Halogen‐Hot‐Injection Synthesis of Mn‐Doped CsPb(Cl/Br)₃ Nanocrystals with Blue/Orange Dual‐Color Luminescence and High Photoluminescence Quantum Yield

Abstract Recently, Mn²⁺‐doped CsPb(Cl/Br)₃ perovskite nanocrystals (NCs), showing the advantages of dual‐color emissions via exciton‐to‐dopant energy transfer and reduced usage of toxic Pb²⁺ heavy metal ions by nontoxic Mn²⁺ substitution, are widely explored. However, photoluminescence quantum yields (PLQYs) for Mn²⁺‐doped CsPb(Cl/Br)₃ NCs still need to be further improved. Here, a halogen‐hot‐injection strategy is developed to prepare Mn:CsPb(Cl_0.6Br_0.4)₃ NCs with the maximal PLQY of 65%. With this method, intense blue narrowband emission from excitonic recombination and orange broadband emission from Mn^{2+ 4}T₁ → ⁶A₁ transition can be simultaneously achieved. The competitive luminescence between perovskite NCs and Mn²⁺ dopants is systematically investigated by controlling the injected halogen types and ratios. As a proof‐of‐concept experiment, the present Mn²⁺‐doped CsPb(Cl/Br)₃ perovskite NCs with highly efficient dual‐color emissions are demonstrated to be applicable as color converter in UV‐excitable solid‐state lighting.