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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Kurilovich AA, Mantsevich VN, Chechkin AV, Palyulin VV. Negative diffusion of excitons in quasi-two-dimensional systems. Phys Chem Chem Phys 2024; 26:922-935. [PMID: 38088027 DOI: 10.1039/d3cp03521b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2024]
Abstract
We show how two different mobile-immobile type models explain the observation of negative diffusion of excitons reported in experimental studies in quasi-two-dimensional semiconductor systems. The main reason for the effect is the initial trapping and a delayed release of free excitons in the area close to the original excitation spot. The density of trapped excitons is not registered experimentally. Hence, the signal from the free excitons alone includes the delayed release of not diffusing trapped particles. This is seen as the narrowing of the exciton density profile or decrease of mean-squared displacement which is then interpreted as a negative diffusion. The effect is enhanced with the increase of recombination intensity as well as the rate of the exciton-exciton binary interactions.
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Affiliation(s)
- Aleksandr A Kurilovich
- Center for Energy Science and Technology, Skolkovo Institute of Science and Technology, Bolshoy Boulevard 30, 121205, Moscow, Russia
| | - Vladimir N Mantsevich
- Chair of Semiconductors and Cryoelectronics, Physics department, Lomonosov Moscow State University, 119991, Moscow, Russia
| | - Aleksei V Chechkin
- Faculty of Pure and Applied Mathematics, Hugo Steinhaus Center, Wroclaw University of Science and Technology, Wyspianskiego 27, 50-370 Wroclaw, Poland
- Institute for Physics & Astronomy, University of Potsdam, D-14476 Potsdam-Golm, Germany
- Akhiezer Institute for Theoretical Physics National Science Center "Kharkov Institute of Physics and Technology", 61108, Kharkov, Ukraine
| | - Vladimir V Palyulin
- Applied AI centre, Skolkovo Institute of Science and Technology, Bolshoy Boulevard 30, Moscow, 121205, Russia.
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3
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van der Sluijs M, Vliem JF, de Wit JW, Rietveld JJ, Meeldijk JD, Vanmaekelbergh DAM. Cation Exchange and Spontaneous Crystal Repair Resulting in Ultrathin, Planar CdS Nanosheets. CHEMISTRY OF MATERIALS : A PUBLICATION OF THE AMERICAN CHEMICAL SOCIETY 2023; 35:8301-8308. [PMID: 37840776 PMCID: PMC10568967 DOI: 10.1021/acs.chemmater.3c01900] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/31/2023] [Revised: 09/15/2023] [Indexed: 10/17/2023]
Abstract
Cation exchange has become a major postsynthetic tool to obtain nanocrystals with a combination of stoichiometry, size, and shape that is challenging to achieve by direct wet-chemical synthesis. Here, we report on the transformation of highly anisotropic, ultrathin, and planar PbS nanosheets into CdS nanosheets of the same dimensions. We monitor the evolution of the Cd-for-Pb exchange by ex-situ TEM, HAADF-STEM, and EDX. We observe that in the early stages of the exchange the sheets show large in-sheet voids that repair spontaneously upon further exchange and annealing, resulting in ultrathin, planar, and crystalline CdS nanosheets. After cation exchange, the nanosheets show broad sub-band gap luminescence, as often observed in CdS nanocrystals. The photoluminescence excitation spectrum reveals the heavy- and light-hole exciton features, with very strong quantum confinement and large electron-hole Coulomb energy, typical for 2D ultrathin Cd-chalcogenide nanosheets.
