Multicolor electrochromic devices and their fabrication methods

Abstract

This application discloses a multi-color electrochromic device and its fabrication method. The multi-color electrochromic device includes: a porous layer having a first side and a second side facing away from each other; an electrolyte filling the porous layer; a first metal layer disposed on the first side of the porous layer; a first electrochromic layer disposed on the first metal layer, wherein both surfaces of the first electrochromic layer in the thickness direction are reflective surfaces, thereby forming a first optical resonant cavity; and a counter electrode disposed on the second side of the porous layer. The electrochromic layer of the multi-color electrochromic device of this application can be directly observed without being affected by other structural layers, resulting in better visual effects. Furthermore, the overall thickness of the multi-color electrochromic device can reach less than 100 μm, exhibiting ultra-thin and flexible characteristics, making it easier to integrate with different devices. Simultaneously, its fabrication process is simple, facilitating large-area, mass production.

Description

Technical Field

[0001] This application relates to an electrochromic device, specifically a multi-color electrochromic device and its preparation method. Background Technology

[0002] Recently, inorganic multi-color electrochromic devices have attracted widespread attention due to their superior color adjustment capabilities compared to traditional inorganic electrochromic devices and their better cycle stability than organic electrochromic devices. Combined with the bistable and low-energy-consumption characteristics of electrochromism itself, inorganic multi-color electrochromic devices have significant application potential in display, anti-counterfeiting, and sensing fields. However, the "sandwich" structure of traditional electrochromic devices results in defects such as large thickness (millimeter level) and poor flexibility, which cannot meet the ultra-thin requirements of display and anti-counterfeiting applications. At the same time, the traditional "sandwich" structure also makes the color of multi-color electrochromic devices susceptible to the influence of electrolytes and counter electrodes. These shortcomings greatly limit the practical application of multi-color electrochromic devices. Summary of the Invention

[0003] The main objective of this application is to provide a multicolor electrochromic device and its preparation method to overcome the shortcomings of the prior art.

[0004] To achieve the aforementioned objectives, the technical solution adopted in this application includes:

[0005] One aspect of this application provides a multi-color electrochromic device, comprising:

[0006] A porous layer having a first and a second surface facing away from each other;

[0007] Electrolytes are filled within the porous layer;

[0008] A first metal layer is disposed on the first surface of the porous layer;

[0009] A first electrochromic layer is disposed on the first metal layer, and both sides of the first electrochromic layer in the thickness direction are reflective surfaces, thereby forming a first optical resonant cavity;

[0010] The electrode is disposed on the second surface of the porous layer.

[0011] Another aspect of this application provides a method for fabricating a multi-color electrochromic device, comprising:

[0012] A porous layer is provided, the porous layer having a first side and a second side facing away from each other;

[0013] A first metal layer and a first electrochromic layer are sequentially disposed on the first surface of the porous layer. Both sides of the first electrochromic layer in the thickness direction are reflective surfaces, thereby forming a first optical resonant cavity.

[0014] A counter electrode is disposed on the second surface of the porous layer;

[0015] And, an electrolyte is filled in the porous layer.

[0016] Another aspect of this application provides the use of the aforementioned multicolor electrochromic device in the fabrication of display devices and other fields.

[0017] Compared to existing technologies, this application integrates the electrochromic layer and counter electrode of the multi-color electrochromic device on both sides of a porous layer, and utilizes the porous structure of the porous layer to store electrolyte. The electrochromic layer and counter electrode are connected by the electrolyte stored in the porous layer, thus preventing the electrochromic layer from being obscured by other structural layers such as electrolyte and counter electrode, allowing it to be directly observed. This avoids the influence of other structural layers on its intrinsic color and dynamic color changes, resulting in better visual effects. Furthermore, the overall thickness of the multi-color electrochromic device is mainly determined by the porous layer, reaching less than 100 μm, and exhibiting ultra-thin and flexible characteristics, making it easier to combine with different devices and meet the application needs of different fields. At the same time, the fabrication process of this multi-color electrochromic device is simple, which is conducive to large-area, mass production. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of the structure of an electrochromic device in the prior art;

[0020] Figure 2 This is a schematic diagram of the structure of a multi-color electrochromic device according to Embodiment 1 of this application;

[0021] Figure 3 This is a photograph of a multi-color electrochromic device in Embodiment 1 of this application before it is powered on;

[0022] Figure 4 This is a photograph of a multi-color electrochromic device according to Embodiment 1 of this application after being powered on;

[0023] Figure 5 This is a photograph of the color change of a multi-color electrochromic device under different voltages according to Embodiment 1 of this application;

[0024] Figure 6 These are the reflectance test spectra of the electrochromic devices in Embodiment 1 and Comparative Example 4 of this application;

[0025] Figure 7 This is a schematic diagram of the structure of a multi-color electrochromic device according to Embodiment 2 of this application;

[0026] Figures 8a-8c These are photographs of the front, back, and bent states of a multi-color electrochromic device according to Embodiment 2 of this application before being powered on.

[0027] Figures 9a-9c These are photographs of the front, back, and bent states of a multi-color electrochromic device according to Embodiment 2 of this application after being powered on.

[0028] Figure 10 This is a schematic diagram of the structure of a multi-color electrochromic device according to Embodiment 4 of this application;

[0029] Figure 11 This is a photograph of a multi-color electrochromic device in Embodiment 4 of this application before it is powered on;

[0030] Figure 12 This is a photograph of a multi-color electrochromic device according to Embodiment 4 of this application after being powered on. Detailed Implementation

[0031] Please see Figure 1 As shown, existing electrochromic devices mainly consist of a substrate 1, an electrochromic layer 2, an electrolyte layer 3, and a counter electrode 4 arranged sequentially from bottom to top. Therefore, the electrochromic layer 2 is obscured by the electrolyte layer 3 and the counter electrode 4 and cannot be directly observed. Although the electrolyte layer and the counter electrode can be prepared using materials with high light transmittance, the color of the electrochromic layer is inevitably interfered with by the electrolyte layer and the counter electrode, which greatly reduces the overall color perception of the device, especially in terms of reduced reflectivity and deviation of electrode color. At the same time, as mentioned earlier, such electrochromic devices also generally have shortcomings such as a thickness of more than millimeters and poor flexibility, making it difficult to produce on a large scale and in large quantities, and also inconvenient to combine with increasingly thin and light electronic devices.

