Leveraging Chemical Crosslinking to Reconcile Elastic Recovery Rate and Ductility in High-Mobility Stretchable Conjugated Polymers

Abstract

Despite recent advances in stretchable polymer semiconductors, the trade-off of charge mobility between mechanical properties remains outstanding using conventional physical or chemical strategies. Herein, we introduce a transesterification crosslinking in hydroxy-modified poly(indacenodithiophene-alt-benzothiadizole)s (OH-IDTBT-5%) using polyurethane elastomer crosslinker containing polycaprolactone segment (PU-PCL), to simultaneously enhance the elastic recovery rate, elastic modulus (~1.5 GPa) and hole mobility, while maintaining exceptional ductility (COS >100%, εF ~30%). The crosslinked network restricts plastic deformation, yielding outstanding elastic recovery rate (>90% at 4% strain) with delayed plastic deformation onset strain (PdOS ~100%). Notably, the crosslinking reaction passivated detrimental hydroxy groups and enhanced mobility to 2.13 cm2 V-1 s-1, which remained relatively consistent even after 500 stretching cycles at 70% strain. Importantly, the crosslinking films exhibited excellent robustness against organic solvent by remaining over 90% fraction after soaking. Our strategy provides an opportunity for high-performance stretchable semiconductors, by overcoming not only the trade-off between charge transport property and mechanical durability in general, but also the sacrifice of ductility in chemical crosslinking systems.