Triplet-mediated waveguiding and energy transfer in organic phosphors on cellulose

Purely organic emitters can generate long-lived phosphorescence at room temperature. With their extremely low toxicity and environmentally friendly processes, their extended emissive decay, often lasting several milliseconds, combined with high quantum yields makes them promising for a range of emission and sensory platforms. Room temperature phosphorescence (RTP) is highly dependent on both the crystallinity and geometry of organic crystals, which are significantly influenced by the surrounding environments. Key factors include organic solvents in which organic emitters are dissolved or dispersed, the surface properties where the organic crystal is grown, and nearby adjacent emitters. This work presents a strategy for forming nanorod-shaped purely organic chromophores that exhibit RTP through hybridization with host molecules on an eco-friendly cellulose membrane. Tuning the crystal morphology significantly influences the photophysical properties and enhances phosphorescence efficiency while enabling waveguided emission along a one-dimensional geometry. Finally, to exploit the ultralong phosphorescent lifetime in the millisecond regime, phosphorescence resonance energy transfer was achieved by coupling with Rhodamine B, an organic fluorophore, highlighting the potential for tunable emission through the formation of an amorphous interface at the contact region.