[0032] In view of these shortcomings of the prior art, the applicant has proposed the technical solution of this application, which will be described in more detail below.

[0033] Some embodiments of this application provide a multi-color electrochromic device including:

[0034] A porous layer having a first and a second surface facing away from each other;

[0035] Electrolytes are filled within the porous layer;

[0036] A first metal layer is disposed on the first surface of the porous layer;

[0037] A first electrochromic layer is disposed on the first metal layer, and both sides of the first electrochromic layer in the thickness direction are reflective surfaces, thereby forming a first optical resonant cavity;

[0038] The electrode is disposed on the second surface of the porous layer.

[0039] By adopting the aforementioned design, at least one electrochromic layer is located on the outermost layer of the electrochromic device. When in use, whether energized or not, the color and brightness of the electrochromic layer are not obscured by other structural layers in the electrochromic device and can be directly observed, thus achieving a very good visual effect.

[0040] In one embodiment, the first metal layer and the first electrochromic layer constitute a metal-dielectric structure, which can produce optical interference to display multiple colors. Furthermore, by adjusting the thickness of the first electrochromic layer material, the constructive and destructive interference of light can be adjusted to achieve selective absorption and reflection of light, thereby also adjusting the structural color of the metal-dielectric structure accordingly.

[0041] In one embodiment, the first optical resonant cavity includes a Fabry-Perot resonant cavity. By forming this first optical resonant cavity, the electrochromic device can exhibit brilliant optical structural colors in the unpowered state, and in the powered state, it can achieve an organic fusion of optical structural colors and electrochromic properties, obtaining a color variety far exceeding the sum of the electrochromic and optical structural color varieties.

[0042] In one embodiment, the counter electrode includes a conductive layer and / or an ion storage layer, wherein the ion storage layer is disposed between the conductive layer and the second surface of the porous layer. The conductive layer can be made of metallic materials such as W, Ag, Pt, Au, Al, Cu, Ti, Mo, and Ni; or transparent conductive oxides such as ITO (indium tin oxide), FTO (fluorine-doped tin oxide), AZO (aluminum-doped zinc oxide), GZO (gallium-doped zinc oxide), ATO (antimony-doped tin oxide), IZO (indium-doped zinc oxide), NTO (niobium-doped titanium oxide), ZnO, OMO (oxide / metal / oxide), and CTO; silver (Ag) nanowires; metal mesh; or non-metallic conductive materials such as OMO (oxide-metal oxide), carbon nanotube films, and graphene films, and is not limited thereto. The ion storage layer can be formed using a variety of materials with ion storage capabilities known in the art, such as, but not limited to, ITO, AZO, FTO, Ta2O5, and CeO2.

[0043] In one embodiment, the counter electrode includes a second electrochromic layer and a second metal layer, the second electrochromic layer being disposed on the counter electrode, and the second metal layer being located between the second electrochromic layer and the second surface of the porous layer.

[0044] By adopting this design, the outermost layer on both sides of the electrochromic device is an electrochromic layer, and a very good visual effect can be obtained on both sides.

[0045] In one embodiment, the second metal layer and the second electrochromic layer also constitute a metal-dielectric structure, which can produce optical interference to display multiple colors. Furthermore, by adjusting the thickness of the second electrochromic layer material, the constructive and destructive interference of light can be adjusted to achieve selective absorption and reflection of light, thereby also adjusting the structural color of the metal-dielectric structure accordingly.

[0046] In one embodiment, both surfaces of the second electrochromic layer in the thickness direction are reflective surfaces, thereby forming a second optical resonant cavity.

[0047] Furthermore, the second optical resonator includes a Fabry-Perot resonator.

[0048] In this application, the reflective surface can be a mirror, a diffuse reflective surface, or the like.

[0049] Similarly, by forming the second optical resonant cavity in this application, the electrochromic device can exhibit brilliant optical structural colors in the unpowered state, and achieve an organic fusion of optical structural colors and electrochromic properties in the powered state. The second optical resonant cavity works in conjunction with the aforementioned first optical resonant cavity, enabling the electrochromic device of this application to exhibit multi-colored and variable visual effects on both sides. Furthermore, the visual effects on both sides can be the same or different to meet the usage requirements of different application scenarios.

[0050] In one embodiment, the materials of the first and second electrochromic layers include inorganic electrochromic materials, organic electrochromic materials, or composites thereof, with inorganic electrochromic materials being preferred due to their better cycle stability. Typical inorganic electrochromic materials include oxides of Co, Rh, Ir, Ni, Cr, Mn, Fe, Ti, V, Nb, Ta, Mo, and W, such as LiNiO2 (lithium nickel oxide), IrO2, NiO, V2O5, lithium cobalt oxide, Rh2O3, CrO3, WO3, MoO3, Nb2O5, Ta2O5, or TiO2, and are not limited to these. Typical organic electrochromic materials include organic polymers, small organic molecules, metal supramolecular polymers, and organometallic compounds, such as methyl viologen, violarin, polyaniline, polythiophene, polypyrrole, Prussian blue, organometallic chelates (e.g., titanine compounds), polydiyne, and are not limited to these.

[0051] In one embodiment, the thickness of the first electrochromic layer and the second electrochromic layer is >0 and ≤2000nm, preferably 100-500nm, so that the overall thickness of the multicolor electrochromic device is smaller and thinner.

