Brown coloration and electrochromic properties of nickel doped TiO2 thin films deposited by nebulized spray pyrolysis technique

Abstract

Titanium dioxide (TiO2) is a promising candidate for electrochromic smart window and energy applications. In the present work, an eco-friendly approach to spray deposition technique was used to deposit undoped and nickel doped TiO2 thin films using glycerol as an additive. The effect of nickel doping on the microstructure, morphology, composition, magnetic, and electrochromic properties of TiO2 was investigated in detail. Under the action of negative voltage, the undoped TiO2 films exhibit blue coloration, whereas, the nickel doped TiO2 films exhibit brown coloration due to Ni2+ induced defects. The 6% nickel doped TiO2 film achieved a high reversibility of 82% and high transmittance modulation of 48.5%, with a colouration efficiency of 267 cm2/C, fast response of 2.3 s for colouration and 2.5 s for bleaching, compared to other nickel doped TiO2 films.