Ab-initio calculations of quasiparticle and excitonic properties of low band gap, polythiophene-based polymers

ORAL

Abstract

Electron donor polythiophene-derived polymers coupled with electron acceptor C60 compounds are the basis for the state-of-the-art organic photovoltaic (OPV) technology. However, with an incident photon to converted electron efficiency of only 5\%, OPV cells are not yet competitive with conventional inorganic semiconductor technology. One of the limitations is the relatively high energy gap of polythiophene which precludes the absorption of infrared photons. In this work, using the GW approximation and solving the Bethe-Salpeter equation, we compare results of the quasiparticle and excitonic properties of thiophene-, vinylene- and cyanovinylene-based copolymers with lower energy band gaps than polythiophene. The energy band alignments of the polymers and the C60 molecule are also discussed.

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Authors

  • Filipe Ribeiro

    UC Berkeley, and LBL

  • Georgy Samsonidze

    UC Berkeley, and LBL

  • Steven G. Louie

    Department of Physics, UC Berkeley, Department of Physics, University of California at Berkeley and Materials Sciences Division of Lawrence Berkeley National Laboratory, UC Berkeley, and LBL, UC Berkeley, Dept. of Physics, UC Berkeley; MSD, LBNL, Department of Physics, University of California at Berkeley and Materials Sciences Division, Lawrence Berkeley National Laboratory, Molecular Foundry, LBNL and Physics Dept, UC Berkeley, UC Berkeley and LBNL, University of California at Berkeley and Lawrence Berkeley National Laboratory

  • Marvin L. Cohen

    UC Berkeley, Lawrence Berkeley National Laboratory, Department of Physics, U C Berkeley, Material Science Divsion, LBNL, epartment of Physics, UC Berkeley, University of California, Berkeley, UC Berkeley, and LBL, UC Berkeley, UC Berkeley \& LBNL