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Role of Side‐Chain Branching on Thin‐Film Structure and Electronic Properties of Polythiophenes
Author(s) -
Himmelberger Scott,
Duong Duc T.,
Northrup John E.,
Rivnay Jonathan,
Koch Felix P. V.,
Beckingham Bryan S.,
Stingelin Natalie,
Segalman Rachel A.,
Mannsfeld Stefan C. B.,
Salleo Alberto
Publication year - 2015
Publication title -
advanced functional materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.069
H-Index - 322
eISSN - 1616-3028
pISSN - 1616-301X
DOI - 10.1002/adfm.201500101
Subject(s) - materials science , branching (polymer chemistry) , side chain , chemical physics , polymer , crystallinity , diffraction , density functional theory , electronic structure , charge density , computational chemistry , optics , composite material , chemistry , physics , quantum mechanics
Side‐chain engineering is increasingly being utilized as a technique to impact the structural order and enhance the electronic properties of semiconducting polymers. However, the correlations drawn between structural changes and the resulting charge transport properties are typically indirect and qualitative in nature. In the present work, a combination of grazing incidence X‐ray diffraction and crystallographic refinement calculations is used to determine the precise molecular packing structure of two thiophene‐based semiconducting polymers to study the impact of side‐chain modifications. The optimized structures provide high‐quality fits to the experimental data and demonstrate that in addition to a large difference in interchain spacing between the two materials, there exists a significant disparity in backbone orientation as well. The calculated structures are utilized in density functional theory calculations to determine the band structure of the two materials and are shown to exhibit a dramatic disparity in interchain dispersion which accounts for the large observed difference in charge carrier mobility. The techniques presented here are meant to be general and are therefore applicable to many other highly diffracting semicrystalline polymers.