A thin-film transistor (TFT) array substrate includes an active layer on a substrate and a lower electrode of a capacitor on the same level as the active layer, a first insulation layer on the active layer and the lower electrode and having a first gap exposing an area of the lower electrode; a gate electrode of the TFT on the first insulation layer, and an upper electrode of the capacitor on the lower electrode and the first insulation layer, the upper electrode having a second gap that exposes the first gap and a portion of the first insulation layer; a second insulation layer disposed between the gate electrode and source electrode and drain electrodes, and not disposed on the upper electrode, in the first gap of the first insulation layer, or in the second gap of the lower electrode.