Nickel-DHBQ coordination polymer electrochromic film and preparation method and application thereof
The preparation of nickel-DHBQ coordination polymer electrochromic films has overcome the limitations of inorganic and organic electrochromic materials, realizing electrochromic films with high response speed, multiple color changes and high stability, which are suitable for smart glass windows, automotive anti-glare rearview mirrors, anti-counterfeiting labels and wearable devices.
Patent Information
- Application Number
- CN202511160083.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-08-19
- Publication Date
- 2025-11-25
AI Technical Summary
Existing inorganic electrochromic materials have slow response speed, low coloring efficiency, and high preparation cost, limiting their flexible applications; organic electrochromic materials have poor environmental stability and short cycle life.
A method for preparing nickel-DHBQ coordination polymer electrochromic films was adopted, which involves growing nickel salt and 2,5-dihydroxy-1,4-benzoquinone solution on a conductive substrate to form a coordination polymer film with a nanoscale porous structure.
It achieves high optical contrast, excellent cycle stability, and multi-color changing effects, making it suitable for fields such as smart displays and energy-saving buildings.
Smart Images
Figure CN121005933A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of electrochromic materials technology, and in particular to a nickel-DHBQ coordination polymer electrochromic thin film, its preparation method, and its application. Background Technology
[0002] Electrochromic materials, as an important class of smart materials, have a history of development dating back to the 1960s. These materials can undergo reversible changes in their optical properties under the influence of an applied electric field, including alterations in parameters such as color, transmittance, and reflectivity. This unique property makes them highly promising for applications in fields such as smart windows, anti-glare rearview mirrors, and electronic displays. After more than half a century of development, electrochromic materials have formed a relatively complete system, mainly including three categories: inorganic materials, organic materials, and organic-inorganic hybrid materials.
[0003] Inorganic electrochromic materials were among the earliest studied and applied, with transition metal oxides being the most representative. Cathode coloring materials such as tungsten trioxide (WO3) and molybdenum oxide (MoO3), and anodic coloring materials such as nickel oxide (NiO) and iridium oxide (IrO2), have attracted considerable attention due to their excellent chemical stability and long cycle life (typically reaching 10⁴–10⁵ cycles). However, these materials generally suffer from slow response speeds (coloring / fading times are typically on the order of tens of seconds) and low coloring efficiency (generally less than 50 cm⁻¹). 2 The inorganic electrochromic materials also suffer from limitations such as limited color options and high temperatures. Furthermore, most inorganic electrochromic materials require high-temperature or vacuum conditions for preparation, which not only increases production costs but also restricts their application in flexible devices. The development of organic electrochromic materials offers a new approach to solving these problems. These materials mainly include viologen compounds, conductive polymers (such as polyaniline and polythiophene), and organometallic complexes. Compared to inorganic materials, organic materials offer advantages such as rich colors, fast response speeds (down to sub-second levels), and highly designable molecular structures. In particular, organic materials can often be processed using solution methods, which significantly reduces preparation costs and improves compatibility with flexible substrates. However, organic materials also face challenges such as poor environmental stability (susceptibility to light, heat, oxygen, etc.) and short cycle life (typically less than 10³ cycles).
[0004] To overcome the limitations of single materials, researchers have recently begun to focus on organic-inorganic hybrid electrochromic materials. These materials attempt to combine the advantages of inorganic and organic components, achieving performance breakthroughs through synergistic effects between the components. Among them, metal-organic frameworks (MOFs) and coordination polymers (CPs) have attracted widespread attention due to their tunable pore structures and abundant redox active centers.
[0005] Quinones exhibit exceptional coordination chemistry due to their unique π-conjugated system and electron-rich properties (possessing both carbonyl and hydroxyl functional groups). These molecules can be used to construct well-structured metal-organic coordination polymer materials through the coordination of their rigid conjugated framework with transition metal ions. Of particular note are the three significant advantages exhibited by these materials: (1) excellent electrochemical reversibility; (2) broad-spectrum optical modulation capability; and (3) unique open-pore structure. This provides new ideas for the design of next-generation high-performance electrochromic materials. Summary of the Invention
[0006] To address the aforementioned problems, this invention provides a nickel-DHBQ coordination polymer electrochromic thin film, its preparation method, and its application.
