1
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Martins JR, Krivenkov V, Bernardo CR, Samokhvalov P, Nabiev I, Rakovich YP, Vasilevskiy MI. Statistical Analysis of Photoluminescence Decay Kinetics in Quantum Dot Ensembles: Effects of Inorganic Shell Composition and Environment. THE JOURNAL OF PHYSICAL CHEMISTRY. C, NANOMATERIALS AND INTERFACES 2022; 126:20480-20490. [PMID: 36523488 PMCID: PMC9743207 DOI: 10.1021/acs.jpcc.2c06134] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/29/2022] [Revised: 11/05/2022] [Indexed: 06/17/2023]
Abstract
Discerning the kinetics of photoluminescence (PL) decay of packed quantum dots (QDs) and QD-based hybrid materials is of crucial importance for achieving their promising potential. However, the interpretation of the decay kinetics of QD-based systems, which usually are not single-exponential, remains challenging. Here, we present a method for analyzing photoluminescence (PL) decay curves of fluorophores by studying their statistical moments. A certain combination of such moments, named as the n-th order moments' ratio, R n , is studied for several theoretical decay curves and experimental PL kinetics of CdSe quantum dots (QDs) acquired by time-correlated single photon counting (TCSPC). For the latter, three different case studies using the R n ratio analysis are presented, namely, (i) the effect of the inorganic shell composition and thickness of the core-shell QDs, (ii) QD systems with Förster resonance energy transfer (FRET) decay channels, and (iii) system of QDs near a layer of plasmonic nanoparticles. The proposed method is shown to be efficient for the detection of slight changes in the PL kinetics, being time-efficient and requiring low computing power for performing the analysis. It can also be a powerful tool to identify the most appropriate physically meaningful theoretical decay function, which best describes the systems under study.
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Affiliation(s)
- João R. Martins
- Center
of Physics-CF-UM-UP, Laboratório de Física para Materiais
e Tecnologias Emergentes (LaPMET), University
of Minho, 4710-057Braga, Portugal
| | - Victor Krivenkov
- Department
of Polymers and Advanced Materials: Physics, Chemistry and Technology, University of Basque Country (UPV/EHU), and Materials
Physics Center (CFM, CSIC-UPV/EHU), 20018Donostia-San Sebastian, Spain
| | - César R. Bernardo
- Center
of Physics-CF-UM-UP, Laboratório de Física para Materiais
e Tecnologias Emergentes (LaPMET), University
of Minho, 4710-057Braga, Portugal
| | - Pavel Samokhvalov
- Laboratory
of Nano-Bioengineering, National Research
Nuclear University MEPhI (Moscow Engineering Physics Institute), 115409Moscow, Russian Federation
| | - Igor Nabiev
- Laboratory
of Research in Nanosciences, University
of Reims Champagne-Ardenne, 51100Reims, France
| | - Yury P. Rakovich
- Department
of Polymers and Advanced Materials: Physics, Chemistry and Technology, University of Basque Country (UPV/EHU), and Materials
Physics Center (CFM, CSIC-UPV/EHU), 20018Donostia-San Sebastian, Spain
- Donostia
International Physics Centre (DIPC), 20018Donostia-San Sebastian, Spain
| | - Mikhail I. Vasilevskiy
- Center
of Physics-CF-UM-UP, Laboratório de Física para Materiais
e Tecnologias Emergentes (LaPMET), University
of Minho, 4710-057Braga, Portugal
- Theory of
Quantum Nanostructures Group, International
Iberian Nano Laboratory (INL), 4715-330Braga, Portugal
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2
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Liu S, Shu Y, Zhu M, Qin H, Peng X. Anomalous Emission Shift of CdSe/CdS/ZnS Quantum Dots at Cryogenic Temperatures. NANO LETTERS 2022; 22:3011-3017. [PMID: 35319213 DOI: 10.1021/acs.nanolett.2c00220] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
The band-gap energy of most bulk semiconductors tends to increase as the temperature decreases. However, non-monotonic temperature dependence of the emission energy has been observed in semiconductor quantum dots (QDs) at cryogenic temperatures. Here, using stable and highly efficient CdSe/CdS/ZnS QDs as the model system, we quantitatively reveal the origins of the anomalous emission red-shift (∼8 meV) below 40 K by correlating ensemble and single QD spectroscopy measurements. About one-quarter of the anomalous red-shift (∼2.2 meV) is caused by the temperature-dependent population of the band-edge exciton fine levels. The enhancement of electron-optical phonon coupling caused by the increasing population of dark excitons with temperature decreases contributes an ∼3.4 meV red-shift. The remaining ∼2.4 meV red-shift is attributed to temperature-dependent electron-acoustic phonon coupling.
