Improvement of CIGS thin-film solar cell performance by optimization of Zn(O,S) buffer layer parameters

The effects of Zn(O,S) buffer layer parameters on CuInGaSe (CIGS) cell performance are investigated using a physically based solar cell model. The key issue for CIGS solar cells is to remove destructive effects like pinholes due to thinning buffer layer. Choosing Zn(O,S) instead of CdS as the buffer layer provides the benefit of more transmission. The current difference between cells with CdS and Zn(O,S) buffer layers is more obvious in thicker films. Three main properties were investigated: buffer layer thickness, doping density, and oxygen content. The cell performance is investigated as multiple parameters are varied simultaneously. The effects of all physical parameters of Zn(O,S) are dependent on each other, so that by increasing Zn(O,S) carrier concentration from 1018 to 1020 cm−3, the optimum oxygen content range to have maximum efficiency will be expanded from 50–75 to 30–90 %.