51
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Scott R, Prudnikau AV, Antanovich A, Christodoulou S, Riedl T, Bertrand GHV, Owschimikow N, Lindner JKN, Hens Z, Moreels I, Artemyev M, Woggon U, Achtstein AW. A comparative study demonstrates strong size tunability of carrier-phonon coupling in CdSe-based 2D and 0D nanocrystals. NANOSCALE 2019; 11:3958-3967. [PMID: 30762858 DOI: 10.1039/c8nr09458f] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
In a comparative study we investigate the carrier-phonon coupling in CdSe based core-only and hetero 2D as well as 0D nanoparticles. We demonstrate that the coupling can be strongly tuned by the lateral size of nanoplatelets, while, due to the weak lateral confinement, the transition energies are only altered by tens of meV. Our analysis shows that an increase in the lateral platelet area results in a strong decrease in the phonon coupling to acoustic modes due to deformation potential interaction, yielding an exciton deformation potential of 3.0 eV in line with theory. In contrast, coupling to optical modes tends to increase with the platelet area. This cannot be explained by Fröhlich interaction, which is generally dominant in II-VI materials. We compare CdSe/CdS nanoplatelets with their equivalent, spherical CdSe/CdS nanoparticles. Universally, in both systems the introduction of a CdS shell is shown to result in an increase of the average phonon coupling, mainly related to an increase of the coupling to acoustic modes, while the coupling to optical modes is reduced with increasing CdS layer thickness. The demonstrated size and CdS overgrowth tunability has strong implications for applications like tuning carrier cooling and carrier multiplication - relevant for solar energy harvesting applications. Other implications range from transport in nanosystems e.g. for field effect transistors or dephasing control. Our results open up a new toolbox for the design of photonic materials.
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Affiliation(s)
- Riccardo Scott
- Institute of Optics and Atomic Physics, Technical University of Berlin, Strasse des 17. Juni 135, 10623 Berlin, Germany.
| | - Anatol V Prudnikau
- Research Institute for Physical Chemical Problems of Belarusian State University, 220006, Minsk, Belarus
| | - Artsiom Antanovich
- Research Institute for Physical Chemical Problems of Belarusian State University, 220006, Minsk, Belarus
| | | | - Thomas Riedl
- Department of Physics, Paderborn University, Warburger Strasse 100, 33098 Paderborn, Germany
| | - Guillaume H V Bertrand
- CEA Saclay, 91191 Gif-sur-Yvette, France and Istituto Italiano di Tecnologia, Via Morego 30, 16163 Genova, Italy
| | - Nina Owschimikow
- Institute of Optics and Atomic Physics, Technical University of Berlin, Strasse des 17. Juni 135, 10623 Berlin, Germany.
| | - Jörg K N Lindner
- Department of Physics, Paderborn University, Warburger Strasse 100, 33098 Paderborn, Germany
| | - Zeger Hens
- Department of Chemistry, Ghent University, Krijgslaan 281 - S3, 9000 Gent, Belgium
| | - Iwan Moreels
- Department of Chemistry, Ghent University, Krijgslaan 281 - S3, 9000 Gent, Belgium and Istituto Italiano di Tecnologia, Via Morego 30, 16163 Genova, Italy
| | - Mikhail Artemyev
- Research Institute for Physical Chemical Problems of Belarusian State University, 220006, Minsk, Belarus
| | - Ulrike Woggon
- Institute of Optics and Atomic Physics, Technical University of Berlin, Strasse des 17. Juni 135, 10623 Berlin, Germany.
| | - Alexander W Achtstein
- Institute of Optics and Atomic Physics, Technical University of Berlin, Strasse des 17. Juni 135, 10623 Berlin, Germany.
