Yu, Ping JuiPing JuiYuLin, Yan ChengYan ChengLinLin, Chia YuChia YuLinWEN-CHANG CHEN2023-01-072023-01-072023-01-0300323861https://scholars.lib.ntu.edu.tw/handle/123456789/627002Recently, diverse approaches to synthesizing intrinsically stretchable conjugated polymers have been presented, such as incorporating the conjugation break spacers or intermolecular interactions in conjugated backbones, resulting in a compromise in the charge carrier mobility. In this study, polythiophenes with flexible [2,2':5′,2'':5″,2‴]-quaterthiophene (QT) or rigid 2-([2,2′-bithiophen]-5-yl)thieno[3,2-b]thiophene (BTTT) backbones were engineered with ester- (E−), thienyl- (T-), and thienyl-ester-substituted (TE) side chains for an enriched amorphous content and an improved mechanical tolerance. Polythiophene with QT backbone and TE side chain (PQT-TE) represents the best mobility−stretchability properties evidenced by the polarized UV–vis absorption, grazing incidence X-ray diffraction, and surface morphological analyses. Accordingly, PQT-TE presents a higher chain conformability and crack-onset strain than QT-based polythiophene with T (PQT-T) or E (PDCBT) side chains. This improvement originated from enriched amorphous domains and enhanced backbone planarity using a biaxially extended conjugation design. PQT-TE exhibits high orthogonal mobility preservations of (64, 90)% under 60% strain parallel/perpendicular to the channel direction. Notably, PQT-TE achieves high orthogonal mobility preservations of (48, 65)% after 800 cyclic stretch−release tests under 60% strain, and these improvements are similarly observed in that of BTTT-based polythiophene (PBTTT-TE). This study demonstrates that the jointed design of the biaxial extension and ester functional groups is efficacious in improving the mobility−stretchability properties of polythiophenes.Conjugated polymer | Field-effect transistor | Intrinsic stretchability | poly(quaterthiophene) | Side-chain engineering[SDGs]SDG7journal article10.1016/j.polymer.2022.1255752-s2.0-85143705574https://api.elsevier.com/content/abstract/scopus_id/85143705574