Fully Biogenic Near-Infrared Phosphors: Phycobiliproteins and Cellulose at Force Toward Highly Efficient and Stable Bio-Hybrid Light-Emitting Diodes

Stable/efficient low-energy emitters for photon down-conversion in bio-hybrid light-emitting diodes (Bio-HLEDs) are still challenging, as the archetypal fluorescent protein (FP) mCherry has led to the best deep-red Bio-HLEDs with poor stabilities: 3 h (on-chip)/160 h (remote). Capitalizing on the excellent refolding under temperature/pH/chemical stress, high brightness, and high compatibility with polysaccharides of phycobiliproteins (smURFP), first-class low-energy emitting Bio-HLEDs are achieved. They outperform those with mCherry regardless of using reference polyethylene oxide (on-chip: 24 h vs. 3 h) and new biopolymer hydroxypropyl cellulose (HPC; on-chip: 44 h vs. 3 h) coatings. Fine optimization of smURFP-HPC-coatings leads to stable record devices (on-chip: 2600 h/108 days) compared to champion devices with perylene diimides (on-chip: <700 h) and artificial FPs (on-chip: 35 h). Finally, spectroscopy/computational/thermal assays confirm that device degradation is related to the photo-induced reduction of biliverdin to bilirubin. Overall, this study pinpoints a new family of biogenic emitters toward superior protein-based lighting.