1
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Gallagher S, Kline J, Jahanbakhshi F, Sadighian JC, Lyons I, Shen G, Hammel BF, Yazdi S, Dukovic G, Rappe AM, Ginger DS. Ligand Equilibrium Influences Photoluminescence Blinking in CsPbBr 3: A Change Point Analysis of Widefield Imaging Data. ACS NANO 2024; 18:19208-19219. [PMID: 38982590 DOI: 10.1021/acsnano.4c04968] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/11/2024]
Abstract
Photoluminescence intermittency remains one of the biggest challenges in realizing perovskite quantum dots (QDs) as scalable single photon emitters. We compare CsPbBr3 QDs capped with different ligands, lecithin, and a combination of oleic acid and oleylamine, to elucidate the role of surface chemistry on photoluminescence intermittency. We employ widefield photoluminescence microscopy to sample the blinking behavior of hundreds of QDs. Using change point analysis, we achieve the robust classification of blinking trajectories, and we analyze representative distributions from large numbers of QDs (Nlecithin = 1308, Noleic acid/oleylamine = 1317). We find that lecithin suppresses blinking in CsPbBr3 QDs compared with oleic acid/oleylamine. Under common experimental conditions, lecithin-capped QDs are 7.5 times more likely to be nonblinking and spend 2.5 times longer in their most emissive state, despite both QDs having nearly identical solution photoluminescence quantum yields. We measure photoluminescence as a function of dilution and show that the differences between lecithin and oleic acid/oleylamine capping emerge at low concentrations during preparation for single particle experiments. From experiment and first-principles calculations, we attribute the differences in lecithin and oleic acid/oleylamine performance to differences in their ligand binding equilibria. Consistent with our experimental data, density functional theory calculations suggest a stronger binding affinity of lecithin to the QD surface compared to oleic acid/oleylamine, implying a reduced likelihood of ligand desorption during dilution. These results suggest that using more tightly binding ligands is a necessity for surface passivation and, consequently, blinking reduction in perovskite QDs used for single particle and quantum light experiments.
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Affiliation(s)
- Shaun Gallagher
- Department of Chemistry, University of Washington, Seattle, Washington 98195, United States
| | - Jessica Kline
- Department of Chemistry, University of Washington, Seattle, Washington 98195, United States
| | - Farzaneh Jahanbakhshi
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - James C Sadighian
- Department of Chemistry, University of Washington, Seattle, Washington 98195, United States
| | - Ian Lyons
- Department of Chemistry, University of Washington, Seattle, Washington 98195, United States
| | - Gillian Shen
- Department of Chemistry, University of Washington, Seattle, Washington 98195, United States
| | - Benjamin F Hammel
- Materials Science and Engineering, University of Colorado Boulder, Boulder, Colorado 80309-0215, United States
| | - Sadegh Yazdi
- Materials Science and Engineering, University of Colorado Boulder, Boulder, Colorado 80309-0215, United States
- Renewable and Sustainable Energy Institute, University of Colorado Boulder, Boulder, Colorado 80309-0215, United States
| | - Gordana Dukovic
- Materials Science and Engineering, University of Colorado Boulder, Boulder, Colorado 80309-0215, United States
- Renewable and Sustainable Energy Institute, University of Colorado Boulder, Boulder, Colorado 80309-0215, United States
- Department of Chemistry, University of Colorado Boulder, Boulder, Colorado 80309-0215, United States
| | - Andrew M Rappe
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - David S Ginger
- Department of Chemistry, University of Washington, Seattle, Washington 98195, United States
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2
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Dhar M, Berg MA. Efficient, nonparametric removal of noise and recovery of probability distributions from time series using nonlinear-correlation functions: Photon and photon-counting noise. J Chem Phys 2024; 161:034116. [PMID: 39028845 DOI: 10.1063/5.0212157] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2024] [Accepted: 06/28/2024] [Indexed: 07/21/2024] Open
Abstract
A preceding paper [M. Dhar, J. A. Dickinson, and M. A. Berg, J. Chem. Phys. 159, 054110 (2023)] shows how to remove additive noise from an experimental time series, allowing both the equilibrium distribution of the system and its Green's function to be recovered. The approach is based on nonlinear-correlation functions and is fully nonparametric: no initial model of the system or of the noise is needed. However, single-molecule spectroscopy often produces time series with either photon or photon-counting noise. Unlike additive noise, photon noise is signal-size correlated and quantized. Photon counting adds the potential for bias. This paper extends noise-corrected-correlation methods to these cases and tests them on synthetic datasets. Neither signal-size correlation nor quantization is a significant complication. Analysis of the sampling error yields guidelines for the data quality needed to recover the properties of a system with a given complexity. We show that bias in photon-counting data can be corrected, even at the high count rates needed to optimize the time resolution. Using all these results, we discuss the factors that limit the time resolution of single-molecule spectroscopy and the conditions that would be needed to push measurements into the submicrosecond region.
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Affiliation(s)
- Mainak Dhar
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina 29208, USA
| | - Mark A Berg
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina 29208, USA
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3
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Penkov B, Niedzwiecki D, Lari N, Drndić M, Shepard K. Time-domain event detection using single-instruction, multiple-thread gpGPU architectures in single-molecule biophysical data. COMPUTER PHYSICS COMMUNICATIONS 2024; 300:109191. [PMID: 38737416 PMCID: PMC11086699 DOI: 10.1016/j.cpc.2024.109191] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2024]
Abstract
Discrete amplitude levels in ordered, time-domain data often represent different underlying latent states of the system that is being interrogated. Analysis and feature extraction from these data sets generally require considering the order of each individual point; this approach cannot take advantage of contemporary general-purpose graphics processing units (gpGPU) and single-instruction multiple-data (SIMD) instruction set architectures. Two sources of such data from single-molecule biological measurements are nanopores and single-molecule field effect transistor (smFET) nanotube devices; both generate streams of time-ordered current or voltage data, typically sampled near 1 MS/s, with run times of minutes, yielding terabyte-scale datasets. Here, we present three gpGPU-based algorithms to overcome limitations associated with serial event detection in time series data, resulting in a 250× improvement in the rate with which we can detect salient features in nanopore and smFET datasets. The code is freely available.
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Affiliation(s)
- Boyan Penkov
- Department of Electrical Engineering, Columbia University, New York, NY, 10027
| | - David Niedzwiecki
- Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA 19104 USA
| | - Nicolae Lari
- Department of Electrical Engineering, Columbia University, New York, NY, 10027
| | - Marija Drndić
- Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA 19104 USA
| | - Kenneth Shepard
- Department of Electrical Engineering, Columbia University, New York, NY, 10027
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4
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Sica AV, Hua AS, Lin HH, Sletten EM, Atallah TL, Caram JR. Spectrally Selective Time-Resolved Emission through Fourier-Filtering (STEF). J Phys Chem Lett 2023; 14:552-558. [PMID: 36630700 DOI: 10.1021/acs.jpclett.2c01504] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
We demonstrate a method for separating and resolving the dynamics of multiple emitters without the use of conventional filters. By directing the photon emission through a fixed path-length imbalanced Mach-Zehnder interferometer, we interferometrically cancel (or enhance) certain spectral signatures corresponding to one emissive species. Our approach, Spectrally selective Time-resolved Emission through Fourier-filtering (STEF), leverages the detection and subtraction of both outputs of a tuned Mach-Zehnder interferometer, which can be combined with time-correlated single photon counting (TCSPC) or confocal imaging to demix multiple emitter signatures. We develop a procedure to calibrate out imperfections in Mach-Zehnder interferometry schemes. Additionally, we demonstrate the range and utility of STEF by performing the following procedures with one measurement: (1) filtering out laser scatter from a sample, (2) separating and measuring a fluorescence lifetime from a binary chromophore mixture with overlapped emission spectra, (3) confocally imaging and separately resolving the standard fluorescent stains in bovine pulmonary endothelial cells and nearly overlapping fluorescent stains on RAW 264.7 cells. This form of spectral balancing can allow for robust and tunable signal sorting.
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Affiliation(s)
- Anthony V Sica
- Department of Chemistry and Biochemistry, University of California, Los Angeles, 607 Charles E. Young Drive, Los Angeles, California90095-1569, United States
| | - Ash Sueh Hua
- Department of Chemistry and Biochemistry, University of California, Los Angeles, 607 Charles E. Young Drive, Los Angeles, California90095-1569, United States
| | - Helen H Lin
- Department of Chemistry and Biochemistry, University of California, Los Angeles, 607 Charles E. Young Drive, Los Angeles, California90095-1569, United States
| | - Ellen M Sletten
- Department of Chemistry and Biochemistry, University of California, Los Angeles, 607 Charles E. Young Drive, Los Angeles, California90095-1569, United States
| | - Timothy L Atallah
- Department of Chemistry and Biochemistry, Denison University, 500 West Loop, Granville, Ohio43023, United States
| | - Justin R Caram
- Department of Chemistry and Biochemistry, University of California, Los Angeles, 607 Charles E. Young Drive, Los Angeles, California90095-1569, United States
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5
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Baronnier J, Mahler B, Boisron O, Dujardin C, Kulzer F, Houel J. Optical properties of fully inorganic core/gradient-shell CdSe/CdZnS nanocrystals at the ensemble and single-nanocrystal levels. Phys Chem Chem Phys 2021; 23:22750-22759. [PMID: 34608907 DOI: 10.1039/d1cp02927d] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We report the synthesis and optical characterization of fully inorganic gradient-shell CdSe/CdZnS nanocrystals (NCs) with high luminescence quantum yield (QY, 50%), which were obtained by replacing native oleic-acid (OA) ligands with halide ions (Cl-and Br-). Absorption, photoluminescence excitation (PLE) and photoluminescence (PL) spectra in solution were unaffected by the ligand-exchange procedure. The halide-capped NCs were stable in solution for several weeks without modification of their PL spectra; once deposited as unprotected thin films and exposed to air, however, they did show signs of aging which we attribute to increasing heterogeneity of (effective) NC size. Time-resolved PL measurements point to the existence of four distinct emissive states, which we attribute to neutral, singly-charged and multi-excitonic entities. We found that the relative contribution of these four components to the overall PL decay is modified by the OA-to-halide ligand exchange, while the excited-state lifetimes themselves, surprisingly, remain largely unaffected. The high PL quantum yield of the halide-capped NCs allowed observation of single particle blinking and photon-antibunching; one surprising result was that aging processes that occurs during the first few days after deposition on glass seemed to offer a certain increased protection against photobleaching. These results suggest that halide-capped CdSe/CdZnS NCs are promising candidates for incorporation into opto-electronic devices, based on, for example, hybrid perovskite matrices, which require eliminating the steric hindrance and electronic barrier of bulky organic ligands to ensure efficient coupling.
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Affiliation(s)
- Justine Baronnier
- Univ. Lyon, Université Claude Bernard Lyon 1, CNRS UMR5306, Institut Lumière Matière, 69622 Villeurbanne, France.
| | - Benoit Mahler
- Univ. Lyon, Université Claude Bernard Lyon 1, CNRS UMR5306, Institut Lumière Matière, 69622 Villeurbanne, France.
| | - Olivier Boisron
- Univ. Lyon, Université Claude Bernard Lyon 1, CNRS UMR5306, Institut Lumière Matière, 69622 Villeurbanne, France.
| | - Christophe Dujardin
- Univ. Lyon, Université Claude Bernard Lyon 1, CNRS UMR5306, Institut Lumière Matière, 69622 Villeurbanne, France.
| | - Florian Kulzer
- Univ. Lyon, Université Claude Bernard Lyon 1, CNRS UMR5306, Institut Lumière Matière, 69622 Villeurbanne, France.
| | - Julien Houel
- Univ. Lyon, Université Claude Bernard Lyon 1, CNRS UMR5306, Institut Lumière Matière, 69622 Villeurbanne, France.
