Multi‐Timescale UV Memory With Wavelength‐Programmable Retention for Robust Graded Discharge‐Risk Warning

Graded ultraviolet (UV) arc‐discharge warning requires optoelectronic memory that converts transient UV inputs into photocurrent traces retaining both recent signal changes and longer discharge history. Here, we report a C8‐BTBT/Sr 2 Nb 3 O 10 heterostructure for wavelength‐programmable multi‐timescale UV memory. Inspired by wavelength‐selective photoreception in mantis shrimp eyes, the heterostructure maps different UV excitation wavelengths onto distinct photocurrent‐decay profiles, achieving an approximately 44‐fold separation in the decay time between 350 and 280 nm excitation, with the device response evolving from rapid recovery to sustained retention. This wavelength‐dependent relaxation is supported by optical‐gap contrast, staggered energy alignment, and oxygen‐vacancy‐associated trapping, establishing the physical basis for multi‐timescale UV memory. Applied to graded discharge‐risk warning, the multiwavelength memory readout recognizes the early‐warning state with 99.2% accuracy under normal monitoring and increases the disturbed‐condition average accuracy by 29.3 percentage points relative to no‐memory readout. These results establish excitation‐wavelength‐programmed UV memory as a front‐end strategy for temporal readout and robust graded risk warning.