CN114716155A - Preparation method of thin film electrode for electrochromic device, thin film electrode and application - Google Patents

Abstract

The invention provides a preparation method for a thin film electrode of an electrochromic device, the thin film electrode and application, wherein pure nickel oxide is prepared mainly through a sol-gel method, modification test is carried out on nickel oxide base through component doping, process parameter regulation and control and different preparation methods, the optimal doping proportion is estimated through a theoretical method of lattice substitution and density functional, and finally the nickel oxide base anode coloring thin film with high electrochromic efficiency, high response speed and good cycle stability is obtained, and the electrochromic device with multiple application scenes can be assembled through designing a multilayer all-solid-state structure.

Description

Preparation method, thin film electrode and use of thin film electrode for electrochromic device

technical field

The present invention relates to the field of electrochromic devices and nano-synthesis, in particular to a preparation method for electrochromic device thin-film electrodes, thin-film electrodes and uses thereof.

Background technique

Under the urgent need of building energy-saving, various energy-saving glass began to flourish, such as low-emissivity coated glass, insulating glass and sunlight control glass. However, the adjustment of light intensity of glass of these materials is constant, that is, it cannot change with environmental factors such as season and climate. Therefore, a glass with controllable transmittance has become the focus of research. Electrochromism provides a new solution to this problem.

The most important property of electrochromism is the reversible change of optical properties (transmittance, reflectance, absorption) under the action of a small electrical signal. Devices based on electrochromic assembly are called electrochromic devices. Electrochromic and electrochromic devices have the ability to transmit, reflect and absorb visible light and solar radiation. As a specific product application of electrochromic devices, electrochromic smart windows can adjust the visible light intensity, which accounts for nearly half of solar energy, and at the same time change the color of the window to increase the aesthetics of the building.

Generally, the encapsulation structure of the electrochromic device sequentially includes: a first transparent conductive layer, an anode electrochromic layer, an electrolyte layer, a cathode electrochromic layer, and a second transparent conductive layer. Among them, the electrochromic layer is the core part of the whole device. In recent years, the research on electrochromic layers has significantly improved the electrochromic properties. However, due to the small control range of the solar spectral transmittance and insufficient interfacial mass transfer efficiency, the coloring efficiency is still low in practical applications. , slow response speed and poor cycle stability.

SUMMARY OF THE INVENTION

In order to solve at least one problem existing in the above-mentioned prior art, the present invention provides a preparation method for electrochromic device thin-film electrode, thin-film electrode and application thereof, which firstly prepares pure nickel oxide by sol-gel method, The nickel oxide base was modified and tested by different doping, process parameter control and different preparation methods, and the optimal doping ratio was predicted by the theoretical method of lattice substitution and density functional, and finally high electrochromic efficiency was obtained. , nickel oxide-based anodic coloring films with fast response speed and good cycle stability, and electrochromic devices with multiple application scenarios can be assembled by designing a multi-layer all-solid-state structure.

The present invention adopts the following technical solutions on the one hand for realizing the purpose of the invention:

A preparation method for electrochromic device thin-film electrodes, using nickel acetate as a nickel source, using cobalt acetate as a cobalt source, using a sol-gel method to prepare a cobalt ion-doped nickel oxide mixed solution; using a spin coating method , smear the cobalt ion-doped nickel oxide mixed solution on the surface of the ITO conductive glass to make a cobalt ion-doped nickel oxide thin film electrode diaphragm; the ITO conductive glass is clean ITO conductive glass; the cobalt ion-doped nickel oxide The thin film electrode is annealed to obtain the cobalt ion-doped nickel oxide thin film electrode.

Further, the preparation method specifically comprises the following steps:

Add a preset amount of nickel acetate and a preset amount of ethanolamine to an appropriate amount of ethylene glycol methyl ether; according to the preset doping ratio, add a preset amount of cobalt acetate, and stir at a constant temperature until the stirring is uniform to prepare The cobalt ion-doped nickel oxide mixed solution was formed into the cobalt ion-doped nickel oxide mixed solution; after the cobalt ion-doped nickel oxide mixed solution was placed in a dark place for 24 hours, the cobalt ion-doped nickel oxide mixed solution was spin-coated on the surface of the clean ITO conductive glass , to make the cobalt ion doped nickel oxide thin film electrode; the cobalt ion doped nickel oxide thin film electrode is placed in a muffle furnace for annealing treatment.

