Size-selected and surface-passivated CsPbBr perovskite nanocrystals for self-enhanced electrochemiluminescence in aqueous media.

In this work, CsPbBr3 perovskite nanocrystals (NCs) synthesized via a ligand-assisted reprecipitation method (LCPB) were discovered to emit self-enhanced electrochemiluminescence (ECL) with the surface oleylamine as both a coreactant and a stabilizer. Solvent regulation and tri-n-octylphosphine post-treatment were manipulated for size-selected and surface-passivated LCPBs, which showed remarkable aqueous ECL performance with respect to efficiency and stability. Furthermore, thanks to the self-enhancement mode with a shorter charge transfer pathway and less energy loss, the ECL efficiency obtained for these as-synthesized LCPBs in aqueous solution without any additional coreactant was up to 57.08% using the Ru(bpy)32+-tripropylamine system as the standard. As a proof-of-concept, the products were successfully employed for the bioanalyses of hydrogen peroxide, ascorbic acid, and cancer cells based on inhibition, coreaction, and impedance detection principles, respectively. More importantly, the basic properties of LCPBs in aqueous media including surface chemistry, charge transfer process, and ECL mechanism were studied systematically. Such efforts are aimed at perfecting the fundamental research of all-inorganic perovskite NCs and opening an avenue for the design of highly crystalline and luminescent perovskites as advanced ECL emitters for applications in the ECL domain.