1
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Kumar G, Lin CC, Kuo HC, Chen FC. Enhancing photoluminescence performance of perovskite quantum dots with plasmonic nanoparticles: insights into mechanisms and light-emitting applications. NANOSCALE ADVANCES 2024; 6:782-791. [PMID: 38298599 PMCID: PMC10825943 DOI: 10.1039/d3na01078c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/05/2023] [Accepted: 12/28/2023] [Indexed: 02/02/2024]
Abstract
Perovskite quantum dots (QDs) are considered as promising materials for numerous optoelectronic applications due to their narrow emission spectra, high color purity, high photoluminescence quantum yields (PLQYs), and cost-effectiveness. Herein, we synthesized various types of perovskite QDs and incorporated Au nanoparticles (NPs) to systematically investigate the impact of plasmonic effects on the photoluminescence performance of perovskite QDs. The PLQYs of the QDs are enhanced effectively upon the inclusion of Au NPs in the solutions, with an impressive PLQY approaching 99% achieved. The PL measurements reveal that the primary mechanism behind the PL improvement is the accelerated rate of radiative recombination. Furthermore, we integrate perovskite QDs and Au NPs, which function as color conversion layers, with blue light-emitting diodes (LEDs), achieving a remarkable efficiency of 140.6 lm W-1. Additionally, we prepare photopatternable thin films of perovskite QDs using photocrosslinkable polymers as the matrix. Microscale patterning of the thin films is accomplished, indicating that the addition of plasmonic NPs does not adversely affect their photopatternable properties. Overall, our research not only elucidates the underlying mechanisms of plasmonic effects on perovskite QDs but presents a practical method for enhancing their optical performance, paving the way for next-generation optoelectronic applications, including high-definition micro-LED panels.
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Affiliation(s)
- Gautham Kumar
- Department of Photonics, College of Electrical and Computer Engineering, National Yang Ming Chiao Tung University Hsinchu 30010 Taiwan
| | - Chien-Chung Lin
- Graduate Institute of Photonics and Optoelectronics, Department of Electrical Engineering, National Taiwan University Taipei 10617 Taiwan
| | - Hao-Chung Kuo
- Department of Photonics, College of Electrical and Computer Engineering, National Yang Ming Chiao Tung University Hsinchu 30010 Taiwan
| | - Fang-Chung Chen
- Department of Photonics, College of Electrical and Computer Engineering, National Yang Ming Chiao Tung University Hsinchu 30010 Taiwan
- Center for Emergent Functional Matter Science, National Yang Ming Chiao Tung University Hsinchu 30010 Taiwan
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2
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Mohkam M, Sadraeian M, Lauto A, Gholami A, Nabavizadeh SH, Esmaeilzadeh H, Alyasin S. Exploring the potential and safety of quantum dots in allergy diagnostics. MICROSYSTEMS & NANOENGINEERING 2023; 9:145. [PMID: 38025887 PMCID: PMC10656439 DOI: 10.1038/s41378-023-00608-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/27/2023] [Revised: 09/01/2023] [Accepted: 09/07/2023] [Indexed: 12/01/2023]
Abstract
Biomedical investigations in nanotherapeutics and nanomedicine have recently intensified in pursuit of new therapies with improved efficacy. Quantum dots (QDs) are promising nanomaterials that possess a wide array of advantageous properties, including electronic properties, optical properties, and engineered biocompatibility under physiological conditions. Due to these characteristics, QDs are mainly used for biomedical labeling and theranostic (therapeutic-diagnostic) agents. QDs can be functionalized with ligands to facilitate their interaction with the immune system, specific IgE, and effector cell receptors. However, undesirable side effects such as hypersensitivity and toxicity may occur, requiring further assessment. This review systematically summarizes the potential uses of QDs in the allergy field. An overview of the definition and development of QDs is provided, along with the applications of QDs in allergy studies, including the detection of allergen-specific IgE (sIgE), food allergens, and sIgE in cellular tests. The potential treatment of allergies with QDs is also described, highlighting the toxicity and biocompatibility of these nanodevices. Finally, we discuss the current findings on the immunotoxicity of QDs. Several favorable points regarding the use of QDs for allergy diagnosis and treatment are noted.
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Affiliation(s)
- Milad Mohkam
- Allergy Research Center, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Mohammad Sadraeian
- Institute for Biomedical Materials and Devices (IBMD), Faculty of Science, University of Technology Sydney, Sydney, NSW 2007 Australia
| | - Antonio Lauto
- School of Science, University of Western Sydney, Campbelltown, NSW 2560 Australia
- School of Medicine, University of Western Sydney, Campbelltown, NSW 2560 Australia
| | - Ahmad Gholami
- Biotechnology Research Center, Shiraz University of Medical Sciences, Shiraz, Iran
- Department of Pharmaceutical Biotechnology, School of Pharmacy, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Seyed Hesamodin Nabavizadeh
- Allergy Research Center, Shiraz University of Medical Sciences, Shiraz, Iran
- Department of Allergy and Clinical Immunology, Namazi Hospital, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Hossein Esmaeilzadeh
- Allergy Research Center, Shiraz University of Medical Sciences, Shiraz, Iran
- Department of Allergy and Clinical Immunology, Namazi Hospital, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Soheila Alyasin
- Allergy Research Center, Shiraz University of Medical Sciences, Shiraz, Iran
- Department of Allergy and Clinical Immunology, Namazi Hospital, Shiraz University of Medical Sciences, Shiraz, Iran
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3
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Steenbock T, Dittmann T, Kumar S, Bester G. Ligand-Induced Symmetry Breaking as the Origin of Multiexponential Photoluminescence Decay in CdSe Quantum Dots. J Phys Chem Lett 2023; 14:8859-8866. [PMID: 37756012 DOI: 10.1021/acs.jpclett.3c02056] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/28/2023]
Abstract
The bright photoluminescence (PL) of colloidal CdSe quantum dots (QDs) makes them interesting for optical applications. For most of them, well-defined PL properties, dominated by a single excitonic state, are required. However, in many PL experiments with QD ensembles, multiexponential decay was observed. On the basis of spin-orbit density functional theory and screened configuration interaction calculations, we show that highly symmetric and defect-free CdSe QDs with diameters of 1.7 and 2.0 nm possess a multiexponential low-temperature PL at the single-dot level. This is a consequence of ligand-induced symmetry breaking with a subsequent rearrangement of the lowest eight excitonic states in two sets of four singly degenerate excitonic states. For each set, the lowest state is dark and the other three are bright. We find that the splitting between the sets can be modified by the coverage and choice of the ligand, which facilitates the engineering of the PL properties of CdSe QDs.
