An integrated pressure-sensing visible electrochromic device and a method of manufacturing the same

Abstract

The application discloses an integrated pressure-sensing visible electrochromic device and a preparation method thereof. The electrochromic device comprises a first conductive electrode film, an electrolyte structure layer and an electrochromic conductive film which are stacked in sequence. The electrolyte structure layer comprises an electrolyte film and an insulating layer which is combined on the surface of the electrolyte film. The surface of the electrolyte film which is in contact with the insulating film is provided with a microstructure. The application realizes the integrated construction of the pressure-sensing visible electrochromic device by using a simple structure design. The sensitivity and threshold range of the pressure sensing of the device can be adjusted by regulating the size of the microstructure of the electrolyte structure layer and the thickness of the insulating layer. In addition, the color change depth and position of the electrochromic device can directly and intuitively display the application size and position of the pressure signal, so that the user can read information more conveniently, and the electrochromic device has good portability.

Description

An integrated pressure-sensing and visual electrochromic device and its fabrication method Technical Field

[0001] This invention relates to the field of functional device technology, and in particular to an integrated pressure-sensing and visible electrochromic device and its preparation method. Background Technology

[0002] Electrochromic devices offer advantages such as controllable color switching, low cost, and energy efficiency, and have been applied in numerous fields. In recent years, with the rapid development of wearable devices, the integration of electrochromic technology with sensing, monitoring, and flexible electronics technologies has attracted widespread attention, with its main applications being wearable displays, electronic paper, and visual inspection equipment.

[0003] Existing technologies utilize polydimethylsiloxane with a pyramidal microstructure as a dielectric layer to develop highly sensitive flexible pressure sensors. These sensors are integrated with an electrochromic display via external circuitry. The voltage applied to the electrochromic display can be adjusted by changing the applied pressure and its duration, thereby controlling the color change. However, this visual electrochromic device simply connects two devices with different functions via external circuitry; it is not fully integrated and cannot display the corresponding force location based on the color change.

[0004] Therefore, the existing technology still needs further improvement and enhancement. Summary of the Invention

[0005] In view of the shortcomings of the prior art, the purpose of this invention is to provide an integrated pressure-sensing and visual electrochromic device and its preparation method. The electrochromic device provided by this invention has an integrated design, simple structure, and the depth and position of color change can intuitively display the applied pressure signal magnitude and position in situ.

[0006] To achieve this objective, the present invention adopts the following technical solution:

[0007] In a first aspect, there is an integrated pressure-sensing and visible electrochromic device, comprising: a first conductive electrode film, an electrolyte structure layer, and an electrochromic conductive film stacked sequentially.

[0008] The electrolyte structure layer includes an electrolyte membrane and an insulating layer composited on the surface of the electrolyte membrane, wherein the surface of the electrolyte membrane in contact with the insulating membrane is provided with microstructures.

[0009] As a preferred technical solution, in the integrated pressure-sensing and visible electrochromic device, one side of the electrolyte layer with a microstructure is in contact with the electrochromic conductive film, and the other side is in contact with the first conductive electrode film.

[0010] As a preferred technical solution, the integrated pressure-sensing and visible electrochromic device, wherein the first conductive electrode film comprises: a polydimethylsiloxane material layer and silver nanowires embedded in the surface of the polydimethylsiloxane material layer.

[0011] As a preferred technical solution, the integrated pressure-sensing and visible electrochromic device, wherein the electrochromic conductive film comprises: a second conductive electrode film, and an electrochromic material layer deposited on the surface of the second conductive electrode film; the second conductive electrode film comprises: a polydimethylsiloxane material layer and silver nanowires embedded on the surface of the polydimethylsiloxane material layer.

[0012] As a preferred technical solution, the integrated pressure-sensing and visible electrochromic device uses an electrochromic material selected from one or more of tungsten oxide nanowires, vanadium oxide nanowires, nickel oxide nanowires, polyaniline, and Prussian blue.

[0013] Secondly, a method for fabricating the aforementioned integrated pressure-sensing and visible electrochromic device includes the following steps:

[0014] S10. Provide a substrate; wherein the substrate may be selected from common substrates such as polycarbonate substrate, polyethylene terephthalate substrate, polyvinyl chloride substrate, and quartz glass.

