Colloidal synthesis and phase transformation of all-inorganic bismuth halide perovskite nanoplates

Lead-free bismuth-based halide perovskites and their analogues have attracted research interest for their high stability and optoelectronic properties. However, the morphology-controlled synthesis of bismuth-based perovskite nanocrystals has been rarely demonstrated. Herein, we report the colloidal synthesis of zero-dimensional (0D) Cs3BiCl6 nanosheets (NSs), Cs3Bi2Cl9 NSs/nanoplates (NPs) and Cs4MnBi2Cl12 NPs through a hot-injection method. We demonstrate that the Cs3BiCl6 NSs, as an initial product of Cs3Bi2Cl9 and Cs4MnBi2Cl12 NPs, can transform into Cs3Bi2Cl9 NSs or Cs4MnBi2Cl12 NPs via Cl-induced metal ion insertion reactions under the templating effect of Cs3BiCl6. This growth mechanism is also applicable for the synthesis of Cs4CdBi2Cl12 nanoplates. Furthermore, the alloying of Cd2+ into Cs4MnBi2Cl12 lattice could weaken the strong coupling effect between Mn and Mn, which leads to a prolonged photoluminescence lifetime and an enhanced photoluminescence quantum yield (PLQY). As a proof of concept, the alloyed Cs4MnxCd1−xBi2Cl12 NPs are used as a scintillator, which show a lowest detection limit of 134.5 nGy/s. The X-ray imaging results display a high spatial resolution of over 20 line pairs per millimeter (lp/mm). These results provide new insights in the synthesis of anisotropic bismuth-based perovskite nanocrystals and their applications in radiation detection.