Petascale Simulations of the Morphology and the Molecular Interface of Bulk Heterojunctions
| Autor: | Michael A. Matheson, Zach D. Seibers, William A. Shelton, S. Michael Kilbey, Jan-Michael Y. Carrillo, Rajeev Kumar, John F. Ankner, Monojoy Goswami, Bobby G. Sumpter, Kiran Bhaskaran-Nair |
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| Rok vydání: | 2016 |
| Předmět: |
Materials science
Morphology (linguistics) General Engineering General Physics and Astronomy Heterojunction Nanotechnology 02 engineering and technology Substrate (electronics) 010402 general chemistry 021001 nanoscience & nanotechnology 01 natural sciences Polymer solar cell 0104 chemical sciences Petascale computing Molecular dynamics Chemical physics General Materials Science Neutron reflectometry Thin film 0210 nano-technology |
| Zdroj: | ACS Nano. 10:7008-7022 |
| ISSN: | 1936-086X 1936-0851 |
| DOI: | 10.1021/acsnano.6b03009 |
| Popis: | Understanding how additives interact and segregate within bulk heterojunction (BHJ) thin films is critical for exercising control over structure at multiple length scales and delivering improvements in photovoltaic performance. The morphological evolution of poly(3-hexylthiophene) (P3HT) and phenyl-C61-butyric acid methyl ester (PCBM) blends that are commensurate with the size of a BHJ thin film is examined using petascale coarse-grained molecular dynamics simulations. Comparisons between two-component and three-component systems containing short P3HT chains as additives undergoing thermal annealing demonstrate that the short chains alter the morphology in apparently useful ways: they efficiently migrate to the P3HT/PCBM interface, increasing the P3HT domain size and interfacial area. Simulation results agree with depth profiles determined from neutron reflectometry measurements that reveal PCBM enrichment near substrate and air interfaces but a decrease in that PCBM enrichment when a small amount of short P3HT chains are integrated into the BHJ blend. Atomistic simulations of the P3HT/PCBM blend interfaces show a nonmonotonic dependence of the interfacial thickness as a function of number of repeat units in the oligomeric P3HT additive, and the thiophene rings orient parallel to the interfacial plane as they approach the PCBM domain. Using the nanoscale geometries of the P3HT oligomers, LUMO and HOMO energy levels calculated by density functional theory are found to be invariant across the donor/acceptor interface. These connections between additives, processing, and morphology at all length scales are generally useful for efforts to improve device performance. |
| Databáze: | OpenAIRE |
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