A thin-film transistor (TFT) array substrate includes a transistor disposed on a base substrate and a storage capacitor electrically connected to the transistor. The transistor includes a gate electrode, an active layer electrically insulated from the gate electrode, the active layer including a semiconductor material, and a first electrode and a second electrode disposed to be spaced apart from each other on the active layer. The storage capacitor includes a lower electrode including a light inflow path, and an upper electrode disposed to face the lower electrode and electrically connected to the second electrode.