The huge kp of 1 enabled efficient RTP in air in the amorphous state using various conventional polymers as matrices (Figure -3f and Figures S10-S12 and Table ). A p of 54% was achieved at room temperature in air for a poly(methyl methacrylate) (PMMA) film doped with 5-wt% 1a (Figure ). This was among the highest reported for polymer-based RTP systems doped with metal-free organic dyes. In these systems, insufficient kp requires a tailor-made approach that involves specific interactions between the polymers and dopants. Hydrogen bonding in poly(vinyl alcohol) was reported to be effective and widely used, 10c-e but those interactions or polymers are difficult to use in water. A 1b-doped PMMA film was resistant to water, where it exhibited RTP. Moreover, phosphorescent films with p values of 48-18% were obtained by doping 1b into six different conventional polymers (Figure ,f and Figure -S12 and Table ). The emission maxima and FWHMs were almost unchanged, with high color purities independent of the polymers. Thus, RTP properties of the films were derived from inherent characteristics of 1.