Preparation method of high-stability flexible stretchable transparent electrode
By combining the pre-covering method and the film-forming transfer method, flexible transparent electrodes with TPU/PH1000/AgNWs structure were prepared, which solved the problem of insufficient application of traditional electrode materials in flexible and stretchable equipment, and achieved high stability and excellent conductivity.
Patent Information
- Application Number
- CN202510253094.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-05
- Publication Date
- 2025-06-06
AI Technical Summary
The application of traditional transparent electrode materials such as ITO in flexible and stretchable electronic devices is limited by their brittleness, poor adhesion, insufficient tensile performance and complex processing technology. The AgNWs' conductivity decreases after multiple deformations, and its stability and durability are insufficient.
The pre-covering method is combined with the film formation transfer method. The AgNWs conductive layer is first spin-coated on the glass substrate, then spin-coated PH1000 to form a pre-covered layer, and finally the film is formed by spin-coated TPU to form a flexible transparent electrode with a TPU/PH1000/AgNWs structure, and the conductivity and adhesion are optimized through step-by-step heating annealing and the use of surfactant.
It achieves high stability, low surface resistance, low surface roughness and excellent optical performance, suitable for flexible optoelectronic devices, and maintains good conductivity under multiple stretching and bending.
Smart Images
Figure CN120108845A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the field of transparent electrode preparation, and in particular to a method for preparing a highly stable, flexible and stretchable transparent electrode. Background Art
[0002] With the rapid development of flexible electronic technology, flexible stretchable transparent electrodes have become a hot topic in research and industrialization as key materials in next-generation electronic devices such as flexible displays, touch screens, and solar cells. As one of the core components of the device, the performance of the transparent electrode directly affects the function and stability of the device. However, although traditional transparent electrode materials such as indium tin oxide (ITO) have good conductivity and transparency, they face many challenges, such as strong brittleness, poor adhesion to flexible substrates, insufficient stretchability, and complex processing technology, which limit their widespread application in flexible and stretchable electronic devices.
[0003] Silver nanowires (AgNWs) are a type of nanomaterial with excellent electrical conductivity. Their length is much greater than their diameter, which enables them to have good electron mobility and low resistivity, as well as good mechanical and optoelectronic properties. Compared with ITO, AgNWs not only have high electrical conductivity, but also provide strong mechanical flexibility while ensuring transparency. Common PET / AgNWs are widely used in the preparation of flexible organic solar cells and other fields, but when they are prepared into flexible optoelectronic devices, mechanical stability and long-term reliability are still facing challenges. This is mainly because after multiple deformations, the points where AgNWs intersect with each other are damaged, which increases the surface resistance or even insulation. Therefore, increasing the adhesion of the electrode on the flexible substrate and the deformation recovery ability are the key to constructing highly stable, flexible and stretchable transparent electrodes.
[0004] Thermoplastic polyurethane (TPU) has excellent flexibility and stretchability, high light transmittance, and high flexibility during processing. It can be well used as a substrate for preparing flexible and stretchable transparent electrodes. However, when preparing TPU / AgNWs flexible and stretchable transparent electrodes, if spin coating is directly performed on the formed TPU film, the formed AgNWs conductive layer will be rough and easy to fall off during stretching deformation. When the electrode is prepared by directly casting the dissolved TPU film on the surface of the pre-prepared AgNWs conductive layer using the casting method and then peeling it off, it may cause the AgNWs to be coated and insulated, making the electrode ineffective. At present, using PH1000 as a pre-coating layer for silver nanowires (AgNWs) can avoid the problems of rough AgNWs conductive layer and AgNWs being coated and insulated, but the performance of the prepared electrode, such as stability and durability, will be affected. Summary of the invention
[0005] In order to solve the above technical problems, the present invention proposes a method for preparing a highly stable, flexible and stretchable transparent electrode.
[0006] The technical solution adopted by the present invention is:
[0007] A method for preparing a highly stable, flexible and stretchable transparent electrode comprises the following steps:
[0008] a. Pre-treat the substrate;
[0009] b. preparing a conductive layer;
[0010] b1. Preparation of self-assembled monolayer film: After pretreatment, an effective area replacing the traditional electrode is reserved on the surface of the substrate using tape, and then an organosilicon compound is spin-coated on the surface of the substrate to form a self-assembled monolayer film;
[0011] b2. Preparation of silver nanowire layer: Prepare AgNWs dispersion, shake it and let it stand for a while, take out the upper solution, spin-coat the self-assembled monolayer, and then heat and anneal in steps to form a silver nanowire layer;
[0012] b3. Pre-coating the surface of the silver nanowires: washing the silver nanowire layer with an organic solvent, then spin-coating a PH1000 solution containing a surfactant on the silver nanowire layer, and then performing step-by-step heating annealing to obtain a pre-coated silver nanowire layer, that is, a conductive layer;
[0013] c. Preparation of flexible and stretchable transparent electrodes;
[0014] Prepare TPU solution, fix the substrate with the prepared conductive layer on a coating machine, peel off the tape, and use a layered spin coating method to spin coat the TPU solution; after spin coating, perform ultraviolet irradiation or annealing treatment, and then peel it off from the substrate to obtain a flexible and stretchable transparent electrode, and the side attached to the glass is the effective area of the electrode.
