Complexing Agent-Dependent Properties of Chemically Deposited Tin Antimony Sulphide Thin Films for Use in Sustainable Energy Devices

Complexing agents are important in the control of chemical kinetics. Thin films of tin antimony sulphide (Sn₂Sb₂S₅) were deposited on glass substrates and the effect of different complexing agents [tri-sodium citrate (Na₃C₆H₅O₇) and tartaric acid (C₄H₆O₆)] on their properties were investigated. X-ray diffractometry studies indicate that the films crystallized in an orthorhombic structure. Films grown with Na₃C₆H₅O₇ exhibited increased texturing and higher crystallite size (16.6–22.1 nm), while that of C₄H₆O₆ was between 16.80 and 20.0 nm. Energy dispersive spectroscopy studies reveal that the antimony/sulfur ratio increased with an increase in the tin content in the former and decreased with an increase in the tin content in the latter. X-ray photoelectron spectroscopy studies confirmed the formation of Sn₂Sb₂S₅ films. Scanning electron microscopy analysis shows morphological evolution from seed-like to block-like structures in Na₃C₆H₅O₇and a seed-like structure in the C₄H₆O₆ environments. Optical spectroscopy results indicated that the films possess optical absorption coefficient (α) > 10⁴ cm^-1and a direct energy band gap that exhibited the classic Burstein-Moss shift. The energy band gap and the processing parameters fit into a quadratic model with high values of R². The electrical properties from Hall effect studies give typical semiconductor properties of Sn₂Sb₂S₅ in a range suitable for use in sustainable energy devices.