Blends of semiconductor polymer and small molecular crystals for improved-performance thin-film transistors

Abstract

Incorporating dihexyl-quarterthiophene (DH4T) into the active layer of a poly(3-hexylthiophene) thin-film transistor can enhance the mobility by a factor of 10. The DH4T concentration dependence shows the improvement in mobility is due to the formation of crystals within the blend film, which occur at a critical concentration of 29% DH4T. Application of percolation theory reveals that transport in blend devices is limited by the mobility of the poly(3-hexylthiophene) (P3HT) and by the crystal packing. With improved polymer performance, the mobility in blend films is expected to approach 1cm2∕Vs.