Further, the molar ratio of the nickel acetate to the ethanolamine is 1:1.

Further, according to the preset film thickness requirement, the surface of the ITO conductive glass is repeatedly spin-coated by a spin coater, and is placed in an oven for drying after each spin-coating layer.

Further, the method for obtaining the clean ITO conductive glass includes: sequentially using deionized water, acetone and anhydrous ethanol to clean the ITO conductive glass.

Further, the constant-temperature stirring method includes: stirring with a magnetic stirrer, the temperature of the magnetic stirrer is set to be between 60°C and 85°C, and the stirring time is set to 2 hours.

Further, the temperature of the oven is set to 100°C-120°C, and the drying time of each spin-coated layer is set to 5 minutes.

Further, the annealing temperature of the muffle furnace is set to 380°C-450°C, and the annealing time is set to 2 hours.

On the other hand, the present invention also discloses the thin film electrode prepared by the method for preparing the thin film electrode for electrochromic devices and the use of the thin film electrode.

The beneficial effects of the present invention are:

1. By adding a preset amount of nickel acetate to an appropriate amount of ethylene glycol methyl ether in advance; and adding an appropriate amount of ethanolamine; thereby preparing a nickel oxide precursor solution, thereby ensuring the crystal stability of the generated nickel oxide. By changing the doping concentration of cobalt element, the relationship between cobalt doping on the structure, morphology and properties of the thin film particles was obtained, so as to obtain the optimal doping ratio.

2. The constant temperature stirring process after debugging mainly realizes the interfacial effects such as element substitution doping, vacancy enrichment and coupling bonding of the doping components on the existing nickel oxide crystal structure. These effects will help the redox reaction electrons. migrate.

3. The component doping can effectively improve the conductivity of the nickel oxide film and reduce the forbidden band width, which is directly beneficial to the increase of the control range of the solar spectrum transmittance of the electrochromic layer.

4. Test the effects of different annealing temperatures and times on the composition, surface morphology, optical and electrochemical stability of nickel oxide films, and obtain the optimal process parameters through the structure-activity relationship.

The above description is only an overview of the technical solution of the present application. In order to be able to understand the technical means of the present application more clearly, it can be implemented according to the content of the description, and in order to make the above-mentioned and other purposes, features and advantages of the present application more obvious and easy to understand , and the specific embodiments of the present application are listed below.

Description of drawings

In order to explain the embodiments of the present invention or the technical solutions in the prior art more clearly, the following briefly introduces the accompanying drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only It is exemplary, and for those of ordinary skill in the art, other drawings can also be obtained according to the provided drawings without any creative effort.

FIG. 1 is the SEM images of the obtained samples SOL-0(a) and SOL-2(b) according to the specific embodiment of the application.

FIG. 2 is a micro-domain energy spectrum analysis diagram of the obtained sample SOL-2 according to a specific embodiment of the present application.

Figure 3(a) is the XRD patterns of the five groups of samples obtained in the specific embodiment of the application.

Figure 3(b) shows the forbidden band widths of the five groups of samples obtained in the specific embodiment of the present application.

Figure 4 shows the electrochromic properties of SOL-0, SOL-2, SOL-4, SOL-6, SOL-8 measured in 1M KOH, wherein:

Figure 4(a) is the CV curve of each sample at 0.05V s-1;

Figure 4(b) shows the transmittances of SOL-0 and SOL-4 in the 1st and 600th original deposition state, colored state and faded state;

Figure 4(c) shows the response time of SOL-0, SOL-2, SOL-4 and SOL-6 under different cycle times;

Figure 4(d) shows the coloring efficiency of SOL-0 and SOL-6.

