1
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Tolmachev DO, Fernée MJ, Shornikova EV, Siverin NV, Yakovlev DR, Van Avermaet H, Hens Z, Bayer M. Positive Trions in InP/ZnSe/ZnS Colloidal Nanocrystals. ACS NANO 2024; 18:9378-9388. [PMID: 38498768 DOI: 10.1021/acsnano.3c09971] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/20/2024]
Abstract
InP-based colloidal nanocrystals are being developed as an alternative to cadmium-based materials. However, their optical properties have not been widely studied. In this paper, the fundamental magneto-optical properties of InP/ZnSe/ZnS nanocrystals are investigated at cryogenic temperatures. Ensemble measurements using two-photon excitation spectroscopy revealed the band-edge hole state to have 1Sh symmetry, resolving some controversy on this issue. Single nanocrystal microphotoluminescence measurements provided increased spectral resolution that facilitated direct detection of the lowest energy confined acoustic phonon mode at 0.9 meV, which is several times smaller than the previously reported values for similar nanocrystals. Zeeman splitting of narrow spectral lines in a magnetic field indicated a bright trion emission. A simple trion model was used to identify a positive trion charge. Furthermore, the Zeeman split spectra allowed the direct measurement of both the electron and hole g-factors, which match existing theoretical predictions.
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Affiliation(s)
- Danil O Tolmachev
- Experimentelle Physik 2, Technische Universität Dortmund, 44227 Dortmund, Germany
| | - Mark J Fernée
- Experimentelle Physik 2, Technische Universität Dortmund, 44227 Dortmund, Germany
| | - Elena V Shornikova
- Experimentelle Physik 2, Technische Universität Dortmund, 44227 Dortmund, Germany
| | - Nikita V Siverin
- Experimentelle Physik 2, Technische Universität Dortmund, 44227 Dortmund, Germany
| | - Dmitri R Yakovlev
- Experimentelle Physik 2, Technische Universität Dortmund, 44227 Dortmund, Germany
| | - Hannes Van Avermaet
- Physics and Chemistry of Nanostructures, Ghent University, 9000 Ghent, Belgium
| | - Zeger Hens
- Physics and Chemistry of Nanostructures, Ghent University, 9000 Ghent, Belgium
| | - Manfred Bayer
- Experimentelle Physik 2, Technische Universität Dortmund, 44227 Dortmund, Germany
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2
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Li Y, Wang L, Xiang D, Zhu J, Wu K. Dielectric and Wavefunction Engineering of Electron Spin Lifetime in Colloidal Nanoplatelet Heterostructures. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2024; 11:e2306518. [PMID: 38234238 DOI: 10.1002/advs.202306518] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/10/2023] [Revised: 11/23/2023] [Indexed: 01/19/2024]
Abstract
Colloidal semiconductor nanoplatelets (NPLs) have emerged as low-cost and free-standing alternates of traditional quantum wells. The giant heavy- and light-hole splitting in NPLs allows for efficient optical spin injection. However, the electron spin lifetimes for prototypical CdSe NPLs are within a few picoseconds, likely limited by strong electron-hole exchange in these quantum- and dielectric-confined materials. Here how this hurdle can be overcome with engineered NPL-heterostructures is demonstrated. By constructing type-I CdSe/ZnS core/shell NPLs, dielectric screening inside the core is strongly enhanced, prolonging the electron spin polarization time (τesp) to over 30 ps (or 60 ps electron spin-flip time). Alternatively, by growing type-II CdSe/CdTe core/crown NPLs to spatially separate electron and hole wavefunctions, the electron-hole exchange is strongly suppressed, resulting in τesp as long as 300 ps at room temperature. This study not only exemplifies how the well-established synthetic chemistry of colloidal heterostructures can aid in spin dynamics control but also establishes the feasibility of room-temperature coherent spin manipulation in colloidal NPLs.
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Affiliation(s)
- Yulu Li
- State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, Liaoning, 116023, China
| | - Lifeng Wang
- State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, Liaoning, 116023, China
- University of the Chinese Academy of Sciences, Beijing, Hebei, 100049, China
| | - Dongmei Xiang
- State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, Liaoning, 116023, China
| | - Jingyi Zhu
- State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, Liaoning, 116023, China
| | - Kaifeng Wu
- State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, Liaoning, 116023, China
- University of the Chinese Academy of Sciences, Beijing, Hebei, 100049, China
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3
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Smirnova OO, Kalitukha IV, Rodina AV, Dimitriev GS, Sapega VF, Ken OS, Korenev VL, Kozyrev NV, Nekrasov SV, Kusrayev YG, Yakovlev DR, Dubertret B, Bayer M. Optical Alignment and Optical Orientation of Excitons in CdSe/CdS Colloidal Nanoplatelets. NANOMATERIALS (BASEL, SWITZERLAND) 2023; 13:2402. [PMID: 37686910 PMCID: PMC10489814 DOI: 10.3390/nano13172402] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2023] [Revised: 08/21/2023] [Accepted: 08/22/2023] [Indexed: 09/10/2023]
Abstract
Optical alignment and optical orientation of excitons are studied experimentally on an ensemble of core/shell CdSe/CdS colloidal nanoplatelets. Linear and circular polarization of photoluminescence during resonant excitation of excitons is measured at cryogenic temperatures and with magnetic fields applied in the Faraday geometry. The developed theory addresses the optical alignment and optical orientation of excitons in colloidal nanocrystals, taking into account both bright and dark exciton states in the presence of strong electron-hole exchange interaction and the random in-plane orientation of nanoplatelets within the ensemble. Our theoretical analysis of the obtained experimental data allows us to evaluate the exciton fine structure parameters, the g-factors, and the spin lifetimes of the bright and dark excitons. The optical alignment effect enables the identification of the exciton and trion contributions to the emission spectrum, even in the absence of their clear separation in the spectra.
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Affiliation(s)
- Olga O. Smirnova
- Ioffe Institute, Russian Academy of Sciences, 194021 St. Petersburg, Russia
| | - Ina V. Kalitukha
- Ioffe Institute, Russian Academy of Sciences, 194021 St. Petersburg, Russia
- Experimentelle Physik 2, Technische Universität Dortmund, 44221 Dortmund, Germany
| | - Anna V. Rodina
- Ioffe Institute, Russian Academy of Sciences, 194021 St. Petersburg, Russia
| | | | - Victor F. Sapega
- Ioffe Institute, Russian Academy of Sciences, 194021 St. Petersburg, Russia
| | - Olga S. Ken
- Ioffe Institute, Russian Academy of Sciences, 194021 St. Petersburg, Russia
| | | | - Nikolai V. Kozyrev
- Ioffe Institute, Russian Academy of Sciences, 194021 St. Petersburg, Russia
| | - Sergey V. Nekrasov
- Ioffe Institute, Russian Academy of Sciences, 194021 St. Petersburg, Russia
| | - Yuri G. Kusrayev
- Ioffe Institute, Russian Academy of Sciences, 194021 St. Petersburg, Russia
| | - Dmitri R. Yakovlev
- Ioffe Institute, Russian Academy of Sciences, 194021 St. Petersburg, Russia
- Experimentelle Physik 2, Technische Universität Dortmund, 44221 Dortmund, Germany
| | - Benoit Dubertret
- Laboratoire de Physique et d’Étude des Matériaux, ESPCI, CNRS, 75231 Paris, France
| | - Manfred Bayer
- Experimentelle Physik 2, Technische Universität Dortmund, 44221 Dortmund, Germany
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4
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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: 27] [Impact Index Per Article: 27.0] [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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5
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Qiang G, Zhukov EA, Evers E, Yakovlev DR, Golovatenko AA, Rodina AV, Onushchenko AA, Bayer M. Electron Spin Coherence in CdSe Nanocrystals in a Glass Matrix. ACS NANO 2022; 16:18838-18848. [PMID: 36317947 DOI: 10.1021/acsnano.2c07645] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
The coherent spin dynamics of electrons in CdSe nanocrystals embedded in a glass matrix with diameters from 3.3 up to 6.1 nm are investigated by time-resolved Faraday ellipticity at room and cryogenic temperatures. Only one Larmor precession frequency is detected, which corresponds to the larger of the two precession frequencies and thus g-factor values found in the typical signal from solution-grown colloidal CdSe nanocrystals. We identify this frequency accordingly as associated with the spin precession of resident electrons localized in the nanocrystals in the vicinity of the surface. We provide a detailed theoretical analysis of the exciton level spin structure in the magnetic field and model the spin dynamics in CdSe nanocrystals of different symmetries. This allows us to exclude the exciton as the origin of the experimentally observed oscillating signal. At a cryogenic temperature of 6 K, an additional nonoscillating component emerges in the spin dynamics. We consider several possible origins of this signal and conclude that it is related to the hole spin polarization.
