Color-tunable and high quantum-yield luminescence from a biomolecule-inspired single species emitter of white light


Single-species light emitters with high photoluminescence quantum yields (PLQYs) and broad- spectrum color tunability are sought-after for applications ranging from bio-imaging to artificial lighting. We explore a new strategy to design such emitters, inspired by bioluminescent fireflies and click-beetles. These organisms use a single molecular substrate, D-Luciferin (LH2), to emit light ranging in color from green to red. By combining LH2 with metals, we synthesize new bio-analogous, color-tunable, luminescent metal complexes. The copper complex forms an organic molecule of intrinsic microporosity (OMIM), which crystallizes into a stable structure with intermolecular voids. By changing the composition of guest molecules in the voids, we can tune the emitted color. The optimum composition gives nearly perfect white light, with the highest PLQY reported for a single-species white- light emitter. Similarities between our OMIM and the luciferase active site provide a new approach to investigating the heavily-debated mechanisms underlying in-vivo bioluminescence color variations. Moreover, as a proof of principle, we show that these materials can be used in a new type of light- emitting device (LED). The current generation of LEDs requires at least two active layers to achieve color tunability. The tunability is intrinsic in our materials, and therefore may lead to simpler device fabrication.