Spray‐Pyrolyzed Kesterite Based CZTS (Cu ₂ ZnSnS ₄ ) Thin Films: Structural, Optical, and Compositional Analysis for Photovoltaic Applications

The Cu 2 ZnSnS 4 (CZTS) absorber material has been widely investigated in recent years due to several beneficial qualities such as earth‐abundant, nontoxic, tunable band gap, and large absorption coefficient. The CZTS absorber layers were fabricated on a soda lime glass (SLG) substrate by nonvacuum spray pyrolysis technique at various deposition times. This work systematically correlates deposition time, film thickness, and the properties of CZTS thin films using a home‐built, low‐cost spray pyrolysis system. The samples were postannealed for 40 min in N 2 environment at 450°C. The structural, optical, compositional, and morphological properties of CZTS samples are investigated. The XRD and Raman analyses confirm the formation of the kesterite tetragonal phase. The crystallite size, D, increases from 58 to ∼70 nm with increasing deposition time, while dislocation density, δ , decreases from (2.9 to 2.1) × 10 14 lines/m 2 . The SEM analysis shows that the sample fabricated at a longer deposition time exhibits enhanced crystallinity. The energy‐dispersive X‐ray spectroscopy (EDS) study confirms the formation of CZTS in a Zn‐rich condition. The optical characteristics reveal that the CZTS samples have an absorption coefficient in the order of ∼10 4 cm −1 , refractive index, n ranges 2.958–2.974 and a band gap energy, E g , varies from 1.38 to 1.41 eV. These excellent features of the CZTS films suggest that they have enormous potential in using them as an earth‐abundant and eco‐friendly absorber layer in next‐generation solar cell applications.