1
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Chang WJ, Zeng H, Terry Weatherly CK, Provazza J, Liu P, Weiss EA, Stern NP, Tempelaar R. Dark State Concentration Dependent Emission and Dynamics of CdSe Nanoplatelet Exciton-Polaritons. ACS NANO 2024. [PMID: 39042269 DOI: 10.1021/acsnano.4c03545] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/24/2024]
Abstract
The recent surge of interest in polaritons has prompted fundamental questions about the role of dark states in strong light-matter coupling phenomena. Here, we systematically vary the relative number of dark states by controlling the number of stacked CdSe nanoplatelets confined in a Fabry-Pérot cavity. We find the emission spectrum to change significantly with an increasing number of nanoplatelets, with a gradual shift of the dominant emission intensity from the lower polariton branch to a manifold of dark states. Through accompanying calculations based on a kinetic model, this shift is rationalized by an entropic trapping of excitations by the dark state manifold, while a weak dark state dispersion due to local disorder explains their nonzero emission. Our results point toward the relevance of the dark state concentration to the optical and dynamical properties of cavity-embedded quantum emitters with ramifications for Bose-Einstein condensate formation, polariton lasing, polariton-based quantum transduction schemes, and polariton chemistry.
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Affiliation(s)
- Woo Je Chang
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208-3113, United States
| | - Hongfei Zeng
- Department of Physics and Astronomy, Northwestern University, Evanston, Illinois 60208-3113, United States
| | | | - Justin Provazza
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208-3113, United States
| | - Pufan Liu
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208-3113, United States
| | - Emily A Weiss
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208-3113, United States
| | - Nathaniel P Stern
- Department of Physics and Astronomy, Northwestern University, Evanston, Illinois 60208-3113, United States
| | - Roel Tempelaar
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208-3113, United States
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2
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Deswal P, Samanta K, Ghosh D. The impact of spatially heterogeneous chemical doping on the electronic properties of CdSe quantum dots: insights from ab initio computation. NANOSCALE 2023; 15:17055-17067. [PMID: 37846794 DOI: 10.1039/d3nr04342h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/18/2023]
Abstract
The introduction of copper (Cu) impurity in semiconductor CdSe quantum dots (QDs) gives rise to unique photoluminescence (PL) bands exhibiting distinctive characteristics, like broad line width, significant Stokes shift, and complex temporal decay. The atomistic origins of these spectral features are yet to be understood comprehensively. We employed multiple computational techniques to systematically study the impact of the spatial heterogeneity of Cu atoms on the stability and photophysical properties, including the emission linewidth of doped QDs under ambient conditions. The Cu substitution introduces a spin-polarized intragap state, the energetic position of which is strongly dependent on the dopant location and causes spectral broadening in QD ensembles. Furthermore, the dopant dynamics under ambient conditions are significantly influenced by the specific arrangement of Cu within the QDs. The dynamic electronic structures of surface-doped CdSe illustrate more pronounced perturbations and vary the mid-gap state position more drastically than those of the core-doped QDs. Vibronic coupling broadens the photoluminescence peaks associated with the conduction band-to-defect level transition for individual QDs. These insights into the dynamic structure-photophysical property relationship suggest viable approaches, such as tuning the operational temperature and selective co-doping, to enhance the functional performances of doped CdSe QDs strategically.
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Affiliation(s)
- Priyanka Deswal
- Department of Physics, Indian Institute of Technology, Delhi, Hauz Khas, New Delhi 110016, India
| | - Kushal Samanta
- Department of Materials Science and Engineering, Indian Institute of Technology, Delhi, Hauz Khas, New Delhi 110016, India.
| | - Dibyajyoti Ghosh
- Department of Materials Science and Engineering, Indian Institute of Technology, Delhi, Hauz Khas, New Delhi 110016, India.
- Department of Chemistry, Indian Institute of Technology, Delhi, Hauz Khas, New Delhi 110016, India
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3
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Bhati M, Ivanov SA, Senftle TP, Tretiak S, Ghosh D. How structural and vibrational features affect optoelectronic properties of non-stoichiometric quantum dots: computational insights. NANOSCALE 2023; 15:7176-7185. [PMID: 37013402 DOI: 10.1039/d2nr06785d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/19/2023]
Abstract
While stoichiometric quantum dots (QDs) have been well studied, a significant knowledge gap remains in the atomistic understanding of the non-stoichiometric ones, which are predominantly present during the experimental synthesis. Here, we investigate the effect of thermal fluctuations on structural and vibrational properties of non-stoichiometric cadmium selenide (CdSe) nanoclusters: anion-rich (Se-rich) and cation-rich (Cd-rich) using ab initio molecular dynamics (AIMD) simulations. While the excess atoms on the surface fluctuate more for a given QD type, the optical phonon modes are mostly composed of Se atoms dynamics, irrespective of the composition. Moreover, Se-rich QDs have higher bandgap fluctuations compared to Cd-rich QDs, suggesting poor optical properties of Se-rich QDs. Additionally, non-adiabatic molecular dynamics (NAMD) suggests faster non-radiative recombination for Cd-rich QDs. Altogether, this work provides insights into the dynamic electronic properties of non-stoichiometric QDs and proposes a rationale for the observed optical stability and superiority of cation-rich candidates for light emission applications.
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Affiliation(s)
- Manav Bhati
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, NM, 87545, USA.
- Center for Nonlinear Studies, Los Alamos National Laboratory, Los Alamos, NM, 87545, USA
- Department of Chemical and Biomolecular Engineering, Rice University, 6100 Main Street, Houston, TX 77005-1892, USA
| | - Sergei A Ivanov
- Materials Physics and Applications Division, Los Alamos National Laboratory, Los Alamos, New Mexico, 87545, USA
- Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, NM, 87545, USA
| | - Thomas P Senftle
- Department of Chemical and Biomolecular Engineering, Rice University, 6100 Main Street, Houston, TX 77005-1892, USA
| | - Sergei Tretiak
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, NM, 87545, USA.
- Center for Nonlinear Studies, Los Alamos National Laboratory, Los Alamos, NM, 87545, USA
- Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, NM, 87545, USA
| | - Dibyajyoti Ghosh
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, NM, 87545, USA.
