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

Abstract

To provide a multicolor light-emitting device having high luminous efficiency.SOLUTION: A light-emitting device contains a material serving as an energy donor, a fluorescent material, and a phosphorescent material in a light-emitting layer. The material serving as an energy donor has a function of converting triplet excitation energy into light emission. A molecular structure of the fluorescent material includes a luminophore and protecting groups, and five or more protecting groups are contained in one molecule of a guest material. Introduction of protecting groups into molecules inhibits triplet excitation energy transfer from the material serving as an energy donor to the light-emitting material by a Dexter mechanism. Each of the protecting groups is an alkyl group or a branched-chain alkyl group. In the light-emitting device, light emission is obtained from both the fluorescent material and the phosphorescent material.SELECTED DRAWING: Figure 2

Claims

1. A light-emitting element having a light-emitting layer between a pair of electrodes, the light-emitting layer includes a first material having a function of converting triplet excitation energy into light emission, a second material having a function of converting singlet excitation energy into light emission, and a third material having a function of converting triplet excitation energy into light emission; the first material includes a first organic compound and a second organic compound; the first organic compound and the second organic compound are a combination that forms an exciplex, the first organic compound is a compound exhibiting phosphorescence, the second material comprises a luminophore and five or more protecting groups; the luminophore is a fused aromatic ring or a fused heteroaromatic ring; the five or more protecting groups each independently include one of an alkyl group having from 1 to 10 carbon atoms, a substituted or unsubstituted cycloalkyl group having from 3 to 10 carbon atoms, or a trialkylsilyl group having from 3 to 12 carbon atoms; A light-emitting element, in which light is emitted from both the second material and the third material.

2. In claim 1, a light-emitting element, wherein at least four of the five or more protecting groups are each independently any one of an alkyl group having 3 to 10 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 10 carbon atoms, and a trialkylsilyl group having 3 to 12 carbon atoms.

3. A light-emitting element having a light-emitting layer between a pair of electrodes, the light-emitting layer includes a first material having a function of converting triplet excitation energy into light emission, a second material having a function of converting singlet excitation energy into light emission, and a third material having a function of converting triplet excitation energy into light emission; the first material includes a first organic compound and a second organic compound; the first organic compound and the second organic compound are a combination that forms an exciplex, the first organic compound is a compound exhibiting phosphorescence, the second material having a luminophore and four protecting groups; the luminophore is a fused aromatic ring or a fused heteroaromatic ring; the four protecting groups are not directly bonded to the fused aromatic ring or to the fused aromatic ring; the four protecting groups each independently have any one of an alkyl group having from 3 to 10 carbon atoms, a substituted or unsubstituted cycloalkyl group having from 3 to 10 carbon atoms, and a trialkylsilyl group having from 3 to 12 carbon atoms; A light-emitting element, in which light is emitted from both the second material and the third material.

4. A light-emitting element having a light-emitting layer between a pair of electrodes, the light-emitting layer includes a first material having a function of converting triplet excitation energy into light emission, a second material having a function of converting singlet excitation energy into light emission, and a third material having a function of converting triplet excitation energy into light emission; the first material includes a first organic compound and a second organic compound; the first organic compound and the second organic compound are a combination that forms an exciplex, the first organic compound is a compound exhibiting phosphorescence, the second material comprises a luminophore and two or more diarylamino groups; the luminophore is a fused aromatic ring or a fused heteroaromatic ring; the fused aromatic ring or the fused heteroaromatic ring is bonded to the two or more diarylamino groups; each of the aryl groups in the two or more diarylamino groups independently has at least one protecting group; each of the protecting groups independently has one of an alkyl group having from 3 to 10 carbon atoms, a substituted or unsubstituted cycloalkyl group having from 3 to 10 carbon atoms, or a trialkylsilyl group having from 3 to 12 carbon atoms; A light-emitting element, in which light is emitted from both the second material and the third material.

