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

• US 9,917,259 B2
• Filed: 07/28/2015
• Issued: 03/13/2018
• 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
• Primary Examiner(s): Garrett, Dawn L
• Application Number:
  US14/811,525
• Publication Number:
  US 20150333270A1
• Time in Patent Office: 959 Days
• 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 (m 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 EL layers (n is a natural number of two or more) between an anode and a cathode, each of the n EL layers comprising at least a light-emitting layer;

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

m≦

n−

1) and an (m+1)-th EL layer, the first layer comprising at least one of an alkali metal, an alkaline earth metal, and a rare earth metal;

a second layer between the first layer and the (m+1)-th EL layer, the second layer comprising an electron-transporting material; and

a charge-generation layer between the second layer and the (m+1)-th EL layer, the charge-generation layer comprising a hole-transporting material and an acceptor substance,

wherein each of the n EL layers further comprises a hole-transporting layer and an electron-transporting layer with the light-emitting layer interposed therebetween, and

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 electron-transporting material has a LUMO level of greater than or equal to −

5.0 eV.

3. The light-emitting element according to claim 1, wherein the electron-transporting material is a perylene derivative or a nitrogen-containing condensed aromatic compound.

4. 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.

5. The light-emitting element according to claim 1, wherein the hole-transporting material is a carbazole derivative or aromatic hydrocarbon.

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

7. A light-emitting device comprising the light-emitting element according to claim 1.

8. A light-emitting element comprising:

n EL layers (n is a natural number of two or more) between an anode and a cathode, each of the n EL layers comprising at least a light-emitting layer;

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

m≦

n−

1) and an (m+1)-th EL layer, the first layer comprising a first electron-transporting material and a donor substance;

a second layer between the first layer and the (m+1)-th EL layer, the second layer comprising a second electron-transporting material; and

a charge-generation layer between the second layer and the (m+1)-th EL layer, the charge-generation layer comprising a hole-transporting material and an acceptor substance,

wherein each of the n EL layers further comprises a hole-transporting layer and an electron-transporting layer with the light-emitting layer interposed therebetween, and

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

9. The light-emitting element according to claim 8, wherein the donor substance comprises at least one of an alkali metal, an alkaline earth metal, and a rare earth metal.

10. The light-emitting element according to claim 8, wherein each of the first electron-transporting material and the second electron-transporting material has a LUMO level of greater than or equal to −

5.0 eV.

11. The light-emitting element according to claim 8, wherein each of the first electron-transporting material and the second electron-transporting material is a perylene derivative or a nitrogen-containing condensed aromatic compound.

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

13. The light-emitting element according to claim 8, wherein the hole-transporting material is a carbazole derivative or aromatic hydrocarbon.

14. The light-emitting element according to claim 8, wherein the acceptor substance is molybdenum oxide.

15. A light-emitting device comprising the light-emitting element according to claim 8.