Perovskite-Chalcogenide Epitaxial Heterostructures: Possibility of Multiple Axial Orientations of CsPbBr₃ Nanocrystals on PbBi₂S₄ Nanorods

The chemistry of designing epitaxial perovskite-chalcogenide nanocrystal heterostructures still could not be established yet in spite of significant successes in understanding both perovskite and chalcogenide nanostructures formation. Interfacing the ionic–covalent bonding at the junction of both remains the major obstacle for establishing the seamless formation of such nanostructures. Keeping the compatibility of Bi(III) ions with Pb(II) in different lead halide perovskite nanocrystals, herein, multiple possibilities of interface junctions of ionic CsPbBr3 and covalent PbBi2S4 sulfide nanocrystals are reported. Creating the common Pb(II) sublattice structures in this system indeed helped in designing such a wide possibility of nanocrystal heterostructures, and this supported the connection of CsPbBr3 polyhedral nanocrystals with PbBi2S4 nanorods in different orientations. While epitaxial heterostructure formations are typically observed with the interface of specific facets of two nanoscale materials, here, for perovskites, this provides multiple options of different facets combination. This concept remained important for fundamental understanding in creating junctions of ionic–covalent crystals and also helped in establishing the method for designing halide perovskite-chalcogenide nanocrystal heterostructures. Such interface junctions, where defects are mostly generated due to halide deficiency, quench the optical emission, but, in contrary, enhance the catalytic activities.