[0052] In one embodiment, the thickness of the first metal layer and the second metal layer is >0 and ≤2000nm, preferably 90-150nm, so that the overall thickness of the multicolor electrochromic device is smaller and thinner.

[0053] In one embodiment, the surface of the porous layer is relatively flat, and multiple pores are evenly distributed on its surface.

[0054] In one embodiment, the pore size of the porous layer is 100nm to 1000nm, so as to ensure that the electrolyte can contact the electrochromic layer through the metal layer while maintaining the high saturation of the color of the multicolor electrochromic device.

[0055] In one embodiment, the thickness of the porous layer is >0 and ≤1000μm, preferably >0 and ≤100μm.

[0056] In one embodiment, the porous layer may be made of organic materials, inorganic materials or composite materials thereof, such as nylon, polysulfone (PS), polyacrylonitrile (PAN), modified polysulfone (PSF), polyvinylidene fluoride (PVDF), PVC (polyvinyl chloride), PES (polyethersulfone), PP (polypropylene), cellulose, porous metal membranes, porous metal oxide membranes, porous non-metal oxide membranes, porous carbon membranes, porous carbon paper, etc., and is not limited thereto.

[0057] In one embodiment, the electrolyte is in direct contact with both the first metal layer and the counter electrode.

[0058] In one embodiment, the first metal layer and the second metal layer have a porous structure, allowing ions to pass freely through the first metal layer and the second metal layer.

[0059] For example, the first metal layer is conformally deposited on the first surface of the porous layer, and therefore also has a porous structure, allowing ions to pass freely through the first metal layer.

[0060] In one embodiment, the electrolyte comprises a photocurable electrolyte. The electrolyte may contain one or more compounds, such as those containing H... + Li + Al 3+ Na + K + Mg + Zn + 、Rb + or Cs + The electrolyte comprises at least one polymer, such as polyacrylate, polyurethane, polyvinyl chloride (PVC), polyethylene oxide (PEO), polyacrylonitrile (PAN), polyvinylidene fluoride (PVDF), polymethyl methacrylate (PMMA), polypropylene oxide (PPO), polyvinylidene chloride (PVDC), and single-ion polymer electrolytes. In one example, the electrolyte layer may contain lithium salt compounds, such as LiClO4, LiBF4, LiTFSI, LiAsF6, or LiPF6. Ions contained in the electrolyte can play a role in color change or light transmittance change by being inserted into or removed from the electrochromic layer according to the polarity of the applied voltage. In some cases, the electrolyte may also be a gel electrolyte such as PMMA-PEG-LiClO4, PVDF-PC-LiPF6, etc.

[0061] Preferably, the electrolyte is a photocurable electrolyte, which can fully fill the pore structure within the porous layer, increasing the electrolyte content ratio in the electrochromic device. Furthermore, after curing, it can strengthen the bonding strength between the first metal layer, the counter electrode, and the porous layer. Particularly noteworthy is that by using a UV-curable electrolyte, the surface color quality of the multi-color electrochromic device of this application can be significantly improved, greatly increasing its color switching speed. The raw materials of the UV-curable electrolyte include 30-50 wt% polymer, 10-25 wt% ionic salt, 0.1-1.0 wt% photoinitiator, and 35-45 wt% solvent.

[0062] The polymer may be selected from, but is not limited to, polyacrylate, polyurethane, polyvinyl chloride (PVC), polyethylene oxide (PEO), polyacrylonitrile (PAN), polyvinylidene fluoride (PVDF), polymethyl methacrylate (PMMA), polypropylene oxide (PPO), and polyvinylidene chloride (PVDC). The ionic salt may be selected from, but is not limited to, those containing H+. + Li + Al 3+ Na + K + Mg + Zn + 、Rb + Cs + The photoinitiator can be, but is not limited to, DMPA, TPO, TPO-L, 907, ITX, EDB, OMBB, CBP, etc. The solvent can be, but is not limited to, eutectic solvents, propylene carbonate (PC), ethylene carbonate (EC), dimethyl carbonate (DMC), diethyl carbonate (DEC), methyl ethyl carbonate (EMC), etc.

[0063] In one embodiment, the first metal layer and the first electrochromic layer are sequentially deposited on the first surface of the porous layer by physical and / or chemical deposition.

[0064] In one embodiment, the counter electrode is deposited on the second surface of the porous layer by physical and / or chemical deposition. Furthermore, the second metal layer and the second electrochromic layer are also sequentially deposited on the second surface of the porous layer by physical and / or chemical deposition.

[0065] In one embodiment, the physical and / or chemical deposition method includes, but is not limited to, any one or a combination of magnetron sputtering, electron beam evaporation, thermal evaporation, and ion plating.

[0066] By depositing the remaining structural layers of the electrochromic device onto a porous layer, the device structure can be made thinner, more flexible, and more robust, making it more suitable for large-area, mass production. Furthermore, the overall shape of the electrochromic device can be adjusted, making it easier to combine with devices that have curved or other non-planar surfaces.

[0067] The materials of the first and second metal layers can be selected from non-reactive metals, such as chromium, gold, silver, copper, tungsten, titanium, or their alloys, and are not limited thereto. Preferably, the first and second metal layers are formed of metal materials with high conductivity, such as silver (Ag) or copper (Cu), so that the first and second metal layers also serve as current collectors for the first and second electrochromic layers, respectively.

[0068] In one embodiment, the multicolor electrochromic device further includes a substrate, the counter electrode is connected to the substrate, and the counter electrode is located between the substrate and a second surface of the porous layer. The substrate may be made of glass, plexiglass, plastic sheet, wood board, or metal, and is not limited thereto.

[0069] In one embodiment, the overall thickness of the multicolor electrochromic device is less than 100 μm, i.e., an ultrathin electrochromic device.

