Donor-acceptor (DA) polymers have garnered significant attention in flexible electronics because of their in-chain donor-acceptor interactions, which lower the band gap and promote high mobility in their native undoped form. Prior studies have extensively investigated the processing of conjugated polymers, including DA polymers, into thin films. However, the processing of these polymers into fibers and the corresponding structure-property relationship has not been well studied. Here, we report the successful processing of core-shell DA polymer fibers using a coaxial electrospinning technique. DPP-DTT is a high-mobility p-type DA polymer considered in this study. The core-shell fibers comprise a flexible polymer at the core and DPP-DTT at the shell. We investigated the effects of collector rotational speed on fiber morphology development. The GIWAXS analysis reveals that the fiber exhibits a mixed orientation of DPP-DTT at a lower collector rotational speed. However, at higher rotational speeds, an increased orientation of DPP-DTT polymer chains along the fiber axial direction was observed. Atomistic molecular dynamics simulations using applied shear confirm better order in the assembled aggregates. Additionally, the effects of mechanical stretching on the collected fibers were investigated using a custom-built tensile tester. The local conductance from AFM-TUNA analysis showed approximate Ohmic behavior throughout the fiber. Our electrospinning approach can be extended to large-scale fiber mat processing for optoelectronic applications.
