WO2023160156A1

WO2023160156A1 - Devices equipped with transparent film heaters and methods for preparing the same

Info

Publication number: WO2023160156A1
Application number: PCT/CN2022/139549
Authority: WO
Inventors: Boda ZHENG; Jie Chen; Cong Wang; Hongwu CHEN
Original assignee: Zhejiang Dahua Technology Co., Ltd.
Priority date: 2022-02-28
Filing date: 2022-12-16
Publication date: 2023-08-31

Abstract

The present disclosure relates to devices equipped with transparent film heaters and methods for preparing the devices and the transparent film heaters. The devices may include a substrate and a transparent film heater deposited on the substrate and configured to heat the substrate. The transparent film heater may include a heating layer configured to generate heat and an isolation layer deposited between the substrate and the heating layer. The isolation layer may be configured to reduce heat conduction from the heating layer to the substrate.

Description

DEVICES EQUIPPED WITH TRANSPARENT FILM HEATERS AND METHODS FOR PREPARING THE SAME

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to Chinese Patent Application No. 202221001577.0, filed on April 27, 2022, Chinese Patent Application No. 202210279673. X, filed on March 22, 2022, and Chinese Patent Application No. 202210188205.1, filed on February 28, 2022, the contents of each of which are incorporated herein by reference in their entirety.

TECHNICAL FIELD

The present disclosure relates to the technical field of electric heating devices, and in particular, to devices equipped with transparent film heaters and methods for preparing the devices and the transparent film heaters.

BACKGROUND

Devices equipped with transparent film heaters are mainly used in scenarios that are prone to be disturbed by frosting or fogging. Examples include camera windows, car windows, transparent glass curtain walls, etc. which are equipped with transparent film heaters to defrost, defog, and maintain a high light transmittance. However, transparent film heaters prepared by conventional processes often possess poor properties, such as high heat loss, low optoelectronic properties, low stability, or the like, thereby reducing the effectiveness of defrosting and defogging. Therefore, it is desirable to provide methods for preparing transparent film heaters with improved properties and devices equipped with the transparent film heaters.

SUMMARY

An aspect of the present disclosure relates to a device. The device may include a substrate and a transparent film heater deposited on the substrate and configured to heat the substrate. The transparent film heater may include a heating layer configured to generate heat and an isolation layer deposited between the substrate and the heating layer. The isolation layer may be configured to reduce heat conduction from the heating layer to the substrate.

In some embodiments, the isolation layer may include a silica aerogel-resin composite material.

In some embodiments, a thickness of the isolation layer may be 0.8-2.0 μm.

In some embodiments, the heating layer may include metal nanowires.

In some embodiments, a thickness of the heating layer may be 100-1000 nm. The diameters of the metal nanowires may be 10-100 nm. The aspect ratios of the metal nanowires may be 200-2000.

In some embodiments, the metal nanowires may include silver nanowires.

In some embodiments, the heating layer may include an indium tin oxide layer (ITO) , a carbon black layer, a conductive graphite layer, a carbon nanotube layer, a graphene layer, a silver layer, and/or a copper layer.

In some embodiments, the transparent film heater may further include a protective layer deposited on a side of the heating layer away from the substrate.

In some embodiments, a thickness of the protective layer may be 30-50 nm.

Another aspect of the present disclosure relates to a method for preparing a transparent film heater. The method may include providing a substrate; activating the substrate by surface modification; coating an isolation layer on the activated substrate; curing the isolation layer; coating a heating layer on a side of the isolation layer away from the substrate, wherein the heating layer is configured to generate heat, and the isolation layer is configured to reduce heat conduction from the heating layer to the substrate; and curing the heating layer.

A further aspect of the present disclosure relates to a method for preparing a transparent film heater. The method may include preparing a dispersion of silver nanocrystal seeds by starting a reaction in a first mixture including a first silver source, a reducing agent, a protecting agent, and a polar solvent; preparing a first dispersion of silver nanowires by irradiating a second mixture including the dispersion of the silver nanocrystal seeds, a second silver source, and a thermoset resin by ultraviolet light; removing the polar solvent from the first dispersion of silver nanowires; preparing a second dispersion of silver nanowires by mixing a third mixture including a curing accelerator with the as-processed dispersion of silver nanowires; activating a substrate by surface modification; and preparing the transparent film heater by curing the second dispersion of silver nanowires deposited on the activated substrate.

In some embodiments, the reducing agent may include an aldehyde-based acid anhydride.

In some embodiments, the aldehyde-based acid anhydride may include 5-Formyl-2-thiopheneboronic acid and/or 2-Formylfuran-5-boronic acid.

In some embodiments, a mass fraction of the reducing agent in the first mixture may be 1%-10%.

In some embodiments, the silver nanocrystal seeds may be silver nanoparticles with grain sizes of 2-10 nm.

In some embodiments, the first silver source or the second silver source may include silver nitrate, silver acetate, silver perchlorate, and/or silver fluoride. The protecting agent may include polyvinylpyrrolidone and/or cetyltrimethylammonium bromide. The thermoset resin may include bisphenol resin, silicone resin, polyimide, and/or polyurethane. The curing accelerator may include 2-Ethyl-4-methylimidazole and/or 2, 4, 5-tris (dimethylaminomethyl) phenol.

In some embodiments, a mass fraction of the first silver source in the first mixture may be 0.08%-2%. A mass fraction of the protecting agent in the first mixture may be 0.2%-4%. A mass fraction of the second silver source in the second mixture may be 0.08%-2%. A mass fraction of the thermoset resin in the dispersion of silver nanowires may be 30%-70%. A mass fraction of the curing accelerator in the second dispersion of silver nanowires may be 0.08%-2%.

In some embodiments, an irradiation time of the ultraviolet light to the second mixture may be 12h-36h.

In some embodiments, a curing temperature of the second dispersion of silver nanowires may be 130℃-220℃. A curing time of the second dispersion of silver nanowires may be 10min-150min.

A further aspect of the present disclosure relates to a device. The device may include a substrate and a transparent film heater deposited on a surface of the substrate and configured to heat the substrate. The transparent film heater may be prepared by preparing a dispersion of silver nanocrystal seeds by starting a reaction in a first mixture including a first silver source, a reducing agent, a protecting agent, and a polar solvent; preparing a first dispersion of silver nanowires by irradiating a second mixture including the dispersion of the silver nanocrystal seeds, a second silver source, and a thermoset resin by ultraviolet light; removing the polar solvent from the first dispersion of silver nanowires; preparing a second dispersion of silver nanowires by mixing a third mixture including a curing accelerator with the as-processed dispersion of silver nanowires; activating a substrate by surface modification; and preparing the transparent film heater by curing the second dispersion of silver nanowires deposited on the activated substrate.

A further aspect of the present disclosure relates to a method for preparing a transparent film heater. The method may include providing an arbitrary shaped substrate; activating the arbitrary shaped substrate by surface modification; preparing a silver nanowire layer with a random network structure on the activated arbitrary shaped substrate by dipping the activated arbitrary shaped substrate into a dispersion of silver nanowires, wherein the dispersion of silver nanowires includes silver nanowires, mercaptosiloxane, and a polar solvent; and preparing the transparent film heater by curing the silver nanowire layer.

In some embodiments, before curing the silver nanowire layer, the method may further include preparing a porous silica layer on a surface of the silver nanowire layer by dipping the silver nanowire layer into a dispersion of porous silica.

In some embodiments, a concentration of the dispersion of porous silica may be 0.5-5mg/mL. Particle sizes of porous silicas in the dispersion of porous silica may be 20-200nm.

In some embodiments, before preparing the porous silica layer, the method may further include cleaning the silver nanowire layer with the polar solvent.

In some embodiments, the silver nanowires are prepared by preparing a reducing agent by heating polyol; and preparing the silver nanowires by starting a reaction in a mixture including the reducing agent, a silver source, an oxygen scavenger, and an ionic liquid composed of chloride ions and organic polymer chain ammonium ions.

In some embodiments, a concentration of the silver nanowires in the dispersion of silver nanowires may be 0.5-5mg/mL. A mass ratio of mercaptosiloxane to the silver nanowires in the dispersion of silver nanowires may be 1: 5-1: 20.

In some embodiments, the mercaptosiloxane may include 3-Mercaptopropyltriethoxysilane, (3-Mercaptopropyl) trimethoxysilane, and/or 3-Mercaptopropylmethyldimethoxysilane.

In some embodiments, the surface modification may include plasma modification, ultraviolet ozone modification, chemical oxidation modification, and/or coupling agent modification.

In some embodiments, a time that the activated arbitrary shaped substrate may be in the dispersion of silver nanowires is 10min-20min. A temperature of the dispersion of silver nanowires may be 25℃-65℃.

A further aspect of the present disclosure relates to a device. The device may include an arbitrary shaped substrate and a transparent film heater deposited on a surface of the arbitrary shaped substrate and configured to heat the arbitrary shaped substrate. The transparent film heater may be prepared by activating the arbitrary shaped substrate by surface modification; preparing a silver nanowire layer with a random network structure on the activated arbitrary shaped substrate by dipping the activated arbitrary shaped substrate into a dispersion of silver nanowires, wherein the dispersion of silver nanowires includes silver nanowires, mercaptosiloxane, and a polar solvent; and preparing the transparent film heater by curing the silver nanowire layer.

Additional features will be set forth in part in the description which follows, and in part will become apparent to those skilled in the art upon examination of the following and the accompanying drawings or may be learned by production or operation of the examples. The features of the present disclosure may be realized and attained by practice or use of various aspects of the methodologies, instrumentalities, and combinations set forth in the detailed examples discussed below.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure is further described in terms of exemplary embodiments. These exemplary embodiments are described in detail with reference to the drawings. These embodiments are non-limiting exemplary embodiments, in which like reference numerals represent similar structures throughout the several views of the drawings, and wherein:

FIG. 1 is a schematic diagram illustrating an exemplary device with a transparent film heater according to some embodiments of the present disclosure;

FIG. 2 is a schematic diagram illustrating an exemplary device with a transparent film heater according to some embodiments of the present disclosure;

FIG. 3 is a flowchart illustrating an exemplary process for preparing a transparent film heater according to some embodiments of the present disclosure;

FIG. 4 is a flowchart illustrating an exemplary process for preparing a transparent film heater according to some embodiments of the present disclosure;

FIG. 5 is a flowchart illustrating an exemplary process for preparing a transparent film heater according to some embodiments of the present disclosure;

FIG. 6 is a schematic diagram illustrating an exemplary device with a transparent film heater according to some embodiments of the present disclosure;

FIG. 7 is a schematic diagram illustrating exemplary silver nanowires according to some embodiments of the present disclosure; and

FIG. 8 is a schematic diagram illustrating an exemplary silver nanowire according to some embodiments of the present disclosure.

DETAILED DESCRIPTION

In the following detailed description, numerous specific details with reference to the accompanying drawings are set forth by way of examples in order to provide a thorough understanding of the relevant disclosure. Various modifications to the disclosed embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be applied to other embodiments and applications without departing from the spirit and scope of the present disclosure. The identical numerals in the drawings represent same or similar structures or operations unless the context clearly indicates otherwise.

It will be understood that the term “system, ” “device, ” “unit, ” and/or “module, ” used herein are one method to distinguish different components, elements, parts, sections, or assemblies of different levels in ascending order. However, the terms may be displaced by another expression if they achieve the same purpose.

The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting. As used herein, the singular forms “a, ” “an, ” and "the” may be intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprise, ” “comprises, ” and/or “comprising, ” “include, ” “includes, ” and/or “including, ” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.

The range of values used herein in the present disclosure briefly illustrates each value in the range of values.

In addition, it should be understood that in the description of the present disclosure, the terms “first” , “second” , or the like, are only used for the purpose of differentiation, and cannot be interpreted as indicating or implying relative importance, nor can be understood as indicating or implying the order.

