Reflection type visible light / thermal infrared separation regulation and control electrochromic thin film device

Abstract

The invention discloses a reflection type visible light / thermal infrared separation regulation and control electrochromic thin film device, and belongs to the technical field of broadband electrochromic camouflage. The reflective visible light / thermal infrared separation regulation and control electrochromic thin film device comprises a visible light-thermal infrared transparent packaging thin film, a visible light / thermal infrared electrochromic working electrode, an electrolyte layer, a counter electrode and a packaging thin film which are sequentially arranged from top to bottom. Wherein the visible light / thermal infrared electrochromic working electrode comprises a patterned interdigital metal conducting layer and an electrochromic functional layer formed on the interdigital metal conducting layer; the electrochromic functional layer is of an interdigital structure which is formed by the first electrochromic film and the second electrochromic film and is the same as the interdigital metal conductive layer. By applying voltage to different electrochromic films in the working electrode and the electrode, regulation and control of coloring / fading and high / low infrared emissivity states are realized, and the effect of visible light / thermal infrared separation regulation and control is achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of wide-band electrochromic camouflage, and in particular relates to a reflective visible light / thermal infrared separation and regulation electrochromic thin film device. Background Art

[0002] In recent years, with the rapid development of detection technology, multi-optical band real-time target detection and analysis technology based on optical, electronic, infrared and other sensor detection has been formed, and the target is identified by detecting the difference in color and infrared radiation characteristics between the target and the background environment. Therefore, a single color is difficult to meet the existing camouflage needs. In view of this situation, wide-band electrochromic technology has better scheme adaptability, and it has the characteristics of regulating electric response optical properties. With the development of this technology, wide-band electrochromic materials have been discovered, such as conductive polymers, which can achieve both visible light color change and thermal infrared radiation regulation. However, due to the variability of the natural environment, there are color changes of different colors such as yellow, light green, dark green, and blue. At the same time, due to the inconsistency of the background infrared radiation characteristics, the same detection target and background will show different infrared thermal image distinctions under different background environments such as the earth, the ocean and the sky. Therefore, an electrochromic device with visible light color and thermal infrared radiation separation and regulation performance is needed to adapt to different environmental backgrounds, so as to have good application potential in the field of intelligent camouflage.

[0003] At present, due to the ion injection and extraction under the color change mechanism of electrochromic devices, as well as the change in the chemical structure of the material, it is difficult for wide-band electrochromic technology to achieve the separation and control of visible light and thermal infrared, that is, the existing visible light and thermal infrared emissivity states are coupled with each other, and a single electrochromic device can only achieve two modes of visible light coloring / high thermal infrared emissivity and visible light fading / low thermal infrared emissivity, or two modes of visible light coloring / low thermal infrared emissivity and visible light fading / high thermal emissivity. Existing transmission-type devices use a second electrochromic layer deposited on a single electrochromic layer, or by controlling the depth and concentration of ion-implanted dual electrochromic layers to achieve separation and control of visible light and infrared. However, due to the inherent properties of transparent conductive electrodes such as FTO and ITO, electrolyte organic solvents and electrochromic layers, the second electrochromic layer, ion storage layer or electrolyte layer will inevitably produce unnecessary infrared absorption, which significantly affects the infrared transmittance control performance of the electrochromic device. Therefore, with the development of detection technology, it is necessary to develop a separation-regulated electrochromic technology with visible light color and thermal infrared radiation regulation performance, eliminate unnecessary infrared absorption between the electrolyte layer and the electrochromic layer, rationally design the electrode structure of the electrochromic working electrode, and develop a visible light / thermal infrared separation-regulated electrochromic device. This will help the application of electrochromic devices in military camouflage and electronic skin, so that the devices can better adapt to different colors and thermal infrared radiation environments and achieve a color-changing effect like "chameleon skin". Summary of the invention

[0004] The purpose of the present invention is to propose a reflective visible light / thermal infrared separation and regulation electrochromic thin film device to solve the problem that the existing wide-band electrochromic devices do not have the visible light color and thermal infrared radiation separation and regulation functions.

