In this Letter, we studied the nature of exciton interactions and lifetimes in the WS2/Reduced graphene oxide (WS2/RGO) heterostructure using femtosecond transient absorption spectroscopy. Our studies demonstrate that the key optoelectronic properties of the heterostructure in the strongly coupled regime are substantially different from those of the control WS2 and RGO, promoting the mixing of electronic states at the interfaces leading to the suppression of direct excitons. The combined effect of midgap states and donor levels induced by RGO below the conduction band of WS2 along with the charge transfer to these trap states forms long-lived non-decaying excitons existing more than 1.5 ns, an ultimate time limit in our experiment. These results identify the interfacial trap states as a useful degree of freedom to engineer the lifetime of trapped excitons.
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5 October 2020
Research Article|
October 06 2020
Observation of room-temperature long-lived trapped exciton in WS2/RGO heterostructure
Anirban Mondal;
Anirban Mondal
1
Department of Physics, Indian Institute of Science Education and Research
, Bhopal-462066, India
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Rajesh Kumar Yadav
;
Rajesh Kumar Yadav
1
Department of Physics, Indian Institute of Science Education and Research
, Bhopal-462066, India
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Megha Shrivastava;
Megha Shrivastava
1
Department of Physics, Indian Institute of Science Education and Research
, Bhopal-462066, India
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Chandra Sekhar Rout
;
Chandra Sekhar Rout
2
Centre for Nano and Material Sciences, Jain University
, Jain Global Campus, Jakkasandra, Ramanagaram, Bangalore-562112, India
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Debjani Karmakar;
Debjani Karmakar
a)
3
Technical Physics Division, Bhabha Atomic Research Centre
, Mumba-400085, India
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K. V. Adarsh
K. V. Adarsh
a)
1
Department of Physics, Indian Institute of Science Education and Research
, Bhopal-462066, India
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Appl. Phys. Lett. 117, 142104 (2020)
Article history
Received:
July 02 2020
Accepted:
September 20 2020
Citation
Anirban Mondal, Rajesh Kumar Yadav, Megha Shrivastava, Chandra Sekhar Rout, Debjani Karmakar, K. V. Adarsh; Observation of room-temperature long-lived trapped exciton in WS2/RGO heterostructure. Appl. Phys. Lett. 5 October 2020; 117 (14): 142104. https://doi.org/10.1063/5.0020637
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