Intrinsically stretchable naphthalenediimide-bithiophene conjugated statistical terpolymers using branched conjugation break spacers for field-effect transistors
Journal
Polymer Chemistry
Journal Volume
12
Journal Issue
42
Pages
6167-6178
Date Issued
2021
Author(s)
Lin, Y.-C.
Matsuda, M.
Sato, K.-I.
Chen, C.-K.
Yang, W.-C.
Higashihara, T.
Abstract
The development of conjugated polymers through the statistical terpolymerization of conjugation break spacers (CBSs) has received great attention because of their synergistic potential in enhancing fracture strain and tensile strength. In this study, a series of bulky and branched CBSs with ester functional groups and dimethyl (P1), methyl/propyl (P2), ethyl/butyl (P3), and dibutyl (P4) alkyl groups were incorporated into naphthalenediimide-bithiophene-based conjugated polymers through statistical terpolymerization. Morphological studies, including atomic force microscopy (AFM) and grazing incidence X-ray diffraction (GIXD) studies, were applied to pristine and stretched polymer films to decipher the structure-stretchability relationship; further, their mobility-stretchability relationship was investigated by studying their field-effect transistor (FET) characteristics. We found that polymers with bulky and branched CBSs exhibit reduced backbone rigidity, allowing polymer chains to entangle more easily than those of stiffer polymers with similar molecular weights. Therefore, the polymer film exhibits a more uniform load distribution throughout the channel layer, and the branched CBSs serve as lubricants that deter crack propagation during deformation. Consequently, P4 with symmetrically extended alkyl groups shows good ductility and mobility-stretchability properties, with orthogonal μe,?/μe,⊥ retention of approximately 20-30% with 60% strain and 30-40% after 400 stretching-releasing cycles with 60% strain. Our results indicated that statistical terpolymerization with branched CBSs is a versatile and effective methodology for controlling orientational and stacking patterns to achieve good mobility-stretchability properties in conjugated polymers. ? 2021 The Royal Society of Chemistry.
Subjects
Field effect transistors
Polymer films
Semiconducting films
Semiconducting polymers
Tensile strength
Alkyl groups
Atomic-force-microscopy
Based conjugated polymers
Bithiophenes
Field-effect transistor
Fracture strain
Grazing incidence X-ray diffraction
Morphological study
Property
Terpolymerisation
Conjugated polymers
Type
journal article