Thermal and electrical properties of poly(3-alkylthiophene)s prepared by the oxidative polymerization

Thermal and electrical properties of poly(3-hexylthiophene)(P3HT), which was prepared by the oxidative polymerization in the range from −30 to 40°C, have been investigated. Differential scanning calorimetry (DSC) showed that the P3HT had a relatively high melting point (170 to 190°C). The P3HT polymerized at a lower temperature gave a sharper endothermic peak in DSC profile, suggesting that crystallinity of the P3HT increased with a decrease in the polymerization temperature. DC conductivity was measured for cast films of the P3HT as a function of temperature (−160 to 200°C). The conductivity increased remarkably with an increase in temperature over the range below room temperature, leveled off at 10−8 to 10−7 [S/cm] between room temperature and some 100°C, and reached a peak at around the melting point.