Theoretical investigation of the effect of Ga content on the power conversion efficiency in ZnO/CdS/Cu(In,Ga)Se2 cells

Abstract

Power conversion efficiency of solar cells is theoretically expected to have its maximum at an absorber energy band gap of E_g 1.4 eV, but experimentally it is found at E_g = 1.18 eV for ZnO/CdS/Cu(In,Ga)Se₂ cells. In the present work, the explanation of this shift is sought in terms of optical losses through the window layer and interface recombination. The calculated results are compared with theoretical and experimental findings as reported in the literature.