Fast Room-Temperature Cation Exchange Synthesis of Mn-Doped CsPbCl₃ Nanocrystals Driven by Dynamic Halogen Exchange

Currently, it is of great challenge to achieve cation exchange in CsPbX₃ (X = Cl, Br, I) perovskite nanocrystals (NCs) on account of rigid Pb²⁺ octahedral coordination protected by six halogen anions (PbX₆^4-). Herein, we demonstrate that dynamic halogen exchange can effectively open up PbX₆^4- octahedrons and enable fast Mn-to-Pb cation exchange at room temperature in a few seconds. Importantly, Cl concentration rather than Mn one is demonstrated to be a dominant factor for cation exchange, where different Mn²⁺/Cl^- salts can be adopted as Mn/Cl sources and Cl-to-Cl or Cl-to-Br anion exchange is the necessary prerequisite. Such a facile synthesizing method can lead to the feasibility of tuning emissive colors for the Mn-doped CsPb(Cl/Br)₃ NCs by controlling both cation and anion exchanges and open a new way to replace Pb²⁺ in CsPbX₃ NCs by other nontoxic metal elements.