α-Quaterthiophene–polyethylene blends: Phase behaviour and electronic properties

We demonstrate that blending α-quaterthiophene (4T) with high-density polyethylene (HDPE) under judiciously chosen processing conditions allows preparation of continuous thin films of insulator content as high as 90 wt% without considerably sacrificing the electronic properties of the semiconducting species, as measured in field-effect transistors (FETs). Similar behaviour was recently reported for all-polymeric crystalline–crystalline semiconducting blends such as poly(3-hexylthiophene):HDPE. However, while that previous work focussed on the sequence in which the two components crystallize, we show here that for the present small molecule:polymer binaries – in addition to the crystallization sequence – the extent of solid–solid phase separation that occurs during blend preparation strongly affects the electronic properties of the active layers.