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Affiliation(s)
- Shaojie Liu
- Key Laboratory of Excited-State Materials of Zhejiang Province and Department of Chemistry, Zhejiang University, Hangzhou, 310027, China
| | - Yufei Shu
- Key Laboratory of Excited-State Materials of Zhejiang Province and Department of Chemistry, Zhejiang University, Hangzhou, 310027, China
| | - Meiyi Zhu
- Key Laboratory of Excited-State Materials of Zhejiang Province and Department of Chemistry, Zhejiang University, Hangzhou, 310027, China
| | - Haiyan Qin
- Key Laboratory of Excited-State Materials of Zhejiang Province and Department of Chemistry, Zhejiang University, Hangzhou, 310027, China
| | - Xiaogang Peng
- Key Laboratory of Excited-State Materials of Zhejiang Province and Department of Chemistry, Zhejiang University, Hangzhou, 310027, China
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3
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Dieleman C, van der Burgt J, Thakur N, Garnett EC, Ehrler B. Direct Patterning of CsPbBr 3 Nanocrystals via Electron-Beam Lithography. ACS APPLIED ENERGY MATERIALS 2022; 5:1672-1680. [PMID: 35252773 PMCID: PMC8889902 DOI: 10.1021/acsaem.1c03091] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2021] [Accepted: 01/03/2022] [Indexed: 05/13/2023]
Abstract
Lead-halide perovskite (LHP) nanocrystals have proven themselves as an interesting material platform due to their easy synthesis and compositional versatility, allowing for a tunable band gap, strong absorption, and high photoluminescence quantum yield (PLQY). This tunability and performance make LHP nanocrystals interesting for optoelectronic applications. Patterning active materials like these is a useful way to expand their tunability and applicability as it may allow more intricate designs that can improve efficiencies or increase functionality. Based on a technique for II-VI quantum dots, here we pattern colloidal LHP nanocrystals using electron-beam lithography (EBL). We create patterns of LHP nanocrystals on the order of 100s of nanometers to several microns and use these patterns to form intricate designs. The patterning mechanism is induced by ligand cross-linking, which binds adjacent nanocrystals together. We find that the luminescent properties are somewhat diminished after exposure, but that the structures are nonetheless still emissive. We believe that this is an interesting step toward patterning LHP nanocrystals at the nanoscale for device fabrication.
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Affiliation(s)
- Christian
D. Dieleman
- Center
for Nanophotonics, AMOLF, Science Park 104, 1098 XG Amsterdam, The Netherlands
- Advanced
Research Center for Nanolithography, Science Park 106, 1098 XG Amsterdam, The Netherlands
| | - Julia van der Burgt
- Center
for Nanophotonics, AMOLF, Science Park 104, 1098 XG Amsterdam, The Netherlands
| | - Neha Thakur
- Advanced
Research Center for Nanolithography, Science Park 106, 1098 XG Amsterdam, The Netherlands
| | - Erik C. Garnett
- Center
for Nanophotonics, AMOLF, Science Park 104, 1098 XG Amsterdam, The Netherlands
| | - Bruno Ehrler
- Center
for Nanophotonics, AMOLF, Science Park 104, 1098 XG Amsterdam, The Netherlands
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4
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Shimura K, Lee T, Ito T, Kim D. Selective hydrothermal synthesis of water-soluble CdTe and CdTe/CdS colloidal quantum dots by controlling the Te/Cd molar ratio of the precursor solution. BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 2021. [DOI: 10.1246/bcsj.20210251] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Kunio Shimura
- Department of Applied Physics, Osaka City University, Osaka 558-8585, Japan
| | - TaeGi Lee
- Department of Applied Physics, Osaka City University, Osaka 558-8585, Japan
| | - Tatsuya Ito
- Department of Applied Physics, Osaka City University, Osaka 558-8585, Japan
| | - DaeGwi Kim
- Department of Applied Physics, Osaka City University, Osaka 558-8585, Japan
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5
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Dieleman CD, Ding W, Wu L, Thakur N, Bespalov I, Daiber B, Ekinci Y, Castellanos S, Ehrler B. Universal direct patterning of colloidal quantum dots by (extreme) ultraviolet and electron beam lithography. NANOSCALE 2020; 12:11306-11316. [PMID: 32421115 DOI: 10.1039/d0nr01077d] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Colloidal quantum dots have found many applications and patterning them on micro- and nanoscale would open a new dimension of tunability for the creation of smaller scale (flexible) electronics or nanophotonic structures. Here we present a simple, general, one-step top-down patterning technique for colloidal quantum dots by means of direct optical or electron beam lithography. We find that both photons and electrons can induce a solubility switch of both PbS and CdSe quantum dot films. The solubility switch can be ascribed to cross-linking of the organic ligands, which we observe from exposure with deep-UV photons (5.5 eV) to extreme-UV photons (91.9 eV), and low-energy (3-70 eV) as well as highly energetic electrons (50 keV). The required doses for patterning are relatively low and feature sizes can be as small as tens of nanometers. The luminescence properties as well as carrier lifetimes remain similar after patterning.
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Affiliation(s)
- Christian D Dieleman
- AMOLF, Center for Nanophotonics, Science Park 104, 1098XG Amsterdam, The Netherlands.
| | - Weiyi Ding
- AMOLF, Center for Nanophotonics, Science Park 104, 1098XG Amsterdam, The Netherlands.
| | - Lianjia Wu
- Advanced Research Center for Nanolithography, EUV Photoresists Group, Science Park 106, 1098 XG Amsterdam, The Netherlands.
| | - Neha Thakur
- Advanced Research Center for Nanolithography, EUV Photoresists Group, Science Park 106, 1098 XG Amsterdam, The Netherlands.
| | - Ivan Bespalov
- Advanced Research Center for Nanolithography, EUV Photoresists Group, Science Park 106, 1098 XG Amsterdam, The Netherlands.
| | - Benjamin Daiber
- AMOLF, Center for Nanophotonics, Science Park 104, 1098XG Amsterdam, The Netherlands.
| | - Yasin Ekinci
- Paul Scherrer Institute, Laboratory of Micro and Nanotechnology, Forschungsstrasse 111, 5232 Villigen, Switzerland
| | - Sonia Castellanos
- Advanced Research Center for Nanolithography, EUV Photoresists Group, Science Park 106, 1098 XG Amsterdam, The Netherlands.
| | - Bruno Ehrler
- AMOLF, Center for Nanophotonics, Science Park 104, 1098XG Amsterdam, The Netherlands.
