Super-resolution photoluminescence lifetime and intensity mapping of interacting CdSe/CdS quantum dots

Abstract

We report an optical imaging method that simultaneously achieves nanometer-scale spatial resolution and records single-photon arrival times with subnanosecond temporal resolution, allowing for visualization of nanoscale photoluminescence dynamics. The technique combines time-correlated single-photon counting with single-molecule localization microscopy by monitoring the emission centroid location with a 2 × 2 array of optical fibers that are coupled to four single-photon counting detectors. We applied this method to image isolated and clustered CdSe/CdS core/shell quantum dots (QDs). Single QDs were localized with ∼5 nm precision using 104 detected photons. Within clusters, emission centroids separated by ∼12 nm were resolved, and spatial mapping of both the emission intensity and lifetime provided evidence of energy transport pathways among the QDs.