Emission Ellipsometry and Photophysical Pathways in Electropolymerized P3DDT Thin Films

In this work, poly(3-dodecylthiophene) (P3DDT) thin films were electrochemically synthesized onto fluorine-doped tin oxide (FTO) substrates via cyclic voltammetry using tetraethylammonium tetrafluoroborate (Et4NBF4) as the supporting electrolyte. Optical analyses were performed using ultraviolet–visible absorption spectroscopy (UV-Vis), photoluminescence spectroscopy (PL), emission ellipsometry (EE) and Raman spectroscopy. The results revealed the formation of distinct structures during the electropolymerization process, which significantly affected the optical behavior observed in the UV–Vis and PL spectra. Furthermore, the EE measurements provided insights into the impact of these structures on the polarization states of emitted and transmitted light on energy and charge transfer mechanisms and on the photophysical behavior of P3DDT. Variations in the degree of polarization (P), anisotropy factor (r), and asymmetry factor (g) were analyzed as a function of the emission wavelength. The results confirm the potential of P3DDT as an active layer in electroluminescent devices, as the emissive material used in the active layer consisted exclusively of this polymer.