Intragranular defects in As-deposited and cadmium chloride-treated polycrystalline cadmium telluride solar cells

Atomic-scale defects limit the open circuit Voltage, and the conversion efficiency of thin film polycrystalline cadmium telluride solar cells. Using state of the art aberration-corrected high resolution transmission electron microscopy, the type, density and atomic structure of intragranular defects present in cadmium chloride treated and untreated CdTe has been established. The cadmium chloride activation process dramatically reduces defect density but faults do remain. Characterizing the defects in both materials is an essential first step to determining their potential electrical effects, and to understanding how the cadmium chloride treatment reduces their density. Improving our knowledge of the mechanisms involved can lead to further process improvements.