Enabling Visible-Light-Charged Near-Infrared Persistent Luminescence in Organics by Intermolecular Charge Transfer

Area of Science:

• Organic electronics
• Photophysics
• Materials science

Background:

• Visible light is an accessible excitation source, but challenging for generating persistent luminescence (PersL).
• Organic materials offer tunable properties but require efficient methods for light-induced persistent emission.

Purpose of the Study:

• To enable efficient near-infrared (NIR) persistent luminescence (PersL) in organic materials using visible light.
• To explore the mechanism of intermolecular charge transfer (xCT) for light storage in organic systems.

Main Methods:

• Application of intermolecular charge transfer (xCT) in host-guest molecular systems.
• Utilizing charge-transfer aggregates (CTAs) and constructed trap states for electron trapping and detrapping.
• Modulating xCT absorption by altering electron-donating abilities of acenaphtho[1,2-b]pyrazine-8,9-dicarbonitrile-based CTAs.

Main Results:

• Achieved efficient charging of NIR PersL in organics using visible light (425-700 nm).
• Demonstrated long-lasting emission up to 4.6 hours at room temperature via thermal stimulation of trapped electrons.
• Tuned organic PersL emission from 681 to 722 nm by modifying CTAs.

Conclusions:

• Intermolecular charge transfer (xCT) is a viable mechanism for visible-light-driven NIR PersL in organic materials.
• The findings advance the understanding of luminescence mechanisms in organic semiconductors.
• The developed materials show promise for optoelectronics, energy storage, and medical diagnostics.