Temperature dependence of resistivity and magnetoresistance in doped regioregular polyalkylthiophenes

Summary form only given, as follows. The temperature dependence of resistivity and magnetoresistance of iodine doped regioregular polybutylthiophene (PBT), polyhexylthiophene (PHT), polyoctylthiophene (POT) and polydecy1thiophene (PDT) has been studied in the present work. In general, the room temperature conductivity of regioregular polyalkylthiophene (PAT) is considerably higher than that of regiorandom PAT due to the enhanced structural order and conjugation length in the former. The temperature dependence of conductivity of regioregular PAT is nearly two orders of magnitJde weaker than the regiorandom PAT. This indicates that regioregular PATs are near the critical regime of disorder-induced metal-insulator transition (MIT), while regiorandom PATs are in the insulating regime. At high pressures the conductivity increases and the temperature dependence of conductivity is weaker due to enhanced interchain transport, especially for regioregular PATs. The role played by the chemical structure, morphology and disorder in the temperature dependence of conductivity and magnetoresistance for regioregular PATs has been studied in detail.