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.

*This work is supported by the DOE; computational resources at NERSC.

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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