A thin film transistor includes a substrate and a gate electrode disposed over the substrate. The gate electrode includes a center part and a peripheral part configured to at least partially surround the center part. The thin film transistor further includes a gate insulating layer disposed below the gate electrode and a first electrode insulated from the gate electrode by the gate insulating layer. The first electrode has at least a portion thereof overlapping the center part. The thin film transistor additionally includes a spacer disposed below the first electrode and a second electrode insulated from the first electrode by the spacer. The second electrode has at least a portion thereof overlapping the peripheral part. The thin film transistor further includes a semiconductor layer connected to the first and second electrodes, and insulated from the gate electrode by the gate insulating layer.