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Affiliation(s)
- Maaike
M. van der Sluijs
- Condensed
Matter & Interfaces, Debye Institute for Nanomaterials Science, Utrecht University, 3584 CC Utrecht, The Netherlands
| | - Jara F. Vliem
- Condensed
Matter & Interfaces, Debye Institute for Nanomaterials Science, Utrecht University, 3584 CC Utrecht, The Netherlands
| | - Jur W. de Wit
- Condensed
Matter & Interfaces, Debye Institute for Nanomaterials Science, Utrecht University, 3584 CC Utrecht, The Netherlands
| | - Jeppe J. Rietveld
- Condensed
Matter & Interfaces, Debye Institute for Nanomaterials Science, Utrecht University, 3584 CC Utrecht, The Netherlands
| | - Johannes D. Meeldijk
- Electron
Microscopy Centre, Utrecht University, Universiteitsweg 99, 3584 CG Utrecht, Netherlands
| | - Daniel A. M. Vanmaekelbergh
- Condensed
Matter & Interfaces, Debye Institute for Nanomaterials Science, Utrecht University, 3584 CC Utrecht, The Netherlands
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4
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Ouzit Z, Baillard G, Liu J, Wagnon B, Guillemeney L, Abécassis B, Coolen L. Luminescence Dynamics of Single Self-Assembled Chains of Förster (FRET)-Coupled CdSe Nanoplatelets. J Phys Chem Lett 2023:6209-6216. [PMID: 37384838 DOI: 10.1021/acs.jpclett.3c00908] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/01/2023]
Abstract
Self-assembled linear chains of CdSe nanoplatelets are known to exhibit highly efficient Förster resonant energy transfer (FRET) leading to fast exciton diffusion between platelets. Here, we compare the luminescence decay dynamics of single nanoplatelets, clusters of a few platelets, and self-assembled chains. As the number of stacked platelets is increased, we show that the luminescence decay becomes faster, which can be interpreted as the FRET-mediated effect of quenchers: excitons may diffuse to nearby quenchers so that their decay rate is increased. On the other hand, a minor slow decay component is also observed for single platelets, corresponding to trapping-detrapping mechanisms in nearby trap states. The contribution of the slow component is enhanced for the platelet chains. This is consistent with a FRET-mediated trapping mechanism where the excitons would diffuse from platelet to platelet until they reach a trap state. Finally, we develop toy models for the FRET-mediated quenching and trapping effects on the decay curves and analyze the relevant parameters.
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Affiliation(s)
- Z Ouzit
- Sorbonne Université, CNRS, Institut des NanoSciences de Paris, INSP, F-75005 Paris, France
| | - G Baillard
- Sorbonne Université, CNRS, Institut des NanoSciences de Paris, INSP, F-75005 Paris, France
| | - J Liu
- Sorbonne Université, CNRS, Institut des NanoSciences de Paris, INSP, F-75005 Paris, France
| | - B Wagnon
- ENSL, CNRS, Laboratoire de Chimie UMR 5182, 46 allée d'Italie, F-69364 Lyon, France
| | - L Guillemeney
- ENSL, CNRS, Laboratoire de Chimie UMR 5182, 46 allée d'Italie, F-69364 Lyon, France
| | - B Abécassis
- ENSL, CNRS, Laboratoire de Chimie UMR 5182, 46 allée d'Italie, F-69364 Lyon, France
| | - L Coolen
- Sorbonne Université, CNRS, Institut des NanoSciences de Paris, INSP, F-75005 Paris, France
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5
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Vonk SJW, Rabouw FT. Biexciton Blinking in CdSe-Based Quantum Dots. J Phys Chem Lett 2023:5353-5361. [PMID: 37276380 DOI: 10.1021/acs.jpclett.3c00437] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Experiments on single colloidal quantum dots (QDs) have revealed temporal fluctuations in the emission efficiency of the single-exciton state. These fluctuations, often termed "blinking", are caused by opening/closing of charge-carrier traps and/or charging/discharging of the QD. In the regime of strong optical excitation, multiexciton states are formed. The emission efficiencies of multiexcitons are lower because of Auger processes, but a quantitative characterization is challenging. Here, we quantify fluctuations of the biexciton efficiency for single CdSe/CdS/ZnS core-shell QDs. We find that the biexciton efficiency "blinks" significantly. The additional electron due to charging of a QD accelerates Auger recombination by a factor of 2 compared to the neutral biexciton, while opening/closing of a charge-carrier trap leads to an increase of the nonradiative recombination rate by a factor of 4. To understand the fast rate of trap-assisted recombination, we propose a revised model for trap-assisted recombination based on reversible trapping. Finally, we discuss the implications of biexciton blinking for lasing applications.
