A tungstate quantum dot-based hydrogel color-changing device with both electrochromic and photochromic properties and its fabrication method

Abstract

This invention discloses a tungstate quantum dot-based hydrogel color-changing device with both electrochromic and photochromic properties, and its fabrication method. The device includes a working electrode / photochromic / electrolyte layer, an electrochromic layer, and a counter electrode conductive layer. The working electrode / photochromic / electrolyte layer is an acrylamide / 2-acrylamido-2-methylpropanesulfonic acid / lithium chloride hydrogel with good ionic conductivity, transparency, and photochromic properties. The electrochromic layer is prepared by spin-coating a tungstate quantum dot / poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid composite solution. The counter electrode conductive layer is an acrylamide / 2-acrylamido-2-methylpropanesulfonic acid hydrogel. This invention solves the technical problems of existing color-changing devices that cannot simultaneously possess electrochromic and photochromic properties, have fast response speeds, large transmittance adjustment capabilities, and flexibility.

Description

Technical Field

[0001] This invention belongs to the field of new materials technology, specifically relating to a tungstate quantum dot-based hydrogel with both electrochromic and photochromic properties, a color-changing device, and a preparation method. Background Technology

[0002] Electrochromism and photochromism refer to the phenomenon that the optical properties of materials change reversibly and stably under the stimulation of an external electric field or external light source. Electrochromic and photochromic materials can be mainly divided into organic and inorganic color-changing materials. Organic color-changing materials include spiropyrans, polythiophenes, viologens and their derivatives. These organic color-changing materials can achieve the conversion between multiple colors, but their cycle stability is poor and their response sensitivity is low, which cannot meet the increasing demands of actual production and life. Inorganic color-changing materials have excellent thermal stability, chemical stability and reversible cycle stability and are widely used. Among them, tungsten oxides and tungstates, as inexpensive, non-toxic and environmentally friendly inorganic materials, exhibit excellent electrochromic and photochromic properties, excellent optical contrast before and after color change and high cycle stability, and are widely used in various fields. Currently, research on the preparation of color-changing materials and devices using tungsten oxide and tungstate materials as electrochromic or photochromic building blocks is increasing, and they show potential application prospects in wearable electronics, the Internet of Things, and smart windows. However, with the increasing demand for energy and management, the preparation and development of highly efficient integrated multifunctional color-changing devices using electrochromic and photochromic technologies is imperative. Although color-changing devices prepared using common tungsten oxide or tungstate materials have high reversibility and chemical stability, their long response time and poor optical contrast limit their applications. Summary of the Invention

[0003] This invention discloses a tungstate quantum dot-based hydrogel color-changing device that combines electrochromic and photochromic properties, as well as its preparation method. It solves the technical problems of existing color-changing devices that cannot simultaneously possess electrochromic and photochromic properties, fast response speed, large transmittance adjustment, and flexibility.

[0004] The present invention adopts the following technical solution:

[0005] A tungstate quantum dot-based hydrogel color-changing device that combines electrochromic and photochromic properties includes a working electrode composite photochromic electrolyte layer, an electrochromic layer, and a counter electrode conductive layer, wherein the electrochromic layer is located between the working electrode composite photochromic electrolyte layer and the counter electrode conductive layer.

[0006] In this invention, the working electrode composite photochromic electrolyte layer is acrylamide / 2-acrylamido-2-methylpropanesulfonic acid / lithium chloride hydrogel; the electrochromic layer is a tungstate quantum dot / poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid composite layer; and the counter electrode conductive layer is acrylamide / 2-acrylamido-2-methylpropanesulfonic acid hydrogel.

[0007] This invention relates to a tungstate quantum dot-based hydrogel color-changing device that combines electrochromic and photochromic properties. The device comprises a working electrode / photochromic / electrolyte layer, an electrochromic layer, and a counter electrode conductive layer. The working electrode / photochromic / electrolyte layer is an acrylamide / 2-acrylamido-2-methylpropanesulfonic acid / lithium chloride hydrogel with good ionic conductivity, transparency, and photochromic properties. The electrochromic layer is prepared by spin-coating a tungstate quantum dot / poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid composite solution. The counter electrode conductive layer is an acrylamide / 2-acrylamido-2-methylpropanesulfonic acid hydrogel. In this invention, tungstate quantum dots exhibit excellent surface and small-size effects, enhancing the electrochromic and photochromic reactivity of the color-changing device. The hydrogel-based color-changing device possesses excellent flexibility, rapid response capability, and superior electrochromic and photochromic properties.