[0005] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0006] A reflective visible light / thermal infrared separation and regulation electrochromic thin film device, comprising a visible light-thermal infrared transparent packaging film, a visible light / thermal infrared electrochromic working electrode, an electrolyte layer, a counter electrode and a packaging film arranged in sequence from top to bottom;

[0007] Among them, the visible light / thermal infrared electrochromic working electrode includes a patterned interdigitated metal conductive layer and an electrochromic functional layer formed on the interdigitated metal conductive layer; the electrochromic functional layer is an interdigitated structure formed by a first electrochromic film and a second electrochromic film, which is the same as the interdigitated metal conductive layer, wherein the first electrochromic film is located on one interdigitated metal conductive layer, and the second electrochromic film is located on another interdigitated metal conductive layer.

[0008] Furthermore, the material of the first electrochromic film is a material having dynamic color control in the visible light band of 350 to 780 nm and maintaining a constant transmittance of more than 80% in the thermal infrared band of 2.5 to 15 μm; the material of the second electrochromic film is a material having the same or same color system of visible light color control as the first electrochromic film material and having an infrared control function in the thermal infrared band of 2.5 to 15 μm, or is a material having an infrared control function only in the thermal infrared band of 2.5 to 15 μm.

[0009] Furthermore, the counter electrode includes a metal conductive layer and an ion storage functional layer formed on the metal conductive layer; the metal conductive layer is a finger structure identical to the finger metal conductive layer in the working electrode or is a complete metal film. When the metal conductive layer is a finger structure, the ion storage functional layer is a finger structure formed by the first electrochromic film and the second electrochromic film; when the metal conductive layer is a complete metal film, the ion storage functional layer is a complete first electrochromic film or a complete second electrochromic film.

[0010] Furthermore, by applying voltage to the working electrode and the counter electrode, the coloring / fading and high / low infrared emissivity states can be regulated.

[0011] Further, the infrared control function of the second electrochromic film material can be achieved by controlling the infrared emissivity or the actual temperature. When the second electrochromic film material realizes the infrared control function by controlling the infrared emissivity, the counter electrode and the ion storage functional layer are forked finger structures, and the visible light color is controlled by applying a voltage between a group of forked fingers of the visible light / thermal infrared electrochromic working electrode and the counter electrode, and the infrared emissivity or the infrared emissivity and color are controlled by applying a voltage between the visible light / thermal infrared electrochromic working electrode and another group of forked fingers of the counter electrode; when the second electrochromic film material realizes the infrared control function by the actual temperature (Joule heat), the counter electrode and the ion storage functional layer are complete film structures, and the visible light color is controlled by applying a voltage between a forked finger of the visible light / thermal infrared electrochromic working electrode and the complete counter electrode, and the infrared control is realized by applying a voltage at both ends of a forked finger of the visible light / thermal infrared electrochromic working electrode.

[0012] Furthermore, the aspect ratio of the fingers in the interdigitated metal conductive layer is greater than or equal to 10.

[0013] Furthermore, the interdigitated metal conductive layer includes a porous substrate and a conductive film formed on the porous substrate by electron beam evaporation or magnetron sputtering; the porous substrate is a porous polyamide-66 film, a polytetrafluoroethylene film, a fluorinated ethylene propylene film, a polyester film or a cellulose film, and the conductive film is one or more of gold, silver, platinum, titanium, and aluminum, with a thickness of 0.05 to 50 μm.

[0014] Furthermore, the material of the first electrochromic film is Prussian blue, titanium dioxide or tungsten oxide, etc.; the second electrochromic film material that has the same visible light color control as the first electrochromic film material or the same color system and has an infrared control function in the 2.5-15μm thermal infrared band can be selected from polyaniline, polythiophene, polypyrrole and their derivatives, with a thickness of 0.5-500μm; the second electrochromic film material that only has an infrared control function in the 2.5-15μm thermal infrared band can be selected from MXene materials, graphene, etc., with a thickness of 0.5-500μm.

[0015] Furthermore, the visible light-thermal infrared transparent packaging film is a window material film such as polyethylene, polypropylene, calcium fluoride, zinc sulfide, zinc selenide, germanium, etc., and has a thickness of 0.01 to 1 mm.