[0015] Preferably, in step a: the substrate is made of polished white glass; the pretreatment process is as follows: the polished white glass is cleaned in sequence by scrubbing with a dust-free cloth and detergent, ultrasonically treating with deionized water, and ultrasonically treating with ethanol, and then treating with ultraviolet ozone.
[0016] Of course, the substrate can also be a high-flatness material such as silicon wafer, PET, etc. Preferably, polished white glass is selected to facilitate observation of light transmittance and surface roughness.
[0017] Preferably, in step b1: the organosilicon compound is octadecyltrimethoxysilane, the spin coating amount is 50 μl-180 μl, the spin coating speed is 5000-8000 rpm, and the spin coating time is 20-60 s.
[0018] The above-mentioned organosilicon compound can also be other organosilicon compounds that can form a self-assembled monolayer film, in order to prevent the AgNWs from adhering to the substrate surface and being difficult to remove after the film is formed. The amount of the spin-coated solution is based on the amount that can actually cover the effective area, such as 50μl, 70μl, 90μl, 120μl, 180μl, etc. The spin-coating speed can be 5000 rpm, 5500 rpm, 7000 rpm, 7800 rpm, etc.
[0019] Preferably, in step b2: the diameter of the AgNWs in the AgNWs dispersion is 10-100 nm, for example, 10 nm, 20 nm, 30 nm, 45 nm, 80 nm, etc.; the length is 5-50 μm, for example, 5 μm, 15 μm, 30 μm, 45 μm, etc.; the concentration of the AgNWs dispersion is 5-20 mg / ml, for example, 5 mg / ml, 10 mg / ml, 15 mg / ml, 20 mg / ml, etc.; the solvent is water, ethanol or isopropanol, etc.
[0020] The amount of solution spin-coated on the self-assembled monolayer film is 30μl-120μl, which is based on the actual coverage of the effective area, for example, 30μl, 50μl, 70μl, 100μl, 120μl, etc. The spin-coating speed is 1000-5000 rpm, for example, 1000 rpm, 2000 rpm, 3000 rpm, 4000 rpm, 5000 rpm, etc., and the spin-coating time is 30-100s.
[0021] Preferably, in step b2, the step-by-step heating annealing process is as follows: the self-assembled monolayer film after spin coating is placed on a first heating stage, maintained at 100°C-110°C for 3-5 minutes, then placed on a second heating stage, maintained at 115°C-120°C for 3-5 minutes, and then placed on a third heating stage, maintained at 130°C-150°C for 3-5 minutes.
[0022] Preferably, in step b3: the organic solvent is ethanol or isopropanol; the surfactant is an alkyl alcoholamine compound or an organophosphorus compound, and the amount of the surfactant added accounts for 1%-3% of the volume of PH1000.
[0023] Preferably, in step b3, the step-by-step heating annealing process is as follows: the spin-coated silver nanowire layer is placed on a first heating stage, maintained at 50°C-60°C for 1-2 minutes, then placed on a second heating stage, maintained at 70°C-80°C for 2-3 minutes, and then placed on a third heating stage, maintained at 95°C-100°C for 3-5 minutes.
[0024] Preferably, in step c: the TPU solution is prepared by dissolving TPU in N,N-dimethylformamide, heating and stirring, and controlling the temperature to 100-130°C, for example, 100°C, 110°C, 120°C, 130°C, etc., until completely dissolved; the concentration of the TPU solution is 150-300 mg / ml, for example, 150 mg / ml, 180 mg / ml, 250 mg / ml, 290 mg / ml, etc.
[0025] Preferably, in step c: using a multiple spin coating method, each spin coating is performed to form a layer of TPU film, and then heating and annealing are performed to solidify;
[0026] The spin coating speed is controlled to be 1000-2000 rpm, such as 1000 rpm, 1300 rpm, 1700 rpm, and the spin coating time is 3-10s; the temperature rise annealing curing is to stand at a temperature of 35-55°C to form a film, such as 35°C, 40°C, 45°C, 50°C, etc.