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Affiliation(s)
- Gang Qiang
- Experimentelle Physik 2, Technische Universität Dortmund, 44221Dortmund, Germany
| | - Evgeny A Zhukov
- Ioffe Institute, Russian Academy of Sciences, 194021St. Petersburg, Russia
| | - Eiko Evers
- Experimentelle Physik 2, Technische Universität Dortmund, 44221Dortmund, Germany
| | - Dmitri R Yakovlev
- Experimentelle Physik 2, Technische Universität Dortmund, 44221Dortmund, Germany
- Ioffe Institute, Russian Academy of Sciences, 194021St. Petersburg, Russia
| | | | - Anna V Rodina
- Ioffe Institute, Russian Academy of Sciences, 194021St. Petersburg, Russia
| | | | - Manfred Bayer
- Experimentelle Physik 2, Technische Universität Dortmund, 44221Dortmund, Germany
- Ioffe Institute, Russian Academy of Sciences, 194021St. Petersburg, Russia
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6
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Transient quantum beatings of trions in hybrid organic tri-iodine perovskite single crystal. Nat Commun 2022; 13:1428. [PMID: 35301328 PMCID: PMC8931091 DOI: 10.1038/s41467-022-29053-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2021] [Accepted: 02/16/2022] [Indexed: 11/09/2022] Open
Abstract
Utilizing the spin degree of freedom of photoexcitations in hybrid organic inorganic perovskites for quantum information science applications has been recently proposed and explored. However, it is still unclear whether the stable photoexcitations in these compounds correspond to excitons, free/trapped electron-hole pairs, or charged exciton complexes such as trions. Here we investigate quantum beating oscillations in the picosecond time-resolved circularly polarized photoinduced reflection of single crystal methyl-ammonium tri-iodine perovskite (MAPbI3) measured at cryogenic temperatures. We observe two quantum beating oscillations (fast and slow) whose frequencies increase linearly with B with slopes that depend on the crystal orientation with respect to the applied magnetic field. We assign the quantum beatings to positive and negative trions whose Landé g-factors are determined by those of the electron and hole, respectively, or by the carriers left behind after trion recombination. These are \documentclass[12pt]{minimal}
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\begin{document}$${g}_{[001]}^{e}$$\end{document}g[001]e = 2.52 and \documentclass[12pt]{minimal}
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\begin{document}$${g}_{[1\bar{1}0]}^{e}\,$$\end{document}g[11¯0]e= 2.63 for electrons, whereas \documentclass[12pt]{minimal}
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\begin{document}$$\big|{g}_{[001]}^{h}\big|\,$$\end{document}g[001]h= 0.28 and \documentclass[12pt]{minimal}
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\begin{document}$$\big|{g}_{[1\bar{1}0]}^{h}\big|\,$$\end{document}g[11¯0]h= 0.57 for holes. The obtained g-values are in excellent agreement with an 8-band K.P calculation for orthorhombic MAPbI3. Using the technique of resonant spin amplification of the quantum beatings we measure a relatively long spin coherence time of ~ 11 (6) nanoseconds for electrons (holes) at 4 K. Understanding photo-physics giving rise to quantum beating oscillations in hybrid organic-inorganic perovskites aids their applications in spintronics and quantum information science. Here, authors demonstrate that quantum beatings observed in single crystal perovskite at cryogenic temperatures are originating from positive and negative trions.
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7
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Hu Z, Shu Y, Qin H, Hu X, Peng X. Water Effects on Colloidal Semiconductor Nanocrystals: Correlation of Photophysics and Photochemistry. J Am Chem Soc 2021; 143:18721-18732. [PMID: 34705444 DOI: 10.1021/jacs.1c09363] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
With high-quality CdSe/CdS core/shell nanocrystals as the main model system and under a controlled atmosphere, responses of photoexcited semiconductor nanocrystals to two active species (water and/or oxygen) in an ambient environment are studied systematically. Under photoexcitation, although high-quality semiconductor nanocrystals in either thin solid films or various solutions have a near-unity photoluminescence quantum yield, there is still a small probability (∼10-5 per photon absorbed) to be photoreduced by the water molecules efficiently accumulated in the highly hydrophilic nanocrystal-ligands interface. The resulting negatively charged nanocrystals are the starting point of most photophysical variations, and the hydroxyl radical─key photo-oxidation product of water─plays the main role for initiating various photochemical processes. Depending on the supplementation of water to the interface, accessibility to oxygen, photoirradiation power, type of matrices, type of measurement schemes, and solubility of nanocrystals in the solution, various photophysical/photochemical phenomena─either reported or not reported in the literature─are reproducibly observed. Results confirm that photophysical properties and photochemical reactions can be well-correlated, offering a unified and unique basis for fundamental studies and the design of processing techniques in industry.
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Affiliation(s)
- Zhuang Hu
- Key Laboratory of Excited-State Materials of Zhejiang Province and Department of Chemistry, Zhejiang University, Hangzhou 310027, China
| | - Yufei Shu
- Key Laboratory of Excited-State Materials of Zhejiang Province and Department of Chemistry, Zhejiang University, Hangzhou 310027, China
| | - Haiyan Qin
- Key Laboratory of Excited-State Materials of Zhejiang Province and Department of Chemistry, Zhejiang University, Hangzhou 310027, China
| | - Xiaofei Hu
- Key Laboratory of Excited-State Materials of Zhejiang Province and Department of Chemistry, Zhejiang University, Hangzhou 310027, China
| | - Xiaogang Peng
- Key Laboratory of Excited-State Materials of Zhejiang Province and Department of Chemistry, Zhejiang University, Hangzhou 310027, China
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8
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Lorenz S, Bieniek J, Erickson CS, Gamelin DR, Fainblat R, Bacher G. Orientation of Individual Anisotropic Nanocrystals Identified by Polarization Fingerprint. ACS NANO 2021; 15:13579-13590. [PMID: 34339182 DOI: 10.1021/acsnano.1c04451] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
The polarization of photoluminescence emitted from anisotropic nanocrystals directly reflects the symmetry of the eigenstates involved in the recombination process and can thus be considered as a characteristic feature of a nanocrystal. We performed polarization resolved magneto-photoluminescence spectroscopy on single colloidal Mn2+:CdSe/CdS core-shell quantum dots of wurtzite crystal symmetry. At zero magnetic field, a distinct linear polarization pattern is observed, while applying a magnetic field enforces circularly polarized emission with a characteristic saturation value below 100%. These polarization features are shown to act as a specific fingerprint of each individual nanocrystal. A model considering the orientation of the crystal c⃗ axis with respect to the optical axis and the magnetic field and taking into account the impact of magnetic doping is introduced and quantitatively explains our findings. We demonstrate that a careful analysis of the polarization state of single nanocrystal emission using the full set of Stokes parameters allows for identification of the complete three-dimensional orientation of the crystal anisotropy axis of an individual nanoobject in lab coordinates.
