Organic electroluminescent element having plurality of light emitting layers with specific thicknesses
View Patent ↗In an organic EL element, a light-emitting layer is divided into at least three layers in a thickness direction including a light-emitting layer A close to an anode, a light-emitting layer C close to a cathode and a light-emitting layer B between the light-emitting layers A and C, wherein in one embodiment a thickness (a) of the light-emitting layer A, a thickness (c) of the light-emitting layer C and a thickness (b) of the light-emitting layer B satisfy the relationship of a<b<c, and an intermediate layer containing an electron blocking material is disposed between the divided light-emitting layers; and in another embodiment, the relationship of a>b>c is satisfied, and an intermediate layer containing a hole blocking material is disposed between the divided light-emitting layers.
1. An organic electroluminescent element, comprising at least a light-emitting layer interposed between a pair of electrodes, wherein;
the light-emitting layer is divided into at least three layers in a thickness direction thereof including a light-emitting layer A close to an anode, a light-emitting layer C close to a cathode and a light-emitting layer B between the light-emitting layer A and the light-emitting layer C;
a thickness (a) of the light-emitting layer A, a thickness (c) of the light-emitting layer C and a thickness (b) of the light-emitting layer B satisfy the relationship of a<b<c; and
an intermediate layer containing an electron blocking material is disposed between the divided light-emitting layers.
2. The organic electroluminescent element according to claim 1 , wherein an Ea value (electron affinity) of the electron blocking material is smaller than a smallest Ea value of materials constituting the light-emitting layers.
3. The organic electroluminescent element according to claim 1 , wherein an electron mobility of the electron blocking material is slower than an electron mobility of a material in which electrons mainly flow among materials constituting the light-emitting layers.
4. The organic electroluminescent element according to claim 1 , wherein a light-emitting material of the light-emitting layer is a phosphorescent material.
5. The organic electroluminescent element according to claim 1 , wherein the intermediate layer contains a light-emitting material.
6. The organic electroluminescent element of claim 5 , wherein the light-emitting material that the intermediate layer contains is a phosphorescent material.
7. An organic electroluminescent element, comprising at least a light-emitting layer interposed between a pair of electrodes, wherein;
the light-emitting layer is divided into at least three layers in a thickness direction thereof including a light-emitting layer A close to an anode, a light-emitting layer C close to a cathode and a light-emitting layer B between the light-emitting layer A and the light-emitting layer C;
a thickness (a) of the light-emitting layer A, a thickness (c) of the light-emitting layer C and a thickness (b) of the light-emitting layer B satisfy the relationship of a>b>c; and
an intermediate layer containing a hole blocking material is disposed between the divided light-emitting layers.
8. The organic electroluminescent element according to claim 7 , wherein an Ip value (ionization potential) of the hole blocking material is larger than a largest Ip value of materials constituting the light-emitting layers.
9. The organic electroluminescent element according to claim 7 , wherein a hole mobility of the hole blocking material is slower than a hole mobility of materials in which holes mainly flow among materials constituting the light-emitting layers.
10. The organic electroluminescent element according to claim 7 , wherein a light-emitting material of the light-emitting layer is a phosphorescent material.
11. The organic electroluminescent element according to claim 7 , wherein the intermediate layer contains a light-emitting material.
12. The organic electroluminescent element according to claim 11 , wherein the light-emitting material that the intermediate layer contains is a phosphorescent material.