One-Step Phosphine-Oxide Post-Modification of Multi-Resonance Emitters for Efficient, Narrowband, Quenching-Resistant...

Area of Science:

• Materials Science
• Organic Electronics
• Photophysics

Background:

• Multiple-resonance thermally activated delayed fluorescence (MR-TADF) materials are vital for high-efficiency, wide color-gamut organic light-emitting diodes (OLEDs).
• Existing MR-TADF emitters often face challenges with complex synthesis and limited structural diversity.
• Aggregation-caused quenching (ACQ) and spectral broadening are significant issues in OLED performance.

Purpose of the Study:

• To develop a facile and versatile strategy for synthesizing novel MR-TADF emitters.
• To investigate the impact of a phosphine-oxide (P═O) post-modification on the photophysical properties and device performance.
• To demonstrate the potential of these new emitters for high-performance OLED applications.

Main Methods:

• A one-step, metal-free phosphine-oxide (P═O) post-modification strategy was employed.
• New B/N/P═O fused MR-TADF emitters, PO-BCzBN and PO-tFBN, were synthesized and characterized.
• Photophysical properties (emission spectra, quantum yields, decay rates) and device performance in sensitizer-free OLEDs were evaluated.

Main Results:

• The P═O modification introduced a covalent lock, enhancing π-conjugation rigidity and suppressing ACQ via steric hindrance.
• PO-BCzBN and PO-tFBN exhibited narrowband emission (21-23 nm FWHM) with near-unity photoluminescence quantum yields (98-99%).
• Sensitizer-free OLEDs achieved high external quantum efficiencies (21.6%-35.8%) with minimal spectral broadening and ACQ.

Conclusions:

• The developed P═O post-modification strategy is effective for creating high-performance MR-TADF emitters.
• The new emitters demonstrate excellent photophysical properties and device stability, suitable for wide color-gamut OLEDs.
• This approach offers a promising route for designing structurally diverse and efficient TADF materials.