A vanadium dioxide-based particle-free printed electronic ink, its preparation method and application

Abstract

This invention belongs to the field of electronic materials technology, specifically relating to a vanadium dioxide-based particle-free printed electronic ink, its preparation method, and its application. The preparation method of the vanadium dioxide-based particle-free printed electronic ink of this invention includes the following steps: Step S1, dissolving a complexing agent in a solvent, then adding a vanadium precursor and mixing uniformly to obtain a vanadium-based ink; Step S2, adding a reducing agent and organic additives to the vanadium-based ink, stirring to dissolve, and filtering to obtain the vanadium dioxide-based particle-free printed electronic ink. The electronic ink of this invention exhibits strong stability, can be stored for a long time at room temperature under natural light without precipitation, and can be used to prepare uniform and dense vanadium dioxide thin films.

Description

Technical Field

[0001] This invention belongs to the field of electronic materials technology, specifically relating to a vanadium dioxide-based particle-free printed electronic ink, its preparation method, and its application. Background Technology

[0002] Vanadium dioxide (VO2), a typical thermo-induced phase change material, undergoes a reversible metal-insulator transition near a critical temperature close to room temperature (~68°C). This phase transition is accompanied by resistivity changes of several orders of magnitude and significant changes in infrared optical properties, making it a promising candidate for applications in smart windows, optical switches, thermal sensors, and next-generation communication devices. Currently, mainstream technologies for preparing vanadium dioxide functional thin films, such as physical vapor deposition (PVD) and chemical vapor deposition (CVD), while capable of producing high-quality films, generally suffer from inherent drawbacks such as expensive equipment, complex processes, limited deposition area, and poor compatibility with flexible polymer substrates. These limitations make it difficult to meet the demands of modern electronics manufacturing for low cost, flexibility, and large-scale production.

[0003] In contrast, printed electronics (PCB) technology offers a revolutionary path to achieving these goals by depositing functional materials in the form of "ink." PCB technology primarily involves patterning highly dispersed or water-soluble inorganic or organic materials to manufacture electronic components. It is an additive manufacturing technology that directly transfers ink to a substrate, encompassing a variety of highly adaptable printing methods such as screen printing, gravure printing, rotary screen printing, inkjet printing, and aerosol printing. PCB technology is suitable for large-area manufacturing, simplifies electronic product manufacturing processes, is compatible with various flexible substrates, enables environmentally friendly green production, and is cost-effective. Inkjet printing is suitable for high-precision, digital direct writing of graphics; aerosol printing can form films on uneven surfaces; while screen printing and gravure printing excel at large-area, high-efficiency mass production. This versatility creates unprecedented flexibility for manufacturing electronic devices on various substrates, including flexible plastics, paper, and even fabrics.

[0004] Traditional VO2 applications are largely limited to rigid substrates such as glass and silicon wafers. The future trend is towards making it flexible, bendable, and even stretchable, and capable of large-scale manufacturing through printing processes. Researching and preparing particle-free vanadium dioxide inks that can be thin-filmed, flexible, printable, and intelligent is urgently needed. However, incorporating vanadium dioxide into printed electronics systems still faces significant challenges. The traditional approach is to prepare it as a granular conductive ink, i.e., by grinding VO2 nanoparticles and dispersing them in a solvent. This type of ink has fundamental drawbacks: easy aggregation and poor stability. The nanoparticles have high surface energy, making them prone to aggregation and sedimentation, leading to poor ink storage stability, printhead clogging during printing, and severely impacting yield and reliability. High sintering temperatures and substrate limitations mean that the printed granular film requires high-temperature heat treatment (typically >450℃) to remove insulating dispersants and establish conductive pathways. This temperature far exceeds the tolerance limit of most flexible polymer substrates (typically <200℃). Poor film quality results in porous structures with poor density and high resistivity after sintering. Point contact between particles leads to low carrier mobility, making it difficult to meet the requirements of high-performance devices. Phase transition performance is also compromised. The stringent particle preparation and sintering process can easily introduce lattice defects or cause VO2 oxidation, significantly degrading characteristic phase transition performance (such as on / off ratio and transition sharpness).

