Electronic Disorder in Substituted Fullerenes
Naga Rajesh Tummala,1 Shabaan Ali K. Elroby,2 Chad Risko3,1, Veaceslav Coropceanu1, Saadullah G. Aziz2, and Jean-Luc Brédas4,1
1School of Chemistry and Biochemistry &Center for Organic Photonics and Electronics,
Georgia Institute of Technology, Atlanta, Georgia 30332-0400
2Department of Chemistry, King Abdulaziz University
Jeddah 21589, Saudi Arabia
3Department of Chemistry & Center for Applied Energy Research (CAER)
University of Kentucky, Lexington, Kentucky 40506-0055, USA
4Solar and Photovoltaics Energy Research Center
Division of Physical Sciences and Engineering
King Abdullah University of Science and Technology
Thuwal 23955-6900, Kingdom of Saudi Arabia
Fullerenes are ubiquitously used in organic photovoltaics and electronics for their ability to isotropically pack in three dimensions. However, with the proliferation of the number of fullerene derivatives there is a need to understand how these substitutions affect the electronic and structural disorder resulting mainly from the presence of amorphous regions within the films. Understanding the disorder based on substitutions can lead to more efficient design strategies and improved devices by providing increased fundamental understanding. By using molecular dynamics (MD) simulations and density functional theory (DFT) calculations to evaluate the energetic disorder (the distribution of site energies) of varying adducts of [6,6]-phenyl-C60-butyric acid methyl ester (PCBM)1 and indene-C60, we compare and contrast different components to the site energies and disorder. We also delineate the fundamental difference between the packing in the different (mono, bis, and tris) adducts of these fullerene derivatives.
We gratefully acknowledge the support of various parts of this work by the Deanship of Scientific Research of King Abdulaziz University under an International Collaboration Grant (Award No. D-001-433) and the Office of Naval Research (Award No. N00014-14-1-0171).
(1) Tummala, N. R.; Mehraeen, S.; Fu, Y. T.; Risko, C.; Bredas, J. L. Adv. Funct. Mater. 2013, 23, 5800.