Luminescence Characteristics And Emission Process Of A New Efficient Red Phosphorescent Material Irf

ABSTRACT:The organic phosphorescent OLED has been widely researched because its inner quantum efficiency can reach100%, but there is unclear of the internal luminescence mechanism and process, so the further research is needed. Therefore, to research the carriers inject, transfer, trap and emitting process inside the phosphorescence organic light-emitting devices (PhOLED) is important for improving the efficiency and performance indicators constitutionally.Firstly, in this paper, we set up a transient EL and delay electroluminescence measurement system, and first time use this measurement system studied the internal luminescence mechanism and progress of PhOLED. In those studies we first fabricated a series PhOLED which used one kind of new efficient red-emitting iridium(III) complexes (Bis[2-(9,9-dimethyl-9H-flouren-2-yl)benzothiazolato-N,C2’]iridium(III)(acetylacetona te)) doped with TAZ as the emitting layer.(1) We found that the object materials molecules as traps trap carriers in those samples which with the different host material doped object material as the luminescent materials, and the accumulated charge carriers and trapped charge carriers induce the transient overshoot in transient luminescence measurement.(2) For this host doped object system, the hole-blocking layer (HBL) seriously influence the luminescence mechanism, and energy transfer especially. In those devices which TAZ doped Irf as the emitting layer, the object Irf molecules trapped holes and electrons directly and luminescence, not from the energy transfer from host material molecules to Irf molecules when without HBL, at this time hole always transfer in Irf molecules and electrons transfer in the TAZ molecules. But in the devices with the HBL, luminescence derived from the energy transfer from host to object.(3) We also found that the carrier transport and exciton formation processes change with the EML thickness, the energy transfer more fully with the EML thicker, the emitting-light from the object Irf trapped carriers directly and not from the host-object energy transfer when the EML is thinner.(4) We proved that the transient EL and delay electroluminescence measurement system is an effectively way to research the carriers inject, transfer, trap and the energy transfer or TTA in the EML.Secondly, we fabricated a sample which the highest current efficiency and luminescence intensity reach14cd/A and8200cd/cm2respectively when the doping concentrate is10%in mass ratio, and the thickness of EML and HBL is30-40nm,20-30nm respectively and CBP as the host materials.