Fast patterning of oriented organic microstripes for field-effect ammonia gas sensors

Abstract

A series of organic field-effect transistors (OFETs) with patterned ultra-thin films for NH₃ detection are achieved via fast dip-coating. The morphology and packing structure of the ultra-thin films are greatly dependent on the surface energy of the substrates, geometry features of the patterned electrodes and evaporation atmosphere during the dip-coating process, which in turn results in a significant difference in the NH₃ sensing properties. Based on the newly proposed mechanism, low-trap dielectric-semiconductor interfaces, a stripe-like morphology and an ultrathin film (as low as 2 nm) enable the OFET-based sensors to exhibit unprecedented sensitivity (∼160) with a short response/recovery time. The efficient (2 mm s⁻¹), reliable, and scalable patterning strategy opens a new route for solution-processed OFET-based gas sensors.