At the Paul Scherrer Institute (PSI), researchers have discovered a green luminescent substance that could enable OLEDs to deliver high light yields inexpensively and on a large scale.
Many of the materials that have been considered for OLEDs contain expensive additives such as iridium, making their large-scale application impractical. The researchers at PSI turned to the copper-containing compound CuPCP. Copper is a relatively inexpensive metal, and the compound CuPCP can be easily produced in large quantities.
At the Swiss Light Source (SLS) and the x-ray free-electron laser (SwissFEL) facilities at PSI and the European Synchrotron Radiation facility in France, the researchers investigated the short-lived excited states of CuPCP. They examined how the structure of the compound changed when it absorbed energy, and how the charge was distributed over individual atoms after excitation.
“We wanted to understand what the excited state of the compound looks like,” physicist Grigory Smolentsev said. “This reveals how high the losses of energy that will not be released as light are likely to be, and it shows us how we can possibly minimize these losses.”
The measurements taken by the researchers confirmed that the CuPCP substance could potentially be a light-emitter for OLEDs. The CuPCP compound’s chemical properties make it possible to achieve a high light yield, the researchers said. One reason for this is that the molecule is relatively stiff, and its 3D structure changes only slightly when excited.