Fast UV-Curing Encapsulation for GaN-Based Light-Emitting Diodes

Due to the high refractive index of nitrides, encapsulation is necessary to improve the light extraction efficiency for GaN-based light-emitting diodes (LEDs). Traditional thermal-curing encapsulant needs to be heated for several minutes to form a dome-shaped lens, which is time-consuming. In this paper, we have developed a novel kind of silicon-based ultraviolet (UV)-curing encapsulant, for which only 20 s of near-UV (NUV) light radiation at room temperature is needed. The composition of the encapsulants is optimized to enhance light extraction ability. For 392-nm NUV LEDs packaged by this UV-curing encapsulant, the light output power is enhanced by 10.0%. Moreover, the LEDs packaged by UV-curing and thermal-curing encapsulant presented similar stability and reliability after 480 h of the aging test under a high driving current of 200 mA. This paper demonstrates the potential of silicon-based UV-curing encapsulants for the package of NUV, blue and white LEDs, which is time- and cost-effective for the LED industry.