Molecular design enables color-fluorescence alignment in electrochromic/electrofluorochromic displays

The spectral mismatch between the reflective electrochromic (EC) state and the emissive electrofluorochromic (EFC) state fundamentally limits the practical implementation of EC/EFC displays for adaptive visual interfaces. Here, we present a rational molecular-level design that achieves intrinsic color-fluorescence alignment through a single donor-acceptor chromophore. Redox-tuned intramolecular charge transfer enables synchronized modulation of absorption and emission, thus resolving the longstanding EC/EFC performance trade-off. This intrinsic optical alignment is further stabilized within a tailored ionic liquid matrix that suppresses aggregation. The resulting device delivers benchmark performance, including ultralow bidirectional switching voltages (<1.1 V), sub-second response times (<1.0 s), high optical contrast, and excellent stability. To demonstrate practical utility, we develop a low-energy, dual-mode traffic signaling system that seamlessly integrates EC and EFC functions for continuous operation under varying light conditions. This work establishes a generalized strategy for dual-mode optical materials, advancing reliable and energy-efficient next-generation display technologies.