Preparation method of a novel electrochromic device based on a conductive polymer hydrogel

Abstract

The present invention discloses a novel electrochromic device based on a conductive polymer hydrogel and a preparation method thereof, belonging to the field of materials. By preparing a conductive polymer hydrogel film and a hydrogel electrolyte, the present invention constructs a novel electrochromic device composed of a sandwich structure combination of an electrode / a conductive polymer hydrogel electrochromic functional layer / a hydrogel electrolyte layer; invents a new conductive polymer hydrogel electrochromic material, and at the same time, the hydrogel electrolyte layer replaces the electrode layer, ion storage layer and electrolyte layer of a traditional electrochromic device, simplifying the device structure; and provides a preparation method of a novel electrochromic device based on a conductive polymer hydrogel. The present invention not only reduces the response time and voltage, but also improves the stability of the electrochromic device; and has a simple structure, a simple preparation process, low cost, is suitable for large-scale production, and shows great application value in the fields of smart wear and even military camouflage, etc.

Description

Technical Field

[0001] The present invention relates to the field of materials, and particularly to a preparation method of a novel electrochromic device based on a conductive polymer hydrogel. Background Art

[0002] Electrochromism refers to the phenomenon that under the action of a weak electric field, the color can change reversibly and continuously through the dual injection, extraction or redox reaction of electrons and ions. Assembling a material with electrochromic properties together with an ion conductive layer, an ion storage layer, and an electrode constitutes an electrochromic device with a display function (five-layer structure). Such devices show broad application prospects in many fields, such as smart energy-saving windows, non-glare rearview mirrors, low-power display devices, electronic paper, and color-changing skins. However, the excessive number of device layers results in slow response speed, low coloring efficiency, and also brings problems such as energy consumption, heat dissipation, and multi-material compatibility (Chinese Patent: CN202210781539.X). Therefore, the simplification of the electrochromic device structure has become one of the important challenges that need to be solved urgently in this field.

[0003] Hydrogels are a type of transparent, flexible and soft material with a three-dimensional porous structure, which are widely used in the field of flexible electronics. By modifying and decorating the hydrogels, their mechanical properties can be enhanced, and various new excellent properties can also be imparted to the hydrogels, such as adhesiveness, self-healing, and optical, electrical, and magnetic properties. In Chinese Patents: CN202110018875.4 and CN202210523795.9, the application of hydrogels in electrochromic devices mainly focuses on the electrolyte layer, and a multifunctional hydrogel electrolyte is used to replace the electrode, ion storage layer, and ion conductive layer, greatly simplifying the device structure.

[0004] Chinese Patent CN202110719186.6 discloses the preparation of an electrochromic device using an electrochromic material. PEDOT:PSS conductive polymer is sprayed on a multifunctional polyacrylamide-lithium chloride hydrogel electrolyte to prepare a three-layer electrochromic device. This method still does not solve the problem of the adhesion between the electrochromic function and the electrolyte layer, and using the spraying method, the PEDOT:PSS conductive polymer film is easily broken during the bending or stretching of the hydrogel under external force, resulting in poor device stability and slow response speed. Therefore, the research and development of high-performance electrochromic hydrogel materials is an important challenge facing scientific researchers.

[0005] Due to their flexibility, high tensile properties, and biocompatibility, conductive polymer hydrogels have attracted great interest as soft conductors for flexible electronic devices. Conductive polymer hydrogels provide a good interface between electron transport and ion transport, as well as between brittle and soft materials, and have extensive tunability in terms of mechanical properties, electrical conductivity, and functionalization. Combining the optoelectronic functions of conductive polymers and the excellent mechanical properties of hydrogels, conductive polymer hydrogels have always been a hot research direction in the field of flexible electronics and show great application potential in new applications such as flexible supercapacitors, flexible sensors, and biomedical electronics. However, their application in the field of electrochromics has not been reported yet. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a preparation method of a novel electrochromic device based on conductive polymer hydrogels, which has a simple structure, a simple preparation process, low cost, is suitable for large-scale production, has good stability, a short response time, and a lower voltage requirement.

[0007] To solve the above technical problems, the present invention provides the following technical solutions:

[0008] A preparation method of a novel electrochromic device based on conductive polymer hydrogels, the preparation method comprising the following steps:

[0009] 1) Add an electrolyte to deionized water to obtain an electrolyte solution; add polyvinyl alcohol, heat and mix, and place the mixed solution in a refrigerator for freezing and then thaw at room temperature; repeat 3 - 5 times to prepare a hydrogel electrolyte layer;

[0010] 2) Mix a conductive polymer, an elastomer, and deionized water, grind and homogenize to obtain a conductive polymer ink; perform film-forming treatment at the electrode layer, dry at room temperature, and then perform solvation treatment to obtain a conductive polymer hydrogel electrochromic functional layer;

[0011] 3) Place the hydrogel electrolyte layer obtained in step 1) on the conductive polymer hydrogel electrochromic functional layer prepared in step 2), and encapsulate it with polydimethylsiloxane (PDMS) to obtain a novel electrochromic device.

