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Exciton-driven change of phonon modes causes strong temperature dependent bandgap shift in nanoclusters

Title
Exciton-driven change of phonon modes causes strong temperature dependent bandgap shift in nanoclusters
Authors
Muckel, FranziskaLorenz, SeverinYang, JiwoongNugraha, Taufik AdiScalise, EmilioHyeon, TaeghwanWippermann, StefanBacher, Gerd
DGIST Authors
Muckel, Franziska; Lorenz, Severin; Yang, Jiwoong; Nugraha, Taufik Adi; Scalise, Emilio; Hyeon, Taeghwan; Wippermann, Stefan; Bacher, Gerd
Issue Date
2020-08
Citation
Nature Communications, 11(1), 4127
Type
Article
Article Type
Article
Keywords
QUANTUM DOTSENERGY-GAPCDSELUMINESCENCESURFACESINANOPARTICLESTRANSITIONPEROVSKITE
ISSN
2041-1723
Abstract
The fundamental bandgap Eg of a semiconductor—often determined by means of optical spectroscopy—represents its characteristic fingerprint and changes distinctively with temperature. Here, we demonstrate that in magic sized II-VI clusters containing only 26 atoms, a pronounced weakening of the bonds occurs upon optical excitation, which results in a strong exciton-driven shift of the phonon spectrum. As a consequence, a drastic increase of dEg/dT (up to a factor of 2) with respect to bulk material or nanocrystals of typical size is found. We are able to describe our experimental data with excellent quantitative agreement from first principles deriving the bandgap shift with temperature as the vibrational entropy contribution to the free energy difference between the ground and optically excited states. Our work demonstrates how in small nanoparticles, photons as the probe medium affect the bandgap—a fundamental semiconductor property. © 2020, The Author(s).
URI
http://hdl.handle.net/20.500.11750/12398
DOI
10.1038/s41467-020-17563-0
Publisher
Nature Publishing Group
Related Researcher
  • Author Yang, Jiwoong NanoMaterials Laboratory
  • Research Interests Quantum Dots; Nanocrystals; Displays; Solar Energy; TEM; Photocatalyst
Files:
Collection:
Department of Energy Science and EngineeringNanoMaterials Laboratory1. Journal Articles


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