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Affiliation(s)
- Torben Steenbock
- Department of Chemistry, University of Hamburg, HARBOR, Building 610, Luruper Chaussee 149, Hamburg 22761, Germany
| | - Tobias Dittmann
- Department of Chemistry, University of Hamburg, HARBOR, Building 610, Luruper Chaussee 149, Hamburg 22761, Germany
| | - Surender Kumar
- Department of Chemistry, University of Hamburg, HARBOR, Building 610, Luruper Chaussee 149, Hamburg 22761, Germany
| | - Gabriel Bester
- Department of Chemistry and Physics, University of Hamburg, HARBOR, Building 610, Luruper Chaussee 149, Hamburg 22761, Germany
- The Hamburg Centre for Ultrafast Imaging, Luruper Chaussee 149, Hamburg 22761, Germany
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4
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Nguyen AT, Baucom DR, Wang Y, Heyes CD. Compact, Fast Blinking Cd-Free Quantum Dots for Super-Resolution Fluorescence Imaging. CHEMICAL & BIOMEDICAL IMAGING 2023; 1:251-259. [PMID: 37388960 PMCID: PMC10302876 DOI: 10.1021/cbmi.3c00018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/24/2023] [Revised: 03/20/2023] [Accepted: 03/21/2023] [Indexed: 07/01/2023]
Abstract
Quantum dots (QDs) can be used as fluorescent probes in single molecule localization microscopy to achieve subdiffraction limit resolution (super-resolution fluorescence imaging). However, the toxicity of Cd in the prototypical CdSe-based QDs can limit their use in biological applications. Furthermore, commercial CdSe QDs are usually modified with relatively thick shells of both inorganic and organic materials to render them in the 10-20 nm size range, which is relatively large for biological labels. In this report, we present compact (4-6 nm) CuInS2/ZnS (CIS/ZnS) and compare them to commercially sourced CdSe/ZnS QDs for their blinking behavior, localization precision and super-resolution imaging. Although commercial CdSe/ZnS QDs are brighter than the more compact Cd-free CIS/ZnS QD, both give comparable results of 4.5-5.0-fold improvement in imaging resolution over conventional TIRF imaging of actin filaments. This likely results from the fact that CIS/ZnS QDs show very short on-times and long off times which leads to less overlap in the point spread functions of emitting CIS/ZnS QD labels on the actin filaments at the same labeling density. These results demonstrate that CIS/ZnS QDs are an excellent candidate to complement and perhaps even replace the larger and more toxic CdSe-based QDs for robust single- molecule super-resolution imaging.
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Affiliation(s)
- Anh T. Nguyen
- Department
of Chemistry and Biochemistry, University
of Arkansas, 345 North Campus Drive, Fayetteville, Arkansas 72701, United States
| | - Dustin R. Baucom
- Department
of Chemistry and Biochemistry, University
of Arkansas, 345 North Campus Drive, Fayetteville, Arkansas 72701, United States
| | - Yong Wang
- Department
of Physics, University of Arkansas, 825 West Dickson Street, Fayetteville, Arkansas 72701, United States
| | - Colin D. Heyes
- Department
of Chemistry and Biochemistry, University
of Arkansas, 345 North Campus Drive, Fayetteville, Arkansas 72701, United States
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5
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Vonk SJW, Rabouw FT. Biexciton Blinking in CdSe-Based Quantum Dots. J Phys Chem Lett 2023:5353-5361. [PMID: 37276380 DOI: 10.1021/acs.jpclett.3c00437] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Experiments on single colloidal quantum dots (QDs) have revealed temporal fluctuations in the emission efficiency of the single-exciton state. These fluctuations, often termed "blinking", are caused by opening/closing of charge-carrier traps and/or charging/discharging of the QD. In the regime of strong optical excitation, multiexciton states are formed. The emission efficiencies of multiexcitons are lower because of Auger processes, but a quantitative characterization is challenging. Here, we quantify fluctuations of the biexciton efficiency for single CdSe/CdS/ZnS core-shell QDs. We find that the biexciton efficiency "blinks" significantly. The additional electron due to charging of a QD accelerates Auger recombination by a factor of 2 compared to the neutral biexciton, while opening/closing of a charge-carrier trap leads to an increase of the nonradiative recombination rate by a factor of 4. To understand the fast rate of trap-assisted recombination, we propose a revised model for trap-assisted recombination based on reversible trapping. Finally, we discuss the implications of biexciton blinking for lasing applications.
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Affiliation(s)
- Sander J W Vonk
- Debye Institute for Nanomaterials Science, Utrecht University, Princetonplein 1, 3584 CC Utrecht, The Netherlands
| | - Freddy T Rabouw
- Debye Institute for Nanomaterials Science, Utrecht University, Princetonplein 1, 3584 CC Utrecht, The Netherlands
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6
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Chandrasiri HB, Jing H, Perera T, Hu YS, Snee PT. Fluorescence Intermittency of Quantum Dot-Organic Dye Conjugates: Implications for Alternative Energy and Biological Imaging. J Phys Chem Lett 2023; 14:3621-3626. [PMID: 37023397 DOI: 10.1021/acs.jpclett.3c00076] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/19/2023]
Abstract
Quantum dot (QD)-organic dye couple chromophores are topical due to their applications in biology, catalysis, and energy. The maximization of energy transfer efficiency can be guided by the underlying Förster or Dexter mechanisms; however, the impact of fluorescence intermittency must also be considered. Here we demonstrate that the average ⟨ton⟩ and ⟨toff⟩ times of dye acceptors in coupled QD-dye chromophores are substantially affected by the donors' blinking behavior. With regard to biological imaging, this effect beneficially minimizes the photobleaching of the acceptor dye. The implications for alternative energy are less encouraging as the acceptors' capacity to store energy, using ⟨ton⟩/⟨toff⟩ as a metric, was reduced by as much as ∼95%. These detrimental effects can be mitigated by suppressing QD blinking via surface treatment. This study also demonstrates several instances of the nonconformity of QD blinking dynamics to a power law distribution, as a robust examination of the off times reveals log-normal behavior that is consistent with the Albery model.
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Affiliation(s)
- Hashini B Chandrasiri
- Department of Chemistry, College of Liberal Arts & Sciences, University of Illinois, Chicago, Chicago, Illinois 60607-7061, United States
| | - Haoran Jing
- Department of Chemistry, College of Liberal Arts & Sciences, University of Illinois, Chicago, Chicago, Illinois 60607-7061, United States
| | - Thilini Perera
- Department of Chemistry, College of Liberal Arts & Sciences, University of Illinois, Chicago, Chicago, Illinois 60607-7061, United States
| | - Ying S Hu
- Department of Chemistry, College of Liberal Arts & Sciences, University of Illinois, Chicago, Chicago, Illinois 60607-7061, United States
| | - Preston T Snee
- Department of Chemistry, College of Liberal Arts & Sciences, University of Illinois, Chicago, Chicago, Illinois 60607-7061, United States
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7
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Ghosh S, Mukherjee S, Mandal S, De CK, Mardanya S, Saha A, Mandal PK. Beneficial Intrinsic Hole Trapping and Its Amplitude Variation in a Highly Photoluminescent Toxic-Metal-Free Quantum Dot. J Phys Chem Lett 2023; 14:260-266. [PMID: 36595225 DOI: 10.1021/acs.jpclett.2c03373] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Intrinsic hole trapping as well as hole detrapping have not been observed for any quantum dot (QD) or perovskite nanocrystal (PNC) system. Moreover, amplitude variation of intrinsic hole trapping (or detrapping) has not been reported at all for any QD or PNC system. However, for a CuInS2-based core/alloy-shell (CAS) QD system, (a) both intrinsic hole trapping and detrapping have been observed and (b) very significant amplitude variations of hole trapping (∼16 to ∼42%) and hole detrapping (∼44 to 23%) have been observed. Unlike detrimental electron trapping, hole trapping has been shown to be beneficial, having a direct correlation toward increasing PLQY to 96%. Simultaneous electron and hole trapping has been shown to be quite beneficial for the CuInS2-based CAS QD system leading to the longest ON time (∼130 s) for which a nontoxic metal-based QD remains only in the ON-state without blinking.
