Mobility enhancement in solution-processable organic transistors through polymer chain alignment by roll-transfer printing

A roll-transfer printing method has been proposed for the uniaxial alignment of the liquid crystalline polymer semiconductor of poly(3,3″′-didodecylquarterthiophene) (PQT). It is shown that the roll-transfer printing of PQT at its liquid crystal phase temperatures yields highly aligned films in which the PQT molecules are aligned parallel to the roll-transfer direction and oriented perpendicular to substrates. The average field-effect mobility in the alignment direction of 0.17 cm2/Vs is 8 times higher than that in the perpendicular direction. The alignment of polymer chains is attributed to the enhancement of shear-stress effects during roll-transfer printing in the liquid crystal phase.

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► Field-effect mobility in PQT was enhanced by polymer chain alignment.
► We developed new printing method utilizing the thermotropic liquid crystal phase.
► Ratio of field-effect mobility in parallel/perpendicular direction was more than 8.
► The highest field-effect mobility of 0.28 cm2/Vs was achieved.
► PQT film prepared by this method has edge-on conformation with chain alignment.