Tunneling and Origin of Large Access Resistance in Layered-Crystal Organic Transistors

Abstract

Very high layered crystallinity is achieved in some alkyl-substituted organic semiconductors, allowing high-performance organic thin-film transistors (OTFTs). The authors observe that nonlinear device characteristics depend on the number of layers, for OTFTs based on large-area single-crystalline films of Ph-BTBT-Cn. This nonlinearity is caused by tunneling-based access resistance across layers of alkyl chains, which is the origin of the wide device-to-device variation in mobility seen in single-crystalline OTFTs. With this understanding, since these insulating chains can be tuned by length, they are a point for device optimization.