Nano-metal conductive network / polymer substrate flexible transparent electrode based on coordination bonding and preparation method of nano-metal conductive network / polymer substrate flexible transparent electrode

Abstract

The invention provides a nano metal conductive network / polymer substrate flexible transparent electrode based on coordination bonding and a preparation method thereof, and relates to the field of flexible electronic materials.The method comprises the steps that S1, the surface of a hydrophobic substrate is coated with metal nanowire dispersion liquid, and a micron-sized conductive network is formed through self-assembly by means of the coffee ring effect; s2, preparing a substrate solution for forming a coordination bonding effect with a metal material; and S3, embedding the micron-sized conductive network in the step S1 into the substrate solution prepared in the step S2, and drying and stripping to form the embedded electrode. The method is simple in process and suitable for large-area preparation, and the obtained electrode has the advantages of being high in visible light transmittance, low in sheet resistance, excellent in mechanical stability, rapid in thermal response and the like. The flexible transparent electrode can replace traditional FTO, ITO and other brittle conductive substrates, and has wide application prospects in the fields of flexible solar cells, light-emitting displays, wearable optoelectronic devices and the like.

Description

Technical Field

[0001] This invention relates to the field of flexible electronic materials technology, specifically to a flexible transparent electrode based on coordination bonding nano-metal conductive network / polymer substrate and its preparation method, applicable to flexible displays, wearable electronic devices, electrothermal color-changing devices and flexible energy equipment. Background Technology

[0002] With the rapid development of flexible electronics technology, transparent conductive electrodes, as key components of flexible optoelectronic systems, have a decisive impact on the overall performance of the devices. While traditional transparent conductive electrode materials such as indium tin oxide (ITO) possess excellent optical transparency and electrical properties, their inherent brittleness and scarcity make them unsuitable for the diverse needs of the flexible electronics field. Therefore, developing novel transparent conductive electrode materials with high conductivity, high transparency, good environmental stability, and high mechanical stability is of significant practical importance.

[0003] Metal nanowires are considered a promising alternative to ITO due to their tunable aspect ratio, excellent mechanical flexibility, and ease of wet film formation. However, existing flexible transparent electrodes based on metal nanowires suffer from weak adhesion between the nanowires and common substrates (such as polyethylene terephthalate (PET) and polydimethylsiloxane (PDMS), poor mechanical stability, and easy performance degradation under mechanical deformations such as bending, twisting, folding, and peeling, affecting the electrode's conductivity and long-term reliability. Summary of the Invention

[0004] In view of this, and addressing the technical problems of poor environmental stability and insufficient mechanical stability in existing metal-based flexible transparent conductive electrodes, which prevent them from being used in flexible electronic devices, this invention aims to provide a flexible transparent electrode based on coordination bonding of a nano-metal conductive network / polymer substrate and its preparation method. The key lies in embedding a metal nanowire mesh into a substrate that can interact with the metal. The metal nanowires form coordination bonds with the groups in the substrate, thereby enhancing the interaction force between the metal nanowires and the substrate, improving the environmental and mechanical stability of the electrode, and achieving a flexible transparent electrode that combines high transparency, high conductivity, good environmental stability, excellent mechanical stability, and can be mass-produced.

[0005] This invention provides the following technical solution: a method for preparing a flexible transparent electrode based on a coordination-bonded nano-metal conductive network / polymer substrate, comprising the following steps:

[0006] S1. A metal nanowire dispersion is coated onto a hydrophobic substrate surface, and a micron-scale conductive network is formed by self-assembly using the coffee ring effect. S2. Prepare a substrate solution for forming coordination bonds with metallic materials; S3. The micron-scale conductive network formed in step S1 is embedded in the substrate solution prepared in step S2, and an embedded electrode is formed by drying and peeling; wherein, the metal nanowires and the polymer groups of the substrate solution enhance the interfacial bonding force through coordination bonding.

[0007] According to one embodiment of this application, in step S1, the metal nanowires include silver nanowires, copper nanowires, nickel nanowires or their alloy nanowires, etc., the aspect ratio of the metal nanowires is greater than 100, the concentration of the metal nanowire dispersion is 0.05-10 mg / mL, and the dispersion solvent can be a low-boiling-point solvent such as water, ethanol, or isopropanol.

[0008] According to one embodiment of this application, in step S1, the hydrophobic substrate is a polyfluoroalkoxy material, a fluoropolymer material, or a hydrophobically treated glass, and the contact angle between the glass and deionized water is greater than 70°; under controlled ambient temperature (e.g., 20-35°C) and relative humidity (e.g., 30%-70%), the film is formed using the coffee ring effect.

[0009] Furthermore, fluoropolymer materials can be selected from polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), ethylene-tetrafluoroethylene copolymer (ETFE), ethylene-trifluorochloroethylene copolymer (ECTFE), polyvinyl fluoride (PVF), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), etc.; the hydrophobic treatment process of glass: perform plasma treatment on the glass in an air atmosphere for 1-10 min, and then heat it with perfluoroalkyl silane at 40-100℃ for 1-10 h.

[0010] According to one embodiment of this application, in step S2, the substrate solution is a solution rich in polyvinyl alcohol (PVA), polyethylene glycol (PEG), hydroxyethyl cellulose (HEC), polyacrylic acid (PAA), polyethyleneimine (PEI), or derivatives thereof, which are rich in hydroxyl, carboxyl, amino, or thiol groups.

