Influence of Cu(In,Ga)(Se,S)2 surface treatments on the properties of 30 × 30 cm2 large area modules with atomic layer deposited Zn(O,S) buffers

We report the effect of Cu(In,Ga)(Se,S)2 absorber surface treatments on the properties of atomic layer deposited-Zn(O,S) buffered 30 × 30 cm2 large area modules. The absorber is prepared by the sequential process. H2O and KCN solution treatments are investigated. The absorber surface treatment is found to influence significantly the open circuit voltage and the fill factor of the full modules. Light soaking related metastabilities are also found to depend on the type of treatment. While both H2O and KCN treatments are efficient at removing Se-oxides and Na2HCO3, the KCN treatment is found to remove additionally Ga-oxides and elemental Se that are detected on the surface of the absorber. A 30 × 30 cm2 module aperture efficiency up to 12.3% could be achieved with KCN surface treatment of the absorber.