[0007] To achieve the above-mentioned objectives, the present invention provides the following technical solution:
[0008] This invention provides a method for preparing a nickel-DHBQ coordination polymer electrochromic thin film, comprising the following steps:
[0009] A nickel-DHBQ coordination polymer electrochromic film was obtained by mixing a conductive substrate, a nickel salt solution and a 2,5-dihydroxy-1,4-benzoquinone solution and then carrying out a growth reaction.
[0010] The volume ratio of the nickel salt solution to the 2,5-dihydroxy-1,4-benzoquinone solution is 1-3:1-3;
[0011] The growth reaction is carried out at a temperature of 20–30°C for 3–8 hours.
[0012] Furthermore, the concentration of the nickel salt solution is 0.5–2 mol / L, and the concentration of the 2,5-dihydroxy-1,4-benzoquinone solution is 0.01–0.1 mol / L.
[0013] Furthermore, the nickel salt includes at least one of nickel nitrate, nickel sulfate, nickel chloride, and nickel acetate.
[0014] Furthermore, the conductive substrate includes a fluorine-doped tin oxide substrate.
[0015] Furthermore, it also includes a pretreatment step for the conductive substrate, the pretreatment step being:
[0016] The conductive substrate was washed sequentially with deionized water, ethanol, and acetone for 10–15 minutes each, and then dried at 60–80°C.
[0017] Furthermore, prior to the growth reaction, the non-conductive side of the conductive substrate is covered with tape, and the conductive substrate is placed vertically.
[0018] Furthermore, after the growth reaction is complete, the tape covering the non-conductive side of the conductive substrate is removed, and the surface of the reaction product is ultrasonically cleaned for 10-15 minutes each with anhydrous ethanol and deionized water.
[0019] Furthermore, the tape is a polyimide tape.
[0020] This invention provides a nickel-DHBQ coordination polymer electrochromic film prepared by the above-mentioned method for preparing nickel-DHBQ coordination polymer electrochromic films.
[0021] The present invention also provides the application of the above-mentioned nickel-DHBQ coordination polymer electrochromic film in the preparation of electrochromic materials or devices, the devices including smart glass windows, automotive anti-glare rearview mirrors, anti-counterfeiting labels or wearable devices.
[0022] As can be seen from the above technical solution, compared with the prior art, the beneficial effects of the present invention are as follows:
[0023] First, the fabrication process of this electrochromic film is simple, and high-quality films can be obtained without complex equipment. Second, it exhibits high optical contrast and excellent cycling stability. Finally, multi-color changing effects can be achieved by adjusting the coordination environment. These characteristics make it valuable for applications in fields such as smart displays and energy-efficient buildings. Attached Figure Description
[0024] Figure 1 The images show the color changes of the nickel-DHBQ coordination polymer electrochromic film prepared in Example 1 under colored and faded states.
[0025] Figure 2 The cyclic voltammetric characteristic curve of the nickel-DHBQ coordination polymer electrochromic thin film prepared in Example 1 is shown.
[0026] Figure 3 The images show the optical contrast (ΔT) of the nickel-DHBQ coordination polymer electrochromic film prepared in Example 1 under different states, reflecting its ability to modulate light.
[0027] Figure 4 The image shows the response time of the nickel-DHBQ coordination polymer electrochromic film prepared in Example 1.
[0028] Figure 5 This is an in-situ transmittance response image of the nickel-DHBQ coordination polymer electrochromic film prepared in Example 1;
[0029] Figure 6 The image shows the current density change of the nickel-DHBQ coordination polymer electrochromic film prepared in Example 1.
[0030] Figure 7 The image shows the relationship between the optical density change (ΔOD) and charge density of the nickel-DHBQ coordination polymer electrochromic thin film prepared in Example 1. Detailed Implementation
[0031] This invention provides a method for preparing a nickel-DHBQ coordination polymer electrochromic thin film, comprising the following steps:
[0032] A nickel-DHBQ coordination polymer electrochromic film was obtained by mixing a conductive substrate, a nickel salt solution, and a 2,5-dihydroxy-1,4-benzoquinone solution and then carrying out a growth reaction.
[0033] In this invention, the volume ratio of the nickel salt solution to the 2,5-dihydroxy-1,4-benzoquinone solution is 1-3:1-3, preferably 1:1.
[0034] In this invention, the temperature of the growth reaction is 20-30°C, preferably 22-28°C, and more preferably 24-26°C; the time of the growth reaction is 3-8 hours, preferably 4-6 hours, and more preferably 5 hours.
