Evaluation of Perovskite Photo-sensors with Electron-beam Evaporated Titanium Dioxide Films

Abstract

We have investigated a perovskite photo-sensors with electron-beam evaporated titanium dioxide (TiO2) film as an electron transport buffer layer. The TiO2 films have been deposited on indium-doped tin oxide (ITO) glass substrate at room temperature. Then, prepared TiO2 films are annealed at different temperatures of between room temperature and 500°C. Device structure is ITO/TiO2/Perovskite layer/2,2,7,7-tetrakis (N,N-di-p-methoxyphenylamine)-9,9-spirobifluorene/Au. Before and after annealing process, TiO2 films have changed from an amorphous to crystalline structure mixed with anatase and rutile phases. For a sensing characteristics, a ratio of photo- and dark-current was 1.1×103 without annealing condition. It is assumed that a flat device structure and a larger photocurrent under illumination are effective to reduce carrier generation site.