Synergistic ligand-antisolvent modulation for selective CsPbBr3 perovskite synthesis and functional diversity

Green antisolvents and ligands synergistically direct perovskite phase evolution. • Spectroscopic analyses reveal solvent-dependent ligand dissociation mechanisms. • Distinct phases enable antibacterial and dynamic anti-counterfeiting applications. In this work, we propose a ligand–antisolvent synergistic regulation strategy to synthesize Cs–Pb–Br materials with dual antibacterial and encryption functions. An amphiphilic ligand derived from 5-bromovaleric acid (5-BVA) and oleamide (OAm) is employed with two green antisolvents (water and ethanol). The use of water as an antisolvent yields high-purity CsPbBr 3 quantum dots (QDs) with water stability exceeding 50 days. These QDs exhibit potent antibacterial activity through electrostatic interactions with bacterial cell membranes achieving up to 99.8% inhibition at a low concentration of 120 μg/ml. In contrast, ethanol as the antisolvent leads to a mixed CsPbBr 3 /CsPb 2 Br 5 phase. This mixed phase exhibits water-triggered fluorescence activation originating from CsPbBr 3 recrystallization alongside a thermal quenching effect that enables reversible on–off fluorescence switching upon cooling–heating cycles. This water-induced fluorescence activation effect combined with reversible thermal quenching properties enables multi-level encryption. Ultimately this ligand-antisolvent synergistic regulation strategy not only offers theoretical guidance for the rational and tailored design of multifunctional perovskites but also establishes a foundation for their practical applications in complex optoelectronic and biological environments.