pISSN 0374-4914 eISSN 2289-0041

## Research Paper

New Phys.: Sae Mulli 2021; 71: 210-217

Published online February 26, 2021 https://doi.org/10.3938/NPSM.71.210

## Study on the Effect of ZrO$_{2}$ nano Particles on the Efficiency and Color Properties of White Light Emitting Diodes

Jun Yeong KIM, Hye-Rin KIM, Gi Jung LEE, Seung Chan HONG, Jung-Gyun LEE, Jae-Hyeon KO*

School of Nano Convergence Technology, Nano Convergence Technology Center, Hallym University, Gangwon 24252, Korea

Correspondence to:hwangko@hallym.ac.kr

Received: October 16, 2020; Revised: December 28, 2020; Accepted: January 4, 2021

### Abstract

The effect of the scattering from ZrO$_{2}$: Y$_{2}$O$_{3}$ nano particles on the emitting properties of white light emitting diodes (LEDs) consisting of red-green phosphors (CaAlSiN$_{3}$:Eu$^{2+}$ with Lu$_{3}$Al$_{5}$O$_{12}$:Ce$^{3+}$) and a blue LED chip was investigated in this study. The color coordinates of white LEDs increased with increasing concentration of nanoparticles, and their changes were more substantial at larger concentration. Especially, the relative intensity of the red component in the white spectrum became higher at larger concentrations, which was attributed to the multiple-scattering effect for blue photons and green photons. The luminous efficiency decreased with increasing concentration of nanoparticles due to multiple scattering, trapping and reabsorption of emitted light in the encapsulant of the white LED. This study showed that appropriate color properties can be achieved, even using a smaller amount of expensive red phosphors, by utilizing nanoparticles and suggests the possibility of realizing low-cost, high-CRI (color rendering index) lighting devices.

Keywords: Illumination, Phosphor, White LED, Nanoparticle