Abstract
AbstractBlinking nanoscale emitters, typically single molecules, are employed in single‐molecule localization microscopy (SMLM), such as direct stochastic optical reconstruction microscopy (dSTORM), to overcome Abbe's diffraction limit, offering spatial resolution of few tens of nanometers. Colloidal quantum dots (QDs) feature high photostability, ultrahigh absorption cross‐sections and brightness, as well as wide tunability of the emission properties, making them a compelling alternative to organic molecules. Here, CsPbBr3 nanocrystals, the latest addition to the QD family, are explored as probes in SMLM. Because of the strongly suppressed QD photoluminescence blinking (ON/OFF occurrence higher than 90%), it is difficult to resolve emitters with overlapping point‐spread functions by standard dSTORM methods due to false localizations. A new workflow based on ellipticity filtering efficiently identifies false localizations and allows the precise localization of QDs with subwavelength spatial resolution. Aided by Monte‐Carlo simulations, the optimal QD blinking dynamics for dSTORM applications is identified, harnessing the benefits of higher QD absorption cross‐section and the enhanced QD photostability to further expand the field of QD super‐resolution microscopy toward sub‐nanometer spatial resolution.
Highlights
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A new workand, in particular, direct stochastic optical reconstruction microscopy are a family of nanoscopy methods, which identify the spatial coordinates of an emitter by fitting the point-spread functions (PSFs) of individual emitters and, thereby, recovering flow based on ellipticity filtering efficiently identifies false localizations and allows the emitter’s position with high accuracy.[5]
The emitter remains in the ON-state for most of the time. These observations are consistent with previous studies reporting PL blinking of CsPbX3 quantum dots (QDs) (X = Cl, Br, I),[26,36,37,38,39] and other QD materials,[40,41,42] and will cause problems when QDs are chosen as SMLM probes
Summary
The CsPbBr3 QDs studied were produced according to our previously published procedure.[35]. Measurements on 19 different QDs yield a mean second-order correlation function at zero delay time of 0.31(0.09) (Figure 1d), attesting the presence of wellisolated single emitters in the sample This allows us to assume that some of the bright spots in the wide-field image (Figure 1a) correspond to isolated QDs. We can, treat intensity traces of these spots, after careful evaluation, as single-emitter traces. This is the main obstacle for the deployment of blinking colloidal QDs in SMLM
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