1
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Borel A, Rapisarda F, Doorn SK, Voisin C, Chassagneux Y. Luminescence Properties of Closely Packed Organic Color Centers Grafted on a Carbon Nanotube. NANO LETTERS 2024; 24:3456-3461. [PMID: 38457689 DOI: 10.1021/acs.nanolett.4c00127] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/10/2024]
Abstract
We report on the photoluminescence of pairs of organic color centers in single-wall carbon nanotubes grafted with 3,5-dichlorobenzene. Using various techniques such as intensity correlations, superlocalization microscopy, and luminescence excitation spectroscopy, we distinguish two pairs of color centers grafted on the same nanotube; the distance between the pairs is on the order of several hundreds of nanometers. In contrast, by studying the strong temporal correlations in the spectral diffusion in the framework of the photoinduced Stark effect, we can estimate the distance within each pair to be on the order of a few nanometers. Finally, the electronic population dynamics is investigated using time-resolved luminescence and saturation measurements, showing a biexponential decay with a fast overall recombination (compatible with a fast population transfer between the color centers within a pair) and a weak delayed repopulation of the traps, possibly due to the diffusion of excitons along the tube axis.
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Affiliation(s)
- Antoine Borel
- Laboratoire de physique de l'ENS, Université PSL, CNRS, Sorbonne Université, Université Paris Cité, 75005 Paris, France
| | - Federico Rapisarda
- Laboratoire de physique de l'ENS, Université PSL, CNRS, Sorbonne Université, Université Paris Cité, 75005 Paris, France
| | - Stephen K Doorn
- Center for Integrated Nanotechnologies, Materials Physics and Applications Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
| | - Christophe Voisin
- Laboratoire de physique de l'ENS, Université PSL, CNRS, Sorbonne Université, Université Paris Cité, 75005 Paris, France
| | - Yannick Chassagneux
- Laboratoire de physique de l'ENS, Université PSL, CNRS, Sorbonne Université, Université Paris Cité, 75005 Paris, France
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2
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Trerayapiwat KJ, Li X, Ma X, Sharifzadeh S. Broken Symmetry Optical Transitions in (6,5) Single-Walled Carbon Nanotubes Containing sp3 Defects Revealed by First-Principles Theory. NANO LETTERS 2024; 24:667-671. [PMID: 38174941 DOI: 10.1021/acs.nanolett.3c03957] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2024]
Abstract
We present a first-principles many-body perturbation theory study of nitrophenyl-doped (6,5) single-walled nanotubes (SWCNTs) to understand how sp3 doping impacts the excitonic properties. sp3-doped SWCNTs are promising as a class of optoelectronic materials with bright tunable photoluminescence, long spin coherence, and single-photon emission (SPE), motivating the study of spin excitations. We predict that the dopant results in a single unpaired spin localized around the defect site, which induces multiple low-energy excitonic peaks. By comparing optical absorption and photoluminescence from experiment and theory, we identify the transitions responsible for the red-shifted, defect-induced E11* peak, which has demonstrated SPE for some dopants; the presence of this state is due to both the symmetry-breaking associated with the defect and the presence of the defect-induced in-gap state. Furthermore, we find an asymmetry between the contribution of the two spin channels, suggesting that this system has potential for spin-selective optical transitions.
