Thermally Stable Transparent Sol−Gel Based Siloxane Hybrid Material with High Refractive Index for Light Emitting Diode (LED) Encapsulation

Nonhydrolytic sol−gel condensation for the synthesis of nanosized inorganic−organic hybrid resin and hydrosilylation reaction under a Pt catalyst for the fabrication of oligosiloxane-based hybrid material (phenyl hybrimer) were used in this research. This combination of two chemical reactions results in material with useful properties for light emitting diode (LED) encapsulation. Until now, no polymers and phenyl polysiloxane materials have been reported with a high refractive index (over 1.52) and high transparency accompanied by resistance to yellowing induced by thermal degradation above 150 °C aging in air. In this article, we focused on the fabrication of a transparent and thermally stable phenyl hybrimer with high refractive index for LED encapsulation through siloxane networking by a hydrosilylation reaction with cross-linker and Pt caltalyst. The phenyl hybrimer has a high refractive index about 1.56. In particular, it has good thermal stability against discoloration to yellow by aging even at 200 °C, which is a key factor for the long lifetime of a LED encapsulant.