A mid-infrared regulation performance enhanced all-solid-state electrochromic device and a preparation method thereof

Abstract

The application relates to a mid-infrared regulation performance enhanced full-solid-state electrochromic device and a preparation method thereof. The structure of the mid-infrared regulation performance enhanced full-solid-state electrochromic device comprises a transparent substrate, a first transparent electrode, an electrolyte layer, an electron blocking layer, a micro-nano processed electrochromic layer, a second transparent electrode and a surface high-transparency substrate which are sequentially stacked.

Description

Technical Field

[0001] This invention belongs to the technical field of electrochromic functional materials and devices, specifically relating to a mid-infrared modulated performance enhanced all-solid-state electrochromic device and its preparation method. Background Technology

[0002] Statistics show that building energy consumption accounts for over 40% of total societal energy consumption. Currently, there are two main methods for reducing building energy consumption: active and passive energy conservation. Active energy conservation improves energy efficiency through comprehensive optimization of the HVAC system, thereby reducing energy consumption. Passive energy conservation, on the other hand, achieves this by improving the insulation performance of the heat exchange medium between the building and the outside environment. For example, improving the insulation performance of building walls, roofs, doors, and windows reduces heat loss and dissipation, thus lowering building energy consumption. Furthermore, due to lighting and design requirements, the proportion of window glass in building structures is gradually increasing; however, window glass has the worst insulation performance among building structures. Statistical simulations show that heat exchange through windows accounts for 70% in summer and 60% in winter, indicating that buildings consume a significant portion of their energy through windows. Therefore, reducing energy loss through windows is crucial for improving building energy efficiency.

[0003] Heat exchange through windows involves heat conduction, convection, and radiation. Radiative heat exchange encompasses solar radiation in the visible (380–780 nm) and near-infrared (780–2500 nm) ranges, as well as spontaneous room temperature radiation in the mid-infrared "atmospheric window" (8–14 μm). However, ordinary windows generally lack the ability to dynamically regulate visible and near-infrared solar radiation, and their room temperature radiation regulation capability is weak, leading to higher building energy losses. On one hand, the transmittance of visible and near-infrared light is difficult to control independently, and the high natural light transmittance required for indoor lighting sacrifices some solar radiation regulation capability. On the other hand, window glass is primarily composed of silicon dioxide, which exhibits strong absorption (i.e., high emission) in light wavelengths above 4 μm. Therefore, in summer, the outdoor environment and window surface temperatures are higher than indoor temperatures, causing continuous heat radiation into the room; in winter, the outdoor and window surface temperatures are lower, causing continuous heat radiation outwards, resulting in a significant increase in air conditioning energy consumption for both summer cooling and winter heating.

[0004] Electrochromism refers to the phenomenon where the optical properties of a material (reflectivity, transmittance, absorptivity, etc.) undergo stable and reversible changes under the influence of an applied electric field, manifesting as reversible changes in color and transparency. Electrochromic devices generally consist of a transparent electrode, an electrochromic layer, an ion-conducting layer (also called an electrolyte layer), an ion storage layer, and another transparent electrode. WO3 is the most widely used inorganic electrochromic material. The ion-conducting layer provides an ion transport channel between the electrochromic layer and the ion storage layer, requiring compatibility with the materials of both sides of the film and possessing good electronic insulation and ionic conductivity. Electrochromic smart windows fabricated using electrochromic materials offer a series of advantages, including continuously and precisely adjustable optical properties, strong resistance to environmental interference, good adaptability, low power consumption, and fast color application / fading response. Therefore, compared to other stimulation methods, electrochromic smart windows have significant advantages.

[0005] However, current research on wide-band adjustable electrochromic devices mainly revolves around the controllable deposition of metal ions, utilizing the high emissivity and low reflectivity of the mid-infrared region after metal deposition to construct devices with adjustable emissivity. However, these devices often use liquid electrolytes, leading to problems such as easy leakage, poor stability, and safety concerns. Furthermore, they face challenges during amplification, including poor uniformity and low coloring rates. Meanwhile, all-solid-state electrochromic devices often suffer from limited wide-band adjustment or weak control capabilities. Typically, they can only control visible and near-infrared light (0.38-2.5 μm) covered by sunlight, making it difficult to utilize deep-space cold energy for radiative heat management through the "atmospheric window" (8-14 μm). Effective management of mid-infrared radiative heat would significantly improve building energy efficiency. Summary of the Invention

[0006] To address the aforementioned technical problems, the present invention aims to provide a mid-infrared modulated all-solid-state electrochromic device and its preparation method.

[0007] In a first aspect, the present invention provides a mid-infrared-modulated performance-enhanced all-solid-state electrochromic device, the structure of which includes: a transparent substrate, a first transparent electrode, an electrolyte layer, an electron blocking layer, a micro / nano-fabricated electrochromic layer, a second transparent electrode, and a highly transparent substrate, which are sequentially stacked.

[0008] Preferably, the materials of the first and second transparent electrodes include at least one of transparent conductive oxide, MXENE, and metal nanowires, with a sheet resistance of 10–400 Ω / cm. 2 ;

[0009] Preferably, the first transparent electrode has a solar transmittance of ≥75% in the 0.38-2.5μm wavelength band and a mid-infrared reflectance of ≥75% in the 8-14μm wavelength band, and the second transparent electrode has a solar transmittance of ≥75% in the 0.38-2.5μm wavelength band and a mid-infrared transmittance of ≥75% in the 8-14μm wavelength band.