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Affiliation(s)
| | - Xinxin Li
- Center for Nanoscale Materials, Argonne National Laboratory, Lemont, Illinois 60439, United States
- Consortium for Advanced Science and Engineering, University of Chicago, Chicago, Illinois 60637, United States
| | - Xuedan Ma
- Center for Nanoscale Materials, Argonne National Laboratory, Lemont, Illinois 60439, United States
- Consortium for Advanced Science and Engineering, University of Chicago, Chicago, Illinois 60637, United States
- Northwestern Argonne Institute of Science and Engineering, Evanston, Illinois 60208, United States
| | - Sahar Sharifzadeh
- Department of Electrical and Computer Engineering, Boston University, Boston, Massachusetts 02215, United States
- Division of Materials Science and Engineering, Boston University, Boston, Massachusetts 02215, United States
- Department of Physics, Boston University, Boston, Massachusetts 02215, United States
- Department of Chemistry, Boston University, Boston, Massachusetts 02215, United States
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3
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Sudakov I, Goovaerts E, Wenseleers W, Blackburn JL, Duque JG, Cambré S. Chirality Dependence of Triplet Excitons in (6,5) and (7,5) Single-Wall Carbon Nanotubes Revealed by Optically Detected Magnetic Resonance. ACS NANO 2023; 17:2190-2204. [PMID: 36669768 PMCID: PMC9933588 DOI: 10.1021/acsnano.2c08392] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/22/2022] [Accepted: 01/11/2023] [Indexed: 06/17/2023]
Abstract
The excitonic structure of single-wall carbon nanotubes (SWCNTs) is chirality dependent and consists of multiple singlet and triplet excitons (TEs) of which only one singlet exciton (SE) is optically bright. In particular, the dark TEs have a large impact on the integration of SWCNTs in optoelectronic devices, where excitons are created electrically, such as in infrared light-emitting diodes, thereby strongly limiting their quantum efficiency. Here, we report the characterization of TEs in chirality-purified samples of (6,5) and (7,5) SWCNTs, either randomly oriented in a frozen solution or with in-plane preferential orientation in a film, by means of optically detected magnetic resonance (ODMR) spectroscopy. In both chiral structures, the nanotubes are shown to sustain three types of TEs. One TE exhibits axial symmetry with zero-field splitting (ZFS) parameters depending on SWCNT diameter, in good agreement with the tighter confinement expected in narrower-diameter nanotubes. The ZFS of this TE also depends on nanotube environment, pointing to slightly weaker confinement for surfactant-coated than for polymer-wrapped SWCNTs. A second TE type, with much smaller ZFS, does not show the same systematic trends with diameter and environment and has a less well-defined axial symmetry. This most likely corresponds to TEs trapped at defect sites at low temperature, as exemplified by comparing SWCNT samples from different origins and after different treatments. A third triplet has unresolved ZFS, implying it originates from weakly interacting spin pairs. Aside from the diameter dependence, ODMR thus provides insights in both the symmetry, confinement, and nature of TEs on semiconducting SWCNTs.
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Affiliation(s)
- Ivan Sudakov
- Department
of Physics, University of Antwerp, Universiteitsplein 1, 2610Antwerp, Belgium
- Department
of Chemistry, University of Antwerp, Universiteitsplein 1, 2610Antwerp, Belgium
| | - Etienne Goovaerts
- Department
of Physics, University of Antwerp, Universiteitsplein 1, 2610Antwerp, Belgium
| | - Wim Wenseleers
- Department
of Physics, University of Antwerp, Universiteitsplein 1, 2610Antwerp, Belgium
| | - Jeffrey L. Blackburn
- Materials
Science Center, National Renewable Energy
Laboratory, Golden, Colorado80401, United States
| | - Juan G. Duque
- Chemistry
Division, Physical Chemistry and Applied Spectroscopy Group (C-PCS), Los Alamos National Laboratory, Los Alamos, New Mexico87544, United States
| | - Sofie Cambré
- Department
of Physics, University of Antwerp, Universiteitsplein 1, 2610Antwerp, Belgium
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4
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Khan SN, Weight BM, Gifford BJ, Tretiak S, Bishop A. Impact of Graphene Quantum Dot Edge Morphologies on Their Optical Properties. J Phys Chem Lett 2022; 13:5801-5807. [PMID: 35726899 DOI: 10.1021/acs.jpclett.2c01036] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
The optoelectronic properties of functionalized graphene quantum dots (GQDs) have been explored by simulating electronic structure of three different shapes of GQDs containing exclusively zigzag or armchair edges in both pristine and functionalized forms. Absorption spectra and transition densities for the low-lying excited states are evaluated by using time-dependent density functional theory and compared for different functionalization species. The functionalization position dictates the optical properties of square GQDs, where isomers with CH2 in the intermediate positions (excluding corner and center positions) have higher electronic transition energies and exciton delocalization than other isomers. Rhombic GQDs with all armchair edges exhibit high steric flexibility, and their complete passivation results in the largest structural deformation from planarity and strongest red-shifts. A steady red-shift in the absorption energy is observed following the order F, CH3, Cl, and Br substitutions. This suggests that the steric effects due to large van der Waals radii overcome electronegative effects.
