Electrodeposition of chalcopyrite films from ionic liquid electrolytes

An air and water stable room-temperature ionic liquid based on choline chloride/urea eutectic mixture has been investigated as a system for the electrodeposition of CuInSe2 (CIS) and Cu(In,Ga)Se2 (CIGS) films for photovoltaic applications. Deposition potentials and bath compositions were optimized to obtain Cu–In, Cu–In–Se and Cu–In–Ga–Se precursor films, which were selenized in a tube furnace at 500 °C for 30 min to form CIS and CI(G)S films. Photo-electrochemical measurements on these selenized films showed p-type photoconductivity with band gaps of 1.0 eV and 1.09 eV, respectively, for CIS and CIGS. The films were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), photocurrent spectroscopy and electrolyte electro-reflectance spectroscopy (EER).