Sulfur-Embedded Pure Green Multiple Resonance TADF Emitters: Optimizing Photophysical and Electroluminescent...

Area of Science:

• Organic Electronics
• Materials Science
• Photophysics

Background:

• Thermally activated delayed fluorescence (TADF) is crucial for efficient organic light-emitting diodes (OLEDs).
• Achieving pure green emission with high efficiency and stability remains a challenge in OLED technology.

Purpose of the Study:

• To design and synthesize novel pure green multiple resonance thermally activated delayed fluorescence (MR-TADF) emitters.
• To investigate the structure-property relationships influencing emission characteristics and efficiency roll-off.

Main Methods:

• Synthesis of benzothienocarbazole-based MR-TADF emitters (Th-Cz-BN3 and Th-Cz-BN6).
• Device fabrication and characterization of OLEDs incorporating the synthesized emitters.
• Analysis of photophysical properties including energy splitting and spin-orbit coupling.

Main Results:

• Developed two sulfur-embedded pure green MR-TADF emitters, Th-Cz-BN3 and Th-Cz-BN6.
• Achieved pure green emission (CIE y > 0.7) with external quantum efficiencies exceeding 34.0%.
• Demonstrated significantly suppressed efficiency roll-off in non-sensitized devices.

Conclusions:

• Sulfur incorporation in benzothienocarbazole units enables efficient pure green MR-TADF emission.
• Molecular design strategies can mitigate efficiency roll-off in high-performance OLEDs.
• These findings contribute to the development of advanced materials for next-generation displays.