High-temperature stable wide bandgap metal oxide semiconductor electrocaloric film and method of making same

Abstract

The application relates to the technical field of electrothermal films, in particular to a high-temperature stable wide-bandgap metal oxide semiconductor electrothermal film and a manufacturing method thereof. A semiconductor precursor solution is sprayed on the surface of a substrate heated to a surface temperature reaching a semiconductor precursor solution pyrolysis deposition temperature by adopting a two-fluid atomization pyrolysis spraying process, the two-fluid in the two-fluid atomization pyrolysis spraying process is carrier gas and atomization gas, then ladder annealing is carried out after pyrolysis deposition is completed, and a semiconductor electrothermal film is prepared; the semiconductor precursor solution adopts an inorganic acid-organic complex acid double stabilizing system and inorganic silica sol additives are added in the inorganic acid-organic complex acid double stabilizing system. The application forms a stable sol with uniform particle size through controllable hydrolysis-polycondensation reaction, so that the crystal lattice growth after film formation is more uniform and orderly, the electrothermal emissivity is greater than 70%, the electrothermal conversion efficiency is as high as 98.5% or more, the heating is uniform, the power attenuation is less than negative 5% under long-term use at 500 DEG C, the service life is more than 10000 hours, and the application is suitable for high-temperature heating scenes.

Description

Technical Field

[0001] This invention relates to the field of electrothermal film technology, specifically to a high-temperature stable wide bandgap metal oxide semiconductor electrothermal film and its manufacturing method. Background Technology

[0002] Electrothermal materials are functional materials that can convert electrical energy into heat energy and are a core component of electric heating equipment. Based on their heating mechanism, electrothermal materials can be classified into resistance heating materials, far-infrared heating materials, light wave heating materials, microwave heating materials, and electromagnetic induction heating materials. Based on their appearance, electrothermal materials can be classified into electrothermal fibers, electrothermal wires (wires), heating tapes, electrothermal films, electrothermal foils, electrothermal sheets, electrothermal tubes (rods), electrothermal plates, electrothermal discs, electrothermal coils, etc.

[0003] Currently, the mainstream electrothermal materials on the market are resistance heating materials, such as resistance heating wires, resistance heating elements, and resistance heating plates. Their electrothermal conversion efficiency is extremely low, only about 70%, and they have problems such as being easily damaged, prone to leakage, prone to generating open flames, and unable to directly contact liquids, which greatly limits their application scenarios.

[0004] Far-infrared heating materials significantly improve electrothermal conversion efficiency, reaching over 90%, and the heating process is safer and more environmentally friendly, meeting a wider range of application needs. Currently, the most mature far-infrared heating materials are electrothermal film materials, mainly including carbon-based, metal-based, polymer-based, and semiconductor-based electrothermal films. Among these, carbon-based and polymer-based electrothermal films suffer from significant power attenuation at high temperatures, thus limiting their use to low-temperature conditions and failing to meet high-temperature application requirements. Metal-based electrothermal films are expensive and have complex molding processes, making them unsuitable for large-scale application. Semiconductor-based electrothermal films are cheaper than metal-based films and exhibit lower power attenuation at high temperatures compared to carbon-based and polymer-based films; however, in medium- and high-temperature applications, semiconductor-based films exhibit poor high-temperature stability, with power attenuation reaching negative 15% or more. Summary of the Invention

[0005] The purpose of this invention is to provide a method for manufacturing a high-temperature stable wide bandgap metal oxide semiconductor electrothermal film, which significantly reduces power attenuation in medium and high temperature application scenarios.

[0006] To achieve the above-mentioned objectives, the technical solution adopted by this invention is as follows:

[0007] A method for manufacturing a high-temperature stable wide bandgap metal-oxide-semiconductor electrothermal film includes the following steps:

[0008] Step 1: Spray the semiconductor precursor solution onto the substrate surface heated to the pyrolysis deposition temperature of the semiconductor precursor solution using a two-fluid atomization pyrolysis spraying process. The two fluids in the two-fluid atomization pyrolysis spraying process are carrier gas and atomizing gas.