[0027] In the above method, the electrode patterning preparation or full-area preparation is performed according to the actual electrode size required. Preferably, an effective area is reserved on the substrate by using a tape to achieve electrode patterning. Of course, it is also possible to use full-area preparation and then erase the invalid area, or use laser scribing to etch the effective area after full-area preparation.
[0028] In the above method, PH1000 is a product model, namely poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid (PEDOT:PSS), which can be directly purchased from the market.
[0029] In the above method, the thermoplastic polyurethane elastomer TPU can also be a highly transparent stretchable elastomer such as EVA (ethylene-vinyl acetate copolymer) and PDMS (polydimethylsiloxane).
[0030] The beneficial technical effects of the present invention are as follows:
[0031] (1) The present invention combines the pre-coating method with the film transfer method. During the preparation process, the AgNWs conductive layer is firstly spin-coated on the glass substrate, and then PH1000 is spin-coated to form a pre-coating layer, and finally TPU is spin-coated to form a film. After peeling off the film, a flexible transparent electrode with a TPU / PH1000 / AgNWs structure is obtained. Through the specific control of each step, the present invention makes the prepared electrode have excellent optical properties, low surface resistance, low surface roughness and excellent stability, and is suitable for application in flexible optoelectronic devices.
[0032] (2) When preparing the silver nanowire layer, the present invention adopts a step-by-step heating method for annealing, first slowly heating at a relatively low temperature to remove the solvent, and then heating at a high temperature to enhance the conductivity and mechanical properties of the silver nanowires. After the silver nanowire layer is coated, the silver nanowire layer is rinsed with an organic solvent to remove possible residual impurities and incompletely dissolved precursors; this process can not only effectively clean the surface of the silver nanowires, but also improve the bonding between the silver nanowires and the subsequent layers.
[0033] (3) The present invention spin-coats a poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid (PEDOT:PSS model PH1000) solution containing a surfactant on the silver nanowire layer, uses the surfactant to adjust the surface energy of PH1000, enhances the adhesion between the silver nanowires and PH1000, ensures that the silver nanowire layer and the PH1000 layer have a stronger bonding force, and prevents interlayer peeling during the use of the flexible electrode in the later stage. The surfactant can also promote the uniform distribution of the silver nanowires in the PH1000 layer. Through the introduction of the surfactant, the interface strength between the silver nanowires and PH1000 is effectively enhanced, avoiding the peeling phenomenon caused by insufficient adhesion, and improving the stability of the electrode under multiple stretching and bending.
[0034] (4) After spin coating, the conductivity of PH1000 is further optimized by using a step-by-step annealing process. The solvent is first removed at a relatively low temperature, and then the conductivity of the PH1000 layer is further improved by a step-by-step heating method to ensure that it has stable conductivity under repeated stretching and bending conditions. Specifically, the present invention ensures that the film structure of PH1000 is more compact by precisely controlling the annealing temperature and time, thereby effectively improving its conductivity. In addition, a step-by-step annealing method is used to first remove the solvent and residue at a relatively low temperature, and then enhance the conductivity of PH1000 at a moderately high temperature, thereby improving the charge transfer efficiency. Through this optimized annealing process, the conductivity of the PH1000 layer is significantly improved, so that it can still maintain a high conductivity under repeated bending and stretching.
[0035] (5) The present invention uses a multiple-layer spin coating method when spin coating TPU, that is, each layer of TPU film formed by spin coating is subjected to high-temperature annealing and curing to enhance the mechanical strength and transparency of the electrode layer by layer. Finally, the formed flexible transparent electrode is subjected to ultraviolet irradiation or high-temperature annealing treatment to further remove the solvent, enhance the compactness of the film, and ensure stable electrode performance. BRIEF DESCRIPTION OF THE DRAWINGS
[0036] Figure 1 This is a schematic diagram of the preparation process of the highly stable, flexible and stretchable transparent electrode of the present invention.
[0037] Figure 2(a) is a scanning electron microscope image of AgNWs spin-coated on a glass substrate; (b) is a scanning electron microscope image of the TPU / AgNWs flexible transparent electrode prepared in Comparative Example 1.
[0038] Figure 3 (a) is a scanning electron microscope image of PH1000 / AgNWs on a glass substrate; (bd) are scanning electron microscope images of TPU / PH1000 / AgNWs flexible transparent electrodes at different magnifications.
[0039] Figure 4 (a) is the atomic force microscopy image of AgNWs on a glass substrate; (b) is the atomic force microscopy image of TPU / AgNWs flexible transparent electrode; (c) is the atomic force microscopy image of PH1000 / AgNWs on a glass substrate; (d) is the atomic force microscopy image of TPU / PH1000 / AgNWs flexible transparent electrode.
