Acceptor-Bridged Engineering Enables Highly Efficient Solution-Processed Pure-Green MR-TADF OLEDs With External...

Area of Science:

• Materials Science
• Organic Electronics
• Photophysics

Background:

• Next-generation displays require efficient, narrowband emitters with high color purity.
• Multi-resonance thermally activated delayed fluorescence (MR-TADF) emitters excel in vacuum-deposited OLEDs but face challenges in solution processing due to rigidity.
• Solution-processing offers advantages for large-area, low-cost display manufacturing.

Purpose of the Study:

• To develop novel, solution-processable pure-green MR-TADF emitters for ultrahigh-definition displays.
• To overcome solubility and film morphology limitations of traditional MR-TADF materials.
• To achieve high efficiency and color purity in solution-processed OLEDs.

Main Methods:

• Molecular design using an acceptor-bridged engineering strategy, integrating MR cores with electron-withdrawing pyrimidine bridges.
• Synthesis and characterization of two novel MR-TADF emitters: DBN-Pym and DBN-PhPym.
• Fabrication and testing of solution-processed OLED devices.

Main Results:

• DBN-Pym and DBN-PhPym exhibit narrowband green emission (FWHM: 24-30 nm) with high photoluminescence quantum yields (PLQYs) of 86% and 99%.
• Solution-processed OLEDs show peak emissions at 526/521 nm with high CIE y coordinates (>0.69).
• DBN-PhPym achieved a record external quantum efficiency (EQE) of 29.0% for solution-processed MR-TADF devices, with a narrow FWHM of 34 nm.

Conclusions:

• The acceptor-bridged engineering strategy effectively enhances solubility and modulates electronic properties for efficient narrowband emission.
• The developed emitters represent a significant advancement for solution-processable MR-TADF devices.
• This work paves the way for cost-effective, high-performance solution-processed ultrahigh-definition displays.