Population-resolved single-emitter spectroscopy

The heterogeneity in optically active nanomaterials often hinders efforts to understand their basic photophysics and can limit their use in practical applications. Existing methods have difficulty characterizing single-emitter spectra and optical heterogeneity with accuracy and ease-of-use. Here, we introduce SPICEE (SPectrally Imbalanced Correlations from Ensemble Emission), a photon-correlation technique that automatically samples an ensemble to recover statistical trends in the single-particle spectra. Analytical derivations, numerical modeling, and experiments on a solution ensemble of emitters validate the technique. We apply SPICEE to blue-emitting ZnSeTe semiconductor nanocrystals relevant to display applications and find that the ensemble’s low color purity is primarily caused by a small subpopulation of nanocrystals with a distinct emission mechanism. This work demonstrates SPICEE to be an efficient and powerful tool for analyzing nanoscale systems. Traditional methods struggle to quantify the optical heterogeneity in nanomaterials. Here the authors develop a new spectroscopic tool that rapidly extracts trends in single-particle spectra and apply it to ZnSeTe nanocrystals, revealing the origin of their low color purity.