LIGHT-EMITTING ELEMENT, LIGHT-EMITTING DEVICE, ELECTRONIC DEVICE, AND LIGHTING DEVICE

• US 20150349284A1
• Filed: 05/29/2015
• Published: 12/03/2015
• Est. Priority Date: 05/30/2014
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: SEO, Satoshi, ISHISONE, Takahiro, OHSAWA, Nobuharu, NONAKA, Yusuke, SASAKI, Toshiki
• Granted Patent: US 9,548,468 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G09G 2300/0426 Layout of electrodes and connections
• CPC Class Codes: G09G 3/3225 using an active matrix
• CPC Class Codes: H10K 2101/10 Triplet emission
• CPC Class Codes: H10K 2101/27 Combination of fluorescent and phosphorescent emission
• CPC Class Codes: H10K 2101/30 Highest occupied molecular orbital [HOMO], lowest unoccupied molecular orbital [LUMO] or Fermi energy values
• 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 50/12 comprising dopants
• CPC Class Codes: H10K 50/13 comprising stacked EL layers within one EL unit
• CPC Class Codes: H10K 50/131 with spacer layers between the electroluminescent layers
• CPC Class Codes: H10K 50/15 Hole transporting layers
• CPC Class Codes: H10K 50/16 Electron transporting layers
• CPC Class Codes: H10K 50/81 Anodes
• CPC Class Codes: H10K 50/82 Cathodes
• CPC Class Codes: H10K 50/84 Passivation; Containers; Encapsulations
• CPC Class Codes: H10K 59/00 Integrated devices, or assemblies of multiple devices, comprising at least one organic light-emitting element covered by group H10K50/00
• CPC Class Codes: H10K 59/1213 the pixel elements being TFTs
• CPC Class Codes: H10K 59/131 Interconnections, e.g. wiring lines or terminals
• CPC Class Codes: H10K 59/38 comprising colour filters or colour changing media [CCM]
• CPC Class Codes: H10K 59/876 comprising a resonant cavity structure, e.g. Bragg reflector pair

Abstract

Emission efficiency of a light-emitting element is improved. The light-emitting element has a pair of electrodes and an EL layer between the pair of electrodes. The EL layer includes a first light-emitting layer and a second light-emitting layer. The first light-emitting layer includes a fluorescent material and a host material. The second light-emitting layer includes a phosphorescent material, a first organic compound, and a second organic compound. An emission spectrum of the second light-emitting layer has a peak in a yellow wavelength region. The first organic compound and the second organic compound form an exciplex.

Claims

1. A light-emitting element comprising:

a first electrode;

a second electrode; and

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

wherein the EL layer comprises a first light-emitting layer and a second light-emitting layer,

wherein the first light-emitting layer comprises a fluorescent material and a host material,

wherein the second light-emitting layer comprises a phosphorescent material, a first organic compound, and a second organic compound,

wherein an emission spectrum of the second light-emitting layer has a peak in a yellow wavelength region,

wherein the first organic compound and the second organic compound form an exciplex, and

wherein energy is transferred from the exciplex to the phosphorescent material.

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

wherein a singlet excited level of the host material is higher than a singlet excited level of the fluorescent material, and

wherein a triplet excited level of the host material is lower than a triplet excited level of the fluorescent material.

3. The light-emitting element according to claim 1, wherein a triplet excited level of the host material is lower than triplet excited levels of the first organic compound and the second organic compound.

4. The light-emitting element according to claim 1, wherein the first light-emitting layer and the second light-emitting layer are in contact with each other.

5. The light-emitting element according to claim 1, wherein the first light-emitting layer and the second light-emitting layer are spaced from each other.

6. The light-emitting element according to claim 5, wherein a layer in which a hole-transport material and an electron-transport material are mixed is located between the first light-emitting layer and the second light-emitting layer.

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

wherein the first electrode is an anode,

wherein the second electrode is a cathode,

wherein the first light-emitting layer is over the first electrode, and wherein the second light-emitting layer is over the first light-emitting layer.

8. A light-emitting device comprising:

the light-emitting element according to claim 1; and

a transistor or a substrate.

17. A module comprising:

the light-emitting device according to claim 8; and

a connector connected to the light-emitting device.

18. The module according to claim 17,

wherein the connector is an FPC or a TCP.

19. An electronic device comprising:

the light-emitting device according to claim 8; and

any of an external connection port, a keyboard, an operation button, a speaker and a microphone.

20. A lighting device comprising:

the light-emitting device according to claim 8; and

a housing.

9. A light-emitting element comprising:

a first electrode;

a second electrode; and

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

wherein the EL layer comprises a first light-emitting layer and a second light-emitting layer,

wherein the first light-emitting layer comprises a fluorescent material and a host material,

wherein the second light-emitting layer comprises a phosphorescent material, a first organic compound, and a second organic compound,

wherein the first organic compound and the second organic compound form an exciplex,

wherein an emission spectrum of the phosphorescent material has a peak in a yellow wavelength region, and

wherein energy is transferred from the exciplex to the phosphorescent material.

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

wherein a singlet excited level of the host material is higher than a singlet excited level of the fluorescent material, and

wherein a triplet excited level of the host material is lower than a triplet excited level of the fluorescent material.

11. The light-emitting element according to claim 9, wherein a triplet excited level of the host material is lower than triplet excited levels of the first organic compound and the second organic compound.

12. The light-emitting element according to claim 9, wherein the first light-emitting layer and the second light-emitting layer are in contact with each other.

13. The light-emitting element according to claim 9, wherein the first light-emitting layer and the second light-emitting layer are spaced from each other.

14. The light-emitting element according to claim 13, wherein a layer in which a hole-transport material and an electron-transport material are mixed is located between the first light-emitting layer and the second light-emitting layer.

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

wherein the first electrode is an anode,

wherein the second electrode is a cathode,

wherein the first light-emitting layer is over the first electrode, and

wherein the second light-emitting layer is over the first light-emitting layer.

16. A light-emitting device comprising:

the light-emitting element according to claim 9; and

a transistor or a substrate.