Equalized Dual Emissions from Copper Complexes via Multichannel Balanced Intersystem Crossing: Toward 100% Quantum...

Area of Science:

• Materials Science
• Photochemistry
• Organic Electronics

Background:

• Luminescent materials are crucial for various technologies, but achieving high efficiency requires balancing different emission pathways.
• Suppressing luminescence quenching and improving efficiency in dual-emission systems, particularly those combining thermally activated delayed fluorescence (TADF) and phosphorescence, remains a significant challenge.

Purpose of the Study:

• To develop a novel luminescent material with balanced dual emission (TADF and phosphorescence) for high-efficiency organic light-emitting diodes (OLEDs).
• To investigate strategies for optimizing singlet-triplet ratios by introducing specific charge transfer states.

Main Methods:

• Synthesis of a rigid triphosphine CuI complex modified with carbazole donors.
• Characterization of photophysical properties, including photo- and electroluminescence quantum efficiencies.
• Exciton kinetics analysis to understand emission mechanisms.

Main Results:

• Achieved a near-equal balance of TADF (53%) and phosphorescence (47%) emissions.
• Reported approximately 100% photo- and electroluminescence quantum efficiencies.
• Demonstrated record-high external quantum efficiencies of ~30% in pure-yellow OLEDs.

Conclusions:

• Modification of a rigid CuI complex with carbazole donors effectively creates high-lying ligand-centered charge transfer states, enabling precise control over singlet-triplet ratios.
• The developed material facilitates efficient dual-emission electroluminescence through energy-level matching with host matrix triplet states.
• This work presents a promising approach for designing high-performance luminescent materials for next-generation OLEDs.