[0009] Step 2: After pyrolysis deposition is completed, step annealing is performed to obtain a semiconductor electrothermal film;

[0010] The semiconductor precursor solution comprises the following components by weight: 50-70 parts of tin tetrachloride pentahydrate, 0.8-4.0 parts of doped metal chloride, 1-3 parts of inorganic acid, 1-4 parts of organic complexing acid, 0.2-1 parts of inorganic silica sol additive, 15-25 parts of alcohol solvent, and 0-30 parts of deionized water; the metal ion in the doped metal chloride is antimony and one or more of the following: manganese, iron, nickel, copper, zinc, titanium, bismuth, platinum, chromium, cobalt, and yttrium; the organic complexing acid is ethylenediaminetetraacetic acid, citric acid, glycine, or diethylenetriaminepentaacetic acid.

[0011] Preferably, the two-fluid atomization pyrolysis spraying process employs multiple thin coatings, with a single coating thickness ≤50nm and a total thickness of 0.05μm-3μm.

[0012] Preferably, the atomizing gas pressure to carrier gas pressure in the two-fluid atomization pyrolysis spraying process is 2.5-3:1.

[0013] Preferably, the substrate is a rectangular, square, or circular insulating material substrate, the precursor liquid delivery flow rate is 12.8 mL / min-19.2 mL / min, the flow rate is 0.8 m / s-1.2 m / s, the overlap rate is 60%-80%, and the axial transverse speed is controlled at 50 mm / s-350 mm / s.

[0014] Preferably, the manufacturing method further includes a step of screen printing insulating oil on the substrate surface before the substrate is stepped heated and a step of cleaning the insulating oil after the stepped annealing.

[0015] Preferably, the manufacturing method further includes a step of preparing electrodes on a semiconductor electrothermal film.

[0016] Preferably, the heating of the substrate is carried out in a stepped heating manner, which is preferably divided into four stages: 200-300℃, 300-400℃, 400-500℃, and 600-800℃, with a time of 120-180 seconds in each zone; the stepped annealing is divided into three stages: 600-650℃, 300-400℃, and 100-150℃.

[0017] The preparation of semiconductor precursor solutions follows the principle of "first mixing solvent and complexing acid to adjust pH → adding metal salt in batches → diluting with water → finally adding additives" to avoid local hydrolysis and ensure system homogeneity. The preparation process of semiconductor precursor solutions is as follows: S1, under stirring at room temperature, add organic complexing acid to alcohol solvent, stir until completely dissolved, and add inorganic acid dropwise to adjust the pH value; S2, add tin tetrachloride pentahydrate to the system in step S1, stir until completely dissolved, and then add doped metal chloride in batches, stirring after each addition to avoid local high concentrations that could lead to hydrolysis; S3, add deionized water to the system in step S2, stir, and then add inorganic silica sol additives, stirring to ensure that the silica sol is uniformly dispersed in the complexing sol; S4, after constant temperature, filter and use immediately or encapsulate for later use.

[0018] The present invention also provides a high-temperature stable wide bandgap metal oxide semiconductor electrothermal film prepared by the above-described manufacturing method.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] The present invention features a synergistic combination of component concentrations and proportions: the main source Sn salt has the highest proportion (50-70 parts), ensuring the main crystal structure; the dopant source, complexing agent, auxiliary agent, and solvent are matched in precise mass ratios, which avoids the residual carbon impurities after pyrolysis caused by excessive complexing agent, and also prevents severe crystal distortion caused by excessive dopant. At the same time, the addition of a small amount of silica sol (0.2-1 parts) does not affect the semiconductor conductivity, thus achieving a balance of various performance indicators.

[0021] This invention introduces multiple dopant ions into the SnO2 lattice as the multi-doping source, thereby controlling lattice defects and oxygen vacancy concentrations, optimizing carrier concentration and resistivity, and improving the conductivity, heat resistance, and performance stability of the semiconductor film. Each dopant has a clearly defined role: antimony trichloride provides Sb... 3+ / Sb 5+ It is an n-type doped host ion, replacing Sn. 4+ Substitutional doping occurs when substances enter the crystal lattice, significantly increasing carrier concentration and reducing film resistivity. Doping with metal chlorides such as manganese chloride tetrahydrate, ferric chloride hexahydrate, nickel chloride hexahydrate, cuprous chloride, and zinc chloride hexahydrate, along with multi-element transition metal / main group metal ion doping, synergistically regulates the degree of lattice distortion, inhibits grain boundary growth, and improves the thermal stability and mechanical strength of the film, while simultaneously optimizing the photoelectric response and electrothermal conversion efficiency of the semiconductor film.

