Electric field induced optical anisotropy of P3HT nanofibers in a liquid solution

The nanofiber morphology of regioregular Poly-3-hexylthiophene (P3HT) is a 1D crystalline structure organized by pi-pi stacking of the backbone chains. In this study, we report the impact of electric field on the orientation and optical properties of P3HT nanofibers dispersed in liquid solution. We demonstrate that alternating electric field aligns nanofibers, whereas static electric field forces them to migrate towards the cathode. The alignment of nanofibers introduces anisotropic optical properties, which can be dynamically manipulated until the solvent has evaporated. Time resolved spectroscopic measurements revealed that the electro-optical response time decreases significantly with the magnitude of applied electric field. Thus, for electric field 1.3 V.mu m(-1) the response time was measured as low as 20 ms, while for 0.65 V.mu m(-1) it was 110-150 ms. Observed phenomenon is the first mention of P3HT supramolecules associated with electro-optical effect. Proposed method provides real time control over the orientation of nanofibers, which is a starting point for a novel practical implementation. With further development P3HT nanofibers can be used individually as an anisotropic solution or as an active component in a guest-host system. (C) 2015 Optical Society of America