Getting better control of the light emitted from organic LEDs (OLEDs) could lead to faster links between the Internet and
mobile devices, according to a Scottish researcher.
Anyone who has tried to use the Wi-Fi on a crowded airplane or a packed hotel conference room knows it can be
maddeningly slow; there usually isn’t enough bandwidth . Some researchers, notably Harold Haas, head of the mobile
communications group at the University of Edinburgh, have proposed an alternate system—Li-Fi—which rapidly flickers
room lighting to send signals. To get even more bandwidth out of such a system, it would help if there were an easy way
to break the light up into different colors, using individual wavelengths to send different signals.
Ifor Samuel who heads the organic semiconductor optoelectronics group at the University of St. Andrews in Scotland
described a method his team has developed for making patterned OLEDs for a Li-Fi system at the fall meeting of the
Materials Research Society (MRS) in Boston in December. The idea, he explained to the MRS audience, is that the signal
would be created by high-speed CMOS chips that alter the blue light coming from an array of small, nitride-based LEDs.
OLEDs on top of the LEDs would act as a color conversion layer, multiplexing the signals into other colors.
Because OLEDs are malleable, it would be easy to imprint a diffraction grating into them. Such gratings could control
the direction in which the signal was sent. That could be useful, in slower-speed communications where controlling
direction is more desirable than a high data rate, to provide increased security or reduce power consumption