Organic light emitting diodes, OLEDs for short, have already been traded for some time as the innovative light of the future with applications in flexible displays and large panel lighting. Currently special attention is payed in the research regarding electro luminescent materials in which expensive precious metals such as platinum and iridium are replaced for cost-efficient and more sustainable solutions. New materials suitable for application in e.g. OLEDs should possess properties such as good availability, facile synthetic procedure, no precious metals, good solubility, great thermal stability in the solid and in solution, good resistance to water and air, and also efficient luminescence. This new compound class on the basis of organometallic copper compounds especially suits these purposes.
Chemists at the University of Bremen discovered a new substance class which, based on special organometallic copper compounds (cuprates), can be synthetized without difficulty from inexpensive starting materials. Compounds of the new class display exceptional luminescence properties, that is, for instance, very sharp emission and an extraordinarily high quantum efficiency. An exemplary copper compound according to invention contains a tetranuclear copper cluster. This Cu4 core is surrounded almost completely by a ligand system, a structural arrangement which accounts for a high thermal stability and structural integrity in solution. The core innovation is that the ligand system protects the labile and otherwise extremely air/moisture-sensitive copper-carbon bond. It allows for the exploitation of this structural motif and substitutes the widely used iridium-carbon bond as a key feature for the luminescent properties. It is remarkable that the high complexity of the compound can be realized by very simple synthetic reactions.
The cuprate compounds are suited as potential, robust and inexpensive materials to be built into OLEDs. OLEDs are used for manufacturing flexible displays and for innovative surface illumination. The invention can support the further development of OLEDs and their application in products.
Organometallic copper compounds, cuprates, luminescence, light-active molecules
10 2017 207 804.9; Patent registered in Germany
University of Bremen