[0008] The present invention provides a method for preparing a tungstate quantum dot-based hydrogel color-changing device that combines electrochromic and photochromic properties, comprising the following steps:

[0009] (1) Tungstate quantum dots are prepared by a one-step hydrothermal method, and then the tungstate quantum dot solution is mixed with poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid, surfactant and water to prepare a tungstate quantum dot / poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid electrochromic solution; preferably, the hydrothermal reaction temperature is 160-180℃ and the hydrothermal reaction time is 24-48h;

[0010] (2) Tungstate quantum dots, acrylamide, 2-acrylamido-2-methylpropanesulfonic acid, and lithium chloride are mixed to prepare an acrylamide / 2-acrylamido-2-methylpropanesulfonic acid / lithium chloride hydrogel, which serves as the working electrode composite photochromic electrolyte layer, i.e., working electrode / photochromic / electrolyte layer; preferably, acrylamide, 2-acrylamido-2-methylpropanesulfonic acid, lithium chloride, tungstate quantum dots, ammonium persulfate, N,N-methylenebisacrylamide, and water are mixed and stirred, and then transferred to a mold and dried at a constant temperature to obtain the working electrode composite photochromic electrolyte layer; the mold and transfer method are conventional techniques;

[0011] (3) Acrylamide and 2-acrylamido-2-methylpropanesulfonic acid are mixed to prepare an acrylamide / 2-acrylamido-2-methylpropanesulfonic acid hydrogel, which is the conductive layer of the counter electrode; preferably, acrylamide, 2-acrylamido-2-methylpropanesulfonic acid, ammonium persulfate and N,N-methylenebisacrylamide are added to an aqueous solution in sequence, the mixture is stirred at room temperature and allowed to stand to remove bubbles, and then dried at a constant temperature to obtain the conductive layer of the counter electrode;

[0012] (4) Spin-coating an electrochromic solution onto the substrate surface to obtain an electrochromic layer. Then, composite a working electrode / photochromic / electrolyte layer and a counter electrode conductive layer on both sides of the electrochromic layer to prepare a hydrogel color-changing device. Preferably, the spin-coating speed is 1000-3000 r / s. After the electrochromic solution is spin-coated onto the ITO glass surface, it is subjected to high-temperature annealing treatment.

[0013] In this invention, the tungstate quantum dot / poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid electrochromic solution contains 1.3-1.5% poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid, 14-15% tungstate quantum dot solution, and 0.25-0.3% surfactant, all by mass.

[0014] Beneficial effects of this invention:

[0015] (1) The tungstate quantum dots prepared by the hydrothermal method in this invention serve as both electrochromic and photochromic units, and the WO3 content is adjusted accordingly. 2- With H + By adjusting the molar ratio, tungstate quantum dots with different structures can be prepared, and the color-changing properties of tungstate quantum dots can be controlled. Moreover, the preparation process is simple, low-cost, safe and reliable.

[0016] (2) The all-solid flexible color-changing hydrogel device prepared by the present invention is different from the traditional color-changing device. It uses hydrogel as electrolyte and electrode material to replace the traditional liquid electrolyte and transparent conductive substrate (ITO, FTO, etc.), which solves the defects of traditional color-changing devices such as difficult encapsulation, poor flexibility and complex assembly, and broadens its application prospects.

[0017] (3) The color-changing device prepared by the present invention exhibits excellent electrochromic properties and good photochromic behavior as the intensity of sunlight changes, namely, wide optical control range, short color development and fading response time, and good cycle stability. Attached Figure Description

[0018] Figure 1 This is a schematic diagram illustrating the fabrication method of the tungstate quantum dot-based hydrogel color-changing device that combines electrochromic and photochromic properties according to the present invention.

[0019] Figure 2This is a transmission electron microscope image of the tungstate quantum dots prepared in Example 1.