- Center for Nonlinear Studies, Los Alamos National Laboratory, Los Alamos, NM, 87545, USA
- Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, NM, 87545, USA
- Department of Materials Science and Engineering and Department of Chemistry, Indian Institute of Technology, Delhi, Hauz Khas, New Delhi 110016, India
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4
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Prakash O, Umapathy S. Raman spectroscopy study of CdS nanorods and strain induced by the adsorption of 4-mercaptobenzoic acid. J Chem Phys 2023; 158:134719. [PMID: 37031145 DOI: 10.1063/5.0142702] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/08/2023] Open
Abstract
In this study, near- and off-resonance Raman spectra of cadmium sulfide (CdS) quantum rods (NRs) and 4-mercaptobenzoic acid (4-MBA) adsorbed CdS NRs are reported. The envelopes of characteristic optical phonon modes in the near-resonance Raman spectrum of CdS NRs are deconvoluted by following the phonon confinement model. As compared with off-resonant Raman spectra, optical phonon modes scattering cross section is amplified significantly in near-resonance Raman spectra through the Fröhlich interaction. The Huang–Rhys factor defining the strength of the Fröhlich interaction is estimated (∼0.468). Moreover, the adsorption of different concentrations of 4-mercaptobenzoic acid (4-MBA) onto CdS NRs produces surface strain in CdS NRs originating due to surface reconstruction and consequently blue and red shifts in off-resonance (514.5 nm) Raman spectra depending on the concentration of 4-MBA. These consequences are attributed to compressive and tensile strains, respectively. Relative to bulk CdS powder as the reference, strain in CdS NRs increases with decreasing 4-MBA concentrations. In off-resonance Raman spectra of 4-MBA adsorbed CdS NRs, the full width at half maxima of phonon modes (1-LO and 2-LO) and intensity ratio I2-LO/I1-LO increase with decreasing 4-MBA concentration.
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Affiliation(s)
- Om Prakash
- Department of Inorganic and Physical Chemistry, Indian Institute of Science, Bengaluru 560012, India
- Institute of Physical Chemistry Polish Academy of Science, Warsaw, Poland
| | - Siva Umapathy
- Department of Inorganic and Physical Chemistry, Indian Institute of Science, Bengaluru 560012, India
- Department of Instrumentation and Applied Physics, Indian Institute of Science, Bengaluru 560012, India
- Indian Institute of Science Education and Research, Bhopal 462066, India
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5
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Dzhagan V, Litvinchuk AP, Valakh MY, Zahn DRT. Phonon Raman spectroscopy of nanocrystalline multinary chalcogenides as a probe of complex lattice structures. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2022; 35:103001. [PMID: 36575889 DOI: 10.1088/1361-648x/acaa18] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/17/2022] [Accepted: 12/08/2022] [Indexed: 06/17/2023]
Abstract
Ternary (I-III-VI) and quaternary (I-II-IV-VI) metal-chalcogenides like CuInS2or Cu2ZnSn(S,Se)4are among the materials currently most intensively investigated for various applications in the area of alternative energy conversion and light-emitting devices. They promise more sustainable and affordable solutions to numerous applications, compared to more developed and well understood II-VI and III-V semiconductors. Potentially superior properties are based on an unprecedented tolerance of these compounds to non-stoichiometric compositions and polymorphism. However, if not properly controlled, these merits lead to undesirable coexistence of different compounds in a single polycrystalline lattice and huge concentrations of point defects, becoming an immense hurdle on the way toward real-life applications. Raman spectroscopy of phonons has become one of the most powerful tools of structural diagnostics and probing physical properties of bulk and microcrystalline I-III-VI and I-II-IV-VI compounds. The recent explosive growth of the number of reports on fabrication and characterization of nanostructures of these compounds must be pointed out as well as the steady use of Raman spectroscopy for their characterization. Interpretation of the vibrational spectra of these compound nanocrystals (NCs) and conclusions about their structure can be complicated compared to bulk counterparts because of size and surface effects as well as emergence of new structural polymorphs that are not realizable in the bulk. This review attempts to summarize the present knowledge in the field of I-III-VI and I-II-IV-VI NCs regarding their phonon spectra and capabilities of Raman and IR spectroscopies in the structural characterizations of these promising families of compounds.
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Affiliation(s)
- Volodymyr Dzhagan
- V. Lashkaryov Institute of Semiconductors Physics, National Academy of Sciences of Ukraine, 03038 Kyiv, Ukraine
- Physics Department, Taras Shevchenko National University of Kyiv, 60 Volodymyrs'ka str., 01601 Kyiv, Ukraine
| | - Alexander P Litvinchuk
- Texas Center for Superconductivity and Department of Physics, University of Houston, Houston, TX 77204-5002, United States of America
| | - Mykhailo Ya Valakh
- V. Lashkaryov Institute of Semiconductors Physics, National Academy of Sciences of Ukraine, 03038 Kyiv, Ukraine
| | - Dietrich R T Zahn
- Semiconductor Physics, Chemnitz University of Technology, D-09107 Chemnitz, Germany
- Center for Materials, Architectures, and Integration of Nanomembranes (MAIN), Chemnitz University of Technology, D-09107 Chemnitz, Germany
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6
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Iaru CM, Brodu A, van Hoof NJJ, Ter Huurne SET, Buhot J, Montanarella F, Buhbut S, Christianen PCM, Vanmaekelbergh D, de Mello Donega C, Rivas JG, Koenraad PM, Silov AY. Fröhlich interaction dominated by a single phonon mode in CsPbBr 3. Nat Commun 2021; 12:5844. [PMID: 34615880 PMCID: PMC8494801 DOI: 10.1038/s41467-021-26192-0] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2021] [Accepted: 09/17/2021] [Indexed: 12/02/2022] Open
Abstract
The excellent optoelectronic performance of lead halide perovskites has generated great interest in their fundamental properties. The polar nature of the perovskite lattice means that electron-lattice coupling is governed by the Fröhlich interaction. Still, considerable ambiguity exists regarding the phonon modes that participate in this crucial mechanism. Here, we use multiphonon Raman scattering and THz time-domain spectroscopy to investigate Fröhlich coupling in CsPbBr3. We identify a longitudinal optical phonon mode that dominates the interaction, and surmise that this mode effectively defines exciton-phonon scattering in CsPbBr3, and possibly similar materials. It is additionally revealed that the observed strength of the Fröhlich interaction is significantly higher than the expected intrinsic value for CsPbBr3, and is likely enhanced by carrier localization in the colloidal perovskite nanocrystals. Our experiments also unearthed a dipole-related dielectric relaxation mechanism which may impact transport properties. Electron-phonon interaction is essential for understanding electronic and optical properties of lead halide perovskites. Here, using multiphonon Raman scattering and THz time-domain spectroscopy, the authors characterize the full phonon spectrum of CsPbBr3 and identify a single phonon mode that dominates electron-phonon scattering.
