Simultaneous Enhancement of Charge Transport and Stretchability for IDTBT Polymer Semiconductor via Partial Substitution of Long Alkyl Chains With Cyclopentyl Groups.

Abstract

Polymer semiconductors that simultaneously exhibit high charge mobility and robust mechanical stretchability are essential for the next generation of flexible electronics. Here, we report a new poly(indacenodithiophene-alt-benzothiadiazole) (IDTBT) based polymer semiconductor, IDTBT-C-1, in which a fraction of the long alkyl chains are replaced with cyclopentyl groups, exhibiting a hole mobility of 6.01 cm² V^-1 s^-1, among the highest reported for intrinsically stretchable polymer semiconductors to date, and substantially higher than that of the parent IDTBT (1.39 cm² V^-1 s^-1). Notably, the charge transport performance of IDTBT-C-1 remains highly stable even after 3000 stretching-releasing cycles at 50% strain. Moreover, relative to the parent IDTBT, IDTBT-C-1 exhibits a higher onset strain for surface damage, an increased elastic modulus, and enhanced strain recovery. Further studies reveal that substitution with a cyclopentyl group strengthens interchain interactions among conjugated units. These reinforced interactions facilitate interchain charge hopping, leading to enhanced mobility, while simultaneously promoting the formation of additional physical cross-links that impart superior mechanical stretchability and elastic recovery to IDTBT-C-1 thin films.