[0020] Figure 3 The image shows a scanning electron microscope (SEM) cross-sectional view of the ITO glass with the spin-coated electrochromic layer prepared in Example 1, where a is a low-magnification image and b is a high-magnification image.

[0021] Figure 4 Transmittance curves for acrylamide / 2-acrylamido-2-methylpropanesulfonic acid / lithium chloride hydrogel (AM / AMPS / LiCl), acrylamide / 2-acrylamido-2-methylpropanesulfonic acid hydrogel (AM / AMPSl), acrylamide / lithium chloride hydrogel (AM / LiCl), and acrylic acid / acrylamido-2-acrylamido-2-methylpropanesulfonic acid / lithium chloride hydrogel (AA / APMS / AM / LiCl).

[0022] Figure 5 The graphs show the transmittance curves of the hydrogel color-changing devices prepared in Examples 1 and 2 before and after color change.

[0023] Figure 6 Transmittance curves of electrochromic layers (including glass) prepared at different spin coating speeds.

[0024] Figure 7 The transmittance curves are for the electrochromic layers (containing glass) prepared in Examples 1, 2 and 3.

[0025] Figure 8 The image shows the cyclic voltammetry curves of the electrochromic layer of the hydrogel color-changing device prepared in Example 1 at different scan rates within an electrochemical window of -0.6V to 0.6V.

[0026] Figure 9 The graph shows the chronocurrent curve of the hydrogel color-changing device prepared in Example 1 at -0.6V to 0.6V.

[0027] Figure 10 The graph shows the chronocurrent curve of the hydrogel color-changing device prepared in Example 2 at -0.6V to 0.6V.

[0028] Figure 11 The graph shows the chronocurrent curve of the hydrogel color-changing device prepared in Example 3 at -0.6V to 0.6V. Detailed Implementation

[0029] Research on the fabrication of color-changing materials and devices using tungsten oxide and tungstate materials as electrochromic or photochromic building blocks is increasing. However, the fabrication of highly efficient, integrated, and multifunctional color-changing devices that simultaneously possess electrochromic and photochromic properties remains a significant challenge. Furthermore, currently fabricated tungsten oxide and tungstate color-changing materials and devices suffer from drawbacks such as slow color-switching response times, poor optical contrast, and complex fabrication processes. The purpose of this invention is to address the technical challenges of existing color-changing devices that cannot simultaneously possess electrochromic and photochromic properties, rapid response speed, large transmittance adjustment, and flexibility. Therefore, this invention provides a tungstate quantum dot-based hydrogel color-changing device that combines electrochromic and photochromic properties, along with its fabrication method.

[0030] Nano-modification of tungsten oxides or tungstates to prepare tungstate quantum dots significantly enhances their surface chemical activity, increases the contact area between the electrochromic layer and the electrolyte, facilitates ion insertion, and thus shortens the electrochromic time and improves their responsiveness. Simultaneously, the quantum effect of tungstate quantum dots enables faster photoelectron transfer under external light stimulation, enhancing their photochromic performance. An electrochromic solution is spin-coated onto a substrate surface to obtain an electrochromic layer, followed by the attachment of a working electrode / photochromic / electrolyte layer, thereby transferring the electrochromic layer. The electrochromic layer is then attached to the counter electrode conductive layer from the other side to fabricate a hydrogel color-changing device, such as... Figure 1 As shown, this invention prepares high-performance tungstate quantum dots as the basic unit of electrochromic and photochromic processes through a one-step hydrothermal method. By combining them with hydrogels, a tungstate quantum dot-based hydrogel color-changing device with both electrochromic and photochromic properties is prepared, which has broad application prospects in the fields of flexible sensor devices and wearable electronic devices.

[0031] The raw materials and molds used in this invention are existing products, and the specific preparation operations and performance testing are conventional techniques. Electrochromic performance: The electrochromic performance of the device was tested using a chronoamperometry method with a Shanghai Chenhua CHI650E electrochemical workstation. Transmittance testing method: Measured using a UV-Vis spectrophotometer within the wavelength range of 250-800 nm. Coloring and fading time measurement: The time required for coloring and fading of the device was measured using a UV-Vis spectrophotometer at a wavelength of 550 nm. Optical contrast: The difference in transmittance between the colored and faded states of the device was measured using a UV-Vis spectrophotometer at a wavelength of 550 nm. Driving voltage: The external voltage used to induce coloring and fading of the device. Cyclic stability: Measured using an electrochemical chronoamperometry method.

