Effects on Moisture on CdTe Cell I-V Characteristics

This paper focuses on the effect of water on CdTe solar cells provided by Dr. Sampath´s group at Colorado State University, that have not been encapsulated.. Bare cells were subjected to damp heat conditions defined by 60 degC and 90% Relative Humidity (RH). Current voltage characteristics were acquired periodically over a thousand hour period. Bare, unencapsulated CdTe cells appear to exhibit changes in current collection and current loss mechanisms as well as degradation of contact interfaces as a result of damp heat. XPS analyses have been conducted in an effort to identify effects of moisture ingress. The XPS studies indicate that one possible effect of moisture on CdTe cells is to convert the CdO at grain boundaries to Cd(OH)₂. Since it is generally assumed that CdO acts as an effective electron reflector on CdTe grain boundaries, formation of the hydroxide could explain the degradation of current voltage characteristics of CdTe cells subjected to damp heat