Orange-Red Thermally Activated Delayed Fluorescence Conjugated Polymers toward Highly Efficient Solution-Processable...

Area of Science:

• Materials Science
• Organic Electronics
• Photophysics

Background:

• Developing solution-processable white organic light-emitting diodes (OLEDs) using thermally activated delayed fluorescence (TADF) polymers is challenging due to emitter color matching issues.
• Existing TADF polymers often struggle to achieve efficient and stable white light emission, limiting their practical applications.

Purpose of the Study:

• To synthesize novel orange-red TADF polymers for efficient solution-processable white OLEDs.
• To investigate the photophysical properties and device performance of these new TADF polymers.
• To address the challenge of achieving a suitable spectral match between blue and orange-red emitters in TADF-based white OLEDs.

Main Methods:

• Synthesized a series of orange-red TADF polymers (PCzTQCx) by incorporating quinoxaline-6,7-dicarbonitrile (QC) as an acceptor and triphenylamine (T) with long alkyl chains as a donor into the polymer backbone.
• Fabricated non-doped and doped single-emissive layer OLED devices using the synthesized polymers.
• Characterized the photoluminescence spectra, external quantum efficiency (EQE), luminance, and color rendering index (CRI) of the fabricated devices.

Main Results:

• The synthesized PCzTQCx polymers exhibit orange-red emissions with peaks ranging from 571 to 621 nm.
• Non-doped OLED devices achieved pure white emission with a high CRI of 80.
• Doped devices demonstrated warm white emission with a maximum EQE of 15.7%, luminance of 4325 cd m⁻², and CRI of 64, by combining with a blue TADF small-molecule emitter.

Conclusions:

• The developed orange-red TADF polymers are promising for creating high-performance, solution-processable white OLEDs.
• The strategy of embedding QC and T units effectively tunes the emission color and improves device efficiency.
• These findings offer a viable pathway to overcome the limitations in current TADF polymer-based white OLED technology.