Preparation method of Prussian blue-based ink and electrochromic device
Prussian blue particles were prepared and surface modified by co-precipitation method to prepare Prussian blue-based ink suitable for large-area coating, which solved the structural defects and high cost problems in the existing Prussian blue film preparation process and achieved efficient and stable electrical Discoloration performance and long cycle stability are suitable for electrochromic devices of a variety of substrates.
Patent Information
- Application Number
- CN202411215469.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-02
- Publication Date
- 2024-12-13
AI Technical Summary
The existing Prussian blue film preparation process has structural defects, high cost and low production efficiency, which limits its wide application in the fields of dimmed glass and flexible electrochromic devices for large-area buildings.
Prussian blue particles were prepared by co-precipitation method, and the surface modification of ferrocyanone ions and n-octanylamine was obtained to obtain modified Prussian blue particles mixed with ethanol to prepare Prussian blue-based ink for coating technology to prepare electrochromic devices .
It improves the film forming performance of Prussian blue-based ink, achieves high optical modulation rate, fast response characteristics and excellent long cycle stability, and is suitable for various substrates, reducing production costs and process complexity.
Smart Images
Figure CN119119803A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to a preparation method of a Prussian blue-based ink and an electrochromic device, belonging to the technical field of electrochromic. Background Art
[0002] At present, electrochromic refers to the phenomenon that certain materials undergo redox reactions under low electric fields, resulting in reversible changes in color or optical properties. Electrochromic devices based on electrochromic materials have been applied to automotive anti-glare rearview mirrors, aircraft smart windows, smart goggles and other fields. In addition, with the continuous development of wearable smart electronic devices and flexible devices, the exploration and development of electrochromic devices is no longer limited to improving their electrical and optical properties, but more to flexible materials or substrates to achieve the purpose of expanding the application range of electrochromic devices and meet emerging needs. However, electrochromic devices have not yet been widely used in the field of dimming glass and flexible electrochromic devices for large-area buildings. This is related to the limitations of traditional coating processes such as magnetron sputtering, thermal evaporation, electron beam evaporation and other physical vapor deposition technologies. Although this type of thin film preparation process can accurately control the composition of the film, its high cost and low production efficiency limit its large-scale manufacturing application. Therefore, the development of a low-cost, large-area preparation, and fast production coating process has become one of the key technical issues to be solved.
[0003] The infinite three-dimensional network structure in the crystal structure of Prussian blue (PB) material can provide open ion channels and large gap space, which is conducive to the rapid transfer of ions. At the same time, as a transition metal oxide anode electrochromic material, it has the advantages of low operating voltage, low power consumption, good open circuit memory function and long cycle stability, so it has become one of the most widely studied and most promising electrochromic electrodes. At present, most of the reported PB film preparation processes will cause structural defects to deteriorate its electrochromic performance and electrochemical stability, which seriously restricts the further development and application of this material. Traditional PB film deposition methods include electrochemical deposition and hydrothermal methods. These two methods require expensive equipment, additional power input or high temperature and high pressure conditions. These constraints make it difficult to achieve large-scale production of films. Coating technology is considered to be a film preparation technology with low cost, simple process flow, easy large-area coating, and suitable for various types of substrates. Therefore, it is expected to become one of the key technologies for large-scale production of electrochromic films. However, there is currently a lack of functional inks that are compatible with the large-area low-temperature coating technology of PB-based electrochromic dimming glass, which greatly restricts its practical application.
