Electrochromic nickel oxide thin films by a simple solution process: Influence of post-treatments on growth and properties

Abstract Nickel oxide is one of the few inorganic compounds that combines p -type behavior and large band gap making it very attractive for numerous optoelectronic applications. A very simple and reproducible method to grow nickel oxide thin films with accurate control of their structural, optoelectronic and electrochromic properties is reported in this work. The procedure consists in spin coating a nickel (II) 2-ethylhexanoate solution, followed by an ultraviolet (UV) treatment and a thermal annealing at moderate temperature (T anneal p -type nickel oxide films with high transparency in visible light range, band gap values between 3.6 and 3.8 eV and a doping level up to 8 × 10 20 cm −3 (as determined by Mott-Schottky measurements) has been achieved. Finally, NiO x layers presented efficient electrochromic behavior with >500 coloration/bleaching cycles showing negligible degradation.