Display device

1. A display device comprising: a first transistor, the first transistor including: an oxide semiconductor layer; a first gate electrode facing the oxide semiconductor layer; and a gate insulating layer between the oxide semiconductor layer and the first gate electrode, wherein the first gate electrode has hydrogen storage properties, the first gate electrode includes a first conductive layer, a second conductive layer having a lower resistance than the first conductive layer, and a third conductive layer having hydrogen storage properties, the second conductive layer is arranged between the first conductive layer and the third conductive layer, and the first conductive layer, the second conductive layer and the third conductive layer respectively have a tapered shape having an inclined plane facing upward.

2. The display device according to claim 1 , wherein the third conductive layer is further from the oxide semiconductor layer than the first conductive layer, and a thickness of the third conductive layer is less than a thickness of the first conductive layer.

3. A display device comprising: a first transistor, the first transistor including: an oxide semiconductor layer; a first gate electrode facing the oxide semiconductor layer; and a gate insulating layer between the oxide semiconductor layer and the first gate electrode, wherein the first gate electrode has hydrogen storage properties, the first gate electrode includes a first conductive layer and a second conductive layer having a lower resistance than the first conductive layer, the first conductive layer and the second conductive layer respectively have a tapered shape having an inclined plane facing upward, the first gate electrode includes a fourth conductive layer having hydrogen storage properties, and the fourth conductive layer covers an upper surface and a side surface of the second conductive layer.

4. The display device according to claim 1 , wherein the fourth conductive layer covers an upper surface and a side surface of the first conductive layer, and is in contact with the first gate insulating layer.

5. The display device according to claim 2 , wherein the first gate electrode includes a fourth conductive layer having hydrogen storage properties, and the fourth conductive layer covers an upper surface of the third conductive layer and a side surface of the second conductive layer.

6. The display device according to claim 5 , wherein the fourth conductive layer covers an upper surface and a side surface of the first conductive layer, and is in contact with the first gate insulating layer.

7. A display device comprising: a first transistor, the first transistor including: an oxide semiconductor layer; a first gate electrode facing the oxide semiconductor layer; and a gate insulating layer between the oxide semiconductor layer and the first gate electrode, wherein the first gate electrode includes a first conductive layer capable of forming a metal hydride on a surface of the first conductive layer, a second conductive layer having a lower resistance than the first conductive layer, and a third conductive layer having hydrogen storage properties, the second conductive layer is arranged between the first conductive layer and the third conductive layer, and the first conductive layer, the second conductive layer and the third conductive layer respectively have a tapered shape having an inclined plane facing upward.

8. The display device according to claim 7 , wherein the third conductive layer is further from the oxide semiconductor layer than the first conductive layer, and a thickness of the third conductive layer is less than a thickness of the first conductive layer.

9. A display device comprising: a first transistor, the first transistor including: an oxide semiconductor layer; a first gate electrode facing the oxide semiconductor layer; and a gate insulating layer between the oxide semiconductor layer and the first gate electrode, wherein the first gate electrode includes a first conductive layer capable of forming a metal hydride on a surface of the first conductive layer, the first gate electrode includes a second conductive layer having a lower resistance than the first conductive layer, the first conductive layer and the second conductive layer respectively have a tapered shape having an inclined plane facing upward, the first gate electrode includes a fourth conductive layer having hydrogen storage properties, and the fourth conductive layer covers an upper surface and a side surface of the second conductive layer.

10. The display device according to claim 9 , wherein the fourth conductive layer covers an upper surface and a side surface of the first conductive layer, and is in contact with the first gate insulating layer.

11. The display device according to claim 7 , wherein the first gate electrode includes a fourth conductive layer having hydrogen storage properties, and the fourth conductive layer covers an upper surface of the third conductive layer and a side surface of the second conductive layer.

12. The display device according to claim 11 , wherein the fourth conductive layer covers an upper surface and a side surface of the first conductive layer, and is in contact with the first gate insulating layer.

13. The display device according to claim 8 , further comprising: a display region displaying an image; and a peripheral region surrounding the display region, wherein a plurality of pixel circuits are provided in the display region, a driver circuit configured to drive the plurality of pixel circuits is provided in the peripheral region, the first transistor is included in a pixel circuit provided in a pixel, and a second transistor is included in the driver circuit.