Display apparatus

1. A display apparatus comprising:

a substrate comprising a display area and a sensor area, the display area comprising main pixels and the sensor area comprising auxiliary pixels and a transmission area;

a plurality of display elements included in each of the main pixels and each of the auxiliary pixels;

a first stack structure overlapping the plurality of display elements;

a second stack structure overlapping the transmission area; and

a thin film encapsulation layer covering the first stack structure and the second stack structure,

wherein the first stack structure has a thickness that is different from a thickness of the second stack structure,

each of the first stack structure and the second stack structure comprises a capping layer and a light extraction layer disposed on the capping layer,

the thin film encapsulation layer is disposed on the light extraction layer and comprises a first inorganic encapsulation layer, and

a refractive index of the light extraction layer is less than a refractive index of the capping layer and a refractive index of the first inorganic encapsulation layer.

2. The display apparatus of claim 1 , wherein

the capping layer comprises a first capping area disposed over the transmission area and a second capping area disposed over the plurality of display elements, and

the first capping area has a thickness greater than a thickness of the second capping area.

3. The display apparatus of claim 2 , wherein

the thickness of the first capping area is greater than or equals to about 1.1 times and less than or equals to 10 times of the thickness of the second capping area.

4. The display apparatus of claim 2 , wherein

the light extraction layer comprises a first light extraction area disposed over the transmission area and a second light extraction area disposed over the plurality of display elements, and

the first light extraction area has a thickness greater than a thickness of the second light extraction area.

5. The display apparatus of claim 2 , wherein

the light extraction layer comprises a first light extraction area disposed over the transmission area and a second light extraction area disposed over the plurality of display elements,

a thickness of the first capping area is greater than or equals to about 90 nm and less than or equals to about 150 nm,

a thickness of the second capping area is greater than or equals to about 60 nm and less than or equals to about 85 nm,

a thickness of the first light extraction area is greater than or equals to about 50 nm and less than or equals to about 220 nm, and

a thickness of the second light extraction area is greater than or equals to about 10 nm and less than or equals to about 40 nm.

6. The display apparatus of claim 1 , wherein

the light extraction layer comprises a first light extraction area disposed over the transmission area and a second light extraction area disposed over the plurality of display elements, and

the first light extraction area has a thickness greater than a thickness of the second light extraction area.

7. The display apparatus of claim 6 , wherein

the thickness of the first light extraction area is about twice to about ten times greater than the thickness of the second light extraction area.

8. The display apparatus of claim 1 , wherein

a difference between the refractive index of the capping layer and the refractive index of the light extraction layer is greater than or equals to about 0.5, and

a difference between the refractive index of the first inorganic encapsulation layer and the refractive index of the light extraction layer is greater than or equals to about 0.46.

9. The display apparatus of claim 1 , wherein

the capping layer comprises a first capping area disposed over the transmission area and a second capping area disposed over the plurality of display elements,

the light extraction layer comprises a first light extraction area disposed over the first capping area and a second light extraction area disposed over the second capping area, and

the refractive index of the capping layer is greater than or equals to about 1.79 and less than or equals to about 2.2.

10. The display apparatus of claim 1 , wherein

the plurality of display elements comprise an opposite electrode formed in a single piece to cover the plurality of display elements, and the opposite electrode comprises an opening disposed corresponding to the transmission area.

11. The display apparatus of claim 1 ,

wherein

the plurality of display elements comprise an opposite electrode formed in a single piece to cover the plurality of display elements, and

the opposite electrode comprises a first area disposed corresponding to the plurality of display elements and a second area disposed corresponding to the transmission area, the second area having a thickness that is less than a thickness of the first area.

12. The display apparatus of claim 1 ,

wherein

an inorganic insulating layer and an organic insulating layer are disposed between the substrate and the plurality of display elements,

at least one of the inorganic insulating layer and the organic insulating layer comprises an opening or a groove disposed corresponding to the transmission area, and

the second stack structure is in the opening or the groove.

13. The display apparatus of claim 1 , further comprising

an infrared ray sensor on a lower surface of the substrate, the infrared ray sensor being disposed corresponding to the sensor area.

14. The display apparatus of claim 1 , further comprising

a lower electrode layer below an auxiliary pixel, the lower electrode layer being disposed corresponding to the auxiliary pixel.

15. A display apparatus comprising:

a substrate comprising a transmission area and a display area surrounding the transmission area;

a plurality of display elements in the display area;

a thin film encapsulation layer covering the transmission area and the plurality of display elements;

a capping layer disposed between the plurality of display elements and the thin film encapsulation layer to cover the transmission area; and

a light extraction layer disposed between the capping layer and the thin film encapsulation layer,

wherein at least one of the capping layer and the light extraction layer disposed in a region corresponding to the transmission area has a greater thickness than a region disposed corresponding to the plurality of display elements, and

a refractive index of the light extraction layer is less than a refractive index of the capping layer and a refractive index of the thin film encapsulation layer.

16. The display apparatus of claim 15 , wherein

the thin film encapsulation layer comprises a first inorganic encapsulation layer, and

a refractive index of the light extraction layer is less than a refractive index of the capping layer and a refractive index of the first inorganic encapsulation layer.

17. The display apparatus of claim 15 , wherein

the capping layer comprises a first capping area disposed over the transmission area and a second capping area disposed over the plurality of display elements, and

the first capping area has a thickness greater than a thickness of the second capping area.

18. The display apparatus of claim 15 , wherein

the light extraction layer comprises a first light extraction area disposed over the transmission area and a second light extraction area disposed over the plurality of display elements, and

the first light extraction area has a thickness greater than a thickness of the second light extraction area.

19. The display apparatus of claim 15 , wherein

the plurality of display elements comprise an opposite electrode formed in a single piece to cover the plurality of display elements, and

the opposite electrode comprises a first area disposed corresponding to the plurality of display elements and a second area disposed corresponding to the transmission area, the second area having a thickness less than a thickness of the first area.