Preparation, characterization and electrochromic properties of amorphous Gd-doped TiO2 films

Abstract

Titanium oxide has been widely studied in the field of electrochromism due to its unique color-changing behavior induced by ion insertion. In this paper, amorphous Gd-doped TiO2 films were synthesized via the RF magnetron reactive sputtering. The effects of Gd doping on the electrochromic performance of TiO2 films were explored in detail. The improved coloration efficiency of ∼60% at 540 nm for low Gd-doped TiO2 film (0.61%) is due to the formation of monoclinic Gd2O3 island nanostructure on the surface of TiO2, which enhances the reaction kinetics and charge capacity of the film. The wide optical modulation (73% at 650 nm), large coloration efficiency (59.7 cm2 C−1 at 650 nm) and short response time (coloring time is 16.9 s, bleaching time is 9.1 s) were obtained for the moderately Gd-doped TiO2 film (0.83%). However, for the high Gd-doped TiO2 films (≥1.0%), the coloration efficiency reduced, which is due to the excessive Gd2O3 hindered the electrolyte penetration into the TiO2 active material. By studying the effects of Gd doping on the electrochemical performance of TiO2, it can provide a valuable reference for determining the appropriate doping element and content for electrochromic materials.