1
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Nguyen HA, Dixon G, Dou FY, Gallagher S, Gibbs S, Ladd DM, Marino E, Ondry JC, Shanahan JP, Vasileiadou ES, Barlow S, Gamelin DR, Ginger DS, Jonas DM, Kanatzidis MG, Marder SR, Morton D, Murray CB, Owen JS, Talapin DV, Toney MF, Cossairt BM. Design Rules for Obtaining Narrow Luminescence from Semiconductors Made in Solution. Chem Rev 2023. [PMID: 37311205 DOI: 10.1021/acs.chemrev.3c00097] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Solution-processed semiconductors are in demand for present and next-generation optoelectronic technologies ranging from displays to quantum light sources because of their scalability and ease of integration into devices with diverse form factors. One of the central requirements for semiconductors used in these applications is a narrow photoluminescence (PL) line width. Narrow emission line widths are needed to ensure both color and single-photon purity, raising the question of what design rules are needed to obtain narrow emission from semiconductors made in solution. In this review, we first examine the requirements for colloidal emitters for a variety of applications including light-emitting diodes, photodetectors, lasers, and quantum information science. Next, we will delve into the sources of spectral broadening, including "homogeneous" broadening from dynamical broadening mechanisms in single-particle spectra, heterogeneous broadening from static structural differences in ensemble spectra, and spectral diffusion. Then, we compare the current state of the art in terms of emission line width for a variety of colloidal materials including II-VI quantum dots (QDs) and nanoplatelets, III-V QDs, alloyed QDs, metal-halide perovskites including nanocrystals and 2D structures, doped nanocrystals, and, finally, as a point of comparison, organic molecules. We end with some conclusions and connections, including an outline of promising paths forward.
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Affiliation(s)
- Hao A Nguyen
- Department of Chemistry, University of Washington, Seattle, Washington 98195-1700, United States
| | - Grant Dixon
- Department of Chemistry, University of Washington, Seattle, Washington 98195-1700, United States
| | - Florence Y Dou
- Department of Chemistry, University of Washington, Seattle, Washington 98195-1700, United States
| | - Shaun Gallagher
- Department of Chemistry, University of Washington, Seattle, Washington 98195-1700, United States
| | - Stephen Gibbs
- Department of Chemistry, University of Washington, Seattle, Washington 98195-1700, United States
| | - Dylan M Ladd
- Department of Materials Science and Engineering, University of Colorado Boulder, Boulder, Colorado 80303, United States
| | - Emanuele Marino
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
- Dipartimento di Fisica e Chimica, Università degli Studi di Palermo, Via Archirafi 36, 90123 Palermo, Italy
| | - Justin C Ondry
- Department of Chemistry, James Franck Institute, and Pritzker School of Molecular Engineering, University of Chicago, Chicago, Illinois 60637, United States
| | - James P Shanahan
- Department of Chemistry, Columbia University, New York, New York 10027, United States
| | - Eugenia S Vasileiadou
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States
| | - Stephen Barlow
- Renewable and Sustainable Energy Institute, University of Colorado Boulder, Boulder, Colorado 80303, United States
| | - Daniel R Gamelin
- Department of Chemistry, University of Washington, Seattle, Washington 98195-1700, United States
| | - David S Ginger
- Department of Chemistry, University of Washington, Seattle, Washington 98195-1700, United States
| | - David M Jonas
- Department of Chemistry, University of Colorado Boulder, Boulder, Colorado 80309, United States
- Renewable and Sustainable Energy Institute, University of Colorado Boulder, Boulder, Colorado 80303, United States
| | - Mercouri G Kanatzidis
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States
| | - Seth R Marder
- Department of Chemistry, University of Colorado Boulder, Boulder, Colorado 80309, United States
- Renewable and Sustainable Energy Institute, University of Colorado Boulder, Boulder, Colorado 80303, United States
- Department of Chemical and Biological Engineering, University of Colorado Boulder, Boulder, Colorado 80303, United States
| | - Daniel Morton
- Renewable and Sustainable Energy Institute, University of Colorado Boulder, Boulder, Colorado 80303, United States
| | - Christopher B Murray
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Jonathan S Owen
- Department of Chemistry, Columbia University, New York, New York 10027, United States
| | - Dmitri V Talapin
- Department of Chemistry, James Franck Institute, and Pritzker School of Molecular Engineering, University of Chicago, Chicago, Illinois 60637, United States
| | - Michael F Toney
- Department of Materials Science and Engineering, University of Colorado Boulder, Boulder, Colorado 80303, United States
- Renewable and Sustainable Energy Institute, University of Colorado Boulder, Boulder, Colorado 80303, United States
- Department of Chemical and Biological Engineering, University of Colorado Boulder, Boulder, Colorado 80303, United States
| | - Brandi M Cossairt
- Department of Chemistry, University of Washington, Seattle, Washington 98195-1700, United States
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2
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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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3
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Dynamic lattice distortions driven by surface trapping in semiconductor nanocrystals. Nat Commun 2021; 12:1860. [PMID: 33767138 PMCID: PMC7994579 DOI: 10.1038/s41467-021-22116-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2020] [Accepted: 02/04/2021] [Indexed: 01/18/2023] Open
Abstract
Nonradiative processes limit optoelectronic functionality of nanocrystals and curb their device performance. Nevertheless, the dynamic structural origins of nonradiative relaxations in such materials are not understood. Here, femtosecond electron diffraction measurements corroborated by atomistic simulations uncover transient lattice deformations accompanying radiationless electronic processes in colloidal semiconductor nanocrystals. Investigation of the excitation energy dependence in a core/shell system shows that hot carriers created by a photon energy considerably larger than the bandgap induce structural distortions at nanocrystal surfaces on few picosecond timescales associated with the localization of trapped holes. On the other hand, carriers created by a photon energy close to the bandgap of the core in the same system result in transient lattice heating that occurs on a much longer 200 picosecond timescale, dominated by an Auger heating mechanism. Elucidation of the structural deformations associated with the surface trapping of hot holes provides atomic-scale insights into the mechanisms deteriorating optoelectronic performance and a pathway towards minimizing these losses in nanocrystal devices. Charge trapping can lead to severe nonradiative losses in colloidal semiconductor nanocrystals (NCs). The authors report femtosecond electron diffraction measurements on photoexcited NCs to reveal atomic-scale insights into how localization of charges at trap sites induce surface deformations.
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4
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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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5
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Zhao B, Zhu L, Sun L, Wang S, Lu J, Zhang J, Han Q, Dong H, Tang B, Zhou B, Liu F, Shen X, Lu W. Strong fluorescence blinking of large-size all-inorganic perovskite nano-spheres. NANOTECHNOLOGY 2020; 31:215204. [PMID: 32015226 DOI: 10.1088/1361-6528/ab7250] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
We demonstrated strong fluorescence blinking on large all-inorganic perovskite (CsPbBr3) nano-spheres. By performing (time-resolved) micro-photoluminescence (μ-PL) measurements, the unique blinking characteristics of the as-grown nano-spheres with diameters of hundred nanometers, are clearly observed. Blinking has no obvious on/off states, which is different from the blinking characteristics of quantum dots. It is believed that the blinking of fluorescence is caused by metastable defect-induced trapping of carriers on the surface of the nano-spheres, because dramatically suppressed fluorescence blinking and the decay rates of ultrafast carriers are realized by surface passivation of the nano-spheres. Surface defects are closely related to the ambient atmosphere, which has been further confirmed by PL measurements of the as-grown nano-spheres in vacuum. Additionally, we also found that the fluorescence blinking was significantly suppressed as the sample size increased, which can be attributed to the large-size induced average effect on fluorescence blinking. These results may be important for understanding the mechanism of the fluorescence blinking of perovskite materials and for developing optical devices with good fluorescence stability.