The flowcharts used in the present disclosure illustrate operations that systems implement according to some embodiments of the present disclosure. It is to be expressly understood, the operations of the flowcharts may be implemented not in order. Conversely, the operations may be implemented in an inverted order, or simultaneously. Moreover, one or more other operations may be added to the flowcharts. One or more operations may be removed from the flowcharts.

Generally, a heat loss of a conventional transparent film heater is relatively large, which reduces the defrosting and defogging effect of the transparent film heater. An aspect of the present disclosure provides a device. The device may include a substrate and a transparent film heater deposited on the substrate. The transparent film heater may be configured to heat the substrate. The transparent film heater may include a heating layer and an isolation layer deposited between the substrate and the heating layer. The heating layer may be configured to generate heat. The isolation layer may be configured to reduce heat conduction from the heating layer to the substrate. According to the embodiments of the present disclosure, by providing the isolation layer, the heat generated by the heating layer conducted to the substrate may be reduced, which reduces the heat loss of the device, thereby improving the defrosting and defogging effect of the device. In some embodiments, the heating layer may include metal nanowires, which may generate a great amount of heat.

A heating layer of a transparent film heater may include silver nanowires, which may be referred to as a silver nanowire transparent film heater. However, the chemical and thermal stability of the silver nanowire transparent film heater may be relatively low. In a conventional process for preparing the silver nanowire transparent film heater, a protective layer may be deposited on a surface of the transparent film heater to improve the chemical and thermal stability of the silver nanowire transparent film heater s. However, it will increase the process complexity and time and hinder silver nanowire transparent film heater commercial application. In addition, an adhesion between the protective layer and the silver nanowire heating layer may be poor. Alternatively, in order to improve the chemical and thermal stability of the silver nanowire transparent film heater, a dispersion of silver nanowires may be prepared by mixing the silver nanowires in resin, and then the dispersion of silver nanowires may be coated on a substrate to prepare the silver nanowire transparent film heater. However, the silver nanowires are prone to agglomeration in resin, which may affect the optoelectronic properties of the silver nanowire transparent film heater.

An aspect of the present disclosure provides a method for preparing a transparent film heater. The method may include preparing a dispersion of silver nanocrystal seeds by starting a reaction in a first mixture including a first silver source, a reducing agent, a protecting agent, and a polar solvent. The method may include preparing a first dispersion of silver nanowires by irradiating a second mixture including the dispersion of the silver nanocrystal seeds, a second silver source, and a thermoset resin by ultraviolet light. The method may include removing the polar solvent from the first dispersion of silver nanowires. The method may include preparing a second dispersion of silver nanowires by mixing a third mixture including a curing accelerator with the as-processed first dispersion of silver nanowires. The method may further include activating (or modifying) a substrate by surface modification (also referred to as surface activation) and preparing the transparent film heater by curing the second dispersion of silver nanowires deposited on the activated substrate (also referred to as modified substrate) . According to the embodiments of the present disclosure, on the one hand, the process of preparing the protective layer is omitted, which reduces the complexity and time of the process and avoids the poor adhesion between the protective layer and the transparent heating layer; on the other hand, the silver nanowires may be uniformly dispersed in the dispersion (e.g., the first dispersion, the second dispersion) , which may reduce the agglomeration of the silver nanowires. As a result, the optoelectronic properties of the silver nanowire transparent film heater may be improved.

In general, the transparent film heater is prepared on a plane substrate. Although a transparent film heater may be prepared on an arbitrary shaped substrate by an electrostatic adsorption method, an adhesion between the transparent film heater and the arbitrary shaped substrate and a uniformity of the transparent film heater may be poor. An aspect of the present disclosure provides a method for preparing a transparent film heater. The method may include providing an arbitrary shaped substrate and activating the arbitrary shaped substrate by surface modification. The method may include preparing a silver nanowire layer with random network structure by dipping the activated arbitrary shaped substrate into a dispersion of silver nanowires. The dispersion of silver nanowires may include silver nanowires, mercaptosiloxane, and a polar solvent. The method may further include preparing the transparent film heater by curing the silver nanowire layer. According to the embodiments of the present disclosure, the mercaptosiloxane is provided in the dispersion of silver nanowires, which may uniformly disperse the silver nanowires. In addition, the mercaptosiloxane may bond to surfaces of the silver nanowires through coordination bonds, which may improve the strong adhesion between the transparent film heater and the arbitrary shaped substrate.

FIG. 1 is a schematic diagram illustrating an exemplary device with a transparent film heater according to some embodiments of the present disclosure. As shown in FIG. 1, the device 100 may include a substrate 110 and a transparent film heater 120.

In some embodiments, the materials of the substrate 110 may include glass, polyethylene terephthalate (PET) , polymethyl methacrylate (PMMA) , polycarbonate (PC) , polyarylene ether nitriles (PEN) , acrylonitrile butadiene styrene copolymer/polycarbonate blend (ABS/PC) , or the like, or any combination thereof. In some embodiments, a shape of the device 100 may include a plane, an arc shape, a hemisphere, a sphere, or the like, or any combination thereof. In some embodiments, the shape of the device 100 may be determined by controlling a shape of the substrate 110. For example, when the shape of the substrate 110 is a square, the shape of device 100 may be a square. In some embodiments, the shape of the device 100 may be determined based on actual requirements of an application scenario, which may not be limited in the present disclosure.

The transparent film heater 120 may be deposited on the substrate 110 and configured to heat the substrate 110. In some embodiments, the transparent film heater 120 may include heating layer 121 configured to generate heat. In some embodiments, an electrode 130 may be deposited on the heating layer 121. The electrode 130 may be in electric connection with the heating layer 121 by a plurality of wires 131 deposited in the electrode 130. After being energized, the heating layer 121 may generate heat to heat the substrate 110 for defogging and defrosting. In some embodiments, the transparent film heater 120 may further include an isolation layer 122 deposited between the substrate 110 and the heating layer 121 and configured to reduce heat conduction from the heating layer 121 to the substrate 110.

In some embodiments, the heating layer 121 may include at least one of an indium tin oxide (ITO) layer, a carbon black layer, a conductive graphite layer, a carbon nanotube layer, a graphene layer, a silver layer, or a copper layer. The ITO layer may be formed on a side of the isolation layer 122 away from the substrate 110 by sputtering. The carbon black layer, the conductive graphite layer, the carbon nanotube layer, or the graphene layer may be formed by preparing a slurry and coating the slurry on the side of the isolation layer 122 away from the substrate 110 by at least one of printing, coating, or spin coating. The silver layer or the copper layer may be formed on the side of the isolation layer 122 away from the substrate 110 by sputtering or by preparing a slurry and coating the slurry on the side of the isolation layer 122 away from the substrate 110 by at least one of printing, coating, or spin coating.

In order to reduce the impact of a relatively low light transmittance of the carbon black layer, the conductive graphite layer, the carbon nanotube layer, the graphene layer, the silver layer, or the copper layer on the light transmittance of the device 100, the carbon black layer, the conductive graphite layer, the carbon nanotube layer, the graphene layer, the silver layer, or the copper layer may be deposited on a predetermined position of the substrate 110 instead of completely covering the substrate 110. For example, the carbon black layer, the conductive graphite layer, the carbon nanotube layer, the graphene layer, the silver layer, or the copper layer may be deposited on an edge of the substrate 110. As another example, the carbon black layer, the conductive graphite layer, the carbon nanotube layer, the graphene layer, the silver layer, or the copper layer may be deposited on different positions of the substrate 110 with intervals.

In some embodiments, the isolation layer 122 may include a material with a relatively low thermal conductivity and a relatively high light transmittance. For example, the isolation layer 122 may include a silica aerogel-resin composite material. A three-dimensional (3D) net structure of the silica aerogel enables the silica aerogel to have properties such as a relatively high specific surface area, a relatively high light transmittance, a relatively low density, a relatively low thermal conductivity, or the like, so that, the silica aerogel-resin composite material composed of the silica aerogel and resin has the relatively low thermal conductivity and the relatively high light transmittance. In addition, the resin used to form the silica aerogel-resin composite material needs to have the relatively low thermal conductivity and the relatively high light transmittance. For example, the resin may include epoxy resin, acrylic resin, or the like, and thus, the isolation layer 122 may include a silica aerogel-epoxy resin composite material, a silica aerogel-acrylic resin composite material, or the like. As a result, the isolation layer 122 may reduce heat conduction from the heating layer 121 to the substrate 110 without affecting the light transmittance of the device 100, thereby reducing the heat loss of the device 100 and improving the defrosting and defogging effect of the device100. In addition, the isolation layer 122 may improve adhesion between the heating layer 121 and the substrate 110, thereby improving the stability of the device100.

In some embodiments, the silica aerogel and resin may be physically mixed (no chemical reaction occurs) to prepare the silica aerogel-resin composite material. Specifically, a silica aerogel dispersion may be prepared by mixing the silica aerogel with deionized water by ultrasonic. In some embodiments, a particle size of the silica aerogel may be in a range of 10-400 nm. In some embodiments, the particle size of the silica aerogel may be in a range of 15-300 nm. In some embodiments, the particle size of the silica aerogel may be in a range of 20-200 nm. In some embodiments, the particle size of the silica aerogel may be in a range of 25-100 nm. In some embodiments, the particle size of the silica aerogel may be in a range of 30-50 nm. Further, the silica aerogel dispersion may be mixed and stirred with the resin to obtain a mixed solution of the silica aerogel and the resin. The isolation layer 122 may be formed by coating the mixed solution on a surface of the substrate 110. In order to improve adhesion between the substrate 110 and the isolation layer 122, the surface of the substrate 110 may be cleaned, and/or activated by surface modification (e.g., processing using a surface wetting agent) before the mixed solution is coated.

In some embodiments, the thermal conductivity and the light transmittance of the silica aerogel-resin composite material may be adjusted by adjusting a proportion of the silica aerogel and the resin. For example, when a volume fraction of the silica aerogel in the silica aerogel-resin composite material is in a range of 0.5%-50%, the thermal conductivity of the silica aerogel-resin composite material may be in a range of 0.1-0.8 W/ (m. K) , and the light transmittance of the silica aerogel-resin composite material may be in a range of 91%-94%.

In some embodiments, a thickness of the isolation layer 122 may be 0.4-4.0 μm. In some embodiments, the thickness of the isolation layer 122 may be 0.5-3.5 μm. In some embodiments, the thickness of the isolation layer 122 may be 0.6-3.0 μm. In some embodiments, the thickness of the isolation layer 122 may be 0.7-2.5 μm. In some embodiments, the thickness of the isolation layer 122 may be 0.9-1.5 μm. In some embodiments, the thickness of the isolation layer 122 may be 1.0-1.2 μm. In some embodiments, the thickness of the isolation layer 122 may be 0.8-2.0 μm, so that, the device 100 may have a higher light transmittance, a less heat loss, and an improved stability.

In some embodiments, the transparent film heater 120 may further include a protective layer (not shown) deposited on a side of the heating layer 121 away from the substrate 110. More descriptions of the protective layer may be found elsewhere in the present disclosure, for example, FIG. 2 and the relevant descriptions, which may not be described herein.

It should be noted that the descriptions of the device 100 are merely provided for the purposes of illustration, and not intended to limit the scope of the present disclosure. For persons having ordinary skills in the art, multiple variations and modifications may be made under the teachings of the present disclosure. For example, the protective layer may be omitted. However, those variations and modifications do not depart from the scope of the present disclosure.

FIG. 2 is a schematic diagram illustrating an exemplary device with a transparent film heater according to some embodiments of the present disclosure. In some embodiments, the device 200 is an exemplary embodiment of the device 100 illustrated in FIG. 1. As shown in FIG. 2, the device 200 may include a substrate 210 and a transparent film heater 220. In some embodiments, the substrate 210 is an exemplary embodiment of the substrate 110 illustrated in FIG. 1. In some embodiments, the transparent film heater 220 is an exemplary embodiment of the transparent film heater 120 illustrated in FIG. 1. The transparent film heater 220 may include a heating layer 221 and an isolation layer 222. In some embodiments, the heating layer 221 is an exemplary embodiment of the heating layer 121 illustrated in FIG. 1. In some embodiments, the isolation layer 222 is an exemplary embodiment of the isolation layer 122 illustrated in FIG. 1.

