An efficient multi-color electrochromic electrode based on nanocomposite of aniline and o-toluidine copolymer with nickel oxide

Abstract

As an electrochromic material, NiO has a distinct color conversion, but its single color variation limits its application. In this study, NiO-based multi-color electrochromic films were prepared by using simple hydrothermal and electrodeposition methods. The composite electrochromic film can achieve a variety of color changes in yellow, green, blue and dark brown. NiO provides the substrate for organic copolymers, bringing large contact areas and ion channels, while the copolymerization and recombination of aniline-o-toluidine copolymers achieve a series of rich color changes. The results show that five color changes from colorless to dark brown can be achieved between −1 and 1.5 V. By controlling the applied voltage and the transition between the redox states of the film, the composite film is yellow at 0.2 V, green at 0.5 V, blue at 0.8 V, and dark brown at 1.5 V. The composite film has unprecedented stability. The improvement of cyclic stability is attributed to the uniform and dense coating of nickel oxide on the surface after being combined with copolymer. This encapsulation form will affect the ions entering the deep layer of NiO, reduce the erosion of NiO, and improve the cycling stability of NiO to a certain extent. This is fully demonstrated by the cyclic stability test. After 1000 cycles, the composite film can still show excellent optical modulation range. This study provides reference for the development of NiO multi-color electrochromic materials.