The present disclosure provides a thin film transistor, a method for manufacturing the thin film transistor, an array substrate and a display panel. The thin film transistor includes: a substrate; and a gate electrode, a gate insulating layer, an active layer, a source electrode and a drain electrode on the substrate, wherein the active layer includes a first semiconductor layer and a second semiconductor layer sequentially arranged in a direction perpendicular to the substrate, the second semiconductor layer is arranged on a side of the first semiconductor layer away from the gate electrode; an absolute value of a difference between conduction band minimums of a first oxide material and a second oxide material is greater than 0.2 eV.