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

• US 10,454,054 B2
• Filed: 05/15/2017
• Issued: 10/22/2019
• Est. Priority Date: 05/17/2013
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Ishisone, Takahiro, Seo, Satoshi
• Primary Examiner(s): Alavi, Ali
• Application Number:
  US15/594,976
• Publication Number:
  US 20170317306A1
• Time in Patent Office: 890 Days
• Field of Search: 362231
• CPC Class Codes: C07F 15/0033 Iridium compounds
• CPC Class Codes: C09K 11/06 containing organic luminescent materials
• CPC Class Codes: C09K 2211/1007 Non-condensed systems
• CPC Class Codes: C09K 2211/1059 containing three nitrogen atoms as heteroatoms
• CPC Class Codes: C09K 2211/185 of the platinum group, i.e. Os, Ir, Pt, Ru, Rh or Pd
• CPC Class Codes: H10K 2101/10 Triplet emission
• 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 85/342 comprising iridium
• CPC Class Codes: H10K 85/615 Polycyclic condensed aromatic hydrocarbons, e.g. anthracene
• CPC Class Codes: H10K 85/626 containing more than one polycyclic condensed aromatic rings, e.g. bis-anthracene
• CPC Class Codes: H10K 85/633 comprising polycyclic condensed aromatic hydrocarbons as substituents on the nitrogen atom
• CPC Class Codes: H10K 85/636 comprising heteroaromatic hydrocarbons as substituents on the nitrogen atom
• CPC Class Codes: H10K 85/654 comprising only nitrogen as heteroatom H10K85/652 takes precedence
• 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 includes a first electrode; a first light-emitting layer over the first electrode, containing a first phosphorescent compound and a first host material; a second light-emitting layer over the first light-emitting layer, containing a second phosphorescent compound and a second host material; a third light-emitting layer over the second light-emitting layer, containing a third phosphorescent compound and a third host material; and a second electrode over the third light-emitting layer. Between peaks of emission spectra of the first, second, and third phosphorescent compounds, the peak of the emission spectrum of the second phosphorescent compound is on the longest wavelength side and that of the emission spectrum of the third phosphorescent compound is on the shortest wavelength side. The third host material has higher triplet excitation energy than the first host material and the second host material.

Claims

1. A light-emitting element comprising:

a first electrode;

a first light-emitting layer over the first electrode, the first light-emitting layer comprising a first compound and a first host material, wherein the first compound is capable of converting an energy of a triplet excited state of the first compound into a first light;

a second light-emitting layer over the first light-emitting layer, the second light-emitting layer comprising a second compound and a second host material, wherein the second compound is capable of converting an energy of a triplet excited state of the second compound into a second light;

a third light-emitting layer over the second light-emitting layer, the third light-emitting layer comprising a third compound and a third host material, wherein the third compound is capable of converting an energy of a triplet excited state of the third compound into a third light; and

a second electrode over the third light-emitting layer,

wherein a peak of the emission spectrum of the second compound is longer than a peak of the emission spectrum of the first compound, and

wherein the third host material has higher triplet excitation energy than the first host material and the second host material.

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

wherein the first light is green light,

wherein the second light is red light, and

wherein the third light is blue light.

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

wherein the first electrode is an anode, and

wherein the second electrode is a cathode.

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

wherein the first host material is the same as the second host material.

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

wherein the first compound emits phosphorescence,

wherein the second compound emits phosphorescence, and

wherein the third compound emits phosphorescence.

6. A lighting device comprising:

a lighting portion comprising the light-emitting element according to claim 1; and

a support,

wherein the lighting portion has a curved surface.

7. A light-emitting element comprising:

a first electrode;

a first light-emitting layer over the first electrode, the first light-emitting layer comprising a first compound being capable of emitting green light, a first host material, and a second compound;

a second light-emitting layer over the first light-emitting layer, the second light-emitting layer comprising a third compound being capable of emitting red light, a second host material, and a fourth compound;

a third light-emitting layer over the second light-emitting layer, the third light-emitting layer comprising a fifth compound being capable of emitting blue light and a third host material; and

a second electrode over the third light-emitting layer.

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

wherein the first electrode is an anode, and

wherein the second electrode is a cathode.

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

wherein the first host material is the same as the second host material.

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

wherein the second compound is the same as the fourth compound.

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

wherein the first compound emits phosphorescence,

wherein the third compound emits phosphorescence, and

wherein the fifth compound emits phosphorescence.

12. A lighting device comprising:

a lighting portion comprising the light-emitting element according to claim 7; and

a support,

wherein the lighting portion has a curved surface.