[0005] Particle-free inks exist as molecular precursors and possess significant advantages such as excellent intrinsic stability, low-temperature conversion capability, and continuous, dense film formation. They can be perfectly matched with diverse printing processes, making them an ideal approach for directly printing high-performance vanadium dioxide phase-change devices on flexible substrates. However, research in this field is still in its early stages. Developing a particle-free VO2 ink capable of low-temperature conversion while maintaining a high phase-change on / off ratio and excellent environmental stability is a core issue that urgently needs to be addressed to drive its practical application.

[0006] Therefore, there is an urgent need for a vanadium dioxide-based particle-free printed electronic ink. By designing and screening the ink components, the defects of traditional granular inks, such as easy agglomeration, poor stability, need for high-temperature sintering, and the complexity and difficulty in flexible integration of existing vapor deposition technology, can be overcome, ensuring that a uniform and dense vanadium dioxide film can be obtained on the substrate. Summary of the Invention

[0007] The purpose of this invention is to provide a vanadium dioxide-based particle-free printed electronic ink, its preparation method, and its application. This invention uses a vanadium precursor component mixed with an amine complexing agent, and forms a stable complex by adding a reducing agent and organic additives. A solvent is then added to form the vanadium dioxide-based particle-free printed electronic ink. This electronic ink exhibits high stability and can be stored at room temperature under natural light without precipitation. Furthermore, the preparation method is simple, easy to operate, low-cost, environmentally friendly, and readily applicable to industrial production. The vanadium dioxide thin film prepared by this ink has high transmittance, effectively improving its solar light modulation capability and thermally induced phase transition properties.

[0008] To achieve the above objectives, the present invention provides the following technical solution:

[0009] The first aspect of this invention provides a method for preparing vanadium dioxide-based particle-free printed electronic ink, comprising the following steps:

[0010] Step S1: Dissolve the complexing agent in a solvent, then add the vanadium precursor and mix thoroughly to obtain vanadium-based ink;

[0011] Step S2: Add reducing agent and organic additive to the vanadium-based ink, stir to dissolve, filter, and obtain vanadium dioxide-based particle-free printed electronic ink;

[0012] The viscosity of the electronic ink is 10~40 mPa·s, and the surface tension is 5~40 mN / m.

[0013] As a preferred embodiment, the components, by weight, include: 5-15 parts of vanadium precursor, 10-70 parts of complexing agent, 2-10 parts of reducing agent, 1-10 parts of organic additive, and 20-90 parts of solvent.

[0014] As a preferred embodiment, the weight fraction of the vanadium precursor in this invention can be 5 parts, 7 parts, 9 parts, 11 parts, 13 parts, or 15 parts, etc.

[0015] As a preferred embodiment, the complexing agent in this invention can be in the following weight proportions: 10 parts, 20 parts, 30 parts, 40 parts, 50 parts, 60 parts, or 70 parts, etc.

[0016] As a preferred embodiment, the weight of the reducing agent in this invention can be 2 parts, 4 parts, 6 parts, 8 parts, or 10 parts, etc.

[0017] As a preferred embodiment, the organic additives described in this invention can be in the following weight proportions: 1 part, 2 parts, 3 parts, 4 parts, 5 parts, 6 parts, 7 parts, 8 parts, 9 parts, or 10 parts, etc.

[0018] As a preferred embodiment, the solvent in this invention may be in the following weight proportions: 20 parts, 30 parts, 40 parts, 50 parts, 60 parts, 70 parts, 80 parts, or 90 parts.

[0019] As a preferred embodiment, the vanadium precursor is selected from one or more of vanadium oxyacetylacetonate, vanadium oxysulfate, ammonium metavanadate, and vanadium pentoxide.