[0040] Figure 5 (a) is the atomic force microscope image of glass / ITO; (b) is the atomic force microscope image of PET / ITO.
[0041] Figure 6 The surface resistance of the flexible transparent electrode of TPU / PH1000 / AgNWs structure finally constructed by spin coating AgNWs at different rotation speeds.
[0042] Figure 7 The transmittance of the flexible transparent electrode of TPU / PH1000 / AgNWs structure constructed when PH1000 is spin-coated at different rotation speeds.
[0043] Figure 8 The transmittance graphs of commercial ITO, TPU film, TPU / AgNWs and TPU / PH1000 / AgNWs prepared in the present invention.
[0044] Fig. 9 This is a graph showing the surface resistance change of the flexible stretchable transparent electrode prepared in Example 1 of the present invention under stretching and bending conditions. DETAILED DESCRIPTION
[0045] The inventors of this application found in the course of research that when PEDOT:PSS (PH1000) is used as a pre-coating layer for silver nanowires (AgNWs), the problems of rough conductive layer of AgNWs and insulation of coated AgNWs can be better solved. However, there are still some problems with conventional coating methods, mainly focusing on adhesion, conductivity and interface stability. First, due to the low surface energy of PH1000 itself, the bonding force between silver nanowires and PH1000 is weak, which can easily lead to interlayer peeling and loose adhesion, especially when the flexible electrode is repeatedly bent or stretched, the stability and durability of the electrode will be significantly affected. Secondly, although PH1000 has certain advantages in conductivity, its own conductivity performance depends on the thickness and uniformity of the film. In flexible electrode applications, especially in scenarios that experience high-frequency deformation, the conductivity of the PH1000 film may drop significantly, thereby affecting the performance of the entire electrode. Finally, since the spin coating process of PH1000 solution may lead to non-uniform coating, the silver nanowire layer may be unevenly distributed or locally aggregated during the pre-coating process, resulting in discontinuity of the conductive path and affecting the overall function of the electrode.
[0046] Therefore, this application proposes a method for preparing a highly stable flexible stretchable transparent electrode. The method improves the pre-coating process of PH1000 on AgNWs, so that the prepared flexible stretchable transparent electrode has excellent properties such as low surface resistance, high transmittance, and high deformation stability, and can be applied to flexible optoelectronic devices.
[0047] The present invention will be further described below in conjunction with specific embodiments.
[0048] Example 1
[0049] like Figure 1 As shown, a method for preparing a highly stable, flexible and stretchable transparent electrode comprises the following steps:
[0050] a. Pre-treat the substrate.
[0051] A polished white glass substrate with an area of 2 cm×2 cm was selected and pretreated as follows: the polished white glass was cleaned with a dust-free cloth and detergent, ultrasonically treated with deionized water (5 min), and ultrasonically treated with ethanol (30 min), and then dried with high-purity nitrogen for later use.
[0052] The cleaned and dried polished white glass substrate was then treated with ultraviolet ozone for 15 minutes to improve the hydrophilicity of the glass substrate surface, so that the coating material can better wet the surface, thereby improving the uniformity and adhesion of the coating.
[0053] b. Prepare a conductive layer.
[0054] b1. Preparation of self-assembled monolayer film: After pretreatment, polish the white glass surface and use tape to reserve an effective area with a width of 2 mm to replace the effective area of the traditional rigid electrode to achieve electrode patterning. Then place the obtained patterned substrate on the suction cup of the coating machine, and spin-coat octadecyltrimethoxysilane on the surface of the substrate to form a self-assembled monolayer film. The spin coating speed of octadecyltrimethoxysilane is controlled to 7000 rpm and the spin coating time is 30s.
[0055] b2. Preparation of silver nanowire layer: Prepare AgNWs dispersion, the diameter of AgNWs in the AgNWs dispersion is 30nm, the length is 10μm, the concentration of AgNWs dispersion is 10mg / ml, and the solvent is ethanol. AgNWs are dispersed in ethanol, and fully shaken before use to avoid agglomeration. After shaking, let it stand for 5 minutes, and take 50μl of the upper solution for spin coating.
[0056] The white glass pre-coated with octadecyltrimethoxysilane was placed on the chuck of the coating machine, and the AgNWs dispersion was spin-coated, and the spin-coating speed was controlled to be 3000 rpm and the spin-coating time was 30s. Then, the self-assembled monolayer after spin coating was placed on the first heating stage, kept at 100°C for 3 minutes, then placed on the second heating stage, kept at 115°C for 3 minutes, and then placed on the third heating stage, kept at 13°C for 5 minutes to form a silver nanowire layer.