[0015] S20. A silver nanowire dispersion is coated onto the surface of the substrate to obtain a silver nanowire material layer. The coating can be sprayed, i.e., the silver nanowire dispersion is sprayed onto the surface of the substrate to form a silver nanowire coating film. For example, the nozzle diameter of the spray gun is 0.1-0.5 μm, the distance between the spray gun and the substrate is 2-10 cm, and the silver nanowire concentration is 1-30 mg / ml. The substrate is heated during the spraying process, and the heating temperature can be 40-100℃.

[0016] S30. A polydimethylsiloxane mixture is coated onto the surface of the silver nanowire material layer. After curing and peeling, a first conductive electrode film is obtained. A spin coater can be used to spin coat the polydimethylsiloxane mixture onto the surface of the silver nanowire coating. The mass ratio of polydimethylsiloxane to curing agent in the polydimethylsiloxane mixture is (10-30):1. The spin coater has a spin coater speed of 300-1000 rpm, a spin coat time of 20-60 s, a spin coat acceleration of 100-500 rpm / s, and a thermal curing temperature of 50-100℃ for 0.5-3 h.

[0017] S40. Repeat steps S20 and S30 to obtain the second conductive electrode film; that is, the preparation method of the second conductive electrode film is the same as that of the first conductive electrode film.

[0018] S50. The electrochromic material dispersion is coated onto the surface of the second electrode film and cured to obtain the electrochromic conductive film; the electrochromic material dispersion can be sprayed onto the surface of the second electrode film by spraying, and after heating and stabilization, a highly stable electrochromic film is obtained.

[0019] S60. Disperse polyvinyl alcohol in water to obtain a polyvinyl alcohol aqueous solution. Add phosphoric acid to the polyvinyl alcohol aqueous solution to obtain an electrolyte solution. Alternatively, deionized water, polyvinyl alcohol, and phosphoric acid can be mixed, heated to dissolve, and allowed to stand to remove bubbles, forming a homogeneous solution. The heating temperature during dissolution is 60-90℃, and the standing time for degassing is 12-24h.

[0020] S70. The electrolyte solution is injected into the mold, solidified, and demolded to obtain an electrolyte membrane with a microstructure.

[0021] S80. A polydimethylsiloxane mixed solution is coated on a substrate to obtain an insulating film. The electrolyte membrane with the microstructure is stacked on the surface of the insulating film, and the insulating film is in contact with the microstructure. A certain pressure is applied to the electrolyte membrane, and the insulating film is attached to the top of the structure. The electrolyte structure layer is then cured.

[0022] S90. The first conductive electrode film, the electrolyte structure layer and the electrochromic conductive film are stacked sequentially and then encapsulated to obtain an integrated pressure-sensing and visible electrochromic device.

[0023] As a preferred technical solution, in the preparation method of the integrated pressure-sensing and visible electrochromic device, the concentration of the silver nanowire dispersion is 1-30 mg / ml.

[0024] As a preferred technical solution, the method for preparing the integrated pressure-sensing and visible electrochromic device, wherein the mold is selected from any one of the following: a hemispherical groove array structure polytetrafluoroethylene mold, a columnar groove array structure polytetrafluoroethylene mold, and a pyramidal groove array structure polytetrafluoroethylene mold.

[0025] As a preferred technical solution, in the method for preparing the integrated pressure-sensing and visible electrochromic device, the groove depth is 100-500μm and the spacing between the groove arrays is 0.1-5mm.

[0026] As a preferred technical solution, the method for preparing the integrated pressure-sensing and visible electrochromic device includes a pressure of 0.1-50 kPa and a curing temperature of 40-80°C and a curing time of 0.5-2 h in step S80.

[0027] Beneficial effects: Compared with the prior art, the integrated pressure sensing and visible electrochromic device provided by the present invention has a simple structure and is constructed in one piece. It can adjust the sensitivity and threshold range of pressure sensing by controlling the size of the microstructure of the electrolyte structure layer and the thickness of the insulating layer. In addition, the depth and position of the color change of this device can intuitively display the applied pressure signal magnitude and position in situ, making it more convenient for users to read information and has good portability. Attached Figure Description

[0028] Figure 1 is a schematic diagram of the integrated pressure-sensing and visual electrochromic device structure provided in an embodiment of the present invention.

