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

Abstract

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 cm² V⁻¹ s⁻¹ and 0.239 cm² 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 π–π 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.