Colloidal Quantum Dots as Saturable Fluorophores

Schwartz, Osip; Tenne, Ron; Levitt, Jonathan M.; Deutsch, Zvicka; Itzhakov, Stella; Oron, Dan

doi:10.1021/nn302551v

Cited by 23 publications

(32 citation statements)

References 31 publications

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“…The Journal of Physical Chemistry C Article This appears to be essential for acquiring PL trajectories of single NCs for long durations without substantial photobleaching, presumably due to a sufficient time interval provided for the excited NC to fully relax between pulses. 41 A representative 10 min trajectory of a single NC binned at 30 ms, shown in Figure 1d, demonstrates the lack of PL bleaching over this time scale. Corresponding histograms of the PL intensity during the first and last 100 s are displayed in Figure 1e; notably, in about half of the NCs, the overall PL intensity counts do not significantly change, but lower emission intensities are observed to slightly increase in frequency, while the higher emission intensities slightly decrease in frequency between the first and last 100 s of the PL trajectory.…”

Section: ■ Results and Discussionmentioning

confidence: 85%

Excitation Intensity Dependence of Photoluminescence Blinking in CsPbBr₃ Perovskite Nanocrystals

Gibson¹,

et al. 2018

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Perovskite semiconductors have emerged as a promising class of materials for optoelectronic applications. Their favorable device performances can be partly justified by the defect tolerance that originates from their electronic structure. The effect of this inherent defect tolerance, namely the absence of deep trap states, on the photoluminescence (PL) of perovskite nanocrystals (NCs) is currently not well understood. The PL emission of NCs fluctuates in time according to power law kinetics (PL intermittency, or blinking), a phenomenon that has been explored over the past two decades in a vast array of nanocrystal (NC) materials. The kinetics of the blinking process in perovskite NCs have not been widely explored. Here, PL trajectories of individual orthorhombic cesium lead bromide (CsPbBr 3 ) perovskite NCs are measured using a range of excitation intensities. The power law kinetics of the bright NC state are observed to truncate exponentially at long durations, with a truncation time that decreases with increasing intensity before saturating at an intensity corresponding to an average formation of a single exciton. The results indicate that a diffusion-controlled electron transfer (DCET) mechanism is the most likely charge trapping process, while Auger autoionization plays a lesser role. The relevance of the multiple recombination centers (MRC) model to the results presented here cannot be ascertained, since the underlying switching mechanism is not currently available. Further experimentation and theoretical work are needed to gain a comprehensive understanding of the photophysics in these emerging materials.

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Section: ■ Results and Discussionmentioning

confidence: 85%

Excitation Intensity Dependence of Photoluminescence Blinking in CsPbBr₃ Perovskite Nanocrystals

Gibson¹,

et al. 2018

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“…Since the photon correlation SNR increases monotonically with fluorescence quantum yield (QY) and the excitation repetition rate, labels should exhibit a high QY under close-to-saturation conditions. Photostability for a duration in the scale of a second, necessary for high SNR and to avoid scanning artifacts, has been demonstrated for colloidal QDs, solid-state defects and a variety of dye molecules routinely used in bio-imaging 31,36,38 . Finally, in order to achieve high photon rates under saturation conditions, the emitter's excited state lifetime should preferably be below a microsecond.…”

Section: Discussionmentioning

confidence: 99%

“…The first term, the absorption probability, is limited by the saturation of the emitter, that is, with a high enough laser power we can excite the emitter once per pulse. However, working close to saturation conditions has a negative impact on the stability and blinking of dye molecules and quantum dots (QDs) 36,43 . We therefore prefer to work at a laser power 2-5 times smaller than the saturation power.…”

