Photoswitching between black and colourless spectra exhibits resettable spatiotemporal logic

Logic is the key to computing. Traditionally, logic devices have been fabricated by the top-down approach, whose dimensions are drastically limited. The ultimate goal is to use molecular tailorability to design logics using the bottom-up'' approach. Here we report an unprecedented photochromic molecule that undergoes unimolecular logic switching when excited anywhere in the entire UV-visible spectrum, thus a bottom-up, all-photonic, molecular logic gate. Specifically, these molecular photonic logics embedded in the polymer thin films function as the AND'' or OR'' gate at different temporal responses. To achieve high information-processing density, moreover, a ternary flip-flap-flop gate is realized in the molecular logic because the fact that this photochromic molecule can be photoswitched anywhere in its UV-vis spectrum enabled three different lasers (532, 473, and 561 nm) as the inputs to deliver the complex logic optical outputs.