Room-temperature smectic liquid crystal monolayers for field-effect transistors

Abstract

Two novel π-extended isoindigo derivatives with long alkyl chains, namely TT-IDG-C8 and TT-IDG-C12, were synthesized and characterized. Both compounds possess liquid crystal phase transition temperatures below room temperature, at 22.1 and −20.9 °C for TT-IDG-C8 and TT-IDG-C12, respectively. Room-temperature liquid crystal monolayers were grown using a simple drop-casting method. Organic field-effect transistors (OFETs) were then fabricated based on these monolayer liquid crystals, and hole mobilities of 0.32 and 0.49 cm² V⁻¹ s⁻¹ are extracted for TT-IDG-C8 and TT-IDG-C12, respectively. This is the first demonstration of room-temperature semiconducting smectic liquid crystal monolayers.