Exploring the Influence of Dynamic Disorder on Excitons in Solid Pentacene

ORAL

Abstract

A complete understanding of the spectroscopic and charge transport properties of organic semiconductors requires knowledge of the role of thermal fluctuations and dynamic disorder. We present a first-principles theoretical study aimed at understanding the degree to which dynamic disorder at room temperature results in energy level broadening and excited-state localization within bulk crystalline pentacene. Ab initio molecular dynamics simulations are well-equilibrated for 7-9 ps and tens of thousands of structural snapshots, taken at 0.5 fs intervals, provide input for many-body perturbation theory within the GW approximation and Bethe-Salpeter equation (BSE) approach. The GW-corrected density of states, including thousands of snapshots, indicates that thermal fluctuations significantly broaden the valence and conduction states by \textgreater 0.2 eV. Additionally, we investigate the nature and energy of the lowest energy singlet and triplet excitons, computed for a set of uncorrelated and energetically preferred structures.

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Authors

  • Zhiping Wang

    Molecular Foundry, Lawrence Berkeley National Laboratory

  • Sahar Sharifzadeh

    Lawrence Berkeley National Laboratory, Molecular Foundry, LBNL, Molecular Foundry, Lawrence Berkeley National Laboratory, Molecular Foundry at LBNL, Lawrence Berkeley Natl Lab

  • Peter Doak

    Department of Chemistry, UC-Berkeley; Molecular Foundry LBNL, Molecular Foundry, Lawrence Berkeley National Laboratory and Department of Chemistry, University of California, Berkeley

  • Zhenfei Liu

    Molecular Foundry, Lawrence Berkeley National Laboratory, Molecular Foundry, Lawrence Berkeley National Lab

  • Jeffery B. Neaton

    Department of Physics, UC-Berkeley; Molecular Foundry, LBNL, Molecular Foundry, LBNL, Department of Physics, UC Berkeley, Molecular Foundry, LBNL and Dept. Physics, UC Berkeley, Molecular Foundry, Lawrence Berkeley National Laboratory and Department of Physics, University of California, Berkeley, UC Berkeley, Dept of Physics; Materials Science Division, LBNL, Molecular Foundry, Lawrence Berkeley National Laboratory; Department of Physics, UC-Berkeley, The Molecular Foundry, LBNL; Dept. of Physics, University of California, Berkeley, Lawrence Berkeley National Laboratory, UC Berkeley Department of Physics, Lawrence Berkeley Natl Lab and Department of Physics, UC-Berkeley, Physics Department, UC Berkeley; Molecular Foundry, Lawrence Berkeley National Lab