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Affiliation(s)
- Shahriar N Khan
- Department of Chemistry and Biochemistry, Auburn University, Auburn, Alabama 36849-5312, United States
- Theoretical Division, Center for Integrated Nanotechnologies (CINT), Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
| | - Braden M Weight
- Theoretical Division, Center for Integrated Nanotechnologies (CINT), Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
- Department of Physics, University of Rochester, Rochester, New York 14627, United States
| | - Brendan J Gifford
- Theoretical Division, Center for Integrated Nanotechnologies (CINT), Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
| | - Sergei Tretiak
- Theoretical Division, Center for Integrated Nanotechnologies (CINT), Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
| | - Alan Bishop
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
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5
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Kozawa D, Wu X, Ishii A, Fortner J, Otsuka K, Xiang R, Inoue T, Maruyama S, Wang Y, Kato YK. Formation of organic color centers in air-suspended carbon nanotubes using vapor-phase reaction. Nat Commun 2022; 13:2814. [PMID: 35595760 PMCID: PMC9123200 DOI: 10.1038/s41467-022-30508-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Accepted: 04/28/2022] [Indexed: 11/28/2022] Open
Abstract
Organic color centers in single-walled carbon nanotubes have demonstrated exceptional ability to generate single photons at room temperature in the telecom range. Combining the color centers with pristine air-suspended nanotubes would be desirable for improved performance, but all current synthetic methods occur in solution which makes them incompatible. Here we demonstrate the formation of color centers in air-suspended nanotubes using a vapor-phase reaction. Functionalization is directly verified by photoluminescence spectroscopy, with unambiguous statistics from more than a few thousand individual nanotubes. The color centers show strong diameter-dependent emission, which can be explained with a model for chemical reactivity considering strain along the tube curvature. We also estimate the defect density by comparing the experiments with simulations based on a one-dimensional exciton diffusion equation. Our results highlight the influence of the nanotube structure on vapor-phase reactivity and emission properties, providing guidelines for the development of high-performance near-infrared quantum light sources. Organic color centers in single-walled carbon nanotubes can act as single-photon sources in the telecom range. Here the authors report the functionalization of air-suspended nanotubes through a vapor-phase photochemical reaction, demonstrating a further tailoring of quantum emitter materials.
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Affiliation(s)
- Daichi Kozawa
- Quantum Optoelectronics Research Team, RIKEN Center for Advanced Photonics, Saitama, 351-0198, Japan.
| | - Xiaojian Wu
- Department of Chemistry and Biochemistry, University of Maryland, College Park, MD, 20742, USA
| | - Akihiro Ishii
- Quantum Optoelectronics Research Team, RIKEN Center for Advanced Photonics, Saitama, 351-0198, Japan.,Nanoscale Quantum Photonics Laboratory, RIKEN Cluster for Pioneering Research, Saitama, 351-0198, Japan
| | - Jacob Fortner
- Department of Chemistry and Biochemistry, University of Maryland, College Park, MD, 20742, USA
| | - Keigo Otsuka
- Nanoscale Quantum Photonics Laboratory, RIKEN Cluster for Pioneering Research, Saitama, 351-0198, Japan
| | - Rong Xiang
- State Key Laboratory of Fluid Power and Mechatronic Systems, School of Mechanical Engineering, Zhejiang University, Hangzhou, 310027, China.,Department of Mechanical Engineering, The University of Tokyo, Tokyo, 113-8656, Japan
| | - Taiki Inoue
- Department of Mechanical Engineering, The University of Tokyo, Tokyo, 113-8656, Japan.,Department of Applied Physics, Osaka University, Osaka, 565-0871, Japan
| | - Shigeo Maruyama
- Department of Mechanical Engineering, The University of Tokyo, Tokyo, 113-8656, Japan
| | - YuHuang Wang
- Department of Chemistry and Biochemistry, University of Maryland, College Park, MD, 20742, USA.,Maryland NanoCenter, University of Maryland, College Park, MD, 20742, USA
| | - Yuichiro K Kato
- Quantum Optoelectronics Research Team, RIKEN Center for Advanced Photonics, Saitama, 351-0198, Japan. .,Nanoscale Quantum Photonics Laboratory, RIKEN Cluster for Pioneering Research, Saitama, 351-0198, Japan.
