Light-emitting device, light-emitting apparatus, electronic device, and lighting device
To provide a light-emitting device not only including a light-emitting layer in which energy is efficiently transferred from a host material to a guest material but also having high reliability. The light-emitting device not only includes a light-emitting layer in which the T1 levels and the S1 levels of a host material and a guest material fall within certain ranges so that energy can be efficiently transferred from the host material to the guest material and but also has improved reliability.
1. A light-emitting device comprising:
an EL layer between a pair of electrodes,
wherein the EL layer includes a light-emitting layer,
wherein the light-emitting layer contains a first organic compound, a second organic compound, and a light-emitting substance,
wherein a T1 level (T D(edge) ) and a T1 level (T H(edge) ) satisfy Formula (1):
0.07 eV≤ T H(edge) −T D(edge) ≤0.27 eV (1),
wherein a difference between an S1 level (S′ H(edge) ) and the T1 level (T H(edge) ) satisfies Formula (2):
0.2 eV≤ S′ H(edge) −T H(edge) ≤0.5 eV (2)
wherein the T1 level (T H(edge) ) represents the lower of T1 levels derived from emission edges on a short wavelength side of phosphorescent spectra of the first organic compound and the second organic compound,
wherein the T1 level (T D(edge) ) represents a T1 level derived from an absorption edge of an absorption spectrum of the light-emitting substance, and
wherein the S1 level (S′ H(edge) ) represents an S1 level derived from an emission edge on a short wavelength side of a fluorescent spectrum of a mixed material of the first organic compound and the second organic compound.
2. A light-emitting device comprising:
an EL layer between a pair of electrodes,
wherein the EL layer includes a light-emitting layer,
wherein the light-emitting layer contains a first organic compound, a second organic compound, and a light-emitting substance,
wherein a T1 level (T D(edge) ) and a T1 level (T H(edge) ) satisfy Formula (3):
0.07 eV≤ T H(edge) −T D(edge) ≤0.17 eV (3)
wherein a difference between an S1 level (S′ H(edge) ) and the T1 level (T H(edge) ) satisfies Formula (4):
0.2 eV≤ S′ H(edge) −T H(edge) ≤0.5 eV (4)
wherein the T1 level (T H(edge) ) represents the lower of T1 levels derived from emission edges on a short wavelength side of phosphorescent spectra of the first organic compound and the second organic compound,
wherein the T1 level (T D(edge) ) represents a T1 level derived from an absorption edge of an absorption spectrum of the light-emitting substance, and
wherein the S1 level (S′ H(edge) ) represents an S1 level derived from an emission edge on a short wavelength side of a fluorescent spectrum of a mixed material of the first organic compound and the second organic compound.
3. The light-emitting device according to claim 1 ,
wherein the first organic compound and the second organic compound form an exciplex in combination, and
wherein the S1 level (S′ H(edge) ) is derived from an emission edge on a short wavelength side of a fluorescent spectrum of the exciplex.
4. The light-emitting device according to claim 1 , wherein the first organic compound is a π-electron deficient heteroaromatic compound.
5. The light-emitting device according to claim 1 ,
wherein the first organic compound has a pyridine ring structure, a diazine ring structure, or a triazine ring structure.
6. The light-emitting device according to claim 1 ,
wherein the first organic compound has a structure where an aromatic ring is fused to a furan ring of a furodiazine skeleton.
7. The light-emitting device according to claim 1 ,
wherein the light-emitting substance is a phosphorescent substance.
8. The light-emitting device according to claim 1 ,
wherein the second organic compound is a carbazole derivative.
9. The light-emitting device according to claim 8 ,
wherein the carbazole derivative is a bicarbazole derivative.
10. The light-emitting device according to claim 8 ,
wherein the carbazole derivative is a 3,3′-bicarbazole derivative.
11. A light-emitting apparatus comprising:
the light-emitting device according to claim 1 ; and
an FPC.
12. An electronic device comprising:
the light-emitting apparatus according to claim 11 ; and
at least one of a microphone, a camera, an operation button, an external connection portion, and a speaker.
13. A lighting device comprising:
the light-emitting device according to claim 1 ; and
at least one of a housing and a cover.
14. The light-emitting device according to claim 2 ,
wherein the first organic compound and the second organic compound form an exciplex in combination, and
wherein the S1 level (S′ H(edge) ) is derived from an emission edge on a short wavelength side of a fluorescent spectrum of the exciplex.
15. The light-emitting device according to claim 2 , wherein the first organic compound is a π-electron deficient heteroaromatic compound.
16. The light-emitting device according to claim 2 ,
wherein the first organic compound has a pyridine ring structure, a diazine ring structure, or a triazine ring structure.
17. The light-emitting device according to claim 2 ,
wherein the first organic compound has a structure where an aromatic ring is fused to a furan ring of a furodiazine skeleton.
18. The light-emitting device according to claim 2 ,
wherein the light-emitting substance is a phosphorescent substance.
19. The light-emitting device according to claim 2 ,
wherein the second organic compound is a carbazole derivative.
20. The light-emitting device according to claim 19 ,
wherein the carbazole derivative is a bicarbazole derivative.
21. The light-emitting device according to claim 19 ,
wherein the carbazole derivative is a 3,3′-bicarbazole derivative.