Preparation and characterization of high refractive index silicone/TiO2 nanocomposites for LED encapsulants

In this study, a uniform dispersion of TiO2 nanoparticles (NPs) in silicone for light-emitting diode (LED) encapsulation is demonstrated prepared through high-energy grinding method. Through interaction with surfactant, large clumps of the TiO2 underwent de-aggregation to form a stable dispersed solution, during the grinding process. The silicone/TiO2 composites were prepared by the blending of silicone resin with grinding TiO2 fillers in isopropyl alcohol solvent, which was removed before curing. The refractive index (RI) of surfactant-coated TiO2 NPs loaded silicone is 1.63 at 550 nm, significantly higher than that of conventional silicone (n = 1.50). The barrier properties and thermal conductivity (from 0.9 to 1.32 W/mK) of the silicone/TiO2 composites also can be enhanced, significantly. As a result, a high-power LED encapsulated with this composite showed more than 7.3% increase in the light output and better stability compared to that with the conventional silicone resin.