[0070] Some embodiments of this application provide a method for fabricating a multi-color electrochromic device, including:

[0071] A porous layer is provided, the porous layer having a first side and a second side facing away from each other;

[0072] A first metal layer and a first electrochromic layer are sequentially disposed on the first surface of the porous layer. Both sides of the first electrochromic layer in the thickness direction are reflective surfaces, thereby forming a first optical resonant cavity.

[0073] A counter electrode is disposed on the second surface of the porous layer;

[0074] And, an electrolyte is filled in the porous layer.

[0075] In one embodiment, the preparation method specifically includes: forming the first metal layer and the first electrochromic layer sequentially on the first surface of the porous layer by physical and / or chemical deposition.

[0076] In one embodiment, the preparation method specifically includes: forming the counter electrode on the second surface of the porous layer by physical and / or chemical deposition.

[0077] In one embodiment, the preparation method specifically includes: forming a second metal layer and a second electrochromic layer sequentially on the second surface of the porous layer by physical and / or chemical deposition, thereby forming the counter electrode, wherein both sides of the second electrochromic layer in the thickness direction are reflective surfaces, thereby forming a second optical resonant cavity.

[0078] In one embodiment, the first optical resonator and the second optical resonator include Fabry-Perot resonators.

[0079] In one embodiment, the physical and / or chemical deposition method includes, but is not limited to, any one or a combination of magnetron sputtering, electron beam evaporation, thermal evaporation, and ion plating. For example, the first and second electrochromic layers can be formed by magnetron sputtering, with both surfaces of the first and second electrochromic layers along their thickness direction being mirror-like, i.e., reflective surfaces.

[0080] In one embodiment, the preparation method specifically includes: absorbing a photocurable electrolyte into the porous layer, and then subjecting the porous layer to photo-irradiation treatment to solidify the electrolyte into a solid electrolyte.

[0081] In this application, the operation of filling the porous layer with electrolyte can be performed after the first metal layer and the first electrochromic layer and the counter electrode or the second metal layer and the second electrochromic layer are set, or it can be performed before or during these operations.

[0082] In one embodiment, the preparation method specifically includes: after depositing a first metal layer and a first electrochromic layer on the first surface of the porous layer, and after depositing a counter electrode on the second surface of the porous layer, at least one of the following methods—but not limited to—coating, spraying, impregnation, and potting—is used to fill the porous layer with a photocurable electrolyte, followed by the aforementioned phototreatment to solidify the electrolyte into a solid electrolyte. This method allows the porous structure of the porous layer to be efficiently filled with electrolyte, increasing the electrolyte content in the electrochromic device. This enables the electrolyte to have more uniform and sufficient contact with the first metal layer and the counter electrode, thereby ensuring the electrical performance of the electrochromic device. Furthermore, after the electrolyte is photocured to form a solid electrolyte, it also strengthens the bonding strength between the first metal layer, the counter electrode, and the porous layer, improving the mechanical properties of the electrochromic device.

[0083] In one embodiment, the light used in the illumination process includes, but is not limited to, ultraviolet light.

[0084] Preferably, the photocurable electrolyte may include 30-50 wt% polymer, 10-25 wt% ionic salt, 0.1-1.0 wt% photoinitiator, and 35-45 wt% solvent. The polymer, ionic salt, photoinitiator, and solvent are as described above. By using this curable electrolyte, a UV-curable electrolyte can be formed, which not only possesses the aforementioned advantages but also significantly improves the surface color quality of the multi-color electrochromic device described in this application and greatly increases its color switching speed. This effect is unprecedented in conventional sandwich-structured electrochromic devices using existing photocurable electrolytes, which is very surprising.

[0085] In a typical implementation, a multi-color electrochromic device has an ultra-thin, integrated structure, and its fabrication method includes the following steps:

[0086] S1. A porous substrate is provided as a porous layer, and a first metal layer and a first electrochromic layer are sequentially deposited on the first surface of the porous substrate by physical vapor deposition, and an ion storage layer and a conductive layer are sequentially deposited on the second surface of the porous substrate by physical vapor deposition.

[0087] S2. The porous substrate is made to adsorb the photocurable electrolyte, and then the electrolyte is solidified into a solid electrolyte by ultraviolet light irradiation. Electrodes are then led out from the two opposite sides of the formed electrochromic device to complete the device fabrication.

[0088] The materials, dimensions, and structures of the first and second electrochromic layers, the first and second metal layers, the porous layer, the electrolyte, etc., are as described above and will not be explained in detail here.

[0089] Some embodiments of this application also provide a method of using the multi-color electrochromic device, including: adjusting the potential difference between the first metal layer and the counter electrode, so that ions in the electrolyte stored in the porous layer are inserted into the electrochromic layer, causing the refractive index of the electrochromic material to change, thereby dynamically controlling the color of the electrochromic device.

[0090] Some embodiments of this application also provide a display device that includes the electrochromic device.

[0091] The technical solution of this application will be described in more detail below with reference to the accompanying drawings and several embodiments. However, it should be understood that the following embodiments are merely for explaining and illustrating the technical solution, and do not limit the scope of this application. Furthermore, unless otherwise specified, the various raw materials, reaction equipment, detection equipment, and methods used in the following embodiments are all known in the art.

[0092] Example 1: The structure of an ultra-thin integrated multi-color electrochromic device provided in this example is as follows. Figure 2 As shown, the structure includes, from top to bottom, a first electrochromic layer 11, a first metal layer 12, a porous layer 13, an ion storage layer 14, and a conductive layer 15. The porous layer 13 is a nylon film with a thickness of approximately 50 μm. The nylon film has multiple pores distributed on it, each with a pore size of approximately 800 nm to 1000 nm. These pores are filled with an ultraviolet light-curable electrolyte, which is in direct contact with the first electrochromic layer 11, the first metal layer 12, and the ion storage layer 14.

[0093] Both the ion storage layer 14 and the conductive layer 15 are ITO layers with a thickness of approximately 200 nm. The first metal layer is a W metal layer with a thickness of approximately 100 nm, which is deposited in situ on the porous layer 13 and also has a porous structure. The electrochromic layer is a WO3 layer with a thickness of approximately 145 nm.