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Affiliation(s)
- Binbin Zhao
- Department of Physics, Shanghai Normal University, Shanghai, 200234, People's Republic of China. State Key Laboratory of Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai, 200083, People's Republic of China
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6
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Ostarcevic ER, Jacangelo J, Gray SR, Cran MJ. Current and Emerging Techniques for High-Pressure Membrane Integrity Testing. MEMBRANES 2018; 8:E60. [PMID: 30096937 PMCID: PMC6161006 DOI: 10.3390/membranes8030060] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/21/2018] [Revised: 08/03/2018] [Accepted: 08/06/2018] [Indexed: 01/28/2023]
Abstract
Ideally, pressure driven membrane processes used in wastewater treatment such as reverse osmosis and nanofiltration should provide a complete physical barrier to the passage of pathogens such as enteric viruses. In reality, manufacturing imperfections combined with membrane ageing and damage can result in breaches as small as 20 to 30 nm in diameter, sufficient to allow enteric viruses to contaminate the treated water and compromise public health. In addition to continuous monitoring, frequent demonstration of the integrity of membranes is required to provide assurance that the barrier to the passage of such contaminants is intact. Existing membrane integrity monitoring systems, however, are limited and health regulators typically credit high-pressure membrane systems with only 2 log10 virus rejection, well below their capability. A reliable real-time method that can recognize the true rejection potential of membrane systems greater than 4 log10 has not yet been established. This review provides a critical evaluation of the current methods of integrity monitoring and identifies novel approaches that have the potential to provide accurate, representative virus removal efficiency estimates.
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Affiliation(s)
- Eddy R Ostarcevic
- Institute for Sustainable Industries and Liveable Cities, Victoria University, Werribee 3030, Australia.
| | | | - Stephen R Gray
- Institute for Sustainable Industries and Liveable Cities, Victoria University, Werribee 3030, Australia.
| | - Marlene J Cran
- Institute for Sustainable Industries and Liveable Cities, Victoria University, Werribee 3030, Australia.
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7
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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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8
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Groß H, Hamm JM, Tufarelli T, Hess O, Hecht B. Near-field strong coupling of single quantum dots. SCIENCE ADVANCES 2018; 4:eaar4906. [PMID: 29511739 PMCID: PMC5837425 DOI: 10.1126/sciadv.aar4906] [Citation(s) in RCA: 79] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/14/2017] [Accepted: 01/30/2018] [Indexed: 05/10/2023]
Abstract
Strong coupling and the resultant mixing of light and matter states is an important asset for future quantum technologies. We demonstrate deterministic room temperature strong coupling of a mesoscopic colloidal quantum dot to a plasmonic nanoresonator at the apex of a scanning probe. Enormous Rabi splittings of up to 110 meV are accomplished by nanometer-precise positioning of the quantum dot with respect to the nanoresonator probe. We find that, in addition to a small mode volume of the nanoresonator, collective coherent coupling of quantum dot band-edge states and near-field proximity interaction are vital ingredients for the realization of near-field strong coupling of mesoscopic quantum dots. The broadband nature of the interaction paves the road toward ultrafast coherent manipulation of the coupled quantum dot-plasmon system under ambient conditions.
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Affiliation(s)
- Heiko Groß
- Nano-Optics and Biophotonics Group, Experimentelle Physik 5 and Röntgen Research Center for Complex Material Systems, Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Joachim M. Hamm
- The Blackett Laboratory, Department of Physics, Imperial College London, London SW7 2AZ, UK
| | - Tommaso Tufarelli
- The Blackett Laboratory, Department of Physics, Imperial College London, London SW7 2AZ, UK
| | - Ortwin Hess
- The Blackett Laboratory, Department of Physics, Imperial College London, London SW7 2AZ, UK
- Corresponding author. (B.H.); (O.H.)
| | - Bert Hecht
- Nano-Optics and Biophotonics Group, Experimentelle Physik 5 and Röntgen Research Center for Complex Material Systems, Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
- Corresponding author. (B.H.); (O.H.)
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9
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Yuan G, Gómez D, Kirkwood N, Mulvaney P. Tuning Single Quantum Dot Emission with a Micromirror. NANO LETTERS 2018; 18:1010-1017. [PMID: 29302972 DOI: 10.1021/acs.nanolett.7b04482] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The photoluminescence of single quantum dots fluctuates between bright (on) and dark (off) states, also termed fluorescence intermittency or blinking. This blinking limits the performance of quantum dot-based devices such as light-emitting diodes and solar cells. However, the origins of the blinking remain unresolved. Here, we use a movable gold micromirror to determine both the quantum yield of the bright state and the orientation of the excited state dipole of single quantum dots. We observe that the quantum yield of the bright state is close to unity for these single QDs. Furthermore, we also study the effect of a micromirror on blinking, and then evaluate excitation efficiency, biexciton quantum yield, and detection efficiency. The mirror does not modify the off-time statistics, but it does change the density of optical states available to the quantum dot and hence the on times. The duration of the on times can be lengthened due to an increase in the radiative recombination rate.
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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
| | - Daniel Gómez
- School of Chemical Sciences, RMIT University , Melbourne, Victoria 3001, Australia
| | - Nicholas Kirkwood
- 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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10
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Pietryga JM, Park YS, Lim J, Fidler AF, Bae WK, Brovelli S, Klimov VI. Spectroscopic and Device Aspects of Nanocrystal Quantum Dots. Chem Rev 2017; 116:10513-622. [PMID: 27677521 DOI: 10.1021/acs.chemrev.6b00169] [Citation(s) in RCA: 394] [Impact Index Per Article: 56.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The field of nanocrystal quantum dots (QDs) is already more than 30 years old, and yet continuing interest in these structures is driven by both the fascinating physics emerging from strong quantum confinement of electronic excitations, as well as a large number of prospective applications that could benefit from the tunable properties and amenability toward solution-based processing of these materials. The focus of this review is on recent advances in nanocrystal research related to applications of QD materials in lasing, light-emitting diodes (LEDs), and solar energy conversion. A specific underlying theme is innovative concepts for tuning the properties of QDs beyond what is possible via traditional size manipulation, particularly through heterostructuring. Examples of such advanced control of nanocrystal functionalities include the following: interface engineering for suppressing Auger recombination in the context of QD LEDs and lasers; Stokes-shift engineering for applications in large-area luminescent solar concentrators; and control of intraband relaxation for enhanced carrier multiplication in advanced QD photovoltaics. We examine the considerable recent progress on these multiple fronts of nanocrystal research, which has resulted in the first commercialized QD technologies. These successes explain the continuing appeal of this field to a broad community of scientists and engineers, which in turn ensures even more exciting results to come from future exploration of this fascinating class of materials.
