201
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Zhang H, Sui N, Chi X, Wang Y, Liu Q, Zhang H, Ji W. Ultrastable Quantum-Dot Light-Emitting Diodes by Suppression of Leakage Current and Exciton Quenching Processes. ACS APPLIED MATERIALS & INTERFACES 2016; 8:31385-31391. [PMID: 27781427 DOI: 10.1021/acsami.6b09246] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
A study of hybrid inverted quantum-dot (QD) light-emitting diodes constructed with and without Al2O3 interlayers is presented. The Al2O3 interlayers are deposited at ZnO/QDs or/and QDs/4,4'-bis(carbazol-9-yl)biphenyl interfaces, resulting in large improvement of device performance, including luminance, current efficiency, and device lifetime. Especially, the devices with QD emitters sandwiched by two Al2O3 layers exhibits outstanding performance, the longest operation lifetime, and mediate efficiency. The maximum current efficiency of 15.3 cd/A is obtained, an enhancement factor of 35% in comparison to that (11.3 cd/A) of conventional device without Al2O3 layer. Moreover, device lifetime is also largely enhanced, over 110 000 h for the device containing two Al2O3 interlayers, nearly 40% enhancement relative to that of conventional device that shows a lifetime of only 80 000 h. On the basis of electrical property and photoluminescence spectroscopy studies, we demonstrate that the Al2O3 interlayers play crucial roles in suppressing the leakage current across the device and reducing exciton quenching induced by ZnO.
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Affiliation(s)
- Han Zhang
- College of Physics, Jilin University , Changchun 130012, China
| | - Ning Sui
- College of Physics, Jilin University , Changchun 130012, China
| | - Xiaochun Chi
- College of Physics, Jilin University , Changchun 130012, China
| | - Yinghui Wang
- College of Physics, Jilin University , Changchun 130012, China
| | - Qinghui Liu
- College of Physics, Jilin University , Changchun 130012, China
| | - Hanzhuang Zhang
- College of Physics, Jilin University , Changchun 130012, China
| | - Wenyu Ji
- College of Physics, Jilin University , Changchun 130012, China
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202
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Jeong BG, Park YS, Chang JH, Cho I, Kim JK, Kim H, Char K, Cho J, Klimov VI, Park P, Lee DC, Bae WK. Colloidal Spherical Quantum Wells with Near-Unity Photoluminescence Quantum Yield and Suppressed Blinking. ACS NANO 2016; 10:9297-9305. [PMID: 27690386 DOI: 10.1021/acsnano.6b03704] [Citation(s) in RCA: 58] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Thick inorganic shells endow colloidal nanocrystals (NCs) with enhanced photochemical stability and suppression of photoluminescence intermittency (also known as blinking). However, the progress of using thick-shell heterostructure NCs in applications has been limited due to the low photoluminescence quantum yield (PL QY ≤ 60%) at room temperature. Here, we demonstrate thick-shell NCs with CdS/CdSe/CdS seed/spherical quantum well/shell (SQW) geometry that exhibit near-unity PL QY at room temperature and suppression of blinking. In SQW NCs, the lattice mismatch is diminished between the emissive CdSe layer and the surrounding CdS layers as a result of coherent strain, which suppresses the formation of misfit defects and consequently permits ∼100% PL QY for SQW NCs with a thick CdS shell (≥5 nm). High PL QY of thick-shell SQW NCs is preserved even in concentrated dispersion and in film under thermal stress, which makes them promising candidates for applications in solid-state lightings and luminescent solar concentrators.
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Affiliation(s)
- Byeong Guk Jeong
- Department of Chemical and Biomolecular Engineering, KAIST Institute for the Nanocentury, Korea Advanced Institute of Science and Technology (KAIST) , 291 Daehak-ro, Yuseong-gu, Daejeon 34141, Republic of Korea
| | - Young-Shin Park
- 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
| | - Jun Hyuk Chang
- School of Chemical and Biological Engineering, The National Creative Research Initiative Center for Intelligent Hybrids, Seoul National University , 1 Gwanak-ro, Gwanak-gu, Seoul 08826, Republic of Korea
| | - Ikjun Cho
- Department of Chemical and Biological Engineering, Korea University , 145 Anam-ro, Seongbuk-gu, Seoul 02841, Republic of Korea
| | - Jai Kyeong Kim
- Photoelectronic Hybrids Research Center, Korea Institute of Science and Technology (KIST) , 14-gil 5 Hwarang-ro, Seongbuk-gu, Seoul 02792, Republic of Korea
| | - Heesuk Kim
- Photoelectronic Hybrids Research Center, Korea Institute of Science and Technology (KIST) , 14-gil 5 Hwarang-ro, Seongbuk-gu, Seoul 02792, Republic of Korea
| | - Kookheon Char
- School of Chemical and Biological Engineering, The National Creative Research Initiative Center for Intelligent Hybrids, Seoul National University , 1 Gwanak-ro, Gwanak-gu, Seoul 08826, Republic of Korea
| | - Jinhan Cho
- Department of Chemical and Biological Engineering, Korea University , 145 Anam-ro, Seongbuk-gu, Seoul 02841, Republic of Korea
| | - Victor I Klimov
- Chemistry Division, Los Alamos National Laboratory , Los Alamos, New Mexico 87545, United States
| | - Philip Park
- Department of Chemistry and Biochemistry, University of California , Los Angeles, California 90095, United States
| | - Doh C Lee
- Department of Chemical and Biomolecular Engineering, KAIST Institute for the Nanocentury, Korea Advanced Institute of Science and Technology (KAIST) , 291 Daehak-ro, Yuseong-gu, Daejeon 34141, Republic of Korea
| | - Wan Ki Bae
- Photoelectronic Hybrids Research Center, Korea Institute of Science and Technology (KIST) , 14-gil 5 Hwarang-ro, Seongbuk-gu, Seoul 02792, Republic of Korea
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203
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Abstract
Abstract
The current state-of-the-art of the fabrication and photophysics of graded shells in quantum dots is reviewed. Graded shells, i.e. partially alloyed interfaces between core and shell or between two shells of semiconductor nanoheterostructures, have been demonstrated to improve fluorescence properties and suppress non-radiative pathways of exciton dynamics. By simply looking at linear optics on the level of single excitons this is reflected in increased photoluminescence quantum yields. However, it is shown that graded shells have further beneficial implications for band structure engineering and multiexciton dynamics such as optical gain and charge carrier multiplication.
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Affiliation(s)
- Klaus Boldt
- Department of Chemistry, University of Konstanz, 78457 Konstanz, Germany
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204
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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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205
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Zhao H, Benetti D, Jin L, Zhou Y, Rosei F, Vomiero A. Absorption Enhancement in "Giant" Core/Alloyed-Shell Quantum Dots for Luminescent Solar Concentrator. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2016; 12:5354-5365. [PMID: 27515385 DOI: 10.1002/smll.201600945] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/18/2016] [Revised: 06/20/2016] [Indexed: 05/20/2023]
Abstract
Luminescent solar concentrators (LSCs) can potentially reduce the cost of solar cells by decreasing the photoactive area of the device and boosting the photoconversion efficiency (PCE). This study demonstrates the application of "giant" CdSe/Cdx Pb1-x S core/shell quantum dots (QDs) as light harvesters in high performance LSCs with over 1.15% PCE. Pb addition is critical to maximize PCE. First, this study synthesizes "giant" CdSe/Cdx Pb1-x S QDs with high quantum yield (40%), narrow size distribution (<10%), and stable photoluminescence in a wide temperature range (100-300 K). Subsequently these thick alloyed-shell QDs are embedded in a polymer matrix, resulting in a highly transparent composite with absorption spectrum covering the range 300-600 nm, and are applied as active material for prototype LSCs. The latter exhibits a 15% enhancement in efficiency with respect to 1% PCE of the pure-CdS-shelled QDs. This study attributes this increase to the contribution of Pb doping. The results demonstrate a straightforward approach to enhance light absorption in "giant" QDs by metal doping, indicating a promising route to broaden the absorption spectrum and increase the efficiency of LSCs.
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Affiliation(s)
- Haiguang Zhao
- Centre for Energy, Materials and Telecommunications, Institut National de la Recherche Scientifique, Université du Québec, 1650 Boulevard Lionel-Boulet, Varennes, Québec, J3X1S2, Canada.
| | - Daniele Benetti
- Centre for Energy, Materials and Telecommunications, Institut National de la Recherche Scientifique, Université du Québec, 1650 Boulevard Lionel-Boulet, Varennes, Québec, J3X1S2, Canada
| | - Lei Jin
- Centre for Energy, Materials and Telecommunications, Institut National de la Recherche Scientifique, Université du Québec, 1650 Boulevard Lionel-Boulet, Varennes, Québec, J3X1S2, Canada
| | - Yufeng Zhou
- Centre for Energy, Materials and Telecommunications, Institut National de la Recherche Scientifique, Université du Québec, 1650 Boulevard Lionel-Boulet, Varennes, Québec, J3X1S2, Canada
| | - Federico Rosei
- Centre for Energy, Materials and Telecommunications, Institut National de la Recherche Scientifique, Université du Québec, 1650 Boulevard Lionel-Boulet, Varennes, Québec, J3X1S2, Canada.
- Institute for Fundamental and Frontier Science, University of Electronic Science and Technology of China, Chengdu, 610054, P. R. China.
| | - Alberto Vomiero
- Department of Engineering Sciences and Mathematics, Luleå University of Technology, Luleå, 971 98, Sweden.
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206
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Quantum Dot-Based Nanotools for Bioimaging, Diagnostics, and Drug Delivery. Chembiochem 2016; 17:2103-2114. [DOI: 10.1002/cbic.201600357] [Citation(s) in RCA: 120] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2016] [Indexed: 12/12/2022]
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207
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Li B, Zhang G, Wang Z, Li Z, Chen R, Qin C, Gao Y, Xiao L, Jia S. Suppressing the Fluorescence Blinking of Single Quantum Dots Encased in N-type Semiconductor Nanoparticles. Sci Rep 2016; 6:32662. [PMID: 27605471 PMCID: PMC5015025 DOI: 10.1038/srep32662] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2016] [Accepted: 08/11/2016] [Indexed: 12/20/2022] Open
Abstract
N-type semiconductor indium tin oxide (ITO) nanoparticles are used to effectively suppress the fluorescence blinking of single near-infrared-emitting CdSeTe/ZnS core/shell quantum dots (QDs), where the ITO could block the electron transfer from excited QDs to trap states and facilitate more rapid regeneration of neutral QDs by back electron transfer. The average blinking rate of QDs is significantly reduced by more than an order of magnitude and the largest proportion of on-state is 98%, while the lifetime is not considerably reduced. Furthermore, an external electron transfer model is proposed to analyze the possible effect of radiative, nonradiative, and electron transfer pathways on fluorescence blinking. Theoretical analysis based on the model combined with measured results gives a quantitative insight into the blinking mechanism.
