Ligand‐Mediated Synthesis of Mixed‐Phase Mn²⁺‐Doped Cesium Lead Chloride Nanocrystals

Abstract Herein we report a study on the role of alkylamine ligand in tuning the crystal structure and the luminescence of Mn²⁺‐doped cesium lead chloride (Mn−CPC) nanocrystals. In a typical hot‐injection synthesis of Mn−CPC, oleic acid (OA) and oleylamine (OLA) are used as the capping ligands to mediate the size and surface structure of the nanocrystals. We found that by either increasing the concentration of OLA or substituting OLA with an amine with a shorter chain length (e. g. dodecylamine), the resulted Mn−CPC contains both CsPbCl₃ and Cs₄PbCl₆ phases. The mixed‐phase Mn−CPC exhibit two major photoluminescence emission bands originated from the CsPbCl₃ bandgap and the Mn d‐d transition, respectively. Besides, a near‐UV emission from Cs₄PbCl₆ near‐band‐gap exciton emission also appears and is highly sensitive to the excitation wavelength. The formation mechanism of mixed‐phase Mn−CPC nanocrystals is proposed.