[0022] This invention enables the rapid dissociation of chlorides of metals such as Sn, Sb, Mn, and Fe into metal ions in an acidic water-alcohol mixed solvent, achieving stable dissociation and molecular-level dispersion. The alcohol solvent, such as ethanol, is used to dissolve the metal chlorides, while water is used to dilute the concentration. The ratio of these two solvents is well-suited to the viscosity of the multi-metal salt + complexing agent system, giving the semiconductor precursor solution both good solubility and coatability. It can form a uniform wet film on the substrate during spin coating, spray coating, and blade coating. The solvent gradient evaporation (ethanol evaporates first, water evaporates later) avoids morphological defects during the wet film drying process.

[0023] This invention forms a dual hydrolysis control system of "chelation complexation + acid inhibition", in which organic complex acid and Sn 4+ It forms stable chelate complexes with various doped metal ions, inhibiting the rapid hydrolysis of metal ions in aqueous solution and the formation of hydroxide precipitates due to steric hindrance, thus improving the storage stability of the semiconductor precursor solution. Through a controllable hydrolysis-condensation reaction, it forms a stable sol with uniform particle size, resulting in more uniform and ordered lattice growth after film formation; inorganic acids provide... Adjusting the pH of the system to acidic levels further inhibits the hydrolysis tendency of metal ions and forms a dual-stabilized system of inorganic acid and complexing agent with organic complexing acid. The two work synergistically to ensure that the semiconductor precursor solution does not precipitate or separate at room temperature, greatly improving storage stability. At the same time, it ensures that the hydrolysis-condensation rate is controllable, laying the foundation for film uniformity, and without the introduction of additional impurities, the film layer has high purity after pyrolysis.

[0024] This invention provides amorphous SiO2 nanoparticles as an inorganic framework additive in an inorganic silica sol system. After pyrolysis, the SiO2 is uniformly dispersed in the interstices of the SnO2 lattice, improving the mechanical hardness, wear resistance, and high-temperature resistance of the semiconductor film. At the same time, it inhibits crystallization cracking of the film layer at high temperatures, improves the compactness of the film, and does not affect the conductive path of the lattice, achieving a synergistic effect of "reinforcement without performance loss". This fills the technical gap of traditional tin-based precursor liquid film formation that is "functionalized but without reinforcement", and expands the application scenarios of precursor liquid under high temperature and high wear conditions.

[0025] The advantages of stepped annealing compared to direct high-temperature quenching are as follows: (1) Eliminating the core hidden danger of film cracking: There is lattice stress during the crystallization process of the nascent film. The difference in thermal expansion coefficient between the film and the glass substrate will lead to thermal stress. Quenching will cause the two stresses to concentrate instantly, resulting in film cracking and edge warping. Stepped annealing slowly releases stress, which is the key to avoiding film failure; (2) Achieving precise control of electrothermal performance: The 600-650℃ crystallization stage of stepped annealing ensures the integrity of the SnO2 crystal phase and uniform doping ions. The oxygen vacancy concentration is precisely controlled in the 300-400℃ stage. The shape is stabilized in the 100-150℃ stage. Compared with the oxygen vacancy caused by quenching, the stepped annealing can achieve more stable results. Disorders and lattice distortions result in lower resistivity and improved stability of the film (resistivity drift rate <5% during use); (3) Improved thermal stability and lifespan of the film: SnO2 lattice density is high and grain boundary defects are few after step annealing. When the electric heating film is working at high temperature for a long time (300-500℃), it is not easy for lattice relaxation or grain boundary growth to occur. Compared with the film layer that is cooled suddenly, the lifespan is increased by more than 3 times; (4) Ensure the smoothness of the film layer surface: slow cooling allows the residual gas and a small amount of molten phase in the film layer to gradually escape and solidify, avoiding surface unevenness and whisker growth caused by sudden cooling. The surface roughness of the film layer is lower, and the surface resistance uniformity of the electric heating film is improved.

[0026] The electrothermal film product obtained by this invention has an electrothermal emissivity of >70%, an electrothermal conversion efficiency of over 98.5%, uniform heating, a power attenuation rate of less than -5% during long-term use at 500℃, and a lifespan of over 10,000 hours, making it suitable for high-temperature heating scenarios. Detailed Implementation Example 1

[0027] This embodiment provides a method for manufacturing a high-temperature stable wide bandgap metal oxide semiconductor electrothermal film, comprising the following steps: substrate glass cleaning → screen printing of an insulating layer → plasma cleaning → stepped heating of the substrate → two-fluid atomization pyrolysis deposition to form a film → stepped annealing → insulating layer cleaning → electrode preparation → cooling → electrical aging treatment. In this embodiment, the substrate is a square rigid microcrystalline glass plate. In other examples, the substrate material can also be an insulating material substrate such as an alumina ceramic plate or an aluminum nitride ceramic plate, with a rectangular or circular shape.

