ZnTe Back Buffer Layer to Enhance the Efficiency of CdS/CdTe Solar Cells

The high electron affinity (4.4eV) of CdTe presents a major technological challenge for forming a good back contact to CdTe, limiting the power conversion efficiency of CdTe solar cells. Commonly used metals do not possess an adequately deep work function to create an ohmic contact with CdTe. Instead, approaches such as doping the back surface of CdTe or incorporating a buffer layer between CdTe and the back-metal contact are used to lower the back-barrier height. Here, we investigate the impact of sputtered ZnTe back buffer layer on the performance of CdS:O/CdTe solar cells. We demonstrated CdTe solar cells with an efficiency of around 15% with a 35 nm ZnTe buffer layer.