Influence of silver incorporation on CZTSSe solar cells grown by spray pyrolysis

Abstract

Chemical spray pyrolysis was employed to prepare kesterite Cu2ZnSnS4 layers with different Ag contents. The Cu2ZnSnS4 layers were processed at 350°C from solutions of Cu, Ag, Zn and Sn metal salts and thiourea dissolved in water as the most environmentally friendly solvent. The as-prepared layers were subsequently annealed at high temperature in chalcogen atmosphere in order to obtain well crystallized kesterite Cu2ZnSn(S,Se)4 absorber layers. The influence of different Ag contents on the properties of the as-prepared layers, the resulting absorbers as well as the devices performance was investigated.Enhanced crystallinity and grain growth were observed for Ag containing as-prepared layers as well as selenized layers. As a potential consequence, this enhanced grain growth appears to facilitate the formation of MoSe2 layer at the back contact/absorber interface during the selenization process. Further, the incorporation of Ag improved the performance of kesterite devices up to 7.1% for 5% Ag/(Cu+Ag) composition. However, for Ag contents beyond this level we observed impairing of the device efficiencies with higher Ag content.