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8
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Abdellatif AAH, Younis MA, Alsharidah M, Al Rugaie O, Tawfeek HM. Biomedical Applications of Quantum Dots: Overview, Challenges, and Clinical Potential. Int J Nanomedicine 2022; 17:1951-1970. [PMID: 35530976 PMCID: PMC9076002 DOI: 10.2147/ijn.s357980] [Citation(s) in RCA: 39] [Impact Index Per Article: 19.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2022] [Accepted: 04/12/2022] [Indexed: 12/14/2022] Open
Abstract
Despite the massive advancements in the nanomedicines and their associated research, their translation into clinically-applicable products is still below promises. The latter fact necessitates an in-depth evaluation of the current nanomedicines from a clinical perspective to cope with the challenges hampering their clinical potential. Quantum dots (QDs) are semiconductors-based nanomaterials with numerous biomedical applications such as drug delivery, live imaging, and medical diagnosis, in addition to other applications beyond medicine such as in solar cells. Nevertheless, the power of QDs is still underestimated in clinics. In the current article, we review the status of QDs in literature, their preparation, characterization, and biomedical applications. In addition, the market status and the ongoing clinical trials recruiting QDs are highlighted, with a special focus on the challenges limiting the clinical translation of QDs. Moreover, QDs are technically compared to other commercially-available substitutes. Eventually, we inspire the technical aspects that should be considered to improve the clinical fate of QDs.
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Affiliation(s)
- Ahmed A H Abdellatif
- Department of Pharmaceutics, College of Pharmacy, Qassim University, Buraydah, 51452, Saudi Arabia
- Department of Pharmaceutics and Pharmaceutical Technology, Faculty of Pharmacy, Al-Azhar University, Assiut, 71524, Egypt
| | - Mahmoud A Younis
- Department of Industrial Pharmacy, Faculty of Pharmacy, Assiut University, Assiut, 71526, Egypt
| | - Mansour Alsharidah
- Department of Physiology, College of Medicine, Qassim University, Buraydah, 51452, Saudi Arabia
| | - Osamah Al Rugaie
- Department of Basic Medical Sciences, College of Medicine and Medical Sciences, Qassim University, Unaizah, Al Qassim, 51911, Saudi Arabia
| | - Hesham M Tawfeek
- Department of Industrial Pharmacy, Faculty of Pharmacy, Assiut University, Assiut, 71526, Egypt
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9
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Roy D, Ghosh S, De CK, Mukherjee S, Mandal S, Mandal PK. Excitation-Energy-Dependent Photoluminescence Quantum Yield is Inherent to Optically Robust Core/Alloy-Shell Quantum Dots in a Vast Energy Landscape. J Phys Chem Lett 2022; 13:2404-2417. [PMID: 35257586 DOI: 10.1021/acs.jpclett.2c00157] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
The importance of alloy-shelling in optically robust Core/Alloy-Shell (CAS) QDs has been described from structural and energetic aspects. Unlike fluorescent dyes, both Core/Shell (CS) and CAS QDs exhibit excitation-energy-dependent photoluminescence quantum yield (PLQY). For both CdSe and InP CAS QDs (with metal- and nonmetal-based alloy-shelling, respectively), with increasing excitation energy, (a) the ultrafast rise-time or relaxation-time to the band-edge increases and (b) the magnitude of the normalized bleach signal decreases. Ultrasensitive single-particle spectroscopic investigation results showed that with decreasing excitation energy, (a) the fraction of ON events increases, (b) the ratio of exciton-detrapping rate/trapping rate increases, and (c) the extent of beneficial hole trapping increases. A relative decrease in PLQY with increasing excitation energy is much less pronounced in CAS QDs than in CS QDs. Unless trap states are removed completely especially in the higher-energy landscape, PLQY will remain inherently dependent on excitation energy for QDs in the vast energy landscape. When reporting the PLQY of QDs, the magnitude of the excitation energy must be mentioned.
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Affiliation(s)
- Debjit Roy
- Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Kolkata, Mohanpur, West Bengal, India 741246
| | - Swarnali Ghosh
- Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Kolkata, Mohanpur, West Bengal, India 741246
| | - Chayan K De
- Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Kolkata, Mohanpur, West Bengal, India 741246
| | - Soumen Mukherjee
- Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Kolkata, Mohanpur, West Bengal, India 741246
| | - Saptarshi Mandal
- Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Kolkata, Mohanpur, West Bengal, India 741246
| | - Prasun K Mandal
- Department of Chemical Sciences & Centre for Advanced Functional Materials, Indian Institute of Science Education and Research (IISER) Kolkata, Mohanpur, West Bengal, India 741246
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10
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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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11
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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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12
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Kargozar S, Hoseini SJ, Milan PB, Hooshmand S, Kim H, Mozafari M. Quantum Dots: A Review from Concept to Clinic. Biotechnol J 2020; 15:e2000117. [DOI: 10.1002/biot.202000117] [Citation(s) in RCA: 60] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2020] [Revised: 07/10/2020] [Indexed: 01/30/2023]
Affiliation(s)
- Saeid Kargozar
- Tissue Engineering Research Group (TERG), Department of Anatomy and Cell Biology, School of Medicine Mashhad University of Medical Sciences Mashhad Iran
| | - Seyed Javad Hoseini
- Department of Medical Biotechnology and Nanotechnology, School of Medicine Mashhad University of Medical Sciences Mashhad Iran
| | - Peiman Brouki Milan
- Cellular and Molecular Research Centre Iran University of Medical Sciences Tehran Iran
- Institutes of Regenerative Medicine, Faculty of Advanced Technologies in Medicine Iran University of Medical Sciences Tehran Iran
- Department of Tissue Engineering and Regenerative Medicine, Faculty of Advanced Technologies in Medicine Iran University of Medical Sciences Tehran Iran
| | - Sara Hooshmand
- Pharmacological Research Center of Medicinal Plants Mashhad University of Medical Sciences Mashhad Iran
- Department of Pharmacology, Faculty of Medicine Mashhad University of Medical Sciences Mashhad Iran
| | - Hae‐Won Kim
- Institute of Tissue Regeneration Engineering (ITREN) Dankook University Cheonan Republic of Korea
- Department of Nanobiomedical Science & BK21 PLUS NBM Global Research Center for Regenerative Medicine Dankook University Cheonan Republic of Korea
- Department of Biomaterials Science, School of Dentistry Dankook University Cheonan Republic of Korea
| | - Masoud Mozafari
- Department of Tissue Engineering and Regenerative Medicine, Faculty of Advanced Technologies in Medicine Iran University of Medical Sciences Tehran Iran
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13
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Zenkevich E, Stupak A, von Borczyskowski C. Temperature Dependence of Photoluminescence for Spin-Coated Semiconductor Quantum Dots and Quantum Dot-Dye Nanoassemblies on Quartz Substrate. INTERNATIONAL JOURNAL OF NANOSCIENCE 2019. [DOI: 10.1142/s0219581x19400052] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The attachment of pyridyl substituted porphyrin molecule to the surface of CdSe/ZnS quantum dots in solutions is realized in the competition with capping ligand TOPO molecules resulting in the specific change of photoluminescence for the quantum dots across the temperature range of 77–290[Formula: see text]K. We have shown that fixation of alone quantum dots or quantum dot-porphyrin nanoassemblies on quartz substrate changes significantly temperature dependence of photoluminescence. In contrast to the samples in a glass-forming solution no phase transition of the TOPO capping layer was observed upon removal of the capping layer.
