One‐Step Fabrication of Hydrophobic Hybrid Gate Dielectrics for Low‐Voltage Organic Thin‐Film Transistors

Abstract

We report here on the design, processing, and dielectric properties of low surface energy organic/inorganic hybrid dielectric films for low‐voltage operation of organic thin‐film transistors (OTFTs). The hydrophobic hybrid dielectric films are easily fabricated by one‐step spin coating of a zirconium chloride precursor in an octadecyltrimethoxysilane solution under ambient conditions, followed by thermal curing at low temperatures (approximately 150°C). These novel dielectrics exhibit excellent surface smoothness (root‐mean‐square roughness is <0.5 nm), great insulating property (leakage current densities <10−6 A/cm2), and high capacitance (365 nF/cm2). In addition, the surface nature of the hybrid dielectric is hydrophobic (water contact angle is 105°), without any further surface modifications, which is highly compatible with organic semiconductors. Consequently, the hybrid dielectrics integrated into the pentacene OTFTs function at relatively low voltages (< −2.5 V) with excellent TFT characteristics (mobility: 0.31 cm2/V·s, on/off current ratio: 105, low threshold voltage: down to −0.7 V).