[0035] In this invention, the concentration of the nickel salt solution is 0.5–2 mol / L, preferably 1 mol / L; the concentration of the 2,5-dihydroxy-1,4-benzoquinone solution is 0.01–0.1 mol / L, preferably 0.05 mol / L.
[0036] In this invention, the nickel salt includes at least one of nickel nitrate, nickel sulfate, nickel chloride, and nickel acetate.
[0037] In this invention, the conductive substrate includes a fluorine-doped tin oxide substrate, which is an FTO conductive glass, preferably 2cm × 5cm in size.
[0038] In this invention, a pretreatment step for the conductive substrate is also included, wherein the pretreatment step is as follows:
[0039] The conductive substrate was washed sequentially with deionized water, ethanol, and acetone for 10–15 minutes each, and then dried at 60–80°C.
[0040] In this invention, before the growth reaction, the non-conductive side of the conductive substrate is covered with tape, and the conductive substrate is placed vertically.
[0041] In this invention, after the growth reaction is completed, the tape covering the non-conductive side of the conductive substrate is removed, and the surface of the reaction product is ultrasonically cleaned for 10-15 minutes each with anhydrous ethanol and deionized water.
[0042] In this invention, the tape is a polyimide tape.
[0043] This invention develops a high-performance coordination polymer thin film preparation process by precisely controlling the coordination environment between nickel ions and 2,5-dihydroxy-1,4-benzoquinone. In this coordination polymer, DHBQ (2,5-dihydroxy-1,4-benzoquinone) molecules form a stable coordination bond network with nickel ions through their hydroxyl and carbonyl groups, constructing a periodic framework with a nanoscale porous structure. This unique coordination structure not only ensures the high stability of the material, but its open porous system also facilitates the rapid migration of electrolyte ions, thereby significantly improving charge transport efficiency.
[0044] This invention provides a nickel-DHBQ coordination polymer electrochromic film prepared by the above-mentioned method for preparing nickel-DHBQ coordination polymer electrochromic films. The film uses 2,5-dihydroxy-1,4-benzoquinone, which has significant redox properties, as an organic ligand, and forms a stable polymer network structure with transition metal nickel ions through coordination. This unique molecular design enables the material to possess both excellent electrochemical activity and structural stability.
[0045] The present invention also provides the application of the above-mentioned nickel-DHBQ coordination polymer electrochromic film in the preparation of electrochromic materials or devices, the devices including smart glass windows, automotive anti-glare rearview mirrors, anti-counterfeiting labels or wearable devices.
[0046] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.
[0047] Example 1
[0048] Prepare a 2cm×5cm FTO conductive glass and sonicate it in deionized water, ethanol and acetone solutions for 15 minutes in sequence. Then dry the FTO conductive glass in an oven at 60℃ for later use. Cover the non-conductive side with polyimide tape and support the FTO glass vertically on the inner wall of the reaction vessel, which is a 50mL beaker.
[0049] Weigh 0.2336 g of nickel chloride hexahydrate using an electronic balance, then dissolve it in 10 mL of deionized water to form a 0.1 mol / L nickel chloride hexahydrate solution. Stir the solution continuously at 500 rpm for 10 minutes on a magnetic stirrer until it is fully mixed. The nickel chloride hexahydrate solution will appear pale blue. Pour the solution into a beaker.
[0050] Weigh 0.0705 g of 2,5-dihydroxy-1,4-benzoquinone using an electronic balance, then dissolve it in 10 mL of deionized water to form a 0.05 mol / L 2,5-dihydroxy-1,4-benzoquinone solution. Stir the solution continuously at 500 rpm for 10 min on a magnetic stirrer until it is fully mixed. Pour the solution into a beaker. As the organic ligand solution is added, the color of the solution changes from light blue to transparent colorless and then to purplish-red.
[0051] The beaker was placed on a magnetic stirrer and stirred continuously at 500 rpm for the growth reaction. The reaction temperature was 25℃ and the reaction time was 8 hours. After the reaction was completed, the polyimide tape covering the non-conductive surface of the substrate was removed. The film surface was then ultrasonically cleaned with anhydrous ethanol and deionized water for 15 minutes each, and finally, a nickel-DHBQ coordination polymer electrochromic film was obtained.
[0052] Example 2
[0053] Same as Example 1, except that the concentration of the 2,5-dihydroxy-1,4-benzoquinone solution is 0.1 mol / L.
[0054] Example 3
[0055] Same as Example 1, except that the growth reaction time is 6 hours.
