Excellent Persistent Near-Infrared Room Temperature Phosphorescence from Highly Efficient Host-Guest Systems

Area of Science:

• Materials Science
• Biomedical Engineering
• Photochemistry

Background:

• Organic near-infrared (NIR) room temperature phosphorescence (RTP) is crucial for bioimaging and biosensing due to deep tissue penetration and high signal-to-background ratio (SBR).
• Achieving persistent NIR RTP is challenging due to nonradiative transitions, as predicted by the energy-gap law.

Purpose of the Study:

• To develop a universal system for persistent NIR RTP by combining visible (host) and NIR phosphorescence (guest) materials.
• To enhance phosphorescence emission and suppress nonradiative decay pathways.

Main Methods:

• Constructed a host-guest system using crystalline host materials with a rigid environment to suppress nonradiative transitions.
• Utilized phosphorescence resonance energy transfer (π≈100%) between host and guest materials to promote emission.
• Modulated the aggregated structures of the host-guest systems to optimize phosphorescence properties.

Main Results:

• Successfully created a system exhibiting persistent NIR RTP with significantly suppressed nonradiative transitions.
• Achieved a tenfold enhancement in RTP lifetimes compared to individual guest luminogens.
• Demonstrated efficient phosphorescence resonance energy transfer between host and guest components.

Conclusions:

• The developed host-guest system provides a universal and convenient method to prolong NIR luminogen phosphorescence lifetimes.
• This approach significantly enhances the potential for applications in afterglow imaging, offering deeper penetration and higher SBRs.