Efficient organic light-emitting devices using an iridium complex as a phosphorescent host and a platinum complex as a red phosphorescent guest

We demonstrated efficient organic light-emitting devices (OLEDs) using a phosphorescent host/guest system consisting of bis(2-phenylpyridinato-N,C-2')iridium(acetylacetonate) [(ppy)(2)Ir(acac)] as a host and a platinum complex (Pt-SA-1) as a guest. The OLED using (ppy)(2)Ir(acac) film doped with Pt-SA-1 (1 wt %) showed an ideal red emission via efficient energy transfer from the host to the guest. The external quantum efficiency of the device was as high as 8.3%. The driving voltage was significantly reduced compared with a device using a conventional host of 4,4(')-di(carbazole-9-yl)biphenyl, which resulted from the enhancement of the hole injection from the hole-transport layer to the host.