Classification of metastabilities in the electrical characteristics of ZnO/CdS/Cu(In,Ga)Se2 solar cells

We experimentally distinguish between three types of metastable electrical behavior in Cu(In,Ga)Se-2-based heterojunction thin-film solar cells. A metastable increase of net acceptor concentration in the bulk of the Cu(In,Ga)Se-2 absorber material is induced by illumination with red light, an increase of net positive charge at the interfacial region is induced by blue light, and a reversible creation of negative charges occurs by the application of reverse bias at temperatures above 340 K. We discuss the physical origin of these metastabilities. (C) 2001 Elsevier Science B.V. All rights reserved.