Display device, method of manufacturing the same and tiled display device including the same

A display device comprising:

• a first substrate having a display area and a non-display area adjacent to the display area, the first substrate including a first contact hole in the display area;
• a first barrier insulating layer disposed on the first substrate and including second contact holes overlapping the first contact hole in the display area;
• pad electrodes disposed on the first barrier insulating layer, at least a subset of the pad electrodes being disposed in the second contact holes;
• a display layer disposed on the pad electrodes, the display layer including pixels in the display area;
• and
• a flexible film disposed below the first substrate and electrically connected to the pad electrodes through the first contact hole and the second contact holes,
• wherein the first substrate includes a substrate buffer portion overlapping the first contact hole in the display area and not-overlapping the second contact holes in the display area,
• wherein a first thickness of the substrate buffer portion is smaller than a second thickness of the first substrate that does not overlap the first contact hole, and
• wherein the substrate buffer portion is surrounded along its periphery by the first substrate having the second thickness.