[0010] Preferably, the electrolyte layer is a cationic gel conductive layer based on an organic resin, wherein the cationic cations include Li. + Al 3+ Mg 2+ Zn 2+ K + and Na + At least one of the following; preferably, the thickness of the electrolyte layer is 0.6-5 μm.

[0011] Preferably, the electron blocking layer is made of a wide bandgap material, preferably SiO2, Al2O3, or SnO2, and has a thickness of 5-20 nm.

[0012] Preferably, the material of the micro / nano-fabricated electrochromic layer includes WO3. 3-x1 MoO 3-x2 TiO 2-x3 It contains at least one of V2O5, where x1 ranges from 0 to 0.8, x2 ranges from 0 to 0.8, and x3 ranges from 0 to 0.5; the thickness is 200 to 600 nm.

[0013] Preferably, the electrochromic layer fabricated by micro-nano processes comprises nano-columnar crystals with attached nanoparticles; wherein the diameter of the nano-columnar crystals is 5-50 nm, the distance between the nano-columnar crystals is 5-30 nm, and the particle size of the nanoparticles is 2-20 nm; in the electrochromic layer fabricated by micro-nano processes, the volume ratio of nanoparticles to nano-columnar crystals is 1:5-50;

[0014] Preferably, the processing cycle of the micro-nano fabricated electrochromic layer is 0.5-50um×0.5-50um, the processing depth is 50nm-thickness of the electrochromic layer, and the processing gap is 100-400nm.

[0015] Preferably, the material of the high-transparency substrate includes one of barium fluoride, calcium fluoride, magnesium fluoride, zinc sulfide, zinc selenide, sodium chloride, silicon, germanium, sapphire, polyethylene, and poly(4-methyl-1-pentene);

[0016] Preferably, the high-transmittance substrate has a solar transmittance of ≥85% in the 0.38-2.5μm wavelength band and a mid-infrared transmittance of ≥85% in the 2.5-25μm wavelength band.

[0017] Secondly, the present invention provides a method for fabricating the above-mentioned mid-infrared modulated performance enhanced all-solid-state electrochromic device, the fabrication method comprising the following steps:

[0018] (1) A first transparent electrode was prepared on the surface of a transparent substrate by magnetron sputtering, and a second transparent electrode and an electrochromic layer were prepared sequentially on a high-transparency substrate.

[0019] (2) The electrochromic layer film is micro-nano-fabricated according to the designed size using electron beam etching process to obtain a micro-nano-fabricated electrochromic layer;

[0020] (3) An electron blocking layer was prepared on the surface of the micro-nano fabricated electrochromic layer using atomic layer deposition process;

[0021] (4) The electrolyte solution is filled between the electron blocking layer and the first transparent electrode by vacuum drip irrigation and then cured to obtain the mid-infrared modulation performance enhanced all-solid-state electrochromic device.

[0022] Preferably, in step (1), the process parameters for preparing the electrochromic layer by magnetron sputtering include: using tungsten, molybdenum, titanium, or vanadium as the target material; using methane, argon, and oxygen as the sputtering gas; a total pressure of 0.5-2.0 Pa; a methane partial pressure of 0.5-2%; an oxygen partial pressure of 0-50%; a target-to-substrate distance of 10-20 cm; an initial substrate temperature of room temperature; and a DC power supply applied to the target of 30-150 W or a power density of 0.6-3.0 W / cm². 2 .

[0023] Preferably, step (1) further includes an annealing heat treatment after the electrochromic layer is prepared by magnetron sputtering; wherein the annealing heat treatment process includes: heating from room temperature to 200-375°C at a heating rate of 5-50°C / s and holding at that temperature for 2-60 minutes, and then naturally cooling to room temperature.

[0024] Preferably, in step (2), the process parameters for electron beam etching for micro / nano fabrication include: accelerating voltage 10-100kV, beam current 1-50pA, scanning step size ≤ 1 / 4 of linewidth, and photoresist sensitivity 20-500μC / cm. 2 .

[0025] Beneficial effects

[0026] (1) This invention achieves wide-band modulation from visible light to mid- and far-infrared by designing a simple all-solid-state electrochromic structure, which can achieve excellent energy-saving effects in major regions around the world.

[0027] (2) The present invention significantly enhances the device’s ability to adjust in the mid- and far-infrared, especially in the “atmospheric window” band of 8-13μm, through micro- and nano-structure design;

[0028] (3) The preparation method provided by the present invention is simple and easy to operate. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of an exemplary structure of the all-solid-state electrochromic device with enhanced mid-infrared modulation performance provided by the present invention.

[0030] Figure 2 This is a cross-sectional SEM image of an electrochromic layer fabricated using micro-nano processes, as an example of the present invention. Detailed Implementation

[0031] The present invention will be further illustrated by the following embodiments. It should be understood that the following embodiments are for illustrative purposes only and are not intended to limit the present invention.

[0032] First, such as Figure 1 As shown, the present invention provides a mid-infrared-modulated performance-enhanced all-solid-state electrochromic device. The structure of the mid-infrared-modulated performance-enhanced all-solid-state electrochromic device may include: a transparent substrate, a first transparent electrode, an electrolyte layer, an electron blocking layer, a micro / nano-fabricated electrochromic layer, a second transparent electrode, and a highly transparent substrate, stacked sequentially.

[0033] In some embodiments, the transparent substrate may be made of glass, polymethyl methacrylate (PMMA), or polycarbonate (PC); and the thickness may be 0.05-5 mm.

