Photodynamics of a Single Quantum Dot:  Fluorescence Activation, Enhancement, Intermittency, and Decay

Lee, Steven F.; Osborne, Mark A.

doi:10.1021/ja071876+

Cited by 69 publications

(87 citation statements)

References 14 publications

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“…[88] This rising behavior or PL enhancement (Figure 4e), is also obtained in inorganic semiconductor QDs, e.g., CdSe QDs, [76] ZnS-capped CdSe QDs, [78] etc. This PL rising behavior has been attributed to the migration of charge carriers, followed by a trap-filling process at energetically shallow defects within the film.…”

Section: Pl Rising Mechanismsupporting

confidence: 52%

Impact of Structural Dynamics on the Optical Properties of Methylammonium Lead Iodide Perovskites

Panzer

Meier

et al. 2017

Advanced Energy Materials

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structure, [2] and changing the ratio of precursor compounds prior to the formation of the perovskite layer. [3] These approaches are based on modifying the crystallization process, for example, by controlling the composition of the precursor solution and by varying processing parameters. Such changes also led to major improvements in perovskite-based light-emitting devices within the last year. Initially, the current efficiencies were improved by optimizing the grain size to values below 100 nm, and by changing the precursor compound molar proportions. [4] More recently, efficient perovskite-based LEDs with external quantum efficiencies exceeding 10% were even obtained by expanding towards lower dimensional perovskite structures. [5] Different structures and dimensionalities resulted in altered charge-carrier dynamics affecting the radiative recombination efficiency. [5,6] By drawing strong correlations between structural properties and their electronic structure, major breakthroughs toward light-emitting devices or in photovoltaics could be achieved in very recent years. To a certain extent, this resembles the evolution in the field of organic semiconductors, where improved understanding of the interplay between morphological and electronic structure proved essential to facilitate the recent progress in organic photovoltaics, and the successful commercialisation of organic LED devices. Also, for hybrid perovskites the question of how crystal structure, shape, and grain size governs the electronic structure will remain an important topic in the future to further improve perovskite-based optoelectronic devices. Since the solution processability of hybrid perovskites enables easy tuning of material compositions, a large number of different hybrid perovskites were reported. For example, exchanging the organic cation can alter the crystal structure, shift phase transitions, as does formamidinium, or change further excited-state dynamics, as is happening with Cs or Ru. Furthermore, different halide anions change the optical and excited state properties. The optical bandgap can be changed from the UV to NIR region by replacing the halide from Cl to Br to I. Mixed-halide systems thereof even provide a way to gradually tune the respective bandgap. In fact, the recently reported, most stable and efficient perovskite solar cells (PSCs) are based on a highly optimized mixture of different anions and cations. [1,7] Nevertheless, the most investigated hybrid perovskite representative is the methylammonium lead iodide perovskite CH 3 NH 3 PbI 3 (MAPbI 3 ), which, in the meantime, has become Organolead halide perovskites have attracted a lot of attention over the recent years mostly due to their bright prospective application in photovoltaic devices. For further development, characterization of their physical properties plays a seminal role in order to gain an in-depth understanding of these mid-bandgap ionic semiconductors. Their unique optical and electronic properties are a result of their characteristic electronic stru...

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Section: Pl Rising Mechanismsupporting

confidence: 52%

Impact of Structural Dynamics on the Optical Properties of Methylammonium Lead Iodide Perovskites

Panzer

Meier

et al. 2017

Advanced Energy Materials

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“…48 Additional contribution may emanate from UV promoted photo-annealing of QDs, which can lead to enhancement of photoluminescence by reducing the number of surface trap states. 42,[62][63][64][65] Indeed, such photo-induced enhancement in the PL was also observed for His-PIMA-PEG-QDs following irradiation for 10 min in the UV reactor, though the measured enhancement was smaller (see Supporting Information, Figure S7). …”

