High-transmittance flexible transparent conductive film based on double-side antireflection technology and preparation thereof

Abstract

The application discloses a high-transmittance flexible transparent conductive film based on a double-sided antireflection technology and a preparation method thereof. A SiO2 2D photonic crystal antireflection layer is prepared on a polymer substrate surface of the flexible transparent conductive film by using a gas-liquid interface self-assembly method, and a high-molecular doped metal oxide antireflection layer is prepared on a transparent conductive layer surface by using a solution spin coating method, so that the reflectivity of incident light on the polymer substrate surface and the reflectivity of outgoing light on the transparent conductive layer surface are simultaneously reduced. The average transmittance of the flexible transparent conductive film is increased by 10%, the obtained high-transmittance flexible transparent conductive film has good mechanical bending performance, the vacuum and high-temperature annealing process is avoided in the preparation process, and the preparation of a large-area high-transmittance flexible transparent conductive film is facilitated.

Description

Technical Field

[0001] This invention belongs to the field of flexible electronic thin film technology, and particularly relates to a high-transmittance flexible transparent conductive thin film, its preparation method and application. Background Technology

[0002] Flexible electronics is a technology that fabricates electronic devices on flexible substrates to form flexible electronic circuits. Due to its advantages such as flexibility and lightweight, it can adapt to different working environments to a certain extent and meet the deformation requirements of equipment, thus attracting increasing attention in recent years. Flexible transparent electrodes are an important component of flexible electronic devices, consisting of a flexible substrate material and a transparent conductive layer. Indium tin oxide (ITO) conductive films are commonly used transparent conductive materials for flexible transparent electrodes due to their advantages such as high transmittance, low resistivity, high hardness, wear resistance, and chemical corrosion resistance. Commercially available flexible transparent conductive films typically use highly transparent polyethylene terephthalate (PET) and polyethylene naphthalate (PEN) as substrate materials. However, PET and PEN have a higher refractive index than glass, which leads to increased reflection of incident light from the air and substrate surface, reducing transmittance. Furthermore, because these polymers have poor heat resistance, with glass transition temperatures of 80-150°C, ITO deposition can usually only be performed at low temperatures, easily forming amorphous ITO, resulting in decreased ITO layer transmittance. The two reasons mentioned above result in the transmittance of flexible transparent ITO conductive films being much lower than that of rigid ITO conductive films, which leads to a decrease in the performance of flexible optoelectronic devices.

[0003] Introducing an antireflective film at the interface between a flexible transparent electrode and air can effectively improve its transmittance. Yang et al. deposited a 90 nm thick MgF2 layer on the surface of PET-ITO as an antireflective layer using electron beam evaporation, which increased the average transmittance of PET-ITO in the 400-800 nm range from 78.2% to 81.5% (Feng, J. et al. Record Efficiency Stable Flexible Perovskite Solar Cell Using Effective Additive Assistant Strategy. Adv. Mater. 30, 1801418, 2018.). Lee et al. deposited a plasma-polymerized fluorocarbon antireflection layer on the surface of PET-ITO using mid-frequency magnetron sputtering, increasing the average transmittance of PET-ITO in the 400-800 nm range from 84.0% to 85.5% (Cho, E. et al. Highly efficient and stable flexible perovskitesolar cells enabled by using plasma-polymerized-fluorocarbon antireflection layer. Nano Energy 82, 105737, 2021.). However, the effect of single-sided deposition of a single-layer antireflection film on improving the transmittance of flexible transparent substrates is limited and insufficient to meet the requirement of transparent conductive electrodes with a transmittance greater than 90% for high-performance flexible optoelectronic devices. Depositing multilayer antireflection films on one side of flexible transparent substrates can further improve transmittance, but the fabrication cost of multilayer antireflection films is high, making them unsuitable for low-value-added optoelectronic devices. Therefore, exploring double-sided antireflection technology for flexible transparent substrates is beneficial for developing low-cost, high-transmittance flexible transparent conductive films. Summary of the Invention

[0004] To address the problems existing in the prior art, the present invention aims to provide a flexible transparent conductive film with high transmittance based on double-sided antireflection technology and its preparation method.

