TEMPERATURE-INDEPENDENT ELECTRON-TRANSFER - RHODAMINE B/OXIDE SEMICONDUCTOR DYE-SENSITIZATION SYSTEM

The fluorescence spectrum and decay of rhodamine B (Rh B) adsorbed on insulator (SiO//2) and oxide semiconductors (ZrO//2, TiO//2 (anatase)) were measured in vacuo at temperatures in the range 4-300 K. The effect of temperature on both the intensity and decay rates of the fluorescence is very weak, indicating that the electron transfer (ET) from Rh B in the excited state to those semiconductors (SC) is almost an activationless process. The results lead to the conclusion that continuous levels in the conduction band of the SC serve as the electron acceptor state.