Electrochromic Performance of NiO x Thin Film on Flexible PET/ITO Prepared by Nanocrystallite-Dispersion Sol

Abstract

. An electrochromic nickel oxide thin film was fabricated on a flexible PET/ITO substrate using a nanocrystallite- dispersed coating sol and bar coater. Nanocrystalline NiO x of 3-4 nm crystallite size was first synthesized by base precipitation and thermal conversion. This NiO x nanocrystallite powder was mechanically dispersed in an alcoholic solvent mixed with a silane binder to prepare a coating sol for thin film. This sol method is different from the normal sol-gel method in that it does not require the conversion of precursor by heat treatment. Therefore, this method provides a very facile method to prepare NiO x thin films on any kind of substrate and it can be easily applied to mass production. The electrochromic performance of this NiO x thin film on PET/ITO electrode with a thickness of about 400 nm was investigated in a nonaqueous LiClO 4 electrolyte solution by cyclic voltammetric and repeated chronoamperometric measurements in conjunction with spectrophotome-try. The visible light modulation of 44% and the colorization efficiency of 41 cm 2 /C at 550 nm were obtained at the step potentials of -0.8/+1.2 V vs Ag and a duration of 30 s.