1
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Erkensten D, Brem S, Perea-Causín R, Hagel J, Tagarelli F, Lopriore E, Kis A, Malic E. Electrically tunable dipolar interactions between layer-hybridized excitons. Nanoscale 2023; 15:11064-11071. [PMID: 37309577 PMCID: PMC10324325 DOI: 10.1039/d3nr01049j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/06/2023] [Accepted: 06/02/2023] [Indexed: 06/14/2023]
Abstract
Transition-metal dichalcogenide bilayers exhibit a rich exciton landscape including layer-hybridized excitons, i.e. excitons which are of partly intra- and interlayer nature. In this work, we study hybrid exciton-exciton interactions in naturally stacked WSe2 homobilayers. In these materials, the exciton landscape is electrically tunable such that the low-energy states can be rendered more or less interlayer-like depending on the strength of the external electric field. Based on a microscopic and material-specific many-particle theory, we reveal two intriguing interaction regimes: a low-dipole regime at small electric fields and a high-dipole regime at larger fields, involving interactions between hybrid excitons with a substantially different intra- and interlayer composition in the two regimes. While the low-dipole regime is characterized by weak inter-excitonic interactions between intralayer-like excitons, the high-dipole regime involves mostly interlayer-like excitons which display a strong dipole-dipole repulsion and give rise to large spectral blue-shifts and a highly anomalous diffusion. Overall, our microscopic study sheds light on the remarkable electrical tunability of hybrid exciton-exciton interactions in atomically thin semiconductors and can guide future experimental studies in this growing field of research.
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Affiliation(s)
- Daniel Erkensten
- Department of Physics, Chalmers University of Technology, 41296 Gothenburg, Sweden.
| | - Samuel Brem
- Department of Physics, Philipps-Universität Marburg, 35037 Marburg, Germany
| | - Raül Perea-Causín
- Department of Physics, Chalmers University of Technology, 41296 Gothenburg, Sweden.
| | - Joakim Hagel
- Department of Physics, Chalmers University of Technology, 41296 Gothenburg, Sweden.
| | - Fedele Tagarelli
- Institute of Electrical and Microengineering, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
- Institute of Materials Science and Engineering, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - Edoardo Lopriore
- Institute of Electrical and Microengineering, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
- Institute of Materials Science and Engineering, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - Andras Kis
- Institute of Electrical and Microengineering, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
- Institute of Materials Science and Engineering, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - Ermin Malic
- Department of Physics, Philipps-Universität Marburg, 35037 Marburg, Germany
- Department of Physics, Chalmers University of Technology, 41296 Gothenburg, Sweden.
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2
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Choi J, Embley J, Blach DD, Perea-Causín R, Erkensten D, Kim DS, Yuan L, Yoon WY, Taniguchi T, Watanabe K, Ueno K, Tutuc E, Brem S, Malic E, Li X, Huang L. Fermi Pressure and Coulomb Repulsion Driven Rapid Hot Plasma Expansion in a van der Waals Heterostructure. Nano Lett 2023; 23:4399-4405. [PMID: 37154560 DOI: 10.1021/acs.nanolett.3c00678] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
Transition metal dichalcogenide heterostructures provide a versatile platform to explore electronic and excitonic phases. As the excitation density exceeds the critical Mott density, interlayer excitons are ionized into an electron-hole plasma phase. The transport of the highly non-equilibrium plasma is relevant for high-power optoelectronic devices but has not been carefully investigated previously. Here, we employ spatially resolved pump-probe microscopy to investigate the spatial-temporal dynamics of interlayer excitons and hot-plasma phase in a MoSe2/WSe2 twisted bilayer. At the excitation density of ∼1014 cm-2, well exceeding the Mott density, we find a surprisingly rapid initial expansion of hot plasma to a few microns away from the excitation source within ∼0.2 ps. Microscopic theory reveals that this rapid expansion is mainly driven by Fermi pressure and Coulomb repulsion, while the hot carrier effect has only a minor effect in the plasma phase.
