Transparent electrodes (TEs) have been widely studied as a key component of many optoelectronic devices such as solar cells, flexible light-emitting devices, transparent heaters, and smart windows. Currently, indium tin oxide (ITO) is extensively used as a transparent electrode for these devices owing to its high transparency, electrical conductivity, and chemical stability. However, the scarcity of indium, the expensive deposition method, and the brittleness of ITO prompted the search for new flexible, stable, and low-cost TEs. Silver nanowire (AgNW) networks appear as a promising alternative thanks to their high optical transparency, excellent electrical properties, and mechanical flexibility, and have indeed gained much attention in the last few years. To improve the integration of AgNW networks into industrial devices, their stability against electrical and/or thermal stresses needs to be enhanced. One of the applications of TE is electrochromic smart windows which have attracted great attention due to their potential applications in energy-efficient devices. Thanks to electrochromic materials that can alter their optical transparency as a response to an electrical input, smart windows can decrease the need for energy-intensive heating or air conditioning in buildings and improve the inhabitant's indoor comfort. AgNW networks appear as a promising alternative thanks to their high optical transparency, excellent electrical properties, and mechanical flexibility. However, the stability of AgNWs under electrical, thermal, and environmental stress remains a key issue for the applications.

The present work aims to prepare ITO-free electrochromic films using AgNW networks as a transparent electrode. The AgNW networks are deposited through spray-coating on transparent glass substrates, afterward, the electrochromic material is deposited using radio frequency magnetron sputtering. Bare-AgNWs undergo degradation in sputtering conditions. To avoid such degradation, the AgNW networks are coated with a thin conformal protective oxide layer, ZnO and SnO₂, using atmospheric pressure spatial atomic layer deposition (AP-SALD). The performance of different electrochromic materials, like V₂O­_5, WO₃, and NiO, deposited on AgNWs are investigated through cyclic voltammetry, chronoamperometry, and in-situ opto-electrochemical measurements. AgNWs-based electrochromic oxide thin films are then used for the fabrication of ECDs with AgNWs/WO₃-LiTFSI PMMA-NiO/AgNWs configuration. A hybrid material, known as surface-anchored metal-organic frameworks (SurMOFs) is also studied on flexible substrate revealing an unexpected protective role for the AgNW network in addition to good electrochromic performance. Moreover, AgNWs represent a promising alternative to ITO for flexible devices.

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