Earth abundant and nontoxic absorber material for low cost, thin film solar cells

The fundamental development of Cu₂ZnSnS₄ (CZTS) thin films by non-vacuum, liquid-based techniques have been investigated. CZTS is a quaternary semiconductor material consisting of earth abundant, low-toxicity materials. CZTS is a promising absorber layer material for thin film solar cells due to its optimal optical band gap of ~1.5 eV and a large optical absorption coefficient of over 10⁴ cm^-1. CZTS polycrystalline thin films were prepared by a non-vacuum liquid-based coating method. Optical, structural and electronic characterization and analysis of the thin films were performed using the Hitachi S-4800 scanning electron microscope (SEM) and the Bruker D8 Discover X-ray diffractometer (XRD), the Thermo Scientific DXR SmartRaman spectrometer, and the Cary 5000 UV-Vis spectrophotometer. Results were used to determine the CZTS stoichiometry, crystal structure, orientation and crystallite size, and energy band gap (Eg). Results show the formation of single phase stoichiometric kesterite CZTS.