is 0.1 - 10 micrometers.

[0023] Preferably, the thickness of the electrochromic layer is 1 - 20 micrometers.

[0024] Preferably, the thickness of the ion transport layer is 1 - 100 micrometers.

[0025] Preferably, the thickness of the ion storage layer is 1 - 20 micrometers.

[0026] Preferably, the coloring time of the fast-response electrochromic device is ≤1 s, and the fading time is ≤0.9 s.

[0027] As one of the objects of the invention, the present invention also provides a preparation method for the aforementioned fast-response electrochromic device, comprising the following steps:

[0028] S1. Provide a spinning solution;

[0029] S2. Provide a transparent substrate glass;

[0030] S3. React the spinning solution by a spinning method to obtain an ITO nanofiber precursor and deposit it on the surface of the transparent substrate glass;

[0031] S4. Calcinate the transparent substrate glass obtained in S3 to obtain the first transparent conductive layer;

[0032] S5. Repeat steps S1 to S4 to obtain the second transparent conductive layer;

[0033] S6. Use the first transparent conductive layer as the working electrode, and sequentially coat an ion conduction layer and an ion storage layer on the surface of the first transparent conductive layer;

[0034] Use the second transparent conductive layer as the counter electrode, and coat an electrochromic layer on the surface of the second transparent conductive layer;

[0035] S7. Assemble the multilayer structures separately prepared in S6, and then perform device encapsulation to obtain the electrochromic device.

[0036] Preferably, the composition of the electrochromic layer: 2 - 4 g of PMMA (polymethyl methacrylate), 1 - 2 mL of [BMIM]PF 6 (1-butyl-3-methylimidazolium hexafluorophosphate), 0.01 - 0.1 mol / L of p-BQ (p-benzoquinone), 0.001 - 0.01 mol / L of fluorescein, 20 mL of CH 3 CN (acetonitrile).

[0037] As a preferred embodiment, the composition of the electrochromic layer includes 3.5 g of polymethyl methacrylate, 1.7 mL of [BMIM]PF 6 (1-butyl-3-methylimidazolium hexafluorophosphate), 0.05 mol / L of p-BQ (p-benzoquinone), 0.005 mol / L of fluorescein, 20 mL of CH 3 CN.

[0038] Preferably, the composition of the ion storage layer: 2 - 4 g of PMMA, 1 - 2 mL of [BMIM]PF 6 , 0.01 - 0.1 mol / L of p-BQ, 0.01 - 0.5 mol / L of hydroquinone, and 20 mL of CH 3 CN.

[0039] As a preferred embodiment, the ion conductive layer: 3.5 g of PMMA, 1.7 mL of [BMIM]PF 6 and 20 mL of CH 3 CN.

[0040] Preferably, the ion conductive layer: 2 - 4 g of PMMA, 1 - 2 mL of [BMIM]PF 6 and 20 mL of CH 3 CN.

[0041] As a preferred embodiment, the composition of the ion storage layer: 3.5 g of PMMA, 1.7 mL of [BMIM]PF 6 , 0.05 mol / L of p-BQ, 0.1 mol / L of hydroquinone and 20 mL of CH 3 CN.

[0042] Preferably, the coating method in S6 includes any one of spin coating and blade coating;

[0043] Preferably, in S7, the encapsulation method is one of ultraviolet curing and silicone potting.

[0044] The beneficial technical effects obtained by the present invention:

[0045] 1. By adopting the technical solution of the present invention, ITO nano-conductive fibers with advantages such as high conductivity, high specific surface area, and high electrochemical stability are deposited on the surface of a transparent conductive glass substrate by a spinning method, and the obtained ITO nano-fibers have a transparent and conductive three-dimensional structure, endowing the two-dimensional transparent glass substrate material with a three-dimensional structure, so that it can be directly applied as an electrode layer in electrochromic devices.