[0020] The vanadium precursor of this invention is derived from vanadate ions. By controlling the type and proportion of the precursor, the storage stability of the electronic ink can be guaranteed. At the same time, the complexation efficiency of the metal precursor can be improved during the subsequent formation of the vanadium dioxide thin film, thereby improving the uniformity and integrity of the film.

[0021] As a preferred embodiment, the vanadium precursor is vanadium acetylacetonate and ammonium metavanadate; the mass ratio of vanadium acetylacetonate and ammonium metavanadate is (1~2):1.

[0022] This invention preferably uses a combination of vanadium acetylacetonate and ammonium metavanadate. Vanadium acetylacetonate has good solubility and controllable thermal decomposition, which is conducive to the formation of uniform nanocrystal nuclei. Ammonium metavanadate helps to regulate the vanadium concentration and redox environment in the reaction system. The two work together to achieve the synergistic effect of organic-inorganic precursors, avoiding rapid precipitation or aggregation caused by a single precursor, thereby obtaining a well-dispersed nanoparticle colloid and improving ink stability. At the same time, the synergistic decomposition of the two precursors can promote the directional crystallization of vanadium dioxide, reduce the formation of impurity phases, thereby reducing the surface roughness of the film and improving the uniformity and smoothness of the film thickness.

[0023] As a preferred embodiment, the complexing agent is selected from one or more of 1,2-propanediamine, ethylenediamine, ethylamine, n-propylamine, isopropylamine, n-butylamine, n-hexylamine, ethanolamine, triethanolamine, isopropanolamine, diethylethylenediamine, and hydroxyethylethylenediamine.

[0024] The complexing agent of this invention is an amine compound containing a nitrogen atom with a lone pair of electrons, which can form a stable coordination complex with the vanadium precursor, inhibiting premature hydrolysis and aggregation, keeping the vanadate ions in a stable dissolved state, thereby maintaining long-term storage stability; at the same time, the complexing agent molecules self-assemble in the solution to form a nanoscale template, guiding the vanadium dioxide crystals to grow along a specific crystal plane, making the grain size uniform and the orientation consistent, effectively improving the uniformity of the film.

[0025] As a preferred embodiment, the reducing agent is selected from one or more of glucose, tartaric acid, oxalic acid, ascorbic acid, citric acid, formic acid, and formaldehyde.

[0026] The reducing agent of this invention can stabilize the valence state of vanadium ions, transforming the ink system from a complex mixture of polyvanadates into a relatively simple and stable complex solution, thereby achieving a longer shelf life and improving the stability of the ink. At the same time, during the solvent removal process, the stable complex can effectively avoid film roughness caused by particle agglomeration, thereby improving film uniformity.

[0027] As a preferred embodiment, the organic additive is ethyl cellulose.

[0028] The organic additive used in this invention is ethyl cellulose. The ethyl cellulose molecular chain expands in the solvent and adsorbs onto the surface of the nanoparticles, preventing the particles from agglomerating due to van der Waals forces, thereby improving the storage stability of the electronic ink. In addition, ethyl cellulose can slow down the solvent evaporation rate, allowing the particles to be deposited uniformly during the drying process, avoiding edge accumulation, and improving the uniformity and smoothness of the film thickness.

[0029] As a preferred embodiment, the solvent is selected from one or more of water, alcohol, and ether;

[0030] The alcohol is selected from one of ethylene glycol, glycerol, n-butanol, isopropanol, and triethylene glycol;

[0031] The ether is selected from ethylene glycol methyl ether and diethylene glycol butyl ether.

[0032] As a preferred embodiment, the solvent has a boiling point ≤300℃ at normal pressure.

[0033] The solvent of this invention also functions as a viscosity modifier, which can regulate the viscosity of electronic ink, making the ink suitable for substrates of different materials while ensuring its stability and film-forming properties.

[0034] As a preferred embodiment, the solvent is water and alcohol; the mass ratio of water to alcohol is (1~8):1.