In some embodiments, the heating layer 221 may include the metal nanowires, so that the heating layer 221 may have a relatively high light transmittance, a relatively high heating capacity per unit area, and a relatively low cost. In the present disclosure, when the heating layer 221 may include the metal nanowires, a whole light transmittance of the device 200 may be greater than 90%, and the isolation layer 222 may reduce heat conduction from the heating layer 221 to the substrate 210, thereby reducing the heat loss of the device 100 and improving the defrosting and defogging effect of the device 100. In some embodiments, the metal nanowires may include silver nanowires, copper nanowires, or the like. When the device 200 is prepared, after the isolation layer 222 on the substrate 210 is dry, the metal nanowires may be prepared on a side of the isolation layer 222 away from the substrate 210 by, for example, coating, spraying, spin coating, or screen printing.

In some embodiments, when the heating layer 221 includes the metal nanowires, a thickness of the heating layer 221 may be 100-1000 nm, diameters of the metal nanowires may be 10-100 nm, or aspect ratios of the metal nanowires may be 200-2000, so that the heating layer 221 have better thermal conductivity and light transmittance. In some embodiments, when the heating layer 221 includes the metal nanowires, the thickness of the heating layer 221 may be 200-900 nm, the diameters of the metal nanowires may be 20-90 nm, or the aspect ratios of the metal nanowires may be 400-1800. In some embodiments, when the heating layer 221 includes the metal nanowires, the thickness of the heating layer 221 may be 300-800 nm, the diameters of the metal nanowires may be 30-80 nm, or the aspect ratios of the metal nanowires may be 600-1600. In some embodiments, when the heating layer 221 includes the metal nanowires, the thickness of the heating layer 221 may be 400-700 nm, the diameters of the metal nanowires may be 40-70 nm, or the aspect ratios of the metal nanowires may be 800-1400. In some embodiments, when the heating layer 221 includes the metal nanowires, the thickness of the heating layer 221 may be 500-600 nm, the diameters of the metal nanowires may be 50-60 nm, or the aspect ratios of the metal nanowires may be 1000-1200.

In some embodiments, in order to reduce the oxidation of metal nanowires in the heating layer 221, the transparent film heater 220 of the device 200 may further include a protective layer 223 (also referred to as an overcoat (OC) protective layer) . The protective layer 223 may be deposited on a side of the heating layer 221 away from the substrate 210. In some embodiments, the protective layer 223 may include materials with a relatively high light transmittance. For example, the materials of the protective layer 223 may include organic silicon resin, acrylic resin, or the like, or any combination thereof. In some embodiments, when the device 200 is prepared, after the heating layer 221 is dry, the protective layer 223 may be prepared on a side of the heating layer 221 away from the substrate 210 by, for example, coating, spraying, spin coating, or screen printing. In some embodiments, a thickness of the protective layer 223 may be 10-70 nm. In some embodiments, the thickness of the protective layer 223 may be 20-60 nm. In some embodiments, the thickness of the protective layer 223 may be 30-50 nm. In some embodiments, the thickness of the protective layer 223 may be 35-45 nm.

In some embodiments, the device 200 may further include an electrode (not shown) deposited between the heating layer 221 and the protective layer 223. In some embodiments, the electrode is an exemplary embodiment of the electrode 130 illustrated in FIG. 1.

In some embodiments, in order to reduce the oxidation of metal nanowires in the heating layer 221, the transparent film heater 220 of the device 200 may further a transparent protection layer 224. In some embodiments, the transparent protection layer 224 may be deposited around the heating layer 221. In some embodiments, a thickness of the transparent protection layer 224 may be equal to a thickness of the heating layer 221. In some embodiments, the transparent protection layer 224 may include materials with a relatively high light transmittance. For example, the materials of the transparent protection layer 224 may include organic silicon resin material, or acrylic resin, or the like, or any combination thereof. In some embodiments, when the device 200 is prepared, after the heating layer 221 is dry, the transparent protection layer 224 may be prepared around the heating layer 221 by, for example, coating, spraying, spin coating, or screen printing.

In some embodiments, the substrate 210 may be glass. The isolation layer 222 with a thickness of 1 μm, which is made from a silica aerogel-bisphenol epoxy resin composite material, may be prepared on a side of the substrate 210. The heating layer 221 with a thickness of 120 nm, which includes silver nanowires may be prepared on a side of the isolation layer 222 away from the substrate 210, and then the protective layer 223 with a thickness of 50 nm, which is made from acrylic resin may be prepared on a side of the heating layer 221 away from the substrate 210. In such cases, a volume fraction of the silica aerogel in the isolation layer 222 may be 30%; a sheet resistance of the device 200 may be 25 Ω/□; a light transmittance of the device 200 may be 89%; after the device 200 is energized, a temperature of the heating layer 221 including silver nanowires may be 122 ℃; a temperature of the protective layer 223 may be 106 ℃.

In some embodiments, the substrate 210 may be glass. The isolation layer 222 is not provided in the device 200. The heating layer 221 with a thickness of 120 nm, which includes silver nanowires may be prepared on a side of the substrate 210, and then the protective layer 223 with a thickness of 50 nm, which is made from acrylic resin may be prepared on a side of the heating layer 221 away from the substrate 210. In such cases, the sheet resistance of the device 200 may be 25 Ω/□; the light transmittance of the device 200 may be 89%; after the device 200 is energized, a temperature of the heating layer 221 including silver nanowires may be 122 ℃; a temperature of the protective layer 223 may be 67 ℃. By comparing the above two embodiments, the isolation layer 222 made from the silica aerogel-resin composite material may reduce the heat conduction from the heating layer 221 to the substrate 210 without affecting the light transmittance of the device 200, thereby reducing the heat loss of the device 200 and improving the defrosting and defogging effect of the device 200.

In some embodiments, the device 200 may be applied in various scenarios, for example, vehicles, cameras, sensors, signal indicators, or other transparent products or components. In some embodiments, the device 200 may be applied in a heating table of a microscope. In some embodiments, the device 200 may be applied in medical or biological experiments to observe experimental progress during experimental heating. In some embodiments, the device 200 may be used as a protective cover of a camera, for example, a transparent protective cover of a spherical camera to reduce the problem of low image quality caused by fogging and frosting.

It should be noted that the descriptions of the device 200 are merely provided for the purposes of illustration, and not intended to limit the scope of the present disclosure. For persons having ordinary skills in the art, multiple variations and modifications may be made under the teachings of the present disclosure. However, those variations and modifications do not depart from the scope of the present disclosure.

FIG. 3 is a flowchart illustrating an exemplary process for preparing a transparent film heater according to some embodiments of the present disclosure.

In step 310, a substrate may be provided. More descriptions of the substrate may be found elsewhere in the present disclosure, for example, FIG. 1, FIG. 2, and the relevant descriptions, which may not be described herein.

In step 320, the substrate may be activated by surface modification. In some embodiments, the surface modification may be performed using a surface modification agent and/or a surface wetting agent. In some embodiments, the surface modification may include plasma modification, ultraviolet ozone modification, chemical oxidation modification, coupling agent modification, or the like, or any combination thereof. In some embodiments, the manner of the surface modification may be determined based on material of the substrate. In some embodiments, before being performed the surface modification, the substrate may be cleaned. For example, the substrate may be cleaned by acetone and/or anhydrous ethanol with the ultrasonic, and then the substate may be dried and performed the surface modification.

In step 330, an isolation layer may be coated on the activated substrate. In some embodiments, the isolation layer may be coated by spraying, spin coating, screen printing, or the like, or any combination thereof. More descriptions of the isolation layer may be found elsewhere in the present disclosure, for example, FIG. 1, FIG. 2, and the relevant descriptions, which may not be described herein.

In step 340, the isolation layer may be cured. In some embodiments, the isolation layer may be cured by natural drying, hot air circulation curing, ultraviolet curing, heating curing, or the like, or any combination thereof.

In step 350, a heating layer may be coated on a side of the isolation layer away from the substrate. In some embodiments, the heating layer may be configured to generate heat. The isolation layer may be configured to reduce heat conduction from the heating layer to the substrate. In some embodiments, the heating layer may be coated by spraying, spin coating, screen printing, or the like, or any combination thereof. More descriptions of the heating layer may be found elsewhere in the present disclosure, for example, FIG. 1, FIG. 2, and the relevant descriptions, which may not be described herein.

In step 360, the heating layer may be cured. In some embodiments, the way heating layer may be cured by natural drying, hot air circulation curing, ultraviolet curing, heating curing, or the like, or any combination thereof.

It should be noted that the above description of the process 300 is merely provided for the purposes of illustration, and not intended to limit the scope of the present disclosure. For persons having ordinary skills in the art, multiple variations or modifications may be made under the teachings of the present disclosure. However, those variations and modifications do not depart from the scope of the present disclosure.

FIG. 4 is a flowchart illustrating an exemplary process for preparing a transparent film heater according to some embodiments of the present disclosure.

In step 410, a dispersion of silver nanocrystal seeds may be prepared by starting a reaction in a first mixture including a first silver source, a reducing agent, a protecting agent, and a polar solvent.

The first silver source may refer to a chemical compound containing silver ions. In some embodiments, the first silver source may include silver nitrate, silver acetate, silver perchlorate, silver fluoride, or the like, or any combination thereof. In some embodiments, a mass fraction of the first silver source in the first mixture may be 0.04%-6%. In some embodiments, the mass fraction of the first silver source in the first mixture may be 0.06%-4%. In some embodiments, the mass fraction of the first silver source in the first mixture may be 0.08%-2%. In some embodiments, the mass fraction of the first silver source in the first mixture may be 0.1%-1.5%. In some embodiments, the mass fraction of the first silver source in the first mixture may be 0.1%-1%. In some embodiments, the mass fraction of the first silver source in the first mixture may be 0.1%-0.5%. In some embodiments, the mass fraction of the first silver source in the first mixture may be 0.2%-0.3%.

The reducing agent may refer to a chemical compound with a reducing effect. In some embodiments, the reducing agent may include aldehyde-based acid anhydride. In some embodiments, the aldehyde-based acid anhydride may include 5-Formyl-2-thiopheneboronic acid and/or 2-Formylfuran-5-boronic acid. In some embodiments, a mass fraction of the reducing agent in the first mixture may be 0.6%-20%. In some embodiments, the mass fraction of the reducing agent in the first mixture may be 0.8%-15%. In some embodiments, the mass fraction of the reducing agent in the first mixture may be 1%-10%. In some embodiments, the mass fraction of the reducing agent in the first mixture may be 2%-8%. In some embodiments, the mass fraction of the reducing agent in the first mixture may be 4%-8%. In some embodiments, the mass fraction of the reducing agent in the first mixture may be 6%-8%.

The protecting agent may be a chemical compound configured to protect properties of a material (e.g., the first silver) without changing its properties. In some embodiments, the protecting agent may include polyvinylpyrrolidone (PVP) and/or cetyltrimethylammonium bromide (CTAB) . In some embodiments, a mass fraction of the protecting agent in the first mixture may be 0.1%-8%. In some embodiments, the mass fraction of the protecting agent in the first mixture may be 0.15%-6%. In some embodiments, the mass fraction of the protecting agent in the first mixture may be 0.2%-4%. In some embodiments, the mass fraction of the protecting agent in the first mixture may be 0.25%-3.5%. In some embodiments, the mass fraction of the protecting agent in the first mixture may be 0.3%-3%. In some embodiments, the mass fraction of the protecting agent in the first mixture may be 0.3%-2.5%. In some embodiments, the mass fraction of the protecting agent in the first mixture may be 0.3%-2%. In some embodiments, the mass fraction of the protecting agent in the first mixture may be 0.3%-1.5%. In some embodiments, the mass fraction of the protecting agent in the first mixture may be 0.4%-1%.