[0011] According to one embodiment of this application, in step S2, the mass fraction of the base solution is 0.1-10 wt%, and plasticizers such as ethylene glycol, glycerin, sorbitol, and glycolic acid are added to the base solution to adjust the flexibility, and the concentration of the added plasticizer is 0.01-2 wt%.

[0012] According to one embodiment of this application, in step S3, the drying conditions of the solvent in the base solution are 30-120°C.

[0013] Furthermore, the embedding method in step S3 can be drop coating, spin coating, scraping coating, slot coating, etc.; the drying conditions are drying at 30-120℃, cooling to room temperature and taking it out to obtain an embedded composite electrode attached to a hydrophobic substrate.

[0014] Furthermore, in step S3, the composite electrode is carefully peeled off from the hydrophobic material using tweezers, a blade, or similar tools. After peeling, the composite electrode retains its structural integrity.

[0015] This application also provides a flexible transparent electrode based on coordination bonding of a nano-metal conductive network / polymer substrate, which is prepared by the above method. The electrode has an embedded structure, in which metal nanowires are bonded to the substrate through coordination bonds. The visible light transmittance of the electrode is greater than 85%, the sheet resistance is less than 50 Ω / sq, and the resistance change rate is less than 10% after at least 1000 bending cycles. It is also suitable for electrothermal color-changing devices.

[0016] Compared with the prior art, the beneficial effects that at least one technical solution adopted in the embodiments of this specification can achieve include at least: 1. The embodiments of the present invention achieve a strong interfacial bond between the metal nanowire network and the polymer substrate through coordination bonding, which significantly improves the interfacial stability and mechanical durability of the electrode.

[0017] 2. The preparation method provided in this embodiment of the invention is simple, mild, and low in cost, and is easy to scale up for mass production, thus having excellent industrialization prospects.

[0018] 3. The flexible transparent electrode prepared in the embodiments of the present invention has excellent comprehensive performance, with high light transmittance, low sheet resistance and excellent bending resistance, and can be widely used in next-generation flexible optoelectronic devices. Attached Figure Description

[0019] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a flowchart illustrating the fabrication process of the flexible transparent metal mesh electrode with coordination bonding according to the present invention. Figure 2 This is a schematic diagram showing the contact angle between the hydrophobically treated glass with coordination bonding according to the present invention and water. Figure 3 Schematic diagram of the fabrication principle for a flexible transparent metal mesh with coordination bonding; Figure 4a The transmittance of the electrodes prepared in Example 1 and Comparative Example 1 in the range of 380-1600 nm is shown in the inset. The microgrid morphology of the electrodes prepared in Example 1 and Comparative Example 1 is shown in the inset. Figure 4bFrom top to bottom, the FT-IR spectra of the Ag NWs, HEC, and Ag NWs / HEC electrodes in Example 1 are shown. Figure 4c From top to bottom, the FT-IR spectra of Ag NWs, PDMS, and Ag NWs / PDMS electrodes in Comparative Example 1 are shown. Figure 4d XPS spectra of Ag NWs and Ag NWs / HEC for the electrode prepared in Example 1; Figure 4e The rate of change of sheet resistance of the electrode prepared in Example 1 after being placed in air for 90 days; Figure 4f The rate of change of sheet resistance of the electrode prepared for Comparative Example 1 after being placed in air for 7 days; Figure 4g The sheet resistance change rate curves of the electrodes prepared in Example 1 and Comparative Example 1 after bending 1000 times with a bending radius of 4 mm are shown. Figure 4h The sheet resistance change rate curves of the electrodes prepared in Example 1 and Comparative Example 1 after 600 peeling cycles with 3M adhesive are shown. Figure 4i Performance tests of the electrode prepared in Example 1 under flat, 360° bent, rolled, and folded states; Figure 5a Optical transmittance and microgrid morphology of the electrode prepared in Example 2 at 400-800 nm; Figure 5b The sheet resistance change rate curve of the electrode prepared in Example 2 after bending 1000 times with a bending radius of 4 mm; Figure 6a Optical transmittance and microgrid morphology of the electrode prepared in Example 3 at 400-800 nm; Figure 6b The sheet resistance change rate curve of the electrode prepared in Example 3 after bending 1000 times with a bending radius of 4 mm; Figure 7a Optical transmittance and microgrid morphology of the electrode prepared in Example 4 at 400-800 nm; Figure 7b The sheet resistance change rate curve of the electrode prepared in Example 4 after bending 1000 times with a bending radius of 4 mm; Figure 8a Optical transmittance and microgrid morphology of the electrode prepared in Example 5 at 400-800 nm; Figure 8b The sheet resistance change rate curve of the electrode prepared in Example 5 after bending 1000 times with a bending radius of 4 mm; Figure 9a Optical transmittance and microgrid morphology of the electrode prepared in Example 6 at 400-800 nm; Figure 9b The sheet resistance change rate curve of the electrode prepared in Example 6 after 1000 bending cycles with a bending radius of 4 mm. Detailed Implementation

[0021] The embodiments of this application will now be described in detail with reference to the accompanying drawings.