[0056] Performance testing
[0057] 1. Film color-changing properties
[0058] The standard three-electrode system was used, wherein the nickel-DHBQ coordination polymer electrochromic film prepared in Example 1 was used as the working electrode, a platinum sheet was used as the counter electrode, an Ag / AgCl electrode was used as the reference electrode, and a 1 mol / L KOH solution was used as the electrolyte.
[0059] Test results are available Figure 1 ,Depend on Figure 1 It can be seen that under a voltage of 0.8V, the nickel-DHBQ coordination polymer electrochromic film undergoes an oxidation reaction. This can be visually observed in digital photographs, where the color changes from light brown to dark black.
[0060] When a voltage of -0.2V is applied, a reduction reaction occurs, and the color changes from dark black to light brown, exhibiting good reversible electrochromic properties.
[0061] 2. Electrochemical performance
[0062] Electrochemical testing employed a three-electrode system, using a silver wire electrode as the reference electrode, a platinum wire electrode as the counter electrode, and the nickel-DHBQ coordination polymer electrochromic film prepared in Example 1 as the working electrode. A 1 mol / L KOH solution was used as the electrolyte. Cyclic voltammetry (CV) was employed, with a scan rate of 0.02 V / s, performing cyclic scans within the potential range of -0.2 V to 0.8 V. The test results are shown below. Figure 2 .
[0063] Depend on Figure 2 The nickel-DHBQ coordination polymer electrochromic film exhibits excellent electrochemical performance: at a scan rate of 20 mV / s, the material displays quasi-reversible redox characteristics with two redox peaks. Furthermore, it achieves a high electrochemical conductivity of up to 2.5 mA / cm². 2 The peak current density indicates that the material has abundant electroactive sites, while the narrow peak width and significant integral area reflect the rapid charge transfer kinetics and efficient charge storage capacity, respectively.
[0064] 3. Optical contrast image
[0065] The spectroelectrochemical behavior of the nickel-DHBQ coordination polymer electrochromic thin film prepared in Example 1 was studied using a UV-Vis spectrometer and an electrochromic cycling tester. The results are shown in [Figure 1]. Figure 3 .
[0066] Depend on Figure 3 It was found that, under voltages of -0.2V and 0.8V, the transmittance of the nickel coordination polymer dihydroxybenzoquinone electrochromic film in the 300-800nm UV-Vis range was tested. At -0.2V, the transmittance in the visible light region generally increased with increasing wavelength, exhibiting a fading characteristic; at 0.8V, the transmittance in the visible light region was extremely low, exhibiting a coloring characteristic. At a wavelength of 600nm, the optical contrast ΔT reached 72%, reflecting that the changes in molecular structure during the redox process drastically altered the visible light absorption characteristics, resulting in a high optical modulation range.
[0067] 4. Response time graph
[0068] To evaluate the electrochromic response speed of the thin film, a wavelength of 600 nm was selected as the test condition. The time required for the optical transmittance to change to 72% was defined as the response time. This was used to quantify the coloring and fading characteristics of the nickel-DHBQ coordination polymer electrochromic thin film prepared in Example 1 during the electrochromic process. The test results are shown in [Figure 1]. Figure 4 .
[0069] Depend on Figure 4The coloring response time (tc) and fading response time (tb) of the nickel-DHBQ coordination polymer electrochromic film were found to be 9.6 s and 22.19 s, respectively. Thanks to the relatively fast electrochemical kinetics of the film, rapid redox reactions and ion migrations are achieved, resulting in shorter coloring and fading times.
[0070] 5. In-situ transmittance response image
[0071] Based on optical transmittance measurements at 600 nm wavelength, this study defines the time required for the transmittance change to reach 72% as the response time, which is used to quantitatively characterize the color-changing kinetics of the nickel-DHBQ coordination polymer electrochromic film prepared in Example 1 (test results are shown in [link to test results]). Figure 5 ).like Figure 5 As shown, even when the test time is extended to 700 seconds, the film still maintains stable optical performance: its transmittance decay is negligible, and the response speed does not show a significant decrease. This excellent stability is mainly attributed to the efficient ion migration pathways provided by the material's unique pore structure, and the high redox activity conferred by the synergistic effect of the nickel center and the DHBQ ligand.
