An organic light-emitting diode (OLED) is provided. The OLED comprises a substrate, a first electrode on the substrate, a second electrode disposed opposite to the first electrode, an emission layer disposed between the first electrode and the second electrode, a hole migration region disposed between the first electrode and the emission layer, and an electron migration region disposed between the emission layer and the second electrode. The hole migration region comprises a tertiary amine having one N-substituent comprising a substituted or unsubstituted carbazole moiety and another N-substituent comprising a substituted or unsubstituted fluorene moiety. At least one of the hole migration region and the emission layer comprises a substituted or unsubstituted compound comprising at least two carbazole moieties.