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Affiliation(s)
- Junho Choi
- Department of Physics and Center for Complex Quantum Systems, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Jacob Embley
- Department of Physics and Center for Complex Quantum Systems, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Daria D Blach
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907-2050, United States
| | - Raül Perea-Causín
- Department of Physics, Chalmers University of Technology, 41296 Gothenburg, Sweden
| | - Daniel Erkensten
- Department of Physics, Chalmers University of Technology, 41296 Gothenburg, Sweden
| | - Dong Seob Kim
- Department of Physics and Center for Complex Quantum Systems, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Long Yuan
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907-2050, United States
| | - Woo Young Yoon
- Department of Electrical and Computer Engineering, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Takashi Taniguchi
- International Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan
| | - Kenji Watanabe
- Research Center for Functional Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan
| | - Keiji Ueno
- Department of Chemistry, Graduate School of Science and Engineering, Saitama University, Saitama 338-8570, Japan
| | - Emanuel Tutuc
- Department of Electrical and Computer Engineering, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Samuel Brem
- Department of Physics, Philipps University of Marburg, 35037 Marburg, Germany
| | - Ermin Malic
- Department of Physics, Chalmers University of Technology, 41296 Gothenburg, Sweden
- Department of Physics, Philipps University of Marburg, 35037 Marburg, Germany
| | - Xiaoqin Li
- Department of Physics and Center for Complex Quantum Systems, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Libai Huang
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907-2050, United States
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3
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Tagarelli F, Lopriore E, Erkensten D, Perea-Causín R, Brem S, Hagel J, Sun Z, Pasquale G, Watanabe K, Taniguchi T, Malic E, Kis A. Electrical control of hybrid exciton transport in a van der Waals heterostructure. Nat Photonics 2023; 17:615-621. [PMID: 37426431 PMCID: PMC10322698 DOI: 10.1038/s41566-023-01198-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/08/2022] [Accepted: 03/10/2023] [Indexed: 07/11/2023]
Abstract
Interactions between out-of-plane dipoles in bosonic gases enable the long-range propagation of excitons. The lack of direct control over collective dipolar properties has so far limited the degrees of tunability and the microscopic understanding of exciton transport. In this work we modulate the layer hybridization and interplay between many-body interactions of excitons in a van der Waals heterostructure with an applied vertical electric field. By performing spatiotemporally resolved measurements supported by microscopic theory, we uncover the dipole-dependent properties and transport of excitons with different degrees of hybridization. Moreover, we find constant emission quantum yields of the transporting species as a function of excitation power with radiative decay mechanisms dominating over nonradiative ones, a fundamental requirement for efficient excitonic devices. Our findings provide a complete picture of the many-body effects in the transport of dilute exciton gases, and have crucial implications for studying emerging states of matter such as Bose-Einstein condensation and optoelectronic applications based on exciton propagation.
