Solid-Liquid Mixing-state Organic Lenses for Deep-Ultraviolet Light-Emitting Diodes to Enhance the Light-Extraction Efficiency

Deep ultraviolet light-emitting diodes (DUV-LEDs) have been considered as the most potential ultraviolet light sources, however, the traditional packaging with flat quartz glass has severe total internal reflection (TIR) loss, largely reducing the efficiency of DUV-LED. It is an efficient method to address this problem using organic lens, but traditional organic materials cannot be applied in DUV-LEDs because they are easily cracked by short-wave ultraviolet light. In this report, solid-liquid mixing state (SLMS) organic lens is proposed to enhance the light extraction efficiency and reliability of DUV-LEDs. Results show that the radiant power of DUV-LEDs using SLMS organic lens is enhanced by 53.86% under the injection current of 150 mA compared to DUV-LEDs (275nm)encapsulated with conventional flat quartz glass. Moreover, after 279 hours continuous operation, DUV-LEDs encapsulated with SLMS organice lens can still radiate 8.289 mW, which is only 3.94% lower than the initial power. Consequently, an efficient, low-cost and universal strategy has been proposed to enhance the light-extraction efficiency of DUV-LEDs, which has a great application prospect in packaging industry of DUV-LEDs.