Retarded surface photovoltage response from dye molecules adsorbed on metal oxide surfaces

A retarded surface photovoltage response has been observed on metal oxide layers (SnO2: F, TiO2) covered with adsorbed dye molecules while only the dye molecules were excited by short laser pulses. The retardation ranged between 30 and 570 ns depending on the nature of the metal oxide and on surface treatment. Therefore, charge separation in space of electrons injected from dye molecules into metal oxides is strikingly different from ultrafast electron injection measured by time-resolved optical techniques. (C) 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.