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Affiliation(s)
- Fedele Tagarelli
- Institute of Electrical and Microengineering, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
- Institute of Materials Science and Engineering, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - Edoardo Lopriore
- Institute of Electrical and Microengineering, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
- Institute of Materials Science and Engineering, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - Daniel Erkensten
- Department of Physics, Chalmers University of Technology, Gothenburg, Sweden
| | - Raül Perea-Causín
- Department of Physics, Chalmers University of Technology, Gothenburg, Sweden
| | - Samuel Brem
- Department of Physics, Philipps-Universität Marburg, Marburg, Germany
| | - Joakim Hagel
- Department of Physics, Chalmers University of Technology, Gothenburg, Sweden
| | - Zhe Sun
- Institute of Electrical and Microengineering, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
- Institute of Materials Science and Engineering, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - Gabriele Pasquale
- Institute of Electrical and Microengineering, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
- Institute of Materials Science and Engineering, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - Kenji Watanabe
- Research Center for Functional Materials, National Institute for Materials Science, Tsukuba, Japan
| | - Takashi Taniguchi
- International Center for Materials Nanoarchitectonics, National Institute for Materials Science, Tsukuba, Japan
| | - Ermin Malic
- Department of Physics, Chalmers University of Technology, Gothenburg, Sweden
- Department of Physics, Philipps-Universität Marburg, Marburg, Germany
| | - Andras Kis
- Institute of Electrical and Microengineering, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
- Institute of Materials Science and Engineering, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
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4
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Rosati R, Wagner K, Brem S, Perea-Causín R, Ziegler JD, Zipfel J, Taniguchi T, Watanabe K, Chernikov A, Malic E. Non-equilibrium diffusion of dark excitons in atomically thin semiconductors. Nanoscale 2021; 13:19966-19972. [PMID: 34821228 DOI: 10.1039/d1nr06230a] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Atomically thin semiconductors provide an excellent platform to study intriguing many-particle physics of tightly-bound excitons. In particular, the properties of tungsten-based transition metal dichalcogenides are determined by a complex manifold of bright and dark exciton states. While dark excitons are known to dominate the relaxation dynamics and low-temperature photoluminescence, their impact on the spatial propagation of excitons has remained elusive. In our joint theory-experiment study, we address this intriguing regime of dark state transport by resolving the spatio-temporal exciton dynamics in hBN-encapsulated WSe2 monolayers after resonant excitation. We find clear evidence of an unconventional, time-dependent diffusion during the first tens of picoseconds, exhibiting strong deviation from the steady-state propagation. Dark exciton states are initially populated by phonon emission from the bright states, resulting in creation of hot (unequilibrated) excitons whose rapid expansion leads to a transient increase of the diffusion coefficient by more than one order of magnitude. These findings are relevant for both fundamental understanding of the spatio-temporal exciton dynamics in atomically thin materials as well as their technological application by enabling rapid diffusion.
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Affiliation(s)
- Roberto Rosati
- Department of Physics, Philipps-Universität Marburg, Renthof 7, D-35032 Marburg, Germany.
| | - Koloman Wagner
- Department of Physics, University of Regensburg, Regensburg D-93053, Germany
- Dresden Integrated Center for Applied Physics and Photonic Materials (IAPP) and Würzburg-Dresden Cluster of Excellence ct.qmat, Technische Universität Dresden, 01062 Dresden, Germany
| | - Samuel Brem
- Department of Physics, Philipps-Universität Marburg, Renthof 7, D-35032 Marburg, Germany.
| | - Raül Perea-Causín
- Chalmers University of Technology, Department of Physics, 412 96 Gothenburg, Sweden
| | - Jonas D Ziegler
- Department of Physics, University of Regensburg, Regensburg D-93053, Germany
- Dresden Integrated Center for Applied Physics and Photonic Materials (IAPP) and Würzburg-Dresden Cluster of Excellence ct.qmat, Technische Universität Dresden, 01062 Dresden, Germany
| | - Jonas Zipfel
- Department of Physics, University of Regensburg, Regensburg D-93053, Germany
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Takashi Taniguchi
- International Center for Materials Nanoarchitectonics, National Institute for Materials Science, Tsukuba, Ibaraki 305-004, Japan
| | - Kenji Watanabe
- Research Center for Functional Materials, National Institute for Materials Science, Tsukuba, Ibaraki 305-004, Japan
| | - Alexey Chernikov
- Department of Physics, University of Regensburg, Regensburg D-93053, Germany
- Dresden Integrated Center for Applied Physics and Photonic Materials (IAPP) and Würzburg-Dresden Cluster of Excellence ct.qmat, Technische Universität Dresden, 01062 Dresden, Germany
| | - Ermin Malic
- Department of Physics, Philipps-Universität Marburg, Renthof 7, D-35032 Marburg, Germany.
