Abstract
Surface defect-induced photoluminescence blinking is ubiquitous in lead halide perovskite quantum dots (QDs). Despite efforts to passivate the defects on perovskite QDs by chemically engineering ligand binding moieties, blinking accompanied by photodegradation still poses barriers to studying and implementing quantum-confined perovskite QDs in quantum emitters. We posited that the intermolecular interaction between ligands can affect the QD surface passivation. In the solid state, steric repulsions among bulky ligand tails prevent adequate QD surface ligand coverage. Alternatively, attractive π-π stacking between low-steric phenethylammonium (PEA) ligands promotes the formation of a nearly epitaxial surface ligand layer. Here, we demonstrate that single CsPbBr3 QDs covered by these PEA ligands are nearly non-blinking, with single photon purity reaching 98%. Moreover, these QDs exhibited no spectral shifting and photodegradations, and they remained blinking-free after 12 hours of continuous operation. Free of interferences from blinking and photodegradation, we present size-dependent exciton radiative rates and emission line widths of single CsPbBr3 QDs ranging from strongly to weakly confined regimes.