[0022] The following specific examples illustrate the implementation of this application. Those skilled in the art can easily understand other advantages and effects of this application from the content disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. This application can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this application. It should be noted that, in the absence of conflict, the following embodiments and features in the embodiments can be combined with each other. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0023] Example 1 This embodiment describes a method for fabricating a flexible transparent electrode based on a coordination-bonded nano-metal conductive network / polymer substrate, such as... Figure 1 As shown, it includes the following steps: S1. Construction of a micron-scale silver nanowire conductive network. Specifically, firstly, 1 mL of a 20 mg / mL silver nanowire (Ag NWs, approximately 70 nm in diameter and 100-200 μm in length, purchased from Jiangsu Xianfeng Nanomaterials Technology Co., Ltd.) isopropanol dispersion was added to 79 mL of isopropanol and ultrasonically dispersed (360 W for 2 min) to prepare a 0.25 mg / mL Ag NWs spray dispersion, which was then refrigerated at 4°C for later use. Secondly, SAGA high-definition glass slides (76.2 mm long, 25.4 mm wide, and 1-1.2 mm thick, purchased from Suzhou Rongwang Instrument Co., Ltd.) were sequentially cleaned in an ultrasonic cleaner with acetone, deionized water, and ethanol for 15 min, and then dried with nitrogen to obtain a clean glass slide. Thirdly, the glass slides were treated with a plasma cleaner for 2 min to activate the surface. Subsequently, the glass slide was subjected to vapor-phase hydrophobication treatment with 1H,1H,2H,2H-perfluorodecyltrichlorosilane vapor at 80°C for 3 h, such as... Figure 2As shown, a stable hydrophobic substrate with a contact angle of approximately 113° was obtained. Next, under conditions of 30°C and 50% relative humidity, the above-mentioned 0.25 mg / mL Ag NWs dispersion was uniformly sprayed onto the surface of the hydrophobic substrate using a spray gun (nozzle diameter 0.3 mm, height from the substrate 10 cm, carrier gas pressure 0.2 MPa). Utilizing the coffee ring effect, the Ag NWs self-assembled to form a continuous conductive network during droplet evaporation. Finally, the prepared conductive network was heated on a hot stage at 100°C for 10 min to remove residual solvent and promote welding between nanowires, thereby reducing contact resistance and ultimately obtaining a micron-scale conductive network with a sheet resistance of approximately 10 Ω / sq.

[0024] S2. Preparation of the polymer base solution rich in coordinating groups. Specifically, 1.0 g of hydroxyethyl cellulose (HEC) powder was weighed and pre-dispersed in 4 g of anhydrous ethanol. This was then added to 95 g of deionized water and dissolved in an oil bath at 60°C and 500 rpm with magnetic stirring for 1 h to obtain a clear and transparent 1 wt% HEC solution. Subsequently, 0.3 g of glycerol was added to this solution as a plasticizer, and stirring was continued for 30 min until homogeneous, yielding the desired polymer base solution.

[0025] S3. Forming and Delamination of the Embedded Composite Electrode. Specifically, firstly, the HEC substrate solution obtained in step S2 is uniformly coated onto the Ag NWs conductive network obtained in step S1 using a drop-casting method, ensuring that the network is completely wetted. Then, the sample is transferred to a 40°C forced-air drying oven and allowed to dry for 10 hours to allow sufficient moisture to evaporate, forming a dense polymer film. The preparation process is as follows: Figure 3 As shown in the diagram. During this process, the abundant hydroxyl groups (-OH) on the HEC molecular chain interact with the Ag NWs surface through coordination bonding, forming a strong interfacial bond. Finally, after the sample cools to room temperature, using pointed tweezers, starting from the edge, the complete Ag NWs / HEC composite electrode film is easily peeled off by utilizing the weak adhesion between the hydrophobic substrate and the polymer substrate, ultimately obtaining a flexible transparent electrode based on coordination bonding.

[0026] Comparative Example 1 This comparative example is based on Example 1, and Ag NWs meshes are prepared using the same method as in Example 1. The preparation of Ag NWs / PDMS flexible transparent electrodes in this comparative example includes the following steps: S1. Construction of a micron-scale silver nanowire conductive network. Specifically, firstly, 1 mL of a 20 mg / mL silver nanowire (Ag NWs, approximately 70 nm in diameter and 100-200 μm in length, purchased from Jiangsu Xianfeng Nanomaterials Technology Co., Ltd.) isopropanol dispersion was added to 79 mL of isopropanol and ultrasonically dispersed (360 W for 2 min) to prepare a 0.25 mg / mL Ag NWs spray dispersion, which was then refrigerated at 4°C for later use. Secondly, SAGA high-definition glass slides (76.2 mm long, 25.4 mm wide, and 1-1.2 mm thick, purchased from Suzhou Rongwang Instrument Co., Ltd.) were sequentially cleaned in an ultrasonic cleaner with acetone, deionized water, and ethanol for 15 min, and then dried with nitrogen to obtain a clean glass slide. Thirdly, the glass slides were treated with a plasma cleaner for 2 min to activate the surface. Subsequently, the glass slide was subjected to vapor-phase hydrophobication treatment with 1H,1H,2H,2H-perfluorodecyltrichlorosilane vapor at 80°C for 3 h to obtain a stable hydrophobic substrate with a contact angle of approximately 110°. Next, under conditions of 30°C and 50% relative humidity, the above-mentioned 0.25 mg / mL Ag NWs dispersion was uniformly sprayed onto the surface of the hydrophobic substrate using a spray gun (nozzle diameter 0.3 mm, height from the substrate 10 cm, carrier gas pressure 0.2 MPa). Utilizing the coffee ring effect, the Ag NWs self-assembled to form a continuous conductive network during droplet evaporation. Finally, the prepared conductive network was heated on a hot stage at 100°C for 10 min to remove residual solvent and promote welding between nanowires, thereby reducing contact resistance and ultimately obtaining a micron-scale conductive network with a sheet resistance of approximately 10 Ω / sq.

