Poly(vinyl alcohol) (PVA) is a benchmark matrix for room-temperature phosphorescence (RTP) due to its oxygen barrier properties. However, the impact of trace oxygen trapped during ambient preparation on triplet-state photophysics is often overlooked. Here, we propose a trace oxygen engineering strategy to simultaneously amplify phosphorescence efficiency and dissymmetry factors (glum). By doping chiral binaphthyl phosphate derivatives (R/S-TCP) into PVA, a photoresponsive circularly polarized phosphorescence (CPP) system was developed. Experimental and theoretical results reveal that UV-activation triggers deoxygenation, eliminating triplet quenchers and unlocking radiative pathways. Consequently, the phosphorescence lifetime extends from 0.51 to 1.25 s, and the quantum yield increases from 4.6% to 17.3%. Moreover, the CPP signal evolves from near-noise level to a well-defined state with a high glum of 1.0 × 10–2. Notably, even under vacuum (10–3 bar), photoactivation is still observed, revealing that trace oxygen trapped within the PVA matrix during film fabrication─rather than atmospheric oxygen alone─plays a critical role in triplet-state dynamics. Furthermore, integrating a Förster resonance energy transfer mechanism enables multicolor afterglow tuning for high-level optical encryption and anticounterfeiting. This work highlights the decisive role of micro-oxygen environments in chiral triplet dynamics and provides a universal approach for advanced smart chiroptical materials.
Zhu et al. (2026) studied this question.