Poly(catecholamine) coated CsPbBr3 perovskite microlasers: lasing in water and biofunctionalization

Lead halide perovskites (LHP) microcrystals are promising materials for various optoelectronic applications. Surface coating on particles is a common strategy to improve their functionality and environmental stability, but LHP is not amenable to most coating chemistries because of its intrinsic weakness against polar solvents. Here, we describe a novel method of synthesizing LHP microcrystals in a super-saturated polar solvent using sonochemistry and applying various functional coatings on individual microcrystals in situ. We synthesize cesium lead bromine perovskite (CsPbBr₃) microparticles capped with organic poly-norepinephrine (pNE) layers. The catechol group of pNE coordinates to bromine-deficient lead atoms, forming a defect-passivating and diffusion-blocking shell. The pNE layer enhances the stability of CsPbBr₃ in water by 2,000-folds, enabling bright luminescence and lasing from single microcrystals in water. Furthermore, the pNE shell permits biofunctionalization with proteins, small molecules, and lipid bilayers. Luminescence from CsPbBr₃ microcrystals is sustained in water over 1 hour and observed in live cells. The functionalization method may enable new applications of LHP particles in water-rich environments.