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6
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Weight BM, Sifain AE, Gifford BJ, Kilin D, Kilina S, Tretiak S. Coupling between Emissive Defects on Carbon Nanotubes: Modeling Insights. J Phys Chem Lett 2021; 12:7846-7853. [PMID: 34380317 DOI: 10.1021/acs.jpclett.1c01631] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Covalent functionalization of single-walled carbon nanotubes (SWCNTs) with organic molecules results in red-shifted emissive states associated with sp3-defects in the tube lattice, which facilitate their improved optical functionality, including single-photon emission. The energy of the defect-based electronic excitations (excitons) depends on the molecular adducts, the configuration of the defect, and concentration of defects. Here we model the interactions between two sp3-defects placed at various distances in the (6,5) SWCNT using time-dependent density functional theory. Calculations reveal that these interactions conform to the effective model of J-aggregates for well-spaced defects (>2 nm), leading to a red-shifted and optically allowed (bright) lowest energy exciton. H-aggregate behavior is not observed for any defect orientations, which is beneficial for emission. The splitting between the lowest energy bright and optically forbidden (dark) excitons and the pristine excitonic band are controlled by the single-defect configurations and their axial separation. These findings enable a synthetic design strategy for SWCNTs with tunable near-infrared emission.
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Affiliation(s)
- Braden M Weight
- Center for Integrated Nanotechnologies, Center for Nonlinear Studies, and Theoretical Division Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
- Department of Physics and Astronomy, University of Rochester, Rochester, New York 14627, United States
- Department of Chemistry and Biochemistry, North Dakota State University, Fargo, North Dakota 58102, United States
- Department of Physics, North Dakota State University, Fargo, North Dakota 58102, United States
| | - Andrew E Sifain
- U.S. Army Research Laboratory, Aberdeen Proving Ground, Maryland 21005, United States
| | - Brendan J Gifford
- Center for Integrated Nanotechnologies, Center for Nonlinear Studies, and Theoretical Division Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
| | - Dmitri Kilin
- Department of Chemistry and Biochemistry, North Dakota State University, Fargo, North Dakota 58102, United States
| | - Svetlana Kilina
- Department of Chemistry and Biochemistry, North Dakota State University, Fargo, North Dakota 58102, United States
| | - Sergei Tretiak
- Center for Integrated Nanotechnologies, Center for Nonlinear Studies, and Theoretical Division Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
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7
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Kim Y, Hu Z, Avdeev ID, Singh A, Singh A, Chandrasekaran V, Nestoklon MO, Goupalov SV, Hollingsworth JA, Htoon H. Interplay of Bright Triplet and Dark Excitons Revealed by Magneto-Photoluminescence of Individual PbS/CdS Quantum Dots. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2021; 17:e2006977. [PMID: 33690965 DOI: 10.1002/smll.202006977] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/2020] [Revised: 01/22/2021] [Indexed: 06/12/2023]
Abstract
A low-temperature polarization-resolved magneto-photoluminescence experiment is performed on individual PbS/CdS core/shell quantum dots (QDs). The experiment enables a direct measurement of the exciton Landé g factor and the anisotropic zero-field splitting of the lowest emissive bright exciton triplet in PbS/CdS QDs. While anisotropic splittings of individual QDs distribute randomly in 104-325 μeV range, the exciton Landé g factors increase from 0.95 to 2.70 as the emission energy of the QD increases from 1.0 to 1.2 eV. The tight-binding calculations allow to rationalize these trends as a direct consequence of reducing a cubic symmetry of QD via addition/removal of a few (<70) atoms from the surfaces of the PbS core. Furthermore, it is observed that while right (σ + ) and left (σ - ) circularly polarized photoluminescence (PL) peaks split linearly with magnetic field as expected for Zeeman effect, the energy splitting between X and Y linearly polarized PL peaks remains nearly unchanged. The theoretical study reveals rich and complex magnetic field-induced interplay of bright triplet and dark exciton states explaining this puzzling behavior. These findings fill the missing gaps in the understanding of lead salt QDs and provide foundation for development of classical and quantum light sources operating at telecommunication wavelengths.