- Chalmers University of Technology, Department of Physics, 412 96 Gothenburg, Sweden
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5
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Rosati R, Schmidt R, Brem S, Perea-Causín R, Niehues I, Kern J, Preuß JA, Schneider R, Michaelis de Vasconcellos S, Bratschitsch R, Malic E. Dark exciton anti-funneling in atomically thin semiconductors. Nat Commun 2021; 12:7221. [PMID: 34893602 PMCID: PMC8664915 DOI: 10.1038/s41467-021-27425-y] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2021] [Accepted: 11/16/2021] [Indexed: 11/09/2022] Open
Abstract
Transport of charge carriers is at the heart of current nanoelectronics. In conventional materials, electronic transport can be controlled by applying electric fields. Atomically thin semiconductors, however, are governed by excitons, which are neutral electron-hole pairs and as such cannot be controlled by electrical fields. Recently, strain engineering has been introduced to manipulate exciton propagation. Strain-induced energy gradients give rise to exciton funneling up to a micrometer range. Here, we combine spatiotemporal photoluminescence measurements with microscopic theory to track the way of excitons in time, space and energy. We find that excitons surprisingly move away from high-strain regions. This anti-funneling behavior can be ascribed to dark excitons which possess an opposite strain-induced energy variation compared to bright excitons. Our findings open new possibilities to control transport in exciton-dominated materials. Overall, our work represents a major advance in understanding exciton transport that is crucial for technological applications of atomically thin materials.
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Affiliation(s)
- Roberto Rosati
- Department of Physics, Philipps-Universität Marburg, 35032, Marburg, Germany
| | - Robert Schmidt
- Institute of Physics and Center for Nanotechnology, University of Münster, 48149, Münster, Germany
| | - Samuel Brem
- Department of Physics, Philipps-Universität Marburg, 35032, Marburg, Germany
| | - Raül Perea-Causín
- Chalmers University of Technology, Department of Physics, 412 96, Gothenburg, Sweden
| | - Iris Niehues
- Institute of Physics and Center for Nanotechnology, University of Münster, 48149, Münster, Germany
| | - Johannes Kern
- Institute of Physics and Center for Nanotechnology, University of Münster, 48149, Münster, Germany
| | - Johann A Preuß
- Institute of Physics and Center for Nanotechnology, University of Münster, 48149, Münster, Germany
| | - Robert Schneider
- Institute of Physics and Center for Nanotechnology, University of Münster, 48149, Münster, Germany
| | | | - Rudolf Bratschitsch
- Institute of Physics and Center for Nanotechnology, University of Münster, 48149, Münster, Germany.
| | - Ermin Malic
- Department of Physics, Philipps-Universität Marburg, 35032, Marburg, Germany.
- Chalmers University of Technology, Department of Physics, 412 96, Gothenburg, Sweden.
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6
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Wagner K, Zipfel J, Rosati R, Wietek E, Ziegler JD, Brem S, Perea-Causín R, Taniguchi T, Watanabe K, Glazov MM, Malic E, Chernikov A. Nonclassical Exciton Diffusion in Monolayer WSe_{2}. Phys Rev Lett 2021; 127:076801. [PMID: 34459627 DOI: 10.1103/physrevlett.127.076801] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/09/2021] [Accepted: 06/24/2021] [Indexed: 06/13/2023]
Abstract
We experimentally demonstrate time-resolved exciton propagation in a monolayer semiconductor at cryogenic temperatures. Monitoring phonon-assisted recombination of dark states, we find a highly unusual case of exciton diffusion. While at 5 K the diffusivity is intrinsically limited by acoustic phonon scattering, we observe a pronounced decrease of the diffusion coefficient with increasing temperature, far below the activation threshold of higher-energy phonon modes. This behavior corresponds neither to well-known regimes of semiclassical free-particle transport nor to the thermally activated hopping in systems with strong localization. Its origin is discussed in the framework of both microscopic numerical and semiphenomenological analytical models illustrating the observed characteristics of nonclassical propagation. Challenging the established description of mobile excitons in monolayer semiconductors, these results open up avenues to study quantum transport phenomena for excitonic quasiparticles in atomically thin van der Waals materials and their heterostructures.
