Cu(In,Ga)Se2 film formation from selenization of mixed metal/metal-selenide precursors

For Cu(In,Ga)Se-2 films made by the selenization of metallic precursors, Ga accumulation near the back contact prevents the achievement of high-voltage solar cells. In this work, selenization of mixed metal/metal-selenide precursors has been evaluated with respect to the composition distribution in the Cu(in,Ga)Se2 film and device performance. Four types of precursors consisting of electrodeposited and evaporated Cu-Se/Ga/In and (In,Ga)-Se/Cu were reacted in hydrogen selenide at 450 degrees C for 5, 15, and 90 min with metallic Cu0.8Ga0.2/In precursors as a control. Ga accumulation near the back contact in the selenized films was generally observed except for one precursor With a Cu-Se/Ga/In structure and excess Se in the Cu-Se layer, which had the maximum Ga concentration in the middle of the film, Enhanced Ga incorporation into the Cu(In,Ga)Se-2 is shown by X-ray diffraction for the precursors made from electrochemically deposited Cu-Se and changes in the bandgap were observed in the device behaviors. (C) 2009 Elsevier B.V. All rights reserved