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Affiliation(s)
- Sander J W Vonk
- Debye Institute for Nanomaterials Science, Utrecht University, Princetonplein 1, 3584 CC Utrecht, The Netherlands
| | - Freddy T Rabouw
- Debye Institute for Nanomaterials Science, Utrecht University, Princetonplein 1, 3584 CC Utrecht, The Netherlands
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6
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Rodà C, Di Giacomo A, Tasende Rodríguez LC, M CS, Leemans J, Hens Z, Geiregat P, Moreels I. Colloidal CdSe/CdS Core/Crown Nanoplatelets for Efficient Blue Light Emission and Optical Amplification. NANO LETTERS 2023; 23:3224-3230. [PMID: 37125440 DOI: 10.1021/acs.nanolett.2c05061] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/19/2023]
Abstract
The application of CdSe nanoplatelets (NPLs) in the ultraviolet/blue region remains an open challenge due to charge trapping typically leading to limited photoluminescence quantum efficiency (PL QE) and sub-bandgap emission in core-only NPLs. Here, we synthesized 3.5 monolayer core/crown CdSe/CdS NPLs with various crown dimensions, exhibiting saturated blue emission and PL QE up to 55%. Compared to core-only NPLs, the PL intensity decays monoexponentially over two decades due to suppressed deep trapping and delayed emission. In both core-only and core/crown NPLs we observe biexciton-mediated optical gain between 470 and 510 nm, with material gain coefficients up to 7900 cm-1 and consistently lower gain thresholds in crowned NPLs. Gain lifetimes are limited to 40 ps, due to residual ultrafast trapping and higher exciton densities at threshold. Our results provide guidelines for rational optimization of thin CdSe NPLs toward lighting and light-amplification applications.
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Affiliation(s)
- Carmelita Rodà
- Physics and Chemistry of Nanostructures, Department of Chemistry, Ghent University, Krijgslaan 281-S3, 9000 Gent, Belgium
- Center for Nano and Biophotonics, Ghent University, Technologiepark, Zwijnaarde 15, 9052 Gent, Belgium
| | - Alessio Di Giacomo
- Physics and Chemistry of Nanostructures, Department of Chemistry, Ghent University, Krijgslaan 281-S3, 9000 Gent, Belgium
- Center for Nano and Biophotonics, Ghent University, Technologiepark, Zwijnaarde 15, 9052 Gent, Belgium
| | - Lucía Camila Tasende Rodríguez
- Physics and Chemistry of Nanostructures, Department of Chemistry, Ghent University, Krijgslaan 281-S3, 9000 Gent, Belgium
- Center for Nano and Biophotonics, Ghent University, Technologiepark, Zwijnaarde 15, 9052 Gent, Belgium
| | - Chandra Sekhar M
- Physics and Chemistry of Nanostructures, Department of Chemistry, Ghent University, Krijgslaan 281-S3, 9000 Gent, Belgium
- Center for Nano and Biophotonics, Ghent University, Technologiepark, Zwijnaarde 15, 9052 Gent, Belgium
| | - Jari Leemans
- Physics and Chemistry of Nanostructures, Department of Chemistry, Ghent University, Krijgslaan 281-S3, 9000 Gent, Belgium
- Center for Nano and Biophotonics, Ghent University, Technologiepark, Zwijnaarde 15, 9052 Gent, Belgium
| | - Zeger Hens
- Physics and Chemistry of Nanostructures, Department of Chemistry, Ghent University, Krijgslaan 281-S3, 9000 Gent, Belgium
- Center for Nano and Biophotonics, Ghent University, Technologiepark, Zwijnaarde 15, 9052 Gent, Belgium
| | - Pieter Geiregat
- Physics and Chemistry of Nanostructures, Department of Chemistry, Ghent University, Krijgslaan 281-S3, 9000 Gent, Belgium
- Center for Nano and Biophotonics, Ghent University, Technologiepark, Zwijnaarde 15, 9052 Gent, Belgium
| | - Iwan Moreels
- Physics and Chemistry of Nanostructures, Department of Chemistry, Ghent University, Krijgslaan 281-S3, 9000 Gent, Belgium
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7
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Hasham M, Narayanan P, Yarur Villanueva F, Green PB, Imperiale CJ, Wilson MWB. Sequential Carrier Transfer Can Accelerate Triplet Energy Transfer from Functionalized CdSe Nanocrystals. J Phys Chem Lett 2023; 14:1899-1909. [PMID: 36780580 DOI: 10.1021/acs.jpclett.2c03443] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
