Light-emitting device and light-emitting apparatus
A light-emitting device with high resistance to heat in a fabrication process is provided. The light-emitting device includes an EL layer between an anode and a cathode. The EL layer includes at least a light-emitting layer and an electron-transport layer that includes a first electron-transport layer in contact with the light-emitting layer and a second electron-transport layer in contact with the first electron-transport layer. The first electron-transport layer includes a first heteroaromatic compound including at least one heteroaromatic ring. The second electron-transport layer includes a second heteroaromatic compound that includes at least one heteroaromatic ring and is different from the first heteroaromatic compound. The first heteroaromatic compound has a difference of 20° C. or less between the crystallization temperature (Tpc) of a powder state and the crystallization temperature (Ttc) of a thin film state. The second heteroaromatic compound has a difference of 100° C. or less between Tpc and Ttc.
1 . A light-emitting device comprising:
an EL layer between a first electrode and a second electrode provided over the first electrode,
wherein the EL layer comprises at least a light-emitting layer, an electron-transport layer over the light-emitting layer, and a first electron-injection layer,
wherein the electron-transport layer comprises a first electron-transport layer in contact with the light-emitting layer and a second electron-transport layer over and in contact with the first electron-transport layer,
wherein a first insulating layer includes a part in contact with at least a side surface of the light-emitting layer, a side surface of the first electron-transport layer, and a side surface of the second electron-transport layer,
wherein the first electron-injection layer is provided over the first insulating layer and the second electron-transport layer and under the second electrode,
wherein the first electron-transport layer comprises a first heteroaromatic compound,
wherein the second electron-transport layer comprises a second heteroaromatic compound that is different from the first heteroaromatic compound,
wherein each of the first heteroaromatic compound and the second heteroaromatic compound is represented by any one of Structural Formulae (102) to (116), and
wherein a difference between a crystallization temperature (Tpc) of a powder state and a crystallization temperature (Ttc) of a thin film state of the first heteroaromatic compound is smaller than a difference between a crystallization temperature (Tpc) of a powder state and a crystallization temperature (Ttc) of a thin film state of the second heteroaromatic compound.
2 . The light-emitting device according to claim 1 ,
wherein the difference between the Tpc and the Ttc of the first heteroaromatic compound is less than or equal to 20° C., and
wherein the difference between the Tpc and the Ttc of the second heteroaromatic compound is less than or equal to 100° C.
3 . The light-emitting device according to claim 1 ,
wherein the first electron-injection layer includes a first region covering at least the side surface of the light-emitting layer, the side surface of the first electron-transport layer, and the side surface of the second electron-transport layer, with the part of the first insulating layer provided therebetween.
4 . The light-emitting device according to claim 1 ,
wherein the first heteroaromatic compound is represented by Structural Formula (105), and
wherein the second heteroaromatic compound is represented by Structural Formula (107)
5 . A light-emitting apparatus comprising the light-emitting device according to claim 1 .
6 . A light-emitting apparatus comprising:
a first light-emitting device and a second light-emitting device that are adjacent to each other,
wherein the first light-emitting device comprises a second electrode over a first electrode with a first EL layer between the first electrode and the second electrode,
wherein the first EL layer comprises at least a first light-emitting layer, a first electron-transport layer, a second electron-transport layer, and a first electron-injection layer,
wherein the first electron-transport layer is over and in contact with the first light-emitting layer,
wherein the second electron-transport layer is over and in contact with the first electron-transport layer,
wherein a first insulating layer includes a part in contact with a side surface of the first light-emitting layer, a side surface of the first electron-transport layer, and a side surface of the second electron-transport layer,
wherein the first electron-injection layer is over the second electron-transport layer and the first insulating layer,
wherein the second light-emitting device comprises the second electrode over a third electrode with a second EL layer between the second electrode and the third electrode,
wherein the second EL layer comprises at least a second light-emitting layer, a third electron-transport layer, a fourth electron-transport layer, and the first electron-injection layer,
wherein the third electron-transport layer is over and in contact with the second light-emitting layer,
wherein the fourth electron-transport layer is over and in contact with the third electron-transport layer,
wherein a second insulating layer includes a first part in contact with a side surface of the second light-emitting layer, a side surface of the third electron-transport layer, and a side surface of the fourth electron-transport layer,
wherein the first electron-injection layer is over the fourth electron-transport layer and the second insulating layer,
wherein the first electron-transport layer comprises a first heteroaromatic compound,
wherein the second electron-transport layer comprises a second heteroaromatic compound that is different from the first heteroaromatic compound,
wherein each of the first heteroaromatic compound and the second heteroaromatic compound is represented by any one of Structural Formulae (102) to (116), and
wherein a difference between a crystallization temperature (Tpc) of a powder state and a crystallization temperature (Ttc) of a thin film state of the first heteroaromatic compound is smaller than a difference between a crystallization temperature (Tpc) of a powder state and a crystallization temperature (Ttc) of a thin film state of the second heteroaromatic compound.
7 . The light-emitting apparatus according to claim 6 ,
wherein the difference between the Tpc and the Ttc of the first heteroaromatic compound is less than or equal to 20° C., and
wherein the difference between the Tpc and the Ttc of the second heteroaromatic compound is less than or equal to 100° C.
8 . The light-emitting apparatus according to claim 6 ,
wherein the first electron-injection layer includes:
a first region covering the side surface of the first light-emitting layer, the side surface of the first electron-transport layer, and the side surface of the second electron-transport layer, with the part of the first insulating layer provided therebetween; and
a second region covering the side surface of the second light-emitting layer, the side surface of the third electron-transport layer, and the side surface of the fourth electron-transport layer, with the first part of the second insulating layer provided therebetween.
9 . The light-emitting apparatus according to claim 6 ,
wherein the second insulating layer includes a second part in contact with a second side surface of the first light-emitting layer, a second side surface of the first electron-transport layer, and a second side surface of the second electron-transport layer.
10 . The light-emitting device according to claim 6 ,
wherein the first heteroaromatic compound is represented by Structural Formula (105), and
wherein the second heteroaromatic compound is represented by Structural Formula (107)
11 . The light-emitting device according to claim 6 ,
wherein the third electron-transport layer comprises the first heteroaromatic compound, and
wherein the fourth electron-transport layer comprises the second heteroaromatic compound.
12 . The light-emitting device according to claim 1 ,
wherein each of the first heteroaromatic compound and the second heteroaromatic compound is represented by any one of Structural Formulae (102), (105), and (107), and
13 . The light-emitting device according to claim 6 ,
wherein each of the first heteroaromatic compound and the second heteroaromatic compound is represented by any one of Structural Formulae (102), (105), and (107), and