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Affiliation(s)
- Severin Lorenz
- Werkstoffe der Elektrotechnik and CENIDE, University of Duisburg-Essen, Bismarckstr. 81, Duisburg 47057 Germany
| | - Jan Bieniek
- Werkstoffe der Elektrotechnik and CENIDE, University of Duisburg-Essen, Bismarckstr. 81, Duisburg 47057 Germany
| | - Christian S Erickson
- Department of Chemistry, University of Washington, Seattle, Washington 98195-1700, United States
| | - Daniel R Gamelin
- Department of Chemistry, University of Washington, Seattle, Washington 98195-1700, United States
| | - Rachel Fainblat
- Werkstoffe der Elektrotechnik and CENIDE, University of Duisburg-Essen, Bismarckstr. 81, Duisburg 47057 Germany
| | - Gerd Bacher
- Werkstoffe der Elektrotechnik and CENIDE, University of Duisburg-Essen, Bismarckstr. 81, Duisburg 47057 Germany
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9
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Carulli F, Pinchetti V, Zaffalon ML, Camellini A, Rotta Loria S, Moro F, Fanciulli M, Zavelani-Rossi M, Meinardi F, Crooker SA, Brovelli S. Optical and Magneto-Optical Properties of Donor-Bound Excitons in Vacancy-Engineered Colloidal Nanocrystals. NANO LETTERS 2021; 21:6211-6219. [PMID: 34260252 PMCID: PMC8397387 DOI: 10.1021/acs.nanolett.1c01818] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/20/2021] [Revised: 06/30/2021] [Indexed: 06/13/2023]
Abstract
Controlled insertion of electronic states within the band gap of semiconductor nanocrystals (NCs) is a powerful tool for tuning their physical properties. One compelling example is II-VI NCs incorporating heterovalent coinage metals in which hole capture produces acceptor-bound excitons. To date, the opposite donor-bound exciton scheme has not been realized because of the unavailability of suitable donor dopants. Here, we produce a model system for donor-bound excitons in CdSeS NCs engineered with sulfur vacancies (VS) that introduce a donor state below the conduction band (CB), resulting in long-lived intragap luminescence. VS-localized electrons are almost unaffected by trapping, and suppression of thermal quenching boosts the emission efficiency to 85%. Magneto-optical measurements indicate that the VS are not magnetically coupled to the NC bands and that the polarization properties are determined by the spin of the valence-band photohole, whose spin flip is massively slowed down due to suppressed exchange interaction with the donor-localized electron.
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Affiliation(s)
- Francesco Carulli
- Dipartimento
di Scienza dei Materiali, Università
degli Studi di Milano-Bicocca, via Cozzi 55, IT-20125 Milano, Italy
| | - Valerio Pinchetti
- Dipartimento
di Scienza dei Materiali, Università
degli Studi di Milano-Bicocca, via Cozzi 55, IT-20125 Milano, Italy
| | - Matteo L. Zaffalon
- Dipartimento
di Scienza dei Materiali, Università
degli Studi di Milano-Bicocca, via Cozzi 55, IT-20125 Milano, Italy
| | - Andrea Camellini
- Dipartimento
di Energia, Politecnico di Milano, IT-20133 Milano, Italy
| | | | - Fabrizio Moro
- Dipartimento
di Scienza dei Materiali, Università
degli Studi di Milano-Bicocca, via Cozzi 55, IT-20125 Milano, Italy
| | - Marco Fanciulli
- Dipartimento
di Scienza dei Materiali, Università
degli Studi di Milano-Bicocca, via Cozzi 55, IT-20125 Milano, Italy
| | | | - Francesco Meinardi
- Dipartimento
di Scienza dei Materiali, Università
degli Studi di Milano-Bicocca, via Cozzi 55, IT-20125 Milano, Italy
| | - Scott A. Crooker
- National
High Magnetic Field Laboratory, Los Alamos
National Laboratory, Los Alamos, New Mexico 87545, United States
| | - Sergio Brovelli
- Dipartimento
di Scienza dei Materiali, Università
degli Studi di Milano-Bicocca, via Cozzi 55, IT-20125 Milano, Italy
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10
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Najafi A, Sharma M, Delikanli S, Bhattacharya A, Murphy JR, Pientka J, Sharma A, Quinn AP, Erdem O, Kattel S, Kelestemur Y, Kovalenko MV, Rice WD, Demir HV, Petrou A. Light-Induced Paramagnetism in Colloidal Ag +-Doped CdSe Nanoplatelets. J Phys Chem Lett 2021; 12:2892-2899. [PMID: 33724845 DOI: 10.1021/acs.jpclett.1c00398] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
We describe a study of the magneto-optical properties of Ag+-doped CdSe colloidal nanoplatelets (NPLs) that were grown using a novel doping technique. In this work, we used magnetic circularly polarized luminescence and magnetic circular dichroism spectroscopy to study light-induced magnetism for the first time in 2D solution-processed structures doped with nominally nonmagnetic Ag+ impurities. The excitonic circular polarization (PX) and the exciton Zeeman splitting (ΔEZ) were recorded as a function of the magnetic field (B) and temperature (T). Both ΔEZ and PX have a Brillouin-function-like dependence on B and T, verifying the presence of paramagnetism in Ag+-doped CdSe NPLs. The observed light-induced magnetism is attributed to the transformation of nonmagnetic Ag+ ions into Ag2+, which have a nonzero magnetic moment. This work points to the possibility of incorporating these nanoplatelets into spintronic devices, in which light can be used to control the spin injection.
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Affiliation(s)
- Arman Najafi
- Department of Physics, University at Buffalo SUNY, Buffalo, New York 14260, United States
| | - Manoj Sharma
- Luminous! Centre of Excellence for Semiconductor Lighting and Displays, School of Electrical and Electronic Engineering and Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 639798
- Department of Electrical and Electronics Engineering and Department of Physics, UNAM-Institute of Materials Science and Nanotechnology, Bilkent University, 06800 Ankara, Turkey
| | - Savas Delikanli
- Luminous! Centre of Excellence for Semiconductor Lighting and Displays, School of Electrical and Electronic Engineering and Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 639798
- Department of Electrical and Electronics Engineering and Department of Physics, UNAM-Institute of Materials Science and Nanotechnology, Bilkent University, 06800 Ankara, Turkey
| | - Arinjoy Bhattacharya
- Department of Physics, University at Buffalo SUNY, Buffalo, New York 14260, United States
| | - Joseph R Murphy
- Department of Chemistry and Physics, Southeast Missouri State University, Cape Girardeau, Missouri 63701, United States
- Department of Physics and Astronomy, University of Wyoming, Laramie, Wyoming 82071, United States
| | - James Pientka
- Department of Physics, St. Bonaventure University, St. Bonaventure, New York 14778, United States
| | - Ashma Sharma
- Luminous! Centre of Excellence for Semiconductor Lighting and Displays, School of Electrical and Electronic Engineering and Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 639798
| | - Alexander P Quinn
- Department of Physics, University at Buffalo SUNY, Buffalo, New York 14260, United States
| | - Onur Erdem
- Department of Electrical and Electronics Engineering and Department of Physics, UNAM-Institute of Materials Science and Nanotechnology, Bilkent University, 06800 Ankara, Turkey
| | - Subash Kattel
- Department of Physics and Astronomy, University of Wyoming, Laramie, Wyoming 82071, United States
| | - Yusuf Kelestemur
- Department of Chemistry and Applied Biosciences, ETH Zürich, Vladimir Prelog Weg 1, CH-8093 Zürich, Switzerland
- Department of Metallurgical and Materials Engineering, Atilim University, Ankara 06830, Turkey
| | - Maksym V Kovalenko
- Department of Chemistry and Applied Biosciences, ETH Zürich, Vladimir Prelog Weg 1, CH-8093 Zürich, Switzerland
- Empa-Swiss Federal Laboratories for Materials Science and Technology, Überlandstrasse 129, CH-8600 Dübendorf, Switzerland
| | - William D Rice
- Department of Physics and Astronomy, University of Wyoming, Laramie, Wyoming 82071, United States
| | - Hilmi Volkan Demir
- Luminous! Centre of Excellence for Semiconductor Lighting and Displays, School of Electrical and Electronic Engineering and Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 639798
- Department of Electrical and Electronics Engineering and Department of Physics, UNAM-Institute of Materials Science and Nanotechnology, Bilkent University, 06800 Ankara, Turkey
| | - Athos Petrou
- Department of Physics, University at Buffalo SUNY, Buffalo, New York 14260, United States
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11
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Wu Z, Zhang Y, Hu R, Jiang M, Liang P, Yang Q, Deng L, Jia T, Sun Z, Feng D. Hole-Acceptor-Manipulated Electron Spin Dynamics in CdSe Colloidal Quantum Dots. J Phys Chem Lett 2021; 12:2126-2132. [PMID: 33625852 DOI: 10.1021/acs.jpclett.0c03669] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Electron spin dynamics in CdSe quantum dots with hole acceptors are investigated by time-resolved ellipticity spectroscopy. Two types of hole acceptors, Li[Et3BH] and 1-octanethiol, result in distinctly different electron spin dynamics. The differences include electron g factors, spin dephasing/relaxation times, and mechanisms. In CdSe quantum dots with Li[Et3BH], the electron spin dephasing and relaxation are dominated by electron-nuclear hyperfine interactions in zero and weak magnetic fields. In contrast, hyperfine interactions, electron carrier lifetimes, and exchange interactions between electrons and holes or surface dangling bond spins control the electron spin dynamics in CdSe quantum dots with 1-octanethiol. Inhomogeneous dephasing limits the spin coherence time in larger transverse magnetic fields for both hole acceptor cases, but with distinct different g-factor inhomogeneity. These findings manifest that surface conditions play an important role in the spin dynamics and that thereby the surface and its surroundings can be exploited to control the spin in colloidal nanostructures.
