2D Conjugated Metal-Organic Frameworks for New Generation Flexible Multicolor Electrochromic Devices.

There has been considerable interest in 2D conductive conjugated MOFs (2D c-MOFs) for their potential applications in sensors, opto-electronics, catalysis, and energy storage, owing to their ultra-high specific surface area, relatively high electrical conductivity, and tunable pore channel sizes for ion/charge diffusion/adsorption. The unique advantages brought by systematic tunings in the metal nodes and organic ligands enable the creation of highly accessible and remarkable structures with diverse chemical and physical behaviors. While the 2D c-MOFs are being explored for the rapid widening spectrum of applications, in this work, the great potential of multicolor transitions and functional properties of these 2D c-MOFs are examined for the new generation of flexible multicolor electrochromic devices (FMEDs). Despite the rather limited and yet steady progress that has been made so far, 2D c-MOFs offer great opportunities in addressing the monotonous color switching, undesirable stability, as well as the sluggish kinetics of electron/ion transportation, which are typically encountered by the conventional electrochromic materials. Together with the main challenges that are being faced, this perspective provides a timely re-visit to the expected transition in the near future from the proof-of-concept demonstration to the eventual industrial-scale implementation of 2D c-MOFs in the new generation FEMDs.