[0046] 2. By introducing conductive nano-fibers on the surface of the transparent substrate glass in the present invention, its high conductivity and high specific surface area can shorten the distance of electron transfer, thereby improving the interfacial electron transfer efficiency of the device, and effectively improving the response speed of the device. The coloring time of the prepared fast-response electrochromic device is ≤1 s, and the fading time is ≤1.6 s.

[0047] 3. Compared with the prior art, the electrochromic device provided by the present invention has a lower working voltage and time when achieving the same absorbance change, reducing the probability of side reactions occurring during the electrochemical oxidation-reduction process of the device, and the stability is also improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 It is a schematic diagram of the simulated structure of the electrochromic device based on conductive nano-materials provided by the present invention.

[0049] Figure 2 It is a schematic diagram of the structure of the electrochromic device prepared in Example 1 of the present invention.

[0050] Figure 3 It is a schematic diagram of the preparation process of the conductive nano-fibers provided by the present invention.

[0051] Figure 4 It is a schematic diagram of the preparation process of the electrochromic device provided in Example 1 of the present invention.

[0052] Figures 5a - 5bSEM photos of ITO nanofibers provided in Example 1 of the present invention at different magnifications.

[0053] Figure 5c TEM photo of the ITO nanofibers provided in Example 1 of the present invention.

[0054] Figures 6a - 6c Comparison charts of the optical properties, response time, and number of cycles of the electrochromic devices prepared in Example 1 and Comparative Example 1 of the present invention respectively.

[0055] Figure 7 Comparison of the response speeds of electrochromic devices based on conductive nanofiber electrodes with different thicknesses.

[0056] Figure 8 Comparison of the response speeds of electrochromic devices based on conductive nanofiber electrodes with different areas.

[0057] Figure 9 I-V curves of the electrochromic devices prepared based on the conductive nanofibers provided in Example 1 and Examples 9 - 10 of the present invention. Detailed implementation manners

[0058] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of this application. Obviously,

[0059] The described embodiments are some, but not all, of the embodiments of this application.

[0060] Based on the technical problem of the slow response speed of electrochromic devices in the prior art, by introducing conductive nanofibers with characteristics such as high conductivity, large specific surface area, and excellent electrochemical stability on the electrode surface, the distance of electron transfer is shortened, and the interfacial electron transfer efficiency of the device is improved, thereby effectively improving the response speed of the device. At the same time, since the working voltage of the device is reduced when the same absorbance change is achieved, the probability of side reactions generated during the electrochemical oxidation-reduction process of the device is reduced, and the stability is also improved.

[0061] The structure of the fast-response electrochromic device provided by the present invention is as Figure 1 shown. By introducing conductive nanofibers on the surface of a two-dimensional planar electrode, such as ITO (indium tin oxide), FTO (fluorine-doped tin dioxide) glass, etc., the effective area of the electrode is effectively expanded.

[0062] Preferably, the two-dimensional planar electrode selects FTO as the substrate.

[0063] The FTO electrode has good thermal stability compared to the ITO electrode, and its electrical conductivity will not be affected during the calcination process. Therefore, FTO is selected as the substrate.

[0064] In the present invention, the conductive nanofibers are prepared by a spinning technique.

[0065] Refer to Figure 3 , through the spinning technique, and then combined with a post-treatment process to deposit conductive nanofibers on the surface of the two-dimensional planar electrode.

[0066] As a preferred embodiment, the conductive nanofibers can be any one of electrospinning, wet spinning, melt spinning, etc.

[0067] Preferably, the conductive nanofibers are conductive fiber materials, such as ITO, etc.

[0068] The post-treatment process includes methods such as drying and calcination.

[0069] The two-dimensional planar electrode includes but is not limited to ITO glass, FTO glass, PET-ITO, etc.

[0070] As one of the preferred embodiments, the thickness of the electrochromic layer is 1 to 20 microns.

[0071] As one of the preferred embodiments, the thickness of the ion-conductive layer is 1 to 100 microns.

