Catalyzing Viologen Electrochromic Reaction with CuO_x Nanoparticles

Viologen-based electrochromic devices have attracted great attention because of their tremendous potential in building energy conservation and low power display. However, the unsatisfactory performance at lower voltage limits their application, while the high driving voltage increases the energy consumption as well as safety risk. Herein, an electrocatalytic strategy is proposed for high-performance viologen-based electrochromic devices. Copper oxide (CuO_x) nanoparticles are uniformly deposited on the F-doped Tin Oxide (FTO) glass for enhancing the catalytic activity of Br⁻/Br₃⁻ redox couple, thereby promoting the interfacial charge transfer. The driving voltage can be reduced by ≈30% without sacrificing its high transparency (up to 80%) and the cycling stability can be significantly improved within 200 cycles. Large-area smart windows and electrochromic displays are fabricated, which can be driven by the 1.5 V dry battery. This work opens up a new path to optimize the electrochromic performance of viologens and also lays the foundation for the application of catalysis in optoelectronic devices.