Phonon-Assisted Radiative Lifetimes and Exciton Dynamics from First Principles

Exciton-phonon interactions are crucial for understanding phonon-assisted radiative recombination and exciton dynamics in solids. We present an ab-initio framework for computing the phonon-assisted photoluminescence (PL) spectrum and radiative lifetime at finite temperatures.

From the solution of the Bethe-Salpeter equation (BSE), we define an effective excitonic Hamiltonian that includes both exciton-photon and exciton-phonon interactions, allowing us to calculate radiative lifetimes using second-order time-dependent perturbation theory. Additionally, we performed real-time Boltzmann transport equation (BTE) simulations to study time-resolved photoluminescence (TRPL), providing direct insights into ultrafast exciton thermalization and quantum scattering pathways.

This approach allows for a detailed microscopic understanding of exciton dynamics and phonon-mediated relaxation mechanisms. Our results provide valuable perspectives on phonon-assisted many-body interactions and their influence on optical properties, which are essential for understanding light-emitting processes in optoelectronic materials.