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Affiliation(s)
- Claudiu M Iaru
- Department of Applied Physics and Institute for Photonic Integration, Eindhoven University of Technology, P.O. Box 513, 5600 MB, Eindhoven, The Netherlands.
| | - Annalisa Brodu
- Condensed Matter and Interfaces, Debye Institute for Nanomaterials Science, Utrecht University, Princetonplein 1, 3508 TA, Utrecht, The Netherlands
| | - Niels J J van Hoof
- Department of Applied Physics and Institute for Photonic Integration, Eindhoven University of Technology, P.O. Box 513, 5600 MB, Eindhoven, The Netherlands
| | - Stan E T Ter Huurne
- Department of Applied Physics and Institute for Photonic Integration, Eindhoven University of Technology, P.O. Box 513, 5600 MB, Eindhoven, The Netherlands
| | - Jonathan Buhot
- HH Wills Laboratory, University of Bristol, Bristol, BS8 1TL, UK.,High Field Magnet Laboratory (HFML - EMFL), Radboud University, 6525 ED, Nijmegen, The Netherlands
| | - Federico Montanarella
- Condensed Matter and Interfaces, Debye Institute for Nanomaterials Science, Utrecht University, Princetonplein 1, 3508 TA, Utrecht, The Netherlands
| | - Sophia Buhbut
- Condensed Matter and Interfaces, Debye Institute for Nanomaterials Science, Utrecht University, Princetonplein 1, 3508 TA, Utrecht, The Netherlands
| | - Peter C M Christianen
- High Field Magnet Laboratory (HFML - EMFL), Radboud University, 6525 ED, Nijmegen, The Netherlands
| | - Daniël Vanmaekelbergh
- Condensed Matter and Interfaces, Debye Institute for Nanomaterials Science, Utrecht University, Princetonplein 1, 3508 TA, Utrecht, The Netherlands
| | - Celso de Mello Donega
- Condensed Matter and Interfaces, Debye Institute for Nanomaterials Science, Utrecht University, Princetonplein 1, 3508 TA, Utrecht, The Netherlands
| | - Jaime Gòmez Rivas
- Department of Applied Physics and Institute for Photonic Integration, Eindhoven University of Technology, P.O. Box 513, 5600 MB, Eindhoven, The Netherlands
| | - Paul M Koenraad
- Department of Applied Physics and Institute for Photonic Integration, Eindhoven University of Technology, P.O. Box 513, 5600 MB, Eindhoven, The Netherlands
| | - Andrei Yu Silov
- Department of Applied Physics and Institute for Photonic Integration, Eindhoven University of Technology, P.O. Box 513, 5600 MB, Eindhoven, The Netherlands.
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7
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Martinet Q, Baronnier J, Girard A, Albaret T, Saviot L, Mermet A, Abecassis B, Margueritat J, Mahler B. Ligand-dependent nano-mechanical properties of CdSe nanoplatelets: calibrating nanobalances for ligand affinity monitoring. NANOSCALE 2021; 13:8639-8647. [PMID: 33942037 DOI: 10.1039/d1nr00270h] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
The influence of ligands on the low frequency vibration of cadmium selenide colloidal nanoplatelets of different thicknesses is investigated using resonant low frequency Raman scattering. The strong vibration frequency shifts induced by ligand modifications as well as sharp spectral linewidths make low frequency Raman scattering a tool of choice to follow ligand exchange as well as the nano-mechanical properties of the NPLs, as evidenced by a carboxylate to thiolate exchange study. Apart from their molecular weight, the nature of the ligands, such as the sulfur to metal bond of thiols, induces a modification of the NPLs as a whole, increasing the thickness by one monolayer. Moreover, as the weight of the ligands increases, the discrepancy between the mass-load model and the experimental measurements increase. These effects are all the more important when the number of layers is small and can only be explained by a modification of the longitudinal sound velocity. This modification takes its origin in a change of the lattice structure of the NPLs, that reflects on their elastic properties. These nanobalances are finally used to characterize ligand affinity with the surface using binary thiol mixtures, illustrating the potential of low frequency Raman scattering to finely characterize nanocrystal surfaces.
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Affiliation(s)
- Quentin Martinet
- Institut Lumière Matière Université de Lyon, Université Claude Bernard Lyon 1, UMR CNRS 5306, F-69622 Villeurbanne, France.
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8
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Xiao J, Liu Y, Steinmetz V, Çaǧlar M, Mc Hugh J, Baikie T, Gauriot N, Nguyen M, Ruggeri E, Andaji-Garmaroudi Z, Stranks SD, Legrand L, Barisien T, Friend RH, Greenham NC, Rao A, Pandya R. Optical and Electronic Properties of Colloidal CdSe Quantum Rings. ACS NANO 2020; 14:14740-14760. [PMID: 33044058 DOI: 10.1021/acsnano.0c01752] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Luminescent colloidal CdSe nanorings are a recently developed type of semiconductor structure that have attracted interest due to the potential for rich physics arising from their nontrivial toroidal shape. However, the exciton properties and dynamics of these materials with complex topology are not yet well understood. Here, we use a combination of femtosecond vibrational spectroscopy, temperature-resolved photoluminescence (PL), and single-particle measurements to study these materials. We find that on transformation of CdSe nanoplatelets to nanorings, by perforating the center of platelets, the emission lifetime decreases and the emission spectrum broadens due to ensemble variations in the ring size and thickness. The reduced PL quantum yield of nanorings (∼10%) compared to platelets (∼30%) is attributed to an enhanced coupling between (i) excitons and CdSe LO-phonons at 200 cm-1 and (ii) negatively charged selenium-rich traps, which give nanorings a high surface charge (∼-50 mV). Population of these weakly emissive trap sites dominates the emission properties with an increased trap emission at low temperatures relative to excitonic emission. Our results provide a detailed picture of the nature of excitons in nanorings and the influence of phonons and surface charge in explaining the broad shape of the PL spectrum and the origin of PL quantum yield losses. Furthermore, they suggest that the excitonic properties of nanorings are not solely a consequence of the toroidal shape but also a result of traps introduced by puncturing the platelet center.
