Mobile charge carriers in pulse-irradiated poly- and oligothiophenes

Lower limits of the intrinsic charge carrier mobility in the solid phase of a series of oligothiophene compounds were determined with the pulse-radiol ysis time-resolved microwave conductivity technique, PR-TRMC. The mobility values fall roughly into two regimes and show no correlation with the numbe r of conjugated thiophene units. Relatively low mobilities (in the range of 3-6 10(-4) cm(2)/Vs) were found for a series of cyclohexyl-endcapped thiop henes, while significantly higher values of 0.01-0.02 cm(2)/Vs were obtaine d for several n-hexyl and n-dodecyl substituted compounds and for sexithioy hene. Interestingly, these latter values are similar to those of n-alkyl su bstituted polythiophenes measured earlier.