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SYWS: Symposium Quantum 2D-Moiré and Rhombohedral van-der-Waals Systems

SYWS 1: Quantum 2D-Moiré and Rhombohedral van-der-Waals Systems

SYWS 1.2: Invited Talk

Thursday, September 11, 2025, 11:15–11:45, ZHG008

Exciton dynamics in 2D-moiré materials in space and time — •Stefan Mathias — I. Physikalisches Institut, Georg-August-Universität Göttingen, 37077 Göttingen, Germany

In 2D semiconducting quantum materials, organic semiconductors and their heterostructures, the energy of absorbed light is stored in Coulomb-bound electron-hole pairs, i.e. excitons. For future technological applications of these classes of materials, for instance in optoelectronics and for energy harvesting, it is crucial to study the initial light-matter interaction and the subsequent relaxation and dissipation processes at the fundamental level [1] and on the relevant length and time scales [2].

I will present the ultrafast formation dynamics of bright and dark excitons in different moiré materials in space and time [3]. In particular, I will report on the identification of a key signature of the moiré superlattice that is imprinted on the momentum-resolved interlayer exciton photoemission signal [4,5]. Furthermore, I will present photoemission exciton tomography [6] that allows us to study ultrafast charge transfer from TMD to organic layers, and to disentangle multiorbital contributions in the exciton formation in the 2D moiré - organic semiconductor heterostructures.

References: [1] Merboldt et al., Nature Physics (2025). [2] Schmitt et al., Nature Photonics 19, 187 (2025). [3] Reutzel et al., Adv. in Phys. X 9,, 2378722 (2024) [4] Schmitt et al., Nature 608, 499 (2022). [5] Bange et al., Science Adv. 10, eadi1323 (2024). [6] Bennecke et al., Nature Comm. 15, 1804 (2024).

Keywords: 2D moiré materials; ultrafast dynamics; Photoelectron spectroscopy; heterostructures