Metastable changes of the electrical transport properties of Cu(In,Ga)Se/sub 2/

The authors investigate the electrical transport properties of Cu(In,Ga)Se/sub 2/ polycrystalline thin films and solar cells during and after illumination or forward bias in the dark (the latter only for the cells). For the thin films, they find persistent photoconductivity. In the solar cells, they observed relaxation of the open circuit voltage and a metastable increase of the voltage under constant forward current in the dark. Both phenomena are accompanied by an increase in the sample capacitance. They present a model that explains all the observed metastable phenomena as a consequence of trapping of minority carriers in the bulk of the Cu(In,Ga)Se/sub 2/ material.