[0005] The primary objective of this invention is to provide a high-transmittance flexible transparent conductive film based on double-sided antireflection technology.

[0006] The second objective of this invention is to provide a method for preparing the high-transmittance flexible transparent conductive film based on double-sided antireflection technology.

[0007] To achieve the above objectives, the present invention discloses the following technical solution:

[0008] First, the present invention provides a high transmittance flexible transparent conductive film based on double-sided antireflection technology. The film includes a polymer substrate and a transparent conductive layer thereon. The film is characterized in that a SiO2 2D photonic crystal antireflection layer is provided on the lower surface of the polymer substrate, wherein the SiO2 2D photonic crystal antireflection layer is a single-layer array of SiO2 microspheres; and a polymer-doped metal oxide antireflection layer is provided on the upper surface of the transparent conductive layer.

[0009] As a further technical solution, the SiO2 2D photonic crystal antireflection layer is a single-layer array of SiO2 microspheres with a particle size of 30-300nm.

[0010] As a further technical solution, the polymer in the polymer-doped metal oxide antireflection layer includes, but is not limited to, one or more of the following polymers: polyethylene glycol, polyvinylpyrrolidone, polysorbate, and polyethylene glycol octylphenyl ether.

[0011] As a further technical solution, the metal oxide in the polymer-doped metal oxide antireflection layer includes, but is not limited to, one or more of the following metal oxides: SnO2, TiO2, ZnO, WO3, ZnSnO3, and ZnTiO3.

[0012] As a further technical solution, the doping concentration of the polymer in the polymer-doped metal oxide antireflection layer is 2-36 mg / mL.

[0013] In the high transmittance flexible transparent conductive film of the present invention, the polymer substrate is made of materials including but not limited to: polyethylene terephthalate, polyethylene naphthalate, polycarbonate, polyvinyl chloride, polypropylene, polymethyl methacrylate, polyvinyl alcohol, and polyimide; the transparent conductive layer is made of materials including but not limited to: indium tin oxide (ITO), fluorine-doped tin oxide (FTO), aluminum-doped zinc oxide (AZO), and indium zinc oxide (IZO).

[0014] Secondly, this invention provides a method for preparing the above-mentioned high-transmittance flexible transparent conductive film based on double-sided antireflection technology, comprising the following steps:

[0015] (1) Obtain a flexible transparent conductive film comprising a polymer substrate and a transparent conductive layer;

[0016] (2) Using aminated SiO2 microspheres, SiO2 2D photonic crystals were prepared on the polymer substrate of a flexible transparent conductive film by gas-liquid interface self-assembly method, and dried to form a SiO2 2D photonic crystal antireflection layer.

[0017] (3) A certain concentration of polymer is incorporated into a colloidal solution of metal oxide nanoparticles, stirred evenly, and then spin-coated onto the transparent conductive layer of the flexible transparent conductive film obtained in step (2), and then dried.

[0018] In step (2) above, SiO2 microspheres can be produced using... The SiO2 microspheres were prepared by a method, and then aminated with APTES (3-aminopropyltriethoxysilane) to obtain SiO2-NH2, thereby improving their wettability on the polymer substrate surface.

[0019] Furthermore, in step (2) above, the polymer substrate of the flexible transparent conductive film is first hydrophilically treated, and the aminated SiO2 microspheres are self-assembled into a single-layer colloidal array on the water surface using a tip-guided flow method. Then, the polymer substrate of the hydrophilically treated flexible transparent conductive film is inserted into the water surface with the polymer substrate facing upward, and the SiO2 single-layer colloidal array on the water surface is slowly retrieved to obtain a SiO2 2D photonic crystal loaded on the polymer substrate. After drying, a SiO2 2D photonic crystal antireflection layer is formed.

[0020] In step 3) above, the polymer is added to the ethanol dispersion of the metal oxide colloid, stirred evenly, and then spin-coated onto the transparent conductive layer of the flexible transparent conductive film obtained in step 2). Then, it is annealed at 90-130℃ to obtain a high transmittance flexible transparent conductive film.