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Affiliation(s)
- James Xiao
- Cavendish Laboratory, University of Cambridge, J.J. Thomson Avenue, CB3 0HE, Cambridge, United Kingdom
| | - Yun Liu
- Cavendish Laboratory, University of Cambridge, J.J. Thomson Avenue, CB3 0HE, Cambridge, United Kingdom
| | - Violette Steinmetz
- Cavendish Laboratory, University of Cambridge, J.J. Thomson Avenue, CB3 0HE, Cambridge, United Kingdom
| | - Mustafa Çaǧlar
- Cavendish Laboratory, University of Cambridge, J.J. Thomson Avenue, CB3 0HE, Cambridge, United Kingdom
| | - Jeffrey Mc Hugh
- Cavendish Laboratory, University of Cambridge, J.J. Thomson Avenue, CB3 0HE, Cambridge, United Kingdom
| | - Tomi Baikie
- Cavendish Laboratory, University of Cambridge, J.J. Thomson Avenue, CB3 0HE, Cambridge, United Kingdom
| | - Nicolas Gauriot
- Cavendish Laboratory, University of Cambridge, J.J. Thomson Avenue, CB3 0HE, Cambridge, United Kingdom
| | - Malgorzata Nguyen
- Cavendish Laboratory, University of Cambridge, J.J. Thomson Avenue, CB3 0HE, Cambridge, United Kingdom
| | - Edoardo Ruggeri
- Cavendish Laboratory, University of Cambridge, J.J. Thomson Avenue, CB3 0HE, Cambridge, United Kingdom
| | - Zahra Andaji-Garmaroudi
- Cavendish Laboratory, University of Cambridge, J.J. Thomson Avenue, CB3 0HE, Cambridge, United Kingdom
- Department of Chemical Engineering & Biotechnology, University of Cambridge, Philippa Fawcett Drive, CB3 0AS, Cambridge, United Kingdom
| | - Samuel D Stranks
- Sorbonne Université, CNRS-UMR 7588, Institut des NanoSciences de Paris, INSP, 4 Place Jussieu, F-75005 Paris, France
| | - Laurent Legrand
- Sorbonne Université, CNRS-UMR 7588, Institut des NanoSciences de Paris, INSP, 4 Place Jussieu, F-75005 Paris, France
| | - Thierry Barisien
- Cavendish Laboratory, University of Cambridge, J.J. Thomson Avenue, CB3 0HE, Cambridge, United Kingdom
| | - Richard H Friend
- Cavendish Laboratory, University of Cambridge, J.J. Thomson Avenue, CB3 0HE, Cambridge, United Kingdom
| | - Neil C Greenham
- Cavendish Laboratory, University of Cambridge, J.J. Thomson Avenue, CB3 0HE, Cambridge, United Kingdom
| | - Akshay Rao
- Cavendish Laboratory, University of Cambridge, J.J. Thomson Avenue, CB3 0HE, Cambridge, United Kingdom
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9
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Chang WJ, Park KY, Zhu Y, Wolverton C, Hersam MC, Weiss EA. n-Doping of Quantum Dots by Lithium Ion Intercalation. ACS APPLIED MATERIALS & INTERFACES 2020; 12:36523-36529. [PMID: 32666788 DOI: 10.1021/acsami.0c09366] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The optical properties of colloidal quantum dots (QDs) are controllable through introduction of excess electrons or holes into their delocalized bands. Crucial to robust and energy-efficient electronic doping of QDs is suitable charge compensation. Compensation by surface modification and substitutional impurities are however not sufficiently controllable to enable effective doping of QDs. This article describes electrochemical n-type doping of CdSe QDs where injected electrons are compensated by interstitial Li+ to form LixCdSe, x ≤ 0.3. n-type degenerate doping reversibly decreases absorption into the lowest-energy excitonic state of the QD, activates intraband optical transitions, and shifts the photoluminescence of the QD to higher energy. This work establishes electrochemical interstitial doping as a reversible and highly controllable method for tuning the optical properties of colloidal QDs.
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Affiliation(s)
- Woo Je Chang
- Department of Materials Science and Engineering, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3113, United States
| | - Kyu-Young Park
- Department of Materials Science and Engineering, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3113, United States
| | - Yizhou Zhu
- Department of Materials Science and Engineering, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3113, United States
| | - Christopher Wolverton
- Department of Materials Science and Engineering, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3113, United States
| | - Mark C Hersam
- Department of Materials Science and Engineering, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3113, United States
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3113, United States
- Department of Electrical and Computer Engineering, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3113, United States
| | - Emily A Weiss
- Department of Materials Science and Engineering, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3113, United States
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3113, United States
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10
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Lignos I, Utzat H, Bawendi MG, Jensen KF. Nanocrystal synthesis, μfluidic sample dilution and direct extraction of single emission linewidths in continuous flow. LAB ON A CHIP 2020; 20:1975-1980. [PMID: 32352465 DOI: 10.1039/d0lc00213e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The rational design of semiconductor nanocrystal populations requires control of their emission linewidths, which are dictated by interparticle inhomogeneities and single-nanocrystal spectral linewidths. To date, research efforts have concentrated on minimizing the ensemble emission linewidths, however there is little knowledge about the synthetic parameters dictating single-nanocrystal linewidths. In this direction, we present a flow-based system coupled with an optical interferometry setup for the extraction of single nanocrystal properties. The platform has the ability to synthesize nanocrystals at high temperature <300 °C, adjust the particle concentration after synthesis and extract ensemble-averaged single nanocrystal emission linewidths using flow photon-correlation Fourier spectroscopy.
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Affiliation(s)
- Ioannis Lignos
- Department of Chemical Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA.
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11
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Boldt K, Bartlett S, Kirkwood N, Johannessen B. Quantification of Material Gradients in Core/Shell Nanocrystals Using EXAFS Spectroscopy. NANO LETTERS 2020; 20:1009-1017. [PMID: 31960678 DOI: 10.1021/acs.nanolett.9b04143] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Core/shell nanocrystals with a graded interface between core and shell exhibit improved optoelectronic properties compared with particles with an abrupt, sharp interface. Material gradients mitigate interfacial defects and define the shape of the confinement potential. So far, few works exist that allow to quantify the width of the gradient. In this study, ZnSe/CdS nanocrystals with graded shells made at different temperatures are characterized using extended X-ray absorption fine structure (EXAFS) and Raman spectroscopies. The average coordination number of the probed element with respect to the two possible counterions is fit to a simple, geometric model. It is shown that at the lower temperature limit for shell growth (260 °C), substantial interfacial alloying can be attributed mainly to cation migration. At higher temperature (290 °C), strain minimization leads to atomic ordering of the metal ions and an anomalously low degree of phase mixing.