In some embodiments, the polar solvent may include deionized water, ethanol, methanol, or the like, or any combination thereof.

In some embodiments, a reaction time of the first mixture may be 0.5h-4h. In some embodiments, the reaction time of the first mixture may be 0.5h-3.5h. In some embodiments, the reaction time of the first mixture may be 0.5h-3h. In some embodiments, the reaction time of the first mixture may be 0.5h-2h. In some embodiments, the reaction time of the first mixture may be 1h-2h. In some embodiments, in the dispersion of silver nanocrystal seeds, the silver nanocrystal seeds may be silver nanoparticles with grain sizes of 2-10 nm, which may be conducive to the preparation of silver nanowires in subsequent steps with a better aspect ratio. In some embodiments, in the dispersion of silver nanocrystal seeds, the silver nanocrystal seeds may be silver nanoparticles with grain sizes of 1-20 nm. In some embodiments, in the dispersion of silver nanocrystal seeds, the silver nanocrystal seeds may be silver nanoparticles with grain sizes of 3-15 nm. In some embodiments, in the dispersion of silver nanocrystal seeds, the silver nanocrystal seeds may be silver nanoparticles with grain sizes of 4-10 nm.

In step 420, a first dispersion of silver nanowires may be prepared by irradiating a second mixture including the dispersion of the silver nanocrystal seeds, a second silver source, and a thermoset resin by ultraviolet light.

The second silver source may refer to a chemical compound containing silver ions. In some embodiments, the second silver source may include silver nitrate, silver acetate, silver perchlorate, silver fluoride, or the like, or any combination thereof. In some embodiments, a mass fraction of the second silver source in the second mixture may be 0.04%-6%. In some embodiments, the mass fraction of the second silver source in the second mixture may be 0.06%-4%. In some embodiments, the mass fraction of the second silver source in the second mixture may be 0.08%-2%. In some embodiments, the mass fraction of the second silver source in the second mixture may be 0.1%-1%. In some embodiments, the mass fraction of the second silver source in the second mixture may be 0.1%-0.5%.

In some embodiments, the thermoset resin may include bisphenol resin, silicone resin, polyimide, polyurethane, or the like, or any combination thereof.

In some embodiments, a viscosity of the second mixture may be adjusted by adjusting a proportion of the dispersion of the silver nanocrystal seeds, the second silver source, and the thermoset resin in the second mixture. In some embodiments, the viscosity of the second mixture may be lower than 400 Pa.s. In some embodiments, the viscosity of the second mixture may be lower than 300 Pa.s. In some embodiments, the viscosity of the second mixture may be lower than 200 Pa.s. In some embodiments, the viscosity of the second mixture may be in a range of 20-200 Pa.s. In some embodiments, the viscosity of the second mixture may be in a range of 20-100 Pa.s.

Generally, the silver nanowires may be prone to agglomerate in a dispersion formed by the silver nanowires and resin, which makes it difficult for the silver nanowires to disperse uniformly in the transparent film heater of silver nanowires, thereby affecting the optoelectronic properties of the transparent film heater. In the present disclosure, the silver nanowires are prepared in situ in a thermoset resin, so that the silver nanowires in the first dispersion may be uniformly dispersed, thereby ensuring that the first dispersion may be used to prepare the transparent film heater of silver nanowires with excellent photoelectric properties through one-step coating and other processes. However, the difficulty in preparing silver nanowires in situ in the thermoset resin lies in how to prepare high-quality, high-yield silver nanowires in a non-heating manner. Although an ultraviolet reduction manner (e.g., irradiating by ultraviolet light) may replace a heating manner to prepare the silver nanowires in situ in the thermoset resin, structures of the silver nanowires prepared by the ultraviolet reduction manner are often irregular and a yield of the silver nanowires is relatively low. Therefore, in the present disclosure, the ultraviolet reduction manner may be combined with a crystal seed manner to improve the quality and yield of the silver nanowires.

Generally, when preparing the dispersion of the silver nanocrystal seeds, sodium borohydride, ascorbic acid, etc. are used as reducing agents, which may generate by-products. The by-products would cross-link with a curing agent and consume the curing agent, thereby resulting in incomplete curing of the thermoset resin and affecting an adhesive strength and optoelectronic properties of the transparent film heater of silver nanowires. In addition, a viscosity of the thermoset resin is usually 10000Pa.s-20000Pa.s, which is relatively high and not conducive to the dispersion of the silver nanowires prepared in situ in the thermoset resin. In the present disclosure, the aldehyde-based acid anhydride is used as the reducing agent, which may adjust a viscosity of the second mixture when the dispersion of the silver nanocrystal seeds is mixed with the thermoset resin, which may promote the dispersion of the silver nanocrystal seeds in the second mixture and contribute to an Ostwald growth of the silver nanocrystal seeds, thereby facilitating the uniform dispersion of the silver nanowires prepared in situ in the second mixture. In addition, the reducing agent may be used as a curing agent after reduction, which not only omits the curing agent, but also fully cures the thermoset resin into a firm three-dimensional structure, thereby improving the adhesive strength and optoelectronic properties of the transparent film heater of silver nanowires.

In some embodiments, diameters of the silver nanowires may be determined based on the reaction of the first silver source, and lengths of the silver nanowires may be determined based on the reaction of the second silver source. In some embodiments, particle sizes of the silver nanocrystal seeds may affect the diameters of the silver nanowires. For example, the greater the particle sizes of the silver nanocrystal seeds are, the greater the diameters of the silver nanowires are. In some embodiments, the lengths and diameters of silver nanowires may be adjusted by adjusting a wavelength and an irradiation time of the ultraviolet light to the second mixture. In some embodiments, the wavelength of the ultraviolet light may be 100 nm-400 nm. In some embodiments, the wavelength of the ultraviolet light may be 200 nm-400 nm. In some embodiments, the wavelength of the ultraviolet light may be 340 nm-400 nm. In some embodiments, the wavelength of the ultraviolet light may be 360 nm-400 nm. In some embodiments, the irradiation time of the ultraviolet light to the second mixture may be 10h-40h. In some embodiments, the irradiation time of the ultraviolet light to the second mixture may be 12h-36h. In some embodiments, the irradiation time of the ultraviolet light to the second mixture may be 14h-32h. In some embodiments, the irradiation time of the ultraviolet light to the second mixture may be 16h-30h. In some embodiments, the irradiation time of the ultraviolet light to the second mixture may be 18h-28h. In some embodiments, the irradiation time of the ultraviolet light to the second mixture may be 20h-26h. In some embodiments, the irradiation time of the ultraviolet light to the second mixture may be 22h-24h. In some embodiments, when the wavelength of the ultraviolet light is 340 nm-400 nm and the irradiation time of the ultraviolet light to the second mixture is 12h-36h, the diameters of the silver nanowires may be 30-10 nm and the lengths of the silver nanowires may be 3-10 μm.

In step 430, the first dispersion of silver nanowires may be processed by removing the polar solvent from the first dispersion of silver nanowires.

In some embodiments, the polar solvent may be removed from the first dispersion of silver nanowires by evaporation. After the polar solvent is removed, a viscosity of the as-processed dispersion of silver nanowires may be improved, which makes it easier to form a transparent film heater when a dispersion including the as-processed dispersion is coated on a substrate, thereby improving an adhesion between the transparent film heater and the substrate when the transparent film heater is prepared.

In step 440, a second dispersion of silver nanowires may be prepared by mixing a third mixture including a curing accelerator with the as-processed dispersion of silver nanowires.

In some embodiments, the reducing agent may be used as a curing agent after reduction, accordingly, an additional curing agent may not need to be added to the third mixture.

In some embodiments, the curing accelerator may include 2-Ethyl-4-methylimidazole and/or 2, 4, 5-tris (dimethylaminomethyl) phenol. In some embodiments, a mass fraction of the curing accelerator in the second dispersion of silver nanowires may be 0.04%-6%. In some embodiments, the mass fraction of the curing accelerator in the second dispersion of silver nanowires may be 0.06%-4%. In some embodiments, the mass fraction of the curing accelerator in the second dispersion of silver nanowires may be 0.08%-2%. In some embodiments, the mass fraction of the curing accelerator in the second dispersion of silver nanowires may be 0.1%-1.5%. In some embodiments, the mass fraction of the curing accelerator in the second dispersion of silver nanowires may be 0.1%-1%. In some embodiments, the mass fraction of the curing accelerator in the second dispersion of silver nanowires may be 0.1%-0.5%. In some embodiments, the mass fraction of the thermoset resin in the second dispersion may be 10%-90%. In some embodiments, the mass fraction of the thermoset resin in the second dispersion may be 20%-80%. In some embodiments, the mass fraction of the thermoset resin in the second dispersion may be 30%-70%. In some embodiments, the mass fraction of the thermoset resin in the second dispersion may be 40%-60%.

In step 450, a substrate may be activated by surface modification.

In some embodiments, the substrate may be made from materials with a property of heat-resisting. For example, the materials of the substrate 110 may include glass, polyethylene terephthalate (PET) , polymethyl methacrylate (PMMA) , polycarbonate (PC) , polyarylene ether nitriles (PEN) , acrylonitrile butadiene styrene copolymer/polycarbonate blend (ABS/PC) , or the like, or any combination thereof. In some embodiments, the surface modification may be performed using a surface modification agent and/or a surface wetting agent. In some embodiments, the surface modification may include plasma modification, ultraviolet ozone modification, chemical oxidation modification, coupling agent modification, or the like, or any combination thereof. In some embodiments, the manner of the surface modification may be determined based on material of the substrate. In some embodiments, before being performed the surface modification, the substrate may be cleaned. For example, the substrate may be cleaned by acetone and/or anhydrous ethanol with the ultrasonic, and then the substate may be dried and performed the surface modification. By the surface modification, a surface of the modified substrate may include a great amount of carboxyl and hydroxyl, thereby improving an adhesion between the transparent film heater and the substrate when the transparent film heater is prepared.

In step 460, the transparent film heater may be prepared by curing the second dispersion of silver nanowires deposited on the activated substrate.

In some embodiments, the second dispersion of silver nanowires may be deposited on the activated substrate by spraying, spin coating, Mayer rod coating, or the like, or any combination thereof. In some embodiments, a curing temperature of the second dispersion of silver nanowires may be 110℃-240℃. In some embodiments, the curing temperature of the second dispersion of silver nanowires may be 120℃-230℃. In some embodiments, the curing temperature of the second dispersion of silver nanowires may be 130℃-220℃. In some embodiments, the curing temperature of the second dispersion of silver nanowires may be 140℃-210℃. In some embodiments, a curing temperature of the second dispersion of silver nanowires may be 150℃-200℃. In some embodiments, a curing temperature of the second dispersion of silver nanowires may be 150℃-220℃. In some embodiments, a curing time of the second dispersion of silver nanowires may be 5min-160min. In some embodiments, the curing time of the second dispersion of silver nanowires may be 10min-150min. In some embodiments, the curing time of the second dispersion of silver nanowires may be 15min-140min. In some embodiments, the curing time of the second dispersion of silver nanowires may be 30min-90min. In some embodiments, the curing time of the second dispersion of silver nanowires may be 40min-80min. In some embodiments, the curing time of the second dispersion of silver nanowires may be 50min-70min.

An aspect of the present disclosure provides a device that includes a substrate and a transparent film heater deposited on a surface of the substrate and configured to heat the substrate. The transparent film heater may be prepared by the method provided in the present disclosure. Compared with the conventional preparation method of the transparent film heater, the method provided in the present disclosure may include fewer operations, and the transparent film heater prepared by the method provided in the present disclosure may have improved stability, quality, optoelectronic properties, and adhesion between the transparent film heater and the substrate. In some embodiments, the transparent film heater may be applied in the field of camera, or other optoelectronic devices. For example, the transparent film heater may be used as a transparent dome cover of a camera. When the transparent film heater of the present disclosure is applied to a camera, the transparent film heater may be used as a surface heating body to generate heat to defog or defrost for camera lens, thereby reducing the impact of lens fogging and frosting on the captured image.

