A thin film transistor (TFT) array substrate is provided that includes a TFT on a substrate. The TFT can include an active layer, gate electrode, source electrode, drain electrode, first insulating layer between the active layer and the gate electrode, and second insulating layer between the gate electrode and the source and drain electrodes. A pixel electrode is disposed on the first and second insulating layers. A capacitor including a lower electrode is disposed on a same layer as the gate electrode and an upper electrode. A third insulating layer directly between the second insulating layer and the pixel electrode and between the lower electrode and the upper electrode. A fourth insulating layer covers the source electrode, the drain electrode, and the upper electrode, and exposes the pixel electrode and can further expose a pad electrode.