[0035] This invention uses water and alcohol as compound solvents. Water can effectively dissolve inorganic salt precursors, while alcohol can partially dissolve ethyl cellulose, amine complexing agents, etc., and inhibit excessive hydrolysis of high-valence metal ions. The two are compounded to form a homogeneous medium, which enables inorganic and organic components to co-dissolve and avoids phase separation, thereby improving the storage stability of the ink. At the same time, the two are compounded to form a gradient evaporation. In the early stage, the alcohol evaporates rapidly, taking away some heat and inhibiting edge accumulation. In the later stage, the water evaporates slowly, allowing the particles enough time to rearrange, resulting in a dense, uniform thickness, and crack-free film.

[0036] As a preferred embodiment, the stirring and dissolving conditions in step S2 are: temperature of 10~25°C and time of 6~24h.

[0037] The second aspect of the present invention provides a vanadium dioxide-based particle-free printed electronic ink prepared by the preparation method described in the first aspect.

[0038] A third aspect of the present invention provides an application of electronic ink prepared by the preparation method described in the first aspect, comprising the following steps:

[0039] (1) The electronic ink prepared by the preparation method described in the first aspect is deposited on a substrate to obtain a film-containing substrate;

[0040] (2) The film-containing substrate is first pretreated and then placed in a heat treatment furnace for stepwise annealing to obtain a vanadium dioxide film.

[0041] As a preferred embodiment, the substrate material is selected from one of the following: polyethylene terephthalate, polydimethylsiloxane, polystyrene, polyacrylonitrile, polybutadiene, polystyrene, polycarbonate, polyimide, polyetherimide, thermoplastic polyurethane, silicone film, wool, silk, cotton, flax, jute, modal, bamboo, nylon, paper, glass, and metal.

[0042] As a preferred embodiment, the film-forming method is selected from one of the following: drop coating, coating, dip coating, spray coating, lamination, suspension coating, screen printing, inkjet printing, roll-to-roll printing, screen printing, offset printing, flexographic printing, flatbed printing, gravure printing, stencil brushing, and pad printing.

[0043] As a preferred embodiment, the pretreatment steps are as follows: drying on a heating plate at 80~90°C for 10~15 min, heating at 100~110°C for 10~15 min, and heating at 120~130°C for 10~15 min.

[0044] As a preferred embodiment, the step-by-step annealing process consists of the following steps: the first annealing temperature is 200~500℃ and the annealing time is 0.5~3h; the second annealing temperature is 200~800℃ and the annealing time is 0.5~6h.

[0045] Compared with the prior art, the advantages and beneficial effects of the present invention are as follows:

[0046] 1. This invention addresses the problems of poor stability, easy clogging of printheads, and unstable valence state of vanadium dioxide particulate inks. It employs reducing agents such as oxalic acid, tartaric acid, and ascorbic acid to reduce the vanadium precursor, which is then complexed with a complexing agent. After filtration, a particle-free vanadium dioxide printed electronic ink is obtained. Further additives are added to stabilize it in an ideal valence state, lowering the decomposition temperature of the vanadium dioxide ink and allowing for long-term storage at room temperature. This invention uses a stepwise annealing method to prepare vanadium dioxide, resulting in a complete and uniform ideal vanadium dioxide film. Compared with other methods for preparing vanadium dioxide films, this method offers higher material utilization, greater economic efficiency, and is energy-saving and environmentally friendly.

[0047] 2. The particle-free vanadium dioxide printed electronic ink of the present invention has a simple preparation method, good stability, and can be stored at room temperature for more than a month. Compared with other inks that require low-temperature storage, it is energy-saving and environmentally friendly. The vanadium dioxide thin film preparation process proposed in this invention is simple, and the film is uniform and defect-free. The material utilization rate is high and the cost-effectiveness is high. The preparation process is green and environmentally friendly with few side reactions. In addition, the vanadium dioxide thin film has high transmittance at room temperature, good thermal color change performance, and broad application prospects. Attached Figure Description

[0048] Figure 1 The image shows the XRD pattern of the vanadium dioxide thin film in Example 1.

[0049] Figure 2 This is a SEM image of the vanadium dioxide thin film in Example 1.