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6
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Palstra I, Koenderink AF. A Python Toolbox for Unbiased Statistical Analysis of Fluorescence Intermittency of Multilevel Emitters. THE JOURNAL OF PHYSICAL CHEMISTRY. C, NANOMATERIALS AND INTERFACES 2021; 125:12050-12060. [PMID: 34276862 PMCID: PMC8282189 DOI: 10.1021/acs.jpcc.1c01670] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/24/2021] [Revised: 05/05/2021] [Indexed: 06/13/2023]
Abstract
We report on a Python toolbox for unbiased statistical analysis of fluorescence intermittency properties of single emitters. Intermittency, that is, step-wise temporal variations in the instantaneous emission intensity and fluorescence decay rate properties, is common to organic fluorophores, II-VI quantum dots, and perovskite quantum dots alike. Unbiased statistical analysis of intermittency switching time distributions, involved levels, and lifetimes are important to avoid interpretation artifacts. This work provides an implementation of Bayesian changepoint analysis and level clustering applicable to time-tagged single-photon detection data of single emitters that can be applied to real experimental data and as a tool to verify the ramifications of hypothesized mechanistic intermittency models. We provide a detailed Monte Carlo analysis to illustrate these statistics tools and to benchmark the extent to which conclusions can be drawn on the photophysics of highly complex systems, such as perovskite quantum dots that switch between a plethora of states instead of just two.
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Affiliation(s)
- Isabelle
M. Palstra
- Institute
of Physics, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands
- Center
for Nanophotonics, AMOLF, Science Park 104, 1098 XG Amsterdam, The Netherlands
| | - A. Femius Koenderink
- Center
for Nanophotonics, AMOLF, Science Park 104, 1098 XG Amsterdam, The Netherlands
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7
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Palstra I, de Buy Wenniger IM, Patra BK, Garnett EC, Koenderink AF. Intermittency of CsPbBr 3 Perovskite Quantum Dots Analyzed by an Unbiased Statistical Analysis. THE JOURNAL OF PHYSICAL CHEMISTRY. C, NANOMATERIALS AND INTERFACES 2021; 125:12061-12072. [PMID: 34276863 PMCID: PMC8282187 DOI: 10.1021/acs.jpcc.1c01671] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/24/2021] [Revised: 05/05/2021] [Indexed: 06/13/2023]
Abstract
We analyze intermittency in intensity and fluorescence lifetime of CsPbBr3 perovskite quantum dots by applying unbiased Bayesian inference analysis methods. We apply change-point analysis (CPA) and a Bayesian state clustering algorithm to determine the timing of switching events and the number of states between which switching occurs in a statistically unbiased manner, which we have benchmarked particularly to apply to highly multistate emitters. We conclude that perovskite quantum dots display a plethora of gray states in which brightness, broadly speaking, correlates inversely with decay rate, confirming the multiple recombination centers model. We leverage the CPA partitioning analysis to examine aging and memory effects. We find that dots tend to return to the bright state before jumping to a dim state and that when choosing a dim state, they tend to explore the entire set of states available.
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Affiliation(s)
- Isabelle
M. Palstra
- Institute
of Physics, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands
- Center
for Nanophotonics, AMOLF, Science Park 104, 1098 XG Amsterdam, The Netherlands
| | | | - Biplab K. Patra
- Center
for Nanophotonics, AMOLF, Science Park 104, 1098 XG Amsterdam, The Netherlands
| | - Erik C. Garnett
- Center
for Nanophotonics, AMOLF, Science Park 104, 1098 XG Amsterdam, The Netherlands
| | - A. Femius Koenderink
- Center
for Nanophotonics, AMOLF, Science Park 104, 1098 XG Amsterdam, The Netherlands
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8
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Hasham M, Wilson MWB. Sub-Bandgap Optical Modulation of Quantum Dot Blinking Statistics. J Phys Chem Lett 2020; 11:6404-6412. [PMID: 32787286 DOI: 10.1021/acs.jpclett.0c01599] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Colloidal quantum dots (QDs) suffer from pervasive photoluminescence intermittency that frustrates applications and correlates with irreversible photodegradation. In single-QD spectroscopies, blinking manifests as sporadic switching between ON and OFF states without a characteristic time scale, and the longstanding search for mechanisms has been recently accelerated by techniques to controllably modulate the QD environment. Here, we develop an all-optical modulation scheme and demonstrate that sub-bandgap light tuned to the stimulated emission transition perturbs the blinking statistics of individual CdSe/ZnS core/shell QDs. Resonant optical modulation progressively suppresses long-duration ON events, quantified by a power-law slope that is more negative on average (ΔαON = 0.46 ± 0.09), while OFF distributions and truncation times are unaffected. This characteristic effect is robust to choices in background subtraction and statistical analysis but supports mechanistic descriptions beyond first-order kinetics. This demonstration of all-optical perturbation of QD blinking dynamics provides an experimental avenue to disentangle the complex photophysics of photoluminescence intermittency.
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Affiliation(s)
- Minhal Hasham
- Department of Chemistry, University of Toronto, Toronto, M5S 3H6 Ontario, Canada
| | - Mark W B Wilson
- Department of Chemistry, University of Toronto, Toronto, M5S 3H6 Ontario, Canada
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9
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Xue Y, Wang H, Xie N, Yang Q, Xu F, Shen B, Shi JJ, Jiang D, Dou X, Yu T, Sun BQ. Single-Photon Emission from Point Defects in Aluminum Nitride Films. J Phys Chem Lett 2020; 11:2689-2694. [PMID: 32186889 DOI: 10.1021/acs.jpclett.0c00511] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Quantum technologies require robust and photostable single-photon emitters. Here, room temperature operated single-photon emissions from isolated defects in aluminum nitride (AlN) films are reported. AlN films were grown on nanopatterned sapphire substrates by metal organic chemical vapor deposition. The observed emission lines range from visible to near-infrared, with highly linear polarization characteristics. The temperature-dependent line width increase shows T3 or single-exponential behavior. First-principle calculations based on density functional theory show that point defect species, such as antisite nitrogen vacancy complex (NAlVN) and divacancy (VAlVN) complexes, are considered to be an important physical origin of observed emission lines ranging from approximately 550 to 1000 nm. The results provide a new platform for on-chip quantum sources.
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Affiliation(s)
- Yongzhou Xue
- State Key Laboratory for Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China
| | - Hui Wang
- State Key Laboratory for Artificial Microstructures and Mesoscopic Physics, School of Physics, Peking University, Beijing 100871, China
| | - Nan Xie
- State Key Laboratory for Artificial Microstructures and Mesoscopic Physics, School of Physics, Peking University, Beijing 100871, China
| | - Qian Yang
- State Key Laboratory for Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China
- College of Materials Science and Optoelectronic Technology, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Fujun Xu
- State Key Laboratory for Artificial Microstructures and Mesoscopic Physics, School of Physics, Peking University, Beijing 100871, China
| | - Bo Shen
- State Key Laboratory for Artificial Microstructures and Mesoscopic Physics, School of Physics, Peking University, Beijing 100871, China
| | - Jun-Jie Shi
- State Key Laboratory for Artificial Microstructures and Mesoscopic Physics, School of Physics, Peking University, Beijing 100871, China
| | - Desheng Jiang
- State Key Laboratory for Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China
- College of Materials Science and Optoelectronic Technology, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Xiuming Dou
- State Key Laboratory for Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China
- College of Materials Science and Optoelectronic Technology, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Tongjun Yu
- State Key Laboratory for Artificial Microstructures and Mesoscopic Physics, School of Physics, Peking University, Beijing 100871, China
| | - Bao-Quan Sun
- State Key Laboratory for Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China
- College of Materials Science and Optoelectronic Technology, University of Chinese Academy of Sciences, Beijing 100049, China
- Beijing Academy of Quantum Information Sciences, Beijing 100193, China
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10
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Hou L, Zhao C, Yuan X, Zhao J, Krieg F, Tamarat P, Kovalenko MV, Guo C, Lounis B. Memories in the photoluminescence intermittency of single cesium lead bromide nanocrystals. NANOSCALE 2020; 12:6795-6802. [PMID: 32181469 DOI: 10.1039/d0nr00633e] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Single cesium lead bromide (CsPbBr3) nanocrystals show strong photoluminescence intermittency, with on- and off- dwelling times following power-law distributions. We investigate the correlations for successive on-times and successive off-times, and find a memory effect in the photoluminescence intermittency of such inorganic perovskite nanocrystals. This memory effect is not sensitive to the nature of the surface capping ligand and the embedding polymer. These observations suggest that photoluminescence intermittency and its memory are mainly controlled by intrinsic traps in the nanocrystals. Our findings will help optimizing light-emitting devices based on these perovskite nanocrystals.
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Affiliation(s)
- Lei Hou
- Université de Bordeaux, LP2N, Talence, France.
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11
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Trinh CT, Minh DN, Ahn KJ, Kang Y, Lee KG. Verification of Type-A and Type-B-HC Blinking Mechanisms of Organic-Inorganic Formamidinium Lead Halide Perovskite Quantum Dots by FLID Measurements. Sci Rep 2020; 10:2172. [PMID: 32034230 PMCID: PMC7005873 DOI: 10.1038/s41598-020-58926-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2019] [Accepted: 01/21/2020] [Indexed: 12/04/2022] Open
Abstract
Organic–inorganic halide perovskite nanocrystals or quantum dots (PQDs) are excellent candidates for optoelectronic applications, such as lasers, solar cells, light emitting diodes, and single photon sources. However, the potential applications of PQDs can expand once the photoluminescence, and in particular, the blinking behaviors of single PQDs are understood. Although the blinking of PQDs has been studied extensively recently, the underlying mechanism of the blinking behaviors is still under debate. In this study, we confirmed that type-A and type-B-HC (hot carrier) blinking, contributed to PQD blinking using their fluorescence lifetime intensity distribution (FLID). Type-B-HC blinking was experimentally confirmed for the first time for formamidinium based PQDs, and the simultaneous contributions of type-A and type-B blinking were clearly specified. Further, we related different FLID data to the ON/OFF time distribution as distinct features of different blinking types. We also emphasized that detection capability was crucial for correctly elucidating the blinking mechanism.
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Affiliation(s)
- Cong Tai Trinh
- Department of Physics, Hanyang University, Seoul, 04763, Republic of Korea
| | - Duong Nguyen Minh
- Department of Chemistry, Research Institute for Natural Sciences, Institute of Nano Science and Technology, Hanyang University, Seoul, 04763, Republic of Korea
| | - Kwang Jun Ahn
- Department of Physics and Department of Energy Systems Research, Ajou University, Suwon, 16499, Republic of Korea
| | - Youngjong Kang
- Department of Chemistry, Research Institute for Natural Sciences, Institute of Nano Science and Technology, Hanyang University, Seoul, 04763, Republic of Korea
| | - Kwang-Geol Lee
- Department of Physics, Hanyang University, Seoul, 04763, Republic of Korea.