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Affiliation(s)
- Bin Li
- State Key Laboratory of Quantum Optics and Quantum Optics Devices, Institute of Laser Spectroscopy, Shanxi University, Taiyuan, 030006, China.,Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan, Shanxi, 030006, People's Republic of China
| | - Guofeng Zhang
- State Key Laboratory of Quantum Optics and Quantum Optics Devices, Institute of Laser Spectroscopy, Shanxi University, Taiyuan, 030006, China.,Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan, Shanxi, 030006, People's Republic of China
| | - Zao Wang
- State Key Laboratory of Quantum Optics and Quantum Optics Devices, Institute of Laser Spectroscopy, Shanxi University, Taiyuan, 030006, China.,Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan, Shanxi, 030006, People's Republic of China
| | - Zhijie Li
- State Key Laboratory of Quantum Optics and Quantum Optics Devices, Institute of Laser Spectroscopy, Shanxi University, Taiyuan, 030006, China.,Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan, Shanxi, 030006, People's Republic of China
| | - Ruiyun Chen
- State Key Laboratory of Quantum Optics and Quantum Optics Devices, Institute of Laser Spectroscopy, Shanxi University, Taiyuan, 030006, China.,Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan, Shanxi, 030006, People's Republic of China
| | - Chengbing Qin
- State Key Laboratory of Quantum Optics and Quantum Optics Devices, Institute of Laser Spectroscopy, Shanxi University, Taiyuan, 030006, China.,Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan, Shanxi, 030006, People's Republic of China
| | - Yan Gao
- State Key Laboratory of Quantum Optics and Quantum Optics Devices, Institute of Laser Spectroscopy, Shanxi University, Taiyuan, 030006, China.,Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan, Shanxi, 030006, People's Republic of China
| | - Liantuan Xiao
- State Key Laboratory of Quantum Optics and Quantum Optics Devices, Institute of Laser Spectroscopy, Shanxi University, Taiyuan, 030006, China.,Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan, Shanxi, 030006, People's Republic of China
| | - Suotang Jia
- State Key Laboratory of Quantum Optics and Quantum Optics Devices, Institute of Laser Spectroscopy, Shanxi University, Taiyuan, 030006, China.,Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan, Shanxi, 030006, People's Republic of China
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208
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209
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Oh N, Shim M. Metal Oleate Induced Etching and Growth of Semiconductor Nanocrystals, Nanorods, and Their Heterostructures. J Am Chem Soc 2016; 138:10444-51. [DOI: 10.1021/jacs.6b03834] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- Nuri Oh
- Department
of Materials Science
and Engineering, University of Illinois at Urbana—Champaign, Urbana, Illinois 61801, United States
| | - Moonsub Shim
- Department
of Materials Science
and Engineering, University of Illinois at Urbana—Champaign, Urbana, Illinois 61801, United States
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210
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Rabouw FT, de Mello Donega C. Excited-State Dynamics in Colloidal Semiconductor Nanocrystals. Top Curr Chem (Cham) 2016; 374:58. [PMID: 27573500 PMCID: PMC5480409 DOI: 10.1007/s41061-016-0060-0] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2016] [Accepted: 07/23/2016] [Indexed: 11/29/2022]
Abstract
Colloidal semiconductor nanocrystals have attracted continuous worldwide interest over the last three decades owing to their remarkable and unique size- and shape-, dependent properties. The colloidal nature of these nanomaterials allows one to take full advantage of nanoscale effects to tailor their optoelectronic and physical–chemical properties, yielding materials that combine size-, shape-, and composition-dependent properties with easy surface manipulation and solution processing. These features have turned the study of colloidal semiconductor nanocrystals into a dynamic and multidisciplinary research field, with fascinating fundamental challenges and dazzling application prospects. This review focuses on the excited-state dynamics in these intriguing nanomaterials, covering a range of different relaxation mechanisms that span over 15 orders of magnitude, from a few femtoseconds to a few seconds after photoexcitation. In addition to reviewing the state of the art and highlighting the essential concepts in the field, we also discuss the relevance of the different relaxation processes to a number of potential applications, such as photovoltaics and LEDs. The fundamental physical and chemical principles needed to control and understand the properties of colloidal semiconductor nanocrystals are also addressed.
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Affiliation(s)
- Freddy T Rabouw
- Inorganic Chemistry and Catalysis, Debye Institute for Nanomaterials Science, Utrecht University, PO Box 80000, 3508 TA, Utrecht, The Netherlands.,Soft Condensed Matter, Debye Institute for Nanomaterials Science, Utrecht University, PO Box 80000, 3508 TA, Utrecht, The Netherlands.,Optical Materials Engineering Laboratory, ETH Zurich, 8092, Zurich, Switzerland
| | - Celso de Mello Donega
- Condensed Matter and Interfaces, Debye Institute for Nanomaterials Science, Utrecht University, PO Box 80000, 3508 TA, Utrecht, The Netherlands.
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211
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Todescato F, Fortunati I, Minotto A, Signorini R, Jasieniak JJ, Bozio R. Engineering of Semiconductor Nanocrystals for Light Emitting Applications. MATERIALS 2016; 9:ma9080672. [PMID: 28773794 PMCID: PMC5510729 DOI: 10.3390/ma9080672] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/28/2016] [Revised: 07/18/2016] [Accepted: 08/02/2016] [Indexed: 02/06/2023]
Abstract
Semiconductor nanocrystals are rapidly spreading into the display and lighting markets. Compared with liquid crystal and organic LED displays, nanocrystalline quantum dots (QDs) provide highly saturated colors, wide color gamut, resolution, rapid response time, optical efficiency, durability and low cost. This remarkable progress has been made possible by the rapid advances in the synthesis of colloidal QDs and by the progress in understanding the intriguing new physics exhibited by these nanoparticles. In this review, we provide support to the idea that suitably engineered core/graded-shell QDs exhibit exceptionally favorable optical properties, photoluminescence and optical gain, while keeping the synthesis facile and producing QDs well suited for light emitting applications. Solid-state laser emitters can greatly profit from QDs as efficient gain materials. Progress towards fabricating low threshold, solution processed DFB lasers that are optically pumped using one- and two-photon absorption is reviewed. In the field of display technologies, the exploitation of the exceptional photoluminescence properties of QDs for LCD backlighting has already advanced to commercial levels. The next big challenge is to develop the electroluminescence properties of QD to a similar state. We present an overview of QLED devices and of the great perspectives for next generation display and lighting technologies.
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Affiliation(s)
- Francesco Todescato
- Department of Chemical Science and U.R. INSTM, University of Padova, Via Marzolo 1, Padova I-35131, Italy.
| | - Ilaria Fortunati
- Department of Chemical Science and U.R. INSTM, University of Padova, Via Marzolo 1, Padova I-35131, Italy.
| | - Alessandro Minotto
- Department of Chemical Science and U.R. INSTM, University of Padova, Via Marzolo 1, Padova I-35131, Italy.
| | - Raffaella Signorini
- Department of Chemical Science and U.R. INSTM, University of Padova, Via Marzolo 1, Padova I-35131, Italy.
| | - Jacek J Jasieniak
- Department of Materials Science and Engineering, Monash Energy Materials and Systems Institute (MEMSI), Monash University, 22 Alliance Lane, Room 109, Clayton 3800, Australia.
| | - Renato Bozio
- Department of Chemical Science and U.R. INSTM, University of Padova, Via Marzolo 1, Padova I-35131, Italy.
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212
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Efros AL, Nesbitt DJ. Origin and control of blinking in quantum dots. NATURE NANOTECHNOLOGY 2016; 11:661-71. [PMID: 27485584 DOI: 10.1038/nnano.2016.140] [Citation(s) in RCA: 215] [Impact Index Per Article: 26.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2016] [Accepted: 06/29/2016] [Indexed: 05/24/2023]
Abstract
Semiconductor nanocrystals offer an enormous diversity of potential device applications, based on their size-tunable photoluminescence, high optical stability and 'bottom-up' chemical approaches to self-assembly. However, the promise of such applications can be seriously limited by photoluminescence intermittency in nanocrystal emission, that is, 'blinking', arising from the escape of either one or both of the photoexcited carriers to the nanocrystal surface. In the first scenario, the remaining nanocrystal charge quenches photoluminescence via non-radiative Auger recombination, whereas for the other, the exciton is thought to be intercepted before thermalization and does not contribute to the photoluminescence. This Review summarizes the current understanding of the mechanisms responsible for nanocrystal blinking kinetics as well as core-shell engineering efforts to control such phenomena. In particular, 'softening' of the core-shell confinement potential strongly suppresses non-radiative Auger processes in charged nanocrystals, with successful non-blinking implementations demonstrated in CdSe-CdS core-thick-shell nanocrystals and their modifications.
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Affiliation(s)
- Alexander L Efros
- Naval Research Laboratory, Center for Computational Material Science, Washington DC 20375, USA
| | - David J Nesbitt
- JILA, University of Colorado and National Institute of Standards and Technology, and Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309-0440, USA
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213
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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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214
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Pu C, Peng X. To Battle Surface Traps on CdSe/CdS Core/Shell Nanocrystals: Shell Isolation versus Surface Treatment. J Am Chem Soc 2016; 138:8134-42. [PMID: 27312799 DOI: 10.1021/jacs.6b02909] [Citation(s) in RCA: 97] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Electronic traps at the inorganic-organic interface of colloidal quantum dots (QDs) are detrimental to their luminescent properties. Several types of interface traps were identified for single-crystalline CdSe/CdS core/shell QDs, which were all found to be extrinsic to either the core/shell structure or their optical performance. The electron traps-presumably excess or unpassivated Cd surface sites-are shallow ones and could be readily isolated from the electron wave function of the excitons with more than ∼2 monolayers of CdS shell. There were two identifiable deep hole traps within the bandgap of the QDs, i.e., the surface adsorbed H2S and unpassivated surface S sites. The surface adsorbed H2S could be removed by either degassing processes or photochemical decomposition of H2S without damaging the QDs. The unpassivated surface S sites could be removed by surface treatment with cadmium carboxylates. Understanding of the surface traps enabled establishment of new phosphine-free synthetic schemes for either single-precursor or successive-ion-layer-adsorption-and-reaction approach, which yielded CdSe/CdS core/shell QDs with near-unity photoluminescence quantum yield and monoexponential photoluminescence decay dynamics with 2-10 monolayers of CdS shell.
