Light Efficiency Investigation of Ultraviolet Light-Emitting Diodes Combined With Polarized Emission and Packaging Structure

Abstract

Ultraviolet light-emitting diodes (UV-LEDs) have attracted extensive applications in resin curing, medical treatment, biochemical inspection, and disinfection. However, the UV-LEDs suffer from the main bottleneck of low light efficiency, which depends on the polarized emission and packaging structure of UV-LEDs simultaneously. In this work, we investigated the light efficiency of UV-LEDs combined with polarized emission and packaging structure. Four types of UV-LEDs (UVC-A, UVC-B, UVB, and UVC) without a lens (UV-Ref.), with a flat lens (UV-FL), and with a hemispherical lens (UV-HL) were fabricated, respectively. Through investigating the light output power, far-field emission pattern, and electrical field intensity distribution of UV-LEDs, the UV-HL packaging structure displays the highest emission intensity and light output power in the whole UV band. Compared with the UVC-A-Ref. and UVC-A-FL structures, the enhancement ratios of the light output power of UVC-A-HL structure are 28.9% and 46.5%, respectively. Furthermore, the light extraction efficiency of the TM-polarized mode in the UVC-A-HL structure is enhanced by 29.6% compared with the UVC-A-Ref. structure. The results indicate that the light extraction of UV-LEDs is greatly affected by the polarized emission and packaging structure. Our work opens an efficient guidance to enhance the light efficiency of various UV-LEDs with appropriate packaging structure.