Abstract
Cu2ZnSnS4 (CZTS) thin films have been successfully deposited on glass substrate using ultrasonic spray pyrolysis (USP) technique with different copper concentrations ranging from 0.005 to 0.020 M. The effect of copper concentration on the structural, morphological and optoelectrical properties of deposited films has been investigated. Choice of USP method and copper concentration was found to have a crucial role in stoichiometry, band gap and conductivity of sprayed CZTS thin films. X-ray diffraction indicated that all deposited films have CZTS Kesterite structure with a preferential orientation along (112) plane confirmed by Raman scattering measurements. Copper sulfide (CuS) is present as a secondary phase in all films. The presence of this secondary phase causes films optical band broadening. Good film with nearly stoichiometric CZTS film and desirable band gap of 1.51 eV was obtained at copper concentration of 0.015 M. This result indicates that this film is suitable for being applied as an absorber layer in photovoltaic solar cells.