Rear contact passivation for high bandgap Cu(In,Ga)Se2 solar cells with varying absorber thickness and flat Ga profile

In this study, six samples of Cu(In,Ga)Se2 solar cells with a high band gap (1.31 eV) and a flat Ga profile ([Ga]I([Ga]+[In]) approximate to 0.60) were produced. For every nominal absorber thickness of 0.5, 1.0 and 1.5 gm, the Mo rear contact of one sample was passivated with a 27 nm thick Al2O3 passivation layer with point contact openings, while the other sample's rear contact remained unpassivated. For the passivated cells, mainly large gains in the short circuit current lead to an up to 21%, 13% and 14% (relative) higher power conversion efficiency compared to the unpassivated cells