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12
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Mukherjee A, Ray KK, Phadnis C, Layek A, Bera S, Chowdhury A. Insights on heterogeneity in blinking mechanisms and non-ergodicity using sub-ensemble statistical analysis of single quantum-dots. J Chem Phys 2019; 151:084701. [PMID: 31470698 DOI: 10.1063/1.5095870] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Photo-luminescence (P-L) intermittency (or blinking) in semiconductor nanocrystals (NCs), a phenomenon ubiquitous to single-emitters, is generally considered to be temporally random intensity fluctuations between "bright" ("On") and "dark" ("Off") states. However, individual quantum-dots (QDs) rarely exhibit such telegraphic signals, and yet, a vast majority of single-NC blinking data are analyzed using a single fixed threshold which generates binary trajectories. Furthermore, while blinking dynamics can vary dramatically over NCs in the ensemble, the extent of diversity in the exponents (mOn/Off) of single-particle On-/Off-time distributions (P(tOn/Off)), often used to validate mechanistic models of blinking, remains unclear due to a lack of statistically relevant data sets. Here, we subclassify an ensemble of QDs based on the emissivity of each emitter and subsequently compare the (sub)ensembles' behaviors. To achieve this, we analyzed a large number (>1000) of blinking trajectories for a model system, Mn+2 doped ZnCdS QDs, which exhibits diverse blinking dynamics. An intensity histogram dependent thresholding method allowed us to construct distributions of relevant blinking parameters (such as mOn/Off). Interestingly, we find that single QD P(tOn/Off)s follow either truncated power law or power law, and their relative proportion varies over subpopulations. Our results reveal a remarkable variation in mOn/Off amongst as well as within subensembles, which implies multiple blinking mechanisms being operational amongst various QDs. We further show that the mOn/Off obtained via cumulative single-particle P(tOn/Off) is distinct from the weighted mean value of all single-particle mOn/Off, evidence for the lack of ergodicity. Thus, investigation and analyses of a large number of QDs, albeit for a limited time span of a few decades, are crucial to characterize the spatial heterogeneity in possible blinking mechanisms.
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Affiliation(s)
- Amitrajit Mukherjee
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai, India
| | - Korak Kumar Ray
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai, India
| | - Chinmay Phadnis
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai, India
| | - Arunasish Layek
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai, India
| | - Soumya Bera
- Department of Physics, Indian Institute of Technology Bombay, Powai, Mumbai, India
| | - Arindam Chowdhury
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai, India
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13
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De CK, Roy D, Mandal S, Mandal PK. Suppressed Blinking under Normal Air Atmosphere in Toxic-Metal-Free, Small Sized, InP-Based Core/Alloy-Shell/Shell Quantum Dots. J Phys Chem Lett 2019; 10:4330-4338. [PMID: 31294573 DOI: 10.1021/acs.jpclett.9b01157] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Suppressed blinking has been reported in large (diameter ∼14.1 nm) core/shell InP quantum dots (QDs) under reduced air environment. We report here suppressed blinking with approximately four times smaller (diameter ∼3.6 nm) core/alloy-shell/shell InP QDs under ambient air atmosphere. The ⟨ON fraction⟩ has been obtained to be 0.65. Approximately 26% of the single QDs exhibit ON fraction >80%. The smaller ON exponent (1.19) magnitude in comparison to the OFF exponent (1.45) indicates longer ON events are interrupted by smaller OFF events. ON event truncation time is ∼1.5 times that of the OFF event, signifying the detrapping rate is much higher than the trapping rate. Interestingly, the detrapping rate/trapping rate (single-particle level property) could be directly correlated to the photoluminescence quantum yield (ensemble level property). An additional exponential term required to fit the probability density distribution of the ON event duration could be correlated with hole trapping, leading to extended ON times (>60 s).
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14
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Rabouw F, Antolinez FV, Brechbühler R, Norris DJ. Microsecond Blinking Events in the Fluorescence of Colloidal Quantum Dots Revealed by Correlation Analysis on Preselected Photons. J Phys Chem Lett 2019; 10:3732-3738. [PMID: 31204809 PMCID: PMC6614792 DOI: 10.1021/acs.jpclett.9b01348] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2019] [Accepted: 06/15/2019] [Indexed: 05/24/2023]
Abstract
Nearly all colloidal quantum dots, when measured at the single-emitter level, exhibit fluorescence "blinking". However, despite over 20 years of research on this phenomenon, its microscopic origins are still debated. One reason is a gap in available experimental information, specifically for dynamics at short (submillisecond) time scales. Here, we use photon-correlation analysis to investigate microsecond blinking events in individual quantum dots. While the strongly distributed kinetics of blinking normally makes such events difficult to study, we show that they can be analyzed by excluding photons emitted during long bright or dark periods. Moreover, we find that submillisecond blinking events are more common than one might expect from extrapolating the power-law blinking statistics observed on longer (millisecond) time scales. This result provides important experimental data for developing a microscopic understanding of blinking. More generally, our method offers a simple strategy for analyzing microsecond switching dynamics in the fluorescence of quantum emitters.
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15
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Chen JS, Li M, Cotlet M. Nanoscale Photoinduced Charge Transfer with Individual Quantum Dots: Tunability through Synthesis, Interface Design, and Interaction with Charge Traps. ACS OMEGA 2019; 4:9102-9112. [PMID: 31459998 PMCID: PMC6648770 DOI: 10.1021/acsomega.9b00803] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/22/2019] [Accepted: 05/03/2019] [Indexed: 05/29/2023]
Abstract
Semiconducting colloidal quantum dots (QDs) provide an excellent platform for nanoscale charge-transfer studies. Because of their size-dependent optoelectronic properties, which can be tuned via chemical synthesis and of their versatility in surface ligand exchange, QDs can be coupled with various types of acceptors to create hybrids with controlled type (electron or hole), direction, and rate of charge flow, depending on the foreseen application, either solar harvesting, light emitting, or biosensing. This perspective highlights several examples of QD-based hybrids with controllable (tunable) rate of charge transfer obtained by various approaches, including by changing the QD core size and shell thickness by colloidal synthesis, by the insertion of molecular linkers or dielectric spacers between donor and acceptor components. We also show that subjecting QDs to external factors such as electric fields and alternate optical excitation energy is another approach to bias the internal charge transfer between charges photogenerated in the QD core and QD's surface charge traps. The perspective also provides the reader with various examples of how single nanoparticle spectroscopic studies can help in understanding and quantifying nanoscale charge transfer with QDs.
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Affiliation(s)
- Jia-Shiang Chen
- Center
for Functional Nanomaterials, Brookhaven
National Laboratory, Upton, New York 11973, United States
- Department
of Materials Science and Chemical Engineering, Stony Brook University, Stony
Brook, New York 11794, United States
| | - Mingxing Li
- Center
for Functional Nanomaterials, Brookhaven
National Laboratory, Upton, New York 11973, United States
| | - Mircea Cotlet
- Center
for Functional Nanomaterials, Brookhaven
National Laboratory, Upton, New York 11973, United States
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16
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Lynch PG, Richards H, Wustholz KL. Unraveling the Excited-State Dynamics of Eosin Y Photosensitizers Using Single-Molecule Spectroscopy. J Phys Chem A 2019; 123:2592-2600. [PMID: 30835475 DOI: 10.1021/acs.jpca.9b00409] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The intersystem crossing and dispersive electron-transfer dynamics of eosin Y (EY) photosensitizers are probed using single-molecule microscopy. The blinking dynamics of EY on glass are quantified by constructing cumulative distribution functions of emissive ("on") and nonemissive ("off") events. Maximum likelihood estimation (MLE) and goodness-of-fit tests based on the Kolmogorov-Smirnov (KS) statistic are used to establish the best fit to the blinking data and differentiate among competitive photophysical processes. The on-time probability distributions for EY in N2 and air are power-law distributed after ∼1 s, with fit parameters that are significantly modified upon exposure to oxygen. By extending the statistically principled MLE/KS approach to include an onset time for log-normal behavior, we demonstrate that the off-time distribution for EY in N2 is best fit to a combination of exponential and log-normal functions. The corresponding distribution for EY in air is best fit to a log-normal function alone. Furthermore, power law and log-normal distributions are observed for an individual molecule in air, consistent with dynamic fluctuations in the rate constant for dark-state population and depopulation. These observations support the interpretation that dispersive electron transfer (i.e., the Albery model) from the first excited singlet state (S1) of EY to trap states on glass is predominately responsible for blinking in oxic conditions. In anoxic environment, both triplet-state blinking and dispersive electron transfer from S1 and the excited triplet state (T1) contribute to the excited-state dynamics of EY.
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Affiliation(s)
- Pauline G Lynch
- College of William and Mary , Department of Chemistry , P.O. Box 8795, Williamsburg , Virginia 23187 , United States
| | - Huw Richards
- College of William and Mary , Department of Chemistry , P.O. Box 8795, Williamsburg , Virginia 23187 , United States
| | - Kristin L Wustholz
- College of William and Mary , Department of Chemistry , P.O. Box 8795, Williamsburg , Virginia 23187 , United States
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17
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Oliveira OVD, Costa GDC, Costa LT. Encapsulation of the Sulfur Compounds by Cucurbit[7]uril: A Quantum Chemistry Study. J Phys Chem B 2018. [PMID: 30452266 DOI: 10.1021/acs.jpcc.8b03206] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/13/2023]
Abstract
Benzothiophene (BT) and dibenzothiophene (DT) are the most important contaminants in the petroleum derivatives responsible for serious environmental and health problems. Therefore, we have investigated the absorption of these compounds for the first time by considering cucurbit[7]uril (CB[7]) as the host molecule and using the theoretical levels of density functional theory//B3LYP-D3/6-31G(d). BT and DT absorbed into CB[7] do not undergo a significant structural change in the CB[7] structure. The energy gap of the S-compounds@CB[7] in water and hexane solvents was approximately 5 eV, and this large value implies that the complexes have high chemical stability. Moreover, the absorption of the BT and DT into CB[7] in the water and hexane solvents is a favorable process, whereas the lowest binding energy was observed between the dibenzothiophene and CB[7] in the DT@CB[7] complex. The solvation enthalpy shows a preferential solvation of the complexes in water than in hexane solvent. This trend is confirmed by the AIM analysis that shows the highest stability for the DT@CB[7] system with the contribution of cooperative hydrogen bonding. The transfer free energy of S-compounds@CB[7] complexes from hexane to water are -66.12 and -59.56 kcal/mol for BT@CB[7] and DT@CB[7], respectively, implying the spontaneous transference of these complexes from hexane to water solvent. Overall, our results show that the cucurbiturils can be a new class of host molecules to be used in the removal of S-compounds from petroleum derivatives. Finally, a schematic flow diagram of the desulfurization process by cucurbiturils was proposed.
