Preparation, characterization and electrochromic properties of amorphous Gd-doped TiO 2 films

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 TiO 2 films were synthesized via the RF magnetron reactive sputtering. The effects of Gd doping on the electrochromic performance of TiO 2 films were explored in detail. The improved coloration efficiency of ∼60% at 540 nm for low Gd-doped TiO 2 film (0.61%) is due to the formation of monoclinic Gd 2 O 3 island nanostructure on the surface of TiO 2, which enhances the reaction kinetics and charge capacity of the film. The wide optical modulation (73% at 650 nm), large coloration efficiency (59.7 cm 2  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 TiO 2 film (0.83%). However, for the high Gd-doped TiO 2 films (≥1.0%), the coloration efficiency reduced, which is due to the excessive Gd 2 O 3 hindered the electrolyte penetration into the TiO 2 active material. By studying the effects of Gd doping on the electrochemical performance of TiO 2, it can provide a valuable reference for determining the appropriate doping element and content for electrochromic materials.