TYC Seminar: Ab Initio Modeling of Exciton-Phonon Interactions in Emerging Materials: Applications and Recent Developments

TYC Seminar: Ab Initio Modeling of Exciton-Phonon Interactions in Emerging Materials: Applications and Recent Developments Share on X

Jonah Haber, Stanford University

Excitons — correlated electron-hole pairs generated upon photoexcitation — provide a fundamental framework for describing low-energy optical excitations in semiconductors and insulators. Understanding how these quasiparticles interact with their environment, particularly their coupling to atomic lattice vibrations (phonons), is key to optimizing materials for next-generation optoelectronic devices, including photovoltaics, LEDs, and quantum emitters.

In this seminar, I will present our recent efforts to develop and apply ab initio methods, grounded in many-body perturbation theory, to study exciton-phonon interactions in complex materials. I will begin by discussing various ways in which phonons can couple to excitons, including how phonons renormalize exciton binding energies in halide perovskites and influence exciton line shapes in two-dimensional transition metal dichalcogenides.

Motivated by the inherent complexity of modeling coupled exciton–phonon systems, the second part of the talk will introduce our recent work on Maximally Localized Exciton Wannier Functions (MLXWFs). This new formalism provides a compact, real-space representation of exciton states, offering  insights into exciton band dispersion and  topology, and paving the way for scalable modeling of exciton dynamics. I will demonstrate the utility of this framework through a detailed case study on how lattice vibrations influence exciton transport in organic semiconductors—highlighting how MLXWFs open new avenues for understanding exciton behavior at the microscopic level.

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