Enhancing Light Efficiency and Moisture Stability of the Quantum Dots-Light-Emitting Diodes by Coating Superhydrophobic Nanosilica Particles

Quantum dots-light-emitting diodes (QDs-LEDs) have attracted extensive attention in recent years due to their outstanding performance of color-rendering index (CRI). QDs were found to undergo severe fluorescence quenching in moisture environments, while rare solutions were proposed to solve this issue. In this article, 1H,1H,2H,2H-perfluorooctyltrichlorosilane (FOTS)-modified superhydrophobic nanosilica (FOTS-NS) particles were synthesized and coated on the QDs/polymer films to prevent the moisture from penetrating the films. The light efficiency of the FOTS-NS-coated LEDs was investigated, and the moisture stability of the FOTS-NS-coated QDs/polymer films was tested in an extreme moisture environment (50 °C, 99.6% relative humidity) for 270 h. The results show that compared with the uncoated LEDs, the FOTS-NS layer increases the light efficiency by ~10% for the blue LEDs and ~3.8% for the white LEDs (correlated color temperature of ~5000 K and Ra of ~91) by optimizing the particle deposition density of the FOTS-NS. Besides, the normalized peak intensity degradation of QDs embedded in the coated and uncoated films after aging for 270 h is ~35.68% and ~77.66%, showing the capacity of FOTS-NS layer on enhancing the moisture stability of the QDs-LEDs.