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6
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Enders F, Budweg A, Zeng P, Lauth J, Smith TA, Brida D, Boldt K. Switchable dissociation of excitons bound at strained CdTe/CdS interfaces. NANOSCALE 2018; 10:22362-22373. [PMID: 30474672 DOI: 10.1039/c8nr07973k] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Charge carrier dynamics of semiconductor nano-heterostructures are determined by band alignment and lattice mismatch of the adjacent materials. However, quantum efficiencies for the separation of excited charge carriers at such an interface are hard to predict and cannot yet be easily controlled. In this work we examine nanorods with a severely strained, axial CdTe/CdS interface using femtosecond transient absorption spectroscopy. We show that charge separation is mitigated by equal contributions of valence band distortion and formation of coulomb pairs across the interface. Left undisturbed such localised excitons relax rapidly via non-radiative recombination channels. By adding a competitive hole acceptor that disrupts the coulomb interaction we overcome the synergetic co-localisation of the carriers and realise charge separation. The thus created long-lived state can be exploited for a broad range of applications such as photocatalysis, water splitting, and switchable nanodevices.
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Affiliation(s)
- Florian Enders
- Department of Chemistry, University of Konstanz, 78457 Konstanz, Germany.
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7
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Bodunov EN, Antonov YA, Simões Gamboa AL. On the origin of stretched exponential (Kohlrausch) relaxation kinetics in the room temperature luminescence decay of colloidal quantum dots. J Chem Phys 2017; 146:114102. [DOI: 10.1063/1.4978396] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- E. N. Bodunov
- Department of Physics, Emperor Alexander I St. Petersburg State Transport University, 190031 St. Petersburg, Russia
| | - Yu. A. Antonov
- Department of Physics, Emperor Alexander I St. Petersburg State Transport University, 190031 St. Petersburg, Russia
| | - A. L. Simões Gamboa
- International Research and Education Centre for Physics of Nanostructures, ITMO University, 197101 St. Petersburg, Russia
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8
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Watanabe T, Takahashi K, Shimura K, Bu HB, Hyeon-Deuk K, Kim D. Synthesis of Type-I CdTe Core and Type-II CdTe/CdS Core/Shell Quantum Dots by a Hydrothermal Method and Their Optical Properties. BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 2017. [DOI: 10.1246/bcsj.20160299] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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9
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10
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Boldt K, Ramanan C, Chanaewa A, Werheid M, Eychmüller A. Controlling Charge Carrier Overlap in Type-II ZnSe/ZnS/CdS Core-Barrier-Shell Quantum Dots. J Phys Chem Lett 2015; 6:2590-2597. [PMID: 26266739 DOI: 10.1021/acs.jpclett.5b01144] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We describe the synthesis and spectroscopic characterization of colloidal ZnSe/ZnS/CdS nanocrystals, which exhibit a type-II electronic structure and wave function overlap that is strongly dependent on the thickness of the ZnS barrier. Barrier thickness is controlled by both the amount of deposited material and the reaction and annealing temperature of CdS shell growth. The results show that a single monolayer of ZnS mitigates the overlap significantly, while four and more monolayers effectively suppress band edge absorption and emission. Transient absorption spectra reveal a broad distribution of excitons with mixed S and P symmetry, which become allowed due to alloy formation and contribute to charge carrier relaxation across the barrier. We present a model of the core/shell interface based on cation diffusion, which allows one to estimate the extent of the diffusion layer from optical spectra.
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Affiliation(s)
- Klaus Boldt
- †Physical Chemistry, TU Dresden, Bergstraße 66b, 01062 Dresden, Germany
| | - Charusheela Ramanan
- ‡Department of Physics and Astronomy, VU University, De Boelelaan 1081, NL-1081 HV Amsterdam, The Netherlands
| | - Alina Chanaewa
- ‡Department of Physics and Astronomy, VU University, De Boelelaan 1081, NL-1081 HV Amsterdam, The Netherlands
| | - Matthias Werheid
- †Physical Chemistry, TU Dresden, Bergstraße 66b, 01062 Dresden, Germany
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11
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Chen X, Li L, Lai Y, Yan J, Tang Y, Wang X. Microwave-Assisted Synthesis of Glutathione-Capped CdTe/CdSe Near-Infrared Quantum Dots for Cell Imaging. Int J Mol Sci 2015; 16:11500-8. [PMID: 25997004 PMCID: PMC4463713 DOI: 10.3390/ijms160511500] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2015] [Revised: 05/11/2015] [Accepted: 05/11/2015] [Indexed: 01/02/2023] Open
Abstract
These glutathione (GSH)-conjugated CdTe/CdSe core/shell quantum dot (QD) nanoparticles in aqueous solution were synthesized using a microwave-assisted approach. The prepared type II core/shell QD nanoparticles were characterized by UV-Vis absorption, photoluminescence (PL) spectroscopy, X-ray powder diffraction (XRD) and high-resolution transmission electron microscopy (HR-TEM). Results revealed that the QD nanoparticles exhibited good dispersity, a uniform size distribution and tunable fluorescence emission in the near-infrared (NIR) region. In addition, these nanoparticles exhibited good biocompatibility and photoluminescence in cell imaging. In particular, this type of core/shell NIR QDs may have potential applications in molecular imaging.
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Affiliation(s)
- Xiaogang Chen
- Department of Dermatologic Surgery, Shanghai Skin Disease Hospital, Shanghai 200443, China.
| | - Liang Li
- Department of Dermatologic Surgery, Shanghai Skin Disease Hospital, Shanghai 200443, China.
| | - Yongxian Lai
- Department of Dermatologic Surgery, Shanghai Skin Disease Hospital, Shanghai 200443, China.
| | - Jianna Yan
- Department of Dermatologic Surgery, Shanghai Skin Disease Hospital, Shanghai 200443, China.
| | - Yichen Tang
- Department of Dermatologic Surgery, Shanghai Skin Disease Hospital, Shanghai 200443, China.
| | - Xiuli Wang
- Department of Dermatologic Surgery, Shanghai Skin Disease Hospital, Shanghai 200443, China.