[0034] In some embodiments, the materials of the first and second transparent electrodes may include at least one of transparent conductive oxides (such as indium tin oxide, ITO), MXENE, and metal nanowires, and the sheet resistance may be 10–400 Ω / cm. 2 Preferably, the first transparent electrode has a solar transmittance of ≥75% in the 0.38-2.5μm wavelength band and a mid-infrared reflectance of ≥75% in the 8-14μm wavelength band; the second transparent electrode has a solar transmittance of ≥75% in the 0.38-2.5μm wavelength band and a mid-infrared transmittance of ≥75% in the 8-14μm wavelength band. The first transparent electrode is the bottom infrared reflective electrode of the device. If its reflectivity is insufficient, the infrared modulation capability of the device will significantly decrease; similarly, if the transmittance of the second transparent electrode is insufficient, the infrared modulation capability of the device will significantly decrease.

[0035] In some embodiments, the electrolyte layer may be an organic resin-based cationic gel conductive layer, and the cation may include Li. + Al 3+ Mg 2+ Zn 2+ K + and Na+ At least one of the following; preferably, the thickness of the electrolyte layer can be 0.6-5 μm. However, if the electrolyte layer is too thick, its infrared transmittance will decrease, resulting in a reduction in the infrared modulation capability of the device.

[0036] In some embodiments, the electron blocking layer can be made of a material with a band gap width ≥ 4.5 eV, preferably SiO2, Al2O3, or SnO2; the thickness can be 5-20 nm. By providing an electron blocking layer, the second transparent electrode, such as ITO, can be prevented from directly contacting the electrolyte, thus preventing internal short circuits in the device. Too thin a layer is not conducive to the fabrication of continuous thin films; too thick a layer will affect the optical structure of the device, leading to a decrease in the device's infrared modulation capability. As an internal insulating protective layer, if the electron blocking layer is too thin, internal conductivity is easily achieved; if it is too thick, ion migration speed is slowed down. The electron blocking layer affects the overall modulation performance of the device.

[0037] In some embodiments, the material of the micro / nano-fabricated electrochromic layer may include WO3. 3-x1 MoO 3-x2 TiO 2-x3 It contains at least one of V2O5, where x1 can range from 0 to 0.8, x2 can range from 0 to 0.8, and x3 can range from 0 to 0.5; the thickness can be 200 to 600 nm.

[0038] Among them, such as Figure 2 As shown, the composition of the micro / nano-fabricated electrochromic layer may include nano-columnar crystals with attached nanoparticles; wherein, the diameter of the nano-columnar crystals may be 5-50 nm, the distance between the nano-columnar crystals may be 5-30 nm, and the particle size of the nanoparticles may be 2-20 nm; in the micro / nano-fabricated electrochromic layer, the volume ratio of nanoparticles to nano-columnar crystals may be 1:5-50.

[0039] In some embodiments, the processing cycle of the micro-nano fabricated electrochromic layer can be 0.5-50um×0.5-50um, preferably 1×1um, the processing depth can be 50nm-thickness of the electrochromic layer, and the processing gap can be 100-400nm.

[0040] Typically, all-solid-state electrochromic devices can only modulate the energy of the visible and near-infrared bands covered by sunlight, with limited ability to regulate the mid-infrared band. This is mainly due to two reasons: firstly, the electrochromic layer material has weak regulation performance in the mid-infrared band; secondly, there are limited means to improve the performance of electrochromic devices. This invention primarily achieves mid-infrared band regulation through structural innovation using devices based on inorganic electrochromic materials. Furthermore, based on Mie scattering theory and guided by COMSOL simulations, a reasonable micro / nano fabrication size for the electrochromic layer was designed, resulting in a significant improvement in the mid-infrared (8-14µm) regulation capability within the "atmospheric window."

[0041] Specifically, the micro-nano fabricated electrochromic layer provided by the present invention is composed of periodically and neatly arranged "islands". This can significantly increase the exposed surface of the electrochromic layer, thereby greatly increasing the amount of ions entering the electrochromic surface under low voltage, that is, increasing the surface electron concentration, enhancing the local plasmon resonance absorption of the surface, and ultimately enhancing the control performance in the infrared band.

[0042] Further illustrative explanation: The core structure of the electrochromic device provided by the present invention can be (inner) ITO / electrolyte / WO3 (micro-nano fabrication) / ITO (outer). When no voltage is applied, light is incident from the surface. Since the bottom layer ITO has good infrared reflection performance and the upper layer material has low absorption of mid-infrared, the device as a whole exhibits a state of high infrared reflection. After applying voltage, due to the large number of electrons in WO3 generating local surface plasmon resonance, the infrared absorption capability is greatly enhanced. The device as a whole forms a Fabry-Perot resonant cavity, which further enhances the absorption of infrared, so that the device exhibits excellent modulation performance in the mid-infrared.

[0043] The period, depth, and gap of the electrochromic layer micro / nano fabrication in this invention need to be verified through optical simulation and experiments. By designing appropriate micro / nano fabrication parameters, the micro / nano structure of the electrochromic layer can localize the light field energy within the subwavelength scale through surface plasmon resonance (SPR) or Mie resonance, ensuring that the formed optical structure is a resonant cavity, thereby significantly enhancing the local electric field intensity. If the relevant fabrication parameters are too large or too small, it will affect the mid-infrared modulation capability of the device.

[0044] It is important to note that the technical solution provided by this invention differs from conventional methods that involve inserting a separate metal layer or structural color layer outside the electrochromic layer for micro / nano fabrication to achieve visible light and other wavelength modulation. Conventional methods typically utilize a composite of the electrochromic layer and the structural color layer to achieve the desired performance, or combine the changes in visible light absorption before and after electrochromism with the structural color to achieve multi-channel spectral filtering performance. This invention, however, directly fabricates the electrochromic layer, focusing on improving the device's modulation of the mid-infrared band. The direct micro / nano fabrication of the electrochromic layer increases the electrochromic layer / electrolyte layer interface area, increases the interface electron concentration (enhancing infrared modulation capability), promotes ion migration, strengthens the interface electric field, and improves mid-infrared modulation capability. By designing appropriate micro / nano fabrication dimensions through optical engineering, the electric field polarization and local electric field strength in the mid-infrared band are enhanced, further improving infrared modulation capability.

