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Palato S, Seiler H, Baker H, Sonnichsen C, Brosseau P, Kambhampati P. Investigating the electronic structure of confined multiexcitons with nonlinear spectroscopies. J Chem Phys 2020; 152:104710. [DOI: 10.1063/1.5142180] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Affiliation(s)
- S. Palato
- Department of Chemistry, McGill University, 801 Sherbrooke Street W, Montréal, Québec H3A 0B8, Canada
| | - H. Seiler
- Department of Chemistry, McGill University, 801 Sherbrooke Street W, Montréal, Québec H3A 0B8, Canada
| | - H. Baker
- Department of Chemistry, McGill University, 801 Sherbrooke Street W, Montréal, Québec H3A 0B8, Canada
| | - C. Sonnichsen
- Department of Chemistry, McGill University, 801 Sherbrooke Street W, Montréal, Québec H3A 0B8, Canada
| | - P. Brosseau
- Department of Chemistry, McGill University, 801 Sherbrooke Street W, Montréal, Québec H3A 0B8, Canada
| | - P. Kambhampati
- Department of Chemistry, McGill University, 801 Sherbrooke Street W, Montréal, Québec H3A 0B8, Canada
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2
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Specht JF, Scott R, Corona Castro M, Christodoulou S, Bertrand GHV, Prudnikau AV, Antanovich A, Siebbeles LDA, Owschimikow N, Moreels I, Artemyev M, Woggon U, Achtstein AW, Richter M. Size-dependent exciton substructure in CdSe nanoplatelets and its relation to photoluminescence dynamics. NANOSCALE 2019; 11:12230-12241. [PMID: 31204756 DOI: 10.1039/c9nr03161h] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
CdSe nanoplatelets can be synthesized with different lateral sizes; very small nanoplatelets have almost quantum dot like features (almost discrete exciton states), while very large ones are expected to have properties of colloidal quantum wells (exciton continuum). However, nanoplatelets can be in an intermediate confinement regime with a rich substructure of excitons, which is neither quantum dot like nor an ideal 2D exciton. In this manuscript, we discuss the experimental transition energies and relaxation dynamics of exciton states in CdSe platelets with varying lateral dimensions and compare them with a microscopic theoretical model including exciton-phonon scattering. The model takes special care of the interplay of confinement and Coulomb coupling in the intermediate regime showing strong changes with respect to simple weak or strong confinement models by solving the full four dimensional lateral factorization free exciton wavefunction. Depending on the platelet size broad resonances previously attributed to just ground and excited states are actually composed of a rich substructure of several exciton states in their temporal dynamics. We show that these factorization free exciton states can explain the spectral features observed in photoluminescence experiments. Furthermore we demonstrate that the interplay of exciton bright and dark states provides principle insights into the overall temporal relaxation dynamics, and allows tuning of the exciton cooling via lateral platelet size. Our results and theoretical approach are directly relevant for understanding e.g. the size tuneability of lasing, excitonic cooling dynamics or light harvesting applications in these and similar 2D systems of finite lateral size.
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Affiliation(s)
- Judith F Specht
- Institut für Theoretische Physik, Nichtlineare Optik und Quantenelektronik, Technische Universität Berlin, Hardenbergstr. 36, 10623 Berlin, Germany.
| | - Riccardo Scott
- Institut für Optik und Atomare Physik, Technische Universität Berlin, Strasse des 17 Juni 135, 10623 Berlin, Germany.
| | - Marta Corona Castro
- Institut für Theoretische Physik, Nichtlineare Optik und Quantenelektronik, Technische Universität Berlin, Hardenbergstr. 36, 10623 Berlin, Germany.
| | - Sotirios Christodoulou
- ICFO-Institut de Ciencies Fotoniques, 08860 Castelldefels, Barcelona, Spain and Istituto Italiano di Tecnologia, IT-16163 Genova, Italy
| | - Guillaume H V Bertrand
- Istituto Italiano di Tecnologia, IT-16163 Genova, Italy and CEA Saclay, 91191 Gif-sur-Yvette, France
| | - 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
| | - Laurens D A Siebbeles
- Optoelectronic Materials Section, Delft University of Technology, 2629 HZ Delft, The Netherlands
| | - Nina Owschimikow
- Institut für Optik und Atomare Physik, Technische Universität Berlin, Strasse des 17 Juni 135, 10623 Berlin, Germany.