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Affiliation(s)
- E. Zenkevich
- Department of Information Technologies and Robotics, Belarusian National Technical University, Nezavisimosti Ave. 65, 220013 Minsk, Belarus
| | - A. Stupak
- B. I. Stepanov Institute of Physics, NASB, Nezavisimosti Ave. 68, 220072 Minsk, Belarus
| | - C. von Borczyskowski
- Institute of Physics, University of Technology Chemnitz, Reichenhainer Str. 70, 09107 Chemnitz, Germany
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14
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Xiao L, Sun H. Novel properties and applications of carbon nanodots. NANOSCALE HORIZONS 2018; 3:565-597. [PMID: 32254112 DOI: 10.1039/c8nh00106e] [Citation(s) in RCA: 138] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
In the most recent decade, carbon dots have drawn intensive attention and triggered substantial investigation. Carbon dots manifest superior merits, including excellent biocompatibility both in vitro and in vivo, resistance to photobleaching, easy surface functionalization and bio-conjugation, outstanding colloidal stability, eco-friendly synthesis, and low cost. All of these endow them with the great potential to replace conventional unsatisfactory fluorescent heavy metal-containing semiconductor quantum dots or organic dyes. Even though the understanding of their photoluminescence mechanism is still controversial, carbon dots have already exhibited many versatile applications. In this article, we summarize and review the recent progress achieved in the field of carbon dots, and provide a comprehensive summary and discussion on their synthesis methods and emission mechanisms. We also present the applications of carbon dots in bioimaging, drug delivery, microfluidics, light emitting diode (LED), sensing, logic gates, and chiral photonics, etc. Some unaddressed issues, challenges, and future prospects of carbon dots are also discussed. We envision that carbon dots will eventually have great commercial utilization and will become a strong competitor to some currently used fluorescent materials. It is our hope that this review will provide insights into both the fundamental research and practical applications of carbon dots.
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Affiliation(s)
- Lian Xiao
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, 637371, Singapore.
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15
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Guo X, Kuang Y, Wang S, Li Z, Shen H, Guo L. Shell-dependent blinking behavior and fluorescence dynamics of single ZnSe/CdS core/shell quantum dots. NANOSCALE 2018; 10:18696-18705. [PMID: 30270388 DOI: 10.1039/c8nr06749j] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
An understanding of blinking behavior and photodynamics is crucial for improving the optical properties of quantum dots (QDs). Here we report the emission blinking behavior and dynamical mechanisms of single ZnSe/CdS core/shell QDs with the shell thickness varying from 1 to 6 monolayers. We find that the emission blinking behavior can be efficiently suppressed in the single-exciton regime and that the photoluminescence (PL) quantum yields (QY) and the corresponding fraction-bright of ZnSe/CdS QDs can be optimized by regulating the shell thickness. Specifically, the PL QY reaches a maximum of 93% when the shell thickness is 4 monolayers. The intensity-resolved and time-resolved fluorescence dynamics of single QDs indicate that three exciton decay pathways via trion emission, band-edge emission and shallow surface trap-state emission contribute to the blinking behavior of ZnSe/CdS QDs. The competitive contribution ratios of these three decay components are responsible for the significant difference in emission properties of ZnSe/CdS QDs with different shell thicknesses. Our findings in this work demonstrate that an effective way to improve the quantum yields and fraction-bright of core/shell QDs is to enhance the band-edge emission while suppressing the trion emission and surface trap-state emission.
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Affiliation(s)
- Xing Guo
- Institute of Micro/Nano Photonic Materials and Application, School of Physics and Electronics, Henan University, Kaifeng, 475004, People's Republic of China.
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16
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Stupak AP, Blaudeck T, Zenkevich EI, Krause S, von Borczyskowski C. The nature of non-FRET photoluminescence quenching in nanoassemblies from semiconductor quantum dots and dye molecules. Phys Chem Chem Phys 2018; 20:18579-18600. [PMID: 29953143 DOI: 10.1039/c8cp02846j] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Nanoassemblies formed via self-assembly based on colloidal CdSe quantum dots (QDs) and porphyrin (H2P) dye molecules show Fluorescence Resonant Energy Transfer (FRET) and non-FRET quenching of QD photoluminescence (PL). We present a procedure to unravel and quantify these two relaxation pathways via dynamic and static PL quenching experiments. Accordingly, FRET amounts at maximum to 10% of the total quenching efficiency. Since the degree of ligand coverage is inhomogeneously distributed across the QD ensemble PL quantum yields vary broadly. The attachment of H2P molecules occurs preferentially to those QDs with low ligand coverage. Along with that, nanoassembly formation deviates strongly from Poisson statistics. Like FRET, non-FRET depends on the QD size. We assign non-FRET quenching to the formation of specific new Cd2+ trap states following depletion of several ligands by the spacious dye molecules. While FRET follows quantitatively the Förster model, non-FRET appears on time scales of 1-3 ns in new and enhanced non-radiative near-band-edge QD PL decay channels caused by a trapping of the electrons in long-lived intra-gap states which then manifests itself in a subsequent weak PL emission. We assign the related intra-band emission to a recombination of deep-trap electrons and shallow-trap holes.
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Affiliation(s)
- Aleksander P Stupak
- B. I. Stepanov Institute of Physics, National Academy of Sciences of Belarus, Prospect Nezavisimosti 70, 220072 Minsk, Belarus
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17
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Yuan G, Gómez DE, Kirkwood N, Boldt K, Mulvaney P. Two Mechanisms Determine Quantum Dot Blinking. ACS NANO 2018; 12:3397-3405. [PMID: 29579376 DOI: 10.1021/acsnano.7b09052] [Citation(s) in RCA: 73] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Many potential applications of quantum dots (QDs) can only be realized once the luminescence from single nanocrystals (NCs) is understood. These applications include the development of quantum logic devices, single-photon sources, long-life LEDs, and single-molecule biolabels. At the single-nanocrystal level, random fluctuations in the QD photoluminescence occur, a phenomenon termed blinking. There are two competing models to explain this blinking: Auger recombination and surface trap induced recombination. Here we use lifetime scaling on core-shell chalcogenide NCs to demonstrate that both types of blinking occur in the same QDs. We prove that Auger-blinking can yield single-exponential on/off times in contrast to earlier work. The surface passivation strategy determines which blinking mechanism dominates. This study summarizes earlier studies on blinking mechanisms and provides some clues that stable single QDs can be engineered for optoelectronic applications.
