Encapsulation is a widely recognized method for enhancing the stability of colloidal quantum dots (CQDs). However, traditional encapsulation methods for solid-state materials expose encapsulated CQDs to risks such as ligand loss and poor dispersion. Additionally, these encapsulated CQDs still face the risk of aging due to surface ligand bond breakage under high-energy radiation. In this study, we found that quantum dots in solution exhibited enhanced ultraviolet (UV) tolerance compared to their counterparts in solid form under an inert atmosphere. We attribute this enhancement to improved ligand retention and self-healing of quantum dots in solution. Herein, we introduce a novel method for fabricating liquid-encapsulated quantum dot (LEQD) color conversion films. This technique leverages the self-healing capability of ligands in liquid-state quantum dots to enhance the UV and thermal stability of the quantum dot color conversion films. Experimental results demonstrate that LEQD films exhibit better resistance to UV radiation and high temperatures than solid-encapsulated quantum dot (SEQD) color conversion films. After 400 h of exposure to 100 mW blue light-emitting device (LED) light at 60 °C and 90% humidity, the brightness of LEQD film retained 90% of its initial level. This liquid-state quantum dot encapsulation approach offers a promising pathway for developing more durable quantum dot color conversion films.

The origin of the efficiency drop of quantum dot light-emitting diode (QLED) under consecutive voltage sweeps is still a puzzle. In this work, we report the voltage sweep behavior of QLED. We observed the efficiency drop of red QLED with ZnMgO electron transport layer (ETL) under consecutive voltage sweeps. In contrast, the efficiency increases for ZnO ETL device. By analyzing the electrical characteristics of both devices and surface traps of ZnMgO and ZnO nanoparticles, we found the efficiency drop of ZnMgO device is related to the hole leakage mediated by trap state on ZnMgO nanoparticles. For ZnO device, the efficiency raise is due to suppressed electron leakage. The hole leakage also causes rapid lifetime degradation of ZnMgO device. However, the efficiency and lifetime degradation of ZnMgO device can be eliminated with shelf aging. Our work reveals the distinct voltage sweep behavior of QLED based on different ETLs and may help to understand the lifetime degradation mechanism in QLED.