Preparation Of Flexible Silver Nanowires Transparent Electrode And Its Performance In Electrochromic Devices

Flexible transparent electrode have been widely applied in deformable batteries,flexible displays,solar cells,and wearable sensors.As the core component for flexible conductive decices,flexible transparent conductive films have become a focus of considerable research activities.Currently,indium tin oxide（ITO）is the most commonly used material in the current market due to its low electrical resistance and high optical transmittance.However,its drawbacks of high cost and brittleness are crucial problems that need to be overcome.Silver nanowires（AgNWs）random networks with high transmittance,low sheet resistance,and excellent mechanical flexibility have become the most promising candidates for electrode.However,there are many barriers to the application of electrode based on AgNWs,such as easy oxidization and weak adhesion to the substrates.Therefore,the purpose of this work is to prepare flexible transparent conductive films with excellent performance.This paper proposes to modify the surface of AgNWs to improve the flexibility and adhesion of the electrode;improve the chemical stability of the electrode by coating an amorphous carbon protective layer on the surface of AgNWs;the WO₃@AgNW core-shell nanowires are embedded in the polymer substrate to integrate the electrochromic layer,the conductive layer and the substrate to prepare stretchable silver nanowires with excellent photoelectric and electrochromic properties.An electrochromic device based on flexible silver nanowire transparent electrode has been constructed,and the influence of silver nanowire electrode on the electrochromic performance of the device has also been explored.The novel method modifying the surface of AgNWs with Si（NH₂）solution has enhanced the bonding force with other materials,thereby inhibiting the delamination of AgNWs from the substrate and reducing the high junction resistance between nanowire and wire.Compared with the pristine AgNW/PET,the resistance of the TiO₂/AgNW-Si（NH₂）/PET has advantages in terms of photoelectric performance and adhesion.TiO₂/AgNW-Si（NH₂）/PET has～83%transmittance and～10Ω/sq square resistance,and remaines almost unchanged after mechanical bending 5000 cycles（ΔR/R₀≈3.6%）and repeats peeling off cycles with 3M tape for100 times（ΔR/R₀≈6.0%）.Next,the TiO₂/AgNW-Si（NH₂）/PET film has been treated with TiO₂sol,in which the TiO₂sol is acted as a protective layer to prevent the oxidation of AgNWs.The flexible electrochromic film and device based on TiO₂/AgNW-Si（NH₂）/PET electrode have been constructed,and the electrochromic properties of the film and device have also been studied.The light modulation range of the film is～76%,the coloring response time is 9.9 s,the fading response time is5.8 s,and the coloring efficiency is 60.2 cm²C^-1.After 5000 bending times,the retention rate of the light modulation range exceeds～94%（from～76%to～72%）.A facile approach to fabricate AgNW-C core-shell nanowires has been derived from the carbonization of glucose by a one-pot solvothermal method.Systematic study of the effects of reaction time,reaction temperature and glucose concentration on the morphology,photoelectric properties and bending adhesion of AgNW-C/PET electrodes have been studied,revealing the formation and function of AgNW-C core-shell nanowires mechanism.The relative change rate ofΔR/R₀of the AgNW-C/PET electrode is～19.7%after exposure in air for 100 d.At the same time,the presence of polyhydroxyl on the surface of the carbon shell can improve the adhesion of AgNWs to the substrate.TheΔR/R₀of the AgNW-C/PET electrode is～2.7%or～40%after 2000 bending times or 100 peeling off times by a 3M tape test.The WO₃/AgNW-C/PET film has been fabricated and its electrochromic properties have been studied.The light modulation range of WO₃/AgNW-C/PET film after 200cycles is～72%,and the retention rate exceeds～95%.The flexible electronic devices is prone to delamination problems during the bending application process.Based on this,the integration of electrochromic layer and conductive layer in the electrode is fabricated via a WO₃@AgNW core-shell structure.And embed the core-shell structure into the flexible substrate PDMS to form WO₃@AgNW-PrePDMS electrode.Through the influence of reaction time on the morphology and structure of the synthesized WO₃@AgNW core-shell nanowires,the formation mechanism of WO₃@AgNW core-shell nanowires has been explored.The photoelectric and electrochromic properties of the stretchable WO₃@AgNW-PrePDMS electrode have been studied.The stretchable electrode can maintain stable electrical conductivity（ΔR/R₀≈8.3%and 14%）after 20,000bending cycles and stretching 1000 times.After a long-term electrochromic cycle,the light modulation range retention rate is～95%.After 2000 bending times,the light modulation range retention rate is～94%.WO₃@AgNW-PrePDMS flexible wearable electrochromic device has been constructed and studied.The light modulation range retention rate of device exceeds～98%in the electrochromic cycle test after 200 stretching times.The WO₃@AgNW core-shell nanowire network electrodes with embedded structures can be a strong candidate for wearable electrochemical energy devices in the future.