Thin film transistor and fabricating method thereof, array substrate and display device

1. A thin film transistor, comprising:

a substrate base;

a first gate electrode at a side of the substrate base;

an active layer at a side of the first gate electrode away from the substrate base;

a second gate electrode at a side of the active layer away from the substrate base;

a source/drain electrode at a side of the second gate electrode away from the substrate base, wherein an orthographic projection of the source/drain electrode on the substrate base is at least partially overlapped with an orthographic projection of the second gate electrode on the substrate base;

a buffer layer at a side of the first gate electrode away from the substrate base;

a gate insulating layer at a side of the active layer away from the substrate base; and

an interlayer dielectric layer at a side of the second gate electrode away from the substrate base, and a connection electrode at a side of the interlayer dielectric layer away from the substrate base, wherein:

the buffer layer comprises a first via hole penetrating through the buffer layer, and an orthographic projection of the first via hole on the substrate base is at least partially overlapped with an orthographic projection of the first gate electrode on the substrate base;

the interlayer dielectric layer comprises a second via hole and a third via hole penetrating through the interlayer dielectric layer, an orthographic projection of the second via hole on the substrate base is at least partially overlapped with the orthographic projection of the active layer on the substrate base, an orthographic projection of the third via hole on the substrate base covers the orthographic projection of the first via hole on the substrate base, and the orthographic projection of the third via hole is at least partially overlapped with the orthographic projection of the second gate electrode; and

the connection electrode is electrically connected to the first gate electrode through the first via hole and the third via hole, and is electrically connected to the second gate electrode through the third via.

2. The thin film transistor according to claim 1 , wherein an orthographic projection of the first gate electrode on the substrate covers an orthographic projection of the active layer on the substrate base.

3. The thin film transistor according to claim 1 , wherein the active layer comprises a metal oxide semiconductor material.

4. The thin film transistor according to claim 1 , wherein the connection electrode comprises a transparent conductive material.

5. The thin film transistor according to claim 1 , further comprising:

a passivation layer at a side of the source/drain electrode away from the substrate base; and

a light shielding layer at a side of the passivation layer away from the substrate base, the light shielding layer being configured to absorb and/or reflect ambient light.

6. An array substrate comprising:

a thin film transistor, comprising:

a substrate base, a first gate electrode at a side of the substrate base, an active layer at a side of the first gate electrode away from the substrate base, a second gate electrode at a side of the active layer away from the substrate base, a source/drain electrode at a side of the second gate electrode away from the substrate base, wherein an orthographic projection of the source/drain electrode on the substrate base is at least partially overlapped with an orthographic projection of the second gate electrode on the substrate base, a buffer layer at a side of the first gate electrode away from the substrate base, a gate insulating layer at a side of the active layer away from the substrate base, and an interlayer dielectric layer at a side of the second gate electrode away from the substrate base, and a connection electrode at a side of the interlayer dielectric layer away from the substrate base;

wherein the buffer layer comprises a first via hole penetrating through the buffer layer, and an orthographic projection of the first via hole on the substrate base is at least partially overlapped with an orthographic projection of the first gate electrode on the substrate base;

wherein the interlayer dielectric layer comprises a second via hole and a third via hole penetrating through the interlayer dielectric layer, an orthographic projection of the second via hole on the substrate base is at least partially overlapped with the orthographic projection of the active layer on the substrate base, an orthographic projection of the third via hole on the substrate base covers the orthographic projection of the first via hole on the substrate base, and the orthographic projection of the third via hole is at least partially overlapped with the orthographic projection of the second gate electrode; and

wherein the connection electrode is electrically connected to the first gate electrode through the first via hole and the third via hole, and is electrically connected to the second gate electrode through the third via; and

a photosensitive element at a side of the source/drain electrode of the thin film transistor away from the substrate base, wherein a first electrode of the photosensitive element is connected with one of the source/drain electrode of the thin film transistor.

7. The array substrate according to claim 6 , further comprising a leading-out layer at a side of the photosensitive element away from the substrate base,

wherein a second electrode of the photosensitive element is connected to the leading-out layer.

8. The array substrate according to claim 7 , further comprising a conductive layer in the same layer as the second gate electrode in the thin film transistor,

wherein the conductive layer is connected to the leading-out layer, and

an orthographic projection of the conductive layer on the substrate base is at least partially overlapped with an orthographic projection of the source/drain electrode of the thin film transistor on the substrate base.

9. The array substrate according to claim 8 , further comprising a connection layer in the same layer as the source/drain electrode of the thin film transistor,

wherein the conductive layer is connected to the leading-out layer through the connection layer.

10. The array substrate according to claim 6 , wherein the array substrate is implemented in a display device.

11. A fabricating method of a thin film transistor comprising:

providing a substrate base;

forming a first gate electrode at a side of the substrate base;

forming an active layer at a side of the first gate electrode away from the substrate base;

forming a second gate electrode at a side of the active layer away from the substrate base; and

forming a source/drain electrode at a side of the second gate electrode away from the substrate base, wherein an orthographic projection of the source/drain electrode on the substrate base is at least partially overlapped with an orthographic projection of the second gate electrode on the substrate base, and forming the active layer at the side of the first gate electrode away from the substrate base comprises:

forming a buffer layer at a side of the first gate electrode away from the substrate base, in which the buffer layer comprises a first via hole penetrating through the buffer layer, and an orthographic projection of the first via hole on the substrate base is at least partially overlapped with the orthographic projection of the first gate electrode on the substrate base; and

forming an active layer at a side of the buffer layer away from the substrate base.

12. The method according to claim 11 , further comprising:

forming a passivation layer at a side of the source/drain electrode away from the substrate base; and

forming a light shielding layer at a side of the passivation layer away from the substrate base, the light shielding layer being configured to absorb and/or reflect ambient light.

13. The method according to claim 11 , wherein forming the source/drain electrode at the side of the second gate electrode away from the substrate base comprises:

forming an interlayer dielectric layer at a side of the second gate electrode away from the substrate base, in which the interlayer dielectric layer comprises a second via hole and a third via hole which penetrate through the interlayer dielectric layer, an orthographic projection of the second via hole on the substrate base is at least partially overlapped with an orthographic projection of the active layer on the substrate base, and an orthographic projection of the third via hole on the substrate base covers the orthographic projection of the first via hole on the substrate base; and

forming a source/drain electrode and a connection electrode at a side of the interlayer dielectric layer away from the substrate base, in which the connection electrode is electrically connected to the first gate electrode through the first via hole and the third via hole and is electrically connected to the second gate electrode through the third via hole.