Air-stable ambipolarity of nanofibril polymer semiconductors in staggered organic field-effect transistors

Abstract

Air-stable ambipolar organic field-effect transistors (OFETs) are fabricated from the active layers of π-conjugated polymer and elastomer composites. Compared to the p-channel dominant charge transport behavior of pure donor–acceptor-type copolymer semiconductors, the polymer composites exhibited superior ambipolar charge transport characteristics with well-balanced and high electron and hole mobilities, both of more than 1.0 cm²/Vs. Moreover, these OFETs exhibited significantly improved air stabilities, particularly in the n-channel regime, which is because the encapsulation effect of the nanofibril conjugated polymers surrounded by the elastomer matrix efficiently suppressed electron trapping. At the optimal composition, spinodal decomposition of the constituent polymers is induced, forming fibrillar network structures during the solution casting and thermal annealing processes. These anisotropic polymer aggregates embedded in the elastomer matrix are induced to align in a direction parallel to the channel by directional printing techniques, such as off-centered spin coating and bar coating. This strategy of controlling the semiconductor film morphology is beneficial for the fabrication of high-performance and air-stable complementary-like electronic circuits. Furthermore, the embedded nanofibril morphology in a deformable elastomer can be widely used to realize stretchable optoelectronic devices.