Excitons in functional materials: A computational many-body perspective

In emerging photovoltaic and photocatalytic systems, correlated electron-hole excitations called excitons often serve as carriers in energy transfer processes. Structural complexities, such as reduced dimensionalities, interface compositions, and the presence of impurities, are closely coupled to exciton properties and decay processes. In this talk, I will describe a computational approach to study the excitonic phenomena in materials of complex structures, using ab initio many-body perturbation theory. I will specifically discuss many-body effects on optical and exciton phenomena in and between layered transition metal dichalcogenides, where a mixed nature of electron-hole interactions control the optical signatures and structurally-tunable selection rules. I will further present a new approach to study exciton decay processes in such functional materials from first principles, employing a rate-equation perturbative scheme to exciton-exciton and exciton-phonon interactions.