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52
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Diroll BT, Cho W, Coropceanu I, Harvey SM, Brumberg A, Holtgrewe N, Crooker SA, Wasielewski MR, Prakapenka VB, Talapin DV, Schaller RD. Semiconductor Nanoplatelet Excimers. NANO LETTERS 2018; 18:6948-6953. [PMID: 30244582 DOI: 10.1021/acs.nanolett.8b02865] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Excimers, a portmanteau of "excited dimer", are transient species that are formed from the electronic interaction of a fluorophore in the excited state with a neighbor in the ground state, which have found extensive use as laser gain media. Although common in molecular fluorophores, this work presents evidence for the formation of excimers in a new class of materials: atomically precise two-dimensional semiconductor nanoplatelets. Colloidal nanoplatelets of CdSe display two-color photoluminescence resolved at low temperatures with one band attributed to band-edge fluorescence and a second, red band attributed to excimer fluorescence. Previously reasonable explanations for two-color fluorescence, such as charging, are shown to be inconsistent with additional evidence. As with excimers in other materials systems, excimer emission is increased by increasing nanoplatelet concentration and the degree of cofacial stacking. Consistent with their promise as low-threshold gain media, amplified spontaneous emission emerges from the excimer emission line.
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Affiliation(s)
- Benjamin T Diroll
- Center for Nanoscale Materials , Argonne National Laboratory , Lemont , Illinois 60439 , United States
| | - Wooje Cho
- Department of Chemistry , University of Chicago , Chicago , Illinois 60637 , United States
| | - Igor Coropceanu
- Department of Chemistry , University of Chicago , Chicago , Illinois 60637 , United States
| | - Samantha M Harvey
- Department of Chemistry , Northwestern University , Evanston , Illinois 60208 , United States
- Institute for Sustainability and Energy , Northwestern University , Evanston , Illinois 60208 , United States
| | - Alexandra Brumberg
- Department of Chemistry , Northwestern University , Evanston , Illinois 60208 , United States
| | - Nicholas Holtgrewe
- Center for Advanced Radiation Sources , University of Chicago , Chicago , Illinois 60439 , United States
| | - Scott A Crooker
- National High Magnetic Field Laboratory , Los Alamos , New Mexico 87545 , United States
| | - Michael R Wasielewski
- Department of Chemistry , Northwestern University , Evanston , Illinois 60208 , United States
- Institute for Sustainability and Energy , Northwestern University , Evanston , Illinois 60208 , United States
| | - Vitali B Prakapenka
- Center for Advanced Radiation Sources , University of Chicago , Chicago , Illinois 60439 , United States
| | - Dmitri V Talapin
- Department of Chemistry , University of Chicago , Chicago , Illinois 60637 , United States
| | - Richard D Schaller
- Center for Nanoscale Materials , Argonne National Laboratory , Lemont , Illinois 60439 , United States
- Department of Chemistry , Northwestern University , Evanston , Illinois 60208 , United States
- Institute for Sustainability and Energy , Northwestern University , Evanston , Illinois 60208 , United States
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53
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Christodoulou S, Climente JI, Planelles J, Brescia R, Prato M, Martín-García B, Khan AH, Moreels I. Chloride-Induced Thickness Control in CdSe Nanoplatelets. NANO LETTERS 2018; 18:6248-6254. [PMID: 30178676 PMCID: PMC6526959 DOI: 10.1021/acs.nanolett.8b02361] [Citation(s) in RCA: 83] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2018] [Revised: 09/03/2018] [Indexed: 05/19/2023]
Abstract
Current colloidal synthesis methods for CdSe nanoplatelets (NPLs) routinely yield samples that emit, in discrete steps, from 460 to 550 nm. A significant challenge lies with obtaining thicker NPLs, to further widen the emission range. This is at present typically achieved via colloidal atomic layer deposition onto CdSe cores, or by synthesizing NPL core/shell structures. Here, we demonstrate a novel reaction scheme, where we start from 4.5 monolayer (ML) NPLs and increase the thickness in a two-step reaction that switches from 2D to 3D growth. The key feature is the enhancement of the growth rate of basal facets by the addition of CdCl2, resulting in a series of nearly monodisperse CdSe NPLs with thicknesses between 5.5 and 8.5 ML. Optical characterization yielded emission peaks from 554 nm up to 625 nm with a line width (fwhm) of 9-13 nm, making them one of the narrowest colloidal nanocrystal emitters currently available in this spectral range. The NPLs maintained a short emission lifetime of 5-11 ns. Finally, due to the increased red shift of the NPL band edge photoluminescence excitation spectra revealed several high-energy peaks. Calculation of the NPL band structure allowed us to identify these excited-state transitions, and spectral shifts are consistent with a significant mixing of light and split-off hole states. Clearly, chloride ions can add a new degree of freedom to the growth of 2D colloidal nanocrystals, yielding new insights into both the NPL synthesis as well as their optoelectronic properties.
