Highly Efficient Near-Infrared Delayed Fluorescence Organic Light Emitting Diodes Using a Phenanthrene-Based...

Area of Science:

• Materials Science
• Organic Electronics
• Photophysics

Background:

• High-efficiency organic light-emitting diodes (OLEDs) utilizing thermally activated delayed fluorescence (TADF) emitters are crucial for advanced display and lighting technologies.
• Development of efficient TADF materials for red, deep-red, and near-infrared (NIR) regions remains challenging due to complex molecular design requirements.

Purpose of the Study:

• To report the first near-infrared (NIR) TADF molecule for efficient OLED applications.
• To investigate the performance of the novel NIR TADF molecule in both nondoped and doped OLED devices.

Main Methods:

• Synthesis and characterization of a novel NIR TADF molecule, TPA-DCPP (triphenylamine-2,3-dicyanopyrazinophenanthrene).
• Fabrication and testing of nondoped and doped OLED devices using the synthesized TPA-DCPP molecule.
• Measurement of device performance, including external quantum efficiency (EQE) and Commission International de L'Éclairage (CIE) coordinates.

Main Results:

• The synthesized TPA-DCPP molecule exhibits a small singlet-triplet energy splitting (ΔEST) of 0.13 eV, characteristic of TADF materials.
• Nondoped OLED devices demonstrated a maximum external quantum efficiency (EQE) of 2.1% with CIE coordinates of (0.70, 0.29).
• Doped OLED devices achieved an exceptionally high EQE of nearly 10% at λ=668 nm, rivaling efficient deep-red/NIR phosphorescent OLEDs.

Conclusions:

• TPA-DCPP represents the first successful NIR TADF molecule, overcoming previous limitations in red-to-NIR emitter development.
• The high EQE achieved in doped devices signifies a significant advancement for efficient deep-red and NIR OLED technology.
• This work paves the way for developing novel NIR TADF materials for next-generation optoelectronic applications.