Light by Linear Imidazolin-2-iminate Coinage Metals

• Applicant: Dr. Madalin Damoc
• Subject Area: Inorganic Molecular Chemistry - Synthesis and Characterisation
• Term: since 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 549397418

Since their discovery, organic light-emitting diodes (OLEDs) have replaced inefficient and ecologically harmful lighting sources such as incandescent lamps, fluorescent tubes, liquid crystal displays, etc., and afforded a new generation of lighting devices and screening technologies. Due to their improved efficiency their demand all over the world is expected to increase within the next years. Nonetheless, they still suffer from low operational stability, brightness, and external quantum efficiency. Special attention should be paid to the electroluminescent layer, which converts the electrical energy into light. The replacement of precious metal complexes used as emissive layers in OLEDs, such as those of Pt, Ru, and Os, with relatively more abundant and economic metals is needed. Approaching these challenges, we propose new chemical and photophysical strategies for new generations of emissive layers with enhanced characteristics. The target electroluminescent complexes will be of type M(X)(L) in linear geometry with M = Cu(I), Ag(I), which are widely abundant metals, but also M = Au(I) due to several advantages associated with this metal. The ligand setup includes heteroleptic combinations of a neutral ligand L [N-heterocyclic carbenes (NHCs) or cyclic alkyl amino carbenes (CAACs)] and a monoanionic substituent X (imidazoline-2-iminate). This ligand environment around the coinage metal ions affords enhanced photostability, high quantum efficiencies, as well as efficient harvesting of the excited states. The proposal includes a full photophysical characterization of the obtained complexes as well as the construction of powerful OLED devices with identified promising compounds. Therefore, the project displays a strong interdisciplinary character. The results are highly relevant for industrial applications in OLED production and will contribute knowledge of high ecological and economic value.

• DFG Programme: WBP Position