The method for preparing the transparent film heater provided in the present disclosure is further described according to the following examples and comparative examples.

Example 1

Silver nitrate with a weight of 0.01 g, 5-Formyl-2-thiopheneboronic acid with a weight of 0.45 g, PVP with a weight of 0.31 g, and ethanol with a weigh of 10 g were mixed in a beaker to obtain a first mixture. The first mixture was stirred for 2h to prepare a dispersion of silver nanocrystal seeds. Particle sizes of the silver nanocrystal seeds in the dispersion were 2 nm.

The dispersion of silver nanocrystal seeds, silver nitrate with a weight of 0.09 g, and bisphenol resin with a weight of 1g were mixed to obtain a second mixture with a viscosity of 80 Pa.s. The second mixture was irradiated by ultraviolet light for 24h to prepare a first dispersion of silver nanowires. Diameters of the silver nanowires in the first dispersion were 30-65 nm. Lengths of the silver nanowires in the first dispersion were 5-9 μm.

Ethanol in the first dispersion of silver nanowires may be removed by evaporation. 2-Ethyl-4-methylimidazole with a weight of 0.01g was mixed, by ultrasonic stirring, in the as-processed dispersion of silver nanowires to prepare a second dispersion of silver nanowires.

With the action of the ultrasonic, a substrate of glass was cleaned with acetone and anhydrous ethanol respectively for 15 min. After being dried, the substrate was deposited in a plasma washer for performing a plasma modification on the substrate to graft carboxyl and hydroxyl on a surface of the substrate to prepare an activated substrate. Further, the second dispersion of silver nanowires was uniformly coated on the activated substrate by Mayer rod coating, and then the activated substrate coated with the second dispersion was deposited in a drying box and cured at a curing temperature of 160 ℃ for 60 min to prepare a transparent film heater of the silver nanowires.

Example 2

Silver nitrate with a weight of 0.01 g, 5-Formyl-2-thiopheneboronic acid with a weight of 0.2 g, PVP with a weight of 0.25 g, and ethanol with a weigh of 8 g were mixed in a beaker to obtain a first mixture. The first mixture was stirred for 2h to prepare a dispersion of silver nanocrystal seeds. Particle sizes of the silver nanocrystal seeds in the dispersion were 4 nm.

The dispersion of silver nanocrystal seeds, silver nitrate with a weight of 0.04 g, and bisphenol resin with a weight of 1 g were mixed to obtain a second mixture with a viscosity of 130 Pa.s. The second mixture was irradiated by ultraviolet light for 30h to prepare a first dispersion of silver nanowires. Diameters of the silver nanowires in the first dispersion were 35-60 nm. Lengths of the silver nanowires in the first dispersion were 5-10 μm.

Ethanol in the first dispersion of silver nanowires may be removed by evaporation. 2-Ethyl-4-methylimidazole with a weight of 0.008 g was mixed, by ultrasonic stirring, in the as-processed dispersion of silver nanowires to prepare a second dispersion of silver nanowires.

With the action of the ultrasonic, a substrate of glass was cleaned with acetone and anhydrous ethanol respectively for 15 min. After being dried, the substrate was deposited in a plasma washer for performing a plasma modification on the substrate to graft carboxyl and hydroxyl on a surface of the substrate to prepare an activated substrate. Further, the second dispersion of silver nanowires was uniformly coated on the activated substrate by Mayer rod coating, and then the activated substrate coated with the second dispersion was deposited in a drying box and cured at a curing temperature of 170 ℃ for 50 min to prepare a transparent film heater of the silver nanowires.

Example 3

Silver acetate with a weight of 0.1 g, 2-Formylfuran-5-boronic acid with a weight of 0.45 g, CTAB with a weight of 0.3 g, and methanol with a weigh of 10 g were mixed in a beaker to obtain a first mixture. The first mixture was stirred for 2h to prepare a dispersion of silver nanocrystal seeds. Particle sizes of the silver nanocrystal seeds in the dispersion were 7 nm.

The dispersion of silver nanocrystal seeds, silver nitrate with a weight of 0.14 g, and silicone resin with a weight of 0.9 g were mixed to obtain a second mixture with a viscosity of 50 Pa.s. The second mixture was irradiated by ultraviolet light for 24h to prepare a first dispersion of silver nanowires. Diameters of the silver nanowires in the first dispersion were 60-100 nm. Lengths of the silver nanowires in the first dispersion were 3-10 μm.

Methanol in the first dispersion of silver nanowires may be removed by evaporation. 2, 4, 5-tris (dimethylaminomethyl) phenol with a weight of 0.006 g was mixed, by ultrasonic stirring, in the as-processed dispersion of silver nanowires to prepare a second dispersion of silver nanowires.

With the action of the ultrasonic, a substrate of glass was cleaned with acetone and anhydrous ethanol respectively for 15 min. After being dried, the substrate was deposited in a plasma washer for performing a plasma modification on the substrate to graft carboxyl and hydroxyl on a surface of the substrate to prepare an activated substrate. Further, the second dispersion of silver nanowires was uniformly coated on the activated substrate by Mayer rod coating, and then the activated substrate coated with the second dispersion was deposited in a drying box and cured at a curing temperature of 210 ℃ for 30 min to prepare a transparent film heater of the silver nanowires.

Example 4

Silver acetate with a weight of 0.05 g, 2-Formylfuran-5-boronic acid with a weight of 0.45 g, CTAB with a weight of 0.3 g, and deionized water with a weigh of 7 g were mixed in a beaker to obtain a first mixture. The first mixture was stirred for 2h to prepare a dispersion of silver nanocrystal seeds. Particle sizes of the silver nanocrystal seeds in the dispersion were 5.5 nm.

The dispersion of silver nanocrystal seeds, silver nitrate with a weight of 0.1 g, and polyurethane with a weight of 0.7 g were mixed to obtain a second mixture with a viscosity of 60 Pa.s. The second mixture was irradiated by ultraviolet light for 24h to prepare a first dispersion of silver nanowires. Diameters of the silver nanowires in the first dispersion were 50-85 nm. Lengths of the silver nanowires in the first dispersion were 3-9 μm.

Deionized water in the first dispersion of silver nanowires may be removed by evaporation. 2-Ethyl-4-methylimidazole with a weight of 0.005 g was mixed, by ultrasonic stirring, in the as-processed dispersion of silver nanowires to prepare a second dispersion of silver nanowires.

With the action of the ultrasonic, a substrate of PEN was cleaned by acetone and anhydrous ethanol respectively for 15 min. After being dried, the substrate was deposited in a plasma washer for performing a plasma modification on the substrate to graft carboxyl and hydroxyl on a surface of the substrate to prepare an activated substrate. Further, the second dispersion of silver nanowires was uniformly coated on the activated substrate by Mayer rod coating, and then the activated substrate coated with the second dispersion was deposited in a drying box and cured at a curing temperature of 130 ℃ for 30 min to prepare a transparent film heater of the silver nanowires.

Comparative example 1

Compared with the example 1, acetaldehyde was used to replace 5-Formyl-2-thiopheneboronic acid as the reducing agent, and methyl tetrahydrophthalic anhydride with a weight of 0.5 g, as a curing agent, was added when 2-Ethyl-4-methylimidazole with a weight of 0.01g was added. Specifically, a process for preparing a transparent film heater of comparative example 1 is described as follows.

Silver nitrate with a weight of 0.01 g, acetaldehyde with a weight of 0.45 g, PVP with a weight of 0.31 g, and ethanol with a weigh of 10 g were mixed in a beaker to obtain a first mixture. The first mixture was stirred for 2h to prepare a dispersion of silver nanocrystal seeds.

The dispersion of silver nanocrystal seeds, silver nitrate with a weight of 0.09 g, and bisphenol resin with a weight of 1g were mixed to obtain a second mixture with a viscosity of 80 Pa.s. The second mixture was irradiated by ultraviolet light for 24h to prepare a first dispersion of silver nanowires.

Ethanol in the first dispersion of silver nanowires may be removed by evaporation. 2-Ethyl-4-methylimidazole with a weight of 0.01g and the methyl tetrahydrophthalic anhydride with a weight of 0.5 g were mixed, by ultrasonic stirring, in the as-processed dispersion of silver nanowires to prepare a second dispersion of silver nanowires.

Comparative example 2

Compared with the example 1, sodium borohydride was used to replace 5-Formyl-2-thiopheneboronic acid as the reducing agent, and methyl tetrahydrophthalic anhydride with a weight of 0.5 g, as a curing agent, was added when 2-Ethyl-4-methylimidazole with a weight of 0.01g was added. Specifically, a process for preparing a transparent film heater of comparative example 2 is described as follows.

Silver nitrate with a weight of 0.01 g, sodium borohydride with a weight of 0.45 g, PVP with a weight of 0.31 g, and ethanol with a weigh of 10 g were mixed in a beaker to obtain a first mixture. The first mixture was stirred for 2h to prepare a dispersion of silver nanocrystal seeds.

Comparative example 3

Compared with the example 1, ascorbic acid was used to replace 5-Formyl-2-thiopheneboronic acid as the reducing agent, and methyl tetrahydrophthalic anhydride with a weight of 0.5 g, as a curing agent, was added when 2-Ethyl-4-methylimidazole with a weight of 0.01g was added. Specifically, a process for preparing a transparent film heater of comparative example 3 is described as follows.

Silver nitrate with a weight of 0.01 g, ascorbic acid with a weight of 0.45 g, PVP with a weight of 0.31 g, and ethanol with a weigh of 10 g were mixed in a beaker to obtain a first mixture. The first mixture was stirred for 2h to prepare a dispersion of silver nanocrystal seeds.

Comparative example 4

Compared with the example 1, the silver nitrate with a weight of 0.15 g and bisphenol resin with a weigh of 2 g were mixed with the dispersion of silver nanocrystal seeds to obtain a second mixture with a viscosity of 230 Pa.s. Specifically, a process for preparing a transparent film heater of comparative example 4 is described as follows.

The dispersion of silver nanocrystal seeds, silver nitrate with a weight of 0.15g, and bisphenol resin with a weight of 2g were mixed to obtain a second mixture with a viscosity of 230 Pa.s. The second mixture was irradiated by ultraviolet light for 24h to prepare a first dispersion of silver nanowires.

The optoelectronic properties of the transparent film heaters prepared in examples 1-4 and comparative examples 1-4 are shown in Table 1:

Table 1

As described in connection with the descriptions of examples 1, 3, and 4, since contents of silver ions of the examples 1, 3, and 4 are different, contents of silver nanowires of the transparent film heaters prepared in the examples 1, 3, and 4 are different. Specifically, a content of silver nanowires of the transparent film heater prepared in the example 1 is the least. A content of silver nanowires of the transparent film heater prepared in the example 4 is larger than a content of silver nanowires of the transparent film heater prepared in the example 1. A content of silver nanowires of the transparent film heater prepared in the example 3 is the most. As shown in Table 1, with the increase of the content of the silver nanowires, the sheet resistance of the transparent film heater may decrease and the light transmittance may increase. Comparing the examples 1 and 2, with the decrease of a content of PVP, the sheet resistance of the transparent film heater may increase.

From the comparative examples 1, 2, and 3, it can be seen that by-products generated by a conventional reducing agent (e.g., acetaldehyde, sodium borohydride, ascorbic acid) used in the examples 1, 2, and 3 would cross-link with a curing agent of anhydride and consume the curing agent, hereby resulting in incomplete curing of the thermoset resin and affecting an adhesive strength and optoelectronic properties of the transparent film heater of silver nanowires. In the example 1, the aldehyde-based acid anhydride (e.g., 5-Formyl-2-thiopheneboronic acid) is used as a reducing agent after reduction, which didn’t affect subsequent reaction, and not only omits the curing agent, but also fully cures the thermoset resin into a firm three-dimensional structure, thereby improving the adhesive strength and optoelectronic properties of the transparent film heater of silver nanowires. Comparing the example 1 and the comparative example 2, the increase in the viscosity of the second mixture would cause agglomeration of the silver nanowires in the dispersion, an increase in the sheet resistance, and a decrease in the light transmittance of the transparent film heater.

