π-Stacked Donor-Acceptor Dendrimers for Highly Efficient White Electroluminescence

Area of Science:

• Materials Science
• Organic Electronics
• Photophysics

Background:

• Developing efficient and stable organic light-emitting diodes (OLEDs) is crucial for next-generation displays and lighting.
• Thermally activated delayed fluorescence (TADF) materials offer a pathway to high-efficiency OLEDs by harvesting both singlet and triplet excitons.
• Achieving pure white emission and high performance through solution processing remains a significant challenge.

Purpose of the Study:

• To design and synthesize novel π-stacked dendrimers with cofacially aligned donor and acceptor units.
• To investigate the relationship between molecular structure, charge transfer, and emission properties.
• To fabricate and evaluate solution-processed white OLEDs utilizing these dendrimers.

Main Methods:

• Synthesis of hexaphenylbenzene-cored dendrimers featuring teracridan donors and triazine acceptors in an orthogonal configuration.
• Characterization of photophysical properties, including absorption, emission spectra, and quantum yields.
• Fabrication of two-color white OLED devices using solution processing techniques.

Main Results:

• The dendrimers exhibit through-space charge transfer emission with a thermally activated delayed fluorescence (TADF) effect.
• Emission color was tunable from blue to yellow/red by modifying substituents on the triazine acceptors.
• Solution-processed white OLEDs achieved a maximum external quantum efficiency of 20.6% and a maximum power efficiency of 58.9 lm/W.

Conclusions:

• The developed π-stacked dendrimers are promising candidates for high-efficiency, solution-processed TADF white OLEDs.
• The molecular design strategy effectively controls emission color and enhances device performance.
• This work represents a significant advancement in achieving state-of-the-art efficiencies for all-TADF white OLEDs via solution processing.