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

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 (∼7) and excellent insulating properties, including a low leakage current density with a high breakdown voltage (<10–8 A/cm2 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 cm2 V–1 s–1, on/off current ratios approaching 105, 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.