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Affiliation(s)
- Gangcheng Yuan
- ARC Centre of Excellence in Exciton Science, School of Chemistry , University of Melbourne , Parkville , Victoria 3010 , Australia
| | | | - Nicholas Kirkwood
- ARC Centre of Excellence in Exciton Science, School of Chemistry , University of Melbourne , Parkville , Victoria 3010 , Australia
| | - Klaus Boldt
- ARC Centre of Excellence in Exciton Science, School of Chemistry , University of Melbourne , Parkville , Victoria 3010 , Australia
| | - Paul Mulvaney
- ARC Centre of Excellence in Exciton Science, School of Chemistry , University of Melbourne , Parkville , Victoria 3010 , Australia
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18
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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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19
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Photophysical Properties of Film Composites of Organic Polymers with Heterometallic Complexes of Transition Metals: a Review. THEOR EXP CHEM+ 2017. [DOI: 10.1007/s11237-017-9503-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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20
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Xu H, Brismar H, Fu Y. Influence of surface states on blinking characteristics of single colloidal CdSe-CdS/ZnS core-multishell quantum dot. J Colloid Interface Sci 2017. [PMID: 28645036 DOI: 10.1016/j.jcis.2017.06.046] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
We carefully characterized the fluorescence blinking of single colloidal CdSe-CdS/ZnS core-multishell quantum dots (QDs) with different surface modifications, including octadecylamine (ODA) coated QDs dispersed in chloroform, aqueous 3-mercaptopropionic acids (3MPA) coated QDs in HEPES solution treated by Ca2+ ions and ethylene glycol tetraacetic acid (EGTA, Ca2+ chelator), and aqueous 3MPA-QDs treated by glycerol. It was found that the on- and off-state probability density distributions displayed different rules. The off-state probability density distributions of all QDs complied well with the inverse power law, while the on-state probability density distributions bended upwards in log-log scale, and the degree of the upwards-bending correlated strongly with QD surface modification and fluorescence brightness of the single QD. Further autocorrelation analysis revealed that the fluorescence time series of a single QD was more random when the single QD showed a stronger fluorescence. Realistic numerical simulations with input parameters from quantum mechanical calculations showed that the QD exciton was first generated by an excitation photon; It radiatively recombined to give QD's fluorescence response, i.e., the on-state, which displayed the upwards-bended on-state probability density distribution profile; The electron and/or the hole of the photoexcited exciton in the QD core, after tunneling to the QD surface, randomly walked through the two-dimensional network of the QD surface states, resulting in the off-state probability density distribution profile of the inverse power law. Surface modification modified the QD surface-state network, in turn modifying the on/off probability density distribution profiles. Our findings provide us with a novel highway of applying colloidal QDs to study microscopic physical, and chemical, processes in many fields including in vivo and in vitro imaging, sensing and labelling.
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Affiliation(s)
- Hao Xu
- Section of Cellular Biophysics, Department of Applied Physics, Royal Institute of Technology, Science for Life Laboratory, SE-171 21 Solna, Sweden
| | - Hjalmar Brismar
- Section of Cellular Biophysics, Department of Applied Physics, Royal Institute of Technology, Science for Life Laboratory, SE-171 21 Solna, Sweden
| | - Ying Fu
- Section of Cellular Biophysics, Department of Applied Physics, Royal Institute of Technology, Science for Life Laboratory, SE-171 21 Solna, Sweden.
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21
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Qin H, Meng R, Wang N, Peng X. Photoluminescence Intermittency and Photo-Bleaching of Single Colloidal Quantum Dot. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2017; 29:1606923. [PMID: 28256776 DOI: 10.1002/adma.201606923] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2016] [Revised: 02/02/2017] [Indexed: 06/06/2023]
Abstract
Photoluminescence (PL) blinking of single colloidal quantum dot (QD)-PL intensity switching between different brightness states under constant excitation-and photo-bleaching are roadblocks for most applications of QDs. This progress report shall treat PL blinking and photo-bleaching both as photochemical events, namely, PL blinking as reversible and photo-bleaching being irreversible ones. Most studies on single-molecule spectroscopy of QDs in literature are related to PL blinking, which invites us to concentrate our discussions on the PL blinking, including its brief history in 20 years, analysis methods, competitive mechanisms and different strategies to battle it. In terms of suppression of the PL blinking, wavefunction confinement-confining photo-generated electron and hole within the core and inner portion of the shell of a core/shell QD-demonstrates significant advantages. This strategy yields nearly non-blinking QDs with their emission peaks covering most part of the visible window. As expected, the resulting QDs from this new strategy also show substantially improved anti-bleaching features.
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Affiliation(s)
- Haiyan Qin
- Center for Chemistry of Novel & High-Performance Materials, Department of Chemistry, Zhejiang University, Hangzhou, 310027, China
| | - Renyang Meng
- Center for Chemistry of Novel & High-Performance Materials, Department of Chemistry, Zhejiang University, Hangzhou, 310027, China
| | - Na Wang
- Center for Chemistry of Novel & High-Performance Materials, Department of Chemistry, Zhejiang University, Hangzhou, 310027, China
| | - Xiaogang Peng
- Center for Chemistry of Novel & High-Performance Materials, Department of Chemistry, Zhejiang University, Hangzhou, 310027, China
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22
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Gao F, Bajwa P, Nguyen A, Heyes CD. Shell-Dependent Photoluminescence Studies Provide Mechanistic Insights into the Off-Grey-On Transitions of Blinking Quantum Dots. ACS NANO 2017; 11:2905-2916. [PMID: 28221750 DOI: 10.1021/acsnano.6b08040] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
The majority of quantum dot (QD) blinking studies have used a model of switching between two distinct fluorescence intensity levels, "on" and "off". However, a distinct intermediate intensity level has been identified in some recent reports, a so-called "grey" or "dim" state, which has brought this binary model into question. While this grey state has been proposed to result from the formation of a trion, it is still unclear under which conditions it is present in a QD. By performing shell-dependent blinking studies on CdSe QDs, we report that the populations of the grey state and the on state are strongly dependent on both the shell material and its thickness. We found that adding a ZnS shell did not result in a significant population of the grey state. Using ZnSe as the shell material resulted in a slightly higher population of the grey state, although it was still poorly resolved. However, adding a CdS shell resulted in the population of a grey state, which depended strongly on its thickness up to 5 ML. Interestingly, while the frequency of transitions to and from the grey state showed a very strong dependence on CdS shell thickness, the brightness of and the dwell time in the grey state did not. Moreover, we found that the grey state acts as an on-pathway intermediate state between on and off states, with the thickness of the shell determining the transition probability between them. We also identified two types of blinking behavior in QDs, one that showed long-lived but lower intensity on states and another that showed short-lived but brighter on states that also depended on the shell thickness. Intensity-resolved single QD fluorescence lifetime analysis was used to identify the relationship between the various exciton decay pathways and the resulting intensity levels. We used this data to propose a model in which multiple on, grey, and off states exist whose equilibrium populations vary with time that give rise to the various intensity levels of single QDs and which depends on shell composition and thickness.
