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Center for Nonlinear Studies |
Design of new organic materials for efficient optoelectronics relies on understanding their excited-state electronic structure, which is significantly influenced by both chemistry and solid-state morphology. While many organic materials have varying degrees of disorder, crystalline films with long-range order provide an opportunity to understand many fundamental physical properties relevant to electronics. Here, we will present first-principles many-body perturbation theory calculations of prototypical bulk organic semiconductors, aimed at understanding the influence of solid-state structure on the nature of optical excitations (excitons). Analysis of the electron-hole correlation function, computed within the GW and Bethe-Salpeter equation approach, allows us to quantify the extent and degree of charge transfer of the solid-state exciton. For rubrene and pentacene crystals, we predict that the solid-state exciton is highly sensitive to strain and changes in inter-molecular orientation induced by functionalization. These results indicate that the nature of excitons in organic semiconductors can be controlled by tuning solid-Ââ€state morphology, suggesting a new strategy for the design of optoelectronic materials.
Host: Sergei Tretiak