High-contrast electrochromic nano fiber films changing from yellow-green to black based on butterfly monomer for smart windows and self-adaptive camouflage

High contrast electrochromic (EC) materials have attracted much attention due to their great potential for applications in fields such as electronic displays, smart windows (thermal management) and adaptive camouflage. However, obtaining EC materials with high contrast and long term stability is still a challenge. Herein, we designed and synthesized a butterfly (large planar core-distorted periphery) diamine monomer (DCTPA-NH 2 ) by fusing two triphenylamine (TPA) units on edge of 7H-dibenzocarbazolyl, and prepared four polyamides (PAs) through polycondensation of the monomer with different diacids, which exhibit excellent solution processability, thermal stability, electrochemical redox reversibility. The PAs aggregate to form fibrous film. Among them, the fibrous DCTPA-SA film exhibits high contrast in visible regions (optical contrast of 85 % at 960 nm and 63 % at 555 nm) and near infrared region, fast voltage-optical response (coloring time/bleaching time, 1.5 s/2.0 s), high coloring efficiency (241 cm 2 C -1 ), and good cycling stability (optical contrast after 500 cycles is 76 % of the initial one) due to fast diffuse of ions. In addition, DCTPA-CA exhibits fluorescence (PL) quantum efficiency up to 30.1 % and is sensitive to trinitrophenol (TNP), which is expected to be applied in explosives detection. At last, DCTPA-SA fibrous film device was fabricated for EC devices, smart windows and self-adaptive camouflage models, showing promising application.