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CuInS 2 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 CuIn 1− x Ce x S 2 samples crystallize with chalcopyrite structure at 250 °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 CuIn 1− x Ce x S 2 films decrease from 1.38 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 CuInS 2 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. [ABSTRACT FROM AUTHOR]

In present paper, a promising intermediate band (IB) material of CuGaS 2 thin films incorporating with titanium (Ti) have been successfully fabricated by a facile non-vacuum method. Binary sulfides used as raw material are firstly tried to fabricate Ti-substituted CuGaS 2 thin films via ball milling and spin-coating technique. The experimental measurements showed that the obtained Cu 2 Ga 1− x Ti x S 2 thin films are composed of chalcopyrite structure with well crystallinity. A slightly left shift of (1 1 2) diffraction peaks indicated the successful doping of Ti element. The Hall Effect measurement exhibited the carrier concentration raised obviously from 1.538 × 10 12 ( x = 0) to 1.134 × 10 13 cm −3 ( x = 0.06) with increasing of Ti doping concentration. More important, the UV–vis–NIR spectra exhibited a strong optical absorption in Ti-substituted CuGaS 2 films, which indicated the IBs were roughly formed in the films. [ABSTRACT FROM AUTHOR]