Organic light-emitting display device

Patent metadata

Field	Value
Publication number	US-9722207-B2
Application number	US-201615198672-A
Country	US
Kind code	B2
Filing date	Jun 30, 2016
Priority date	Aug 10, 2015
Publication date	Aug 1, 2017
Grant date	Aug 1, 2017

Abstract

Provided is a display device, including two light-emitting elements having different turn-on voltages. Each of the light-emitting elements includes a patterned electrode, a common layer, a patterned light-emitting layer, and a common electrode. The light-emitting element with the lower turn-on voltage among the two light-emitting elements includes a functional layer which suppresses a hole from being leaked from the light-emitting layer with the higher turn-on voltage through the common layer when the light-emitting element with the higher turn-on voltage among the two light-emitting elements is driven at a low gray scale to move into the patterned light-emitting layer of the light-emitting element with the lower turn-on voltage. Therefore, the light emission of an undesired pixel due to the leakage current is reduced, thereby improving the display quality.

First claim

What is claimed is:

1. A display device, comprising:
two light-emitting elements with different turn-on voltages,
wherein the two light-emitting elements respectively include a patterned electrode, a common layer, a patterned light-emitting layer, and a common electrode, and
wherein the light-emitting element with a lower turn-on voltage among the two light-emitting elements includes a functional layer configured to suppress holes from being leaked from the light-emitting layer with a higher turn-on voltage through the common layer and from moving into the patterned light-emitting layer of the light-emitting element with the lower turn-on voltage, when the light-emitting element with the higher turn-on voltage among the two light-emitting elements is driven at a low gray scale.

2. The display device according to claim 1 , wherein the light-emitting element with the lower turn-on voltage further includes a patterned layer between the common layer and the patterned light-emitting layer, and the functional layer is in contact with the common layer and the patterned layer.

3. The display device according to claim 2 , wherein a highest occupied molecular orbital (HOMO) level of the functional layer is lower than a HOMO level of the patterned layer.

4. The display device according to claim 3 , wherein the HOMO level of the functional layer is equal to or higher than a HOMO level of the patterned light-emitting layer of the light-emitting element with the lower turn-on voltage.

5. The display device according to claim 4 , wherein the functional layer is formed of the same material as a host material of the patterned light-emitting layer of the light-emitting element with the lower turn-on voltage.

6. The display device according to claim 5 , wherein an absolute value of the HOMO level of the functional layer is 5.0 eV or higher and 6.0 eV or lower.

7. The display device according to claim 6 , wherein the turn-on voltage of the light-emitting element with the lower turn-on voltage is increased to be higher than the turn-on voltage of the light-emitting element having the lower turn-on voltage which does not have the functional layer and the increased turn-on voltage is lower than the turn-on voltage of the light-emitting element having a higher turn-on voltage.

8. The display device according to claim 5 , wherein a sum of a thickness of the patterned layer and a thickness of the functional layer is a total thickness determined by a micro-cavity distance between the patterned electrode and the common electrode of the light-emitting element with the lower turn-on voltage.

9. The display device according to claim 8 , wherein the thickness of the functional layer is between 50 Å and 300 Å.

10. The display device according to claim 9 , wherein the patterned layer and the common layer are hole transporting layers which are formed of the same material.

11. The display device according to claim 5 , wherein the light-emitting element with the lower turn-on voltage is an element which emits red or green light and the light-emitting element with the higher turn-on voltage is a light-emitting element which emits blue light.

12. The display device according to claim 5 , wherein the light-emitting element with the lower turn-on voltage is an element which emits red light and the light-emitting element with the higher turn-on voltage is a light-emitting element which emits green or blue light.

13. An organic light-emitting display device including a first pixel and a second pixel which are adjacent to each other, the organic light-emitting display device comprising:
first electrodes corresponding to the first pixel and the second pixel, and spaced apart from each other;
a common hole transporting layer extending onto the first electrodes;
a first patterned light-emitting layer on the common hole transporting layer corresponding to the first pixel;
a second patterned light-emitting layer on the common hole transporting layer corresponding to the second pixel with a highest occupied molecular orbital (HOMO) level lower than that of the first patterned light-emitting layer;
a patterned hole transporting layer between the common hole transporting layer and the first patterned light-emitting layer corresponding to the first pixel;
a functional layer between the patterned hole transporting layer and the first patterned light-emitting layer corresponding to the first pixel with a HOMO level lower than that of the patterned hole transporting layer; and
a second electrode on the first patterned light-emitting layer and the second patterned light-emitting layer.

14. The organic light-emitting display device according to claim 13 , wherein the functional layer is configured to have a HOMO level that is equal to or higher than a HOMO level of the first patterned light-emitting layer.

15. The organic light-emitting display device according to claim 14 , wherein the functional layer is formed of the same material as a host material of the first patterned light-emitting layer.

16. The organic light-emitting display device according to claim 15 , wherein an absolute value of the HOMO level of the functional layer is 5.0 eV or higher and 6.0 eV or lower.

17. The organic light-emitting display device according to claim 16 , wherein a thickness of the functional layer is between 50 Å and 300 Å.

18. The organic light-emitting display device according to claim 17 , wherein the patterned hole transporting layer and the common hole transporting layer are formed of the same material.

19. The organic light-emitting display device according to claim 18 , wherein the first patterned light-emitting layer is a layer which emits red or green light and the second patterned light-emitting layer is a layer which emits blue light.

20. The organic light-emitting display device according to claim 18 , wherein the first patterned light-emitting layer is a layer which emits red light and the second patterned light-emitting layer is a layer which emits green or blue light.

Assignees

• Lg Display Co Ltd

Inventors

• Lee Sohee

Classifications

• H01L51/5056

  Electricity · mapped topic

• G09G2300/0452

  Details of colour pixel setup, e.g. pixel composed of a red, a blue and two green components · CPC title

• H01L2251/552

  Electricity · mapped topic

• H01L51/5221

  Electricity · mapped topic

• G09G2300/0819

  used for counteracting undesired variations, e.g. feedback or autozeroing · CPC title