Cadmium telluride is a most promising thin film photovoltaic material as shown by the higher than 10% efficient CdS/CdTe heterojunction solar cells. In this work, thin film CdS/CdTe solar cells have been prepared using CdS films grown from an aqueous solution and p-CdTe films deposited by metalorganic chemical vapor deposition (MOCVD) and close-spaced sublimation (CSS). The solution-grown CdS films, with high photoconductivity ratios and good optical transmission, are well-suited for optoelectronic devices. The CdTe films deposited by CSS show considerably better microstructure than those by MOCVD because of the higher substrate temperature used in the CSS process. The properties of CdS/CdTe heterojunctions have been studied. Solar cells of 1 cm2 with an AM 1.5 efficiency of 14.6%, verified at the National Renewable Energy Laboratory, have been CdTe films