FIG. 5 is a flowchart illustrating an exemplary process for preparing a transparent film heater according to some embodiments of the present disclosure.

In step 510, an arbitrary shaped substrate may be provided. In some embodiments, a material of the arbitrary shaped substrate may include glass, polyethylene terephthalate (PET) , polymethyl methacrylate (PMMA) , polycarbonate (PC) , polyarylene ether nitriles (PEN) , acrylonitrile butadiene styrene copolymer/polycarbonate blend (ABS/PC) , or the like, or any combination thereof. In some embodiments, a shape of the arbitrary shaped substrate may be regular or irregular. For example, the shape of the arbitrary shaped substrate may include spherical, hemispherical, wavy, sawtooth, or the like, or any combination thereof.

In step 520, the arbitrary shaped substrate may be activated by surface modification. In some embodiments, the surface modification may include plasma modification, ultraviolet ozone modification, chemical oxidation modification, coupling agent modification, or the like, or any combination thereof. By the surface modification, a surface of the activated arbitrary shaped substrate may include a great amount of carboxyl and hydroxyl, thereby improving an adhesion between the transparent film heater and the arbitrary shaped substrate. In some embodiments, before being performed the surface modification, the arbitrary shaped substrate may be cleaned. For example, the arbitrary shaped substrate may be cleaned by acetone and/or anhydrous ethanol with the ultrasonic, and then the arbitrary shaped substate may be dried and performed the surface modification.

In step 530, a silver nanowire layer with a random network structure may be prepared on the activated arbitrary shaped substrate by dipping the activated arbitrary shaped substrate into a dispersion of silver nanowires.

In some embodiments, the dispersion of silver nanowires may include silver nanowires, mercaptosiloxane, and a polar solvent.

Generally, in a preparation process of the silver nanowires, in order to control a morphology and size of the silver nanowires and avoid an agglomeration of the silver nanowires, it is necessary to add PVP as a stabilizer. However, PVP would bind to surfaces of the silver nanowires by coordination bonds and cannot be completely removed from the surfaces of the silver nanowires. Therefore, even if functional groups capable of chemically bonding with the arbitrary shaped substrate are introduced after the silver nanowires are cleaned, the silver nanowires and the arbitrary shaped substrate can only be combined by van der Waals force, so that an adhesion between the silver nanowires and the arbitrary shaped substrate is poor.

In the present disclosure, the silver nanowires may be prepared by starting a reaction in a mixture including a reducing agent that is prepared by heating polyol, a silver source, an oxygen scavenger, and an ionic liquid composed of chloride ions and organic polymer chain ammonium ions. The ionic liquid composed of chloride ions and organic polymer chain ammonium ions may be used as a soft template, so that silver nanoparticles may grow along the organic polymer chain of the ammonium ions, which may promote axial growths of the silver nanowires, thereby improving aspect ratios of the silver nanowires. Since there is no lone pair of electrons, ions in the ionic liquid would not coordinate with silver ions, so that it is easier to remove the ionic liquid during centrifugal cleaning to obtain silver nanowires with pure surfaces, thereby realizing a surface modification of the silver nanowires.

In some embodiments, the polyol may include ethylene glycol, 1, 2-propanediol, glycerol, or the like, or any combination thereof. In some embodiments, by heating, the polyol may be converted into a reducing agent containing at least one aldehyde group. In some embodiments, a temperature of heating the polyol may be 100℃-170℃. In some embodiments, the temperature of heating the polyol may be 110℃-160℃. In some embodiments, the temperature of heating the polyol may be 120℃-150℃. In some embodiments, the temperature of heating the polyol may be 120℃-130℃. In some embodiments, the temperature of heating the polyol may be 120℃-125℃. In some embodiments, a time of heating the polyol may be 0.2h-3h. In some embodiments, the time of heating the polyol may be 0.3h-2.5h. In some embodiments, the time of heating the polyol may be 0.5h-2h. In some embodiments, the time of heating the polyol may be 1h-2h. In some embodiments, the time of heating the polyol may be 1.5h-1.8h.

In some embodiments, a concentration of the ionic liquid in the mixture may be 0.1-1.8 mmol/L. In some embodiments, the concentration of the ionic liquid in the mixture may be 0.2-1.5 mmol/L. In some embodiments, the concentration of the ionic liquid in the mixture may be 0.3-1.2 mmol/L. In some embodiments, the concentration of the ionic liquid in the mixture may be 0.5-1 mmol/L. In some embodiments, the ammonium ions in the ionic liquid may be from tetrapropyl ammonium chloride, tetrabutyl ammonium chloride, tetraamyl ammonium chloride, or the like, or any combination thereof. In some embodiments, a mass fraction of the silver source in the mixture may be 0.06%-1.5%. In some embodiments, the mass fraction of the silver source in the mixture may be 0.08%-1.2%. In some embodiments, the mass fraction of the silver source in the mixture may be 0.1%-1%. In some embodiments, the mass fraction of the silver source in the mixture may be 0.5%-1%. In some embodiments, the mass fraction of the silver source in the mixture may be 0.6%-0.8%. In some embodiments, the silver source may include silver nitrate, silver acetate, silver perchlorate, silver fluoride, or the like, or any combination thereof. In some embodiments, a concentration of the oxygen scavenger in the mixture may be 0.2-4 mmol/L. In some embodiments, the concentration of the oxygen scavenger in the mixture may be 0.4-3.8 mmol/L. In some embodiments, the concentration of the oxygen scavenger in the mixture may be 0.6-. 36 mmol/L. In some embodiments, the concentration of the oxygen scavenger in the mixture may be 0.6-. 2.4 mmol/L. In some embodiments, the concentration of the oxygen scavenger in the mixture may be 0.8-2 mmol/L. In some embodiments, the oxygen scavenger may include 1, 4-dihydroxybenzene, catechol, ferric nitrate, or the like, or any combination thereof.

In some embodiments, a temperature of the reaction in the mixture may be 80℃-200℃. In some embodiments, the temperature of the reaction in the mixture may be 100℃-180℃. In some embodiments, the temperature of the reaction in the mixture may be 120℃-160℃. In some embodiments, the temperature of the reaction in the mixture may be 130℃-150℃. In some embodiments, a time of the reaction in the mixture may be 6h-21h. In some embodiments, the time of the reaction in the mixture may be 8h-20h. In some embodiments, the time of the reaction in the mixture may be 10h-19h. In some embodiments, the time of the reaction in the mixture may be 12h-18h. In some embodiments, the time of the reaction in the mixture may be 14h-16h.

After the reaction, solids in the mixture may be cleaned by a polar solvent and separated to obtain the silver nanowires. In some embodiments, the polar solvent may include ethanol, methanol or deionized water, or the like, or any combination thereof.

When the dispersion of silver nanowires is prepared, the silver nanowires may be mixed with the polar solvent, and then the mercaptosiloxane may be added to the mixture as a dispersant to uniformly disperse, by ultrasound, the silver nanowires. In addition, the mercaptosiloxane may be bound to surfaces of the silver nanowires through coordination bonds, so that when the silver nanowire layer is formed on the surface of the arbitrary shaped substrate, the silver nanowires may be bound to the surface of the activated arbitrary shaped substrate by hydrogen bonds, chemical bonds, and self-assembly, which improves a uniformity of the silver nanowires in the silver nanowire layer and an adhesion between the silver nanowire layer and the arbitrary shaped substrate. In some embodiments, the mercaptosiloxane may include 3-Mercaptopropyltriethoxysilane, (3-Mercaptopropyl) trimethoxysilane, or 3-Mercaptopropylmethyldimethoxysilane, or the like, or any combination thereof. In some embodiments, the polar solvent may include ethanol, methanol, deionized water, or the like, or any combination thereof.

In some embodiments, a concentration of the silver nanowires in the dispersion of silver nanowires is 0.1-10 mg/mL. In some embodiments, the concentration of the silver nanowires in the dispersion of silver nanowires is 0.2-8 mg/mL In some embodiments, the concentration of the silver nanowires in the dispersion of silver nanowires is 0.5-5 mg/mL. In some embodiments, the concentration of the silver nanowires in the dispersion of silver nanowires is 0.5-2 mg/mL. In some embodiments, the concentration of the silver nanowires in the dispersion of silver nanowires is 0.5-1.5 mg/mL. In some embodiments, a mass ratio of mercaptosiloxane to the silver nanowires in the dispersion of silver nanowires is 1: 2-1: 30. In some embodiments, the mass ratio of mercaptosiloxane to the silver nanowires in the dispersion of silver nanowires is 1: 4-1: 25. In some embodiments, the mass ratio of mercaptosiloxane to the silver nanowires in the dispersion of silver nanowires is 1: 5-1: 20. In some embodiments, the mass ratio of mercaptosiloxane to the silver nanowires in the dispersion of silver nanowires is 1: 10-1: 20. In some embodiments, the mass ratio of mercaptosiloxane to the silver nanowires in the dispersion of silver nanowires is 1: 10-1: 15.

In some embodiments, when dipping the activated arbitrary shaped substrate into the dispersion of silver nanowires, a temperature of the dispersion of silver nanowires may be 15℃-80℃. In some embodiments, the temperature of the dispersion of silver nanowires may be 20℃-70℃. In some embodiments, the temperature of the dispersion of silver nanowires may be 25℃-65℃. In some embodiments, the temperature of the dispersion of silver nanowires may be 35℃-55℃. In some embodiments, the temperature of the dispersion of silver nanowires may be 40℃-50℃. In some embodiments, a time that the activated arbitrary shaped substrate is in the dispersion of silver nanowires may be 5min-30min. In some embodiments, the time that the activated arbitrary shaped substrate is in the dispersion of silver nanowires may be 8min-25min. In some embodiments, the time that the activated arbitrary shaped substrate is in the dispersion of silver nanowires may be 10min-20min. In some embodiments, the time that the activated arbitrary shaped substrate is in the dispersion of silver nanowires may be 12min-18min.

In step 540, the transparent film heater may be prepared by curing the silver nanowire layer. In some embodiments, the silver nanowire layer may be cured by natural drying, hot air circulation curing, ultraviolet curing, heating curing, or the like, or any combination thereof. In some embodiments, a temperature of curing the silver nanowire layer may be 20℃-90℃. In some embodiments, the temperature of curing the silver nanowire layer may be 30℃-80℃. In some embodiments, the temperature of curing the silver nanowire layer may be 40℃-70℃. In some embodiments, the temperature of curing the silver nanowire layer may be 50℃-60℃. In some embodiments, a time of curing the silver nanowire layer may be 0.5h-3h. In some embodiments, the time of curing the silver nanowire layer may be 0.8h-2.5h. In some embodiments, the time of curing the silver nanowire layer may be 1h-2h. In some embodiments, the time of curing the silver nanowire layer may be 1.2h-1.5h.

In some embodiments, in order to remove silver nanowires in the silver nanowire layer adsorbed on the surface of the arbitrary shaped substrate only by van der Waals force, before being cured, the silver nanowire layer may be cleaned with the polar solvent, thereby improving the stability of the photoelectric properties of the transparent film heater.

In some embodiments, before being cured, a porous silica layer may be prepared by dipping the silver nanowire layer into a dispersion of porous silica. Since a refractive index of the porous silica layer is between glass and air, the porous silica layer may have dual functions of protecting the silver nanowire layer as a protective layer and improving light transmittance of the transparent film heater as an antireflection layer, which may improve the stability of the transparent film heater and avoid an introduction of an additional antireflection layer.

