Less energy, higher brightness, nanowire LED will be commercialized within five years

According to research from the Niels Bohr Institute (NBI) at the University of Copenhagen in Denmark, LEDs made of nanowires can provide a brighter light source using less energy.

The researchers studied the nanowires in depth using X-ray microscopy, which allowed them to determine how to design the nanowires to provide optimal performance. The findings were published in the scientific journal ACS Nano.

The size of nanowires is only about 2 microns high (μm; 1μm is 1/1000mm), and the diameter is about 10-500 nanometers (nm, 1nm is about 1/1000μm). Nanowires designed for LEDs are composed of an inner gallium nitride (GaN) core and an outer layer of gallium indium nitride (InGaN), both of which are semiconductor materials.

The light source of this diode relies on the presence of mechanical strain between the two materials, and this strain depends greatly on how the two material layers contact each other. Robert Feidenhansl, professor at the University of Copenhagen in Denmark and director of the Bohr Institute, explained, "We studied a variety of nanowires using X-ray microscopy, even the same nanowires in principle, and we could see the differences and their quite different structures."

The relevant research was conducted using nanoscale X-ray microscopy at the "Deutsche Electron Synchrotron Institute" (DESY) electron synchrotron in Hamburg, Germany. Although this method is quite time-consuming and the results are often very limited or even only suitable for a single research topic. However, the special design of using nanoscale X-rays prevents the nanowires from being damaged during the process, allowing researchers to smoothly measure a series of nanowires simultaneously.

X-ray images of each nanowire show the distribution of scattering intensity and mechanical strain in the gallium nitride core and gallium indium nitride outer layer. This strain shows that the outer layer fits the core perfectly.

(Source: Northeastern University)

“We measured 20 nanowires, and we were very surprised when we saw the images, because you can clearly see the details of each nanowire, both the core and outer structures. If there are any defects or slight bends in the structure, it doesn’t function properly. So, we can find out exactly which are the best nanowires and have the most efficient core/shell structure,” explains Tomas Stankevic, a PhD student in the “Neutron and X-ray Scattering” research group at the Bohr Institute at the University of Copenhagen.

Robert Feidenhans’l said that nanowires will bring a more natural light source to LEDs and will also use lower power consumption. In addition, they can be used in smartphones, televisions, and various forms of lighting.

Researchers expect that this kind of nanowire LED lighting can be commercialized within five years.