Low-Temperature Photocurable High-k Polyimide Insulator with Methacrylate Moieties for Realizing Low-Voltage Thin-Film Transistors and Logic Gates

Abstract

With the increasing demand for flexible and wearable electronic devices, the need for efficient and compatible insulating materials has also increased. In this study, low-temperature photocurable polyimide (PI) films with a high dielectric constant (k) were fabricated by incorporating methacrylate photosensitive groups and a high-k pendant moiety for use as insulation materials in microelectronic devices. As-synthesized PIs depending on the substitution of side chain were called PI-73, PI-90, and PI-100. Among them, PI-100 films exhibited a high k (similar to 7) and excellent insulating properties, including a low leakage current density with a high breakdown voltage (<10(-8) A/cm(2) at 4 MV/cm). Remarkably, the photocured PI films achieved outstanding insulation performance and high-k properties without requiring thermal annealing and only photocuring. Owing to these exceptional characteristics, the PI-100 films were well-suited for use as a gate insulator in organic thin-film transistors (OTFTs) operating at low voltages; OTFTs were operated with field-effect mobilities of 0.40 cm(2) V-1 s(-1), on/off current ratios approaching 10(5), and near-zero threshold voltages (0 +/- 0.01 V), all while operating below 2 V. Moreover, it could be successfully used in integrated logic devices with 2 V operation, thereby demonstrating its potential for next-generation microelectronic applications.