Poly(methyl methacrylate) Dielectric Material Applied in Organic Thin Film Transistors

The properties of pentacene-based organic thin film transistors (OTFTs) with poly(methyl methacrylate) (PMMA) as a dielectric layer have been investigated. Toluene was the best solvent for PMMA and the concentration of PMMA was about 8 wt % in toluene. The dielectric constant of PMMA dissolved in toluene was about 2.3. The pentacene film on the PMMA dielectric layer displayed high thin-film quality according to results of atomic force microscopy. The average grain size and surface roughness of pentacene grown on PMMA were about 0.29 µm 2 and 10.26 nm, respectively. The pentacene-based OTFTs with PMMA as a dielectric layer exhibited excellent electric characteristics, including a high mobility of 0.241 cm 2 V -1 s -1 or larger, an on/off current ratio of 2 × 10 4 or larger, and a threshold voltage of less than -5.6 V.