An all-solid-state electrochromic device based on NiO/WO3 complementary structure and solid hybrid polyelectrolyte

An all-solid-state electrochromic (EC) device based on NiO/WO3 complementary structure and solid polyelectrolyte was manufactured for modulating the optical transmittance. The device consists of WO3 film as the main electrochromic layer, single-phase hybrid polyelectrolyte as the Li+ ion conductor layer, and NiO film as the counter electrochromic layer. Indium tin oxide- (ITO) coated glass was used as substrate and ITO films act as the transparent conductive electrodes. The effective area of the device is 5×5 cm2. The device showed an optical modulation of 55% at 550 nm and achieved a coloration efficiency of 87 cm2 C−1. The response time of the device is found to be about 10 s for coloring step and 20 s for bleaching step. The electrochromic mechanism in the NiO/WO3 complementary structure with Li+ ion insertion and extraction was investigated by means of cyclic voltammograms (CV) and X-ray photoelectron spectroscopy (XPS).