Section: Supplementary Section 6 -Snr In Ism and Q-ism A Discussion Omentioning

confidence: 99%

Super-resolution enhancement by quantum image scanning microscopy

et al. 2018

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The principles of quantum optics have yielded a plethora of ideas to surpass the classical limitations of sensitivity and resolution in optical microscopy. While some ideas have been applied in proof-of-principle experiments, imaging a biological sample has remained challenging mainly due to the inherently weak signal measured and the fragility of quantum states of light. In principle, however, these quantum protocols can add new information without sacrificing the classical information and can therefore enhance the capabilities of existing super-resolution techniques. Image scanning microscopy (ISM), a recent addition to the family of super-resolution methods, generates a robust resolution enhancement without sacrificing the signal level. Here we introduce quantum image scanning microscopy (Q-ISM): combining ISM with the measurement of quantum photon correlation allows increasing the resolution of ISM up to two-fold, four times beyond the diffraction limit. We introduce the Q-ISM principle and obtain super-resolved optical images of a biological sample stained with fluorescent quantum dots using photon antibunching, a quantum effect, as a resolution enhancing contrast mechanism. Main TextThe diffraction limit, as formulated by Abbe, sets the attainable resolution in far-field optical microscopy to about half of the visible wavelength 1 , hindering its applicability in life science studies at very small scales. Over the past two decades, several super-resolution methods have successfully overcome the diffraction limit, including emission depletion microscopy, localization microscopy and structured illumination microscopy 2-6 . The continuous and rapid improvement in detector technology has enabled two more recent developments in the field of super-resolution microscopy, which are the center of this work: quantum super-resolution microscopy and image scanning microscopy (ISM). As for the first, a surge of interest in super-resolution imaging based on quantum optics concepts 7-13 , inspired and facilitated by the progress in high temporal resolution imagers, resulted in a few successful proof-of-principle demonstrations 7,8,14 . The second, ISM, relies on a small array of fast detector and offers a two-fold enhancement of resolution 15,16 . Since ISM is compatible with a standard confocal microscope architecture it has already been integrated into commercial products.While all super-resolution modalities violate at least one of the basic assumptions of the Abbe theory, many rely on breaking more than one. For instance, stimulated emission depletion (STED) and saturated structured illumination microscopy (SSIM) breach both the assumption of a linear response of a fluorophore to the excitation light and that of a uniform illumination field 17,18 . In contrast, the few demonstrations of quantum super-resolution microscopy 7,8,14 relied solely on violating the implicit assumption, underlying Abbe's derivation, that light behaves as waves rather than particles. ISM, as well, depends on violating a single assumption, a u...

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“…The PL blinking of single colloidal QD has been actively explored with different chemical compositions, morphologies, and measurement conditions after its discovery in 1996 . The diverse results can be roughly grouped into a few types of blinking.…”

Section: Different Types Of Pl Blinking Of Single Colloidal Qdmentioning

confidence: 99%

Photoluminescence Intermittency and Photo‐Bleaching of Single Colloidal Quantum Dot

et al. 2017

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Photoluminescence (PL) blinking of single colloidal quantum dot (QD)-PL intensity switching between different brightness states under constant excitation-and photo-bleaching are roadblocks for most applications of QDs. This progress report shall treat PL blinking and photo-bleaching both as photochemical events, namely, PL blinking as reversible and photo-bleaching being irreversible ones. Most studies on single-molecule spectroscopy of QDs in literature are related to PL blinking, which invites us to concentrate our discussions on the PL blinking, including its brief history in 20 years, analysis methods, competitive mechanisms and different strategies to battle it. In terms of suppression of the PL blinking, wavefunction confinement-confining photo-generated electron and hole within the core and inner portion of the shell of a core/shell QD-demonstrates significant advantages. This strategy yields nearly non-blinking QDs with their emission peaks covering most part of the visible window. As expected, the resulting QDs from this new strategy also show substantially improved anti-bleaching features.

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Colloidal Quantum Dots as Saturable Fluorophores

Cited by 23 publications

References 31 publications

Excitation Intensity Dependence of Photoluminescence Blinking in CsPbBr₃ Perovskite Nanocrystals

Excitation Intensity Dependence of Photoluminescence Blinking in CsPbBr₃ Perovskite Nanocrystals

Super-resolution enhancement by quantum image scanning microscopy

Photoluminescence Intermittency and Photo‐Bleaching of Single Colloidal Quantum Dot

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Colloidal Quantum Dots as Saturable Fluorophores

Cited by 23 publications

References 31 publications

Excitation Intensity Dependence of Photoluminescence Blinking in CsPbBr3 Perovskite Nanocrystals

Excitation Intensity Dependence of Photoluminescence Blinking in CsPbBr3 Perovskite Nanocrystals

Super-resolution enhancement by quantum image scanning microscopy

Photoluminescence Intermittency and Photo‐Bleaching of Single Colloidal Quantum Dot

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Excitation Intensity Dependence of Photoluminescence Blinking in CsPbBr₃ Perovskite Nanocrystals

Excitation Intensity Dependence of Photoluminescence Blinking in CsPbBr₃ Perovskite Nanocrystals