Multicolored, Low-Power, Flexible Electrochromic Devices Based on Ion Gels

Area of Science:

• Materials Science
• Electrochemistry
• Polymer Science

Background:

• Ion gels, solid-state electrolytes combining copolymers and ionic liquids, offer high ionic conductivity, flexibility, and solution processability.
• Functionalization of ion gels with redox-active species like electrochromic (EC) dyes enables advanced applications.
• Existing electrochromic devices (ECDs) can be improved for multicolor capabilities and lower power consumption.

Purpose of the Study:

• To enhance the functionality of electrochromic (EC) gels for multicolor electrochromic devices (ECDs).
• To explore methods for achieving multicolored displays by controlling EC species equilibrium or modifying molecular structures.
• To demonstrate the fabrication and performance of flexible, patterned, multicolored ECDs.

Main Methods:

• Fabrication of EC gels by incorporating redox-active EC species.
• Manipulation of chemical equilibrium between monomer and dimer forms of EC species.
• Modification of molecular structures of EC species to tune color properties.
• Development of a "cut-and-stick" fabrication strategy for ECDs.
• Characterization of power consumption for maintaining colored states in blue, green, and red ECDs.

Main Results:

• Successfully realized multicolored ECDs by controlling EC species.
• Achieved low power consumption for maintaining colored states: blue (90 μW/cm²), green (4 μW/cm²), and red (32 μW/cm²).
• Demonstrated a patterned, multicolored, flexible ECD on plastic substrate.
• The developed ECDs exhibit excellent flexibility and solution processability.

Conclusions:

• Enhanced EC gels offer a viable route to multicolor ECDs.
• The "cut-and-stick" fabrication method simplifies device production.
• Low power requirements and flexibility make these ECDs suitable for printed electronics.
• Gel-based ECDs show significant potential for low-power display applications, particularly when powered by thin-film batteries.