Cyano-substituted oligo(p-phenylene vinylene) single-crystal with balanced hole and electron injection and transport for ambipolar field-effect transistors

High and balanced hole and electron mobilities were achieved in OFETs based on the high photoluminescence of a 1,4-bis(2-cyano-2-phenylethenyl)benzene single-crystal with symmetric electrodes. For electron and hole, the operation voltage in the OFETs based on symmetric gold electrodes was 30 and -20 V, respectively. The accumulation threshold voltage is low enough for the OFETs to operate in an ambipolar model with the source/drain voltage (V-ds) around 50 V despite the high injection barrier. The highest electron and hole mobility was 0.745 cm(2) V (-1) s(-1) and 0.239 cm(2) V-1 s(-1), and the current density reached 90.7 and 27.4 A cm(-2), respectively with an assumed 10 nm accumulation layer. The high mobility comes from the strong pi-pi interactions. In addition, the highly ordered hydrogen bonding matrix may create an efficient route to pump the charge to the inner layer which can improve the injection ability.