Jeffrey Neaton

Professor Jeffrey Neaton, University of California, Berkeley.  "Excited States and Energy Conversion in Organic Crystals and at Interfaces via First-Principles Methods."  Greater Boston Theoretical Chemistry Talk.  Abstract:  Organic crystals and hybrid interfaces are highly tunable, diverse classes of cheap-to-process materials with promise for next-generation optoelectronics. Further development of new materials requires new intuition that links atomic- and molecular-scale morphology to underlying excited-state properties and phenomena. I will review ab initio methods for calculating excited-state and transport properties of crystalline solids and interfaces, and show several applications, where we have used these methods to explain or drive new experiments. Specifically, I will cover the use of first-principles density functional theory with tuned hybrid functionals, and many-body perturbation theory within the GW approximation and the Bethe-Salpeter equation approach, for computing and understanding spectroscopic properties of acene crystals, including new insights into measured multiexciton phenomena such as singlet fission; as time permits, I will additionally share preliminary results on low-dimensional materials, such as 2d chalcogenides, and halide perovskites. I will also discuss multiple approaches to calculating level alignment at metal-molecule interfaces, where we have recently generalized optimally-tuned range-separated hybrid functionals to treat the electronic structure with accuracy comparable to many-body perturbation theory, and describe implications for single-molecule junction transport measurements