Abstract
The attractive optoelectronic properties of conducting polymers depend sensitively upon intra- and inter-polymer chain interactions, and therefore new methods to manipulate these interactions are continually being pursued. Here, we report a study of the isotopic effects of deuterium substitution on the structure, morphology and optoelectronic properties of regioregular poly(3-hexylthiophene)s with an approach that combines the synthesis of deuterated materials, optoelectronic properties measurements, theoretical simulation and neutron scattering. Selective substitutions of deuterium on the backbone or side-chains of poly(3-hexylthiophene)s result in distinct optoelectronic responses in poly(3-hexylthiophene)/[6,6]-phenyl-C61-butyric acid methyl ester (PCBM) photovoltaics. Specifically, the weak non-covalent intermolecular interactions induced by the main-chain deuteration are shown to change the film crystallinity and morphology of the active layer, consequently reducing the short-circuit current. However, side-chain deuteration does not significantly modify the film morphology but causes a decreased electronic coupling, the formation of a charge transfer state, and increased electron-phonon coupling, leading to a remarkable reduction in the open circuit voltage.
Original language | English |
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Article number | 3180 |
Journal | Nature Communications |
Volume | 5 |
DOIs | |
State | Published - Jan 24 2014 |
Funding
This research was conducted at the Center for Nanophase Materials Sciences (CNMS). Neutron Reflectivity measurements were conducted at the Liquids Reflectometer beamline (BL-4B) in Spallation Neutron Source, ORNL. CNMS and SNS are sponsored at ORNL by the Scientific User Facilities Division, U.S. Department of Energy, managed by UT-Battelle, LLC. Y.-Z.M. was sponsored by the Division of Chemical Sciences, Geosciences, and Biosciences, Office of Basic Energy Sciences, U.S. Department of Energy. We also thank Dr Joseph Strzalka for the assistance with GISAXS and GIWAXS measurements. Use of the Advanced Photon Source (APS) at Argonne National Laboratory was supported by the U.S. Department of Energy, Office of Basic Energy Sciences, under Contract DE-AC02-06CH11357. W.C. gratefully acknowledge financial support from the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under award number KC0203010.