Thermal activation sensitized phosphorescence organic electroluminescent light emitting device

The present invention discloses a thermal activation sensitized phosphorescence organic electroluminescent light emitting device which comprises a light emitting layer. The main body material of the light emitting layer is formed by two materials which are a hole-transporting material and an electron-transporting material. At least one material in the two materials is a thermal activation delay fluorescence material. The main body material is doped with a phosphorescent dye whose proportion is smaller than 15% by weight in the light emitting layer. The triplet energy level of the CT excitation state of the thermal activation delay fluorescence material is higher than the triplet energy level of an n-pi excitation state, and the difference is between 0 and 0.3 eV. Or, the triplet energy level of the CT excitation state of the thermal activation delay fluorescence material is higher than the triplet energy level of the n-pi excitation state, and the difference is larger than 1.0 eV, and the difference between the second triplet energy level of the n-pi excitation state and the first singlet energy level of the CT excitation state is between -0.1 eV and 0.1 eV.