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Affiliation(s)
- Zhen Wu
- State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200241, China
| | - Yuanyuan Zhang
- State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200241, China
| | - Rongrong Hu
- College of Sciences, Shanghai Institute of Technology, Shanghai 201418, China
| | - Meizhen Jiang
- State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200241, China
| | - Pan Liang
- College of Arts and Sciences, Shanghai Dianji University, Shanghai 201306, China
| | - Qing Yang
- State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200241, China
| | - Li Deng
- School of Physics & Electronic Science, East China Normal University, Shanghai 200241, China
| | - Tianqing Jia
- State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200241, China
| | - Zhenrong Sun
- State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200241, China
| | - Donghai Feng
- State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200241, China
- Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan, Shanxi 030006, China
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12
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Xiang D, Li Y, Wang L, Ding T, Wang J, Wu K. Electron and Hole Spin Relaxation in CdSe Colloidal Nanoplatelets. J Phys Chem Lett 2021; 12:86-93. [PMID: 33306386 DOI: 10.1021/acs.jpclett.0c03257] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Solution-processed quantum-confined nanocrystals are important building blocks for scalable implementation of quantum information science. Extensive studies on colloidal quantum dots (QDs) have revealed subpicosecond hole spin relaxation, whereas the electron spin dynamics remains difficult to probe. Here we study electron and hole spin dynamics in CdSe colloidal nanoplatelets (also called quantum wells) of varying thicknesses using circularly polarized transient absorption spectroscopy at room temperature. The clear spectroscopic features of transition bands associated with heavy, light, and spin-orbit split-off holes enabled separate probes of electron and hole dynamics. The hole spin-flip occurred within ∼200 fs, arising from strong spin-orbit coupling in the valence band. The electron spin lifetime decreased from 6.2 to 2.2 ps as the platelet thickness is reduced from 6 to 4 monolayers, reflecting an exchange interaction between the electron and the hole and/or surface dangling bond spins enhanced by quantum confinement.
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Affiliation(s)
- 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, Liaoning 116023, China
| | - Yulu Li
- 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, Liaoning 116023, China
| | - 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, Liaoning 116023, China
- University of the Chinese Academy of Sciences, Beijing 100049, China
| | - Tao Ding
- 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, Liaoning 116023, 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, Liaoning 116023, 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, Liaoning 116023, China
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13
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Li C, Hsu SC, Lin JX, Chen JY, Chuang KC, Chang YP, Hsu HS, Chen CH, Lin TS, Liu YH. Giant Zeeman Splitting for Monolayer Nanosheets at Room Temperature. J Am Chem Soc 2020; 142:20616-20623. [PMID: 33249824 DOI: 10.1021/jacs.0c05368] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Giant Zeeman splitting and zero-field splitting (ZFS) are observed in 2D nanosheets that have monolayers of atomic thickness. In this study, single-crystalline CdSe(ethylenediamine)0.5 and Mn2+-doped nanosheets are synthesized via a solvothermal process. Tunable amounts of Mn2+(0.5-8.0%) are introduced, resulting in lattice contraction as well as phosphorescence from five unpaired electrons. The exciton dynamics are dominated by spin-related electronic transitions (4T1 → 6A1) with long lifetimes (20.5, 132, and 295 μs). Temperature-varied EPR spectroscopy with spectral simulation reveals large ZFS (D = 3850 MHz) due to axial distortion of substituted Mn2+ (S = 5/2). In the magnetic circular dichroism (MCD) measurements, we observed giant Zeeman splitting with large effective g values (up to 231 ± 21), which implies huge sp-d exchange interactions in 2D monolayer regimes, leading to diluted magnetic semiconductor (DMS) materials.
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Affiliation(s)
- Chi Li
- Department of Chemistry, National Taiwan Normal University, Taipei 11677, Taiwan, ROC
| | - Sheng-Chih Hsu
- Department of Chemistry, National Taiwan Normal University, Taipei 11677, Taiwan, ROC
| | - Jun-Xiao Lin
- Department of Applied Physics, National Pingtung University, Pingtung 90003, Taiwan, ROC
| | - Jou-Yun Chen
- Department of Chemistry, National Sun Yat-Sen University, Kaohsiung 80424, Taiwan, ROC
| | - Kai-Chun Chuang
- Department of Chemistry, National Taiwan Normal University, Taipei 11677, Taiwan, ROC
| | - Yuan-Pin Chang
- Department of Chemistry, National Sun Yat-Sen University, Kaohsiung 80424, Taiwan, ROC
| | - Hua-Shu Hsu
- Department of Applied Physics, National Pingtung University, Pingtung 90003, Taiwan, ROC
| | - Ching-Hsiang Chen
- Graduate Institute of Applied Science and Technology, National Taiwan University of Science & Technology, Taipei 10673, Taiwan, ROC
| | - Tien-Sung Lin
- Department of Chemistry, Washington University, Saint Louis, Missouri 63130, United States
| | - Yi-Hsin Liu
- Department of Chemistry, National Taiwan Normal University, Taipei 11677, Taiwan, ROC
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14
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Achtstein AW, Ayari S, Helmrich S, Quick MT, Owschimikow N, Jaziri S, Woggon U. Tuning exciton diffusion, mobility and emission line width in CdSe nanoplatelets via lateral size. NANOSCALE 2020; 12:23521-23531. [PMID: 33225335 DOI: 10.1039/d0nr04745g] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
We investigate the lateral size tunability of the exciton diffusion coefficient and mobility in colloidal quantum wells by means of line width analysis and theoretical modeling. We show that the exciton diffusion coefficient and mobility in laterally finite 2D systems like CdSe nanoplatelets can be tuned via the lateral size and aspect ratio. The coupling to acoustic and optical phonons can be altered via the lateral size and aspect ratio of the platelets. Subsequently the exciton diffusion and mobility become tunable since these phonon scattering processes determine and limit the mobility. At 4 K the exciton mobility increases from ∼ 4 × 103 cm2 V-1 s-1 to more than 1.4 × 104 cm2 V-1 s-1 for large platelets, while there are weaker changes with size and the mobility is around 8 × 101 cm2 V-1 s-1 for large platelets at room temperature. In turn at 4 K the exciton diffusion coefficient increases with the lateral size from ∼ 1.3 cm2 s-1 to ∼ 5 cm2 s-1, while it is around half the value for large platelets at room temperature. Our experimental results are in good agreement with theoretical modeling, showing a lateral size and aspect ratio dependence. The findings open up the possibility for materials with tunable exciton mobility, diffusion or emission line width, but quasi constant transition energy. High exciton mobility is desirable e.g. for solar cells and allows efficient excitation harvesting and extraction.
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Affiliation(s)
- Alexander W Achtstein
- Institute of Optics and Atomic Physics, Technische Universität Berlin, Strasse des 17. Juni 135, 10623 Berlin, Germany.
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15
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Tolmachev DO, Ivanov VY, Yakovlev DR, Shornikova EV, Witkowski B, Shendre S, Isik F, Delikani S, Demir HV, Bayer M. Optically detected magnetic resonance in CdSe/CdMnS nanoplatelets. NANOSCALE 2020; 12:21932-21939. [PMID: 33112343 DOI: 10.1039/d0nr05633b] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Core/shell CdSe/(Cd,Mn)S colloidal nanoplatelets containing magnetic Mn2+ ions are investigated by the optically detected magnetic resonance technique, combining 60 GHz microwave excitation and photoluminescence detection. Resonant heating of the Mn spin system is observed. We identify two mechanisms of optical detection, via variation of either the photoluminescence polarization or its intensity in an external magnetic field. The spin-lattice relaxation dynamics of the Mn spin system is measured and used for evaluation of the Mn concentration. In CdSe/(Cd,Zn,Mn)S nanoplatelets the addition of Zn in the shells significantly broadens the magnetic resonance, evidencing local strain.
