Nanocrystal Heterostructures Based On Halide Perovskites and Lead–Bismuth Chalcogenides

In an effort to extend the library of colloidal heterostructures based on halide perovskites, we report here the synthesis of CsPbBr₃–Pb_xBi_yS_z nanocrystal dimers. Their synthesis is adapted from an earlier established cluster-based approach for perovskite–chalcohalide CsPbBr₃–Pb₄S₃Br₂ heterostructures. However, the simple introduction of bismuth alters the composition of the non-perovskite domain from what would have been a Pb₄S₃Br₂ chalcohalide domain (in the absence of Bi) to a mixed lead–bismuth chalcogenide domain, that is, not incorporating halide ions. Our investigation of the growth dynamics of these CsPbBr₃–Pb_xBi_yS_z heterostructures, performed by in situ optical spectroscopy and ex situ electron microscopy, suggests the existence of an intermediate state where the early formed perovskite domain is partially consumed to feed the growth of the chalcogenide domain. Remarkably, their resulting complex shape can be resolved by advanced electron microscopy and even reconstructed from a tomographic series of images. It is found that these unique heterostructures comprise two distinct anisotropic domains: an elongated lead–bismuth chalcogenide rod attached to a prismatic perovskite core.