[0021] Compared with the prior art, the present invention has achieved the following beneficial effects:

[0022] (1) The present invention uses gas-liquid interface self-assembly and solution spin coating to prepare high-quality double-sided antireflection film, which does not require vacuum and high-temperature annealing process, which is beneficial to the large-area preparation of antireflection film in flexible transparent conductive film, while avoiding the damage to flexible substrate caused by the high temperature process required in traditional antireflection film preparation methods (PVD, CVD).

[0023] (2) The double-sided antireflection film proposed in this invention is characterized by its ability to reduce both the reflectivity of emitted light at the interface between the polymer substrate surface and the air, and the reflectivity of emitted light at the interface between the transparent conductive film surface and the air. This dual antireflection effect can more effectively increase the transmittance of the flexible transparent conductive film. Through the double-sided antireflection technology, we increased the average transmittance of the flexible transparent conductive film PEN-ITO in the visible light band by 10%, reaching 87.1%, achieving the highest transmittance of ITO-based flexible transparent conductive films.

[0024] (3) The flexible transparent conductive film with high transmittance based on double-sided anti-reflection technology prepared by the present invention has good mechanical bending performance. Under the condition of 4mm radius of curvature, the transmittance does not decrease significantly after 2000 bends. Attached Figure Description

[0025] Figure 1 This is a process flow diagram for preparing a high-transmittance flexible transparent conductive film based on double-sided antireflection technology in Example 1 of the present invention.

[0026] Figure 2 This is the transmittance spectrum of the high-transmittance flexible transparent conductive film based on double-sided antireflection technology prepared in Example 1 of the present invention.

[0027] Figure 3 This is a test image of the bending stability of the high-transmittance flexible transparent conductive film based on double-sided antireflection technology prepared in Example 1 of the present invention. Detailed Implementation

[0028] The present invention will be further described below with reference to the accompanying drawings and embodiments, but the present invention is not limited to the following embodiments. Unless otherwise specified, the methods described are conventional methods. Unless otherwise specified, the raw materials are all available from publicly available commercial sources.

[0029] Example 1

[0030] (I) Preparation of SiO2 microspheres

[0031] Using traditional To prepare SiO2 microspheres, all glassware was first soaked in a 4% (w / w) hydrofluoric acid (HF) aqueous solution for 1 hour, and then rinsed thoroughly with ultrapure water. 1.7 mL of ammonia, 1 mL of water, and 50 mL of anhydrous ethanol were mixed thoroughly in a specific ratio. Then, an ethanol solution containing 2.5 mL of TEOS (tetraethoxysilane) was rapidly added, and the mixture was magnetically stirred at room temperature for 12 hours. After the reaction was complete, the mixture was centrifuged at 8000 rpm for 15 minutes to remove the supernatant. The SiO2 microspheres were then washed with anhydrous ethanol until neutral. Next, the mixture was centrifuged at 1000 rpm for 5 minutes to remove any excessively large SiO2 particles from the bottom. This process was repeated several times until no precipitate formed in the lower layer, yielding SiO2 microspheres with a particle size of 80 nm. These microspheres were then sealed and stored in anhydrous ethanol for later use.

[0032] (ii) SiO2 surface modification with amino groups (SiO2-NH2)

[0033] Take another 5 mL of anhydrous ethanol and add 25 μL of APTES (3-aminopropyltriethoxysilane), mixing thoroughly. Take 50 mL of the ethanol dispersion of the obtained 80 nm SiO2 microspheres, sonicate to ensure uniform dispersion in ethanol, and rapidly add the APTES mixture dropwise under magnetic stirring. React at room temperature for 2 h, ensuring the system remains anhydrous throughout the reaction to prevent APTES hydrolysis. After the reaction, centrifuge the obtained SiO2-NH2 microspheres at 8000 rpm for 10 min, wash three times with anhydrous ethanol to remove unreacted APTES, and finally seal and store in anhydrous ethanol.