[0028] In the substrate glass cleaning step, a glass cleaner is used to remove grease and contaminants from the substrate glass surface. In the screen printing insulation layer step, insulating oil is automatically screen-printed onto the glass substrate using a screen printing machine to form an insulating pattern. In the plasma cleaning step, a plasma cleaner is used to clean the glass surface, improving the adhesion of the electrothermal film. In the insulation layer cleaning step, a cleaning machine is used to clean the insulating layer of the mask. In the motor fabrication step, a screen printing machine and silver paste electrodes are used to screen-print silver oxide paste onto the semiconductor electrothermal film according to the designed electrode screen. The screen-printed electrodes are then sent to a heating furnace and an annealing furnace for heating and annealing. In the power-on aging treatment step, a heating element life accelerated aging comprehensive analyzer is used for 16 hours of power-on aging, applying 1.15 times the rated voltage. The voltage is stabilized every 60 minutes during the aging process, and the material is cooled to room temperature after aging.

[0029] In the stepped heating step, the cleaned glass substrate is fed into a tunnel drying oven and heated zone by zone. The tunnel drying oven has four temperature zones: 200-300℃, 300-400℃, 400-500℃, and 600-800℃, with each zone lasting 120-180 seconds. Heating requires that the temperature difference between any point on the substrate surface be ≤±10℃ and should not exceed 800℃, as this can lead to softening and deformation of the glass substrate, excessive growth of SnO2 grains, and increased grain boundary resistance. Glass has a low coefficient of thermal expansion and high brittleness; directly heating from room temperature to the pyrolysis deposition temperature can cause the substrate to instantly develop microcracks or even shatter due to thermal stress. Stepped heating allows the substrate to gradually adapt to temperature changes, eliminating the risk of thermal stress, optimizing the semiconductor precursor solution for film formation, and ensuring efficient pyrolysis and film formation. In this embodiment, the four zone temperatures are set to 250℃, 350℃, 450℃, and 800℃, with each zone lasting 140 seconds.

[0030] In the stepped annealing step, the goal is to optimize the SnO2-based lattice structure, eliminate internal stress in the film, and improve conductivity and thermal stability. The resulting film is a nascent film consisting of "amorphous material with a small amount of nanocrystals." Stepped cooling annealing is a "post-processing optimization" of the lattice and film structure, and the core mechanism is achieved in three stages:

[0031] 600-650℃ stage: Crystallization is complete and lattice rearrangement occurs. This temperature is the optimal crystallization temperature for SnO2-based solid solutions. The amorphous oxide in the nascent film transforms into tetragonal rutile SnO2 (the core conductive crystalline phase of the semiconductor electrothermal film), and doping occurs. The uniform incorporation of multi-metal ions into the SnO2 lattice forms substitutional doping, simultaneously eliminating grain boundary defects, increasing lattice density, and significantly reducing film resistivity. Furthermore, at this temperature, the interfacial bonding between the film and the substrate is further strengthened, resulting in a more uniform eutectic phase of SiO2 and SnO2. In this embodiment, 650℃ is used.

[0032] The 300-400℃ stage: Eliminating internal stress and regulating oxygen vacancies in the film layer. The temperature is reduced from 650℃ to 300℃, gradually matching the thermal expansion coefficients of the film layer and the glass substrate. Slow cooling releases lattice stress and thermal stress generated during crystallization, preventing cracking and warping due to uneven thermal shrinkage. Simultaneously, this temperature range allows for precise control of the oxygen vacancy concentration in the SnO2 lattice (the core carrier for conductivity in the electrothermal film), preventing excessive or insufficient oxygen vacancies caused by rapid cooling and ensuring a balance between carrier concentration and mobility. This embodiment uses 300℃.

