Making the shift from blue to red for better LEDs

Micro-LEDs are a promising technology for the next generation of displays. They have the advantage of being energy efficient and very small.

But each LED can only emit light over a narrow range of colors. A clever solution is to create devices that combine many different LEDs, each emitting a different color. Full-color micro-displays can be created by combining red, green and blue (RGB) micro-LEDs. Now, a KAUST team of Zhe Zhuang, Daisuke Iida and Kazuhiro Ohkawa have worked to develop a more efficient red LED.

Zhang's team created and characterized a series of square devices with a side-length of 98 or 47 micrometers. Their 47-micrometer-long devices emitting light at a peak wavelength of 626 nanometers were shown to have an external quantum efficiency—the number of photons emitted from the LED per electron injected into the device—of up to around 0.87 percent. Also, the color purity of the red micro-LED is optimum because it is very close to the primary red color defined by the industrial standard known as Rec. 2020.