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Affiliation(s)
- Younghee Kim
- Center for Integrated Nanotechnologies, Materials Physics and Applications Division, Los Alamos National Laboratory, Los Alamos, NM 87545, USA
| | - Zhongjian Hu
- Center for Integrated Nanotechnologies, Materials Physics and Applications Division, Los Alamos National Laboratory, Los Alamos, NM 87545, USA
| | | | - Ajay Singh
- Center for Integrated Nanotechnologies, Materials Physics and Applications Division, Los Alamos National Laboratory, Los Alamos, NM 87545, USA
| | - Amita Singh
- Center for Integrated Nanotechnologies, Materials Physics and Applications Division, Los Alamos National Laboratory, Los Alamos, NM 87545, USA
| | - Vigneshwaran Chandrasekaran
- Center for Integrated Nanotechnologies, Materials Physics and Applications Division, Los Alamos National Laboratory, Los Alamos, NM 87545, USA
| | | | - Serguei V Goupalov
- Ioffe Institute, St. Petersburg, 194021, Russia
- Department of Physics, Jackson State University, Jackson, MS 39217, USA
| | - Jennifer A Hollingsworth
- Center for Integrated Nanotechnologies, Materials Physics and Applications Division, Los Alamos National Laboratory, Los Alamos, NM 87545, USA
| | - Han Htoon
- Center for Integrated Nanotechnologies, Materials Physics and Applications Division, Los Alamos National Laboratory, Los Alamos, NM 87545, USA
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8
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Berger F, de Sousa JA, Zhao S, Zorn NF, El Yumin AA, Quintana García A, Settele S, Högele A, Crivillers N, Zaumseil J. Interaction of Luminescent Defects in Carbon Nanotubes with Covalently Attached Stable Organic Radicals. ACS NANO 2021; 15:5147-5157. [PMID: 33600164 PMCID: PMC7992189 DOI: 10.1021/acsnano.0c10341] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/10/2020] [Accepted: 02/05/2021] [Indexed: 05/17/2023]
Abstract
The functionalization of single-walled carbon nanotubes (SWCNTs) with luminescent sp3 defects has greatly improved their performance in applications such as quantum light sources and bioimaging. Here, we report the covalent functionalization of purified semiconducting SWCNTs with stable organic radicals (perchlorotriphenylmethyl, PTM) carrying a net spin. This model system allows us to use the near-infrared photoluminescence arising from the defect-localized exciton as a highly sensitive probe for the short-range interaction between the PTM radical and the SWCNT. Our results point toward an increased triplet exciton population due to radical-enhanced intersystem crossing, which could provide access to the elusive triplet manifold in SWCNTs. Furthermore, this simple synthetic route to spin-labeled defects could enable magnetic resonance studies complementary to in vivo fluorescence imaging with functionalized SWCNTs and facilitate the scalable fabrication of spintronic devices with magnetically switchable charge transport.
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Affiliation(s)
- Felix
J. Berger
- Institute
for Physical Chemistry, Universität
Heidelberg, 69120 Heidelberg, Germany
- Centre
for Advanced Materials, Universität
Heidelberg, 69120 Heidelberg, Germany
| | - J. Alejandro de Sousa
- Institut
de Ciència de Materials de Barcelona (ICMAB-CSIC), Campus UAB, 08193 Bellaterra, Spain
- Laboratorio
de Electroquímica, Departamento de Química, Facultad
de Ciencias, Universidad de los Andes, 5101 Mérida, Venezuela
| | - Shen Zhao
- Faculty
of Physics, Munich Quantum Center and Center for NanoScience (CeNS), Ludwig-Maximilians-Universität München, 80539 München, Germany
- Munich Center
for Quantum Science and Technology (MCQST), 80799 München, Germany
| | - Nicolas F. Zorn
- Institute
for Physical Chemistry, Universität
Heidelberg, 69120 Heidelberg, Germany
- Centre
for Advanced Materials, Universität
Heidelberg, 69120 Heidelberg, Germany
| | - Abdurrahman Ali El Yumin
- Institute
for Physical Chemistry, Universität
Heidelberg, 69120 Heidelberg, Germany
- Centre
for Advanced Materials, Universität
Heidelberg, 69120 Heidelberg, Germany
| | - Aleix Quintana García
