Abstract

Cu₂ZnSnS₄ (CZTS) absorber layers have been deposited via a spray pyrolysis technique without sulfurization process. Spray precursor solutions were prepared with different zinc to tin ratios, and the effects on film growth, structural, compositional, morphological, optical and electrical properties were investigated. The formation of kesterite structure with (112), (220) and (116) planes in the films was confirmed using X-ray diffraction measurements. AFM analysis revealed a smooth, compact and crack-free morphology. The estimated absorption coefficient was close to 10⁵ cm⁻¹ in the visible region for all CZTS films, and the values obtained for the optical band gap energy of the films were between 1.30 and 1.46 eV. The electrical studies showed that all these samples had a p-type conductivity, and the free hole density and mobility reduced with increasing the Zn/Sn molar ratio compatible with the shifts in the transmittance and reflectance spectra.