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12
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Yang P, Chen HS, Zhang S, Zhao J, Du Y, Miao Y, He H, Liu Y. Effect of Cd0.5Zn0.5S shells on temperature-dependent luminescence kinetics of CdSe quantum dots. RSC Adv 2014. [DOI: 10.1039/c4ra07399a] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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13
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Kim D, Yokota H, Shimura K, Nakayama M. Temperature dependence of photoluminescence dynamics of self-assembled monolayers of CdSe quantum dots: the influence of the bound-exciton state. Phys Chem Chem Phys 2014; 15:21051-7. [PMID: 24220232 DOI: 10.1039/c3cp54012j] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We have investigated the temperature dependence of photoluminescence (PL) dynamics of self-assembled monolayers (SAMs) of CdSe quantum dots (QDs). The PL decay profiles become slower with an increase in temperature up to 160 K, contrary to an ordinary behavior due to thermal quenching. Such anomalous temperature dependence of the PL-decay profile is explained using a four-state model which introduces a bound-exciton state into a conventional three-state model consisting of a ground state and two excited states: a lower-lying dark-exciton state and a higher-lying bright-exciton state. Furthermore, it is proposed that the radiative decay time of QDs is strongly influenced by the presence or absence of the bound-exciton state.
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Affiliation(s)
- DaeGwi Kim
- Department of Applied Physics, Graduate School of Engineering, Osaka City University, 3-3-138, Sugimoto, Sumiyoshi-ku, Osaka 558-8585, Japan.
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14
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Zhou D, Zhang H. Critical growth temperature of aqueous CdTe quantum dots is non-negligible for their application as nanothermometers. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2013; 9:3195-3197. [PMID: 24038853 DOI: 10.1002/smll.201201060] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Affiliation(s)
- Ding Zhou
- State Key Laboratory of Supramolecular, Structure and Materials, College of Chemistry, Jilin University, Changchun 130012, PR China
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15
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Blumling DE, McGill S, Knappenberger KL. The influence of applied magnetic fields on the optical properties of zero- and one-dimensional CdSe nanocrystals. NANOSCALE 2013; 5:9049-9056. [PMID: 23945622 DOI: 10.1039/c3nr03252c] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Shape-dependent exciton relaxation dynamics of CdSe 0-D nanocrystals and 1-D nanorods were studied using low-temperature (4.2 K), time-resolved and intensity-integrated magneto-photoluminscence (MPL) spectroscopy. Analysis of the average MPL rate constants from several different nanocrystal quantum dots and rods excited by 400 nm light in applied magnetic fields up to 17.5 T revealed size-dependent energy gaps separating bright and dark exciton fine-structure states. For 1-D nanorods under strong cross-sectional confinement and large length-to-diameter aspect ratios, efficient mixing of bright and dark exciton states was achieved using relatively low applied field strengths (≤4 T). The effect was attributed, in part, to decreased confinement of CdSe hole states associated with the long axis of the nanorod, which resulted in reduction of the energy gaps separating the bright and dark states. Increased control over the angle formed between the applied field vectors and the nanocrystal c-axis led to more efficient and uniform mixing of nanorod exciton states than for quantum dots. The findings suggest 1-D nanostructures are advantageous over 0-D ones for field-responsive applications.
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Affiliation(s)
- Daniel E Blumling
- Department of Natural Sciences, Tennessee Wesleyan College, Athens, TN 37303, USA
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16
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17
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Zhou D, Lin M, Liu X, Li J, Chen Z, Yao D, Sun H, Zhang H, Yang B. Conducting the temperature-dependent conformational change of macrocyclic compounds to the lattice dilation of quantum dots for achieving an ultrasensitive nanothermometer. ACS NANO 2013; 7:2273-2283. [PMID: 23402423 DOI: 10.1021/nn305423p] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
We report a ligand decoration strategy to enlarge the lattice dilation of quantum dots (QDs), which greatly enhances the characteristic sensitivity of a QD-based thermometer. Upon a multiple covalent linkage of macrocyclic compounds with QDs, for example, thiolated cyclodextrin (CD) and CdTe, the conformation-related torsional force of CD is conducted to the inner lattice of CdTe under altered temperature. The combination of the lattice expansion/contraction of CdTe and the stress from CD conformation change greatly enhances the shifts of both UV-vis absorption and photoluminescence (PL) spectra, thus improving the temperature sensitivity. As an example, β-CD-decorated CdTe QDs exhibit the 0.28 nm shift of the spectra per degree centigrade (0.28 nm/°C), 2.4-fold higher than those of monothiol-ligand-decorated QDs.
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Affiliation(s)
- Ding Zhou
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun 130012, People's Republic of China
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18
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Kershaw SV, Susha AS, Rogach AL. Narrow bandgap colloidal metal chalcogenide quantum dots: synthetic methods, heterostructures, assemblies, electronic and infrared optical properties. Chem Soc Rev 2013; 42:3033-87. [DOI: 10.1039/c2cs35331h] [Citation(s) in RCA: 325] [Impact Index Per Article: 29.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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19
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Bu HB, Kikunaga H, Shimura K, Takahasi K, Taniguchi T, Kim D. Hydrothermal synthesis of thiol-capped CdTe nanoparticles and their optical properties. Phys Chem Chem Phys 2013; 15:2903-11. [DOI: 10.1039/c2cp43299d] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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20
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Sagarzazu G, Inoue K, Saruyama M, Sakamoto M, Teranishi T, Masuo S, Tamai N. Ultrafast dynamics and single particle spectroscopy of Au–CdSe nanorods. Phys Chem Chem Phys 2013; 15:2141-52. [DOI: 10.1039/c2cp43458j] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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21
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Gui R, An X. Layer-by-layer aqueous synthesis, characterization and fluorescence properties of type-II CdTe/CdS core/shell quantum dots with near-infrared emission. RSC Adv 2013. [DOI: 10.1039/c3ra43120g] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
A layer-by-layer epitaxial method was developed to synthesize water-soluble, near-infrared (NIR)-emitting type-II core–shell CdTe/CdS quantum dots (QDs) via employing glutathione-capped CdTe QDs as core templates, CdCl2 and thiourea as shell precursors.