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Affiliation(s)
- Chaodan Pu
- Center for Chemistry of Novel & High-Performance Materials, Department of Chemistry, Zhejiang University , Hangzhou, 310027, P. R. China
| | - Xiaogang Peng
- Center for Chemistry of Novel & High-Performance Materials, Department of Chemistry, Zhejiang University , Hangzhou, 310027, P. R. China
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215
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Sowers KL, Hou Z, Peterson JJ, Swartz B, Pal S, Prezhdo O, Krauss TD. Photophysical Properties of CdSe/CdS core/shell quantum dots with tunable surface composition. Chem Phys 2016. [DOI: 10.1016/j.chemphys.2015.09.010] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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216
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217
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Omogo B, Gao F, Bajwa P, Kaneko M, Heyes CD. Reducing Blinking in Small Core-Multishell Quantum Dots by Carefully Balancing Confinement Potential and Induced Lattice Strain: The "Goldilocks" Effect. ACS NANO 2016; 10:4072-82. [PMID: 27058120 DOI: 10.1021/acsnano.5b06994] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
Currently, the most common way to reduce blinking in quantum dots (QDs) is accomplished by using very thick and/or perfectly crystalline CdS shells on CdSe cores. Ideally, a nontoxic material such as ZnS is preferred to be the outer material in order to reduce environmental and cytotoxic effects. Blinking suppression with multishell configurations of CdS and ZnS has been reported only for "giant" QDs of 15 nm or more. One of the main reasons for the limited progress is that the role that interfacial trap states play in blinking in these systems is not very well understood. Here, we show a "Goldilocks" effect to reduce blinking in small (∼7 nm) QDs by carefully controlling the thicknesses of the shells in multishell QDs. Furthermore, by correlating the fluorescence lifetime components with the fraction of time that a QD spends in the on-state, both with and without applying a threshold, we found evidence for two types of blinking that separately affect the average fluorescence lifetime of a single QD. A thorough characterization of the time-resolved fluorescence at the ensemble and single-particle level allowed us to propose a detailed physical model involving both short-lived interfacial trap states and long-lived surface trap states that are coupled. This model highlights a strategy of reducing QD blinking in small QDs by balancing the magnitude of the induced lattice strain, which results in the formation of interfacial trap states between the inner shell and the outer shell, and the confinement potential that determines how accessible the interfacial trap states are. The combination of reducing blinking while maintaining a small overall QD size and using a Cd-free outer shell of ZnS will be useful in a wide array of applications, particularly for advanced bioimaging.
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Affiliation(s)
- Benard Omogo
- Department of Chemistry and Biochemistry, University of Arkansas , Fayetteville, Arkansas 72701, United States
| | - Feng Gao
- Department of Chemistry and Biochemistry, University of Arkansas , Fayetteville, Arkansas 72701, United States
| | - Pooja Bajwa
- Department of Chemistry and Biochemistry, University of Arkansas , Fayetteville, Arkansas 72701, United States
| | - Mizuho Kaneko
- Department of Chemistry and Biochemistry, University of Arkansas , Fayetteville, Arkansas 72701, United States
| | - Colin D Heyes
- Department of Chemistry and Biochemistry, University of Arkansas , Fayetteville, Arkansas 72701, United States
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218
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Vaxenburg R, Rodina A, Lifshitz E, L Efros A. Biexciton Auger Recombination in CdSe/CdS Core/Shell Semiconductor Nanocrystals. NANO LETTERS 2016; 16:2503-11. [PMID: 26950398 DOI: 10.1021/acs.nanolett.6b00066] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
A theoretical study of the positive and negative trion channels in the nonradiative Auger recombination of band-edge biexcitons (BXs) in CdSe/CdS core/shell nanocrystals (NCs) is presented. The theory takes into account the BX fine-structure produced by NC asymmetry and hole-hole exchange interaction. The calculations show that growth of CdS shell upon CdSe core suppresses the rate of the Auger recombination via negative trion channel, while the more efficient Auger recombination via positive trion channel shows much weaker dependence on the shell thickness. The demonstrated oscillatory dependence of the BX Auger rate on the core and shell sizes is explained qualitatively in terms of overlap of the ground and excited carrier wave functions. The calculations show that raise of temperature accelerates the Auger recombination in CdSe/CdS NCs due to reduction of the bulk energy gaps of CdSe and CdS.
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Affiliation(s)
- Roman Vaxenburg
- George Mason University , Fairfax, Virginia 22030, United States
| | - Anna Rodina
- Ioffe Institute, Russian Academy of Sciences , 194021 St. Petersburg, Russia
| | - Efrat Lifshitz
- Technion - Israel Institute of Technology , Haifa 32000, Israel
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219
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Relich PK, Olah MJ, Cutler PJ, Lidke KA. Estimation of the diffusion constant from intermittent trajectories with variable position uncertainties. Phys Rev E 2016; 93:042401. [PMID: 27176323 DOI: 10.1103/physreve.93.042401] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2015] [Indexed: 11/07/2022]
Abstract
The movement of a particle described by Brownian motion is quantified by a single parameter, D, the diffusion constant. The estimation of D from a discrete sequence of noisy observations is a fundamental problem in biological single-particle tracking experiments since it can provide information on the environment and/or the state of the particle itself via the hydrodynamic radius. Here, we present a method to estimate D that takes into account several effects that occur in practice, important for the correct estimation of D, and that have hitherto not been combined together for an estimation of D. These effects are motion blur from the finite integration time of the camera, intermittent trajectories, and time-dependent localization uncertainty. Our estimation procedure, a maximum-likelihood estimation with an information-based confidence interval, follows directly from the likelihood expression for a discretely observed Brownian trajectory that explicitly includes these effects. We begin with the formulation of the likelihood expression and then present three methods to find the exact solution. Each method has its own advantages in either computational robustness, theoretical insight, or the estimation of hidden variables. The Fisher information for this likelihood distribution is calculated and analyzed to show that localization uncertainties impose a lower bound on the estimation of D. Confidence intervals are established and then used to evaluate our estimator on simulated data with experimentally relevant camera effects to demonstrate the benefit of incorporating variable localization errors.
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Affiliation(s)
- Peter K Relich
- Department of Physics and Astronomy, University of New Mexico, Mexico
| | - Mark J Olah
- Department of Physics and Astronomy, University of New Mexico, Mexico
| | | | - Keith A Lidke
- Department of Physics and Astronomy, University of New Mexico, Mexico
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220
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Reisch A, Klymchenko AS. Fluorescent Polymer Nanoparticles Based on Dyes: Seeking Brighter Tools for Bioimaging. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2016; 12:1968-92. [PMID: 26901678 PMCID: PMC5405874 DOI: 10.1002/smll.201503396] [Citation(s) in RCA: 369] [Impact Index Per Article: 46.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/07/2015] [Revised: 12/13/2015] [Indexed: 05/13/2023]
Abstract
Speed, resolution and sensitivity of today's fluorescence bioimaging can be drastically improved by fluorescent nanoparticles (NPs) that are many-fold brighter than organic dyes and fluorescent proteins. While the field is currently dominated by inorganic NPs, notably quantum dots (QDs), fluorescent polymer NPs encapsulating large quantities of dyes (dye-loaded NPs) have emerged recently as an attractive alternative. These new nanomaterials, inspired from the fields of polymeric drug delivery vehicles and advanced fluorophores, can combine superior brightness with biodegradability and low toxicity. Here, we describe the strategies for synthesis of dye-loaded polymer NPs by emulsion polymerization and assembly of pre-formed polymers. Superior brightness requires strong dye loading without aggregation-caused quenching (ACQ). Only recently several strategies of dye design were proposed to overcome ACQ in polymer NPs: aggregation induced emission (AIE), dye modification with bulky side groups and use of bulky hydrophobic counterions. The resulting NPs now surpass the brightness of QDs by ≈10-fold for a comparable size, and have started reaching the level of the brightest conjugated polymer NPs. Other properties, notably photostability, color, blinking, as well as particle size and surface chemistry are also systematically analyzed. Finally, major and emerging applications of dye-loaded NPs for in vitro and in vivo imaging are reviewed.
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Affiliation(s)
- Andreas Reisch
- Laboratoire de Biophotonique et Pharmacologie, UMR 7213 CNRS, Université de Strasbourg, Faculté de Pharmacie, 74, Route du Rhin, 67401 ILLKIRCH Cedex, France
| | - Andrey S. Klymchenko
- Laboratoire de Biophotonique et Pharmacologie, UMR 7213 CNRS, Université de Strasbourg, Faculté de Pharmacie, 74, Route du Rhin, 67401 ILLKIRCH Cedex, France
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221
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Jung J, Lin CH, Yoon YJ, Malak ST, Zhai Y, Thomas EL, Vardeny V, Tsukruk VV, Lin Z. Crafting Core/Graded Shell-Shell Quantum Dots with Suppressed Re-absorption and Tunable Stokes Shift as High Optical Gain Materials. Angew Chem Int Ed Engl 2016; 55:5071-5. [DOI: 10.1002/anie.201601198] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2016] [Indexed: 11/06/2022]
Affiliation(s)
- Jaehan Jung
- School of Materials Science and Engineering; Georgia Institute of Technology; Atlanta GA 30332 USA
| | - Chun Hao Lin
- School of Materials Science and Engineering; Georgia Institute of Technology; Atlanta GA 30332 USA
| | - Young Jun Yoon
- School of Materials Science and Engineering; Georgia Institute of Technology; Atlanta GA 30332 USA
| | - Sidney T. Malak
- School of Materials Science and Engineering; Georgia Institute of Technology; Atlanta GA 30332 USA
| | - Yaxin Zhai
- Department of Physics and Astronomy; University of Utah; Salt Lake City UT 84112 USA
| | - Edwin L. Thomas
- Department of Materials Science and Nanoengineering; Rice University; Houston TX 77251 USA
| | - Valy Vardeny
- Department of Physics and Astronomy; University of Utah; Salt Lake City UT 84112 USA
| | - Vladimir V. Tsukruk
- School of Materials Science and Engineering; Georgia Institute of Technology; Atlanta GA 30332 USA
| | - Zhiqun Lin
- School of Materials Science and Engineering; Georgia Institute of Technology; Atlanta GA 30332 USA
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222
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Jung J, Lin CH, Yoon YJ, Malak ST, Zhai Y, Thomas EL, Vardeny V, Tsukruk VV, Lin Z. Crafting Core/Graded Shell-Shell Quantum Dots with Suppressed Re-absorption and Tunable Stokes Shift as High Optical Gain Materials. Angew Chem Int Ed Engl 2016. [DOI: 10.1002/ange.201601198] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Jaehan Jung
- School of Materials Science and Engineering; Georgia Institute of Technology; Atlanta GA 30332 USA
| | - Chun Hao Lin
- School of Materials Science and Engineering; Georgia Institute of Technology; Atlanta GA 30332 USA
| | - Young Jun Yoon
- School of Materials Science and Engineering; Georgia Institute of Technology; Atlanta GA 30332 USA
| | - Sidney T. Malak
- School of Materials Science and Engineering; Georgia Institute of Technology; Atlanta GA 30332 USA
| | - Yaxin Zhai
- Department of Physics and Astronomy; University of Utah; Salt Lake City UT 84112 USA
| | - Edwin L. Thomas
- Department of Materials Science and Nanoengineering; Rice University; Houston TX 77251 USA
| | - Valy Vardeny
- Department of Physics and Astronomy; University of Utah; Salt Lake City UT 84112 USA
| | - Vladimir V. Tsukruk
- School of Materials Science and Engineering; Georgia Institute of Technology; Atlanta GA 30332 USA
| | - Zhiqun Lin
- School of Materials Science and Engineering; Georgia Institute of Technology; Atlanta GA 30332 USA
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223
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Zhang A, Bian Y, Wang J, Chen K, Dong C, Ren J. Suppressed blinking behavior of CdSe/CdS QDs by polymer coating. NANOSCALE 2016; 8:5006-5014. [PMID: 26865498 DOI: 10.1039/c5nr08504g] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Semiconductor quantum dots (QDs) are very important fluorescent nanocrystals with excellent optical properties. However, QDs, at the single-particle level, show severe fluorescence intermittency (or blinking) on a wide time scale from milliseconds to minutes, which limits certain optical and biological applications. Generally, blinking behavior of QDs strongly depends on their surface state and surrounding environment. Therefore, current blinking suppression approaches are mostly focused on the introduction of an inorganic shell and organic small molecule compounds. In this study, we described a "bottom up" approach for the synthesis of CdSe/CdS/polymer core/shell/shell QDs via the in situ one-pot polymerization approach in order to control the blinking behavior of QDs. Three monomers (dithiothreitol (DTT), phenylenediamine (PDA), and hexamethylenediamine (HDA)) were respectively used to polymerize with hexachlorocyclotriphosphazene (HCCP), and then the polyphosphazene polymers were obtained with cyclotriphosphazene as the basic macromolecular backbone. By regulating the molar ratios of the activated comonomers, we can control the blinking behavior of CdSe/CdS/polymer QDs. Under the optimal conditions, the percentage of "non-blinking" CdSe/CdS/polymer QDs (the "on time" fraction > 99% of the overall observation time) was up to 78%. The suppression mechanism was attributed to the efficient passivation of QD surface traps by the sulfhydryl or phenyl groups in the polyphosphazene polymers.
