Phosphorescence quantum yield enhanced by intermolecular hydrogen bonds in Cu4I4 clusters in the solid state

Area of Science:

• Inorganic Chemistry
• Materials Science
• Solid-State Physics

Background:

• Organo-copper(i) halide complexes featuring a Cu4I4 cubane core are of interest for their unique structural and photophysical properties.
• Understanding the relationship between crystal structure, molecular packing, and luminescence is crucial for developing new materials.

Purpose of the Study:

• To synthesize and characterize organo-copper(i) halide complexes with a Cu4I4 cubane core and cyclic amine ligands.
• To investigate the solid-state photophysical properties of these complexes and correlate them with their crystal structures.
• To evaluate the potential of these complexes for applications in electroluminescent devices.

Main Methods:

• Synthesis of organo-copper(i) halide complexes.
• Single-crystal X-ray diffraction for crystal structure determination.
• Photoluminescence spectroscopy to measure quantum yields and excited-state dynamics.
• Preliminary thin-film deposition experiments.

Main Results:

• Successful synthesis and structural definition of organo-copper(i) halide complexes with a Cu4I4 cubane core.
• A specific complex exhibited a high luminescence quantum yield of 76%, attributed to a columnar arrangement of cubane clusters stabilized by N-HI hydrogen bonds.
• The enhanced rigidity of the cubane core, due to hydrogen bonding, was linked to a slow radiationless deactivation rate, contributing to high luminescence efficiency.
• Preliminary thin-film studies indicated suitability for electroluminescent device applications.

Conclusions:

• Organo-copper(i) halide complexes with Cu4I4 cubane cores possess tunable photophysical properties.
• The observed high luminescence quantum yield is strongly influenced by crystal packing and hydrogen bonding, enhancing core rigidity.
• These materials show promise for cost-effective and efficient electroluminescent devices.