| | - Iwan Moreels
- Istituto Italiano di Tecnologia, IT-16163 Genova, Italy and Department of Chemistry, Ghent University, Krijgslaan 281 - S3, 9000 Gent, Belgium
| | - Mikhail Artemyev
- Research Institute for Physical Chemical Problems of Belarusian State University, 220006, Minsk, Belarus
| | - Ulrike Woggon
- Institut für Optik und Atomare Physik, Technische Universität Berlin, Strasse des 17 Juni 135, 10623 Berlin, Germany.
| | - Alexander W Achtstein
- Institut für Optik und Atomare Physik, Technische Universität Berlin, Strasse des 17 Juni 135, 10623 Berlin, Germany.
| | - Marten Richter
- Institut für Theoretische Physik, Nichtlineare Optik und Quantenelektronik, Technische Universität Berlin, Hardenbergstr. 36, 10623 Berlin, Germany.
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3
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Lin ML, Miscuglio M, Polovitsyn A, Leng YC, Martín-García B, Moreels I, Tan PH, Krahne R. Giant-Shell CdSe/CdS Nanocrystals: Exciton Coupling to Shell Phonons Investigated by Resonant Raman Spectroscopy. J Phys Chem Lett 2019; 10:399-405. [PMID: 30626187 DOI: 10.1021/acs.jpclett.8b03211] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
The interaction between excitons and phonons in semiconductor nanocrystals plays a crucial role in the exciton energy spectrum and dynamics, and thus in their optical properties. We investigate the exciton-phonon coupling in giant-shell CdSe/CdS core-shell nanocrystals via resonant Raman spectroscopy. The Huang-Rhys parameter is evaluated by the intensity ratio of the longitudinal-optical (LO) phonon of CdS with its first multiscattering (2LO) replica. We used four different excitation wavelengths in the range from the onset of the CdS shell absorption to well above the CdS shell band edge to get insight into resonance effects of the CdS LO phonon with high-energy excitonic transitions. The isotropic spherical giant-shell nanocrystals show consistently stronger exciton-phonon coupling as compared to the anisotropic rod-shaped dot-in-rod (DiR) architecture, and the 2LO/LO intensity ratio decreases for excitation wavelengths approaching the CdS band edge. The strong exciton-phonon coupling in the spherical giant-shell nanocrystals can be related to the delocalization of the electronic wave functions. Furthermore, we observe the radial breathing modes of the GS nanocrystals and their overtones by ultralow frequency Raman spectroscopy with nonresonant excitation, using laser energies well below the band gap of the heteronanocrystals, and highlight the differences between higher-order optical and acoustic phonon modes.
