Comparison of electrochromic properties of NiO films prepared by chemical bath deposition and spin coating

We report the electrochromic properties and surface structures of NiO films prepared by chemical bath deposition (CBD) and by spin coating (SC). The NiO films made by CBD exhibited large electrochromic color change compared with those made by SC. Surface micrographs observed by means of scanning electron microscope showed that the structure of the NiO film made by CBD was porous, while SC film had a smooth surface. The large transmittance change of CBD film is due to the porous structure of the CBD film. In addition, we show the transmittance change of CBD film depends on the deposition time, and it has a maximum value at a certain deposition time.