Display device

An organic light emitting display (OLED) device, comprising:

• a substrate including a sub-pixel region and a transparent region;
• a buffer layer in the sub-pixel region and the transparent region on the substrate, the buffer layer having a first refractive index;
• a first gate insulation layer in the sub-pixel region and the transparent region on the buffer layer, the first gate insulation layer including the same material with the buffer layer;
• an active layer between the buffer layer and the first gate insulation layer;
• a first gate electrode on the first gate insulation layer under which the active layer is disposed;
• a first insulating interlayer in the sub-pixel region and the transparent region on the first gate insulation layer, the first insulating interlayer having a second refractive index that is greater than the first refractive index;
• a second gate insulation layer in the sub-pixel region and the transparent region between the first gate insulation layer and the first insulating interlayer;
• a second gate electrode interposed between the second gate insulation layer and the first insulating interlayer;
• source and drain electrodes on the first insulating interlayer, the source and drain electrodes defining a semiconductor element together with the active layer and the first gate electrode;
• and
• a pixel structure on the semiconductor element, the pixel structure being electrically connected to the semiconductor element.