Plasmonic-Enhanced Luminescence Characteristics of Microscale Phosphor Layers on a ZnO Nanorod-Arrayed Glass Substrate

Abstract

We present a planar luminescent layer for glare-free, long life-span white light-emitting diodes (LEDs), with attractive light outputs. The novel and facile remote phosphor approach proposed in this work enhances luminescence properties by combining a waveguiding ZnO-based nanostructure with plasmonic Au nanoparticles. The system comprised a micro-scale yellow phosphor layer that is applied by simple printing onto an Au nanoparticle-dispersed ZnO nanorod array. This architecture resulted in a considerable enhancement in luminous efficacy of approximately 18% due to the combination of waveguide effects from the nanorod structure and plasmonic effects from the Au nanoparticles. Performance was optimized according to the length of the Zn nanorods and the concentration of Au. An optimal efficiency of ~84.26 lm/W for a silicate phosphor-converted LED was achieved using long ZnO nanorods and an Au concentration of 12.5 ppm. The finite-difference time-domain (FDTD) method was successfully used to verify the luminous efficacy improvements in the Au nanoparticle-intervened nano-structures via the wave-guiding and plasmonic effects.