Carbocation-Based Multiresonance Thermally Activated Delayed Fluorescent Emitters with Efficient Narrowband...

Area of Science:

• Materials Science
• Organic Electronics
• Photophysics

Background:

• Multiresonance thermally activated delayed fluorescent (MR-TADF) emitters are crucial for ultrahigh-definition displays.
• Current MR-TADF technology is limited to blue-to-green emissions, with yellow-to-red light being a significant challenge.

Purpose of the Study:

• To develop novel MR-TADF emitters capable of efficient yellow-to-red light emission.
• To overcome the limitations of wide-energy-gap systems in achieving long-wavelength emissions.

Main Methods:

• Introducing positively-charged carbenium ions (C+) into polycyclic skeletons to create strong charge transfer.
• Utilizing steric isopropyl groups and bulky counter ions to suppress intermolecular aggregation.
• Fabricating solution-processed organic light-emitting diodes (OLEDs).

Main Results:

• Achieved a 160 nm emission redshift compared to neutral boron-based emitters by incorporating carbenium ions.
• Obtained high solid-state photoluminescence quantum efficiencies up to 90% due to suppressed aggregation.
• Demonstrated promising external quantum efficiency of 29.4% with a narrow full-width at half-maximum of 0.17 eV in solution-processed OLEDs.

Conclusions:

• The proposed strategy of doping carbenium ions enables the development of narrow-energy-gap MR-TADF emitters.
• This approach facilitates efficient long-wavelength narrowband electroluminescence, crucial for advanced display technologies.
• Ion-based MR-TADF emitters represent a promising pathway for efficient red and yellow light emission in OLEDs.