Jeffrey B. Neaton
Department of Physics, University of California, Berkeley
Materials Sciences Division, Lawrence Berkeley National Laboratory
Kavli Energy Nanosciences Institute at Berkeley

The ability to synthesize and probe new classes of complex photoactive materials with tunable structure and chemical composition – such as halide perovskites, molecular solids, few-layer van
der Waals heterostructures, and more – has driven the development of new theory, computational methods, and intuition for predicting their photophysics. In these novel semiconductors,
photoexcited correlated electron-hole pairs, or excitons, can be strongly bound and do not conform to simple models, and new understanding is needed to interpret the behavior of these
quasiparticles. Here, I will discuss advances in first-principles calculations – based on density functional theory and field-theoretic Green's function formalisms – that have enabled predictive understanding of excitons in these complex systems, including how they are influenced by lattice structure and dynamics, temperature, dielectric screening, and carrier concentration. I will share
recent calculations for multiple systems, comparing them with experiments, and discuss new intuition for the nature and kinetics of excitons with relevance to optoelectronic devices and renewable energy applications.