[0057] b3. Pre-coating the surface of the silver nanowires: rinse the silver nanowire layer with ethanol, then place the patterned AgNWs layer based on the polished white glass substrate on the glue machine suction cup, and spin-coat the PH1000 solution containing the surfactant at 6000RPM for 30s. That is, the poly (3,4-ethylenedioxythiophene)-polystyrene sulfonic acid (PEDOT:PSS) model PH1000 is spin-coated on the surface of the AgNWs layer, and the surfactant Triton X-100 is added to improve its wettability at a volume percentage of 1%.
[0058] Then, step-by-step heating annealing is performed, such as annealing at 50° C. for 1 minute, annealing at 80° C. for 2 minutes, and annealing at 100° C. for 5 minutes, to form a pre-coating of the AgNWs layer, that is, to obtain a conductive layer.
[0059] c. Preparation of flexible and stretchable transparent electrodes;
[0060] TPU was dissolved in N,N-dimethylformamide (DMF), heated and stirred at 120° C. to completely dissolve the TPU, thereby preparing a 250 mg / ml TPU solution.
[0061] Fix the polished white glass substrate with the prepared conductive layer on the coating machine, peel off the tape, and use the layered spin coating method to spin coat the TPU solution. That is, the method of three times of spin coating is adopted, and each time of spin coating (1000RPM for 3s) forms a layer of TPU film, and then heats up and anneals to solidify (place on a 40℃ heating table for 3h to form a film).
[0062] After the spin coating is completed, ultraviolet irradiation is carried out and then it is peeled off from the polished white glass substrate to obtain a flexible and stretchable transparent electrode. The side attached to the polished white glass substrate is the effective area of the electrode.
[0063] Example 2
[0064] A method for preparing a highly stable, flexible and stretchable transparent electrode comprises the following steps:
[0065] a. Pre-treat the substrate.
[0066] A polished white glass substrate with an area of 2 cm×2 cm was selected and pretreated as follows: the polished white glass was cleaned with a dust-free cloth and detergent, ultrasonically treated with deionized water (5 min), and ultrasonically treated with ethanol (30 min), and then dried with high-purity nitrogen for later use.
[0067] The cleaned and dried polished white glass substrate was then treated with ultraviolet ozone for 15 minutes to improve the hydrophilicity of the glass substrate surface, so that the coating material can better wet the surface, thereby improving the uniformity and adhesion of the coating.
[0068] b. Prepare a conductive layer.
[0069] b1. Preparation of self-assembled monolayer film: After pretreatment, polish the white glass surface and use tape to reserve an effective area with a width of 2 mm to replace the effective area of the traditional rigid electrode to achieve electrode patterning. Then place the obtained patterned substrate on the suction cup of the coating machine, and spin-coat octadecyltrimethoxysilane on the surface of the substrate to form a self-assembled monolayer film. The spin coating speed of octadecyltrimethoxysilane is controlled to 7000 rpm and the spin coating time is 30s.
[0070] b2. Preparation of silver nanowire layer: Prepare AgNWs dispersion, the diameter of AgNWs in the AgNWs dispersion is 20nm, the length is 30μm, the concentration of AgNWs dispersion is 20mg / ml, and the solvent is ethanol. AgNWs are dispersed in ethanol, and fully shaken before use to avoid agglomeration. After shaking, let it stand for 10 minutes, and take 50μl of the upper solution for spin coating.
[0071] The white glass pre-coated with octadecyltrimethoxysilane was placed on the chuck of the coating machine, and the AgNWs dispersion was spin-coated, and the spin-coating speed was controlled to be 3000 rpm and the spin-coating time was 30s. Then, the self-assembled monolayer film after spin coating was placed on the first heating stage, kept at 110°C for 3 minutes, then placed on the second heating stage, kept at 120°C for 3 minutes, and then placed on the third heating stage, kept at 150°C for 5 minutes to form a silver nanowire layer.
[0072] b3. Pre-coating the surface of the silver nanowires: rinse the silver nanowire layer with ethanol, then place the patterned AgNWs layer based on the polished white glass substrate on the glue machine suction cup, and spin-coat the PH1000 solution containing the surfactant at 6000RPM for 30s. That is, the poly (3,4-ethylenedioxythiophene)-polystyrene sulfonic acid (PEDOT:PSS) model PH1000 is spin-coated on the surface of the AgNWs layer, and the surfactant Triton X-100 is added to improve its wettability at a volume percentage of 1%.
[0073] Then, step-by-step heating annealing is performed, such as annealing at 60° C. for 2 minutes, annealing at 70° C. for 2 minutes, and annealing at 95° C. for 3 minutes, to form a pre-coating of the AgNWs layer, that is, to obtain a conductive layer.
