Redox-Active Ni(II) Nodes Induced Electrochromism in a Two-Dimensional Conductive Metal–Organic Framework

Metal–organic frameworks (MOFs) are highly desired for electrochromic (EC) applications because of their designable porous structures for fast ionic transport. However, the intrinsic low electronic conductivity of traditional MOF-based EC materials leads to a slow switching speed, poor coloration efficiency, and unfavorable cyclability. Conductive MOFs, with a tunable porous crystal structure and highly improved electronic conductivity, are proposed as promising candidates to achieve synchronous high-speed transport of electrons and ions in the EC process. Here we demonstrate fast and high-coloration-efficiency EC electrodes based on interfacially assembled conductive MOF Ni3(HITP)2 films. The reversible EC behavior of Ni3(HITP)2 is systematically explored and elaborated as the redox of Ni nodes in the crystal. Finally, we demonstrate MOFs-based devices that could potentially be used in fields such as digital displays and optical modulation.