Self-Powered Rewritable Electrochromic Display based on WO_3-x Film with Mechanochemically Synthesized MoO_3–<i>y</i> Nanosheets

Abstract

Electrochromic displays with bistable color states provide a promising means toward transparent human-machine interfaces. However, the need for external power and the weak optical modulation in the visible light region of most electrochromic devices hinder their practical applications in displays. Here we prepare the MoO_3-<i>y</i>/WO_3-<i>x</i> films based on MoO_3-<i>y</i> nanosheets, which show a dark blue color that matches the response of the eye and meets visual comfort standards compared to pure WO_3-<i>x</i> film. By introducing the highly transparent Al³⁺ ion hydrogel layer, a convenient electrochromic device driven by the internal chemical potential has been designed. The device based on the MoO_3-<i>y</i> /WO_3-<i>x</i> film exhibits a high optical modulation in the whole visible light range and can operate at self-powered mode with fast response speed and excellent cycle stability. Moreover, we develop an ionic writing board based on the MoO_3-<i>y</i>/WO_3-<i>x</i> film to surmount the fixed display information issue in conventional electrochromic displays. The ionic writing board exhibits excellent visual display quality and realizes arbitrary writing with a self-powered characteristic. This work provides a simple mechanochemical synthesis procedure of MoO_3-<i>y</i> nanosheets and an ingenious design of self-powered electrochromic devices, which will enable the development of next-generation high-performance electrochromic displays.