[0016] Furthermore, the electrolyte layer includes a solvent, a skeleton polymer and an electrolyte; wherein the solvent is one or more of propylene carbonate, fluoroethylene carbonate, ethyl acetate, and acetonitrile, the skeleton polymer is one or more of polymethyl methacrylate, polyvinyl alcohol, polyethylene oxide, polyvinylidene fluoride, and poly(vinylidene fluoride-co-hexafluoroethylene), and the electrolyte is one or more of ionic liquids, lithium salts, sodium salts, and protonic acids.

[0017] Furthermore, the encapsulation film is a polymer film such as polypropylene, polytetrafluoroethylene, high-density polyethylene, low-density polyethylene, ultra-high molecular weight polyethylene, polyester, or an inorganic film such as calcium fluoride, zinc sulfide, germanium, high-aluminum silicon glass, with a thickness of 0.01 to 1 mm.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] 1. The present invention provides a reflective visible light / thermal infrared separation and regulation electrochromic thin film device, in which the working electrode is a fine stripe interdigitated pattern structure with an aspect ratio greater than 10, and the first electrochromic film and the second electrochromic film are separately arranged on different interdigitated fingers, so that the device is regarded as a complete plane when detected by visible light or thermal infrared from a distance, thereby achieving the purpose of deceiving the detector.

[0020] 2. The present invention realizes the regulation of coloring / fading and high / low infrared emissivity states by applying voltage to different electrochromic films in the working electrode and the counter electrode, thereby achieving the effect of visible light / thermal infrared separation and regulation.

[0021] 3. The present invention places the first electrochromic film and the second electrochromic film in the same layer in the form of an interdigital structure and places them on the top layer of the device, which effectively avoids the mutual influence of optical absorption between layers and maximizes the color-changing performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 A schematic diagram of the structure of the interdigitated metal conductive layer in a reflective visible light / thermal infrared separation and regulation electrochromic thin film device provided by the present invention;

[0023] Figure 2 A schematic diagram of the structure of a reflective visible light / thermal infrared separation and regulation electrochromic thin film device provided in Example 1;

[0024] Figure 3 A schematic diagram of the structure of a reflective visible light / thermal infrared separation and regulation electrochromic thin film device provided in Example 2;

[0025] Figure 4 A visible light color control diagram of the actual reflective visible light / thermal infrared separation control electrochromic thin film device provided in Example 1;

[0026] Figure 5 This is a thermal infrared radiation control diagram of the actual reflective visible light / thermal infrared separation control electrochromic thin film device provided in Example 1. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0028] Example 1

[0029] like Figure 2 As shown, it is a schematic diagram of the structure of the reflective visible light / thermal infrared separation and regulation electrochromic thin film device provided in Example 1; it includes a visible light-thermal infrared transparent encapsulation film, a visible light / thermal infrared electrochromic working electrode, an electrolyte layer, a counter electrode and an encapsulation film arranged in sequence from top to bottom. The first electrochromic film in the working electrode is a Prussian blue film, and the second electrochromic film is a polyaniline derivative film; the conductive film in the interdigitated metal conductive layer is gold; the first electrochromic film in the ion storage layer of the counter electrode is a Prussian blue film, and the second electrochromic film is a polyaniline derivative film.

[0030] The preparation process of the reflective visible light / thermal infrared separation control electrochromic thin film device provided in Example 1 is as follows:

[0031] Step 1. The interdigitated metal conductive layer is designed to be an interdigitated structure formed by two comb-shaped structures with an area ratio of 1:1, wherein the stripe width of the interdigitated structure is about 0.04 mm, so that the two stripes can be regarded as a plane at a certain distance;

[0032] Step 2. A continuous metal conductive layer is deposited on the surface of the porous substrate by electron beam evaporation, and an infrared laser etcher is used to etch a path of 0.01 mm on the surface of the continuous metal conductive layer at a power of 30 W to obtain a patterned interdigitated metal conductive layer;

[0033] Step 3. Add deionized water and HCl to the reaction vessel, then add KCl, FeCl3 6H2O and K3[Fe(CN)6] in sequence, stir at room temperature for 1 h to obtain a uniform solution; then use the three-electrode method at -15μA / cm 2 Deposit for 800 s to deposit a uniform Prussian blue film on one of the interdigitated metal conductive layers;

