White light emitting diodes with enhanced CCT uniformity and luminous flux using ZrO2 nanoparticles.
To enhance the uniformity of correlated color temperature (CCT) and luminous flux, we integrated ZrO2 nanoparticles into white light-emitting diodes. This novel packaging scheme led to a more than 12% increase in luminous flux as compared to that in conventional dispensing structures. This was attributed to the scattering effect of ZrO2 nanoparticles, which enhanced the utilization of blue light. Moreover, the CCT deviation was reduced from 522 to 7 K in a range of -70 to +70°, and essentially eliminated the yellow ring phenomenon. The haze measurement indicated strong scattering across the visible spectrum in the presence of ZrO2 in the silicone layer, and this finding also substantiates our claim. In addition, the chromaticity coordinate shift was steady in the ZrO2 dispensing package structure as the drive current increased, which is crucial for indoor lighting. Combined with its low cost, easy fabrication, and superior optical characteristics, ZrO2 nanoparticles can be an effective performance enhancer for the future generation of white light-emitting devices.
Department of Photonics & Institute of Electro-Optical Engineering, National Chiao Tung University, Hsinchu 30010, Taiwan. hckuo@faculty.nctu.edu.tw.
Kuo-Ju
KJ
Chen
Hau-Vei
HV
Han
Hsin-Chu
HC
Chen
Chien-Chung
CC
Lin
Shih-Hsuan
SH
Chien
Chung-Ching
CC
Huang
Teng-Ming
TM
Chen
Min-Hsiung
MH
Shih
Hao-Chung
HC
Kuo