Controlling the surface ligand chemistry of lead halide perovskite nanocrystals remains one of the most important parameters for stabilizing different facets and maintaining high photoluminescence quantum yields (PLQYs). Successive washings or the use of antisolvents not only quenches the emission but also changes the crystal phase of these nanocrystals. However, studies to date have mostly focused on oleylammonium ion capped six-faceted hexahedron-shaped halide perovskite nanocrystals. In contrast, herein the impact of other ligands stabilizing other than facets of cube shaped nanocrystals is studied, and the physical insights of interface binding for stabilizing new facets and retaining near-unity PLQYs even with successive washings are discussed. Apart from nanocubes, 12-faceted dodecahedrons and 26-faceted rhombicuboctahedrons of CsPbBr3 having tertiary ammonium ion ligands are explored for successive dilution, precipitation, and redispersion studies with further bromide additions to investigate the change in the PLQY, crystal phase, and optical stability. After comparison, it is established that dodecahedron nanocrystals even in a larger size regime showed robust stability and retained near-unity PLQYs with four successive stages of dilutions and precipitations and hardly showed any differences in low-temperature brightness or any enhancement with extra bromide addition. These results suggest that ligands and facets remain the key features in bringing optical stability to lead halide perovskite nanocrystals.

The design of cube-connected nanorods is accomplished by connecting seed nanocrystals of a defined shape in a particular orientation or by etching selective facets of preformed nanorods. In lead halide perovskite nanostructures, which retain mostly a hexahedron cube shape, such patterned nanorods can be designed with the anisotropic direction along the edge, vertex, or facet of seed cubes. Combining the Cs-sublattice platform for transforming metal halides to halide perovskites with facet-specific ligand binding chemistry, herein, vertex-oriented patterning of nanocubes in one-dimensional (1D) rod structures is reported. By tuning the length of host metal halides, their lengths could also be tuned from 100 nm to nearly 1000 nm. The symmetry of the hexagonal phase of host halide CsCdBr 3 and product orthorhombic CsPbBr 3 helped in maintaining the vertex [201] as the anisotropic direction. Neutral exciton recombination rates, extracted from photoluminescence blinking traces, showed a systematic increase from isolated cubes to cube-connected nanorods of various lengths. Efficient coupling of wave functions in vertex-oriented cube assemblies permits exciton delocalization. Our findings on carrier delocalization in cube-connected nanorods along their vertex direction having minimum interfacial contacts provide valuable insights into the fundamental chemistry of assembling anisotropic halide perovskite nanostructures as conducting wires.