Organic light-emitting diode display device and method of manufacturing same

1. An organic light-emitting diode (OLED) display device comprising:

a substrate in which a pixel area and a non-pixel area are defined;

an auxiliary electrode formed on the substrate;

a buffer film covering the auxiliary electrode;

an active interconnection line formed on the buffer film;

an auxiliary interconnection line that extends through the buffer film and connects an end of the active interconnection line to the auxiliary electrode;

a first passivation film covering the auxiliary interconnection line and having a contact hole that is formed through the first passivation film and in which an undercut structure is formed such that the active interconnection line is exposed through the undercut structure; and

a light-emitting element comprising a first electrode, an emissive layer, and a second electrode that are sequentially stacked on the first passivation film within the pixel area,

wherein the second electrode extends into the non-pixel area so that the second electrode is connected to a portion of the active interconnection line, the portion being exposed through the undercut structure within the through hole,

wherein the OLED display device further comprising a driving transistor that is formed on the substrate and which drives the light-emitting element,

wherein the driving transistor comprises a gate electrode and a drain electrode that is electrically connected to the first electrode of the light-emitting element, and

wherein the gate electrode, the drain electrode, and the auxiliary interconnection line are formed in the same process step.

2. The OLED display device according to claim 1 , wherein the second electrode extends along an upper surface of the active interconnection line and reaches a position within the undercut structure, thereby being connected with the auxiliary interconnection line within the undercut structure.

3. The OLED display device according to claim 2 , wherein a portion of the first passivation film protrudes from a wall surface of the contact hole and projects out over the active interconnection line within the contact hole such that the first passivation film partially overlaps the active interconnection line when viewed from above, and

the emissive layer is not formed on an upper surface of a portion of the active interconnection line, the portion overlapping the first passivation film.

4. The OLED display device according to claim 1 , further comprising an auxiliary substrate provided with a color filter, the auxiliary substrate being bonded to the substrate by a filler.

5. The OLED display device according to claim 1 , wherein an upper end of the undercut structure is defined by a lower surface of the passivation film.

6. The OLED display device according to claim 1 , wherein a portion of the first passivation film protrudes from a wall surface of the contact hole and projects out over the active interconnection line within the contact hole such that the first passivation film partially overlaps the active interconnection line when viewed from above, and

the second electrode extends to cover an upper surface of another portion of the active interconnection line, the another portion overlapping the first passivation film when viewed from above.

7. The OLED display device according to claim 1 , further comprising a second passivation film that is formed to fill the undercut structure.

8. A method of manufacturing an organic light-emitting diode (OLED) display device, the method comprising:

forming an auxiliary electrode on a substrate in which a pixel area and a non-pixel area are defined;

forming a buffer film to cover the auxiliary electrode;

forming an active interconnection film on the buffer film;

forming an auxiliary interconnection line formed to pass through the buffer film and configured to connect at least one of the auxiliary electrode to the active interconnection line;

forming a passivation film covering the auxiliary interconnection line;

etching the passivation film within the non-pixel area so that a portion of the auxiliary interconnection line is exposed;

forming a contact hole by partially etching the exposed auxiliary interconnection line such that an undercut structure occurs within the contact hole; and

forming a light-emitting element comprising a first electrode, an emissive layer, and a second electrode that are sequentially formed on the passivation film,

wherein the second electrode extends into the non-pixel area to be connected to the active interconnection line exposed through the undercut structure,

wherein the method further comprising forming a driving transistor that drives the light-emitting element on the substrate,

wherein the driving transistor comprises a gate electrode and a drain electrode electrically connected to the first electrode, and

wherein the gate electrode, the drain electrode and the auxiliary interconnection line are formed in the same process step.

9. The method according to claim 8 , wherein the forming of the active interconnection line comprises:

forming an active pattern made of a silicon-based semiconductor or an oxide-based semiconductor on the buffer film; and

performing a plasma treatment process or a heat treatment process on the active pattern so that the oxide-based semiconductor becomes conductive.

10. The method according to claim 8 , wherein the second electrode extends along an upper surface of the active interconnection line to enter into the undercut structure such that the second electrode is connected to the auxiliary interconnection line.

11. The method according to claim 8 , wherein a portion of the passivation film projects out over the active interconnection line within the contact hole such that the passivation film overlaps the active interconnection line when viewed from above, and

the second electrode extends along an upper surface of the active interconnection line that overlaps the passivation film when viewed from above.

12. The method according to claim 8 , further comprising bonding an auxiliary substrate provided with a color filter to the substrate, the color filter being disposed to the substrate.