[0074] c. Preparation of flexible and stretchable transparent electrodes;
[0075] TPU was dissolved in N,N-dimethylformamide (DMF), heated and stirred at 120° C. to completely dissolve the TPU, thereby preparing a 250 mg / ml TPU solution.
[0076] Fix the polished white glass substrate with the prepared conductive layer on the coating machine, peel off the tape, and use the layered spin coating method to spin coat the TPU solution. That is, the method of three times of spin coating is adopted, and each time of spin coating (1000RPM for 3s) forms a layer of TPU film, and then heats up and anneals to solidify (place on a 50℃ heating table for 3h to form a film).
[0077] Then peel it off from the polished white glass substrate to obtain a flexible and stretchable transparent electrode, and the side attached to the polished white glass substrate is the effective area of the electrode.
[0078] Example 3
[0079] The preparation method is the same as that in Example 1. The difference is that in step b2, the rotation speed is controlled to be 1000 rpm for 30 seconds when spin coating AgNWs.
[0080] Example 4
[0081] The preparation method is the same as that in Example 1. The difference is that in step b2, the rotation speed is controlled to 2000 rpm for 30 seconds when spin coating AgNWs.
[0082] Example 5
[0083] The preparation method is the same as that in Example 1. The difference is that in step b2, the rotation speed is controlled to 4000 rpm for 30 seconds when spin coating AgNWs.
[0084] Example 6
[0085] The preparation method is the same as that in Example 1. The difference is that in step b3, the rotation speed is controlled to 3000 rpm for 30 seconds when the PH1000 solution is spin-coated.
[0086] Example 7
[0087] The preparation method is the same as that in Example 1. The difference is that in step b3, the rotation speed is controlled to 4000 rpm for 30 seconds when the PH1000 solution is spin-coated.
[0088] Example 8
[0089] The preparation method is the same as that in Example 1. The difference is that in step b3, the rotation speed is controlled to 5000 rpm for 30 seconds when the PH1000 solution is spin-coated.
[0090] Example 9
[0091] The preparation method is the same as that in Example 1. The difference is that in step b3, the rotation speed is controlled to 7000 rpm for 30 seconds when the PH1000 solution is spin-coated.
[0092] Comparative Example 1
[0093] The difference from Example 1 is that PH1000 is not spin-coated on the AgNWs layer for pre-coating. The specific steps are as follows:
[0094] (1) A polished white glass substrate with an area of 2 cm×2 cm was selected, and the glass substrate was cleaned in the following steps: scrubbing with a dust-free cloth and detergent, ultrasonic cleaning with deionized water (5 min), and ultrasonic cleaning with ethanol (30 min), and then dried with high-purity nitrogen gas for later use.
[0095] (2) The pre-cleaned polished white glass substrate obtained in step (1) is treated with ultraviolet ozone for 15 minutes to improve the hydrophilicity of the surface of the glass substrate so that the coating material can better wet the surface, thereby improving the uniformity and adhesion of the coating.
[0096] (3) Using a traceless tape, an effective area with a width of 2 mm is reserved on the surface of the glass sheet treated with UV ozone obtained in step (2) to replace the effective area of the traditional rigid electrode to achieve electrode patterning.
[0097] (4) The patterned substrate obtained in step (3) was placed on a coating machine suction cup and the organic silicon compound octadecyltrimethoxysilane was spin-coated at 7000 rpm for 30 seconds.
[0098] (5) The substrate pre-coated with octadecyltrimethoxysilane obtained in step (4) was placed on the chuck of a coating machine, and AgNWs were spin-coated at 3000 rpm for 30 s, and annealed at 120°C for 10 min. The AgNWs concentration was 10 mg / ml and dispersed in ethanol. The AgNWs were fully shaken before use to avoid agglomeration. After shaking, the substrate was left to stand for 5 min, and 50 μl of the upper solution was spin-coated.
[0099] (6) TPU was dissolved in DMF at a concentration of 250 mg / ml and heated at 120°C with stirring to completely dissolve it.
[0100] (7) Fix the glass sheet with the conductive layer prepared in step (6) on a coating machine, remove the traceless tape, and spin-coat the TPU dissolved in step (6) on the surface at 1000 rpm for 3 seconds, place it on a 40°C heating table for 3 hours to form a film, and after peeling it off, the side attached to the glass is the effective area of the electrode.
[0101] The test found that the TPU / PH1000 / AgNWs structured flexible stretchable transparent electrode constructed in Example 1 of the present invention can maintain a surface resistance of 15Ω / sq and a transmittance of more than 82%, which is similar to the performance of commercially available flexible stretchable transparent electrodes.
