From color control to machine perception: Electrochromic materials as spectral information encoders

Electrochromic materials can do more than change color: their electrically programmable optical states can weight incident light across wavelength before detection. This perspective considers these materials as spectral information encoders for compact machine perception. It explains how a material–device system converts a spectrum into a set of photocurrents through calibrated spectral responses, and how a spectral-state library links accessible material states to their programming conditions. It outlines a design framework that connects materials chemistry, ion transport, photonic structures, and detection to application requirements. It also discusses why spectral diversity, reproducibility, and downstream task performance complement conventional electrochromic metrics. Long-term response repeatability and calibration stability remain essential requirements for translating programmable spectral encoding into reliable imaging systems.