Enhanced Light Extraction Using Blue LED Package Consisting of ${\rm TiO}_{2}$ -Doped Silicone Layer and Silicone Lens

Abstract

A novel, blue light-emitting diode (LED) packaging structure with improved light and thermal characteristics is presented. The package includes a TiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> -doped silicone layer and silicone lens. This dual-layer graded refractive index structure used for LED encapsulation was fabricated using dispensing technology. In the LEDs doped with TiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> nanoparticles and a silicone lens, the light scattering capability and average refraction index of silicone were enhanced, thus reducing reflection losses. The LED achieved a light extraction efficiency increase of 24.5% and a junction temperature reduction of 12.1 °C compared with a conventional single-layer encapsulated LED. Consequently, the proposed structure not only improved the LED performance, but also reduced thermal accumulation in the packaging.