The electrospinning technique is an attractive route to improve the electrical properties of conjugated polymer fibers by inducing the alignment of polymer chains as a result of stretching during the electrospinning process. Here, we report the effects of various processing conditions on the structure and properties of electrospun poly(3-hexylthiophene) (P3HT) fibers. The processing of P3HT was facilitated using high molecular weight poly(ethylene oxide) (PEO). The PEO concentration in the P3HT/PEO fiber was varied from 25% to 2.5% to minimize the concentration of insulating materials in the fiber. The effects of PEO concentration on morphology and electrical properties were monitored. While the electrical conductivity changed slightly, no significant change of overall morphology was observed with the varying PEO concentration, as in all cases, non-beaded fibers were obtained. The self-assembly of P3HT in the spinning solutions was investigated using shear-rheology and photoluminescence analysis for various conditions, including the shear history, heating, and cooling cycle the solution was subjected to. The XRD data on the electrospun fibers suggest that the P3HT chains formed crystalline domains with both interchain π-π and lamellar stackings. Electrical conductivity was measured for fibers mat and single fiber. The single fiber electrical conductivity was higher than that of the mat, and for the undoped single fiber, the electrical conductivity of ~4.5*10<sup>-5</sup> S/cm was obtained. This is similar to that obtained for pure P3HT thin film, without PEO. Our results provide insights into processing-structure-property relationships for conjugated polymers.

Processing and characterization of electrospun poly(3-hexylthiophene) fibers

ACS Fall 2021

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