Nanocrystal (NC)-sensitized triplet-fusion upconversion is a rising strategy to convert long-wavelength, incoherent light into higher-energy output photons. Here, we chart the photophysics of tailor-functionalized CdSe NCs to understand energy transfer to surface-anchored transmitter ligands, which can proceed via correlated exciton transfer or sequential carrier hops. Varying NC size, we observe a pronounced acceleration of energy transfer (from kquench = 0.0096 ns-1 ligand-1 to 0.064 ns-1 ligand-1) when the barrier to hole-first sequential transfer is lowered from 100 ± 25 meV to 50 ± 25 meV. This acceleration is 5.1× the expected effect of increased carrier wave function leakage, so we conclude that sequential transfer becomes kinetically dominant under the latter conditions. Last, transient photoluminescence shows that NC band-edge and trap states are comparably quenched by functionalization (up to ∼98% for sequential transfer) and exhibit matched dynamics for t > 300 ns, consistent with a dynamic quasi-equilibrium where photoexcitations can ultimately be extracted even when a carrier is initially trapped.
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Affiliation(s)
- Minhal Hasham
- Department of Chemistry, University of Toronto, Toronto, Ontario M5S 3H6, Canada
| | - Pournima Narayanan
- Department of Chemistry, University of Toronto, Toronto, Ontario M5S 3H6, Canada
| | | | - Philippe B Green
- Department of Chemistry, University of Toronto, Toronto, Ontario M5S 3H6, Canada
| | | | - Mark W B Wilson
- Department of Chemistry, University of Toronto, Toronto, Ontario M5S 3H6, Canada
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8
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Diroll BT, Guzelturk B, Po H, Dabard C, Fu N, Makke L, Lhuillier E, Ithurria S. 2D II-VI Semiconductor Nanoplatelets: From Material Synthesis to Optoelectronic Integration. Chem Rev 2023; 123:3543-3624. [PMID: 36724544 DOI: 10.1021/acs.chemrev.2c00436] [Citation(s) in RCA: 32] [Impact Index Per Article: 32.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The field of colloidal synthesis of semiconductors emerged 40 years ago and has reached a certain level of maturity thanks to the use of nanocrystals as phosphors in commercial displays. In particular, II-VI semiconductors based on cadmium, zinc, or mercury chalcogenides can now be synthesized with tailored shapes, composition by alloying, and even as nanocrystal heterostructures. Fifteen years ago, II-VI semiconductor nanoplatelets injected new ideas into this field. Indeed, despite the emergence of other promising semiconductors such as halide perovskites or 2D transition metal dichalcogenides, colloidal II-VI semiconductor nanoplatelets remain among the narrowest room-temperature emitters that can be synthesized over a wide spectral range, and they exhibit good material stability over time. Such nanoplatelets are scientifically and technologically interesting because they exhibit optical features and production advantages at the intersection of those expected from colloidal quantum dots and epitaxial quantum wells. In organic solvents, gram-scale syntheses can produce nanoparticles with the same thicknesses and optical properties without inhomogeneous broadening. In such nanoplatelets, quantum confinement is limited to one dimension, defined at the atomic scale, which allows them to be treated as quantum wells. In this review, we discuss the synthetic developments, spectroscopic properties, and applications of such nanoplatelets. Covering growth mechanisms, we explain how a thorough understanding of nanoplatelet growth has enabled the development of nanoplatelets and heterostructured nanoplatelets with multiple emission colors, spatially localized excitations, narrow emission, and high quantum yields over a wide spectral range. Moreover, nanoplatelets, with their large lateral extension and their thin short axis and low dielectric surroundings, can support one or several electron-hole pairs with large exciton binding energies. Thus, we also discuss how the relaxation processes and lifetime of the carriers and excitons are modified in nanoplatelets compared to both spherical quantum dots and epitaxial quantum wells. Finally, we explore how nanoplatelets, with their strong and narrow emission, can be considered as ideal candidates for pure-color light emitting diodes (LEDs), strong gain media for lasers, or for use in luminescent light concentrators.