[0012] Further, in step 1), the electrolyte is any one of lithium perchlorate (LiClO4), LiAsF6, LiBF6, LiPF6, or LiCF3SO3; the concentration of the electrolyte solution is 1 - 10 mol / L.

[0013] Further, in step 1), the concentration of polyvinyl alcohol is 10 wt.% - 20 wt.%.

[0014] Further, in the step 2), the conductive polymer is any one of polyaniline (PANI), poly(3,4-ethylenedioxythiophene) (PEDOT), polypyrrole (PPy), poly(3-hexylthiophene) (P3HT), or poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS).

[0015] Further, in the step 2), the elastomer is one or more of polyurethane (PU), polyvinyl alcohol (PVA), or polyacrylamide (PAAm).

[0016] Further, in the step 2), the mass ratio of the conductive polymer to the elastomer is 1:1 to 1:5; the mass concentration of the conductive polymer ink is 3 wt.% to 8 wt.%.

[0017] Further, in the step 2), the electrode layer is any one of indium tin oxide transparent conductive glass (ITO-glass), indium tin oxide transparent conductive polyethylene terephthalate (ITO-PET), fluorine-doped tin oxide transparent conductive glass (FTO-glass), fluorine-doped tin oxide transparent conductive polyethylene terephthalate (FTO-PET), AgNWs / PDMS, AgNWs / PU, AgNWs / SEBS, AuNWs / PDMS, AuNWs / PU, AuNWs / SEBS, Ag-AuNWs / PDMS, Ag-AuNWs / PU, Ag-AuNWs / SEBS, SWCNT / PDMS, SWCNT / PU, SWCNT / SEBS, PEDOT:PSS / PDMS, PEDOT:PSS / PU, PEDOT:PSS / SEBS, AgNWs / PEDOT:PSS / PDMS, AgNWs / PEDOT:PSS / PU, or AgNWs / PEDOT:PSS / SEBS.

[0018] Further, in the step 2), the method of solvation treatment is direct drop coating with a solvent having a concentration of 0.01–1 mol / L, and the solvent is any one or more of dimethyl sulfoxide (DMSO), ethylene glycol (EG), N,N-dimethylformamide (DMF), tetrahydrofuran (THF), glycerol, hexitol, ethylene glycol monomethyl ether, diethylene glycol, dimethyl sulfate, erythritol, xylitol, concentrated sulfuric acid (H2SO4), quaternary ammonium salt ionic liquid, lithium chloride (LiCl), sodium chloride (NaCl), potassium chloride (KCl), calcium chloride (CaCl2), magnesium chloride (MgCl2), aluminum chloride (AlCl3), samarium chloride (SmCl2), zirconium chloride (ZrCl4), iron chloride (FeCl3), or copper chloride (CuCl2).

[0019] Furthermore, in the step 2), the film forming method is spin coating, inkjet printing, screen printing and 3D printing; and the drying time at room temperature is 24-48 hours.

[0020] Furthermore, in step 1), the heating condition is 80-90° C.; the freezing condition is -20° C. for 8 hours, and the thawing condition is at room temperature for 4 hours.

[0021] The present invention has the following beneficial effects:

[0022] In the above scheme, the present invention utilizes processing and manufacturing methods such as screen printing and 3D printing, as well as solvent post-treatment, to prepare a conductive polymer hydrogel, thus pioneering new materials in the field of conductive polymer hydrogel electrochromism. Simultaneously, materials with excellent performance are screened, and a layer of hydrogel electrolyte is used to replace the electrode, ion storage layer, and ion conductive layer. The assembled new conductive polymer hydrogel electrochromic device has a simplified three-layer device structure compared to the traditional electrochromic device (five-layer structure). Compared with the conventional hydrogel electrochromic device, the present invention has a faster response speed (coloring time: 0.3s, fading time: 0.42s), a lower voltage requirement, and better stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 Schematic diagram of the three-layer structure of the novel electrochromic device based on conductive polymer hydrogel provided by the present invention;

[0024] Figure 2 Schematic diagram of the assembly process of the novel electrochromic device based on conductive polymer hydrogel prepared in Example 1 of the present invention;

[0025] Figure 3 Actual pictures of the color change of the novel electrochromic device based on conductive polymer hydrogel prepared in Example 1 of the present invention in normal and bent states;

