Thin film transistor, manufacturing method thereof, array substrate and display panel

A method for manufacturing a thin film transistor, comprising:

• forming a gate electrode, a gate insulating layer, an active layer, a source electrode and a drain electrode on a substrate,
• wherein the active layer comprises 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;
• the first semiconductor layer comprises a first oxide material, and the second semiconductor layer comprises a second oxide material;
• the first oxide material has an electron mobility higher than that of the second oxide material;
• and
• the first oxide material has a conduction band minimum lower than that of the second oxide material, and an absolute value of a difference between the conduction band minimum of the first oxide material and the conduction band minimum of the second oxide material is greater than 0.2 eV,
• wherein the active layer further comprises a third semiconductor layer on a side of the second semiconductor layer away from the gate electrode;
• the third semiconductor layer comprises a crystalline oxide material;
• and
• an absolute value of a conduction band minimum of the crystalline oxide material is greater than that of the conduction band minimum of the second oxide material;
• and
• the crystalline oxide material comprises crystalline IGZO (136) with an atomic ratio of In:Ga:Zn being 1:3:6 to improve physical blocking characteristics for preventing H and O elements in its adjacent layer from affecting the active layer.