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Title: Doping effect on photoabsorption and charge-separation dynamics in light-harvesting organic molecule

Using ab-initio theoretical methods, we demonstrate possible enhancement of photo-conversion efficiency of an organic solar cell via intentional doping in molecular graphene-fullerene heterojunction [the hexabenzocoronene (HBC)-triethylene glycol (TEG)–C{sub 60} molecule]. Photoabsorption analysis indicates oxygen substitution into HBC leads to an extension of the spectra up to an infrared regime. A quantum-mechanical molecular dynamics simulation incorporating nonadiabatic electronic transitions reveals that a dissociated charge state (D{sup +} and A{sup -}) in the O-doped system is more stable than the pristine case due to the presence of an effective barrier by the TEG HOMO/LUMO level. We also find that oxygen doping in HBC enhances the intermolecular carrier mobility after charge separation. On the other hand, the pristine molecule undergoes rapid recombination between donor and acceptor charges at the interface. These analyses suggest that the graphene oxidation opens a new window in the application of organic super-molecules to solar cells.
Authors:
 [1] ;  [2] ;  [3] ;  [4]
  1. Research Center for Condensed Matter Physics, Department of Civil Engineering and Urban Design, Hiroshima Institute of Technology, Hiroshima 731-5193 (Japan)
  2. Department of Electrical and Electronic Engineering, Okayama University, Okayama 700-8530 (Japan)
  3. Department of Physics, Kumamoto University, Kumamoto 860-8555 Japan (Japan)
  4. Collaboratory for Advanced Computing and Simulations, Department of Computer Science, Department of Physics & Astronomy, Department of Chemical Engineering & Materials Science, Department of Biological Sciences, University of Southern California, CA90089-024 (United States)
Publication Date:
OSTI Identifier:
22492415
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Advances; Journal Volume: 6; Journal Issue: 1; Other Information: (c) 2016 Author(s); Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; CARRIER MOBILITY; CHARGE STATES; DOPED MATERIALS; FULLERENES; GRAPHENE; HETEROJUNCTIONS; INTERFACES; MOLECULAR DYNAMICS METHOD; MOLECULES; ORGANIC SOLAR CELLS; OXIDATION; OXYGEN; PHOTOVOLTAIC CONVERSION; QUANTUM MECHANICS; RECOMBINATION; VISIBLE RADIATION