Core-Substituted Pyromellitic Diimides: A Versatile Molecular Scaffold for Tunable Triplet Emission

Area of Science:

• Materials Science
• Organic Electronics
• Photochemistry

Background:

• Arylene diimides are key n-type organic semiconductors with tunable fluorescence for optoelectronics.
• Triplet-state emission in these materials is underexplored, despite its importance for ambient-organic triplet harvesting.
• Advancing organic triplet materials requires tunable triplet states for applications in lighting and photocatalysis.

Purpose of the Study:

• To demonstrate tunable triplet emission in pyromellitic diimides, the smallest arylene diimide.
• To synthesize and characterize a series of core-substituted pyromellitic diimides (cPmDIs).
• To explore the potential of cPmDIs in ambient-organic phosphorescence and triplet harvesting.

Main Methods:

• Synthesis of diverse core-substituted pyromellitic diimides (cPmDIs).
• Photophysical and electrochemical characterization of the synthesized cPmDIs.
• Theoretical calculations to support experimental findings.

Main Results:

• Core substitution of pyromellitic diimides induced a wide range of fluorescence colors.
• Achieved tunable phosphorescence spanning the visible spectrum based on core substituents.
• Demonstrated ambient-orange phosphorescence in a thiophenyl-cPmDI derivative in crystalline and film states.

Conclusions:

• Core-substituted pyromellitic diimides offer tunable triplet emission, expanding their utility in optoelectronics.
• This work provides a significant step towards predictive design of ambient-organic phosphors.
• The findings pave the way for advanced triplet harvesting materials for diverse applications.