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Affiliation(s)
- Koloman Wagner
- Department of Physics, University of Regensburg, Regensburg D-93053, Germany
| | - Jonas Zipfel
- Department of Physics, University of Regensburg, Regensburg D-93053, Germany
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Roberto Rosati
- Department of Physics, Philipps-Universität Marburg, Renthof 7, Marburg D-35032, Germany
| | - Edith Wietek
- Department of Physics, University of Regensburg, Regensburg D-93053, Germany
| | - Jonas D Ziegler
- Department of Physics, University of Regensburg, Regensburg D-93053, Germany
| | - Samuel Brem
- Department of Physics, Philipps-Universität Marburg, Renthof 7, Marburg D-35032, Germany
| | - Raül Perea-Causín
- Department of Physics, Chalmers University of Technology, Fysikgården 1, 41258 Gothenburg, Sweden
| | - Takashi Taniguchi
- International Center for Materials Nanoarchitectonics, National Institute for Materials Science, Tsukuba, Ibaraki 305-004, Japan
| | - Kenji Watanabe
- Research Center for Functional Materials, National Institute for Materials Science, Tsukuba, Ibaraki 305-004, Japan
| | | | - Ermin Malic
- Department of Physics, Philipps-Universität Marburg, Renthof 7, Marburg D-35032, Germany
- Department of Physics, Chalmers University of Technology, Fysikgården 1, 41258 Gothenburg, Sweden
| | - Alexey Chernikov
- Department of Physics, University of Regensburg, Regensburg D-93053, Germany
- Dresden Integrated Center for Applied Physics and Photonic Materials (IAPP) and Würzburg-Dresden Cluster of Excellence ct.qmat, Technische Universität Dresden, 01062 Dresden, Germany
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7
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Abstract
Monolayers of transition metal dichalcogenides (TMDs) have been established in the last years as promising materials for novel optoelectronic devices. However, the performance of such devices is often limited by the dissociation of tightly bound excitons into free electrons and holes. While previous studies have investigated tunneling at large electric fields, we focus in this work on phonon-assisted exciton dissociation that is expected to be the dominant mechanism at small fields. We present a microscopic model based on the density matrix formalism providing access to time- and momentum-resolved exciton dynamics including phonon-assisted dissociation. We track the pathway of excitons from optical excitation via thermalization to dissociation, identifying the main transitions and dissociation channels. Furthermore, we find intrinsic limits for the quantum efficiency and response time of a TMD-based photodetector and investigate their tunability with externally accessible knobs, such as excitation energy, substrate screening, temperature and strain. Our work provides microscopic insights in fundamental mechanisms behind exciton dissociation and can serve as a guide for the optimization of TMD-based optoelectronic devices.
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Affiliation(s)
- Raül Perea-Causín
- Department of Physics, Chalmers University of Technology, 412 96 Gothenburg, Sweden.
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8
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Thurakkal S, Feldstein D, Perea-Causín R, Malic E, Zhang X. The Art of Constructing Black Phosphorus Nanosheet Based Heterostructures: From 2D to 3D. Adv Mater 2021; 33:e2005254. [PMID: 33251663 DOI: 10.1002/adma.202005254] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/03/2020] [Revised: 10/08/2020] [Indexed: 06/12/2023]
Abstract
Assembling different kinds of 2D nanosheets into heterostructures presents a promising way of designing novel artificial materials with new and improved functionalities by combining the unique properties of each component. In the past few years, black phosphorus nanosheets (BPNSs) have been recognized as a highly feasible 2D material with outstanding electronic properties, a tunable bandgap, and strong in-plane anisotropy, highlighting their suitability as a material for constructing heterostructures. In this study, recent progress in the construction of BPNS-based heterostructures ranging from 2D hybrid structures to 3D networks is discussed, emphasizing the different types of interactions (covalent or noncovalent) between individual layers. The preparation methods, optical and electronic properties, and various applications of these heterostructures-including electronic and optoelectronic devices, energy storage devices, photocatalysis and electrocatalysis, and biological applications-are discussed. Finally, critical challenges and prospective research aspects in BPNS-based heterostructures are also highlighted.