[0094] The precursor of the UV-curable electrolyte, namely the UV-curable electrolyte solution, contains 40 wt% polyacrylate, 20 wt% LITFSI, 0.4 wt% photoinitiator DMPA, and the balance eutectic solvent (DES), with the total content of all components being 100 wt%.

[0095] The two opposing surfaces of the first electrochromic layer 11 are both mirror-like, thus forming a Fabry-Perot resonant cavity. The first electrochromic layer 11 also forms a metal-dielectric structure with the first metal layer 12.

[0096] The overall thickness of this multi-color electrochromic device is 97μm, and it can achieve single-sided multi-color electrochromic properties.

[0097] A method for preparing this multi-color electrochromic device includes:

[0098] S1. A first metal layer and a first electrochromic layer are sequentially deposited on the first side (front side) of the porous layer using magnetron sputtering, and an ion storage layer and a conductive layer are sequentially deposited on the second side (back side) of the porous substrate using magnetron sputtering.

[0099] S2. The porous substrate is immersed in ultraviolet light curing electrolyte to fully absorb the ultraviolet light curing electrolyte. Then, the ultraviolet light absorbed by the porous substrate is fully irradiated to solidify the ultraviolet light curing electrolyte into a solid electrolyte. Electrodes are then led out from the two opposite sides of the formed electrochromic device to complete the device fabrication.

[0100] A photograph of a multi-color electrochromic device obtained in this embodiment is shown below. Figure 3 As shown, its color is orange before power is applied. By applying positive and negative voltages (3V to -3V) between the first metal layer and the conductive layer and adjusting the voltage values, the color of the device can be reversibly switched between orange and green. The color switching speed is approximately 2.4 seconds. (See reference...) Figure 4 By gradually applying voltages of 0V, -1.5V, and -3V, the device can achieve multi-color changes of orange, yellow, and green. (See [reference needed]). Figure 5 .

[0101] Comparative Example 1: The structure of the electrochromic device provided in this comparative example is similar to that of Example 1, but the first electrochromic layer is formed by in-situ thermal oxidation of the surface of the first metal layer, resulting in a rough surface.

[0102] The electrochromic device is orange before being powered on, and turns green after a voltage of -3V is applied. With gradually applied voltages of 0V, -1.5V, and -3V, the device's color changes only between orange and green.

[0103] Comparative Example 2 provides an electrochromic device with a structure similar to that of Example 1, but not only is the porous layer filled with an electrolyte, but a solid electrolyte layer is also disposed between the second side (back side) of the porous layer and the ion storage layer. The type and content of the electrolyte in this solid electrolyte layer are the same as those of the UV-curable electrolyte in Example 1.

[0104] The electrochromic device has an overall thickness of 300 μm, is orange before being powered on, and turns green after a voltage of -3V is applied, with a response time of 3 seconds.

[0105] Comparative Example 3 provides an electrochromic device with a structure similar to that of Example 1, but the UV-curing electrolyte is replaced with a PVDF-PC-LiPF6 gel electrolyte. This gel electrolyte contains 20 wt% LiPF6.

[0106] The overall thickness of the electrochromic device is 300 μm. Before being energized, the device is wetted with gel electrolyte and appears as a darker orange than in Example 1. After applying a voltage of -3V, it appears as a darker green, with a response time of 3s.

[0107] Comparative Example 4 provides an electrochromic device with a structure similar to that of Example 1, but the ultraviolet curing electrolyte is replaced with the commonly used electrochromic electrolyte PC-LiClO4.

[0108] The overall thickness of this electrochromic device is 150 μm, such as Figure 6 As shown, after being wetted with liquid electrolyte, the device exhibits a darker orange color than the device in Example 1, and its reflectivity decreases by 53.6%, severely affecting the color quality of the device. After applying a voltage of -3V, it exhibits a dark green color with a response time of 3 seconds. Figure 6 In the comparison example 4, “ultra-thin multi-color device + non-curing electrolyte” corresponds to the device in the comparison example 4, and “ultra-thin multi-color device + UV curing electrolyte” corresponds to the device in example 1.

[0109] In addition, the devices of Example 1, Comparative Example 3, and Comparative Example 4 were subjected to multiple bending and impact tests under the same conditions. The results showed that the device of Example 1 remained essentially unchanged in terms of structure and electrochromic performance. However, the devices of Comparative Examples 3 and 4 could not recover their initial shape after bending. The device of Comparative Example 3 showed slight structural changes and significant alterations in electrochromic performance after multiple impacts, mainly manifested as a significant slowdown in color switching speed. The device of Comparative Example 4 showed leakage and uneven electrolyte distribution after multiple impacts, and failed to change color after being energized.

[0110] Example 2 This example provides a structure for an ultra-thin, integrated, multi-color electrochromic device as follows: Figure 7As shown, the structure includes, from top to bottom, a first electrochromic layer 21, a first metal layer 22, a porous layer 23, a second metal layer 24, and a second electrochromic layer 25. The porous layer 23 is made of porous carbon paper with a thickness of about 100 μm. The porous carbon paper has multiple uniformly distributed pores, each with a pore diameter of about 300 nm. These pores are filled with a UV-curable electrolyte, which is in direct contact with the first electrochromic layer 21, the first metal layer 22, the second metal layer 24, and the second electrochromic layer 25.

[0111] Both the first and second metal layers are W metal layers with a thickness of approximately 100 nm and have a porous structure. The first electrochromic layer is a WO3 layer with a thickness of approximately 85 nm, and the second electrochromic layer is a WO3 layer with a thickness of approximately 390 nm.

[0112] The precursor of the UV-curable electrolyte, namely the UV-curable electrolyte solution, contains 30 wt% polyvinyl chloride, 25 wt% LiClO4, 0.1 wt% photoinitiator OMBB, and the balance dimethyl carbonate, with the total content of all components being 100 wt%.