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Affiliation(s)
- Rijun Gui
- School of Chemistry and Molecules Engineering
- East China University of Science and Technology
- Shanghai 200237
- P. R. China
- School of Chemistry and Chemical Engineering
| | - Xueqin An
- School of Chemistry and Molecules Engineering
- East China University of Science and Technology
- Shanghai 200237
- P. R. China
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22
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Kar A, Kundu S, Patra A. Photocatalytic properties of semiconductor SnO2/CdS heterostructure nanocrystals. RSC Adv 2012. [DOI: 10.1039/c2ra21065g] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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23
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Ghosh Chaudhuri R, Paria S. Core/shell nanoparticles: classes, properties, synthesis mechanisms, characterization, and applications. Chem Rev 2011; 112:2373-433. [PMID: 22204603 DOI: 10.1021/cr100449n] [Citation(s) in RCA: 1549] [Impact Index Per Article: 119.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Rajib Ghosh Chaudhuri
- Department of Chemical Engineering, National Institute of Technology, Rourkela 769 008, Orissa, India
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24
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Boldt K, Jander S, Hoppe K, Weller H. Characterization of the organic ligand shell of semiconductor quantum dots by fluorescence quenching experiments. ACS NANO 2011; 5:8115-8123. [PMID: 21942207 DOI: 10.1021/nn202748v] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
We present the characterization of the organic ligand shell of CdSe/Cd(x)Zn(1-x)S/ZnS nanoparticles by means of fluorescence quenching experiments. Both electron scavengers and acceptors for resonance energy transfer were employed as probes. Different quenching behavior for short and long chain thiol ligands in water was found. It could be shown that poly(ethylene oxide) (PEO)-capping of the particles comprises a densely packed inner shell and a loosely packed outer shell in which ions and small molecules diffuse unhindered. A quantitative uptake of quencher molecules into the PEO shell was observed, through which the particle volume including the ligand sphere could be determined.
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Affiliation(s)
- Klaus Boldt
- Institute for Physical Chemistry, University of Hamburg, Grindelallee 177, 20146 Hamburg, Germany
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Saruyama M, So YG, Kimoto K, Taguchi S, Kanemitsu Y, Teranishi T. Spontaneous formation of wurzite-CdS/zinc blende-CdTe heterodimers through a partial anion exchange reaction. J Am Chem Soc 2011; 133:17598-601. [PMID: 21972931 DOI: 10.1021/ja2078224] [Citation(s) in RCA: 73] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Ion exchange of ionic semiconductor nanoparticles (NPs) is a facile method for the synthesis of type-II semiconductor heterostructured NPs with staggered alignment of band edges for photoelectric applications. Through consideration of the crystallographic orientation and strain at the heterointerface, well-designed heterostructures can be constructed through ion exchange reactions. Here we report the selective synthesis of anisotropically phase-segregated cadmium sulfide (CdS)/ cadmium telluride (CdTe) heterodimers via a novel anion exchange reaction of CdS NPs with an organic telluride precursor. The wurtzite-CdS/zinc blende-CdTe heterodimers in this study resulted from spontaneous phase segregation induced by the differences in the crystal structures of the two phases, accompanying a centrosymmetry breaking of the spherical CdS NPs. The CdS/CdTe heterodimers exhibited photoinduced spatial charge separation because of their staggered band-edge alignment.
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Affiliation(s)
- Masaki Saruyama
- Department of Chemistry, Graduate School of Pure and Applied Sciences, University of Tsukuba, 1-1-1 Tennoidai, Tsukuba, Ibaraki 305-8571, Japan
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26
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Yang P, Ando M, Murase N. Facile synthesis of highly luminescent CdSe/CdxZn1−xS quantum dots with widely tunable emission spectra. Colloids Surf A Physicochem Eng Asp 2011. [DOI: 10.1016/j.colsurfa.2011.09.029] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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27
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Shen H, Yuan H, Niu JZ, Xu S, Zhou C, Ma L, Li LS. Phosphine-free synthesis of high-quality reverse type-I ZnSe/CdSe core with CdS/Cd(x)Zn(1 - x)S/ZnS multishell nanocrystals and their application for detection of human hepatitis B surface antigen. NANOTECHNOLOGY 2011; 22:375602. [PMID: 21852741 DOI: 10.1088/0957-4484/22/37/375602] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Highly photoluminescent (PL) reverse type-I ZnSe/CdSe nanocrystals (NCs) and ZnSe/CdSe/CdS/Cd(x)Zn(1 - x)S/ZnS core/multishell NCs were successfully synthesized by a phosphine-free method. By this low-cost, 'green' synthesis route, more than 10 g of high-quality ZnSe/CdSe/CdS/Cd(x)Zn(1 - x)S/ZnS NCs were synthesized in a large scale synthesis. After the overgrowth of a CdS/Cd(x)Zn(1 - x)S/ZnS multishell on ZnSe/CdSe cores, the PL quantum yields (QYs) increased from 28% to 75% along with the stability improvement. An amphiphilic oligomer was used as a surface coating agent to conduct a phase transfer experiment, core/multishell NCs were dissolved in water by such surface modification and the QYs were still kept above 70%. The as-prepared water dispersible ZnSe/CdSe/CdS/Cd(x)Zn(1 - x)S/ZnS core/multishell NCs not only have high fluorescence QYs but also are extremely stable in various physiological conditions. Furthermore, a biosensor system (lateral flow immunoassay system, LFIA) for the detection of human hepatitis B surface antigen (HBsAg) was developed by using this water-soluble core/multishell NCs as a fluorescent label and a nitrocellulose filter membrane for lateral flow. The result showed that such ZnSe/CdSe/CdS/Cd(x)Zn(1 - x)S/ZnS core/multishell NCs were excellent fluorescent labels to detect HBsAg. The sensitivity of HBsAg detection could reach as high as 0.05 ng ml( - 1).
