New technology for LED manufacturers
According to reports, researchers at Saudi Arabia's King Abdullah University of Science and Technology (KAUST) have developed a nanocrystalline material that can rapidly convert blue light into white light.
While technologies such as Wi-Fi and Bluetooth have matured, there are still several benefits to shortening the wavelengths of electromagnetic waves used to transmit information.
So-called visible light communication (VLC) harnesses the unregulated electromagnetic spectrum and may be more energy efficient. VLC also offers a way to combine information transmission, lighting and display technologies, such as using ceiling lights to provide internet connectivity for laptops.
Many visible light communication (VLC) applications such as these require white LEDs, typically implemented by combining blue-emitting diodes with phosphors that convert the light to red and green. However, this transition process is not fast enough to match the switching speed of the LED on and off.
"The VLC rate achieved with the white light produced in the above way is limited to 100 million bits per second," said Boon Ooi, professor of electrical engineering at KAUST.
Ooi, member of the Photonics Laboratory at King Abdullah University of Science and Technology (KAUST), Osman Bakr, associate professor in the Laboratory of Functional Nanomaterials at KAUST, and their colleagues used nanocrystal-based converters that enable higher data transfer rates .
Based on a simple, cost-effective solution, combined with conventional nitride phosphors, the research team fabricated cesium lead bromide nanocrystals of about 8 nanometers in size. When illuminated by a blue laser, the nanocrystals glow green, while the nitrides glow red, which combine to create an inviting white light.
The researchers used a technique called "femtosecond transient spectroscopy" to characterize the optical properties of the nanocrystalline material. They were able to show that the optical process of cesium lead bromide nanocrystals takes roughly 7 nanoseconds. This means they can tune the light emission frequency to 491 megahertz, which is potentially 40 times faster than using phosphors, enabling data transfer rates of 2 billion bits per second.
"The fast reaction is partly due to the size of the crystals," Bakr said. "The steric confinement makes it more likely that electrons and holes will recombine and emit photons."
Importantly, the quality of white light produced using perovskite nanostructures is comparable to current LED technology.