[0004] The PB ink prepared by the sol-gel method requires the ITO / glass and ITO / PET substrates to be plasma treated before the PB film can be prepared by spin coating. The electrochromic device based on liquid electrolyte assembled with tungsten oxide as the working electrode and Prussian blue as the counter electrode has an optical modulation of 79% and a coloring efficiency of 123.32 cm 2 C -1 , the electrochromic cycle of the wavelength 633nm exceeds 100 cycles. The disadvantages of this solution are: the substrate needs to be surface treated, the long-cycle stability of the device is poor, and the large-scale production of electrochromic devices is limited. Summary of the invention
[0005] The technical problem to be solved by the present invention is to overcome the defects of the prior art and provide a method for preparing a Prussian blue-based ink. The film-forming performance of the Prussian blue-based ink prepared by the method is improved, and the electrochromic device containing the Prussian blue-based ink coating prepared thereby exhibits a high optical modulation rate, a fast response characteristic and excellent long-cycle stability.
[0006] In order to solve the above technical problems, the technical solution of the present invention is: a method for preparing a Prussian blue-based ink, the method comprising the following steps:
[0007] S01: Preparation of Prussian blue particles;
[0008] S02: Surface modification of Prussian blue particles using ferrocyanide ions and n-octylamine to obtain modified Prussian blue particles;
[0009] S03: Stirring the modified Prussian blue particles and ethanol to obtain a Prussian blue-based ink.
[0010] Furthermore, in step S01, Prussian blue particles are prepared by a co-precipitation method.
[0011] Further, step S01 is specifically as follows:
[0012] Na4[Fe(CN)6]·10H2O aqueous solution was dropped into Fe(NO)3·9H2O aqueous solution, stirred, centrifuged, washed and vacuum dried to obtain Prussian blue particles.
[0013] Furthermore, in step S01, washing is performed with deionized water; and / or vacuum drying is performed at 60°C.
[0014] Further, in step S02, the surface modification of Prussian blue particles using ferrocyanide ions and n-octylamine specifically includes:
[0015] Furthermore, the Prussian blue particles were mixed with a Na4[Fe(CN)6]·10H2O aqueous solution and stirred, and then n-butanol and n-octylamine were added and stirred continuously, and then the modified Prussian blue particles were obtained through centrifugation, washing and vacuum drying.
[0016] Furthermore, the average particle size of the Prussian blue particles is less than 100 nanometers.
[0017] Furthermore, in step S02, washing is performed by ethanol washing; and / or vacuum drying is specifically vacuum freeze drying.
[0018] The invention also provides a Prussian blue-based ink, which is prepared by the above preparation method.
[0019] The present invention also provides an electrochromic device, comprising a substrate and a Prussian blue-based ink coating coated on the substrate with the Prussian blue-based ink.
[0020] Furthermore, the substrate is an ITO / glass substrate, an ITO / PET substrate, an ITO / Ag / AZO / PET substrate, or an AgNW-PET substrate.
[0021] After adopting the above technical solution, the present invention has the following beneficial effects:
[0022] 1. The present invention uses ferrocyanide ions and n-octylamine to modify the surface of insoluble PB particles, thereby enhancing the affinity of the PB particles to the ethanol solvent, thereby obtaining a uniform ethanol-dispersed Prussian blue-based ink. The method of the present invention does not require high temperature and high pressure conditions, and the preparation process is simple. The ink will not precipitate or deteriorate when stored for a long time at room temperature, has good wettability to various substrates, and has excellent film-forming properties.
[0023] 2. Prussian blue-based ink with ethanol as solvent has suitable surface tension and viscosity, excellent film-forming properties, and is suitable for various substrates such as glass and PET. Combined with coating technology, uniform PB electrochromic films can be prepared.
[0024] 3. The PB electrochromic film with Prussian blue-based ink coating has a microstructure of amorphous embedded nanocrystals, which enhances the electrochromic performance and long-cycle stability of the film. BRIEF DESCRIPTION OF THE DRAWINGS
[0025] Figure 1 is a dynamic light scattering particle size distribution diagram of the PB ink of the present invention;
[0026] FIG. 2( a ) is a HRTEM image of the PB electrochromic film of the present invention. Figure 1 ;
[0027] FIG2( b ) is a second HRTEM image of the PB electrochromic film of the present invention;
[0028] FIG3( a) is an XRD pattern diagram of the PB electrochromic film of the present invention;
[0029] FIG3( b ) is a FTIR spectrum of the PB electrochromic film of the present invention;
[0030] FIG3( c ) is a SEM image of the PB electrochromic film of the present invention;
[0031] FIG. 3( d ) is an AFM image of the PB electrochromic film of the present invention.