Detailed ways

In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention clearer and more comprehensible, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention, but not to limit the present invention.

A specific embodiment of the present application provides a method for preparing a thin film electrode for an electrochromic device. The preparation method can be used for the preparation of thin film electrodes of electrochromic devices, and the thin film electrodes prepared by the method can be used as electrode materials of electrochromic devices. The preparation method of the thin film electrode includes using nickel acetate as a nickel source, using cobalt acetate as a cobalt source, and using a sol-gel method to prepare a cobalt ion-doped nickel oxide mixed solution. The specific method is: adding a preset amount of nickel acetate and a preset amount of ethanolamine to an appropriate amount of ethylene glycol methyl ether; the order of adding nickel acetate and amine acetate here is not required; according to the preset doping ratio, add A preset amount of cobalt acetate is stirred at a constant temperature until the stirring is uniform, so as to prepare the cobalt ion-doped nickel oxide mixed solution. In this example, nickel oxide is used as the precursor, and cobalt oxide is the doping component, so the preferred order of addition is to add nickel acetate first, and then add cobalt acetate. Preferably, the molar ratio of the nickel acetate to the ethanolamine is set to 1:1. The "sol-gel method" mentioned here refers to using compounds containing highly chemically active components as precursors, mixing these raw materials uniformly in the liquid phase, and performing hydrolysis and condensation chemical reactions to form stable transparent in the solution. In the sol system, the sol is slowly polymerized between the aged colloidal particles to form a gel with a three-dimensional network structure, and the gel network is filled with a solvent that loses fluidity to form a gel. The gel is dried, sintered and solidified to prepare nanometers. The constant-temperature stirring method mentioned here includes: using a magnetic stirrer to stir, and the temperature of the magnetic stirrer is set to be between 60°C and 85°C. In the following preparation experiments, the setting temperature is 75°C, and the stirring time is set to 2 hours. .

The cobalt ion-doped nickel oxide mixed solution was allowed to stand in a dark place for 24 hours.

Then, the mixed solution of cobalt ion doped nickel oxide is coated on the surface of the ITO conductive glass by a spin coating method to form a cobalt ion doped nickel oxide thin film electrode diaphragm. The ITO conductive glass is clean ITO conductive glass. The specific method: spin-coating the cobalt ion-doped nickel oxide mixed solution on the surface of the clean ITO conductive glass to make the cobalt ion-doped nickel oxide thin film electrode; and the method for obtaining the clean ITO conductive glass includes: sequentially The ITO conductive glass was cleaned with deionized water, acetone and absolute ethanol. The "ITO conductive glass" mentioned here refers to the process of depositing silicon dioxide (SiO2) and indium tin oxide (ITO) thin films by magnetron sputtering on the basis of soda-lime-based or silicon-boron-based substrate glass. completed. It is a metal compound with good transparent and conductive properties, and has the characteristics of band gap, high light transmittance in the visible spectral region, and low resistivity. In addition, according to the preset film thickness requirements, the spin coating process uses a spin coater to repeatedly spin the surface of the ITO conductive glass, and after each spin-coating layer, it is placed in an oven for drying. Preferably, the temperature of the oven is set to 100°C-120°C. In the following preparation experiments, the set temperature is 110°C, and the drying time of each spin-coating layer is set to 5 minutes.

Finally, the cobalt ion doped nickel oxide thin film electrode is annealed to obtain the cobalt ion doped nickel oxide thin film electrode. Preferably, the annealing equipment is a muffle furnace, and the annealing temperature is set at 380°C-450°C. In the following preparation experiments, the setting temperature is 400°C, and the annealing time is set at 2 hours.

In order to further verify the characteristics of the thin film electrode prepared by the preparation method, the following samples were prepared according to the original different ratios by the thin film electrode method disclosed in this application, and the following analysis and tests were performed on each sample.