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Affiliation(s)
- Osmair Vital de Oliveira
- Instituto Federal de Educação Ciência e Tecnologia de São Paulo, campus Catanduva , CEP: 29106-010 , Catanduva, São Paulo 15808-305 , Brazil
| | - Gabriela de Carvalho Costa
- Instituto de Química, Universidade Federal Fluminense - Outeiro de São João Batista , s/n CEP:24020-141 , Niterói, Rio de Janeiro 24210-000 , Brazil
| | - Luciano T Costa
- Instituto de Química, Universidade Federal Fluminense - Outeiro de São João Batista , s/n CEP:24020-141 , Niterói, Rio de Janeiro 24210-000 , Brazil
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18
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Manceau M, Vezzoli S, Glorieux Q, Giacobino E, Carbone L, De Vittorio M, Hermier JP, Bramati A. CdSe/CdS Dot-in-Rods Nanocrystals Fast Blinking Dynamics. Chemphyschem 2018; 19:3288-3295. [PMID: 30281885 DOI: 10.1002/cphc.201800694] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2018] [Indexed: 11/07/2022]
Abstract
Analyzing the autocorrelation function of the fluorescence intensity, we demonstrate that these nanoemitters are characterized by a short value of the mean duration of bright periods (ten to a few hundreds of microseconds). The comparison of the results obtained for samples with different geometries shows that not only the shell thickness is crucial but also the shape of the dot-in-rods. Increasing the shell aspect ratio results in shorter bright periods suggesting that surface traps impact the stability of the fluorescence intensity.
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Affiliation(s)
- M Manceau
- Laboratoire Kastler Brossel, Sorbonne Université, CNRS, ENS-PSL Research University, Collège de France, 4, place Jussieu Case 74, F-75005, Paris, France
- Université Paris 13, Sorbonne Paris Cité, Laboratoire de Physique des Lasers, F-93430, Villetaneuse, France
| | - S Vezzoli
- The Blackett Laboratory, Department of Physics, Imperial College London, London, SW72AZ, United Kingdom
| | - Q Glorieux
- Laboratoire Kastler Brossel, Sorbonne Université, CNRS, ENS-PSL Research University, Collège de France, 4, place Jussieu Case 74, F-75005, Paris, France
| | - E Giacobino
- Laboratoire Kastler Brossel, Sorbonne Université, CNRS, ENS-PSL Research, University, Collège de France, 4, place Jussieu Case 74, F-75005, Paris, France
| | - L Carbone
- CNR NANOTEC-Institute of Nanotechnology c/o Campus Ecotekne, University of Salento, Via Monteroni -, 73100, Lecce, Italy
| | - M De Vittorio
- Istituto Italiano di Tecnologia (IIT) Center for Bio-Molecular Nanotechnologies Via Barsanti sn, 73010 Arnesano (Lecce), Italy, CNR NANOTEC-Institute of Nanotechnology c/o Campus Ecotekne, University of Salento, Via Monteroni -, 73100, Lecce, Italy
| | - J-P Hermier
- Groupe d'Etude de la Matière Condensée (GEMaC), Université de Versailles Saint-Quentin-en-Yvelines, CNRS UMR 8635, Université Paris-Saclay, 45 Avenue des Etats-Unis, 78035, Versailles Cedex, France
| | - A Bramati
- Laboratoire Kastler Brossel, Sorbonne Université, CNRS, ENS-PSL Research University, Collège de France, 4, place Jussieu Case 74, F-75005, Paris, France
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19
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Pramanik S, Bhandari S, Pan UN, Roy S, Chattopadhyay A. A White Light-Emitting Quantum Dot Complex for Single Particle Level Interaction with Dopamine Leading to Changes in Color and Blinking Profile. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2018; 14:e1800323. [PMID: 29665212 DOI: 10.1002/smll.201800323] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/24/2018] [Revised: 02/19/2018] [Indexed: 06/08/2023]
Abstract
The interaction of the neurotransmitter dopamine is reported with a single particle white light-emitting (WLE) quantum dot complex (QDC). The QDC is composed of yellow emitting ZnO quantum dots (Qdots) and blue emitting Zn(MSA)2 complex (MSA = N-methylsalicylaldimine) synthesized on their surfaces. Sensing is achieved by the combined changes in the visual luminescence color from white to blue, chromaticity color coordinates from (0.31, 0.33) to (0.24, 0.23) and the ratio of the exponents (αon /αoff ) of on/off probability distribution (from 0.24 to 3.21) in the blinking statistics of WLE QDC. The selectivity of dopamine toward ZnO Qdots, present in WLE QDC, helps detect ≈13 dopamine molecules per Qdot. Additionally, the WLE QDC exhibits high sensitivity, with a limit of detection of 3.3 × 10-9 m (in the linear range of 1-100 × 10-9 m) and high selectivity in presence of interfering biological species. Moreover, the single particle on-off bilking statistics based detection strategy may provide an innovative way for ultrasensitive detection of analytes.
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Affiliation(s)
- Sabyasachi Pramanik
- Department of Chemistry, Indian Institute of Technology Guwahati, Guwahati, 781039, Assam, India
| | - Satyapriya Bhandari
- Centre for Nanotechnology, Indian Institute of Technology Guwahati, Guwahati, 781039, Assam, India
| | - Uday Narayan Pan
- Department of Chemistry, Indian Institute of Technology Guwahati, Guwahati, 781039, Assam, India
| | - Shilaj Roy
- Department of Chemistry, Indian Institute of Technology Guwahati, Guwahati, 781039, Assam, India
| | - Arun Chattopadhyay
- Department of Chemistry, Indian Institute of Technology Guwahati, Guwahati, 781039, Assam, India
- Centre for Nanotechnology, Indian Institute of Technology Guwahati, Guwahati, 781039, Assam, India
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20
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Roy D, Mandal S, De CK, Kumar K, Mandal PK. Nearly suppressed photoluminescence blinking of small-sized, blue–green–orange–red emitting single CdSe-based core/gradient alloy shell/shell quantum dots: correlation between truncation time and photoluminescence quantum yield. Phys Chem Chem Phys 2018; 20:10332-10344. [DOI: 10.1039/c8cp00952j] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Nearly suppressed PL blinking of small sized CdSe based CGASS QDs.
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Affiliation(s)
- Debjit Roy
- Department of Chemical Sciences
- Indian Institute of Science Education and Research (IISER) Kolkata
- Mohanpur
- India
| | - Saptarshi Mandal
- Department of Chemical Sciences
- Indian Institute of Science Education and Research (IISER) Kolkata
- Mohanpur
- India
| | - Chayan K. De
- Department of Chemical Sciences
- Indian Institute of Science Education and Research (IISER) Kolkata
- Mohanpur
- India
| | - Kaushalendra Kumar
- Department of Chemical Sciences
- Indian Institute of Science Education and Research (IISER) Kolkata
- Mohanpur
- India
| | - Prasun K. Mandal
- Department of Chemical Sciences
- Indian Institute of Science Education and Research (IISER) Kolkata
- Mohanpur
- India
- Centre for Advanced Functional Materials
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21
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Liu J, Konthasinghe K, Davanco M, Lawall J, Anant V, Verma V, Mirin R, Woo Nam S, Dong Song J, Ma B, Sheng Chen Z, Qiao Ni H, Chuan Niu Z, Srinivasan K. Single self-assembled InAs/GaAs quantum dots in photonic nanostructures: The role of nanofabrication. PHYSICAL REVIEW APPLIED 2018; 9:10.1103/PhysRevApplied.9.064019. [PMID: 30984800 PMCID: PMC6459412 DOI: 10.1103/physrevapplied.9.064019] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Single self-assembled InAs/GaAs quantum dots are a promising solid-state quantum technology, with which vacuum Rabi splitting, single-photon-level nonlinearities, and bright, pure, and indistinguishable single-photon generation having been demonstrated. For such achievements, nanofabrication is used to create structures in which the quantum dot preferentially interacts with strongly-confined optical modes. An open question is the extent to which such nanofabrication may also have an adverse influence, through the creation of traps and surface states that could induce blinking, spectral diffusion, and dephasing. Here, we use photoluminescence imaging to locate the positions of single InAs/GaAs quantum dots with respect to alignment marks with < 5 nm uncertainty, allowing us to measure their behavior before and after fabrication. We track the quantum dot emission linewidth and photon statistics as a function of distance from an etched surface, and find that the linewidth is significantly broadened (up to several GHz) for etched surfaces within a couple hundred nanometers of the quantum dot. However, we do not observe appreciable reduction of the quantum dot radiative efficiency due to blinking. We also show that atomic layer deposition can stabilize spectral diffusion of the quantum dot emission, and partially recover its linewidth.
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Affiliation(s)
- Jin Liu
- Center for Nanoscale Science and Technology, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA
- School of Physics, Sun-Yat Sen University, Guangzhou, 510275, China
- Maryland NanoCenter, University of Maryland, College Park, USA
| | | | - Marcelo Davanco
- Center for Nanoscale Science and Technology, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA
| | - John Lawall
- Physical Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA
| | | | - Varun Verma
- National Institute of Standards and Technology, Boulder, CO 80305, USA
| | - Richard Mirin
- National Institute of Standards and Technology, Boulder, CO 80305, USA
| | - Sae Woo Nam
- National Institute of Standards and Technology, Boulder, CO 80305, USA
| | - Jin Dong Song
- Center for Opto-Electronic Materials and Devices Research, Korea Institute of Science and Technology, Seoul 136-791, South Korea
| | - Ben Ma
- State Key Laboratory for Superlattice and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing, 100083, China
- College of Materials Science and Opto-Electronic Technology, University of Chinese Academy of Sciences
- Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China (Dated: September 27, 2018)
| | - Ze Sheng Chen
- State Key Laboratory for Superlattice and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing, 100083, China
- College of Materials Science and Opto-Electronic Technology, University of Chinese Academy of Sciences
- Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China (Dated: September 27, 2018)
| | - Hai Qiao Ni
- State Key Laboratory for Superlattice and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing, 100083, China
- College of Materials Science and Opto-Electronic Technology, University of Chinese Academy of Sciences
- Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China (Dated: September 27, 2018)
| | - Zhi Chuan Niu
- State Key Laboratory for Superlattice and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing, 100083, China
- College of Materials Science and Opto-Electronic Technology, University of Chinese Academy of Sciences
- Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China (Dated: September 27, 2018)
| | - Kartik Srinivasan
- Center for Nanoscale Science and Technology, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA
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22
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Chen JS, Zang H, Li M, Cotlet M. Hot excitons are responsible for increasing photoluminescence blinking activity in single lead sulfide/cadmium sulfide nanocrystals. Chem Commun (Camb) 2018; 54:495-498. [DOI: 10.1039/c7cc08356d] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The kinetics of PL blinking for isolated PbS/CdS nanocrystals changes with the photon excitation energy, with PL blinking increasing in frequency and changing from a two-state to a multistate on/off switching when the excitation energy changes from 1Sh–1Se (≈1.4 eV) to 1Ph–1Pe (≈2.4 eV).
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Affiliation(s)
- Jia-Shiang Chen
- Center for Functional Nanomaterials
- Brookhaven National Laboratory
- Upton
- USA
- Department of Materials Science and Chemical Engineering
| | - Huidong Zang
- Center for Functional Nanomaterials
- Brookhaven National Laboratory
- Upton
- USA
| | - Mingxing Li
- Center for Functional Nanomaterials
- Brookhaven National Laboratory
- Upton
- USA
| | - Mircea Cotlet
- Center for Functional Nanomaterials
- Brookhaven National Laboratory
- Upton
- USA
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23
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Barbiero M, Castelletto S, Gan X, Gu M. Spin-manipulated nanoscopy for single nitrogen-vacancy center localizations in nanodiamonds. LIGHT, SCIENCE & APPLICATIONS 2017; 6:e17085. [PMID: 30167213 PMCID: PMC6062043 DOI: 10.1038/lsa.2017.85] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/02/2017] [Revised: 05/08/2017] [Accepted: 05/08/2017] [Indexed: 05/12/2023]
Abstract
Due to their exceptional optical and magnetic properties, negatively charged nitrogen-vacancy (NV-) centers in nanodiamonds (NDs) have been identified as an indispensable tool for imaging, sensing and quantum bit manipulation. The investigation of the emission behaviors of single NV- centers at the nanoscale is of paramount importance and underpins their use in applications ranging from quantum computation to super-resolution imaging. Here, we report on a spin-manipulated nanoscopy method for nanoscale resolutions of the collectively blinking NV- centers confined within the diffraction-limited region. Using wide-field localization microscopy combined with nanoscale spin manipulation and the assistance of a microwave source tuned to the optically detected magnetic resonance (ODMR) frequency, we discovered that two collectively blinking NV- centers can be resolved. Furthermore, when the collective emitters possess the same ground state spin transition frequency, the proposed method allows the resolving of each single NV- center via an external magnetic field used to split the resonant dips. In spin manipulation, the three-level blinking dynamics provide the means to resolve two NV- centers separated by distances of 23 nm. The method presented here offers a new platform for studying and imaging spin-related quantum interactions at the nanoscale with super-resolution techniques.