[0026] Figure 4 This is a comparison chart of transmittance curves of the novel electrochromic device based on conductive polymer hydrogel prepared in Example 1 of the present invention and Comparative Example 1;

[0027] Figure 5 This is the stability curve (10,000 cycles, 200,000 s) of the novel electrochromic device based on conductive polymer hydrogel prepared in Example 1 of the present invention;

[0028] Figure 6 This is the stability curve (400 cycles, 8000 s) of the electrochromic device based on PEDOT:PSS conductive polymer prepared in Comparative Example 1 of the present invention. DETAILED DESCRIPTION

[0029] To make the technical problems, technical solutions, and advantages to be solved by the present invention clearer, the following will be described in detail with reference to the accompanying drawings and specific embodiments. However, the present invention is by no means limited to these examples. The following are only preferred embodiments of the present invention, which are only used to explain the present invention and should not be construed as limiting the scope of the present invention. It should be noted that any modifications, equivalent substitutions, and improvements made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

[0030] Unless otherwise specified, the components used in the present invention are all commercially available products. Without special instructions for the experimental test conditions, they are all conventional technical operations in the art.

[0031] Aiming at the problems of slow response speed and poor stability performance of electrochromic devices in the prior art, the present invention provides a novel electrochromic device based on a conductive polymer hydrogel.

[0032] Example 1

[0033] A preparation method of a conductive polymer hydrogel electrochromic device includes the following steps:

[0034] 1) Add 1M LiClO4 electrolyte to deionized water, stir well to dissolve to obtain an electrolyte solution; add 10wt.% polyvinyl alcohol, heat at 60°C and stir well for 2 hours to obtain a mixed solution; pour it into a mold (5 cm long, 2 cm wide, 0.8 cm thick), place it in a refrigerator, freeze at -20°C for 8 h; thaw at room temperature for 4 h; repeat the cycle 3 times to prepare a PVA-LiClO4 hydrogel electrolyte.

[0035] 2) Mix PEDOT:PSS particles with deionized water, grind and homogenize to obtain a PEDOT:PSS conductive polymer ink with a mass concentration of 5wt.%; perform screen printing on ITO-PET, dry at room temperature, and drop-coat with a 0.03mol / L FeCl3 solvent to obtain a PEDOT:PSS conductive polymer hydrogel electrochromic layer.

[0036] 3) Place the PVA-LiClO4 hydrogel electrolyte obtained in step 1) on the PEDOT:PSS conductive polymer hydrogel electrochromic layer obtained in step 2), and encapsulate it at room temperature with a PDMS frame to obtain a PEDOT:PSS conductive polymer hydrogel electrochromic device.

[0037] Figure 2 It is a schematic diagram of the assembly process of the novel electrochromic device based on the conductive polymer hydrogel prepared by the present invention.

[0038] Figure 3To adjust the voltage applied to the electrochromic device of PEDOT:PSS conductive polymer hydrogel through an electrochemical workstation, the color changes of the electrochromic device of the conductive polymer hydrogel were recorded in the normal and bent states.

[0039] Figure 4 In this example, a UV spectrophotometer was used to adjust the voltage applied to the working electrode through an electrochemical workstation, and the transmittance-time curve of the electrochromic device of the conductive polymer hydrogel at the maximum absorption wavelength (685 nm) was recorded.

[0040] Figure 5 In this example, a UV spectrophotometer was used to adjust the voltage applied to the working electrode through an electrochemical workstation, and the stability curve (10,000 cycles, 200,000 s) of the electrochromic device of the conductive polymer hydrogel at the maximum absorption wavelength (685 nm) was recorded.

[0041] Example 2

[0042] A method for preparing an electrochromic device of a conductive polymer hydrogel includes the following steps:

[0043] 1) Add 1M LiAsF6 electrolyte to deionized water, stir well to dissolve to obtain an electrolyte solution; add 12 wt.% polyvinyl alcohol, heat at 60 °C and stir well for 2 hours to obtain a mixed solution; pour it into a mold (5 cm long, 2 cm wide, 0.8 cm thick), place it in a refrigerator, freeze at -20 °C for 8 h; thaw at room temperature for 4 h; repeat 3 times to prepare a PVA-LiAsF6 hydrogel electrolyte.

[0044] 2) Mix P3HT particles with deionized water, grind and homogenize to obtain a P3HT conductive polymer ink with a mass concentration of 10 wt.%; perform 3D printing on the AuNWs / PU transparent conductive substrate layer, dry at room temperature, and drop-coat with a 0.05 mol / L CaCl2 solvent to obtain a P3HT conductive polymer hydrogel electrochromic layer.

