Numerical Modelling of Ultra Thin Cu(In,Ga)Se2 Solar Cells

Various thicknesses of copper-indium-gallium-diselenide (CIGS) absorber layer are incorporated into numerical simulation by Solar Cell Capacitance Simulator (SCAPS) to investigate the performance of ultra thin CIGS solar cells. CuIn1-xGaxSe2 absorber layer thickness is varied from 0.3-1.0 μm. Results show that the performance of CIGS solar cells decreases as the absorber layer thickness is decreased. Conversion efficiencies of 10.74% and 14.36% are achieved for cells with 0.3 μm and 1.0 μm thick absorber layers, respectively. Incorporation of band gap grading or commonly known as back surface field in the ultra thin CIGS solar cells improves the performance of the cells. In this study, back surface field is incorporated in the numerical modelling of the ultrathin CIGS solar cells. For the graded cells, efficiencies of 12.38% and 17.26% are achieved for cells with 0.3 μm and 1.0 μm thick absorber layers. These improvements are attributed to the less recombination loss at the CIGS/Mo interface. This study shows ultra thin CIGS solar cells have comparable performance parameters with the conventional CIGS solar cells.