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Factors Governing Intercalation of Fullerenes and Other Small Molecules Between the Side Chains of Semiconducting Polymers Used in Solar Cells
Author(s) -
Cates Nichole,
Cho Eunkyung,
Gysel Roman,
Risko Chad,
Coropceanu Veaceslav,
Miller Chad E.,
Sweetnam Sean,
Sellinger Alan,
Heeney Martin,
McCulloch Iain,
Brédas JeanLuc,
Toney Michael F.,
McGehee Michael D.
Publication year - 2012
Publication title -
advanced energy materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 10.08
H-Index - 220
eISSN - 1614-6840
pISSN - 1614-6832
DOI - 10.1002/aenm.201200392
Subject(s) - fullerene , materials science , polymer , van der waals force , miscibility , molecule , polymer solar cell , conjugated system , chemical physics , differential scanning calorimetry , polymer blend , organic solar cell , chemical engineering , polymer chemistry , organic chemistry , copolymer , thermodynamics , chemistry , composite material , physics , engineering
While recent reports have established significant miscibility in polymer:fullerene blends used in organic solar cells, little is actually known about why polymers and fullerenes mix and how their mixing can be controlled. Here, X‐ray diffraction (XRD), differential scanning calorimetry (DSC), and molecular simulations are used to study mixing in a variety of polymer:molecule blends by systematically varying the polymer and small‐molecule properties. It is found that a variety of polymer:fullerene blends mix by forming bimolecular crystals provided there is sufficient space between the polymer side chains to accommodate a fullerene. Polymer:tetrafluoro‐tetracyanoquinodimethane (F4‐TCNQ) bimolecular crystals were also observed, although bimolecular crystals did not form in the other studied polymer:non‐fullerene blends, including those with both conjugated and non‐conjugated small molecules. DSC and molecular simulations demonstrate that strong polymer–fullerene interactions can exist, and the calculations point to van der Waals interactions as a significant driving force for molecular mixing.