Flexible black electrochromic device based on color complementation and preparation method thereof
By using a six-layer structure design based on complementary colors and a photocuring system, the problems of insufficient process complexity and stability of existing black electrochromic devices in flexible applications are solved, achieving the effects of simplified structure and improved response speed.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-31
- Publication Date
- 2026-04-03
AI Technical Summary
Existing black electrochromic devices suffer from complex manufacturing processes, poor interlayer interface compatibility, slow response speed, and insufficient cycle stability in flexible applications, making it difficult to meet the needs of flexible wearable devices.
Employing the complementary color principle of orange and blue, and through a six-layer structure design including a PET substrate, an ITO layer, a cathode electrochromic layer, and an electrolyte/anodic electrochromic layer, the device utilizes a photocuring system to reduce small molecule migration and simplify the device structure.
The structure of the flexible black electrochromic device has been simplified, the response speed and cycle stability have been improved, and the application requirements of flexible wearable devices have been met.
Smart Images
Figure CN121785022A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of electrochromic technology, and more specifically, to a flexible black electrochromic device based on color complementarity and its fabrication method. Background Technology
[0002] Electrochromic devices have significant application value in fields such as smart windows, display devices, and wearable electronics because they can dynamically adjust light transmittance. Among them, black electrochromic devices have become a current research hotspot due to their high contrast, strong privacy protection capabilities, and excellent light and heat shielding effects (such as effectively blocking visible light and infrared radiation in smart window applications, reducing building energy consumption).
[0003] Existing methods for achieving black electrochromic properties mainly include the intrinsic black of a single electrochromic material and the superposition of multiple complementary colors (such as red, green, and blue, or yellow and blue). However, complementary color schemes typically require the construction of multiple independently controlled electrochromic layer structures, significantly increasing the complexity of device fabrication. Furthermore, poor interlayer compatibility can lead to delamination and slowed response times, making it difficult to meet the demands of flexible applications. With the rapid development of flexible electronics technology, wearable devices, foldable displays, and other flexible applications place higher demands on the flexibility, portability, and cycle stability of electrochromic devices. Existing rigid black electrochromic devices cannot adapt to bending and folding deformations, while flexible black devices suffer from low color purity, complex structures, or short cycle life. Therefore, there is an urgent need to develop a black electrochromic device based on the principle of complementary colors, with a simple structure and flexible bendability. Summary of the Invention
[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a flexible black electrochromic device based on complementary colors and its preparation method. This invention utilizes the complementary color principle of orange and blue to achieve the preparation of a pure black electrochromic device; by mixing the anodic electrochromic material with the electrolyte solution, the complex structure caused by complementary colors is simplified, while a photocuring system is used to reduce the migration of small molecules.
[0005] To achieve the above objectives, the present invention adopts the following technical solution:
[0006] A flexible black electrochromic device based on complementary colors has a six-layer structure, comprising a first flexible substrate, a first ITO layer, a cathode electrochromic layer, an electrolyte / anodic electrochromic layer, a second ITO layer, and a second flexible substrate stacked sequentially from bottom to top.
[0007] Furthermore, both the first and second flexible substrates are PET, with a thickness of 110-140μm.
[0008] Furthermore, both the first ITO layer and the second ITO layer are prepared using an In2O3-SnO2 ceramic target as the target material, and the thickness of both the first ITO layer and the second ITO layer is 180-220 nm; the mass ratio of In2O3 to SnO2 in the In2O3-SnO2 ceramic target is 90:10.
[0009] Furthermore, the cathode electrochromic layer is made from a PEDOT:PSS solution; the thickness of the cathode electrochromic layer is 100-200 nm.
[0010] Furthermore, the electrolyte layer is formed by curing a mixed solution of electrolyte solution and anodic electrochromic material. The electrolyte solution is made of electrolyte, polymer monomer, photoinitiator, solvent and thickener. The anodic electrochromic material is N,N,N',N'-tetra(p-tolyl)benzidine. The thickness of the electrolyte / anodic electrochromic layer is 50-200 μm.
[0011] Furthermore, the mass ratio of the electrolyte solution to the anodic electrochromic material is 100:(0.1-1); based on 100% of the total mass of the electrolyte solution, the electrolyte accounts for 3 wt% of the total mass of the electrolyte solution, the polymer monomer accounts for 10-15 wt% of the total mass of the electrolyte solution, the photoinitiator accounts for 3-5 wt% of the total mass of the electrolyte solution, the solvent accounts for 65-70 wt% of the total mass of the electrolyte solution, and the balance is a thickener.