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Affiliation(s)
- Martina Barbiero
- Laboratory of Artificial-Intelligence Nanophotonics, School of Science, RMIT University, Melbourne, Victoria 3001, Australia
| | | | - Xiaosong Gan
- Center for Micro-Photonics, Faculty of Science, Engineering and Technology, Swinburne University of Technology, PO Box 218, Hawthorn, Victoria 3122, Australia
| | - Min Gu
- Laboratory of Artificial-Intelligence Nanophotonics, School of Science, RMIT University, Melbourne, Victoria 3001, Australia
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24
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Zang H, Routh PK, Meng Q, Cotlet M. Electron transfer dynamics from single near infrared emitting lead sulfide-cadmium sulfide nanocrystals to titanium dioxide. NANOSCALE 2017; 9:14664-14671. [PMID: 28937699 DOI: 10.1039/c7nr03500d] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
In this study we report the first successful demonstration of electron transfer between single near infrared emitting PbS/CdS nanocrystals and an external acceptor, titanium dioxide (TiO2). We demonstrate distance-dependent electron transfer from single nanocrystals to TiO2 and explore the effect of this process on the photoluminescence dynamics of these nanocrystals. Isolated PbS/CdS QDs are found to exhibit blinking dynamics similar to other nanocrystals like CdSe/ZnS; however, their photoluminescence follows a quasi two-state pattern with heterogeneous photoluminescence lifetimes which may be the result of their emission originating from different energy states. Electron transfer of these nanocrystals with an external acceptor inhibits their photoluminescence lifetime heterogeneity and biases their blinking dynamics in a manner similar to that observed for visible emitting CdSe/ZnS nanocrystals undergoing electron transfer with external acceptors. While the present study reconfirms the universality of quantum dot blinking among various types of nanocrystals, it also demonstrates that universality remains valid for the communication of various types of nanocrystals with the exterior world, here pictured as electron transfer with external acceptors.
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Affiliation(s)
- Huidong Zang
- Center for Functional Nanomaterials at Brookhaven National Laboratory, Upton, New York 11973, USA.
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25
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Fisher AAE, Osborne MA. Sizing Up Excitons in Core-Shell Quantum Dots via Shell-Dependent Photoluminescence Blinking. ACS NANO 2017; 11:7829-7840. [PMID: 28679040 DOI: 10.1021/acsnano.7b01978] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Semiconductor nanocrystals or quantum dots (QDs) are now widely used across solar cell, display, and bioimaging technologies. While advances in multishell, alloyed, and multinary core-shell QD structures have led to improved light-harvesting and photoluminescence (PL) properties of these nanomaterials, the effects that QD-capping have on the exciton dynamics that govern PL instabilities such as blinking in single-QDs is not well understood. We report experimental measurements of shell-size-dependent absorption and PL intermittency in CdSe-CdS QDs that are consistent with a modified charge-tunnelling, self-trapping (CTST) description of the exciton dynamics in these nanocrystals. By introducing an effective, core-exciton size, which accounts for delocalization of charge carriers across the QD core and shell, we show that the CTST models both the shell-depth-dependent red-shift of the QD band gap and changes in the on/off-state switching statistics that we observe in single-QD PL intensity trajectories. Further analysis of CdSe-ZnS QDs, shows how differences in shell structure and integrity affect the QD band gap and PL blinking within the CTST framework.
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Affiliation(s)
- Aidan A E Fisher
- Department of Chemistry, School of Life Sciences, University of Sussex , Falmer, Brighton BN1 9QJ, United Kingdom
| | - Mark A Osborne
- Department of Chemistry, School of Life Sciences, University of Sussex , Falmer, Brighton BN1 9QJ, United Kingdom
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26
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Chu JW, Yang H. Identifying the structural and kinetic elements in protein large-amplitude conformational motions. INT REV PHYS CHEM 2017. [DOI: 10.1080/0144235x.2017.1283885] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
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27
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Mitsui M, Fukui H, Takahashi R, Takakura Y, Mizukami T. Single-Molecule Fluorescence Spectroscopy of Perylene Diimide Dyes in a γ-Cyclodextrin Film: Manifestation of Photoinduced H-Atom Transfer via Higher Triplet (n, π*) Excited States. J Phys Chem A 2017; 121:1577-1586. [DOI: 10.1021/acs.jpca.6b11353] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Masaaki Mitsui
- Department
of Chemistry, College of Science, Rikkyo University, 3-34-1, Nishiikebukuro, Toshima-ku, Tokyo 171-8501, Japan
| | - Hiroki Fukui
- Department
of Chemistry, Faculty of Science, Shizuoka University, 836 Ohya, Suruga-ku, Shizuoka 422-8529, Japan
| | - Ryoya Takahashi
- Department
of Chemistry, Faculty of Science, Shizuoka University, 836 Ohya, Suruga-ku, Shizuoka 422-8529, Japan
| | - Yasushi Takakura
- Department
of Chemistry, College of Science, Rikkyo University, 3-34-1, Nishiikebukuro, Toshima-ku, Tokyo 171-8501, Japan
| | - Toshinari Mizukami
- Department
of Chemistry, College of Science, Rikkyo University, 3-34-1, Nishiikebukuro, Toshima-ku, Tokyo 171-8501, Japan
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28
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Sarkar SK, Mukherjee S, Garai A, Thilagar P. A Complementary Aggregation Induced Emission Pair for Generating White Light and Four-Colour (RGB and Near-IR) Cell Imaging. CHEMPHOTOCHEM 2017. [DOI: 10.1002/cptc.201600032] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Samir Kumar Sarkar
- Department of Inorganic and Physical Chemistry; Indian Institute of Science; Bangalore 560012 India
| | - Sanjoy Mukherjee
- Department of Inorganic and Physical Chemistry; Indian Institute of Science; Bangalore 560012 India
| | - Aditya Garai
- Department of Inorganic and Physical Chemistry; Indian Institute of Science; Bangalore 560012 India
| | - Pakkirisamy Thilagar
- Department of Inorganic and Physical Chemistry; Indian Institute of Science; Bangalore 560012 India
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29
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Kennes K, Dedecker P, Hutchison JA, Fron E, Uji-i H, Hofkens J, Van der Auweraer M. Field-Controlled Charge Separation in a Conductive Matrix at the Single-Molecule Level: Toward Controlling Single-Molecule Fluorescence Intermittency. ACS OMEGA 2016; 1:1383-1392. [PMID: 30023508 PMCID: PMC6044678 DOI: 10.1021/acsomega.6b00207] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/25/2016] [Accepted: 11/09/2016] [Indexed: 06/07/2023]
Abstract
The fluorescence intermittency or "blinking" of single molecules of ATTO647N (ATTO) in the conductive matrix polyvinylcarbazole (PVK) is described in the presence of an external applied electric field. It is shown that due to the energy distribution of the highest occupied molecular orbital (HOMO) level of PVK, which is energetically close to the HOMO of ATTO, sporadic electron transfer occurs. As a result, the on/off dynamics of blinking can be influenced by the electric field. This field will, depending on the respective position and orientation of the dye/polymer system with respect to those of the electrodes, either enhance or suppress electron transfer from PVK to ATTO as well as the back electron transfer from reduced ATTO to PVK. After the charge-transfer step, the applied field will pull the hole in PVK away from the dye, increasing the overall time the dye resides in a dark state.
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Affiliation(s)
- Koen Kennes
- Molecular
Imaging and Photonics, Department of Chemistry, Katholieke Universiteit Leuven, Celestijnenlaan 200F, Leuven 3001, Belgium
| | - Peter Dedecker
- Molecular
Imaging and Photonics, Department of Chemistry, Katholieke Universiteit Leuven, Celestijnenlaan 200F, Leuven 3001, Belgium
| | - James A. Hutchison
- ISIS
& icFRC, University of Strasbourg and
CNRS UMR 7006, 8 allée
Gaspard Monge, Strasbourg 67000, France
- School
of Chemistry and Bio21 Institute, University
of Melbourne, Melbourne, Victoria 3010, Australia
| | - Eduard Fron
- Molecular
Imaging and Photonics, Department of Chemistry, Katholieke Universiteit Leuven, Celestijnenlaan 200F, Leuven 3001, Belgium
| | - Hiroshi Uji-i
- Molecular
Imaging and Photonics, Department of Chemistry, Katholieke Universiteit Leuven, Celestijnenlaan 200F, Leuven 3001, Belgium
- RIES, Hokkaido
University, N20W10, Kita-Ward, Sapporo 001-0020, Japan
| | - Johan Hofkens
- Molecular
Imaging and Photonics, Department of Chemistry, Katholieke Universiteit Leuven, Celestijnenlaan 200F, Leuven 3001, Belgium
- RIES, Hokkaido
University, N20W10, Kita-Ward, Sapporo 001-0020, Japan
| | - Mark Van der Auweraer
- Molecular
Imaging and Photonics, Department of Chemistry, Katholieke Universiteit Leuven, Celestijnenlaan 200F, Leuven 3001, Belgium
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30
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Boutelle RC, Neuhauser D, Weiss S. Far-Field Super-resolution Detection of Plasmonic Near-Fields. ACS NANO 2016; 10:7955-7962. [PMID: 27501216 DOI: 10.1021/acsnano.6b03873] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
We demonstrate a far-field single molecule super-resolution method that maps plasmonic near-fields. The method is largely invariant to fluorescence quenching (arising from probe proximity to a metal), has reduced point-spread-function distortion compared to fluorescent dyes (arising from strong coupling to nanoscopic metallic features), and has a large dynamic range (of 2 orders of magnitude) allowing mapping of plasmonic field-enhancements regions. The method takes advantage of the sensitivity of quantum dot (QD) stochastic blinking to plasmonic near-fields. The modulation of the blinking characteristics thus provides an indirect measure of the local field strength. Since QD blinking can be monitored in the far-field, the method can measure localized plasmonic near-fields at high throughput using a simple far-field optical setup. Using this method, propagation lengths and penetration depths were mapped-out for silver nanowires of different diameters and for different dielectric environments, with a spatial accuracy of ∼15 nm. We initially use sparse sampling to ensure single molecule localization for accurate characterization of the plasmonic near-field with plans to increase density of emitters in further studies. The measured propagation lengths and penetration depths values agree well with Maxwell finite-difference time-domain calculations and with published literature values. This method offers advantages such as low cost, high throughput, and superresolved mapping of localized plasmonic fields at high sensitivity and fidelity.
