Enhancement of Luminous Efficiency and Uniformity of CCT for Quantum Dot-Converted LEDs by Incorporating With ZnO Nanoparticles

• Published in: IEEE transactions on electron devices Vol. 65; no. 1; pp. 158 - 164
• Main Authors: Tang, Yong, Li, Zhi, Li, Zong-Tao, Li, Jia-Sheng, Yu, Shu-Dong, Rao, Long-Shi
• Format: Journal Article
• Language: English
• Published: IEEE 01.01.2018
• Subjects: Cadmium compounds; Encapsulation; II-VI semiconductor materials; Light emitting diodes; Light-emitting diodes (LEDs); Nanoparticles; quantum dots (QDs); Scattering; Zinc oxide; ZnO nanoparticles
• ISSN: 0018-9383; 1557-9646
• DOI: 10.1109/TED.2017.2771785

ZnO nanoparticles were incorporated into quantum dot (QD)-silicone encapsulation materials of the light-emitting diodes (LEDs) to exploit their strong scattering effect, which were proved by the ZnO-only film experiment. The novel packaging scheme led to a decrease in the radiation flux because of the conversion-energy loss of QDs and backscattering of ZnO nanoparticles. Under the similar color coordinate, the luminous flux of the ZnO-incorporated QD-LED showed a 3.37% increase compared to the conventional structure. This was attributed to the scattering effect, which enhanced the utilization of blue light and the conversion of yellow light. And the angular-dependent correlated color temperature (CCT) deviation was reduced from 862 to 712 K in the range of −70° to 70°. Moreover, the CCT monotonically decreased, and the chromaticity coordinate steadily shifted to the yellow region as the amount of ZnO nanoparticles increased. Therefore, ZnO nanoparticles can be a favorable optical performance enhancer for the future generation of QD-converted LEDs.