Photoluminescence Up-Conversion in CsPbBr3 Nanocrystals

We report the first observation of phonon-assisted photoluminescence up-conversion from CsPbBr3 nanocrystals (NCs) at both the ensemble and single-NC levels. Ensemble up-conversion efficiencies are estimated to be on the order of 75% for a ΔE = 23 meV excitation detuning into the nanocrystal gap.