[0033] 100-150℃ stage: Low-temperature shaping and performance stabilization. Cooling to 100℃ allows the crystallized SnO2 lattice to complete its "shaping," preventing lattice distortion caused by sudden cooling to room temperature. Simultaneously, it allows small amounts of residual gases (such as HCl and CO2) on the film surface to slowly escape, ensuring a smooth film surface. Finally, after cooling to room temperature, the film lattice structure, oxygen vacancy concentration, and interfacial bonding all reach a stable state, preventing resistivity drift due to structural relaxation during subsequent use. This embodiment uses 100℃.

[0034] The annealing peak temperature of this invention is slightly lower than the heating peak temperature in order to balance the crystallization effect and the protection of the substrate / film: 700-800℃ is the optimal temperature for the pyrolysis of the semiconductor precursor solution (ensuring complete decomposition of chlorides and thorough removal of complexing agents), but after coating, the film layer has already formed a nascent oxide. 600-650℃ is sufficient to allow it to complete crystallization and rearrangement, while avoiding the softening and deformation of the glass substrate caused by prolonged heating at 700-800℃. At the same time, it prevents the SnO2 lattice from growing excessively (excessively large grains will increase grain boundary resistance and reduce conductivity).

[0035] In the two-fluid atomization pyrolysis deposition film formation step, the flow rate (liquid supply per unit time) and velocity (liquid velocity at the nozzle outlet) of the semiconductor precursor liquid determine the "droplet deposition density per unit area". It needs to form a triangular balance with the atomization gas pressure and the axial lateral velocity to avoid "agglomeration due to excessive flow rate and discontinuity of film layer due to insufficient flow rate".

[0036] The two fluids are carrier gas and atomizing gas. The pressure of the two fluids determines the atomized particle size and the uniformity of droplet transport. For small substrates (<200×200mm), the atomizing gas pressure is 0.25-0.35MPa, while for large substrates (>400×400mm), the atomizing gas pressure is 0.35-0.45MPa. The carrier gas pressure is controlled at 0.10-0.20MPa, always more than 0.15MPa lower than the atomizing gas pressure. The ratio of atomizing gas pressure to carrier gas pressure is 2.5-3:1. Under this ratio, the droplet size distribution is the narrowest (CV≤15%), and there is no obvious diffusion during transport. This is the basis for uniform film formation, ensuring that the droplets can uniformly cover the edge of the substrate and avoid "thick in the center and thin at the edge". In this embodiment, the substrate is 400×400mm, the atomizing gas pressure is 0.3MPa, the carrier gas pressure is 0.12MPa, the atomizing gas pressure:carrier gas pressure = 2.5:1, the carrier gas is air, and the atomizing gas is the precursor liquid atomizing gas.

[0037] Flow rate directly determines film thickness; uneven flow rate leads to uneven transverse striations. Excessive flow rate results in insufficient atomization (droplets not completely broken up), causing localized aggregation. Insufficient flow rate prevents the formation of a continuous film layer on the substrate surface, resulting in pinholes. Quantitative calculation based on substrate area: Recommended flow rate (mL / min) = Substrate area (m² / min) 2 )×800~1200, for example: 400×400mm substrate (0.16m 2 The recommended flow rate is 0.16 × 800~1200 = 12.8-19.2 mL / min. In this example, the flow rate is 15 mL / min.

[0038] Flow velocity determines the "flight time" of droplets from the nozzle to the substrate. If the flow velocity is too slow, the droplets settle due to gravity during transport, resulting in more deposition at the bottom than at the top. If the flow velocity is too fast, the droplets have excessive kinetic energy upon impacting the substrate, causing them to bounce and be lost, resulting in insufficient deposition in some areas. Flow velocity (m / s) = flow rate (m³ / s) 3 / s) ÷ Nozzle outlet cross-sectional area (m²) 2 The flow rate is controlled between 0.8 and 1.2 m / s. In this embodiment, the flow rate is 0.88 m / s.

[0039] The lateral velocity (the speed at which the nozzle moves relative to the substrate) is the core of kinematic uniformity, determining the "dwell time of the nozzle at different positions on the substrate." It needs to be coordinated with flow rate and atomizing air pressure to eliminate "reciprocating spray streaks" and "edge buildup." Core requirements: Overlap rate = 60%-80%; Spray overlap rate (%) = [(effective spray width of the nozzle - single lateral movement step distance) ÷ effective spray width of the nozzle] × 100%. In this embodiment, the effective spray width of the nozzle is 400mm, and an overlap of 70% is required. Therefore, the single lateral movement step distance = 400 × (1 - 70%) = 120mm.