[0045] 3) Place the PVA-LiAsF6 hydrogel electrolyte obtained in step 1) on the P3HT conductive polymer hydrogel electrochromic layer obtained in step 2), and encapsulate it at room temperature with a PDMS frame to obtain a P3HT conductive polymer hydrogel electrochromic device.

[0046] Example 3

[0047] A method for preparing an electrochromic device of a conductive polymer hydrogel includes the following steps:

[0048] 1) Add 3M LiPF6 electrolyte to deionized water, stir well to dissolve to obtain an electrolyte solution; add 15 wt.% polyvinyl alcohol, heat at 60 °C and stir well for 2 hours to obtain a mixed solution; pour it into a mold (5 cm long, 2 cm wide, 0.8 cm thick), place it in the refrigerator, freeze at -20 °C for 8 h; at room temperature, thaw for 4 h; repeat the cycle 3 times to prepare a PVA-LiCl hydrogel electrolyte.

[0049] 2) Mix PANI particles with deionized water, grind and homogenize to obtain a PANI conductive polymer ink with a mass concentration of 6 wt.%; perform inkjet printing on the AgNWs / PDMS transparent conductive substrate layer, dry at room temperature, and drop-coat with a 0.05 mol / L KCl solvent to obtain a PANI conductive polymer hydrogel electrochromic layer.

[0050] 3) Place the PVA-LiCl hydrogel electrolyte obtained in step 1) on the PANI conductive polymer hydrogel electrochromic layer obtained in step 2), and encapsulate it at room temperature with a PDMS frame to obtain a PANI conductive polymer hydrogel electrochromic device.

[0051] Example 4

[0052] A method for preparing a conductive polymer hydrogel electrochromic device, comprising the following steps:

[0053] 1) Add 1.5M LiBF6 electrolyte to deionized water, stir well to dissolve to obtain an electrolyte solution; add 10 wt.% polyvinyl alcohol, heat at 60 °C and stir well for 2 hours to obtain a mixed solution; pour it into a mold (5 cm long, 2 cm wide, 0.8 cm thick), place it in the refrigerator, freeze at -20 °C for 8 h; at room temperature, thaw for 4 h; repeat the cycle 3 times to prepare a PVA-LiBF6 hydrogel electrolyte.

[0054] 2) Mix PPy particles with deionized water, grind and homogenize to obtain a PPy conductive polymer ink with a mass concentration of 1 wt.%; perform spin coating on the ITO-glass transparent conductive substrate layer, dry at room temperature, and drop-coat with a 0.06 mol / L dimethyl sulfoxide (DMSO) solvent to obtain a PPy conductive polymer hydrogel electrochromic layer.

[0055] 3) Assembly of the PPy conductive polymer hydrogel electrochromic device

[0056] Place the PVA-LiBF6 hydrogel electrolyte obtained in step 1) on the PPy conductive polymer hydrogel electrochromic layer obtained in step 2), and encapsulate it at room temperature with a PDMS frame to obtain a PPy conductive polymer hydrogel electrochromic device.

[0057] Example 5

[0058] Preparation method of conductive polymer hydrogel electrochromic device, comprising the following steps:

[0059] 1) Add 1.5 M LiCF3SO3 electrolyte to deionized water, stir well to dissolve to obtain an electrolyte solution; add 12 wt.% polyvinyl alcohol, heat at 60 °C and stir well for 2 hours to obtain a mixed solution; pour it into a mold (5 cm long, 2 cm wide, 0.8 cm thick), place it in a refrigerator, carry out freezing at -20 °C for 8 h; thaw at room temperature for 4 h; repeat the cycle 3 times to prepare a PVA-LiCF3SO3 hydrogel electrolyte.

[0060] 2) Mix PEDOT particles with deionized water, grind and homogenize to obtain a PEDOT conductive polymer ink with a mass concentration of 1 wt.%; spin-coat on the FTO-glass transparent conductive substrate layer, dry at room temperature, and drop-coat with 0.04 mol / L glycerol solvent to obtain a PEDOT conductive polymer hydrogel electrochromic layer.

[0061] 3) Place the PVA-LiCF3SO3 hydrogel electrolyte obtained in step 1) on the PEDOT conductive polymer hydrogel electrochromic layer obtained in step 2), and encapsulate it at room temperature with a PDMS frame to obtain a PEDOT conductive polymer hydrogel electrochromic device.