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Affiliation(s)
- Klaus Boldt
- Department of Chemistry & Zukunftskolleg, Box 710 , University of Konstanz , 78457 Konstanz , Germany
| | - Stuart Bartlett
- Diamond Light Source , Diamond House, Harwell Science and Innovation Campus , Didcot , Oxfordshire OX11 0DE , United Kingdom
| | - Nicholas Kirkwood
- ARC Centre in Exciton Science, School of Chemistry , The University of Melbourne , Parkville , Victoria 3010 , Australia
| | - Bernt Johannessen
- ANSTO Australian Synchrotron , 800 Blackburn Rd , Clayton , Victoria 3168 , Australia
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12
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Richard C, McGee R, Goenka A, Mukherjee P, Bhargava R. On-demand Milifluidic Synthesis of Quantum Dots in Digital Droplet Reactors. Ind Eng Chem Res 2019; 59:3730-3735. [PMID: 33911342 DOI: 10.1021/acs.iecr.9b04230] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Colloidal quantum dots (QDs) offer dramatic potential due to their size-dependent optical properties. Lack of facile synthesis methods for precise and reproducible size and composition, however, present an extant barrier to their widespread use. Here we report the use of droplet microfluidics for the simple and highly reproducible synthesis of cadmium sulfide (CdS) and cadmium selenide (CdSe) QDs without the use of harsh solvents and in ambient conditions. Our approach uses a liquid-liquid barrier between two immiscible liquids to generate a digital droplet reactor. This reaction droplet is easily controlled and manipulated and offers enhanced mixing when coupled to a helical mixer, resulting in a significant reduction in size distribution compared to benchtop procedures. Furthermore, QD characteristics have modeled and predicted based on the parameters of the microfluidic device. We believe this method overcomes the current manufacturing challenges with synthesizing nanostructures, which is required for the next generation of nanosensors.
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Affiliation(s)
- Craig Richard
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana Champaign, Urbana, IL 61801, USA.,Department of Bioengineering, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
| | - Rachel McGee
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana Champaign, Urbana, IL 61801, USA
| | - Aditya Goenka
- Department of Chemical Engineering, Indian Institute Technology, Kharagpur, India
| | - Prabuddha Mukherjee
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana Champaign, Urbana, IL 61801, USA
| | - Rohit Bhargava
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana Champaign, Urbana, IL 61801, USA.,Department of Bioengineering, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA.,Departments of Bioengineering, Chemical and Biomolecular Engineering, Electrical and Computer Engineering, Mechanical Science and Engineering and Chemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.,Cancer Center at Illinois
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13
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Kelley AM. Exciton-optical phonon coupling in II-VI semiconductor nanocrystals. J Chem Phys 2019; 151:140901. [DOI: 10.1063/1.5125147] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Affiliation(s)
- Anne Myers Kelley
- Chemistry and Chemical Biology, University of California, Merced 5300 North Lake Rd., Merced, California 95343, USA
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14
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Garoz‐Ruiz J, Perales‐Rondon JV, Heras A, Colina A. Spectroelectrochemistry of Quantum Dots. Isr J Chem 2019. [DOI: 10.1002/ijch.201900028] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Jesus Garoz‐Ruiz
- Department of ChemistryUniversidad de Burgos Pza. Misael Bañuelos s/n E-09001 Burgos Spain
| | - Juan V. Perales‐Rondon
- Department of ChemistryUniversidad de Burgos Pza. Misael Bañuelos s/n E-09001 Burgos Spain
| | - Aranzazu Heras
- Department of ChemistryUniversidad de Burgos Pza. Misael Bañuelos s/n E-09001 Burgos Spain
| | - Alvaro Colina
- Department of ChemistryUniversidad de Burgos Pza. Misael Bañuelos s/n E-09001 Burgos Spain
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15
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Gao Y, Yin P. Effect of Bond Dispersion on Raman Spectra Shift in II-VI Semiconductor Nanocrystals. Inorg Chem 2019; 58:4859-4868. [PMID: 30931557 DOI: 10.1021/acs.inorgchem.8b03359] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
To understand Raman spectra shifts of nanocrystals, the top-down phonon confinement approach and the bottom-up quantum chemical approach were developed. The former is suitable for large-sized nanocrystals, and the latter is suitable for clusters containing fewer atoms. Here, we find that a simpler chemical bond model based on the bond dispersion feature can demonstrate Raman spectra shift either in normal size II-VI semiconductor nanocrystals or in atomically precise clusters. According to the bond dispersion model, the Raman spectral line of the II-VI semiconductor nanocrystal (AIIBVI) is expressed as the sum of the Lorentz subpeaks of the AII( i)BVI( j) bonds with different coordinates i and j. The calculated Raman lines of CdSe, CdS, CdTe, ZnS, and ZnSe nanocrystals are in agreement with the measured Raman spectral lines. The origin of the red shift and asymmetric broadening of the peak position of nanocrystals may be revealed as well. Results provide insight into how different bonds contribute to different vibrational spectra.
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Affiliation(s)
- Yukun Gao
- Key Laboratory of Bio-inspired Smart Interfacial Science and Technology of Ministry of Education, School of Chemistry , Beihang University , Beijing 100191 , China
| | - Penggang Yin
- Key Laboratory of Bio-inspired Smart Interfacial Science and Technology of Ministry of Education, School of Chemistry , Beihang University , Beijing 100191 , China
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16
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Harvey SM, Phelan BT, Hannah DC, Brown KE, Young RM, Kirschner MS, Wasielewski MR, Schaller RD. Auger Heating and Thermal Dissipation in Zero-Dimensional CdSe Nanocrystals Examined Using Femtosecond Stimulated Raman Spectroscopy. J Phys Chem Lett 2018; 9:4481-4487. [PMID: 30011208 DOI: 10.1021/acs.jpclett.8b01504] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
We report femtosecond stimulated Raman spectroscopy (FSRS) measurements on dispersions of CdSe semiconductor nanocrystals (NCs) as a function of particle size and pump fluence. Upon photoexcitation, we observe depletion of stimulated Raman gain corresponding to generation of longitudinal optical (LO) phonons followed by recovery on picosecond timescales. At higher fluences, production of multiple excitons slows recovery of FSRS signals, which we attribute to sustained increases of LO phonon populations due to multiexcitonic Auger heating. Owing to the discretized electronic structure of these NCs, such heating cannot be readily monitored via electronic spectroscopic analysis of high-energy band tails as has been performed for higher-dimensional materials. Notably, recovery timescales exceed those of the biexcitonic Auger recombination process and as such reveal overall thermalization timescales likely owing to an acoustic phonon thermalization bottleneck that dictates the cooling timescale.
