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  4. The Role of Excitons and Free Charges in the Excited-State Dynamics of Solution-Processed Few-Layer MoS
 
research article

The Role of Excitons and Free Charges in the Excited-State Dynamics of Solution-Processed Few-Layer MoS

Tsokkou, Demetra
•
Yu, Xiaoyun  
•
Sivula, Kevin  
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2016
Journal of Physical Chemistry C

Solution-processed semiconducting transition metal dichalcogenides are emerging as promising two-dimensional materials for photovoltaic and optoelectronic applications. Here, we have used transient absorption spectroscopy to provide unambiguous evidence and distinct signatures of photogenerated excitons and charges in solution-processed few-layer MoS2 nanoflakes (10–20 layers). We find that photoexcitation above the direct energy gap results in the ultrafast generation of a mixture of free charges in direct band states and of excitons. While the excitons are rapidly trapped, the free charges are long-lived with nanosecond recombination times. The different signatures observed for these species enable the experimental extraction of the exciton binding energy, which we find to be ∼80 meV in the nanoflakes, in agreement with reported values in the bulk material. Carrier-density-dependent measurements bring new insights about the many-body interactions between free charges resulting in band gap renormalization effects in the few-layer MoS2 nanoflakes.

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Type
research article
DOI
10.1021/acs.jpcc.6b09267
Web of Science ID

WOS:000385607000059

Author(s)
Tsokkou, Demetra
Yu, Xiaoyun  
Sivula, Kevin  
Banerji, Natalie
Date Issued

2016

Publisher

American Chemical Society

Published in
Journal of Physical Chemistry C
Volume

120

Issue

40

Start page

23286

End page

23292

Editorial or Peer reviewed

REVIEWED

Written at

EPFL

EPFL units
LIMNO  
Available on Infoscience
October 14, 2016
Use this identifier to reference this record
https://infoscience.epfl.ch/handle/20.500.14299/129752
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