Driving thin-film transistor and organic light-emitting display device using the same

An organic light-emitting display device comprising:

• a substrate including a plurality of sub-pixels;
• a driving thin-film transistor disposed in each sub-pixel among the plurality of sub-pixels and including:
• a first active layer disposed on the substrate and including a first protruding portion,
• a second active layer overlapping with the first active layer and including a second protruding portion located at a different position than the first protruding portion,
• a first gate electrode disposed between the first active layer and the second active layer,
• a source electrode connected to the first protruding portion of the first active layer, and
• a drain electrode connected to the second protruding portion of the second active layer;
• a switching thin-film transistor connected to the driving thin-film transistor in each sub-pixel among the plurality of sub-pixels and including:
• a second gate electrode in the same layer as the first gate electrode,
• a second source electrode and a second drain electrode in the same layer as the first source electrode of the driving thin-film transistor and the first drain electrode of the driving thin-film transistor, and
• a third active layer in the same layer as the first active layer of the driving thin-film transistor or the second active layer of the driving thin-film transistor;
• and
• an organic light-emitting diode connected to the first source electrode or the first drain electrode.