Preparation of ZrO2/silicone hybrid materials for LED encapsulation via in situ sol-gel reaction

Organic silicones have been used as encapsulant materials for light-emitting diodes (LEDs) for many years, while their performances need to be improved in order to satisfy the requirements of high-power LEDs. A ZrO 2 /silicone hybrid resin (ZHR) was synthesized for LEDs encapsulation by in situ sol-gel reactions. The oligosiloxane was synthesized as polymeric matrix by nonaqueous sol-gel condensation using diphenylsilanediol (DPSD), vinyltrimethoxysilane (VTMS), and 3-methacryloxy propyl trimethoxysilane (MPTMS) as monomers. Then zirconium propoxide was added into this polymeric matrix to be hydrolyzed to obtain the hybrid resin with a uniform dispersion of ZrO 2 nanoparticles. The Si–O–Zr covalent bond was detected and benefited for excellent dispersibility of the ZrO 2 nanoparticles and the well compatibility between organic and inorganic phases. The cured ZHR with 5 wt% ZrO 2 content showed high light transmittance (greater than 80% in visible light range), high refractive index (=1.56), and high thermal stability (no yellowing at 150°C for 240 hours). The luminous flux of the LED chip with ZHR encapsulant was 10% higher than that of the pure silicone resin, suggesting that ZHR has great application potential in the field of LED packaging.