Enhanced color-conversion efficiency between colloidal quantum dot-phosphors and nitride LEDs by using nano-patterned p-GaN

Abstract

We have demonstrated that color-conversion efficiency can be enhanced through the use of non-radiative energy transfer between CdSe/ZnS core/shell colloidal quantum dots(QDs) and nitride multi-quantum well(MQW) in light emitting diodes(LEDs) having nano-patterned p-GaN. The nitride LEDs having nano-patterned p-GaN were fabricated by selective deep etching of p-GaN by using self-assembled ITO nano-dots as a etch mask. For comparison, we also fabricated the nitride LEDs having groove-etched p-GaN as well as the LEDs having a normal p-GaN layer. The results show that the LEDs having nano-patterned p-GaN showed the higher color conversion efficiency of 15.5 % and the improved effective internal quantum efficiency of 71 %. The enhanced efficiency can be attributed to sufficient close QD-MQW separation due to deep etching of p-GaN by using nano-patterning, which resulted in faster energy transfer rate of 2.47 ns-1 for non-radiative QD-MQW energy-transfer.