Stretchable polymer semiconductors are essential materials
to realize
soft skin-like electronics. However, most high-mobility semiconducting
polymers suffer from poor stretchability and strain-dependent charge
carrier mobility. Herein, we report an approach to improve the stretchability
of semiconducting polymers while maintaining charge carrier mobility.
The strain independent performance was accomplished by incorporating
a nontoxic small molecule, namely triacetin (TA), into high-mobility
conjugated polymers. We observed that TA molecules substantially increased
the stretchability of the high-mobility semiconducting polymer diketopyrrolopyrrole-thienyl-vinyl-thiophene
(DPP-TVT), with a crack onset strain >100%, while the neat DPP-TVT
polymer only shows a low crack onset strain <25%. The organic field-effect
transistor (OFET) devices fabricated using the TA blend films maintain
similar charge carrier mobility compared to the neat DPP-TVT-based
devices. The influences of TA additive were further characterized,
which included reduced glass transition temperature of polymer backbones,
decreased modulus, and breakage of the polymer chain aggregations.
The TA additive functions as a plasticizer residing in between lamellae
layers of semiconducting polymers, which helps to preserve the crystalline
molecular packing under deformation. We demonstrated the applicability
of this approach by improving the stretchability of various semiconducting
polymers using TA and its analog tricaproin. Last, a stretchable OFET
array was fabricated with TA blended films, and it showed a well-maintained
charge carrier mobility even after 1000 stretch–release cycles
at 50% strain.