[0072] After depositing the conductive nanofibers on the surface of the two-dimensional planar electrode by using the technical solution of the present invention, an electrochromic device is further prepared on the surface of the nanofibers by a coating method. The introduced conductive nanofibers can serve as an electron channel, effectively shortening the distance of electron transmission and simultaneously increasing the transmission speed of electrons in the functional film layer.

[0073] Based on the above characteristics, the response speed of the electrochromic device is significantly improved, the coloring time ≤ 1 s, and the fading time ≤ 0.9 s. The technical solution of the present invention will be further described in detail below through specific examples.

[0074] Example 1

[0075] This example provides a method for fabricating an electrochromic device based on the electrospinning technique, and the specific steps are as follows:

[0076] (1) Preparation of conductive nanofibers:

[0077] Configuration of the spinning solution: Weigh 1.45 g of In(NO 3 ) 3 ·4H 2 O (indium nitrate tetrahydrate), and at the same time combine it with In(NO 3 ) 3 with a molar ratio of 9:1 of SnCl2 ·2H 2 O (stannous dichloride dihydrate) was added to a mixed solvent of 7 mL of DMF (N,N-dimethylformamide) and 9 mL of anhydrous C 2 H 5 OH (ethanol), and stirred until dissolved. Then, 1.5 g of PVP (polyvinylpyrrolidone) was added and stirred at 45 °C until dissolved to obtain a colorless, clear and transparent solution, which was the spinning solution.

[0078] Electrospinning: The spinning solution prepared by the above method was loaded into a 1 mL syringe, the needle size was 21#, the positive voltage for spinning was +15 kV, the negative voltage was -2.5 kV, the distance between the needle and the receiving plate was set to 15 cm, the liquid discharge rate was controlled at 1 mL / h, and the receiving plate was an FTO glass electrode; in this example, the thickness of the nanofibers deposited on the electrode was controlled by controlling the spinning time.

[0079] Calcination: The FTO glass deposited with the ITO nanofiber precursor was placed in a muffle furnace, and the calcination conditions were as follows: first, it was heated to 200 °C at a rate of 2 °C / min and maintained at this temperature for 1 hour, then heated to 520 °C at a rate of 1 °C / min and maintained at this temperature for 2 hours, and finally cooled to room temperature naturally after the program ended, and ITO (indium tin oxide) conductive nanofibers could be prepared on the electrode surface. The thickness of the ITO conductive nanofibers was 0.5 microns, and the area of the ITO conductive nanofibers was 11.23 square centimeters.

[0080] See Figure 5a 、 Figure 5b are SEM photos of different magnifications of the morphology of ITO nanofibers, Figure 5c is a TEM photo of the morphology of ITO nanofibers; as can be seen from the figure, the ITO nanofibers exhibit a porous network structure, with a diameter of 200 - 500 nanometers and a length of more than 20 microns. It can be seen from the TEM that the nanofibers are composed of nanoscale grains.

[0081] (2) Fabrication of electrochromic devices

[0082] Solution preparation: The components of the electrochromic layer material include: 3.5 g of PMMA (polymethyl methacrylate), 1.7 mL of [BMIM]PF 6 (1-butyl-3-methylimidazolium hexafluorophosphate), 0.05 mol / L p-BQ (p-benzoquinone), 0.005 mol / L Flu (fluorescein), 20 mL of CH 3 CN (acetonitrile); the components of the ion storage layer: 3.5 g of PMMA, 1.7 mL of [BMIM]PF 6 , 0.05 mol / L p-BQ, 0.1 mol / L HQ (hydroquinone), 20 mL of CH3 CN; Ionic conductive layer: 3.5 g PMMA, 1.7 mL [BMIM]PF 6 , 20 mL CH 3 CN.

