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

• US 20160190500A1
• Filed: 12/22/2015
• Published: 06/30/2016
• Est. Priority Date: 12/26/2014
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: WATABE, Takeyoshi, SASAKI, Toshiki, SEO, Satoshi
• Granted Patent: US 9,991,471 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: C07F 15/0033 Iridium compounds
• CPC Class Codes: C09K 11/06 containing organic luminescent materials
• CPC Class Codes: H10K 2101/10 Triplet emission
• CPC Class Codes: H10K 2101/90 Multiple hosts in the emissive layer
• CPC Class Codes: H10K 50/11 characterised by the electroluminescent [EL] layers
• CPC Class Codes: H10K 50/852 comprising a resonant cavity structure, e.g. Bragg reflector pair
• CPC Class Codes: H10K 59/40 OLEDs integrated with touch screens
• CPC Class Codes: H10K 59/876 comprising a resonant cavity structure, e.g. Bragg reflector pair
• CPC Class Codes: H10K 85/342 comprising iridium
• CPC Class Codes: H10K 85/631 Amine compounds having at least two aryl rest on at least one amine-nitrogen atom, e.g. triphenylamine
• CPC Class Codes: H10K 85/633 comprising polycyclic condensed aromatic hydrocarbons as substituents on the nitrogen atom
• CPC Class Codes: H10K 85/6572 comprising only nitrogen in the heteroaromatic polycondensed ring system, e.g. phenanthroline or carbazole
• CPC Class Codes: H10K 85/6576 comprising only sulfur in the heteroaromatic polycondensed ring system, e.g. benzothiophene

Abstract

A light-emitting element that emits light with high color purity, a light-emitting element that emits light at high emission efficiency, or a light-emitting element with reduced power consumption. The light-emitting element includes a first electrode, a second electrode, and an EL layer. The first electrode is configured to reflect light. The second electrode is configured to reflect light and transmit light. The EL layer is between the first electrode and the second electrode. The EL layer includes a guest material. The guest material is configured to convert triplet excitation energy into light emission. The emission spectrum of the guest material in a dichloromethane solution has a peak in a wavelength region ranging from 440 nm to 470 nm and has a full width at half maximum of greater than or equal to 20 nm and less than or equal to 80 nm.

Claims

1. A light-emitting element comprising:

a first electrode;

a second electrode; and

an EL layer,

wherein the first electrode is configured to reflect light,

wherein the second electrode is configured to reflect light and transmit light,

wherein the EL layer is between the first electrode and the second electrode,

wherein the EL layer includes a first guest material,

wherein the first guest material is configured to convert triplet excitation energy into light emission, and

wherein an emission spectrum of the first guest material in a dichloromethane solution has a maximum value in a wavelength region ranging from 440 nm to 470 nm and has a full width at half maximum of greater than or equal to 20 nm and less than or equal to 80 nm.

2. The light-emitting element according to claim 1, wherein light intensity of the first guest material in the dichloromethane solution at a wavelength of 530 nm is greater than or equal to 0% and less than or equal to 50% of the maximum value.

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

wherein an chromaticity y in CIE 1931 chromaticity coordinates of the first guest material is greater than or equal to 0.01 and less than or equal to 0.3, and

wherein the chromaticity y is calculated from the emission spectrum of the first guest material in the dichloromethane solution.

4. The light-emitting element according to claim 1, wherein the light-emitting element emits light whose chromaticity yin CIE 1931 chromaticity coordinates is greater than or equal to 0.01 and less than or equal to 0.06 at a current efficiency greater than or equal to 3 cd/A.

5. The light-emitting element according to claim 1, wherein the light-emitting element emits light whose chromaticity y in CIE 1931 chromaticity coordinates is greater than 0.06 and less than or equal to 0.08 at a current efficiency greater than or equal to 8 cd/A.

6. The light-emitting element according to claim 1, wherein the light-emitting element emits light whose chromaticity y in CIE 1931 chromaticity coordinates is greater than 0.08 and less than or equal to 0.1 at a current efficiency greater than or equal to 10 cd/A.

7. The light-emitting element according to claim 1, wherein the first guest material includes iridium.

8. The light-emitting element according to claim 1, wherein the first guest material includes iridium.

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

wherein the first guest material includes a ligand coordinated to the iridium, and

wherein the ligand includes a nitrogen-containing five-membered heterocyclic skeleton.

10. The light-emitting element according to claim 9, wherein the nitrogen-containing five-membered heterocyclic skeleton is an imidazole skeleton or a triazole skeleton.

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

wherein the first electrode includes at least one of Al and Ag, and

wherein the second electrode includes at least one of Mg and Ag.

12. A display device comprising:

the light-emitting element according to claim 1; and

at least one of a color filter and a transistor.

13. An electronic device comprising:

the display device according to claim 12; and

at least one of a housing and a touch sensor.

14. A light-emitting element comprising:

a first electrode;

a second electrode;

a first EL layer;

a second EL layer; and

a charge-generation layer,

wherein the first electrode is configured to reflect light,

wherein the second electrode is configured to reflect light and transmit light,

wherein the first EL layer, the second EL layer, and the charge-generation layer are between the first electrode and the second electrode,

wherein the first EL layer includes a first guest material,

wherein the first guest material is configured to convert triplet excitation energy into light emission, and

wherein an emission spectrum of the first guest material in a dichloromethane solution has a maximum value in a wavelength region ranging from 440 nm to 470 nm and has a full width at half maximum of greater than or equal to 20 nm and less than or equal to 80 nm.

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

wherein the second EL layer includes a second guest material, and

wherein the emission spectrum of the second guest material has a maximum value in any one of a green wavelength region, a yellow-green wavelength region, a yellow wavelength region, an orange wavelength region, and a red wavelength region.

16. The light-emitting element according to claim 15, wherein the second guest material is configured to convert triplet excitation energy into light emission.

17. The light-emitting element according to claim 14, wherein the first guest material includes iridium.

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

wherein the first guest material includes a ligand coordinated to the iridium, and

wherein the ligand includes a nitrogen-containing five-membered heterocyclic skeleton.

19. A display device comprising:

the light-emitting element according to claim 14; and

at least one of a color filter and a transistor.

20. An electronic device comprising:

the display device according to claim 19; and

at least one of a housing and a touch sensor.