Researchers have gained insights into a promising material for organic light-emitting diodes (OLEDs). The substance enables high light yields and would be inexpensive to produce on a large scale. The newly generated understanding will facilitate the rapid and cost-efficient development of new lighting appliances in the future.

The compound is a yellowish solid; when dissolved in a liquid or a thin layer is placed on an electrode and an electric current is applied, it gives off an intense green glow — the molecules absorb the energy supplied to them and gradually emit it again in the form of light. This process is called electroluminescence.

This green luminescent substance is a candidate for producing OLEDs. For a number of years, OLEDs have been found in the displays of smartphones and other devices such as flexible television screens. In addition, OLEDs make cost-efficient room lighting with a large surface area possible. The materials best suited to these applications still need to be found since many substances under consideration for OLEDs contain expensive materials such as iridium, impeding their application on a large scale and on extensive surfaces. Without such additives, the materials can actually emit only a small part of the energy supplied to them as light; the rest is lost as vibrational energy.

The goal of current research is to find more efficient materials for cheaper and more environmentally friendly displays and large-area lighting. Inexpensive and readily available metals such as copper promise progress. Researchers have made a more precise examination of the copper-containing compound CuPCP. There are four copper atoms in the middle of each molecule, surrounded by carbon and phosphorus atoms. Copper is a relatively inexpensive metal and the compound itself can be easily produced in large quantities.

Researchers took a look at the short lived excited states of the copper compound. The measurements confirmed that the substance is a good candidate for OLEDs due to its chemical structure. The compound’s quantum chemical properties make it possible to achieve a high light yield. One reason for this is that the molecule is relatively stiff and its 3D structure changes only slightly when excited. The measurement data will help chemists understand which part of the molecule stands in the way of high efficiency and how the compound can be improved to increase its light output.

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