High Stability of Liquid-Typed White Light-Emitting Diode with Zn0.8Cd0.2S White Quantum Dots

Chin-Chuan Huang,Hao-Chung Kuo,Chun-Liang Lin,Yan-Kuin Su,Kuo-Hsiung Chu,Chia-Wei Sun,Chin-Wei Sher

doi:10.3390/coatings11040415

Abstract

In this study, we demonstrate a new design of white light-emitting diode (WLED) with high stability and luminous efficiency as well as positive aging. Colloidal ternary Zn0.8Cd0.2S (named Zn0.8) white quantum dots (WQDs) were prepared by chemical route and dispersed in xylene, integrating them into an ultraviolet light-emitting diode (UV-LED) to form WQD-white light emitting diode (WQD-WLED). High efficiency, high color quality and excellent reliability of WQD-WLED with neutral white correlated color temperature (CCT) can be obtained. The experimental results indicate that the stability of relative luminous efficiency and color rendering index (CRI) of the WQD-WLED can reach up to 160 and 82%, respectively. Moreover, the WQD-WLED can operate more than 1000 h under 100 mA, and the quantity of WQDs in the glass package can be reduced.

Highlights

The phosphor-converted white light-emitting diode (WLED) has attracted a significant amount of attention due to its low material cost, good thermal stability, longer lifetime, higher luminous efficiency and environmental sustainability for solid-state lighting (SSL) [1,2,3]
Coordinate-shift, while the LWQD-WLED remains at almost the same position after 1000 h of operating time
RWQD-WLED shows moderate CIE coordinate-shift, while the LWQD-WLED remains at almost the same position after 1000 h of operating time

Summary

Introduction

The phosphor-converted white light-emitting diode (WLED) has attracted a significant amount of attention due to its low material cost, good thermal stability, longer lifetime, higher luminous efficiency and environmental sustainability for solid-state lighting (SSL) [1,2,3]. Using liquid-type QDs is one of the strategies to improve the performance of QDs-based WLED Most of those devices, using the special WQDs as light converting materials in liquid-type QD-based WLED is a new type of WLED to match the DOE demands in the SSL without self-absorption between different colors of monochromatic QDs, and it is important to design a container that liquid-type WQD can be well sealed inside without solvent evaporation. We designed a glass box to protect the white light Zn0.8Cd0.2S (named Zn0.8) QDs to keep it at a liquid state This method can increase the luminous efficiency and reliability of WQDs-based devices. The liquid-type WQD LED (LWQD-WLED) demonstrates that the luminous efficiency, color rendering index (CRI), and correlated color temperature (CCT) of devices are 5 lm/Welectric, higher than 80 and 4360 K, respectively. The ultra-high stability and luminous efficiency of the device means that progress towards outstanding performance of commercially viable solid-state lighting has been made

Experiment

Measurement and Analysis

Findings

Conclusions