Detrimental Impact of Na Upon Rb Postdeposition Treatments of Cu(In,Ga)Se ₂ Absorber Layers

Passivation of the Cu(In,Ga)Se2 (CIGS)/Mo back contact using AlO x is studied to reduce recombination at this interface. Herein, RbF postdeposition treatment (RbF-PDT), a well-established method improve absorber and front interface properties used on back-passivated solar cells. It found that combination deteriorates performance due formation an injection barrier reduced acceptor concentration. Photoluminescence yield decay times show no indication increased defect recombination, as both are improved. With time-of-flight secondary ion mass spectroscopy, in-depth lateral alkali profiles measured. shown Na concentration higher /Mo Rb accumulates CdS/CIGS hypothesized released during RbF-PDT inhibits diffusion into CIGS layer. remains reduced. Modeling dark light current–voltage characteristics shows low doping responsible for V oc fill factor (FF). suggested commonly observed FF losses upon heavier PDT can be eliminated by adapting initial amount.