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Affiliation(s)
- Samantha M Harvey
- Department of Chemistry , Northwestern University , Evanston , Illinois 60208 , United States
- Institute for Sustainability and Energy at Northwestern , Northwestern University , Evanston , Illinois 60208 , United States
| | - Brian T Phelan
- Department of Chemistry , Northwestern University , Evanston , Illinois 60208 , United States
- Institute for Sustainability and Energy at Northwestern , Northwestern University , Evanston , Illinois 60208 , United States
| | - Daniel C Hannah
- Department of Chemistry , Northwestern University , Evanston , Illinois 60208 , United States
- Institute for Sustainability and Energy at Northwestern , Northwestern University , Evanston , Illinois 60208 , United States
| | - Kristen E Brown
- Department of Chemistry , Northwestern University , Evanston , Illinois 60208 , United States
- Institute for Sustainability and Energy at Northwestern , Northwestern University , Evanston , Illinois 60208 , United States
| | - Ryan M Young
- Department of Chemistry , Northwestern University , Evanston , Illinois 60208 , United States
- Institute for Sustainability and Energy at Northwestern , Northwestern University , Evanston , Illinois 60208 , United States
| | - Matthew S Kirschner
- Department of Chemistry , Northwestern University , Evanston , Illinois 60208 , United States
| | - Michael R Wasielewski
- Department of Chemistry , Northwestern University , Evanston , Illinois 60208 , United States
- Institute for Sustainability and Energy at Northwestern , Northwestern University , Evanston , Illinois 60208 , United States
| | - Richard D Schaller
- Department of Chemistry , Northwestern University , Evanston , Illinois 60208 , United States
- Institute for Sustainability and Energy at Northwestern , Northwestern University , Evanston , Illinois 60208 , United States
- Center for Nanoscale Materials , Argonne National Laboratory , Argonne , Illinois 60439 , United States
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17
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Spencer AP, Hutson WO, Irgen-Gioro S, Harel E. Exciton-Phonon Spectroscopy of Quantum Dots Below the Single-Particle Homogeneous Line Width. J Phys Chem Lett 2018; 9:1503-1508. [PMID: 29510628 DOI: 10.1021/acs.jpclett.8b00065] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
We demonstrate that high-dimensionality coherent spectroscopy yields "super-resolved" spectra whereby peaks may be localized far below their homogeneous line width by resolving them across multiple, coherently coupled dimensions. We implement this technique using a fifth-order photon-echo spectroscopy called Gradient-Assisted Multidimensional Electronic-Raman Spectroscopy (GAMERS) that combines resonant and nonresonant excitation to disperse the optical response across three spectral dimensions: two involving excitonic transitions and one that encodes phonon energies. In analogy to super-resolution localization microscopies, which separate spatially overlapping signals in time, GAMERS isolates signals spectrally using combined electronic and nuclear resolution. Optical phonon lines in a colloidal solution of CdSe quantum dots at room temperature separated by less than 150 μeV are resolved despite the homogeneous line width of these transitions being nearly an order of magnitude broader. The frequency difference between these phonon modes is attributed to softening of the longitudinal phonon mode upon excitation to the lowest exciton state. Further, such phonon mode selectivity yields spectra with electronic line widths that approach the single particle limit. Through this enhanced spectral resolution, the GAMERS method yields insights into the nature of coupling between longitudinal optical and acoustic phonons and specific excitonic transitions that were previously hidden.
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Affiliation(s)
- Austin P Spencer
- Department of Chemistry , Northwestern University , 2145 Sheridan Road , Evanston , Illinois 60208 , United States
| | - William O Hutson
- Department of Chemistry , Northwestern University , 2145 Sheridan Road , Evanston , Illinois 60208 , United States
| | - Shawn Irgen-Gioro
- Department of Chemistry , Northwestern University , 2145 Sheridan Road , Evanston , Illinois 60208 , United States
| | - Elad Harel
- Department of Chemistry , Northwestern University , 2145 Sheridan Road , Evanston , Illinois 60208 , United States
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18
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19
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Utzat H, Shulenberger KE, Achorn OB, Nasilowski M, Sinclair TS, Bawendi MG. Probing Linewidths and Biexciton Quantum Yields of Single Cesium Lead Halide Nanocrystals in Solution. NANO LETTERS 2017; 17:6838-6846. [PMID: 29039964 DOI: 10.1021/acs.nanolett.7b03120] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Cesium lead halide (CsPbX3, X = Cl, Br, I) perovskite nanocrystals (PNCs) have recently become a promising material for optoelectronic applications due to their high emission quantum yields and facile band gap tunability via both halide composition and size. The spectroscopy of single PNCs enhances our understanding of the effect of confinement on excitations in PNCs in the absence of obfuscating ensemble averaging and can also inform synthetic efforts. However, single PNC studies have been hampered by poor PNC photostability under confocal excitation, precluding interrogation of all but the most stable PNCs, and leading to a lack of understanding of PNCs in the regime of high confinement. Here, we report the first comprehensive spectroscopic investigation of single PNC properties using solution-phase photon-correlation methods, including both highly confined and blue-emitting PNCs, previously inaccessible to single NC techniques. With minimally perturbative solution-phase photon-correlation Fourier spectroscopy (s-PCFS), we establish that the ensemble emission linewidth of PNCs of all sizes and compositions is predominantly determined by the intrinsic single PNC linewidth (homogeneous broadening). The single PNC linewidth, in turn, dramatically increases with increasing confinement, consistent with what has been found for II-VI semiconductor nanocrystals. With solution-phase photon antibunching measurements, we survey the biexciton-to-exciton quantum yield ratio (BX/X QY) in the absence of user-selection bias or photodegradation. Remarkably, the BX/X QY ratio depends both on the PNC size and halide composition, with values between ∼2% for highly confined bromide PNCs and ∼50% for intermediately confined iodide PNCs. Our results suggest a wide range of underlying Auger rates, likely due to transitory charge carrier separation in PNCs with relaxed confinement.