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Affiliation(s)
- Sotirios Christodoulou
- Istituto
Italiano di Tecnologia, Via Morego 30, 16163 Genova, Italy
- ICFO
- Institut de Ciencies Fotoniques, The Barcelona Institute of Science
and Technology, Castelldefels, 08860 Barcelona, Spain
| | - Juan I. Climente
- Departament
de Química Física i Analítica, Universitat Jaume I, 12080 Castelló de la Plana, Spain
| | - Josep Planelles
- Departament
de Química Física i Analítica, Universitat Jaume I, 12080 Castelló de la Plana, Spain
| | - Rosaria Brescia
- Istituto
Italiano di Tecnologia, Via Morego 30, 16163 Genova, Italy
| | - Mirko Prato
- Istituto
Italiano di Tecnologia, Via Morego 30, 16163 Genova, Italy
| | | | - Ali Hossain Khan
- Istituto
Italiano di Tecnologia, Via Morego 30, 16163 Genova, Italy
- Department
of Chemistry, Ghent University, Krijgslaan 281-S3, 9000 Gent, Belgium
- E-mail:
| | - Iwan Moreels
- Istituto
Italiano di Tecnologia, Via Morego 30, 16163 Genova, Italy
- Department
of Chemistry, Ghent University, Krijgslaan 281-S3, 9000 Gent, Belgium
- E-mail:
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54
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Pandya R, Chen RYS, Cheminal A, Dufour M, Richter JM, Thomas TH, Ahmed S, Sadhanala A, Booker EP, Divitini G, Deschler F, Greenham NC, Ithurria S, Rao A. Exciton–Phonon Interactions Govern Charge-Transfer-State Dynamics in CdSe/CdTe Two-Dimensional Colloidal Heterostructures. J Am Chem Soc 2018; 140:14097-14111. [DOI: 10.1021/jacs.8b05842] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Raj Pandya
- Cavendish Laboratory, University of Cambridge, J.J. Thompson Avenue, CB3 0HE, Cambridge, United Kingdom
| | - Richard Y. S. Chen
- Cavendish Laboratory, University of Cambridge, J.J. Thompson Avenue, CB3 0HE, Cambridge, United Kingdom
| | - Alexandre Cheminal
- Cavendish Laboratory, University of Cambridge, J.J. Thompson Avenue, CB3 0HE, Cambridge, United Kingdom
| | - Marion Dufour
- LPEM, ESPCI Paris, PSL Research University, CNRS, 10 Rue Vauquelin, 75005 Paris, France
| | - Johannes M. Richter
- Cavendish Laboratory, University of Cambridge, J.J. Thompson Avenue, CB3 0HE, Cambridge, United Kingdom
| | - Tudor H. Thomas
- Cavendish Laboratory, University of Cambridge, J.J. Thompson Avenue, CB3 0HE, Cambridge, United Kingdom
| | - Shahab Ahmed
- Institute for Manufacturing, Department of Engineering, University of Cambridge, 17 Charles Babbage Road, CB3 0FS, Cambridge, United Kingdom
| | - Aditya Sadhanala
- Cavendish Laboratory, University of Cambridge, J.J. Thompson Avenue, CB3 0HE, Cambridge, United Kingdom
| | - Edward P. Booker
- Cavendish Laboratory, University of Cambridge, J.J. Thompson Avenue, CB3 0HE, Cambridge, United Kingdom
| | - Giorgio Divitini
- Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, CB3 0FS, Cambridge, United Kingdom
| | - Felix Deschler
- Cavendish Laboratory, University of Cambridge, J.J. Thompson Avenue, CB3 0HE, Cambridge, United Kingdom
| | - Neil C. Greenham
- Cavendish Laboratory, University of Cambridge, J.J. Thompson Avenue, CB3 0HE, Cambridge, United Kingdom
| | - Sandrine Ithurria
- LPEM, ESPCI Paris, PSL Research University, CNRS, 10 Rue Vauquelin, 75005 Paris, France
| | - Akshay Rao
- Cavendish Laboratory, University of Cambridge, J.J. Thompson Avenue, CB3 0HE, Cambridge, United Kingdom
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55