[0027] S2. Preparation of polydimethylsiloxane-based mixture. Specifically, the basic prepolymer of polydimethylsiloxane (PDMS) and the curing agent are accurately weighed at a weight ratio of 10:1, placed in a container, and stirred thoroughly for about 10 minutes using a glass rod or centrifugal stirrer until the mixture is uniform in color and has no obvious filamentous texture, thus obtaining the PDMS base mixture.

[0028] S3. Molding and Peeling of the Embedded Composite Electrode. Specifically, firstly, the PDMS mixture prepared in step S2 is uniformly poured onto the surface of the micron-sized conductive network obtained in step S1, allowing it to level naturally and completely cover the surface. Then, the sample is placed in a vacuum desiccator and vacuum-treated at room temperature for 30 minutes to thoroughly remove air bubbles introduced during mixing. After degassing, the sample is transferred to a preheated 80°C forced-air drying oven and cured for 2 hours to allow the PDMS to fully cross-link and solidify. After the sample cools, it is immersed in a 65°C deionized water bath and allowed to stand for 15 minutes. During this process, water molecules penetrate the interface between the PDMS and the hydrophobic glass slide, significantly weakening their adhesion. Finally, the Ag NWs / PDMS composite electrode can be completely peeled off using pointed tweezers, yielding a flexible transparent electrode with excellent flexibility and adhesion.

[0029] The present invention performs performance tests on the flexible transparent conductive electrodes prepared in Example 1 and Comparative Example 1 to further illustrate the superiority of the coordination-bonded nano-metal conductive network / polymer substrate flexible transparent electrode prepared in Example 1.

[0030] First, the flexible transparent conductive electrodes obtained in Example 1 and Comparative Example 1 were characterized in morphology and tested in performance. The results show that the electrodes obtained in Example 1 and Comparative Example 1 are both transparent thin films with a microgrid structure. Specific results are as follows: First, such as Figure 4a As shown, the morphology of the two transparent conductive electrodes was observed using an optical microscope. The insets in the figure, from left to right, are optical photographs of Example 1 and Comparative Example 1. It can be seen that both exhibit a micro-network structure, with the micro-network of Example 1 being curled. Simultaneously, the transmittance of the electrodes was tested using a UV-Vis spectrophotometer, revealing that the transmittances of both were similar, at 85% and 84.9% respectively at 550 nm.

[0031] Secondly, the electrode prepared in Example 1 was subjected to FTIR testing, and the results are as follows: Figure 4b As shown, from top to bottom, the FTIR curves of AgNWs / HEC, HEC-glycerol, and Ag NWs are presented. Compared with the original Ag NWs and HEC-glycerol, the FTIR spectrum of the Ag NWs / HEC electrode shows a new Ag-O stretching vibration peak at 736 cm⁻¹, while the OH peak red-shifts from 3280 cm⁻¹ to 3237 cm⁻¹. These changes collectively indicate that a coordination bond has formed between Ag NWs and the hydroxyl group, which is expected to significantly improve the mechanical stability of the electrode. The FTIR test results of the electrode prepared in Comparative Example 1 are shown below. Figure 4cAs shown, from top to bottom, the FTIR curves are for Ag NWs / PDMS, PDMS, and Ag NWs. A comparison reveals that no coordination bond is formed between Ag NWs and PDMS. To further confirm the existence of the coordination bond, as shown... Figure 4d As shown, XPS analysis was performed on the transparent electrode prepared in Example 1. Compared with pure Ag NWs, the binding energies of Ag 3d3 / 2 and Ag 3d5 / 2 in the AgNWs / HEC electrode showed positive shifts of 0.27 eV and 0.29 eV, respectively. This shift indicates an electron transfer from Ag to the hydroxyl oxygen in the HEC, providing direct evidence for the formation of a coordination bond between Ag NWs and hydroxyl groups.

[0032] Next, the electrodes of Example 1 and Comparative Example 1 were placed in air for long-term stability observation. Figures 4e-4f As shown, the sheet resistance of the electrode in Example 1 changed by less than 0.2% after being placed in air for 90 days; while the sheet resistance of the electrode in Comparative Example 1 increased by 32.87% after being placed in air for one week.

[0033] Finally, under a bending radius of 4 mm, repeated bending tests were performed on the electrodes of Example 1 and Comparative Example 1, respectively. The results are as follows: Figure 4g-Figure 4i The results showed that the sheet resistance of the electrode in Example 1 remained almost unchanged after 1000 bends, while the sheet resistance of the electrode in Comparative Example 1 increased by 20% after 1000 bends. Repeated peel tests were performed on the electrodes using 3M tape. After 600 peels, the sheet resistance of the electrode in Example 1 increased by only 7.6%, while the sheet resistance of the electrode in Comparative Example 1 increased nearly 30 times after 30 peels. The transparent electrode prepared in Example 1 was integrated into a circuit, and its conductivity was tested under deformation conditions such as 360° twisting, rolling, or curling. The results showed that the LED maintained a constant brightness, indicating that the electrode has excellent deformation tolerance and structural stability.

[0034] In summary, the flexible transparent electrode prepared in Example 1, with its coordination-bonded nano-metal conductive network / polymer substrate, exhibits significantly better performance than that of Comparative Example 1 in terms of microstructure, chemical bonding, mechanical stability, environmental stability, and deformation tolerance, fully demonstrating its technological advantages.