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Affiliation(s)
| | | | - Shimon Weiss
- Department of Physics, Bar Ilan University , Ramat Gan, 52900, Israel
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31
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Woodall DL, Tobias AK, Jones M. Resolving carrier recombination in CdS quantum dots: A time-resolved fluorescence study. Chem Phys 2016. [DOI: 10.1016/j.chemphys.2015.10.011] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
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32
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Osborne MA, Fisher AAE. Charge-tunnelling and self-trapping: common origins for blinking, grey-state emission and photoluminescence enhancement in semiconductor quantum dots. NANOSCALE 2016; 8:9272-9283. [PMID: 27088542 DOI: 10.1039/c6nr00529b] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Understanding instabilities in the photoluminescence (PL) from light emitting materials is crucial to optimizing their performance for different applications. Semiconductor quantum dots (QDs) offer bright, size tunable emission, properties that are now being exploited in a broad range of developing technologies from displays and solar cells to biomaging and optical storage. However, instabilities such as photoluminescence intermittency, enhancement and bleaching of emission in these materials can be detrimental to their utility. Here, we report dielectric dependent blinking, intensity-"spikes" and low-level, "grey"-state emission, as well as PL enhancement in ZnS capped CdSe QDs; observations that we found consistent with a charge-tunnelling and self-trapping (CTST) description of exciton-dynamics on the QD-host system. In particular, modulation of PL in grey-states and PL enhancement are found to have a common origin in the equilibrium between exciton charge carrier core and surface-states within the CTST framework. Parameterized in terms of size and electrostatic properties of the QD and its nanoenvironment, the CTST offers predictive insight into exciton-dynamics in these nanomaterials.
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Affiliation(s)
- M A Osborne
- Department of Chemistry, School of Life Sciences, University of Sussex, Falmer, Brighton, BN1 9QJ, UK.
| | - A A E Fisher
- Department of Chemistry, School of Life Sciences, University of Sussex, Falmer, Brighton, BN1 9QJ, UK.
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33
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Zang H, Routh PK, Huang Y, Chen JS, Sutter E, Sutter P, Cotlet M. Nonradiative Energy Transfer from Individual CdSe/ZnS Quantum Dots to Single-Layer and Few-Layer Tin Disulfide. ACS NANO 2016; 10:4790-4796. [PMID: 27031885 DOI: 10.1021/acsnano.6b01538] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The combination of zero-dimensional (0D) colloidal CdSe/ZnS quantum dots with tin disulfide (SnS2), a two-dimensional (2D)-layered metal dichalcogenide, results in 0D-2D hybrids with enhanced light absorption properties. These 0D-2D hybrids, when exposed to light, exhibit intrahybrid nonradiative energy transfer from photoexcited CdSe/ZnS quantum dots to SnS2. Using single nanocrystal spectroscopy, we find that the rate for energy transfer in 0D-2D hybrids increases with added number of SnS2 layers, a positive manifestation toward the potential functionality of such 2D-based hybrids in applications such as photovoltaics and photon sensing.
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Affiliation(s)
- Huidong Zang
- Center for Functional Nanomaterials, Brookhaven National Laboratory , Upton, New York 11973, United States
| | - Prahlad K Routh
- Center for Functional Nanomaterials, Brookhaven National Laboratory , Upton, New York 11973, United States
- Materials Science Department, Stony Brook University , Stony Brook, New York 11794, United States
| | - Yuan Huang
- Center for Functional Nanomaterials, Brookhaven National Laboratory , Upton, New York 11973, United States
| | - Jia-Shiang Chen
- Center for Functional Nanomaterials, Brookhaven National Laboratory , Upton, New York 11973, United States
- Materials Science Department, Stony Brook University , Stony Brook, New York 11794, United States
| | | | | | - Mircea Cotlet
- Center for Functional Nanomaterials, Brookhaven National Laboratory , Upton, New York 11973, United States
- Materials Science Department, Stony Brook University , Stony Brook, New York 11794, United States
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34
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Bajwa P, Gao F, Nguyen A, Omogo B, Heyes CD. Influence of the Inner-Shell Architecture on Quantum Yield and Blinking Dynamics in Core/Multishell Quantum Dots. Chemphyschem 2016; 17:731-40. [PMID: 26693950 PMCID: PMC5086001 DOI: 10.1002/cphc.201500868] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2015] [Revised: 11/16/2015] [Indexed: 11/11/2022]
Abstract
Choosing the composition of a shell for QDs is not trivial, as both the band-edge energy offset and interfacial lattice mismatch influence the final optical properties. One way to balance these competing effects is by forming multishells and/or gradient-alloy shells. However, this introduces multiple interfaces, and their relative effects on quantum yield and blinking are not yet fully understood. Here, we undertake a systematic, comparative study of the addition of inner shells of a single component versus gradient-alloy shells of cadmium/zinc chalogenides onto CdSe cores, and then capping with a thin ZnS outer shell to form various core/multishell configurations. We show that architecture of the inner shell between the CdSe core and the outer ZnS shell significantly influences both the quantum yield and blinking dynamics, but that these effects are not correlated-a high ensemble quantum yield doesn't necessarily equate to reduced blinking. Two mathematical models have been proposed to describe the blinking dynamics-the more common power-law model and a more recent multiexponential model. By binning the same data with 1 and 20 ms resolution, we show that the on times can be better described by the multiexponential model, whereas the off times can be better described by the power-law model. We discuss physical mechanisms that might explain this behavior and how it can be affected by the inner-shell architecture.
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Affiliation(s)
- Pooja Bajwa
- Department of Chemistry and Biochemistry, University of Arkansas, 345 N. Campus Drive, Fayetteville, AR, 72701, USA
| | - Feng Gao
- Department of Chemistry and Biochemistry, University of Arkansas, 345 N. Campus Drive, Fayetteville, AR, 72701, USA
| | - Anh Nguyen
- Department of Chemistry and Biochemistry, University of Arkansas, 345 N. Campus Drive, Fayetteville, AR, 72701, USA
| | - Benard Omogo
- Department of Chemistry and Biochemistry, University of Arkansas, 345 N. Campus Drive, Fayetteville, AR, 72701, USA
| | - Colin D Heyes
- Department of Chemistry and Biochemistry, University of Arkansas, 345 N. Campus Drive, Fayetteville, AR, 72701, USA
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35
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Hartmann NF, Yalcin SE, Adamska L, Hároz EH, Ma X, Tretiak S, Htoon H, Doorn SK. Photoluminescence imaging of solitary dopant sites in covalently doped single-wall carbon nanotubes. NANOSCALE 2015; 7:20521-20530. [PMID: 26586162 DOI: 10.1039/c5nr06343d] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Covalent dopants in semiconducting single wall carbon nanotubes (SWCNTs) are becoming important as routes for introducing new photoluminescent emitting states with potential for enhanced quantum yields, new functionality, and as species capable of near-IR room-temperature single photon emission. The origin and behavior of the dopant-induced emission is thus important to understand as a key requirement for successful room-T photonics and optoelectronics applications. Here, we use direct correlated two-color photoluminescence imaging to probe how the interplay between the SWCNT bright E(11) exciton and solitary dopant sites yields the dopant-induced emission for three different dopant species: oxygen, 4-methoxybenzene, and 4-bromobenzene. We introduce a route to control dopant functionalization to a low level as a means for introducing spatially well-separated solitary dopant sites. Resolution of emission from solitary dopant sites and correlation to their impact on E(11) emission allows confirmation of dopants as trapping sites for localization of E(11) excitons following their diffusive transport to the dopant site. Imaging of the dopant emission also reveals photoluminescence intermittency (blinking), with blinking dynamics being dependent on the specific dopant. Density functional theory calculations were performed to evaluate the stability of dopants and delineate the possible mechanisms of blinking. Theoretical modeling suggests that the trapping of free charges in the potential well created by permanent dipoles introduced by dopant atoms/groups is likely responsible for the blinking, with the strongest effects being predicted and observed for oxygen-doped SWCNTs.
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Affiliation(s)
- Nicolai F Hartmann
- Center for Integrated Nanotechnologies, Materials Physics and Applications Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.
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36
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Ackerman PJ, Mundoor H, Smalyukh II, van de Lagemaat J. Plasmon-Exciton Interactions Probed Using Spatial Coentrapment of Nanoparticles by Topological Singularities. ACS NANO 2015; 9:12392-400. [PMID: 26567626 DOI: 10.1021/acsnano.5b05715] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
We study plasmon-exciton interaction by using topological singularities to spatially confine, selectively deliver, cotrap and optically probe colloidal semiconductor and plasmonic nanoparticles. The interaction is monitored in a single quantum system in the bulk of a liquid crystal medium where nanoparticles are manipulated and nanoconfined far from dielectric interfaces using laser tweezers and topological configurations containing singularities. When quantum dot-in-a-rod particles are spatially colocated with a plasmonic gold nanoburst particle in a topological singularity core, its fluorescence increases because blinking is significantly suppressed and the radiative decay rate increases by nearly an order of magnitude owing to the Purcell effect. We argue that the blinking suppression is the result of the radiative rate change that mitigates Auger recombination and quantum dot ionization, consequently reducing nonradiative recombination. Our work demonstrates that topological singularities are an effective platform for studying and controlling plasmon-exciton interactions.
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Affiliation(s)
- Paul J Ackerman
- Department of Physics, University of Colorado , Boulder, Colorado 80309, United States
- Department of Electrical, Computer and Energy Engineering, University of Colorado , Boulder, Colorado 80309, United States
| | - Haridas Mundoor
- Department of Physics, University of Colorado , Boulder, Colorado 80309, United States
| | - Ivan I Smalyukh
- Department of Physics, University of Colorado , Boulder, Colorado 80309, United States
- Department of Electrical, Computer and Energy Engineering, University of Colorado , Boulder, Colorado 80309, United States
- Liquid Crystal Materials Research Center and Materials Science and Engineering Program, University of Colorado , Boulder, Colorado 80309, United States
- Renewable and Sustainable Energy Institute, National Renewable Energy Laboratory and University of Colorado , Boulder, Colorado 80309, United States
| | - Jao van de Lagemaat
- Department of Physics, University of Colorado , Boulder, Colorado 80309, United States
- National Renewable Energy Laboratory , Golden, Colorado 80401, United States
- Renewable and Sustainable Energy Institute, National Renewable Energy Laboratory and University of Colorado , Boulder, Colorado 80309, United States
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37
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ATP hydrolysis assists phosphate release and promotes reaction ordering in F1-ATPase. Nat Commun 2015; 6:10223. [PMID: 26678797 PMCID: PMC4703894 DOI: 10.1038/ncomms10223] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2015] [Accepted: 11/16/2015] [Indexed: 12/28/2022] Open
Abstract
F1-ATPase (F1) is a rotary motor protein that can efficiently convert chemical energy to mechanical work of rotation via fine coordination of its conformational motions and reaction sequences. Compared with reactant binding and product release, the ATP hydrolysis has relatively little contributions to the torque and chemical energy generation. To scrutinize possible roles of ATP hydrolysis, we investigate the detailed statistics of the catalytic dwells from high-speed single wild-type F1 observations. Here we report a small rotation during the catalytic dwell triggered by the ATP hydrolysis that is indiscernible in previous studies. Moreover, we find in freely rotating F1 that ATP hydrolysis is followed by the release of inorganic phosphate with low synthesis rates. Finally, we propose functional roles of the ATP hydrolysis as a key to kinetically unlock the subsequent phosphate release and promote the correct reaction ordering.
