Hihghly Efficient White Organic Light Emitting Devices Based On New Host/Dopant Materials

White Organic Light-Emitting Devices （WOLEDs） are of great significance due totheir potentials as a promising technology for the next generation light source/displaytechnology. Among the three primary colors RGB compounded white light,performance of organic blue emitting materials based devices are still below therequirements for applications on solid state lightings and displays. In this work, a seriesof new host/dopant materials have been designed, synthesized and investigated. Theseemitting materials based devices exibit considerable performance, which could promotethe improvement of OLEDs technology.1. A new multifunctional host material DFBC has been designed, synthesized andcharacterized. DFBC was found to have good morphological and thermal stability witha high glass transition temperature of192℃and a decomposition temperature of480℃.The quinoline and9-phenylcarbazole groups also endow the compound with goodcharge transport property. Triplet energy of DFBC is determined to be2.33eV, which isconsiderably higher than those of other commonly used blue fluorescent materials andphosphorescent orange/red emitters. The PL quantum efficiency in CH₂Cl₂solution wasmeasured to be0.73. A non-doped tri-layer blue fluorescent device based on DFBCshows a deep blue emission with a Commission Internationale de L’Eclairagecoordinates of （0.16,0.10） and an emission peak of448nm. Maximum powerefficiency of the device is1.1lm/W. An orange phosphorescent device using DFBC as ahost in conjunction with an iridium complex as dopant exhibits a maximum powerefficiency of21.0lm/W, which is much higher than that of a CBP-based control device（11.5lm/W） with the same device structure. Furthermore, by using DFBC as a blueflorescent emitter and a host for phosphorescent dopant, a white emitting OLED with amaximum power efficiency of22.5lm/W and CIE coordinates of （0.38,0.33） wereobtained. The results indicate that DFBC is a high performance versatile material for theuse in F/P WOLEDs.2. A new blue-emitting iridium complex Ir（tfpd）2pic has been designed,synthesized and used to fabricate blue phosphorescent organic light-emitting devices with a efficiency up to41.4lm/W （52.6cd/A）. Even at a luminance of1000cd/m², thepower efficiency and current efficiency of the blue device are still as high as25.2lm/Wand43.8cd/A, respectively. Furthermore, by combining the blue phosphorescence ofIr（tfpd）2pic and the yellow emission of Ir（npy）₂acac, highly efficient white emissionwith a maximum efficiency of49.0lm/W （54.5cd/A） has been achieved. Theefficiencies of Ir（tfpd）2pic based blue/white devices are amoung the best reportedvalues.3. A series of deep-red emitters containing new ancillary ligands have also beendesigned and synthesized. The five materials were doped into CBP to fabricate standardphosphorescent devices with emission peaks centred at600-650nm, and the efficiencyroll-off was not very clear in these devices. Notably, for a bebq2:5%Ir（piq）2bop device,deep-red OLEDs with a luminous efficiency of9.1lm/W （10.3cd/A） can be obtained at100cd/m², along with a Commission de L’Eclairage1931chromaticity coordinates of（0.67,0.33） and a emission peak of624nm. More importantly, we found anextrapolated lifetime of over30000h for the benchmark luminance of100cd/m². Theresult is better than Ir（piq）₃based device when using the same device structure.Due to such a high performance of these new host/dopant materials, this work maybe of great importance for the WOLEDs technology.