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

{
  "publication_number": "US12004359B2",
  "country": "US",
  "kind": "B2",
  "title": "Light-emitting element, display device, electronic device, and lighting device",
  "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": [
    "1. 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 light-emitting layer, wherein the light-emitting layer comprises a host material and a guest material, wherein the host material comprises a first organic compound and a second organic compound, wherein an exciplex formed by the first organic compound and the second organic compound 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 exciplex, and wherein the lowest triplet excitation energy level of the exciplex is higher than or equal to a lowest triplet excitation energy level of the guest material.",
    "2. The light-emitting element according to claim 1, 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 exciplex.",
    "3. The light-emitting element according to claim 1, wherein the lowest triplet excitation energy level of the exciplex is higher than or equal to a lowest singlet excitation energy level of the guest material.",
    "4. The light-emitting element according to claim 1, wherein a difference between the lowest triplet excitation energy level of the exciplex and the lowest triplet excitation energy level of the guest material is higher than or equal to 0.5 eV.",
    "5. The light-emitting element according to claim 1, wherein a thermally activated delayed fluorescence emission energy of the exciplex is higher than or equal to a phosphorescence emission energy of the guest material.",
    "6. The light-emitting element according to claim 1, wherein a difference between a thermally activated delayed fluorescence emission energy of the exciplex and a phosphorescence emission energy of the guest material is higher than or equal to 0.5 eV.",
    "7. The light-emitting element according to claim 1, wherein the exciplex 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.",
    "8. The light-emitting element according to claim 1, 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.",
    "9. The light-emitting element according to claim 1, 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.",
    "10. A display device comprising: the light-emitting element according to claim 1; and any one of a color filter, a seal and a transistor.",
    "11. An electronic device comprising: the display device according to claim 10; and a housing or a touch sensor.",
    "12. A lighting device comprising: the light-emitting element according to claim 1; and a housing or a touch sensor."
  ],
  "description_excerpt": "This application is a divisional of copending U.S. application Ser. No. 16/542,589, filed on Aug. 16, 2019 which is a divisional of U.S. application Ser. No. 14/878,376, filed on Oct. 8, 2015 (now abandoned), which are all incorporated herein by reference.\n\nOne embodiment of the present invention relates to a light-emitting element in which a light-emitting layer capable of providing light emission by application of an electric field is provided between a pair of electrodes, and also relates to a display device, an electronic device, and a lighting device including the light-emitting element.\n\nNote that one embodiment of the present invention is not limited to the above technical field. The technical field of one embodiment of the invention disclosed in this specification and the like relates to an object, a method, or a manufacturing method. In addition, one embodiment of the present invention relates to a process, a machine, manufacture, or a composition of matter. Specifically, examples of the technical field of one embodiment of the present invention disclosed in this specification include a semiconductor device, a display device, a liquid crystal display device, a light-emitting device, a lighting device, a power storage device, a storage device, a method for driving any of them, and a method for manufacturing any of them.\n\nIn recent years, research and development have been extensively conducted on light-emitting elements using electroluminescence (EL). In a basic structure of such a light-emitting element, a layer containing a light-emitting substance (an EL layer) is interposed between a pair of electrodes.",
  "cpc": [
    "H10K 50/11",
    "C07C 15/28",
    "C09K 11/06",
    "C09K 2211/1003",
    "F21Y 2105/00",
    "H10K 2101/10",
    "H10K 2101/20",
    "H10K 2101/27",
    "H10K 2101/30",
    "H10K 2101/90",
    "H10K 50/121",
    "H10K 50/805",
    "H10K 50/8426",
    "H10K 59/38",
    "H10K 59/40",
    "H10K 85/615",
    "H10K 85/633",
    "H10K 85/6572"
  ],
  "ipc": [
    "C09K 11/06",
    "H10K 99/00",
    "H10K 50/11",
    "H10K 50/12",
    "H10K 85/60"
  ],
  "assignees": [
    "Semiconductor Energy Laboratory Co Ltd"
  ],
  "inventors": [
    "Nobuharu Ohsawa",
    "Satoshi Seo"
  ],
  "filing_date": "2022-11-17",
  "publication_date": "2024-06-04",
  "grant_date": "2024-06-04",
  "priority_date": "2014-10-10",
  "application_number": "US-202217989000-A",
  "family_id": "55656051",
  "cited_by_count": 1,
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