[0035] Example 2 A method for fabricating a flexible transparent electrode based on a coordination-bonded nano-metal conductive network / polymer substrate includes the following steps: S1. Construction of a micron-scale silver nanowire conductive network. Specifically, firstly, 1 mL of a 20 mg / mL silver nanowire (Ag NWs, approximately 70 nm in diameter and 100-200 μm in length, purchased from Jiangsu Xianfeng Nanomaterials Technology Co., Ltd.) isopropanol dispersion was added to 79 mL of isopropanol and ultrasonically dispersed (360 W for 2 min) to prepare a 0.25 mg / mL Ag NWs spray dispersion, which was then refrigerated at 4°C for later use. Secondly, SAGA high-definition glass slides (76.2 mm long, 25.4 mm wide, and 1-1.2 mm thick, purchased from Suzhou Rongwang Instrument Co., Ltd.) were sequentially cleaned in an ultrasonic cleaner with acetone, deionized water, and ethanol for 15 min, and then dried with nitrogen to obtain a clean glass slide. Thirdly, the glass slides were treated with a plasma cleaner for 2 min to activate the surface. Subsequently, the glass slide was subjected to vapor-phase hydrophobication treatment with 1H,1H,2H,2H-perfluorodecyltrichlorosilane vapor at 80°C for 3 h to obtain a stable hydrophobic substrate with a contact angle of approximately 110°. Next, under conditions of 30°C and 50% relative humidity, the above-mentioned 0.25 mg / mL Ag NWs dispersion was uniformly sprayed onto the surface of the hydrophobic substrate using a spray gun (nozzle diameter 0.3 mm, height from the substrate 10 cm, carrier gas pressure 0.2 MPa). Utilizing the coffee ring effect, the Ag NWs self-assembled to form a continuous conductive network during droplet evaporation. Finally, the prepared conductive network was heated on a hot stage at 100°C for 10 min to remove residual solvent and promote welding between nanowires, thereby reducing contact resistance and ultimately obtaining a micron-scale conductive network with a sheet resistance of approximately 10 Ω / sq.

[0036] S2. Preparation of the polymer base solution rich in coordinating groups. Specifically, 1.0 g of carboxymethyl cellulose (CMC) powder was weighed and slowly and uniformly added to 99 g of deionized water under high-speed stirring. The solution was dissolved for 1 h under magnetic stirring at 800 rpm to obtain a clear and transparent 1 wt% CMC solution. Subsequently, 0.3 g of glycerol was added to this solution as a plasticizer, and stirring was continued for 30 min until homogeneous, obtaining the desired polymer base solution.

[0037] S3. Forming and Delamination of the Embedded Composite Electrode. Specifically, firstly, the CMC substrate solution obtained in step S2 is uniformly coated onto the Ag NWs conductive network obtained in step S1 using a drop-coating method, ensuring that the network is completely wetted. Then, the sample is transferred to a 40°C forced-air drying oven and allowed to dry for 10 hours to allow sufficient moisture to evaporate, forming a dense polymer film. During this process, the abundant carboxyl groups (-COO) on the CMC molecular chain... -The hydroxyl groups (-OH) and the Ag NWs surface interact through coordination bonding to form a strong interfacial bond. Finally, after the sample cools to room temperature, the entire Ag NWs / CMC composite electrode film is easily peeled off from the edge using pointed tweezers, taking advantage of the weak adhesion between the hydrophobic substrate and the polymer substrate, ultimately yielding a flexible transparent electrode based on coordination bonding.

[0038] In this embodiment, observation using an optical microscope shows that the morphology of the Ag NWs / CMC composite electrode prepared in this embodiment is consistent with the results of Example 1. The photoelectric performance results of this embodiment, observed using a UV-Vis spectrophotometer, are also similar to those of Example 1. Testing the photoelectric performance of the Ag NWs / CMC composite electrode in this embodiment using an electrochemical workstation and spectrophotometer indicates that this electrode possesses the advantages of both high conductivity and excellent transmittance. Figure 5a and Figure 5b As shown, compared to Example 1, the Ag NWs / CMC composite electrode prepared in this example exhibits good photoelectric properties and flexibility.

[0039] Example 3 A method for fabricating a flexible transparent electrode based on a coordination-bonded nano-metal conductive network / polymer substrate includes the following steps: S1. Construction of a micron-scale copper nanowire conductive network. Specifically, firstly, 5 mL of a 2 mg / mL copper nanowire (Cu NWs, diameter approximately 100-300 nm, length 30-50 μm, purchased from Nanjing Suzhan Intelligent Technology Co., Ltd.) isopropanol dispersion was added to 95 mL of ethanol and ultrasonically treated (360 W, 1 min) to ensure uniform dispersion, preparing a 0.1 mg / mL Cu NWs spray dispersion, which was then refrigerated at 4°C for later use. Secondly, SAGA high-definition glass slides (length: 76.2 mm, width: 25.4 mm, thickness: 1-1.2 mm, purchased from Suzhou Rongwang Instrument Co., Ltd.) were sequentially cleaned in an ultrasonic cleaner with acetone, deionized water, and ethanol for 15 min, and then dried with nitrogen to obtain a clean glass slide. Thirdly, the glass slides were treated with a plasma cleaner for 2 min to activate the surface. Subsequently, the glass slide was subjected to vapor-phase hydrophobication treatment with 1H,1H,2H,2H-perfluorodecyltrichlorosilane vapor at 80°C for 3 h to obtain a stable hydrophobic substrate with a contact angle of approximately 110°. Next, under conditions of 30°C and 50% relative humidity, the above-mentioned 0.1 mg / mL Cu NWs dispersion was uniformly sprayed onto the surface of the hydrophobic substrate using a spray gun (nozzle diameter 0.3 mm, height from the substrate 20 cm, carrier gas pressure 0.2 MPa). Utilizing the coffee ring effect, the Cu NWs self-assembled to form a continuous conductive network during droplet evaporation. Finally, the prepared conductive network was heated on a hot stage at 100°C for 10 min to remove residual solvent and promote welding between nanowires, thereby reducing contact resistance and ultimately obtaining a micron-scale conductive network with a sheet resistance of approximately 10 Ω / sq.

