Regensburg 2025 – scientific programme

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SYIS: Symposium Progress and Challenges in Modelling Electron-Phonon Interaction in Solids

SYIS 1: Progress and Challenges in Modelling Electron-Phonon Interaction in Solids

SYIS 1.2: Invited Talk

Tuesday, March 18, 2025, 10:00–10:30, H1

Exciton-phonon dynamics from first principles — •Enrico Perfetto — Physics Department University of Rome Tor Vergata

Exciton dynamics, encompassing ultrafast photogeneration, diffusion, and thermalization, plays a fundamental role in optoelectronic, photovoltaic, and photocatalytic processes. In this talk we discuss a novel many-body approach to describe exciton dynamics from first-principles. We show that the introduction of an auxiliary exciton species, termed 'irreducible exciton', is crucial to formulate a theory free from overscreening of the electron-phonon interaction. The resulting Excitonic Bloch Equations, while having the same computational cost as the well-known Excitonic Boltzmann Equations, enable a comprehensive description of the temporal evolution of coherent, irreducible, and incoherent excitons during and after the optical excitation.

Within this framework, we explore the real-time dynamics of exciton formation, elucidating the mechanism by which quasi-free electron-hole pairs, generated by above-gap photoexcitation, are dynamically converted into bound excitons.

Keywords: Exciton dynamics; Exciton-phonon coupling