University of Michigan develops ultra-narrow spectrum red light MicroLED

With its high brightness, long life and extremely small pixel size, Micro LED is regarded as the leader of the next generation of display and lighting technology, especially showing great potential in cutting-edge fields such as augmented reality, virtual reality and visible light communications.

Although blue and green InGaN-based LEDs have been successful, red-band LED performance still faces problems of low efficiency and color instability, which limits the popularity of Micro LED full-color display technology.

Regarding the problem of Micro LED red light, the team of Professors Yuanpeng Wu and Zetian Mi from the University of Michigan recently published new results in "Light: Science & Applications". The team solved the above problems through an innovative 3D nanowire photonic crystal structure.

Researchers have developed a new 3D nanowire red Micro LED device. The device achieves an extremely narrow emission spectrum, with a full width at half maximum of only 5 nm at a wavelength of 617nm. This narrow emission spectrum helps achieve a wider color gamut.

The extremely narrow spectral width significantly improves the color purity of the device, making its color coordinates fully compliant with the NTSC pure red standard and exceeding the Adobe RGB color gamut, which means that future Micro LED displays will have more realistic and highly saturated color performance.

In terms of efficiency, the measured peak external quantum efficiency of an ultra-miniature device with a size of only 1 square micron is about 12%. This performance improvement is due to the reshaping of spontaneous emission behavior by photonic crystals. The photonic band edge mode coupling enables the optical waveguide to emit perpendicular to the surface, with a divergence angle of less than 20 degrees, which greatly enhances the light extraction efficiency.

In addition, the device exhibits excellent stability. Within a range where the injected current changes by more than an order of magnitude, the peak wavelength of the device remains almost unchanged, completely solving the problem of wavelength instability caused by the quantum-confined Stark effect.