[0029] Figure 2 shows the scanning electron microscope (SEM) image and XRD pattern of the silver nanowires prepared in Example 1 of this invention;

[0030] Figure 3 shows the scanning electron microscope (SEM) image and XRD pattern of the tungsten oxide nanowires prepared in Example 1 of this invention;

[0031] Figure 4 is a scanning electron microscope image of the conductive electrode thin film prepared in Example 1 of the present invention;

[0032] Figure 5 shows scanning electron microscope images of microstructures of different sizes prepared in Example 2 of the present invention;

[0033] Figure 6 shows scanning electron microscope images of the insulation layer thickness under different pressure loads prepared in Example 2 of the present invention;

[0034] Figure 7 is an optical photograph of the actual test pressure device and apparatus provided in Embodiment 3 of the present invention;

[0035] Figure 8 shows a comparison of the pressure sensing sensitivity of different insulation layer thicknesses provided in Embodiment 3 of the present invention;

[0036] Figure 9 shows the current variation in the device under different test pressures provided in Embodiment 3 of the present invention;

[0037] Figure 10 shows optical images of the electrochromic device under different shape pressures provided in Embodiment 3 of the present invention.

[0038] Figure 11 shows the current change in the device provided in Embodiment 3 of the present invention after 1000 cycles of constant pressure;

[0039] Figure 12 is a test diagram of the stability of the electrochromic device after 100 cycles of color change provided in Embodiment 3 of the present invention. Detailed Implementation

[0040] This invention provides an integrated pressure-sensing and visual electrochromic device and its fabrication method. To make the objectives, technical solutions, and effects of this invention clearer and more explicit, the invention is further described in detail below. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0041] Those skilled in the art will understand that, unless specifically stated otherwise, the singular forms “a,” “an,” “the,” and “the” used herein may also include the plural forms. It should be further understood that the word “comprising” as used in this specification means the presence of the stated features, integers, or steps, but does not exclude the presence or addition of one or more other features.

[0042] It will be understood by those skilled in the art that, unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. It should also be understood that terms such as those defined in general dictionaries should be understood to have the same meaning as in the context of the prior art, and should not be interpreted in an idealized or overly formal sense unless specifically defined as herein.

[0043] Figure 1 shows the structure of the integrated pressure-sensing, visible electrochromic device provided by the present invention. The electrochromic device includes: a first conductive electrode film 10, an electrolyte structure layer 20, and an electrochromic conductive film 30. The electrolyte structure layer 20 can be composed of an electrolyte layer with a microstructure on its surface and an insulating layer, with the insulating layer attached to the side of the electrolyte layer with the microstructure. The first conductive electrode film is stacked on the side of the electrolyte structure layer 20 without the microstructure, and the electrochromic conductive film is stacked on the side of the electrolyte structure layer 20 with the microstructure. It should be noted that the first conductive electrode film can also be stacked on the side of the electrolyte structure layer 20 with the microstructure, and the electrochromic conductive film can be stacked on the side of the electrolyte structure layer 20 without the microstructure. The first conductive electrode film 10 can be a polydimethylsiloxane elastomer film with silver nanowires embedded in its surface. The polydimethylsiloxane elastomer film can be obtained by spin-coating a mixture of polydimethylsiloxane and a curing agent onto a substrate and then curing it by heating. The electrochromic conductive film 30 includes: a second conductive electrode film and an electrochromic material layer deposited on the surface of the second conductive electrode film; the second conductive electrode film includes: a polydimethylsiloxane material layer and silver nanowires embedded on the surface of the polydimethylsiloxane material layer.

[0044] The electrochromic device provided by this invention displays pressure signals in situ through the following mechanism: When no pressure is applied, the device remains unchanged after applying a bias voltage; however, when pressure is applied at a point, the electrolyte comes into contact with the electrochromic layer, and under the application of a bias voltage, electrochromic changes occur at the contact area. The pressure signal (both magnitude and location) is displayed in situ; the location of the pressure corresponds to the location of the color change, and the magnitude of the pressure can be determined based on the degree of color change.

[0045] This invention utilizes a simple structural design to truly realize the integrated construction of a pressure-sensing and visual electrochromic device; it can also adjust the sensitivity and threshold range of pressure sensing by controlling the size of the electrolyte structure layer microstructure and the thickness of the insulating layer; furthermore, the depth and position of the color change of this electrochromic device can intuitively display the applied pressure signal magnitude and position in situ, making it easier for users to read information and providing good portability; the simple structural design provides a way to miniaturize pressure-sensing and visual devices, and also reduces production costs, enabling the device to be mass-produced.

[0046] The integrated pressure-sensing and visual electrochromic device and its fabrication method provided by the present invention will be further explained below with reference to specific fabrication examples.

