34.2: PMMA Buffer‐Layer Effects on Electrical Performance of Pentacene OTFTs with a Cross‐linked PVA Gate Insulator on a Flexible Substrate

Abstract

Abstract In this paper we proposed for the first time a technique of poly‐methylmethacrylate (PMMA) buffer layer insertion to overcome unsaturated output characteristics of OTFTs with cross‐linked poly‐vinylalcohol (PVA) gate insulators on a PET substrate. A 3:1 diluted PMMA buffer layer insertion resulted in saturated output characteristics and small shift of a threshold voltage in successive I‐V measurements for OTFTs due to the enhancement of surface hydrophobicity on the gate insulator. The electrical performances of a threshold voltage, a subthreshold slope and on‐off current ratio have been noticeably improved after PMMA buffer layers insertion. To our best knowledge, the highest mobility of 0.32 cm 2 /Vsec has been obtained among OTFTs fabricated with polymer gate insulators by spin coating processes on a PET substrate.