This study focused on the characteristics of solution-processed phosphorescent organic light-emitting diodes (PHOLEDs) by using a small molecular carbazole derivative, 3,6-di(9-carbazolyl)-9-(2-ethylhexyl)carbazole (TCz1) which has side chains for solubility in organic solvent and high triplet level as a host material for the PHOLEDs. The device with fac-tris(2-phenylpyridine) iridium(III) doped in TCz1 emitted green light, and showed the maximum luminance of approximately 25,000 cd/m(2). Blending hole transport material into emissive layer, carrier balance factor in the device was optimized and the maximum current and the external quantum efficiency of 23 cd/A and 6.8% were achieved.