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Affiliation(s)
- Feng Gao
- Department of Chemistry and Biochemistry, University of Arkansas , 345 North Campus Drive, Fayetteville, Arkansas 72701, United States
| | - Pooja Bajwa
- Department of Chemistry and Biochemistry, University of Arkansas , 345 North Campus Drive, Fayetteville, Arkansas 72701, United States
| | - Anh Nguyen
- Department of Chemistry and Biochemistry, University of Arkansas , 345 North Campus Drive, Fayetteville, Arkansas 72701, United States
| | - Colin D Heyes
- Department of Chemistry and Biochemistry, University of Arkansas , 345 North Campus Drive, Fayetteville, Arkansas 72701, United States
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23
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Ruth A, Hayashi M, Zapol P, Si J, McDonald MP, Morozov YV, Kuno M, Jankó B. Fluorescence intermittency originates from reclustering in two-dimensional organic semiconductors. Nat Commun 2017; 8:14521. [PMID: 28223699 PMCID: PMC5322502 DOI: 10.1038/ncomms14521] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2016] [Accepted: 01/06/2017] [Indexed: 12/02/2022] Open
Abstract
Fluorescence intermittency or blinking is observed in nearly all nanoscale fluorophores. It is characterized by universal power-law distributions in on- and off-times as well as 1/f behaviour in corresponding emission power spectral densities. Blinking, previously seen in confined zero- and one-dimensional systems has recently been documented in two-dimensional reduced graphene oxide. Here we show that unexpected blinking during graphene oxide-to-reduced graphene oxide photoreduction is attributed, in large part, to the redistribution of carbon sp2 domains. This reclustering generates fluctuations in the number/size of emissive graphenic nanoclusters wherein multiscale modelling captures essential experimental aspects of reduced graphene oxide's absorption/emission trajectories, while simultaneously connecting them to the underlying photochemistry responsible for graphene oxide's reduction. These simulations thus establish causality between currently unexplained, long timescale emission intermittency in a quantum mechanical fluorophore and identifiable chemical reactions that ultimately lead to switching between on and off states. Fluorescence blinking has been recently observed in two-dimensional graphene oxide systems, yet its origin has so far remained elusive. Here, the authors unveil the nature of such long timescale emission intermittency and link it to the distribution of sp2 carbon domains.
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Affiliation(s)
- Anthony Ruth
- Department of Physics, University of Notre Dame, Notre Dame, Indiana 46556, USA
| | - Michitoshi Hayashi
- National Taiwan University, Center for Condensed Matter Sciences, National Taiwan University,, Taipei 10617, Taiwan
| | - Peter Zapol
- Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439, USA
| | - Jixin Si
- Department of Physics, University of Notre Dame, Notre Dame, Indiana 46556, USA
| | | | - Yurii V Morozov
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, USA
| | - Masaru Kuno
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, USA
| | - Boldizsár Jankó
- Department of Physics, University of Notre Dame, Notre Dame, Indiana 46556, USA
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24
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Meng R, Qin H, Niu Y, Fang W, Yang S, Lin X, Cao H, Ma J, Lin W, Tong L, Peng X. Charging and Discharging Channels in Photoluminescence Intermittency of Single Colloidal CdSe/CdS Core/Shell Quantum Dot. J Phys Chem Lett 2016; 7:5176-5182. [PMID: 27973911 DOI: 10.1021/acs.jpclett.6b02448] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
Understanding photoluminescence (PL) intermittency of single quantum dots (QDs) (intensity blinking by randomly switching between distinguishable brightness states under continuous excitation) has been a long-standing fundamental challenge and potential roadblock for their applications. Here we introduce a new analysis method for single-molecule spectroscopy that treats the blinking as photochemical/chemical processes (switching between neutral/bright and charged/dim states). It uncovers the channels for charging (bright to dim) and discharging (dim to bright) involved in PL blinking of single CdSe/CdS core/shell QDs. Both charging and discharging of the single CdSe/CdS core/shell QD possess a photochemical channel (∼10-5 to 10-6 events/photon) that linearly depends on excitation in both single- and multi-exciton regime. These two linear channels coupled to a spontaneous discharging channel (∼2 events/s) to dictate the QDs from nonblinking to gradually blinking under increasing excitation. For high-quality CdSe/CdS core/shell QDs, Auger ionization of multiexciton for both charging and discharging is negligible.
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Affiliation(s)
- Renyang Meng
- Center for Chemistry of Novel & High-Performance Materials, Department of Chemistry, Zhejiang University , Hangzhou 310027, China
| | - Haiyan Qin
- Center for Chemistry of Novel & High-Performance Materials, Department of Chemistry, Zhejiang University , Hangzhou 310027, China
| | - Yuan Niu
- Center for Chemistry of Novel & High-Performance Materials, Department of Chemistry, Zhejiang University , Hangzhou 310027, China
- State Key Laboratory of Modern Optical Instrumentation, College of Optical Science and Engineering, Zhejiang University , Hangzhou 310027, China
| | - Wei Fang
- State Key Laboratory of Modern Optical Instrumentation, College of Optical Science and Engineering, Zhejiang University , Hangzhou 310027, China
| | - Sen Yang
- State Key Laboratory of Modern Optical Instrumentation, College of Optical Science and Engineering, Zhejiang University , Hangzhou 310027, China
| | - Xing Lin
- State Key Laboratory of Modern Optical Instrumentation, College of Optical Science and Engineering, Zhejiang University , Hangzhou 310027, China
| | - Hujia Cao
- Center for Chemistry of Novel & High-Performance Materials, Department of Chemistry, Zhejiang University , Hangzhou 310027, China
| | - Junliang Ma
- Center for Chemistry of Novel & High-Performance Materials, Department of Chemistry, Zhejiang University , Hangzhou 310027, China
| | - Wanzhen Lin
- Center for Chemistry of Novel & High-Performance Materials, Department of Chemistry, Zhejiang University , Hangzhou 310027, China
| | - Limin Tong
- State Key Laboratory of Modern Optical Instrumentation, College of Optical Science and Engineering, Zhejiang University , Hangzhou 310027, China
| | - Xiaogang Peng
- Center for Chemistry of Novel & High-Performance Materials, Department of Chemistry, Zhejiang University , Hangzhou 310027, China
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25
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Streiter M, Krause S, von Borczyskowski C, Deibel C. Dynamics of Single-Molecule Stokes Shifts: Influence of Conformation and Environment. J Phys Chem Lett 2016; 7:4281-4284. [PMID: 27733039 DOI: 10.1021/acs.jpclett.6b02102] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
We report on time-dependent Stokes shift measurements of single molecules. Excitation and emission spectroscopy were applied to study the temporal Stokes shift evolution of single perylene diimide molecules embedded in a polymer matrix on the time scale of seconds. The Stokes shift varied between individual molecules as well as for single molecules undergoing different conformations and geometries. From the distribution and temporal evolution of Stokes shifts, we unravel the interplay of nanoenvironment and molecular conformation. We found that Stokes shift fluctuations are related to simultaneous and unidirectional shifts of both emission and excitation spectra.
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Affiliation(s)
- Martin Streiter
- Institut für Physik, Technische Universität Chemnitz , 09126 Chemnitz, Germany
| | - Stefan Krause
- Institut für Physik, Technische Universität Chemnitz , 09126 Chemnitz, Germany
| | | | - Carsten Deibel
- Institut für Physik, Technische Universität Chemnitz , 09126 Chemnitz, Germany
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26
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Abstract
Organic (opto)electronic materials have received considerable attention due to their applications in thin-film-transistors, light-emitting diodes, solar cells, sensors, photorefractive devices, and many others. The technological promises include low cost of these materials and the possibility of their room-temperature deposition from solution on large-area and/or flexible substrates. The article reviews the current understanding of the physical mechanisms that determine the (opto)electronic properties of high-performance organic materials. The focus of the review is on photoinduced processes and on electronic properties important for optoelectronic applications relying on charge carrier photogeneration. Additionally, it highlights the capabilities of various experimental techniques for characterization of these materials, summarizes top-of-the-line device performance, and outlines recent trends in the further development of the field. The properties of materials based both on small molecules and on conjugated polymers are considered, and their applications in organic solar cells, photodetectors, and photorefractive devices are discussed.