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Affiliation(s)
- Miao-Ling Lin
- State Key Laboratory of Superlattices and Microstructures , Institute of Semiconductors, Chinese Academy of Sciences , Beijing 100083 , China
- Center of Materials Science and Optoelectronics Engineering & CAS Center of Excellence in Topological Quantum Computation , University of Chinese Academy of Sciences , Beijing 100190 , China
| | - Mario Miscuglio
- Istituto Italiano di Tecnologia (IIT) , Via Morego 30 , 16163 Genoa , Italy
| | - Anatolii Polovitsyn
- Department of Chemistry , Ghent University , Krijgslaan 281-S3 , 9000 Gent , Belgium
| | - Yu-Chen Leng
- State Key Laboratory of Superlattices and Microstructures , Institute of Semiconductors, Chinese Academy of Sciences , Beijing 100083 , China
- Center of Materials Science and Optoelectronics Engineering & CAS Center of Excellence in Topological Quantum Computation , University of Chinese Academy of Sciences , Beijing 100190 , China
| | | | - Iwan Moreels
- Department of Chemistry , Ghent University , Krijgslaan 281-S3 , 9000 Gent , Belgium
| | - Ping-Heng Tan
- State Key Laboratory of Superlattices and Microstructures , Institute of Semiconductors, Chinese Academy of Sciences , Beijing 100083 , China
- Center of Materials Science and Optoelectronics Engineering & CAS Center of Excellence in Topological Quantum Computation , University of Chinese Academy of Sciences , Beijing 100190 , China
| | - Roman Krahne
- Istituto Italiano di Tecnologia (IIT) , Via Morego 30 , 16163 Genoa , Italy
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Diroll BT, Guo P, Schaller RD. Heat Transfer at Hybrid Interfaces: Interfacial Ligand-to-Nanocrystal Heating Monitored with Infrared Pump, Electronic Probe Spectroscopy. NANO LETTERS 2018; 18:7863-7869. [PMID: 30431280 DOI: 10.1021/acs.nanolett.8b03640] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
The transfer of thermal energy from the ligand passivating layer to the inorganic core of colloidal nanocrystals is observed using infrared-pump, electronic-probe (IPEP) spectroscopy. Inorganic nanocrystals are excellent model systems for organic-inorganic hybrid interfaces as they have much larger surface-to-volume ratios than bulk solids, which facilitate spectroscopic measurements of weak signals. Such interfaces between disparate materials are challenging to probe by traditional methods. Here, resonant excitation of the hydrocarbon ligand vibrational absorptions results in a transient red-shift of the CdSe nanocrystal excitonic features consistent with heating, as demonstrated by steady-state absorption measurements, which provide a calibration of the pump-induced temperature rise. The time constant associated with heating ranges from 10 to 30 ps depending on the sample morphology, static temperature, input fluence, and environment, all of which are studied in this work. Heat transfer speeds up and the magnitude of nanocrystal heating decreases at higher temperatures. Unlike chemical modulation of electrical conductivity, ligand exchange for several common organic ligands does not dramatically change the interfacial conductivity of the nanocrystal-ligand interface. However, changes in the medium (e.g., solvent) do change the rate of heat outcoupling from the nanocrystal-ligand complex. Although applied here to nanocrystals to measure interfacial heat transfer, IPEP spectroscopy is readily applicable for any heterogeneous system in which one component has spectrally isolated molecular vibrations or lattice phonons.
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Affiliation(s)
- Benjamin T Diroll
- Center for Nanoscale Materials , Argonne National Laboratory , Lemont , Illinois 60439 , United States
| | - Peijun Guo
- Center for Nanoscale Materials , Argonne National Laboratory , Lemont , Illinois 60439 , 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
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Schnitzenbaumer KJ, Dukovic G. Comparison of Phonon Damping Behavior in Quantum Dots Capped with Organic and Inorganic Ligands. NANO LETTERS 2018; 18:3667-3674. [PMID: 29781281 DOI: 10.1021/acs.nanolett.8b00800] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Surface ligand modification of colloidal semiconductor nanocrystals has been widely used as a means of controlling photoexcited-state generation, relaxation, and coupling to the environment. While progress has been made in understanding how surface ligand modification affects the behavior of electronic states, less is known about the influence of surface ligand modification on phonon behavior, which impacts relaxation dynamics and transport phenomena. In this work, we compare the dynamics of optical and acoustic phonons in CdTe quantum dots (QDs), CdTe/CdSe core/shell QDs capped with octadecylphosphonic acid ligands, and CdTe QDs capped with Se2- to ascertain how ligand exchange from native aliphatic ligands to single-atom Se2- ligands affects phonon behavior. We use transient absorption spectroscopy and observe modulations in the kinetics of excited-state decay due to QD lattice vibrations from both optical and acoustic phonons, which we describe using the damped oscillator model. The longitudinal optical phonons have similar frequencies and damping behavior in all three samples. In contrast, the longitudinal acoustic phonon mode in the Se2--capped CdTe QDs is severely damped, much more so than in CdTe and CdTe/CdSe QDs capped with the native aliphatic ligands. We attribute these differences in the acoustic phonon behavior to the differences in how the QD dissipates vibrational energy to its surroundings as a function of ligand identity. Our results indicate that these inorganic surface-capping ligands enhance not only the electronic but also the mechanical coupling of nanocrystals with their environment.
