Back contacts to CSSCdS/CdTe solar cells and stability of performances

High efficiency CdTe/CdS thin film solar cells with a good stability can be obtained if a low gap. high conductivity p-type semiconductor, such as Sb2 Te3, is used as a back contact for CdTe. However, even though Sb2Te3 is use d as a back contact, some cells can exhibit a low fill factor. This, at fir st sight, could suggest that the back contact is not the right one. Here we would like to show that a low fill factor could depend not only on the bac k contact but also on the front contact and on the amount of Na-diffusion f rom the soda lime glass substrate. (C) 2000 Elsevier Science S.A. All right s reserved.