| Abstract: | Understanding excited-state dynamics in functional materials is essential for applications across optoelectronics and photophysics. In particular, exciton relaxation mechanisms and lifetimes are coupled to optical selection rules stemming from the underlying atomistic structure. In this talk, I will present our recent studies of excited-state dynamics in molecular crystals and transition metal dichalcogenides using first-principles approaches based on many-body perturbation theory. I will demonstrate the connection between time-resolved exciton propagation and material structure, dimensionality, and symmetry, and present our new approach to compute exciton propagation in these systems. I will further demonstrate direct connections between exciton dispersion and its relaxation mechanisms, offering a predictive theoretical pathway to tune the underlying exciton dynamics using structural design. |