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Affiliation(s)
- Aidi Zhang
- School of Chemistry and Chemical Engineering, State Key Laboratory of Metal Matrix Composites, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, People's Republic of China.
| | - Yannan Bian
- School of Chemistry and Chemical Engineering, State Key Laboratory of Metal Matrix Composites, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, People's Republic of China.
| | - Jinjie Wang
- School of Chemistry and Chemical Engineering, State Key Laboratory of Metal Matrix Composites, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, People's Republic of China.
| | - Kuiyong Chen
- School of Materials Science and Engineering, State Key Laboratory of Metal Matrix Composites, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai, 200240, People's Republic of China
| | - Chaoqing Dong
- School of Chemistry and Chemical Engineering, State Key Laboratory of Metal Matrix Composites, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, People's Republic of China.
| | - Jicun Ren
- School of Chemistry and Chemical Engineering, State Key Laboratory of Metal Matrix Composites, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, People's Republic of China.
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224
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Bajwa P, Gao F, Nguyen A, Omogo B, Heyes CD. Influence of the Inner-Shell Architecture on Quantum Yield and Blinking Dynamics in Core/Multishell Quantum Dots. Chemphyschem 2016; 17:731-40. [PMID: 26693950 PMCID: PMC5086001 DOI: 10.1002/cphc.201500868] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2015] [Revised: 11/16/2015] [Indexed: 11/11/2022]
Abstract
Choosing the composition of a shell for QDs is not trivial, as both the band-edge energy offset and interfacial lattice mismatch influence the final optical properties. One way to balance these competing effects is by forming multishells and/or gradient-alloy shells. However, this introduces multiple interfaces, and their relative effects on quantum yield and blinking are not yet fully understood. Here, we undertake a systematic, comparative study of the addition of inner shells of a single component versus gradient-alloy shells of cadmium/zinc chalogenides onto CdSe cores, and then capping with a thin ZnS outer shell to form various core/multishell configurations. We show that architecture of the inner shell between the CdSe core and the outer ZnS shell significantly influences both the quantum yield and blinking dynamics, but that these effects are not correlated-a high ensemble quantum yield doesn't necessarily equate to reduced blinking. Two mathematical models have been proposed to describe the blinking dynamics-the more common power-law model and a more recent multiexponential model. By binning the same data with 1 and 20 ms resolution, we show that the on times can be better described by the multiexponential model, whereas the off times can be better described by the power-law model. We discuss physical mechanisms that might explain this behavior and how it can be affected by the inner-shell architecture.
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Affiliation(s)
- Pooja Bajwa
- Department of Chemistry and Biochemistry, University of Arkansas, 345 N. Campus Drive, Fayetteville, AR, 72701, USA
| | - Feng Gao
- Department of Chemistry and Biochemistry, University of Arkansas, 345 N. Campus Drive, Fayetteville, AR, 72701, USA
| | - Anh Nguyen
- Department of Chemistry and Biochemistry, University of Arkansas, 345 N. Campus Drive, Fayetteville, AR, 72701, USA
| | - Benard Omogo
- Department of Chemistry and Biochemistry, University of Arkansas, 345 N. Campus Drive, Fayetteville, AR, 72701, USA
| | - Colin D Heyes
- Department of Chemistry and Biochemistry, University of Arkansas, 345 N. Campus Drive, Fayetteville, AR, 72701, USA
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225
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Orfield NJ, McBride JR, Wang F, Buck MR, Keene JD, Reid KR, Htoon H, Hollingsworth JA, Rosenthal SJ. Quantum Yield Heterogeneity among Single Nonblinking Quantum Dots Revealed by Atomic Structure-Quantum Optics Correlation. ACS NANO 2016; 10:1960-8. [PMID: 26849531 DOI: 10.1021/acsnano.5b05876] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
Physical variations in colloidal nanostructures give rise to heterogeneity in expressed optical behavior. This correlation between nanoscale structure and function demands interrogation of both atomic structure and photophysics at the level of single nanostructures to be fully understood. Herein, by conducting detailed analyses of fine atomic structure, chemical composition, and time-resolved single-photon photoluminescence data for the same individual nanocrystals, we reveal inhomogeneity in the quantum yields of single nonblinking "giant" CdSe/CdS core/shell quantum dots (g-QDs). We find that each g-QD possesses distinctive single exciton and biexciton quantum yields that result mainly from variations in the degree of charging, rather than from volume or structure inhomogeneity. We further establish that there is a very limited nonemissive "dark" fraction (<2%) among the studied g-QDs and present direct evidence that the g-QD core must lack inorganic passivation for the g-QD to be "dark". Therefore, in contrast to conventional QDs, ensemble photoluminescence quantum yield is principally defined by charging processes rather than the existence of dark g-QDs.
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Affiliation(s)
- Noah J Orfield
- Department of Chemistry, Vanderbilt University , Nashville, Tennessee 37235, United States
- Vanderbilt Institute for Nanoscale Science and Engineering, Vanderbilt University , Nashville, Tennessee 37235, United States
| | - James R McBride
- Department of Chemistry, Vanderbilt University , Nashville, Tennessee 37235, United States
- Vanderbilt Institute for Nanoscale Science and Engineering, Vanderbilt University , Nashville, Tennessee 37235, United States
| | - Feng Wang
- Materials Physics & Applications Division: Center for Integrated Nanotechnologies, Los Alamos National Laboratory , Los Alamos, New Mexico 87545, United States
| | - Matthew R Buck
- Materials Physics & Applications Division: Center for Integrated Nanotechnologies, Los Alamos National Laboratory , Los Alamos, New Mexico 87545, United States
| | - Joseph D Keene
- Department of Chemistry, Vanderbilt University , Nashville, Tennessee 37235, United States
- Vanderbilt Institute for Nanoscale Science and Engineering, Vanderbilt University , Nashville, Tennessee 37235, United States
| | - Kemar R Reid
- Vanderbilt Institute for Nanoscale Science and Engineering, Vanderbilt University , Nashville, Tennessee 37235, United States
- Department of Interdisciplinary Materials Science, Vanderbilt University , Nashville, Tennessee 37235, United States
| | - Han Htoon
- Materials Physics & Applications Division: Center for Integrated Nanotechnologies, Los Alamos National Laboratory , Los Alamos, New Mexico 87545, United States
| | - Jennifer A Hollingsworth
- Materials Physics & Applications Division: Center for Integrated Nanotechnologies, Los Alamos National Laboratory , Los Alamos, New Mexico 87545, United States
| | - Sandra J Rosenthal
- Department of Chemistry, Vanderbilt University , Nashville, Tennessee 37235, United States
- Vanderbilt Institute for Nanoscale Science and Engineering, Vanderbilt University , Nashville, Tennessee 37235, United States
- Department of Interdisciplinary Materials Science, Vanderbilt University , Nashville, Tennessee 37235, United States
- Department of Physics and Astronomy, Vanderbilt University , Nashville, Tennessee 37235, United States
- Department of Pharmacology, Chemical and Biomolecular Engineering, Vanderbilt University , Nashville, Tennessee 37235, United States
- Materials Science and Technology Division, Oak Ridge National Laboratory , Oak Ridge, Tennessee 37831, United States
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226
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Swart I, Liljeroth P, Vanmaekelbergh D. Scanning probe microscopy and spectroscopy of colloidal semiconductor nanocrystals and assembled structures. Chem Rev 2016; 116:11181-219. [PMID: 26900754 DOI: 10.1021/acs.chemrev.5b00678] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Colloidal semiconductor nanocrystals become increasingly important in materials science and technology, due to their optoelectronic properties that are tunable by size. The measurement and understanding of their energy levels is key to scientific and technological progress. Here we review how the confined electronic orbitals and related energy levels of individual semiconductor quantum dots have been measured by means of scanning tunneling microscopy and spectroscopy. These techniques were originally developed for flat conducting surfaces, but they have been adapted to investigate the atomic and electronic structure of semiconductor quantum dots. We compare the results obtained on colloidal quantum dots with those on comparable solid-state ones. We also compare the results obtained with scanning tunneling spectroscopy with those of optical spectroscopy. The first three sections provide an introduction to colloidal quantum dots, and a theoretical basis to be able to understand tunneling spectroscopy on dots attached to a conducting surface. In sections 4 and 5 , we review the work performed on lead-chalcogenide nanocrystals and on colloidal quantum dots and rods of II-VI compounds, respectively. In section 6 , we deal with colloidal III-V nanocrystals and compare the results with their self-assembled counter parts. In section 7 , we review the work on other types of semiconductor quantum dots, especially on Si and Ge nanocrystals.
