A thin-film transistor (“TFT”) array substrate includes: a TFT including an active layer, a gate electrode, a source electrode, a drain electrode, a first insulating layer disposed between the active layer and the gate electrode, and a second insulating layer disposed between the gate electrode, and the source and drain electrode; a pixel electrode including a transparent conductive oxide and disposed in an opening defined in the second insulating layer; a capacitor including a first electrode disposed on a layer on which the active layer is disposed, and a second electrode disposed on a layer on which the gate electrode is disposed; a pad electrode disposed on the second insulating layer and including a material substantially the same as a material in the source electrode and the drain electrode; a first protective layer disposed on the pad electrode; and a second protective layer disposed on the first protective layer.