Deep-Blue Oxadiazole-Containing Thermally Activated Delayed Fluorescence Emitters for Organic Light-Emitting Diodes

Area of Science:

• Materials Science
• Organic Electronics
• Photophysics

Background:

• Thermally Activated Delayed Fluorescence (TADF) materials are crucial for efficient organic light-emitting diodes (OLEDs).
• Developing deep-blue and sky-blue emitters with high color purity and quantum yields remains a significant challenge in OLED technology.
• Oxadiazole moieties are explored as electron-accepting units to tune the electronic properties of TADF emitters.

Purpose of the Study:

• To synthesize and characterize novel oxadiazole-based TADF emitters for deep-blue to sky-blue emission.
• To investigate the effect of oxadiazole moieties on the emission color and photophysical properties.
• To evaluate the performance of these emitters in OLED devices.

Main Methods:

• Synthesis and characterization of four novel oxadiazole-based TADF emitters.
• Photoluminescence spectroscopy to determine emission wavelengths and photoluminescence quantum yields (PLQYs).
• Fabrication and testing of OLED devices incorporating the synthesized emitters doped in mCP and PPT hosts.

Main Results:

• The synthesized oxadiazole emitters exhibited bluer emission compared to the reference 2CzPN due to weaker acceptor strength.
• Emissions ranged from 435 to 474 nm with PLQYs between 14-55%.
• OLED devices achieved maximum external quantum efficiencies of 11.2% (sky-blue) and 6.6% (deep-blue), with small singlet-triplet energy gaps (0.25–0.46 eV) enabling efficient delayed fluorescence.

Conclusions:

• Novel oxadiazole-based compounds are promising TADF emitters for achieving efficient deep-blue and sky-blue OLEDs.
• The weaker acceptor strength of oxadiazole moieties effectively tunes emission towards the blue region.
• These emitters demonstrate potential for next-generation display and lighting applications requiring high-performance blue light.