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Affiliation(s)
- Ingmar Swart
- Debye Institute for Nanomaterials Science, Chemistry Department, University of Utrecht , Princetonplein 5, 3584 CC Utrecht, The Netherlands
| | - Peter Liljeroth
- Department of Applied Physics, Aalto University School of Science , PO Box 15100, 00076 Aalto, Finland
| | - Daniel Vanmaekelbergh
- Debye Institute for Nanomaterials Science, Chemistry Department, University of Utrecht , Princetonplein 5, 3584 CC Utrecht, The Netherlands
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227
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Zhao H, Sirigu G, Parisini A, Camellini A, Nicotra G, Rosei F, Morandi V, Zavelani-Rossi M, Vomiero A. Dual emission in asymmetric "giant" PbS/CdS/CdS core/shell/shell quantum dots. NANOSCALE 2016; 8:4217-26. [PMID: 26837955 DOI: 10.1039/c5nr08881j] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Semiconducting nanocrystals optically active in the infrared region of the electromagnetic spectrum enable exciting avenues in fundamental research and novel applications compatible with the infrared transparency windows of biosystems such as chemical and biological optical sensing, including nanoscale thermometry. In this context, quantum dots (QDs) with double color emission may represent ultra-accurate and self-calibrating nanosystems. We present the synthesis of giant core/shell/shell asymmetric QDs having a PbS/CdS zinc blende (Zb)/CdS wurtzite (Wz) structure with double color emission close to the near-infrared (NIR) region. We show that the double emission depends on the excitation condition and analyze the electron-hole distribution responsible for the independent and simultaneous radiative exciton recombination in the PbS core and in the CdS Wz shell, respectively. These results highlight the importance of the driving force leading to preferential crystal growth in asymmetric QDs, and provide a pathway for the rational control of the synthesis of double color emitting giant QDs, leading to the effective exploitation of visible/NIR transparency windows.
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Affiliation(s)
- Haiguang Zhao
- CNR-INO SENSOR Lab, Via Branze 45, 25123 Brescia, Italy and Institut National de la Recherche Scientifique, 1650 Boulevard Lionel-Boulet, Varennes, Québec J3X 1S2, Canada.
| | - Gianluca Sirigu
- Dipartimento di Fisica, Politecnico di Milano, piazza L. da Vinci 32, 20133 Milano, Italy
| | - Andrea Parisini
- CNR-IMM Sezione di Bologna, Via Gobetti 101, 40129 Bologna, Italy
| | - Andrea Camellini
- Dipartimento di Fisica, Politecnico di Milano, piazza L. da Vinci 32, 20133 Milano, Italy
| | - Giuseppe Nicotra
- CNR-IMM Sezione di Catania, Strada VIII, 5, 95121 Catania, Italy
| | - Federico Rosei
- Institut National de la Recherche Scientifique, 1650 Boulevard Lionel-Boulet, Varennes, Québec J3X 1S2, Canada. and Institute for Fundamental and Frontier Science University of Electronic Science and Technology of China, Chengdu 610054, P.R. China and Center for Self-Assembled Chemical Structures, McGill University, 801 Sherbrooke Street West, Montreal, QC H3A 0B8, Canada
| | - Vittorio Morandi
- CNR-IMM Sezione di Bologna, Via Gobetti 101, 40129 Bologna, Italy
| | | | - Alberto Vomiero
- Institut National de la Recherche Scientifique, 1650 Boulevard Lionel-Boulet, Varennes, Québec J3X 1S2, Canada. and Department of Engineering Sciences and Mathematics, Luleå University of Technology, 971 98 Luleå, Sweden.
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228
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Wu K, Liang G, Kong D, Chen J, Chen Z, Shan X, McBride JR, Lian T. Quasi-type II CuInS 2/CdS core/shell quantum dots. Chem Sci 2016; 7:1238-1244. [PMID: 29910880 PMCID: PMC5975837 DOI: 10.1039/c5sc03715h] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2015] [Accepted: 11/12/2015] [Indexed: 02/03/2023] Open
Abstract
Ternary chalcopyrite CuInS2 quantum dots (QDs) have been extensively studied in recent years as an alternative to conventional QDs for solar energy conversion applications. However, compared with the well-established photophysics in prototypical CdSe QDs, much less is known about the excited properties of CuInS2 QDs. In this work, using ultrafast spectroscopy, we showed that both conduction band (CB) edge electrons and copper vacancy (VCu) localized holes were susceptible to surface trappings in CuInS2 QDs. These trap states could be effectively passivated by forming quasi-type II CuInS2/CdS core/shell QDs, leading to a single-exciton (with electrons delocalized among CuInS2/CdS CB and holes localized in VCu) half lifetime of as long as 450 ns. Because of reduced electron-hole overlap in quasi-type II QDs, Auger recombination of multiple excitons was also suppressed and the bi-exciton lifetime was prolonged to 42 ps in CuInS2/CdS QDs from 10 ps in CuInS2 QDs. These demonstrated advantages, including passivated trap states, long single and multiple exciton lifetimes, suggest that quasi-type II CuInS2/CdS QDs are promising materials for photovoltaic and photocatalytic applications.
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Affiliation(s)
- Kaifeng Wu
- Department of Chemistry , Emory University , 1515 Dickey Drive, NE , Atlanta , Georgia 30322 , USA .
| | - Guijie Liang
- Hubei Key Laboratory of Low Dimensional Optoelectronic Materials and Devices , Hubei University of Arts and Science , Xiangyang 441053 , Hubei Province , P. R. China
| | - Degui Kong
- College of Electronic Engineering , Heilongjiang University , Harbin 150080 , P. R. China
| | - Jinquan Chen
- Department of Chemistry , Emory University , 1515 Dickey Drive, NE , Atlanta , Georgia 30322 , USA .
| | - Zheyuan Chen
- Department of Chemistry , Emory University , 1515 Dickey Drive, NE , Atlanta , Georgia 30322 , USA .
| | - Xinhe Shan
- Department of Chemistry , Emory University , 1515 Dickey Drive, NE , Atlanta , Georgia 30322 , USA .
| | - James R McBride
- Department of Chemistry , The Vanderbilt Institute of Nanoscale Science and Engineering , Vanderbilt University , Nashville TN 37235 , USA
| | - Tianquan Lian
- Department of Chemistry , Emory University , 1515 Dickey Drive, NE , Atlanta , Georgia 30322 , USA .
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229
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Tomalia DA, Khanna SN. A Systematic Framework and Nanoperiodic Concept for Unifying Nanoscience: Hard/Soft Nanoelements, Superatoms, Meta-Atoms, New Emerging Properties, Periodic Property Patterns, and Predictive Mendeleev-like Nanoperiodic Tables. Chem Rev 2016; 116:2705-74. [DOI: 10.1021/acs.chemrev.5b00367] [Citation(s) in RCA: 166] [Impact Index Per Article: 20.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Affiliation(s)
- Donald A. Tomalia
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
- Department of Physics, Virginia Commonwealth University, Richmond, Virginia 23284, United States
- National Dendrimer & Nanotechnology Center, NanoSynthons LLC, 1200 North Fancher Avenue, Mt. Pleasant, Michigan 48858, United States
| | - Shiv N. Khanna
- Department
of Physics, Virginia Commonwealth University, Richmond, Virginia 23284, United States
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230
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Gawande MB, Goswami A, Asefa T, Guo H, Biradar AV, Peng DL, Zboril R, Varma RS. Core-shell nanoparticles: synthesis and applications in catalysis and electrocatalysis. Chem Soc Rev 2016; 44:7540-90. [PMID: 26288197 DOI: 10.1039/c5cs00343a] [Citation(s) in RCA: 462] [Impact Index Per Article: 57.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Core-shell nanoparticles (CSNs) are a class of nanostructured materials that have recently received increased attention owing to their interesting properties and broad range of applications in catalysis, biology, materials chemistry and sensors. By rationally tuning the cores as well as the shells of such materials, a range of core-shell nanoparticles can be produced with tailorable properties that can play important roles in various catalytic processes and offer sustainable solutions to current energy problems. Various synthetic methods for preparing different classes of CSNs, including the Stöber method, solvothermal method, one-pot synthetic method involving surfactants, etc., are briefly mentioned here. The roles of various classes of CSNs are exemplified for both catalytic and electrocatalytic applications, including oxidation, reduction, coupling reactions, etc.
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Affiliation(s)
- Manoj B Gawande
- Regional Centre of Advanced Technologies and Materials, Faculty of Science, Department of Physical Chemistry, Palacky University, Šlechtitelů 11, 783 71, Olomouc, Czech Republic.
| | - Anandarup Goswami
- Regional Centre of Advanced Technologies and Materials, Faculty of Science, Department of Physical Chemistry, Palacky University, Šlechtitelů 11, 783 71, Olomouc, Czech Republic. and Department of Chemistry and Chemical Biology, Rutgers, The State University of New Jersey, 610 Taylor Road, Piscataway, New Jersey 08854, USA
| | - Tewodros Asefa
- Department of Chemistry and Chemical Biology, Rutgers, The State University of New Jersey, 610 Taylor Road, Piscataway, New Jersey 08854, USA and Department of Chemical and Biochemical Engineering, Rutgers, The State University of New Jersey, 98 Brett Road, Piscataway, New Jersey 08854, USA
| | - Huizhang Guo
- Department of Materials Science and Engineering, College of Materials, Xiamen University, Xiamen 361005, People's Republic of China
| | - Ankush V Biradar
- Catalysis Division, CSIR-National Chemical Laboratory, Dr. Homi Bhabha Road, Pune 411008, India
| | - Dong-Liang Peng
- Department of Materials Science and Engineering, College of Materials, Xiamen University, Xiamen 361005, People's Republic of China
| | - Radek Zboril
- Regional Centre of Advanced Technologies and Materials, Faculty of Science, Department of Physical Chemistry, Palacky University, Šlechtitelů 11, 783 71, Olomouc, Czech Republic.
| | - Rajender S Varma
- Sustainable Technology Division, National Risk Management Research Laboratory, US Environmental Protection Agency, 26 West Martin Luther King Drive, MS 443, Cincinnati, Ohio 45268, USA.
