Transport mechanisms in ZnO/CdS/CuInSe2 solar cells

The transport mechanisms in ZnO/CdS/CuInSe2 solar cells prepared by ARCO (now Siemens) Solar Inc. have been analyzed by measurements of current versus voltage at different temperatures in the dark, short-circuit current versus open-circuit voltage at different temperatures in the light, spectral response of quantum efficiency, and junction capacitance. In the dark, recombination in the depletion region and/or thermally assisted tunneling are the dominant transport mechanisms. The observation of a smaller open-circuit voltage than would be predicted from the dark transport parameters is the result of a small change in the transport parameters under illumination, probably without a change in transport mechanism.