The Fabrication And Reasearch Of Warm White Organic Light-Emitting Diodes

Phosphorescent materials can utilize both singlet and triplet excitons and realize theoretically 100%internal quantum efficiency.Therefore,they are regarded as the most potential class of organic electroluminescent materials.White light organic light-emitting diodes?WOLEDs?have attracted wide attention as backlighting sources for flat panel displays and potential applications in solid-state lighting.However,there are few reported on all-phosphor materials WOLEDs with good comprehensive performance.Therefore,based on the phosphorescent materials of red,green and blue iridium complexes,a series of white light devices with three luminescent layers were designed and prepared in this paper.The specific research work is as follows:1.Red phosphor material?PQ₂Ir?dpm??was selected as luminescent material,and a series of single or double light-emitting layer?s?devices were designed and fabricated.The dependence of device performances on the doping concentration of the luminescent materials,the thickness of each functional layer and the ladder layer studied in detail.Finally,the optimal device displayed the performances as follows:the maximum brightness of 85740cd/m²,the maximum external efficiency of 19.3%,the maximum current efficiency of 54.04cd/A,the maximum power efficiency of 49.99 lm/W.2.In this work,Iridium complex?Ir?ppz?₃?with higher energy levels was selected as hole sensitizer.The relatively higher HOMO level of Ir?ppz?₃ is helpful in trapping holes,thus not only delay the transport of the holes but also balance the distribution of carriers within light-emitting layer.Consequently,device performances were significantly improved.The current efficiency of the sensitized monolayer increased from 38.31 cd/A to 45.70 cd/A.3.Based on the optimization of devices obtained by co-doping red phosphor?PQ₂Ir?dpm??with blue?FIrpic?or green?Ir?mppy?₃?phosphor into host material as light-emitting layer,a series of WOLEDs with three light-emitting layers were designed and fabricated.The best performance white device with maximum external quantum efficiency,brightness and current efficiency of 32.1%,75640 cd/m² and 65.51 cd/A,respectively.The color coordinate?0.383,0.399?is located in the warm white area.