For stretchable electronics, intrinsically stretchable conjugated polymers (CPs) shows good prospects due to their low-cost and excellent processing performance. However, A main challenge lies in how to simultaneously enhance mechanical and electrical properties of intirinsically stretchable CPs to date. In this work, high mobility near-amorphous CP poly(indacenodithiophene-co-benzothiadiazole) (IDT-BT) with ultrahigh molecular weight has been synthesized as a strategy to overcome this challenge. In sharp contrast to high mobility, semicrystallinity CPs such as PDPPT3-HDO, simultaneously enhanced mechanical and electrical properties can be obtained by increasing molecular weight of IDT-BT, owing to the higher chain entanglement extent and larger range of intrachain charge transport pathway. Notably, IDT-BT with ultrahigh molecular weight (&gt;1000 kg mol-1, weight average) simultaneously exhibitted the highest charge mobility μ=2.63 cm2V-1s-1, tensile modulus E=1126.7 MPa, crack onset strain &gt;100% and fracture strain≥21% (Figure 1). In addition, due to the transient cross-linking sets acted by entanglement sites, IDT-BT with the highest entanglement extent (i.e. IDT-BT-1049.6k) showed the best elasticity among IDT-BTs with various Mws, with the highest elastic recovery &gt;80% and no crack after 100 cycles of strain. To the best of our knowledge, this is the first time that mobility &gt;2 cm2V-1s-1, crack onset strain &gt;100% and elastic modulus &gt;1 GPa was realized simultaneously in intrinsically stretchable CPs. The ultrahigh molecular weight IDT-BT can also be a potential candidate for stretchable electronics due to its outstanding overall performance.

Simultaneous enhancement of stretchability, strength and mobility in ultrahigh-molecular-weight poly(indacenodithiophene-co-benzothiadiazole)

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