[0034] Step 4. Add deionized water and H2SO4 into a reaction container, then add triphenylamine and aniline in sequence, and stir at room temperature for 12 hours to obtain a uniform solution; then use a three-electrode method to deposit a uniform polyaniline derivative film on the other interdigitated metal conductive layer under a constant voltage condition of 0.60V for 100 seconds;

[0035] Step 5. lithium perchlorate, 1-ethyl-3-methylimidazolium tetrafluoroborate and polymethyl methacrylate are added to a reaction vessel, and then propylene carbonate and fluoroethylene carbonate are added in sequence, and the mixture is stirred at 60° C. for 5 hours to obtain an electrolyte layer;

[0036] Step 6. Package the working electrode and a counter electrode that is exactly the same as the working electrode by a "roll-to-roll" hot pressing method, and then coat the electrolyte layer on the back of the packaged visible light / thermal infrared electrochromic working electrode and the counter electrode, and stack them in the order of "visible light / thermal infrared electrochromic working electrode / electrolyte layer / counter electrode" to obtain a reflective visible light / thermal infrared separation and regulation electrochromic thin film device.

[0037] The working principle of the reflective visible light / thermal infrared separation control electrochromic thin film device of Example 1 is:

[0038] When the applied voltage is -1.6V, the Prussian blue of the first electrochromic film changes its lattice structure due to the injection of cations, and appears colorless and transparent, and appears yellow after being superimposed with the color of the interdigitated metal conductive layer; when the applied voltage is +0.6V, the Prussian blue film changes its lattice structure due to the release of cations, and appears blue, and appears green after being superimposed with the yellow of the interdigitated metal conductive layer. When the applied voltage is +0.6V, the polyaniline derivative of the second electrochromic film changes its molecular structure due to a reversible oxidation reaction and produces a polaron / bipolaron structure, and appears green and a high emission state; when the applied voltage is -1.6V, the polyaniline derivative film changes its molecular structure due to a reversible reduction reaction and eliminates the polaron / bipolaron structure, and appears colorless, transparent and a low emission state, and appears yellow and other colors after being superimposed with the color of the interdigitated metal conductive layer. When the electrolyte concentration is constant, the first / second electrochromic film can be applied with positive / negative, positive / positive, negative / negative or negative / positive external voltages respectively and realize the transition of different control states. Since the stripe width of the interdigitated pattern is small, when observed, the first / second electrochromic film shows a similar effect compared with its independent continuous electrochromic film, and finally realizes the separate control of visible light and thermal infrared radiation.

[0039] Example 2

[0040] like Figure 3 As shown, it is a schematic diagram of the structure of the reflective visible light / thermal infrared separation and regulation electrochromic thin film device provided in Example 2; it includes a visible light-thermal infrared transparent encapsulation film, a visible light / thermal infrared electrochromic working electrode, an electrolyte layer, a counter electrode and an encapsulation film arranged in sequence from top to bottom. The first electrochromic film in the working electrode is a Prussian blue film, and the second electrochromic film is a MXene film; the conductive film in the interdigitated metal conductive layer is gold; and the electrochromic film in the ion storage layer of the counter electrode is a Prussian blue film.

[0041] The preparation process of the reflective visible light / thermal infrared separation control electrochromic thin film device provided in Example 2 is as follows:

[0042] Step 1. The interdigitated metal conductive layer is designed to be an interdigitated structure formed by two comb-shaped structures with an area ratio of 1:1, wherein the stripe width of the interdigitated structure is about 0.04 mm, so that the two stripes can be regarded as a plane at a certain distance;

[0043] Step 2. A continuous metal conductive layer is deposited on the surface of the porous substrate by electron beam evaporation, and an infrared laser etcher is used to etch a path with a width of 0.01 mm on the surface of the continuous metal conductive layer at a power of 30 W to obtain a patterned interdigitated metal conductive layer;

