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Exciton coherence times and diffusion constants in molecular crystals from exciton-phonon coupling with an ab initio GW-BSE approach

ORAL

Abstract

Predictive theories of exciton dynamics are of growing importance as increasingly complex materials, with strong electron-hole interactions, are used in device physics applications. For instance, in organic photovoltaics, an important part of energy conversion processes involves the diffusion of a photo-excited exciton to donor-acceptor interfaces where charge separation can occur. To quantitatively understand exciton dynamics, a microscopic theory of exciton-phonon interactions is required. Here, we describe an ab initio framework for computing exciton-phonon matrix elements, using density functional perturbation theory in conjunction with many-body perturbation theory within the GW plus Bethe-Salpeter equation (BSE) approach. We apply this formalism to crystalline tetracene, a prototypical organic semiconductor with strong electron-hole interactions. We compare and contrast how low-lying spin singlet and triplet excitons couple to the phonon field. We perturbatively compute phonon-limited exciton coherence times throughout the Brillioun zone and report exciton diffusion constants, evaluated using the relaxation time approximation. In all cases, we compare with experimental measurements, where available.

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Presenters

  • Jonah Haber

    Physics, UC Berkeley, Physics, University of California, Berkeley

Authors

  • Jonah Haber

    Physics, UC Berkeley, Physics, University of California, Berkeley

  • Felipe Da Jornada

    Materials Science and Engineering, Stanford University

  • Sivan Refaely-Abramson

    Department of Materials and Interfaces, Weizmann Institute of Science, Materials and Interfaces, Weizmann Institute of Science

  • Gabriel Antonius

    Hydrogen Research Institute, Université du Québec à Trois-Rivières, Département de Chimie, Biochimie et Physique, Université du Québec à Trois-Rivières, Trois-Rivières, Hydrogen Research Institute, Université du Québec à Trois-Riviéres

  • Steven Louie

    University of California at Berkeley, and Lawrence Berkeley National Laboratory, Department of Physics, University of California, Berkeley, Berkeley, California 94720, USA and Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, C, University of California, Berkeley, Department of Physics, University of California, Berkeley, Lawrence Berkeley National Laboratory and University of California at Berkeley, Department of Physics, University of California at Berkeley and Lawrence Berkeley National Laboratory, Department of Physics, UC Berkeley, Physics, Unviersyt of Calfornia, Berkeley, Physics, University of California, Berkeley, Physics, University of California, Berkeley and Lawrence Berkeley National Lab

  • Jeffrey B Neaton

    Lawrence Berkeley National Laboratory, Physics, UC Berkeley, Kavli Energy Nanoscience Institute at Berkeley, Physics, University of California, Berkeley, Department of Physics, University of California, Berkeley, University of California, Berkeley; Molecular Foundry, Lawrence Berkeley National Laboratory; Kavli Energy Nanosciences Institute at Berkeley, University of California, Berkeley, Lawrence Berkeley National Lab