[0047] Silver nanowires were prepared according to the synthesis method reported in the literature (Nano Letters, 2015, Vol. 15, pp. 6722-6726) and dispersed in an ethanol solution at a concentration of 10 mg / mL. The obtained silver nanowires were analyzed using scanning electron microscopy and X-ray diffraction, and their SEM images and XRD patterns are shown in Figure 2. A spray gun with a nozzle diameter of 0.3 μm was used, and the distance between the nozzle and the PC substrate was controlled at 8 cm. The heating stage temperature was controlled at 60 °C. 5 mL of the silver nanowire dispersion was uniformly sprayed onto a 36 cm thick substrate. 2 On a PC substrate; after spraying, the substrate was transferred to a spin coater for fixation. The spin coating speed was adjusted to 400 rpm, the spin coating time to 40 s, and the acceleration to 400 rpm / s. 2 g of polydimethylsiloxane mixed solution (mass ratio 10:1) was poured onto the substrate surface. After spin coating, the substrate with polydimethylsiloxane mixed solution was transferred to an 80℃ oven for heating and curing for 1 h. After peeling off the film, a flexible conductive electrode film was obtained. The film was analyzed by scanning electron microscopy, and its scanning electron micrograph is shown in Figure 4.

[0048] Tungsten oxide nanowires were prepared according to the synthesis method reported in the literature (Angewandte Chemie International Edition, 2012, Vol. 51, pp. 2395-2399) and dispersed in an ethanol solution at a concentration of 2 mg / mL. The obtained tungsten oxide nanowires were analyzed using scanning electron microscopy and X-ray diffraction, and their SEM images and XRD patterns are shown in Figure 3. A 0.3 μm nozzle was used, with the distance between the nozzle and the conductive electrode film controlled at 5 cm, and the heating stage temperature controlled at 120 °C. 2 mL of the tungsten oxide nanowire dispersion was uniformly sprayed onto a 36 cm thick substrate. 2 The conductive electrode film surface; after spraying, the film is transferred to a 150℃ oven and heated for 5 minutes to obtain a highly stable electrochromic film.

[0049] Weigh 1g of polyvinyl alcohol and add it to 9g of deionized water. Stir continuously in an oil bath at 85℃ for 1h until dissolved. After dissolution, when the temperature drops to 50℃, add 0.8ml of phosphoric acid, stir for 1h, and let stand at room temperature for 12h to remove bubbles, obtaining a mixed solution of polyvinyl alcohol and phosphoric acid (i.e., electrolyte solution). Pour the mixed solution into a mold, transfer it to a clean room, control the humidity at 50%, and place it at room temperature (25℃) for 12h. After demolding, an electrolyte film with a microstructure can be obtained. The electrolyte film obtained by scanning electron microscopy is analyzed, and its microstructure is shown in Figure 5.

[0050] Quartz glass was used as the substrate and fixed on a spin coater. The spin coating speed was set to 8000 rpm, the spin coating time to 60 s, and the acceleration to 500 rpm / s. 2 g of polydimethylsiloxane mixed solution (mass ratio 10:1) was poured onto the substrate surface and spin coated. After spin coating, an electrolyte film was placed on it, with the contact surface being a microstructure surface. The entire assembly was transferred to the compression platform of a universal testing machine. Stresses of 0.5 kPa, 1 kPa, 2 kPa, and 5 kPa were applied to different electrolyte films using the universal testing machine. The films were then transferred to a 60℃ oven and heated for 30 min to obtain electrolyte structural layers with polydimethylsiloxane elastomers of different thicknesses. The interfaces of the obtained electrolyte structural layers were analyzed and characterized using a scanning electron microscope, and the scanning electron microscope images of the insulating layers with different thicknesses were obtained, as shown in Figure 6.

[0051] The conductive electrode film and electrochromic film obtained above are placed on both sides of the electrolyte structure layer in the order of assembly structure. After encapsulation, an integrated pressure-sensing and visible electrochromic device can be obtained. The pressure device used in the characterization test and the actual image of the device are shown in Figure 7.

[0052] The obtained devices were characterized by pressure sensing sensitivity tests, and the results were compared, as shown in Figure 8. Figure 8 shows that the pressure-sensing visible electrochromic device has good sensing sensitivity, with the device having the thinnest insulating layer exhibiting the highest sensitivity.

[0053] The integrated pressure-sensing and visual electrochromic device was subjected to different pressure tests, as shown in Figure 9. During the test, the device's current and transmittance changed with the pressure, and the device maintained a consistent response over time. The reactions under different pressures could be clearly distinguished. In addition, as shown in Figure 10, after applying pressure of different shapes, the device showed color-changing areas of the same shape, indicating that the integrated device has a good function of providing in-situ visual pressure information.