[0050] Figure 3 This is a physical image of the electronic ink used in Example 1.

[0051] Figure 4 This is a photograph of the vanadium dioxide thin film in Example 1. Detailed Implementation

[0052] The technical solutions in the embodiments of the present invention will be clearly and completely described below. 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.

[0053] The sources of some components in the examples and comparative examples are as follows:

[0054] Vanadium acetylacetonate, CAS No. 3153-26-2, was purchased from Shanghai Maclean Biochemical Technology Co., Ltd.

[0055] Ammonium metavanadate, CAS No. 7803-55-6, was purchased from Shanghai Maclean Biochemical Technology Co., Ltd.

[0056] Triethanolamine, CAS No. 102-71-6, was purchased from Shanghai Maclean Biochemical Technology Co., Ltd.

[0057] Ethanolamine, CAS No. 141-43-5, was purchased from Shanghai Maclean Biochemical Technology Co., Ltd.

[0058] Tartaric acid, CAS No. 526-83-0, was purchased from Shanghai Maclean Biochemical Technology Co., Ltd.

[0059] Ascorbic acid, CAS No. 50-81-7, purchased from Shanghai Maclean Biochemical Technology Co., Ltd.

[0060] Formic acid, CAS No. 64-18-6, purchased from Shanghai Maclean Biochemical Technology Co., Ltd.

[0061] Ethyl cellulose, product number E110670, was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.

[0062] Glycerol, CAS No. 56-81-5, purchased from Sinopharm Chemical Reagent Co., Ltd.

[0063] Triethylene glycol, CAS No. 112-27-6, was purchased from Sinopharm Chemical Reagent Co., Ltd.

[0064] Example 1

[0065] This embodiment provides a method for preparing vanadium dioxide-based particle-free printed electronic ink, including the following steps:

[0066] Step S1: Dissolve 10 parts of the complexing agent triethanolamine in 20 parts of solvent (10 parts of water and 10 parts of glycerol), then add 5 parts of vanadium precursor (2.5 parts of acetylacetone vanadium oxide and 2.5 parts of ammonium metavanadate) and mix evenly to obtain vanadium-based ink.

[0067] Step S2: Add 2 parts of reducing agent tartaric acid and 1 part of organic additive ethyl cellulose to the vanadium-based ink and stir to dissolve (temperature 25°C, time 6h), filter, and obtain vanadium dioxide-based particle-free printed electronic ink (viscosity 28mPa·s, surface tension 20mN / m).

[0068] The electronic ink was spin-coated onto a 10×10cm quartz glass substrate. The spin-coating parameters were set as follows: a uniform coating speed of 500 r / min and a uniform coating time of 10 s; a spin-coating speed of 3000 r / min and a spin-coating time of 20 s. The substrate was dried at 80°C for 15 min, heated at 100°C for 15 min, and heated at 120°C for 15 min on a heating plate. The pretreated film was then heated to 700°C at a heating rate of 2°C / min and heat-treated under an argon atmosphere for 1 h to obtain a vanadium dioxide film.

[0069] Example 2

[0070] This embodiment provides a method for preparing vanadium dioxide-based particle-free printed electronic ink, including the following steps:

[0071] Step S1: Dissolve 10 parts of complexing agent ethanolamine in 65 parts of solvent (35 parts of water and 30 parts of glycerol), then add 6 parts of vanadium precursor ammonium metavanadate and mix evenly to obtain vanadium-based ink;

[0072] Step S2: Add 5 parts of reducing agent tartaric acid and 1 part of organic additive ethyl cellulose to the vanadium-based ink and stir to dissolve (temperature 10°C, time 24h), filter, and obtain vanadium dioxide-based particle-free printed electronic ink (viscosity 10mPa·s, surface tension 5mN / m).

