Synergistic LSPR and Interfacial Built-in Electric Field in Au/WO3 Film for High-Performance Flexible Electrochromic Smart Window

Abstract

Electrochromic (EC) technology enables reversible optical modulation under external electric stimuli, emerging as a cornerstone for next-generation smart windows and low-power displays. However, inorganic EC materials such as tungsten oxide (WO₃) generally suffer from slow response speed, low coloration efficiency and poor flexibility arising from dense microstructure and brittleness, which greatly constrained their practical deployment. Herein, we reported Au nanoparticles (AuNPs)/WO₃ heterofilm that synergistically harness the localized surface plasmon resonance (LSPR) effect of AuNPs and the built-in electric field at the AuNPs/WO₃ heterointerface. This synergy greatly boosted the electron/ion transport kinetics and light-matter interaction, delivering exceptional EC performance with ultrafast switching (2.0 and 0.7 s for coloration and bleaching), remarkable coloration and bleaching efficiencies of 187 and 680 cm 2 C -1 , as well as 90% optical contrast retention after 1000 cycles. A 6 cm × 6 cm flexible EC smart window assembled with this heterofilm exhibits dynamic transmittance modulation and excellent mechanical robustness, with negligible performance loss after 100 bending cycles. This work provides a facile, scalable plasmonic-interface engineering route to overcome intrinsic limitations of inorganic EC materials, extendable to other transition metal oxide systems for high-performance flexible optoelectronics.