A Significant Development in MicroLED Technology Has Come Out Of A Collaboration Between Lumileds And Eindhoven University Of Technology.

A significant development in MicroLED technology has come out of a collaboration between Lumileds and Eindhoven University of Technology.

The research team has successfully demonstrated a novel approach to improving MicroLED performance by integrating metallic or dielectric metasurfaces directly into the LED structure, resulting in dramatically improved light directionality and efficiency. This development addresses two critical limitations that have hampered MicroLED development: their relatively low external quantum efficiency (EQE) and their characteristic Lambertian emission pattern, which disperses light in all directions rather than concentrating it where needed.

The research team, led by Jaime Gómez Rivas from Eindhoven University of Technology and Toni López from Lumileds, developed a novel approach that integrates nanostructured metasurfaces within the LED architecture itself. These metasurfaces consist of precisely arranged aluminum (Al) or silicon dioxide (SiO₂) nanoparticles organized in hexagonal lattice patterns. The key innovation lies in how these metasurfaces interact with the quantum wells in the LED. Rather than modifying the semiconductor material itself-which can damage the active region and reduce performance-the researchers placed the metasurface above the multiple quantum wells (MQWs) of the LED. This configuration allows the metasurface to support collective resonances that result from coupling localized resonances in nanoparticles throughout the array.

The researchers created three different types of metasurface-enhanced MicroLEDs: a hexagonal diffraction array of aluminum nanoparticles designed to achieve directional enhancement of electroluminescence; a sub-diffraction metasurface that enhances omnidirectional light outcoupling, particularly useful for smaller LED devices; and a hexagonal diffraction array using SiO₂ nanoparticles instead of aluminum to avoid Ohmic losses in the metal.

The experimental results were impressive. For the first MicroLED type, the device showed a directionality enhancement of approximately 8.6 within the emission cone of ±30°. For the third type with the SiO₂ nanoparticles, researchers achieved an integrated light extraction efficiency (LEE) of 21.4 compared to the reference device.