[0073] The electronic ink was spin-coated onto a 10×10cm quartz glass substrate. The spin-coating parameters were set as follows: a uniform coating speed of 500 r / min and a uniform coating time of 10 s; a spin-coating speed of 3000 r / min and a spin-coating time of 20 s. The substrate was dried at 80°C for 15 min, heated at 100°C for 15 min, and heated at 120°C for 15 min on a heating plate. The pretreated film was then heated to 700°C at a heating rate of 2°C / min and heat-treated under an argon atmosphere for 1 h to obtain a vanadium dioxide film.

[0074] Example 3

[0075] This embodiment provides a method for preparing vanadium dioxide-based particle-free printed electronic ink, including the following steps:

[0076] Step S1: Dissolve 10 parts of complexing agent ethanolamine in 65 parts of solvent (35 parts of water and 30 parts of triethylene glycol), then add 6 parts of vanadium precursor ammonium metavanadate and mix evenly to obtain vanadium-based ink.

[0077] Step S2: Add 5 parts of reducing agent tartaric acid and 1 part of organic additive ethyl cellulose to the vanadium-based ink and stir to dissolve (temperature 15°C, time 10h), filter, and obtain vanadium dioxide-based particle-free printed electronic ink (viscosity 20mPa·s, surface tension 10mN / m).

[0078] The electronic ink was spin-coated onto a 10×10cm quartz glass substrate. The spin-coating parameters were set as follows: a uniform coating speed of 500 r / min and a uniform coating time of 10 s; a spin-coating speed of 3000 r / min and a spin-coating time of 20 s. The substrate was dried at 80°C for 15 min, heated at 100°C for 15 min, and heated at 120°C for 15 min on a heating plate. The pretreated film was then heated to 700°C at a heating rate of 2°C / min and heat-treated under an argon atmosphere for 1 h to obtain a vanadium dioxide film.

[0079] Example 4

[0080] This embodiment provides a method for preparing vanadium dioxide-based particle-free printed electronic ink, including the following steps:

[0081] Step S1: Dissolve 10 parts of complexing agent ethanolamine in 65 parts of solvent (35 parts of water and 30 parts of triethylene glycol), then add 6 parts of vanadium precursor ammonium metavanadate and mix evenly to obtain vanadium-based ink.

[0082] Step S2: Add 6 parts of reducing agent ascorbic acid and 1 part of organic additive ethyl cellulose to the vanadium-based ink and stir to dissolve (temperature 20°C, time 18h), filter, and obtain vanadium dioxide-based particle-free printed electronic ink (viscosity 30mPa·s, surface tension 20mN / m).

[0083] The electronic ink was spin-coated onto a 10×10cm quartz glass substrate. The spin-coating parameters were set as follows: a uniform coating speed of 500 r / min and a uniform coating time of 10 s; a spin-coating speed of 3000 r / min and a spin-coating time of 20 s. The substrate was dried at 80°C for 15 min, heated at 100°C for 15 min, and heated at 120°C for 15 min on a heating plate. The pretreated film was then heated to 700°C at a heating rate of 2°C / min and heat-treated under an argon atmosphere for 1 h to obtain a vanadium dioxide film.

[0084] Example 5

[0085] This embodiment provides a method for preparing vanadium dioxide-based particle-free printed electronic ink, including the following steps:

[0086] Step S1: Dissolve 10 parts of complexing agent ethanolamine in 65 parts of solvent (35 parts of water and 30 parts of triethylene glycol), then add 6 parts of vanadium precursor ammonium metavanadate and mix evenly to obtain vanadium-based ink.

[0087] Step S2: Add 8 parts of reducing agent (6 parts of tartaric acid and 2 parts of formic acid) and 1 part of organic additive ethyl cellulose to the vanadium-based ink and stir to dissolve (temperature 15°C, time 16h), filter, and obtain vanadium dioxide-based particle-free printed electronic ink (viscosity 25mPa·s, surface tension 15mN / m).

[0088] The electronic ink was spin-coated onto a 10×10cm quartz glass substrate. The spin-coating parameters were set as follows: a uniform coating speed of 500 r / min and a uniform coating time of 10 s; a spin-coating speed of 3000 r / min and a spin-coating time of 20 s. The substrate was dried at 80°C for 15 min, heated at 100°C for 15 min, and heated at 120°C for 15 min on a heating plate. The pretreated film was then heated to 700°C at a heating rate of 2°C / min and heat-treated under an argon atmosphere for 1 h to obtain a vanadium dioxide film.

