Light-Emitting Element, Light-Emitting Device, Lighting Device, and Electronic Device

• US 20110057179A1
• Filed: 09/02/2010
• Published: 03/10/2011
• Est. Priority Date: 09/07/2009
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: NOWATARI, Hiromi, SEO, Satoshi
• Granted Patent: US 9,099,682 B2
• Time in Patent Office: Days
• US Class Current: 257/40
• CPC Class Codes: H10K 2101/40 Interrelation of parameters between multiple constituent active layers or sublayers, e.g. HOMO values in adjacent layers
• CPC Class Codes: H10K 50/11 characterised by the electroluminescent [EL] layers
• CPC Class Codes: H10K 50/13 comprising stacked EL layers within one EL unit
• CPC Class Codes: H10K 50/15 Hole transporting layers
• CPC Class Codes: H10K 50/16 Electron transporting layers
• CPC Class Codes: H10K 50/19 Tandem OLEDs
• CPC Class Codes: H10K 50/81 Anodes
• CPC Class Codes: H10K 50/82 Cathodes
• CPC Class Codes: H10K 59/32 Stacked devices having two or more layers, each emitting at different wavelengths
• CPC Class Codes: H10K 71/164 using vacuum deposition
• CPC Class Codes: H10K 85/00 Organic materials used in the body or electrodes of devices covered by this subclass
• CPC Class Codes: H10K 85/324 comprising aluminium, e.g. Alq3
• CPC Class Codes: H10K 85/621 Aromatic anhydride or imide compounds, e.g. perylene tetra-carboxylic dianhydride or perylene tetracarboxylic di-imide
• CPC Class Codes: H10K 85/633 comprising polycyclic condensed aromatic hydrocarbons as substituents on the nitrogen atom
• CPC Class Codes: H10K 85/654 comprising only nitrogen as heteroatom H10K85/652 takes precedence

Abstract

A light-emitting element is provided, in which n (n is a natural number of two or more) EL layers are provided between an anode and a cathode. Between the m-th (in is a natural number, 1≦m≦n−1) EL layer and the (m+1)-th EL layer, a first layer containing any of an alkali metal, an alkaline earth metal, a rare earth metal, an alkali metal compound, an alkaline earth metal compound, and a rare earth metal compound, a second layer containing a substance having high electron-transport properties in contact with the first layer, and a charge-generation layer containing a substance having high hole-transport properties and an acceptor substance in contact with the second layer are provided in this order over the anode. The charge-generation layer does not have a peak of an absorption spectrum in a visible light region.

Claims

1. A light-emitting element comprising:

n (n is a natural number of two or more) EL layers between an anode and a cathode;

a first layer provided between an m-th (m is a natural number, 1≦

m≦

n−

1) EL layer and an (m+1)-th EL layer wherein the first layer contains one selected from the group consisting of an alkali metal, an alkaline earth metal, a rare earth metal, an alkali metal compound, an alkaline earth metal compound, and a rare earth metal compound;

a second layer provided on the first layer and between the m-th EL layer and the (m+1)-th EL layer wherein the second layer contains a substance having high electron-transport properties; and

a charge-generation layer provided on the second layer and between the m-th EL layer and the (m+1)-th EL layer wherein the charge-generation layer contains a substance having high hole-transport properties and an acceptor substance,

wherein the charge-generation layer does not have a peak of an absorption spectrum in a visible light region.

2. The light-emitting element according to claim 1, wherein the layer containing the substance having high hole-transport properties and the acceptor substance is a layer to which the acceptor substance is added so that a mass ratio of the acceptor substance to the substance having high hole-transport properties is from 0.1:

1 to 4.0;

1, both inclusive.

3. The light-emitting element according to claim 1, wherein the substance having high electron-transport properties contained in the second layer has a LUMO level of greater than or equal to −

5.0 eV.

4. The light-emitting element according to claim 1, wherein the substance having high electron-transport properties contained in the second layer is a perylene derivative or a nitrogen-containing condensed aromatic compound.

5. The light-emitting element according to claim 1, wherein the acceptor substance is a transition metal oxide or an oxide of a metal belonging to any of Groups 4 to 8 of the periodic table.

6. The light-emitting element according to claim 1, wherein the substance having high hole-transport properties is a carbazole derivative or aromatic hydrocarbon.

7. The light-emitting element according to claim 1, wherein the acceptor substance is molybdenum oxide.

8. A light-emitting device manufactured using the light-emitting element according to claim 1.

9. An electronic device comprising the light-emitting device according to claim 8.

10. A lighting device comprising the light-emitting device according to claim 8.

11. A light-emitting element comprising:

n (n is a natural number of two or more) EL layers between an anode and a cathode;

a first layer provided between an m-th (in is a natural number, 1≦

m≦

n−

1) EL layer and an (m+1)-th EL layer wherein the first layer contains a substance having high electron-transport properties and a donor substance;

a second layer provided on the first layer and between the m-th EL layer and the (m+1)-th EL layer wherein the second layer contains a substance having high electron-transport properties; and

a charge-generation layer provided on the second layer and between the m-th EL layer and the (m+1)-th EL layer wherein the charge-generation layer contains a substance having high hole-transport properties and an acceptor substance,

wherein the charge-generation layer does not have a peak of an absorption spectrum in a visible light region.

12. The light-emitting element according to claim 11, wherein the first layer is a layer to which the donor substance is added so that a mass ratio of the donor substance to the substance having high electron-transport properties is from 0.001:

1 to 0.1;

1, both inclusive.

13. The light-emitting element according to claim 11, wherein the donor substance is one selected from the group consisting of an alkali metal, an alkaline earth metal, a rare earth metal, an alkali metal compound, an alkaline earth metal compound, and a rare earth metal compound.

14. The light-emitting element according to claim 11, wherein the layer containing the substance having high hole-transport properties and the acceptor substance is a layer to which the acceptor substance is added so that a mass ratio of the acceptor substance to the substance having high hole-transport properties is from 0.1:

1 to 4.0;

1, both inclusive.

15. The light-emitting element according to claim 11, wherein the substance having high electron-transport properties contained in the second layer has a LUMO level of greater than or equal to −

5.0 eV.

16. The light-emitting element according to claim 11, wherein the substance having high electron-transport properties contained in the second layer is a perylene derivative or a nitrogen-containing condensed aromatic compound.

17. The light-emitting element according to claim 11, wherein the acceptor substance is a transition metal oxide or an oxide of a metal belonging to any of Groups 4 to 8 of the periodic table.

18. The light-emitting element according to claim 11, wherein the substance having high hole-transport properties is a carbazole derivative or aromatic hydrocarbon.

19. The light-emitting element according to claim 11, wherein the acceptor substance is molybdenum oxide.

20. A light-emitting device manufactured using the light-emitting element according to claim 11.

21. An electronic device comprising the light-emitting device according to claim 20.

22. A lighting device comprising the light-emitting device according to claim 20.