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A Generalized Packing Model for Bulk Crystalline Regioregular Poly(3‐alkylthiophenes) with Extended Side Chains
Author(s) -
Bohle Anne,
Dudenko Dmytro,
Koenen Nils,
Sebastiani Daniel,
Allard Sybille,
Scherf Ullrich,
Spiess Hans Wolfgang,
Hansen Michael Ryan
Publication year - 2018
Publication title -
macromolecular chemistry and physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.57
H-Index - 112
eISSN - 1521-3935
pISSN - 1022-1352
DOI - 10.1002/macp.201700266
Subject(s) - side chain , thiophene , stacking , polymer chemistry , polythiophene , polymer , materials science , conjugated system , planarity testing , chemistry , crystallography , conductive polymer , organic chemistry , composite material
Poly(3‐alkylthiophenes) are one of the most frequently used conjugated polymer classes in organic photovoltaics. Here, a generalized packing model for the polythiophene main chains in the crystalline form I of high molecular weight regioregular poly(3‐alkylthiophenes) with extended side chains (pentyl through octyl) is reported. The model is based on structural constraints from solid‐state NMR: short internuclear distances of less than 4.0 Å of neighboring thiophene protons parallel to the stacking direction and the isotropic chemical shift for the thiophene protons is high‐field shifted by 0.9 ± 0.1 ppm. Nucleus‐independent chemical shift calculations show that only the most recent structure for P3HT (space group P2 1 / c ) is compatible with these structural constraints. On this basis, a generalized packing model is developed, showing that slipping parallel to the stacked polymer chains of up to 1.5 Å is allowed, while out‐of‐plane tilts perpendicular to the stacked chains are only tolerated up to 20°.