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Affiliation(s)
- Danil O Tolmachev
- Experimentelle Physik 2, Technische Universität Dortmund, 44227 Dortmund, Germany.
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16
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Shornikova EV, Yakovlev DR, Tolmachev DO, Ivanov VY, Kalitukha IV, Sapega VF, Kudlacik D, Kusrayev YG, Golovatenko AA, Shendre S, Delikanli S, Demir HV, Bayer M. Magneto-Optics of Excitons Interacting with Magnetic Ions in CdSe/CdMnS Colloidal Nanoplatelets. ACS NANO 2020; 14:9032-9041. [PMID: 32585089 DOI: 10.1021/acsnano.0c04048] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Excitons in diluted magnetic semiconductors represent excellent probes for studying the magnetic properties of these materials. Various magneto-optical effects, which depend sensitively on the exchange interaction of the excitons with the localized spins of the magnetic ions can be used for probing. Here, we study core/shell CdSe/(Cd,Mn)S colloidal nanoplatelets hosting diluted magnetic semiconductor layers. The inclusion of the magnetic Mn2+ ions is evidenced by three magneto-optical techniques using high magnetic fields up to 15 T: polarized photoluminescence, optically detected magnetic resonance, and spin-flip Raman scattering. We show that the holes in the excitons play the dominant role in exchange interaction with magnetic ions. We suggest and test an approach for evaluation of the Mn2+ concentration based on the spin-lattice relaxation dynamics of the Mn2+ spin system.
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Affiliation(s)
- Elena V Shornikova
- Experimentelle Physik 2, Technische Universität Dortmund, 44227 Dortmund, Germany
| | - Dmitri R Yakovlev
- Experimentelle Physik 2, Technische Universität Dortmund, 44227 Dortmund, Germany
- Ioffe Institute, Russian Academy of Sciences, 194021 St. Petersburg, Russia
| | - Danil O Tolmachev
- Experimentelle Physik 2, Technische Universität Dortmund, 44227 Dortmund, Germany
- Ioffe Institute, Russian Academy of Sciences, 194021 St. Petersburg, Russia
| | - Vitalii Yu Ivanov
- Institute of Physics, Polish Academy of Sciences, PL-02-668 Warsaw, Poland
| | - Ina V Kalitukha
- Ioffe Institute, Russian Academy of Sciences, 194021 St. Petersburg, Russia
| | - Victor F Sapega
- Ioffe Institute, Russian Academy of Sciences, 194021 St. Petersburg, Russia
| | - Dennis Kudlacik
- Experimentelle Physik 2, Technische Universität Dortmund, 44227 Dortmund, Germany
| | - Yuri G Kusrayev
- Ioffe Institute, Russian Academy of Sciences, 194021 St. Petersburg, Russia
| | | | - Sushant Shendre
- LUMINOUS! Center of Excellence for Semiconductor Lighting and Displays, School of Electrical and Electronic Engineering, School of Physical and Materials Sciences, Nanyang Technological University, 639798 Singapore
| | - Savas Delikanli
- LUMINOUS! Center of Excellence for Semiconductor Lighting and Displays, School of Electrical and Electronic Engineering, School of Physical and Materials Sciences, Nanyang Technological University, 639798 Singapore
- Department of Electrical and Electronics Engineering, Department of Physics, UNAM - Institute of Materials Science and Nanotechnology, Bilkent University, 06800 Ankara, Turkey
| | - Hilmi Volkan Demir
- LUMINOUS! Center of Excellence for Semiconductor Lighting and Displays, School of Electrical and Electronic Engineering, School of Physical and Materials Sciences, Nanyang Technological University, 639798 Singapore
- Department of Electrical and Electronics Engineering, Department of Physics, UNAM - Institute of Materials Science and Nanotechnology, Bilkent University, 06800 Ankara, Turkey
| | - Manfred Bayer
- Experimentelle Physik 2, Technische Universität Dortmund, 44227 Dortmund, Germany
- Ioffe Institute, Russian Academy of Sciences, 194021 St. Petersburg, Russia
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17
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Ayari S, Quick MT, Owschimikow N, Christodoulou S, Bertrand GHV, Artemyev M, Moreels I, Woggon U, Jaziri S, Achtstein AW. Tuning trion binding energy and oscillator strength in a laterally finite 2D system: CdSe nanoplatelets as a model system for trion properties. NANOSCALE 2020; 12:14448-14458. [PMID: 32618327 DOI: 10.1039/d0nr03170d] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
We present a theoretical study combined with experimental validations demonstrating that CdSe nanoplatelets are a model system to investigate the tunability of trions and excitons in laterally finite 2D semiconductors. Our results show that the trion binding energy can be tuned from 36 meV to 18 meV with the lateral size and decreasing aspect ratio, while the oscillator strength ratio of trions to excitons decreases. In contrast to conventional quantum dots, the trion oscillator strength in a nanoplatelet at low temperature is smaller than that of the exciton. The trion and exciton Bohr radii become lateral size tunable, e.g. from ∼3.5 to 4.8 nm for the trion. We show that dielectric screening has strong impact on these properties. By theoretical modeling of transition energies, binding energies and oscillator strength of trions and excitons and comparison with experimental findings, we demonstrate that these properties are lateral size and aspect ratio tunable and can be engineered by dielectric confinement, allowing to suppress e.g. detrimental trion emission in devices. Our results strongly impact further in-depth studies, as the demonstrated lateral size tunable trion and exciton manifold is expected to influence properties like gain mechanisms, lasing, quantum efficiency and transport even at room temperature due to the high and tunable trion binding energies.
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Affiliation(s)
- Sabrine Ayari
- Laboratoire de Physique des Materiaux, Faculte des Sciences de Bizerte, Universite de Carthage, Jarzouna 7021, Tunisia
| | - Michael T Quick
- Institute of Optics and Atomic Physics, Technische Universität Berlin, Strasse des 17. Juni 135, 10623 Berlin, Germany.
| | - Nina Owschimikow
- Institute of Optics and Atomic Physics, Technische Universität Berlin, Strasse des 17. Juni 135, 10623 Berlin, Germany.
| | | | | | - Mikhail Artemyev
- Research Institute for Physical Chemical Problems of Belarusian State University, 220006 Minsk, Belarus
| | - Iwan Moreels
- Department of Chemistry, Ghent University, Krijgslaan 281 - S3, 9000 Gent, Belgium
| | - Ulrike Woggon
- Institute of Optics and Atomic Physics, Technische Universität Berlin, Strasse des 17. Juni 135, 10623 Berlin, Germany.
| | - Sihem Jaziri
- Laboratoire de Physique des Materiaux, Faculte des Sciences de Bizerte, Universite de Carthage, Jarzouna 7021, Tunisia and Laboratoire de Physique de la Matiere Condensee, Departement de Physique, Faculte des Sciences de Tunis, Campus Universitaire, 1060 Tunis, Tunisia
| | - Alexander W Achtstein
- Institute of Optics and Atomic Physics, Technische Universität Berlin, Strasse des 17. Juni 135, 10623 Berlin, Germany.
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18
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Feng D, Yakovlev DR, Dubertret B, Bayer M. Charge Separation Dynamics in CdSe/CdS Core/Shell Nanoplatelets Addressed by Coherent Electron Spin Precession. ACS NANO 2020; 14:7237-7244. [PMID: 32453553 DOI: 10.1021/acsnano.0c02402] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
We investigate the charge separation dynamics provided by carrier surface trapping in CdSe/CdS core/shell nanoplatelets by means of a three-laser-beam pump-orientation-probe technique, detecting the electron spin coherence at room temperature. Signals with two Larmor precession frequencies are found, which strongly differ in their dynamical characteristics and dependencies on pump power and shell thickness. The electron trapping process occurs on a time scale of about 10 ns, and the charge separation induced thereby has a long lifetime of up to hundreds of microseconds. On the other hand, the hole trapping requires times from subpicoseconds to hundreds of picoseconds, and the induced charge separation has a lifetime of a few nanoseconds. With increasing CdS shell thickness the hole trapping vanishes, while the electron trapping is still detectable. These findings have important implications for understanding the photophysical processes of nanoplatelets and other colloidal nanostructures.
