Inorganic all-solid-state composite structure for dynamic color

Dynamic color modulation holds great promise for next-generation display technologies, offering wide applicability in smart displays, adaptive surfaces, and wearable electronics. However, conventional WO₃-based electrochromic (EC) devices face inherent limitations, making it difficult to simultaneously achieve broad color tunability and rapid response performance. Here, we proposed an inorganic all-solid-state composite structure that synergistically integrates structural color and WO₃-based EC modulation via color superposition. The underlying Ag/Al₂O₃/Ni/Al₂O₃ stack provides static structural coloration, while the top ITO/WO₃/LiTaO₃/NiO/ITO stack enables dynamic, voltage-controlled color tuning. The resulting composite structure achieves precise, reversible color modulation under 1.5 V, with colored and bleached times of 2.5 and 1 s, respectively, and excellent stability over 1000 cycles. After applying the voltage to induce coloration, the device can maintain its colored state without a continuous power supply, demonstrating the intrinsic non-volatile EC behavior. This integrated approach effectively overcomes the narrow color range and sluggish switching of conventional WO₃-based EC systems, providing a simple-to-fabricate, versatile, and energy-efficient platform for high-performance adaptive optical devices. Looking ahead, extending the color tunability of EC layers or introducing multiple EC modulation layers could further expand the dynamic color range, paving the way for multicolor, reconfigurable reflective displays and smart optical systems.