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Affiliation(s)
- Kyle J Schnitzenbaumer
- Department of Chemistry and Biochemistry , University of Colorado , Boulder , Colorado 80309 , United States
| | - Gordana Dukovic
- Department of Chemistry and Biochemistry , University of Colorado , Boulder , Colorado 80309 , United States
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6
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Xu R, Liao C, Xu Y, Zhang C, Xiao M, Zhang L, Lu C, Cui Y, Zhang J. Bright type-II photoluminescence from Mn-doped CdS/ZnSe/ZnS quantum dots with Mn 2+ ions as exciton couplers. NANOSCALE 2017; 9:18281-18289. [PMID: 29139512 DOI: 10.1039/c7nr05670b] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Mn2+ ions were introduced as exciton couplers to enhance the quantum yield (QY) of type-II photoluminescence (PL) from CdS/ZnSe/ZnS quantum dots (QDs) with slow hot-exciton cooling and low radiative rate. Transient absorption spectroscopy verifies the faster bleach recovery and faster peak red-shifting at the charge-transfer state. And the transient PL peak of the QDs changes from blue-shifting to red-shifting due to Mn2+ doping. The QY of type-II PL can be enhanced from ∼35% to ∼60% by Mn2+ doping. As the energy-transfer-stations of hot excitons during rapid ET (∼100 ps), Mn2+ ions transform more excitons from hot to cold for emission. As the couplers of cold excitons during long thermal equilibrium (∼100 ns), Mn2+ ions further decrease exciton trapping by strong bidirectional coupling. This work provides a unique way of acquiring high QY of type-II PL, and highlights the general law of PL enhancement in Mn-doped QDs.
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Affiliation(s)
- Ruilin Xu
- Advanced Photonic Center, Southeast University, Nanjing 210096, China.
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7
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Balan AD, Eshet H, Olshansky JH, Lee YV, Rabani E, Alivisatos AP. Effect of Thermal Fluctuations on the Radiative Rate in Core/Shell Quantum Dots. NANO LETTERS 2017; 17:1629-1636. [PMID: 28183177 DOI: 10.1021/acs.nanolett.6b04816] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
The effect of lattice fluctuations and electronic excitations on the radiative rate is demonstrated in CdSe/CdS core/shell spherical quantum dots (QDs). Using a combination of time-resolved photoluminescence spectroscopy and atomistic simulations, we show that lattice fluctuations can change the radiative rate over the temperature range from 78 to 300 K. We posit that the presence of the core/shell interface plays a significant role in dictating this behavior. We show that the other major factor that underpins the change in radiative rate with temperature is the presence of higher energy states corresponding to electron excitation into the shell. These effects should be present in other core/shell samples and should also affect other excited state rates, such as the rate of Auger recombination or the rate of charge transfer.
