Fully Coplanar Ladder Phenazine‐Based n‐Type Polymer for High‐Performance Electrochromic Energy Storage Using Zn ²⁺ /H ⁺ Hybrid Aqueous Electrolyte in an Atmospheric Environment

Conjugated polymer‐based electrochromic energy storage materials are promising for visual energy storage devices due to their tunable color, high optical contrast, and mechanical flexibility. However, the development of n‐type polymer‐based electrochromic materials that exhibit high cycling stability in both air and aqueous electrolytes, along with high energy density, remains a major challenge. In this present, a simple electrochemical polymerization method was successfully employed to synthesize poly(o‐phenylenediamine) (PoPD) electrochromic films. PoPD exhibits high electron transport, robust electrochemical stability, and low driving voltage, originating from its fully coplanar, ladder‐type rigid conjugated structure and high electron affinity. In addition, Employing an aqueous H + /Zn 2+ hybrid‐ion electrolyte remarkably enhanced the electrochromic kinetics of PoPD, resulting in superior overall performance. With a 1:1 H + /Zn 2+ aqueous electrolyte, the PoPD film achieved a high coloration efficiency (81.58 cm 2 /C), fast switching (6.3 s for coloring and 2.9s for bleaching), excellent cycling stability (90.71% optical contrast retention after 1000 cycles and 94.51% current density retention after 3000 cycles), and a specific capacity of 157.22 mAh/g. Synergistic H + /Zn 2+ co‐insertion/extraction enhances the electrochemical performance of PoPD. Rigid fully coplanar ladder‐type phenazine‐based conjugated polymers exhibit enormous potential in enabling high‐performance air and aqueous‐based electrochromic energy storage devices, and organic electrochemical transistors.