Phosphor-Saving SiO₂-Aerogel-Embedded Silicone for Enhancing White LEDs Characteristics

Porous low-density SiO₂ aerogel and yttrium aluminium garnet (YAG) phosphor powders were simultaneously mixed in the silicone encapsulant to improve the light output characteristics of white light-emitting diodes (WLEDs) and reduce the amount of phosphor used. The YAG phosphor concentration in silicone encapsulant was fixed at 10 wt%, and the mixing concentration of SiO₂ aerogel was optimized according to the light output characteristics of WLEDs. WLEDs have the highest light output flux of 152 (± 1) lm and the smallest angle dependent correlated color temperature (CCT) difference of 209 K at room temperature and 350 mA when the mixing concentration of SiO₂ aerogel is 1.5 wt%. The light output flux and the angle dependent CCT difference of WLEDs are increased by 6.3% and reduced by 101K compared with those of WLEDs without SiO₂ aerogel, respectively. The optical axis CCT of WLEDs with a SiO₂ aerogel concentration of 1.5 wt% is 4950 (± 50) K, which is 550 K less than the 5500 (± 100) K of WLEDs without SiO₂ aerogel. The optical axis CCT of WLEDs with SiO₂ aerogel mixing concentration of 1.5 wt% can be increased to 5500 K by reducing the mixing amount of YAG phosphor by 5%, and the light output flux can still be higher than that of WLEDs without SiO₂ aerogel. This is the first time that SiO₂ aerogel has been mixed in the silicone encapsulant of WLEDs to improve the light output characteristics and reduce the YAG phosphor usage by 5%.