Kiyoshi Miyashita

Photoluminescence study of electron–hole recombination dynamics in the vacuum-deposited SiO2/TiO2 multilayer film with photo-catalytic activity

Abstract Photoluminescences were observed from vacuum-deposited TiO 2 (240 nm set-thick) and SiO 2 /TiO 2 multilayer films with photo-catalytic activities. More intense luminescence was observed from the SiO 2 (20 nm set-thick)/TiO 2 multilayer film than from the bare TiO 2 film, the former film being known to have higher photo-catalytic activity and photocurrent. The time-resolved photoluminescence upon excitation at 266 nm using a femtosecond pulse laser system showed bi-exponential decays. The two decay lifetimes of the emission from the multilayer film were both found to be longer than those from the bare TiO 2 film. This finding indicates the presence of longer-lived photo-generated charge carriers at the SiO 2 /TiO 2 interface, where the nanometer-scale SiO 2 overlayer suppresses electron–hole recombination.