US Patent 9748313 Organic electroluminescent element

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.