Electronic device including a light-emitting element having functional layers with thickness profiles

1. An electronic device comprising:

a base layer;

a first electrode on the base layer;

a pixel defining layer on the base layer and having an opening that exposes an upper surface of the first electrode;

a hole transport region in the opening and having a thickness gradually decreasing from a center of the opening toward a side surface of the pixel defining layer;

an emission layer directly on the hole transport region and having a thickness gradually increasing from the center of the opening toward the side surface of the pixel defining layer;

an electron transport region on the emission layer; and

a second electrode on the electron transport region,

wherein the emission layer comprises a host and a dopant.

2. The electronic device of claim 1 , wherein

a first average thickness in a first portion of the hole transport region is greater than a second average thickness in a second portion of the hole transport region,

the first portion is 60% of a total cross-sectional area of the hole transport region, with a virtual center line passing through the center of the hole transport region as the center line of the total cross-sectional area in the thickness direction of the hole transport region,

the second portion is 80% of the total cross-sectional area of the hole transport region, and

wherein a value of the first average thickness is a cross-sectional area of the first portion divided by a width of the first portion, and a value of the second average thickness is a cross-sectional area of the second portion dived by a width of the second portion.

3. The electronic device of claim 2 , wherein

an upper surface of the hole transport region is a curved surface convex toward the emission layer.

4. The electronic device of claim 1 , wherein

a first average thickness in a first portion of the emission layer is smaller than a second average thickness in a second portion of the emission layer,

the first portion is 60% of a total cross-sectional area of the emission layer, with a virtual center line passing through the center of the emission layer as the center line of the total cross-sectional area in the thickness direction of the emission layer,

the second portion is 80% of the total cross-sectional area of the emission layer, and

wherein a value of the first average thickness is a cross-sectional area of the first portion divided by a width of the first portion, and a value of the second average thickness is a cross-sectional area of the second portion divided by a width of the second portion.

5. The electronic device of claim 4 , wherein

a lower surface of the emission layer is a curved surface concave toward an upper surface of the emission layer, and

the upper surface of the emission layer is a flat surface.

6. The electronic device of claim 1 , wherein

a percentage difference between

a sum of a thickness of a first portion of the hole transport region measured at a virtual center line, which passes through the center of the opening and is normal to the first electrode, and a thickness of a second portion of the emission layer measured at the virtual center line, and

a sum of a thickness of a third portion of the hole transport region and a thickness of a fourth portion of the emission layer respectively measured at a virtual outer peripheral line parallel to the virtual center line,

is less than about 10%.

7. The electronic device of claim 1 , wherein the hole transport region comprises

a hole injection layer on the first electrode; and

a hole transport layer on the hole injection layer,

the hole injection layer and having a thickness gradually decreasing from the center of the opening toward the side surface of the pixel defining layer.

8. The electronic device of claim 7 , wherein

the hole transport layer has a thickness gradually decreasing from the center of the opening toward the side surface of the pixel defining layer.

9. The electronic device of claim 7 , wherein

an upper surface of the hole injection layer is a curved surface convex toward the emission layer, and

an upper surface of the hole transport layer is a curved surface convex toward the emission layer.

10. The electronic device of claim 1 , wherein

a resistivity of the hole transport region is lower than a resistivity of the emission layer.

11. The electronic device of claim 10 , wherein

the resistivity of the emission layer is about 10 times to about 100 times the resistivity of the hole transport region.

12. The electronic device of claim 1 , wherein

the side surface of the pixel defining layer defining the opening is hydrophobic.

13. The electronic device of claim 1 , wherein

the hole transport region and the emission layer are provided by an inkjet printing method, and

the electron transport region is provided by a deposition method.

14. An electronic device comprising:

a pixel defining layer in which a plurality of openings spaced apart from each other on a plane are defined; and

a plurality of light-emitting elements comprising at least one functional layer in each of the plurality of openings,

wherein each of the plurality of light-emitting elements comprises:

a first electrode, at least a portion of the first electrode being in direct contact with at least a portion of the pixel defining layer;

a hole transport region on the first electrode and being greater in thickness at a center of the hole transport region than at an outer periphery thereof;

an emission layer on the hole transport region and being smaller in thickness at a center of the emission layer than at an outer periphery thereof;

an electron transport region on the emission layer; and

a second electrode on the electron transport region, and

wherein the center of the hole transport region and the center of the emission layer respectively correspond to a point that passes through a virtual center line normal to the first electrode, and the outer periphery of the hole transport region and the outer periphery of the emission layer respectively correspond to a point spaced apart from the center toward the pixel defining layer.

15. The electronic device of claim 14 , wherein

the at least one functional layer is provided by an inkjet printing method.

16. The electronic device of claim 14 , wherein

an upper surface of the hole transport region is a curved surface convex toward the emission layer.

17. The electronic device of claim 16 , wherein

a shape of a lower surface of the emission layer corresponds to a shape of the upper surface of the hole transport region, and

an upper surface of the emission layer is a flat surface.

18. The electronic device of claim 16 , wherein

in the plurality of openings, a difference between a first thickness from the first electrode to an upper portion of the emission layer at a center of an opening of the plurality of openings and a second thickness from the first electrode to the upper portion of the emission layer at an outer periphery of the opening is less than about 10%.

19. An electronic device comprising a plurality of light-emitting elements,

each of the plurality of light-emitting elements comprising:

a first electrode;

a hole transport region on the first electrode;

an emission layer directly on the hole transport region, the emission layer comprising a host and a dopant;

an electron transport region on the emission layer; and

a second electrode on the electron transport region,

wherein a first thickness of the hole transport region, which is a distance between the first electrode and the emission layer, decreases from a center of the hole transport region to an outer periphery thereof, and

a second thickness of the emission layer, which is a distance between the hole transport region and the electron transport region, increases from a center of the emission layer to an outer periphery thereof.

20. The electronic device of claim 19 , wherein

an upper surface of the hole transport region is a curved surface convex toward the emission layer, and

a shape of a lower surface of the emission layer corresponds to a shape of the upper surface of the hole transport region, and an upper surface of the emission layer is a flat surface.