Cobalt and tantalum additions for enhanced electrochromic performances of nickel-based oxide thin films grown by pulsed laser deposition

Aiming at improving the durability of anodic electrochromic nickel oxide thin films, Ni-M-O (M = Co. Ta) thin films were grown by pulsed laser deposition (PLD), using optimized conditions, namely room temperature and 10(-1) mbar oxygen pressure. For low Co and Ta contents (< 5%), both additions lead to a loss of the [1 1 1] preferred orientation of the NiO rock-salt structure followed by a film amorphization with increasing Ta amount. Among the two series of metal additions (M < 20%), the Ni-Co-O (5% Co) and Ni-Ta-O (10% Ta) thin films show the highest electrochemical performances especially in respect of improved durability. If the enhanced properties are associated with a limited dissolution of the oxidized phase for the Ni-Ta-O system, the opposite trend is observed for the Ni-Co-O system as compared to pure NiO. (c) 2005 Elsevier B.V. All rights reserved.