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Affiliation(s)
- Donghai Feng
- State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200062, China
| | - Dmitri R Yakovlev
- Experimentelle Physik 2, Technische Universität Dortmund, 44221 Dortmund, Germany
- Ioffe Institute, Russian Academy of Sciences, 194021 St. Petersburg, Russia
| | - 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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19
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Vovk IA, Lobanov VV, Litvin AP, Leonov MY, Fedorov AV, Rukhlenko ID. Band Structure and Intersubband Transitions of Three-Layer Semiconductor Nanoplatelets. NANOMATERIALS (BASEL, SWITZERLAND) 2020; 10:nano10050933. [PMID: 32408535 PMCID: PMC7279220 DOI: 10.3390/nano10050933] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/27/2020] [Revised: 04/29/2020] [Accepted: 05/07/2020] [Indexed: 06/11/2023]
Abstract
This paper presents the first general theory of electronic band structure and intersubband transitions in three-layer semiconductor nanoplatelets. We find a dispersion relation and wave functions of the confined electrons and use them to analyze the band structure of core/shell nanoplatelets with equal thicknesses of the shell layers. It is shown that the energies of electrons localized inside the shell layers can be degenerate for certain electron wave vectors and certain core and shell thicknesses. We also show that the energies of intersubband transitions can be nonmonotonic functions of the core and shell thicknesses, exhibiting pronounced local minima and maxima which can be observed in the infrared absorption spectra. Our results will prove useful for the design of photonic devices based on multilayered semiconductor nanoplatelets operating at infrared frequencies.
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Affiliation(s)
- Ilia A. Vovk
- ITMO University, Center of Information Optical Technology, Saint Petersburg 197101, Russia; (I.A.V.); (V.V.L.); (A.P.L.); (M.Y.L.); (A.V.F.)
| | - Vladimir V. Lobanov
- ITMO University, Center of Information Optical Technology, Saint Petersburg 197101, Russia; (I.A.V.); (V.V.L.); (A.P.L.); (M.Y.L.); (A.V.F.)
| | - Aleksandr P. Litvin
- ITMO University, Center of Information Optical Technology, Saint Petersburg 197101, Russia; (I.A.V.); (V.V.L.); (A.P.L.); (M.Y.L.); (A.V.F.)
| | - Mikhail Yu. Leonov
- ITMO University, Center of Information Optical Technology, Saint Petersburg 197101, Russia; (I.A.V.); (V.V.L.); (A.P.L.); (M.Y.L.); (A.V.F.)
| | - Anatoly V. Fedorov
- ITMO University, Center of Information Optical Technology, Saint Petersburg 197101, Russia; (I.A.V.); (V.V.L.); (A.P.L.); (M.Y.L.); (A.V.F.)
| | - Ivan D. Rukhlenko
- The University of Sydney, Institute of Photonics and Optical Science (IPOS), School of Physics, Camperdown, NSW 2006, Australia
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20
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Shornikova EV, Golovatenko AA, Yakovlev DR, Rodina AV, Biadala L, Qiang G, Kuntzmann A, Nasilowski M, Dubertret B, Polovitsyn A, Moreels I, Bayer M. Surface spin magnetism controls the polarized exciton emission from CdSe nanoplatelets. NATURE NANOTECHNOLOGY 2020; 15:277-282. [PMID: 31988504 DOI: 10.1038/s41565-019-0631-7] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/08/2019] [Accepted: 12/18/2019] [Indexed: 06/10/2023]
Abstract
The surface of nominally diamagnetic colloidal CdSe nanoplatelets can demonstrate paramagnetic behaviour owing to the uncompensated spins of dangling bonds, as we reveal here by optical spectroscopy in high magnetic fields up to 15 T using the exciton spin as a probe of the surface magnetism. The strongly nonlinear magnetic field dependence of the circular polarization of the exciton emission is determined by the magnetization of the dangling-bond spins (DBSs), the exciton spin polarization as well as the spin-dependent recombination of dark excitons. The sign of the exciton-DBS exchange interaction depends on the nanoplatelet growth conditions.
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Affiliation(s)
- Elena V Shornikova
- Experimentelle Physik 2, Technische Universität Dortmund, Dortmund, Germany.
| | | | - Dmitri R Yakovlev
- Experimentelle Physik 2, Technische Universität Dortmund, Dortmund, Germany.
- Ioffe Institute, Russian Academy of Sciences, St. Petersburg, Russia.
| | - Anna V Rodina
- Ioffe Institute, Russian Academy of Sciences, St. Petersburg, Russia.
| | - Louis Biadala
- Institut d'Electronique, de Microélectronique et de Nanotechnologie, CNRS, Villeneuve-d'Ascq, France
| | - Gang Qiang
- Experimentelle Physik 2, Technische Universität Dortmund, Dortmund, Germany
| | - Alexis Kuntzmann
- Laboratoire de Physique et d'Etude des Matériaux, ESPCI, CNRS, Paris, France
| | - Michel Nasilowski
- Laboratoire de Physique et d'Etude des Matériaux, ESPCI, CNRS, Paris, France
| | - Benoit Dubertret
- Laboratoire de Physique et d'Etude des Matériaux, ESPCI, CNRS, Paris, France
| | - Anatolii Polovitsyn
- Department of Chemistry, Ghent University, Ghent, Belgium
- Istituto Italiano di Tecnologia, Genova, Italy
| | - Iwan Moreels
- Department of Chemistry, Ghent University, Ghent, Belgium
- Istituto Italiano di Tecnologia, Genova, Italy
| | - Manfred Bayer
- Experimentelle Physik 2, Technische Universität Dortmund, Dortmund, Germany
- Ioffe Institute, Russian Academy of Sciences, St. Petersburg, Russia
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21
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Shornikova EV, Yakovlev DR, Biadala L, Crooker SA, Belykh VV, Kochiev MV, Kuntzmann A, Nasilowski M, Dubertret B, Bayer M. Negatively Charged Excitons in CdSe Nanoplatelets. NANO LETTERS 2020; 20:1370-1377. [PMID: 31960677 DOI: 10.1021/acs.nanolett.9b04907] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The low-temperature emission spectrum of CdSe colloidal nanoplatelets (NPLs) consists of two narrow lines. The high-energy line stems from the recombination of neutral excitons. The origin of the low-energy line is currently debated. We experimentally study the spectral shift, emission dynamics, and spin polarization of both lines at low temperatures down to 1.5 K and in high magnetic fields up to 60 T and show that the low-energy line originates from the recombination of negatively charged excitons (trions). This assignment is confirmed by the NPL photocharging dynamics and associated variations in the spectrum. We show that the negatively charged excitons are considerably less sensitive to the presence of surface spins than the neutral excitons. The trion binding energy in three-monolayer-thick NPLs is as large as 30 meV, which is 4 times larger than its value in the two-dimensional limit of a conventional CdSe quantum well confined between semiconductor barriers. A considerable part of this enhancement is gained by the dielectric enhancement effect, which is due to the small dielectric constant of the environment surrounding the NPLs.
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Affiliation(s)
- Elena V Shornikova
- 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
| | - Louis Biadala
- Institut d'Electronique, de Microélectronique et de Nanotechnologie, CNRS , 59652 Villeneuve-d'Ascq , France
| | - Scott A Crooker
- National High Magnetic Field Laboratory , Los Alamos National Laboratory , Los Alamos , 87545 New Mexico , United States
| | - Vasilii V Belykh
- P. N. Lebedev Physical Institute, Russian Academy of Sciences , 119991 Moscow , Russia
| | - Mikhail V Kochiev
- P. N. Lebedev Physical Institute, Russian Academy of Sciences , 119991 Moscow , Russia
| | - Alexis Kuntzmann
- Laboratoire de Physique et d'Etude des Matériaux , ESPCI, CNRS , 75231 Paris , France
| | - 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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22
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Kudlacik D, Sapega VF, Yakovlev DR, Kalitukha IV, Shornikova EV, Rodina AV, Ivchenko EL, Dimitriev GS, Nasilowski M, Dubertret B, Bayer M. Single and Double Electron Spin-Flip Raman Scattering in CdSe Colloidal Nanoplatelets. NANO LETTERS 2020; 20:517-525. [PMID: 31825228 DOI: 10.1021/acs.nanolett.9b04262] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
CdSe colloidal nanoplatelets are studied by spin-flip Raman scattering in magnetic fields up to 5 T. We find pronounced Raman lines shifted from the excitation laser energy by an electron Zeeman splitting. Their polarization selection rules correspond to those expected for scattering mediated by excitons interacting with resident electrons. Surprisingly, Raman signals shifted by twice the electron Zeeman splitting are also observed. The theoretical analysis and experimental dependences show that the mechanism responsible for the double flip involves two resident electrons interacting with a photoexcited exciton. Effects related to various orientations of the nanoplatelets in the ensemble and different orientations of the magnetic field are analyzed.