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Affiliation(s)
- Oksana Ostroverkhova
- Department of Physics, Oregon State University , Corvallis, Oregon 97331, United States
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27
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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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28
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Omogo B, Gao F, Bajwa P, Kaneko M, Heyes CD. Reducing Blinking in Small Core-Multishell Quantum Dots by Carefully Balancing Confinement Potential and Induced Lattice Strain: The "Goldilocks" Effect. ACS NANO 2016; 10:4072-82. [PMID: 27058120 DOI: 10.1021/acsnano.5b06994] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
Currently, the most common way to reduce blinking in quantum dots (QDs) is accomplished by using very thick and/or perfectly crystalline CdS shells on CdSe cores. Ideally, a nontoxic material such as ZnS is preferred to be the outer material in order to reduce environmental and cytotoxic effects. Blinking suppression with multishell configurations of CdS and ZnS has been reported only for "giant" QDs of 15 nm or more. One of the main reasons for the limited progress is that the role that interfacial trap states play in blinking in these systems is not very well understood. Here, we show a "Goldilocks" effect to reduce blinking in small (∼7 nm) QDs by carefully controlling the thicknesses of the shells in multishell QDs. Furthermore, by correlating the fluorescence lifetime components with the fraction of time that a QD spends in the on-state, both with and without applying a threshold, we found evidence for two types of blinking that separately affect the average fluorescence lifetime of a single QD. A thorough characterization of the time-resolved fluorescence at the ensemble and single-particle level allowed us to propose a detailed physical model involving both short-lived interfacial trap states and long-lived surface trap states that are coupled. This model highlights a strategy of reducing QD blinking in small QDs by balancing the magnitude of the induced lattice strain, which results in the formation of interfacial trap states between the inner shell and the outer shell, and the confinement potential that determines how accessible the interfacial trap states are. The combination of reducing blinking while maintaining a small overall QD size and using a Cd-free outer shell of ZnS will be useful in a wide array of applications, particularly for advanced bioimaging.
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Affiliation(s)
- Benard Omogo
- Department of Chemistry and Biochemistry, University of Arkansas , Fayetteville, Arkansas 72701, United States
| | - Feng Gao
- Department of Chemistry and Biochemistry, University of Arkansas , Fayetteville, Arkansas 72701, United States
| | - Pooja Bajwa
- Department of Chemistry and Biochemistry, University of Arkansas , Fayetteville, Arkansas 72701, United States
| | - Mizuho Kaneko
- Department of Chemistry and Biochemistry, University of Arkansas , Fayetteville, Arkansas 72701, United States
| | - Colin D Heyes
- Department of Chemistry and Biochemistry, University of Arkansas , Fayetteville, Arkansas 72701, United States
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29
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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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30
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Chizhik AM, Stein S, Dekaliuk MO, Battle C, Li W, Huss A, Platen M, Schaap IAT, Gregor I, Demchenko AP, Schmidt CF, Enderlein J, Chizhik AI. Super-Resolution Optical Fluctuation Bio-Imaging with Dual-Color Carbon Nanodots. NANO LETTERS 2016; 16:237-42. [PMID: 26605640 DOI: 10.1021/acs.nanolett.5b03609] [Citation(s) in RCA: 71] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Success in super-resolution imaging relies on a proper choice of fluorescent probes. Here, we suggest novel easily produced and biocompatible nanoparticles-carbon nanodots-for super-resolution optical fluctuation bioimaging (SOFI). The particles revealed an intrinsic dual-color fluorescence, which corresponds to two subpopulations of particles of different electric charges. The neutral nanoparticles localize to cellular nuclei suggesting their potential use as an inexpensive, easily produced nucleus-specific label. The single particle study revealed that the carbon nanodots possess a unique hybrid combination of fluorescence properties exhibiting characteristics of both dye molecules and semiconductor nanocrystals. The results suggest that charge trapping and redistribution on the surface of the particles triggers their transitions between emissive and dark states. These findings open up new possibilities for the utilization of carbon nanodots in the various super-resolution microscopy methods based on stochastic optical switching.
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Affiliation(s)
- Anna M Chizhik
- Third Institute of Physics, Georg August University , 37077 Göttingen, Germany
| | - Simon Stein
- Third Institute of Physics, Georg August University , 37077 Göttingen, Germany
| | - Mariia O Dekaliuk
- A. V. Palladin Institute of Biochemistry, National Academy of Sciences of Ukraine , Leontovicha Street 9, Kiev 01601, Ukraine
| | - Christopher Battle
- Third Institute of Physics, Georg August University , 37077 Göttingen, Germany
| | - Weixing Li
- Third Institute of Physics, Georg August University , 37077 Göttingen, Germany
| | - Anja Huss
- Third Institute of Physics, Georg August University , 37077 Göttingen, Germany
| | - Mitja Platen
- Third Institute of Physics, Georg August University , 37077 Göttingen, Germany
| | - Iwan A T Schaap
- Third Institute of Physics, Georg August University , 37077 Göttingen, Germany
- Institute of Biological Chemistry, Biophysics and Bioengineering, Heriot Watt University , Edinburgh EH14 4A, United Kingdom
| | - Ingo Gregor
- Third Institute of Physics, Georg August University , 37077 Göttingen, Germany
| | - Alexander P Demchenko
- A. V. Palladin Institute of Biochemistry, National Academy of Sciences of Ukraine , Leontovicha Street 9, Kiev 01601, Ukraine
| | - Christoph F Schmidt
- Third Institute of Physics, Georg August University , 37077 Göttingen, Germany
| | - Jörg Enderlein
- Third Institute of Physics, Georg August University , 37077 Göttingen, Germany
| | - Alexey I Chizhik
- Third Institute of Physics, Georg August University , 37077 Göttingen, Germany
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31
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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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32
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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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33
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Meixner AJ, Jäger R, Jäger S, Bräuer A, Scherzinger K, Fulmes J, Krockhaus SZO, Gollmer DA, Kern DP, Fleischer M. Coupling single quantum dots to plasmonic nanocones: optical properties. Faraday Discuss 2015; 184:321-37. [PMID: 26404008 DOI: 10.1039/c5fd00074b] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Coupling a single quantum emitter, such as a fluorescent molecule or a quantum dot (QD), to a plasmonic nanostructure is an important issue in nano-optics and nano-spectroscopy, relevant for a wide range of applications, including tip-enhanced near-field optical microscopy, plasmon enhanced molecular sensing and spectroscopy, and nanophotonic amplifiers or nanolasers, to mention only a few. While the field enhancement of a sharp nanoantenna increasing the excitation rate of a very closely positioned single molecule or QD has been well investigated, the detailed physical mechanisms involved in the emission of a photon from such a system are, by far, less investigated. In one of our ongoing research projects, we try to address these issues by constructing and spectroscopically analysing geometrically simple hybrid heterostructures consisting of sharp gold cones with single quantum dots attached to the very tip apex. An important goal of this work is to tune the longitudinal plasmon resonance by adjusting the cones' geometry to the emission maximum of the core-shell CdSe/ZnS QDs at nominally 650 nm. Luminescence spectra of the bare cones, pure QDs and hybrid systems were distinguished successfully. In the next steps we will further investigate, experimentally and theoretically, the optical properties of the coupled systems in more detail, such as the fluorescence spectra, blinking statistics, and the current results on the fluorescence lifetimes, and compare them with uncoupled QDs to obtain a clearer picture of the radiative and non-radiative processes.
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Affiliation(s)
- Alfred J Meixner
- Center for Light-Matter Interaction, Sensors & Analytics (LISA+), Institute of Physical and Theoretical Chemistry, University of Tübingen, Auf der Morgenstelle 18, 72076 Tübingen, Germany.
