Display device

1. A display device comprising:

a substrate;

a transistor disposed on the substrate;

a pixel electrode connected to the transistor;

a bank layer disposed on the pixel electrode and defining a pixel opening overlapping the pixel electrode;

an emission layer disposed in the pixel opening;

a common electrode disposed on the emission layer and the bank layer;

an encapsulation layer disposed on the common electrode;

a sensing electrode disposed on the encapsulation layer;

a first insulating layer disposed on the encapsulation layer and overlapping the pixel opening;

a second insulating layer disposed on the first insulating layer; and

a third insulating layer surrounding the first insulating layer,

wherein a refractive index of the first insulating layer, a refractive index of the second insulating layer, and a refractive index of the third insulating layer are different from one another,

the refractive index of the first insulating layer is greater than the refractive index of the third insulating layer, and

a maximum thickness of the third insulating layer is greater than a maximum thickness of the first insulating layer in a direction perpendicular to a main plane extension direction of the substrate so that a maximum height of the third insulating layer from the substrate is greater than a maximum height of the first insulating layer from the substrate.

2. The display device of claim 1 , wherein

the refractive index of the second insulating layer is less than the refractive index of the first insulating layer and is greater than the refractive index of the third insulating layer.

3. The display device of claim 2 , wherein

an opening is defined in the third insulating layer, the first insulating layer is disposed in the opening of the third insulating layer, and

the second insulating layer covers the first insulating layer and the third insulating layer.

4. The display device of claim 3 , wherein

a width of the opening of the third insulating layer corresponds to a width of the first insulating layer, and

an end portion of the first insulating layer contacts an end portion of the third insulating layer.

5. The display device of claim 3 , wherein

a width of the opening of the third insulating layer is greater than a width of the first insulating layer, and

the first insulating layer is spaced apart from the third insulating layer.

6. The display device of claim 3 , wherein

a width of the opening of the third insulating layer is greater than a width of the first insulating layer, and

the third insulating layer covers a lateral side of the first insulating layer.

7. The display device of claim 3 , wherein

the sensing electrode is covered by the third insulating layer.

8. The display device of claim 7 , further comprising:

a sensing electrode connector connected to the sensing electrode; and

a sensing insulating layer disposed between the sensing electrode and the sensing electrode connector.

9. The display device of claim 3 , wherein

the sensing electrode is disposed on the third insulating layer.

10. The display device of claim 9 , further comprising

a sensing electrode connector connected to the sensing electrode,

wherein the third insulating layer is disposed between the sensing electrode and the sensing electrode connector.

11. The display device of claim 2 , wherein

the second insulating layer covers the first insulating layer, and

the third insulating layer covers the second insulating layer.

12. The display device of claim 11 , wherein

the second insulating layer covers an upper side and a lateral side of the first insulating layer, and

the third insulating layer covers an upper side and a lateral side of the second insulating layer.

13. The display device of claim 11 , wherein

a width of the second insulating layer is greater than a width of the first insulating layer, and

the third insulating layer is disposed on an entirety of the substrate.

14. The display device of claim 11 , wherein

a thickness of the second insulating layer is greater than the maximum thickness of the first insulating layer, and

the maximum thickness of the third insulating layer is greater than the thickness of the second insulating layer.

15. The display device of claim 11 , further comprising:

a sensing electrode connector connected to the sensing electrode; and

a sensing insulating layer disposed between the sensing electrode and the sensing electrode connector,

wherein the first insulating layer is disposed on the sensing insulating layer.

16. The display device of claim 11 , further comprising:

a sensing electrode connector connected to the sensing electrode; and

a sensing insulating layer disposed between the sensing electrode and the sensing electrode connector,

wherein the first insulating layer includes a same material as a material of the sensing insulating layer and is disposed in a same layer.

17. The display device of claim 2 , wherein

a difference between a refractive index of the first insulating layer and a refractive index of the second insulating layer is equal to or greater than about 0.01 and is equal to or less than about 0.67.

18. The display device of claim 17 , wherein

a difference between a refractive index of the second insulating layer and a refractive index of the third insulating layer is equal to or greater than about 0.01 and is equal to or less than about 0.67.

19. The display device of claim 18 , wherein

the difference between the refractive index of the first insulating layer and the refractive index of the second insulating layer is equal to or greater than about 0.05, and

the difference between the refractive index of the second insulating layer and the refractive index of the third insulating layer is equal to or greater than about 0.05.