Synthesis and characterization of triarylamine-based polyimides for electrochromic and optoelectronic conversion behaviors

In this study, four novel triarylamine-based polyimides with different substituted groups (tert-butyl and -H) containing pyrrole moieties were successfully prepared by polycondensation reaction. The electrochemical and electrochromic properties of the polyimides were measured by cyclic voltammetry and spectro-electrochemistry. The polyimides exhibited obvious electrochromic behavior with good thermal stability (the 10% weight-loss temperatures were recorded in the range of 345-386°C), film-forming ability and reversible stability after 1000 s. The color of the polyimide films changed from colorless to light blue or yellow to blue on increasing the applied potential. The highest coloration efficiency reached up to 190 cm 2 C −1 . The polyimide films exhibited a stable response to the light (on or off) after 200 s. Especially, PyHBTPI displayed effective solubility, superior optical contrast (~30%) in the visible region, faster response time (1.19 s for coloring process), and obvious color change from yellow to blue with good stability, thus, confirming the potential use for high contrast displays. Overall, the study demonstrates the successful development of high-performance polyimides for electrochromic and optoelectronic behaviors. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137 , 48808.