High performance encapsulant for light-emitting diodes (LEDs) by a sol-gel derived hydrogen siloxane hybrid

The hydrosilylation reaction is a dominant curing method for the light-emitting diode (LED) silicone encapsulant, which requires characteristics of high transparency, high refractive index, and thermal stability against the LED junction temperature. In this research, we synthesized a hydrogen containing oligosiloxane resin through non-hydrolytic sol-gel condensation. Methyldiethoxysilane (MDES) and diphenylsilanediol (DPSD) were used as precursors and a non-hydrolytic sol-gel condensation reaction was performed under acidic conditions. The synthesized hydrogen oligosiloxane resin was mixed with a phenyl and vinyl containing oligosiloxane (PVO) resin, which was prepared by a sol-gel condensation between vinyltrimethoxysilane (VTMS) and the DPSD. This blended solution was cured at 150 degrees C for 4 hours to complete the hydrosilylation reaction. The cured material (phenyl hybrimer) shows low shrinkage during the curing reaction and provides excellent transparency (similar to 90% at 450 nm) and thermal stability (440 degrees C) with a high refractive index (n = 1.58 at 632.8 nm).