[0083] The device was prepared by the doctor - blade method, which specifically included: The conductive electrode used an FTO glass electrode modified with ITO nanofibers. First, the electrochromic layer was doctor - bladed on the working electrode with a thickness of 2 microns; then, the ion storage layer was doctor - bladed on the counter electrode with a thickness of 2 microns; afterwards, the ion conductive layer was doctor - bladed on the surface of the ion storage layer with a thickness of 30 microns; after the solvent evaporated, the working electrode and the counter electrode were assembled together to obtain a solid - state electrochromic device.

[0084] The device based on two FTO glass electrodes modified with ITO nanofibers was an FTO - 3D device.

[0085] (3) Testing of electrochromic performance: The optical performance and electro - response performance of the FTO - 3D device were tested, and the results are shown in Figures 6a - 6c .

[0086] Example 2

[0087] The difference between this example and Example 1 was only that: the thickness of the conductive nanofibers was different. By controlling the spinning time, the thickness of the nanofibers could be obtained as 2.1 microns.

[0088] Example 3

[0089] The difference between this example and Example 1 was only that: the thickness of the conductive nanofibers was different. By controlling the spinning time, the thickness of the nanofibers could be obtained as 3.9 microns.

[0090] Example 4

[0091] The difference between this example and Example 1 was only that: the thickness of the conductive nanofibers was different. By controlling the spinning time, the thickness of the nanofibers could be obtained as 6.0 microns.

[0092] Example 5

[0093] The difference between this example and Example 1 was only that: the thickness of the conductive nanofibers was different. By controlling the spinning time, the thickness of the nanofibers could be obtained as 6.5 microns.

[0094] Refer to Figure 7 which is the comparison chart of the response speeds of nanofibers with different thicknesses in Examples 1 - 5. It can be seen from the figure that as the thickness of the conductive nanofibers increases, the response speed of the device increases.

[0095] Example 6

[0096] The difference between this embodiment and Embodiment 1 is only that: the area of the conductive nanofibers is different, and by controlling the diameter of the nanofibers, the area of the nanofibers can be obtained as 4.5 square centimeters.

[0097] Embodiment 7

[0098] The difference between this embodiment and Embodiment 1 is only that: the area of the conductive nanofibers is different, and by controlling the diameter of the nanofibers, the area of the nanofibers can be obtained as 31.50 square centimeters.

[0099] Embodiment 8

[0100] The difference between this embodiment and Embodiment 1 is only that: the area of the conductive nanofibers is different, and by controlling the diameter of the nanofibers, the area of the nanofibers can be obtained as 69.95 square centimeters.

[0101] Refer to Figure 8 It is a comparison chart of the response speeds of the conductive nanofibers with different areas in Embodiment 1, Embodiment 6 - Embodiment 8. As can be seen from the figure, compared with a larger area, the response speed of 4.5 square centimeters is slower. When it is greater than 11.23 square centimeters, the difference in the response speed is not significant.

[0102] Embodiment 9

[0103] The difference between this embodiment and Embodiment 1 is only that: weigh 1.45 g of In(NO 3 ) 3 ·4H 2 O (indium nitrate tetrahydrate), and at the same time mix it with SnCl 3 ) 3 with a molar ratio of 8:2 of SnCl 2 ·2H 2 O (stannous chloride dihydrate) and add it to a mixed solvent of 7 mL of DMF (N,N - dimethylformamide) and 9 mL of anhydrous C 2 H 5 OH (ethanol), and stir to dissolve. Then, add 1.5 g of PVP (polyvinylpyrrolidone) and stir to dissolve at 45 °C to obtain a colorless, clear and transparent solution, which is the spinning solution.

[0104] Other steps are the same.

[0105] Embodiment 10

[0106] The difference between this embodiment and Embodiment 1 is only that: weigh 1.45 g of In(NO 3 ) 3 ·4H 2 O (indium nitrate tetrahydrate), and at the same time mix it with In(NO 3 ) 3 with a molar ratio of 7:3 of SnCl2 ·2H 2 O (stannous dichloride dihydrate) was added to a mixed solvent of 7 mL of DMF (N,N-dimethylformamide) and 9 mL of anhydrous C 2 H 5 OH (ethanol), and stirred until dissolved. Then, 1.5 g of PVP (polyvinylpyrrolidone) was added and stirred at 45 °C until dissolved to obtain a colorless, clear and transparent solution, which was the spinning solution.

