Ultra-Linear Afterglow Oxygen Sensing and Visualization in Morphology-Engineered Phosphorescent Microporous Copolymers

Phosphorescence-based oxygen sensors offer an efficient route to rapid oxygen visualization, yet their practical deployment is often hindered by nonlinear Stern-Volmer responses and low sensitivity arising from heterogeneous microenvironments in physically mixed systems. Here, we report a scalable morphological-engineering strategy to construct microporous films with room-temperature phosphorescence (RTP) that show ultralinear oxygen sensing. Triphenylamine-derived phosphors are covalently integrated into amphiphilic copolymers composed of hydrophobic and hydrophilic segments, effectively suppressing phosphor aggregation. By judiciously selecting volatile nonazeotropic and azeotropic mixed solvents, we direct the formation of interconnected microporous networks or perforated microcells, thereby dramatically increasing the quenchable phosphorescent fraction. The resulting films exhibit long RTP lifetimes (∼100 ms) and ultralinear oxygen sensing (R2 > 0.999) with Stern-Volmer quenching constants KSV of up to 2071, together with excellent reproducibility. These afterglow microporous films further enable real-time visualization of gas flow and underwater dissolved oxygen monitoring, demonstrating their potential as reliable platforms for high-performance oxygen sensing.