Dielectric Behavior of Poly(3-Hexylthiophene)/Carbon Nanotube Composites by Broadband Dielectric Spectroscopy

Some of the most exciting novel approaches for renewable solar energy conversion are organic photovoltaic devices that take advantage of the unique properties of polymers such as poly(3-hexylthiophene) (P3HT). Although these types of devices present significant advantages (stability and price), their long-term performance has to be continuously improved. This paper describes the dielectric behavior of pristine P3HT and its nanocomposites versus temperature and frequency by using broadband dielectric spectroscopy. Dielectric spectra reveal the existence of two relaxation phenomena (alpha, beta), below and above the glass transition. The alpha relaxation is related to the crystallization phenomena, and the beta relaxation is due to dipolar polarization processes. These results can be incorporated into a continuous understanding of the electrical behaviors of such polymers, which play extremely important roles in the overall quality of photovoltaic devices that use such polymeric materials.