Ultrahigh On‐Current Density of Organic Field‐Effect Transistors Facilitated by Molecular Monolayer Crystals

Abstract Organic semiconductor materials are not recognized as a system for high current density applications due to the generally low mobility and high contact resistance. In this work, solution‐processed organic molecular monolayer crystals (1L‐crystals) as the active layers in field‐effect transistors, demonstrating high current density application are utilized. The 1L‐crystal‐based devices exhibit high intrinsic mobility of 10.9 cm 2 V –1 s –1 and a contact resistance as low as 28 Ω cm, offering unprecedently high width‐normalized current density up to 19 µA µm –1 and 1.2 MA cm –2 normalized by cross‐section area. Joule heating effects in these high current devices are investigated. At a current density of 7 µA µm –1 , 1L‐crystal‐based transistor works stably within 1000 consecutive scans. Above this current density, thermal degradation in the current starts to occur and pulsed mode operation can restrict the degradation. The 1L‐crystals exhibit superiority in high‐current and potential high‐frequency applications, which can expand the current boundary of organic semiconductor materials.