Photoluminescence Up-Conversion in CsPbBr3 Nanocrystals

Here 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 ∆E=23 meV excitation detuning into the nanocrystal gap.