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Affiliation(s)
- Jeffrey M Pietryga
- Nanotechnology and Advanced Spectroscopy Team, Chemistry Division, Los Alamos National Laboratory , Los Alamos, New Mexico 87545, United States
| | - Young-Shin Park
- Nanotechnology and Advanced Spectroscopy Team, Chemistry Division, Los Alamos National Laboratory , Los Alamos, New Mexico 87545, United States.,Center for High Technology Materials, University of New Mexico , Albuquerque, New Mexico 87131, United States
| | - Jaehoon Lim
- Nanotechnology and Advanced Spectroscopy Team, Chemistry Division, Los Alamos National Laboratory , Los Alamos, New Mexico 87545, United States
| | - Andrew F Fidler
- Nanotechnology and Advanced Spectroscopy Team, Chemistry Division, Los Alamos National Laboratory , Los Alamos, New Mexico 87545, United States
| | - Wan Ki Bae
- Photo-Electronic Hybrids Research Center, Korea Institute of Science and Technology , Seoul 02792, Korea
| | - Sergio Brovelli
- Dipartimento di Scienza dei Materiali, Università degli Studi di Milano-Bicocca , I-20125 Milano, Italy
| | - Victor I Klimov
- Nanotechnology and Advanced Spectroscopy Team, Chemistry Division, Los Alamos National Laboratory , Los Alamos, New Mexico 87545, United States
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11
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Geißler D, Würth C, Wolter C, Weller H, Resch-Genger U. Excitation wavelength dependence of the photoluminescence quantum yield and decay behavior of CdSe/CdS quantum dot/quantum rods with different aspect ratios. Phys Chem Chem Phys 2017; 19:12509-12516. [DOI: 10.1039/c7cp02142a] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Our results reveal a strong λexc-dependence of PL quantum yields and decay times, particularly for longer quantum dot-quantum rods with high aspect ratios.
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Affiliation(s)
- D. Geißler
- Federal Institute for Materials Research and Testing (BAM)
- Berlin
- Germany
| | - C. Würth
- Federal Institute for Materials Research and Testing (BAM)
- Berlin
- Germany
| | - C. Wolter
- University of Hamburg
- Institute of Physical Chemistry
- Hamburg
- Germany
| | - H. Weller
- University of Hamburg
- Institute of Physical Chemistry
- Hamburg
- Germany
| | - U. Resch-Genger
- Federal Institute for Materials Research and Testing (BAM)
- Berlin
- Germany
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12
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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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13
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Hu F, Yin C, Zhang H, Sun C, Yu WW, Zhang C, Wang X, Zhang Y, Xiao M. Slow Auger Recombination of Charged Excitons in Nonblinking Perovskite Nanocrystals without Spectral Diffusion. NANO LETTERS 2016; 16:6425-6430. [PMID: 27689439 DOI: 10.1021/acs.nanolett.6b02874] [Citation(s) in RCA: 81] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Over the last two decades, intensive research efforts have been devoted to the suppressions of photoluminescence (PL) blinking and Auger recombination in metal-chalcogenide nanocrystals (NCs), with significant progresses being made only very recently in few specific NC structures. Here we show that nonblinking PL is readily available in the newly synthesized perovskite CsPbI3 NCs and that their Auger recombination of charged excitons is greatly slowed down, as signified by a PL lifetime about twice shorter than that of neutral excitons. Moreover, spectral diffusion is completely absent in single CsPbI3 NCs at the cryogenic temperature, leading to a resolution-limited PL line width of ∼200 μeV.
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Affiliation(s)
- Fengrui Hu
- National Laboratory of Solid State Microstructures, School of Physics, and Collaborative Innovation Center of Advanced Microstructures, Nanjing University , Nanjing 210093, China
| | - Chunyang Yin
- National Laboratory of Solid State Microstructures, School of Physics, and Collaborative Innovation Center of Advanced Microstructures, Nanjing University , Nanjing 210093, China
| | - Huichao Zhang
- National Laboratory of Solid State Microstructures, School of Physics, and Collaborative Innovation Center of Advanced Microstructures, Nanjing University , Nanjing 210093, China
- College of Electronics and Information, Hangzhou Dianzi University , Xiasha Campus, Hangzhou 310018, China
| | - Chun Sun
- State Key Laboratory on Integrated Optoelectronics and College of Electronic Science and Engineering, Jilin University , Changchun 130012, China
| | - William W Yu
- State Key Laboratory on Integrated Optoelectronics and College of Electronic Science and Engineering, Jilin University , Changchun 130012, China
| | - Chunfeng Zhang
- National Laboratory of Solid State Microstructures, School of Physics, and Collaborative Innovation Center of Advanced Microstructures, Nanjing University , Nanjing 210093, China
| | - Xiaoyong Wang
- National Laboratory of Solid State Microstructures, School of Physics, and Collaborative Innovation Center of Advanced Microstructures, Nanjing University , Nanjing 210093, China
| | - Yu Zhang
- State Key Laboratory on Integrated Optoelectronics and College of Electronic Science and Engineering, Jilin University , Changchun 130012, China
| | - Min Xiao
- National Laboratory of Solid State Microstructures, School of Physics, and Collaborative Innovation Center of Advanced Microstructures, Nanjing University , Nanjing 210093, China
- Department of Physics, University of Arkansas , Fayetteville, Arkansas 72701, United States
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14
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Lim SJ, Ma L, Schleife A, Smith AM. Quantum Dot Surface Engineering: Toward Inert Fluorophores with Compact Size and Bright, Stable Emission. Coord Chem Rev 2016; 320-321:216-237. [PMID: 28344357 PMCID: PMC5363762 DOI: 10.1016/j.ccr.2016.03.012] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The surfaces of colloidal nanocrystals are complex interfaces between solid crystals, coordinating ligands, and liquid solutions. For fluorescent quantum dots, the properties of the surface vastly influence the efficiency of light emission, stability, and physical interactions, and thus determine their sensitivity and specificity when they are used to detect and image biological molecules. But after more than 30 years of study, the surfaces of quantum dots remain poorly understood and continue to be an important subject of both experimental and theoretical research. In this article, we review the physics and chemistry of quantum dot surfaces and describe approaches to engineer optimal fluorescent probes for applications in biomolecular imaging and sensing. We describe the structure and electronic properties of crystalline facets, the chemistry of ligand coordination, and the impact of ligands on optical properties. We further describe recent advances in compact coatings that have significantly improved their properties by providing small hydrodynamic size, high stability and fluorescence efficiency, and minimal nonspecific interactions with cells and biological molecules. While major progress has been made in both basic and applied research, many questions remain in the chemistry and physics of quantum dot surfaces that have hindered key breakthroughs to fully optimize their properties.
