Berlin 2024 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 20: Focus Session: Young Semiconductor Forum

HL 20.1: Invited Talk

Tuesday, March 19, 2024, 09:30–10:00, EW 203

Coherent ultrafast exciton dynamics mediated by vibronic couplings — •Antonietta De Sio — Universität Oldenburg

The ultrafast dynamics of non-equilibrium excitations in functional materials and nanostructures, triggered by light-matter interaction, rely on a complex interplay between electronic and nuclear motion. Vibronic couplings may significantly influence the initial energy flow and charge motion following photoexcitation. In-depth understanding of the underlying physics of photoinduced ultrafast phenomena is thus crucial for steering nanoscale energy and charge transport, for the rationale design of efficient new materials and development of quantum technologies. Most of the mechanisms underlying these processes occur on only few 100s-fs timescales, thus demanding methods combining high time resolution and the ability to unravel couplings. Here I would like to give an overview of our most recent results showing how two-dimensional electronic spectroscopy with <10 fs time resolution provides detailed new insight into the ultrafast coherent exciton dynamics in technologically relevant materials, spanning from organic semiconductors to perovskites, and the fundamental role of vibronic couplings in these dynamics[1-2]. Specifically, we recently discovered intermolecular conical intersections in thin films of quadrupolar dyes governing ultrafast energy relaxation within <50 fs. In halide perovskites, we recently unveiled exciton Rabi oscillations driven by coherent phonon fields. Our results also suggest strategies to control ultrafast coherent dynamics in functional materials. [1] De Sio et al, Nature Nano. 16, 63 (2021) [2] Nguyen et al, Nature Comm. 14, 1047 (2023)