Green Light-Responsive Electrochromic Device with Yellow-to-Green Color Switching for Optimizing Adaptive Visible Camouflage Systems

Compared to static camouflage's fixed mode, adaptive systems utilizing electrochromic (EC) technology dynamically adjust colors and patterns to fit changing environments, greatly enhancing concealment and adaptability. However, the system necessitates sensing, processing, and EC response modules, which increases complexity and costs. In this work, the photoresponsive cadmium sulfide (CdS) yellow nanoparticles are synthesized and incorporated into an ethyl viologen-based EC ionogel (transparent/blue), thereby endowing the device with the ability to sense green light. Due to the superposition of yellow/blue colors, the device transitions from yellow (bleached state, 0 V) to deep green (colored state, -1.2 V). The yellow and green colors of the device are similar to two common camouflage colors (ΔE < 10) while also exhibiting fast switching speed (t_c/t_b: 2.0/2.5 s) and excellent cycling stability (maintain 98% after 5000 cycles). By connecting with a microcontroller, an adaptive EC camouflage system capable of detecting green light and transitioning from yellow to green is successfully developed. The above results show this system's application potential and demonstrate the effectiveness of photoresponsive/EC technologies in optimizing adaptive visible camouflage systems.