[0062] Example 6

[0063] Preparation method of conductive polymer hydrogel electrochromic device, comprising the following steps:

[0064] 1) Add 2.5 M LiAsF6 electrolyte to deionized water, stir well to dissolve to obtain an electrolyte solution; add 14 wt.% polyvinyl alcohol, heat at 60 °C and stir well for 2 hours to obtain a mixed solution; pour it into a mold (5 cm long, 2 cm wide, 0.8 cm thick), place it in a refrigerator, carry out freezing at -20 °C for 8 h; thaw at room temperature for 4 h; repeat the cycle 3 times to prepare a PVA-LiAsF6 hydrogel electrolyte.

[0065] 2) Mix PEDOT:PSS particles, PU (mass ratio 1:1) with deionized water, grind and homogenize to obtain a PEDOT:PSS / PU conductive polymer ink with a mass concentration of 40 wt.%; perform 3D printing on the AgNWs / PEDOT:PSS / PDMS transparent conductive substrate layer, dry at room temperature, and drop-coat with 0.05 mol / L CaCl2 solvent to obtain a PEDOT:PSS / PU conductive polymer hydrogel electrochromic layer.

[0066] 3) Place the PVA-LiAsF6 hydrogel electrolyte obtained in step 1) on the PEDOT:PSS / PU conductive polymer hydrogel electrochromic layer obtained in step 2), and encapsulate it at room temperature with a PDMS frame to obtain a PEDOT conductive polymer hydrogel electrochromic device.

[0067] Example 7

[0068] A method for preparing a conductive polymer hydrogel electrochromic device, comprising the following steps:

[0069] 1) Add 7M LiPF6 electrolyte to deionized water, stir well to dissolve to obtain an electrolyte solution; add 16 wt.% polyvinyl alcohol, heat at 60 °C and stir well for 2 hours to obtain a mixed solution; pour it into a mold (5 cm long, 2 cm wide, 0.8 cm thick), place it in a refrigerator, freeze at -20 °C for 8 h; thaw at room temperature for 4 h; repeat the cycle 3 times to prepare a PVA-LiCl hydrogel electrolyte.

[0070] 2) Mix PEDOT:PSS particles, PVA (mass ratio 1:3) with deionized water, grind and homogenize to obtain a 10 wt.% PEDOT:PSS / PVA conductive polymer ink; perform inkjet printing on the AgNWs / SEBS transparent conductive substrate layer, dry at room temperature, and drop-coat with 0.08 mol / L AlCl3 solvent to obtain a PEDOT:PSS / PVA conductive polymer hydrogel electrochromic layer.

[0071] 3) Place the PVA-LiCl hydrogel electrolyte obtained in step 1) on the PEDOT:PSS / PVA conductive polymer hydrogel electrochromic layer obtained in step 2), and encapsulate it at room temperature with a PDMS frame to obtain a PEDOT:PSS / PVA conductive polymer hydrogel electrochromic device.

[0072] Example 8

[0073] A method for preparing a conductive polymer hydrogel electrochromic device, comprising the following steps:

[0074] 1) Add 6M LiClO4 electrolyte to deionized water, stir well to dissolve to obtain an electrolyte solution; add 15 wt.% polyvinyl alcohol, heat at 60 °C and stir well for 2 hours to obtain a mixed solution; pour it into a mold (5 cm long, 2 cm wide, 0.8 cm thick), place it in a refrigerator, freeze at -20 °C for 8 h; thaw at room temperature for 4 h; repeat the cycle 3 times to prepare a PVA-LiClO4 hydrogel electrolyte.

[0075] 2) Mix PEDOT:PSS particles and PAAm (mass ratio 1:5) with deionized water, grind and homogenize to obtain a 15 wt.% PEDOT:PSS / PAAm conductive polymer ink; perform 3D printing on the Ag-AuNWs / SEBS transparent conductive substrate layer, dry at room temperature, and drop-coat with 0.1 mol / L ZrCl4 solvent to obtain a PEDOT:PSS / PAAm conductive polymer hydrogel electrochromic layer.

[0076] 3) Place the PVA-LiClO4 hydrogel electrolyte obtained in step 1) on the PEDOT conductive polymer hydrogel electrochromic layer obtained in step 2), and encapsulate at room temperature with a PDMS frame to obtain a PEDOT:PSS / PAAm conductive polymer hydrogel electrochromic device.

[0077] Example 9

[0078] A method for preparing a conductive polymer hydrogel electrochromic device, comprising the following steps:

[0079] 1) Add 3M LiCF3SO3 electrolyte to deionized water, stir well to dissolve to obtain an electrolyte solution; add 16 wt.% polyvinyl alcohol, heat at 60 °C and stir well for 2 hours to obtain a mixed solution; pour into a mold (5 cm long, 2 cm wide, 0.8 cm thick), place in a refrigerator, freeze at -20 °C for 8 h; thaw at room temperature for 4 h; repeat 3 times to prepare a PVA-LiCF3SO3 hydrogel electrolyte;

[0080] 2) Mix PEDOT particles and PU (mass ratio 1:1.5) with deionized water, grind and homogenize to obtain a 1 wt.% PEDOTPU conductive polymer ink; spin-coat on the PEDOT:PSS / PDMS transparent conductive substrate layer, dry at room temperature, and drop-coat with 0.07 mol / L CuCl2 solvent to obtain a PEDOT / PU conductive polymer hydrogel electrochromic layer.

