The present invention relates to an organic photoelectric device and a material used therein. The organic photoelectric device includes a substrate, an anode disposed on the substrate, a hole transport layer (HTL) disposed on the anode, an emission layer disposed on the hole transport layer (HTL), and a cathode disposed on the emission layer. The emission layer is characterized in that it includes a host and a phosphorescent dopant, and the host has a difference between the reduction potential or oxidation potential of the host and the reduction potential or oxidation potential of the phosphorescent dopant of less than 0.5eV. The organic photoelectric device according to the present invention is capable of accomplishing higher efficiency and a lower driving voltage than those of the conventional organic photoelectric device, and has a simplified structure resulting in saving of manufacturing cost.