[0040] The transverse axis speed is controlled between 50-350 mm / s, more preferably 50-150 mm / s. A transverse axis speed of 100 mm / s is suitable for a flow rate of 15 mL / min. Defect control measures for abnormal speed: Too slow (<50 mm / s) will result in excessively long local residence time, droplet accumulation, excessively thick film, and agglomeration. The speed should be increased to the suitable range, or the precursor liquid flow rate should be reduced. Too fast (>150 mm / s) will result in excessively short residence time, discontinuous film, and numerous pinholes. The speed should be reduced, or the carrier gas pressure should be increased (to ensure droplet tracking). Speed ​​fluctuations will result in deep and shallow stripes in the reciprocating direction. In this case, a servo motor drive with a speed accuracy ≤±1 mm / s should be used. Additionally, since droplets at the substrate edge tend to diffuse outwards, leading to insufficient deposition, an edge deceleration program needs to be set: when the nozzle moves to 50 mm before the substrate edge, the speed is reduced by 20%-30% to extend the residence time and compensate for edge deposition.

[0041] Multiple thin coatings are used, with each coat having a thickness ≤50nm and a total thickness of 0.05μm-3μm. In this embodiment, the target film thickness is 2μm, requiring 40 coats at a thickness of 50nm per coat. A 3-5s interval is maintained between each coat to allow residual gas from the previous coat to escape completely and prevent reaction with droplets in the next coat. A single coat spraying time exceeding 20s will inevitably lead to localized accumulation. With a single thick coat, droplets tend to agglomerate and flow on the substrate surface, and pyrolysis is incomplete (the bottom droplets are covered by the upper layer, preventing rapid solvent evaporation). With multiple thin coats, each thin liquid film can be rapidly and completely pyrolyzed, resulting in progressively stacked film layers and significantly improved uniformity.

[0042] Regarding the semiconductor precursor solution, an inorganic acid-organic complex acid dual stabilization system is adopted, and an inorganic silica sol additive is added to it.

[0043] Specifically, in this embodiment, the semiconductor precursor solution comprises the following components by weight: 60 parts tin tetrachloride pentahydrate, 0.8 parts antimony trichloride, 0.35 parts manganese chloride tetrahydrate, 0.1 parts ferric chloride hexahydrate, 0.6 parts nickel chloride hexahydrate, 0.2 parts cuprous chloride, 0.05 parts zinc chloride hexahydrate, 2 parts hydrochloric acid, 3.5 parts ethylenediaminetetraacetic acid (EDTA), 1 part inorganic silica sol additive, 18 parts anhydrous ethanol, and 10 parts deionized water. In other examples, hydrochloric acid can be replaced with inorganic acids such as glacial acetic acid, formic acid, and sulfuric acid as pH adjusters, and EDTA can be replaced with organic complex acids such as glycine, citric acid, and diethylenetriaminepentaacetic acid (DTPA).

[0044] The preparation of semiconductor precursor solutions follows the principle of "mixing solvent and complexing acid first, then adjusting acidity → adding metal salt in batches → diluting with water → finally adding additives" to avoid localized hydrolysis and ensure system homogeneity. The specific preparation process is as follows:

[0045] (1) Raw material pretreatment: All raw materials are of electronic grade purity, deionized water is 18.2 MΩ•cm ultrapure water, and silica sol is ultrasonically dispersed in advance until no agglomeration.

[0046] (2) Solvent and complexing agent premixing: Add anhydrous ethanol to a three-necked flask, add organic complexing acid while stirring at room temperature (300-500 r / min, 400 r / min in this example), stir until completely dissolved, then add inorganic acid dropwise, stir, and adjust the acidity of the system to pH 1-3, in this example, the pH is adjusted to 3.

[0047] (3) Add metal salts in batches: First add the main source tin tetrachloride pentahydrate and stir until completely dissolved. Then add the doped metal salts in batches in the order of antimony trichloride → manganese chloride → ferric chloride → nickel chloride → cuprous chloride → zinc chloride. Stir for 15 minutes after each addition to avoid excessive local concentration leading to hydrolysis.

[0048] (4) Addition and dispersion of additives: Add deionized water to the above system, stir and then add inorganic silica sol additives, increase the stirring speed to 600-800 r / min (800 r / min in this example), and stir to make the silica sol uniformly dispersed in the complex sol.

[0049] (5) Constant temperature aging: Place the system in a water bath at 70-75℃ and stir at a constant temperature to allow the complexation reaction between metal ions and organic complex acids to reach equilibrium and form a stable sol system.