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Affiliation(s)
- Huaibin Shen
- Key Laboratory for Special Functional Materials, Henan University, Kaifeng 475004, People's Republic of China
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Nano-engineered electron-hole exchange interaction controls exciton dynamics in core-shell semiconductor nanocrystals. Nat Commun 2011; 2:280. [PMID: 21505436 PMCID: PMC3127490 DOI: 10.1038/ncomms1281] [Citation(s) in RCA: 126] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2010] [Accepted: 03/17/2011] [Indexed: 11/16/2022] Open
Abstract
A strong electron–hole exchange interaction (EI) in semiconductor nanocrystals (NCs) gives rise to a large (up to tens of meV) splitting between optically active ('bright') and optically passive ('dark') excitons. This dark–bright splitting has a significant effect on the optical properties of band-edge excitons and leads to a pronounced temperature and magnetic field dependence of radiative decay. Here we demonstrate a nanoengineering-based approach that provides control over EI while maintaining nearly constant emission energy. We show that the dark–bright splitting can be widely tuned by controlling the electron–hole spatial overlap in core–shell CdSe/CdS NCs with a variable shell width. In thick-shell samples, the EI energy reduces to <250 μeV, which yields a material that emits with a nearly constant rate over temperatures from 1.5 to 300 K and magnetic fields up to 7 T. The EI-manipulation strategies demonstrated here are general and can be applied to other nanostructures with variable electron–hole overlap. Electron–hole exchange interaction is an intrinsic property of semiconductors, which affects their fine structure. Brovelli et al. demonstrate a nanoengineering-based approach that provides control over the exchange interaction energy at nearly constant emission energy, which cannot be carried out using core-only nanocrystals.
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Ivanov SA, Achermann M. Spectral and dynamic properties of excitons and biexcitons in type-II semiconductor nanocrystals. ACS NANO 2010; 4:5994-6000. [PMID: 20873722 DOI: 10.1021/nn101357q] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Using time-resolved photoluminescence spectroscopy, we analyze single and multiexciton emission energies and decay dynamics of CdS/ZnSe core/shell nanocrystals (NCs). The NCs exhibit a characteristic type-II band alignment that leads to spatially separated charges; this effect is at the origin of long radiative exciton lifetimes, repulsive biexciton interaction energies, and reduced Auger recombination efficiencies. We determine these properties as a function of ZnSe shell thickness and find that the exciton emission energies and the decay times depend little on this parameter. In contrast, the spectral and dynamic properties of biexcitons vary strongly with the shell thickness. The considerable shell dependence of the biexciton decay lets us conclude that the associated Auger process involves the excitation of holes localized in the ZnSe shell. In NCs with thick shells, the large blue shift of the biexciton emission energy is mainly caused by Coulomb repulsion between electrons localized in the CdS core. The different sensitivity of exciton and multiexciton characteristics on the ZnSe shell thickness provides a unique opportunity to tune them independently.
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Affiliation(s)
- S A Ivanov
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
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Yong KT. Biophotonics and biotechnology in pancreatic cancer: cyclic RGD-peptide-conjugated type II quantum dots for in vivo imaging. Pancreatology 2010; 10:553-64. [PMID: 20975319 DOI: 10.1159/000283577] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/21/2009] [Accepted: 01/29/2010] [Indexed: 12/11/2022]
Abstract
This work introduces a novel, facile and straightforward approach to produce cyclic-RGD-peptide-conjugated type II CdTe/CdS quantum dot (QD) formulation for pancreatic tumor targeting and imaging in live animals. The ultra-small QDs were prepared by a hot colloidal synthesis method. Phospholipid micelles were then used to encapsulate the QDs, allowing them to be stably dispersed in biological fluids and able to conjugate with cyclic-RGD peptides. The QD complex had shown low cytotoxicity on Panc-1 human pancreatic cancer cell lines. In addition, the tissue sections and biodistribution of QD complexes were imaged and analyzed in mice bearing pancreatic tumor xenografts, confirming specific tumor targeting. These studies support further evaluation of type II QDs as potential probes for early pancreatic cancer assessment and detection.
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Affiliation(s)
- Ken-Tye Yong
- Institute for Lasers, Photonics and Biophotonics, University at Buffalo, The State University of New York, Buffalo, NY, USA.
