Swapping out the silicon for flexible, lightweight and inexpensive polymers has been a goal of materials scientists for several decades in the hope of making more powerful yet lower priced circuits with the added benefits of flexibility and toughness and opening up the efficiencies of fiber optic data transmission to data storage.
Writing in the April 16 issue of the journal Nature Communications, a team from the University of Iowa and New York University point out that a major obstacle to the development of next-generation circuitry lies in the fact that magnetic and spin-based technologies for data storage and processing using light instead of electrons suffer from optical losses in the magnetic metals used and the resistivity of semiconductor spin-based emitters at room temperature. For semiconducting polymers high energy barriers thus exist to the reading of stored information. But the magnetic aspect means data can be stored for years without additional power.
"A critical issue is how to convert information from one type to another [stored to transmitted]," explains Michael Flatté. "Although it does not cost a lot of energy to convert one to the other in ordinary, silicon chip-based computers, the energy cost is very high for flexible, plastic computing devices that are hoped to be used for inexpensive 'throwaway' information processors.
He and his colleagues have now demonstrated an efficient means of converting information encoded in magnetic storage to light in a flexible plastic device. They were able to demonstrate information transduction between a ferromagnet thin film (cobalt-platinum) just a few nanometers thick and an organic light-emitting diode (OLED) at room temperature with no current flow between the magnet and the organic device. The approach overcomes the weakness of the spin-orbit interaction and the low efficiency of spin injection from magnetic electrodes seen at anything but low temperature and with low polarization efficiency. The team explains that the magnet induction process exploits the spin dependence of the exciton recombination process in the organic semiconductor.
"The magnetic fields from the magnetic storage device directly modify the light emission from the device," explains team member Markus Wohlgenannt. "This could help solve problems of storage and communication for new types of inexpensive, low-power computers based on conducting plastics." The proof of principle was carried out on large-scale devices but there is no obstacle to their miniaturization for viable high-capacity storage technologies. "Regarding the next step, as described we demonstrated stored to transmitted but not transmitted to stored," Flatté told Materials Today. "We would like to do that in order to demonstrate information transduction in both directions."
"Magnetoelectroluminescence for Room Temperature Transduction between Magnetic and Optical Information" in Nature Commun, 2014, 5, #3609; DOI: 10.1038/ncomms4609
David Bradley blogs at http://www.sciencebase.com and tweets @sciencebase, he is author of the popular science book "Deceived Wisdom".