Pyrimidine-based twisted donor-acceptor delayed fluorescence molecules: a new universal platform for highly efficient...

Area of Science:

• Materials Science
• Organic Electronics
• Photophysics

Background:

• High-efficiency deep-blue emitters are crucial for organic light-emitting diodes (OLEDs) used in displays and lighting.
• Thermally activated delayed fluorescence (TADF) molecules offer a pathway to harvest both singlet and triplet excitons for improved electron-to-photon conversion efficiency.
• Existing deep-blue emitters often face challenges with stability and efficiency.

Purpose of the Study:

• To develop a new platform for high-efficiency deep-blue TADF emitters.
• To investigate the potential of acridan-pyrimidine donor-acceptor (D-A) systems for TADF applications.
• To demonstrate the performance of these emitters in OLED devices.

Main Methods:

• Design and synthesis of pre-twisted acridan-pyrimidine donor-acceptor molecules.
• Characterization of photophysical properties, including singlet-triplet energy splitting and photoluminescence quantum yields.
• Fabrication and testing of OLED devices incorporating the synthesized TADF emitters.

Main Results:

• The designed acridan-pyrimidine D-A molecules exhibited small singlet-triplet energy splitting and high photoluminescence quantum yields.
• OLEDs fabricated with these TADF emitters demonstrated bright blue electroluminescence.
• Achieved external quantum efficiencies up to 20.4%, current efficiencies of 41.7 cd A^-1, and power efficiencies of 37.2 lm W^-1.

Conclusions:

• The acridan-pyrimidine D-A motif serves as a versatile platform for developing efficient deep-blue TADF emitters.
• This design strategy shows significant promise for advancing the performance of TADF-OLEDs.
• The developed emitters are suitable for high-performance full-color displays and white lighting applications.