[0081] 3) Place the PVA-LiCF3SO3 hydrogel electrolyte obtained in step 1) on the PEDOT / PU conductive polymer hydrogel electrochromic layer obtained in step 2), and encapsulate at room temperature with a PDMS frame to obtain a PEDOT / PU conductive polymer hydrogel electrochromic device.

[0082] Example 10

[0083] A method for preparing a conductive polymer hydrogel electrochromic device, comprising the following steps:

[0084] 1) Add 10 mL of LiBF6 electrolyte to deionized water, stir well to dissolve to obtain an electrolyte solution; add 20 wt.% polyvinyl alcohol, heat at 60 °C and stir well for 2 hours to obtain a mixed solution; pour it into a mold (5 cm long, 2 cm wide, 0.8 cm thick), place it in the refrigerator, freeze at -20 °C for 8 h; thaw at room temperature for 4 h; repeat the cycle 3 times to prepare the PVA-KCl hydrogel electrolyte.

[0085] 2) Mix PPY particles and PVA (mass ratio 1:2.5) with deionized water, grind and homogenize to obtain a 20 wt.% PPy / PVA conductive polymer ink; perform 3D printing on the AgNWs / PEDOT:PSS / SEBS transparent conductive substrate layer, dry at room temperature, and drop-coat with a 0.05 mol / L SmCl2 solvent to obtain the PPy / PVA conductive polymer hydrogel electrochromic layer.

[0086] 3) Place the PVA-KCl hydrogel electrolyte obtained in step 1) on the PPy / PVA conductive polymer hydrogel electrochromic layer obtained in step 2), and encapsulate it at room temperature with a PDMS frame to obtain the PPy / PVA conductive polymer hydrogel electrochromic device.

[0087] After multiple experiments and explorations by the inventors, the selection of different electrode layers has little effect on the performance parameters of the novel electrochromic device. It is found that the selection of the conductive polymer hydrogel film and the hydrogel electrolyte layer has a greater impact on the performance of the novel electrochromic device. The following comparative examples are set for further illustration. The combination method of the electrochromic device in the comparative examples is exactly the same as that in Example 1 of the present invention, except that only the selection of each component is different.

[0088] Comparative Example 1

[0089] The preparation of the hydrogel electrolyte layer in this case is exactly the same as that in Example 1. Then, spray a 5 wt.% PEDOT:PSS conductive polymer solution on the surface of the hydrogel electrolyte layer, and then evenly place the ITO-PET electrode on the surface of the hydrogel electrolyte layer sprayed with the conductive polymer solution to test the performance of the electrochromic device.

[0090] The response time of the electrochromic device based on the PEDOT:PSS conductive polymer is 2.33 s for the coloring time and 0.41 s for the fading time (as Figure 4 shown). The stability of the electrochromic device based on the PEDOT:PSS conductive polymer is only 400 cycles (as Figure 6 shown).

[0091] Comparative Example 2

[0092] A preparation method for a conductive polymer hydrogel electrochromic device, comprising the following steps:

[0093] 1) Add 1 M LiCl electrolyte to deionized water, stir well to dissolve to obtain an electrolyte solution; add 10 wt.% polyvinyl alcohol, heat at 60 °C and stir well for 2 hours to obtain a mixed solution; pour it into a mold (5 cm long, 2 cm wide, 0.8 cm thick), place it in a refrigerator, carry out freezing at -20 °C for 8 h; at room temperature, thaw for 4 h; repeat the cycle 3 times to prepare a PVA-LiCl hydrogel electrolyte.

[0094] 2) Mix PEDOT:PSS particles with deionized water, grind and homogenize to obtain a PEDOT:PSS conductive polymer ink with a mass concentration of 5 wt.%; perform screen printing on ITO-PET and dry at room temperature to obtain a PEDOT:PSS conductive polymer hydrogel electrochromic layer.

[0095] 3) Place the PVA-LiCl hydrogel electrolyte obtained in step 1) on the PEDOT:PSS conductive polymer hydrogel electrochromic layer obtained in step ⒉), and encapsulate it at room temperature with a PDMS frame to obtain a PEDOT:PSS conductive polymer hydrogel electrochromic device.