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38
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Early KT, Nesbitt DJ. Ultrafast Laser Studies of Two-Photon Excited Fluorescence Intermittency in Single CdSe/ZnS Quantum Dots. NANO LETTERS 2015; 15:7781-7787. [PMID: 26542640 DOI: 10.1021/acs.nanolett.5b01139] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Two-photon fluorescence microscopy of single quantum dots conditions has been reported by several groups, with contrasting observations regarding the kinetics and dynamics of fluorescence intermittency or "blinking". Here, we investigate the power dependence, kinetics, and statistics of two photon-excited fluorescence intermittency from single CdSe/ZnS quantum dots in a solid PMMA film as a function of sub-bandgap laser intensity at 800 nm. Fluorescence intermittency is observed at all excitation powers and a quadratic (n = 1.97(3)) dependence of the shot noise-limited fluorescence intensity on the incident laser power is verified, confirming essentially zero background contribution from one-photon excitation processes. Such analyses permit two photon absorption cross sections for single quantum dots to be extracted quantitatively from the data, which reveal good agreement with those obtained from previous two-photon FCS measurements. Strictly inverse power law-distributed off-state dwell times are observed for all excitation powers, with a mean power law exponent ⟨m(off)⟩ = 1.65(4) in excellent agreement with the behavior observed under one-photon excitation conditions. Finally, a superquadratic (n = 2.3(2)) rather than quartic (n = 4) power dependence is observed for the on-state blinking dwell times, which we kinetically analyze and interpret in terms of a novel 2 + 1 "hot" exciton ionization/blinking mechanism due to partially saturated 1-photon sub-bandgap excitation out of the two-photon single exciton state. The kinetic results are consistent with quantum dot photoionization quantum yields from "hot" exciton states (4(1) × 10(-6)) comparable with experimental estimates (10(-6)-10(-5)) of Auger ionization efficiencies out of the biexcitonic state.
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Affiliation(s)
- Kevin T Early
- Joint Institute for Lab Astrophysics, National Institute of Standards and Technology and University of Colorado, Boulder, Colorado 80309, United States
- Department of Chemistry and Biochemistry, University of Colorado Boulder, Colorado 80309, United States
| | - David J Nesbitt
- Joint Institute for Lab Astrophysics, National Institute of Standards and Technology and University of Colorado, Boulder, Colorado 80309, United States
- Department of Chemistry and Biochemistry, University of Colorado Boulder, Colorado 80309, United States
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39
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Zhang J, Chen R, Zhu Z, Adachi C, Zhang X, Lee CS. Highly Stable Near-Infrared Fluorescent Organic Nanoparticles with a Large Stokes Shift for Noninvasive Long-Term Cellular Imaging. ACS APPLIED MATERIALS & INTERFACES 2015; 7:26266-26274. [PMID: 26558487 DOI: 10.1021/acsami.5b08539] [Citation(s) in RCA: 84] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Fluorescent organic nanoparticles based on small molecules have been regarded as promising candidates for bioimaging in recent years. In this study, we report a highly stable near-infrared (NIR) fluorescent organic nanoprobes based on nanoparticles of an anthraquinone derivate with strong aggregation-induced emission (AIE) characteristics and a large Stokes shift (>175 nm). These endow the nanoprobe with high fluorescent brightness and high signal-to-noise ratio. On the other hand, the nanoprobe also shows low cytotoxicity, good stability over a wide pH range, superior resistance against photodegradation and photobleaching comparing to typical commercial fluorescent organic dyes such as fluorescein sodium. Endowed with such merits in term of optical performance, biocompatibility, and stability, the nanoprobe is demonstrated to be an ideal fluorescent probe for noninvasive long-term cellular tracing and imaging applications. As an example, it is shown that strong red fluorescence from the nanoprobe can still be clearly observed in A549 human lung cancer cells after incubation for six generations over 15 days.
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Affiliation(s)
- Jinfeng Zhang
- Center of Super-Diamond and Advanced Films (COSDAF) & Department of Physics and Materials Science, City University of Hong Kong , 83 Tat Chee Avenue, Kowloon, Hong Kong SAR, P. R. China
| | - Rui Chen
- Center of Super-Diamond and Advanced Films (COSDAF) & Department of Physics and Materials Science, City University of Hong Kong , 83 Tat Chee Avenue, Kowloon, Hong Kong SAR, P. R. China
| | - Zelin Zhu
- Center of Super-Diamond and Advanced Films (COSDAF) & Department of Physics and Materials Science, City University of Hong Kong , 83 Tat Chee Avenue, Kowloon, Hong Kong SAR, P. R. China
| | - Chihaya Adachi
- Center for Organic Photonics and Electronics Research (OPERA), Kyushu University , 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan
| | - Xiaohong Zhang
- Functional Nano & Soft Materials Laboratory (FUNSOM) and Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices, Soochow University , Suzhou, P. R. China
| | - Chun-Sing Lee
- Center of Super-Diamond and Advanced Films (COSDAF) & Department of Physics and Materials Science, City University of Hong Kong , 83 Tat Chee Avenue, Kowloon, Hong Kong SAR, P. R. China
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40
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Miller JB, Dandu N, Velizhanin KA, Anthony RJ, Kortshagen UR, Kroll DM, Kilina S, Hobbie EK. Enhanced Luminescent Stability through Particle Interactions in Silicon Nanocrystal Aggregates. ACS NANO 2015; 9:9772-9782. [PMID: 26348831 DOI: 10.1021/acsnano.5b02676] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Close-packed assemblies of ligand-passivated colloidal nanocrystals can exhibit enhanced photoluminescent stability, but the origin of this effect is unclear. Here, we use experiment, simulation, and ab initio computation to examine the influence of interparticle interactions on the photoluminescent stability of silicon nanocrystal aggregates. The time-dependent photoluminescence emitted by structures ranging in size from a single quantum dot to agglomerates of more than a thousand is compared with Monte Carlo simulations of noninteracting ensembles using measured single-particle blinking data as input. In contrast to the behavior typically exhibited by the metal chalcogenides, the measured photoluminescent stability shows an enhancement with respect to the noninteracting scenario with increasing aggregate size. We model this behavior using time-dependent density functional theory calculations of energy transfer between neighboring nanocrystals as a function of nanocrystal size, separation, and the presence of charge and/or surface-passivation defects. Our results suggest that rapid exciton transfer from "bright" nanocrystals to surface trap states in nearest-neighbors can efficiently fill such traps and enhance the stability of emission by promoting the radiative recombination of slowly diffusing excited electrons.
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Affiliation(s)
- Joseph B Miller
- North Dakota State University , Fargo, North Dakota 58108, United States
| | - Naveen Dandu
- North Dakota State University , Fargo, North Dakota 58108, United States
| | - Kirill A Velizhanin
- Theoretical Division, Los Alamos National Laboratory , Los Alamos, New Mexico 87545, United States
| | - Rebecca J Anthony
- University of Minnesota , Minneapolis, Minnesota 55455, United States
| | - Uwe R Kortshagen
- University of Minnesota , Minneapolis, Minnesota 55455, United States
| | - Daniel M Kroll
- North Dakota State University , Fargo, North Dakota 58108, United States
| | - Svetlana Kilina
- North Dakota State University , Fargo, North Dakota 58108, United States
| | - Erik K Hobbie
- North Dakota State University , Fargo, North Dakota 58108, United States
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41
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Schörner M, Beyer SR, Southall J, Cogdell RJ, Köhler J. Multi-Level, Multi Time-Scale Fluorescence Intermittency of Photosynthetic LH2 Complexes: A Precursor of Non-Photochemical Quenching? J Phys Chem B 2015; 119:13958-63. [PMID: 26419118 DOI: 10.1021/acs.jpcb.5b06979] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The light harvesting complex LH2 is a chromoprotein that is an ideal system for studying protein dynamics via the spectral fluctuations of the emission of its intrinsic chromophores. We have immobilized these complexes in a polymer film and studied the fluctuations of the fluorescence intensity from individual complexes over 9 orders of magnitude in time. Combining time-tagged detection of single photons with a change-point analysis has allowed the unambigeous identification of the various intensity levels due to the huge statistical basis of the data set. We propose that the observed intensity level fluctuations reflect conformational changes of the protein backbone that might be a precursor of the mechanism from which nonphotochemical quenching of higher plants has evolved.
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Affiliation(s)
- Mario Schörner
- Experimental Physics IV and Bayreuth Institute for Macromolecular Research (BIMF), University of Bayreuth , 95447 Bayreuth, Germany
| | - Sebastian Reinhardt Beyer
- Experimental Physics IV and Bayreuth Institute for Macromolecular Research (BIMF), University of Bayreuth , 95447 Bayreuth, Germany
| | - June Southall
- Institute of Molecular, Cell & Systems Biology, College of Medical Veterinary and Life Sciences, University of Glasgow , Glasgow G12 8QQ, United Kingdom
| | - Richard J Cogdell
- Institute of Molecular, Cell & Systems Biology, College of Medical Veterinary and Life Sciences, University of Glasgow , Glasgow G12 8QQ, United Kingdom
| | - Jürgen Köhler
- Experimental Physics IV and Bayreuth Institute for Macromolecular Research (BIMF), University of Bayreuth , 95447 Bayreuth, Germany
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42
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Zbydniewska E, Duzynska A, Popoff M, Hourlier D, Lenfant S, Judek J, Zdrojek M, Mélin T. Charge Blinking Statistics of Semiconductor Nanocrystals Revealed by Carbon Nanotube Single Charge Sensors. NANO LETTERS 2015; 15:6349-6356. [PMID: 26418364 DOI: 10.1021/acs.nanolett.5b01338] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
We demonstrate the relation between the optical blinking of colloidal semiconductor nanocrystals (NCs) and their electrical charge blinking for which we provide the first experimental observation of power-law statistics. To show this, we harness the performance of CdSe/ZnS NCs coupled with carbon nanotube field-effect transistors (CNTFETs), which act as single charge-sensitive electrometers with submillisecond time resolution, at room temperature. A random telegraph signal (RTS) associated with the NC single-trap charging is observed and exhibits power-law temporal statistics (τ(-α), with α in the range of ∼1-3), and a Lorentzian current noise power spectrum with a well-defined 1/f(2) corner. The spectroscopic analysis of the NC-CNTFET devices is consistent with the charging of NC defect states with a charging energy of Ec ≥ 200 meV. These results pave the way for a deeper understanding of the physics and technology of nanocrystal-based optoelectronic devices.