[0032] FIG4( a ) is a spectrum diagram of the PB electrochromic film of the present invention in a colored state (+0.6 V) and a faded state (-0.6 V);
[0033] FIG4( b ) is a graph showing the response time and in-situ transmittance of the PB electrochromic film of the present invention between the colored and faded states at a wavelength of 700 nm;
[0034] FIG4( c ) is a graph showing the variation of the in-situ optical density of the PB electrochromic film of the present invention with the charge density;
[0035] FIG4( d ) is an in-situ transmission spectrum of the PB electrochromic film of the present invention at a wavelength of 700 nm;
[0036] FIG5( a) is a transmission spectrum diagram of the PB-based electrochromic device of the present invention;
[0037] FIG5( b ) is a graph showing the response time and in-situ transmittance of the PB-based electrochromic device of the present invention between the colored and faded states at 633 nm;
[0038] FIG5( c ) is an in-situ transmission spectrum of the PB-based electrochromic device of the present invention at 633 nm. DETAILED DESCRIPTION
[0039] The present invention provides a method for preparing a Prussian blue-based ink and an electrochromic device. Those skilled in the art can refer to the content of this article and appropriately improve the process parameters to achieve the same. It should be particularly noted that all similar substitutions and modifications are obvious to those skilled in the art and they all fall within the scope of protection of the present invention. The method and application of the present invention have been described through preferred embodiments, and relevant personnel can obviously modify or appropriately change and combine the method and application of this article without departing from the content, spirit and scope of the present invention to implement and apply the technology of the present invention.
[0040] A method for preparing a Prussian blue-based ink, the method comprising the steps of:
[0041] S01: Preparation of Prussian blue particles;
[0042] S02: Surface modification of Prussian blue particles using ferrocyanide ions and n-octylamine to obtain modified Prussian blue particles;
[0043] S03: Stirring the modified Prussian blue particles and ethanol to obtain a Prussian blue-based ink.
[0044] In step S01, Prussian blue particles are prepared by a co-precipitation method.
[0045] Specifically, step S01 is as follows:
[0046] Na4[Fe(CN)6]·10H2O aqueous solution was dropped into Fe(NO)3·9H2O aqueous solution, stirred, centrifuged, washed and vacuum dried to obtain Prussian blue particles.
[0047] Specifically, in step S01, washing is performed with deionized water; and vacuum drying is performed at 60°C.
[0048] Specifically, in step S02, surface modification of Prussian blue particles using ferrocyanide ions and n-octylamine specifically includes:
[0049] Specifically, Prussian blue particles are mixed with a Na4[Fe(CN)6]·10H2O aqueous solution and stirred, and then n-butanol and n-octylamine are added and stirred continuously, and then the modified Prussian blue particles are obtained by centrifugation, washing and vacuum drying.
[0050] Specifically, in step S02, washing is performed by ethanol washing; and vacuum drying is specifically vacuum freeze drying.
[0051] Specifically, the average particle size of the Prussian blue particles is less than 100 nanometers.
[0052] An electrochromic device comprises a substrate and a Prussian blue-based ink coating coated on the substrate with prepared Prussian blue-based ink.
[0053] Specifically, the substrate is various transparent conductive substrates such as ITO / glass substrate; ITO / PET substrate; ITO / Ag / AZO / PET substrate or AgNW-PET substrate.
[0054] Electrochromic devices include, but are not limited to, electrochromic glass.
[0055] In order to make the contents of the present invention more clearly understood, the present invention is further described in detail below based on specific embodiments in conjunction with the accompanying drawings.
