CROSS-REFERENCE TO RELATED APPLICATIONS

This is the US National Stage of International Patent Application No. PCT/CN2019/078591, filed Mar. 19, 2019, which claims the benefit of Chinese Patent Application No. 201811559197.7, filed Dec. 19, 2018.

FIELD OF DISCLOSURE

The present disclosure relates to displays, and more particularly, to a thermally activated delayed fluorescent material, a method of fabricating the same, and an electroluminescent device.

BACKGROUND OF DISCLOSURE

Organic light emitting diodes (OLEDs) have advantages of self-illumination, fast response times, wide viewing angles, and flexible display, and are dominant in the display field.

A luminescent layer is disposed in the OLED. The luminescent layer is made of a luminescent material having luminescent properties, such as a fluorescent material, a phosphorescent material, and a thermally activated delayed fluorescence (TADF) material.

An electron donor and an electron acceptor in the TADF material are connected by a single bond, wherein the single bond is easy to rotate so as to induce an excessively broad spectrum of the TADF material.

SUMMARY OF DISCLOSURE

An object of the present disclosure is to provide a thermally activated delayed fluorescent material, a method of fabricating the same, and an electroluminescent device, which improves luminous efficiency of the thermally activated delayed fluorescent material.

An embodiment of the present disclosure provides a thermally activated delayed fluorescent material, comprising a molecular structural formula of


and an electron donor and an electron acceptor of the thermally activated delayed fluorescent material are connected with each other by a hexatomic ring, wherein D is the electron acceptor and is


is the electron donor.

In an embodiment, a molecular structural formula of the thermally activated delayed fluorescent material is


and an electron donor and an electron acceptor of the thermally activated delayed fluorescent material are connected with each other by a hexatomic ring, wherein D is the electron acceptor and is


is the electron donor, and X is C(CH3)2, 2H, S, or O.

An embodiment of the present disclosure further provides a method of fabricating a thermally activated delayed fluorescent material, comprising steps of:

adding oxytetrahydrofuran, n-butyllithium, and a solution of boron bromide in diethyl ether in sequence into


to react in a predetermined temperature range so as to obtain a first reaction solution;
purifying the first reaction solution to obtain a first solid;
performing a catalytic reaction to the first solid in methane using a palladium carbon catalyst to obtain a second reaction solution; and
filtering the second reaction solution to obtain the thermally activated delayed fluorescent material.

In an embodiment, the step of purifying the first reaction solution to obtain the first solid comprises steps of:

mixing the first reaction solution with water in the predetermined temperature range to obtain the second solid; and

dissolving the second solid in dichloromethane to obtain a mixture, and adding silica gel and toluene into the mixture for purifying so as to obtain the first solid.

In an embodiment, the first solid is


and the thermally activated delayed fluorescent material is



In an embodiment, the predetermined temperature range is between −75° C. and −80° C.

An embodiment of the present disclosure further provides a method of fabricating a thermally activated delayed fluorescent material, comprising steps of:

adding oxytetrahydrofuran, n-butyllithium, and a solution of boron bromide in diethyl ether in sequence into


to react in a predetermined temperature range so as to obtain a first reaction solution;
adding a reactant into the first reaction solution to obtain a third reaction solution;
purifying the third reaction solution to obtain a third solid;
performing a catalytic reaction to the third solid in methane using a palladium carbon catalyst to obtain a fourth reaction solution; and
filtering the fourth reaction solution to obtain the thermally activated delayed fluorescent material.

In an embodiment, the reactant is meta-Chloroperoxybenzoic acid, the third solid is


and the thermally activated delayed fluorescent material is



In an embodiment, the reactant is sulfur powder, the third solid is



and the thermally activated delayed fluorescent material is



In an embodiment, the predetermined temperature range is between −75° C. and −80° C.

An embodiment of the present disclosure further provides an electroluminescent device, comprising: a substrate layer; an anode layer, a hole transporting layer, a luminescent layer, an electron transporting layer, and a cathode layer disposed in sequence,

wherein the anode layer is used to provide holes;

wherein the hole transporting layer is used to transport the holes to the luminescent layer;

wherein the cathode layer is used to provide electrons;

wherein the electron transporting layer is used to transport the electrons to the luminescent layer;

wherein the luminescent layer comprises the thermally activated delayed fluorescent material described above; and

wherein the luminescent layer is used to recombine the holes and the electrons to generate excitons, and cause the thermally activated delayed fluorescent material to emit light under an effect of the excitons.

In a thermally activated delayed fluorescent material, a method of fabricating the same, and an electroluminescent device in an embodiment of the present disclosure, the electron donor and the electron acceptor are connected with each other by a hexatomic ring, so as to improve a luminous efficiency.

