Multicolor V2O5/TiO2 electrochromic films with fast switching and long lifespan for camouflage and information display

Abstract

V₂O₅, which has multicolor and energy storage properties, is a promising electrochromic material for multifunctional electrochromic devices, but its practical application is limited by its poor lifespan and long switching time. In this work, high-performance V₂O₅/TiO₂ films were fabricated by spraying a V₂O₅ solution on in situ-grown TiO₂ nanorods. Due to the porous structure formed between the TiO₂ nanorods and the remarkable electron transfer performance of TiO₂, the switching time of the V₂O₅/TiO₂ films decreased. Moreover, the strong adhesion between the TiO₂ nanorods and F-doped tin oxide (FTO) glass and the increased surface roughness of the substrates significantly improved the cycling stability of the V₂O₅/TiO₂ films. With a large transmittance modulation (47.8% at 668 nm), fast response speed (τ_c = 5.1 s, τ_b = 4.2 s), and long lifespan, V₂O₅/TiO₂ films were used as electrodes for the electrochromic energy storage device (EESD), which switched in six colors through color overlay: dark orange, sandy yellow, green-yellow, yellow-green, dark green, and dark brown. Inspired by pixel displays, EESDs were designed by segmenting V₂O₅ films to stagger the display of the electrochromic and ion storage layers, which presented 11 types of information based on different combinations of colors. This work provides inspiration for developing multifunctional electrochromic devices, especially for camouflage and information displays.