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Affiliation(s)
- Benjamin T Diroll
- Center for Nanoscale Materials, Argonne National Laboratory, 9700 S. Cass Avenue, Lemont, Illinois 60439, United States
| | - Burak Guzelturk
- X-ray Science Division, Advanced Photon Source, Argonne National Laboratory, 9700 S. Cass Avenue, Lemont, Illinois 60439, United States
| | - Hong Po
- Laboratoire de Physique et d'Etude des Matériaux, ESPCI-Paris, PSL Research University, Sorbonne Université Univ Paris 06, CNRS UMR 8213, 10 rue Vauquelin 75005 Paris, France
| | - Corentin Dabard
- Laboratoire de Physique et d'Etude des Matériaux, ESPCI-Paris, PSL Research University, Sorbonne Université Univ Paris 06, CNRS UMR 8213, 10 rue Vauquelin 75005 Paris, France
| | - Ningyuan Fu
- Laboratoire de Physique et d'Etude des Matériaux, ESPCI-Paris, PSL Research University, Sorbonne Université Univ Paris 06, CNRS UMR 8213, 10 rue Vauquelin 75005 Paris, France
| | - Lina Makke
- Laboratoire de Physique et d'Etude des Matériaux, ESPCI-Paris, PSL Research University, Sorbonne Université Univ Paris 06, CNRS UMR 8213, 10 rue Vauquelin 75005 Paris, France
| | - Emmanuel Lhuillier
- Sorbonne Université, CNRS, Institut des NanoSciences de Paris, INSP, 75005 Paris, France
| | - Sandrine Ithurria
- Laboratoire de Physique et d'Etude des Matériaux, ESPCI-Paris, PSL Research University, Sorbonne Université Univ Paris 06, CNRS UMR 8213, 10 rue Vauquelin 75005 Paris, France
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9
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VanOrman ZA, Weiss R, Bieber AS, Chen B, Nienhaus L. Mechanistic insight into CdSe nanoplatelet-sensitized upconversion: size and stacking induced effects. Chem Commun (Camb) 2023; 59:322-325. [PMID: 36511180 DOI: 10.1039/d2cc04694f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
CdSe nanoplatelets (NPLs) have been reported as triplet sensitizers for photon upconversion (UC). However, their UC quantum yields lag behind more conventional systems. Here, we take advantage of their one-dimensional quantum confinement to decouple effects caused by the energetic driving force and lateral size. A surprising anti-correlation between the power threshold Ith and the UC quantum yield based on the NPL size is found. We attribute this result to two distinct triplet-triplet annihilation mechanisms based on the NPL lateral dimension and degree of NPL stacking-mediated either by molecular diffusion or triplet energy diffusion.
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Affiliation(s)
- Zachary A VanOrman
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, FL 32306, USA.
| | - Rachel Weiss
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, FL 32306, USA.
| | - Alexander S Bieber
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, FL 32306, USA.
| | - Banghao Chen
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, FL 32306, USA.
| | - Lea Nienhaus
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, FL 32306, USA.