1. SEM analysis

FIG. 1 is the SEM images of the samples SOL-0(a) and SOL-2(b) obtained in this example. The particle size and particle void are one of the key factors affecting the electrochemical performance of electrochromic devices. From Figure 1(a), it can be seen that the particles of the doped nickel oxide film are smaller and uniform in size, ranging from 50 to 200 nm. . Due to the agglomeration of particles, the film is rough and uneven, and the gaps between particles are large. It can be seen from Figure 1(b) that the particles of the cobalt (Co)-doped nickel oxide (NiO) film are smaller than that of the undoped nickel oxide film, the particle size ranges from 50 to 100 nm, the particles are uniform, and the film is flat. The voids between particles are small. Therefore, the incorporation of cobalt reduces the particle size of the nickel oxide film particles and improves the distribution of the particles.

In order to further verify that the thin film electrode method disclosed in this application successfully introduces cobalt element, the micro-domain energy spectrum analysis of the sample SOL-2 is carried out, and the results are shown in Fig. 2 . The content of Co, Ni and O elements can be clearly seen from the energy spectrum, and the cobalt element was successfully incorporated into the nickel oxide.

2. XRD test analysis

Figure 3(a) shows the XRD patterns of the five groups of samples. The diffraction peaks of the product are (111), (200) and (220), which are consistent with the nickel oxide standard card (JCPDS No. 47-1049). The incorporation of cobalt did not change the crystal structure of nickel oxide.

Figure 3(b) shows the forbidden band widths of 5 groups of samples that are not accessible by cobalt doping. The results show that the doping atomic lattice of the metal cobalt element is replaced. With the increase of the doping ratio, the band gap is gradually reduced and the conductivity is improved. , but reaching a certain doping ratio will reach saturation and the band gap will increase.

3. Electrochromic testing of thin films

In this test item, three states of the sample need to be tested: the original deposition state, the colored state and the discolored state. The electrochromic test was carried out in 1M KOH electrolyte, and the related electrochromic performance test characterization methods were: optical performance, color changing response time, color changing cycle life, electrochemical performance color changing coloring efficiency. Figure 4 shows the electrochromic properties of SOL-0, SOL-2, SOL-4, SOL-6, SOL-8 measured in 1M KOH, wherein:

(a) is the CV curve of each sample at 0.05V s-1; (b) is the transmittance of SOL-0 and SOL-4 at the 1st and 600th original deposition state, colored state and faded state ; (c) is the response time of SOL-0, SOL-2, SOL-4 and SOL-6 under different cycle times; (d) is the coloring efficiency of SOL-0 and SOL-6. The above test system adopts a three-electrode test system, the electrolyte is 1M KOH, and the working voltage is -0.6-0.8V (refer to Ag/AgO).

Figure 4(a) There are obvious redox peaks on the cyclic voltammetry curve. The oxidation peaks of the first cycle of the five groups of samples appear at 0.62V, 0.6V, 0.57V, 0.53V, and 0.58V, respectively. The 600th cycle The oxidation peaks appeared at 0.6V, 0.58V, 0.6V, 0.62V, and 0.53V, respectively. The position of the reduction peak is about -0.1V. At the beginning of the first cycle, the color of the film layer is brown. As the scanning progresses, when the point position increases to about 0.4V, the color of the film begins to change. When the first cycle progresses to a potential of about 0.6V, the film color becomes brown-black. During the second half of the first cycle, the color of the film became lighter from 0.2V, and by the end of the first cycle, the film became transparent. From the second cycle, the change in film color is a reversible change from clear to brown, that is, an electrochromic reaction occurs during the cyclic voltammetry test:

Anodic reaction:

Ni(OH) ₂ →NiOOH+H ⁺ +e ^- (1)

Cathodic reaction:

NiOOH+H ⁺ +e ^- →Ni(OH) ₂ (2)

Figure 4(b) is the transmittance of SOL-0 and SOL-4 at the 1st and 600th times as original deposition state, colored state and faded state, it can be seen that the ΔT of the two samples increases with the number of cycles Compared with the colored state, the light transmittance of the faded state increases with the increase of the number of cycles. When the cycle reaches 600 times, the transmittance at 550nm drops to 48% and 53%, respectively; while the colored state The transmittance does not change much, and the decrease in transmittance is limited as the number of cycles increases. This result proves that the inactive species during the discoloration cycle is NiOOH. It is obvious from the changes in the figure that the incorporation of cobalt element improves the cycling stability of the films.