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Affiliation(s)
- Hendrik Utzat
- Department of Chemistry, Massachusetts Institute of Technology , 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
| | - Katherine E Shulenberger
- Department of Chemistry, Massachusetts Institute of Technology , 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
| | - Odin B Achorn
- Department of Chemistry, Massachusetts Institute of Technology , 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
| | - Michel Nasilowski
- Department of Chemistry, Massachusetts Institute of Technology , 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
| | - Timothy S Sinclair
- Department of Chemistry, Massachusetts Institute of Technology , 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
| | - Moungi G Bawendi
- Department of Chemistry, Massachusetts Institute of Technology , 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
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20
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Nadtochenko V, Denisov N, Aybush A, Gostev F, Shelaev I, Titov A, Umanskiy S, Cherepanov AD. Ultrafast Spectroscopy of Fano-Like Resonance between Optical Phonon and Excitons in CdSe Quantum Dots: Dependence of Coherent Vibrational Wave-Packet Dynamics on Pump Fluence. NANOMATERIALS 2017; 7:nano7110371. [PMID: 29113056 PMCID: PMC5707588 DOI: 10.3390/nano7110371] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/08/2017] [Revised: 10/25/2017] [Accepted: 10/27/2017] [Indexed: 11/16/2022]
Abstract
The main goal of the present work is to study the coherent phonon in strongly confined CdSe quantum dots (QDs) under varied pump fluences. The main characteristics of coherent phonons (amplitude, frequency, phase, spectrogram) of CdSe QDs under the red-edge pump of the excitonic band [1S(e)-1S3/2(h)] are reported. We demonstrate for the first time that the amplitude of the coherent optical longitudinal-optical (LO) phonon at 6.16 THz excited in CdSe nanoparticles by a femtosecond unchirped pulse shows a non-monotone dependence on the pump fluence. This dependence exhibits the maximum at pump fluence ~0.8 mJ/cm2. At the same time, the amplitudes of the longitudinal acoustic (LA) phonon mode at 0.55 THz and of the coherent wave packet of toluene at 15.6, 23.6 THz show a monotonic rise with the increase of pump fluence. The time frequency representation of an oscillating signal corresponding to LO phonons revealed by continuous wavelet transform (CWT) shows a profound destructive quantum interference close to the origin of distinct (optical phonon) and continuum-like (exciton) quasiparticles. The CWT spectrogram demonstrates a nonlinear chirp at short time delays, where the chirp sign depends on the pump pulse fluence. The CWT spectrogram reveals an anharmonic coupling between optical and acoustic phonons.
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Affiliation(s)
- Victor Nadtochenko
- N.N. Semenov Institute of Chemical Physics, Russian Academy of Sciences, Kosygina st., 4, 119991 Moscow, Russia.
- Institute of Problem of Chemical Physics, Russian Academy of Sciences, 142432 Chernogolovka, Russia.
- Chemical Faculty, Moscow State University, Leninskie Gory, 119992 Moscow, Russia.
| | - Nikolay Denisov
- Institute of Problem of Chemical Physics, Russian Academy of Sciences, 142432 Chernogolovka, Russia.
| | - Arseniy Aybush
- N.N. Semenov Institute of Chemical Physics, Russian Academy of Sciences, Kosygina st., 4, 119991 Moscow, Russia.
| | - Fedor Gostev
- N.N. Semenov Institute of Chemical Physics, Russian Academy of Sciences, Kosygina st., 4, 119991 Moscow, Russia.
| | - Ivan Shelaev
- N.N. Semenov Institute of Chemical Physics, Russian Academy of Sciences, Kosygina st., 4, 119991 Moscow, Russia.
| | - Andrey Titov
- N.N. Semenov Institute of Chemical Physics, Russian Academy of Sciences, Kosygina st., 4, 119991 Moscow, Russia.
| | - Stanislav Umanskiy
- N.N. Semenov Institute of Chemical Physics, Russian Academy of Sciences, Kosygina st., 4, 119991 Moscow, Russia.
| | - And Dmitry Cherepanov
- N.N. Semenov Institute of Chemical Physics, Russian Academy of Sciences, Kosygina st., 4, 119991 Moscow, Russia.
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21
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Grenland JJ, Maddux CJA, Kelley DF, Kelley AM. Charge Trapping versus Exciton Delocalization in CdSe Quantum Dots. J Phys Chem Lett 2017; 8:5113-5118. [PMID: 28972776 DOI: 10.1021/acs.jpclett.7b02242] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The spectroscopic and photophysical similarities and differences between charge trapping by surface ligands on CdSe quantum dots and charge delocalization into the shell in excited CdSe core/shell nanocrystals are discussed. Optical absorption and resonance Raman spectroscopies are used to study small CdSe quantum dots coated with organic ligands that accept electrons (methyl viologen) or holes (phenothiazine, 4-methylbenzenethiol), as well as with semiconductor shells that delocalize electrons (CdS) or holes (CdTe). The organic ligands have only a small effect on the optical absorption spectrum and contribute negligibly to the resonance Raman spectra, indicating little participation of ligand orbitals in the initial excitation. The semiconductor shells more strongly red-shift the absorption spectrum by delocalizing the electron and/or hole into the shell, and vibrations of the shell appear in the resonance Raman spectrum, showing that the shell is involved in the vertical excitation. The qualitative differences between ligand and semiconductor shells are discussed in terms of the energetics and coupling strengths.
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Affiliation(s)
- Jamie J Grenland
- Chemistry and Chemical Biology, University of California, Merced , 5200 North Lake Road, Merced, California 95343, United States
| | - Cassandra J A Maddux
- Chemistry and Chemical Biology, University of California, Merced , 5200 North Lake Road, Merced, California 95343, United States
| | - David F Kelley
- Chemistry and Chemical Biology, University of California, Merced , 5200 North Lake Road, Merced, California 95343, United States
| | - Anne Myers Kelley
- Chemistry and Chemical Biology, University of California, Merced , 5200 North Lake Road, Merced, California 95343, United States
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22
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Faust A, Amit Y, Banin U. Phonon-Plasmon Coupling and Active Cu Dopants in Indium Arsenide Nanocrystals Studied by Resonance Raman Spectroscopy. J Phys Chem Lett 2017; 8:2519-2525. [PMID: 28524661 DOI: 10.1021/acs.jpclett.7b00661] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Doping of semiconductor nanocrystals is an emerging tool to control their properties and has recently received increased interest as the means to characterize the impurities and their effect on the electronic characteristics of the nanocrystal evolve. We present a temperature-dependent Raman scattering study of Cu-doped InAs nanocrystals observing changes in the relative scattering intensities of the different modes upon increased dopant concentrations. First, the longitudinal optical (LO) phonon overtone mode is suppressed, indicating weakening of the coupling strength related to the effect of screening by the free electrons. Second, the transverse optical (TO) mode is relatively enhanced compared to the LO mode, which is attributed to the appearance of a coupled phonon-plasmon mode analogous to observations for n-type doped bulk InAs. These signatures indicate that the Cu impurities serve as active dopants and occupy an impurity-related pseudo sub-band akin to the heavy doping limit.
