Ultra-high refractive index LED encapsulant

In this paper, we report a method for preparing a silicone-based nanocomposite material for high brightness light emitting diode (LED) packaging. High refractive index (RI) encapsulant is desired in order to reduce the RI contrast between the LED chip and air, thus increasing the light extraction efficiency (LEE). In our method, TiO₂ nanoparticles were added to the silicone resin to prepare the nanocomposite, and the RI was improved from 1.56 of neat silicone to 1.73 at the GaN-emitting wavelength of 460 nm. The nanocomposite also exhibits high relative transparency in the visible light wavelength of 300-800 nm. At 460 nm, the material containing 10 wt% filler loading shows above 90% relative transparency. Accelerated reliability test was conducted on the high-performance nanocomposites, and less than 2% degradation was measured in both RI and relative transparency.