[0044] Step 3. Add deionized water and HCl to the reaction vessel, then add KCl, FeCl3 6H2O and K3[Fe(CN)6] in sequence, stir at room temperature for 1 h to obtain a uniform solution; then use the three-electrode method at -15μA / cm 2 Deposit for 800 s to deposit a uniform Prussian blue film on one of the interdigitated metal conductive layers;

[0045] Step 4. HF and HCl are added to the reaction vessel, and then Ti3AlC2 powder is added in small amounts gradually, and heated at 45°C with stirring for 12 to 24 hours; the mixture is centrifuged and washed with deionized water for several times until the supernatant is close to neutral, and the precipitate is collected; the collected precipitate is then added to distilled water, and then LiCl is added, and stirred at room temperature for 12 to 24 hours; the single layer Ti3C2T is peeled off by multiple expansion centrifugation methods. x MXene and increase the yield, and finally collect the upper suspension by low-speed centrifugation to obtain a single layer / few layers of Ti3C2T x MXene dispersion;

[0046] Step 5. Add the above Ti3C2T x After the MXene dispersion and deionized water were evenly mixed, a self-supporting MXene film was obtained by vacuum filtration.

[0047] Step 6. lithium perchlorate, 1-ethyl-3-methylimidazolium tetrafluoroborate and polymethyl methacrylate are added to a reaction container, and then propylene carbonate and fluoroethylene carbonate are added in sequence, and the mixture is stirred at 60° C. for 5 hours to obtain an electrolyte layer;

[0048] Step 7. Deposit a Prussian blue film on the gold conductive layer as the counter electrode, package the working electrode and the counter electrode by a roll-to-roll hot pressing method, and then coat the electrolyte layer on the back of the packaged visible light / thermal infrared electrochromic working electrode and the counter electrode, and stack them in the order of "visible light / thermal infrared electrochromic working electrode / electrolyte layer / counter electrode" to obtain a reflective visible light / thermal infrared separation and regulation electrochromic thin film device.

[0049] The working principle of the reflective visible light / thermal infrared separation control electrochromic thin film device of Example 2 is:

[0050] When the applied voltage is -1.6V, the Prussian blue of the first electrochromic film changes its lattice structure due to the injection of cations, and it appears colorless and transparent, and it appears yellow after superimposing with the color of the interdigitated metal conductive layer; when the applied voltage is +0.6V, the Prussian blue film changes its lattice structure due to the release of cations, and it appears blue, and it appears green after superimposing with the yellow of the interdigitated metal conductive layer. When the applied voltage is 3.0V, the MXene of the second electrochromic film can heat up rapidly due to the Joule heating effect. According to the Stefan-Boltzmann law, the thermal infrared radiation power of the MXene film increases; after the applied voltage is removed, due to the low emissivity characteristics of the MXene film itself and the planar thermal conductivity, the surface will quickly dissipate heat and present low thermal infrared radiation. Since the MXene film uses the applied voltage on the electrode surface to generate the Joule heating effect, the first / second electrochromic film can be applied with positive / negative, positive / positive, negative / negative or negative / positive applied voltages respectively and realize the transition of different control states. Since the stripe width of the interdigitated pattern is small, the first / second electrochromic film exhibits a similar effect as its independent continuous electrochromic film during observation, and ultimately achieves separate regulation of visible light and thermal infrared radiation.

Claims

1. A reflective visible light / thermal infrared separation and control electrochromic thin film device, characterized in that: It includes a visible light-thermal infrared transparent packaging film, a visible light / thermal infrared electrochromic working electrode, an electrolyte layer, a counter electrode and a packaging film which are arranged in sequence from top to bottom; Among them, the visible light / thermal infrared electrochromic working electrode includes a patterned interdigitated metal conductive layer and an electrochromic functional layer formed on the interdigitated metal conductive layer; the electrochromic functional layer is an interdigitated structure formed by a first electrochromic film and a second electrochromic film, which is the same as the interdigitated metal conductive layer, wherein the first electrochromic film is located on one interdigitated metal conductive layer, and the second electrochromic film is located on another interdigitated metal conductive layer.

