Microstructural and optical properties of CuIn3Te5 thin films for solar cells

CuIn3Te5 thin films were deposited onto soda-lime glass (SLG) substrates by using a molecular beam epitaxy (MBE) system. Microstructural properties were examined by means of scanning electron microscopy (SEM), X-ray diffraction (XRD) and Raman scattering. The substrate temperature (Tsub) dependence of film properties was investigated in the range of 100–400 °C. Large-grain CuIn3Te5 thin films with a defect chalcopyrite structure were dominantly grown at 200–400 °C. Preferred (1 1 2) orientation was observed even at the low substrate temperature of 200 °C. The optical bandgaps of these films were determined to be 1.01–1.05 eV from transmission and reflection measurements. The best solar cell fabricated using CuIn3Te5 thin films grown at 200 °C yielded an efficiency of 4.64% with Voc=318 mV, Jsc=29.0 mA/cm2 and FF=0.504.