CdS thin films for terrestrial solar cells

Four different polycrystalline thin-film CdS-based solar cells have been reported with conversion efficiencies in excess of 5%. These cells (Cu2S/CdS, CdTe/CdS, InP/CdS, and CuInSe2/CdS) are briefly reviewed here. It is noted that present economic projections require the fabrication of terrestrial solar cells with 10% conversion efficiency, a constructed array cost of $60/sq m, and at volumes of approximately 100 million sq m/yr. The paper describes some of the physical constraints on CdS thin films and the economic constraints on CdS thin film fabrication, imposed, respectively, by the 10% conversion efficiency requirement and the low-cost production scale-up requirement.