Poly(2,5-bis(3-alkylthiophene-2-yl)thieno[3,2-b]thiophene) (PBTTT) has  been widely investigated as a polymer semiconductor for organic electronics due to a large hole mobility and highly ordered structure[1]. The alkyl side-chains on a polymer backbone influence the polymer packing and orientation in thin films, which in turn affects the formation of lamellar structures and the charge-transport properties. Here, we study PBTTT chains with different size of the alkyl substituents (C12, C14, C16) using molecular mechanics and molecular dynamics; based on the optimized structures, simulations of the X-ray diffraction (XRD) patterns are carried out. Several force fields are evaluated to determine the packing structures of PBTTT lamellae. Structural changes of the polymer imposed by different alkyl chain lengths are observed, and the contributions of the polymer alkyl side-chains in the diffracted peaks are investigated. Effects of thermal annealing are taken into account to study how temperature, which leads to disorder of side-chains, affects the polymer structure. [1] McCulloch, I.; Heeney, M.; Bailey, C.; Genevicius, K.; Macdonald, I.; Shkunov, M.; Sparrowe, D.; Tierney, S.; Wagner, R.; Zhang, W.; Chabinyc, M. L.; Kline, R. J.; McGehee, M. D.; Toney, M. F. Nature Mater. 2006, 5, 328-333.

Influence of the alkyl wide-chain length on the packing of poly (2,5-bis(3–alkyl thiophene –2–yl) thieno[3,2-b] thiophene) (PBTTT) studied using molecular simulations

239th National Meeting (2010)

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