Strongly bound excitons in monolayer PtS2 and PtSe2

Abstract
Based on first-principles calculations, the structural, electronic, and optical properties of monolayers PtS2 and PtSe2 are investigated. The bond stiffnesses and elastic moduli are determined by means of the spring constants and strain-energy relations, respectively. Dynamic stability is confirmed by calculating the phonon spectra, which shows excellent agreement with experimental reports for the frequencies of the Raman-active modes. The Heyd-Scuseria-Ernzerhof functional results in electronic bandgaps of 2.66 eV for monolayer PtS2 and 1.74 eV for monolayer PtSe2. G0W0 calculations combined with the Bethe-Salpeter equation are used to predict the optical spectra and exciton binding energies (0.78 eV for monolayer PtS2 and 0.60 eV for monolayer PtSe2). It turns out that the excitons are strongly bound and therefore very stable against external perturbations.

Citation
Sajjad M, Singh N, Schwingenschlögl U (2018) Strongly bound excitons in monolayer PtS2 and PtSe2. Applied Physics Letters 112: 043101. Available: http://dx.doi.org/10.1063/1.5010881.

Acknowledgements
The research reported in this publication was supported by funding from the King Abdullah University of Science and Technology (KAUST).

Publisher
AIP Publishing

Journal
Applied Physics Letters

DOI
10.1063/1.5010881

Additional Links
http://aip.scitation.org/doi/10.1063/1.5010881

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