Recent Progress in Organic Light-Emitting Devices

Recent development in high performance organic light-emitting devices (OLEDs) will be discussed. A variety of wide-energy-gap charge transport materials have been prepared and used for phosphorescent OLEDs. For instance, 1,3,5-tris[3,5-bis(3-pyridinyl)-phenyl]benzene (TPPB) was synthesized and used as an electron transport layer. A high power efficiency of 37 lm/W was achieved for blue OLED using iridium(III )-bis[2-(4,6-difluorophenyl)pyridinate-N, C^2´]picolinate (FIrpic) as an emitter. Long lifetime has been achieved by using the tandem structure, so called multiphoton emission (MPE) structure. A long lifetime such as over 100,000 hrs at 1000 cd/m² has been achieved for an amber OLED. A white OLED exhibited over 30,000 hrs lifetime with the initial luminance of 5000 cd/m², which promises that OLEDs can be used not only for displays, but also for general lighting.