Enhanced colour modulation in printed electrochromic pixels via optimization of a polymer gel electrolyte

With the growing demand for thinner and more flexible electrochromic devices (ECDs), proper electrolyte selection is critical for the design and implementation of these systems. Compared to a traditional liquid electrolyte, polymer gel electrolytes have received growing application in ECDs due to their efficient ion transport, high stability, and, most importantly, zero risk of leakage during device integration. In this work, we capitalize on these features in the design, fabrication, and testing of a flexible and multifunctional polymer gel electrolyte using a polyvinylidene fluoride-co-hexafluoropropylene (PVDF-HFP) matrix enriched with ionic liquids and plasticizers that interface with adjacent electrochromic pixels. This polymer gel electrolyte remains stable at room temperature, enabling operation of ECD pixel elements over 2750 cycles and 2.5 days of continuous operation. Applications such as passive color filtering using the electrolyte are also explored, highlighting its potential to improve operation and expand colour range without modification of the electrochromic film.