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231
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Lippert LG, Hallock JT, Dadosh T, Diroll BT, Murray CB, Goldman YE. NeutrAvidin Functionalization of CdSe/CdS Quantum Nanorods and Quantification of Biotin Binding Sites using Biotin-4-Fluorescein Fluorescence Quenching. Bioconjug Chem 2016; 27:562-8. [PMID: 26722835 DOI: 10.1021/acs.bioconjchem.5b00577] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We developed methods to solubilize, coat, and functionalize with NeutrAvidin elongated semiconductor nanocrystals (quantum nanorods, QRs) for use in single molecule polarized fluorescence microscopy. Three different ligands were compared with regard to efficacy for attaching NeutrAvidin using the "zero-length cross-linker" 1-ethyl-3-[3-(dimethylamino)propyl]carbodiimide (EDC). Biotin-4-fluorescene (B4F), a fluorophore that is quenched when bound to avidin proteins, was used to quantify biotin binding activity of the NeutrAvidin coated QRs and biotin binding activity of commercially available streptavidin coated quantum dots (QDs). All three coating methods produced QRs with NeutrAvidin coating density comparable to the streptavidin coating density of the commercially available quantum dots (QDs) in the B4F assay. One type of QD available from the supplier (ITK QDs) exhibited ∼5-fold higher streptavidin surface density compared to our QRs, whereas the other type of QD (PEG QDs) had 5-fold lower density. The number of streptavidins per QD increased from ∼7 streptavidin tetramers for the smallest QDs emitting fluorescence at 525 nm (QD525) to ∼20 tetramers for larger, longer wavelength QDs (QD655, QD705, and QD800). QRs coated with NeutrAvidin using mercaptoundecanoicacid (MUA) and QDs coated with streptavidin bound to biotinylated cytoplasmic dynein in single molecule TIRF microscopy assays, whereas Poly(maleic anhydride-alt-1-ocatdecene) (PMAOD) or glutathione (GSH) QRs did not bind cytoplasmic dynein. The coating methods require optimization of conditions and concentrations to balance between substantial NeutrAvidin binding vs tendency of QRs to aggregate and degrade over time.
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Affiliation(s)
| | | | - Tali Dadosh
- Electron Microscopy Unit, Department of Chemical Research Support, Weizmann Institute of Science , Rehovot 7610001, Israel
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232
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van der Stam W, Bladt E, Rabouw FT, Bals S, de Mello Donega C. Near-Infrared Emitting CuInSe₂/CuInS₂ Dot Core/Rod Shell Heteronanorods by Sequential Cation Exchange. ACS NANO 2015; 9:11430-8. [PMID: 26449673 PMCID: PMC4660388 DOI: 10.1021/acsnano.5b05496] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
The direct synthesis of heteronanocrystals (HNCs) combining different ternary semiconductors is challenging and has not yet been successful. Here, we report a sequential topotactic cation exchange (CE) pathway that yields CuInSe2/CuInS2 dot core/rod shell nanorods with near-infrared luminescence. In our approach, the Cu(+) extraction rate is coupled to the In(3+) incorporation rate by the use of a stoichiometric trioctylphosphine-InCl3 complex, which fulfills the roles of both In-source and Cu-extracting agent. In this way, Cu(+) ions can be extracted by trioctylphosphine ligands only when the In-P bond is broken. This results in readily available In(3+) ions at the same surface site from which the Cu(+) is extracted, making the process a direct place exchange reaction and shifting the overall energy balance in favor of the CE. Consequently, controlled cation exchange can occur even in large and anisotropic heterostructured nanocrystals with preservation of the size, shape, and heterostructuring of the template NCs into the product NCs. The cation exchange is self-limited, stopping when the ternary core/shell CuInSe2/CuInS2 composition is reached. The method is very versatile, successfully yielding a variety of luminescent CuInX2 (X = S, Se, and Te) quantum dots, nanorods, and HNCs, by using Cd-chalcogenide NCs and HNCs as templates. The approach reported here thus opens up routes toward materials with unprecedented properties, which would otherwise remain inaccessible.
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Affiliation(s)
- Ward van der Stam
- Debye Institute for Nanomaterials Science, Utrecht University, P.O. Box 80000, 3508 TA Utrecht, The Netherlands
| | - Eva Bladt
- Electron Microscopy for Materials Science (EMAT), University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp, Belgium
| | - Freddy T. Rabouw
- Debye Institute for Nanomaterials Science, Utrecht University, P.O. Box 80000, 3508 TA Utrecht, The Netherlands
| | - Sara Bals
- Electron Microscopy for Materials Science (EMAT), University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp, Belgium
| | - Celso de Mello Donega
- Debye Institute for Nanomaterials Science, Utrecht University, P.O. Box 80000, 3508 TA Utrecht, The Netherlands
- Address correspondence to
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233
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Zhao H, Vomiero A, Rosei F. Ultrasensitive, Biocompatible, Self-Calibrating, Multiparametric Temperature Sensors. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2015; 11:5741-6. [PMID: 26467511 DOI: 10.1002/smll.201502249] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/28/2015] [Revised: 08/31/2015] [Indexed: 05/20/2023]
Abstract
Core-shell quantum dots serve as self-calibrating, ultrasensitive, multiparametric, near-infrared, and biocompatible temperature sensors. They allow temperature measurement with nanometer accuracy in the range 150-373 K, the broadest ever recorded for a nanothermometer, with sensitivities among the highest ever reported, which makes them essentially unique in the panorama of biocompatible nanothermometers with potential for in vivo biological thermal imaging and/or thermoablative therapy.
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Affiliation(s)
- Haiguang Zhao
- CNR INO SENSOR Lab, Via Branze 45, Brescia, 25123, Italy
- Centre for Energy, Materials and Telecommunications, Institut National de la Recherche Scientifique, 1650 Boulevard Lionel-Boulet, Varennes, Québec, J3X 1S2, Canada
| | - Alberto Vomiero
- CNR INO SENSOR Lab, Via Branze 45, Brescia, 25123, Italy
- Department of Engineering Sciences and Mathematics, Luleå University of Technology, Luleå, 971 98, Sweden
| | - Federico Rosei
- Centre for Energy, Materials and Telecommunications, Institut National de la Recherche Scientifique, 1650 Boulevard Lionel-Boulet, Varennes, Québec, J3X 1S2, Canada
- Institute for Fundamental and Frontier Science, University of Electronic Science and Technology of China, Chengdu, 610054, P. R. China
- Center for Self-Assembled Chemical Structures, McGill University, Montreal, Quebec, H3A 2K6, Canada
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234
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Swarnkar A, Chulliyil R, Ravi VK, Irfanullah M, Chowdhury A, Nag A. Colloidal CsPbBr3 Perovskite Nanocrystals: Luminescence beyond Traditional Quantum Dots. Angew Chem Int Ed Engl 2015; 54:15424-8. [PMID: 26546495 DOI: 10.1002/anie.201508276] [Citation(s) in RCA: 421] [Impact Index Per Article: 46.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2015] [Indexed: 11/12/2022]
Abstract
Traditional CdSe-based colloidal quantum dots (cQDs) have interesting photoluminescence (PL) properties. Herein we highlight the advantages in both ensemble and single-nanocrystal PL of colloidal CsPbBr3 nanocrystals (NCs) over the traditional cQDs. An ensemble of colloidal CsPbBr3 NCs (11 nm) exhibits ca. 90 % PL quantum yield with narrow (FWHM=86 meV) spectral width. Interestingly, the spectral width of a single-NC and an ensemble are almost identical, ruling out the problem of size-distribution in PL broadening. Eliminating this problem leads to a negligible influence of self-absorption and Förster resonance energy transfer, along with batch-to-batch reproducibility of NCs exhibiting PL peaks within ±1 nm. Also, PL peak positions do not alter with measurement temperature in the range of 25 to 100 °C. Importantly, CsPbBr3 NCs exhibit suppressed PL blinking with ca. 90 % of the individual NCs remain mostly emissive (on-time >85 %), without much influence of excitation power.
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Affiliation(s)
- Abhishek Swarnkar
- Department of Chemistry, Indian Institute of Science Education and Research (IISER), Pune 411008 (India)
| | - Ramya Chulliyil
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400076 (India)
| | - Vikash Kumar Ravi
- Department of Chemistry, Indian Institute of Science Education and Research (IISER), Pune 411008 (India)
| | - Mir Irfanullah
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400076 (India)
| | - Arindam Chowdhury
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400076 (India)
| | - Angshuman Nag
- Department of Chemistry, Indian Institute of Science Education and Research (IISER), Pune 411008 (India).
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235
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Swarnkar A, Chulliyil R, Ravi VK, Irfanullah M, Chowdhury A, Nag A. Colloidal CsPbBr3Perovskite Nanocrystals: Luminescence beyond Traditional Quantum Dots. Angew Chem Int Ed Engl 2015. [DOI: 10.1002/ange.201508276] [Citation(s) in RCA: 288] [Impact Index Per Article: 32.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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236
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Lifshitz E. Evidence in Support of Exciton to Ligand Vibrational Coupling in Colloidal Quantum Dots. J Phys Chem Lett 2015; 6:4336-4347. [PMID: 26538048 DOI: 10.1021/acs.jpclett.5b01567] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The Perspective focuses on the investigation of an unresolved conflict in semiconductor colloidal quantum dots (CQDs) research, concerning the influence of the immediate surrounding on the optical properties of the materials. Today's advanced synthetic colloidal procedures offer formation of a high-quality inorganic crystallite, capped with various organic/inorganic molecular ligands. The Perspective aims to clarify whether exciton recombination processes in CQDs are influenced by the type of crystallite-ligand bonding and, moreover, whether these excitonic processes experience direct coupling to the ligands' vibrational modes. Most ligands used have redox characteristics whose functional groups are added on to the CQDs' surface via coordination, covalent or ionic bonding. The surface-ligand bonding introduces electronic states either above or below the intraband/interband energy gap, resulting in electronic passivation or in creation of trapping states that affect intraband and interband relaxation processes. Furthermore, crystalline electronic states may have a direct coupling to molecular vibrational states via direct overlap of electronic wave functions or through a long-range energy-transfer process. Also, photoejected carriers resulting from an Auger process or ionization processes may diffuse temporarily onto a ligand site. These scenarios are discussed in the current publication with supporting theoretical and experimental observations.