[0032] Example 1

[0033] A method for fabricating a tungstate quantum dot-based hydrogel color-changing device that combines electrochromic and photochromic properties comprises the following steps:

[0034] (1) Dissolve 0.41g of sodium tungstate dihydrate in 25g of deionized water solution. After complete dissolution, add 0.2534g of 0.1M hydrochloric acid solution and then add 25mL of ethylene glycol. Stir and mix to form a transparent and colorless solution. Transfer the solution to a 100mL polytetrafluoroethylene reactor and heat it in an oven at 180℃ for 48h. Cool it to room temperature to prepare an aqueous solution of tungstate quantum dots.

[0035] (2) Weigh 0.13g of poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid solid, 1.4g of tungstate quantum dot solution and 0.025g of Triton-X100 solution and add them to deionized water to prepare a 10g mixed solution. Stir and mix for 1h to prepare a mixed electrochromic solution.

[0036] (3) The ITO glass was placed in a surface plasma cleaner and cleaned under the following conditions: working power of 60W, working pressure of 60Pa, and working time of 5min. Then, the mixed electrochromic solution prepared in step (2) was spin-coated onto the surface of the ITO glass at 3000r / s for 30s, and then annealed at 120℃ for 10min. The above operation was repeated three times to prepare an electrochromic layer.

[0037] (4) The specific preparation method of acrylamide / 2-acrylamido-2-methylpropanesulfonic acid / lithium chloride photochromic hydrogel electrolyte and electrode is as follows: 6g of acrylamide and 1.228g of 2-acrylamido-2-methylpropanesulfonic acid are dissolved in 10g of deionized water and stirred for 10min. Then, 2.95g of lithium chloride, 0.036g of ammonium persulfate and 0.025g of N,N-methylenebisacrylamide are added and stirred for 20min. The mixture is then transferred to a mold and dried at a constant temperature in a 60℃ oven for 1h. After cooling to room temperature, the working electrode composite photochromic electrolyte layer is prepared.

[0038] (5) Attach the acrylamide / 2-acrylamido-2-methylpropanesulfonic acid / lithium chloride photochromic hydrogel to the ITO glass surface with the electrochromic layer in step (3), so that the hydrogel surface and the electrochromic layer are in complete contact. Place it at room temperature for 10 minutes, and transfer the electrochromic layer from the ITO surface to the hydrogel surface through the adhesion between the electrochromic layer and the hydrogel surface.

[0039] (6) The specific preparation method of the acrylamide / 2-acrylamido-2-methylpropanesulfonic acid hydrogel electrode is as follows: 6g of acrylamide and 1.228g of 2-acrylamido-2-methylpropanesulfonic acid are dissolved in 10g of deionized water and stirred for 10min. Then, 0.036g of ammonium persulfate and 0.025g of N,N-methylenebisacrylamide are added and stirred for 20min. The mixture is then transferred to a mold and dried at a constant temperature in a 60℃ oven for 1h. After cooling to room temperature, the conductive layer of the electrode is prepared.

[0040] (7) The photochromic hydrogel electrolyte layer of the working electrode and the conductive layer of the electrode are combined and attached to form a tightly contacted vertical layered structure through the physicochemical interaction between the hydrogels, and assembled into a flexible all-solid-state hydrogel color-changing device.

[0041] from Figure 2 Transmission electron microscopy images show that the tungstate quantum dot solution prepared in Example 1 is uniformly dispersed in aqueous solution.

[0042] from Figure 3 It can be seen that the electrochromic solution is spin-coated onto the ITO glass surface, and its thickness is approximately 2.5 μm. The thickness of both the conductive layer hydrogel and the photochromic / electrolyte layer working electrode hydrogel is 3 mm.

