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Designing surface-confined molecular systems capable of expressing changes in functional properties as a result of slight variations in chemical structure under the influence of an external stimulus is of contemporary interest. In this context, we have designed three tetraterpyridine ligands with variations in their core architecture (phenyl vs tetraphenylethynyl vs bithiophene) to create spray-coated electrochromic assemblies of iron(II)-based metallosupramolecular polymer network films on transparent conducting oxide substrates. These assemblies exhibited molecular permeability and spectroelectrochemical properties that are in turn dictated by the ligand structure. Electrochromic films with high coloration efficiencies (up to 1050 cm2/C) and superior optical contrast (up to 76%) with a concomitant color-to-color redox transition were readily achieved. These functional switching elements were integrated into sandwich-type electrochromic cells (CE up to 641 cm2/C) that exhibited high contrast ratios of up to 56%, with attractive ON-OFF ratios, fast switching kinetics, and high operational stability. Every measurable spectroelectrochemical property of the films and devices is an associated function of the ligand structure that coordinates the same metal ion to different extents. While exhibiting a ligand-structure induced differential metal coordination leading to porosity and spectroelectrochemical diversification, these assemblies allow the creation of electrochromic patterns and images by a simple spray-coating technique.

A generic strategy of incorporating diverse functions in electrochromic dynamic windows is presented by sensibly choosing the individual layers of a bilayered active electrode. Here, all-solid electrochromic devices (ECD) with a remarkably high visible modulation (60–80%) and superior near-infrared (NIR) shielding performance (>90% full scale) were fabricated by simple solution-processing. The concept is demonstrated by selecting materials with identical chemical composition, i.e., porous amorphous-WO3 (a-WO3) coated on top of polycrystalline WO3·H2O nanosheets. These ECDs show four distinct voltage-selective modes in the ± 2.8 V range for enhanced privacy and energy saving. The IR modulation efficiency (IRME) of the devices stands at a record ~85%, with an outstanding solar modulation efficiency (SME) of ~63%. The initial energy storage estimations for the ECDs revealed superior volumetric stored charge density of ~400 Ccm−3@ 10 mVs−1, which is excellent for secondary energy sourcing. The fabricated EC glasses (with 50% usage) could directly save ~165 kWhm-2 yr-1 worth of energy by equating the energy-saving and generation. With reflected radiation reduction, the total saving may surpass the total energy generation from standard Si-Solar cells (~18% efficiency) of equal areal coverage.