Optical properties of composited TiO2-aluminium-doped ZnS photoanode

Abstract

Abstract A composited photoanode for optoelectronic devices have widely attracted much attention for many decades. In this work, wide band gap semiconductors, ZnS, and aluminium-doped ZnS were synthesized through simply chemical synthetic route with band gap energy of 3.67 – 3.69 eV. The thin films of TiO2/ZnS and TiO2/aluminium-doped ZnS composites with various concentration were prepared by doctor blade technique. By means of X-ray diffraction, the thin film structures of TiO2 is rarely dominated by ZnS or aluminium-doped ZnS. A ruthenium sensitizer (N719) was sensitized on the composited thin films. The absorption and photoluminescence of the composited photoanode were characterized, indicating the band gap energy of 3.41 eV for all thin films. It was observed that both ZnS and aluminium-doped Zns reduce the amount of dye uptake. Also, the photoluminescence of dye sensitized TiO2/ZnS and TiO2/aluminium-doped ZnS photoanode was rather blue-shifted and enhanced with the increasing of ZnS or aluminium-doped ZnS amount. Moreover, using Time Correlated Single Photon Counting technique (TCSPC), the emission lifetimes of dye sensitized TiO2, TiO2/ZnS and TiO2/aluminium-doped ZnS anodes are 3.32 ns, 8.40 ns and 6.42 ns, respectively which indicate the charge injection from excited dye to photoanode.