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

Open access
Date
2017-07Type
- Journal Article
Citations
Cited 54 times in
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Cited 55 times in
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ETH Bibliography
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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. Show more
Permanent link
https://doi.org/10.3929/ethz-b-000125056Publication status
publishedExternal links
Journal / series
Structural DynamicsVolume
Pages / Article No.
Publisher
American Institute of PhysicsOrganisational unit
03934 - Kovalenko, Maksym / Kovalenko, Maksym
Funding
306733 - Chemically Engineered Nanocrystal Solids (EC)
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Citations
Cited 54 times in
Web of Science
Cited 55 times in
Scopus
ETH Bibliography
yes
Altmetrics