[0054] Cyclic stability tests were performed on the integrated pressure-sensing and visible electrochromic device. As shown in Figure 11, after 1000 pressure cycles, the current signal still maintained good response speed and magnitude. As shown in Figure 12, after 100 electrochromic cycles, it was still able to change color stably, indicating that the device has excellent cyclic stability and a stable output signal.

[0055] It should be understood that the application of the present invention is not limited to the examples above. Those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims.

Claims

1. An integrated pressure-sensing and visual electrochromic device, characterized in that, include: The first conductive electrode film, the electrolyte structure layer, and the electrochromic conductive film are stacked sequentially. The electrolyte structure layer includes: an electrolyte membrane and an insulating membrane composited on the surface of the electrolyte membrane, wherein the surface of the electrolyte membrane in contact with the insulating membrane is provided with microstructures; the electrochromic conductive film includes: a second conductive electrode film and an electrochromic material layer deposited on the surface of the second conductive electrode film; wherein the electrolyte membrane is made of polyvinyl alcohol and phosphoric acid, the insulating membrane is made of polydimethylsiloxane, and the electrochromic material layer is made of tungsten oxide nanowires.

2. The integrated pressure-sensing and visible electrochromic device according to claim 1, characterized in that, The electrolyte structure layer has a microstructure on one side that is in contact with the electrochromic conductive film, and the other side that is in contact with the first conductive electrode film.

3. The integrated pressure-sensing and visible electrochromic device according to claim 1, characterized in that, The first conductive electrode film includes: a polydimethylsiloxane material layer and silver nanowires embedded on the surface of the polydimethylsiloxane material layer.

4. The integrated pressure-sensing and visible electrochromic device according to claim 1, characterized in that, The second conductive electrode film includes: a polydimethylsiloxane material layer and silver nanowires embedded in the surface of the polydimethylsiloxane material layer.

5. A method for fabricating an integrated pressure-sensing, visual electrochromic device as described in claim 1, characterized in that, The process includes the following steps: S10, providing a substrate; S20, coating a silver nanowire dispersion onto the surface of the substrate to obtain a silver nanowire material layer; S30, coating a polydimethylsiloxane mixture onto the surface of the silver nanowire material layer, followed by curing and peeling to obtain a first conductive electrode film; S40, repeating steps S20 and S30 to obtain a second conductive electrode film; S50, coating an electrochromic material dispersion onto the surface of the second conductive electrode film to obtain the electrochromic conductive film. S60. Disperse polyvinyl alcohol in water to obtain a polyvinyl alcohol aqueous solution, add phosphoric acid to the polyvinyl alcohol aqueous solution to obtain an electrolyte solution; S70. Inject the electrolyte solution into a mold, cure and demold to obtain an electrolyte membrane with a microstructure; S80. A polydimethylsiloxane mixture is coated onto a substrate to obtain an insulating film. The electrolyte membrane with the microstructure is stacked on the surface of the insulating film, and the insulating film is in contact with the microstructure. A certain pressure is applied to the electrolyte membrane, and the insulating film is attached to the top of the structure. The electrolyte structure layer is then cured to obtain the electrolyte structure layer. S90. The first conductive electrode film, the electrolyte structure layer, and the electrochromic conductive film are stacked sequentially and then encapsulated to obtain an integrated pressure-sensing and visible electrochromic device.

6. The method for fabricating the integrated pressure-sensing and visible electrochromic device according to claim 5, characterized in that, The concentration of the silver nanowire dispersion is 1-30 mg / ml.

7. The method for fabricating the integrated pressure-sensing and visible electrochromic device according to claim 5, characterized in that, The mold is selected from any one of the following: a hemispherical groove array structure polytetrafluoroethylene mold, a columnar groove array structure polytetrafluoroethylene mold, and a pyramidal groove array structure polytetrafluoroethylene mold.

8. The method for fabricating the integrated pressure-sensing and visible electrochromic device according to claim 7, characterized in that, The groove depth is 100-500μm, and the spacing between the groove arrays is 0.1-5mm.

9. The method for fabricating the integrated pressure-sensing and visible electrochromic device according to claim 5, characterized in that, The pressure is 0.1-50 kPa; the curing temperature in step S80 is 40-80℃, and the time is 0.5-2 h.

Images