Phonon-Induced Ultrafast Exciton Decomposition in Transition Metal Dichalcogenides: An Ab Initio Approach

Underlying relaxation processes following light excitation in semiconductors are key in materials-based quantum information science. These processes are broadly studied in transition metal dichalcogenides (TMDs), where constructed atomistic design allows for tunable excited-state properties, lifetime, and stability. In this talk, I will describe our new ab initio theoretical approach to compute exciton decomposition in these systems, paving a route to explore microscopic processes occurring between optical absorption and emission. Our approach, based on a Lindblad density matrix formalism, captures quantum many-body effects by combining predictive assessment of the exciton states and a band-resolved analysis of their scattering with phonons. In particular, we explore the effect of mixed exciton states on both momentum and spin transitions, and study how these vary as a function of layer composition. Our findings supply an understanding of the underlying exciton relaxation mechanisms, offering new insights into the concept of excitons as stable quantum states in functional materials.