W/WO₃/TiO₂ Multilayer Film with Elevated Electrochromic and Capacitive Properties

Area of Science:

• Materials Science
• Electrochemistry
• Nanotechnology

Background:

• Electrochromic capacitors offer tunable appearances with charge state.
• Tungsten oxide (WO3) is a common material but provides limited color modulation (transparent to blue).
• Achieving desirable visual aesthetics in electrochromic capacitors remains a challenge.

Purpose of the Study:

• To design and investigate W/WO3/TiO2 multilayer films for improved electrochromic capacitor performance.
• To explore the impact of TiO2 layer thickness on optical and electrochemical properties.
• To develop electrochromic capacitors with enhanced visual aesthetics and energy storage capabilities.

Main Methods:

• Fabrication of W/WO3/TiO2 multilayer films using magnetron sputtering.
• Systematic investigation of the effect of TiO2 layer thickness.
• Characterization of optical and electrochemical properties, including coloration efficiency, areal capacitance, rate performance, and cycle life.

Main Results:

• The optimal TiO2 layer thickness was determined to be 10 nm.
• The optimized film exhibited a high coloration efficiency (CE) of 74.2 cm²/C.
• Excellent areal capacitance (32.0 mF/cm²), rate performance (87% retention at 1 mA/cm²), and cycle stability (91% retention after 1000 cycles) were achieved.

Conclusions:

• The W/WO3/TiO2 multilayer structure significantly enhances the performance of electrochromic capacitors.
• The optimized TiO2 layer thickness is crucial for achieving superior optical and electrochemical properties.
• These findings present a viable pathway for developing advanced electrochromic capacitors with both aesthetic appeal and high functionality.