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Affiliation(s)
- Shameel Thurakkal
- Division of Chemistry and Biochemistry, Department of Chemistry and Chemical Engineering, Chalmers University of Technology, Kemigården 4, Göteborg, SE-412 96, Sweden
| | - David Feldstein
- Division of Condensed Matter and Materials Theory, Department of Physics, Chalmers University of Technology, Kemigården 1, Göteborg, SE-412 96, Sweden
| | - Raül Perea-Causín
- Division of Condensed Matter and Materials Theory, Department of Physics, Chalmers University of Technology, Kemigården 1, Göteborg, SE-412 96, Sweden
| | - Ermin Malic
- Division of Condensed Matter and Materials Theory, Department of Physics, Chalmers University of Technology, Kemigården 1, Göteborg, SE-412 96, Sweden
| | - Xiaoyan Zhang
- Division of Chemistry and Biochemistry, Department of Chemistry and Chemical Engineering, Chalmers University of Technology, Kemigården 4, Göteborg, SE-412 96, Sweden
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9
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Feldstein D, Perea-Causín R, Wang S, Dyksik M, Watanabe K, Taniguchi T, Plochocka P, Malic E. Microscopic Picture of Electron-Phonon Interaction in Two-Dimensional Halide Perovskites. J Phys Chem Lett 2020; 11:9975-9982. [PMID: 33180499 PMCID: PMC7735742 DOI: 10.1021/acs.jpclett.0c02661] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Accepted: 10/21/2020] [Indexed: 05/06/2023]
Abstract
Perovskites have attracted much attention due to their remarkable optical properties. While it is well established that excitons dominate their optical response, the impact of higher excitonic states and formation of phonon sidebands in optical spectra still need to be better understood. Here, we perform a theoretical study of excitonic properties of monolayered hybrid organic perovskites-supported by temperature-dependent photoluminescence measurements. Solving the Wannier equation, we obtain microscopic access to the Rydberg-like series of excitonic states including their wave functions and binding energies. Exploiting the generalized Elliot formula, we calculate the photoluminescence spectra demonstrating a pronounced contribution of a phonon sideband for temperatures up to 50 K, in agreement with experimental measurements. Finally, we predict temperature-dependent line widths of the three energetically lowest excitonic transitions and identify the underlying phonon-driven scattering processes.
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Affiliation(s)
- David Feldstein
- Department
of Physics, Chalmers University of Technology, Gothenburg 412 96, Sweden
- Campus
Nord, Universitat Politècnica de
Catalunya, Barcelona 08034, Spain
| | - Raül Perea-Causín
- Department
of Physics, Chalmers University of Technology, Gothenburg 412 96, Sweden
| | - Shuli Wang
- UPR
3228, CNRS-UGA-UPS-INSA, Laboratoire National
des Champs Magnétiques Intenses, Grenoble and Toulouse, France
| | - Mateusz Dyksik
- UPR
3228, CNRS-UGA-UPS-INSA, Laboratoire National
des Champs Magnétiques Intenses, Grenoble and Toulouse, France
- Department
of Experimental Physics, Faculty of Fundamental Problems of Technology, Wroclaw University of Science and Technology, Wroclaw, Poland
| | - Kenji Watanabe
- Research
Center for Functional Materials, National
Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
| | - Takashi Taniguchi
- Research
Center for Functional Materials, National
Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
| | - Paulina Plochocka
- UPR
3228, CNRS-UGA-UPS-INSA, Laboratoire National
des Champs Magnétiques Intenses, Grenoble and Toulouse, France
- Department
of Experimental Physics, Faculty of Fundamental Problems of Technology, Wroclaw University of Science and Technology, Wroclaw, Poland
| | - Ermin Malic
- Department
of Physics, Chalmers University of Technology, Gothenburg 412 96, Sweden
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10
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Rosati R, Perea-Causín R, Brem S, Malic E. Negative effective excitonic diffusion in monolayer transition metal dichalcogenides. Nanoscale 2020; 12:356-363. [PMID: 31825433 DOI: 10.1039/c9nr07056g] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
While exciton relaxation in monolayers of transition metal dichalcogenides (TMDs) has been intensively studied, spatial exciton diffusion has received only a little attention - in spite of being a key process for optoelectronics and having already shown interesting unconventional behaviours (e.g. spatial halos). Here, we study the spatiotemporal dynamics in TMD monolayers and track optically excited excitons in time, momentum, and space. In particular, we investigate the temperature-dependent exciton diffusion including the remarkable exciton landscape constituted by bright and dark states. Based on a fully quantum mechanical approach, we show at low temperatures an unexpected negative effective diffusion characterized by a shrinking of the spatial exciton distributions. This phenomenon can be traced back to the existence of dark exciton states in TMD monolayers and is a result of an interplay between spatial exciton diffusion and intervalley exciton-phonon scattering.
