Influence of Conduction Band Offsets at Window/Buffer and Buffer/Absorber Interfaces on the Roll-Over of J-V Curves of CIGS Solar Cells

By comparing simulated and measured current-voltage (J-V) characteristics of a high efficiency Cu(In,Ga)Se
₂
(CIGS) solar cell, we investigate the effect of conduction band offsets at window/buffer and buffer/absorber interfaces on the roll-over of the J-V curves with temperature. We simulate the J-V characteristics in the temperature range 300 K - 100 K, achieving good fits with measurements by describing the transport of electrons over the barrier at the ZnO/CdS interface by the thermionic-emission theory, and including a Schottky contact at the back CIGS/Mo interface.