High-Performance Ultraviolet Organic Light-Emitting Diode Enabled by High-Lying Reverse Intersystem Crossing

Area of Science:

• Materials Science
• Organic Electronics
• Photophysics

Background:

• Developing efficient ultraviolet (UV) organic emitters is crucial for next-generation organic light-emitting diodes (OLEDs).
• Existing UV emitters often struggle with balancing color purity and exciton utilization.
• Novel excited-state engineering is needed to overcome these limitations.

Purpose of the Study:

• To report a high-quality UV emitter with a hybridized local and charge-transfer (HLCT) excited state.
• To investigate its application in UV OLEDs.
• To demonstrate improved performance metrics for UV electroluminescence.

Main Methods:

• Synthesis and characterization of a novel UV emitter, 2BuCz-CNCz.
• Fabrication of OLED devices utilizing the synthesized emitter.
• Electroluminescence (EL) spectroscopy and efficiency measurements.

Main Results:

• The UV emitter, 2BuCz-CNCz, exhibits a hybridized local and charge-transfer (HLCT) excited state.
• It demonstrates a narrowband UV electroluminescent (EL) emission at 396 nm with high color purity (CIE_{x, y} =0.161, 0.031).
• The device achieved a record-high maximum external quantum efficiency (EQE) of 10.79% with minimal efficiency roll-off.

Conclusions:

• The developed UV emitter effectively balances color purity and exciton utilization through its unique excited state properties.
• The state-of-the-art device performance highlights the potential of HLCT emitters for high-performance UV OLEDs.
• This work provides a promising pathway for the advancement of UV organic light-emitting diode technology.