Synthesis of CsPbI3 Rhombic Dodecahedra Using Facet-Selective Bidentate Ammonium Ligands.

CsPbI3 nanocrystals exhibit bright, tunable photoluminescence and are attractive for use in a variety of optoelectronic devices. Existing colloidal syntheses of CsPbI3 predominantly produce nanocubes or other hexahedral shapes because of the stability of the nanocube facets in the perovskite structure. In this work, we utilize a bidentate ammonium ligand with a tunable linker between the two head groups in order to preferentially nucleate and stabilize rhombic dodecahedral nanocrystals. These particles show enhanced environmental stability compared to CsPbI3 nanocrystals capped with monodentate ammonium ligands and self-assemble into ordered, hexagonally packed monolayers. This work represents a new entry into the limited shape catalog of CsPbI3 and expands the design principles for facet-selective ligands in lead-halide perovskite nanocrystals.