Balance the Carrier Mobility To Achieve High Performance Exciplex OLED Using a Triazine-Based Acceptor

Area of Science:

• Materials Science
• Organic Electronics
• Photophysics

Background:

• Exciplex-based organic light-emitting diodes (OLEDs) offer efficient light emission.
• Designing suitable electron donor and acceptor molecules is crucial for optimizing exciplex performance.

Purpose of the Study:

• To design and synthesize a novel star-shaped 1,3,5-triazine/cyano hybrid molecule (CN-T2T) as an electron acceptor.
• To investigate the efficiency of exciplex-based OLEDs utilizing the CN-T2T/Tris-PCz system.
• To explore the impact of balanced carrier mobility on OLED performance.

Main Methods:

• Synthesis of the CN-T2T molecule.
• Fabrication of OLED devices with a specific device structure.
• Characterization of photoluminescence quantum yield (ΦPL), energy level offsets (ΔET-S), and external quantum efficiency (EQE).

Main Results:

• The CN-T2T/Tris-PCz exciplex exhibited a high ΦPL of 0.53 and efficient exciton up-conversion.
• A green OLED device achieved a high EQE of 11.9% due to balanced carrier mobility.
• Highly efficient yellow (6.9% EQE) and red (9.7% EQE) OLEDs were demonstrated by doping the exciplex host.

Conclusions:

• Balanced hole and electron mobility in the emitting layer is critical for high-efficiency exciplex-based OLEDs.
• The star-shaped CN-T2T molecule is a promising electron acceptor for efficient OLED emitters.
• The developed exciplex system enables efficient multi-color emission in OLED devices.