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Affiliation(s)
- Adam Faust
- The Institute of Chemistry and the Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem , Jerusalem 91904, Israel
| | - Yorai Amit
- The Institute of Chemistry and the Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem , Jerusalem 91904, Israel
| | - Uri Banin
- The Institute of Chemistry and the Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem , Jerusalem 91904, Israel
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23
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Levchenko TI, Kübel C, Khalili Najafabadi B, Boyle PD, Cadogan C, Goncharova LV, Garreau A, Lagugné-Labarthet F, Huang Y, Corrigan JF. Luminescent CdSe Superstructures: A Nanocluster Superlattice and a Nanoporous Crystal. J Am Chem Soc 2017; 139:1129-1144. [DOI: 10.1021/jacs.6b10490] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Tetyana I. Levchenko
- Department
of Chemistry, The University of Western Ontario, London, Ontario N6A 5B7, Canada
| | - Christian Kübel
- Institute
of Nanotechnology and Karlsruhe NanoMicro Facility, Karlsruhe Institute of Technology, 76344 Eggenstein-Leopoldshafen, Germany
| | | | - Paul D. Boyle
- Department
of Chemistry, The University of Western Ontario, London, Ontario N6A 5B7, Canada
| | - Carolyn Cadogan
- Department
of Physics and Astronomy, The University of Western Ontario, London, Ontario N6A 3K7, Canada
| | - Lyudmila V. Goncharova
- Department
of Physics and Astronomy, The University of Western Ontario, London, Ontario N6A 3K7, Canada
- The
Centre for Advanced Materials and Biomaterials Research (CAMBR), The University of Western Ontario, London, Ontario N6A 5B7, Canada
| | - Alexandre Garreau
- Department
of Chemistry, The University of Western Ontario, London, Ontario N6A 5B7, Canada
| | - François Lagugné-Labarthet
- Department
of Chemistry, The University of Western Ontario, London, Ontario N6A 5B7, Canada
- The
Centre for Advanced Materials and Biomaterials Research (CAMBR), The University of Western Ontario, London, Ontario N6A 5B7, Canada
| | - Yining Huang
- Department
of Chemistry, The University of Western Ontario, London, Ontario N6A 5B7, Canada
- The
Centre for Advanced Materials and Biomaterials Research (CAMBR), The University of Western Ontario, London, Ontario N6A 5B7, Canada
| | - John F. Corrigan
- Department
of Chemistry, The University of Western Ontario, London, Ontario N6A 5B7, Canada
- The
Centre for Advanced Materials and Biomaterials Research (CAMBR), The University of Western Ontario, London, Ontario N6A 5B7, Canada
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24
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Beecher AN, Dziatko RA, Steigerwald ML, Owen JS, Crowther AC. Transition from Molecular Vibrations to Phonons in Atomically Precise Cadmium Selenide Quantum Dots. J Am Chem Soc 2016; 138:16754-16763. [DOI: 10.1021/jacs.6b10705] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Affiliation(s)
- Alexander N. Beecher
- Department
of Chemistry, Columbia University, New York, New York 10027, United States
| | - Rachel A. Dziatko
- Department
of Chemistry, Barnard College, New York, New York 10027, United States
| | | | - Jonathan S. Owen
- Department
of Chemistry, Columbia University, New York, New York 10027, United States
| | - Andrew C. Crowther
- Department
of Chemistry, Barnard College, New York, New York 10027, United States
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25
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Kelley AM. Comparison of three empirical force fields for phonon calculations in CdSe quantum dots. J Chem Phys 2016; 144:214702. [DOI: 10.1063/1.4952990] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Affiliation(s)
- Anne Myers Kelley
- Chemistry and Chemical Biology, University of California, Merced, 5200 North Lake Road, Merced, California 95343, USA
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26
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Liu J, Kilina SV, Tretiak S, Prezhdo OV. Ligands Slow Down Pure-Dephasing in Semiconductor Quantum Dots. ACS NANO 2015; 9:9106-9116. [PMID: 26284384 DOI: 10.1021/acsnano.5b03255] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
It is well-known experimentally and theoretically that surface ligands provide additional pathways for energy relaxation in colloidal semiconductor quantum dots (QDs). They increase the rate of inelastic charge-phonon scattering and provide trap sites for the charges. We show that, surprisingly, ligands have the opposite effect on elastic electron-phonon scattering. Our simulations demonstrate that elastic scattering slows down in CdSe QDs passivated with ligands compared to that in bare QDs. As a result, the pure-dephasing time is increased, and the homogeneous luminescence line width is decreased in the presence of ligands. The lifetime of quantum superpositions of single and multiple excitons increases as well, providing favorable conditions for multiple excitons generation (MEG). Ligands reduce the pure-dephasing rates by decreasing phonon-induced fluctuations of the electronic energy levels. Surface atoms are most mobile in QDs, and therefore, they contribute greatly to the electronic energy fluctuations. The mobility is reduced by interaction with ligands. A simple analytical model suggests that the differences between the bare and passivated QDs persist for up to 5 nm diameters. Both low-frequency acoustic and high-frequency optical phonons participate in the dephasing processes in bare QDs, while low-frequency acoustic modes dominate in passivated QDs. The theoretical predictions regarding the pure-dephasing time, luminescence line width, and MEG can be verified experimentally by studying QDs with different surface passivation.
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Affiliation(s)
- Jin Liu
- Department of Chemical Engineering, University of Rochester , Rochester, New York 14627, United States
| | - Svetlana V Kilina
- Department of Chemistry, North Dakota State University , Fargo, North Dakota 58108, United States
| | - Sergei Tretiak
- Los Alamos National Laboratory , Los Alamos, New Mexico 87545, United States
| | - Oleg V Prezhdo
- Department of Chemistry, University of Southern California , Los Angeles, California 90089, United States
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27
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Fernée MJ, Sinito C, Tamarat P, Lounis B. State selective pumping reveals spin-relaxation pathways in CdSe quantum dots. NANO LETTERS 2014; 14:4480-4485. [PMID: 25040881 DOI: 10.1021/nl501448p] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The band-edge exciton in elongated CdSe nanocrystals is composed of an upper and lower manifold associated with heavy and light holes in which the energy separation is sensitive to the nanocrystal shape. Using resonant photoluminescence excitation, we probe the upper heavy hole exciton manifold and find rapid relaxation to the lower light hole manifold on a 5 ps time scale. State selective excitation allows the preparation of single quantum states in this system. We used this to map the hole spin relaxation pathways between the fine structure sublevels, which have energy splittings incommensurate with either optical or acoustic phonon energies. This reveals a hitherto unexpected hole spin-relaxation channel in these materials.
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Affiliation(s)
- Mark J Fernée
- Université de Bordeaux , LP2N, F-33405 Talence, France
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28
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Fernée MJ, Sinito C, Mulvaney P, Tamarat P, Lounis B. The optical phonon spectrum of CdSe colloidal quantum dots. Phys Chem Chem Phys 2014; 16:16957-61. [DOI: 10.1039/c4cp02022g] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
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