Performance Regulation and Application Evaluation of Colorless Polyimide for Flexible Displays

Abstract

Flexible display technology demands specific characteristics from substrate materials, including a high glass transition temperature, significant optical transparency, strong mechanical properties, and a compatible coefficient of thermal expansion. This research focused on improving the optical, thermal, and mechanical properties of colorless polyimide films by adjusting the ratios of fluorine monomers and investigating various annealing temperatures. This approach provided valuable insights into the relationship between structural characteristics and performance, as well as the impact of annealing temperature on these attributes. To evaluate the reliability of the colorless polyimide films, a chemical vapor deposition method was employed to deposit buffer layers onto the surface of colorless polyimide films. High-temperature annealing experiments indicated that both excessively high and low thermal expansion coefficient could result in the formation of cracks. Finally, after conducting 200,000 folding tests, it was confirmed that the films displayed excellent mechanical properties, with no cracks observed in the buffer layer. This research could provide important insights for developing new substrate materials in display applications.

Keywords: Flexible display, Colorless polyimide, Performance Regulation, Folding reliability