The role of surface states in the ultrafast photoinduced electron transfer from sensitizing dye molecules to semiconductor colloids

Investigations on the ultrafast electron injection mechanism from the dye alizarin to wide band gap semiconductor colloids aqueous medium are presented, combined with detailed studies on population, depopulation and relaxation phenomena in trap states and their influence on the injection process. The measurements underline the crucial role of trap states in the injection mechanism of electrons from dye molecules to semiconductor surfaces.