- Institut
de Ciència de Materials de Barcelona (ICMAB-CSIC), Campus UAB, 08193 Bellaterra, Spain
| | - Simon Settele
- Institute
for Physical Chemistry, Universität
Heidelberg, 69120 Heidelberg, Germany
| | - Alexander Högele
- Faculty
of Physics, Munich Quantum Center and Center for NanoScience (CeNS), Ludwig-Maximilians-Universität München, 80539 München, Germany
- Munich Center
for Quantum Science and Technology (MCQST), 80799 München, Germany
| | - Núria Crivillers
- Institut
de Ciència de Materials de Barcelona (ICMAB-CSIC), Campus UAB, 08193 Bellaterra, Spain
| | - Jana Zaumseil
- Institute
for Physical Chemistry, Universität
Heidelberg, 69120 Heidelberg, Germany
- Centre
for Advanced Materials, Universität
Heidelberg, 69120 Heidelberg, Germany
- E-mail:
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9
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Palotás J, Negyedi M, Kollarics S, Bojtor A, Rohringer P, Pichler T, Simon F. Incidence of Quantum Confinement on Dark Triplet Excitons in Carbon Nanotubes. ACS NANO 2020; 14:11254-11261. [PMID: 32790277 PMCID: PMC7513465 DOI: 10.1021/acsnano.0c03139] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2020] [Accepted: 08/13/2020] [Indexed: 05/28/2023]
Abstract
The photophysics of single-wall carbon nanotubes (SWCNTs) is intensively studied due to their potential application in light harvesting and optoelectronics. Excited states of SWCNTs form strongly bound electron-hole pairs, excitons, of which only singlet excitons participate in application relevant optical transitions. Long-living spin-triplet states hinder applications, but they emerge as candidates for quantum information storage. Therefore, knowledge of the triplet exciton energy structure, in particular in a SWCNT chirality dependent manner, is greatly desired. We report the observation of light emission from triplet state recombination, i.e., phosphorescence, for several SWCNT chiralities using a purpose-built spectrometer. This yields the singlet-triplet gap as a function of the SWCNT diameter, and it follows predictions based on quantum confinement effects. Saturation under high microwave power (up to 10 W) irradiation allows the spin-relaxation time for triplet states to be determined. Our study sensitively discriminates whether the lowest optically active state is populated from an excited state on the same nanotube or through Förster exciton energy transfer from a neighboring nanotube.
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Affiliation(s)
- J. Palotás
- Department
of Physics and MTA-BME Lendület Spintronics Research Group
(PROSPIN), Budapest University of Technology
and Economics, PO Box 91, H-1521 Budapest, Hungary
- Institute
for Molecules and Materials, FELIX Laboratory, Radboud University, Toernooiveld 7, 6525ED Nijmegen, The Netherlands
| | - M. Negyedi
- Department
of Physics and MTA-BME Lendület Spintronics Research Group
(PROSPIN), Budapest University of Technology
and Economics, PO Box 91, H-1521 Budapest, Hungary
- Universität
Tübingen Physikalische Institut, Auf der Morgenstelle 14D, 72076 Tübingen, Germany
- HighFinesse
GmbH, Auf der Morgenstelle
14D, 72076 Tübingen, Germany
| | - S. Kollarics
- Department
of Physics and MTA-BME Lendület Spintronics Research Group
(PROSPIN), Budapest University of Technology
and Economics, PO Box 91, H-1521 Budapest, Hungary
| | - A. Bojtor
- Department
of Physics and MTA-BME Lendület Spintronics Research Group
(PROSPIN), Budapest University of Technology
and Economics, PO Box 91, H-1521 Budapest, Hungary
| | - P. Rohringer
- Faculty
of Physics, University of Vienna, Strudlhofgasse 4, Vienna A-1090, Austria
| | - T. Pichler
- Faculty
of Physics, University of Vienna, Strudlhofgasse 4, Vienna A-1090, Austria
| | - F. Simon
- Department
of Physics and MTA-BME Lendület Spintronics Research Group
(PROSPIN), Budapest University of Technology
and Economics, PO Box 91, H-1521 Budapest, Hungary
- Laboratory
of Physics of Complex Matter, École
Polytechnique Fédérale de Lausanne, Lausanne CH-1015, Switzerland
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