Electrochromic behavior of dimethyl terephthalate in ionic liquids-based quasi-solid matrices

This study reports a solid-state electrochromic device (ECD) based on dimethylterephthalate (DMT), demonstrating high stability and low operating voltage on both rigid and flexible substrates. DMT molecules were incorporated into a poly(vinylidene fluoride- co -hexafluoropropylene) ionogel (IG) using ionic liquids as environmentally friendly electrolytes. Cyclic voltammetry and in-situ spectroelectrochemistry were employed to investigate the electrochromic mechanism in the DMT@IG system. An ECD with two electrodes was fabricated on ITO-coated glass, operating at a low potential difference of 2 V, with bleaching times of 2.06 seconds, coloration times of 5.92 seconds, an optical contrast of 21%, and a color efficiency of 147.7 cm² C⁻¹. The device maintained stability for up to 30 cycles. Furthermore, a flexible three-electrode configuration with a DMT@IG membrane was designed, confirming DMT's potential as an advantageous material for low-voltage electrochromic and flexible display applications.