Organic light emitting device and method for manufacturing the same

• US 20080158108A1
• Filed: 06/22/2007
• Published: 07/03/2008
• Est. Priority Date: 12/27/2006
• Status: Active Grant

• Current Assignee: LG Display Co., Ltd.
• Original Assignee: LG Philips LCD Company Limited (LG Display Co., Ltd.)
• Inventors: Hwang, Kwang Jo, Park, Jae Hee
• Granted Patent: US 8,110,977 B2
• Time in Patent Office: Days
• US Class Current: 345/76
• CPC Class Codes: G09G 2300/0439 Pixel structures
• CPC Class Codes: G09G 2300/0842 forming a memory circuit, e.g. a dynamic memory with one capacitor
• CPC Class Codes: G09G 3/3233 with pixel circuitry controlling the current through the light-emitting element
• CPC Class Codes: H10K 2102/3026 Top emission
• CPC Class Codes: H10K 59/126 Shielding, e.g. light-blocking means over the TFTs

Abstract

A top emission OLED includes a driving TFT including a channel region and source and drain electrodes. A power supply, a ground line, and a light emitting diode are electrically coupled to the TFT and an auxiliary electrode is electrically coupled to the ground line and to the source electrode of the driver transistor. The auxiliary electrode resides between the light emitting diode and the channel region of the driver transistor and is configured to shield the channel region of the driver transistor from an electric field generated by the light emitting diode.

Claims

1. An organic light emitting device comprising:

a driver transistor including a channel region and source and drain electrodes;

a power supply, a ground line, and a light emitting diode, electrically coupled to the driver transistor; and

an auxiliary electrode electrically coupled to the ground line and to the source electrode of the driver transistor,

wherein the auxiliary electrode resides between the light emitting diode and the channel region of the driver transistor and is configured to shield the channel region of the driver transistor from an electric field generated by the light emitting diode.

2. The organic light emitting device of claim 1, wherein the auxiliary electrode overlies the source electrode and at least a portion of the channel region and is separated therefrom by an insulating layer.

3. The organic light emitting device of claim 1, wherein the auxiliary electrode overlies the source electrode and extends over the channel region to a point in proximity to the drain electrode and is separated therefrom by an insulating layer.

4. The organic light emitting device of claim 3, wherein the auxiliary electrode overlies is separated from the channel region and drain electrode by an insulating layer, and wherein auxiliary electrode encircles a perimeter of at least a portion of the channel region.

5. The organic light emitting device of claim 1, wherein the driver transistor is a p-type transistor.

6. The organic light emitting device of claim 1, wherein the auxiliary electrode is integral with the ground line.

7. The organic light emitting device of claim 1 further comprising a switching transistor electrically coupled to the driver transistor.

8. The organic light emitting device of claim 1, wherein the light emitting diode includes a first electrode electrically coupled to the drain of the driver transistor, and wherein the auxiliary electrode shields the channel region from the electric field generated at the first electrode.

9. An organic light emitting device comprising:

a driving transistor including a channel region, a source electrode and a drain electrode;

a light emitting diode overlying the driving transistor, the diode including, a first electrode electrically coupled to the drain electrode and overlying the driving transistor, an organic light emitting layer overlying the first electrode, and a second electrode overlying the organic light emitting layer; and

an auxiliary electrode between the first electrode and the channel region and electrically coupled to a ground line and to the source electrode, the auxiliary electrode overlying the channel region.

10. The organic light emitting device of claim 9, wherein the channel region has a ring shape and the auxiliary encircles at least a portion of the channel region.

11. The organic light emitting device of claim 9, wherein a portion of the auxiliary electrode overlaps with a portion of the ground line.

12. The organic light emitting device of claim 9 further comprising a switching transistor electrically coupled to the driver transistor.

13. The organic light emitting device of claim 9, wherein the auxiliary electrode comprises at least one selected from the group consisting of Al, an aluminum alloy, W, Cu, Mo, and Ti.

14. The organic light emitting device of claim 9, wherein the auxiliary electrode comprises at least one selected from the group consisting of indium tin oxide and indium zinc oxide.

15. A method for forming an organic light emitting device, the method comprising:

forming a driving transistor including a gate electrode overlying a substrate, a semiconductor layer overlying the gate electrode and separated therefrom by a gate insulating layer, a source electrode and a drain electrode overlying the semiconductor layer and defining a channel region in the semiconductor layer;

forming a light emitting diode overlying the driving transistor, the diode including, a first electrode electrically coupled to the source electrode and overlying the transistor, an organic light emitting layer overlying the first electrode, and a second electrode overlying the organic light emitting layer; and

forming an auxiliary electrode between the first electrode and the channel region and electrically coupled to a ground line and to the source electrode.

16. The method of claim 15, wherein forming an auxiliary electrode comprises:

forming a metal layer overlying the semiconductor layer and patterning the metal layer to form the source and drain electrodes;

forming a first passivation layer overlying source and drain electrodes and forming an opening in the first passivation layer to expose a portion of the source electrode;

forming a second metal layer overlying the first passivation layer and contacting the source electrode through the opening in first passivation layer; and

patterning the second metal layer to form the ground line and the auxiliary electrode.

17. The method of claim 15, wherein forming an auxiliary electrode comprises:

forming a metal layer overlying the semiconductor layer and patterning the metal layer to form the source and drain electrodes;

forming a first passivation layer overlying source and drain electrodes and forming an opening in the first passivation layer to expose a portion of the source electrode;

forming a second metal layer overlying the first passivation layer and contacting the source electrode through the opening in first passivation layer;

patterning the second metal layer to form the auxiliary electrode; and

forming a third metal layer overlying the auxiliary electrode and patterning the third metal layer to form the ground line.

18. The method of claim 16, wherein patterning the second metal layer to form the auxiliary electrode comprises patterning second metal layer on the first passivation layer to encircle the periphery of the channel region.

19. The method of claim 17, wherein patterning the second metal layer to form the auxiliary electrode comprises patterning second metal layer on the first passivation layer to encircle the periphery of the channel region.

20. The method of claim 16, wherein forming a light emitting diode comprises:

depositing a metal including at least one selected from the group consisting of Al, an aluminum alloy, W, Cu, Mo, and Ti and patterning the metal to form the auxiliary electrode;

or

depositing a metal including at least one selected from the group consisting of indium tin oxide and indium zinc oxide and patterning the metal to form the auxiliary electrode.