Section: Characterization Of the Hydrophilicmentioning

confidence: 65%

Photoligation of an Amphiphilic Polymer with Mixed Coordination Provides Compact and Reactive Quantum Dots

et al. 2015

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We introduce a new set of multicoordinating polymers as ligands that combine two distinct metal-chelating groups, lipoic acid and imidazole, for the surface functionalization of QDs. These ligands combine the benefits of thiol and imidazole coordination to reduce issues of thiol oxidation and weak binding affinity of imidazole. The ligand design relies on the introduction of controllable numbers of lipoic acid and histamine anchors, along with hydrophilic moieties and reactive functionalities, onto a poly(isobutylene-alt-maleic anhydride) chain via a one-step nucleophilic addition reaction. We further demonstrate that this design is fully compatible with a novel and mild photoligation strategy to promote the in situ ligand exchange and phase transfer of hydrophobic QDs to aqueous media under borohydride-free conditions. Ligation with these polymers provides highly fluorescent QDs that exhibit great long-term colloidal stability over a wide range of conditions, including a broad pH range (3-13), storage at nanomolar concentration, under ambient conditions, in 100% growth media, and in the presence of competing agents with strong reducing property. We further show that incorporating reactive groups in the ligands permits covalent conjugation of fluorescent dye and redox-active dopamine to the QDs, producing fluorescent platforms where emission is controlled/tuned by Förster Resonance Energy Transfer (FRET) or pH-dependent charge transfer (CT) interactions. Finally, the polymer-coated QDs have been coupled to cell-penetrating peptides to facilitate intracellular uptake, while subsequent cytotoxicity tests show no apparent decrease in cell viability.

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“…It was reported that light-induced photobleaching was a common factor affecting the fluorescence ability of colloidal semiconductor nanocrystals. [19][20] With the same photodynamics mechanism, our QDs system did not show complete decay in just hundreds of seconds, due to the fact that the excitation photons from the natural light in our study had low energy and limited excitation frequency. So it took more than five hours for the QDs system to complete the quenching process.…”

Section: Resultsmentioning

confidence: 77%

Fluorescence Resonance Energy Transfer Based Immunosensing of Human IgG by Using Quantum Dot/GIgG–Gold Nanoparticles/IgG Conjugation

Luo¹,

Liu²,

Li³

et al. 2014

j. nanosci. nanotech.

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A novel immunosensor of human immune globulin (IgG) was fabricated based on the fluorescence transfer between luminescent semiconductor quantum dots (QDs) and gold nanoparticles (AuNPs). AuNPs and CdSe/ZnS QDs were respectively labeled with immune reaction pair:IgG and goat anti-human immunoglobulin (GIgG), by optimizing the conditions including pH value and protein amount. In the assembled QD-GIgG-IgG-AuNP fluorescence resonance energy transfer (FRET) immunocomplex system, the presence of AuNP-IgG directly reduced the fluorescence intensity of the GIgG conjugated QDs. As a result, the concentration of AuNP-IgG had a linear relationship with the fluorescence decrease in a range of 0-1.57 microg/mL. Furthermore, the mechanism of the QDs' fluorescence decay has also been discussed and attributed to the light-induced photobleaching. This novel sensing method achieves quantitative detection of trace proteins, suggesting the potential of biomolecule-AuNPs conjugation based analytical methods in further application.

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Photodynamics of a Single Quantum Dot: Fluorescence Activation, Enhancement, Intermittency, and Decay

Cited by 69 publications

References 14 publications

Impact of Structural Dynamics on the Optical Properties of Methylammonium Lead Iodide Perovskites

Impact of Structural Dynamics on the Optical Properties of Methylammonium Lead Iodide Perovskites

Photoligation of an Amphiphilic Polymer with Mixed Coordination Provides Compact and Reactive Quantum Dots

Fluorescence Resonance Energy Transfer Based Immunosensing of Human IgG by Using Quantum Dot/GIgG–Gold Nanoparticles/IgG Conjugation

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