IP Library › Granted Patent US 9,876,187

Granted Patent B2

US 9,876,187 · App. 12/237,042 · Granted Jan 23, 2018

Light-emitting element, light-emitting device, and electronic appliance

Inventors: Satoko Shitagaki (Kanagawa, JP); Tsunenori Suzuki (Kanagawa, JP); Satoshi Seo (Kanagawa, JP)

Assignee: Semiconductor Energy Laboratory Co., Ltd.

H01L51/5048 H01L2251/552

View Patent ↗

Loading inventors, assignments & file history…

Monitor This Case

Get email alerts when status or documents change.

Order Certified Copies

Most orders are placed with the USPTO same day — all within 24 business hours.

Order via The Patent Place →

Pre-filled with this patent's details

Quick Facts

Patent No.: US 9,876,187
App. No.: 12/237,042
Granted: Jan 23, 2018
Kind: B2

External Links

USPTO Patent Center↗ Full Patent PDF↗

Abstract

In a light-emitting element including an EL layer between a pair of electrodes, between an electrode functioning as an anode and a fourth layer having a light-emitting property (light-emitting layer), the EL layer includes at least a first layer having a hole-injecting property (hole-injecting layer), a second layer having a hole-transporting property (first hole-transporting layer), and a third layer having a hole-transporting property (second hole-transporting layer). The absolute value of the highest occupied molecular orbital level (HOMO level) of the second layer is larger than the absolute value of the highest occupied molecular orbital level (HOMO level) of each of the first layer and the third layer. With such a structure, the rate of transport of holes injected from the electrode functioning as an anode is reduced and emission efficiency of the light-emitting element is improved.

Claims (139)

1. A light-emitting element comprising:

a first electrode;

a second electrode; and

an EL layer between the first electrode and the second electrode, the EL layer comprising:

a first layer including a substance having an acceptor property and a first substance having a hole-transporting property over the first electrode;

a second layer including a second substance having a hole-transporting property over the first layer;

a third layer including the first substance having a hole-transporting property over the second layer; and

a fourth layer including a substance having a light-emitting property over the third layer,

wherein the second layer is provided between the first layer and the third layer, and

wherein an absolute value of a highest occupied molecular orbital level of the second substance is larger than an absolute value of highest occupied molecular orbital level of the first substance.

2. The light-emitting element according to claim 1 ,

wherein the absolute value of the highest occupied molecular orbital level of the second substance is larger than the absolute value of the highest occupied molecular orbital level of the first substance by 0.1 eV or more.

3. A light-emitting element comprising:

an anode;

an cathode; and

an EL layer between the anode and the cathode, the EL layer comprising:

a first layer including a substance having an acceptor property and a first substance having a hole-transporting property over the anode;

a second layer including a second substance having a hole-transporting property over the first layer;

a third layer including the first substance having a hole-transporting property over the second layer; and

a fourth layer including a substance having a light-emitting property over the third layer,

wherein the second layer is provided between the first layer and the third layer, and

wherein an absolute value of a highest occupied molecular orbital level of the second substance is smaller than an absolute value of highest occupied molecular orbital level of the first substance.

4. The light-emitting element according to claim 3 ,

wherein the absolute value of the highest occupied molecular orbital level of the second substance is smaller than the absolute value of the highest occupied molecular orbital level of the first substance by 0.1 eV or more.

5. A light-emitting element comprising:

a first electrode;

a second electrode; and

an EL layer between the first electrode and the second electrode, the EL layer comprising:

a first layer including a substance having an acceptor property and a first substance having a hole-transporting property over the first electrode;

a second layer including a second substance having a hole-transporting property over the first layer;

a third layer including the first substance having a hole-transporting property over the second layer; and

a fourth layer including a substance having a light-emitting property over the third layer; and

a fifth layer controlling transport of electrons between the second electrode and the fourth layer,

wherein the second layer is provided between the first layer and the third layer,

wherein an absolute value of a highest occupied molecular orbital level of the second substance is larger than an absolute value of a highest occupied molecular orbital level of the first substance, and

wherein the fifth layer comprises a first organic compound having an electron-transporting property and a second organic compound having a hole-transporting property, and a content of the second organic compound is less than 50% of the total in mass ratio.

