Experimental Investigation on the Moisture Stability of QDs-LEDs With Layered Packaging Structure

Quantum dots (QDs)/phosphor hybrid white light emitting diodes (QDs-LEDs) have attracted extensive attention in recent years due to their advantages of high light efficiency and high color rendering index (CRI). However, the QDs present poor thermal and moisture stability, which hinders the commercialization of QDs-LEDs. The layered packaging structure with QDs/silicone film upon the phosphors/silicone film was proposed to improve the thermal stability of QDs-LEDs, while the moisture stability of this packaging structure has not been verified so far. In this study, the moisture stability of QDs-LEDs with layered packaging structure in a high moisture environment with relative humidity of ~99.8% was experimentally investigated. The results show that the normalized light peak intensity degradations of QDs/silicone and phosphor/silicone films are 12.5% and 54.0% after aging for 178h, which indicates that the moisture stability of QDs is the key factor for determining the moisture stability of QDs-LEDs. The red light peak intensity degradations of QDs-LEDs with QDs/silicone film upon and below the phosphor/silicone film are 21.1% and 8.0% after aging for 178h, indicating that layered packaging structure with QDs/silicone film at the down layer can enhance the moisture stability of QDs-LEDs.