2. The reflective visible light / thermal infrared separation and control electrochromic thin film device according to claim 1, characterized in that: The material of the first electrochromic film is a material that has dynamic color control in the visible light band of 350 to 780 nm and maintains a transmittance of more than 80% in the thermal infrared band of 2.5 to 15 μm; the material of the second electrochromic film is a material that has the same visible light color control as the first electrochromic film material or the same color system and has an infrared control function in the thermal infrared band of 2.5 to 15 μm, or is a material that only has an infrared control function in the thermal infrared band of 2.5 to 15 μm.

3. The reflective visible light / thermal infrared separation and control electrochromic thin film device according to claim 1, characterized in that: The counter electrode comprises a metal conductive layer and an ion storage functional layer formed on the metal conductive layer; the metal conductive layer is an interdigitated structure identical to the interdigitated metal conductive layer in the working electrode or is a complete metal film.

4. The reflective visible light / thermal infrared separation and control electrochromic thin film device according to claim 1, characterized in that: When the second electrochromic thin film material realizes the infrared control function by regulating the infrared emissivity, the counter electrode and the ion storage functional layer are a forked finger structure, and the visible light color is controlled by applying a voltage between the visible light / thermal infrared electrochromic working electrode and a group of forked fingers of the counter electrode, and the infrared emissivity or the infrared emissivity and color are controlled by applying a voltage between the visible light / thermal infrared electrochromic working electrode and another group of forked fingers of the counter electrode; when the second electrochromic thin film material realizes the infrared control function by temperature, the counter electrode and the ion storage functional layer are a complete thin film structure, and the visible light color is controlled by applying a voltage between a forked finger of the visible light / thermal infrared electrochromic working electrode and the complete counter electrode, and the infrared is controlled by applying a voltage at both ends of a forked finger of the visible light / thermal infrared electrochromic working electrode.

5. The reflective visible light / thermal infrared separation and control electrochromic thin film device according to claim 1, characterized in that: The aspect ratio of the interdigitated metal conductive layer is greater than or equal to 10.

6. The reflective visible light / thermal infrared separation and control electrochromic thin film device according to claim 1, characterized in that: The interdigitated metal conductive layer includes a porous substrate and a conductive film formed on the porous substrate by electron beam evaporation or magnetron sputtering; the porous substrate is a porous polyamide-66 film, a polytetrafluoroethylene film, a fluorinated ethylene propylene film, a polyester film or a cellulose film, and the conductive film is one or more of gold, silver, platinum, titanium and aluminum.

7. The reflective visible light / thermal infrared separation and control electrochromic thin film device according to claim 1, characterized in that: The material of the first electrochromic film is Prussian blue, titanium dioxide or tungsten oxide; the material of the second electrochromic film that has the same visible light color control as the first electrochromic film material or the same color series and has an infrared control function in the 2.5-15μm thermal infrared band is polyaniline, polythiophene, polypyrrole and their derivatives; the material of the second electrochromic film that only has an infrared control function in the 2.5-15μm thermal infrared band is MXene material or graphene.

8. The reflective visible light / thermal infrared separation and control electrochromic thin film device according to claim 1, characterized in that: The visible light-thermal infrared transparent packaging film is polyethylene, polypropylene, calcium fluoride, zinc sulfide, zinc selenide or germanium.

9. The reflective visible light / thermal infrared separation and control electrochromic thin film device according to claim 1, characterized in that: The electrolyte layer includes a solvent, a skeleton polymer and an electrolyte; wherein the solvent is one or more of propylene carbonate, fluoroethylene carbonate, ethyl acetate, and acetonitrile; the skeleton polymer is one or more of polymethyl methacrylate, polyvinyl alcohol, polyethylene oxide, polyvinylidene fluoride, and poly(vinylidene fluoride-co-hexafluoroethylene); and the electrolyte is one or more of an ionic liquid, a lithium salt, a sodium salt, and a protonic acid.

10. The reflective visible light / thermal infrared separation and control electrochromic thin film device according to claim 1, characterized in that: The packaging film is polypropylene, polytetrafluoroethylene, high-density polyethylene, low-density polyethylene, ultra-high molecular weight polyethylene, polyester, calcium fluoride, zinc sulfide, germanium or high-aluminum silicon glass.

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