5. A light-emitting element having a light-emitting layer between a pair of electrodes, the light-emitting layer includes a first material having a function of converting triplet excitation energy into light emission, a second material having a function of converting singlet excitation energy into light emission, and a third material having a function of converting triplet excitation energy into light emission; the first material includes a first organic compound and a second organic compound; the first organic compound and the second organic compound are a combination that forms an exciplex, the first organic compound is a compound exhibiting phosphorescence, the second material comprises a luminophore and two or more diarylamino groups; the luminophore is a fused aromatic ring or a fused heteroaromatic ring; the fused aromatic ring or the fused heteroaromatic ring is bonded to the two or more diarylamino groups; each of the aryl groups in the two or more diarylamino groups independently has at least two protecting groups; each of the protecting groups independently has any one of an alkyl group having from 3 to 10 carbon atoms, a substituted or unsubstituted cycloalkyl group having from 3 to 10 carbon atoms, and a trialkylsilyl group having from 3 to 12 carbon atoms; A light-emitting element, in which light is emitted from both the second material and the third material.

6. In claim 4 or claim 5, The light-emitting device, wherein the diarylamino group is a diphenylamino group.

7. In any one of claims 2 to 6, The alkyl group having 3 to 10 carbon atoms is a branched alkyl group.

8. A light-emitting element having a light-emitting layer between a pair of electrodes, the light-emitting layer includes a first material having a function of converting triplet excitation energy into light emission, a second material having a function of converting singlet excitation energy into light emission, and a third material having a function of converting triplet excitation energy into light emission; the first material includes a first organic compound and a second organic compound; the first organic compound and the second organic compound are a combination that forms an exciplex, the first organic compound is a compound exhibiting phosphorescence, the second material comprises a luminophore and a plurality of protecting groups; the luminophore is a fused aromatic ring or a fused heteroaromatic ring; at least one of the atoms constituting the plurality of protecting groups is located directly above one face of the fused aromatic ring or the fused heteroaromatic ring, and at least one of the atoms constituting the plurality of protecting groups is located directly above the other face of the fused aromatic ring or the fused heteroaromatic ring; A light-emitting element, in which light is emitted from both the second material and the third material.

9. A light-emitting element having a light-emitting layer between a pair of electrodes, the light-emitting layer includes a first material having a function of converting triplet excitation energy into light emission, a second material having a function of converting singlet excitation energy into light emission, and a third material having a function of converting triplet excitation energy into light emission; the first material includes a first organic compound and a second organic compound; the first organic compound and the second organic compound are a combination that forms an exciplex, the first organic compound is a compound exhibiting phosphorescence, the second material comprises a luminophore and two or more diphenylamino groups; the luminophore is a fused aromatic ring or a fused heteroaromatic ring; the condensed aromatic ring or the condensed heteroaromatic ring is bonded to the two or more diphenylamino groups; the phenyl groups in the two or more diphenylamino groups each independently have a protecting group at the 3-position and the 5-position; each of the protecting groups independently has one of an alkyl group having from 3 to 10 carbon atoms, a substituted or unsubstituted cycloalkyl group having from 3 to 10 carbon atoms, or a trialkylsilyl group having from 3 to 12 carbon atoms; A light-emitting element, in which light is emitted from both the second material and the third material.

10. In claim 9, The alkyl group having 3 to 10 carbon atoms is a branched alkyl group.

11. In claim 7 or claim 10, The branched alkyl group has a quaternary carbon.

12. In any one of claims 1 to 11, The light-emitting device, wherein the fused aromatic ring or the fused heteroaromatic ring contains any one of naphthalene, anthracene, fluorene, chrysene, triphenylene, tetracene, pyrene, perylene, coumarin, quinacridone, and naphthobisbenzofuran.

13. In any one of claims 1 to 12, A light-emitting element, wherein a peak wavelength of an emission spectrum of the first material is located on the shorter wavelength side than a peak wavelength of an emission spectrum of the second material.

14. In any one of claims 1 to 13, A light-emitting device, wherein an emission spectrum of the first material overlaps with an absorption band on the longest wavelength side of an absorption spectrum of the second material.

15. In any one of claims 1 to 14, A light-emitting element, wherein the concentration of the second material is higher than the concentration of the third material in the light-emitting layer.

16. In any one of claims 1 to 15, The third material is a compound that exhibits phosphorescence.

17. In any one of claims 1 to 16, A light-emitting element, wherein a peak wavelength of an emission spectrum of the second material is located on the shorter wavelength side than a peak wavelength of an emission spectrum of the third material.

18. A light-emitting element according to any one of claims 1 to 17, and at least one of a color filter and a transistor.

19. A light emitting device according to claim 18; An electronic device having at least one of a housing or a display unit.

20. A light-emitting element according to any one of claims 1 to 17, A lighting device having a housing.

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