Electronic transport in semiconductor nanoparticles for photocatalytic and photovoltaic applications

It is shown by contactless transient photoconductance measurements that electron transport in TiO2 is highly dispersive and is strongly influenced by surface treatments. A fast recombination process is observed after band to band excitation. Oxalic acid absorbed at the surface slows the decay appreciably, as does alcohol. The electron transport in TiO2 films and powder of the same composition is nearly identical pointing to an only minor importance of inter grain transport for the present measurements (up to 100 μs). Dye sensitization of TiO2 leads not only to charge carrier generation by light in the visible range but also seems also to improve the electron transport properties.