Until recently, the synthesis of polythiophenes using Suzuki chemistry has proven difficult because of the ready protodeborylation of thiophene boronates. However, we now report that the new generation of bulky, electron-rich Pd(0)-phosphane catalysts are effective and reliable for the preparation of regioregular polyalkylthiophenes using Suzuki coupling. Moreover, the monomers can be prepared in high yield by Ir-catalysed borylation, without the need for strong organolithium bases, making this potentially a highly functional group-tolerant approach to polyalkylthiophene derivatives. Perfluoroalkylthiophenes also undergo this reaction.

We have approximated the tail of the Gaussian distribution of states of organic semiconduc-tors with an exponential function. We have used this approach to calculate the carrier concentra-tion in organic materials, and subsequently the charge distribution in the accumulation region of a field effect device and the space-charge capacitance in accumulation mode. Small signal high frequency capacitance-voltage measurements performed at various temperatures show good agreement with this model and the characteristic temperature of the exponential function has been estimated from these measurements based on the theory developed.