To date, few studies of the mobility–stretchability properties of N-type semiconductors, including naphthalenediimide (NDI)-based polymers, have been conducted, and the preparation of intrinsically stretchable N-type semiconducting polymers is very important in the construction of stretchable electronics. In this study, three NDI-based random terpolymers are synthesized by introducing functionalized conjugation break spacers (CBSs) with ester, sulfone, and amide groups. N-type semiconducting polymers with ester and amide-based CBSs undergo conformational reorganization during stretching, as evidenced by the progressive evolution of mixed edge-on and face-on orientations, as well as the increased UV–vis dichroic ratio. This phenomenon is attributed to the improved chain conformability and ductility from the randomized distribution of the CBSs along the polymer backbone with more planar CBSs. Therefore, polymers with ester-based CBSs achieve superior orthogonal electron mobility (μe) >0.005 cm2 V–1 s–1 and an average μe retention of 61% after 400 cyclic stretching at 60% strain. To the best of our knowledge, this study is the first to decipher the mobility–stretchability properties of N-type semiconducting polymers that warrant further investigation for constructing intrinsically stretchable and wearable electronics.

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....

The development of stretchable semiconducting polymers through statistical terpolymerization with conjugation break spacers (CBSs) has gained much attention. In this study, we systematically investigated the effects of incorporating CBSs with thioether units into naphthalenediimide (NDI)-based n-type semiconducting polymers on their semiconductivity and stretchability compared to polymers with the corresponding alkyl- and ether-based CBSs. Indeed, six NDI-based semiconducting polymers with CBSs composed of di­(ethylene sulfide), tetra­(ethylene sulfide), di­(ethylene oxide), tetra­(ethylene oxide), octylene, and tetradecylene units were synthesized by statistical terpolymerization based on Migita–Kosugi–Stille cross-coupling reactions of 5,5′-bis­(trimethylstannyl)-2,2′-bithiophene (2T), 4,9-dibromo-2,7-bis­(2-decyl­tetradecyl)­benzo­[lmn]­[3,8]­phenanthroline-1,3,6,8-tetraone (Br-NDI-Br), and CBSs. The experimental results indicate that heteroatom-based CBSs would sufficiently affect solid-state packing, intrinsic stretchability, and mobility retentions of the corresponding polymers. Although all of the polymers demonstrated strong edge-on orientations, those with ether-based CBSs displayed the lowest crystallinity among them. This result was attributed to the phase separation induced by highly polar ethylene oxide moieties, leading to inferior charge transport performances and low crack onset strain. In contrast, the thin film of the polymer with thioether-based CBSs showed delayed crack onset strain and a high dichroic ratio. The narrower bond angle of C–S–C (98.9°) than C–O–C (113.3°) calculated by the DFT method led to a more bent conformation along the polymer backbone, which provided a strain-releasing capability to realign the polymer chains. Consequently, the polymers with thioether-based CBSs displayed higher mobility–stretchability properties than those comprising ether-based CBSs. This is the first report on the design, synthesis, and application to organic field-effect transistors (OFETs) of stretchable n-type semiconducting polymer materials, clarifying the impact of heteroatoms on the mobility–stretchability properties of n-type semiconducting polymers with new CBSs having ethylene oxide and ethylene sulfide units.

Intrinsically stretchable semiconducting polymers have been extensively developed owing to their potential application in wearable and biomedical electronics. However, most of the developments for stretchable semiconductors have been primarily focused on p-type semiconducting polymers, and their n-type counterparts lag far behind. Therefore, we report the first investigation of the mobility−stretchability properties of ntype conjugated block copolymers (BCPs). The BCPs were designed and synthesized with an ABA-type architecture comprising polyisobutene (PIB) and poly(naphthalenediimide− bithiophene) (PNDI2T) with various compositions: ABA100 (0 wt % PIB), ABA85 (15 wt % PIB), and ABA52 (48 wt % PIB). ABA52 is found to present a lower elastic modulus, higher crack-onset strain, and a lower crystallinity than the analogues of ABA85 and ABA100 with or without a lower PIB content. At 0% strain, the ABA100, ABA85, and ABA52 polymers show electron mobilities (μ e ) of 0.012, 0.043, and 0.0032 cm 2 V −1 s −1 , respectively. At 100% strain, the ABA100, ABA85, and ABA52 polymers show μ e retention rates of (30, 17), (14, 18), and (46, 57)% with strains applied parallel/perpendicular to the channel direction, respectively. ABA100 and ABA85 exhibit similar performance decay; in contrast, ABA52 possesses a much improved μ e retention due to a high PIB content. The result of this study indicates a proof-of-concept BCP design for improving the mobility−stretchability properties of ntype semiconductors, which warrants further investigation.

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