Micromorphology, photophysical and electrical properties of pristine and ferric chloride doped poly(3-hexylthiophene) films

Poly(3-hexylthiophene) (P3HT), synthesized by chemical oxidative polymerization at ∼258 K, has been probed by Fourier transform infrared (FT-IR), ultraviolet–visible (UV–vis) spectroscopy, scanning electron microscopy (SEM) and by measuring the temperature dependence of DC conductivity (σDC) in both its pristine and partially doped state. FT-IR and UV–vis studies suggest the formation of polaronic charge species in both pristine and partially doped P3HT. SEM of pristine P3HT film exhibits the formation of randomly distributed polymer fibrils whereas ferric chloride doped P3HT film shows the formation of dopant islands (size ∼500 nm), some of which adhered to the polymer fibrils. The temperature dependence of DC conductivity in the range 77–300 K is well explained by Mott's 3-dimensional variable range hopping (3D-VRH) model.