Auxiliary Lines Reducing Resistance In A Cathode Of An Organic Light Emitting Display Device

• US 20160293888A1
• Filed: 09/21/2015
• Published: 10/06/2016
• Est. Priority Date: 04/02/2015
• Status: Active Grant

• Current Assignee: LG Display Co., Ltd.
• Original Assignee: LG Display Co., Ltd.
• Inventors: GEE, MoonBae, SHIM, Sungbin, KIM, Suhyeon
• Granted Patent: US 9,748,318 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: H10K 50/824 combined with auxiliary electrodes
• CPC Class Codes: H10K 59/122 Pixel-defining structures or layers, e.g. banks
• CPC Class Codes: H10K 59/123 Connection of the pixel electrodes to the thin film transistors [TFT]
• CPC Class Codes: H10K 59/124 Insulating layers formed between TFT elements and OLED elements
• CPC Class Codes: H10K 59/1315 comprising structures specially adapted for lowering the resistance
• CPC Class Codes: H10K 59/80522 combined with auxiliary electrodes

Abstract

An organic light emitting diode (OLED) display device is described that includes a shared cathode between OLED pixels as well as auxiliary lines that are formed between rows and/or columns of the OLED pixels. As the cathode is shared between many if not all of the pixels of display device, resistance within the cathode can affect the brightness of those pixels that are further from the cathode'"'"'s voltage source. The auxiliary lines serve to counteract the voltage drop caused by this resistance. The auxiliary lines are electrically connected to the cathode in close proximity to individual pixels of the display.

Claims

1. A display device comprising:

a pixel area comprising;

a pacification layer;

an anode electrically coupled to a source or a drain of a thin film transistor though the pacification layer;

an organic light-emitting layer formed on the anode;

a cathode formed on the organic light-emitting layer; and

a contact area comprising;

an auxiliary contact hole formed in the pacification layer, the auxiliary contact hole having an inverse tapered shape;

an auxiliary line having a first portion formed over the pacification layer and a second portion formed in the auxiliary contact hole;

a portion of the cathode physically contacting the second portion of the auxiliary line within the auxiliary contact hole.

2. The display device of claim 1 further comprising:

a bank layer formed on both the pacification layer and the first portion of the auxiliary line.

3. The display device of claim 1 further comprising:

a bank layer formed on the pacification layer but leaving exposed the first portion of the auxiliary line.

4. The display device of claim 1 wherein the inverse tapered shape of the auxiliary contact hole is such that an upper portion of the auxiliary contact hole is narrower than a bottom portion of the auxiliary contact hole.

5. The display device of claim 1

wherein the second portion of the auxiliary line is formed against a plurality of sidewalls of the auxiliary contact hole;

and

wherein the portion of the cathode physically contacts the second portion of the auxiliary line formed against the sidewalls.

6. The display device of claim 1 further comprising:

an island of bank material formed on the second portion of the auxiliary line formed on a bottom of the auxiliary contact hole, the island of bank material located beneath some portion of the cathode.

7. The display device of claim 1

wherein the auxiliary contact hole is extended to have a greater length or width in a horizontal or a vertical direction, respectively, along a direction parallel to a surface of the display device.

8. The display device of claim 1 further comprising:

an anode contact hole formed in the pacification layer, the anode contact hole having an inverse tapered shape.

9. The display device of claim 8 wherein the anode is formed against a plurality of sidewalls of the anode contact hole.

10. The display device of claim 1 wherein the auxiliary line is a first auxiliary line and wherein the display device further comprises:

a second auxiliary line formed on a same layer as the pacification layer and electrically coupled to the auxiliary line.

11. The display device of claim 10

wherein the second auxiliary line has a thickness greater than the source or drain of the thin film transistor.

12. The display device of claim 1

wherein the pacification layer comprises a first thickness in the contact area and a second thickness in the pixel area;

and

wherein the first thickness is thicker than the second thickness.

13. The display device of claim 1 wherein the pacification layer is a first pacification layer, and wherein the auxiliary line is a first auxiliary line.

14. The display device of claim 1 wherein the pacification layer is a second pacification layer, and wherein the auxiliary line is a first auxiliary line, the display device further comprising:

a first pacification layer formed beneath the second pacification layer.

15. The display device of claim 14 further comprising

a connection electrode electrically coupled to a source or a drain of a thin film transistor through the first pacification layer;

an anode electrically coupled to the connection electrode though the second pacification layer

16. The display device of claim 15

a second auxiliary line formed on a same layer as the second pacification layer and electrically coupled to the first auxiliary line, the second auxiliary electrode having a thickness greater than the connection electrode.

17. A display device comprising:

a plurality of organic light emitting diode (OLED) pixels formed in grid pattern across a surface, each of the pixels comprising an anode electrically isolated from each other anode, the pixels sharing a common cathode that is electrically coupled to each of the pixels;

a horizontal set of first auxiliary lines traversing the pixel area along a first axis, each of the auxiliary lines of the set passing between two rows of the pixels;

a vertical set of first auxiliary lines traversing the pixels along a second axis, each of the auxiliary lines of the set passing between two columns of the pixels; and

wherein each of the first auxiliary lines is electrically coupled to a portion of the cathode located proximately to one of the pixels.

18. The display device of claim 17 wherein for at least a subset of the pixels, one of the auxiliary lines is located on at least one side of each pixel in the subset.

19. The display device of claim 18 wherein for the subset of pixels, one of the auxiliary lines is located on each side of each pixel in the subset.

20. The display device of claim 17 further comprising:

a plurality of contact holes located at a plurality of intersection points between the horizontal and the vertical sets of first auxiliary lines; and

wherein the horizontal and the vertical sets of first auxiliary lines are electrically coupled through the contact holes.

21. The display device of claim 17 further comprising:

a horizontal set of second auxiliary lines formed underneath and electrically connected to the horizontal set of first auxiliary lines; and

a vertical set of second auxiliary lines formed underneath and electrically connected to the vertical set of first auxiliary lines.

22. The display device of claim 21 wherein the second auxiliary lines are formed of a same material as a source, a drain, or a connection electrode of each of the pixels.

23. The display device of claim 21 wherein the second auxiliary lines comprise a plurality of discontinuities, leaving gaps in the second auxiliary lines between each pixel.

24. The display device of claim 21 further comprising:

an interlayer dielectric formed under and physically contacting the second auxiliary lines.