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31
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Liu YF, Yu JS. In situ synthesis of highly luminescent glutathione-capped CdTe/ZnS quantum dots with biocompatibility. J Colloid Interface Sci 2010; 351:1-9. [PMID: 20719328 DOI: 10.1016/j.jcis.2010.07.047] [Citation(s) in RCA: 99] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2010] [Revised: 07/01/2010] [Accepted: 07/17/2010] [Indexed: 11/17/2022]
Abstract
This paper focuses on the in situ synthesis of novel CdTe/ZnS core-shell quantum dots (QDs) in aqueous solution. Glutathione (GSH) was used as both capping reagent and sulfur source for in situ growth of ZnS shell on the CdTe core QDs. The maximum emission wavelengths of the prepared CdTe/ZnS QDs can be simply tuned from 569 nm to 630 nm. The PL quantum yield of CdTe/ZnS QDs synthesized is up to 84%, larger than the original CdTe QDs by around 1.7 times. The PL lifetime results reveal a triexponential decay model of exciton and trap radiation behavior. The average exciton lifetime at room temperature is 17.1 ns for CdTe (2.8 nm) and 27.4 ns for CdTe/ZnS (3.7 nm), respectively. When the solution of QDs is dialyzed for 3 h, 1.17 ppm of Cd(2+) is released from CdTe QDs and 0.35 ppm is released from CdTe/ZnS. At the dose of 120 microg/ml QDs, 9.5% of hemolysis was induced by CdTe QDs and 3.9% was induced by CdTe/ZnS QDs. These results indicate that the synthesized glutathione-capped CdTe/ZnS QDs are of less toxicity and better biocompatibility, so that are attractive for use in biological detection and related fields.
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Affiliation(s)
- Ying-Fan Liu
- Key Lab of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, PR China
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32
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Wang CH, Wei CM, Huang SC, Chen YF, Lai CW, Ho ML, Chou PT. Recombination Dynamics of the Enhanced Quantum Efficiency in CdSe/ZnTe/ZnS Type-II Quantum Dots. J CHIN CHEM SOC-TAIP 2010. [DOI: 10.1002/jccs.201000077] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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33
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Kim S, Park J, Kim S, Jung W, Sung J, Kim SW. The effects of staggered bandgap in the InP/CdSe and CdSe/InP core/shell quantum dots. J Colloid Interface Sci 2010; 346:347-51. [DOI: 10.1016/j.jcis.2010.03.030] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2009] [Revised: 02/22/2010] [Accepted: 03/13/2010] [Indexed: 12/01/2022]
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34
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Hewa-Kasakarage NN, El-Khoury PZ, Tarnovsky AN, Kirsanova M, Nemitz I, Nemchinov A, Zamkov M. Ultrafast carrier dynamics in type II ZnSe/CdS/ZnSe nanobarbells. ACS NANO 2010; 4:1837-44. [PMID: 20337435 DOI: 10.1021/nn100229x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
We employ femtosecond transient absorption spectroscopy to get an insight into ultrafast processes occurring at the interface of type II ZnSe/CdS heterostructured nanocrystals fabricated via colloidal routes and comprising a barbell-like arrangement of ZnSe tips and CdS nanorods. Our study shows that resonant excitation of ZnSe tips results in an unprecedently fast transfer of excited electrons into CdS domains of nanobarbells (<0.35 ps), whereas selective pumping of CdS components leads to a relatively slow injection of photoinduced holes into ZnSe tips (tau(h)= 95 ps). A qualitative thermodynamic description of observed electron processes within the classical limit of Marcus theory was used to identify a specific charge transfer regime associated with the ultrafast electron injection into CdS. Potential photocatalytic applications of the observed fast separation of carriers along the main axis of ZnSe/CdS barbells are discussed.
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35
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Zhang W, Chen G, Wang J, Ye BC, Zhong X. Design and Synthesis of Highly Luminescent Near-Infrared-Emitting Water-Soluble CdTe/CdSe/ZnS Core/Shell/Shell Quantum Dots. Inorg Chem 2009; 48:9723-31. [DOI: 10.1021/ic9010949] [Citation(s) in RCA: 137] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Affiliation(s)
- Wenjin Zhang
- State Key Laboratory of Bioreactor Engineering, Department of Chemistry, and School of Bioengineering, East China University of Science and Technology, Shanghai 200237, China
| | - Guanjiao Chen
- State Key Laboratory of Bioreactor Engineering, Department of Chemistry, and School of Bioengineering, East China University of Science and Technology, Shanghai 200237, China
| | - Jian Wang
- State Key Laboratory of Bioreactor Engineering, Department of Chemistry, and School of Bioengineering, East China University of Science and Technology, Shanghai 200237, China
| | - Bang-Ce Ye
- State Key Laboratory of Bioreactor Engineering, Department of Chemistry, and School of Bioengineering, East China University of Science and Technology, Shanghai 200237, China
| | - Xinhua Zhong
- State Key Laboratory of Bioreactor Engineering, Department of Chemistry, and School of Bioengineering, East China University of Science and Technology, Shanghai 200237, China
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36
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Lo SS, Khan Y, Jones M, Scholes GD. Temperature and solvent dependence of CdSe/CdTe heterostructure nanorod spectra. J Chem Phys 2009; 131:084714. [DOI: 10.1063/1.3212693] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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37
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Growth of near-IR luminescent colloidal CdTe/CdS nanoheterostructures based on CdTe tetrapods. MENDELEEV COMMUNICATIONS 2009. [DOI: 10.1016/j.mencom.2009.05.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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38
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Wang J, Long Y, Zhang Y, Zhong X, Zhu L. Preparation of Highly Luminescent CdTe/CdS Core/Shell Quantum Dots. Chemphyschem 2009; 10:680-5. [DOI: 10.1002/cphc.200800672] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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39
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Al Salman A, Tortschanoff A, van der Zwan G, van Mourik F, Chergui M. A model for the multi-exponential excited-state decay of CdSe nanocrystals. Chem Phys 2009. [DOI: 10.1016/j.chemphys.2008.10.042] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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40
