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Localized holes and delocalized electrons in photoexcited inorganic perovskites: Watching each atomic actor by picosecond X-ray absorption spectroscopy

Authors :
Fabio G. Santomauro
Jakob Grilj
Lars Mewes
Georgian Nedelcu
Sergii Yakunin
Thomas Rossi
Gloria Capano
André Al Haddad
James Budarz
Dominik Kinschel
Dario S. Ferreira
Giacomo Rossi
Mario Gutierrez Tovar
Daniel Grolimund
Valerie Samson
Maarten Nachtegaal
Grigory Smolentsev
Maksym V. Kovalenko
Majed Chergui
Source :
Structural Dynamics, Vol 4, Iss 4, Pp 044002-044002-11 (2017)
Publication Year :
2017
Publisher :
AIP Publishing LLC and ACA, 2017.

Abstract

We report on an element-selective study of the fate of charge carriers in photoexcited inorganic CsPbBr3 and CsPb(ClBr)3 perovskite nanocrystals in toluene solutions using time-resolved X-ray absorption spectroscopy with 80 ps time resolution. Probing the Br K-edge, the Pb L3-edge, and the Cs L2-edge, we find that holes in the valence band are localized at Br atoms, forming small polarons, while electrons appear as delocalized in the conduction band. No signature of either electronic or structural changes is observed at the Cs L2-edge. The results at the Br and Pb edges suggest the existence of a weakly localized exciton, while the absence of signatures at the Cs edge indicates that the Cs+ cation plays no role in the charge transport, at least beyond 80 ps. This first, time-resolved element-specific study of perovskites helps understand the rather modest charge carrier mobilities in these materials.

Subjects

Subjects :
Crystallography
QD901-999

Details

Language :
English
ISSN :
23297778
Volume :
4
Issue :
4
Database :
Directory of Open Access Journals
Journal :
Structural Dynamics
Publication Type :
Academic Journal
Accession number :
edsdoj.14273744b56a45f19558a24ddca6a534
Document Type :
article
Full Text :
https://doi.org/10.1063/1.4971999