Particle size and crystallinity dependent electron injection in Fluorescein 27-sensitized TiO2 films.

Influence of processing parameters, such as autoclaving and firing temperature, on the optical properties of nanocrystalline anatase TiO2 film and on the process of electron injection from the dye fluorescein 27 to the as-prepared films is studied. Transmission electron microscopy and steady-state and time-resolved femtosecond spectroscopy measurements indicate that the larger the TiO2 particle and the better its overall crystallinity, the faster the process of electron injection. Unraveling factors that control the properties of the sub-20-nm sized semiconductor particles, and by this the electron injection to them, is important for understanding the process of interfacial electron transfer from the dye to the semiconductor, as well as future optimization of the function of the photoelectrochemical cell based on dye-sensitized TiO2 films.