Guided mode caused by silicon nanopillar array for light emission enhancement in color-converting LED.

Plasmonic metallic nanostructures have been demonstrated an effective way to enhance the light emission efficiency in LEDs. Here, we propose a design of white LEDs that combining dielectric silicon nanopillar array in the color-converting layer. By investigating theoretically the guided mode caused by the nanopillar array-waveguide system, we demonstrate that the silicon nanopillar arrays enable larger near-field enhancement and more efficient photons emission property than the plasmonic counterparts. These performances make the silicon nanopillar arrays have potential application in light converter for efficient white LEDs. We also show that the guided mode can be controlled by changing the period of nanopillar grating and the thickness of polymer layer. More significant performance can be achieved by further optimizing the shape and size of the silicon nanoparticles. Compared with the square nanoparticle arrays, the hexagonal nanopillar arrays are demonstrated to have larger field enhancement and emission enhancement. Our research is expected to give insights into the design and optimization of the solid-state lighting systems by using silicon nanostructures, and the all-dielectric metamaterials for gaining or lasing devices.