The activation of thin film CdTe solar cells using alternative chlorine containing compounds

Abstract The re-crystallisation of thin film cadmium telluride (CdTe) using cadmium chloride (CdCl 2 ) is a vital process for obtaining high efficiency photovoltaic devices. However, the precise micro-structural mechanisms involved are not well understood. In this study, we have used alternative chlorine-containing compounds to determine if these can also assist the re-crystallisation of the CdTe layer and to understand the separate roles of cadmium and chlorine during the activation. The compounds used were: tellurium tetrachloride (TeCl 4 ), cadmium acetate (Cd(CH 3 CO 2 ) 2 ), hydrochloric acid (HCl) and zinc chloride (ZnCl 2 ). TeCl 4 was used to assess the role of Cl and the formation of a Te-rich outer layer which may assist the formation of the back contact. (Cd(CH 3 CO 2 ) 2 ) and HCl were used to distinguish between the roles of cadmium and chlorine in the process. Finally, ZnCl 2 was employed as an alternative to CdCl 2 . We report on the efficacy of using these alternative Cl-containing compounds to remove the high density of planar defects present in untreated CdTe.