Organic light emitting diode display device

1. An organic light emitting diode display device, comprising:

a substrate having an emitting area and a non-emitting area, the substrate having a first surface and a second surface;

an overcoating layer on the first surface of the substrate and including a plurality of convex portions and a plurality of concave portions, at least one of the plurality of convex portions including a bottom surface portion, a top surface portion, and a side surface portion between the bottom and top surface portions;

a light emitting diode on the overcoating layer; and

a cholesteric liquid crystal layer on the second surface of the substrate in a transmission direction of a light emitted from the light emitting diode having a flat portion at locations corresponding to the plurality of concave portions,

wherein the flat portion is substantially parallel to the substrate, and

wherein a diameter of the flat portion is within a range of 1% to 25% of a diameter between the top surface portions of adjacent two of the plurality of convex portions.

2. The organic light emitting diode display device of claim 1 , wherein the substrate includes red, green, blue, and white sub-pixels,

wherein the light emitting diode emits red, green, blue, and white colored lights in the red, green, blue and white sub-pixels, respectively, and

wherein the cholesteric liquid crystal layer selectively reflects the blue colored light having a wavelength within a range of 440 nm to 480 nm.

3. The organic light emitting diode display device of claim 1 , wherein the substrate includes red, green, blue, and white sub-pixels,

wherein the light emitting diode emits red, green, blue, and white colored lights in the red, green, blue and white sub-pixels, respectively,

wherein the cholesteric liquid crystal layer includes red, green, blue, and white cholesteric liquid crystal layers in the red, green, blue and white sub-pixels, respectively,

wherein the red cholesteric liquid crystal layer selectively reflects the red colored light having a wavelength within a range of 650 nm to 720 nm,

wherein the green cholesteric liquid crystal layer selectively reflects the green colored light having a wavelength within a range of 490 nm to 575 nm,

wherein the blue cholesteric liquid crystal layer selectively reflects the blue colored light having a wavelength within a range of 440 nm to 480 nm, and

wherein the white cholesteric liquid crystal layer selectively reflects the white colored light having a wavelength within a range of 365 nm to 720 nm.

4. The organic light emitting diode display device of claim 1 , further comprising a retardation plate and a linear polarizing plate sequentially on a second surface of the substrate.

5. The organic light emitting diode display device of claim 4 , wherein the cholesteric liquid crystal layer is disposed between the light emitting diode and the retardation plate.

6. The organic light emitting diode display device of claim 1 , wherein a slope of the side surface portion increases from the bottom surface portion to the top surface portion.

7. The organic light emitting diode display device of claim 1 , wherein the light emitting diode includes a first electrode on the overcoating layer, a light emitting layer on the first electrode and a second electrode on the light emitting layer.

8. The organic light emitting diode display device of claim 7 , wherein a thickness of the light emitting layer on the side surface portion is smaller than a thickness of the light emitting layer on the plurality of concave portions.

9. The organic light emitting diode display device of claim 1 , further comprising a wavelength converting layer interposed between the substrate and the overcoating layer, and

wherein an edge portion of the wavelength converting layer extends beyond an edge portion of the plurality of convex portions and the plurality of concave portions toward the non-emitting area.

10. The organic light emitting diode display device of claim 9 , further comprising a bank over the overcoating layer and including an opening exposing the first electrode,

wherein the plurality of convex portions and the plurality of concave portions are formed in the opening.

11. The organic light emitting diode display device of claim 10 , wherein the plurality of convex portions and the plurality of concave portions contact an edge portion of the bank.

12. The organic light emitting diode display device of claim 10 , wherein the bank overlays an edge portion of the convex portions and the plurality of concave portions.

13. The organic light emitting diode display device of claim 10 , wherein an edge portion of the wavelength converting layer, an edge portion of the plurality of convex portions and the plurality of concave portions and an edge portion of the bank overlap one another in the non-emitting area.

14. The organic light emitting diode display device of claim 1 , wherein a border portion of the emitting area and the non-emitting area overlaps an edge portion of the plurality of convex portions and the plurality of concave portions.

15. The organic light emitting diode display device of claim 1 , wherein the convex portion constitutes one of a hexagonal shape and a honeycomb structure in a plan view.

16. The organic light emitting diode display device of claim 1 , wherein the flat portion has a circular shape in a plan view, and the top surface portion has a hexagonal shape in a plan view.

17. The organic light emitting diode display device of claim 7 , wherein the first electrode directly contacts the flat portion such that:

a light emitted from the light emitting diode is reflected by the cholesteric liquid crystal layer and re-enters the light emitting diode;

the light re-reflected by the second electrode passes through the first electrode and the side surface portion to become a first light having different optical paths; and

the light re-reflected by the second electrode passes through the first electrode and the flat portion to become a second light having same optical paths.

18. The organic light emitting diode display device of claim 4 , further comprising a surface treatment layer on the linear polarizing plate, wherein the surface treatment layer includes an anti-glare layer having a silica bead.