We have synthesized a novel diamine compound (DCA) containing carbazole groups. The compound has an electron-transport ability and a high thermal stability, and a high ionization potential (Ip). Green-emitting electroluminescent (EL) devices with the compound as a hole-blocking material have been fabricated. The luminance of the device achieved 10000 cd/m(2) and the EL efficiency was improved. Devices capable of emitting bright green, blue, or red emissions with DCA as an electron-transport layer have been fabricated.