# US 2019/0376550 A1 · Light-Emitting Element, Display Device, Electronic Device, and Lighting Device

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- Number: US 2019/0376550 A1
- Document ID: US20190376550A1
- Status: Published application
- Kind: A1
- Application number: 16/542,589
- Filed: 2019-08-16
- Published: 2019-12-12
- Earliest claimed: 2014-10-10
- Assignees: Semiconductor Energy Laboratory Co., Ltd.
- Applicants: Semiconductor Energy Laboratory Co., Ltd.
- Inventors: Nobuharu Ohsawa; Satoshi Seo
- Web page: https://patentgrep.com/patent/US20190376550A1

## CPC

- H10K 50/11: characterised by the electroluminescent [EL] layers
- C09K 11/06: containing organic luminescent materials
- H10K 50/121: {for assisting energy transfer, e.g. sensitization}
- H10K 85/615: {Polycyclic condensed aromatic hydrocarbons, e.g. anthracene}
- H10K 2101/10: Triplet emission
- H10K 2101/20: Delayed fluorescence emission
- H10K 2101/27: {Combination of fluorescent and phosphorescent emission}
- H10K 2101/30: Highest occupied molecular orbital [HOMO], lowest unoccupied molecular orbital [LUMO] or Fermi energy values
- H10K 2101/90: {Multiple hosts in the emissive layer}
- H10K: ORGANIC ELECTRIC SOLID-STATE DEVICES
- C09K: MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE

## Abstract

A light-emitting element including a fluorescent material as a light-emitting material and having high emission efficiency is provided. The light-emitting element includes a pair of electrodes and an EL layer provided between the pair of electrodes. The EL layer includes a host material and a guest material. The host material is capable of exhibiting thermally activated delayed fluorescence at room temperature. The guest material is capable of exhibiting fluorescence. The second triplet excitation energy level of the guest material is higher than or equal to the lowest singlet excitation energy level of the guest material.

## Claims

### Claim at position 1

1-8. (canceled)

### Claim 9

A light-emitting element comprising:
a pair of electrodes; and
an EL layer provided between the pair of electrodes,
wherein the EL layer comprises a host material and a guest material,
wherein the host material is capable of exhibiting thermally activated delayed fluorescence at room temperature,
wherein the guest material is capable of exhibiting fluorescence,
wherein a second triplet excitation energy level of the guest material is higher than or equal to a lowest triplet excitation energy level of the host material, and
wherein the lowest triplet excitation energy level of the host material is higher than or equal to a lowest triplet excitation energy level of the guest material.

### Claim 10 (depends on 9)

The light-emitting element according to claim 9,
wherein the second triplet excitation energy level of the guest material is higher than or equal to a lowest singlet excitation energy level of the host material.

### Claim 11 (depends on 9)

The light-emitting element according to claim 9, wherein the lowest triplet excitation energy level of the host material is higher than or equal to a lowest singlet excitation energy level of the guest material.

### Claim 12 (depends on 9)

The light-emitting element according to claim 9,
wherein a difference between the lowest triplet excitation energy level of the host material and that of the guest material is higher than or equal to 0.5 eV.

### Claim 13 (depends on 9)

The light-emitting element according to claim 9,
wherein a thermally activated delayed fluorescence emission energy of the host material is higher than or equal to a phosphorescence emission energy of the guest material.

### Claim 14 (depends on 9)

The light-emitting element according to claim 9,
wherein a difference between a thermally activated delayed fluorescence emission energy of the host material and a phosphorescence emission energy of the guest material is higher than or equal to 0.5 eV.

### Claim 15 (depends on 9)

The light-emitting element according to claim 9, wherein the host material has a difference of more than 0 eV and less than or equal to 0.2 eV between a lowest singlet excitation energy level and the lowest triplet excitation energy level.

### Claim 16 (depends on 9)

The light-emitting element according to claim 9, wherein the guest material comprises at least one skeleton selected from anthracene, tetracene, chrysene, pyrene, perylene and acridine, and at least one substituent bonded to the skeleton.

### Claim 17 (depends on 9)

The light-emitting element according to claim 9,
wherein the guest material comprises a skeleton, a first substituent and a second substituent,
wherein the skeleton is selected from anthracene, tetracene, chrysene, pyrene, perylene and acridine, and
wherein a structure of the first substituent is same as that of the second substituent.

### Claim 18 (depends on 9)

A display device comprising:
the light-emitting element according to claim 9; and
any one of a color filter, a seal and a transistor.

### Claim 19 (depends on 18)

An electronic device comprising:
the display device according to claim 18; and
a housing or a touch sensor.

### Claim 20 (depends on 9)

A lighting device comprising:
the light-emitting element according to claim 9; and
a housing or a touch sensor.

### Claim at position 14

21-32. (canceled)