Embodiments of the present disclosure relate to a thin film transistor, a method for manufacturing the same, a display panel, and a display device. The thin film transistor includes a substrate, an active layer located on the substrate, and a light shielding layer, a first dielectric layer, and a second dielectric layer located between the substrate and the active layer, wherein the first dielectric layer is located between the second dielectric layer and the substrate, and wherein a refractive index of the first dielectric layer is greater than a refractive index of the second dielectric layer.