Fast-switching electrochromic smart windows based on NiO-nanorods counter electrode

Abstract Not only do the outstanding electrochromic devices provide a fast switching response, but they can also block light and heat to reduce energy consumption in buildings. Herein, we fabricated an outstanding WO3/NiO nanorods-based electrochromic device consisting of a working electrode of 1D WO3 nanorods/ITO/glass substrate and a counter electrode of 1D NiO nanorods/ITO/glass substrate. The 1D NiO nanorods with a large surface area act as an ion storage layer, which can offer a huge number of electrons to form small polarons and the localized surface plasmon resonance on the 1D WO3 nanorods. The high small polaron content causes strong lattice distortion, which helps the Li+ ions easily diffuse into the 1D WO3 nanorods and gives the 1D WO3/NiO nanorods-based electrochromic device excellent electrochromic characteristics. The electrochromic characteristics include high optical transmittance difference (~61, ~89 %), high coloration efficiency (174, 386 cm2/C) and fast coloration/bleaching switching times (~2.05/~0.74 s, ~0.85/~1.0 s) at the wavelengths of 680 and 1000 nm, respectively. These characteristics make the WO3/NiO nanorods-based electrochromic device a very promising smart window candidate for lighting control and energy-saving applications.