The Preparation And The Electroluminescence Of The Multilayer Devices Based On Quantum Dots

Quantum-dot light emitting diodes (QLEDs) exhibit several advantages such as the narrow emission line width, the easier tunability of color emission in the whole visible regime by tuning the particle size and shape, and the significantly lower emitter cost for QLEDs compared with organic phosphorescent emitters. According to those characteristics, QLEDs have been regarded as a significant candidate for the next-generation solid-state lighting and displays.In this paper, firstly we use QDs as electron transport layer(ETL), and it improves the performance of the OLED device with MEH-PPV as light-emitting layer. But because QDs have their own light, the color purity of the device have been influenced; Then we prepared the laminated device with MEH-PPV/QDs as the repeat unit, the device will have better luminous brightness as a result; The anode modification of PEDOT:PSS and the cathode modification of PFN or LiF will have better performance in the device with QDs as light emitting layer.We choose a water soluble barrier layer of PFN spin-coated between each QD layer to prevent the dissolving of front QDs layer by coating the next QDs layer, then we use red, green and blue QDs to prepare white light device and when the voltage is 9V, the light color of the device is closest to white light; The exciton recombination zone of five QD monolayer films was investigated, the exciton recombination zone is adjacent to ITO. In addition, the selection of different barrier layer can also change the position of the exciton composite.Finally we tried to introduce some organic hole transporting layer (HTL) to balance the charge injection with the device structure of ITO/(PEDOT:PSS)/QDs (R4B1)/LiF/AL. The HTLs we choose are PVK, NPB, CBP and poly-TPD, although the HTLs have close LUMO energy levels, they can improve the device brightness in different degree. The barrier height for charge injection cannot be contributed to the significant decrease in current density, while the hole mobility might be a possible influencing factor.