Light emitting diodes (LEDs) is used for wide range of applications such as backlight of liquid crystal display (LCD), vehicle lighting and general illumination. With the requirement of increasing size of LCD, LED is now used as the backlight source to provide more colorful and brighter picture. The encapsulant of LED plays an important role of light extraction. The efficiency that light passes from LED dies into surrounding encapsulations limits the light output. The light extraction can be improved by encapsulating LED with high refractive index encapsulants. Therefore, high refractive index nanocomposite has attracted considerable interests in LED encapsulation. If encapsulating resin with an index of 1.80 or more can be prepared, the light extraction efficiency will greatly enhanced due to vanish of internal reflection occurred at the interface between the light emitting semiconductor die and the resin.
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