Application and Analysis of Cross-linked Cyanoethyl Pullulan for Organic Thin Film Transistors

Abstract

Organic thin film transistors (OTFTs) were fabricated with cross-linked polymer films as new gate insulator materials. Cyanoethyl pullulan (CYEPL) was cross-linked with three different cross-linkers: (3-Glycidyloxypropyl)trimethoxysilane (GPTMS), suberoyl chloride (SCL) and ethylenediaminetetraacetic dianhydride (EDTAD). The curing temperature was as low as 90 ℃. The morphology of the polymer films was evaluated with atomic force microscopy (AFM). The capacitance-voltage measurement with MIS (metal-insulator-semiconductor) structures showed high dielectric constant 13.6 and high capacitance 75nFcm-2. Pentacene molecules deposited by vapor deposition onto the SCL cross-linked dielectric surface were arranged in a favorable two-dimensional way, which lead to well π-conjugated and large crystal grains. A high carrier mobility 8.6cm2/V&#8226

S was obtained in pentacene OTFTs, with negligible hysteresis and low operation voltage (-3V). The dependence of capacitance on frequency was also studied.