Improving Ambient Contrast Ratio and Color Uniformity of Mini Full Color Light-Emitting Diodes Using an SiO2/Graphite Bilayered Packaging Structure

Abstract

Abstract Mini full-color light-emitting diodes (mini-fc-LEDs) are a promising solution for display applications, including outdoor, cinema, and wearable devices, owing to their high resolution. However, it is difficult to simultaneously obtain high color uniformity and ambient contrast ratio (ACR). To solve this issue, we report a bilayered packaging structure with an SiO2 scattering layer on the bottom and a graphite extinction layer on the top. The bilayered packaging structure combines the scattering effect of SiO2 nanoparticles and the extinction effect of graphite nanoparticles, wherein the scattering effect improves the color uniformity, and the extinction effect improves the ACR. The color uniformity and ACR of the mini-fc-LEDs were selectively adjusted by changing the nanoparticle concentration and the thickness ratio of the bilayer. Compared to conventional devices, the inhomogeneity of the bilayered devices reduced by 65.9%, the ACR increased by 32.9%, and the figure of merit (FOM, representing the overall performance of the device) increased by 168.8%. We believe that the proposed packaging structure can also be applied to other LEDs such as OLEDs and micro-LEDs.