(337h) Processing of Donor-Acceptor Conjugated Polymers to Core-Shell Electrospun Fibers and Their Properties

Donor-acceptor (DA) polymers have gained significant attention in flexible electronics due to 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 DA polymer into thin films. However, the processing of DA polymer 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 core and DPP-DTT at the shell side. 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. Additionally, the effects of mechanical stretching on the collected fibers were investigated using a custom-built tensile tester. AFM analysis showed similar surface roughness up to 150% strain, indicating that DPP-DTT polymer layer in the outer shell can withstand this mechanical strain. Also, local conductance from TUNA analysis showed approximate Ohmic behavior throughout the fiber. Our electrospinning approach can be extended to large-scale fiber mat processing for optoelectronic applications.