In some embodiments, a concentration of the dispersion of porous silica may be 0.1-10mg/mL. In some embodiments, the concentration of the dispersion of porous silica may be 0.3-8mg/mL. In some embodiments, the concentration of the dispersion of porous silica may be 0.5-5mg/mL. In some embodiments, the concentration of the dispersion of porous silica may be 0.5-3mg/mL. In some embodiments, the concentration of the dispersion of porous silica may be 0.8-1mg/mL. In some embodiments, particle sizes of porous silicas in the dispersion of porous silica may be 5-300 nm. In some embodiments, the particle sizes of porous silicas in the dispersion of porous silica may be 10-250 nm. In some embodiments, the particle sizes of porous silicas in the dispersion of porous silica may be 20-200 nm. In some embodiments, the particle sizes of porous silicas in the dispersion of porous silica may be 20-100 nm. In some embodiments, the particle sizes of porous silicas in the dispersion of porous silica may be 50-80 nm.

In some embodiments, a time that the silver nanowire layer is in the dispersion of porous silica may be 5min-30min. In some embodiments, the time that the silver nanowire layer is in the dispersion of porous silica may be 8min-25min. In some embodiments, the time that the silver nanowire layer is in the dispersion of porous silica may be 10min-20min. In some embodiments, the time that the silver nanowire layer is in the dispersion of porous silica may be 12min-18min. In some embodiments, a temperature of the dispersion of silver nanowires may be 15℃-80℃. In some embodiments, a temperature of the dispersion of porous silica may be 20℃-70℃. In some embodiments, the temperature of the dispersion of porous silica may be 25℃-60℃. In some embodiments, the temperature of the dispersion of porous silica may be 35℃-50℃. In some embodiments, the temperature of the dispersion of porous silica may be 40℃-50℃.

The method for preparing the transparent film heater provided in the present disclosure has simple process, few operations, low cost and energy consumption, thereby broadening the application range of the transparent film heater. The prepared transparent film heater may have improved stability, quality, optoelectronic properties, and broad prospects for commercial application.

In some embodiments, the transparent film heater may be applied in the field of camera, or other optoelectronic devices. For example, the transparent film heater may be used as a transparent dome cover of a camera (e.g., a panoramic spherical camera, a hemispherical camera) . When the transparent film heater of the present disclosure is applied to a camera, the transparent film heater may be used as a surface heating body to generate heat to defog or defrost for camera lens, thereby reducing the impact of lens fogging and frosting on the captured image.

It should be noted that the above description of the process 500 is merely provided for the purposes of illustration, and not intended to limit the scope of the present disclosure. For persons having ordinary skills in the art, multiple variations or modifications may be made under the teachings of the present disclosure. However, those variations and modifications do not depart from the scope of the present disclosure.

FIG. 6 is a schematic diagram illustrating an exemplary device with a transparent film heater according to some embodiments of the present disclosure. As shown in FIG. 6, the device 600 may include an arbitrary shaped substrate 610 and a transparent film heater 620 deposited on a surface of the arbitrary shaped substrate 610 and configured to heat the arbitrary shaped substrate 610. In some embodiments, the transparent film heater 620 may be prepared by the method described elsewhere in the present disclosure, for example, FIG. 5 and the relevant descriptions. In some embodiments, the transparent film heater 620 may include a silver nanowire layer 611 deposited on a side of the arbitrary shaped substrate 610 and a porous silica layer 612 deposited on a side of the silver nanowire layer 611 away from the arbitrary shaped substrate 610.

The method for preparing the transparent film heater provided in FIG. 5 is further described according to the following examples and comparative examples.

Example 5

An arbitrary shaped substrate of PC with a shape of a hollow hemisphere (e.g., a dome cover) was provided. With the action of the ultrasonic, the arbitrary shaped substrate was cleaned with acetone and ethanol for 15 min, and then the cleaned arbitrary shaped substrate was dried by natural drying. An outer surface of the arbitrary shaped substrate was covered with a protective film. The arbitrary shaped substrate was deposited in a plasma washer for performing a plasma modification on an inner surface of the arbitrary shaped substrate to graft carboxyl and hydroxyl on the inner surface of the arbitrary shaped substrate to prepare an activated arbitrary shaped substrate.

Ethylene glycol with a weight of 50g was added in a reaction vessel (e.g., a beaker) , and was heated at a temperature of 125℃ for 90 min by dipping the reaction vessel into an oil-bath pan to prepare a reducing agent. Then, tetrabutyl ammonium chloride with a weight of 0.008g, ferric nitrate nonahydrate with a weight of 0.024g, and silver nitrate with a weight of 0.477g were mixed with the reducing agent by ultrasonic to prepare a mixture. The mixture was heated in the oil-bath pan at a temperature of 140℃ for 18h, and then was cleaned with ethanol three times by centrifuging to prepare silver nanowires. FIG. 7 is a schematic diagram illustrating exemplary silver nanowires according to some embodiments of the present disclosure. Specifically, FIG. 7 illustrates a scanning electron microscope (SEM) image of the silver nanowires prepared in the example 5. As shown in FIG. 7, the silver nanowires have a high yield and clean surfaces. FIG. 8 is a schematic diagram illustrating an exemplary silver nanowire according to some embodiments of the present disclosure. Specifically, FIG. 8 illustrates an SEM image of one of the silver nanowires prepared in the example 5.

The silver nanowires were mixed with ethanol and 3-Mercaptopropyltriethoxysilane by ultrasonic for 15 min, and then the mixture was stirred for 5 min. After the above operations (I. e., the ultrasonic mixing and the stirring) were repeated three times, a dispersion of silver nanowires was prepared. In the dispersion of silver nanowires, the 3-Mercaptopropyltriethoxysilane was adsorbed on surfaces of the silver nanowires. A mass ratio of the 3-Mercaptopropyltriethoxysilane to the silver nanowires in the dispersion of silver nanowires was 1: 15. A concentration of the silver nanowires in the dispersion of silver nanowires was 1 mg/mL.

The dispersion of silver nanowires was heated to a temperature of 50℃, and then the activated arbitrary shaped substrate was dipped in the dispersion of silver nanowires for 15 min to form a silver nanowire layer with a random network structure on the inner surface of the arbitrary shaped substrate to prepare a silver nanowire layer.

Further, powder of porous silica with an average particle size of 100 nm was mixed in the ethanol by ultrasonic for 15 min to prepare a dispersion of porous silica. A concentration of the dispersion of porous silica was 1 mg/mL. The silver nanowire layer was dipped in the dispersion of porous silica at a temperature of 45℃ for 15 min to form a porous silica layer on a surface of the silver nanowire layer, and then was cured in a drying box at a temperature of 55℃ for 1h to prepare a transparent film heater.

Example 6

An arbitrary shaped substrate of PC with a shape of a hollow hemisphere (e.g., a dome cover) was provided. With the action of the ultrasonic, the arbitrary shaped substrate was cleaned with acetone and ethanol for 15 min, and then the cleaned arbitrary shaped substrate was dried by natural drying. An outer surface of the arbitrary shaped substrate was covered with a protective film. The arbitrary shaped substrate was deposited in 30wt%of hydrogen peroxide solution at a temperature of 50℃ for 20 min, and then was cleaned with deionized water to prepare an activated arbitrary shaped substrate.

Propyl glycol with a weight of 60g was added in a reaction vessel (e.g., a beaker) , and was heated at a temperature of 130℃ for 90 min by dipping the reaction vessel into an oil-bath pan to prepare a reducing agent. Then, tetrabutyl ammonium chloride with a weight of 0.008g, catechol with a weight of 0.011g, and silver nitrate with a weight of 0.477g were mixed with the reducing agent by ultrasonic to prepare a mixture. The mixture was heated in the oil-bath pan at a temperature of 140℃ for 17h, and then was cleaned with ethanol for three times by centrifuging to prepare silver nanowires.

The silver nanowires were mixed with deionized water and 3-Mercaptopropylmethyldimethoxysilane by ultrasonic for 15 min, and then the mixture was stirred for 5 min. After the above operations (I. e., the ultrasonic mixing and the stirring) were repeated three times, a dispersion of silver nanowires was prepared. In the dispersion of silver nanowires, 3-Mercaptopropylmethyldimethoxysilane was adsorbed on surfaces of the silver nanowires. A mass ratio of the 3-Mercaptopropylmethyldimethoxysilane to the silver nanowires in the dispersion of silver nanowires was 1: 15. A concentration of the silver nanowires in the dispersion of silver nanowires was 0.5 mg/mL.

The dispersion of silver nanowires was heated to a temperature of 55℃, and then the activated arbitrary shaped substrate was dipped in the dispersion of silver nanowires for 15 min to form a silver nanowire layer with a random network structure on an inner surface of the arbitrary shaped substrate to prepare a silver nanowire layer.

Further, powder of porous silica with an average particle size of 50 nm was mixed in the deionized water by ultrasonic for 15 min to prepare a dispersion of porous silica. A concentration of the dispersion of porous silica was 0.5 mg/mL. The silver nanowire layer was dipped in the dispersion of porous silica at a temperature of 55℃ for 15min to form a porous silica layer on a surface of the silver nanowire layer, and then was cured in a drying box at a temperature of 60℃ for 1h to prepare a transparent film heater.

Example 7

An arbitrary shaped substrate of PC with a shape of a hollow hemisphere (e.g., a dome cover) was provided. With the action of the ultrasonic, the arbitrary shaped substrate was cleaned with acetone and ethanol for 15 min, and then the cleaned arbitrary shaped substrate was dried by natural drying. An outer surface of the arbitrary shaped substrate was covered with a protective film. The arbitrary shaped substrate was deposited in 30wt%of hydrogen peroxide solution at a temperature of 50℃ for 20 min, and then was cleaned with the deionized water to prepare an activated arbitrary shaped substrate.

The silver nanowires were mixed with deionized water and 3-Mercaptopropylmethyldimethoxysilane by ultrasonic for 15 min, and then the mixture was stirred for 5 min. After the above operations (I. e., the ultrasonic mixing and the stirring) were repeated three times, a dispersion of silver nanowires was prepared. In the dispersion of silver nanowires, 3-Mercaptopropylmethyldimethoxysilane was adsorbed on surfaces of the silver nanowires. A mass ratio of the 3-Mercaptopropylmethyldimethoxysilane to the silver nanowires in the dispersion of silver nanowires was 1: 10. A concentration of the silver nanowires in the dispersion of silver nanowires was 0.5 mg/mL.

The dispersion of silver nanowires was heated to a temperature of 55℃, and then the activated arbitrary shaped substrate was dipped in the dispersion of silver nanowires FOR 18 min to form a silver nanowire layer with a random network structure on an inner surface of the arbitrary shaped substrate to prepare a silver nanowire layer.

Comparative example 5

Compared with the example 5, in the comparative example 5, the silver nanowires were prepared in a conventional polyol manner in which PVP was used.

Comparative example 6

Compared with the example 5, in the comparative example 6, 3-Mercapto-3-methyl-1-butanol was used to replace 3-Mercaptopropyltriethoxysilane.

The optoelectronic properties of the transparent film heaters prepared in examples 5-7 and comparative examples 5-6 are shown in Table 2:

Table 2

From the examples 6 and 7, it can be seen that as a concentration of the dispersant (e.g., 3-Mercaptopropylmethyldimethoxysilane) increases, a sheet resistance of the transparent film heater increases, which indicates that the dispersant needs to be added in an appropriate amount while ensuring the uniform dispersion of the silver nanowires. From the examples 5, 6, and 7, it can be seen that the sheet resistances of the transparent film heaters after being peeled and pulled 10 times by 3M tape are not changed a lot, which indicates that the transparent film heaters prepared by the method provided in the present disclosure have an improved adhesion with the arbitrary shaped substrate. The transparent film heaters prepared by the conventional method provided in the comparative example 5 and 6 were spalled from the substrate after being peeled and pulled times by 3M tapes. The reason is that the PVP adsorbed in the surfaces of the silver nanowires was not removed completely, and even if the arbitrary shaped substrate is activated (or modified) , the grafted groups (e.g., carboxyl and hydroxyl) on the arbitrary shaped substrate and the PVP on the silver nanowires are usually combined by physical adsorption with poor binding force. In addition, PVP is difficult to be removed and its surface has a relatively high resistance, which results in relatively high sheet resistances of the transparent film heaters prepared in the comparative example 5 and 6.