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Achtstein AW, Marquardt O, Scott R, Ibrahim M, Riedl T, Prudnikau AV, Antanovich A, Owschimikow N, Lindner JKN, Artemyev M, Woggon U. Impact of Shell Growth on Recombination Dynamics and Exciton-Phonon Interaction in CdSe-CdS Core-Shell Nanoplatelets. ACS NANO 2018; 12:9476-9483. [PMID: 30192515 DOI: 10.1021/acsnano.8b04803] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
We investigate the impact of shell growth on the carrier dynamics and exciton-phonon coupling in CdSe-CdS core-shell nanoplatelets with varying shell thickness. We observe that the recombination dynamics can be prolonged by more than one order of magnitude, and analyze the results in a global rate model as well as with simulations including strain and excitonic effects. We reveal that type I band alignment in the hetero platelets is maintained at least up to three monolayers of CdS, resulting in approximately constant radiative rates. Hence, observed changes of decay dynamics are not the result of an increasingly different electron and hole exciton wave function delocalization as often assumed, but an increasingly better passivation of nonradiative surface defects by the shell. Based on a global analysis of time-resolved and time-integrated data, we recover and model the temperature dependent quantum yield of these nanostructures and show that CdS shell growth leads to a strong enhancement of the photoluminescence quantum yield. Our results explain, for example, the very high lasing gain observed in CdSe-CdS nanoplatelets due to the type I band alignment that also makes them interesting as solar energy concentrators. Further, we reveal that the exciton-LO-phonon coupling is strongly tunable by the CdS shell thickness, enabling emission line width and coherence length control.
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Affiliation(s)
- Alexander W Achtstein
- Institute of Optics and Atomic Physics , Technical University of Berlin , Strasse des 17. Juni 135 , 10623 Berlin , Germany
| | - Oliver Marquardt
- Weierstraß Institute for Applied Analysis and Stochastics , Mohrenstraße 39 , 10117 Berlin , Germany
| | - Riccardo Scott
- Institute of Optics and Atomic Physics , Technical University of Berlin , Strasse des 17. Juni 135 , 10623 Berlin , Germany
| | - Mohamed Ibrahim
- Institute of Optics and Atomic Physics , Technical University of Berlin , Strasse des 17. Juni 135 , 10623 Berlin , Germany
| | - Thomas Riedl
- Department of Physics , Paderborn University , Warburger Strasse 100 , 33098 Paderborn , Germany
| | - Anatol V Prudnikau
- Research Institute for Physical Chemical Problems of Belarusian State University , 220006 Minsk , Belarus
- Physical Chemistry , TU Dresden , Bergstrasse 66b , 01062 Dresden , Germany
| | - Artsiom Antanovich
- Research Institute for Physical Chemical Problems of Belarusian State University , 220006 Minsk , Belarus
| | - Nina Owschimikow
- Institute of Optics and Atomic Physics , Technical University of Berlin , Strasse des 17. Juni 135 , 10623 Berlin , Germany
| | - Jörg K N Lindner
- Department of Physics , Paderborn University , Warburger Strasse 100 , 33098 Paderborn , Germany
| | - Mikhail Artemyev
- Research Institute for Physical Chemical Problems of Belarusian State University , 220006 Minsk , Belarus
| | - Ulrike Woggon
- Institute of Optics and Atomic Physics , Technical University of Berlin , Strasse des 17. Juni 135 , 10623 Berlin , Germany
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56