[0089] Example 6

[0090] This embodiment provides a method for preparing vanadium dioxide-based particle-free printed electronic ink, including the following steps:

[0091] Step S1: Dissolve 10 parts of complexing agent ethanolamine in 65 parts of solvent (35 parts of water and 30 parts of triethylene glycol), then add 15 parts of vanadium precursor ammonium metavanadate and mix evenly to obtain vanadium-based ink.

[0092] Step S2: Add 6 parts of reducing agent tartaric acid and 1 part of organic additive ethyl cellulose to the vanadium-based ink and stir to dissolve (temperature 20°C, time 12h), filter, and obtain vanadium dioxide-based particle-free printed electronic ink (viscosity 30mPa·s, surface tension 25mN / m).

[0093] The electronic ink was spin-coated onto a 10×10cm quartz glass substrate. The spin-coating parameters were set as follows: spin speed 3000 r / min, spin time 20 s. The film was dried at 80°C for 15 min, heated at 100°C for 15 min, and heated at 120°C for 15 min on a heating plate. The pretreated film was then heated to 300°C at a heating rate of 1°C / min and heat-treated in air for 1 h. After natural cooling, the film was placed in an argon atmosphere and heated to 700°C at a heating rate of 2°C / min for 1 h to obtain a vanadium dioxide film.

[0094] Example 7

[0095] This embodiment provides a method for preparing vanadium dioxide-based particle-free printed electronic ink, including the following steps:

[0096] Step S1: Dissolve 70 parts of complexing agent triethanolamine in 90 parts of solvent (80 parts of water and 10 parts of glycerol), then add 15 parts of vanadium precursor (10 parts of acetylacetone vanadium oxide and 5 parts of ammonium metavanadate) and mix evenly to obtain vanadium-based ink.

[0097] Step S2: Add 10 parts of reducing agent tartaric acid and 10 parts of organic additive ethyl cellulose to the vanadium-based ink and stir to dissolve (temperature 15°C, time 18h), filter, and obtain vanadium dioxide-based particle-free printed electronic ink (viscosity 35mPa·s, surface tension 30mN / m).

[0098] The electronic ink was spin-coated onto a 10×10cm quartz glass substrate. The spin-coating parameters were set as follows: a uniform coating speed of 500 r / min and a uniform coating time of 10 s; a spin-coating speed of 3000 r / min and a spin-coating time of 20 s. The substrate was dried at 80°C for 15 min, heated at 100°C for 15 min, and heated at 120°C for 15 min on a heating plate. The pretreated film was then heated to 700°C at a heating rate of 2°C / min and heat-treated under an argon atmosphere for 1 h to obtain a vanadium dioxide film.

[0099] Comparative Example 1

[0100] The difference between this comparative example and Example 1 is that the vanadium precursor was changed to 2.5 parts of ammonium metavanadate.

[0101] Comparative Example 2

[0102] The difference between this comparative example and Example 1 is that the vanadium precursor was changed to 20 parts of metavanadate.

[0103] Comparative Example 3

[0104] The difference between this comparative example and Example 1 is that 10 parts of the complexing agent triethanolamine are not added to the ink.

[0105] Comparative Example 4

[0106] The difference between this comparative example and Example 1 is that no 2 parts of the reducing agent tartaric acid are added to the ink.

[0107] Comparative Example 5

[0108] The difference between this comparative example and Example 1 is that no part of the organic additive ethyl cellulose is added to the ink.

[0109] Comparative Example 6

[0110] The difference between this comparative example and Example 1 is that the solvent was changed to 5 parts of glycerol.

[0111] Comparative Example 7

[0112] The difference between this comparative example and Example 1 is that the solvent was changed to 150 parts of glycerol.