[0045] It is also important to note that electrochromic layers prepared using conventional techniques are often difficult to apply to direct etching micro / nano fabrication processes. This is primarily because conventionally magnetized WO3 films typically consist of large grains, and the grain size limits the precision of the etched structure during ion beam etching. The electrochromic layer provided by this invention comprises nano-columnar crystals and nanoparticles attached to these crystals. This structure exhibits excellent processing performance and can be used for micro / nano fabrication because achieving ideal perpendicular cutting during etching is generally difficult. Larger grains can fracture, resulting in an angled etch interface. Clearly, smaller particle sizes facilitate higher steepness. The WO3 electrochromic layer film prepared by this invention is composed of even smaller nanocomposite structures, thus exhibiting better precision (steepness) after etching.

[0046] Based on the LSPR effect calculations, the size of the columnar nanocrystals provided by this invention corresponds to near-infrared absorption. Simultaneously, after coloring, the nanoparticles contain a large number of free carriers that undergo in-band transitions under infrared light, resulting in broadband absorption in the mid-infrared band. Increasing the size of the columnar crystals or nanoparticles causes a red shift of the absorption peak to higher wavelengths, while smaller sizes result in a blue shift of the absorption peak to lower wavelengths. Both excessively large and small sizes will affect the optimal absorption position.

[0047] Furthermore, based on the localized surface plasmon resonance (LSPR) effect, different nanoparticle and nanoarray sizes correspond to different absorption peak positions and full width at half maximum (FWHM). LSPR is a collective oscillation phenomenon generated by free electrons in metal or heavily doped semiconductor nanoparticles under incident light excitation. Within a certain size range (typically tens of nanometers), the intensity of the LSPR absorption peak increases with increasing size because larger particles have larger optical cross-sections (absorption and scattering cross-sections), enabling them to interact with light more effectively. The core of the electrochromic process is to reversibly inject / extract electrons and ions (Li+) by applying voltage, thereby changing the oxidation state and free carrier concentration of WO3, etc. To obtain strong LSPR absorption in a specific wavelength range in the colored state (such as the strong NIR absorption required for smart windows mainly used for infrared shielding), it is necessary to precisely control the size and morphology of nanostructures such as WO3. In WO3 electrochromic devices, the LSPR absorption effect mainly occurs on WO3 nanostructures in the deeply reduced (colored) state. Nanoparticle size is one of the key parameters for regulating LSPR characteristics. Increasing the size tends to redshift the LSPR peak and enhance its intensity (within the medium size range), but may also lead to peak broadening due to radiation damping and potentially sacrifice response speed. Decreasing the size tends to blueshift the LSPR peak, broaden its peak width (dominated by surface scattering), and weaken its intensity (when too small), but is beneficial for improving response speed and specific surface area. Therefore, it is necessary to rationally design the size of the nanopillars to balance the device's response speed and resonant absorption capability. Secondly, in the mid-infrared band (especially the 8–14 μm atmospheric window), the electrochromic performance of WO3 mainly depends on free carrier absorption. Free electrons undergo in-band transitions under infrared light, producing broadband absorption, with stronger absorption at longer wavelengths. In this invention, the nanoparticles, due to their large specific surface area, can generate a large number of free electrons even at low voltage, resulting in significant absorption in the mid-infrared. However, when the size increases to a value much larger than the incident light wavelength, the LSPR effect weakens, gradually transitioning to reflective characteristics similar to bulk materials.

[0048] Meanwhile, this invention calculates the nanoparticle and nanoarray sizes based on the dielectric constant and structural parameters of the electrochromic material used. The electron concentration induced by ion entry results in strong absorption in the mid-infrared range. Furthermore, this invention calculates the structural parameters for micro / nano fabrication based on the dielectric constant and structural parameters of the electrochromic material used. Micro / nano fabrication further increases the interface area, expands ion migration channels, and improves the device's response speed.

[0049] In some embodiments, the material of the high-transmittance substrate may include one of barium fluoride, calcium fluoride, magnesium fluoride, zinc sulfide, zinc selenide, sodium chloride, silicon, germanium, sapphire, polyethylene (PE), and poly(4-methyl-1-pentene) (TPX). Preferably, the high-transmittance substrate has a solar transmittance of ≥85% in the 0.38-2.5μm wavelength band and a mid-infrared transmittance of ≥85% in the 2.5-25μm wavelength band. If the infrared transmittance of the transparent electrode is insufficient, it can easily lead to a decrease in the infrared modulation capability of the device; if the transmittance in the solar band is insufficient, it will affect the solar energy regulation capability of the device.

[0050] In some embodiments, the solar band modulation capability of the mid-infrared modulation performance-enhanced all-solid-state electrochromic device is ≥0.5, and the mid- and far-infrared emissivity modulation rate (mid- and far-infrared modulation capability) before and after the phase transition caused by voltage drive is ≥0.4.

[0051] The following is an exemplary description of a method for fabricating a mid-infrared modulated performance-enhanced all-solid-state electrochromic device provided by the present invention. The fabrication method may include the following steps:

[0052] (1) A first transparent electrode was prepared on the surface of a transparent substrate by magnetron sputtering, and a second transparent electrode and an electrochromic layer were prepared sequentially on a high-transparency substrate.

