Lattice and electronic structure variations in critical lithium doped nickel oxide thin film for superior anode electrochromism

Abstract

Application of electrochromic anode material has recently attracted tremendous attention for fields of electronics, photonics and energy storage. While limited understanding of mechanisms of performance optimization and electrochromic process is still the hindrance for the development of such materials. Here, we demonstrate a novel lithium doped nickel oxide ultra-thin film with critical structure that can be synthesized via an one-step sputtering process, as a superior anode material for electrochromic device with extraordinary capability of deep coloring (tripled than nickel oxide film), large transmittance contrast (close to 70%) and high charge capacitance (13 mF cm−2). We observed extremely significant pronounced lattice expanding/reducing and in the electrochromic process of doped thin film. Variations of electronic structure were detected and we using the theoretical calculations reveal the presence of electronic defect states induced by lithium doping, which effectively reduces the band gap of nickel oxide and contributes bleaching and coloring. These findings shed new light on future development of electrochromic materials and devices for practical implementation.