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The competition between the radiative and nonradiative lifetimes determines the optical quantum yield and plays a crucial role in the potential optoelectronic applications of transition metal dichalcogenides (TMDCs). Here, we show that, in the presence of free carriers, an additional nonradiative decay channel opens for excitons in TMDC monolayers. Although the usual Auger decay channel is suppressed at low doping levels by the simultaneous momentum and energy conservation laws, exciton–phonon coupling relaxes this suppression. By solving a Bethe–Salpeter equation, we calculate the phonon-assisted Auger decay rates in four typical TMDCs as a function of doping, temperature, and dielectric environment. We find that even for a relatively low doping of 1012 cm−2, the nonradiative lifetime ranges from 16 to 165 ps in different TMDCs, offering competition to the radiative decay channel.
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Exciton Dynamics in 2D Transition Metal Dichalcogenides
Abstract 2D transition metal dichalcogenides (TMDCs) have emerged as a promising class of materials for broad applications. The physical properties of TMDCs are dominated by strong excitonic effects, which critically determine the performance of photonic and optoelectronic devices. In this Review, the current state of research on exciton dynamics in TMDCs is summarized, discussed common optical characterization techniques, and analyzed factors that influence exciton behaviors, such as thickness, dielectric environment, strain, and heterostructure configuration. Throughout this work, the challenges and opportunities for future research in this rapidly evolving field are also highlighted.
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- Award ID(s):
- 2416149
- PAR ID:
- 10573903
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Advanced Optical Materials
- Volume:
- 13
- Issue:
- 11
- ISSN:
- 2195-1071
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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