The Polymer Society of Korea

Abstract

In this study, we investigate the electrical properties of organic devices based on a small-molecule/insulator sandwich structure. The devices consist of a p-type organic semiconductor, dinaphtho[2,3-b:2′,3′-f]thieno[3,2-b]thiophene (DNTT), and a parylene tunneling dielectric layer (TDL). By varying the thickness of the TDL, three distinct operating regions are observed. At TDL thickness of 15 nm, hole tunneling enables channel formation in the lower DNTT layer, resulting in parallel-channel transistor behavior comparable to that of conventional single-layer DNTT devices. At a TDL thickness to 40 nm partially suppresses hole tunneling, leading to the appearance of negative differential transconductance and current saturation. At a TDL thickness of 80 nm, hole tunneling is inhibited during gate-voltage sweeping, and the lower DNTT layer acts as a floating gate. In this region, the device operates as a photomemory, exhibiting a photoresponse under 450 nm illumination.