Performance optimization and functional integration in emerging electrochromic device architectures

Electrochromic devices (ECDs) are evolving from single-function optical modulators into multifunctional platforms capable of regulating light, heat, energy storage, and sensing. In particular, dual-band electrochromic systems that independently modulate visible and near-infrared radiation have emerged as a promising strategy for efficient solar spectrum management, addressing the limitation of conventional electrochromic materials that primarily operate in the visible region. This review critically examines recent advances in dual-band ECDs, with emphasis on material design principles that combine redox-induced polaronic absorption with localized surface plasmon resonance in doped and non-stoichiometric metal oxides and hybrid nanocomposites. Beyond material chemistry, we analyze how device architectures such as plasmonic heterostructures, metal-dielectric-metal electrodes, Fabry-Perot nanocavities, and self-powered configurations govern spectral selectivity, switching kinetics, and durability. Furthermore, emerging multifunctional electrochromic systems that integrate energy storage, photovoltaics, nanogenerators, and biosensing functionalities are systematically discussed through the lens of electrochemical energy storage and optical modulation. By identifying key performance trade-offs between optical contrast, charge capacity, cycling stability, and scalability, this review provides a framework for rationally designing next-generation multifunctional ECDs toward practical smart window, display, and energy-adaptive applications.