Coordination Induction-Enhanced Thermally Activated Delayed Fluorescence for Silver(I) Complexes

Area of Science:

• Materials Science
• Organic Chemistry
• Photophysics

Background:

• Donor-acceptor (D-A) type nitrogen-containing compounds are crucial for thermally activated delayed fluorescence (TADF) emitters.
• High-efficiency emission is a primary challenge for D-A-type TADF materials, especially in doped organic light-emitting diodes (OLEDs).
• Coordination-induced delayed fluorescence offers a method to tune energy levels and achieve efficient intramolecular ligand charge transfer (ILCT) emission.

Purpose of the Study:

• To modulate the energy-level structure of yellow-emitting D-A-type hybrid fluorescence-TADF molecules through Ag(I) coordination.
• To investigate the impact of metal coordination on TADF properties, including spin-orbit coupling and radiative lifetimes.
• To develop a robust strategy for designing novel TADF-active metal complexes.

Main Methods:

• Synthesis of two Ag(I) complexes with D-A-type hybrid fluorescence-TADF molecules.
• Characterization of the coordination environment and its effect on energy levels and ΔEST.
• Evaluation of photoluminescence quantum yield (PLQY) and excited-state lifetimes (τF, τTADF) in PMMA films.

Main Results:

• Two Ag(I) complexes exhibiting ILCT-type emission were successfully obtained.
• Coordination-tuned energy levels and reduced ΔEST led to enhanced TADF performance.
• Complex 1 achieved a PLQY of 98% (τF = 134 ns; τTADF = 2.7 μs), and Complex 2 showed a PLQY of 46% (τF = 70.7 ns; τTADF = 2.0 μs).

Conclusions:

• Ag(I) coordination is an effective strategy for designing high-efficiency TADF materials.
• The developed metal complexes demonstrate significant potential for applications in OLEDs.
• This work provides a robust framework for the rational design of novel TADF-active metal complexes.