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Affiliation(s)
- Efrat Lifshitz
- Schulich Faculty of Chemistry, Russell Berrie Nanotechnology Institute, Solid State Institute, Technion, Israel Institute of Technology , Haifa 32000, Israel
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237
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Reeves KG, Schleife A, Correa AA, Kanai Y. Role of Surface Termination on Hot Electron Relaxation in Silicon Quantum Dots: A First-Principles Dynamics Simulation Study. NANO LETTERS 2015; 15:6429-6433. [PMID: 26331672 DOI: 10.1021/acs.nanolett.5b01707] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The role of surface termination on phonon-mediated relaxation of an excited electron in quantum dots was investigated using first-principles simulations. The surface terminations of a silicon quantum dot with hydrogen and fluorine atoms lead to distinctively different relaxation behaviors, and the fluorine termination shows a nontrivial relaxation process. The quantum confined electronic states are significantly affected by the surface of the quantum dot, and we find that a particular electronic state dictates the relaxation behavior through its infrequent coupling to neighboring electronic states. Dynamical fluctuation of this electronic state results in a slow shuttling behavior within the manifold of unoccupied electronic states, controlling the overall dynamics of the excited electron with its characteristic frequency of this shuttling behavior. The present work revealed a unique role of surface termination, dictating the hot electron relaxation process in quantum-confined systems in the way that has not been considered previously.
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Affiliation(s)
- Kyle G Reeves
- Department of Chemistry, University of North Carolina at Chapel Hill , Chapel Hill, North Carolina 27514, United States
| | - André Schleife
- Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign , Champaign, Illinois 61820, United States
| | - Alfredo A Correa
- Condensed Matter and Materials Division, Lawrence Livermore National Laboratory , Livermore, California 94550, United States
| | - Yosuke Kanai
- Department of Chemistry, University of North Carolina at Chapel Hill , Chapel Hill, North Carolina 27514, United States
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238
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Non-blinking (Zn)CuInS/ZnS Quantum Dots Prepared by In Situ Interfacial Alloying Approach. Sci Rep 2015; 5:15227. [PMID: 26458511 PMCID: PMC4602315 DOI: 10.1038/srep15227] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2015] [Accepted: 09/15/2015] [Indexed: 11/09/2022] Open
Abstract
Semiconductor quantum dots (QDs) are very important optical nanomaterials with a wide range of potential applications. However, blinking behavior of single QD is an intrinsic drawback for some biological and photoelectric applications based on single-particle emission. Herein we present a rational strategy for fabrication of non-blinking (Zn)CuInS/ZnS QDs in organic phase through in situ interfacial alloying approach. This new strategy includes three steps: synthesis of CuInS QDs, eliminating the interior traps of QDs by forming graded (Zn)CuInS alloyed QDs, modifying the surface traps of QDs by introducing ZnS shells onto (Zn)CuInS QDs using alkylthiols as sulfur source and surface ligands. The suppressed blinking mechanism was mainly attributed to modifying QDs traps from interior to exterior via a step-by-step modification. Non-blinking QDs show high quantum yield, symmetric emission spectra and excellent crystallinity, and will enable applications from biology to optoelectronics that were previously hindered by blinking behavior of traditional QDs.
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239
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Grim JQ, Manna L, Moreels I. A sustainable future for photonic colloidal nanocrystals. Chem Soc Rev 2015; 44:5897-914. [PMID: 26084788 DOI: 10.1039/c5cs00285k] [Citation(s) in RCA: 103] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Colloidal nanocrystals - produced in a growing variety of shapes, sizes and compositions - are rapidly developing into a new generation of photonic materials, spanning light emitting as well as energy harvesting applications. Precise tailoring of their optoelectronic properties enables them to satisfy disparate application-specific requirements. However, the presence of toxic heavy metals such as cadmium and lead in some of the most mature nanocrystals is a serious drawback which may ultimately preclude their use in consumer applications. Although the pursuit of non-toxic alternatives has occurred in parallel to the well-developed Cd- and Pb-based nanocrystals, synthetic challenges have, until recently, curbed progress. In this review, we highlight recent advances in the development of heavy-metal-free nanocrystals within the context of specific photonic applications. We also describe strategies to transfer some of the advantageous nanocrystal features such as shape control to non-toxic materials. Finally, we present recent developments that have the potential to make substantial impacts on the quest to attain a balance between performance and sustainability in photonics.
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Affiliation(s)
- Joel Q Grim
- Nanochemistry Department, Istituto Italiano di Tecnologia, Via Morego 30, IT-16163 Genova, Italy.
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240
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Hu Z, Xu S, Xu X, Wang Z, Wang Z, Wang C, Cui Y. Co-doping of Ag into Mn:ZnSe Quantum Dots: Giving Optical Filtering effect with Improved Monochromaticity. Sci Rep 2015; 5:14817. [PMID: 26446850 PMCID: PMC4597225 DOI: 10.1038/srep14817] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2015] [Accepted: 09/10/2015] [Indexed: 11/21/2022] Open
Abstract
In optics, when polychromatic light is filtered by an optical filter, the monochromaticity of the light can be improved. In this work, we reported that Ag dopant atoms could be used as an optical filter for nanosized Mn:ZnSe quantum dots (QDs). If no Ag doping, aqueous Mn:ZnSe QDs have low monochromaticity due to coexisting of strong ZnSe band gap emission, ZnSe trap emission, and Mn dopant emission. After doping of Ag into QDs, ZnSe band gap and ZnSe trap emissions can be filtered, leaving only Mn dopant emission with improved monochromaticity. The mechanism for the optical filtering effect of Ag was investigated. The results indicate that the doping of Ag will introduce a new faster deactivation process from ZnSe conduction band to Ag energy level, leading to less electrons deactived via ZnSe band gap emission and ZnSe trap emission. As a result, only Mn dopant emission is left.
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Affiliation(s)
- Zhiyang Hu
- Advanced Photonics Center, School of Electronic Science and Engineering, Southeast University, Nanjing, 210096 (P. R. China)
| | - Shuhong Xu
- Advanced Photonics Center, School of Electronic Science and Engineering, Southeast University, Nanjing, 210096 (P. R. China)
| | - Xiaojing Xu
- Advanced Photonics Center, School of Electronic Science and Engineering, Southeast University, Nanjing, 210096 (P. R. China)
| | - Zhaochong Wang
- Advanced Photonics Center, School of Electronic Science and Engineering, Southeast University, Nanjing, 210096 (P. R. China)
| | - Zhuyuan Wang
- Advanced Photonics Center, School of Electronic Science and Engineering, Southeast University, Nanjing, 210096 (P. R. China)
| | - Chunlei Wang
- Advanced Photonics Center, School of Electronic Science and Engineering, Southeast University, Nanjing, 210096 (P. R. China)
| | - Yiping Cui
- Advanced Photonics Center, School of Electronic Science and Engineering, Southeast University, Nanjing, 210096 (P. R. China)
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241
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Lim SJ, Zahid MU, Le P, Ma L, Entenberg D, Harney AS, Condeelis J, Smith AM. Brightness-equalized quantum dots. Nat Commun 2015; 6:8210. [PMID: 26437175 PMCID: PMC4594210 DOI: 10.1038/ncomms9210] [Citation(s) in RCA: 72] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2014] [Accepted: 07/29/2015] [Indexed: 11/17/2022] Open
Abstract
As molecular labels for cells and tissues, fluorescent probes have shaped our understanding of biological structures and processes. However, their capacity for quantitative analysis is limited because photon emission rates from multicolour fluorophores are dissimilar, unstable and often unpredictable, which obscures correlations between measured fluorescence and molecular concentration. Here we introduce a new class of light-emitting quantum dots with tunable and equalized fluorescence brightness across a broad range of colours. The key feature is independent tunability of emission wavelength, extinction coefficient and quantum yield through distinct structural domains in the nanocrystal. Precise tuning eliminates a 100-fold red-to-green brightness mismatch of size-tuned quantum dots at the ensemble and single-particle levels, which substantially improves quantitative imaging accuracy in biological tissue. We anticipate that these materials engineering principles will vastly expand the optical engineering landscape of fluorescent probes, facilitate quantitative multicolour imaging in living tissue and improve colour tuning in light-emitting devices. Quantum dots with different size emit light at different wavelengths but also different brightness, which complicates analysis of fluorescence images. Here, the authors synthesize multicolour brightness-equalized quantum dots by controlling the composition and structure of core-shell HgCdSeS-CdZnS nanocrystals.
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Affiliation(s)
- Sung Jun Lim
- Department of Bioengineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA.,Micro and Nanotechnology Laboratory, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
| | - Mohammad U Zahid
- Department of Bioengineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA.,Micro and Nanotechnology Laboratory, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
| | - Phuong Le
- Department of Bioengineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA.,Micro and Nanotechnology Laboratory, 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
| | - David Entenberg
- Department of Anatomy and Structural Biology, Albert Einstein College of Medicine of Yeshiva University, Bronx, New York 10461, USA.,Integrated Imaging Program, Albert Einstein College of Medicine of Yeshiva University, Bronx, New York 10461, USA.,Gruss-Lipper Biophotonics Center, Albert Einstein College of Medicine of Yeshiva University, Bronx, New York 10461, USA
| | - Allison S Harney
- Department of Anatomy and Structural Biology, Albert Einstein College of Medicine of Yeshiva University, Bronx, New York 10461, USA.,Integrated Imaging Program, Albert Einstein College of Medicine of Yeshiva University, Bronx, New York 10461, USA.,Gruss-Lipper Biophotonics Center, Albert Einstein College of Medicine of Yeshiva University, Bronx, New York 10461, USA.,Department of Radiology, Albert Einstein College of Medicine of Yeshiva University, Bronx, New York 10461, USA
| | - John Condeelis
- Department of Anatomy and Structural Biology, Albert Einstein College of Medicine of Yeshiva University, Bronx, New York 10461, USA.,Integrated Imaging Program, Albert Einstein College of Medicine of Yeshiva University, Bronx, New York 10461, USA.,Gruss-Lipper Biophotonics Center, Albert Einstein College of Medicine of Yeshiva University, Bronx, New York 10461, USA
| | - Andrew M Smith
- Department of Bioengineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA.,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
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242
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Wang F, Karan NS, Nguyen HM, Mangum BD, Ghosh Y, Sheehan CJ, Hollingsworth JA, Htoon H. Quantum Optical Signature of Plasmonically Coupled Nanocrystal Quantum Dots. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2015; 11:5028-34. [PMID: 26140499 DOI: 10.1002/smll.201500823] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/24/2015] [Revised: 05/23/2015] [Indexed: 05/28/2023]
Abstract
Small clusters of two to three silica-coated nanocrystals coupled to plasmonic gap-bar antennas can exhibit photon antibunching, a characteristic of single quantum emitters. Through a detailed analysis of their photoluminescence emissions characteristics, it is shown that the observed photon antibunching is the evidence of coupled quantum dot formation resulting from the plasmonic enhancement of dipole-dipole interaction.
