Limiting Halide\nExchange and Doping Mn(II) in Vertex-Oriented\nCube-Connected Patterned Lead Halide Perovskite Nanorods

Lead halide perovskite nanocrystals remained in the forefront\nof\ninorganic optical nanomaterials for a decade. The chemistry of their\nformation leading to bright and phase-stable nanocrystals is also\nlargely understood. However, this study mostly focuses on isotropic\nnanostructures and is limited to anisotropic shapes. Again, the study\nof shape anisotropy is more explored for orthorhombic CsPbBr<sub>3</sub> and limited for the high-bandgap cubic phase CsPbCl<sub>3</sub> nanocrystals.\nKeeping this in mind, herein, the halide exchange is carried out in\na specific cube-connected patterned vertex-oriented nanorod of CsPbBr<sub>3</sub> intending for complete conversion to CsPbCl<sub>3</sub>.\nThe host CsPbBr<sub>3</sub> nanorods are prepared here by B-site cation\nexchange in CsCdBr<sub>3</sub> following a Cs-sublattice platform,\nas no such traditional protocol has been developed for their direct\nsynthesis. In addition, direct synthesis of CdCdCl<sub>3</sub> nanorods\nhaving an appropriate Cs-sublattice framework leading to anisotropic\nCsPbCl<sub>3</sub> nanorods is also not achieved in a similar pathway.\nHence, cubic CsPbCl<sub>3</sub> nanorods are targeted from CsPbBr<sub>3</sub> through anion exchange. However, it is observed that such\nanion exchange has a limiting stage beyond which the anisotropic rod\nis dismantled into isotropic cube structures. The chemistry of control\nof such limiting parameters is investigated, and the phase–shape\nrelationship during the anion exchange is established. The key observation\nhere for such a unique shape of CsPbBr<sub>3</sub> is related to their\northorhombic phase, which lost its sublattice structure when the phase\nslowly converted to a pure cubic phase. However, with optimum Cl insertion,\nthe mixed halide perovskite nanorods are retained, and these are also\nfurther doped with Mn(II) for obtaining anisotropic doped nanorods,\nand their changes in optical features are reported. Hence, the shape–phase\nrelationship in anisotropic halide perovskite nanorods matters and\ncontrols the limit of halide exchange leading to the mixed halide\nperovskite anisotropic nanorods.