[0102] The performance of the electrodes prepared in Example 1 and Comparative Example 1 was compared and analyzed. It was found through testing that due to the lack of pre-coating of AgNWs with PH1000, the surface resistance of the electrode in Comparative Example 1 was much higher than that in Example 1, and even insulation occurred.
[0103] A more specific description will be given below in conjunction with the accompanying drawings.
[0104] (1) When preparing Comparative Example 1, only AgNWs were present. After the spin-coated TPU film was peeled off, the surface resistance increased significantly, and even insulation occurred in some areas. Figure 2 As shown in the figure, the TPU film formation process causes AgNWs to be coated, which increases its surface resistance and even makes it insulating.
[0105] (2) Characterize the surface using scanning electron microscopy (SEM). Figure 3As shown in (a), after PH1000 is spin-coated on the surface of AgNWs, the AgNWs are effectively covered and embedded in the PH1000 layer. The introduction of the PH1000 film layer makes the contact between the AgNWs closer, and at the same time, due to the excellent conductivity of PH1000, the conductive path of the electrode is optimized. After TPU is spin-coated and film-formed, as shown in Figure 3 As shown in (b), the pre-coating effect of the PH1000 layer on the AgNWs ensures that the AgNWs are embedded in the PH1000 layer flatly, avoiding the excessive coating or insulation effect of the TPU film on the AgNWs. Under the protection of the PH1000 layer, the AgNWs can maintain a high conductivity and effectively prevent the increase in surface resistance caused by excessive insulation coating. After the preparation of the highly stable flexible stretchable transparent electrode (TPA) of the present invention is completed, as shown in FIG. Figure 3 As shown in (c) in the figure, a regular and uniform dense grid structure is formed on the electrode surface. Figure 3 As shown in (d), AgNWs are evenly distributed and span these grids. The formation of this structure not only optimizes the conductivity of the electrode, but also improves the mechanical toughness and recoverability of the electrode. Due to the existence of the grid structure, the electrode can effectively disperse stress during stretching and bending, ensuring that the electrode can quickly return to its original shape after being deformed by external forces, thereby significantly improving the mechanical stability of the flexible electrode.
[0106] (3) Characterize the surface using atomic force microscopy (AFM). Figure 4 As shown in (a), when AgNWs are spin-coated on a glass substrate, since the diameter of the AgNWs is about 25-30 nm, the AgNWs are intertwined during the spin-coating process, resulting in a large surface roughness. Figure 4 (b) shows the surface characteristics after TPU is directly spin-coated on the AgNWs layer and formed into a film. It can be seen that the surface roughness is reduced, but part or all of the AgNWs are covered by TPU, which indicates that when directly preparing TPU / AgNWs flexible transparent electrodes, a large surface resistance may occur, and even insulation phenomenon may be caused. Figure 4 (c) shows that after spin coating PH1000 on the AgNWs surface, the surface roughness is reduced from 20.8nm to 13.1nm, indicating that the pre-coating layer of PH1000 effectively reduces the surface roughness and improves the surface flatness. Figure 4 As shown in (d), the surface roughness is further reduced, mainly because the surface after film formation is closely attached to the glass substrate, thus ensuring a high surface flatness. In order to compare with the traditional electrode, Figure 5AFM images of rigid ITO and PET / ITO are shown. The results show that the surface roughness of the TPA structured flexible transparent electrode is similar to that of the traditional electrode, indicating that the electrode has good prospects for application in flexible optoelectronic devices.
[0107] (4) General Figure 6 , Figure 7 and Figure 8 By comparison and optimization, when the rotation speed of AgNWs is 3000 rpm and PH1000 is 6000 rpm, the constructed TPU / PH1000 / AgNWs structure flexible transparent electrode can maintain a surface resistance of 15Ω / sq and a transmittance of more than 82%, which is similar to the performance of commercial flexible transparent electrodes.
[0108] (5) The stability of flexible transparent electrodes is the basis for flexible optoelectronic devices to achieve stretching and bending. Since AgNWs are pre-coated in highly conductive PH1000, the TPA structured flexible transparent electrode has the characteristics of low surface resistance and high stability. Fig. 9 After being folded in half thousands of times, the surface resistance did not increase, and the electrode did not fail after a tensile deformation of up to 150%.
[0109] The application scope of the TPU / PH1000 / AgNWs structure flexible transparent electrode prepared by the present invention includes but is not limited to: flexible organic solar cells, flexible perovskite solar cells, flexible photoluminescent devices, flexible LEDs, flexible sensors, etc. When the TPU / PH1000 / AgNWs structure flexible transparent electrode is used in the preparation of these flexible optoelectronic devices, it should be protected by the present invention.