[0056] Embodiment 1
[0057] A method for preparing a Prussian blue-based ink, the method comprising the steps of:
[0058] First, 45 ml of 0.1 M Na4[Fe(CN)6]·10H2O aqueous solution was slowly dropped into 60 ml of 0.1 M Fe(NO)3·9H2O aqueous solution, stirred at room temperature for 4 hours, centrifuged to obtain a precipitate, and washed the precipitate twice with deionized water, and vacuum dried at 60°C for 10 hours to obtain crude PB particles (i.e., Prussian blue particles);
[0059] 1 g of crude PB particles, 0.6 g of Na4[Fe(CN)6]·10H2O and 20 ml of water were added to a beaker and stirred at room temperature for 1 day, followed by the addition of 150 ml of n-butanol and 0.8 ml of n-octylamine, and continued stirring at room temperature for 1 day. The precipitate was obtained by centrifugation, and the precipitate was washed twice with ethanol and then freeze-dried in vacuum to obtain ethanol-dispersible PB nanoparticles (i.e., modified Prussian blue particles);
[0060] 1.0 g of ethanol-dispersible PB nanoparticles was added to 15 ml of ethanol and stirred at room temperature for 3 days to obtain PB ink (ie, Prussian blue-based ink).
[0061] The concentrations of Na4[Fe(CN)6]·10H2O aqueous solution and Fe(NO)3·9H2O aqueous solution can be selected between 0.1M and 0.5M; the centrifugation process can be replaced by decantation method and normal pressure filtration method;
[0062] The PB ink is coated on the ITO glass in combination with the coating process to form a PB film, and then the film is placed in a vacuum drying oven at 60°C for 10 hours to obtain a PB electrochromic film. The concentration of the PB ink can be adjusted between 20mg / ml and 70mg / ml as needed.
[0063] Figure 1 The dynamic light scattering particle size distribution diagram of the PB ink prepared according to Example 1 is shown, and the results show that the average particle size is 77nm. The sub-100nm particles enable the Prussian blue ink to spread and adsorb better on the substrate surface, thereby facilitating the formation of a uniform film.
[0064] Figure 2(a) and Figure 1 The HRTEM image of the PB electrochromic film shown in (b) shows clear lattice fringes with interplanar spacings of 0.199 nm and 0.131 nm, corresponding to the interplanar spacings of the (400) and (220) planes of cubic PB (73#0687), respectively. Combined with the XRD results, it is proved that the PB electrochromic film has a structure of amorphous embedded nanocrystals.
[0065] In Figure 3(a), diffraction peaks corresponding to the (200), (220), and (400) crystal planes of cubic PB appear. These peaks are broad and have very low intensities, indicating that PB has a low degree of crystallinity and a small grain size.
[0066] The FTIR spectrum shown in Figure 3(b) shows the bonds belonging to PB (C≡N bonds and Fe-C bonds), which corresponds to the chemical formula of Prussian blue.
[0067] In Figure 3(c), the surface and cross-sectional SEM images of the PB electrochromic film show that the PB electrochromic film is composed of densely packed nanoparticles. The presence of nanopores effectively increases the specific surface area, provides more active sites, reduces the diffusion path, and is conducive to the embedding and extraction of electrolyte ions.
[0068] FIG3( d ) shows that the root mean square roughness is 4.29 nm, indicating that the surface of the film is smooth and the electrochromic ink prepared by the present invention has excellent film-forming uniformity.