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Affiliation(s)
- Dennis Kudlacik
- Experimentelle Physik 2 , Technische Universität Dortmund , 44227 Dortmund , Germany
| | - Victor F Sapega
- Ioffe Institute , Russian Academy of Sciences , 194021 St. Petersburg , Russia
| | - Dmitri R Yakovlev
- Experimentelle Physik 2 , Technische Universität Dortmund , 44227 Dortmund , Germany
- Ioffe Institute , Russian Academy of Sciences , 194021 St. Petersburg , Russia
| | - Ina V Kalitukha
- Ioffe Institute , Russian Academy of Sciences , 194021 St. Petersburg , Russia
| | - Elena V Shornikova
- Experimentelle Physik 2 , Technische Universität Dortmund , 44227 Dortmund , Germany
| | - Anna V Rodina
- 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 , 44227 Dortmund , Germany
- Ioffe Institute , Russian Academy of Sciences , 194021 St. Petersburg , Russia
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23
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Fainblat R, Delikanli S, Spee L, Czerny T, Isik F, Sharma VK, Demir HV, Bacher G. Impurity incorporation and exchange interactions in Co2+-doped CdSe/CdS core/shell nanoplatelets. J Chem Phys 2019; 151:224708. [DOI: 10.1063/1.5129391] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Affiliation(s)
- Rachel Fainblat
- Werkstoffe der Elektrotechnik and CENIDE, University of Duisburg-Essen, Bismarckstr. 81, Duisburg 47057, Germany
| | - Savas Delikanli
- Luminous! Center of Excellence for Semiconductor Lighting and Displays, School of Electrical and Electronic Engineering, School of Physical and Materials Sciences, School of Materials Sciences and Engineering, Nanyang Technological University, 639798, Singapore
- Department of Electrical and Electronics Engineering, Department of Physics, UNAM-Institute of Materials Science and Nanotechnology, Bilkent University, Ankara 06800, Turkey
| | - Leon Spee
- Werkstoffe der Elektrotechnik and CENIDE, University of Duisburg-Essen, Bismarckstr. 81, Duisburg 47057, Germany
| | - Tamara Czerny
- Werkstoffe der Elektrotechnik and CENIDE, University of Duisburg-Essen, Bismarckstr. 81, Duisburg 47057, Germany
| | - Furkan Isik
- Department of Electrical and Electronics Engineering, Department of Physics, UNAM-Institute of Materials Science and Nanotechnology, Bilkent University, Ankara 06800, Turkey
| | - Vijay Kumar Sharma
- Luminous! Center of Excellence for Semiconductor Lighting and Displays, School of Electrical and Electronic Engineering, School of Physical and Materials Sciences, School of Materials Sciences and Engineering, Nanyang Technological University, 639798, Singapore
| | - Hilmi Volkan Demir
- Luminous! Center of Excellence for Semiconductor Lighting and Displays, School of Electrical and Electronic Engineering, School of Physical and Materials Sciences, School of Materials Sciences and Engineering, Nanyang Technological University, 639798, Singapore
- Department of Electrical and Electronics Engineering, Department of Physics, UNAM-Institute of Materials Science and Nanotechnology, Bilkent University, Ankara 06800, Turkey
| | - Gerd Bacher
- Werkstoffe der Elektrotechnik and CENIDE, University of Duisburg-Essen, Bismarckstr. 81, Duisburg 47057, Germany
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24
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Pinchetti V, Shornikova EV, Qiang G, Bae WK, Meinardi F, Crooker SA, Yakovlev DR, Bayer M, Klimov VI, Brovelli S. Dual-Emitting Dot-in-Bulk CdSe/CdS Nanocrystals with Highly Emissive Core- and Shell-Based Trions Sharing the Same Resident Electron. NANO LETTERS 2019; 19:8846-8854. [PMID: 31651177 DOI: 10.1021/acs.nanolett.9b03676] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Colloidal CdSe nanocrystals (NCs) overcoated with an ultrathick CdS shell, also known as dot-in-bulk (DiB) structures, can support two types of excitons, one of which is core-localized and the other, shell-localized. In the case of weak "sub-single-exciton" pumping, emission alternates between the core- and shell-related channels, which leads to two-color light. This property makes these structures uniquely suited for a variety of photonic applications as well as ideal model systems for realizing complex excitonic quasi-particles that do not occur in conventional core/shell NCs. Here, we show that the DiB design can enable an unusual regime in which the same long-lived resident electron can endow trionlike characteristics to either of the two excitons of the DiB NC (core- or shell-based). These two spectrally distinct trion states are apparent in the measured photoluminescence (PL) and spin dynamics of core and shell excitons conducted over a wide range of temperatures and applied magnetic fields. Low-temperature PL measurements indicate that core- and shell-based trions are characterized by a nearly ideal (∼100%) emission quantum yield, suggesting the strong suppression of Auger recombination for both types of excitations. Polarization-resolved PL experiments in magnetic fields of up to 60 T reveal that the core- and the shell-localized trions exhibit remarkably similar spin dynamics, which in both cases are controlled by spin-flip processes involving a heavy hole.
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Affiliation(s)
- Valerio Pinchetti
- Dipartimento di Scienza dei Materiali , Università degli Studi di Milano-Bicocca , via Roberto Cozzi 55 , I-20125 Milano , Italy
| | - Elena V Shornikova
- Experimentelle Physik 2 , Technische Universität Dortmund , 44227 Dortmund , Germany
| | - Gang Qiang
- Experimentelle Physik 2 , Technische Universität Dortmund , 44227 Dortmund , Germany
| | - Wan Ki Bae
- Chemistry Division , Los Alamos National Laboratory , Los Alamos , New Mexico 87545 , United States
| | - Francesco Meinardi
- Dipartimento di Scienza dei Materiali , Università degli Studi di Milano-Bicocca , via Roberto Cozzi 55 , I-20125 Milano , Italy
| | - Scott A Crooker
- National High Magnetic Field Laboratory , Los Alamos National Laboratory , Los Alamos , New Mexico 87545 , United States
| | - Dmitri R Yakovlev
- Experimentelle Physik 2 , Technische Universität Dortmund , 44227 Dortmund , Germany
- Ioffe Institute, Russian Academy of Sciences , 194021 St. Petersburg , Russia
| | - Manfred Bayer
- Experimentelle Physik 2 , Technische Universität Dortmund , 44227 Dortmund , Germany
- Ioffe Institute, Russian Academy of Sciences , 194021 St. Petersburg , Russia
| | - Victor I Klimov
- Chemistry Division , Los Alamos National Laboratory , Los Alamos , New Mexico 87545 , United States
| | - Sergio Brovelli
- Dipartimento di Scienza dei Materiali , Università degli Studi di Milano-Bicocca , via Roberto Cozzi 55 , I-20125 Milano , Italy
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25
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Pandya R, Steinmetz V, Puttisong Y, Dufour M, Chen WM, Chen RYS, Barisien T, Sharma A, Lakhwani G, Mitioglu A, Christianen PCM, Legrand L, Bernardot F, Testelin C, Chin AW, Ithurria S, Chamarro M, Rao A. Fine Structure and Spin Dynamics of Linearly Polarized Indirect Excitons in Two-Dimensional CdSe/CdTe Colloidal Heterostructures. ACS NANO 2019; 13:10140-10153. [PMID: 31490653 DOI: 10.1021/acsnano.9b03252] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Heterostructured two-dimensional colloidal nanoplatelets are a class of material that has attracted great interest for optoelectronic applications due to their high photoluminescence yield, atomically tunable thickness, and ultralow lasing thresholds. Of particular interest are laterally heterostructured core-crown nanoplatelets with a type-II band alignment, where the in-plane spatial separation of carriers leads to indirect (or charge transfer) excitons with long lifetimes and bright, highly Stokes shifted emission. Despite this, little is known about the nature of the lowest energy exciton states responsible for emission in these materials. Here, using polarization-controlled, steady-state, and time-resolved photoluminescence measurements, at temperatures down to 1.6 K and magnetic fields up to 30 T, we study the exciton fine structure and spin dynamics of archetypal type-II CdSe/CdTe core-crown nanoplatelets. Complemented by theoretical modeling and zero-field quantum beat measurements, we find the bright-exciton fine structure consists of two linearly polarized states with a fine structure splitting ∼50 μeV and an indirect exciton Landé g-factor of 0.7. In addition, we show the exciton spin lifetime to be in the microsecond range with an unusual B-3 magnetic field dependence. The discovery of linearly polarized exciton states and emission highlights the potential for use of such materials in display and imaging applications without polarization filters. Furthermore, the small exciton fine structure splitting and a long spin lifetime are fundamental advantages when envisaging CdSe/CdTe nanoplatelets as elementary bricks for the next generation of quantum devices, particularly given their ease of fabrication.