[0040] S2. Preparation of the polymer base solution rich in coordinating groups. Specifically, 1.0 g of hydroxyethyl cellulose (HEC) powder was weighed and pre-dispersed in 4 g of anhydrous ethanol. This was then added to 95 g of deionized water and dissolved in an oil bath at 60°C and 500 rpm with magnetic stirring for 1 h to obtain a clear and transparent 1 wt% HEC solution. Subsequently, 0.3 g of glycerol was added to this solution as a plasticizer, and stirring was continued for 30 min until homogeneous, yielding the desired polymer base solution.

[0041] S3. Forming and Peeling of the Embedded Composite Electrode. Specifically, firstly, the HEC substrate solution obtained in step S2 is uniformly coated onto the Cu NWs conductive network obtained in step S1 using a drop-coating method, ensuring that the network is completely wetted. Then, the sample is transferred to a 40°C forced-air drying oven and allowed to dry for 10 hours to allow sufficient moisture to evaporate, forming a dense polymer film. During this process, the abundant hydroxyl groups (-OH) on the HEC molecular chain interact with the Cu NWs surface through coordination bonding, forming a strong interfacial bond. Finally, after the sample cools to room temperature, using pointed tweezers, starting from the edge, the complete Cu NWs / HEC composite electrode film is easily peeled off using the weak adhesion between the hydrophobic substrate and the polymer substrate, ultimately obtaining a flexible transparent electrode based on coordination bonding.

[0042] like Figure 6a and Figure 6b As shown, compared to Example 1, the Ag NWs / CMC composite electrode prepared in this example exhibits good photoelectric properties and flexibility.

[0043] Example 4 A method for fabricating a flexible transparent electrode based on a coordination-bonded nano-metal conductive network / polymer substrate includes the following steps: S1. Construction of a micron-scale silver nanowire conductive network. Specifically, firstly, 1 mL of a 20 mg / mL silver nanowire (Ag NWs, approximately 70 nm in diameter and 100-200 μm in length, purchased from Jiangsu Xianfeng Nanomaterials Technology Co., Ltd.) isopropanol dispersion was added to 79 mL of isopropanol and ultrasonically dispersed (360 W for 2 min) to prepare a 0.25 mg / mL Ag NWs spray dispersion, which was then refrigerated at 4°C for later use. Secondly, SAGA high-definition glass slides (76.2 mm long, 25.4 mm wide, and 1-1.2 mm thick, purchased from Suzhou Rongwang Instrument Co., Ltd.) were sequentially cleaned in an ultrasonic cleaner with acetone, deionized water, and ethanol for 15 min, and then dried with nitrogen to obtain a clean glass slide. Thirdly, the glass slides were treated with a plasma cleaner for 2 min to activate the surface. Subsequently, the glass slide was subjected to vapor-phase hydrophobication treatment with 1H,1H,2H,2H-perfluorodecyltrichlorosilane vapor at 80°C for 3 h to obtain a stable hydrophobic substrate with a contact angle of approximately 110°. Next, under conditions of 30°C and 50% relative humidity, the above-mentioned 0.25 mg / mL Ag NWs dispersion was uniformly sprayed onto the surface of the hydrophobic substrate using a spray gun (nozzle diameter 0.3 mm, height from the substrate 20 cm, carrier gas pressure 0.2 MPa). Utilizing the coffee ring effect, the Ag NWs self-assembled to form a continuous conductive network during droplet evaporation. Finally, the prepared conductive network was heated on a hot stage at 100°C for 10 min to remove residual solvent and promote welding between nanowires, thereby reducing contact resistance and ultimately obtaining a micron-scale conductive network with a sheet resistance of approximately 10 Ω / sq.

[0044] S2. Preparation of the polymer base solution rich in coordinating groups. Specifically, 1.0 g of hydroxyethyl cellulose (HEC) powder was weighed and pre-dispersed in 4 g of anhydrous ethanol. This was then added to 95 g of deionized water and dissolved in an oil bath at 60°C and 500 rpm with magnetic stirring for 1 h to obtain a clear and transparent 1 wt% HEC solution. Subsequently, 0.3 g of ethylene glycol was added to this solution as a plasticizer, and stirring was continued for 30 min until homogeneous, obtaining the desired polymer base solution.

[0045] S3. Forming and Peeling of the Embedded Composite Electrode. Specifically, firstly, the HEC substrate solution obtained in step S2 is uniformly coated onto the Ag NWs conductive network obtained in step S1 using a drop-coating method, ensuring that the network is completely wetted. Then, the sample is transferred to a 40°C forced-air drying oven and allowed to dry for 10 hours to allow sufficient moisture to evaporate, forming a dense polymer film. During this process, the abundant hydroxyl groups (-OH) on the HEC molecular chain interact with the Ag NWs surface through coordination bonding, forming a strong interfacial bond. Finally, after the sample cools to room temperature, using pointed tweezers, starting from the edge, the complete Ag NWs / HEC composite electrode film is easily peeled off using the weak adhesion between the hydrophobic substrate and the polymer substrate, ultimately obtaining a flexible transparent electrode based on coordination bonding.

