  Nanocrystals based on metal-halide perovskites offer a promising material
platform for highly efficient lighting. Using transient optical spectroscopy,
we study excitation recombination dynamics in manganese-doped CsPb(Cl,Br)3
perovskite nanocrystals. We find an increase in the intrinsic excitonic
radiative recombination rate upon doping, which is typically a challenging
material property to tailor. Supported by ab initio calculations, we can
attribute the enhanced emission rates to increased exciton localization through
lattice periodicity breaking from Mn dopants, which increases exciton effective
masses and overlap of electron and hole wavefunctions and thus the oscillator
strength. Our report of a fundamental strategy for improving luminescence
efficiencies in perovskite nanocrystals will be valuable for maximizing
efficiencies in light-emitting applications.