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Affiliation(s)
- Raj Pandya
- Cavendish Laboratory , University of Cambridge , J.J. Thomson Avenue , CB3 0HE Cambridge , United Kingdom
| | - Violette Steinmetz
- Sorbonne Université CNRS-UMR 7588, Institut des NanoSciences de Paris , INSP, 4 place Jussieu , F-75005 Paris , France
| | - Yuttapoom Puttisong
- Functional Electronic Materials, Department of Physics, Chemistry and Biology , Linköping University , 58183 Linköping , Sweden
| | - Marion Dufour
- Laboratoire de Physique et d'Etude des Matériaux, ESPCI Paris , PSL Research University, CNRS , 10 rue Vauquelin , 75005 Paris , France
| | - Weimin M Chen
- Functional Electronic Materials, Department of Physics, Chemistry and Biology , Linköping University , 58183 Linköping , Sweden
| | - Richard Y S Chen
- Cavendish Laboratory , University of Cambridge , J.J. Thomson Avenue , CB3 0HE Cambridge , United Kingdom
| | - Thierry Barisien
- Sorbonne Université CNRS-UMR 7588, Institut des NanoSciences de Paris , INSP, 4 place Jussieu , F-75005 Paris , France
| | - Ashish Sharma
- ARC Centre of Excellence in Exciton Science, School of Chemistry , The University of Sydney , Sydney , New South Wales 2006 , Australia
| | - Girish Lakhwani
- ARC Centre of Excellence in Exciton Science, School of Chemistry , The University of Sydney , Sydney , New South Wales 2006 , Australia
| | - Anatolie Mitioglu
- 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
| | - Laurent Legrand
- Sorbonne Université CNRS-UMR 7588, Institut des NanoSciences de Paris , INSP, 4 place Jussieu , F-75005 Paris , France
| | - Frédérick Bernardot
- Sorbonne Université CNRS-UMR 7588, Institut des NanoSciences de Paris , INSP, 4 place Jussieu , F-75005 Paris , France
| | - Christophe Testelin
- Sorbonne Université CNRS-UMR 7588, Institut des NanoSciences de Paris , INSP, 4 place Jussieu , F-75005 Paris , France
| | - Alex W Chin
- Sorbonne Université CNRS-UMR 7588, Institut des NanoSciences de Paris , INSP, 4 place Jussieu , F-75005 Paris , France
| | - Sandrine Ithurria
- Laboratoire de Physique et d'Etude des Matériaux, ESPCI Paris , PSL Research University, CNRS , 10 rue Vauquelin , 75005 Paris , France
| | - Maria Chamarro
- Sorbonne Université CNRS-UMR 7588, Institut des NanoSciences de Paris , INSP, 4 place Jussieu , F-75005 Paris , France
| | - Akshay Rao
- Cavendish Laboratory , University of Cambridge , J.J. Thomson Avenue , CB3 0HE Cambridge , United Kingdom
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26
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Brodu A, Chandrasekaran V, Scarpelli L, Buhot J, Masia F, Ballottin MV, Severijnen M, Tessier MD, Dupont D, Rabouw FT, Christianen PCM, de Mello Donega C, Vanmaekelbergh D, Langbein W, Hens Z. Fine Structure of Nearly Isotropic Bright Excitons in InP/ZnSe Colloidal Quantum Dots. J Phys Chem Lett 2019; 10:5468-5475. [PMID: 31424940 DOI: 10.1021/acs.jpclett.9b01824] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The fine structure of exciton states in colloidal quantum dots (QDs) results from the compound effect of anisotropy and electron-hole exchange. By means of single-dot photoluminescence spectroscopy, we show that the emission of photoexcited InP/ZnSe QDs originates from radiative recombination of such fine structure exciton states. Depending on the excitation power, we identify a bright exciton doublet, a trion singlet, and a biexciton doublet line that all show pronounced polarization. Fluorescence line narrowing spectra of an ensemble of InP/ZnSe QDs in magnetic fields demonstrate that the bright exciton effectively consists of three states. The Zeeman splitting of these states is well described by an isotropic exciton model, where the fine structure is dominated by electron-hole exchange and shape anisotropy leads to only a minor splitting of the F = 1 triplet. We argue that excitons in InP-based QDs are nearly isotropic because the particular ratio of light and heavy hole masses in InP makes the exciton fine structure insensitive to shape anisotropy.
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Affiliation(s)
- Annalisa Brodu
- Debye Institute for Nanomaterials Science , Utrecht University , 3584 CC Utrecht , The Netherlands
| | - Vigneshwaran Chandrasekaran
- Physics and Chemistry of Nanostructures , Ghent University , 9000 Ghent , Belgium
- Center for Nano and Biophotonics , Ghent University , 9052 Ghent , Belgium
| | - Lorenzo Scarpelli
- School of Physics and Astronomy , Cardiff University , Cardiff CF24 3AA , United Kingdom
| | - Jonathan Buhot
- High Field Magnet Laboratory, HFML-EMFL , Radboud University , 6525 ED Nijmegen , The Netherlands
| | - Francesco Masia
- School of Physics and Astronomy , Cardiff University , Cardiff CF24 3AA , United Kingdom
| | - Mariana V Ballottin
- High Field Magnet Laboratory, HFML-EMFL , Radboud University , 6525 ED Nijmegen , The Netherlands
| | - Marion Severijnen
- High Field Magnet Laboratory, HFML-EMFL , Radboud University , 6525 ED Nijmegen , The Netherlands
| | - Mickaël D Tessier
- Physics and Chemistry of Nanostructures , Ghent University , 9000 Ghent , Belgium
- Center for Nano and Biophotonics , Ghent University , 9052 Ghent , Belgium
| | - Dorian Dupont
- Physics and Chemistry of Nanostructures , Ghent University , 9000 Ghent , Belgium
- Center for Nano and Biophotonics , Ghent University , 9052 Ghent , Belgium
| | - Freddy T Rabouw
- Debye Institute for Nanomaterials Science , Utrecht University , 3584 CC Utrecht , The Netherlands
| | - Peter C M Christianen
- High Field Magnet Laboratory, HFML-EMFL , Radboud University , 6525 ED Nijmegen , The Netherlands
| | - Celso de Mello Donega
- Debye Institute for Nanomaterials Science , Utrecht University , 3584 CC Utrecht , The Netherlands
| | - Daniël Vanmaekelbergh
- Debye Institute for Nanomaterials Science , Utrecht University , 3584 CC Utrecht , The Netherlands
| | - Wolfgang Langbein
- School of Physics and Astronomy , Cardiff University , Cardiff CF24 3AA , United Kingdom
| | - Zeger Hens
- Physics and Chemistry of Nanostructures , Ghent University , 9000 Ghent , Belgium
- Center for Nano and Biophotonics , Ghent University , 9052 Ghent , Belgium
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27
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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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28
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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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29
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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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30
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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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