Copper precursor-driven variations in structural, optical and electrical properties of SILAR-deposited CTS thin films

Abstract This pioneering study elucidates, for the first time, the profound impact of copper precursors (copper acetate, copper sulfate, and copper chloride) on the structural, optical, and electrical properties of Copper Tin Sulfide (CTS) thin films synthesized via successive ionic layer adsorption and reaction (SILAR) deposition. Comprehensive characterization using x-ray diffraction (XRD), cross-sectional scanning electron microscopy (SEM), atomic force microscopy (AFM), Fourier transform infrared (FTIR) spectroscopy, and electrical and optical measurements revealed significant variations in crystallite size (74.9–84.4 nm), film thickness (1.235–4.75 μm), and conductance (3.2–4.7 × 10 −11 S). Notably, copper acetate-derived films exhibited enhanced surface morphology, whereas copper chloride-derived films demonstrated exceptional optoelectronic properties, including a maximum bandgap energy of 3.7 eV, highest conductance of 4.7 × 10 −11 S, and unique optical characteristics, such as zero transmittance below 300 nm, low absorption above 300 nm, and a balanced absorption profile, rendering them suitable for photovoltaic cells, optical sensors, and UV-blocking applications. These results demonstrate the critical influence of copper precursors on CTS thin film properties, paving the way for tailored material design and enhanced device performance, with significant implications for the development of efficient and sustainable photovoltaic technologies.