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Affiliation(s)
- Sung Jun Lim
- Micro and Nanotechnology Laboratory, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
- Department of Bioengineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
| | - Liang Ma
- Micro and Nanotechnology Laboratory, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
- Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
| | - André Schleife
- Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
| | - Andrew M. Smith
- Micro and Nanotechnology Laboratory, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
- Department of Bioengineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
- Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
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15
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Gao Y, Yu G, Wang Y, Dang C, Sum TC, Sun H, Demir HV. Green Stimulated Emission Boosted by Nonradiative Resonant Energy Transfer from Blue Quantum Dots. J Phys Chem Lett 2016; 7:2772-2778. [PMID: 27388758 DOI: 10.1021/acs.jpclett.6b01122] [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
Thanks to their tunability and versatility, the colloidal quantum dots (CQDs) made of II-VI semiconductor compound offer the potential to bridge the "green gap" in conventional semiconductors. However, when the CQDs are pumped to much higher initial excitonic states compared to their bandgap, multiexciton interaction is enhanced, leading to a much higher stimulated emission threshold. Here, to circumvent this drawback, for the first time, we show a fully colloidal gain in green enabled by a partially indirect pumping approach assisted by Förster resonance energy transfer process. By introducing the blue CQDs as exciton donors, the lasing threshold of the green CQDs, is reduced dramatically. The blue CQDs thus serve as an energy-transferring buffer medium to reduce excitation energy from pumping photons in a controlled way by injecting photoinduced excitons into green CQDs. Our newly developed colloidal pumping scheme could enable efficient CQD lasers of full visible colors by a single pump source and cascaded exciton transfer. This would potentially pave the way for an efficient multicolor laser for lighting and display applications.
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Affiliation(s)
- Yuan Gao
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University , 21 Nanyang Link, 637371, Singapore
- LUMINOUS! Center of Excellence for Semiconductor Lighting and Displays, School of Electrical and Electronic Engineering and The Photonics Institute, Nanyang Technological University , 50 Nanyang Avenue, 639798, Singapore
| | - Guannan Yu
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University , 21 Nanyang Link, 637371, Singapore
| | - Yue Wang
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University , 21 Nanyang Link, 637371, Singapore
| | - Cuong Dang
- LUMINOUS! Center of Excellence for Semiconductor Lighting and Displays, School of Electrical and Electronic Engineering and The Photonics Institute, Nanyang Technological University , 50 Nanyang Avenue, 639798, Singapore
| | - Tze Chien Sum
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University , 21 Nanyang Link, 637371, Singapore
| | - Handong Sun
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University , 21 Nanyang Link, 637371, Singapore
- LUMINOUS! Center of Excellence for Semiconductor Lighting and Displays, School of Electrical and Electronic Engineering and The Photonics Institute, Nanyang Technological University , 50 Nanyang Avenue, 639798, Singapore
| | - Hilmi Volkan Demir
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University , 21 Nanyang Link, 637371, Singapore
- LUMINOUS! Center of Excellence for Semiconductor Lighting and Displays, School of Electrical and Electronic Engineering and The Photonics Institute, Nanyang Technological University , 50 Nanyang Avenue, 639798, Singapore
- Department of Electrical and Electronics Engineering and Department of Physics, UNAM - Institute of Materials Science and Nanotechnology, Bilkent University , 06800 Bilkent, Ankara, Turkey
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16
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Sharma DK, Hirata S, Bujak L, Biju V, Kameyama T, Kishi M, Torimoto T, Vacha M. Single-particle spectroscopy of I-III-VI semiconductor nanocrystals: spectral diffusion and suppression of blinking by two-color excitation. NANOSCALE 2016; 8:13687-94. [PMID: 27376712 DOI: 10.1039/c6nr03950b] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Ternary I-III-VI semiconductor nanocrystals have been explored as non-toxic alternatives to II-VI semiconductors for optoelectronic and sensing applications, but large photoluminescence spectral width and moderate brightness restrict their practical use. Here, using single-particle photoluminescence spectroscopy on nanocrystals of (AgIn)xZn2(1-x)S2 we show that the photoluminescence band is inhomogeneously broadened and that size distribution is the dominant factor in the broadening. The residual homogeneous linewidth of individual nanocrystals reaches up to 75% of the ensemble spectral width. Single nanocrystals undergo spectral diffusion which also contributes to the inhomogeneous band. Excitation with two lasers with energies above and below the bandgap reveals coexistence of two emitting donor states within one particle. Spectral diffusion in such particles is due to temporal activation and deactivation of one such state. Filling of a trap state with a lower-energy laser enables optical modulation of photoluminescence intermittency (blinking) and leads to an almost two-fold increase in brightness.
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Affiliation(s)
- Dharmendar Kumar Sharma
- Department of Materials Science and Engineering, Tokyo Institute of Technology, Ookayama 2-12-1-S8-44, Meguro-ku, Tokyo 152-8552, Japan.
| | - Shuzo Hirata
- Department of Materials Science and Engineering, Tokyo Institute of Technology, Ookayama 2-12-1-S8-44, Meguro-ku, Tokyo 152-8552, Japan.
| | - Lukasz Bujak
- Department of Materials Science and Engineering, Tokyo Institute of Technology, Ookayama 2-12-1-S8-44, Meguro-ku, Tokyo 152-8552, Japan.
| | - Vasudevanpillai Biju
- Research Institute for Electronic Science, Hokkaido University, N20W10, Kita Ward, Sapporo 001-0020, Japan
| | - Tatsuya Kameyama
- Department of Crystalline Materials Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603, Japan
| | - Marino Kishi
- Department of Crystalline Materials Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603, Japan
| | - Tsukasa Torimoto
- Department of Crystalline Materials Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603, Japan
| | - Martin Vacha
- Department of Materials Science and Engineering, Tokyo Institute of Technology, Ookayama 2-12-1-S8-44, Meguro-ku, Tokyo 152-8552, Japan.
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17
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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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18
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Hu F, Lv B, Yin C, Zhang C, Wang X, Lounis B, Xiao M. Carrier Multiplication in a Single Semiconductor Nanocrystal. PHYSICAL REVIEW LETTERS 2016; 116:106404. [PMID: 27015498 DOI: 10.1103/physrevlett.116.106404] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/11/2015] [Indexed: 06/05/2023]
Abstract
To confirm the existence of the carrier multiplication (CM) effect and estimate its generation efficiency of multiple excitons in semiconductor nanocrystals (NCs), it is imperative to completely exclude the false contribution of charged excitons from the measured CM signal. Here we place single CdSe NCs above an aluminum film and successfully resolve their UV-excited photoluminescence (PL) time trajectories where the true and false CM signals are contained in the blinking "on" and "off" levels, respectively. By analyzing the PL dynamics of the on-level photons, an average CM efficiency of ∼20.2% can be reliably estimated when the UV photon energy is ∼2.46 times the NC energy gap.
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Affiliation(s)
- Fengrui Hu
- National Laboratory of Solid State Microstructures, School of Physics, and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
| | - Bihu Lv
- National Laboratory of Solid State Microstructures, School of Physics, and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
| | - Chunyang Yin
- National Laboratory of Solid State Microstructures, School of Physics, and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
| | - Chunfeng Zhang
- National Laboratory of Solid State Microstructures, School of Physics, and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
| | - Xiaoyong Wang
- National Laboratory of Solid State Microstructures, School of Physics, and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
| | - Brahim Lounis
- Laboratoire Photonique Numérique et Nanosciences, Université de Bordeaux, Institut d'Optique Graduate School and CNRS, Talence 33405, France
| | - Min Xiao
- National Laboratory of Solid State Microstructures, School of Physics, and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
- Department of Physics, University of Arkansas, Fayetteville, Arkansas 72701, USA
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19
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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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20
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Jin Z, Owour P, Lei S, Ge L. Graphene, graphene quantum dots and their applications in optoelectronics. Curr Opin Colloid Interface Sci 2015. [DOI: 10.1016/j.cocis.2015.11.007] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
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21
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Whitcomb KJ, Geisenhoff JQ, Ryan DP, Gelfand MP, Van Orden A. Photon Antibunching in Small Clusters of CdSe/ZnS Core/Shell Quantum Dots. J Phys Chem B 2015; 119:9020-8. [PMID: 25232642 DOI: 10.1021/jp5083856] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Coincident photon histogram measurements of fluorescence antibunching via confocal microscopy correlated with atomic force microscopy were carried out on (i) individual CdSe/ZnS core/shell quantum dots (QDs), (ii) several well separated QDs, and (iii) clusters of QDs. Individual QDs and well separated QDs showed the expected degree of antibunching for a single emitter and several independent emitters, respectively. The degree of antibunching in small, compact clusters was more characteristic of a single emitter than multiple emitters. The antibunching in clusters provides strong evidence of nonradiative energy transfer between QDs in a cluster. A minimal phenomenological model of energy transfer gives reasonable quantitative agreement with the experimental results.