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Liu J, Kilina SV, Tretiak S, Prezhdo OV. Ligands Slow Down Pure-Dephasing in Semiconductor Quantum Dots. ACS NANO 2015; 9:9106-9116. [PMID: 26284384 DOI: 10.1021/acsnano.5b03255] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
It is well-known experimentally and theoretically that surface ligands provide additional pathways for energy relaxation in colloidal semiconductor quantum dots (QDs). They increase the rate of inelastic charge-phonon scattering and provide trap sites for the charges. We show that, surprisingly, ligands have the opposite effect on elastic electron-phonon scattering. Our simulations demonstrate that elastic scattering slows down in CdSe QDs passivated with ligands compared to that in bare QDs. As a result, the pure-dephasing time is increased, and the homogeneous luminescence line width is decreased in the presence of ligands. The lifetime of quantum superpositions of single and multiple excitons increases as well, providing favorable conditions for multiple excitons generation (MEG). Ligands reduce the pure-dephasing rates by decreasing phonon-induced fluctuations of the electronic energy levels. Surface atoms are most mobile in QDs, and therefore, they contribute greatly to the electronic energy fluctuations. The mobility is reduced by interaction with ligands. A simple analytical model suggests that the differences between the bare and passivated QDs persist for up to 5 nm diameters. Both low-frequency acoustic and high-frequency optical phonons participate in the dephasing processes in bare QDs, while low-frequency acoustic modes dominate in passivated QDs. The theoretical predictions regarding the pure-dephasing time, luminescence line width, and MEG can be verified experimentally by studying QDs with different surface passivation.
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Affiliation(s)
- Jin Liu
- Department of Chemical Engineering, University of Rochester , Rochester, New York 14627, United States
| | - Svetlana V Kilina
- Department of Chemistry, North Dakota State University , Fargo, North Dakota 58108, United States
| | - Sergei Tretiak
- Los Alamos National Laboratory , Los Alamos, New Mexico 87545, United States
| | - Oleg V Prezhdo
- Department of Chemistry, University of Southern California , Los Angeles, California 90089, United States
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35
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Shchukina AL, Eremchev IY, Naumov AV. Looking at a blinking quantum emitter through time slots: the effect of blind times. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2015; 92:032102. [PMID: 26465421 DOI: 10.1103/physreve.92.032102] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/18/2015] [Indexed: 06/05/2023]
Abstract
Most experimental observations of physical processes are naturally accompanied by "blind" ("dead") times, which in principle can distort the result of measurements. Here we analyze how the presence of blind times in measurements changes the measured statistics of blinking fluorescence of single quantum dots. We show that information can be extracted even for blinking processes with characteristic times longer than both blind times and time slots between them.
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Affiliation(s)
- A L Shchukina
- Center of New Technologies, University of Warsaw, 02-097 Warsaw, Poland
- Institute for Spectroscopy of Russian Academy of Sciences, Troitsk, 142910 Moscow, Russia
| | - I Yu Eremchev
- Institute for Spectroscopy of Russian Academy of Sciences, Troitsk, 142910 Moscow, Russia
| | - A V Naumov
- Institute for Spectroscopy of Russian Academy of Sciences, Troitsk, 142910 Moscow, Russia
- Moscow State Pedagogical University, 119991 Moscow, Russia
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36
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Tovstun SA, Razumov VF. A method for calculating the parameters of Förster resonance energy transfer in nanoclusters of colloidal quantum dots from data on their photoluminescence: an account of fluorescence intermittency. HIGH ENERGY CHEMISTRY 2015. [DOI: 10.1134/s0018143915040189] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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37
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Zenkevich E, Stupak A, Göhler C, Krasselt C, von Borczyskowski C. Tuning electronic states of a CdSe/ZnS quantum dot by only one functional dye molecule. ACS NANO 2015; 9:2886-2903. [PMID: 25703788 DOI: 10.1021/nn506941c] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Self-assembly of only one functionalized porphyrin dye molecule with one CdSe/ZnS quantum dot (QD) not only modifies the photoluminescence (PL) intensity but also creates a few energetically clearly distinguishable electronic states, opening additional effective relaxation pathways. The related energy modifications are in the range of 10-30 meV and show a pronounced sensitivity to the specific nature of the respective dye. We assign the emerging energies to surface states. Time-resolved PL spectroscopy in combination with spectral deconvolution reveals that surface properties of QDs are a complex interplay of the nature of the dye molecule and the topography of the ligand layer across a temperature range from 77 to 290 K. This includes a kind of phase transition of trioctylphosphine oxide ligands, switching the nature of surface states observed below and above the phase transition temperature. Most importantly, our findings can be closely related to recent calculations of ligand-induced modifications of surface states of QDs. The identification of the optical properties emerged from a combination of spectroscopy on single QDs and QDs in an ensemble.
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Affiliation(s)
- Eduard Zenkevich
- †Department of Information Technologies and Robotics, National Technical University of Belarus, Nezavisimosti Ave., 65, 220013 Minsk, Belarus
| | - Aleksander Stupak
- ‡B.I. Stepanov Institute of Physics, National Academy of Science of Belarus, Nezavisimosti Ave., 70, 220072 Minsk, Belarus
| | - Clemens Göhler
- §Institute of Physics, Technische Universität Chemnitz, Reichenhainerstr. 70, 09107 Chemnitz, Germany
| | - Cornelius Krasselt
- §Institute of Physics, Technische Universität Chemnitz, Reichenhainerstr. 70, 09107 Chemnitz, Germany
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38
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Hess CM, Riley EA, Reid PJ. Dielectric dependence of single-molecule photoluminescence intermittency: nile red in poly(vinylidene fluoride). J Phys Chem B 2014; 118:8905-13. [PMID: 24995904 PMCID: PMC4372109 DOI: 10.1021/jp505874m] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
![]()
The
dependence of single-molecule photoluminescence intermittency
(PI) or “blinking” on the local dielectric constant
(ε) is examined for nile red (NR) in thin films of poly(vinylidene
fluoride) (PVDF). In previous studies, variation of the local dielectric
constant was accomplished by studying luminophores in chemically and
structurally different hosts. In contrast, the NR/PVDF guest–host
pair allows for the investigation of PI as a function of ε while
keeping the chemical composition of both the luminophore and host
unchanged. The solvatochromic properties of NR are used to measure
the local ε, while fluctuations in NR emission intensity over
time provide a measure of the PI. PVDF is an ideal host for this study
because it provides submicron-sized dielectric domains that vary from
nonpolar (ε ≈ 2) to very polar (ε ≈ 70).
The results presented here demonstrate that the local dielectric environment
can have a pronounced effect on PI. We find that the NR emissive events
increase 5-fold with an increase in ε from 2.2 to 74. A complex
dependence on ε is also observed for NR nonemissive event durations,
initially increasing as ε increases from 2.2 to 3.4 but decreasing
in duration with further increase in ε. The variation in emissive
event durations with ε is reproduced using a photoinduced electron-transfer
model involving electron transfer from NR to PVDF. In addition, an
increase in NR photostability with an increase in ε is observed,
suggesting that the dielectric environment plays an important role
in defining the photostability of NR in PVDF.
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Affiliation(s)
- Chelsea M Hess
- Department of Chemistry, University of Washington , Box 351700, Seattle, Washington 98195, United States
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