[0107] All other steps were the same.

[0108] See Figure 9 , which is the I-V curve of the electrochromic device prepared from the conductive nanofibers obtained in Example 1 and Examples 9 - 10. The greater the current at the same voltage, the better the conductivity. As can be seen from the figure, Example 1 (the molar ratio of indium atoms to tin atoms is 9:1) has the best conductivity, which is the most ideal doping ratio, followed by Example 10 (the molar ratio of indium atoms to tin atoms is 7:3).

[0109] Comparative Example 1

[0110] The difference between this comparative example and Example 1 is only that: the conductive electrodes are different. The conductive electrode in this comparative example is two FTO electrodes, and the obtained electrochromic device is the FTO device.

[0111] The results are shown in Figure 6a . Compared with the device based on the FTO electrode, the FTO-3D device has better electroresponse ability, and has a greater fluorescence intensity and absorbance change at the same voltage and the same time.

[0112] See Figure 6b . When reaching the same absorbance change, the FTO-3D device has a shorter response time, with a coloring time of 1.0 s and a fading time of only 0.9 s.

[0113] Refer to Figure 6c . It can be seen that the FTO-3D device has better cycle stability. After 500 cycles of color change - fading, the absorbance change of the FTO device has attenuated; the absorbance change of the FTO-3D device remains basically unchanged.

[0114] Comparative Example 2

[0115] The difference between this comparative example and Example 1 is only that: the high-temperature calcination temperature is different. In this comparative example, the FTO glass deposited with the ITO nanofiber precursor was placed in a muffle furnace, and the calcination conditions were as follows: first, it was heated to 600 °C at a rate of 1 °C / min and maintained at this temperature for 2 hours, and finally it was naturally cooled to room temperature after the program ended, and the ITO conductive nanofibers could be prepared on the electrode surface.

[0116] The ITO conductive nanofibers obtained in this comparative example are ITO hollow micro-nanofibers, and their conductive properties do not meet the requirements of the present invention as electrochromic devices.

[0117] In summary, compared with the device constructed based on the FTO electrode in Comparative Example 1, the FTO-3D device provided in Example 1 has better electro-response ability. Under the same voltage and the same time, the FTO-3D device has a larger transparency change (optical modulation, Figure 6a and Figure 6b ), and when reaching the same absorbance change, the FTO-3D device has a shorter response time ( Figure 6c ). Moreover, the FTO-3D device has better cycle stability. The voltage parameters of the FTO-3D device are -1.13V, 3s; the voltage parameters of the FTO device are -1.15V, 6s.

[0118] The above are only the preferred embodiments of the present invention, and they do not limit the protection scope of the present invention. For those skilled in the art, various changes and modifications can be made to the present invention. Any changes, modifications, substitutions, integrations, and parameter changes made to these embodiments by means of conventional substitutions or capable of achieving the same functions without departing from the principle and spirit of the present invention fall within the protection scope of the present invention.

Claims

1. A transparent conductive material, characterized in that: include Transparent conductive glass substrate; ITO nano-conductive fibers deposited on the surface of the transparent conductive glass substrate; The ITO nano conductive fiber is obtained by spinning an indium source and a tin source and then calcining at high temperature.

2. The transparent conductive material according to claim 1, characterized in that: The preparation method of the ITO nano conductive fiber comprises: The indium source and the tin source are added into an organic mixed solvent, dissolved and mixed evenly, and then polyvinyl pyrrolidone is added to obtain a spinning solution; The spinning solution is reacted by the spinning method to obtain an ITO nanofiber precursor; The ITO nanofiber precursor is calcined at high temperature to obtain the ITO nano conductive fiber.

