Exploring the electrochromic and electrofluorochromic responses triggered by carbazole when grafted on triphenylmethane in polyimide

We report a facile strategy for developing electro(fluoro)chromic (EC/EFC) polyimides by incorporating a new structurally designed diamine containing carbazole-substituted triphenylmethane, which serves as a building block responsible for the EC/EFC effects. Three dianhydrides with variable planarity and flexibility were selected to construct the polyimides, which proved to play an essential role in tailoring the EC/EFC response. Besides structural and physico-chemical characterization, a detailed study was carried out concerning their electrochemical behavior, highlighting the formation of polymer dimers or polymer networks by electropolymerization contingent on the macromolecule's solid-state arrangements. We have demonstrated that the dimerization process leads to polymer structures with a relatively high EC efficiency (up to 372 cm²/C) and significant recovery of this parameter (up to 96 %) after 100 cycles. Although the polymers exhibited high emission in the solid-state via the AIE effect, this was effectively reduced by applying oxidation potentials as a result of initial geometry orientation changing. Thus, the present polyimides can simultaneously integrate EC and EFC characteristics, suggesting that dimerization and aggregation can be considered appropriate pathways to improve the EC/EFC behavior of polymers containing carbazole units.