Enabling Thermally Stimulated Delayed Phosphorescence in Cu(I) Cyclic Trinuclear Complexes with Near-Unity Quantum...

Area of Science:

• Materials Science
• Photochemistry
• Inorganic Chemistry

Background:

• Thermally stimulated delayed phosphorescence (TSDP) is a promising emission phenomenon recently observed in gold complexes.
• Developing efficient TSDP emitters using earth-abundant metals is crucial for practical applications.
• Existing TSDP emitters often rely on precious metals, limiting their widespread use.

Purpose of the Study:

• To explore halogen bonding as a strategy for achieving TSDP in copper(I) complexes.
• To investigate the photophysical properties and quantum yields (QYs) of bromo-substituted copper(I) cyclic trinuclear complexes (CTCs).
• To understand the mechanism by which halogen bonding influences TSDP behavior and emission efficiency.

Main Methods:

• Synthesis of bromo-substituted copper(I) cyclic trinuclear complexes (CTCs).
• Photophysical characterization, including emission intensity and quantum yield (QY) measurements.
• Theoretical calculations to analyze excited-state dynamics and the role of halogen bonding.

Main Results:

• Successful induction of TSDP emission in bromo-substituted Cu(I) CTCs via halogen bonding.
• Halogen bonding was found to suppress excited-state distortions and reduce the energy gap between T1 and T2 triplet states.
• Significantly suppressed nonradiative decay and high QYs, with one complex achieving near-unity QY, were observed.

Conclusions:

• Halogen bonding is an effective strategy to achieve high-efficiency TSDP in earth-abundant Cu(I) complexes.
• This approach enables efficient spin-allowed reverse internal conversion, leading to enhanced TSDP.
• The findings extend TSDP behavior to Cu(I) complexes, offering a promising alternative to gold-based emitters.