Effect of External Electric Field on the Ordered Structure of Molecular Chains and Hole Mobility in Regioregular Poly(3-hexylthiophene) with Different Molecular Weights

This research investigated the effect of a high-voltage external electric field on the ordered structure of molecular chains and hole mobility in regioregular poly(3-hexylthiophene) (P3HT) with different molecular weights through X-ray diffraction, atomic force microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, micro-Raman spectroscopy, UV–vis spectroscopy, photoluminescence spectroscopy, and organic field-effect transistors. The optimal magnitude of the external electric field was 5000 V/cm. With the optimized electric field applied to a series of P3HT films, the carrier mobility of all P3HT films increased, and the increase rate changed from 105% to 56%, closely depending on the increase in molecular weight from 33 kg/mol to 100 kg/mol. The results indicated that the increase in carrier mobility was attributed to the P3HT conformation order, which was controlled by the external electric field. Molecular weight was a critical factor in determining the P3HT conformation...