Impact of Phonons on Electron-Hole Interactions in Semiconductors and Insulators.*

In this talk, I will introduce our recent ab initio generalization of the Bethe-Salpeter equation (BSE) [2] to include phonon contributions to the dielectric screening and its impact on the interaction of photoexcited electron-hole pairs (excitons) in semiconductors and insulators (including standard III-V semiconductors, but also more complex ternary halide perovskites) [1]. I will first present our initial approximate implementation of this method, based on Wannier-Mott (hydrogenic) excitons and Frohlich electron-phonon coupling, and compare this with our recently implemented general formalism. I will discuss this comparison in the context of common approximations and give an outlook on future applications of this method. Further, I will give an overview of recent studies of excitons in other materials from the halide perovskite family, and discuss the role of structural and chemical heterogeneity on the photophysical properties of this complex family of materials.

[1] Rohlfing & Louie, Phys. Rev. Lett. 81, 2312 (1998).

[2] Filip, Haber & Neaton, Phys. Rev. Lett., 127, 067401 (2021).