Effect of crystal orientation in Cu(In,Ga)Se 2 fabricated by multi-layer precursor method on its cell performance

Abstract

Abstract Cu(In,Ga)Se2 (CIGS) films with different crystal orientations and Ga/(In + Ga), Ga/III, profiles are fabricated by the so-called “multi-layer precursor method”, utilizing multi-layer co-evaporation of material sources. In this literature, the crystal orientation and averaged Ga/III near the CIGS surface, estimated from the Ga/III profile, are investigated to improve the cell performance, especially open-circuit voltage (VOC). It is revealed that the VOC increases and more enhances with (220/204)-oriented CIGS absorbers, when the averaged Ga/III near the CIGS surface increases. The conversion efficiency of the solar cell on flexible stainless steel substrate is ultimately improved by the manipulations of the crystal orientation, namely, I(220/204)/I(112) of approximately 1.7, and the averaged Ga/III near the CIGS surface of 0.38 under the multi-layer precursor method.