Published online by Cambridge University Press: 10 February 2011
How stable are Cu(In,Ga)Se2 solar cells? CuInSe2 is known also as an ionic Cu conductor and the Cu-In-Se system has a rich phase diagram. Two stability-related problems are treated from a thermodynamic point of view: -a- Cu migration, -b- phase segregation. We show how Cu migration imparts self-stabilization on the system. Based on recently reported results on the room temperature phase diagram of CuInSe2, we explain why an overlayer of an ordered vacancy compound (OVC) is not to be expected to appear as a separate phase, even though the surface composition corresponds to that of the I-III3V5 OVC compound.