Tunable dielectric constant of polyimide-barium titanate nanocomposite materials as the gate dielectrics for organic thin film transistor applications
Journal
RSC Advances
Journal Volume
4
Journal Issue
107
Pages
62132-62139
Date Issued
2014
Author(s)
Abstract
We report on a systematic study of hydroxyl-containing polyimide (PI)-BaTiO3 (BT) nanoparticle (NP) nanocomposite dielectric materials, to determine the effects of BT NPs loadings (X) for X = 0, 2, 5, 8, 10, and 12 wt%, on p-type pentacene organic thin film transistors (OTFTs). A condensation reaction to produce well-dispersed BT NPs within the PI matrix was followed by spin-coating to form a dielectric thin film directly on a silicon substrate. The thermal, optical, surface, dielectric, and electrical properties of the PI-BPX hybrid dielectric composite correlated to BT content for each sample. The hybrid dielectric composites exhibit tunable insulating properties, including high dielectric constant values in the range 5.2-11.3, high capacitances from 3.1 to 27.9 nF cm-2 for a film thickness of approximately 350 nm, and low leakage current densities in the range of 1.85 × 10-7 to 2.76 × 10-6 A cm-2 at 2 MV cm-1. Bottom-gate top-contact OTFTs fabricated using various PI-BTX hybrid dielectrics, exhibit low threshold voltages of -4.09-2.62 V, moderately high field-effect mobility rates of 3.36 × 10-2∼2.32 × 10-1 cm2 V-1 s-1, and high ON/OFF ratios of approximately 105. This study opens a route towards transparent and highly stable hybrid dielectric materials with tunable dielectric properties, by careful selection of NPs and polymer matrix combinations.
Type
journal article