Thermal delayed fluorescence compound, and applications thereof

Abstract

The invention belongs to the technical field of organic electroluminescent material, and discloses a thermal activated delayed fluorescence compound, and applications thereof. According to the thermaldelayed fluorescence compound, the energy level difference of the singlet state and the triplet state is equal to or lower than 300meV, it is beneficial for increasing of reverse intersystem crossingrate from triplet exciton to singlet exciton; and in addition, when the relatively low singlet state and triplet state energy level different is maintained, the thermal activated delayed fluorescencecompound also possesses relatively high S1 to S0 electron transition oscillator strength, so that the thermal activated delayed fluorescence compound possesses relatively high optical radiation transition rate, and it is beneficial for increasing of compound luminescence efficiency.

Description

technical field [0001] The invention relates to the technical field of organic electroluminescent devices, in particular to a thermally activated delayed fluorescent compound and its application. Background technique [0002] Organic electroluminescence can be divided into fluorescence and phosphorescence electroluminescence. According to the spin quantum statistical theory, the formation probability ratio of singlet excitons and triplet excitons is 1:3, that is, singlet excitons only account for 25% of the "electron-hole pairs". Therefore, the fluorescence from the radiative transition of singlet excitons only accounts for 25% of the total input energy, while the electroluminescence of phosphorescent materials can utilize the energy of all excitons through the heavy metal effect, thus having a greater superiority. Most of the current phosphorescent electroluminescent devices adopt the host-guest structure, that is, the phosphorescent material is doped into the host materi...

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Problems solved by technology

[0004] However, there are still many deficiencies in such TADF-based materials and OLED devices, such as limited types of materials, and the stability of the devices needs to be improved.

For example, to achieve ΔE ST (The energy level difference between the singlet state and the triplet state) is less than 0.3eV. Many TADF materials need to completely separate the HOMO-LUMO orbitals in the design, which leads to a decrease in the optical radiation transition rate of the TADF material, which also affects the material properties.

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