Display device and tiled display device including the same

1 . A display device, comprising:

a substrate comprising a first contact hole disposed in the substrate;

a first connection line disposed on a surface of the substrate and electrically connected to a pad unit disposed on another surface opposite to the surface of the substrate through the first contact hole, the surface and the another surface being on opposite sides of the substrate in the thickness direction;

an organic filling part filling a depression of the first connection line formed in the first contact hole to planarize an upper surface of the first connection line such that an upper surface of the organic filling part is coplanar with the upper surface of the first connection line;

a thin film transistor layer disposed on the substrate and the first connection line, the thin film transistor layer comprising at least one thin film transistor and at least one insulating film; and

a light emitting element layer disposed on the thin film transistor layer, the light emitting element layer including a light emitting element electrically connected to the at least one thin film transistor, wherein

the thin film transistor layer comprises a second connection line electrically connecting the first connection line and the at least one thin film transistor through a second contact hole in the at least one insulating film,

the first contact hole, in which the first connection line is disposed, and the second contact hole, in which the second connection line is disposed, are laterally spaced apart from each other in a widthwise direction of the substrate perpendicular to the thickness direction,

the first connection line extends continuously from the first contact hole to overlap a center portion of the second contact hole in the thickness direction of the substrate,

the first connection line is between the organic filling part and the pad unit such that the organic filling part and the pad unit are spaced apart from each other,

a first insulating film of the at least one insulating film directly contacts the upper surface of the organic filling part, and

a material of the first insulating film of the at least one insulating film is different than a material of the organic filling part.

2 . The display device of claim 1 , wherein the material of the organic filling part includes at least one of acrylic resin, epoxy resin, phenolic resin, polyamide resin, and polyimide resin.

3 . The display device of claim 1 , wherein the at least one insulating film of the thin film transistor layer further comprises:

a gate insulating film disposed on the first connection line and the substrate;

an interlayer insulating film disposed on the gate insulating film; and

wherein the thin film transistor layer further comprises:

a connection electrode disposed on the interlayer insulating film and electrically connected to the at least one thin film transistor, and the second connection line and the connection electrode are disposed on a same layer.

4 . The display device of claim 3 , wherein the second connection line is electrically connected to the first connection line through the second contact hole penetrating the at least one insulating film.

5 . The display device of claim 1 , wherein

the substrate comprises another contact hole disposed on the another surface of the substrate and connected to the first contact hole, and

the pad unit is electrically connected to the first connection line through the another contact hole.

6 . The display device of claim 1 , wherein the first connection line is exposed at the another surface of the substrate through the first contact hole and is electrically connected to the pad unit.

7 . The display device of claim 1 , wherein

the substrate comprises a plurality of light emitting areas and a plurality of light blocking areas surrounding the plurality of light emitting areas, and

the display device further comprises:

a wavelength conversion layer disposed on the light emitting element layer, the wavelength conversion layer including a wavelength conversion unit corresponding to a part of the plurality of light emitting areas and a light transmission unit corresponding to another part of the plurality of light emitting areas; and

a color filter layer disposed on the wavelength conversion layer and including a plurality of color filters respectively corresponding to the plurality of light emitting areas.

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

a flexible film disposed on the another surface of the substrate and connected to the pad unit; and

a source driver disposed on the flexible film and supplying a voltage to the second connection line.

9 . A tiled display device, comprising:

a plurality of display devices each including a display area including a plurality of pixels and a non-display area adjacent to the display area; and

a coupling member connecting the plurality of display devices, wherein each of the plurality of display devices comprises:

a substrate comprising a first contact hole disposed in the substrate;

a first connection line disposed on a surface of the substrate and electrically connected to a pad unit disposed on another surface opposite to the surface of the substrate through the first contact hole, the surface and the another surface being on opposite sides of the substrate in the thickness direction;

an organic filling part filling a depression of the first connection line formed in the first contact hole to planarize an upper surface of the first connection line such that an upper surface of the organic filling part is coplanar with the upper surface of the first connection line;

a thin film transistor layer disposed on the substrate and the first connection line, the thin film transistor layer comprising at least one thin film transistor and at least one insulating film; and

a light emitting element layer disposed on the thin film transistor layer, the light emitting element layer including a light emitting element electrically connected to the at least one thin film transistor, wherein

the thin film transistor layer comprises a second connection line electrically connecting the first connection line and the at least one thin film transistor through a second contact hole in the at least one insulating film,

the first contact hole, in which the first connection line is disposed, and the second contact hole, in which the second connection line is disposed, are laterally spaced apart from each other in a widthwise direction of the substrate perpendicular to the thickness direction,

the first connection line extends continuously from the first contact hole to overlap a center portion of the second contact hole in the thickness direction of the substrate,

the first connection line is between the organic filling part and the pad unit such that the organic filling part and the pad unit are spaced apart from each other,

a first insulating film of the at least one insulating film directly contacts the upper surface of the organic filling part, and

a material of the first insulating film of the at least one insulating film is different than a material of the organic filling part.

10 . The display device of claim 1 , wherein:

the first connection line extends to contact a bottom portion of the second connection line disposed in the center portion of the second contact hole, and

the second contact hole is disposed at a higher level than the first contact hole.