The electronic structure at organic/organic interfaces plays a key role, among others, in defining the quantum efficiency of organics-based photovoltaic cells. Here, we perform quantum-chemical and microelectrostatic calculations on molecular aggregates of various sizes and shapes to characterize the interfacial dipole moment at pentacene/C60 heterojunctions. The results show that the interfacial dipole mostly originates in polarization effects due to the asymmetry in the multipolar expansion of the electronic density distribution between the interacting molecules, rather than in a charge transfer from donor to acceptor. The local dipole is found to fluctuate in sign and magnitude over the interface and appears as a sensitive probe of the relative arrangements of the pentacene and C60 molecules (and of the resulting local electrical fields sensed by the molecular units). © 2010 American Chemical Society.
|Original language||English (US)|
|Number of pages||10|
|Journal||The Journal of Physical Chemistry C|
|State||Published - Feb 2 2010|
Bibliographical noteKAUST Repository Item: Exported on 2020-10-01
Acknowledged KAUST grant number(s): KUS-C1-015-21
Acknowledgements: The authors acknowledge the European projects MINOTOR (FP7-NMP-228424), MODECOM (NMP3-CT-2006-016434), and ONE-P (NMP3-LA-2008-212311) for financial support. The work in Mons is partly supported by the Interuniversity Attraction Pole IAP 6/27 of the Belgian Federal Governement, and the Belgian National Fund for Scientific Research (FNRS/FRFC). The work at Georgia Tech is partly supported by the STC program of the National Science Foundation under award DMR-0120967 and by the Center for Advanced Molecular Photovoltaics (Award No KUS-C1-015-21 made by King Abdullah University of Science and Technology, KAUST). J.C. and D.B. are FNRS Research Fellows. J.I. is grateful to the “Advanced Material in Aquitaine” program (www.ama-materials.com) for his Ph.D. grant. J.C. thanks University Bordeaux I for a visiting professorship. Calculations were carried out on mainframe computers of the “M3PEC-MESOCENTRE” of University Bordeaux I financed by Conseil Régional d’Aquitaine and the French Ministry of Research and Technology, as well as on the Interuniversity Scientific Calculation Facility (ISCF) installed at Facultés Universitaires Notre-Dame de la Paix (Namur, Belgium), for which the authors gratefully acknowledge the financial support of FNRS-FRFC.
This publication acknowledges KAUST support, but has no KAUST affiliated authors.