Thermal activated 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 thermalactivated delayed fluorescence compound, the energy level difference of the singlet state and the triplet state is relatively low, it is beneficial for increasing of reverse intersystem crossing ratefrom 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 fluorescence compound also possesses relatively high S1 to S0 electron transition oscillator strength, so that the thermal activated delayed fluorescence compound possesses relatively high optical radiation transitionrate, 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 electroluminescent materials are classified into fluorescent electroluminescent materials and phosphorescent electroluminescent materials. Among them, phosphorescent electroluminescent materials can utilize the energy of all excitons through the heavy metal effect, so they have greater advantages. In 2009, thermally activated delayed fluorescence compounds, namely TADF (Thermally activated delayed fluorescence) materials, were proposed and applied in the technical field of organic electroluminescent devices. Under thermal excitation, this kind of fluorescent compound can use the reverse gap crossing of triplet excitons to obtain 100% singlet excitons, which not only avoids the use of expensive heavy metal complexes, but also has device efficien...

AI Technical Summary

Problems solved by technology

Although such traditional molecular design has obtained the ideal ΔE ST value, but the complete separation of HOMO and LUMO orbitals and the embedding of barrier units cause the integral of electron exchange between HOMO and LUMO in the molecule to approach 0, that is, the radiative transition rate constant Kr@S1->S in the molecule becomes smaller, Not conducive to the improvement of the luminous efficiency of molecules

In addition, the intermediate barrier unit makes the molecular structure more flexible, thereby reducing the light radiation transition constant of the molecule and the moment intensity during the transition (Kr is proportional to the moment intensity f)

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