[0096] Comparative Example 3

[0097] A method for preparing a conductive polymer hydrogel electrochromic device, comprising the following steps:

[0098] 1) Add 1.5 M LiBF6 electrolyte to deionized water, stir well to dissolve to obtain an electrolyte solution; add 10 wt.% polyvinyl alcohol, heat at 60 °C and stir well for 2 hours to obtain a mixed solution; pour it into a mold (5 cm long, 2 cm wide, 0.8 cm thick), place it in a refrigerator, carry out freezing at -20 °C for 8 h; at room temperature, thaw for 4 h; repeat the cycle 3 times to prepare a PVA-LiBF6 hydrogel electrolyte.

[0099] 2) Mix PPy particles with deionized water, grind and homogenize to obtain a PPy conductive polymer ink with a mass concentration of 1 wt.%; perform spin coating on an ITO-glass transparent conductive substrate layer and dry at room temperature to obtain a PPy conductive polymer hydrogel electrochromic layer.

[0100] 3) Assembly of the PPy conductive polymer hydrogel electrochromic device

[0101] Place the PVA-LiBF6 hydrogel electrolyte obtained in step 1) on the PPy conductive polymer hydrogel electrochromic layer obtained in step 2), and encapsulate it at room temperature with a PDMS frame to obtain a PPy conductive polymer hydrogel electrochromic device.

[0102] To further illustrate the beneficial effects achieved by the present invention, the performance data of the novel electrochromic devices prepared in Examples 1-10 and the electrochromic devices prepared in Comparative Examples 1-3 are shown in Table 1 below:

[0103] Among them, the test method for the response time and stability performance data of the electrochromic device is as follows: To characterize the electrochromic performance of the electrochromic device, a test system was built according to the experimental needs in this patent. The main test equipment includes the CHI660E electrochemical workstation of Shanghai Chenhua and the Maya2000 fiber optic spectrometer of Ocean Optics Company in the United States. In-situ testing was adopted during the test process, and the transmittance spectrum change process with voltage could be monitored in real time. The test wavelength range was 400-1100 nm. When evaluating the color change performance of the electrochromic device, the contrast is usually used to measure the magnitude of the spectral modulation ability of the thin film. In this article, the contrast is the difference between the maximum transmittance and the minimum transmittance at a fixed wavelength. In addition, the contrast retention value (i.e., the ratio of the contrast before and after cycling) is also used to compare the electrochromic stability of the thin film. The response time is the time taken for the transmittance to change by 90% during the coloring or fading process. The stability was tested by the cyclic voltage pulse method with +1V, 10s; -1V, 10s as a cycle.

[0104] Table 1

[0105]

[0106]

[0107] In Examples 1-10 of the present invention, a novel electrochromic device composed of a sandwich structure combination of an electrode / conductive polymer hydrogel electrochromic functional layer / hydrogel electrolyte layer was constructed through the prepared conductive polymer hydrogel thin film and hydrogel electrolyte; among them, the hydrogel electrolyte layer replaced the electrode layer, ion storage layer, and electrolyte layer of the traditional electrochromic device, achieving the purpose of simplifying the device structure. The present invention not only reduces the response time and voltage but also improves the stability of the electrochromic device; moreover, it has a simple structure, a simple preparation process, low cost, is suitable for large-scale production, and shows great application value in the fields of smart wear and even military camouflage, etc.

[0108] Both the comparative example and Example 1 have a three-layer device structure, consisting of Figure 3It can be seen that the response time of the electrochromic device in Example 1 based on the PEDOT:PSS conductive polymer hydrogel is a coloring time of 0.47 s and a fading time of 0.39 s, while the response time of the electrochromic device in Comparative Example 1 is a coloring time of 2.33 s and a fading time of 0.41 s. This is because directly spraying the PEDOT:PSS conductive polymer on the surface of the hydrogel cannot form a stable thin film, and during the voltage application test, the transmission of electrons through the conjugated π-chain is blocked; the speed of ions entering the electrochromic device becomes slower, and the device response naturally decreases. From Figure 4 and Figure 5 It can be seen that the stability of the electrochromic device based on the PEDOT:PSS conductive polymer hydrogel is as high as 10,000 cycles, while the stability of the electrochromic device based on the PEDOT:PSS conductive polymer is only 400 cycles. The reason for the sharp drop in stability from 10,000 cycles to 400 cycles (such as Figure 6 ), as mentioned above, electrochromism mainly depends on electron conduction and ion transport. For the PEDOT:PSS conductive polymer sprayed on the surface of the hydrogel, there is no very stable electron conduction path and ion transport channel, and during the test, the entry and extraction of ions into and from the electrochromic layer are too slow, resulting in a large number of ions blocking the ion transport channel, and the stability drops sharply.

