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HL: Fachverband Halbleiterphysik

HL 5: Optical Properties I

HL 5.1: Vortrag

Montag, 18. März 2024, 09:30–09:45, EW 561

Can we predict exciton binding energies from ground-state properties? — •Malte Grunert, Max Großmann, and Erich Runge — Theoretische Physik I, TU Ilmenau, Germany

Accurate ab-initio exciton binding energies are commonly obtained by solving the Bethe-Salpeter equation on the results of an expensive quasiparticle calculation. Accurate ground-state properties, however, are often much cheaper to evaluate. Establishing reliable connections between cheap ground-state properties and expensive exciton binding energies is therefore desirable - ideally, we would be able to predict the latter based on the former!

A well-known method of predicting exciton binding energies is the Wannier-Mott model, which is however not directly applicable to more localized excitons. Several alternative approaches have been put forward proposing that e.g., the colocalization of electron and hole states [1] or a high JDOS around the bandgap [2] correlates with increasing exciton binding strength.

We investigate and possibly verify these proposed links between exciton binding energies and ground-state properties in several dozen materials across different classes of materials, including simple narrow- and wide-bandgap semiconductors, insulators, and more complex compounds such as transition metal chalcogenides and perovskites. We critically evaluate emerging trends and attempt predictions going beyond the Wannier-Mott model.

[1] M. Dvorak et al., Phys. Rev. Lett., 2013, 110, 016402

[2] E. Baldini et al., Nat. Commun. 2017, 8, 13

Keywords: Excitons; DFT; High-Throughput