Linearly Arranged Multi-π-Stacked Structure for Efficient Through-Space Charge-Transfer Emitters

Area of Science:

• Optoelectronics
• Materials Science
• Organic Chemistry

Background:

• Noncovalent interactions are key for designing optoelectronic molecules.
• Developing efficient molecular architectures is crucial for advanced materials.

Purpose of the Study:

• To construct novel donor-acceptor-donor (D|A|D) molecules with multi π-stacked conjugated units.
• To explore the potential of indeno[2,1-b]fluorene as a trident bridge for molecular construction.
• To develop high-performance thermally activated delayed fluorescence (TADF) materials.

Main Methods:

• Synthesized two novel D|A|D molecules (2DMB and 2DMFB) using an improved double C-H activation approach.
• Utilized indeno[2,1-b]fluorene as a rigid scaffold to achieve multi π-stacking.
• Investigated intramolecular stacking and through-space charge transfer.

Main Results:

• Achieved closely packed intramolecular stacking due to the rigid D|A|D structure.
• Observed efficient through-space charge transfer, leading to high radiative transition rates.
• Obtained high photoluminescence quantum yields and superior device efficiencies in organic light-emitting diodes (OLEDs).

Conclusions:

• The developed molecular design enables efficient optoelectronic properties through controlled noncovalent interactions.
• The novel D|A|D molecules are promising candidates for high-performance TADF materials.
• OLEDs incorporating these molecules demonstrated maximum external quantum efficiencies of 28.6% and 16.2%.