Effect of annealing temperature and CdCl2 treatment on the photo-conversion efficiency of CdTe/Zn0.1Cd0.9S thin film solar cells

Abstract

We report the effects of annealing in conjunction with CdCl2 treatment on the photovoltaic properties of CdTe/Zn0.1Cd0.9S thin film solar cells. CdTe layer is subjected to dry CdCl2 treatment by thermal evaporation method and subsequently, heat treated in air using a tube furnace from 400 to 500°C. AFM and XRD results show improved grain size and crystallographic properties of the CdTe film with dry CdCl2 treatment. This recrystallization and grain growth of the CdTe layer upon CdCl2 treatment translates into improved photo-conversion efficiencies of CdTe/Zn0.1Cd0.9S cell. The results of dry CdCl2 treatment were compared with conventional wet CdCl2 treatment. Photo-conversion efficiency of 5.2% is achieved for dry CdCl2-treated cells in comparison with 2.4% of wet-treated cell at heat treatment temperature of 425°C.