Cu doping by copper or Cu2Te materials enhances p+ formation in CdTe near the back contact interface, allowing better
formation of ohmic contact. However, the Cu in CdTe junction is also considered as a principal component of CdTe cell degradation.
In this paper, Na-doped ZnTe layer was employed as a back contact material to improve the stability of CdTe solar cells. As a process
variable, post CdCl2 treatment of CdS/CdTe film was conducted before or after depositing ZnTe:Na on CdTe. The change of the
photovoltaic properties of CdTe cells were investigated with aging time. Low-temperature photoluminescence analysis was conducted
to describe the degradation mechanism. The result showed that the CdTe solar cells with better stability compare to Cu contact were
achieved using an optimized ZnTe:Na back contact.