Time-of-flight measurements in thin films of regioregular poly(3-hexyl thiophene)

Abstract

We have studied the transport of holes in thin films of regioregular poly(3-hexyl thiophene) (RRPHT). In comparison to regiorandom poly(3-hexyl thiophene) (PHT), RRPHT is a promising material for electronic devices, due to the high field effect mobility observed. We have studied the photogenerated charge carrier transport by using the integral time-of-flight (TOF) method. We have also studied the transport properties of the equilibrium charge carriers by a newly developed method of equilibrium charge carrier extraction in the case of a linearly increasing voltage. From TOF measurements in the subnanosecond time scale, it was experimentally obtained that the drift distance of holes is smaller than the inter-electrode distance in both PHT and RRPHT films and the mobility is higher than 10−2 cm2/Vs. In the millisecond time scale we obtained additional low mobility of equilibrium holes in RRPHT.