[0043] from Figure 4 It can be seen that the transmittance of the prepared acrylamide / 2-acrylamido-2-methylpropanesulfonic acid / lithium chloride hydrogel is 91.54% (550nm), and the transmittance of the acrylamide / 2-acrylamido-2-methylpropanesulfonic acid hydrogel is 88.30% (550nm).

[0044] from Figure 5 It can be seen that the optical contrast of the prepared hydrogel color-changing device before and after the color change is 70.61%.

[0045] from Figure 6 It can be seen that the transmittance of the prepared electrochromic layer is 76%.

[0046] The electrochemical performance of the device was measured using a two-electrode method. Cyclic voltammetry was performed at scan rates of 5, 10, 15, and 20 mV / s, with a potential range of -0.6 V to 0.6 V. From... Figure 8 It can be seen that the device exhibits obvious redox peaks, and the area covered by the cyclic voltammetry curve increases with the increase of the scan rate, indicating that the increase of the scan rate is more conducive to the insertion of ions, thereby storing more charge and thus increasing its surface capacitance.

[0047] The device's cyclic stability was tested using a two-electrode method. The chronoamperometry method had a potential range of -1V to 1V, a pulse time of 1s, and a static time of 2s. Figure 9 It can be seen that the fabricated device maintains stable coloring current and fading current after about 1000 reversible cycles, indicating that it has excellent reversible cycling performance.

[0048] As shown in Table 1, the fabricated device exhibits excellent electrochromic properties, including coloring and fading response time, optical contrast after coloring and fading, and driving voltage. This demonstrates that it possesses superior electrochromic performance, as reported in most literatures.

[0049]

[0050] Adjusting the spin-coating speed of the mixed electrochromic solution in step (3) above to 1000 r / s or 2000 r / s, while keeping other parameters unchanged, yields electrochromic layers with transmittances of 67% and 72%, respectively. (See [reference needed]). Figure 6 .

[0051] Example 2

[0052] A method for fabricating a tungstate quantum dot-based hydrogel color-changing device that combines electrochromic and photochromic properties includes the following steps:

[0053] (1) Compared with Example 1, Example 2 increased the amount of sodium tungstate dihydrate to 0.82g and the amount of 0.1M hydrochloric acid solution to 1.0g. The amount of other reagents and the preparation process were the same as in Example 1.

[0054] (2) Compared with Example 1, the amount of poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid solid used in Example 2 was 0.065 g. The amounts of other reagents and the preparation process were the same as in Example 1.

[0055] (3) The cleaning steps and annealing process of ITO glass are the same as in Example 1. The spin coating process of the prepared mixed electrochromic solution on the surface of ITO glass is as follows: spin coating for 30 seconds at 3000 r / s, and repeating the spin coating three times.

[0056] (4) The specific preparation method of acrylamide / lithium chloride photochromic hydrogel electrolyte and electrode is as follows: 3.515g of acrylamide is dissolved in 10g of deionized water and stirred for 10min. 0.018g of ammonium persulfate and 0.013g of N,N-methylenebisacrylamide are added and stirred for 30min. The mixture is then transferred to a mold and dried at a constant temperature of 60℃ for 1h. After cooling to room temperature, the hydrogel is soaked in 30% lithium chloride aqueous solution for 12h. The surface moisture is wiped off and the mixture is naturally dried for 4h to obtain the final product.

[0057] (5) The method for transferring the electrochromic layer from the ITO glass surface to the acrylamide / lithium chloride hydrogel surface is the same as in Example 1. (6) The specific preparation method of the acrylamide / 2-acrylamido-2-methylpropanesulfonic acid hydrogel electrode is the same as in Example 1.

[0058] (7) The steps for the flexible all-solid-state hydrogel color-changing device are the same as those in Example 1.

[0059] from Figure 4 It can be seen that the prepared acrylamide / lithium chloride hydrogel has a transmittance of 88.28% (550nm), exhibiting excellent transparency.

[0060] from Figure 5 It can be seen that the optical contrast of the prepared hydrogel color-changing device before and after the color change is 60.61%.

[0061] from Figure 7 It can be seen that the transmittance of the prepared electrochromic layer is 66%.

