Solution-Processable Chiral Boron Complexes for Circularly Polarized Red Thermally Activated Delayed Fluorescent...

Area of Science:

• Materials Science
• Organic Electronics
• Photochemistry

Background:

• Circularly polarized luminescence (CPL) molecules are crucial for chiroptical organic light-emitting diode (OLED) applications.
• Thermally activated delayed fluorescence (TADF) emitters offer high efficiency but integrating CPL properties remains challenging.

Purpose of the Study:

• To develop novel TADF emitters with CPL properties for high-performance chiroptical OLEDs.
• To investigate the structure-property relationships in boron complexes for efficient chiral charge transfer.

Main Methods:

• Synthesis of new boron complexes featuring a chiral donor (cD)-acceptor (A)-donor (D) architecture (cD-A-D).
• Characterization of photophysical properties, including CPL, TADF, and quantum yield.
• Fabrication and testing of solution-processed red circularly polarized OLEDs (CP-OLEDs).

Main Results:

• Achieved high dissymmetry factors (|g_lum|) up to 2.2 × 10^-3 in solution.
• Obtained red-shifted emission around 600 nm with quantum yields over 15% in doped films.
• Demonstrated CP-OLEDs with external quantum efficiencies (EQEs) up to 2.0% and CPL dissymmetry factors of 2.6 × 10^-3.

Conclusions:

• The cD-A-D strategy is effective for designing high-performance CPL TADF emitters based on axially chiral boron complexes.
• Efficient chiral intramolecular charge transfer (ICT) is key to achieving large |g_lum| values and high device performance.
• These findings provide insights into chiral transfer mechanisms for advanced CP-OLED applications.