Surface States at CuInSe2/Aqueous Electrolyte Interface

Abstract

Impedance measurements were used to evaluate the relative band edge positions of single crystal p-CuInSej electrodes in aqueous 0.1M IQS04 solution by measuring die extrapolated flat-band potentials, Vf t . We find that Vf t can be shifted by oxidation and reduction of the electrode surface and this observation was verified by chopped light current-potentialmeasurements. The surface state density distribution responsible for this shift was evaluated and found that it islocated at 0.43 eV above the valence band with a peak density of 3x101 4 eV'1 cm' 2 and it could be removed by electrochemical reduction