[0012] Furthermore, in the electrolyte solution, the electrolyte is lithium bis(trifluoromethanesulfonyl)imide, the polymer monomer is polyethylene glycol diacrylate, the photoinitiator is phenyl bis(2,4,6-trimethylbenzoyl)phosphine oxide, the solvent is a combination of propylene carbonate and N-methylpyrrolidone, the mass ratio of propylene carbonate to N-methylpyrrolidone is (62-67):3, and the tackifier is polymethyl methacrylate.
[0013] A method for fabricating a flexible black electrochromic device based on color complementarity includes the following steps:
[0014] (a) Using an In2O3-SnO2 ceramic target as the target material, a first ITO layer is formed by sputtering on a first flexible substrate and a second ITO layer is formed on the surface of a second flexible substrate by magnetron sputtering.
[0015] (b) The PEDOT:PSS solution is coated onto the surface of the first ITO layer by scraping, and after drying, a cathodic electrochromic layer is formed;
[0016] (c) Mix electrolyte, polymer monomer, photoinitiator, solvent and thickener to prepare electrolyte solution; add anodic electrochromic material to electrolyte solution and stir evenly to obtain electrolyte / anodic electrochromic material mixed solution;
[0017] (d) A flexible black electrochromic device is prepared by curing a mixed solution of electrolyte / anodic electrochromic material into an electrolyte / anodic electrochromic layer through a roll-to-roll process and an ultraviolet curing process.
[0018] Furthermore, in step (a), the magnetron sputtering process conditions are: vacuum level controlled at 1.0 × 10⁻⁶. -4 -5.0×10 - 3 Pa, the heating temperature of the PET substrate is 25-50℃, and the sputtering power is 80-180W.
[0019] Furthermore, in step (d), the roll-to-roll speed is controlled at 0.1-1 m / min, and the UV lamp power is 60-200 W / cm. 2 The photocuring time is 15-60 seconds.
[0020] The beneficial effects of this invention are:
[0021] This invention uses poly(3,4-ethylenedioxythiophene) as the cathode electrochromic material, which appears blue, and N,N,N',N'-tetra(p-tolyl)benzidine as the anode electrochromic material, which appears orange. The electrochromic device changes from transparent to black through the complementarity of the two colors. At the same time, N,N,N',N'-tetra(p-tolyl)benzidine is mixed in the electrolyte solution system to simplify the device structure and reduce the complexity of the process. The introduced photocuring system can also effectively fix N,N,N',N'-tetra(p-tolyl)benzidine in the electrolyte layer (4) to avoid the loss of device cycle stability due to small molecule migration. Attached Figure Description
[0022] Figure 1 This is a schematic diagram of the structure of the black electrochromic device of the present invention;
[0023] Figure 2 This is a comparison diagram of the color changes of the black electrochromic device in Example 1 under different voltages;
[0024] Figure 3 This is a comparison chart of the transmittance changes of the black electrochromic device in Example 1 under the conditions of 0V and wavelength 400-1000nm and 2.0V and wavelength 400-1000nm.
[0025] Figure 4 This is a comparison of the cycling stability of the black electrochromic device in Example 1 at 0V, 2.0V cycling voltages and a wavelength of 550nm.
[0026] Figure 5 This is a bending diagram of the black electrochromic device in Example 1.
[0027] In the figure: First flexible substrate 1, first ITO layer 2, cathode electrochromic layer 3, electrolyte / anodic electrochromic layer 4, second ITO layer 5, and second flexible substrate 6. Detailed Implementation
[0028] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0029] The present invention is based on a color-complementary flexible black electrochromic device, which consists of, from bottom to top, a first flexible substrate 1, a first ITO layer 2, a cathode electrochromic layer 3, an electrolyte / anodic electrochromic layer 4, a second ITO layer 5, and a second flexible substrate 6 stacked together.
[0030] Both the first flexible substrate 1 and the second flexible substrate 6 are PET, with a thickness of 110-140μm.
[0031] The first ITO layer 2 and the second ITO layer 5 are both prepared using an In2O3-SnO2 ceramic target as the target material. The thickness of the first ITO layer 2 and the second ITO layer 5 is 180-220 nm. The mass ratio of In2O3 to SnO2 in the In2O3-SnO2 ceramic target is 90:10.
[0032] The cathode electrochromic layer 3 is made from PEDOT:PSS solution; the thickness of the cathode electrochromic layer 3 is 100-200nm.