[0050] (6) Fine filtration of finished product: The aged sol is vacuum filtered through a 0.22μm polytetrafluoroethylene filter membrane to remove a small amount of undissolved particles or agglomerates, resulting in a clear, transparent, uniform and stable semiconductor precursor solution, which is then sealed and stored away from light. Example 2

[0051] This embodiment provides a method for manufacturing a high-temperature stable wide bandgap metal oxide semiconductor electrothermal film, including the following steps: substrate glass cleaning → screen printing of insulating layer → plasma cleaning → stepped heating of substrate → two-fluid atomization pyrolysis deposition film formation → stepped annealing → insulating layer cleaning → electrode preparation → cooling → aging treatment.

[0052] Compared to Example 1, this example mainly involves parameter adjustments in the two-fluid atomization pyrolysis deposition film formation step and the stepped annealing step, as detailed below; all other parameters remain the same:

[0053] First, in the stepped annealing process, the temperature settings for the three stages are changed to 620℃, 350℃, and 150℃ respectively.

[0054] Second, in the film formation step, the substrate is 400×400mm, the atomizing gas pressure is 0.35MPa, the carrier gas pressure is 0.13MPa, the atomizing gas pressure:carrier gas pressure = 2.7:1; the flow rate is 18mL / min, the flow velocity is 1.0m / s; the single transverse step is 120mm, the axial transverse speed is 120mm / s; the target film thickness is 2μm, and the single pass is 50nm.

[0055] The semiconductor precursor solution comprises the following components by weight: 55 parts tin tetrachloride pentahydrate, 0.6 parts antimony trichloride, 0.2 parts manganese chloride tetrahydrate, 0.1 parts ferric chloride hexahydrate, 0.5 parts nickel chloride hexahydrate, 0.4 parts cuprous chloride, 0.05 parts zinc chloride hexahydrate, 1.5 parts hydrochloric acid, 3 parts ethylenediaminetetraacetic acid, 0.8 parts inorganic silica sol additive, 15 parts anhydrous ethanol, and 18 parts deionized water.

[0056] Film thickness uniformity: A thickness gauge was used to measure the film thickness at five points in a quincunx pattern (one point at the center and one point at each of the four corners). The thickness at each measurement point was then calculated, along with the average and standard deviation, and finally the coefficient of variation. The film thickness difference was ≤ ±3%.

[0057] Surface resistivity uniformity: A sheet resistance meter is used to measure the sheet resistance at nine points, and the average value, standard deviation and coefficient of variation are calculated.

[0058] Electrothermal emissivity and electrothermal conversion efficiency were tested according to GB / T 28204-2011 (film heating elements for household and similar uses) and GB / T 7287-2008 (infrared radiation heaters).

[0059] The electrothermal cycling performance was tested according to JG / T 286-2010 "Low Temperature Radiant Electrothermal Films" at the working temperature, with 15 cycles of power-on.

[0060] Power attenuation rate, in accordance with Clause 6.12 of GB / T 28204-2011 "Diameter Heating Elements for Household and Similar Purposes".

[0061] Mechanical strength, according to GB / T 7287-2008 (Infrared Radiation Heater) test method.

[0062] The semiconductor electrothermal films of Examples 1-2 were tested respectively, and the test results are shown in Table 1.

[0063] Table 1: Test Results of Semiconductor Electrothermal Films in Examples 1-2 of the Present Invention

[0064]

[0065] The foregoing has shown and described the basic principles, main features and advantages of this invention. Those skilled in the art should understand that this invention is not limited to the above embodiments. The embodiments and descriptions in the specification are only illustrative of the principles of this invention. Various changes and modifications can be made to this invention without departing from the spirit and scope of this invention. All such changes and modifications fall within the scope of this invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A method of manufacturing a high-temperature stable wide bandgap metal oxide semiconductor electrocaloric film, characterized in that: Includes the following steps: Step 1: Spray the semiconductor precursor liquid onto the substrate surface that has been heated in stages to a surface temperature that reaches the pyrolysis deposition temperature of the semiconductor precursor liquid using a two-fluid atomization pyrolysis spraying process. The two fluids in the two-fluid atomization pyrolysis spraying process are carrier gas and atomizing gas. Step 2: After pyrolysis deposition is completed, step annealing is performed to obtain a semiconductor electrothermal film; The peak annealing temperature is lower than the peak heating temperature. The stepped annealing is divided into three stages: 600-650℃, 300-400℃, and 100-150℃, and finally cooled to room temperature. The semiconductor precursor solution comprises the following components by weight: 50-70 parts of tin tetrachloride pentahydrate, 0.8-4.0 parts of doped metal chloride, 1-3 parts of inorganic acid, 1-4 parts of organic complexing acid, 0.2-1 parts of inorganic silica sol additive, 15-25 parts of alcohol solvent, and 0-30 parts of deionized water; the metal ion in the doped metal chloride is antimony and one or more of the following: manganese, iron, nickel, copper, zinc, titanium, bismuth, platinum, chromium, cobalt, and yttrium; the organic complexing acid is ethylenediaminetetraacetic acid, citric acid, glycine, or diethylenetriaminepentaacetic acid.

