2. The researchers in the chemical owner's solid-state room used high-quality CdSe/ZnS and CdSe/CdS/ZnS nanocrystalline quantum dots with core-shell structure prepared by American Ocean Nanotechnology Company. At the same time, poly-TPD is used as hole transport layer and aluminum octahydroxyquinoline (Alq3) is used as electron transport layer. By adjusting the size of quantum dots, optimizing the device structure and the thickness of each layer, QLED devices with four colors of red, orange, yellow and green were fabricated, and their maximum brightness reached 9064 (red light), 3200 (orange light), 4470 (yellow light) and 3700 (green light) cd/m2 respectively, which was the highest value reported in QLED literature. At the same time, these QD light-emitting diodes also have lower starting voltage (3-4V), improved efficiency (1. 1-2.8 cd/A), high color purity (the half-maximum width of electroluminescent spectrum is about 30nm) and long working life.
3.QD-LED has a device structure similar to polymer light emitting diode (PLED) and can be processed in solution. Its luminescent layer is made of colloidal solution of semiconductor quantum dots (QDs) by spin coating, so it has the same advantages as PLED, such as simple preparation process, low cost and flexible devices. At the same time, compared with PLED, QD-LED has the outstanding advantages of high luminous color purity (narrow half-peak width) and adjustable luminous color by controlling the size of quantum dots. In addition, QD light emitting diode is also an important application field of semiconductor nanocrystals. Therefore, the research of QD light emitting diodes has attracted great attention of thin film electroluminescent devices and semiconductor nanocrystals researchers.