[0072] 6. Current density change graph
[0073] Under square-wave excitation at 0.8 V and -0.2 V (vs. Ag line), the nickel-DHBQ coordination polymer electrochromic film exhibits excellent electrochemical reversibility and stability. Figure 6 It can be seen that the material generates approximately 3 mA / cm at 0.8V. 2 Its stable current response is approximately -6 mA / cm² at -0.2V. 2 The current response is excellent, with current density fluctuations of less than 5% during continuous cycling. This highly reversible current response characteristic confirms the superior performance of Ni. 2+ / Ni 3+ The efficient synergistic effect between the DHBQ ligand quinone / hydroquinone redox pair reflects both the material's good structural stability and rapid charge transfer kinetics.
[0074] 7. Graph showing the relationship between optical density change (ΔOD) and charge density.
[0075] according to Figure 7 Test data shows that the Ni-DHBQ thin film achieves a coloration efficiency (CE) of 47.3 cm⁻¹ at a wavelength of 600 nm. 2 ·C -1This value indicates that the material possesses excellent electrochromic properties. Coloring efficiency (CE), a key parameter for evaluating the performance of electrochromic materials, is defined as the change in optical density (ΔOD) caused by a unit change in charge density (ΔQ) during the coloring process. The specific calculation formula is as follows:
[0076] CE(λ)=ΔOD / ΔQ=log(T b / T c ) / ΔQ
[0077] Where λ is the selected wavelength (600 nm) for the maximum ΔT, and T b and T c The transmittance values are those of the nickel-DHBQ coordination polymer electrochromic films in the bleached and colored states, respectively.
[0078] By linearly fitting the relationship curve between ΔOD and ΔQ, the slope was calculated to be the coloring efficiency value of 47.3 cm. 2 ·C -1 This high CE value is mainly attributed to Ni. 2+ Rapid ion transport is facilitated by redox reactions synergistic with DHBQ ligands and the material’s unique porous structure.
[0079] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.
Claims
1. A method for preparing a nickel-DHBQ coordination polymer electrochromic thin film, characterized in that, Includes the following steps: A nickel-DHBQ coordination polymer electrochromic film was obtained by mixing a conductive substrate, a nickel salt solution and a 2,5-dihydroxy-1,4-benzoquinone solution and then carrying out a growth reaction. The volume ratio of the nickel salt solution to the 2,5-dihydroxy-1,4-benzoquinone solution is 1-3:1-3; The growth reaction is carried out at a temperature of 20–30°C for 3–8 hours.
2. The method for preparing the nickel-DHBQ coordination polymer electrochromic thin film according to claim 1, characterized in that, The concentration of the nickel salt solution is 0.5–2 mol / L, and the concentration of the 2,5-dihydroxy-1,4-benzoquinone solution is 0.01–0.1 mol / L.
3. The method for preparing the nickel-DHBQ coordination polymer electrochromic thin film according to claim 2, characterized in that, The nickel salt includes at least one of nickel nitrate, nickel sulfate, nickel chloride, and nickel acetate.
4. The method for preparing the nickel-DHBQ coordination polymer electrochromic thin film according to any one of claims 1 to 3, characterized in that, The conductive substrate includes a fluorine-doped tin oxide substrate.
5. The method for preparing the nickel-DHBQ coordination polymer electrochromic thin film according to claim 4, characterized in that, It also includes a pretreatment step for a conductive substrate, wherein the pretreatment step is as follows: The conductive substrate was washed sequentially with deionized water, ethanol, and acetone for 10–15 minutes each, and then dried at 60–80°C.
6. The method for preparing the nickel-DHBQ coordination polymer electrochromic thin film according to claim 5, characterized in that, Before the growth reaction, cover the non-conductive side of the conductive substrate with tape and place the conductive substrate vertically.
7. The method for preparing the nickel-DHBQ coordination polymer electrochromic thin film according to claim 6, characterized in that, After the growth reaction is complete, remove the tape covering the non-conductive side of the conductive substrate, and then ultrasonically clean the surface of the reaction product for 10-15 minutes each with anhydrous ethanol and deionized water.
8. The method for preparing the nickel-DHBQ coordination polymer electrochromic thin film according to claim 6 or 7, characterized in that, The tape is a polyimide tape.
9. The nickel-DHBQ coordination polymer electrochromic film prepared by the method of any one of claims 1 to 8.
10. The application of the nickel-DHBQ coordination polymer electrochromic thin film according to claim 9 in the preparation of electrochromic materials or devices, characterized in that, The devices include smart glass windows, automotive anti-glare rearview mirrors, anti-counterfeiting labels, or wearable devices.