It can be seen from Figure 4(c) that, compared with pure NiO films, under the same test conditions, the response time of both the colored state and the decolorized state decreased with the increase of the cobalt doping ratio.

As can be seen in Fig. 4(d), compared with the pure nickel oxide film sample SOL-0, the coloring efficiency of the sample SOL-6 is improved, and the coloring and bleaching times are 8.2 and 9.9 s, respectively, which is attributed to Ni and Co. Phase separation between oxides, point duty color activity in thin films is favored by higher surface areas in the particles from which they are formed, and higher surface areas are present in particles in the nanoscale range.

Claims (10)

1. A preparation method for a thin film electrode of an electrochromic device is characterized by comprising the following steps:

preparing a cobalt ion-doped nickel oxide mixed solution by taking nickel acetate as a nickel source and cobalt acetate as a cobalt source by adopting a sol-gel method;

coating the cobalt ion-doped nickel oxide mixed solution on the surface of ITO conductive glass by adopting a spin-coating method to prepare a cobalt ion-doped nickel oxide film electrode membrane; the ITO conductive glass is clean ITO conductive glass; and annealing the cobalt ion-doped nickel oxide thin film electrode to obtain the cobalt ion-doped nickel oxide thin film electrode.

2. The method for preparing the thin film electrode for the electrochromic device according to claim 1, comprising the steps of:

adding nickel acetate and ethanolamine with preset amount into proper amount of ethylene glycol monomethyl ether;

adding a preset amount of cobalt acetate according to a preset doping proportion, and stirring at constant temperature until the cobalt acetate is uniformly stirred to prepare the cobalt ion doped nickel oxide mixed solution;

standing the cobalt ion-doped nickel oxide mixed solution in the shade for 24 hours, and then spin-coating the cobalt ion-doped nickel oxide mixed solution on the surface of the clean ITO conductive glass to prepare the cobalt ion-doped nickel oxide thin film electrode;

and placing the cobalt ion doped nickel oxide film electrode in a muffle furnace for annealing treatment.

3. The method for preparing a thin film electrode for an electrochromic device according to claim 2, wherein: the molar ratio of the nickel acetate to the ethanolamine is 1: 1.

4. the method for preparing a thin film electrode for an electrochromic device according to claim 2, wherein: and repeatedly spin-coating the surface of the ITO conductive glass by using a spin coater according to the preset film thickness requirement, and drying the ITO conductive glass in an oven after each layer is spin-coated.

5. The method for preparing a thin film electrode for an electrochromic device according to claim 2, wherein: the method for obtaining the clean ITO conductive glass comprises the following steps: and sequentially adopting deionized water, acetone and absolute ethyl alcohol to clean the ITO conductive glass.

6. The method for preparing a thin film electrode for an electrochromic device according to claim 2, wherein: the constant-temperature stirring method comprises the following steps: stirring by adopting a magnetic stirrer, wherein the temperature range of the magnetic stirrer is set to be 60-85 ℃, and the stirring time is set to be 2 hours.

7. The method for preparing a thin film electrode for an electrochromic device according to claim 4, wherein: the temperature of the oven is set to be 100-120 ℃, and the drying time of each spin coating layer is set to be 5 minutes.

8. The method for preparing a thin film electrode for an electrochromic device according to claim 2, wherein: the annealing temperature of the muffle furnace is set to 380-450 ℃, and the annealing time is set to 2 hours.

9. A thin film electrode prepared by the preparation method for the thin film electrode of the electrochromic device according to any one of claims 1 to 8.

10. Use of a thin film electrode prepared by the method for preparing a thin film electrode of an electrochromic device according to any one of claims 1 to 8, wherein: the material is used as an electrode material of an electrochromic device.

Images