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

• US 20140191220A1
• Filed: 01/08/2014
• Published: 07/10/2014
• Est. Priority Date: 01/10/2013
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Seo, Satoshi, Watabe, Takeyoshi
• Granted Patent: US 9,391,290 B2
• Time in Patent Office: Days
• US Class Current: 257/40
• CPC Class Codes: H10K 2101/00 Properties of the organic materials covered by group H10K85/00
• CPC Class Codes: H10K 2101/10 Triplet emission
• CPC Class Codes: H10K 2101/90 Multiple hosts in the emissive layer
• CPC Class Codes: H10K 2102/361 Temperature
• CPC Class Codes: H10K 50/11 characterised by the electroluminescent [EL] layers
• CPC Class Codes: H10K 50/121 for assisting energy transfer, e.g. sensitization
• CPC Class Codes: H10K 59/12 Active-matrix OLED [AMOLED] displays
• 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 85/631 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 85/636 comprising heteroaromatic 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 of the present invention can have sufficiently high emission efficiency with a structure including a host material being able to remain chemically stable even if a phosphorescent compound having higher emission energy is used as a guest material. The relation between the relative emission intensity and the emission time of light emission obtained from the host material and the guest material contained in a light-emitting layer is represented by a multicomponent decay curve. The relative emission intensity of the slowest component of the multicomponent decay curve becomes 1/100 for a short time within a range where the slowest component is not interfered with by quenching of the host material (the emission time of the slowest component is preferably less than or equal to 15 μsec); thus, sufficiently high emission efficiency can be obtained.

Claims

1. A light-emitting device comprising:

a light-emitting layer,

wherein emission time-dependence of emission intensity of the light-emitting device is represented by a multicomponent decay curve, and

wherein an emission time of a slowest component of the multicomponent decay curve is less than or equal to 15 μ

sec where the emission time is a time required for the emission intensity to become 1/100.

2. The light-emitting device according to claim 1, wherein the light-emitting device is configured to emit blue light.

3. An electronic device comprising the light-emitting device according to claim 1.

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

5. A light-emitting device comprising:

a light-emitting layer comprising at least a first organic compound and a second organic compound,

wherein the first organic compound and the second organic compound are selected so that emission time-dependence of emission intensity of the light-emitting device is represented by a multicomponent decay curve, and

wherein an emission time of a slowest component of the multicomponent decay curve is less than or equal to 15 μ

sec where the emission time is a time required for the emission intensity to become 1/100.

6. The light-emitting device according to claim 5, wherein the multicomponent decay curve represents at least two components derived from the first organic compound and/or the second organic compound at the time when the emission intensity becomes 1/100.

7. The light-emitting device according to claim 5, wherein the light-emitting device is configured to emit blue light.

8. An electronic device comprising the light-emitting device according to claim 5.

9. A lighting device comprising the light-emitting device according to claim 5.

10. A light-emitting device comprising:

a light-emitting layer comprising a guest material and a host material,

wherein a T1 level of the guest material is equal to or lower than a T1 level of the host material,

wherein the guest material and the host material are selected so that emission time-dependence of emission intensity of the light-emitting device is represented by a multicomponent decay curve, and

wherein an emission time of a slowest component of the multicomponent decay curve is less than or equal to 15 μ

sec where the emission time is a time required for the emission intensity to become 1/100.

11. The light-emitting device according to claim 10, wherein a difference between the T1 level of the guest material and the T1 level of the host material is greater than or equal to 0 eV and less than or equal to 0.2 eV.

12. The light-emitting device according to claim 10, wherein the guest material is a phosphorescence compound.

13. The light-emitting device according to claim 10, wherein the multicomponent decay curve represents at least two components derived from the guest material at the time when the emission intensity becomes 1/100.

14. The light-emitting device according to claim 10, wherein the light-emitting device is configured to emit blue light.

15. An electronic device comprising the light-emitting device according to claim 10.

16. A lighting device comprising the light-emitting device according to claim 10.