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Rodà C, Salzmann BBV, Wagner I, Ussembayev Y, Chen K, Hodgkiss JM, Neyts K, Moreels I, Vanmaekelbergh D, Geiregat P. Stimulated Emission through an Electron-Hole Plasma in Colloidal CdSe Quantum Rings. NANO LETTERS 2021; 21:10062-10069. [PMID: 34842440 PMCID: PMC9113625 DOI: 10.1021/acs.nanolett.1c03501] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
Colloidal CdSe quantum rings (QRs) are a recently developed class of nanomaterials with a unique topology. In nanocrystals with more common shapes, such as dots and platelets, the photophysics is consistently dominated by strongly bound electron-hole pairs, so-called excitons, regardless of the charge carrier density. Here, we show that charge carriers in QRs condense into a hot uncorrelated plasma state at high density. Through strong band gap renormalization, this plasma state is able to produce broadband and sizable optical gain. The gain is limited by a second-order, yet radiative, recombination process, and the buildup is counteracted by a charge-cooling bottleneck. Our results show that weakly confined QRs offer a unique system to study uncorrelated electron-hole dynamics in nanoscale materials.
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Affiliation(s)
- Carmelita Rodà
- Physics
and Chemistry of Nanostructures, Department of Chemistry, Center for Nano and
Biophotonics, Liquid Crystals and Photonics Research Group, Department of Information
Technology, and Physics and Chemistry of Nanostructures, Department of Chemistry, Ghent University, B-9000 Gent, Belgium
| | - Bastiaan B. V. Salzmann
- Debye
Institute for Nanomaterials Science, Utrecht
University, 3508 TA Utrecht, The Netherlands
| | - Isabella Wagner
- School of Chemical and Physical Sciences, Robinson Research Institute,
and MacDiarmid Institute
for Advanced Materials and Nanotechnology, Victoria University of Wellington, Wellington 6012, New Zealand
| | - Yera Ussembayev
- Physics
and Chemistry of Nanostructures, Department of Chemistry, Center for Nano and
Biophotonics, Liquid Crystals and Photonics Research Group, Department of Information
Technology, and Physics and Chemistry of Nanostructures, Department of Chemistry, Ghent University, B-9000 Gent, Belgium
| | - Kai Chen
- School of Chemical and Physical Sciences, Robinson Research Institute,
and MacDiarmid Institute
for Advanced Materials and Nanotechnology, Victoria University of Wellington, Wellington 6012, New Zealand
- The
Dodd-Walls Centre for Photonic and Quantum Technologies, University of Otago, Dunedin 9010, New Zealand
| | - Justin M. Hodgkiss
- School of Chemical and Physical Sciences, Robinson Research Institute,
and MacDiarmid Institute
for Advanced Materials and Nanotechnology, Victoria University of Wellington, Wellington 6012, New Zealand
| | - Kristiaan Neyts
- Physics
and Chemistry of Nanostructures, Department of Chemistry, Center for Nano and
Biophotonics, Liquid Crystals and Photonics Research Group, Department of Information
Technology, and Physics and Chemistry of Nanostructures, Department of Chemistry, Ghent University, B-9000 Gent, Belgium
| | - Iwan Moreels
- Physics
and Chemistry of Nanostructures, Department of Chemistry, Center for Nano and
Biophotonics, Liquid Crystals and Photonics Research Group, Department of Information
Technology, and Physics and Chemistry of Nanostructures, Department of Chemistry, Ghent University, B-9000 Gent, Belgium
| | - Daniel Vanmaekelbergh
- Debye
Institute for Nanomaterials Science, Utrecht
University, 3508 TA Utrecht, The Netherlands
| | - Pieter Geiregat
- Physics
and Chemistry of Nanostructures, Department of Chemistry, Center for Nano and
Biophotonics, Liquid Crystals and Photonics Research Group, Department of Information
Technology, and Physics and Chemistry of Nanostructures, Department of Chemistry, Ghent University, B-9000 Gent, Belgium
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Salzmann BV, Vliem JF, Maaskant DN, Post LC, Li C, Bals S, Vanmaekelbergh D. From CdSe Nanoplatelets to Quantum Rings by Thermochemical Edge Reconfiguration. CHEMISTRY OF MATERIALS : A PUBLICATION OF THE AMERICAN CHEMICAL SOCIETY 2021; 33:6853-6859. [PMID: 34552306 PMCID: PMC8444342 DOI: 10.1021/acs.chemmater.1c01618] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/11/2021] [Revised: 08/11/2021] [Indexed: 05/28/2023]
Abstract
The variation in the shape of colloidal semiconductor nanocrystals (NCs) remains intriguing. This interest goes beyond crystallography as the shape of the NC determines its energy levels and optoelectronic properties. While thermodynamic arguments point to a few or just a single shape(s), terminated by the most stable crystal facets, a remarkable variation in NC shape has been reported for many different compounds. For instance, for the well-studied case of CdSe, close-to-spherical quantum dots, rods, two-dimensional nanoplatelets, and quantum rings have been reported. Here, we report how two-dimensional CdSe nanoplatelets reshape into quantum rings. We monitor the reshaping in real time by combining atomically resolved structural characterization with optical absorption and photoluminescence spectroscopy. We observe that CdSe units leave the vertical sides of the edges and recrystallize on the top and bottom edges of the nanoplatelets, resulting in a thickening of the rims. The formation of a central hole, rendering the shape into a ring, only occurs at a more elevated temperature.
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Affiliation(s)
- Bastiaan
B. V. Salzmann
- Condensed
Matter & Interfaces, Debye Institute for Nanomaterials Science, Utrecht University, 3508TA Utrecht, The Netherlands
| | - Jara F. Vliem
- Condensed
Matter & Interfaces, Debye Institute for Nanomaterials Science, Utrecht University, 3508TA Utrecht, The Netherlands
| | - D. Nicolette Maaskant
- Condensed
Matter & Interfaces, Debye Institute for Nanomaterials Science, Utrecht University, 3508TA Utrecht, The Netherlands
| | - L. Christiaan Post
- Condensed
Matter & Interfaces, Debye Institute for Nanomaterials Science, Utrecht University, 3508TA Utrecht, The Netherlands
| | - Chen Li
- EMAT
and Nanolab Centre of Excellence, Antwerp
University, 2020 Antwerp, Belgium
| | - Sara Bals
- EMAT
and Nanolab Centre of Excellence, Antwerp
University, 2020 Antwerp, Belgium
| | - Daniel Vanmaekelbergh
- Condensed
Matter & Interfaces, Debye Institute for Nanomaterials Science, Utrecht University, 3508TA Utrecht, The Netherlands
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