An Improved Strategy for High-Quality Cesium Bismuth Bromine Perovskite Quantum Dots with Remarkable Electrochemiluminescence Activities

Low-toxic trivalent bismuth, with an isoelectronic structure (6s²6p⁰) and a similar ionic radius to divalent lead, represents a promising candidate for constructing lead-free perovskites. Herein, cesium bismuth halide perovskite quantum dots (Cs₃Bi₂Br₉ QDs) were synthesized via a comprehensively improved ligand-assisted reprecipitation method with the addition of γ-butyrolactone, trace distilled water, and tetrabutylammonium bromide, as well as the aid of ultrasonic technology. The as-prepared QDs displayed remarkable monodispersity, outstanding stability, and highly passivated surfaces with a near-single-component PL decay, thus affording superb optical properties with a photoluminescence quantum yield up to 37%, outperforming all the reported bismuth-based perovskites. Furthermore, Cs₃Bi₂Br₉ QDs were first attempted for electrochemiluminescence (ECL) and exhibited a stable and efficient ECL response following either an annihilation or a coreaction ECL mechanism. Not only were the optical properties and stability of Cs₃Bi₂Br₉ QDs greatly improved in this work, but their electrochemical behaviors and ECL natures were also investigated systematically for the first time, demonstrating the significant potential to extend this environmentally friendly bismuth-based perovskite into the ECL domain.