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Affiliation(s)
- Arunima D Balan
- Department of Chemistry, University of California, Berkeley , Berkeley, California 94720, United States
- Materials Sciences Division, Lawrence Berkeley National Laboratory , Berkeley, California 94720, United States
- Kavli Energy NanoScience Institute , Berkeley, California 94720, United States
| | | | - Jacob H Olshansky
- Department of Chemistry, University of California, Berkeley , Berkeley, California 94720, United States
- Materials Sciences Division, Lawrence Berkeley National Laboratory , Berkeley, California 94720, United States
- Kavli Energy NanoScience Institute , Berkeley, California 94720, United States
| | - Youjin V Lee
- Department of Chemistry, University of California, Berkeley , Berkeley, California 94720, United States
| | - Eran Rabani
- Department of Chemistry, University of California, Berkeley , Berkeley, California 94720, United States
- Materials Sciences Division, Lawrence Berkeley National Laboratory , Berkeley, California 94720, United States
| | - A Paul Alivisatos
- Department of Chemistry, University of California, Berkeley , Berkeley, California 94720, United States
- Materials Sciences Division, Lawrence Berkeley National Laboratory , Berkeley, California 94720, United States
- Kavli Energy NanoScience Institute , Berkeley, California 94720, United States
- Department of Materials Science and Engineering, University of California , Berkeley, California 94720, United States
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8
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Miscuglio M, Lin ML, Di Stasio F, Tan PH, Krahne R. Confined Acoustic Phonons in Colloidal Nanorod Heterostructures Investigated by Nonresonant Raman Spectroscopy and Finite Elements Simulations. NANO LETTERS 2016; 16:7664-7670. [PMID: 27960519 DOI: 10.1021/acs.nanolett.6b03706] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Lattice vibrational modes in cadmium chalcogenide nanocrystals (NCs) have a strong impact on the carrier dynamics of excitons in such confined systems and on the optical properties of these nanomaterials. A prominent material for light emitting applications are CdSe/CdS core-shell dot-in-rods. Here we present a detailed investigation of the acoustic phonon modes in such dot-in-rods by nonresonant Raman spectroscopy with laser excitation energy lower than their bandgap. With high signal-to-noise ratio in the frequency range from 5-50 cm-1, we reveal distinct Raman bands that can be related to confined extensional and radial-breathing modes (RBM). Comparison of the experimental results with finite elements simulation and analytical analysis gives detailed insight into the localized nature of the acoustic vibration modes and their resonant frequencies. In particular, the RBM of dot-in-rods cannot be understood by an oscillation of a CdSe sphere embedded in a CdS rod matrix. Instead, the dot-in-rod architecture leads to a reduction of the sound velocity in the core region of the rod, which results in a redshift of the rod RBM frequency and localization of the phonon induced strain in vicinity of the core where optical transitions occur. Such localized effects potentially can be exploited as a tool to tune exciton-phonon coupling in nanocrystal heterostructures.
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Affiliation(s)
- Mario Miscuglio
- Nanochemistry Department, Istituto Italiano di Tecnologia , Via Morego 30, 16163 Genova, Italy
- Dipartimento di Chimica e Chimica Industriale, Università di Genova , Via Dodecaneso 31, 16146 Genova, Italy
| | - Miao-Ling Lin
- State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences , Beijing 100083, China
| | - Francesco Di Stasio
- Nanochemistry Department, Istituto Italiano di Tecnologia , Via Morego 30, 16163 Genova, Italy
| | - Ping-Heng Tan
- State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences , Beijing 100083, China
| | - Roman Krahne
- Nanochemistry Department, Istituto Italiano di Tecnologia , Via Morego 30, 16163 Genova, Italy
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Mork AJ, Lee EMY, Dahod NS, Willard AP, Tisdale WA. Modulation of Low-Frequency Acoustic Vibrations in Semiconductor Nanocrystals through Choice of Surface Ligand. J Phys Chem Lett 2016; 7:4213-4216. [PMID: 27700102 DOI: 10.1021/acs.jpclett.6b01659] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Recent experimental and theoretical results have highlighted the surprisingly dominant role of acoustic phonons in regulating dynamic processes in nanocrystals. While it has been known for many years that acoustic phonon frequencies in nanocrystals depend on their size, strategies for tuning acoustic phonon energy at a given fixed size were not available. Here, we show that acoustic phonon frequencies in colloidal quantum dots (QDs) can be tuned through the choice of the surface ligand. Using low-frequency Raman spectroscopy, we explore the dependence of the l = 0 acoustic phonon resonance in CdSe QDs on ligand size, molecular weight, and chemical functionality. On the basis of these aggregated observations, we conclude that the primary mechanism for this effect is mass loading of the QD surface and that interactions between ligands and with the surrounding environment play a comparatively minor yet non-negligible role.
