Organic electroluminescent element
View Patent ↗The objective is to provide an organic electroluminescent element with an improved luminous efficiency. The organic electroluminescent element has a structure in which a first light-emitting unit containing a phosphorescent red light-emitting material, a second light-emitting unit containing a phosphorescent yellow light-emitting material, and a third light-emitting unit containing a fluorescent blue light-emitting material are stacked with interlayers in-between. A peak emission wavelength of the phosphorescent yellow light-emitting material is in a range of 530 nm to 570 nm. A peak emission wavelength of the fluorescent blue light-emitting material is in a range of 440 nm to 480 nm. The organic electroluminescent element has a ratio of a yellow emission intensity to a blue emission intensity in a range of 1.0 to 2.0. The organic electroluminescent element further has a ratio of a red emission intensity to the blue emission intensity in a range of 1.5 to 3.0.
1. An organic electroluminescent element comprising a structure comprising:
a first light-emitting unit containing a phosphorescent red light-emitting material;
a second light-emitting unit containing a phosphorescent yellow light-emitting material;
a third light-emitting unit containing a fluorescent blue light-emitting material; and
an interlayer comprising:
a first interlayer provided between the first light-emitting unit and the second light-emitting unit; and
a second interlayer provided between the second light-emitting unit and the third light-emitting unit, wherein:
the first interlayer is configured to inject charges into the first light-emitting unit and the second light-emitting unit,
the second interlayer is configured to inject charges into the second light-emitting unit and the third light-emitting unit,
a peak emission wavelength of the phosphorescent yellow light-emitting material is in a range of 530 nm to 570 nm,
a peak emission wavelength of the fluorescent blue light-emitting material is in a range of 440 nm to 480 nm,
the organic electroluminescent element having a ratio of a yellow emission intensity to a blue emission intensity is in a range of 1.0 to 2.0,
the organic electroluminescent element has a ratio of a red emission intensity to the blue emission intensity in a range of 1.5 to 3.0, and
the first light-emitting unit contains only the phosphorescent red light-emitting material as a light-emitting dopant.
2. The organic electroluminescent element according to claim 1 , wherein at least one of the second light-emitting unit and the third light-emitting unit contains a red light-emitting material.
3. The organic electroluminescent element according to claim 1 , wherein at least one of the first light-emitting unit and the second light-emitting unit contains an energy transfer facilitating material for facilitating transfer of energy to a light-emitting material.
4. The organic electroluminescent element according to claim 3 , wherein the first light-emitting unit contains a phosphorescent yellow light-emitting material as the energy transfer facilitating material.