Light-emitting element, light-emitting device, electronic device, lighting device, lighting system, and guidance system
An object is to provide a light-emitting element with a favorable lifetime. A light-emitting element which includes a first electrode, a second electrode, and an EL layer and in which the EL layer includes a hole-injection layer and first to fourth layers; the hole-injection layer includes an organic acceptor and is positioned between the first electrode and the first layer; the first layer includes a first hole-transport material; the second layer includes a second hole-transport material and is positioned between the first layer and the third layer; the third layer includes a third hole-transport material; the fourth layer includes a host material and a light-emitting material and is positioned between the third layer and the second electrode; the HOMO level of the second hole-transport material is deeper than the HOMO level of the first hole-transport material; the HOMO level of the host material is deeper than the second hole-transport material HOMO level; the HOMO level of the third hole-transport material is deeper than or equal to the HOMO level of the host material; a difference between the HOMO level of the second hole-transport material and the HOMO level of the third hole-transport material is less than or equal to 0.3 eV; and the second hole-transport material is a triarylamine compound having a structure where a dibenzofuran skeleton or a dibenzothiophene skeleton is bonded to nitrogen of an amine directly or via a divalent aromatic hydrocarbon group.
1. A light-emitting element comprising:
an anode;
a first layer over the anode;
a second layer over the first layer;
a third layer over the second layer;
a light-emitting layer over the third layer; and
a cathode over the light-emitting layer,
wherein the first layer comprises an organic compound having at least one electron withdrawing group, wherein the organic compound is optionally a condensed heteroaromatic ring,
wherein the second layer comprises a triarylamine having a fluorenylamine skeleton,
wherein the third layer comprises an organic compound represented by Structural Formula (100) shown below:
2. A light-emitting device comprising:
the light-emitting element according to claim 1 ; and
a transistor or a substrate.
3. An electronic device comprising:
the light-emitting device according to claim 2 ; and
a sensor, an operation button, a speaker, or a microphone.
4. A lighting device comprising:
the light-emitting device according to claim 2 ; and
a housing.
5. A lighting system comprising:
a control portion;
a sensor portion; and
a lighting portion,
wherein the lighting portion includes a plurality of light-emitting device portions,
wherein each light-emitting device portion of the plurality of light-emitting device portions includes one or more light-emitting elements, and
wherein each light-emitting element of the one or more light-emitting elements is the light-emitting element according to claim 1 .
6. The lighting system according to claim 5 , wherein the sensor portion senses presence information or positional information of a user and transmits the information to the control portion, whereby the control portion makes the light-emitting device portion emit light with appropriate emission intensity.
7. The lighting system according to claim 5 , wherein the emission intensity of the light-emitting device portion is sequentially changed with a change in the positional information of the user.
8. A guidance system using the lighting system according to claim 5 .
9. The guidance system according to claim 8 ,
wherein the sensor portion has a function of detecting attribute information of the user, and
wherein the guidance system guides the user in the appropriate direction by changing the emission intensity of the light-emitting device portion on the basis of the attribute information and the positional information of the user.
10. The light-emitting element according to claim 1 , further comprising:
a fourth layer over the third layer,
wherein the fourth layer comprises an organic compound having a carbazole skeleton, a carbazole skeleton and a triphenylene skeleton, a carbazole skeleton and a phenanthrene skeleton, or a carbazole skeleton and a naphthalene skeleton.
11. The light-emitting element according to claim 1 ,
wherein the organic compound in the first layer is 7,7,8,8-tetracyano-2,3,5,6-tetrafluoroquinodimethane, 3,6-difluoro-2,5,7,7,8,8-hexacyanoquinodimethane, chloranil, or 2,3,6,7,10,11-hexacyano-1,4,5,8,9,12-hexaazatriphenylene.