Phonon-driven exciton scattering and dissociation from first principles*

Understanding the processes governing exciton dissociation is of central importance for optoelectronic devices such as solar cells. Recently, we have introduced a new ab initio approach to compute temperature-dependent phonon-driven exciton dissociation rates in optoelectronic materials [1,2]. In this talk, we will present a rigorous theoretical framework that unifies many-body perturbation theory (MBPT) and Fermi's golden rule (FGR), allowing us to derive rigorous expressions for phonon-driven exciton scattering rates. We will show how the formalism of rearrangement collision theory [3] can be applied to extend the usual FGR approach to describe phonon-driven exciton dissociation, as well as the FGR exciton-to-exciton and exciton-to-uncorrelated charge carrier scattering [4,5]. We will apply this framework to a model involving Wannier-Mott excitons in the limit of Fröhlich electron-phonon coupling [6] to demonstrate the relative importance of exciton dissociation and exciton-exciton scattering channels in polar materials. 

 

[1] Coveney, Haber, Alvertis, Neaton & Filip, In prep. (2023).

[2] Alvertis, Haber, Li, Coveney, Louie, Filip & Neaton, Submitted (2023).

[3] Sunakawa, Progr. Theo. Phys. 24, (1960).

[4] Antonius & Louie, PRB 105, 085111 (2022). 

[5] Marini, PRL 101, 106405 (2008).

[6] Filip, Haber & Neaton, PRL 127, 067401 (2021).