Enhancing Light Extration of Near-Ultraviolet LED Incorporating Scattering Nanoparticles by a Pre- prepared Lens Packaging Structure

Near-ultraviolet light-emitting diodes (NUV- LEDs) are more likely to be commercial due to its mature chip fabrication process and package technologies. However, the low light extraction efficiency (LEE) of NUV-LEDs limits its commercialization. In this study, we introduce a novel pre- prepared lens packaging structure for NUV-LEDs incorporating with scattering particles and optimize their structures by the optical simulation methods. Three packaging types structure including the blank LED, LED incorporating with scattering particles, and LED incorporating with scattering particles and pre-prepared lens are modeled for optical simulation. The influence of different scattering condition, lens structure and the substrate reflectivity were studied in detail by comparing different packaging types of NUV-LEDs. The light output power is extracted for comparisons after simulation. The NUV-LEDs with lens structure perform the best in light output power, and the improvement keeps rising with the higher bulk scattering coefficient. Besides, the reflectivity of the substrate contributes greatly to the component light extraction. Furthermore, the lens structure with different diameters were optimized and the result shows that the larger diameter lens can obtain greater improvement in optical output. When the reflectivity of the LED substrate is set as 80%, the NUV-LED with silicone and particles mixtures as well as lens structure shows 14.27% improvement in optical output power compared with the NUV-LED with particles and silicone mixtures at the bulk scattering coefficient value of 1 mm^-1. Consequently, the novel pre-prepared lens packaging structure could greatly improve the optical output of NUV-LEDs.