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10
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Rodà C, Geiregat P, Di Giacomo A, Moreels I, Hens Z. Area-Independence of the Biexciton Oscillator Strength in CdSe Colloidal Nanoplatelets. NANO LETTERS 2022; 22:9537-9543. [PMID: 36409988 DOI: 10.1021/acs.nanolett.2c03683] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Colloidal CdSe nanoplatelets (NPLs) are unique systems to study two-dimensional excitons and excitonic complexes. However, while absorption and emission of photons through exciton formation and recombination have been extensively quantified, few studies have addressed the exciton-biexciton transition. Here, we use cross-polarized pump-probe spectroscopy to measure the absorption coefficient spectrum of this transition and determine the biexciton oscillator strength (fBX). We show that fBX is independent of the NPL area and that the concomitant biexciton area (SBX) agrees with predictions of a short-range interaction model. Moreover, we show that fBX is comparable to the oscillator strength of forming localized excitons at room temperature while being unaffected itself by center-of-mass localization. These results confirm the relevance of biexcitons for light-matter interaction in NPLs. Moreover, the quantification of the exciton-biexciton transition introduced here will enable researchers to rank 2D materials by the strength of this transition and to compare experimental results with theoretical predictions.
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Affiliation(s)
- Carmelita Rodà
- Physics and Chemistry of Nanostructures, Department of Chemistry, Ghent University, 9000Gent, Belgium
- NB-Photonics, Center for Nano- and Biophotonics, Ghent University, 9000Gent, Belgium
| | - Pieter Geiregat
- Physics and Chemistry of Nanostructures, Department of Chemistry, Ghent University, 9000Gent, Belgium
- NB-Photonics, Center for Nano- and Biophotonics, Ghent University, 9000Gent, Belgium
| | - Alessio Di Giacomo
- Physics and Chemistry of Nanostructures, Department of Chemistry, Ghent University, 9000Gent, Belgium
- NB-Photonics, Center for Nano- and Biophotonics, Ghent University, 9000Gent, Belgium
| | - Iwan Moreels
- Physics and Chemistry of Nanostructures, Department of Chemistry, Ghent University, 9000Gent, Belgium
- NB-Photonics, Center for Nano- and Biophotonics, Ghent University, 9000Gent, Belgium
| | - Zeger Hens
- Physics and Chemistry of Nanostructures, Department of Chemistry, Ghent University, 9000Gent, Belgium
- NB-Photonics, Center for Nano- and Biophotonics, Ghent University, 9000Gent, Belgium
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11
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Kurilovich AA, Mantsevich VN, Mardoukhi Y, Stevenson KJ, Chechkin AV, Palyulin VV. Non-Markovian diffusion of excitons in layered perovskites and transition metal dichalcogenides. Phys Chem Chem Phys 2022; 24:13941-13950. [PMID: 35621272 DOI: 10.1039/d2cp00557c] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The diffusion of excitons in perovskites and transition metal dichalcogenides shows clear anomalous, subdiffusive behaviour in experiments. In this paper we develop a non-Markovian mobile-immobile model which provides an explanation of this behaviour through paired theoretical and simulation approaches. The simulation model is based on a random walk on a 2D lattice with randomly distributed deep traps such that the trapping time distribution involves slowly decaying power-law asymptotics. The theoretical model uses coupled diffusion and rate equations for free and trapped excitons, respectively, with an integral term responsible for trapping. The model provides a good fitting of the experimental data, thus, showing a way for quantifying the exciton diffusion dynamics.
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Affiliation(s)
- Aleksandr A Kurilovich
- Center for Energy Science and Technology, Skolkovo Institute of Science and Technology, 121205, Moscow, Russia
| | - Vladimir N Mantsevich
- Chair of Semiconductors and Cryoelectronics & Quantum Technology Center, Physics Department, Lomonosov Moscow State University, 119991 Moscow, Russia
| | - Yousof Mardoukhi
- Institute for Physics & Astronomy, University of Potsdam, D-14476 Potsdam-Golm, Germany
| | - Keith J Stevenson
- Center for Energy Science and Technology, Skolkovo Institute of Science and Technology, 121205, Moscow, Russia
| | - Aleksei V Chechkin
- Institute for Physics & Astronomy, University of Potsdam, D-14476 Potsdam-Golm, Germany.,Faculty of Pure and Applied Mathematics, Hugo Steinhaus Center, Wroclaw University of Science and Technology, Wyspianskiego 27, 50-370 Wroclaw, Poland.,Akhiezer Institute for Theoretical Physics National Science Center "Kharkov Institute of Physics and Technology", 61108, Kharkov, Ukraine
| | - Vladimir V Palyulin
- RAIC Center, Skolkovo Institute of Science and Technology, 121205, Moscow, Russia.