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Affiliation(s)
- Feng Wang
- Center for Integrated Nanotechnologies, Materials Physics & Applications Division, Los Alamos National Laboratory, Los Alamos, NM, 87545, USA
| | - Niladri S Karan
- Center for Integrated Nanotechnologies, Materials Physics & Applications Division, Los Alamos National Laboratory, Los Alamos, NM, 87545, USA
| | - Hue Minh Nguyen
- Center for Integrated Nanotechnologies, Materials Physics & Applications Division, Los Alamos National Laboratory, Los Alamos, NM, 87545, USA
| | - Benjamin D Mangum
- Center for Integrated Nanotechnologies, Materials Physics & Applications Division, Los Alamos National Laboratory, Los Alamos, NM, 87545, USA
| | - Yagnaseni Ghosh
- Center for Integrated Nanotechnologies, Materials Physics & Applications Division, Los Alamos National Laboratory, Los Alamos, NM, 87545, USA
| | - Chris J Sheehan
- Center for Integrated Nanotechnologies, Materials Physics & Applications Division, Los Alamos National Laboratory, Los Alamos, NM, 87545, USA
| | - Jennifer A Hollingsworth
- Center for Integrated Nanotechnologies, Materials Physics & Applications Division, Los Alamos National Laboratory, Los Alamos, NM, 87545, USA
| | - Han Htoon
- Center for Integrated Nanotechnologies, Materials Physics & Applications Division, Los Alamos National Laboratory, Los Alamos, NM, 87545, USA
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243
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Li Z, Yao W, Kong L, Zhao Y, Li L. General Method for the Synthesis of Ultrastable Core/Shell Quantum Dots by Aluminum Doping. J Am Chem Soc 2015; 137:12430-3. [PMID: 26389704 DOI: 10.1021/jacs.5b05462] [Citation(s) in RCA: 79] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Semiconductor quantum dots (QDs) have attracted extensive attention in various applications because of their unique optical and electronic properties. However, long-term photostability remains a challenge for their practical application. Here, we present a simple method to enhance the photostability of QDs against oxidation by doping aluminum into the shell of core/shell QDs. We demonstrate that Al in the coating shell can be oxidized to Al2O3, which can serve as a self-passivation layer on the surface of the core/shell QDs and effectively stop further photodegradation during long-term light irradiation. The prepared CdSe/CdS:Al QDs survived 24 h without significant degradation when they were subjected to intense illumination under LED light (450 nm, 0.35 W/cm(2)), whereas conventional CdSe/CdS QDs were bleached within 3 h.
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Affiliation(s)
- Zhichun Li
- School of Environmental Science and Engineering, Shanghai Jiao Tong University , 800 Dongchuan Road, Shanghai 200240, China
| | - Wei Yao
- School of Environmental Science and Engineering, Shanghai Jiao Tong University , 800 Dongchuan Road, Shanghai 200240, China
| | - Long Kong
- School of Environmental Science and Engineering, Shanghai Jiao Tong University , 800 Dongchuan Road, Shanghai 200240, China
| | - Yixin Zhao
- School of Environmental Science and Engineering, Shanghai Jiao Tong University , 800 Dongchuan Road, Shanghai 200240, China
| | - Liang Li
- School of Environmental Science and Engineering, Shanghai Jiao Tong University , 800 Dongchuan Road, Shanghai 200240, China
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244
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Zang H, Cristea M, Shen X, Liu M, Camino F, Cotlet M. Charge trapping and de-trapping in isolated CdSe/ZnS nanocrystals under an external electric field: indirect evidence for a permanent dipole moment. NANOSCALE 2015; 7:14897-14905. [PMID: 26293119 DOI: 10.1039/c5nr03714j] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Single nanoparticle studies of charge trapping and de-trapping in core/shell CdSe/ZnS nanocrystals incorporated into an insulating matrix and subjected to an external electric field demonstrate the ability to reversibly modulate the exciton dynamics and photoluminescence blinking while providing indirect evidence for the existence of a permanent ground state dipole moment in such nanocrystals. A model assuming the presence of energetically deep charge traps physically aligned along the direction of the permanent dipole is proposed in order to explain the dynamics of nanocrystal blinking in the presence of a permanent dipole moment.
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Affiliation(s)
- Huidong Zang
- Center for Functional Nanomaterials, Brookhaven National Laboratory, Upton, NY 11973, USA.
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245
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Coupling Single Giant Nanocrystal Quantum Dots to the Fundamental Mode of Patch Nanoantennas through Fringe Field. Sci Rep 2015; 5:14313. [PMID: 26394763 PMCID: PMC4585802 DOI: 10.1038/srep14313] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2015] [Accepted: 08/25/2015] [Indexed: 01/07/2023] Open
Abstract
Through single dot spectroscopy and numerical simulation studies, we demonstrate that the fundamental mode of gold patch nanoantennas have fringe-field resonance capable of enhancing the nano-emitters coupled around the edge of the patch antenna. This fringe-field coupling is used to enhance the radiative rates of core/thick-shell nanocrystal quantum dots (g-NQDs) that cannot be embedded into the ultra-thin dielectric gap of patch nanoantennas due to their large sizes. We attain 14 and 3 times enhancements in single exciton radiative decay rate and bi-exciton emission efficiencies of g-NQDs respectively, with no detectable metal quenching. Our numerical studies confirmed our experimental results and further reveal that patch nanoantennas can provide strong emission enhancement for dipoles lying not only in radial direction of the circular patches but also in the direction normal to the antennas surface. This provides a distinct advantage over the parallel gap-bar antennas that can provide enhancement only for the dipoles oriented across the gap.
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246
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Lane LA, Qian X, Nie S. SERS Nanoparticles in Medicine: From Label-Free Detection to Spectroscopic Tagging. Chem Rev 2015; 115:10489-529. [DOI: 10.1021/acs.chemrev.5b00265] [Citation(s) in RCA: 607] [Impact Index Per Article: 67.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Lucas A. Lane
- Departments
of Biomedical Engineering and Chemistry, Emory University and Georgia Institute of Technology, Health Sciences Research Building,
Room E116, 1760 Haygood Drive, Atlanta, Georgia 30322, United States
| | - Ximei Qian
- Departments
of Biomedical Engineering and Chemistry, Emory University and Georgia Institute of Technology, Health Sciences Research Building,
Room E116, 1760 Haygood Drive, Atlanta, Georgia 30322, United States
| | - Shuming Nie
- Departments
of Biomedical Engineering and Chemistry, Emory University and Georgia Institute of Technology, Health Sciences Research Building,
Room E116, 1760 Haygood Drive, Atlanta, Georgia 30322, United States
- College
of Engineering and Applied Sciences, Nanjing University, 22 Hankou
Road, Nanjing, Jiangsu Province 210093, China
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247
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Jensen RA, Coropceanu I, Chen Y, Bawendi MG. Thermal Recovery of Colloidal Quantum Dot Ensembles Following Photoinduced Dimming. J Phys Chem Lett 2015; 6:2933-2937. [PMID: 26267184 DOI: 10.1021/acs.jpclett.5b00989] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Colloidal CdSe quantum dot (QD) core ensembles were photodimmed and allowed to recover in the dark using ambient thermal energy at a range of temperatures. Nonlinear thermal recovery is well described by a stretched exponential function, and further analysis yields an underlying probability distribution of rate constants. Casting the rate constants as a collection of first-order activated processes provides an activation barrier probability distribution with significant density at room-temperature thermal energy that peaks at 200 meV before decaying to zero. This treatment for the recovery transition intuitively describes the distributed kinetics observed and complements commonly proposed blinking mechanisms.
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Affiliation(s)
- Russell A Jensen
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Igor Coropceanu
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Yue Chen
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Moungi G Bawendi
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
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248
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Abstract
Strain in colloidal heteronanocrystals with non-centrosymmetric lattices presents a unique opportunity for controlling optoelectronic properties and adds a new degree of freedom to existing wavefunction engineering and doping paradigms. We synthesized wurtzite CdSe nanorods embedded in a thick CdS shell, hereby exploiting the large lattice mismatch between the two domains to generate a compressive strain of the CdSe core and a strong piezoelectric potential along its c-axis. Efficient charge separation results in an indirect ground-state transition with a lifetime of several microseconds, almost one order of magnitude longer than any other CdSe/CdS nanocrystal. Higher excited states recombine radiatively in the nanosecond time range, due to increasingly overlapping excited-state orbitals. k̇p calculations confirm the importance of the anisotropic shape and crystal structure in the buildup of the piezoelectric potential. Strain engineering thus presents an efficient approach to highly tunable single- and multiexciton interactions, driven by a dedicated core/shell nanocrystal design. Quantum dots confine electrons to a nanometre length scale, and this gives rise to numerous quantum effects. Here, the authors directly control the excitonic structure of nanocrystal quantum dots by manipulating intra-particle piezoelectric fields.
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249
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Nanayakkara SU, van de Lagemaat J, Luther JM. Scanning Probe Characterization of Heterostructured Colloidal Nanomaterials. Chem Rev 2015. [PMID: 26196958 DOI: 10.1021/cr500280t] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Affiliation(s)
- Sanjini U. Nanayakkara
- National Renewable Energy Laboratory, 15013 Denver
West Parkway, Golden, Colorado 80401, United States
| | - Jao van de Lagemaat
- National Renewable Energy Laboratory, 15013 Denver
West Parkway, Golden, Colorado 80401, United States
| | - Joseph M. Luther
- National Renewable Energy Laboratory, 15013 Denver
West Parkway, Golden, Colorado 80401, United States
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250
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Coopersmith K, Han H, Maye MM. Stepwise Assembly and Characterization of DNA Linked Two-Color Quantum Dot Clusters. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2015; 31:7463-7471. [PMID: 26086169 DOI: 10.1021/acs.langmuir.5b01130] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The DNA-mediated self-assembly of multicolor quantum dot (QD) clusters via a stepwise approach is described. The CdSe/ZnS QDs were synthesized and functionalized with an amphiphilic copolymer, followed by ssDNA conjugation. At each functionalization step, the QDs were purified via gradient ultracentrifugation, which was found to remove excess polymer and QD aggregates, allowing for improved conjugation yields and assembly reactivity. The QDs were then assembled and disassembled in a stepwise manner at a ssDNA functionalized magnetic colloid, which provided a convenient way to remove unreacted QDs and ssDNA impurities. After assembly/disassembly, the clusters' optical characteristics were studied by fluorescence spectroscopy and the assembly morphology and stoichiometry was imaged via electron microscopy. The results indicate that a significant amount of QD-to-QD energy transfer occurred in the clusters, which was studied as a function of increasing acceptor-to-donor ratios, resulting in increased QD acceptor emission intensities compared to controls.
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Affiliation(s)
- Kaitlin Coopersmith
- Department of Chemistry, Syracuse University, Syracuse, New York 13244, United States
| | - Hyunjoo Han
- Department of Chemistry, Syracuse University, Syracuse, New York 13244, United States
| | - Mathew M Maye
- Department of Chemistry, Syracuse University, Syracuse, New York 13244, United States
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