[0033] The electrolyte layer 4 is formed by curing a mixed solution of electrolyte solution and anodic electrochromic material, with a mass ratio of electrolyte solution to anodic electrochromic material of 100:(0.1-1); the anodic electrochromic material is preferably N,N,N',N'-tetra(p-tolyl)benzidine; the thickness of the electrolyte / anodic electrochromic layer 4 is 50-200 μm. The electrolyte solution is made of an electrolyte (preferably lithium bis(trifluoromethanesulfonyl)imide), a polymer monomer (preferably polyethylene glycol diacrylate), a photoinitiator (preferably phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide), a solvent (preferably a composition of propylene carbonate and N-methylpyrrolidone, with a mass ratio of propylene carbonate to N-methylpyrrolidone of (62-67):3), and a tackifier (preferably polymethyl methacrylate); based on 100% of the total mass of the electrolyte solution, the electrolyte accounts for 3 wt% of the total mass of the electrolyte solution, the polymer monomer accounts for 10-15 wt% of the total mass of the electrolyte solution, the photoinitiator accounts for 3-5 wt% of the total mass of the electrolyte solution, the solvent accounts for 65-70 wt% of the total mass of the electrolyte solution, and the balance is a tackifier.
[0034] This flexible black electrochromic device based on color complementarity is fabricated using the following method:
[0035] (a) Using an In2O3-SnO2 ceramic target as the target material, a first ITO layer 2 was formed by sputtering on a first flexible substrate 1 and a second ITO layer 5 was formed on the surface of a second flexible substrate 6 by magnetron sputtering. The magnetron sputtering process conditions were as follows: the vacuum degree was controlled at 1.0 × 10⁻⁶. -4 -5.0×10 -3 Pa, the heating temperature of the PET substrate is 25-50℃, and the sputtering power is 80-180W.
[0036] (b) The PEDOT:PSS solution is coated onto the surface of the first ITO layer 2 by scraping, and after drying, a cathodic electrochromic layer 3 is formed; the scraping speed is 0.5-5 m / min, and the drying temperature is 100-160℃.
[0037] (c) Mix electrolyte, polymer monomer, photoinitiator, solvent and thickener to prepare electrolyte solution; add anodic electrochromic material to electrolyte solution and stir evenly to obtain electrolyte / anodic electrochromic material mixed solution.
[0038] (d) A flexible black electrochromic device is prepared by curing a mixed solution of electrolyte / anodic electrochromic material into an electrolyte / anodic electrochromic layer 4 using a roll-to-roll process and ultraviolet curing. The roll-to-roll speed is controlled at 0.1-1 m / min, and the ultraviolet lamp power is 60-200 W / cm. 2 The photocuring time is 15-60 seconds.
[0039] The preferred embodiment is as follows:
[0040] Example 1
[0041] Step (a): After cleaning, the first flexible substrate 1 and the second flexible substrate 6 are laid flat on the carrier in the magnetron sputtering equipment (both the first flexible substrate 1 and the second flexible substrate 6 are PET, and both are 125 μm thick). An In2O3-SnO2 ceramic target (In2O3 to SnO2 mass ratio of 90:10) is used as the target material. The two substrates are preheated to 35°C and evacuated to a vacuum of 1.0 × 10⁻⁶. -4 Pa, with a sputtering power of 100W, a first ITO layer 2 and a second ITO layer 5 of 200nm are sputtered on the surfaces of two substrates respectively, to obtain a composite film A of the first flexible substrate 1 / first ITO layer 2 and a composite film B of the second flexible substrate 6 / second ITO layer 5.
[0042] Step (b): Fix the combined film A on the doctor blade coater (with the first ITO layer 2 facing upwards), take a PEDOT:PSS solution (purchased from Shanghai Jingnian Chemical Co., Ltd., Clevios PH1000) and pour it onto one side of the surface of the first ITO layer 2. Adjust the doctor blade height to control the wet film height at 150 μm, and coat the PEDOT:PSS solution evenly on the surface of the first ITO layer 2 at a doctor blade coating speed of 0.5 m / min. Transfer it to an oven at 120°C for drying to form a PEDOT layer with a thickness of 150 nm (i.e., the cathode electrochromic layer 3), and obtain the combined film C of the first flexible substrate 1 / first ITO layer 2 / PEDOT layer.