3. The transparent conductive material according to claim 2, characterized in that: The indium source is indium nitrate; the tin source is stannous chloride; the molar ratio of indium atoms in the indium source to tin atoms in the tin source is 7:3 to 9:1, preferably 9:1; And / or, the organic mixed solvent is a mixed solution of N,N-dimethylformamide and a low boiling point organic solvent; and / or, the volume ratio of N,N-dimethylformamide to the low boiling point organic solvent is 2:1 to 1:2; And / or, the transparent conductive substrate material is any one of ITO glass, FTO glass or PET-ITO glass; And / or, the spinning technology includes any one of electrospinning, wet spinning, and melt spinning.

4. The transparent conductive material according to claim 2, characterized in that: The high temperature calcination conditions include using a programmed temperature method, first heating to 180-220°C at a rate of 1-3°C / min, maintaining at this temperature for 0.5-1.5 hours, then heating to 500-550°C at a rate of 1-3°C / min, and maintaining for 1.5-2.5 hours; and finally naturally cooling to room temperature.

5. The transparent conductive material according to claim 2, characterized in that: The ITO conductive nanofibers obtained after high-temperature calcination have a transparent, conductive three-dimensional structure with a diameter of 100 to 800 nanometers. The area of ​​the ITO nano-conductive fibers is 4.5 to 70 square centimeters; preferably, the area of ​​the ITO nano-conductive fibers is 4.5 to 12 square centimeters.

6. A fast-response electrochromic device, characterized in that: include: The five-layer structure consists of the first transparent conductive layer - electrochromic layer - ion conductive layer - ion storage layer - second transparent conductive layer; The first transparent conductive layer and the second transparent conductive layer are both transparent conductive three-dimensional electrodes; The first transparent conductive layer and the second transparent conductive layer are the transparent conductive materials according to any one of claims 1 to 5.

7. The electrochromic device according to claim 6, characterized in that: The thickness of the nanofibers deposited on the surface of the transparent substrate material is 0.1 to 10 microns; The thickness of the electrochromic layer is 1 to 20 microns; The thickness of the ion transport layer is 1 to 100 microns; The thickness of the ion storage layer is 1 to 20 micrometers.

8. The electrochromic device according to claim 6, characterized in that: The coloring time of the electrochromic device is ≤1s, and the fading time is ≤0.9s.

9. A method for preparing an electrochromic device according to any one of claims 6 to 8, characterized in that: The following steps are involved: S1. Providing a spinning solution; S2. Providing a transparent substrate conductive glass; S3. The spinning solution is reacted by a spinning method to obtain an ITO nanofiber precursor, and deposited on the surface of a transparent substrate glass; S4. calcining the transparent substrate glass obtained in S3 to obtain a first transparent conductive layer; S5. Repeat steps S1 to S4 to obtain a second transparent conductive layer; S6. Using the first transparent conductive layer as a working electrode, and sequentially coating an ion conducting layer and an ion storage layer on the surface of the first transparent conductive layer; Using the second transparent conductive layer as a counter electrode, coating an electrochromic layer on the surface of the second transparent conductive layer; S7. Assemble the multilayer structures prepared in S6, and then package the device to obtain the electrochromic device.

10. The preparation method according to claim 9, characterized in that: The electrochromic layer comprises: 2-4 g polymethyl methacrylate, 1-2 mL [BMIM] PF6 (1-butyl-3-methylimidazolium hexafluorophosphate), 0.01-0.1 mol / L p-BQ (p-benzoquinone), 0.001-0.01 mol / L fluorescein, and 20 mL acetonitrile; the ion storage layer comprises: 3.5 g PMMA, 1.7 mL [BMIM] PF6, 0.05 mol / L p-BQ, 0.1 mol / L hydroquinone, and 20 mL CH3CN; The ion conductive layer includes 2-4 g PMMA, 1-2 mL [BMIM] PF6 and 20 mL CH3CN; The coating method in S7 includes any one of spin coating and scraper coating; The S8 packaging method is one of UV curing or silicone potting.

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