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Hewa-Kasakarage NN, Kirsanova M, Nemchinov A, Schmall N, El-Khoury PZ, Tarnovsky AN, Zamkov M. Radiative Recombination of Spatially Extended Excitons in (ZnSe/CdS)/CdS Heterostructured Nanorods. J Am Chem Soc 2009; 131:1328-34. [DOI: 10.1021/ja8082895] [Citation(s) in RCA: 116] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Nishshanka N. Hewa-Kasakarage
- The Center for Photochemical Sciences, Department of Physics, and Department of Chemistry, Bowling Green State University, Bowling Green, Ohio 43403
| | - Maria Kirsanova
- The Center for Photochemical Sciences, Department of Physics, and Department of Chemistry, Bowling Green State University, Bowling Green, Ohio 43403
| | - Alexander Nemchinov
- The Center for Photochemical Sciences, Department of Physics, and Department of Chemistry, Bowling Green State University, Bowling Green, Ohio 43403
| | - Nickolas Schmall
- The Center for Photochemical Sciences, Department of Physics, and Department of Chemistry, Bowling Green State University, Bowling Green, Ohio 43403
| | - Patrick Z. El-Khoury
- The Center for Photochemical Sciences, Department of Physics, and Department of Chemistry, Bowling Green State University, Bowling Green, Ohio 43403
| | - Alexander N. Tarnovsky
- The Center for Photochemical Sciences, Department of Physics, and Department of Chemistry, Bowling Green State University, Bowling Green, Ohio 43403
| | - Mikhail Zamkov
- The Center for Photochemical Sciences, Department of Physics, and Department of Chemistry, Bowling Green State University, Bowling Green, Ohio 43403
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41
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Green M, Williamson P, Samalova M, Davis J, Brovelli S, Dobson P, Cacialli F. Synthesis of type II/type I CdTe/CdS/ZnS quantum dots and their use in cellular imaging. ACTA ACUST UNITED AC 2009. [DOI: 10.1039/b913292a] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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42
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Chin PTK, de Mello Donegá C, van Bavel SS, Meskers SCJ, Sommerdijk NAJM, Janssen RAJ. Highly Luminescent CdTe/CdSe Colloidal Heteronanocrystals with Temperature-Dependent Emission Color. J Am Chem Soc 2007; 129:14880-6. [DOI: 10.1021/ja0738071] [Citation(s) in RCA: 153] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Patrick T. K. Chin
- Contribution from the Molecular Materials and Nanosystems, Materials and Interface Chemistry, and Soft Matter Cryo TEM Research Unit, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands, and Condensed Matter and Interfaces, Debye Institute, Utrecht University, P.O. Box 80000, 3508 TA Utrecht, The Netherlands
| | - Celso de Mello Donegá
- Contribution from the Molecular Materials and Nanosystems, Materials and Interface Chemistry, and Soft Matter Cryo TEM Research Unit, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands, and Condensed Matter and Interfaces, Debye Institute, Utrecht University, P.O. Box 80000, 3508 TA Utrecht, The Netherlands
| | - Svetlana S. van Bavel
- Contribution from the Molecular Materials and Nanosystems, Materials and Interface Chemistry, and Soft Matter Cryo TEM Research Unit, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands, and Condensed Matter and Interfaces, Debye Institute, Utrecht University, P.O. Box 80000, 3508 TA Utrecht, The Netherlands
| | - Stefan C. J. Meskers
- Contribution from the Molecular Materials and Nanosystems, Materials and Interface Chemistry, and Soft Matter Cryo TEM Research Unit, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands, and Condensed Matter and Interfaces, Debye Institute, Utrecht University, P.O. Box 80000, 3508 TA Utrecht, The Netherlands
| | - Nico A. J. M. Sommerdijk
- Contribution from the Molecular Materials and Nanosystems, Materials and Interface Chemistry, and Soft Matter Cryo TEM Research Unit, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands, and Condensed Matter and Interfaces, Debye Institute, Utrecht University, P.O. Box 80000, 3508 TA Utrecht, The Netherlands
| | - René A. J. Janssen
- Contribution from the Molecular Materials and Nanosystems, Materials and Interface Chemistry, and Soft Matter Cryo TEM Research Unit, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands, and Condensed Matter and Interfaces, Debye Institute, Utrecht University, P.O. Box 80000, 3508 TA Utrecht, The Netherlands
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Ivanov SA, Piryatinski A, Nanda J, Tretiak S, Zavadil KR, Wallace WO, Werder D, Klimov VI. Type-II core/shell CdS/ZnSe nanocrystals: synthesis, electronic structures, and spectroscopic properties. J Am Chem Soc 2007; 129:11708-19. [PMID: 17727285 DOI: 10.1021/ja068351m] [Citation(s) in RCA: 176] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We report a two-step synthesis of highly luminescent CdS/ZnSe core/shell nanocrystals (emission quantum yields up to 50%) that can produce efficient spatial separation of electrons and holes between the core and the shell (type-II localization regime). Our synthesis involves fabrication of cubic-singony CdS core particles that are subsequently overcoated with a layer of ZnSe in the presence of surfactant-ligands in a noncoordinating solvent. Studies of different growth regime of the ZnSe shell indicate that one approach to obtaining high emission efficiencies is through alloying the CdS/ZnSe interface with CdSe, which leads to the formation of an intermediate ZnCdSe layer with a graded composition. We perform theoretical modeling of these core/shell nanocrystals using effective mass approximation and applying first-order perturbation theory for treating both direct electron-hole coupling and the core/shell interface-polarization effects. Using this model we determine the range of geometrical parameters of the core/shell structures that result in a type-II localization regime. We further applied this model to evaluate the degree of electron-hole spatial separation (quantified in terms of the electron-hole overlap integral) based on measured emission wavelengths. We also discuss the potential applicability of these nanocrystals in lasing technologies and specifically the possibility of single-exciton optical gain in type-II nanostructures.
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Affiliation(s)
- Sergei A Ivanov
- C-PCS, Chemistry Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.
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