Organic electroluminescence element
View Patent ↗The present invention provides an organic electroluminescence element having at least a light-emitting layer disposed between a pair of electrodes, wherein the light-emitting layer includes at least two electron transporting materials and a hole transporting host material, with at least one of the electron transporting materials being an electron transporting light-emitting material, and a total concentration of the at least two electron transporting materials in the light-emitting layer decreases from a cathode side toward an anode side.
1. An organic electroluminescence element comprising at least a light-emitting layer disposed between a pair of electrodes, wherein the light-emitting layer comprises at least two electron transporting materials and a hole transporting host material, with at least one of the electron transporting materials being an electron transporting light-emitting material, each of the at least two electron transporting materials is present over the entire region of the light-emitting layer, and a concentration of each of the at least two electron transporting materials in the light-emitting layer decreases from a cathode side toward an anode side; and
wherein the total concentration of the at least two electron transporting materials is 20% by weight or less in an interface region of the light-emitting layer on the anode side and the total concentration of the at least two electron transporting materials is 80% by weight or more in an interface region of the light-emitting layer on the cathode side.
2. The organic electroluminescence element according to claim 1 , wherein the electron transporting light-emitting material is a phosphorescent light-emitting material.
3. The organic electroluminescence element according to claim 2 , wherein the phosphorescent light-emitting material is a metal complex having a tri- or higher-dentate ligand.
4. The organic electroluminescence element according to claim 1 , wherein the hole transporting host material is a carbazole derivative or an indole derivative.
5. The organic electroluminescence element according to claim 4 , wherein the hole transporting host material is 1,3-bis(carbazole-9-yl)benzene or a derivative thereof.
6. The organic electroluminescence element according to claim 1 , wherein the at least two electron transporting materials comprise the electron transporting light-emitting material and an electron transporting host material; and
wherein the electron transporting host material is an azole derivative or an azine derivative.
7. The organic electroluminescence element according to claim 1 , wherein a peak wavelength of an emission spectrum is 430 nm or more, and less than 480 nm.
8. The organic electroluminescence element according to claim 1 , wherein the total concentration of the at least two electron transporting materials in the light-emitting layer decreases stepwise from the cathode side toward the anode side.