Exciplex-Based Electroluminescence: Over 21% External Quantum Efficiency and Approaching 100 lm/W Power Efficiency

Area of Science:

• Organic Electronics
• Materials Science
• Photophysics

Background:

• Exciplex emitters are crucial for high-efficiency organic light-emitting devices (OLEDs).
• Developing novel electron acceptors with high triplet energy and good charge transport is key to improving OLED performance.

Purpose of the Study:

• To synthesize and characterize a new benzimidazole-triazine-based electron acceptor, PIM-TRZ.
• To fabricate and evaluate highly efficient exciplex emitters utilizing PIM-TRZ for OLED applications.

Main Methods:

• Synthesis of PIM-TRZ, a benzimidazole-triazine derivative.
• Fabrication of organic light-emitting devices using TAPC:PIM-TRZ blend as the emitting layer.
• Characterization of photoluminescence quantum yield (PLQY), turn-on voltage, and various efficiency metrics (CE, PE, EQE).

Main Results:

• The TAPC:PIM-TRZ film achieved a high PLQY of 93.4%.
• The OLED device demonstrated a low turn-on voltage (2.3 V) and record efficiencies: 71.2 cd A^-1 (CE), 97.3 lm W^-1 (PE), and 21.7% (EQE).
• A green emitting device using PIM-TRZ as a cohost achieved high efficiencies (68.3 cd A^-1 CE, 86.6 lm W^-1 PE, 20.2% EQE).

Conclusions:

• PIM-TRZ is a promising electron acceptor for high-performance exciplex OLEDs.
• The developed devices exhibit superior efficiency compared to previously reported exciplex-based OLEDs.
• This work paves the way for next-generation OLEDs with enhanced efficiency and performance.