The electrochemical cathodic template synthesis of nickel hydroxide thin films for electrochromic devices: Role of temperature

Abstract

The influence of temperature on the synthesis of Ni(OH)2 electrochromic films prepared using the cathodic template method has been investigated. The influence of deposition temperature on the morphology of nickel hydroxide films has been determined. By means of scanning electron and atomic-force microscopy, it has been established that surface morphology depends on deposition temperature. The flattest film surface corresponded to a deposition temperature of 30 °C, which indicated high optical properties. The maximum profile shift of films deposited at different temperatures was 400nM, while for the film deposited at 30 °C - 212 nM. By means of X-ray diffraction, it has been established that all films have crystal lattice similar to α-Ni(OH)2, with a high number of defects. It also has been discovered that at a deposition temperature of 20-60 °C, a peak at 2θ=16° appears on the diffraction pattern, the highest intensity of which corresponds to the process temperature of 30-40 °C. By means of cyclic voltamperometry and recording of transmittance changes, it has been demonstrated that nickel hydroxide film deposited at 30 °C has the best electrochemical and optical properties. A partial correlation between optical and electrochemical properties of films deposited at different temperatures has been noted.