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Affiliation(s)
- A Jolene Mork
- Department of Chemistry and ‡Department of Chemical Engineering, Massachusetts Institute of Technology , Cambridge, Massachusetts 02139, United States
| | - Elizabeth M Y Lee
- Department of Chemistry and ‡Department of Chemical Engineering, Massachusetts Institute of Technology , Cambridge, Massachusetts 02139, United States
| | - Nabeel S Dahod
- Department of Chemistry and ‡Department of Chemical Engineering, Massachusetts Institute of Technology , Cambridge, Massachusetts 02139, United States
| | - Adam P Willard
- Department of Chemistry and ‡Department of Chemical Engineering, Massachusetts Institute of Technology , Cambridge, Massachusetts 02139, United States
| | - William A Tisdale
- Department of Chemistry and ‡Department of Chemical Engineering, Massachusetts Institute of Technology , Cambridge, Massachusetts 02139, United States
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Cassette E, Dean JC, Scholes GD. Two-Dimensional Visible Spectroscopy For Studying Colloidal Semiconductor Nanocrystals. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2016; 12:2234-44. [PMID: 26849032 DOI: 10.1002/smll.201502733] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/08/2015] [Indexed: 05/27/2023]
Abstract
Possibilities offered by 2D visible spectroscopy for the investigation of the properties of excitons in colloidal semiconductor nanocrystals are overviewed, with a particular focus on their ultrafast dynamics. The technique of 2D electronic spectroscopy is illustrated with several examples showing its advantages compared to 1D ultrafast spectroscopic techniques (transient absorption and time-resolved photoluminescence).
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Affiliation(s)
- Elsa Cassette
- Department of Chemistry, Princeton University, Princeton, NJ, 08544, USA
| | - Jacob C Dean
- Department of Chemistry, Princeton University, Princeton, NJ, 08544, USA
| | - Gregory D Scholes
- Department of Chemistry, Princeton University, Princeton, NJ, 08544, USA
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11
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Biadala L, Siebers B, Beyazit Y, Tessier MD, Dupont D, Hens Z, Yakovlev DR, Bayer M. Band-Edge Exciton Fine Structure and Recombination Dynamics in InP/ZnS Colloidal Nanocrystals. ACS NANO 2016; 10:3356-64. [PMID: 26889780 DOI: 10.1021/acsnano.5b07065] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
We report on a temperature-, time-, and spectrally resolved study of the photoluminescence of type-I InP/ZnS colloidal nanocrystals with varying core size. By studying the exciton recombination dynamics we assess the exciton fine structure in these systems. In addition to the typical bright-dark doublet, the photoluminescence stems from an upper bright state in spite of its large energy splitting (∼100 meV). This striking observation results from dramatically lengthened thermalization processes among the fine structure levels and points to optical-phonon bottleneck effects in InP/ZnS nanocrystals. Furthermore, our data show that the radiative recombination of the dark exciton scales linearly with the bright-dark energy splitting for CdSe and InP nanocrystals. This finding strongly suggests a universal dangling bonds-assisted recombination of the dark exciton in colloidal nanostructures.
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Affiliation(s)
- Louis Biadala
- Experimentelle Physik 2, Technische Universität Dortmund , 44221 Dortmund, Germany
| | - Benjamin Siebers
- Experimentelle Physik 2, Technische Universität Dortmund , 44221 Dortmund, Germany
| | - Yasin Beyazit
- Experimentelle Physik 2, Technische Universität Dortmund , 44221 Dortmund, Germany
| | | | | | | | - Dmitri R Yakovlev
- Experimentelle Physik 2, Technische Universität Dortmund , 44221 Dortmund, Germany
- Ioffe Institute, Russian Academy of Sciences , 194021 St. Petersburg, Russia
| | - 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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12
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Liu S, Borys NJ, Sapra S, Eychmüller A, Lupton JM. Localization and Dynamics of Long-Lived Excitations in Colloidal Semiconductor Nanocrystals with Dual Quantum Confinement. Chemphyschem 2015; 16:1663-9. [DOI: 10.1002/cphc.201402826] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2015] [Revised: 01/30/2015] [Indexed: 11/08/2022]
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13
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Osada N, Oshima T, Kuwahara S, Toyoda T, Shen Q, Katayama K. Photoexcited carrier dynamics of double-layered CdS/CdSe quantum dot sensitized solar cells measured by heterodyne transient grating and transient absorption methods. Phys Chem Chem Phys 2014; 16:5774-8. [DOI: 10.1039/c3cp55177f] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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