Improved electrochromic performances of NiO based thin films by lithium addition: From single layers to devices

Abstract

Aiming at enhancing the electrochromic properties of anodically colored NiO thin films, lithium doped NiO thin films were grown on FTO/glass substrates, by the pulsed laser deposition (PLD) method. Optimized conditions, namely a room temperature substrate under 10 Pa oxygen pressure were used. Comparison with undoped NiO thin films indicates that lithium doping deteriorates NiO cubic phase (1 1 1) preferred orientation and also induces lattice disorder. The investigation of the electrochromic properties of Li-Ni-O thin films in aqueous liquid electrolyte, 1 M KOH, on the one hand and in hydrophobic lithium conductive ionic liquid, 0.3 M LiTFSI in BMITFSI, on the other hand, demonstrates an improvement in the electrochromic performances with lithium doping. Finally, electrochromic devices built on the association of WO 3 and Li-Ni-O thin films and using the above quoted ionic liquid blended with PMMA as electrolyte are reported. Good electrochromic performances and neutral color are shown. © 2012 Elsevier Ltd.