[0109] The above is the preferred embodiment of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A preparation method of a novel electrochromic device based on a conductive polymer hydrogel, characterized in that, It includes the following steps: 1) Add the electrolyte into deionized water to obtain an electrolyte solution; add polyvinyl alcohol, heat and mix, place the mixed solution in a refrigerator for freezing and then thaw at room temperature; repeat 3 - 5 times to prepare a hydrogel electrolyte layer; 2) Mix the conductive polymer, elastomer and deionized water, grind and homogenize to obtain a conductive polymer ink; perform film-forming treatment at the electrode layer, dry at room temperature, and then perform solvation treatment to obtain a conductive polymer hydrogel electrochromic functional layer; 3) Place the hydrogel electrolyte layer obtained in step 1) on the conductive polymer hydrogel electrochromic functional layer prepared in step 2), and encapsulate it with polydimethylsiloxane (PDMS) to obtain a novel electrochromic device; Among them, in step 1), the electrolyte is any one of lithium perchlorate (LiClO4), LiAsF6, LiBF6, LiPF6 or LiCF3SO3; the concentration of the electrolyte solution is 1 - 10 mol / L; In step 2), the solvation treatment method is to directly drop-coat with a solvent with a concentration of 0.01 - 1 mol / L, and the solvent is any one or more of dimethyl sulfoxide (DMSO), ethylene glycol (EG), N,N-dimethylformamide (DMF), tetrahydrofuran (THF), glycerol, hexitol, ethylene glycol monomethyl ether, diethylene glycol, dimethyl sulfate, erythritol, xylitol, concentrated sulfuric acid (H2SO4), quaternary ammonium salt ionic liquid, lithium chloride (LiCl), sodium chloride (NaCl), potassium chloride (KCl), calcium chloride (CaCl2), magnesium chloride (MgCl2), aluminum chloride (AlCl3), samarium chloride (SmCl2), zirconium chloride (ZrCl4), iron chloride (FeCl3) or copper chloride (CuCl2).

2. The preparation method of the novel electrochromic device based on the conductive polymer hydrogel according to claim 1, characterized in that, In step 1), the concentration of polyvinyl alcohol is 10 wt.% - 20 wt.%.

3. The preparation method of the novel electrochromic device based on the conductive polymer hydrogel according to claim 1, wherein, In step 2), the conductive polymer is any one of polyaniline (PANI), poly(3,4-ethylenedioxythiophene) (PEDOT), polypyrrole (PPy), poly(3-methylthiophene) (P3HT) or poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS).

4. The preparation method of the novel electrochromic device based on a conductive polymer hydrogel according to claim 1, characterized in that, In step 2), the elastomer is one or more of polyurethane (PU), polyvinyl alcohol (PVA) or polyacrylamide (PAAm).

5. The preparation method of the novel electrochromic device based on the conductive polymer hydrogel according to claim 1, characterized in that, In step 2), the mass ratio of the conductive polymer to the elastomer is 1:1 - 1:5; the mass concentration of the conductive polymer ink is 3 wt.% - 8 wt.%.

6. The preparation method of the novel electrochromic device based on the conductive polymer hydrogel according to claim 1, wherein, In step 2), the electrode layer is any one of indium tin oxide transparent conductive glass (ITO-glass), indium tin oxide transparent conductive polyethylene terephthalate (ITO-PET), fluorine-doped tin oxide transparent conductive glass (FTO-glass), fluorine-doped tin oxide transparent conductive polyethylene terephthalate (FTO-PET), AgNWs / PDMS, AgNWs / PU, AgNWs / SEBS, AuNWs / PDMS, AuNWs / PU, AuNWs / SEBS, Ag-AuNWs / PDMS, Ag-AuNWs / PU, Ag-AuNWs / SEBS, SWCNT / PDMS, SWCNT / PU, SWCNT / SEBS, PEDOT:PSS / PDMS, PEDOT:PSS / PU, PEDOT:PSS / SEBS, AgNWs / PEDOT:PSS / PDMS, AgNWs / PEDOT:PSS / PU or AgNWs / PEDOT:PSS / SEBS.

7. The preparation method of the novel electrochromic device based on the conductive polymer hydrogel according to claim 1, characterized in that In step 2), the film-forming treatment method is spin coating, inkjet printing, screen printing and 3D printing; the room temperature drying time is 24 - 48 h.

8. The preparation method of the novel electrochromic device based on the conductive polymer hydrogel according to any one of claims 1-7, characterized in that, In step 1), the heating condition is 60 - 90 °C; the freezing condition is -20 °C for 8 h and thawing at room temperature for 4 h.

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