Coordinatively improving polymeric phosphorescence lifetime and quantum yield via triplet exciton modulation

Area of Science:

• Materials Science
• Polymer Chemistry
• Photophysics

Background:

• Advancing polymeric materials with excellent room temperature phosphorescence (RTP) is challenging due to the trade-off between long phosphorescence lifetime (τP) and high phosphorescence quantum yield (ΦP).
• Optimizing triplet exciton generation and quenching is crucial for improving RTP performance.

Purpose of the Study:

• To develop a synergistic strategy (Iodine-Stretch-Boric Acid - ISB) to simultaneously enhance both phosphorescence lifetime (τP) and absolute phosphorescence quantum yield (ΦP) in polymeric materials.
• To investigate the mechanism by which the ISB strategy modulates triplet exciton dynamics.

Main Methods:

• The ISB strategy was applied to binaphthyl derivative-incorporated polyvinyl alcohol (BINs@PVA) films.
• The strategy utilizes external heavy atom effects to enhance spin-orbit coupling and induces a dense cross-linked network.
• Modulation of non-radiative rate constant (k^P_nr) and intersystem crossing rate constant (k_ISC) was analyzed.

Main Results:

• Post-ISB treatment of DFBN@PVA films resulted in a significant increase in RTP performance.
• Achieved a long τP of 1239.8 ms (28.4-fold increase) and a high absolute ΦP of 33.8% (24.1-fold increase).
• The ISB strategy enhanced film durability, maintaining bright RTP emission after prolonged exposure to water, acidic, alkaline, and hot water conditions.

Conclusions:

• The ISB strategy effectively overcomes the limitations in achieving high τP and ΦP simultaneously in polymeric phosphors.
• The developed materials exhibit excellent stability and potential for applications in multicolor secure information, antibacterial coatings, and water-resistant RTP devices.