Multifunctional donor–acceptor conjugated polymers containing isoindigo and benzothiadiazole moieties for electrochromic, photoelectric sensor, 2,4,6-trinitrophenol detection and resistance memory device

Six novel donor–acceptor conjugated polymers were designed and synthesized by the Stille coupling reaction of triarylamine derivatives as donor units with isoindigo derivative or benzothiadiazole as acceptor units. These polymers have good solubility and film-forming properties in common organic solvents. The char yields of polymers in nitrogen atmosphere at 800 °C range from 34 to 60%. In particular, these conjugated polymers exhibit high photoluminescence (PL) quantum efficiency (up to 42.9%). These polymers demonstrate two pairs of redox peaks with low onset voltages (0.51 V vs. Ag/AgCl for P5) and narrow band gaps (Eg = 2.52 ~ 2.95 eV). The colors of all polymer films change significantly with the applied voltage increasing. Moreover, the polymers show high coloring efficiency (up to 163%) and maintain good electrochromic (EC) cycle stability over 500 s. In addition, excellent results in terms of memory storage (ON/OFF = 1.2 × 104), 2,4,6-Trinitrophenol (TNP) detection (Ksv = 45,790 M-1) can meet the requirements of multifunctional materials.