[0113] A method for preparing this multi-color electrochromic device includes:

[0114] S1. A first metal layer and a first electrochromic layer are sequentially deposited on the first side (front side) of the porous layer using magnetron sputtering, and a second metal layer and a second electrochromic layer are sequentially deposited on the second side (back side) of the porous substrate using magnetron sputtering.

[0115] S2. The porous substrate is immersed in ultraviolet light curing electrolyte to fully absorb the ultraviolet light curing electrolyte. Then, the ultraviolet light absorbed by the porous substrate is fully irradiated to solidify the ultraviolet light curing electrolyte into a solid electrolyte. Electrodes are then led out from the two opposite sides of the formed electrochromic device to complete the device fabrication.

[0116] The multi-color electrochromic device fabricated in this embodiment has an overall thickness of 97 μm. Before being energized, its front side is orange and its back side is indigo. Figures 8a-8c As shown. By applying positive and negative voltages (-4V to 4V) between the first and second metal layers and adjusting the voltage values, the front color of the device can be reversibly switched between orange and green, and the back color between indigo and dark blue. The color switching speed is approximately 2.5 seconds. See [reference needed]. Figures 9a-9c Applying more precise voltages, such as 0V, -1.5V, and -4V, allows for a variety of color variations on the front side, ranging from orange, yellow, and green, and on the back side, ranging from indigo, light blue, and dark blue.

[0117] Example 3: The structure of the ultra-thin integrated multi-color electrochromic device provided in this example is similar to that in Example 1, also including a first electrochromic layer, a first metal layer, a porous layer, an ion storage layer, and a conductive layer arranged sequentially from top to bottom. The difference between the two is:

[0118] The porous layer is a porous PP membrane with a thickness of approximately 100 μm. The porous PP membrane has multiple uniformly distributed pores with a pore size of approximately 1000 nm. These pores are filled with a UV-curable electrolyte, which is in direct contact with the first electrochromic layer 21, the first metal layer 22, and the ion storage layer 24. The ion storage layer 24 is a NiO layer with a thickness of approximately 200 nm. The conductive layer 25 is an ITO layer with a thickness of approximately 200 nm. The first metal layer is a W layer with a thickness of approximately 100 nm, which is deposited in situ on the porous PP membrane and also has a porous structure. The first electrochromic layer is a WO3 layer with a thickness of approximately 145 nm.

[0119] The two opposing surfaces of the first electrochromic layer 21 are both mirror-like, thus forming a Fabry-Perot resonant cavity. The first electrochromic layer 21 and the first metal layer 22 also form a metal-dielectric structure.

[0120] The precursor of the UV-curable electrolyte, namely the UV-curable electrolyte solution, contains 50 wt% polyethylene oxide, 14 wt% CsPF6 lithium salt, 1 wt% photoinitiator TPO-L, and the balance ethylene carbonate, with the total content of all components being 100 wt%.

[0121] A method for preparing this multi-color electrochromic device includes:

[0122] S1. A first metal layer and a first electrochromic layer are sequentially deposited on the first side (front side) of the porous layer using magnetron sputtering, and an ion storage layer and a conductive layer are sequentially deposited on the second side (back side) of the porous substrate using magnetron sputtering.

[0123] S2. The porous substrate is immersed in ultraviolet light curing electrolyte to fully absorb the ultraviolet light curing electrolyte. Then, the ultraviolet light absorbed by the porous substrate is fully irradiated to solidify the ultraviolet light curing electrolyte into a solid electrolyte. Electrodes are then led out from the two opposite sides of the formed electrochromic device to complete the device fabrication.

[0124] The multi-color electrochromic device fabricated in this embodiment has an overall thickness slightly greater than 100 μm. Before being energized, its front side is orange and its back side is brown. By applying positive and negative voltages (-4V to 4V) between the first metal layer and the conductive layer, the front side color of the device can be reversibly switched between orange and green, and the back side color can be reversibly switched between brown and white. Adjusting more precise voltage values ​​of 0V, -1.5V, and -4V allows for multi-color changes in the front side color, including orange, yellow, and green.

[0125] Example 4: The structure of an ultra-thin integrated multi-color electrochromic device provided in this example is as follows. Figure 10 As shown, the structure includes, from top to bottom, a first metal layer 31, a first electrochromic layer 32, a second metal layer 33, a porous layer 34, a third metal layer 35, and a second electrochromic layer 36. The porous layer is a PES porous membrane with a thickness of approximately 40 μm, containing multiple pores with a diameter of 100 nm to 200 nm. These pores are filled with a UV-curable electrolyte, which is in direct contact with the first metal layer 31, the first electrochromic layer 32, the second metal layer 33, the third metal layer 35, and the second electrochromic layer 36.

[0126] The added first metal layer 31 can improve the saturation of the color on the upper surface of the device.

[0127] The first metal layer 31 is a Ni layer with a thickness of 8 nm. The second and third metal layers are both W layers with a thickness of approximately 100 nm. The first and second electrochromic layers are WO3 layers with a thickness of 85–390 nm.

[0128] The precursor of the UV-curable electrolyte, namely the UV-curable electrolyte solution, contains 45 wt% polymethyl methacrylate, 10 wt% LiAsF6, 0.5 wt% photoinitiator ITX, and the balance diethyl carbonate, with the total content of all components being 100 wt%.

[0129] A method for preparing this multi-color electrochromic device includes:

[0130] S1. A first metal layer, a first electrochromic layer, and a second metal layer are sequentially deposited on the first side (front side) of the porous layer using magnetron sputtering, and a third metal layer and a second electrochromic layer are sequentially deposited on the second side (back side) of the porous substrate using magnetron sputtering.

