Electrochromic-supercapacitor (ECS) that integrate dynamic optical modulation and electrochemical energy storage have attracted increasing attention for advanced display and energy-related applications. Herein, two donor-acceptor type electrochromic materials (pBQ and pDQ), incorporating pyrazine and pyridazine isomeric units, were synthesized to investigate the structural effects of diazine isomers on backbone conformation, optical modulation, and energy storage performance. The position of nitrogen atoms within diazine units effectively regulates molecular planarity and π-electron delocalization, and the pyrazine-based pBQ exhibits a more planar backbone with smaller dihedral angles (0.9^° and 4.3^°) compared with pDQ (13.1^° and 12.9^°). pBQ demonstrates vivid magenta coloration in the neutral state and highly transparent oxidized state, achieving a high color saturation of 51.82 and a low oxidized-state chroma of 0.26. Moreover, pBQ exhibits excellent electrochromic performance, including a coloration efficiency of 279.5 cm² C^-1, fast switching times of 1.12 s/0.56 s, and outstanding cycling stability with over 90% retention after 1000 cycles. Furthermore, pBQ also displays superior energy storage capability with an area-specific capacitance of 2.61 mF cm^-2. The fabricated prototype ECS devices based on pBQ enable reversible information display and energy storage functions simultaneously.
 

Diazine isomers Electrochromic-supercapacitor bifunctional Color control