Metal-Organic Framework-Based Flexible Devices with Simultaneous Electrochromic and Electrofluorochromic Functions

In this work, taking advantage of redox-active metal-organic frameworks (MOFs), a flexible MOF-based device with simultaneous electrochromic and electrofluorochromic (EC-EFC) functions is realized for the first time. The redox-active MOF film is constructed by fast one-step cathodic electrodeposition on flexible conductive substrates from a solution containing triphenylamine, an electrochromic and fluorescent ligand, and Zn2+ ions. Due to redox nitrogen in the ligand, the flexible device can achieve color switch between pale yellow and deep blue in response to external potentials, and the color change is accompanied with fluorescence quenching and recovery. In addition, benefiting from the high specific surface area and hierarchical porous structure of the MOF film, the device shows fast switching time of 4.5 and 6.2 s for oxidization and reduction processes, respectively, and there is no obvious attenuation after cycling for 3000 s. Such EC-EFC devices have good potential to be applied as displays for various types of portable/wearable consumer products.