[0053] (2) The electrochromic layer film is micro-nano-fabricated according to the designed size using electron beam etching process to obtain a micro-nano-fabricated electrochromic layer;

[0054] (3) An electron blocking layer was prepared on the surface of the micro-nano fabricated electrochromic layer using atomic layer deposition process;

[0055] (4) The electrolyte solution is filled between the electron blocking layer and the first transparent electrode by vacuum drip irrigation and then cured to obtain the mid-infrared modulation performance enhanced all-solid-state electrochromic device.

[0056] In some embodiments, the process parameters for preparing the electrochromic layer by magnetron sputtering in step (1) may include: using tungsten, molybdenum, titanium, or vanadium as the target material; using methane, argon, and oxygen as the sputtering gas; a total pressure of 0.5-2.0 Pa; a methane partial pressure of 0.5-2%, preferably 1%; an oxygen partial pressure of 0-50%; a target-to-substrate distance of 10-20 cm; an initial substrate temperature of room temperature; and a DC power supply applied to the target of 30-150 W or a power density of 0.6-3.0 W / cm². 2 .

[0057] In some embodiments, step (1) may also include an annealing heat treatment after the electrochromic layer is prepared by magnetron sputtering; wherein the annealing heat treatment process includes: heating from room temperature to 200-375°C at a heating rate of 5-50°C / s and holding at that temperature for 2-60 minutes, and then naturally cooling to room temperature.

[0058] This invention combines magnetron sputtering with subsequent heat treatment. During magnetron sputtering, an appropriate amount of methane gas is introduced to prepare a loosely structured nanopillar structure. During the subsequent rapid annealing heat treatment, due to the rapid heating rate, the loose nanoparticles undergo uneven expansion, and some nanopillars break down, producing small particles. If the proportion of methane gas introduced is too low, only columnar crystals form, failing to form nanoparticles; if too much methane gas is introduced, the nanopillar crystals collapse, leading to increased grain boundaries and affecting ion migration and subsequent processing performance.

[0059] More specifically, the DC magnetron sputtering system used in this invention for magnetron sputtering deposition may include a deposition chamber, a sample inlet chamber, several target heads, a substrate, a DC current source, and a series of mechanical pumps and vacuum pumps. The target head is at a certain angle to the substrate and separated by a certain distance, and the DC power supply is connected to the target head. The substrate is ultrasonically cleaned with acetone, anhydrous ethanol, and deionized water for 20 minutes each, and then dried with compressed air. A portion of the conductive substrate is covered with high-temperature tape as an electrode and fixed to the substrate tray. The substrate is placed in the sample inlet chamber, and the mechanical pump is turned on to evacuate to below 5 Pa. Then, the baffle valve is opened, and the vacuum level (baseline vacuum) is increased to 10. -4 Splash chambers with Pa and below.

[0060] The specific sputtering deposition process is as follows: High-purity argon and oxygen are introduced into the sputtering chamber, with the purity of the argon and oxygen being 99.99% or higher. The total pressure and oxygen partial pressure in the chamber are controlled within the range of 0.5-2.0 Pa and 0-50%, respectively, with the oxygen partial pressure preferably being 0-25%. The vertical distance between the target and the substrate is controlled at 10-20 cm, and the initial substrate temperature is room temperature. The DC power supply is turned on, with the power controlled at 30-200 W. The pre-sputtering time is 5-30 min, the sputtering time is 10-60 min, and the substrate temperature is room temperature. After sputtering, the substrate is removed after the substrate temperature has dropped to room temperature.

[0061] In some embodiments, the process parameters for electron beam etching for micro / nano fabrication in step (2) may include: accelerating voltage 10-100kV, beam current 1-50pA, scanning step size ≤ 1 / 4 of linewidth, and photoresist sensitivity 20-500μC / cm. 2 .

[0062] In some embodiments, the process parameters for preparing the electron blocking layer by atomic layer deposition in step (3) may include: precursor flow rate of 0.1-1 sccm and chamber pressure of 0.1-10 Torr.

[0063] In some embodiments, in step (4), the electrolyte solution can be obtained by mixing solvent, photoresin, stabilizer, ultraviolet absorber, organic precursor and ion source solution in a mass ratio of (1-5):(0.5-5):(0.1-2):(0.01-0.2):(0.5-5):1.

[0064] The solvent may include propylene glycol methyl ether acetate (PMA), N-methylpyrrolidone (NMP), and N,N-dimethylformamide (DMF); the photoresist may be UV-curable resin UC-935 (Xianmeite); the stabilizer may be ferrocene; the UV absorber may be photoinitiator 1173; and the organic precursor may be ethoxylated trimethylolpropane triacrylate (ETPTA).

[0065] The ion source in the ion source solution may include at least one of the chloride, perchlorate and sulfate salts of Li, Al, Mg, Zn, K or Na; preferably, the concentration of the ion source solution may be 0.1-2 mol / L.

[0066] In some embodiments, in step (4), the curing method can be ultraviolet curing (e.g., 100W) or thermal curing.

[0067] The fabrication process involved in this invention is simple, low-cost, and easy to promote. The high-performance electrochromic device developed by this invention has a wider range of application prospects.

[0068] This patent proposes a wide-band modulated electrochromic device based on electrochromic materials such as WO3, achieving a fully solid-state structure through material innovation and structural design. Furthermore, micro-nano structure design further enhances the device's controllability within the "atmospheric window." According to Energyplus software simulations, this electrochromic smart window demonstrates better energy efficiency than Low-E glass in major regions worldwide.

