Preparation of CuInxGa1−xSe2 solar cells by electron beam evaporation of powdered evaporants

Cu(In,Ga)Se2 (CIGS) thin films were deposited by electron beam evaporation of ball-milled powders containing various amounts of gallium. The effects of the gallium concentration in the Cu(In,Ga)Se2 on the structure, surface morphology and optical properties of the films were investigated using X-ray diffraction, energy-dispersive X-ray analysis, atomic force microscopy and optical spectroscopy. All of the films, which were deposited at 450 °C, were polycrystalline and exhibited a chalcopyrite structure with a (112) preferred orientation. The optical constants of the films were calculated. The grain size, the roughness and the band gap increased with increasing amounts of gallium in the films. A glass/TCO/CdS/CIGS/Au solar cell with 12.87% efficiency was prepared directly from the powdered material.