Interest has been growing in defects of halide perovskites in view of their intimate connection with key material optoelectronic properties. In perovskite quantum dots (PQDs), the influence of defects is even more apparent than in their bulk counterparts. By combining experiment and theory, we report herein a halide-vacancy-driven, ligand-directed self-assembly process of CsPbBr3 PQDs. With the assistance of oleic acid and didodecyldimethylammonium sulfide, surface-Br-vacancy-rich CsPbBr3 PQDs self-assemble into nanowires (NWs) that are 20-60 nm in width and several millimeters in length. The NWs exhibit a sharp photoluminescence profile (≈18 nm full-width at-half-maximum) that peaks at 525 nm. Our findings provide insight into the defect-correlated dynamics of PQDs and defect-assisted fabrication of perovskite materials and devices.

We report a facile processing strategy that utilizes perovskite quantum dots (QDs) to distribute elemental dopants uniformly across a MAPbI3 film and anchor ligands to the film's surface—reducing the film's trap-state density and rendering its surface hydrophobic. QD-treated MAPbI3 films yield solar cells with 21.5% power conversion efficiency (PCE) (versus 18.3% for non-QD-treated) and maintain 80% of their initial PCE under 1-sun continuous illumination for 500 h with improved thermal stability.

The large specific surface area of perovskite nanocrystals (NCs) increases the likelihood of surface defects compared to that of bulk single crystals and polycrystalline thin films. It is thus crucial to comprehend and control their defect population in order to exploit the potential of perovskite NCs. This Perspective describes and classifies recent advances in understanding defect chemistry and avenues toward defect density reduction in perovskite NCs, and it does so in the context of the promise perceived in light-emitting devices. Several pathways for decreasing the defect density are explored, including advanced NC syntheses, new surface-capping strategies, doping with metal ions and rare earths, engineering elemental compensation, and the translation of core-shell heterostructures into the perovskite materials family. We close with challenges that remain in perovskite NC defect research.