Organic light-emitting diodes (OLEDs) are manufactured on the basis of platinum metal derivatives that can convert electric charge into light with an efficiency of 100%. However, light-emitting materials that have already found application, including organic derivatives of platinum and iridium, are characterised by high cost and rapid burnout of the radiating layer.
An attempt to solve this problem has been made by the scientists from St. Petersburg State University, the Kurnakov Institute of General and Inorganic Chemistry RAS and the University of Liverpool, who applied a new approach to the creation of OLED materials based on compounds of palladium, a platinum group metal. They obtained new compounds in the form of crystals, which emitted bright green light during irradiation by ultraviolet light, and thin polymer films. To determine the structure of the crystals, the scientists exposed them to X-rays, which fell upon the detector along a trajectory that depended on the structure of the compound under study.
The authors found that the distance between palladium atoms in the crystals is so small that an interaction occurs between the metals, leading to the redistribution of electrons, as a result of which the substance can go into a radiating state. By replacing palladium atoms with platinum atoms, one can obtain substances with yellow, orange and red radiation.
“Palladium is a metal of the platinum group, and it has a larger content in the Earth’s crust compared to platinum and iridium; nevertheless, its compounds are rarely if ever used in light-emitting materials because a lot of its energy gets scattered in the form of heat. We managed not only to obtain new palladium compounds with effective luminescence, but also, which I believe is more important, to develop a recipe for a new type of light-emitting materials,” Mikhail Kinzhalov, one of the authors of the study and doctor of chemical sciences, is quoted as saying by the Russian Science Foundation.
