Dynamic photo-enhanced polyacrylic acid-based room temperature phosphorescence materials with persistent long-wavelength and even near-infrared luminescence via Förster resonance energy transfer

Stimulus-responsive organic room temperature phosphorescence (RTP) materials have attracted widespread attention in chemical sensors, bioimaging and information security. In this work, a dynamic photo-enhanced RTP material is prepared by doping 1,8-naphthalic anhydride (NA) into the polyacrylic acid (PAA) matrix. After 10 min irradiation of 302 nm UV light, the RTP properties of the doping systems PAA-NA are significantly enhanced and the photo-enhanced performances show excellent reversibility. More interestingly, PAA-NA as energy donor and the commercial dye rhodamine B (RhB) as energy acceptor are used to construct the ternary doping systems PAA-NA-RhB, which exhibit color-tunable long afterglow from orange to red through the triplet-to-singlet Förster resonance energy transfer (TS-FRET) process. Significantly, RhB as the intermediate and near infrared (NIR) dye Nile blue (NiB) as energy acceptor are codoped into energy donor PAA-NA matrices to facilely prepare the quaternary doping systems PAA-NA-RhB-NiB, and persistent NIR luminescence is realized successfully via the stepwise FRET process after 10 min irradiation of 302 nm UV light. The great application potential of the prepared photo-enhanced PAA-based RTP materials in high-level information encryption has been confirmed due to their excellent RTP performance. This study broadens the range of photo-enhanced polymer-based RTP materials and extends the persistent luminescence of PAA-based RTP materials to the long-wavelength and NIR regions.