Electrochromic Properties of LixNiyO Films Deposited by RF Magnetron Sputtering

Electrochromic properties of a series of LixNiyO films were studied to obtain the films that give a good reversible electrochromic reaction in a nonaqueous electrolyte solution. We paid attention to the lithium content in the films. The films were deposited by radio-frequency (rf) magnetron sputtering with LixNiyO targets under different conditions. The lithium contents were selected by using three different LixNiyO targets. NiO pellets were also used for cosputtering with the targets to finely adjust the lithium content in LixNiyO films. We found that a LixNiyO film gave a high electrochromic coloration efficiency when the lithium content in the film was adjusted to about 0.2. The X-ray diffraction (XRD) study showed that the crystalline Li2Ni8O10 film yielded good electrochromic performance, and that the (102) XRD peak was dominant in the films.