[0069] The following examples further illustrate the present invention in detail. It should also be understood that the following examples are only for further explanation of the present invention and should not be construed as limiting the scope of protection of the present invention. Any non-essential improvements and adjustments made by those skilled in the art based on the above description of the present invention are within the scope of protection of the present invention. The specific process parameters, etc., in the following examples are merely examples within a suitable range; that is, those skilled in the art can make appropriate selections within the range based on the description herein, and are not intended to be limited to the specific values ​​in the examples below. Unless otherwise specified, the technical means used in the examples are conventional means well known to those skilled in the art.

[0070] Example 1

[0071] The method for fabricating a mid-infrared-modulated, enhanced-performance all-solid-state electrochromic device provided by this invention includes the following steps:

[0072] (1) First, a first transparent electrode with high solar transmittance (78%) and high mid-infrared reflectivity (75%) is prepared on a glass substrate. Second, a second transparent electrode with high solar transmittance and high mid-infrared transmittance (80% broadband transmittance) is prepared on a high-transmittance BaF2 substrate. Third, an inorganic electrochromic layer is deposited on the second transparent electrode. The electrode is sputtered using magnetron sputtering with tungsten as the target material and methane, argon, and oxygen as the sputtering gases. The total pressure is 2.0 Pa, the partial pressure of methane is 1%, the partial pressure of oxygen is 12%, the distance between the target and the substrate is 15 cm, the initial substrate temperature is room temperature, and the applied DC power to the target is 70 W or the power density is 1.55 W / cm². 2 A 400 nm electrochromic layer film is deposited; wherein the material of the micro-nano fabricated electrochromic layer is WO3; it is composed of nano-columnar crystals with attached nanoparticles, the diameter of the nano-columnar crystals is 25 nm, the distance between the nano-columnar crystals is 15 nm, the particle size of the nanoparticles is 10 nm, and the volume ratio of nanoparticles to nano-columnar crystals is 1:20; after the electrochromic layer is prepared by magnetron sputtering, it is subjected to annealing heat treatment, the annealing heat treatment process includes: heating from room temperature to 350 °C at a heating rate of 25 °C / s and holding at that temperature for 10 minutes, and then naturally cooling to room temperature;

[0073] (2) The electrochromic layer film is micro-nano-processed according to the designed size using electron beam etching process. The micro-nano-processing size is: processing cycle 1×1um, processing depth 400nm, and processing gap 200nm.

[0074] (3) Atomic layer deposition was used to deposit 15 nm of SiO2 on the surface of the micro-nano fabricated electrochromic layer;

[0075] (4) According to existing technology, an electrolyte solution prepared in the mass ratio of PMA (propylene glycol methyl ether acetate), UC-935 (Xianmeite), ferrocene, ultraviolet absorber, ETPTA (ethoxylated trimethylolpropane triacrylate), and ion source solution in a mass ratio of 1:1:1:0.1:2:1 is filled between the electron blocking layer and the first transparent electrode by vacuum drip irrigation; wherein, the ion source solution is LiClO4, the solvent is propylene carbonate, and the concentration range of the ion source solution is 1 mol / L; a complete device is formed by ultraviolet light curing; the thickness of the resin layer is controlled to 1 μm by the surface tension of the hard template and the resin solution; wherein, the light curing is to place the device under a 100W ultraviolet lamp for uniform irradiation; after the device is cured, the excess organic matter on the surface of the device is removed by an organic solvent to obtain the mid-infrared modulation performance enhanced all-solid-state electrochromic device.

[0076] Example 2

[0077] The fabrication method of the mid-infrared modulated performance enhanced all-solid-state electrochromic device provided in this embodiment is the same as that in Embodiment 1, with the main difference being:

[0078] In step (1), the thickness of the electrochromic layer film is 200 nm;

[0079] In step (2), the depth of micro-nano fabrication is 200 nm.

[0080] Example 3

[0081] The fabrication method of the mid-infrared modulated performance enhanced all-solid-state electrochromic device provided in this embodiment is the same as that in Embodiment 1, with the main difference being:

[0082] In step (1), the thickness of the electrochromic layer film is 600 nm;

[0083] In step (2), the depth of micro-nano fabrication is 600 nm.

[0084] Example 4

[0085] The fabrication method of the mid-infrared modulated performance enhanced all-solid-state electrochromic device provided in this embodiment is the same as that in Embodiment 1, with the main difference being:

[0086] In step (1), the first transparent electrode has a solar transmittance of 75% and a mid-infrared reflectance of 78%.

[0087] Example 5

[0088] The fabrication method of the mid-infrared modulated performance enhanced all-solid-state electrochromic device provided in this embodiment is the same as that in Embodiment 1, with the main difference being:

[0089] In step (1), the second transparent electrode has a transmittance of 75% for sunlight and mid-infrared broadband.

[0090] Example 6

[0091] The fabrication method of the mid-infrared modulated performance enhanced all-solid-state electrochromic device provided in this embodiment is the same as that in Embodiment 1, with the main difference being:

[0092] In step (2), the gap in the micro-nano fabrication is 100 nm.

[0093] Example 7

[0094] The fabrication method of the mid-infrared modulated performance enhanced all-solid-state electrochromic device provided in this embodiment is the same as that in Embodiment 1, with the main difference being:

[0095] In step (2), the gap in the micro-nano fabrication is 400 nm.

[0096] Example 8

[0097] The fabrication method of the mid-infrared modulated performance enhanced all-solid-state electrochromic device provided in this embodiment is the same as that in Embodiment 1, with the main difference being:

[0098] In step (2), the depth of micro-nano fabrication is 200 nm.

