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

• US 20150333283A1
• Filed: 05/11/2015
• Published: 11/19/2015
• Est. Priority Date: 05/13/2014
• Status: Abandoned Application

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: ISHISONE, Takahiro, SEO, Satoshi, NONAKA, Yusuke, OHSAWA, Nobuharu
• Application Number:
  US14/709,008
• Publication Number:
  US 20150333283A1
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: H10K 2101/10 Triplet emission
• CPC Class Codes: H10K 2101/27 Combination of fluorescent and phosphorescent emission
• CPC Class Codes: H10K 2101/40 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 50/131 with spacer layers between the electroluminescent layers
• CPC Class Codes: H10K 85/342 comprising iridium
• CPC Class Codes: H10K 85/633 comprising polycyclic condensed aromatic hydrocarbons as substituents on the nitrogen atom

Abstract

Provided is a light-emitting element which includes a first electrode, a second electrode over the first electrode, and first and second light-emitting layers therebetween. The first light-emitting layer contains a first host material and a first light-emitting material, and the second light-emitting layer contains a second host material and a second light-emitting material. The first light-emitting material is a fluorescent material, and the second light-emitting material is a phosphorescent material. The level of the lowest triplet excited state (T₁ level) of the first light-emitting material is higher than the T₁ level of the first host material. A light-emitting device, an electronic device, and a lighting device including the light-emitting element are further provided.

Claims

1. A light-emitting element comprising:

a first electrode;

a second electrode over the first electrode; and

a first light-emitting layer and a second light-emitting layer between the first electrode and the second electrode,

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

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

wherein the first light-emitting material is a fluorescent material, and the second light-emitting material is a phosphorescent material, and

wherein a T₁ level of the first light-emitting material is higher than a T₁ level of the first host material.

2. 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.

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

wherein the first light-emitting layer and the second light-emitting layer are separated from each other.

4. The light-emitting element according to claim 1, further comprising a layer between the first light-emitting layer and the second light-emitting layer,

wherein the layer comprises a hole-transport material and an electron-transport material.

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

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

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

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

8. A light-emitting element comprising:

a first electrode;

a second electrode over the first electrode;

a first light-emitting unit and a second light-emitting unit between the first electrode and the second electrode; and

an interlayer between the first light-emitting unit and the second light-emitting unit,

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

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

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

wherein the first light-emitting material is a fluorescent material and the second light-emitting material is a phosphorescent material, and

wherein a T₁ level of the first light-emitting material is higher than a T₁ level of the first host material.

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

wherein the first light-emitting layer and the second light-emitting layer are in contact with each other.

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

wherein the first light-emitting layer and the second light-emitting layer are separated from each other.

11. The light-emitting element according to claim 8, further comprising a layer between the first light-emitting layer and the second light-emitting layer,

wherein the layer comprises a hole-transport material and an electron-transport material.

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

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

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

wherein the second light-emitting unit is located over the first light-emitting unit.

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

wherein the second light-emitting unit comprises a third light-emitting layer which comprises a third host material and a third light-emitting material.

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

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