Effect of sulfurization time on properties of Cu2ZnSnS4 thin films obtained by sol–gel deposited precursors

Abstract

As a promising and alternative solar absorber material, the Cu2ZnSnS4 (CZTS) has gained a broad interest over recent years due to its excellent material properties such as suitable and tunable band gap energy of 1.4–1.6 eV and absorption coefficient over 104 cm−1 (Jimbo et al. in Thin Solid Films 515(15):5997–5999, 2007; Katagiri et al. in Sol Energy Mater Sol Cells 65(1–4):141–148, 2001). In addition, all components of the CZTS are naturally abundant and non toxic. Nowadays solution based-approaches are being developed for the deposition of CZTS to overcome the problem of expensive and complicated vacuum-based methods. In this work, we report the study of properties of the novel wurtzite CZTS material prepared by sol–gel sulfurization as a function of annealing time. The effect of annealing time on structural and optical properties of the films was investigated. The X-ray diffraction analysis confirmed the formation of the wurtzite CZTS phase. The crystallinity of the films increases with an increasing sulfurization time. The values of the optical absorption coefficients for the film were found to be 104 cm−1. The optical band-gap values were estimated to be between 1.58 and 1.79 eV depending on the sulfurization time.