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Abstract Mechanically deformable polymeric semiconductors are a key material for fabricating flexible organic thin‐film transistors (FOTFTs)—the building block of electronic circuits and wearable electronic devices. However, for many π‐conjugated polymers achieving mechanical deformability and efficient charge transport remains challenging. Here the effects of polymer backbone bending stiffness and film microstructure on mechanical flexibility and charge transport are investigated via experimental and computational methods for a series of electron‐transporting naphthalene diimide (NDI) polymers having differing extents of π‐conjugation. The results show that replacing increasing amounts of the π‐conjugated comonomer dithienylvinylene (TVT) with the π‐nonconjugated comonomer dithienylethane (TET) in the backbone of the fully π‐conjugated polymeric semiconductor, PNDI‐TVT100(yielding polymeric series PNDI‐TVTx, 100 ≥x≥ 0), lowers backbone rigidity, degree of texturing, and π–π stacking interactions between NDI moieties. Importantly, this comonomer substitution increases the mechanical robustness of PNDI‐TVTxwhile retaining efficient charge transport. Thus, reducing the TVT content of PNDI‐TVTxsuppresses film crack formation and dramatically stabilizes the field‐effect electron mobility upon bending (e.g., 2 mm over 2000 bending cycles). This work provides a route to tune π–π stacking in π‐conjugated polymers while simultaneously promoting mechanical flexibility and retaining good carrier mobility in FOTFTs.
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Enhanced miscibility and strain resistance of blended elastomer/π‐conjugated polymer composites through side chain functionalization towards stretchable electronics
Abstract This work presents improved compatibility in an elastomer/π‐conjugated polymer blend through side chain functionalization of the electronic polymer. Poly[(3‐(6‐bromohexyl)thiophene)‐ran‐(3‐hexylthiophene)] (P3BrxHT,x = 0%–100%) was synthesized (i) to improve miscibility with polybutadiene (PB) elastomer through altered π–π interactions and (ii) to covalently bond across phase‐segregated interfaces. Functionalization led to morphology with reduced domain sizes to improve crack onset strain from 7% to 40%. Furthermore, UV‐activated crosslinking reinforced mechanically weak interfaces and yielded at least an additional 40% increase in crack onset strain. Charge mobility in PB/P3BrxHT organic field‐effect transistors showed minimal dependence on bromide concentration and no negative effects from crosslinking. Functionalization was an effective method to reduce brittleness in PB/P3BrxHT blends through morphology modification and crosslinking to improve stability towards strain for potential stretchable electronic applications. © 2019 Society of Chemical Industry
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- PAR ID:
- 10458521
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Polymer International
- Volume:
- 69
- Issue:
- 3
- ISSN:
- 0959-8103
- Format(s):
- Medium: X Size: p. 308-316
- Size(s):
- p. 308-316
- Sponsoring Org:
- National Science Foundation
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