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Affiliation(s)
- Kevin J Whitcomb
- †Department of Chemistry and ‡Department of Physics, Colorado State University, Fort Collins, Colorado 80523, United States
| | - Jessica Q Geisenhoff
- †Department of Chemistry and ‡Department of Physics, Colorado State University, Fort Collins, Colorado 80523, United States
| | - Duncan P Ryan
- †Department of Chemistry and ‡Department of Physics, Colorado State University, Fort Collins, Colorado 80523, United States
| | - Martin P Gelfand
- †Department of Chemistry and ‡Department of Physics, Colorado State University, Fort Collins, Colorado 80523, United States
| | - Alan Van Orden
- †Department of Chemistry and ‡Department of Physics, Colorado State University, Fort Collins, Colorado 80523, United States
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22
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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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23
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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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24
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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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25
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Shibu ES, Hamada M, Nakanishi S, Wakida SI, Biju V. Photoluminescence of CdSe and CdSe/ZnS quantum dots: Modifications for making the invisible visible at ensemble and single-molecule levels. Coord Chem Rev 2014. [DOI: 10.1016/j.ccr.2013.10.014] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
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26
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Early KT, Nesbitt DJ. Size-dependent photoionization in single CdSe/ZnS nanocrystals. NANO LETTERS 2013; 13:4844-4849. [PMID: 24020423 DOI: 10.1021/nl402607a] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Fluorescence intermittency in single semiconductor nanocrystals has been shown to follow power law statistics over many decades in time and in probability. Recently, several studies have shown that, while "off" dwell times are insensitive to almost all experimental parameters, "on" dwell times exhibit a pump-power dependent exponential truncation at long times, suggestive of enhanced biexciton photoionization probabilities at high excitation powers. Here we report the dependence of this on-time truncation on nanocrystal radius. We observe a decrease in the per-pulse photoionization probability from 1.8(2) × 10(-4) to 2.0(7) × 10(-6) as the CdSe core radius increases from 1.3 to 3.5 nm, with a radius scaling for the probability for charge ejection arising from biexciton formation P(ionize)(r) is proportional to 1/r(3.5(5)). Effective mass calculations of the exciton wave functions show that the product of fractional electron and hole probabilities in the trap-rich ZnS shell scale similarly with nanocrystal radius. Possible charge ejection mechanisms from such a surface-localized state are discussed.
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Affiliation(s)
- Kevin T Early
- JILA, National Institute of Standards and Technology and University of Colorado, Department of Chemistry and Biochemistry, University of Colorado Boulder , Boulder, Colorado 80309, United States
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27
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Nguyen KT, Li D, Borah P, Ma X, Liu Z, Zhu L, Grüner G, Xiong Q, Zhao Y. Photoinduced charge transfer within polyaniline-encapsulated quantum dots decorated on graphene. ACS APPLIED MATERIALS & INTERFACES 2013; 5:8105-8110. [PMID: 23855339 DOI: 10.1021/am402182z] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
A new method to enhance the stability of quantum dots (QDs) in aqueous solution by encapsulating them with conducting polymer polyaniline was reported. The polyaniline-encapsulated QDs were then decorated onto graphene through π-π interactions between graphene and conjugated polymer shell of QDs, forming stable polyaniline/QD/graphene hybrid. A testing electronic device was fabricated using the hybrid in order to investigate the photoinduced charge transfer between graphene and encapsulated QDs within the hybrid. The charge transfer mechanism was explored through cyclic voltammetry and spectroscopic studies. The hybrid shows a clear response to the laser irradiation, presenting a great advantage for further applications in optoelectronic devices.
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Affiliation(s)
- Kim Truc Nguyen
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371
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28
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Cassette E, Mirkovic T, Scholes GD. Toward the Control of Nonradiative Processes in Semiconductor Nanocrystals. J Phys Chem Lett 2013; 4:2091-2093. [PMID: 26283258 DOI: 10.1021/jz4010812] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Affiliation(s)
- Elsa Cassette
- Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, Ontario M5S 3H6, Canada
| | - Tihana Mirkovic
- Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, Ontario M5S 3H6, Canada
| | - Gregory D Scholes
- Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, Ontario M5S 3H6, Canada
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29
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Hoy J, Morrison PJ, Steinberg LK, Buhro WE, Loomis RA. Excitation Energy Dependence of the Photoluminescence Quantum Yields of Core and Core/Shell Quantum Dots. J Phys Chem Lett 2013; 4:2053-60. [PMID: 26283252 DOI: 10.1021/jz4004735] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
The photoluminescence (PL) intensity of semiconductor quantum dots (QDs) is routinely monitored to track the chemical and physical properties within a sample or device incorporating the QDs. A dependence of the PL quantum yields (QYs) on the excitation energy could lead to erroneous conclusions but is commonly not considered. We summarize previous evidence and present results from two methodologies that confirm the possibility of a dependence of the PL QYs on the excitation energy. The data presented indicate that PL QYs of CdSe and CdSe/ZnS QDs suspended in toluene are highest for excitation just above the band gap, Eg, of each. The PL QYs decrease with increasing excitation energies up to 1 eV above Eg. The PL intensity decay profiles recorded for these samples at varying emission and excitation energies indicate that the changes in the PL QYs result from the nonradiative relaxation pathways sampled as the charge carriers relax down to the band edge.