[0069] Figure 4 shows the in-situ spectral test of the PB electrochromic film. The test conditions are all carried out in a three-electrode system with a Pt sheet as the counter electrode and Ag / AgCl as the reference electrode in a PC-LiClO4 electrolyte containing acetic acid. Figure 4(a) shows the coloring and fading curves of the film in the wavelength range of 400 to 1000nm. The optical modulation (ΔT) of the PB film at 700nm under ±0.6V is 82.48%. From the in-situ transmittance curve at 700nm shown in Figure 4(b), it can be calculated that the coloring time (Tc) of the PB film is 3.9s and the fading time (Tb) is 9.3s. Compared with the coloring time, the fading time is longer because there is a significant difference in the interfacial charge transfer resistance between the film and the electrolyte interface during the coloring and fading process, making it more difficult for ions to embed into the film than to de-embed. As shown in Figure 4(c), the coloring efficiency of the PB film is calculated to be 178.59cm based on the relationship between the charge stored per unit area (Q) and the optical density change (ΔOD). 2 C -1 , which means that less charge embedding per unit area can enable the film to achieve a large optical modulation range; Figure 4(d) shows that the prepared PB film was subjected to a long cycle test of 1000 cycles. After 1000 cycles, the optical modulation retention rate of the film was 80%, indicating that the film has good cycle stability.
[0070] The electrochromic device described in FIG5 is composed of a tungsten oxide thin film layer as a working electrode, a Prussian blue thin film layer as a counter electrode, and a quasi-solid electrolyte between the two electrodes; as shown in FIG5(a), the optical modulation of the device at 633 nm is 66.93%; from the in-situ transmittance curve at 633 nm shown in FIG4(b), it can be calculated that the coloring time (Tc) of the PB-WO3 device is 3.84 s, and the fading time (Tb) is 4.56 s, and the response time is very short; as shown in FIG5(c), the optical modulation rate of the device is still 44.1% after 10,000 cycles of continuous operation, indicating that the PB-WO3 quasi-solid-state device has excellent cycle stability.
[0071] The specific embodiments described above further illustrate the technical problems, technical solutions and beneficial effects solved by the present invention. It should be understood that the above are only specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.
Claims
1. A method for preparing a Prussian blue-based ink, characterized in that The steps of the method include: S01: Preparation of Prussian blue particles; S02: Surface modification of Prussian blue particles using ferrocyanide ions and n-octylamine to obtain modified Prussian blue particles; S03: Stirring the modified Prussian blue particles and ethanol to obtain a Prussian blue-based ink.
2. The preparation method according to claim 1, characterized in that: In step S01, Prussian blue particles are prepared by a co-precipitation method.
3. The preparation method according to claim 2, characterized in that: Step S01 is specifically as follows: Na4[Fe(CN)6]·10H2O aqueous solution was dropped into Fe(NO)3·9H2O aqueous solution, stirred, centrifuged, washed and vacuum dried to obtain Prussian blue particles.
4. The preparation method according to claim 3, characterized in that: In step S01, washing is performed with deionized water; and / or vacuum drying is performed at 60°C.
5. The preparation method according to claim 1, characterized in that: In step S02, surface modification of Prussian blue particles using ferrocyanide ions and n-octylamine specifically includes: The Prussian blue particles were mixed with a Na4[Fe(CN)6]·10H2O aqueous solution and stirred, and then n-butanol and n-octylamine were added and stirred continuously, and then the modified Prussian blue particles were obtained through centrifugation, washing and vacuum drying.
6. The preparation method according to claim 5, characterized in that: In step S02, washing is performed by ethanol washing; and / or vacuum drying is performed by vacuum freeze drying.
7. The preparation method according to claim 1, characterized in that: The average particle size of Prussian blue particles is less than 100 nanometers.
8. A Prussian blue-based ink, characterized in that: The method is prepared according to any one of claims 1 to 7.
9. The Prussian blue-based ink according to claim 8, characterized in that It has an amorphous embedded nanocrystalline structure.
10. An electrochromic device, characterized in that: The invention comprises a substrate and a Prussian blue-based ink coating layer coated on the substrate with the Prussian blue-based ink according to claim 7.
11. The electrochromic device according to claim 10, characterized in that: The substrate is an ITO / glass substrate, an ITO / PET substrate, an ITO / Ag / AZO / PET substrate, or an AgNW-PET substrate.