Understanding Singlet and Triplet Excitons in Acene Crystals from First Principles

ORAL

Abstract

Singlet fission, a process in which two triplet excitons are formed from a singlet exciton, has the potential to increase the solar cell efficiencies above 100\%. Efficient singlet fission has been reported in larger acene crystals, such as tetracene and pentacene, in part attributable to their low-lying triplet energies. In this work, we use many-body perturbation theory within the GW approximation and the Bethe-Salpeter equation approach to compute quasiparticle gaps, low-lying singlet and and triplet excitations, and optical absorption spectra across the entire acene family of crystals, from benzene to hexacene. We closely examine the degree of localization and charge-transfer character of the low-lying singlets and triplets, and their sensitivity to crystal environment, and discuss implications for the efficiency of singlet fission in this systems. This work supported by DOE and computational resources provided by NERSC.

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Authors

  • Tonatiuh Rangel Gordillo

    Lawrence Berkeley Natl Lab

  • Sahar Sharifzadeh

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

  • Leeor Kronik

    Department of Materials and Interfaces, Weizmann Institute of Science, Weizmann Institute of Science, Israel, Dept. Materials and Interfaces, Weizmann Institute, Weizmann Institute of Science, Department of Materials and Interfaces, Weizmann Institute of Science, Rehovoth 76100, Israel, Dept. of Materials and Interfaces, Weizmann Institute of Science, Rehovot 7610001, Department of Materials and Interfaces, Weizmann Institute of Science, Israel

  • 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