Dresden 2026 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 35: Optical Properties II
HL 35.9: Talk
Wednesday, March 11, 2026, 18:45–19:00, POT/0251
Half-saddle excitons in monolayer SnS2: a first-principles study — •Vinicius Alves Bastos1, Fulvio Paleari2, Eleonora Luppi3, Marco Gibertini1,2, and Alice Ruini1,2 — 1Dipartimento di Scienze Fisiche, Informatiche e Matematiche, UNIMORE, Modena (Italy) — 2CNR-Nano, Modena (Italy) — 3Laboratoire de Chimie Théorique, Sorbonne Université and CNRS, Paris (France)
Monolayer SnS2 has been demonstrated as a visible-light absorber with promising characteristics for applications in fuel cells and thin film photovoltaics [1]. Motivated by that, we have performed a first-principles study of bound excitons in this system within the GW-BSE formalism [2]. We have gone beyond previous works by analysing the exciton symmetries, electron-hole contributions, and transition dipoles. We find a richer structure of bound excitons than previously reported, e.g., deeply bound dark excitons with binding energies of about 0.9 eV and a very strong bright exciton at 2.9 eV, in good correspondence with the experimental absorption peak. Also, the bound excitons are localized around the direct band gap at the M point, which exhibits a saddle point at the top valence band and a minimum at the bottom conduction band. Consequently, we show that linearly polarized light can be used to completely select two of the three inequivalent M saddles, as previously demonstrated in graphene [3]. PNRR MUR project ECS_00000033_ECOSISTER
[1] Y. Sun et al., Angew. Chem. Int. Ed. 51, 8727 (2012). [2] D. Sangalli et al., J. Phys. Condens. Matter. 31, 325902 (2019). [3] S. Sharma et al., arXiv preprint, arXiv:2503.21376 (2025).
Keywords: excitons; GW-BSE; 2D materials; SnS2; saddletronics