Lead-free perovskite KCsSnI1.7Cl1.3 material exhibiting superior photocatalytic antimicrobial activity.

The development of environmentally friendly and highly efficient materials is critical for next-generation antibacterial and optoelectronic applications. In this study, we present the successful synthesis of a novel lead-free perovskite, KCsSnI1.7Cl1.3, via a rapid and scalable chemical bath deposition method at 150 °C for just 5 min. The resulting film features well-defined orthorhombic, pyramid-like crystals with uniform grain sizes (800-1000 nm) and a compact, pinhole-free morphology. Remarkably, the material exhibits strong optical absorption up to 800 nm, positioning it as a promising candidate for hot electron generation and light-driven applications. KCsSnI1.7Cl1.3 also demonstrated outstanding antibacterial performance, showing broad-spectrum activity against multiple bacterial strains. The highest inhibition was recorded against Staphylococcus aureus, with inhibition zones increasing from 17 mm in the dark to 35 mm under UV illumination-highlighting its efficient photocatalytic response. The antibacterial effect followed the order: S. aureus > B. subtilis > E. coli > Salmonella sp., and was significantly enhanced with increasing concentrations (100-400 ppm). No inhibition was observed in control wells, confirming the selective activity of the material. With its lead-free composition, strong light-harvesting ability, and exceptional antibacterial properties, KCsSnI1.7Cl1.3 emerges as a highly promising material for future applications in antibacterial coatings, water purification systems, and advanced optoelectronic devices. Its green synthesis, scalability, and multifunctionality offer a sustainable pathway toward real-world deployment in environmental and biomedical fields.