Twofold rigidity activates ultralong organic high-temperature phosphorescence.

Area of Science:

• Materials Science
• Photochemistry
• Polymer Chemistry

Background:

• High-temperature phosphorescence is crucial for advanced optical materials.
• Thermal degradation often limits the performance of phosphorescent materials at elevated temperatures.
• Developing robust phosphorescent systems for extreme environments remains a significant challenge.

Purpose of the Study:

• To pioneer a strategy for achieving high-temperature phosphorescence.
• To investigate the role of molecular and matrix rigidity in thermal stability.
• To explore the application of high-temperature phosphorescent materials in fire rescue scenarios.

Main Methods:

• Utilizing planar rigid molecules as guests and rigid polymers as host matrices.
• Doping planar rigid molecules into rigid polymer matrices.
• Characterizing phosphorescence decay times at various temperatures (293 K to 433 K).
• Correlating molecular structure (rotational ability of guest molecule substituents) with phosphorescence performance.

Main Results:

• The doped materials demonstrated sustained phosphorescence at high temperatures: 40 s at 293 K, 20 s at 373 K, 6 s at 413 K, and 1 s at 433 K.
• Increased rotational ability of groups attached to the guest molecules led to decreased high-temperature phosphorescence performance.
• The materials exhibited phosphorescence even in high smoke conditions, indicating potential for visibility.

Conclusions:

• Planar rigid molecules within rigid polymer matrices effectively enable high-temperature phosphorescence by suppressing thermal vibrations.
• Molecular design, specifically minimizing rotational freedom, is key to enhancing thermal stability of phosphorescent materials.
• These high-temperature phosphorescent materials show promise for practical applications, such as identifying rescue personnel in fire environments.