Effects of CdCl2 heat treatment on the morphological and chemical properties of CdTe/CdS thin films solar cells

► CdTe/CdS/ITO/glass solar cells annealed at 340-420 °C temperatures were studied with and without CdCl2 treatment using SEM and XPS. ► CdCl2 treated CdTe structures exhibited recrystallization and a progressive increase in grain sizes upon annealing. ► XPS spectra for S 2p, Cd 3d and Te 3d peaks were analyzed for the as-grown and for the annealed samples with and without CdCl2 treatment. ► The spectra show the TeO3 peaks are removed upon annealing the CdCl2 treated samples and enhanced upon annealing without CdCl2 treatment.