[0099] Example 9

[0100] The fabrication method of the mid-infrared modulated performance enhanced all-solid-state electrochromic device provided in this embodiment is the same as that in Embodiment 1, with the main difference being:

[0101] In step (2), the depth of the micro-nano fabrication is 50 nm.

[0102] Example 10

[0103] The fabrication method of the mid-infrared modulated performance enhanced all-solid-state electrochromic device provided in this embodiment is the same as that in Embodiment 1, with the main difference being:

[0104] In step (3), the surface deposition thickness of the SiO2 electrochromic layer is 5 nm.

[0105] Example 11

[0106] The fabrication method of the mid-infrared modulated performance enhanced all-solid-state electrochromic device provided in this embodiment is the same as that in Embodiment 1, with the main difference being:

[0107] In step (3), the SiO2 electrochromic layer is deposited with a thickness of 20 nm.

[0108] Example 12

[0109] The fabrication method of the mid-infrared modulated performance enhanced all-solid-state electrochromic device provided in this embodiment is the same as that in Embodiment 1, with the main difference being:

[0110] In step (1), the high-transparency substrate is TPX.

[0111] Example 13

[0112] The fabrication method of the mid-infrared modulated performance enhanced all-solid-state electrochromic device provided in this embodiment is the same as that in Embodiment 1, with the main difference being:

[0113] In step (1), the high-transparency substrate is PE.

[0114] Example 14

[0115] The fabrication method of the mid-infrared modulated performance enhanced all-solid-state electrochromic device provided in this embodiment is the same as that in Embodiment 1, with the main difference being:

[0116] In step (4), the thickness of the resin layer is controlled to be 0.6 μm by the surface tension of the hard template and the resin solution.

[0117] Example 15

[0118] The fabrication method of the mid-infrared modulated performance enhanced all-solid-state electrochromic device provided in this embodiment is the same as that in Embodiment 1, with the main difference being:

[0119] In step (4), the thickness of the resin layer is controlled to be 5 μm by the surface tension of the hard template and the resin solution.

[0120] Example 16

[0121] The fabrication method of the mid-infrared modulated performance enhanced all-solid-state electrochromic device provided in this embodiment is the same as that in Embodiment 1, with the main difference being:

[0122] In step (1), the partial pressure of methane is 0.5%.

[0123] Testing revealed that the electrochromic layer of the micro-nano fabricated process provided in this embodiment is made of WO3; it consists of nano-columnar crystals with attached nanoparticles, the diameter of the nano-columnar crystals is 50 nm, the distance between the nano-columnar crystals is 30 nm, the particle size of the nanoparticles is 20 nm, and the volume ratio of nanoparticles to nano-columnar crystals is 1:10.

[0124] Example 17

[0125] The fabrication method of the mid-infrared modulated performance enhanced all-solid-state electrochromic device provided in this embodiment is the same as that in Embodiment 1, with the main difference being:

[0126] In step (1), the partial pressure of methane is 2%.

[0127] Testing revealed that the electrochromic layer of the micro-nano fabricated process provided in this embodiment is made of WO3; it consists of nano-columnar crystals with attached nanoparticles, the diameter of the nano-columnar crystals is 20 nm, the distance between the nano-columnar crystals is 10 nm, the particle size of the nanoparticles is 5 nm, and the volume ratio of nanoparticles to nano-columnar crystals is 1:40.

[0128] Comparative Example 1

[0129] The method for preparing the electrochromic device provided in this comparative example is the same as in Example 1, with the main difference being:

[0130] In step (2), the gap in the micro-nano fabrication is 450 nm.

[0131] Comparative Example 2

[0132] The method for preparing the electrochromic device provided in this comparative example is the same as in Example 1, with the main difference being:

[0133] In step (1), the electrochromic layer film thickness is 100 nm;

[0134] In step (2), the processing depth is 100 nm.

[0135] Comparative Example 3

[0136] The method for preparing the electrochromic device provided in this comparative example is the same as in Example 1, with the main difference being:

[0137] In step (4), the thickness of the resin layer is controlled to be 10 μm by the surface tension of the hard template and the resin solution.

[0138] Comparative Example 4

[0139] The method for preparing the electrochromic device provided in this comparative example is the same as in Example 1, with the main difference being:

[0140] In step (2), the processing depth is 10 nm.

[0141] Comparative Example 5

[0142] The method for preparing the electrochromic device provided in this comparative example is the same as in Example 1, with the main difference being:

[0143] In step (2), the processing gap is 50 nm.

[0144] Comparative Example 6

[0145] The method for preparing the electrochromic device provided in this comparative example is the same as in Example 1, with the main difference being:

[0146] In step (1), the partial pressure of methane is 0.2%.

[0147] Testing revealed that the electrochromic layer fabricated in this comparative example is made of WO3, consisting only of nano-columnar crystals with a diameter of 50 nm.

[0148] Comparative Example 7

[0149] The method for preparing the electrochromic device provided in this comparative example is the same as in Example 1, with the main difference being:

[0150] In step (1), the partial pressure of methane is 5%.

[0151] Testing revealed that the material of the micro-nano-fabricated electrochromic layer prepared in this comparative example is WO3; it consists of nano-columnar crystals with attached nanoparticles, the diameter of the nano-columnar crystals is 30 nm, the distance between the nano-columnar crystals is 5 nm, the particle size of the nanoparticles is 5 nm, and the ratio of nanoparticles to nano-columnar crystals is 1:1; however, the nano-columnar crystals collapsed, leading to an increase in grain boundaries.