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Affiliation(s)
- Jessica Hoy
- Department of Chemistry and Center for Materials Innovation, Washington University in Saint Louis, One Brookings Drive, CB 1134, Saint Louis, Missouri 63130, United States
| | - Paul J Morrison
- Department of Chemistry and Center for Materials Innovation, Washington University in Saint Louis, One Brookings Drive, CB 1134, Saint Louis, Missouri 63130, United States
| | - Lindsey K Steinberg
- Department of Chemistry and Center for Materials Innovation, Washington University in Saint Louis, One Brookings Drive, CB 1134, Saint Louis, Missouri 63130, United States
| | - William E Buhro
- Department of Chemistry and Center for Materials Innovation, Washington University in Saint Louis, One Brookings Drive, CB 1134, Saint Louis, Missouri 63130, United States
| | - Richard A Loomis
- Department of Chemistry and Center for Materials Innovation, Washington University in Saint Louis, One Brookings Drive, CB 1134, Saint Louis, Missouri 63130, United States
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Xiao J, Wang Y, Hua Z, Wang X, Zhang C, Xiao M. Carrier multiplication in semiconductor nanocrystals detected by energy transfer to organic dye molecules. Nat Commun 2013; 3:1170. [PMID: 23132020 PMCID: PMC3493642 DOI: 10.1038/ncomms2183] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2012] [Accepted: 10/01/2012] [Indexed: 11/20/2022] Open
Abstract
In semiconductors, an absorbed photon can generate multiple electron-hole pairs, but measurements of this carrier multiplication efficiency in nanocrystals need to correctly account for charged excitons. Xiao et al. meet this need by measuring energy transfer of biexcitons from nanocrystals to acceptor dyes. Carrier multiplication describes an interesting optical phenomenon in semiconductors whereby more than one electron-hole pair, or exciton, can be simultaneously generated upon absorption of a single high-energy photon. So far, it has been highly debated whether the carrier multiplication efficiency is enhanced in semiconductor nanocrystals as compared with their bulk counterpart. The controversy arises from the fact that the ultrafast optical methods currently used need to correctly account for the false contribution of charged excitons to the carrier multiplication signals. Here we show that this charged exciton issue can be resolved in an energy transfer system, where biexcitons generated in the donor nanocrystals are transferred to the acceptor dyes, leading to an enhanced fluorescence from the latter. With the biexciton Auger and energy transfer lifetime measurements, an average carrier multiplication efficiency of ~17.1% can be roughly estimated in CdSe nanocrystals when the excitation photon energy is ~2.46 times of their energy gap.
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Affiliation(s)
- Jun Xiao
- National Laboratory of Solid State Microstructures and School of Physics, Nanjing University, Nanjing 210093, China
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31
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Stopel MHW, Prangsma JC, Blum C, Subramaniam V. Blinking statistics of colloidal quantum dots at different excitation wavelengths. RSC Adv 2013. [DOI: 10.1039/c3ra43637c] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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Zhao J, Chen O, Strasfeld DB, Bawendi MG. Biexciton quantum yield heterogeneities in single CdSe (CdS) core (shell) nanocrystals and its correlation to exciton blinking. NANO LETTERS 2012; 12:4477-83. [PMID: 22871126 PMCID: PMC3482465 DOI: 10.1021/nl3013727] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
We explore biexciton (BX) nonradiative recombination processes in single semiconductor nanocrystals (NCs) using confocal fluorescence microscopy and second-order photon intensity correlation. More specifically, we measure the photoluminescence blinking and BX quantum yields (QYs) and study the correlation between these two measurements for single core (shell) CdSe (CdS) nanocrystals (NCs). We find that NCs with a high "on" time fraction are significantly more likely to have a high BX QY than NCs with a low "on" fraction, even though the BX QYs of NCs with a high "on" fraction vary dramatically. The BX QYs of single NCs are also weakly dependent upon excitation wavelength. The weak correlation between exciton "on" fractions and BX QYs suggests that multiple recombination processes are involved in the BX recombination. To explain our results, we propose a model that combines both trapping and an Auger mechanism for BX recombination.
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34
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Liu J, Yang X, Wang K, He Y, Zhang P, Ji H, Jian L, Liu W. Single nanoparticle imaging and characterization of different phospholipid-encapsulated quantum dot micelles. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2012; 28:10602-10609. [PMID: 22716937 DOI: 10.1021/la301873m] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Phospholipid quantum dot (QD) micelles have been extensively used as fluorescent tags in single nanoparticle imaging for biomedical imaging. In this work, the microscopic structures and photophysical properties of the phospholipid QD micelles were studied at the single nanoparticle level. Two commonly used types of phospholipid QD micelles were prepared and tested both on a solid-phase surface and in liquid phase, including 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-encapsulated QD micelles (DSPE-QDMs) and 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-[methoxy(polyethylene glycol)-2000]-encapsulated QD micelles (PEG-DSPE-QDMs). Their fluorescence intensities and diffusion trajectories were determined by a total internal reflection fluorescence-based single nanoparticle imaging platform and comparatively analyzed carefully. It was demonstrated that DSPE-QDMs possessed a comparably wider intensity distribution and lower diffusion coefficient than that of PEG-DSPE-QDMs. PEG-DSPE-QDMs exhibited an obvious fluorescent intermittence. The results suggested that for most of the DSPE-QDMs, more than one QD were encapsulated in a single micelle. On the other hand, only one QD was embedded in a single micelle of PEG-DSPE-QDMs for most of the cases. Such variances suggested that phospholipids play a key role in the fabrication of the QD micelles. This work provides a useful foundation for their further biomedical applications.
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Affiliation(s)
- Jianbo Liu
- State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Key Laboratory for Bio-Nanotechnology and Molecular Engineering of Hunan Province, Hunan University, Changsha 410082, P. R. China
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Liu J, Yang X, Wang K, He X, Wang Q, Huang J, Liu Y. Aggregation control of quantum dots through ion-mediated hydrogen bonding shielding. ACS NANO 2012; 6:4973-4983. [PMID: 22616644 DOI: 10.1021/nn300517k] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Nanoparticle stabilization against detrimental aggregation is a critical parameter that needs to be well controlled. Herein, we present a facile and rapid ion-mediated dispersing technique that leads to hydrophilic aggregate-free quantum dots (QDs). Because of the shielding of the hydrogen bonds between cysteamine-capped QDs, the presence of F(-) ions disassembled the aggregates of QDs and afforded their high colloidal stability. The F(-) ions also greatly eliminated the nonspecific adsorption of the QDs on glass slides and cells. Unlike the conventional colloidal stabilized method that requires the use of any organic ligand and/or polymer for the passivation of the nanoparticle surface, the proposed approach adopts the small size and large diffusion coefficient of inorganic ions as dispersant, which offers the disaggregation a fast reaction dynamics and negligible influence on their intrinsic surface functional properties. Therefore, the ion-mediated dispersing strategy showed great potential in chemosensing and biomedical applications.
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Affiliation(s)
- Jianbo Liu
- State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, College of Biology, Hunan University, Changsha 410082, PR China
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Xu Z, Cotlet M. Photoluminenscence blinking dynamics of colloidal quantum dots in the presence of controlled external electron traps. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2012; 8:253-258. [PMID: 22180124 DOI: 10.1002/smll.201101643] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/12/2011] [Indexed: 05/31/2023]
Abstract
The effect of the external charge trap on the photoluminescence blinking dynamics of individual colloidal quantum dots is investigated with a series of colloidal quantum dot-bridge-fullerene dimers with varying bridge lengths, where the fullerene moiety acts as a well-defined, well-positioned external charge trap. It is found that charge transfer followed by charge recombination is an important mechanism in determining the blinking behavior of quantum dots when the external trap is properly coupled with the excited state of the quantum dot, leading to a quasi-continuous distribution of 'on' states and an early fall-off from a power-law distribution for both 'on' and 'off' times associated with quantum dot photoluminescence blinking.