Having thus described the basic concepts, it may be rather apparent to those skilled in the art after reading this detailed disclosure that the foregoing detailed disclosure is intended to be presented by way of example only and is not limiting. Various alterations, improvements, and modifications may occur and are intended to those skilled in the art, though not expressly stated herein. These alterations, improvements, and modifications are intended to be suggested by this disclosure, and are within the spirit and scope of the exemplary embodiments of this disclosure.

Moreover, certain terminology has been used to describe embodiments of the present disclosure. For example, the terms “one embodiment, ” “an embodiment, ” and/or “some embodiments” mean that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present disclosure. Therefore, it is emphasized and should be appreciated that two or more references to “an embodiment” or “one embodiment” or “an alternative embodiment” in various portions of this disclosure are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined as suitable in one or more embodiments of the present disclosure.

Further, it will be appreciated by one skilled in the art, aspects of the present disclosure may be illustrated and described herein in any of a number of patentable classes or contexts including any new and useful process, machine, manufacture, or composition of matter, or any new and useful improvement thereof. Accordingly, aspects of the present disclosure may be implemented entirely hardware, entirely software (including firmware, resident software, micro-code, etc. ) , or combining software and hardware implementation that may all generally be referred to herein as a “unit, ” “module, ” or “system. ” Furthermore, aspects of the present disclosure may take the form of a computer program product embodied in one or more computer-readable media having computer-readable program code embodied thereon.

Furthermore, the recited order of processing elements or sequences, or the use of numbers, letters, or other designations therefore, is not intended to limit the claimed processes and methods to any order except as may be specified in the claims. Although the above disclosure discusses through various examples what is currently considered to be a variety of useful embodiments of the disclosure, it is to be understood that such detail is solely for that purpose, and that the appended claims are not limited to the disclosed embodiments, but, on the contrary, are intended to cover modifications and equivalent arrangements that are within the spirit and scope of the disclosed embodiments.

Similarly, it should be appreciated that in the foregoing description of embodiments of the present disclosure, various features are sometimes grouped together in a single embodiment, figure, or description thereof for the purpose of streamlining the disclosure aiding in the understanding of one or more of the various inventive embodiments. This method of disclosure, however, is not to be interpreted as reflecting an intention that the claimed subject matter requires more features than are expressly recited in each claim. Rather, inventive embodiments lie in less than all features of a single foregoing disclosed embodiment.

In some embodiments, the numbers expressing quantities or properties used to describe and claim certain embodiments of the application are to be understood as being modified in some instances by the term “about, ” “approximate, ” or “substantially. ” For example, “about, ” “approximate, ” or “substantially” may indicate ±20%variation of the value it describes, unless otherwise stated. Accordingly, in some embodiments, the numerical parameters set forth in the written description and attached claims are approximations that may vary depending upon the desired properties sought to be obtained by a particular embodiment. In some embodiments, the numerical parameters should be construed in light of the number of reported significant digits and by applying ordinary rounding techniques. Notwithstanding that the numerical ranges and parameters setting forth the broad scope of some embodiments of the application are approximations, the numerical values set forth in the specific examples are reported as precisely as practicable.

Each of the patents, patent applications, publications of patent applications, and other material, such as articles, books, specifications, publications, documents, things, and/or the like, referenced herein is hereby incorporated herein by this reference in its entirety for all purposes, excepting any prosecution file history associated with same, any of same that is inconsistent with or in conflict with the present document, or any of same that may have a limiting effect as to the broadest scope of the claims now or later associated with the present document. By way of example, should there be any inconsistency or conflict between the description, definition, and/or the use of a term associated with any of the incorporated material and that associated with the present document, the description, definition, and/or the use of the term in the present document shall prevail.

In closing, it is to be understood that the embodiments of the application disclosed herein are illustrative of the principles of the embodiments of the application. Other modifications that may be employed may be within the scope of the application. Thus, by way of example, but not of limitation, alternative configurations of the embodiments of the application may be utilized in accordance with the teachings herein. Accordingly, embodiments of the present application are not limited to that precisely as shown and described.

Claims

A device, comprising:

a substrate; and

a transparent film heater deposited on the substrate and configured to heat the substrate, wherein the transparent film heater includes:

a heating layer configured to generate heat, and

an isolation layer deposited between the substrate and the heating layer and configured to reduce heat conduction from the heating layer to the substrate.
The device of claim 1, wherein the isolation layer includes a silica aerogel-resin composite material.
The device of claim 1 or claim 2, wherein a thickness of the isolation layer is 0.8-2.0 μm.
The device of any one of claims 1-3, wherein the heating layer includes metal nanowires.
The device of claim 4, wherein

a thickness of the heating layer is 100-1000 nm,

diameters of the metal nanowires are 10-100 nm, or

aspect ratios of the metal nanowires are 200-2000.
The device of claim 4, wherein the metal nanowires include silver nanowires.
The device of any one of claims 1-3, wherein the heating layer includes at least one of an indium tin oxide layer (ITO) , a carbon black layer, a conductive graphite layer, a carbon nanotube layer, a graphene layer, a silver layer, or a copper layer.
The device of any one of claims 1-7, wherein the transparent film heater further includes a protective layer deposited on a side of the heating layer away from the substrate.
The device of claim 8, wherein a thickness of the protective layer is 30-50 nm.
A method for preparing a transparent film heater, comprising:

providing a substrate;

activating the substrate by surface modification;

coating an isolation layer on the activated substrate;

curing the isolation layer;

coating a heating layer on a side of the isolation layer away from the substrate, wherein the heating layer is configured to generate heat, and the isolation layer is configured to reduce heat conduction from the heating layer to the substrate; and
A method for preparing a transparent film heater, comprising:

preparing a dispersion of silver nanocrystal seeds by starting a reaction in a first mixture including a first silver source, a reducing agent, a protecting agent, and a polar solvent;

preparing a first dispersion of silver nanowires by irradiating a second mixture including the dispersion of the silver nanocrystal seeds, a second silver source, and a thermoset resin by ultraviolet light;

removing the polar solvent from the first dispersion of silver nanowires;

preparing a second dispersion of silver nanowires by mixing a third mixture including a curing accelerator with the as-processed dispersion of silver nanowires;

activating a substrate by surface modification; and

preparing the transparent film heater by curing the second dispersion of silver nanowires deposited on the activated substrate.
The method of claim 11, wherein the reducing agent includes an aldehyde-based acid anhydride.
The method of claim 12, wherein the aldehyde-based acid anhydride includes at least one of 5-Formyl-2-thiopheneboronic acid or 2-Formylfuran-5-boronic acid.
The method of any one of claims 11-13, wherein a mass fraction of the reducing agent in the first mixture is 1%-10%.
The method of any one of claims 11-14, wherein the silver nanocrystal seeds are silver nanoparticles with grain sizes of 2-10 nm.
The method of any one of claims 11-15, wherein

the first silver source or the second silver source includes at least one of silver nitrate, silver acetate, silver perchlorate, or silver fluoride,

the protecting agent includes at least one of polyvinylpyrrolidone or cetyltrimethylammonium bromide,

the thermoset resin includes at least one of bisphenol resin, silicone resin, polyimide, or polyurethane, or

the curing accelerator includes at least one of 2-Ethyl-4-methylimidazole or 2, 4, 5-tris (dimethylaminomethyl) phenol.
The method of any one of claims 11-16, wherein

a mass fraction of the first silver source in the first mixture is 0.08%-2%,

a mass fraction of the protecting agent in the first mixture is 0.2%-4%,

a mass fraction of the second silver source in the second mixture is 0.08%-2%,

a mass fraction of the thermoset resin in the dispersion of silver nanowires is 30%-70%, or

a mass fraction of the curing accelerator in the second dispersion of silver nanowires is 0.08%-2%.
The method of any one of claims 11-17, wherein an irradiation time of the ultraviolet light to the second mixture is 12h-36h.
The method of any one of claims 11-18, wherein

a curing temperature of the second dispersion of silver nanowires is 130℃-220℃, or

a curing time of the second dispersion of silver nanowires is 10min-150min.
A device, comprising:

a substrate; and

a transparent film heater deposited on a surface of the substrate and configured to heat the substrate, wherein the transparent film heater is prepared by:

preparing a dispersion of silver nanocrystal seeds by starting a reaction in a first mixture including a first silver source, a reducing agent, a protecting agent, and a polar solvent;

preparing a first dispersion of silver nanowires by irradiating a second mixture including the dispersion of the silver nanocrystal seeds, a second silver source, and a thermoset resin by ultraviolet light;

removing the polar solvent from the first dispersion of silver nanowires;

preparing a second dispersion of silver nanowires by mixing a third mixture including a curing accelerator with the as-processed dispersion of silver nanowires;

activating a substrate by surface modification; and

preparing the transparent film heater by curing the second dispersion of silver nanowires deposited on the activated substrate.
A method for preparing a transparent film heater, comprising:

providing an arbitrary shaped substrate;

activating the arbitrary shaped substrate by surface modification;

preparing a silver nanowire layer with a random network structure on the activated arbitrary shaped substrate by dipping the activated arbitrary shaped substrate into a dispersion of silver nanowires, wherein the dispersion of silver nanowires includes silver nanowires, mercaptosiloxane, and a polar solvent; and

preparing the transparent film heater by curing the silver nanowire layer.
The method of claim 21, wherein before curing the silver nanowire layer, the method further includes:

preparing a porous silica layer on a surface of the silver nanowire layer by dipping the silver nanowire layer into a dispersion of porous silica.
The method of claim 22, wherein

a concentration of the dispersion of porous silica is 0.5-5mg/mL, or

particle sizes of porous silicas in the dispersion of porous silica are 20-200nm.
The method of claim 22, wherein before preparing the porous silica layer, the method further includes:

cleaning the silver nanowire layer with the polar solvent.
The method of any one of claims 21-24, wherein the silver nanowires are prepared by:

preparing a reducing agent by heating polyol; and

preparing the silver nanowires by starting a reaction in a mixture including the reducing agent, a silver source, an oxygen scavenger, and an ionic liquid composed of chloride ions and organic polymer chain ammonium ions.
The method of any one of claims 21-25, wherein

a concentration of the silver nanowires in the dispersion of silver nanowires is 0.5-5mg/mL, or

a mass ratio of mercaptosiloxane to the silver nanowires in the dispersion of silver nanowires is 1: 5-1: 20.
The method of any one of claims 21-26, wherein the mercaptosiloxane includes at least one of 3-Mercaptopropyltriethoxysilane, (3-Mercaptopropyl) trimethoxysilane, or 3-Mercaptopropylmethyldimethoxysilane.
The method of any one of claims 21-27, wherein the surface modification includes at least one of plasma modification, ultraviolet ozone modification, chemical oxidation modification, or coupling agent modification.
The method of any one claims 21-28, wherein

a time that the activated arbitrary shaped substrate is in the dispersion of silver nanowires is 10min-20min, or

a temperature of the dispersion of silver nanowires is 25℃-65℃.
A device, comprising:

an arbitrary shaped substrate; and

a transparent film heater deposited on a surface of the arbitrary shaped substrate and configured to heat the arbitrary shaped substrate, wherein the transparent film heater is prepared by:

activating the arbitrary shaped substrate by surface modification;

preparing a silver nanowire layer with a random network structure on the activated arbitrary shaped substrate by dipping the activated arbitrary shaped substrate into a dispersion of silver nanowires, wherein the dispersion of silver nanowires includes silver nanowires, mercaptosiloxane, and a polar solvent; and

preparing the transparent film heater by curing the silver nanowire layer.