Light-emitting element, light-emitting apparatus, display, and electronic device
A light-emitting element has a cathode, an anode, a light-emitting portion interposed between the cathode and the anode and having a light-emitting layer that emits light on energization between the cathode and the anode, and a hole-injection layer interposed between and in direct contact with the anode and the light-emitting layer and having a capability of receiving holes, and the hole-injection layer is mainly composed of a benzidine derivative.
1. A light-emitting element comprising:
a cathode;
an anode;
a light-emitting portion interposed between the cathode and the anode and having a light-emitting layer that emits light on energization between the cathode and the anode; and
a hole-injection layer interposed between and in direct contact with the anode and the light-emitting layer and having a capability of receiving holes, wherein:
the hole-injection layer is mainly composed of a benzidine derivative, and the hole-injection layer has an average thickness in the range of 80 nm to 200 nm.
2. The light-emitting element according to claim 1 , wherein the distance between the anode and the cathode is in the range of 150 nm to 300 nm.
3. The light-emitting element according to claim 1 , wherein the anode has the surface thereof on the hole-injection layer side treated with plasma.
4. The light-emitting element according to claim 1 , wherein the anode is composed of indium tin oxide.
5. The light-emitting element according to claim 1 , wherein:
the light-emitting portion has several light-emitting layers; and
the hole-injection layer is interposed between and in direct contact with the anode and the closest light-emitting layer to the anode.
6. The light-emitting element according to claim 5 , wherein:
the light-emitting portion contains first, second, and third light-emitting layers for emission of light in different colors, layered in this order from the side of the anode to the side of the cathode; and
the hole-injection layer is interposed between and in direct contact with the anode and the first light-emitting layer.
7. The light-emitting element according to claim 6 , wherein the first light-emitting layer contains an acene compound.
8. The light-emitting element according to claim 7 , wherein the acene compound is a naphthacene derivative.
9. The light-emitting element according to claim 7 , wherein the content ratio of the acene compound in the first light-emitting layer is in the range of 90 wt % to 99.99 wt %.
10. The light-emitting element according to claim 6 , wherein the light-emitting portion has an intermediate layer interposed between the first and second light-emitting layers.
11. The light-emitting element according to claim 6 , wherein the first light-emitting layer emits red light on energization between the cathode and the anode, and the second and third light-emitting layers emit blue and green light or vice versa on energization between the cathode and the anode.
12. The light-emitting element according to claim 1 , wherein the benzidine derivative has a content ratio in the range of 50 wt % to 100 wt % with respect to the hole-injection layer.
13. A light-emitting apparatus comprising the light-emitting element according to claim 1 .
14. A display comprising the light-emitting apparatus according to claim 13 .
15. An electronic device comprising the display according to claim 14 .
16. A light-emitting element comprising:
a cathode;
an anode;
a light-emitting portion inserted between the cathode and the anode and having a light-emitting layer that emits light on energization between the cathode and the anode; and
a hole-injection layer sandwiched between and in direct contact with the anode and the light-emitting layer and having a capability of receiving holes, wherein:
the hole-injection layer is mainly composed of a benzidine derivative, and
the distance between the anode and the cathode is in the range of 150 nm to 300 nm.
17. The light-emitting element according to claim 16 , wherein the benzidine derivative has a content ratio in the range of 50 wt % to 100 wt % with respect to the hole-injection layer.
18. A light-emitting element comprising:
a cathode;
an anode;
a light-emitting portion inserted between the cathode and the anode and having a light-emitting layer that emits light on energization between the cathode and the anode; and
a hole-injection layer sandwiched between and in direct contact with the anode and the light-emitting layer and having a capability of receiving holes, wherein:
the hole-injection layer is mainly composed of a benzidine derivative,
the light-emitting portion contains first, second, and third light-emitting layers for emission of light in different colors, layered in this order from the side of the anode to the side of the cathode; and
the hole-injection layer is interposed between and in direct contact with the anode and the first light-emitting layer.
19. The light-emitting element according to claim 18 , wherein the benzidine derivative has a content ratio in the range of 50 wt % to 100 wt % with respect to the hole-injection layer.