CdTe Thin Film PV: How Has the Technology Evolved and What Challenges Lie Ahead

Abstract

This paper reviews the evolution of CdTe photovoltaics since the first CdTe/CdS solar cells were reported in the early 70’s with modest efficiencies (~5%). Today’s commercial CdTe thin film modules have areas of 2.5 m2 and efficiencies of 17–18%; small area cells are over 22% efficiency. In reaching this performance, the typical/original CdTe/CdS hetero-structure evolved into a CdTe/Cd(Se)Te/MZO (Magnesium Zing Oxide). The technology continues to rely on a post-deposition heat-treatment (in the presence of CdCl2), and the use of Cu (p-type dopant) for the formation of the back contact. Advancing performance to higher levels will depend on the CdTe community’s ability to address key device and material properties (net p-type doping) that limit the cell’s open circuit voltage to 0.9 Volts.