CUED Publications database

Photo-Induced Bandgap Renormalization Governs the Ultrafast Response of Single-Layer MoS2.

Pogna, EAA and Marsili, M and De Fazio, D and Dal Conte, S and Manzoni, C and Sangalli, D and Yoon, D and Lombardo, A and Ferrari, AC and Marini, A and Cerullo, G and Prezzi, D (2016) Photo-Induced Bandgap Renormalization Governs the Ultrafast Response of Single-Layer MoS2. ACS Nano, 10. pp. 1182-1188.

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Transition metal dichalcogenides (TMDs) are emerging as promising two-dimensional (2D) semiconductors for optoelectronic and flexible devices. However, a microscopic explanation of their photophysics, of pivotal importance for the understanding and optimization of device operation, is still lacking. Here, we use femtosecond transient absorption spectroscopy, with pump pulse tunability and broadband probing, to monitor the relaxation dynamics of single-layer MoS2 over the entire visible range, upon photoexcitation of different excitonic transitions. We find that, irrespective of excitation photon energy, the transient absorption spectrum shows the simultaneous bleaching of all excitonic transitions and corresponding red-shifted photoinduced absorption bands. First-principle modeling of the ultrafast optical response reveals that a transient bandgap renormalization, caused by the presence of photoexcited carriers, is primarily responsible for the observed features. Our results demonstrate the strong impact of many-body effects in the transient optical response of TMDs even in the low-excitation-density regime.

Item Type: Article
Uncontrolled Keywords: many-body perturbation theory real-time simulations transient absorption spectroscopy transition metal dichalcogenides two-dimensional materials
Divisions: Div B > Solid State Electronics and Nanoscale Science
Div B > Photonics
Depositing User: Cron Job
Date Deposited: 17 Jul 2017 18:58
Last Modified: 22 Jun 2018 20:32