6. A light-emitting element comprising:

an anode;

an cathode; and

an EL layer between the anode and the cathode, the EL layer comprising:

a first layer including a substance having an acceptor property and a first substance having a hole-transporting property over the anode;

a second layer including a second substance having a hole-transporting property over the first layer,

a third layer including the first substance having a hole-transporting property over the second layer;

a fourth layer including a substance having a light-emitting property over the third layer; and

a fifth layer controlling transport of electrons between the cathode and the fourth layer,

wherein the second layer is provided between the first layer and the third layer,

wherein an absolute value of a highest occupied molecular orbital level of the second substance is smaller than an absolute value of highest occupied molecular orbital level of the first substance, and

7. The light-emitting element according to claim 5 ,

wherein a difference between an absolute value of a lowest unoccupied molecular orbital level of the second organic compound and an absolute value of a lowest unoccupied molecular orbital level of the first organic compound is 0.3 eV or less, and

wherein a relationship of P 1 /P 2 ≧3 is satisfied where a dipole moment of the first organic compound is P 1 and a dipole moment of the second organic compound is P 2 .

8. The light-emitting element according to claim 6 ,

wherein a relationship of P 1 /P 2 ≧3 is satisfied where a dipole moment of the first organic compound is P 1 and a dipole moment of the second organic compound is P 2 .

9. The light-emitting element according to claim 5 ,

wherein the first organic compound is a metal complex, and

wherein the second organic compound is an aromatic amine compound.

10. The light-emitting element according to claim 6 ,

wherein the first organic compound is a metal complex, and

wherein the second organic compound is an aromatic amine compound.

11. A light-emitting element comprising:

a first electrode;

a second electrode; and

an EL layer between the first electrode and the second electrode, the EL layer comprising:

a first layer including a substance having an acceptor property and a first substance having a hole-transporting property over the first electrode;

a second layer including a second substance having a hole-transporting property over the first layer

a third layer including the first substance having a hole-transporting property over the second layer;

a fourth layer including a substance having a light-emitting property over the third layer; and

a fifth layer controlling transport of electrons between the second electrode and the fourth layer,

wherein the second layer is provided between the first layer and the third layer,

wherein the fifth layer comprises a first organic compound having an electron-transporting property and a second organic compound having an electron-trapping property, and a content of the second organic compound is less than 50% of the total in mass ratio.

12. A light-emitting element comprising:

a first electrode;

a second electrode; and

an EL layer between the first electrode and the second electrode, the EL layer comprising:

a first layer including a substance having an acceptor property and a first substance having a hole-transporting property over the first electrode;

a second layer including a second substance having a hole-transporting property over the first layer;

a third layer including the first substance having a hole-transporting property over the second layer;

a fourth layer including a substance having a light-emitting property over the third layer; and

a fifth layer controlling transport of electrons between the second electrode and the fourth layer,

wherein the second layer is provided between the first layer and the third layer,

13. The light-emitting element according to claim 11 ,

wherein an absolute value of a lowest unoccupied molecular orbital level of the second organic compound is larger than an absolute value of lowest unoccupied molecular orbital level of the first organic compound by 0.3 eV or more.

14. The light-emitting element according to claim 12 ,

15. The light-emitting element according to claim 11 ,

wherein the first organic compound is a metal complex, and

wherein the second organic compound is a coumarin derivative.

16. The light-emitting element according to claim 12 ,

wherein the first organic compound is a metal complex, and

wherein the second organic compound is a coumarin derivative.

17. The light-emitting element according to claim 11 ,

wherein the first organic compound is a metal complex, and

wherein the second organic compound is a quinacridone derivative.

18. The light-emitting element according to claim 12 ,

wherein the first organic compound is a metal complex, and

wherein the second organic compound is a quinacridone derivative.

19. The light-emitting element according to claim 1 ,