Exciton-to-Dopant Energy Transfer in Mn-Doped Cesium Lead Halide Perovskite Nanocrystals

We report the one-pot synthesis of colloidal Mn-doped cesium lead halide (CsPbX₃) perovskite nanocrystals and efficient intraparticle energy transfer between the exciton and dopant ions resulting in intense sensitized Mn luminescence. Mn-doped CsPbCl₃ and CsPb(Cl/Br)₃ nanocrystals maintained the same lattice structure and crystallinity as their undoped counterparts with nearly identical lattice parameters at ∼0.2% doping concentrations and no signature of phase separation. The strong sensitized luminescence from d-d transition of Mn²⁺ ions upon band-edge excitation of the CsPbX₃ host is indicative of sufficiently strong exchange coupling between the charge carriers of the host and dopant d electrons mediating the energy transfer, essential for obtaining unique properties of magnetically doped quantum dots. Highly homogeneous spectral characteristics of Mn luminescence from an ensemble of Mn-doped CsPbX₃ nanocrystals and well-defined electron paramagnetic resonance spectra of Mn²⁺ in host CsPbX₃ nanocrystal lattices suggest relatively uniform doping sites, likely from substitutional doping at Pb²⁺. These observations indicate that CsPbX₃ nanocrystals, possessing many superior optical and electronic characteristics, can be utilized as a new platform for magnetically doped quantum dots expanding the range of optical, electronic, and magnetic functionality.