[0034] (III) Preparation of SiO2 2D Photonic Crystals with PEN Surface

[0035] The PEN surface of PEN-ITO was treated with plasma for 15 min to improve the wettability of SiO2 microspheres on the PEN surface. The SiO2-NH2 ethanol dispersion was concentrated to 200 mg·mL⁻¹. -1 The concentration was uniformly dispersed by ultrasonication. A 2D photonic crystal of SiO2 was assembled using the tip-guided current method; see [link to documentation]. Figure 1 First, take a small amount of concentrated solution using a 1mL syringe, bringing the tip just close to the surface of the culture medium containing ultrapure water. Then, slowly inject the SiO2-NH2 concentrated solution onto the water surface. The SiO2-NH2 quickly spreads on the water surface and self-assembles into a monolayer colloidal array. Next, add a 3mg / mL solution. -1 The surfactant SDS (sodium dodecyl sulfonate) solution makes them more tightly packed; the PEN-ITO ...

[0036] (iv) Preparation of polyvinylpyrrolidone (PVP)-doped SnO2 thin films on ITO surfaces

[0037] 9 mg of polyvinylpyrrolidone (PVP) with a molecular weight of 58,000 was added to 1 mL of an ethanol dispersion of 13 mg / mL SnO2 colloid, and the mixture was stirred until homogeneous. The solution was then spin-coated onto the ITO side of a PEN-ITO film with a SiO2 2D photonic crystal surface at 2000 rpm for 30 s. The resulting film was annealed at 105 °C for 1 h. A high-transmittance flexible transparent conductive film was obtained, with an average visible light transmittance of 87.1%. Figure 2 As shown.

[0038] (V) Bending test of flexible transparent conductive film

[0039] The bending experiment of the thin film was conducted using a stainless steel rod with a radius of 4 mm. The obtained high-transmittance flexible transparent conductive film was slowly bent until it adhered tightly to the stainless steel rod. After holding the bending for about 3 seconds, the device was slowly relaxed until it was fully relaxed, and then held for another 3 seconds. This counted as one bending experiment. The transmittance was measured after every 200 repetitions, for a total of 2000 bends. Under the condition of a curvature radius of 4 mm, after 2000 bends, the transmittance did not decrease significantly. Figure 3 As shown, both the SiO2 2D photonic crystal antireflection film and the polymer-doped metal oxide antireflection film exhibit good bending stability.

[0040] Example 2

[0041] The preparation method of SiO2 microspheres and the assembly of SiO2 photonic crystals at the PEN interface were consistent with those in Example 1. 12 mg of polyethylene glycol (PEG) with a molecular weight of 1500 was added to 1 mL of an ethanol dispersion of 13 mg / mL TiO2 colloid, and the mixture was stirred until homogeneous. The solution was spin-coated onto the ITO side of a PEN-ITO film with a SiO2 2D photonic crystal as the PEN surface at 2500 rpm for 30 s. The resulting film was annealed at 105 °C for 1 h. A flexible, transparent, conductive film with high transmittance was obtained, with an average visible light transmittance of 86.7%.

[0042] Example 3

[0043] The preparation method of SiO2 microspheres and the assembly of SiO2 photonic crystals at the PEN interface were consistent with those in Example 1. 6 mg of polysorbate 80 was added to 1 mL of an ethanol dispersion of 13 mg / mL TiO2 colloid and stirred until homogeneous. The solution was spin-coated onto the ITO side of a PEN-ITO film with a SiO2 2D photonic crystal as the PEN surface at 2500 rpm for 30 s. The resulting film was annealed at 105 °C for 1 h. A flexible, transparent, conductive film with high transmittance was obtained, with an average visible light transmittance of 86.5%.

[0044] Example 4

[0045] The preparation method of SiO2 microspheres and the assembly of SiO2 photonic crystals at the PEN interface were consistent with those in Example 1. 15 mg of polyethylene glycol octylphenyl ether was added to 1 mL of an ethanol dispersion of 13 mg / mL TiO2 colloid and stirred until homogeneous. The solution was spin-coated onto the ITO side of a PEN-ITO film with a SiO2 2D photonic crystal as the PEN surface at 2500 rpm for 30 s. The resulting film was annealed at 105 °C for 1 h. A flexible, transparent conductive film with high transmittance was obtained, with an average visible light transmittance of 86.3%.