[0131] S2. The porous substrate is immersed in ultraviolet light curing electrolyte to fully absorb the ultraviolet light curing electrolyte. Then, the ultraviolet light absorbed by the porous substrate is fully irradiated to solidify the ultraviolet light curing electrolyte into a solid electrolyte. Electrodes are then led out from the two opposite sides of the formed electrochromic device to complete the device fabrication.

[0132] This embodiment yields a multi-color electrochromic device (i.e., Figures 11-12 The overall thickness of the Ni sample is 50 μm. Before being energized, its front side is red, compared to the control sample (i.e., lacking the first metal layer). Figures 10-11 The Ni-free sample (in which the saturation is higher) has a higher saturation. See [reference needed]. Figure 11 By applying positive and negative voltages (-4V to 4V) between the first metal layer and the conductive layer, and adjusting the voltage value, the front color of the device can be reversibly switched between red and grass green. Compared with the control sample lacking the first metal layer, its color saturation is also higher. (See reference...) Figure 12 .

[0133] Example 5

[0134] The structure of the multicolor electrochromic device provided in this embodiment is similar to that of Embodiment 1, except that: a polyurethane-PC-LiClO4 gel electrolyte is used instead of the UV-curable electrolyte in Embodiment 1. Also, a porous polypropylene film with a thickness of approximately 300 μm is used instead of the nylon film, and the pore size of the porous polypropylene film is approximately 500 nm to 1000 nm.

[0135] This multi-color electrochromic device exhibits rigidity after the electrolyte is cured, with a thickness of approximately 310 μm, and cannot be bent. Similar to Example 1, this electrochromic device also exhibits multi-color changes when a voltage of -3V to 3V is applied, with a response time of 4s.

[0136] Example 6

[0137] The structure of the multicolor electrochromic device provided in this embodiment is similar to that in Embodiment 1, except that a polyaniline layer of the same thickness (with reflective surfaces on both sides) is used instead of the tungsten oxide layer in Embodiment 1 as the electrochromic layer.

[0138] This electrochromic device can reversibly switch between tan and green when -3V and 3V voltages are applied, with a response time of 2s.

[0139] Example 7

[0140] The structure of the multicolor electrochromic device provided in this embodiment is similar to that in Embodiment 1, except that: the tungsten oxide layer in Embodiment 1 is replaced by a PEDOT:PSS layer of the same thickness (with reflective surfaces on both sides) as the electrochromic layer.

[0141] This electrochromic device can reversibly switch between yellow and dark blue when -3V and 3V voltages are applied, with a response time of 1 second.

[0142] Example 8

[0143] The structure of the multicolor electrochromic device provided in this embodiment is similar to that in Embodiment 1, except that a Prussian blue layer (with reflective surfaces on both sides) of the same thickness is used instead of the tungsten oxide layer in Embodiment 1 as the electrochromic layer.

[0144] This electrochromic device can reversibly switch between light yellow and dark blue when a voltage of -3V and 3V is applied, with a response time of 2.5s.

[0145] Example 9

[0146] The structure of the multicolor electrochromic device provided in this embodiment is similar to that of Embodiment 1, except that a porous alumina film (prepared by anodizing) with a thickness of about 30 μm is used instead of the porous nylon film in Embodiment 1. This porous alumina film has multiple uniformly distributed pores with a diameter of about 500 nm, and the conductive layer is disposed on a transparent glass substrate.

[0147] The multicolor electrochromic device is approximately 30μm thick. When an electrolyte is added, the color will shift to blue, such as yellow turning into green. When a voltage of -3V and 3V is applied, a reversible switch between green and dark blue can be achieved with a response time of 3s.

[0148] Example 10

[0149] The structure of the multicolor electrochromic device provided in this embodiment is similar to that in Embodiment 1, except that the WO3 layer is replaced with a V2O5 layer of the same thickness.

[0150] The initial color of this multi-color electrochromic device is green. When a -3V voltage is applied, the device changes to blue. When a +3V voltage is applied, the device gradually changes to yellow, with a switching time of approximately 4 seconds.

[0151] Example 11

[0152] The structure of the multicolor electrochromic device provided in this embodiment is similar to that in Embodiment 1, except that the WO3 layer is replaced with an Nb2O5 layer of the same thickness.

[0153] The initial color of this multi-color electrochromic device is orange. When a -3V voltage is applied, the device color gradually changes to brown and then dark brown, with a switching time of approximately 4 seconds.

[0154] Example 12

[0155] The structure of the multicolor electrochromic device provided in this embodiment is similar to that in Embodiment 1, except that the WO3 layer is replaced with a MoO3 layer of the same thickness.

[0156] The initial color of this multi-color electrochromic device is yellow. When a -3V voltage is applied, the device color gradually changes to green and then blue-gray, with a switching time of approximately 3 seconds.

[0157] It should be noted that the above description is only a preferred embodiment of this application and is not intended to limit this application. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A multi-color electrochromic device, characterized in that... include: A porous layer having a first and a second surface facing away from each other; Electrolytes are filled within the porous layer; A first metal layer having a porous structure is disposed on a first surface of the porous layer; A first electrochromic layer is disposed on the first metal layer, and both sides of the first electrochromic layer in the thickness direction are reflective surfaces, thereby forming a first optical resonant cavity, the first optical resonant cavity including a Fabry-Perot resonant cavity. The electrode is disposed on the second surface of the porous layer.

2. The multi-color electrochromic device according to claim 1, characterized in that: The counter electrode includes a conductive layer and / or an ion storage layer, wherein the ion storage layer is disposed between the conductive layer and the second surface of the porous layer.

3. The multi-color electrochromic device according to claim 1, characterized in that: The counter electrode includes a second metal layer and a second electrochromic layer. The second electrochromic layer is disposed on the counter electrode. The second metal layer is located between the second electrochromic layer and the second surface of the porous layer. Both sides of the second electrochromic layer in the thickness direction are reflective surfaces, thereby forming a second optical resonant cavity. The second optical resonant cavity includes a Fabry-Perot resonant cavity.

