Bulk charge transport in liquid-crystalline polymer semiconductors based on poly(2,5-bis(3-alkylthiophen-2-yl)thieno[3,2-b]thiophene)

Abstract

The class of liquid-crystalline semiconducting polymers based on poly(2,5-bis(3-alkylthiophen-2-yl)thieno[3,2-b]thiophene) recently has attracted significant interest in the field of organic electronics, predominantly due to their promising performance in field-effect transistor (FET) structures with device mobilities reaching—if not exceeding—those of amorphous silicon architectures. Less is known, however, about the bulk charge-transport properties of these interesting macromolecules. We therefore conducted time-of-flight (TOF) photoconductivity measurements on one particular material of this class of organic semiconductors—i.e. poly(2,5-bis(3-dodecylthiophen-2-yl)thieno[3,2-b]thiophene), pBTTT-C₁₂—and attempted to correlate the electronic bulk properties of this polymer with its microstructural development with temperature. The effect of annealing was also investigated.