Highly Efficient Near-Infrared Electrofluorescence from a Thermally Activated Delayed Fluorescence Molecule.

Area of Science:

• Materials Science
• Organic Electronics
• Photophysics

Background:

• Near-infrared organic light-emitting diodes (NIR-OLEDs) offer unique advantages like flexibility and low-cost fabrication for sensing applications.
• A significant limitation for NIR-OLEDs is their low external electroluminescence (EL) quantum efficiency (EQE).

Purpose of the Study:

• To develop a highly efficient NIR emitter utilizing thermally activated delayed fluorescence (TADF).
• To apply this TADF emitter in NIR-OLEDs to overcome the EQE limitations.

Main Methods:

• Synthesis and characterization of a novel NIR-TADF emitter, TPA-PZTCN.
• Fabrication and testing of NIR-OLED devices incorporating the TPA-PZTCN emitter.
• Investigation of TADF-sensitized NIR-OLEDs using a deeper NIR fluorophore.

Main Results:

• The TPA-PZTCN emitter achieved a photoluminescence quantum yield exceeding 40% at 729 nm.
• NIR-OLEDs demonstrated a 734 nm emission with an unprecedented 13.4% EQE for rare-metal-free devices.
• TADF-sensitized NIR-OLEDs reached approximately 900 nm emission with over 1% EQE and >600 hours operational durability.

Conclusions:

• The developed NIR-TADF emitter significantly enhances EQE in NIR-OLEDs.
• This technology presents a viable path for efficient and durable rare-metal-free NIR-OLEDs for sensing.
• The TADF sensitization approach extends NIR-OLEDs to longer wavelengths with promising performance.