Researchers unveil new developments in OLED lighting efficiency

According to scientists from Philips Research and Eindhoven University of Technology, this is an important step forward for OLED device optimisation and efficiency that is determined by the position of the narrow zone in which the light is generated. The findings were published in Nature Photonics. OLED lighting works by passing electricity through one or more thin layers of organic semiconductors. These layers are sandwiched between two electrodes and the whole 'sandwich' is deposited onto a supporting sheet of glass or other transparent material. When current is applied to the electrodes it flows through the organic film and the film emits light. Using different materials in the films makes it possible for the OLEDs to emit differently coloured light, and using a combination of materials, white light is emitted. PhD student Marco Carvelli, who part-headed the research, said: "There are many factors that influence the efficiency, or light out-coupling efficiency. Not all the light reaches our eyes, as some of it is trapped and absorbed in the OLED, particularly when it is formed close to the electrodes. In the most efficient OLEDs the light comes nicely from the centre. Simply put, we have provided the microscope through which we can see whether we are able to perfectly realise that goal." Dietrich Bertram, manager of the OLED Lighting business centre at Philips Lighting, added: "This is a great achievement and it demonstrates the good progress we are making in understanding OLEDs. The insights from this and other research activities are important contributions to further improving the performance of our Lumiblade OLED lighting devices and to secure our leading position in OLED lighting."