4. The multi-color electrochromic device according to claim 3, characterized in that: The thickness of the second electrochromic layer is >0 and ≤2000 nm.

5. The multi-color electrochromic device according to claim 4, characterized in that: The thickness of the second electrochromic layer is 100–500 nm.

6. The multi-color electrochromic device according to claim 3, characterized in that: The thickness of the second metal layer is >0 and ≤2000 nm.

7. The multi-color electrochromic device according to claim 6, characterized in that: The thickness of the second metal layer is 90–150 nm.

8. The multi-color electrochromic device according to claim 3, characterized in that: The second metal layer has a porous structure.

9. The multi-color electrochromic device according to claim 3, characterized in that: The material of the second electrochromic layer includes inorganic electrochromic materials and / or organic electrochromic materials.

10. The multi-color electrochromic device according to any one of claims 1-9, characterized in that: The thickness of the first electrochromic layer is >0 and ≤2000 nm.

11. The multi-color electrochromic device according to claim 10, characterized in that: The thickness of the first electrochromic layer is 100–500 nm.

12. The multi-color electrochromic device according to any one of claims 1-9, characterized in that: The thickness of the first metal layer is >0 and ≤2000 nm.

13. The multi-color electrochromic device according to claim 12, characterized in that: The thickness of the first metal layer is 90–150 nm.

14. The multicolor electrochromic device according to any one of claims 1-9, characterized in that: The porous layer contains pores with a diameter of 100nm to 1000nm.

15. The multicolor electrochromic device according to any one of claims 1-9, characterized in that: The thickness of the porous layer is >0 and ≤1000μm.

16. The multi-color electrochromic device according to claim 15, characterized in that: The thickness of the porous layer is >0 and ≤100μm.

17. The multicolor electrochromic device according to any one of claims 1-9, characterized in that: The material of the first electrochromic layer includes inorganic electrochromic materials and / or organic electrochromic materials.

18. The multicolor electrochromic device according to any one of claims 1-9, characterized in that: The electrolyte is in direct contact with both the first metal layer and the counter electrode.

19. The multicolor electrochromic device according to any one of claims 1-9, characterized in that: The electrolyte includes a photocurable electrolyte.

20. The multicolor electrochromic device according to any one of claims 1-9, characterized in that: The first metal layer and the first electrochromic layer are sequentially deposited on the first surface of the porous layer by physical and / or chemical deposition methods.

21. The multicolor electrochromic device according to any one of claims 1-9, characterized in that: The counter electrode is deposited on the second surface of the porous layer by physical and / or chemical deposition.

22. The multicolor electrochromic device according to any one of claims 1-9, characterized in that: The overall thickness of the multicolor electrochromic device is less than 100μm.

23. The multicolor electrochromic device according to any one of claims 1-9, characterized in that: The multicolor electrochromic device further includes a substrate, the counter electrode is connected to the substrate, and the counter electrode is located between the substrate and the second surface of the porous layer.

24. The multicolor electrochromic device according to any one of claims 1-9, characterized in that: The electrolyte comprises 30-50 wt% polymer, 10-25 wt% ionic salt, 0.1-1.0 wt% photoinitiator, and 35-45 wt% solvent.

25. A method for preparing the multi-color electrochromic device according to any one of claims 1-24, characterized in that, include: A porous layer is provided, the porous layer having a first side and a second side facing away from each other; A first metal layer and a first electrochromic layer are sequentially disposed on the first surface of the porous layer. Both sides of the first electrochromic layer in the thickness direction are reflective surfaces, thereby forming a first optical resonant cavity. A counter electrode is disposed on the second surface of the porous layer; And, an electrolyte is filled in the porous layer.

26. The method for preparing a multi-color electrochromic device according to claim 25, characterized in that, Specifically, it includes: The first metal layer and the first electrochromic layer are sequentially formed on the first surface of the porous layer by physical and / or chemical deposition.

27. The method for preparing a multi-color electrochromic device according to claim 25, characterized in that, Specifically, it includes: The counter electrode is formed on the second surface of the porous layer by physical and / or chemical deposition.

28. The method for preparing a multi-color electrochromic device according to claim 25, characterized in that, Specifically, it includes: The second metal layer and the second electrochromic layer are sequentially formed on the second surface of the porous layer by physical and / or chemical deposition, thereby forming the counter electrode. The two surfaces of the second electrochromic layer in the thickness direction are both reflective surfaces, thereby forming the second optical resonant cavity.

29. The method for preparing a multi-color electrochromic device according to claim 28, characterized in that: The first optical resonant cavity and the second optical resonant cavity include Fabry-Perot resonant cavities.

30. The method for preparing a multi-color electrochromic device according to claim 28, characterized in that: The physical and / or chemical deposition methods include any one or a combination of magnetron sputtering, electron beam evaporation, thermal evaporation, and ion plating.

31. The method for preparing a multi-color electrochromic device according to claim 25, characterized in that, Specifically, it includes: The porous layer absorbs a photocurable electrolyte, and then the porous layer is subjected to light irradiation to solidify the electrolyte into a solid electrolyte.

32. The method for preparing a multi-color electrochromic device according to claim 31, characterized in that, Specifically, it includes: After a first metal layer and a first electrochromic layer are disposed on the first side of the porous layer, and a counter electrode is disposed on the second side of the porous layer, a photocurable electrolyte is filled into the porous layer by at least one of the following methods: scraping, spraying, impregnation, and potting. Then, the aforementioned phototreatment is performed to solidify the electrolyte into a solid electrolyte.

33. The method for preparing a multi-color electrochromic device according to claim 31, characterized in that... The light used in the light treatment includes ultraviolet light.

34. The method for preparing a multi-color electrochromic device according to claim 31, characterized in that: The photocurable electrolyte comprises 30-50 wt% polymer, 10-25 wt% ionic salt, 0.1-1.0 wt% photoinitiator, and 35-45 wt% solvent.

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