Enhanced Light Extraction From DUV-LEDs by AlN-Doped Fluoropolymer Encapsulation

AlN-doped fluoropolymer encapsulation layer was proposed for deep-ultraviolet light-emitting diodes. The proposed method can significantly enhance the light extraction from the chip-on-board packaging structure, which is attributed to the increased refractive index and light scattering ability of the encapsulant layer by the doping of AlN nanoparticles (NPs). When the AlN NPs content increases from 0.05 to 0.15 wt%, the light output power enhancement increases from 10.1% to 16.4% at a driving current of 120 mA compared with pure fluoropolymer packaging structure. Furthermore, after aging tests at 100 °C for 600 h, the relative light output power of the 0.15 wt% AlN-doped fluoropolymer structure is only reduced by 5.3%, which is much lower than the pure fluoropolymer structure of 13% and the conventional silicone structure of 23.2%.