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Shornikova EV, Biadala L, Yakovlev DR, Feng D, Sapega VF, Flipo N, Golovatenko AA, Semina MA, Rodina AV, Mitioglu AA, Ballottin MV, Christianen PCM, Kusrayev YG, Nasilowski M, Dubertret B, Bayer M. Electron and Hole g-Factors and Spin Dynamics of Negatively Charged Excitons in CdSe/CdS Colloidal Nanoplatelets with Thick Shells. NANO LETTERS 2018; 18:373-380. [PMID: 29160075 DOI: 10.1021/acs.nanolett.7b04203] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
We address spin properties and spin dynamics of carriers and charged excitons in CdSe/CdS colloidal nanoplatelets with thick shells. Magneto-optical studies are performed by time-resolved and polarization-resolved photoluminescence, spin-flip Raman scattering and picosecond pump-probe Faraday rotation in magnetic fields up to 30 T. We show that at low temperatures the nanoplatelets are negatively charged so that their photoluminescence is dominated by radiative recombination of negatively charged excitons (trions). Electron g-factor of 1.68 is measured, and heavy-hole g-factor varying with increasing magnetic field from -0.4 to -0.7 is evaluated. Hole g-factors for two-dimensional structures are calculated for various hole confining potentials for cubic- and wurtzite lattice in CdSe core. These calculations are extended for various quantum dots and nanoplatelets based on II-VI semiconductors. We developed a magneto-optical technique for the quantitative evaluation of the nanoplatelets orientation in ensemble.
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Affiliation(s)
- Elena V Shornikova
- Experimentelle Physik 2, Technische Universität Dortmund , 44221 Dortmund, Germany
- Rzhanov Institute of Semiconductor Physics, Siberian Branch of Russian Academy of Sciences , 630090 Novosibirsk, Russia
| | - Louis Biadala
- Institut d'Electronique, de Microélectronique et de Nanotechnologie, CNRS , 59652 Villeneuve-d'Ascq, France
| | - Dmitri R Yakovlev
- Experimentelle Physik 2, Technische Universität Dortmund , 44221 Dortmund, Germany
- Ioffe Institute, Russian Academy of Sciences , 194021 St. Petersburg, Russia
| | - Donghai Feng
- Experimentelle Physik 2, Technische Universität Dortmund , 44221 Dortmund, Germany
- State Key Laboratory of Precision Spectroscopy, East China Normal University , 200062 Shanghai, China
| | - Victor F Sapega
- Ioffe Institute, Russian Academy of Sciences , 194021 St. Petersburg, Russia
| | - Nathan Flipo
- Experimentelle Physik 2, Technische Universität Dortmund , 44221 Dortmund, Germany
| | | | - Marina A Semina
- Ioffe Institute, Russian Academy of Sciences , 194021 St. Petersburg, Russia
| | - Anna V Rodina
- Ioffe Institute, Russian Academy of Sciences , 194021 St. Petersburg, Russia
| | - Anatolie A Mitioglu
- High Field Magnet Laboratory (HFML-EMFL), Radboud University , 6525 ED Nijmegen, The Netherlands
| | - Mariana V Ballottin
- High Field Magnet Laboratory (HFML-EMFL), Radboud University , 6525 ED Nijmegen, The Netherlands
| | - Peter C M Christianen
- High Field Magnet Laboratory (HFML-EMFL), Radboud University , 6525 ED Nijmegen, The Netherlands
| | - Yuri G Kusrayev
- Ioffe Institute, Russian Academy of Sciences , 194021 St. Petersburg, Russia
| | - Michel Nasilowski
- Laboratoire de Physique et d'Etude des Matériaux, ESPCI, CNRS , 75231 Paris, France
| | - Benoit Dubertret
- Laboratoire de Physique et d'Etude des Matériaux, ESPCI, CNRS , 75231 Paris, France
| | - Manfred Bayer
- Experimentelle Physik 2, Technische Universität Dortmund , 44221 Dortmund, Germany
- Ioffe Institute, Russian Academy of Sciences , 194021 St. Petersburg, Russia
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