The dark exciton ground state promotes photon-pair emission in individual perovskite nanocrystals

Cesium lead halide perovskites exhibit outstanding optical and electronic properties for a wide range of applications in optoelectronics and for light-emitting devices. Yet, the physics of the band-edge exciton, whose recombination is at the origin of the photoluminescence, is not elucidated. Here,...

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Bibliographic Details
Published in:Nature communications 2020-11, Vol.11 (1), p.6001-6001, Article 6001
Main Authors: Tamarat, Philippe, Hou, Lei, Trebbia, Jean-Baptiste, Swarnkar, Abhishek, Biadala, Louis, Louyer, Yann, Bodnarchuk, Maryna I., Kovalenko, Maksym V., Even, Jacky, Lounis, Brahim
Format: Article
Language:English
Subjects:
140/125
639/624/399/1017
639/925/357/1017
Anisotropy
Cesium
Crystals
Emitters
Emitters (electron)
Excitons
Fine structure
Holes (electron deficiencies)
Humanities and Social Sciences
Iodides
Lead
Lead compounds
Light emission
Low temperature
Metal halides
multidisciplinary
Nanocrystals
Optical properties
Optoelectronics
Perovskites
Photoluminescence
Photons
Physics
Quantum Physics
Recombination
Science
Science (multidisciplinary)
Thermal coupling
Ultrastructure
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Summary:Cesium lead halide perovskites exhibit outstanding optical and electronic properties for a wide range of applications in optoelectronics and for light-emitting devices. Yet, the physics of the band-edge exciton, whose recombination is at the origin of the photoluminescence, is not elucidated. Here, we unveil the exciton fine structure of individual cesium lead iodide perovskite nanocrystals and demonstrate that it is governed by the electron-hole exchange interaction and nanocrystal shape anisotropy. The lowest-energy exciton state is a long-lived dark singlet state, which promotes the creation of biexcitons at low temperatures and thus correlated photon pairs. These bright quantum emitters in the near-infrared have a photon statistics that can readily be tuned from bunching to antibunching, using magnetic or thermal coupling between dark and bright exciton sublevels. The optical and electronic properties of cesium lead halide perovskite nanocrystals are dictated by the band-edge exciton, whose physics is not elucidated. Here, the authors unveil its fine structure and demonstrate that the ground dark singlet state promotes the creation of biexcitons at low temperatures and thus correlated photon pairs.
ISSN:2041-1723
2041-1723
DOI:10.1038/s41467-020-19740-7