Light-emitting device

1 . A light-emitting device comprising:

a first electrode;

a second electrode; and

an organic compound layer between the first electrode and the second electrode,

wherein the organic compound layer comprises a first light-emitting unit, an intermediate layer, and a second light-emitting unit in this order from the first electrode side,

wherein the first light-emitting unit comprises a first light-emitting layer,

wherein the second light-emitting unit comprises a second light-emitting layer,

wherein the intermediate layer comprises a first layer, a second layer, and a third layer in this order from the first electrode side,

wherein the first layer and the second layer are in contact with each other and the second layer and the third layer are in contact with each other,

wherein a spin density of the first layer is lower than or equal to 1×10 17 spins/cm 3 , and

wherein a LUMO level of a material included in the second layer is greater than or equal to −4.30 eV and less than or equal to −3.00 eV.

2 . The light-emitting device according to claim 1 , wherein the material included in the second layer, a material included in the first layer, and a material included in the third layer are different from one another.

3 . The light-emitting device according to claim 1 , wherein a thickness of the second layer is greater than or equal to 1 nm and less than or equal to 10 nm.

4 . The light-emitting device according to claim 1 ,

wherein the first layer comprises a first substance and a second substance, and

wherein the first substance has an acid dissociation constant pK a of 8 or more.

5 . The light-emitting device according to claim 1 ,

wherein the first layer comprises a first substance and a second substance, and

wherein the first substance is an organic compound having any one of a pyrrolidine skeleton, a piperidine skeleton, and a hexahydropyrimidopyrimidine skeleton.

6 . The light-emitting device according to claim 1 ,

wherein the first layer comprises a first substance and a second substance, and

wherein the first substance is an organic compound having a 1,3,4,6,7,8-hexahydro-2H-pyrimido[1,2-a]pyrimidine skeleton.

7 . The light-emitting device according to claim 1 ,

wherein the first layer comprises a first substance and a second substance, and

wherein the second substance is an organic compound having an electron-transport property.

8 . The light-emitting device according to claim 1 , wherein the material included in the second layer is a metal complex.

9 . The light-emitting device according to claim 1 , wherein the material included in the second layer is a phthalocyanine-based metal complex.

10 . The light-emitting device according to claim 1 , wherein the material included in the second layer is 2,3,8,9,14,15-hexafluorodiquinoxalino[2,3-a:2′,3′-c]phenazine.

11 . A light-emitting device comprising:

a first electrode;

a second electrode; and

an organic compound layer between the first electrode and the second electrode,

wherein the organic compound layer comprises a first light-emitting unit, an intermediate layer, and a second light-emitting unit in this order from the first electrode side,

wherein the first light-emitting unit comprises a first light-emitting layer,

wherein the second light-emitting unit comprises a second light-emitting layer,

wherein the intermediate layer comprises a first layer, a second layer, and a third layer in this order from the first electrode side,

wherein the first layer and the second layer are in contact with each other and the second layer and the third layer are in contact with each other,

wherein a spin density of the first layer is lower than or equal to 1×10 17 spins/cm 3 ,

wherein a LUMO level of a material included in the second layer is greater than or equal to −4.30 eV and less than or equal to −3.00 eV, and

wherein the third layer comprises an organic compound having a hole-transport property and a material having an acceptor property.

12 . The light-emitting device according to claim 11 , wherein the material included in the second layer, a material included in the first layer, and a material included in the third layer are different from one another.

13 . The light-emitting device according to claim 11 , wherein a thickness of the second layer is greater than or equal to 1 nm and less than or equal to 10 nm.

14 . The light-emitting device according to claim 11 ,

wherein the first layer comprises a first substance and a second substance, and

wherein the first substance has an acid dissociation constant pK a of 8 or more.

15 . The light-emitting device according to claim 11 ,

wherein the first layer comprises a first substance and a second substance, and

wherein the first substance is an organic compound having any one of a pyrrolidine skeleton, a piperidine skeleton, and a hexahydropyrimidopyrimidine skeleton.

16 . The light-emitting device according to claim 11 ,

wherein the first layer comprises a first substance and a second substance, and

wherein the first substance is an organic compound having a 1,3,4,6,7,8-hexahydro-2H-pyrimido[1,2-a]pyrimidine skeleton.

17 . The light-emitting device according to claim 11 ,

wherein the first layer comprises a first substance and a second substance, and

wherein the second substance is an organic compound having an electron-transport property.

18 . The light-emitting device according to claim 11 , wherein the material included in the second layer is a metal complex.

19 . The light-emitting device according to claim 11 , wherein the material included in the second layer is a phthalocyanine-based metal complex.

20 . The light-emitting device according to claim 11 , wherein the material included in the second layer is 2,3,8,9,14,15-hexafluorodiquinoxalino[2,3-a:2′,3′-c]phenazine.