Claims

1. A high-transmittance flexible transparent conductive film, said film comprising a polymer substrate and a transparent conductive layer thereon, characterized in that, A SiO2 2D photonic crystal antireflection layer is formed on the lower surface of a polymer substrate. The SiO2 2D photonic crystal antireflection layer is a monolayer array of SiO2 microspheres. The SiO2 2D photonic crystal is prepared on the polymer substrate surface by using aminated SiO2 microspheres and employing a gas-liquid interface self-assembly method. After drying, the SiO2 2D photonic crystal antireflection layer is formed. A polymer-doped metal oxide antireflection layer is formed on the upper surface of a transparent conductive layer. A certain concentration of polymer is incorporated into a colloidal solution of metal oxide nanoparticles, stirred evenly, and then spin-coated onto the surface of the transparent conductive layer. After drying, the polymer-doped metal oxide antireflection layer is formed.

2. The high transmittance flexible transparent conductive film as described in claim 1, characterized in that, The SiO2 2D photonic crystal antireflection layer is a single-layer array of SiO2 microspheres with a particle size of 30-300 nm.

3. The high transmittance flexible transparent conductive film as described in claim 1, characterized in that, The polymer in the polymer-doped metal oxide antireflection layer is selected from one or more of the following polymers: polyethylene glycol, polyvinylpyrrolidone, polysorbate, and polyethylene glycol octylphenyl ether.

4. The high transmittance flexible transparent conductive film as described in claim 1, characterized in that, The metal oxide in the polymer-doped metal oxide antireflection layer is selected from one or more of the following metal oxides: SnO2, TiO2, ZnO, WO3, ZnSnO3, and ZnTiO3.

5. The high transmittance flexible transparent conductive film as described in claim 1, characterized in that, The doping concentration of the polymer in the polymer-doped metal oxide antireflection layer is 2-36 mg / mL.

6. The high transmittance flexible transparent conductive film as described in claim 1, characterized in that, The polymer substrate is selected from the following materials: polyethylene terephthalate, polyethylene naphthalate, polycarbonate, polyvinyl chloride, polypropylene, polymethyl methacrylate, polyvinyl alcohol, and polyimide; the transparent conductive layer is selected from the following materials: indium tin oxide, fluorine-doped tin oxide, aluminum-doped zinc oxide, and indium zinc oxide.

7. A method for preparing a high-transmittance flexible transparent conductive film according to any one of claims 1 to 6, comprising the following steps: 1) Obtain a flexible transparent conductive film comprising a polymer substrate and a transparent conductive layer; 2) Using aminated SiO2 microspheres, SiO2 2D photonic crystals were prepared on the polymer substrate of a flexible transparent conductive film by gas-liquid interface self-assembly method, and dried to form a SiO2 2D photonic crystal antireflection layer; 3) A certain concentration of polymer is incorporated into a colloidal solution of metal oxide nanoparticles, stirred evenly, and then spin-coated onto the transparent conductive layer of the flexible transparent conductive film obtained in step 2), and then dried.

8. The preparation method according to claim 7, characterized in that, In step 2), SiO2 microspheres are prepared using the Stöber method, and then the SiO2 microspheres are aminated using 3-aminopropyltriethoxysilane to obtain aminated SiO2 microspheres SiO2-NH2.

9. The preparation method according to claim 7, characterized in that, In step 2), the polymer substrate of the flexible transparent conductive film is hydrophilicated. The aminated SiO2 microspheres are self-assembled into a single-layer colloidal array on the water surface using a tip-guided flow method. Then, the polymer substrate of the hydrophilic-treated flexible transparent conductive film is inserted into the water surface with the polymer substrate facing upward. The SiO2 single-layer colloidal array on the water surface is slowly retrieved to obtain a SiO2 2D photonic crystal loaded on the polymer substrate. After drying, a SiO2 2D photonic crystal antireflection layer is formed.

10. The preparation method according to claim 7, characterized in that, In step 3), the polymer is added to the ethanol dispersion of the metal oxide colloid, stirred evenly, and then spin-coated onto the transparent conductive layer of the flexible transparent conductive film obtained in step 2). Then, it is annealed at 90~130℃ to obtain a high transmittance flexible transparent conductive film.

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