Enhanced light extraction of deep ultraviolet light-emitting diodes by using optimized aluminum reflector.

Deep ultraviolet light-emitting diodes (DUV-LEDs) have become a promising UV light source for sterilization, disinfection, and purification. However, the challenge in practical application of DUV-LEDs still remains in their low light efficiency. In this paper, we propose an optimized aluminum (Al) reflector for the light extraction enhancement of DUV-LEDs. The optical model of DUV-LEDs was established, and the optical simulations were performed to achieve the optimized reflector. The DUV-LEDs exhibit the highest light efficiency when the reflector has the optimized feature sizes with an angle of 60°, a height of 2.0 mm, and an internal radius of 2.5 mm. Furthermore, the optimized reflector with different reflectance was fabricated and applied for the packaging of DUV-LEDs. Consequently, the light output powers of DUV-LEDs are enhanced by 28.8%, 37.0%, and 43.8%, respectively, by using the different reflectors at the driving current of 100 mA. It is attributed to the remarkable reflection effect of the Al reflector, which increases the light extraction of the sidewall emission from the DUV-LED chip.