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12
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Cocina A, Brechbühler R, Vonk SJW, Cui J, Rossinelli AA, Rojo H, Rabouw FT, Norris DJ. Nanophotonic Approach to Study Excited-State Dynamics in Semiconductor Nanocrystals. J Phys Chem Lett 2022; 13:4145-4151. [PMID: 35506998 DOI: 10.1021/acs.jpclett.2c00599] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
In semiconductor nanocrystals, excited electrons relax through multiple radiative and nonradiative pathways. This complexity complicates characterization of their decay processes with standard time- and temperature-dependent photoluminescence studies. Here, we exploit a simple nanophotonic approach to augment such measurements and to address open questions related to nanocrystal emission. We place nanocrystals at different distances from a gold reflector to affect radiative rates through variations in the local density of optical states. We apply this approach to spherical CdSe-based nanocrystals to probe the radiative efficiency and polarization properties of the lowest dark and bright excitons by analyzing temperature-dependent emission dynamics. For CdSe-based nanoplatelets, we identify the charge-carrier trapping mechanism responsible for strongly delayed emission. Our method, when combined with careful modeling of the influence of the nanophotonic environment on the relaxation dynamics, offers a versatile strategy to disentangle the complex excited-state decay pathways present in fluorescent nanocrystals as well as other emitters.
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Affiliation(s)
- Ario Cocina
- Optical Materials Engineering Laboratory, Department of Mechanical and Process Engineering, ETH Zurich, 8092 Zurich, Switzerland
| | - Raphael Brechbühler
- Optical Materials Engineering Laboratory, Department of Mechanical and Process Engineering, ETH Zurich, 8092 Zurich, Switzerland
- Laboratory for Air Pollution and Environmental Technology, Empa, 8600 Dübendorf, Switzerland
| | - Sander J W Vonk
- Debye Institute for Nanomaterials Science, Utrecht University, 3584 CC Utrecht, The Netherlands
| | - Jian Cui
- Optical Materials Engineering Laboratory, Department of Mechanical and Process Engineering, ETH Zurich, 8092 Zurich, Switzerland
- Helmholtz Pioneer Campus, Helmholtz Zentrum München, 85764 Neuherberg, Germany
| | - Aurelio A Rossinelli
- Optical Materials Engineering Laboratory, Department of Mechanical and Process Engineering, ETH Zurich, 8092 Zurich, Switzerland
| | - Henar Rojo
- Optical Materials Engineering Laboratory, Department of Mechanical and Process Engineering, ETH Zurich, 8092 Zurich, Switzerland
| | - Freddy T Rabouw
- Optical Materials Engineering Laboratory, Department of Mechanical and Process Engineering, ETH Zurich, 8092 Zurich, Switzerland
- Debye Institute for Nanomaterials Science, Utrecht University, 3584 CC Utrecht, The Netherlands
| | - David J Norris
- Optical Materials Engineering Laboratory, Department of Mechanical and Process Engineering, ETH Zurich, 8092 Zurich, Switzerland
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Olejniczak A, Rich R, Gryczynski Z, Cichy B. Non-excitonic defect-assisted radiative transitions are responsible for new D-type blinking in ternary quantum dots. NANOSCALE HORIZONS 2021; 7:63-76. [PMID: 34792059 DOI: 10.1039/d1nh00424g] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
This work addresses the issue of dark states formation in QDs by cooperative excitonic and intrinsic defect-assisted radiative transitions. Here we refer to the observed blinking as D-type to distinguish it from purely excitonic types. It is shown experimentally that defect-assisted radiative relaxations in a single I-III-VI QD result in atypical blinking characteristics that cannot be explained on the basis of charged exciton models. In addition to the excitonic channel, it has been proposed that defect-assisted kinetics can also form blinking patterns. Two conditions for the formation of dark states have been identified which are related to correlation and competition when considering photons emitted from bright defects. Two transition schemes have therefore been proposed. The first transition scheme includes time-correlated trapping of more than one electron at a single trap centre. This is used to simulate variations in the defect's charge state and switching between radiative/nonradiative transitions. The latter scheme, on the other hand, involves uncorrelated trapping and radiative relaxations from two different types of defects (competition). Both schemes are seen to play an equal role in radiative processes in I-III-VI QDs. Considered together, the proposed models can reflect the experimental data with very good accuracy, providing a better understanding of the underlying physics. An important implication of these schemes is that dark states formation doesn't have to be limited to mechanisms that involve charged excitons, and it may also be observed for independent defect assisted kinetics. This is especially valid for highly defected or multinary QDs.
