Multicolored electrochromic metallopolymers based on triphenylamine-substituted terpyridine coordination with transition metal ions

The design and synthesis of multicolored electrochromic materials are essential for advancing dynamic display technologies and enhancing the functionality of smart materials in various applications. Here, we have developed a series of triphenylamine-substituted terpyridine coordination metallopolymer (CMP) films through one-step electrochemical polymerization, utilizing six different transition metal ions: Fe²⁺, Ru²⁺, Zn²⁺, Co²⁺, Pd²⁺, and Ni²⁺. These metal ions serve as redox centers, combined with triphenylamine, to produce CMP films exhibiting exceptional color change performance (ΔT: 59.8 % at 700 nm for p-FeL₂) as well as high coloration efficiency (307.8 cm² C⁻¹ for p-FeL₂). The electrochromic properties of the six metal-coordinated polymer films were systematically compared, providing a comprehensive analysis of the structure-electrochromic property relationship driven by the varying metal-to-ligand charge transfer effects associated with different metal ions. Additionally, we integrated the CMP films with V₂O₅ to create a hybrid electrochromic device, which demonstrated reversible color changes. These results highlight the potential of CMP films for developing multicolor displays and advancing electrochromic technologies.