[0046] like Figure 7a and Figure 7b As shown, compared to Example 1, the Ag NWs / CMC composite electrode prepared in this example exhibits good photoelectric properties and flexibility.

[0047] Example 5 A method for fabricating a flexible transparent electrode based on a coordination-bonded nano-metal conductive network / polymer substrate includes the following steps: S1. Construction of a micron-scale silver nanowire conductive network. Specifically, firstly, 0.2 mL of a 20 mg / mL silver nanowire (Ag NWs, approximately 70 nm in diameter and 100-200 μm in length, purchased from Jiangsu Xianfeng Nanomaterials Technology Co., Ltd.) isopropanol dispersion was added to 79 mL of isopropanol and ultrasonically dispersed (360 W for 2 min) to prepare a 0.05 mg / mL Ag NWs spray dispersion, which was then refrigerated at 4 ℃ for later use. Secondly, SAGA high-definition glass slides (76.2 mm long, 25.4 mm wide, and 1-1.2 mm thick, purchased from Suzhou Rongwang Instrument Co., Ltd.) were sequentially cleaned in an ultrasonic cleaner with acetone, deionized water, and ethanol for 15 min, and then dried with nitrogen to obtain a clean glass slide. Thirdly, the glass slides were treated with a plasma cleaner for 2 min to activate the surface. Subsequently, the glass slide was subjected to vapor-phase hydrophobication treatment with 1H,1H,2H,2H-perfluorodecyltrichlorosilane vapor at 80°C for 3 h to obtain a stable hydrophobic substrate with a contact angle of approximately 110°. Next, under conditions of 30°C and 50% relative humidity, the above-mentioned 0.05 mg / mL Ag NWs dispersion was uniformly sprayed onto the surface of the hydrophobic substrate using a spray gun (nozzle diameter 0.3 mm, height from the substrate 20 cm, carrier gas pressure 0.2 MPa). Utilizing the coffee ring effect, the Ag NWs self-assembled to form a continuous conductive network during droplet evaporation. Finally, the prepared conductive network was heated on a hot stage at 100°C for 10 min to remove residual solvent and promote welding between nanowires, thereby reducing contact resistance and ultimately obtaining a micron-scale conductive network with a sheet resistance of approximately 50 Ω / sq.

[0048] S2. Preparation of the polymer base solution rich in coordinating groups. Specifically, 1.0 g of hydroxyethyl cellulose (HEC) powder was weighed and pre-dispersed in 4 g of anhydrous ethanol. This was then added to 95 g of deionized water and dissolved in an oil bath at 60°C and 500 rpm with magnetic stirring for 1 h to obtain a clear and transparent 1 wt% HEC solution. Subsequently, 0.3 g of glycerol was added to this solution as a plasticizer, and stirring was continued for 30 min until homogeneous, yielding the desired polymer base solution.

[0049] S3. Forming and Peeling of the Embedded Composite Electrode. Specifically, firstly, the HEC substrate solution obtained in step S2 is uniformly coated onto the Ag NWs conductive network obtained in step S1 using a drop-coating method, ensuring that the network is completely wetted. Then, the sample is transferred to a 40°C forced-air drying oven and allowed to dry for 10 hours to allow sufficient moisture to evaporate, forming a dense polymer film. During this process, the abundant hydroxyl groups (-OH) on the HEC molecular chain interact with the Ag NWs surface through coordination bonding, forming a strong interfacial bond. Finally, after the sample cools to room temperature, using pointed tweezers, starting from the edge, the complete Ag NWs / HEC composite electrode film is easily peeled off using the weak adhesion between the hydrophobic substrate and the polymer substrate, ultimately obtaining a flexible transparent electrode based on coordination bonding.

[0050] like Figure 8a and Figure 8b As shown, the electrode obtained in this embodiment has a visible light transmittance of 90%, a sheet resistance of 50 Ω / sq, and a resistance change of less than 5% after 1000 bends. It is suitable for solar cells, transparent heating films, etc.

[0051] Example 6 A method for fabricating a flexible transparent electrode based on a coordination-bonded nano-metal conductive network / polymer substrate includes the following steps: S1. Construction of a micron-scale silver nanowire conductive network. Specifically, firstly, 4 mL of a 20 mg / mL silver nanowire (Ag NWs, approximately 70 nm in diameter and 100-200 μm in length, purchased from Jiangsu Xianfeng Nanomaterials Technology Co., Ltd.) isopropanol dispersion was added to 76 mL of isopropanol and ultrasonically dispersed (360 W for 2 min) to prepare a 1.0 mg / mL Ag NWs spray dispersion, which was then refrigerated at 4°C for later use. Secondly, SAGA high-definition glass slides (76.2 mm long, 25.4 mm wide, and 1-1.2 mm thick, purchased from Suzhou Rongwang Instrument Co., Ltd.) were sequentially cleaned in an ultrasonic cleaner with acetone, deionized water, and ethanol for 15 min, and then dried with nitrogen to obtain a clean glass slide. Thirdly, the glass slides were treated with a plasma cleaner for 2 min to activate the surface. Subsequently, the glass slide was subjected to vapor-phase hydrophobication treatment with 1H,1H,2H,2H-perfluorodecyltrichlorosilane vapor at 80°C for 3 h to obtain a stable hydrophobic substrate with a contact angle of approximately 110°. Next, under conditions of 30°C and 50% relative humidity, the above-mentioned 1.0 mg / mL Ag NWs dispersion was uniformly sprayed onto the surface of the hydrophobic substrate using a spray gun (nozzle diameter 0.3 mm, height from the substrate 20 cm, carrier gas pressure 0.2 MPa). Utilizing the coffee ring effect, the Ag NWs self-assembled to form a continuous conductive network during droplet evaporation. Finally, the prepared conductive network was heated on a hot stage at 100°C for 10 min to remove residual solvent and promote welding between nanowires, thereby reducing contact resistance and ultimately obtaining a micron-scale conductive network with a sheet resistance of approximately 3 Ω / sq.

