Spintronic OLED promises brighter displays

July 14, 2012 // By Christoph Hammerschmidt
University of Utah physicists invented a “spintronic” organic light-emitting diode or OLED that promises to be brighter, cheaper and more environmentally friendly than the kinds of LEDs currently used in television and computer displays, lighting, traffic lights and numerous electronic devices.

The Utah physicists made a prototype of the new kind of LED – known technically as a spin-polarized organic LED or spin OLED – that produces an orange color. Valy Vardeny, University of Utah distinguished professor of physics expects it will be possible within two years to use the new technology to produce red and blue as well, and he eventually expects to make white spin OLEDs.

However, it could be five years before the new LEDs hit the market because right now, they operate at temperatures no warmer than about -33°C, and must be improved so they can run at room temperature, Vardeny adds.

The study was funded by the U.S. National Science Foundation, the U.S. Department of Energy, the Israel Science Foundation and U.S.-Israel Binational Science Foundation. The research was part of the University of Utah's new Materials Research Science and Engineering Center, funded by the National Science Foundation and the Utah Science Technology and Research initiative.

The device invented by the Utah physicists uses an organic semiconductor, but isn't simply an electronic device that stores information based on the electrical charges of electrons. Instead, it is a “spintronic” device – meaning information also is stored using the “spins” of the electrons. A low voltage is used to inject negatively charged electrons and positively charged “electron holes” through the organic semiconductor. When a magnetic field is applied to the electrodes, the spins of the electrons and electron holes in the organic semiconductor can be manipulated to align either parallel or antiparallel.

In the new study, the physicists report two crucial advances in the materials used to create “bipolar” organic spin valves that allow the new spin OLED to generate light, rather than just regulate electrical current. Previous organic spin valves could only adjust the flow of electrical current through the valves.

The first big advance was the use deuterium instead of normal hydrogen in the organic layer of