Display device including an encapsulation structure

1. A display device comprising:

a substrate;

a display element disposed over the substrate; and

an encapsulation layer on the display element, wherein the encapsulation layer comprises:

an organic encapsulation layer including a bottom surface facing the display element and a top surface opposite to the bottom surface;

a first inorganic encapsulation layer between the display element and the organic encapsulation layer;

a second inorganic encapsulation layer on the top surface of the organic encapsulation layer; and

an inorganic insulating layer on the bottom surface of the organic encapsulation layer to be interposed between the first inorganic encapsulation layer and the organic encapsulation layer, wherein the inorganic insulating layer comprises an oxygen-rich layer that has a refractive index less than a refractive index of the first inorganic encapsulation layer.

2. The display device of claim 1 , wherein the oxygen-rich layer comprises an oxygen-rich silicon oxynitride layer.

3. The display device of claim 1 , wherein the first inorganic encapsulation layer comprises aluminum oxide, titanium oxide, tantalum oxide, hafnium oxide, zinc oxide, silicon oxide, silicon nitride, or silicon oxynitride.

4. The display device of claim 1 , wherein the first inorganic encapsulation layer has a thickness raging from about 600 nm to about 2,200 nm.

5. The display device of claim 1 , further comprising:

a LiF layer between the display element and the first inorganic encapsulation layer.

6. The display device of claim 1 , wherein the second inorganic encapsulation layer comprises at least one of inorganic insulating materials including aluminum oxide, titanium oxide, tantalum oxide, hafnium oxide, zinc oxide, silicon oxide, silicon nitride, and silicon oxynitride.

7. A display device comprising:

a substrate;

a pixel electrode;

a pixel-defining layer covering edges of the pixel electrode, an opening of the pixel-defining layer overlapping a portion of the pixel electrode;

an emission layer on the portion of the pixel electrode;

an opposite electrode on the emission layer;

an organic encapsulation layer including a bottom surface facing the opposite electrode and a top surface opposite to the bottom surface;

an inorganic encapsulation layer on the top surface of the organic encapsulation layer; and

a first inorganic insulating layer, a second inorganic insulating layer, and a third inorganic insulating layer that are between the opposite electrode and the bottom surface of the organic encapsulation layer,

wherein the third inorganic insulating layer is directly on the bottom surface of the organic encapsulation layer, the second inorganic insulating layer is between the third inorganic insulating layer and the first inorganic insulating layer, and the first inorganic insulating layer is between the opposite electrode and the second inorganic insulating layer, and

wherein the third inorganic insulating layer has a refractive index less than a refractive index of the second inorganic insulating layer.

8. The display device of claim 7 , wherein the third inorganic insulating layer comprises an oxygen-rich layer.

9. The display device of claim 7 , wherein each of the first, second, and third inorganic insulating layers comprises a silicon oxynitride layer.

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

as LiF layer between the opposite electrode and the first inorganic insulating layer.

11. The display device of claim 7 , wherein the inorganic encapsulation layer comprises at least one of inorganic insulating materials including aluminum oxide, titanium oxide, tantalum oxide, hafnium oxide, zinc oxide, silicon oxide, silicon nitride, and silicon oxynitride.

12. A display device comprising:

a substrate;

a pixel electrode;

a pixel-defining layer covering edges of the pixel electrode, an opening of the pixel-defining layer overlapping a portion of the pixel electrode;

an emission layer on the portion of the pixel electrode;

an opposite electrode on the emission layer;

an organic encapsulation layer including a bottom surface facing the opposite electrode and a top surface opposite to the bottom surface;

an inorganic encapsulation layer on the top surface of the organic encapsulation layer; and

a first inorganic insulating layer, a second inorganic insulating layer, and a third inorganic insulating layer that are between the opposite electrode and the bottom surface of the organic encapsulation layer,

wherein the third inorganic insulating layer is directly on the bottom surface of the organic encapsulation layer, the second inorganic insulating layer is between the third inorganic insulating layer and the first inorganic insulating, layer, and the first inorganic insulating layer is between the opposite electrode and the second inorganic insulating layer,

wherein each of the first, second, and third inorganic insulating layers comprises a silicon oxynitride layer, and

wherein the first, second, and third inorganic insulating layers respectively comprise different Si, O, and No content ratios or concentrations.

13. The display device of claim 12 , wherein the third inorganic insulating layer comprises an oxygen-rich silicon oxynitride layer.

14. The display device of claim 12 , wherein the third inorganic insulating layer has a refractive index less than a refractive index of the second inorganic insulating layer.

15. The display device of claim 12 , further comprising:

a LiF layer between the opposite electrode and the first inorganic insulating layer.

16. The display device of claim 12 , wherein the inorganic encapsulation layer comprises at least one of inorganic insulating materials including aluminum oxide, titanium oxide, tantalum oxide, hafnium oxide, zinc oxide, silicon oxide, silicon nitride, and silicon oxynitride.