[0113] Test method:

[0114] (1) Storage stability of electronic ink: Store at room temperature away from light and record the number of days that stratification occurs.

[0115] (2) Uniformity of vanadium dioxide film: The height difference between the vanadium dioxide film and the quartz glass substrate in the examples and comparative examples will form a step. The step height between the substrate and the film was measured using an optical profilometer (model ContourX-100, Bruker, USA). The uniformity and flatness of the film were judged by comparing the step height between 10 points.

[0116] Table 1 Performance Test Results

[0117]

[0118] Compared to Example 1, in Comparative Example 1, the vanadium precursor was changed to 2.5 parts of ammonium metavanadate. Due to the insufficient amount of vanadium precursor and lack of compounding, the ink storage stability decreased, and the uniformity of the formed film was poor. Compared to Example 1, in Comparative Example 2, the vanadium precursor was changed to 20 parts of ammonium metavanadate. Due to the excessive amount of vanadium precursor and lack of compounding, the ink storage stability decreased, and the uniformity of the formed film was poor, with obvious particles. Compared to Example 1, in Comparative Example 3, 10 parts of the complexing agent triethanolamine were not added to the ink. The lack of the complexing agent reduced the ink storage stability, and the uniformity of the formed film was poor. Compared to Example 1, in Comparative Example 4, 2 parts of reducing agent were not added to the ink. The ink lacks the complexing effect of tartaric acid, resulting in reduced ink storage stability and noticeable film particle formation. Compared to Example 1, Comparative Example 5 did not include 1 part of the organic additive ethyl cellulose, leading to reduced ink storage stability and poor film uniformity. Compared to Example 1, Comparative Example 6 used 5 parts of glycerol as the solvent, resulting in reduced ink storage stability and poor film uniformity due to insufficient solvent usage and lack of compounding. Compared to Example 1, Comparative Example 7 used 150 parts of glycerol as the solvent, resulting in reduced ink storage stability and poor film uniformity due to excessive solvent usage and lack of compounding.

Claims

1. A method for preparing a vanadium dioxide-based particle-free printed electronic ink, characterized in that, By weight, the following steps are included: Step S1: Dissolve 10-70 parts of amine complexing agent in 20-90 parts of solvent, then add 5-15 parts of vanadium precursor and mix evenly to prepare vanadium-based ink; Step S2: Add 2-10 parts of reducing agent and 1-10 parts of organic additive ethyl cellulose to the vanadium-based ink, stir to dissolve, filter, and obtain vanadium dioxide-based particle-free printed electronic ink. The viscosity of the electronic ink is 10~40 mPa·s, and the surface tension is 5~40 mN / m; The vanadium precursor is selected from vanadium acetylacetonate and ammonium metavanadate in a mass ratio of (1~2):1; The solvent is water and alcohol in a mass ratio of (1~8):1; The alcohol is selected from one of ethylene glycol, glycerol, n-butanol, isopropanol, and triethylene glycol.

2. The method for preparing a vanadium dioxide-based particle-free printed electronic ink according to claim 1, characterized in that, The amine complexing agent is selected from one or more of 1,2-propanediamine, ethylenediamine, ethylamine, n-propylamine, isopropylamine, n-butylamine, n-hexylamine, ethanolamine, triethanolamine, isopropanolamine, diethylethylenediamine, and hydroxyethylethylenediamine. The reducing agent is selected from one or more of glucose, tartaric acid, oxalic acid, ascorbic acid, citric acid, formic acid, and formaldehyde.

3. A vanadium dioxide-based particle-free printed electronic ink, characterized in that, It is prepared by the preparation method according to any one of claims 1 to 2.

4. An application of a vanadium dioxide-based particle-free printed electronic ink, characterized in that, The process includes the following steps: (1) The electronic ink prepared by the preparation method according to any one of claims 1 to 2 is deposited on a substrate to obtain a film-containing substrate; (2) The film-containing substrate is first pretreated and then placed in a heat treatment furnace for stepwise annealing to obtain a vanadium dioxide film.

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