An ultraviolet (UV) transparent and stable methyl-siloxane hybrid material was prepared by a facile sol-gel method. The transparency and stability of a UV-LED encapsulant is an important issue because it affects UV light extraction efficiency and long-term reliability. We introduced a novel concept for UV-LED encapsulation using a thermally curable oligosiloxane resin. The encapsulant was fabricated by a hydrosilylation of hydrogen-methyl oligosiloxane resin and vinyl-methyl siloxane resin, and showed a comparable transmittance to polydimethylsiloxane (PDMS) in the UVB (∼300 nm) region. Most remarkably, the methyl-siloxane hybrid materials exhibited long-term UV stability under light soaking in UVB (∼300 nm) for 1000 h.
Keywords: UV LED encapsulant; UV transparency; hybrid materials; methyl siloxane; sol−gel.