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Affiliation(s)
- Ewa Zbydniewska
- Institute of Electronics Microelectronics and Nanotechnology, IEMN-CNRS UMR 8520 , Avenue Poincaré CS60069, 59652 Villeneuve d'Ascq France
- Faculty of Physics, Warsaw University of Technology , Koszykowa 75, 00-662 Warsaw, Poland
| | - Anna Duzynska
- Faculty of Physics, Warsaw University of Technology , Koszykowa 75, 00-662 Warsaw, Poland
| | - Michka Popoff
- Institute of Electronics Microelectronics and Nanotechnology, IEMN-CNRS UMR 8520 , Avenue Poincaré CS60069, 59652 Villeneuve d'Ascq France
- Lille Centre for Infection and Immunity, Cellular Microbiology of Infectious Pathogens, CNRS UMR8204, INSERM U1019, University of Lille Nord-de-France, Institut Pasteur de Lille , F-59019 Lille, France
| | - Djamila Hourlier
- Institute of Electronics Microelectronics and Nanotechnology, IEMN-CNRS UMR 8520 , Avenue Poincaré CS60069, 59652 Villeneuve d'Ascq France
| | - Stéphane Lenfant
- Institute of Electronics Microelectronics and Nanotechnology, IEMN-CNRS UMR 8520 , Avenue Poincaré CS60069, 59652 Villeneuve d'Ascq France
| | - Jaroslaw Judek
- Faculty of Physics, Warsaw University of Technology , Koszykowa 75, 00-662 Warsaw, Poland
| | - Mariusz Zdrojek
- Faculty of Physics, Warsaw University of Technology , Koszykowa 75, 00-662 Warsaw, Poland
| | - Thierry Mélin
- Institute of Electronics Microelectronics and Nanotechnology, IEMN-CNRS UMR 8520 , Avenue Poincaré CS60069, 59652 Villeneuve d'Ascq France
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Zang H, Cristea M, Shen X, Liu M, Camino F, Cotlet M. Charge trapping and de-trapping in isolated CdSe/ZnS nanocrystals under an external electric field: indirect evidence for a permanent dipole moment. NANOSCALE 2015; 7:14897-14905. [PMID: 26293119 DOI: 10.1039/c5nr03714j] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Single nanoparticle studies of charge trapping and de-trapping in core/shell CdSe/ZnS nanocrystals incorporated into an insulating matrix and subjected to an external electric field demonstrate the ability to reversibly modulate the exciton dynamics and photoluminescence blinking while providing indirect evidence for the existence of a permanent ground state dipole moment in such nanocrystals. A model assuming the presence of energetically deep charge traps physically aligned along the direction of the permanent dipole is proposed in order to explain the dynamics of nanocrystal blinking in the presence of a permanent dipole moment.
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Affiliation(s)
- Huidong Zang
- Center for Functional Nanomaterials, Brookhaven National Laboratory, Upton, NY 11973, USA.
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44
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Si J, Volkán-Kacsó S, Eltom A, Morozov Y, McDonald MP, Kuno M, Jankó B. Heterogeneous Fluorescence Intermittency in Single Layer Reduced Graphene Oxide. NANO LETTERS 2015; 15:4317-4321. [PMID: 26057349 DOI: 10.1021/acs.nanolett.5b00191] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We provide, for the first time, direct experimental evidence for heterogeneous blinking in reduced graphene oxide (rGO) during photolysis. The spatially resolved intermittency originates from regions within individual rGO sheets and shows 1/f-like power spectral density. We describe the evolution of rGO blinking using the multiple recombination center (MRC) model that captures common features of nanoscale blinking. Our results illustrate the universal nature of blinking and suggest a common microscopic origin for the effect.
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Affiliation(s)
- Jixin Si
- †Department of Physics, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - Sándor Volkán-Kacsó
- §Noyes Laboratory of Chemical Physics, California Institute of Technology, 1200 East California Boulevard, Pasadena, California 91125, United States
| | - Ahmed Eltom
- ‡Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - Yurii Morozov
- ‡Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - Matthew P McDonald
- ‡Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - Masaru Kuno
- ‡Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - Boldizsár Jankó
- †Department of Physics, University of Notre Dame, Notre Dame, Indiana 46556, United States
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45
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Volkán-Kacsó S. Two-state theory of binned photon statistics for a large class of waiting time distributions and its application to quantum dot blinking. J Chem Phys 2015; 140:224110. [PMID: 24929377 DOI: 10.1063/1.4881460] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
A theoretical method is proposed for the calculation of the photon counting probability distribution during a bin time. Two-state fluorescence and steady excitation are assumed. A key feature is a kinetic scheme that allows for an extensive class of stochastic waiting time distribution functions, including power laws, expanded as a sum of weighted decaying exponentials. The solution is analytic in certain conditions, and an exact and simple expression is found for the integral contribution of "bright" and "dark" states. As an application for power law kinetics, theoretical results are compared with experimental intensity histograms from a number of blinking CdSe/ZnS quantum dots. The histograms are consistent with distributions of intensity states around a "bright" and a "dark" maximum. A gap of states is also revealed in the more-or-less flat inter-peak region. The slope and to some extent the flatness of the inter-peak feature are found to be sensitive to the power-law exponents. Possible models consistent with these findings are discussed, such as the combination of multiple charging and fluctuating non-radiative channels or the multiple recombination center model. A fitting of the latter to experiment provides constraints on the interaction parameter between the recombination centers. Further extensions and applications of the photon counting theory are also discussed.
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Affiliation(s)
- Sándor Volkán-Kacsó
- Noyes Laboratory of Chemical Physics, California Institute of Technology, 1200 East California Boulevard, Pasadena, California 91125, USA
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46
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Abstract
Luminescence blinking is an inherent feature of optical emission from individual fluorescent molecules and quantum dots. There have been intense efforts, although not with complete resolution, toward the understanding of the mechanistic origin of blinking and also its mitigation in quantum dots. As an advance in our microscopic view of blinking, we show that the luminescence blinking of a quantum dot becomes unusually heavy in the temporal vicinity of a reactive transformation. This stage of heavy blinking is a result of defects/dopants formed within the quantum dot on its path to conversion. The evolution of blinking behavior along the reaction path allows us to measure the lifetime of the critical dopant-related intermediate in the reaction. This work establishes luminescence blinking as a single-nanocrystal level probe of catalytic, photocatalytic, and electrochemical events occurring in the solid-state or on semiconductor surfaces.
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Affiliation(s)
- Aaron L Routzahn
- †Department of Chemistry, ‡Department of Physics, and §Materials Research Lab, University of Illinois, Urbana-Champaign, Illinois 61801, United States
| | - Prashant K Jain
- †Department of Chemistry, ‡Department of Physics, and §Materials Research Lab, University of Illinois, Urbana-Champaign, Illinois 61801, United States
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47
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Houel J, Doan QT, Cajgfinger T, Ledoux G, Amans D, Aubret A, Dominjon A, Ferriol S, Barbier R, Nasilowski M, Lhuillier E, Dubertret B, Dujardin C, Kulzer F. Autocorrelation analysis for the unbiased determination of power-law exponents in single-quantum-dot blinking. ACS NANO 2015; 9:886-893. [PMID: 25549009 DOI: 10.1021/nn506598t] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We present an unbiased and robust analysis method for power-law blinking statistics in the photoluminescence of single nanoemitters, allowing us to extract both the bright- and dark-state power-law exponents from the emitters' intensity autocorrelation functions. As opposed to the widely used threshold method, our technique therefore does not require discriminating the emission levels of bright and dark states in the experimental intensity timetraces. We rely on the simultaneous recording of 450 emission timetraces of single CdSe/CdS core/shell quantum dots at a frame rate of 250 Hz with single photon sensitivity. Under these conditions, our approach can determine ON and OFF power-law exponents with a precision of 3% from a comparison to numerical simulations, even for shot-noise-dominated emission signals with an average intensity below 1 photon per frame and per quantum dot. These capabilities pave the way for the unbiased, threshold-free determination of blinking power-law exponents at the microsecond time scale.
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Affiliation(s)
- Julien Houel
- Institut Lumière-Matière, CNRS UMR5306, Université Lyon 1, Université de Lyon , 69622 Villeurbanne CEDEX, France
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48
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Smyder JA, Amori AR, Odoi MY, Stern HA, Peterson JJ, Krauss TD. The influence of continuous vs. pulsed laser excitation on single quantum dot photophysics. Phys Chem Chem Phys 2014; 16:25723-8. [PMID: 24950616 DOI: 10.1039/c4cp01395f] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The impact of pulsed versus continuous wave (cw) laser excitation on the photophysical properties of single quantum dots (QDs) has been investigated in an experiment in which all macroscopic variables are identical except the nature of laser excitation. Pulsed excitation exaggerates the effects of photobleaching, results in a lower probability of long ON fluorescence blinking events, and leads to shorter fluorescence lifetimes with respect to cw excitation at the same wavelength and average intensity. Spectral wandering, biexciton quantum yields, and power law exponents that describe fluorescence blinking are largely insensitive to the nature of laser excitation. These results explicitly illustrate important similarities and differences in fluorescence dynamics between pulsed and cw excitation, enabling more meaningful comparisons between literature reports and aiding in the design of new experiments to mitigate possible influences of high photon flux on QDs.
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Affiliation(s)
- Julie A Smyder
- Departments of Chemistry, University of Rochester, Rochester, New York 14627, USA.
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49
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Zhu Z, Marcus RA. Extension of the diffusion controlled electron transfer theory for intermittent fluorescence of quantum dots: inclusion of biexcitons and the difference of "on" and "off" time distributions. Phys Chem Chem Phys 2014; 16:25694-700. [PMID: 24801196 DOI: 10.1039/c4cp01274g] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The equations for the diffusion controlled electron transfer (DCET) theory of quantum dot blinking are extended to include biexcitons. In contrast to excitons, which undego resonant light to dark transitions, the biexcitons, having a much larger total energy, undergo a Fermi's Golden rule type transfer (many acceptance states). The latter immediately gives rise to an exponential tail for the light state, and it is explained why the dark state power law behavior is unaffected. Results are given for both continuous and pulsed excitation. The typical -3/2 power law for the light state at low light intensities, and for the dark state at all intensities, as well as dependence of the exponential tail on the square of the light intensity, and a decrease of the power in the power law for the light state from -3/2 to less negative values with increasing light intensity are all consistent with the theory. The desirability of measuring the dependence of the spectral diffusion coefficient on light intensity at room temperature as a test of several aspects of the theory is noted.
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Affiliation(s)
- Zhaoyan Zhu
- Noyes Laboratory of Chemical Physics, California Institute of Technology, Pasadena, California 91125, USA.
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50
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Schmidt R, Krasselt C, Göhler C, von Borczyskowski C. The fluorescence intermittency for quantum dots is not power-law distributed: a luminescence intensity resolved approach. ACS NANO 2014; 8:3506-3521. [PMID: 24580107 DOI: 10.1021/nn406562a] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The photoluminescence (PL) of single emitters like semiconductor quantum dots (QDs) shows PL intermittency, often called blinking. We explore the PL intensities of single CdSe/ZnS QDs in polystyrene (PS), on polyvenylalcohol (PVA), and on silicon oxide (SiOx) by the change-point analysis (CPA). By this, we relate results from the macrotime (sub-ms to 1000 s) and the microtime (0.1-100 ns) range to discrete PL intensities. We conclude that the intensity selected "on"-times in the ms range correspond to only a few (discrete) switching times, while the PL decays in the ns range are multiexponential even with respect to the same selected PL intensity. Both types of relaxation processes depend systematically on the PL intensity in course of a blinking time trace. The overall distribution of on-times does not follow a power law contrary to what has often been reported but can be compiled into 3-4 characteristic on-times. The results can be explained by the recently suggested multiple recombination centers model. Additionally, we can identify a well-defined QD state with a very low PL intensity above the noise level, which we assign to the strongly quenched exciton state. We describe our findings by a model of a hierarchical sequence of hole and electron trapping. Blinking events are the consequence of slow switching processes among these states and depend on the physicochemical properties of the heterogeneous nanointerface of the QDs.
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Affiliation(s)
- Robert Schmidt
- Institute of Physics, Optical Spectroscopy and Molecular Physics, Centre for Nanostructured Materials and Analytics (nanoMA), Technische Universität Chemnitz , 09107 Chemnitz, Germany
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