Simple Encoded Circularly Polarized Protein Lighting

Lighting systems with circularly polarized luminescence (CPL) are an emerging field with high hopes in, for example, neural cell circuits and encoding applications. The major challenges that forfeits their real-world application are i) the design of chiroptical materials (CMs) with high CPL brightness (B_CPL; today's record is Eu-based compounds with average 287 M⁻¹cm⁻¹, while 90% of other CMs show <150 M⁻¹cm⁻¹ in solution) and ii) how to keep CPL response in films/coatings of technological relevance. Since natural evolution is driven by chiral selectivity at the supramolecular level, fluorescent proteins (FPs) are ideal candidates to provide large B_CPL spanning visible and near-infrared regions. This hypothesis is confirmed for all the known FP classes, demonstrating high emission intensities (photoluminescence quantum yields (ϕ) up to 76%) and record average B_CPL of |200| M⁻¹cm⁻¹ (solution). What is more, the CPL response is also kept in polymer coatings. It is rationalized that structural factors (chromophore rigidity, surrounding amino acids, supramolecular packaging, and exciton coupling) hold a significant influence, regardless of the ϕ values. Finally, proof-of-concept CPL-encoded signals in monochromatic/white hybrid light-emitting diodes with FP-polymer filters show exceptional stabilities. Overall, this work stands out FPs toward a new CM family, in general, and biogenic CPL-encoded lighting systems, in particular.