[0052] S2. Preparation of the polymer base solution rich in coordinating groups. Specifically, 1.0 g of hydroxyethyl cellulose (HEC) powder was weighed and pre-dispersed in 4 g of anhydrous ethanol. This was then added to 95 g of deionized water and dissolved in an oil bath at 60°C and 500 rpm with magnetic stirring for 1 h to obtain a clear and transparent 1 wt% HEC solution. Subsequently, 0.3 g of glycerol was added to this solution as a plasticizer, and stirring was continued for 30 min until homogeneous, yielding the desired polymer base solution.

[0053] S3. Forming and Peeling of the Embedded Composite Electrode. Specifically, firstly, the HEC substrate solution obtained in step S2 is uniformly coated onto the Ag NWs conductive network obtained in step S1 using a drop-coating method, ensuring that the network is completely wetted. Then, the sample is transferred to a 40°C forced-air drying oven and allowed to dry for 10 hours to allow sufficient moisture to evaporate, forming a dense polymer film. During this process, the abundant hydroxyl groups (-OH) on the HEC molecular chain interact with the Ag NWs surface through coordination bonding, forming a strong interfacial bond. Finally, after the sample cools to room temperature, using pointed tweezers, starting from the edge, the complete Ag NWs / HEC composite electrode film is easily peeled off using the weak adhesion between the hydrophobic substrate and the polymer substrate, ultimately obtaining a flexible transparent electrode based on coordination bonding.

[0054] like Figure 9a and Figure 9b As shown, the electrode obtained in this embodiment has a visible light transmittance of 80%, a sheet resistance of 3Ω / sq, and a resistance change of less than 5% after 1000 bends. It is suitable for touch screens, OLEDs, etc.

[0055] This invention addresses the technical problem of insufficient environmental and mechanical stability in existing metal-based flexible transparent electrodes, which makes them unsuitable for long-term use in flexible electronic devices. By embedding a nano-metal conductive network into a polymer substrate solution that can form coordination bonds with the metal, this invention achieves a robust bond between the metal mesh and the substrate material through the coordination bonding between the metal and polymer groups. This method is not only simple and suitable for large-area fabrication, but also yields electrodes with advantages such as high visible light transmittance, low sheet resistance, excellent mechanical stability, and rapid thermal response. This flexible transparent electrode can replace traditional brittle conductive substrates such as FTO and ITO, and has broad application prospects in flexible solar cells, light-emitting displays, and wearable optoelectronic devices.

[0056] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method for fabricating a flexible transparent electrode based on a coordination-bonded nano-metal conductive network / polymer substrate, characterized in that, Includes the following steps: S1. A metal nanowire dispersion is coated onto a hydrophobic substrate surface, and a micron-scale conductive network is formed by self-assembly using the coffee ring effect. S2. Prepare a substrate solution for forming coordination bonds with metallic materials; S3. The micron-scale conductive network formed in step S1 is embedded in the substrate solution prepared in step S2, and an embedded electrode is formed by drying and peeling; wherein, the metal nanowires and the polymer groups of the substrate solution enhance the interfacial bonding force through coordination bonding.

2. The preparation method according to claim 1, characterized in that, In step S1, the metal nanowires are any one of silver nanowires, copper nanowires, and nickel nanowires, the aspect ratio of the metal nanowires is greater than 100, and the concentration of the metal nanowire dispersion is 0.05-10 mg / mL.

3. The preparation method according to claim 1, characterized in that, In step S1, the hydrophobic substrate is a fluoropolymer material or hydrophobically treated glass, and the contact angle between the glass and deionized water is greater than 70°.

4. The preparation method according to claim 1, characterized in that, In step S2, the base solution is any one of polyvinyl alcohol, polyethylene glycol, hydroxyethyl cellulose, polyacrylic acid, and polyethyleneimine.

5. The preparation method according to claim 1, characterized in that, In step S2, the mass fraction of the base solution is 0.1-10 wt%, and a plasticizer is added to the base solution to adjust the flexibility, wherein the concentration of the plasticizer is 0.01-2 wt%.

6. The preparation method according to claim 1, characterized in that, In step S3, the solvent in the base solution is dried at 30-120°C.

7. A flexible transparent electrode based on a coordination-bonded nano-metal conductive network / polymer substrate, characterized in that, The electrode is prepared by the method according to any one of claims 1-6, the electrode has an embedded structure, the visible light transmittance of the electrode is greater than 85%, the sheet resistance is less than 50 Ω / sq, the resistance change rate is less than 10% after at least 1000 bending cycles, and it is suitable for electrothermal color-changing devices.

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