DOPANT AND IMPURITY EFFECTS IN ELECTRODEPOSITED CDS CDTE THIN-FILMS FOR PHOTOVOLTAIC APPLICATIONS/

The effect of deliberately added Cl-, Cu2+ and Ag+ on the performance of electrodeposited thin-film CdS/CdTe photovoltaic devices has been s tudied. It has been found that the incorporation of Cl- from the depos ition electrolytes into both CdS and CdTe films is essential for the p roduction of high-efficiency devices. The incorporation of Cu2+ into C dTe was found to result in a loss in performance for concentrations in the electrolyte >30 ppb, corresponding to a concentration of ca. 10(2 0) cm(-3) Cu in the film. Below 30 ppb, there is some evidence that Cu 2+ may enhance the performance of the device. The incorporation of Ag into CdTe was found to be deleterious at concentrations in the electro lyte as low as the detection limit (5 ppb). By controlling these speci es within the determined limits, it was possible to produce high-effic iency devices over a period of 4-5 months (>100 depositions) from a si ngle electrolyte.