Continuous Condensed Triplet Accumulation for Irradiance-Induced Anticounterfeit Afterglow

Area of Science:

• Materials Science
• Photophysics
• Organic Chemistry

Background:

• Afterglow emission offers potential for bioimaging and security but is limited by low brightness.
• Autofluorescence can interfere with traditional imaging techniques, necessitating alternative methods.

Purpose of the Study:

• To develop a brighter afterglow room-temperature phosphorescence material.
• To overcome the limitations of low brightness in afterglow applications.
• To enable new applications in bioimaging and security devices.

Main Methods:

• Incorporation of (S)-(-)-2,2'-Bis(diphenylphosphino)-1,1'-binaphthyl ((S)-BINAP) into a crystalline host lattice.
• Utilizing strong excitation to promote continuous formation of condensed triplet excitons.
• Characterizing the photophysical properties, including triplet exciton concentration and emission brightness.

Main Results:

• Achieved bright green afterglow room-temperature phosphorescence from (S)-BINAP.
• Demonstrated suppressed deactivation via Förster resonance energy transfer due to (S)-BINAP's small triplet-triplet absorption cross-section.
• Reached a high steady-state concentration of triplet excitons (2.3 × 10^-2 M), resulting in significantly enhanced afterglow brightness.

Conclusions:

• The developed material exhibits significantly brighter afterglow, enabling detection of particles near the diffraction limit in aqueous solutions.
• The brighter afterglow facilitates irradiance-dependent anticounterfeiting applications.
• This work paves the way for advanced bioimaging and security technologies utilizing enhanced afterglow properties.