Bio-hybrid light-emitting diodes (Bio-HLEDs) based on color down-converting filters with fluorescent proteins (FPs) have achieved moderate efficiencies (50 lm/W) and stabilities (300 h) due to both thermal-and photo-degradation. Here, we present a significant enhancement in efficiency (~130 lm/W) and stability (>150 days) using a zero-thermalquenching bio-phosphor design. This is achieved shielding the FP surface with a hydrophilic polymer allowing their homogenous integration into the network of a light-guiding and hydrophobic host polymer. We rationalize how the control of the mechanical and optical features of this bio-phosphor is paramount towards highly stable and efficient Bio-HLEDs, regardless of the operation conditions. This is validated by the relationships between the stiffness of the FP-polymer phosphor and the maximum temperature reached under device operation as well as the transmittance of the filters and device efficiency.

This work presents a pioneering multidisciplinary approach toward enhancing biohybrid light-emitting diodes (BioHLEDs), merging synthetic biology tools, polymer chemistry, and device engineering to design a thin color down-converting coating with a single white-emitting fluorescent protein (WFP). In particular, the WFP consists of fused red-, green-, and blue-emitting FPs following the so-called protein superglue approach. This WFP shows an efficient and stable white emission originated from a Förster resonance energy transfer between FP moieties. The emission chromaticity is, in addition, easily controlled by the rigidity of the polymer matrix of the coating, reaching photoluminescence quantum yields of 26% that stand out among intrinsic white-emitting materials. The WFP single-component color down-converting packaging was applied to fabricate BioHLEDs featuring efficient neutral white emission that is stable over 400 h. This represents the most stable BioHLED reported to date. Thus, this work is a landmark for the use of synthetic biology tools to design tailored luminescent biomaterials for lighting applications.