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Affiliation(s)
- Roberto Rosati
- Chalmers University of Technology, Department of Physics, 412 96 Gothenburg, Sweden.
| | - Raül Perea-Causín
- Chalmers University of Technology, Department of Physics, 412 96 Gothenburg, Sweden.
| | - Samuel Brem
- Chalmers University of Technology, Department of Physics, 412 96 Gothenburg, Sweden.
| | - Ermin Malic
- Chalmers University of Technology, Department of Physics, 412 96 Gothenburg, Sweden.
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Perea-Causín R, Brem S, Rosati R, Jago R, Kulig M, Ziegler JD, Zipfel J, Chernikov A, Malic E. Exciton Propagation and Halo Formation in Two-Dimensional Materials. Nano Lett 2019; 19:7317-7323. [PMID: 31532993 DOI: 10.1021/acs.nanolett.9b02948] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The interplay of optics, dynamics, and transport is crucial for the design of novel optoelectronic devices, such as photodetectors and solar cells. In this context, transition-metal dichalcogenides (TMDs) have received much attention. Here, strongly bound excitons dominate optical excitation, carrier dynamics, and diffusion processes. While the first two have been intensively studied, there is a lack of fundamental understanding of nonequilibrium phenomena associated with exciton transport that is of central importance (e.g., for high-efficiency light harvesting). In this work, we provide microscopic insights into the interplay of exciton propagation and many-particle interactions in TMDs. On the basis of a fully quantum mechanical approach and in excellent agreement with photoluminescence measurements, we show that Auger recombination and emission of hot phonons act as a heating mechanism giving rise to strong spatial gradients in excitonic temperature. The resulting thermal drift leads to an unconventional exciton diffusion characterized by spatial exciton halos.
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Affiliation(s)
- Raül Perea-Causín
- Department of Physics , Chalmers University of Technology , 412 96 Gothenburg , Sweden
| | - Samuel Brem
- Department of Physics , Chalmers University of Technology , 412 96 Gothenburg , Sweden
| | - Roberto Rosati
- Department of Physics , Chalmers University of Technology , 412 96 Gothenburg , Sweden
| | - Roland Jago
- Department of Physics , Chalmers University of Technology , 412 96 Gothenburg , Sweden
| | - Marvin Kulig
- Department of Physics , University of Regensburg , Regensburg D-93053 , Germany
| | - Jonas D Ziegler
- Department of Physics , University of Regensburg , Regensburg D-93053 , Germany
| | - Jonas Zipfel
- Department of Physics , University of Regensburg , Regensburg D-93053 , Germany
| | - Alexey Chernikov
- Department of Physics , University of Regensburg , Regensburg D-93053 , Germany
| | - Ermin Malic
- Department of Physics , Chalmers University of Technology , 412 96 Gothenburg , Sweden
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