Fe(II)–bis(terpyridine) units were covalently embedded on the extended surface of the indium tin oxide (ITO) support, and oligomeric molecular wires derived from these units were subsequently grown using a diazonium electrografting under ambient temperature and pressure. The resulting smart material exhibits excellent electrochromic performance, changing its optical properties in response to external voltage, both in a liquid electrolyte (3-electrode cell) and when assembled into a solid-state electrochromic device (2-electrode cell). Electrografting molecular architectures within interparticle pores results in dense molecular packing, as confirmed by surface coverage measurements and the presence of π–π* satellites in both the C 1s and N 1s X-ray photoelectron spectra. Electrografting is more time-efficient than the conventional layer-by-layer growth of coordination-based molecular assemblies. Moreover, it eliminates the need for a separate surface templating layer, resulting in enhanced conductivity through the molecular wire. Thus, the electron transfer rate of the developed material is in par with that of monolayer-based materials. The electrochromic devices were assembled by incorporating the material and surface-enhanced ITO as electrodes through a lithium gel electrolyte and a Nafion layer. In-operando measured optical properties demonstrate that the device exhibits extremely high cycling stability, notable coloration efficiency, and short switching times.
Jadali et al. (2026) studied this question.