Persistent Room Temperature Phosphorescence from Triarylboranes: A Combined Experimental and Theoretical Study

Area of Science:

• Materials Science
• Organic Chemistry
• Photophysics

Background:

• Achieving efficient room-temperature phosphorescence (RTP) in organic materials is challenging due to slow intersystem crossing (ISC) and non-radiative decay.
• Existing RTP materials often rely on lone pair electrons (e.g., in O or N atoms) to facilitate ISC, which can limit design flexibility.

Purpose of the Study:

• To report the first persistent RTP from triarylboranes, a class of compounds lacking lone pairs.
• To investigate the mechanism behind RTP in these novel materials and explore their potential for new optoelectronic applications.

Main Methods:

• Synthesis of simple triarylboranes.
• Photophysical characterization including lifetime measurements.
• Crystallography and crystal structure analysis.
• Computational studies using Density Functional Theory (DFT) and Multi-Reference Configuration Interaction (MRCI).

Main Results:

• Demonstrated persistent RTP with lifetimes up to 0.5 seconds from triarylboranes.
• Observed RTP primarily in the crystalline state and in doped polymer films, suggesting aggregation-induced emission (AIE) characteristics.
• Crystal structure analysis indicated the importance of intermolecular interactions for efficient RTP.
• Computational and photophysical studies revealed that (σ, B p)→(π, B p) transitions accelerate ISC in these systems.

Conclusions:

• Triarylboranes offer a new molecular framework for designing room-temperature phosphorescent materials without relying on traditional (n, π*) transitions.
• Intermolecular interactions and specific electronic transitions play a crucial role in enabling efficient RTP in these lone-pair-free systems.
• This work opens new avenues for developing advanced organic luminophors for various applications.