2. The method of claim 1, wherein the high-temperature stable wide bandgap metal oxide semiconductor electrocaloric film is formed by a process comprising: depositing a metal oxide semiconductor film on a substrate; and annealing the metal oxide semiconductor film at a temperature of 300 °C to 600 °C in an atmosphere comprising oxygen. The two-fluid atomization pyrolysis spraying process employs multiple thin coatings, with a single coating thickness ≤50nm and a total thickness of 0.05μm-3μm.

3. The method of claim 1, wherein the high-temperature stable wide bandgap metal oxide semiconductor electrocaloric film is formed by a process comprising: depositing a metal oxide semiconductor film on a substrate; and annealing the metal oxide semiconductor film at a temperature of 300 °C to 600 °C in an atmosphere comprising oxygen. In the two-fluid atomization pyrolysis spraying process, the atomizing gas pressure to carrier gas pressure ratio is 2.5-3:

1.

4. The method of claim 1, wherein the high-temperature stable wide bandgap metal oxide semiconductor electrocaloric film is formed by a process comprising: depositing a metal oxide semiconductor film on a substrate; and annealing the metal oxide semiconductor film at a temperature of 300 °C to 600 °C in an atmosphere comprising oxygen. The substrate is a rectangular or circular insulating material substrate, the precursor liquid delivery flow rate is 12.8 mL / min-19.2 mL / min, the flow rate is 0.8 m / s-1.2 m / s, the overlap rate is 60%-80%, and the axial transverse speed is controlled at 50 mm / s-350 mm / s.

5. The method of claim 1, wherein the high-temperature stable wide bandgap metal oxide semiconductor electrocaloric film is formed by a process comprising: depositing a metal oxide semiconductor film on a substrate; and annealing the metal oxide semiconductor film at a temperature of 300 °C to 600 °C in an atmosphere comprising oxygen. The manufacturing method also includes a step of screen printing insulating oil on the substrate surface before the substrate is stepped heated, and a step of cleaning the insulating oil after the stepped annealing.

6. The method of claim 1, wherein the high-temperature stable wide bandgap metal oxide semiconductor electrocaloric film is formed by a process comprising: depositing a metal oxide semiconductor film on a substrate; and annealing the metal oxide semiconductor film at a temperature of 300 °C to 600 °C in an atmosphere comprising oxygen. The manufacturing method also includes the step of preparing electrodes on a semiconductor electrothermal film.

7. The method of claim 1, wherein the high-temperature stable wide bandgap metal oxide semiconductor electrocaloric film is formed by a process comprising: depositing a metal oxide semiconductor film on a substrate; and annealing the metal oxide semiconductor film at a temperature of 300 °C to 600 °C in an atmosphere comprising oxygen. The preparation process of the semiconductor precursor solution is as follows: S1, under stirring at room temperature, add the organic complex acid to the alcohol solvent, stir until completely dissolved, add inorganic acid dropwise, and adjust the pH value. S2. Add tin tetrachloride pentahydrate to the system in step S1, stir until completely dissolved, and then add the doped metal chloride in batches. Stir after each doped metal chloride is added to avoid local high concentrations that could lead to hydrolysis. S3. Add deionized water to the system in step S2, stir, and then add the inorganic silica sol additive. Stir to ensure that the silica sol is evenly dispersed in the complexed sol. S4. After constant temperature, filter and use immediately or package for later use.

8. A high-temperature stable wide bandgap metal oxide semiconductor electrothermal film prepared by the manufacturing method according to any one of claims 1 to 7.

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