The synergistic effect of oxygen vacancies and localized surface plasmon resonance on improving electrochromism for TiO ₂ films

Titanium dioxide (TiO 2 ), as an electrochromic material, shows immense application potential in fields, such as electronic displays and smart windows. To further improve electrochromic property of TiO 2 , the carbon-doped TiO 2 (C-TiO 2 ) film with high oxygen vacancy concentration were prepared by combining the hydrothermal and heat treatment techniques. Furthermore, TiO 2 /Cu and C-TiO 2 /Cu films with local surface plasmon resonance (LSPR) effect were fabricated by electrodepositing Cu nanoparticles, greatly improving the electrochromic performance of the films. The analysis results indicate that the C-TiO 2 /Cu film shows the shortest switching time (7 s/5 s), the highest coloration efficiency is 80.68 cm 2 /C and the largest transmittance modulation 61.7 % at 545 nm. The density functional theory (DFT) calculation indicates that oxygen vacancies can accelerate the insertion and removal of ions, as well as the electrochemical reaction. In addition, the introduction of Cu improves the local electronic structure, thereby increasing electron transitions and conductivity. That is to say, under the combined effect of oxygen vacancies and LSPR, the electrochromic properties of TiO 2 film have been significantly enhanced. This work provides reference significance for the development of electrochromism.