Study On White Light Quantum Dot LED Based On ZnO As Electron Transport Layer

QDs (Colloidal Quantum Dots) have high fluorescence efficiency、good monochrome performance、wavelength can be regulated and high stability, etc.. It have the potential to replace the conventional organic or inorganic luminescent materials become the core portion of the next generation LED devices. At present, domestic and foreign scholars have a lot of research on QD-LEDs devices, but very few reports on white QD-LEDs devices.In this thesis, the QD-LEDs were prepaid which structure is ITO/TPD:PVK/ QDs+PEDOT/ZnO/LiF/Al. PEDOT:PSS is used as shield layer, colloid ZnO is used as Electron-transport Layer. Then test the performance of them.First, we studied the influence of surface treatment on ITO film, found the work function of ITO film can be improved by immersion in mixed solution of deionized water, ammonia, hydrogen peroxide, which volume ratio is 5:1:1, thereby reducing the turn-on voltage. The turn-on voltage of devices after processing is reduced about 22%.Secondly, Quantumn Dot LED with ZnO Electron-transport layer has been prepared. The new method of multi-layer Quantumn Dot by only sol-gel process can achieve white light. The influence of technological parameter such as mass ratio of TPD and PVK, and the density of quantum dot had been analyzed. The results show that when the mass ratio of TPD and PVK is 5:1, the density of QD is 1.0mg/ml, and using ZnO as Electron-transport layer, the brightness of device can reaches 1500cd/m2 at 15V, CIE is (0.3819,0.4025), color rendering index is 93.5. Device glowing in specific shape of letters was been achieved by using wet etching.Finally, we prepared the CNT conductive film by spraying method and investigated the surface properties of it, which structure is CNT-TCFs/TPD:PVK/QD/ Alq3/LiF/Al. The white light can be achieved by adjust density of QD andthe current density and the bright of device will increase with the augment of QD’density.The flatness of CNT-TCFs is optimized after modify by TPD:PVK, which lead to improvement of the luminescence performance. When the mass ratio of TPD and PVK is 1:1, QD-LEDs have best characteristics of luminescence.