Synthesis and characterization of Ce-incorporated CuInS2 chalcopyrites

摘要

CuInS2 thin films incorporating with cerium have been successfully fabricated by a powder metallurgy method. X-ray diffraction and scanning electron microscope measurements showed that the as-prepared CuIn1-xCexS2 samples crystallize with chalcopyrite structure at 250 degrees C and the crystallinity and film compactness could be improved as annealing temperature rises. In the ultraviolet-visible-near infrared spectrum, two additional light absorption peaks were observed at 1690 nm and 1930 nm. The optical bandgaps of CuIn1-xCexS2 films decrease from 138 eV to 1.34 eV with increasing cerium content. These observed optical behaviors could suggest that an intermediate band forms in the forbidden band of CuInS2 semiconductor due to cerium incorporation. The position of intermediate band locates at 0.64 eV below conduction-band bottom. This kind of rare-earth doped materials enhances long-wavelength absorption, which could be helpful for high-efficiency solar cells. (C) 2015 Elsevier B.V. All rights reserved.