[0152] Table 1 below compares the relevant parameters of the electrochromic devices prepared in Examples 1-17 and Comparative Examples 1-7:

[0153]

[0154]

[0155]

[0156] Although the present invention has been described in detail through the preferred embodiments above, it should be understood that the above description should not be considered as a limitation of the present invention. Various modifications and substitutions to the present invention will be apparent to those skilled in the art after reading the above description. Therefore, the scope of protection of the present invention should be defined by the appended claims.

Claims

1. A mid-infrared modulated performance enhanced all-solid-state electrochromic device, characterized in that, The structure of the mid-infrared modulated performance enhanced all-solid-state electrochromic device includes: a transparent substrate, a first transparent electrode, an electrolyte layer, an electron blocking layer, a micro-nano fabricated electrochromic layer, a second transparent electrode, and a highly transparent substrate, which are stacked sequentially. The material of the micro / nano-fabricated electrochromic layer includes WO3. 3-x1 MoO 3-x2 TiO 2-x3 It contains at least one of V2O5, where x1 ranges from 0 to 0.8, x2 ranges from 0 to 0.8, and x3 ranges from 0 to 0.5; the thickness is 200 to 600 nm. The micro / nano-fabricated electrochromic layer comprises nano-columnar crystals with attached nanoparticles; wherein the diameter of the nano-columnar crystals is 5-50 nm, the distance between the nano-columnar crystals is 5-30 nm, and the particle size of the nanoparticles is 2-20 nm; in the micro / nano-fabricated electrochromic layer, the volume ratio of nanoparticles to nano-columnar crystals is 1:5-50. The processing cycle of the electrochromic layer in the micro-nano fabrication is 0.5-50um×0.5-50um, the processing depth is 50nm-thickness of the electrochromic layer, and the processing gap is 100-400nm.

2. The all-solid-state electrochromic device with enhanced mid-infrared modulation performance according to claim 1, characterized in that, The materials of the first and second transparent electrodes include at least one of transparent conductive oxide, MXENE, and metal nanowires, with a sheet resistance of 10–400 Ω / cm. 2 ; The first transparent electrode has a solar transmittance of ≥75% in the 0.38-2.5μm band and a mid-infrared reflectance of ≥75% in the 8-14 μm band. The second transparent electrode has a solar transmittance of ≥75% in the 0.38-2.5μm band and a mid-infrared transmittance of ≥75% in the 8-14 μm band.

3. The all-solid-state electrochromic device with enhanced mid-infrared modulation performance according to claim 1, characterized in that, The electrolyte layer is a cationic gel conductive layer based on organic resin, and the cationic cations include Li. + Al 3+ Mg 2+ Zn 2+ K + and Na + At least one of the following; the thickness of the electrolyte layer is 0.6-5 μm.

4. The all-solid-state electrochromic device with enhanced mid-infrared modulation performance according to claim 1, characterized in that, The electron blocking layer is made of a wide bandgap material and has a thickness of 5-20 nm.

5. The all-solid-state electrochromic device with enhanced mid-infrared modulation performance according to claim 4, characterized in that, The electron blocking layer is made of SiO2, Al2O3, or SnO2.

6. The all-solid-state electrochromic device with enhanced mid-infrared modulation performance according to claim 1, characterized in that, The material of the high-transparency substrate includes one of barium fluoride, calcium fluoride, magnesium fluoride, zinc sulfide, zinc selenide, sodium chloride, silicon, germanium, sapphire, polyethylene, and poly(4-methyl-1-pentene); The high-transmittance substrate has a solar transmittance of ≥85% in the 0.38-2.5μm band and a mid-infrared transmittance of ≥85% in the 2.5-25 μm band.

7. A method for preparing the mid-infrared modulated performance enhanced all-solid-state electrochromic device as described in claim 1, characterized in that, The preparation method includes the following steps: (1) A first transparent electrode was prepared on the surface of a transparent substrate by magnetron sputtering, and a second transparent electrode and an electrochromic layer were prepared sequentially on a high-transparency substrate. (2) The electrochromic layer film is micro- or nano-fabricated according to the designed size using electron beam etching process to obtain a micro- or nano-fabricated electrochromic layer; (3) An electron blocking layer is prepared on the surface of the micro / nano-fabricated electrochromic layer using atomic layer deposition (ALD). (4) The electrolyte solution is filled between the electron blocking layer and the first transparent electrode by vacuum drip irrigation and then cured to obtain the mid-infrared modulation performance enhanced all-solid-state electrochromic device.

8. The preparation method according to claim 7, characterized in that, In step (1), the process parameters for preparing the electrochromic layer by magnetron sputtering include: using tungsten, molybdenum, titanium, or vanadium as the target material; using methane, argon, and oxygen as the sputtering gas; a total pressure of 0.5-2.0 Pa; a methane partial pressure of 0.5-2%; an oxygen partial pressure of 0-50%; a target-to-substrate distance of 10-20 cm; an initial substrate temperature of room temperature; and a DC power supply applied to the target of 30-150 W or a power density of 0.6-3.0 W / cm². 2 .

9. The preparation method according to claim 7, characterized in that, Step (1) also includes an annealing heat treatment after the electrochromic layer is prepared by magnetron sputtering; wherein the annealing heat treatment process includes: heating from room temperature to 200-375℃ at a heating rate of 5-50℃ / s and holding at that temperature for 2-60 minutes, and then naturally cooling to room temperature.

10. The preparation method according to claim 7, characterized in that, In step (2), the process parameters for micro / nano fabrication using electron beam etching include: accelerating voltage 10-100 kV, beam current 1-50 pA, scanning step size ≤ 1 / 4 of linewidth, and photoresist sensitivity 20-500 μC / cm. 2 .

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