Dresden 2020 – scientific programme

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DS: Fachverband Dünne Schichten

DS 11: 2D semiconductors and van der Waals heterostructures II (joint session HL/DS)

DS 11.6: Talk

Monday, March 16, 2020, 16:30–16:45, POT 81

Theory of optical absorption in monolayers of transition metal dichalcogenides — •Frank Lengers, Doris E. Reiter, and Tilmann Kuhn — Westfälische Wilhelms-Universität Münster, Wilhelm-Klemm Str. 10, 48149 Münster

Monolayers of transition metal dichalcogenides are attractive materials for optoelectronics due to their strong exciton-light interaction. At the same time the interaction of excitons and phonons plays a crucial role in these systems leading to strong phonon-assisted processes in optical experiments.

In this contribution different theoretical methods for the computation of linear absorption spectra in monolayers of transition metal dichalcogenides are investigated. To be specific, we consider the spectra of MoSe₂ using either a correlation expansion in 2nd or 4th Born Approximation or an approximation closely related to the time convolution less master equation used in the theory of open quantum systems. We show that the 2nd Born Approximation gives poor results for elevated temperatures due to the exceptionally strong exciton-phonon interaction. On the other hand the time convolution less approach gives suprisingly good results despite its simplicity when compared to higher-order correlation expansion. This rather easy method can therefore be readily applied to the class of atomically thin solids where strong carrier-phonon interaction plays a vital role.