[0062] The device's cyclic stability was tested using a two-electrode method. The chronoamperometry method had a potential range of -1V to 1V, a pulse time of 1s, and a static time of 2s. Figure 10 It can be seen that the fabricated device exhibits a certain degree of attenuation in both coloring and fading currents after approximately 500 reversible cycles, indicating that it has good reversible cycling performance.

[0063] Example 3

[0064] A method for fabricating a tungstate quantum dot-based hydrogel color-changing device that combines electrochromic and photochromic properties includes the following steps:

[0065] (1) Compared with the preparation method of tungstate quantum dot solution in Example 1, 0.1545g of ammonium molybdate tetrahydrate solution was added. The amount of other solvents and preparation steps were the same as in Example 1. A small amount of ammonium molybdate was added as a dopant.

[0066] (2) The preparation method of the mixed electrochromic solution is the same as that in Example 1.

[0067] (3) The cleaning steps and annealing process of ITO glass are the same as in Example 1. The spin coating process of the prepared mixed electrochromic solution on the surface of ITO glass is as follows: spin coating for 30 seconds at 3000 r / s, and repeating the spin coating three times.

[0068] (4) The preparation method of acrylic acid / acrylamide / 2-acrylamido-2-methylpropanesulfonic acid / lithium chloride photochromic hydrogel electrolyte and electrode is the same as that in Example 1. An acrylic acid solution is added to this method, and the total mass of acrylic acid and acrylamide is maintained at 6g, that is, 2.84g of acrylic acid and 3.52g of acrylamide are added. The dosage of other reagents and the preparation process are the same as in Example 1.

[0069] (5) The method for transferring the electrochromic layer from the ITO glass surface to the surface of the acrylic / acrylamide / 2-acrylamido-2-methylpropanesulfonic acid / lithium chloride hydrogel is the same as in Example 1.

[0070] (6) The specific preparation method of the acrylamide / 2-acrylamido-2-methylpropanesulfonic acid hydrogel electrode is the same as that in Example 1.

[0071] (7) The steps for the flexible all-solid-state hydrogel color-changing device are the same as those in Example 1.

[0072] from Figure 4 It can be seen that the prepared acrylic acid / acrylamide / 2-acrylamido-2-methylpropanesulfonic acid / lithium chloride hydrogel has a transmittance of 91.38% (550nm), exhibiting excellent transparency.

[0073] from Figure 7 It can be seen that the transmittance of the prepared electrochromic layer is 49%.

[0074] The device's cyclic stability was tested using a two-electrode method. The chronoamperometry method had a potential range of -1V to 1V, a pulse time of 1s, and a static time of 2s. Figure 11 It can be seen that the fabricated device exhibits a significant decrease in both coloring and fading currents after approximately 160 reversible cycles, indicating poor reversibility.

[0075] The references corresponding to numbers 1-9 in Table 1 are as follows:

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[0077] [2] LV X, XU H, YANG Y, et al. Flexible laterally-configuredelectrochromic supercapacitor with feasible patterned display [J]. Chem EngJ, 2023, 458.

[0078] [3] ALMARRI A H. Enhanced electrochromic properties of anatase TiO2for flexible electrochromic device [J]. Ionics, 2022, 28(9): 4435-4444.

[0079] [4] MA C, LIU H, TENG C, et al. Wetting-Induced Fabrication ofGraphene Hybrid with Conducting Polymers for High-Performance FlexibleTransparent Electrodes [J]. ACS Appl Mater Interfaces, 2020, 12(49): 55372-88381.

[0080] [5] KAI H, SUDA W, OGAWA Y, et al. Intrinsically StretchableElectrochromic Display by a Composite Film of Poly(3,4-ethylenedioxythiophene) and Polyurethane [J]. ACS Appl Mater Interfaces,2017, 9(23): 19513-19518.

[0081] [6] KIM D S, LEE Y H, KIM J W, et al. A stretchable array of high-performance electrochromic devices for displaying skin-attached multi-sensorsignals [J]. Chem Eng J, 2022, 429.

[0082] [7] FAN Q, FAN H, LI K, et al. Stretchable, Electrochemically-StableElectrochromic Devices Based on Semi-Embedded Ag@Au Nanowire Network [J].Small, 2023: e2208234.

