The Optimization Of Functional Layers Of Quantum Dot Light Emitting Diodes

In recent years,colloidal quantum dots?QDs?have showed great perpormance in light emitting diodes?LEDs?,lasers and solar cells.The wide application of QDs is mainly attributed to their unique properties,such as high thermal stability,pure luminescence spectrum,tunable wavelength and high luminous efficiency.Quantum dot light emitting diodes?QD-LEDs?are considered as one of the most competitive technologies in the next generation of display technology due to their high brightness,high color rendering index and variable wavelength.Electrodes,carrier transport layers and light emitting layers,all are components of QD-LED,will influence the luminous properties of QD-LEDs.The main contents of this work include:1.Optimization of PEDOT:PSS thin film conducting electrode:The effects of different treatments?droping and dipping of ethylene glycol?on the conductivity of PEDOT:PSS films were investigated.Two samples were prepared by experiments and the results found that the performance of films with dipping method were better.Next,on the basis of dipping method,we prepared PEDOT films with different dipping temperature and different dipping time,and found that the PEDOT films showed the best conductivity and great environmental stability when the dipping temperature is 110?and dipping time is 10min.Last,experiments of the multilayer film was studied,showing that the conductivity and stability were improved as the film thickness increased.2.Effect of mixed hole transport materials on the performance of QD-LEDs. QD-LED devices with Poly-TPD and PVK were prepared by spin coating and evaporation.Results showed that when the mass ratio of Poly-TPD and PVK is 1:1,the devices had the highest luminous intensity thanks to the deep HOMO energy level of PVK and high hole mobility of Poly-TPD,which made hole injection and transmission more effective,improving the electron and hole composite efficiency.3.Optimization of the properties of mixed formamidinium?FA?and methylammonium?MA?lead bromide perovskite LEDs.The FA_1-xMA_xPbBr₃nanocrystals were prepared at room temperature,and results showed that as the molar ratio of MA increased,the size of mixed nanocrystals became smaller and the PL emission peak appeared 2nm red shift.At the same time,the FA_1-xMA_xPbBr₃ perovskite LED devices were fabricated.we found that the conversion efficiency of perovskite LEDs became higher with the doping of MA due to the longer hole diffusion length of MAPbBr₃ compared to FAPbBr₃,which ensures that holes and electrons can combine more effectively.