A thin film transistor, comprising a substrate, an active layer disposed on the substrate, and a source and drain that make electrical contact with the active layer, wherein the source and drain each comprise a first sub-electrode and a second sub-electrode that are stacked along a thickness of the active layer, and the first sub-electrode is closer to the active layer relative to the second sub-electrode. An area of an overlapping region between an orthographic projection of the second sub-electrode of at least one of the source and drain on the substrate and an overlapping region between an orthographic projection of the first sub-electrode of the at least one of the source and the drain on the substrate and the orthographic projection of the active layer on the substrate.