[0043] Step (c): Lithium bis(trifluoromethanesulfonyl)imide (purchased from Anaiji, item number W830445), polyethylene glycol diacrylate (purchased from Maclean, item number P816111), phenyl bis(2,4,6-trimethylbenzoyl)phosphine oxide (purchased from Aladdin, item number P138333), a combined solvent of propylene carbonate and N-methylpyrrolidone (propylene carbonate purchased from Aladdin, item number P105723; N-methylpyrrolidone purchased from Aladdin, item number M100588), and polymethyl methacrylate (purchased from Taicang Kaida Plastic Raw Materials Co., Ltd., item number 2018045679) are uniformly stirred and mixed to obtain the electrolyte. The solution (in the electrolyte solution, lithium bis(trifluoromethanesulfonyl)imide accounts for 3 wt%, polyethylene glycol diacrylate accounts for 15 wt%, phenyl bis(2,4,6-trimethylbenzoyl)phosphine oxide accounts for 3 wt%, solvent accounts for 68 wt%, propylene carbonate to N-methylpyrrolidone mass ratio is 65:3, and polymethyl methacrylate accounts for 11%); anodic electrochromic material N,N,N',N'-tetra(p-tolyl)benzidine (purchased from Aladdin, product number N159575, electrolyte solution to anodic electrochromic material mass ratio 100:0.5) was added to the electrolyte solution and heated and stirred until homogeneous to obtain an electrolyte / anodic electrochromic material mixed solution.
[0044] Step (d): Fix composite membrane C and composite membrane B (PEDOT layer and second ITO layer 5 placed opposite each other) on a roll-to-roll device. Adjust the slit width between composite membrane C and composite membrane B to 100 μm. Pour the electrolyte / anodic electrochromic material mixed solution into the slit. Start the roll-to-roll device and uniformly fill the mixed solution between composite membrane C and composite membrane B at a speed of 0.3 m / min. Then, at 80 W / cm 2 A flexible electrochromic device can be obtained by curing under a UV lamp for 30 seconds. The electrolyte / anodic electrochromic material mixed solution is cured to form an electrolyte / anodic electrochromic layer 4.
[0045] When a voltage is applied to the two electrodes of the black electrochromic device obtained in Example 1, the color change of the device under different voltages is as follows: Figure 2 As shown, it appears transparent at 0V; when the voltage rises to 2V, the device appears pure black.
[0046] The transmittance variation and cycle stability of the device were characterized by a UV-Vis spectrometer and a transmittance meter: (1) An external power supply was connected to both sides of the device, with the first ITO layer 2 connected to the negative electrode and the second ITO layer 5 connected to the positive electrode. The device was placed in a UV-Vis spectrometer, and transmittance spectral data under 0 V and 2.0 V conditions were measured at a scan rate of 0.5 nm, and the transmittance spectral data were obtained. Figure 3(2) An electrochromic cycling device was used as the external power supply, with the cycling voltages set to 2.0 V and -2.0 V, and the power-on duration for both being 30 seconds. After a certain number of cycles, the transmittance data under the two voltages were recorded using a transmittance meter and plotted. Figure 4 Test data shows that at 0V, the device's T-value (transmittance) is 45%, appearing transparent; at 2V, the device is colored, with a T-value of 1%, appearing black, and ΔT of 44%. The device can be stably cycled 300 times at 0V and 2V, demonstrating good cycle stability.
[0047] Example 1: Bending diagram of the black electrochromic device as shown in Figure 1 Figure 5 As shown, the device exhibits good flexibility.
[0048] Comparative Example 1
[0049] The electrochromic device was prepared according to Example 1, except that the TPB-4Me / NMP solution and the electrolyte solution were mixed at a mass ratio of 1:2 to form a mixed solution, which was then used to replace the electrolyte / anodic electrochromic material mixed solution in Example 1 by equal mass. The TPB-4Me / NMP solution was prepared by adding 2.72 g of TPB-4Me to 50 mL of NMP solution and stirring thoroughly at 500 rpm to dissolve the TPB-4Me, resulting in a 0.1 mol / L TPB-4Me / NMP solution.
[0050] At 80W / cm 2 The electrochromic device of Comparative Example 1 was prepared by photocuring under ultraviolet light. The transmittance changes and cycling stability of the devices of Example 1 and Comparative Example 1 at -2V, 2.0V cycling voltages and a wavelength of 550nm were tested according to the test method of Example 1. Detailed data are shown in the table below:
[0051]
[0052] Numerical results show that the device in Comparative Example 1 has a higher transmittance contrast, but due to its small molecular structure, it has poor stability, resulting in a significantly lower number of cycles compared to Example 1. This indicates that the preparation method has both better stability and contrast.