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Affiliation(s)
- Adam Olejniczak
- Institute of Low Temperature and Structure Research, Polish Academy of Sciences, Okólna 2, 50-422 Wrocław, Poland.
| | - Ryan Rich
- Department of Mathematics, Computer Science and Physics, Texas Wesleyan University, 1201 Wesleyan Street, Fort Worth, TX 76105, USA
| | - Zygmunt Gryczynski
- Department of Physics and Astronomy, Texas Christian University, Fort Worth, TX 76129, USA
| | - Bartłomiej Cichy
- Institute of Low Temperature and Structure Research, Polish Academy of Sciences, Okólna 2, 50-422 Wrocław, Poland.
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Wang L, Xiang D, Gao K, Wang J, Wu K. Colloidal n-Doped CdSe and CdSe/ZnS Nanoplatelets. J Phys Chem Lett 2021; 12:11259-11266. [PMID: 34766755 DOI: 10.1021/acs.jpclett.1c02856] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Colloidal semiconductor nanoplatelets (NPLs) are chemical versions of well-studied quantum wells (QWs). For QWs, gating and carrier doping are standard tools to manipulate their optical, electric, or magnetic properties. It would be highly desirable to use pure chemical methods to dope extra charge carriers into free-standing colloidal NPLs to achieve a similar level of manipulation. Here we report colloidal n-doped CdSe and CdSe/ZnS NPLs achieved through a photochemical doping method. The extra electrons doped into the conduction band edges are evidenced by exciton absorption bleaches recoverable through dedoping and the appearance of new intersub-band transitions in the near-infrared. A high surface ligand coverage is the key to successful doping; otherwise, the doped electrons can be depleted likely by unpassivated surface cations. Large trion binding energies of 20-30 meV are found for the n-doped CdSe NPLs, which, in contrast, are reduced by 1 order of magnitude in CdSe/ZnS core/shell NPLs due to dielectric screening. Furthermore, we identify a long-lived negative trion with a lifetime of 1.5-1.6 ns that is likely dominated by radiative recombination.
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Affiliation(s)
- Lifeng Wang
- State Key Laboratory of Molecular Reaction Dynamics and Dynamics Research Center for Energy and Environmental Materials, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, Liaoning, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Dongmei Xiang
- State Key Laboratory of Molecular Reaction Dynamics and Dynamics Research Center for Energy and Environmental Materials, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, Liaoning, China
| | - Kaimin Gao
- State Key Laboratory of Molecular Reaction Dynamics and Dynamics Research Center for Energy and Environmental Materials, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, Liaoning, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Junhui Wang
- State Key Laboratory of Molecular Reaction Dynamics and Dynamics Research Center for Energy and Environmental Materials, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, Liaoning, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Kaifeng Wu
- State Key Laboratory of Molecular Reaction Dynamics and Dynamics Research Center for Energy and Environmental Materials, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, Liaoning, China
- University of Chinese Academy of Sciences, Beijing 100049, China
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