Achievement of high electrochromic performance of TiO2 thin films prepared via spray pyrolysis method, influence of annealing process

In this study, an optimised TiO2 thin film was first prepared by the traditional spray pyrolysis method on SnO2:F (FTO) coated glass substrates, and then it was annealed at 450 degrees C in an ambient air atmosphere for different time durations of 1, 2, and 3 h. The FESEM images, XRD diffractograms, Raman and PL spectra indicate that compared to the pristine state, the annealing process has considerably affected the morphology and improved the crystallinity and stoichiometry of the layer. The electrochromic (EC) measurements revealed that the 3h annealed sample has the highest ever reported colouration efficiency of 91.54 cm2.C-1 (approximately 30 times bigger than the related reports) and low colouration and bleaching times of 0.2 and 1.1 s, respectively.