Building a Highly Stable Red/Near Infrared Afterglow Library with Highly Branched Structures.

Area of Science:

• Organic electronics
• Materials science
• Photophysics

Background:

• Achieving high-temperature organic phosphorescence is difficult due to nonradiative transitions in low-energy gap triplet states.
• Organic red/near-infrared (NIR) emitters often suffer from poor thermal stability, limiting their applications.

Purpose of the Study:

• To develop bright and thermally stable organic red/NIR afterglow materials.
• To overcome the challenge of nonradiative decay in organic phosphors at elevated temperatures.

Main Methods:

• Utilized highly efficient phosphorescence resonance energy transfer (PRET) from branched phosphorescent luminogens (donors) to red/NIR dyes (acceptors).
• Optimized aggregated structures of branched luminogens to create internal cavities for dye loading and spatial confinement.
• Investigated 16 host-guest systems with varied branched luminogen topologies and red/NIR dye sizes.

Main Results:

• Achieved bright and persistent red/NIR afterglow with high-temperature resistance up to 413 K.
• Demonstrated that internal cavities in branched structures suppress nonradiative transitions at high temperatures.
• Confirmed the universality of the PRET strategy across various host-guest systems.

Conclusions:

• Developed an efficient strategy for creating highly stable red/NIR afterglow materials.
• Branched luminogen structures and PRET are key to suppressing nonradiative decay and enhancing thermal stability.
• The findings offer a promising approach for high-performance organic light-emitting applications.