Quasi-heavy atom effect for room-temperature phosphorescence

= 455 nm, quantum efficiency: 8.72%, lifetime: 4.20 s) only within a PVA matrix. This suggests an unrecognized intrinsic PVA property promoting efficient SOC and ISC. We propose a novel "quasi-heavy atom effect," where PVA's unique characteristics facilitate SOC similar to heavy atoms, but without their toxicity or cost. This understanding is critical for designing novel RTP materials.