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Affiliation(s)
- Zhihua Xu
- Center for Functional Nanomaterials, Brookhaven National Laboratory, Upton New York 11973, USA
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37
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Blumling DE, Tokumoto T, McGill S, Knappenberger KL. Temperature- and field-dependent energy transfer in CdSe nanocrystal aggregates studied by magneto-photoluminescence spectroscopy. Phys Chem Chem Phys 2012; 14:11053-9. [DOI: 10.1039/c2cp41586k] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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38
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Bixby TJ, Cordones AA, Leone SR. CdSe/ZnS quantum dot intermittency in N,N′-diphenyl-N,N′-bis(3-methylphenyl)-(1,1′-biphenyl)-4,4′-diamine (TPD). Chem Phys Lett 2012. [DOI: 10.1016/j.cplett.2011.11.051] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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39
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Greytak AB, Allen PM, Liu W, Zhao J, Young ER, Popović Z, Walker B, Nocera DG, Bawendi MG. Alternating layer addition approach to CdSe/CdS core/shell quantum dots with near-unity quantum yield and high on-time fractions. Chem Sci 2012; 3:2028-2034. [PMID: 24932403 DOI: 10.1039/c2sc00561a] [Citation(s) in RCA: 97] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
We report single-particle photoluminescence (PL) intermittency (blinking) with high on-time fractions in colloidal CdSe quantum dots (QD) with conformal CdS shells of 1.4 nm thickness, equivalent to approximately 4 CdS monolayers. All QDs observed displayed on-time fractions > 60% with the majority > 80%. The high-on-time-fraction blinking is accompanied by fluorescence quantum yields (QY) close to unity (up to 98% in an absolute QY measurement) when dispersed in organic solvents and a monoexponential ensemble photoluminescence (PL) decay lifetime. The CdS shell is formed in high synthetic yield using a modified selective ion layer adsorption and reaction (SILAR) technique that employs a silylated sulfur precursor. The CdS shell provides sufficient chemical and electronic passivation of the QD excited state to permit water solubilization with greater than 60% QY via ligand exchange with an imidazole-bearing hydrophilic polymer.
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Affiliation(s)
- Andrew B Greytak
- Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts, USA
| | - Peter M Allen
- Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts, USA
| | - Wenhao Liu
- Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts, USA
| | - Jing Zhao
- Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts, USA
| | - Elizabeth R Young
- Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts, USA
| | - Zoran Popović
- Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts, USA
| | - Brian Walker
- Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts, USA
| | - Daniel G Nocera
- Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts, USA
| | - Moungi G Bawendi
- Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts, USA
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40
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Durisic N, Godin AG, Walters D, Grütter P, Wiseman PW, Heyes CD. Probing the "dark" fraction of core-shell quantum dots by ensemble and single particle pH-dependent spectroscopy. ACS NANO 2011; 5:9062-73. [PMID: 22023370 PMCID: PMC3259027 DOI: 10.1021/nn203272p] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
The optical properties of core-shell CdSe-ZnS quantum dots (QDs) are characterized by complex photophysics leading to difficulties in interpreting quantitative measurements based on QD emission. By comparing the pH dependence of fluorescence of single QDs to that of an ensemble, we have been able to propose a molecular scale model of how QD surface chemical and physical processes are affected by protons and oxygen. We show that the connection between the ensemble fluorescence intensity and the single QD fluorescence properties such as dark fraction, blinking, particle brightness, and a multiexponential fluorescence lifetime decay is not trivial. The ensemble fluorescence intensity is more weakly dependent on pH than the single particle fluorescence which, together with fluorescence lifetime analysis, provided evidence that the dark fraction of QDs emits photons with low quantum efficiency and long lifetime. We uncovered two surface-dependent mechanisms that affected the fluorescence emission: an immediate physical effect of charges surrounding the QD and an irreversible chemical effect from reaction of the H(+) and O(2) with the QD shell surface. These results will have important implications for those using QD-based fluorescence lifetime imaging as well as for proper implementation of these probes for quantitative cellular imaging applications.
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Affiliation(s)
- Nela Durisic
- Department of Physics, McGill University, 3600 Rue University, Montreal, Quebec, Canada, H3A 2T8
| | - Antoine G. Godin
- Department of Physics, McGill University, 3600 Rue University, Montreal, Quebec, Canada, H3A 2T8
| | - Derrel Walters
- Department of Chemistry and Biochemistry, University of Arkansas, 345 N. Campus Drive, Fayetteville, AR, 72701
| | - Peter Grütter
- Department of Physics, McGill University, 3600 Rue University, Montreal, Quebec, Canada, H3A 2T8
| | - Paul W. Wiseman
- Department of Physics, McGill University, 3600 Rue University, Montreal, Quebec, Canada, H3A 2T8
- Department of Chemistry, McGill University, 800 Rue Sherbrooke Ouest, Montreal, Quebec, Canada, H3A 2K6
| | - Colin D. Heyes
- Department of Chemistry and Biochemistry, University of Arkansas, 345 N. Campus Drive, Fayetteville, AR, 72701
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41
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Blum C, Schleifenbaum F, Stopel M, Peter S, Sackrow M, Subramaniam V, Meixner AJ. Room temperature excitation spectroscopy of single quantum dots. BEILSTEIN JOURNAL OF NANOTECHNOLOGY 2011; 2:516-24. [PMID: 22003458 PMCID: PMC3190622 DOI: 10.3762/bjnano.2.56] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/22/2011] [Accepted: 06/09/2011] [Indexed: 05/23/2023]
Abstract
We report a single molecule detection scheme to investigate excitation spectra of single emitters at room temperature. We demonstrate the potential of single emitter photoluminescence excitation spectroscopy by recording excitation spectra of single CdSe nanocrystals over a wide spectral range of 100 nm. The spectra exhibit emission intermittency, characteristic of single emitters. We observe large variations in the spectra close to the band edge, which represent the individual heterogeneity of the observed quantum dots. We also find specific excitation wavelengths for which the single quantum dots analyzed show an increased propensity for a transition to a long-lived dark state. We expect that the additional capability of recording excitation spectra at room temperature from single emitters will enable insights into the photophysics of emitters that so far have remained inaccessible.