[0110] It should be noted that the above are only preferred embodiments of the present invention and do not constitute any limitation to the present invention. Any simple modification, change or equivalent substitution of the above embodiments based on the technical essence of the present invention shall be included in the protection scope of the present invention.
Claims
1. A method for preparing a highly stable, flexible and stretchable transparent electrode, characterized in that The following steps are involved: a. Pre-treat the substrate; b. preparing a conductive layer; b1. Preparation of self-assembled monolayer film: After pretreatment, an effective area replacing the traditional electrode is reserved on the surface of the substrate using tape, and then an organosilicon compound is spin-coated on the surface of the substrate to form a self-assembled monolayer film; b2. Preparation of silver nanowire layer: Prepare AgNWs dispersion, shake it and let it stand for a while, take out the upper solution, spin-coat the self-assembled monolayer, and then heat and anneal in steps to form a silver nanowire layer; b3. Pre-coating the surface of the silver nanowires: washing the silver nanowire layer with an organic solvent, then spin-coating a PH1000 solution containing a surfactant on the silver nanowire layer, and then performing step-by-step heating annealing to obtain a pre-coated silver nanowire layer, that is, a conductive layer; c. Preparation of flexible and stretchable transparent electrodes; Prepare TPU solution, fix the substrate with the prepared conductive layer on a coating machine, peel off the tape, and use a layered spin coating method to spin coat the TPU solution; after spin coating, perform ultraviolet irradiation or annealing treatment, and then peel it off from the substrate to obtain a flexible and stretchable transparent electrode, and the side attached to the glass is the effective area of the electrode.
2. The method for preparing a highly stable, flexible and stretchable transparent electrode according to claim 1, characterized in that: In step a: the substrate is polished white glass; the pretreatment process is as follows: the polished white glass is cleaned in sequence by scrubbing with a dust-free cloth and detergent, ultrasonically treating with deionized water, and ultrasonically treating with ethanol, and then treating with ultraviolet ozone.
3. The method for preparing a highly stable, flexible and stretchable transparent electrode according to claim 1, characterized in that: In step b1: the organic silicon compound is octadecyltrimethoxysilane, the spin coating amount is 50 μl-180 μl, the spin coating speed is 5000-8000 rpm, and the spin coating time is 20-60 s.
4. The method for preparing a highly stable, flexible and stretchable transparent electrode according to claim 1, characterized in that: In step b2: the diameter of the AgNWs in the AgNWs dispersion is 10-100 nm, the length is 5-50 μm, the concentration of the AgNWs dispersion is 5-20 mg / ml, and the solvent is water, ethanol or isopropanol; The amount of solution for spin coating the self-assembled monolayer film is 30 μl-120 μl, the spin coating speed is 1000-5000 rpm, and the spin coating time is 30-100 s.
5. The method for preparing a highly stable, flexible and stretchable transparent electrode according to claim 1, characterized in that: In step b2, the step-by-step heating annealing process is as follows: the self-assembled monolayer film after spin coating is placed on a first heating stage, maintained at 100°C-110°C for 3-5 minutes, then placed on a second heating stage, maintained at 115°C-120°C for 3-5 minutes, and then placed on a third heating stage, maintained at 130°C-150°C for 3-5 minutes.
6. The method for preparing a highly stable, flexible and stretchable transparent electrode according to claim 1, characterized in that: In step b3: the organic solvent is ethanol or isopropanol; the surfactant is an alkyl alcoholamine compound or an organic phosphorus compound, and the added amount of the surfactant accounts for 1%-3% of the volume of PH1000.
7. The method for preparing a highly stable, flexible and stretchable transparent electrode according to claim 1, characterized in that: In step b3, the step-by-step heating annealing process is as follows: the spin-coated silver nanowire layer is placed on a first heating stage, maintained at 50°C-60°C for 1-2 minutes, then placed on a second heating stage, maintained at 70°C-80°C for 2-3 minutes, and then placed on a third heating stage, maintained at 95°C-100°C for 3-5 minutes.
8. The method for preparing a highly stable, flexible and stretchable transparent electrode according to claim 1, characterized in that: In step c: the TPU solution is prepared by dissolving TPU in N,N-dimethylformamide, heating and stirring, and controlling the temperature to be 100-130° C. until the TPU is completely dissolved; the concentration of the TPU solution is 150-300 mg / ml.
9. The method for preparing a highly stable, flexible and stretchable transparent electrode according to claim 1, characterized in that: In step c: using a multiple spin coating method, each spin coating is performed to form a layer of TPU film, and then heating and annealing are performed to solidify; The spin coating speed is controlled to be 1000-2000 rpm and the spin coating time is 3-10s each time; The temperature rise annealing curing is to stand at a temperature of 35-55°C to form a film.
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