A New Strategy to Enhance Room Temperature Phosphorescence Performance in Physical Doping Polymer System

Abstract Physical doping is a general and effective strategy to fabricate host‐guest room temperature phosphorescence (RTP) polymer materials. However, some aggregates of phosphors will appear due to their limited solubility and phase separation in polymer matrix, resulting in unstable and/or poor RTP property. In this work, a new strategy, the utilization of cyclodextrins with fit cavity size, is proposed to improve the dispersion of phosphors and enhance RTP performance both in covalent and ionic bond system. The resultant high Förster resonance energy transfer (FRET) efficiency ( Φ FRET ) and outstanding RTP performance confirmed that the added cyclodextrins can effectively disperse fluorescence dye (guest) in covalently modified sodium alginate (SA‐R) matrix. Thanks to the introduced “ FRET ruler”, the distance between energy donor and acceptor can be measured, accompanying with the afterglow color of SA‐R films changing from green to red. For SA‐NpC@RhB, the introduction of β‐CD can enhance the Φ FRET up to 57.4%, with corresponding photoluminescence quantum yield ( Φ PL ) as high as 21.15%. The Φ FRET for SA‐NpC/γ‐CD@SR101 is ≈8.5 times enhanced, with the corresponding Φ PL rising from 0.87% to 19.13%. Besides, this strategy is also successfully applied into ionic bond system (SA/R), and the Φ PL for SA/BDA/γ‐CD@RhB can reach 24.05%. Furthermore, these materials with good RTP performance are applied in multiple information encryption, optical information storage, and anti‐counterfeiting.