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Affiliation(s)
- Christian Blum
- Nanobiophysics Group and MESA+ Institute for Nanotechnology, University of Twente, PO Box 217, 7500 AE Enschede, The Netherlands
| | - Frank Schleifenbaum
- Center for Plant Molecular Biology, Biophysical Chemistry, University of Tübingen, Auf der Morgenstelle 18, 72076 Tübingen, Germany
| | - Martijn Stopel
- Nanobiophysics Group and MESA+ Institute for Nanotechnology, University of Twente, PO Box 217, 7500 AE Enschede, The Netherlands
| | - Sébastien Peter
- Center for Plant Molecular Biology, Biophysical Chemistry, University of Tübingen, Auf der Morgenstelle 18, 72076 Tübingen, Germany
| | - Marcus Sackrow
- Institut für Physikalische und Theoretische Chemie, University of Tübingen, Auf der Morgenstelle 8, 72076 Tübingen, Germany
- present address: Picoquant GmbH, Rudower Chaussee 29, 12489 Berlin, Germany
| | - Vinod Subramaniam
- Nanobiophysics Group and MESA+ Institute for Nanotechnology, University of Twente, PO Box 217, 7500 AE Enschede, The Netherlands
| | - Alfred J Meixner
- Institut für Physikalische und Theoretische Chemie, University of Tübingen, Auf der Morgenstelle 8, 72076 Tübingen, Germany
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Tyagi P, Kambhampati P. False multiple exciton recombination and multiple exciton generation signals in semiconductor quantum dots arise from surface charge trapping. J Chem Phys 2011; 134:094706. [DOI: 10.1063/1.3561063] [Citation(s) in RCA: 150] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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43
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Krasselt C, Schuster J, von Borczyskowski C. Photoinduced hole trapping in single semiconductor quantum dots at specific sites at silicon oxide interfaces. Phys Chem Chem Phys 2011; 13:17084-92. [DOI: 10.1039/c1cp22040c] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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McGuire JA, Sykora M, Robel I, Padilha LA, Joo J, Pietryga JM, Klimov VI. Spectroscopic Signatures of Photocharging due to Hot-Carrier Transfer in Solutions of Semiconductor Nanocrystals under Low-Intensity Ultraviolet Excitation. ACS NANO 2010; 4:6087-97. [PMID: 20939512 DOI: 10.1021/nn1016296] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Affiliation(s)
- John A. McGuire
- Center for Advanced Solar Photophysics, Chemistry Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
| | - Milan Sykora
- Center for Advanced Solar Photophysics, Chemistry Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
| | - István Robel
- Center for Advanced Solar Photophysics, Chemistry Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
| | - Lazaro A. Padilha
- Center for Advanced Solar Photophysics, Chemistry Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
| | - Jin Joo
- Center for Advanced Solar Photophysics, Chemistry Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
| | - Jeffrey M. Pietryga
- Center for Advanced Solar Photophysics, Chemistry Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
| | - Victor I. Klimov
- Center for Advanced Solar Photophysics, Chemistry Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
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45
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Hamada M, Nakanishi S, Itoh T, Ishikawa M, Biju V. Blinking suppression in CdSe/ZnS single quantum dots by TiO2 nanoparticles. ACS NANO 2010; 4:4445-4454. [PMID: 20731430 DOI: 10.1021/nn100698u] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
The photoluminescence of semiconductor quantum dots and fluorescence of single molecules intermittently turn ON and OFF, a phenomenon referred to as blinking. In quantum dots, blinking occurs as a result of intermittent Auger ionization, which results in the formation of positively charged quantum dots. Due to strong Coulombic interactions, successive photoactivation of a charged quantum dot results in nonradiative carrier recombination, inducing long-lived OFF states in the intensity trajectories. Blinking is an undesirable property with respect to applications of quantum dots toward single-molecule imaging and single-photon logic devices. Here we report significant blinking suppression for CdSe/ZnS single quantum dots in the presence of TiO(2) nanoparticles. In this work, we continuously recorded photoluminescence intensity trajectories of single quantum dots with and without TiO(2) nanoparticles. Interestingly, the intensity trajectory of a single quantum dot that was covalently tethered on a cover glass and dipped in water resulted in near-complete blinking suppression as soon as a TiO(2) nanoparticle solution was introduced. The blinking suppression was associated with a decrease in the photoluminescence intensity but without considerable changes in the photoluminescence lifetime, indicating that nonradiative carrier recombination in quantum dots was channeled into electron transfer to TiO(2) nanoparticles and back electron transfer to quantum dots. On the basis of these experiments and recent reports on photoinduced electron transfer from quantum dots to TiO(2) nanoparticles, we hypothesize that blinking of a quantum dot can be suppressed by increasing the rate of nonradiative regeneration of its neutral state by interfacing with a well-defined charge carrier trap such as an electron acceptor, which accepts an electron during Auger ionization and neutralizes the charged quantum dot by back electron transfer. Correlation between blinking suppression and electron transfer in a quantum dot-TiO(2) nanoparticle system may have important implications, for the preparation of nonblinking quantum dot for incessant and on-demand light emission, donor-acceptor systems for efficient solar energy harvesting, and hybrid semiconductor materials for quantum optical devices.
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Affiliation(s)
- Morihiko Hamada
- Nano-bioanalysis Group, Health Research Institute, National Institute of Advanced Industrial Science and Technology, 2217-14 Hayashi-Cho, Takamatsu, Kagawa 761-0396, Japan
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Crouch CH, Sauter O, Wu X, Purcell R, Querner C, Drndic M, Pelton M. Facts and artifacts in the blinking statistics of semiconductor nanocrystals. NANO LETTERS 2010; 10:1692-1698. [PMID: 20364845 DOI: 10.1021/nl100030e] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Since its initial discovery just over a decade ago, blinking of semiconductor nanocrystals has typically been described in terms of probability distributions for durations of bright, or "on," states and dark, or "off," states. These distributions are obtained by binning photon counts in order to construct a time series for emission intensity and then applying a threshold to distinguish on states from off states. By examining experimental data from CdSe/ZnS core/shell nanocrystals and by simulating this data according to a simple, two-state blinking model, we find that the apparent truncated power-law distributions of on times can depend significantly on the choices of binning time and threshold. For example, increasing the binning time by a factor of 10 can double the apparent truncation time and change the apparent power-law exponent by 30%, even though the binning time is only 3% of the truncation time. Our findings indicate that stringent experimental conditions are needed to accurately determine blinking-time probability distributions. Similar considerations should apply to any phenomenon characterized by time series data that displays telegraph noise.
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Affiliation(s)
- Catherine H Crouch
- Department of Physics and Astronomy, Swarthmore College, Swarthmore, Pennsylvania 19081, USA.
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Marcus RA. Interaction of theory and experiment: examples from single molecule studies of nanoparticles. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2010; 368:1109-24. [PMID: 20123749 PMCID: PMC3263810 DOI: 10.1098/rsta.2009.0261] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
This article is in part the author's perspective on the revolution that has occurred in theoretical chemistry during the past half-century. In this period much of theoretical chemistry has moved from its initial emphasis on analytic treatments, resulting in equations for physical chemical and chemical phenomena, to the detailed computation of many different systems and processes. In the best sense the old and the new are complementary and their coexistence can benefit both. Experiment too has seen major developments. One of the newer types of experiment is that of single molecule studies. They range from those on small inorganic and organic nanoparticles to large biological species. We illustrate some of the issues that arise, using the topic of 'quantum dots' (QDs), and choosing a particular inorganic nanoparticle, CdSe, the most studied of these systems. Its study reflects the problems that arise in experiment and in theories in this field. The complementary nature of the conventional ensemble experiments and the new single molecule experiments is described and is illustrated by trajectories for the two types of experiments. The research in the QD field is both experimentally and theoretically a currently ongoing process, for which the answers are not fully known in spite of the large body of research. The detailed role of surface states is part of the problem. The field continues to yield new and unexpected results. In a sense this part of the article is an interim report that illustrates one analytic approach to the topic and where computer calculations and simulations can be expected to provide added insight.
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Affiliation(s)
- Rudolph A Marcus
- Noyes Laboratory of Chemical Physics, California Institute of Technology, Pasadena, CA 91125, USA.
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48
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Chon B, Lim SJ, Kim W, Seo J, Kang H, Joo T, Hwang J, Shin SK. Shell and ligand-dependent blinking of CdSe-based core/shell nanocrystals. Phys Chem Chem Phys 2010; 12:9312-9. [DOI: 10.1039/b924917f] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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49
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Baker TA, Rouge JL, Nesbitt DJ. Single molecule studies of quantum dot fluorescence intermittency: evidence for both dark and light-assisted blinking dynamics. Mol Phys 2009. [DOI: 10.1080/00268970902933820] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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50
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Lee SF, Osborne MA. Brightening, Blinking, Bluing and Bleaching in the Life of a Quantum Dot: Friend or Foe? Chemphyschem 2009; 10:2174-91. [DOI: 10.1002/cphc.200900200] [Citation(s) in RCA: 136] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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