Berlin 2018 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 83: 2D Materials (Symposium and Joint Session with HL and O): Session III (joint session DS/CPP/HL)

CPP 83.6: Vortrag

Freitag, 16. März 2018, 11:15–11:30, H 2032

Disclosing the nature of excitons in van der Waals materials: The role of layer stacking in hexagonal boron nitride — Wahib Aggoune^1,2, •Caterina Cocchi^2,3, Dmitrii Nabok^2,3, Karim Rezouali¹, Mohamed Akli Belkhir¹, and Claudia Draxl^2,3 — ¹Laboratoire de Physique Théorique, Faculté des Sciences Exactes, Université de Bejaia, 06000 Bejaia, Algeria — ²Institut fur Physik and IRIS Adlershof, Humboldt-Universitat zu Berlin, Berlin, Germany — ³European Theoretical Spectroscopic Facility (ETSF)

With the example of bulk hexagonal boron-nitride, a prototypical van der Waals (vdW) crystal, we demonstrate that the electronic and optical properties of these materials can be tuned by layer patterning. By modifying the stacking, energy, intensity, and character of the electron-hole (e-h) pairs can be selectively modulated. Depending on the specific layer arrangement, lowest-energy excitons are localized within a single layer or delocalized in the three-dimensional space. Only in specific stackings charge-transfer e-h pairs appear above the absorption onset, triggered by the spatial distribution of the electronic states involved. Our results, obtained within a first-principles many-body framework, provide all the ingredients to identify, predict, and tailor the character of the e-h pairs in vdW materials.