The effect of molecular structure and environment on the miscibility and diffusivity in polythiophene-methanofullerene bulk heterojunctions: theory and modeling with the RISM approach

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DOIResolve DOI: http://doi.org/10.3390/polym8040136
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TypeArticle
Proceedings titlePolymers
Conference2015 International Chemical Congress of Pacific Basin Societies, December 15–20, 2015, Honolulu, Hawaii, USA
ISSN2073-4360
Volume8
Issue4
Article number136
Pages116
SubjectOrganic photovoltaics; Structural properties; Dynamical properties; PCBM; P3HT; P3BT; RISM
AbstractAlthough better means to model the properties of bulk heterojunction molecular blends are much needed in the field of organic optoelectronics, only a small subset of methods based on molecular dynamics- and Monte Carlo-based approaches have been hitherto employed to guide or replace empirical characterization and testing. Here, we present the first use of the integral equation theory of molecular liquids in modelling the structural properties of blends of phenyl-C₆₁-butyric acid methyl ester (PCBM) with poly(3-hexylthiophene) (P3HT) and a carboxylated poly(3-butylthiophene) (P3BT), respectively. For this, we use the Reference Interaction Site Model (RISM) with the Universal Force Field (UFF) to compute the microscopic structure of blends and obtain insight into the miscibility of its components. Input parameters for RISM, such as optimized molecular geometries and charge distribution of interaction sites, are derived by the Density Functional Theory (DFT) methods. We also run Molecular Dynamics (MD) simulation to compare the diffusivity of the PCBM in binary blends with P3HT and P3BT, respectively. A remarkably good agreement with available experimental data and results of alternative modelling/simulation is observed for PCBM in the P3HT system. We interpret this as a step in the validation of the use of our approach for organic photovoltaics and support of its results for new systems that do not have reference data for comparison or calibration. In particular, for the less-studied P3BT, our results show that expectations about its performance in binary blends with PCBM may be overestimated, as it does not demonstrate the required level of miscibility and short-range structural organization. In addition, the simulated mobility of PCBM in P3BT is somewhat higher than what is expected for polymer blends and falls into a range typical for fluids. The significance of our predictive multi-scale modelling lies in the insights it offers into nanoscale morphology and charge transport behaviour in multi-component organic semiconductor blends.
Publication date
PublisherMDPI
LanguageEnglish
AffiliationNational Institute for Nanotechnology; National Research Council Canada
Peer reviewedYes
Identifierpolym8040136
NPARC number23000422
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Record identifier9e47b5a1-1198-4bbc-9e48-83c3735d2230
Record created2016-07-15
Record modified2016-07-15
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