[0083] [8] YANG G, DING J, YANG B, et al. Highly stretchable electrochromichydrogels for use in wearable electronic devices [J]. Journal of MaterialsChemistry C, 2019, 7(31): 9481-9486.

[0084] [9] KIM Y, PARK C, IM S, et al. Design of intrinsically stretchableand highly conductive polymers for fully stretchable electrochromic devices[J]. Sci Rep, 2020, 10(1): 16488。

Claims

1. A tungstate quantum dot-based hydrogel color-changing device that combines electrochromic and photochromic properties, comprising a working electrode composite photochromic electrolyte layer, an electrochromic layer, and a counter electrode conductive layer, wherein the electrochromic layer is located between the working electrode composite photochromic electrolyte layer and the counter electrode conductive layer; the working electrode composite photochromic electrolyte layer is an acrylamide / 2-acrylamido-2-methylpropanesulfonic acid / lithium chloride hydrogel; the electrochromic layer is a tungstate quantum dot / poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid composite layer; and the counter electrode conductive layer is an acrylamide / 2-acrylamido-2-methylpropanesulfonic acid hydrogel.

2. The method for preparing the tungstate quantum dot-based hydrogel color-changing device with both electrochromic and photochromic properties as described in claim 1, characterized in that, Includes the following steps: (1) Tungstate quantum dots were prepared by a one-step hydrothermal method, and then the tungstate quantum dot solution was mixed with poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid, surfactant and water to prepare a tungstate quantum dot / poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid electrochromic solution. (2) Acrylamide, 2-acrylamido-2-methylpropanesulfonic acid and lithium chloride are mixed to prepare an acrylamide / 2-acrylamido-2-methylpropanesulfonic acid / lithium chloride hydrogel, which serves as the composite photochromic electrolyte layer for the working electrode; (3) Acrylamide and 2-acrylamido-2-methylpropanesulfonic acid were mixed to prepare an acrylamide / 2-acrylamido-2-methylpropanesulfonic acid hydrogel, which served as the conductive layer for the counter electrode; (4) Spin-coat an electrochromic solution onto the substrate surface to obtain an electrochromic layer; composite a working electrode / photochromic / electrolyte layer and a counter electrode conductive layer on both sides of the electrochromic layer to prepare a hydrogel color-changing device.

3. The method for preparing the tungstate quantum dot-based hydrogel color-changing device with both electrochromic and photochromic properties according to claim 2, characterized in that, The hydrothermal reaction temperature is 160-180℃, and the hydrothermal reaction time is 24-48h; in the tungstate quantum dot / poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid electrochromic solution, the content of poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid is 1.3-1.5%, the content of tungstate quantum dot solution is 14-15%, and the content of surfactant is 0.25-0.3%.

4. The method for preparing the tungstate quantum dot-based hydrogel color-changing device with both electrochromic and photochromic properties according to claim 2, characterized in that, Acrylamide, 2-acrylamido-2-methylpropanesulfonic acid, lithium chloride, tungstate quantum dots, ammonium persulfate, N,N-methylenebisacrylamide and water were mixed and stirred, and then dried at a constant temperature to obtain the working electrode composite photochromic electrolyte layer.

5. The method for preparing the tungstate quantum dot-based hydrogel color-changing device with both electrochromic and photochromic properties according to claim 2, characterized in that, Acrylamide, 2-acrylamido-2-methylpropanesulfonic acid, ammonium persulfate, and N,N-methylenebisacrylamide were added sequentially to an aqueous solution. The mixture was stirred at room temperature and allowed to stand to remove air bubbles. The mixture was then dried at a constant temperature to obtain the conductive layer for the counter electrode.

6. The method for preparing the tungstate quantum dot-based hydrogel color-changing device with both electrochromic and photochromic properties according to claim 2, characterized in that, The spin coating speed is 1000-3000 r / s; after the electrochromic solution is spin-coated onto the ITO glass surface, it is subjected to high-temperature annealing treatment.

7. The application of the tungstate quantum dot-based hydrogel color-changing device with both electrochromic and photochromic properties as described in claim 1 in the preparation of color-changing devices or as a color-changing device.

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