Spintronic OLED Debuts

An organic light-emitting diode (OLED) whose intensity is mediated by electron spin rather than purely by electronic charge may usher in a new breed of organic displays that are cheaper, brighter, and controlled by magnetic fields (Science, DOI: 10.1126/science.1223444). Z. Valy Vardeny of the University of Utah and colleagues based their spintronic device, which emits orange light, on their previous development of an “organic spin-valve,” a switch that regulates current on the basis of the up or down alignment of electron spin. Several augmentations to the original spin-valve design, including a deuterated derivative of poly(phenylene vinylene) and a thin layer of lithium fluoride on a cobalt electrode, make it possible to inject both negatively charged electrons and positively charged electron holes into the device, rather than only electrons. The collisions of the oppositely charged particles then generate photons. An external magnetic field, which aligns the spins of the electrons and electron holes, adjusts the intensity of the light. With further research, Vardeny envisions the development of spin-OLEDs that change colors.