Revisiting organic charge-transfer cocrystals for wide-range tunable, ambient phosphorescence

Area of Science:

• Materials Science
• Organic Chemistry
• Photophysics

Background:

• Organic materials with tunable phosphorescence are crucial for advanced applications.
• Cocrystallization via non-covalent interactions offers a promising route to novel phosphorescent materials.
• Existing methods often lack precise control over emission properties.

Purpose of the Study:

• To develop a tunable phosphorescence system using donor-acceptor cocrystals.
• To investigate the role of halogen bonding in stabilizing charge-transfer phosphorescence.
• To establish the molecular origin of tunable emission in these systems.

Main Methods:

• Cocrystallization of pyromellitic diimide with various electron-donating molecules.
• Spectroscopic studies (UV-Vis absorption, emission, lifetime) to characterize photophysical properties.
• Single-crystal X-ray diffraction to elucidate molecular packing and intermolecular interactions.

Main Results:

• Achieved tunable phosphorescence emission from green to reddish-orange by varying donor strength.
• Demonstrated ambient, charge-transfer phosphorescence (³CT) in intermolecular donor-acceptor systems.
• Observed noteworthy quantum yields across the emission spectrum.

Conclusions:

• The study presents a novel strategy for designing efficient organic phosphors with tunable emission.
• Halogen bonding plays a key role in stabilizing the charge-transfer triplet states.
• This work opens new avenues for developing advanced organic light-emitting materials.