Effects of gate dielectric thickness and semiconductor thickness on device performance of organic field-effect transistors based on pentacene

In this paper, the pentacene-based organic field-effect transistors (OFETs) with poly(methyl methacrylate) (PMMA) as gate dielectrics were fabricated, and the effects of gate dielectric thickness and semiconductor thickness on the device performance were investigated. The optimal PMMA thickness is in the range of 350–400 nm to sustain a considerable current density and stable performance. The device performance depends on the thicknesses of the active layer non-monotonically, which can be explained by the morphology of the pentacene film and the position of the conducting channel in the active layer. The device with a pentacene thickness of 50 nm shows the best performance, which has a maximum hole mobility of 1.12 cm2/V · s. In addition, the introduction of a thin layer of tris-(8-hydroxyquinolinato) aluminum (Alq3) to the OFETs as a light-emitting material greatly decreases the device performance.