[0053] The above description is merely a preferred embodiment of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principles of the present invention should also be considered within the scope of protection of the present invention.
Claims
1. A flexible black electrochromic device based on complementary colors, characterized in that, The device has a six-layer structure, including a first flexible substrate (1), a first ITO layer (2), a cathode electrochromic layer (3), an electrolyte / anodic electrochromic layer (4), a second ITO layer (5), and a second flexible substrate (6) stacked sequentially from bottom to top.
2. The flexible black electrochromic device based on color complementarity according to claim 1, characterized in that, The first flexible substrate (1) and the second flexible substrate (6) are both PET, with a thickness of 110-140μm.
3. The flexible black electrochromic device based on color complementarity according to claim 1, characterized in that, The first ITO layer (2) and the second ITO layer (5) are both prepared using an In2O3-SnO2 ceramic target as the target material. The thickness of the first ITO layer (2) and the second ITO layer (5) is 180-220 nm. The mass ratio of In2O3 to SnO2 in the In2O3-SnO2 ceramic target is 90:
10.
4. The flexible black electrochromic device based on color complementarity according to claim 1, characterized in that, The cathode electrochromic layer (3) is made from PEDOT:PSS solution; the thickness of the cathode electrochromic layer (3) is 100-200nm.
5. The flexible black electrochromic device based on complementary colors according to claim 1, characterized in that, The electrolyte layer (4) is formed by curing a mixture of electrolyte solution and anodic electrochromic material. The electrolyte solution is made of electrolyte, polymer monomer, photoinitiator, solvent and tackifier. The anodic electrochromic material is N,N,N',N'-tetra(p-tolyl)benzidine. The thickness of the electrolyte / anodic electrochromic layer (4) is 50-200 μm.
6. The flexible black electrochromic device based on complementary colors according to claim 5, characterized in that, The mass ratio of electrolyte solution to anodic electrochromic material is 100:(0.1-1); based on 100% of the total mass of electrolyte solution, the electrolyte accounts for 3wt% of the total mass of electrolyte solution, the polymer monomer accounts for 10-15wt% of the total mass of electrolyte solution, the photoinitiator accounts for 3-5wt% of the total mass of electrolyte solution, the solvent accounts for 65-70wt% of the total mass of electrolyte solution, and the balance is a thickener.
7. The flexible black electrochromic device based on complementary colors according to claim 6, characterized in that, In the electrolyte solution, the electrolyte is lithium bis(trifluoromethanesulfonyl)imide, the polymer monomer is polyethylene glycol diacrylate, the photoinitiator is phenyl bis(2,4,6-trimethylbenzoyl)phosphine oxide, the solvent is a combination of propylene carbonate and N-methylpyrrolidone, the mass ratio of propylene carbonate to N-methylpyrrolidone is (62-67):3, and the tackifier is polymethyl methacrylate.
8. A method for fabricating a flexible black electrochromic device based on color complementarity according to any one of claims 1-7, characterized in that, Includes the following steps: (a) Using an In2O3-SnO2 ceramic target as the target material, a first ITO layer (2) is sputtered on the first flexible substrate (1) and a second ITO layer (5) is sputtered on the surface of the second flexible substrate (6) by magnetron sputtering process. (b) The PEDOT:PSS solution was coated onto the surface of the first ITO layer (2) by scraping, and after drying, a cathodic electrochromic layer (3) was formed. (c) Mix electrolyte, polymer monomer, photoinitiator, solvent and thickener to prepare electrolyte solution; add anodic electrochromic material to electrolyte solution and stir evenly to obtain electrolyte / anodic electrochromic material mixed solution; (d) The electrolyte / anodic electrochromic material mixture solution is cured by roll-to-roll process and ultraviolet curing process to form electrolyte / anodic electrochromic layer (4), and a flexible black electrochromic device is obtained.
9. The method for fabricating a flexible black electrochromic device based on color complementarity according to claim 8, characterized in that, In step (a), the magnetron sputtering process conditions are: vacuum level controlled at 1.0 × 10⁻⁶. -4 -5.0×10 -3 Pa, the heating temperature of the PET substrate is 25-50℃, and the sputtering power is 80-180W.
10. The method for fabricating a flexible black electrochromic device based on color complementarity according to claim 8, characterized in that, In step (d), the roll-to-roll speed is controlled at 0.1-1 m / min, and the UV lamp power is 60-200 W / cm. 2 The photocuring time is 15-60 seconds.