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.