High‐Temperature‐Resistant Polyimide Films With Enhanced Tg for Improved Performance in Flexible TFT Devices

ABSTRACT Flexible display devices based on polyimide (PI) materials have found widespread applications in the display industry. However, the lower glass transition temperature ( T g ) of PI Films limits the process temperature of low‐temperature poly silica (LTPS), resulting in numerous defects in the thin film transistor (TFT) devices. In this paper, mABZ (meta‐amine benzimidazole) was introduced into the PI film, increasing the T g of PI from 457°C to 481°C and reducing the thermal expansion coefficient ( CTE ) to 1.09 ppm, thereby the annealing temperature of TFT could be increased to 480°C. Through the high‐temperature process of LTPS TFT and the innovative use of PI as a substrate, the mobility ( Mob ) of the TFT devices increased by 49%. This enhancement also led to a 33% rise in the on‐state current ( I on ). Additionally, the hysteresis decreased by 0.6 V, and the change in threshold voltage (delta V th ) during negative bias stress measurements reduced by 0.36 V. The introduction of high‐temperature‐resistant PI helps reduce the internal defects of the TFT device during the annealing process. The novel PI materials and the TFT device's corresponding high‐temperature process will help reduce the image sticking of OLED display panels and improve the display stability.