Polymer-based organic room-temperature phosphorescent (RTP) materials have recently attracted significant attention. In most of the previous works, ‘chemical approaches’ have been applied to improve the performance of RTP materials, such as designing certain phosphors or selecting specific polymeric matrixes. However, enhancing triplet emission through facile ‘physical approaches’ is rarely reported. In this study, we report enhanced RTP emissions of phosphor-doped polymers by thermal annealing. By doping a difluoroboron β-diketonate derivative into poly(diacetone acrylamide) (PDAAM), green RTP emissions can be obtained. After thermal annealing at 125 °C for 5 min, the afterglow duration of RTP increased from 2.6 s to 5.3 s, and also the brightness of RTP emission exhibited a 3-fold increase. Such post-treatment is applicable for various polymeric matrixes. The mechanism underlying thermal-annealing enhanced RTP was investigated. Moreover, it demonstrated that controlled RTP by thermal annealing can be used in information encryption and anti-counterfeiting. This work provides new insight into the development of organic RTP materials with tunable emissions.
Additional GPC, NMR, and DSC results, PL spectra, phosphorescence decay profiles.