CN111171012A - Thermal activation delayed fluorescent material, preparation method thereof and organic electroluminescent device - Google Patents

Thermal activation delayed fluorescent material, preparation method thereof and organic electroluminescent device Download PDF

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CN111171012A
CN111171012A CN201910216690.7A CN201910216690A CN111171012A CN 111171012 A CN111171012 A CN 111171012A CN 201910216690 A CN201910216690 A CN 201910216690A CN 111171012 A CN111171012 A CN 111171012A
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郑江波
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Guangdong Juhua Printing Display Technology Co Ltd
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Abstract

The invention relates to a thermal activation delayed fluorescent material, a preparation method thereof and an organic electroluminescent device. The heat-activated delayed fluorescence material is a compound with a structure shown in a formula (I):
Figure DDA0002002302810000011
in the formula (I), R1、R2、R3And R4Each independently a nitrogen-containing electron donating group or a hydrogen atom,and R is1、R2、R3And R4At least one of the nitrogen-containing electron donating groups is a nitrogen-containing electron donating group, and the nitrogen-containing electron donating group is connected with a corresponding benzene ring through an N atom; r5And R6Each independently a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. The series of materials can reduce the energy level difference between the triplet state energy level and the singlet state energy level, thereby improving the luminous quantum efficiency of the device and realizing the luminous efficiency of more than 8 percent.

Description

Thermal activation delayed fluorescent material, preparation method thereof and organic electroluminescent device
Technical Field
The invention relates to the technical field of organic electroluminescent materials, in particular to a thermal activation delayed fluorescent material, a preparation method thereof and an organic electroluminescent device.
Background
Organic electroluminescent diodes (OLEDs) are receiving much attention because of their high efficiency, wide color gamut, low power consumption, rollability, and the like, especially in the display and lighting fields. However, the materials used in the current OLED are generally common fluorescent materials or phosphorescent materials, the common fluorescent materials can only utilize singlet excitons, the theoretical maximum internal quantum efficiency of which is 25%, and the phosphorescent materials can simultaneously utilize singlet excitons and triplet excitons, the theoretical maximum internal quantum efficiency of which can reach 100%, but rare noble metals are required, which is a technical problem of the luminescent materials used in the current OLED.
In recent years, a thermally activated delayed fluorescence material (TADF material) has attracted much attention, and because the theoretical maximum internal quantum efficiency can reach 100%, and because rare noble metals are not used, the production cost is lower, the pure organic TADF material is a very promising organic light-emitting material. However, currently, there are few studies on the thermally activated delayed fluorescence material, and the external quantum efficiency of the thermally activated delayed fluorescence material is still low when the thermally activated delayed fluorescence material is actually applied, so that the requirement of developing an OLED device cannot be met.
Disclosure of Invention
Therefore, it is necessary to provide a thermally activated delayed fluorescence material with high external quantum efficiency to solve the problem of few types of thermally activated delayed fluorescence materials.
A thermally activated delayed fluorescence material, which is a compound having a structure of the following formula (I):
Figure BDA0002002302790000021
in the formula (I), R1、R2、R3And R4Each independently of the others being nitrogen containingAn electron group or a hydrogen atom, and R1、R2、R3And R4At least one of the nitrogen-containing electron donating groups is a nitrogen-containing electron donating group, and the nitrogen-containing electron donating group is connected with a corresponding benzene ring through an N atom; r5And R6Each independently a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.
In one embodiment, the nitrogen-containing electron donating group has the structure
Figure BDA0002002302790000022
Wherein Ar is1And Ar2Independently selected from H or alkyl with 1-24 carbon atoms, and Ar1And Ar2At least one of which is an alkyl group;
or, Ar1And Ar2Independently selected from substituted or unsubstituted phenyl;
or, Ar1And Ar2Independently selected from substituted or unsubstituted phenyl, wherein Ar1、Ar2To the N atom to form a five-membered ring, or Ar1、Ar2N atom and independently of said Ar1And Ar2The other atom of the group is connected to a six-membered ring, said other atom being C, N, S, O or Si; and when the other atom is C, N or Si, the six membered ring is substituted or unsubstituted.
In one embodiment, the Ar1And Ar2Independently selected from substituted or unsubstituted phenyl;
or, Ar1And Ar2Independently selected from substituted or unsubstituted phenyl, wherein Ar1、Ar2To the N atom to form a five-membered ring, or Ar1、Ar2N atom and independently of said Ar1And Ar2The other atom of the group, which is C, N, S, O or Si, is connected to a six-membered ring.
In one embodiment, the nitrogen-containing electron donating group is selected from one of the following groups:
Figure BDA0002002302790000031
wherein, R 'and R' are respectively and independently selected from one of hydrogen atom, methyl, tertiary butyl and aromatic amine group.
In one embodiment, R1、R2、R3And R4Two of them are nitrogen-containing electron donating groups, and the other two are hydrogen atoms.
In one embodiment, the thermally activated delayed fluorescence material is selected from one of compounds having the following structures from formula M1 to formula M30:
Figure BDA0002002302790000032
Figure BDA0002002302790000041
Figure BDA0002002302790000051
Figure BDA0002002302790000061
it is to be noted that t-Bu in the above structural formula represents a tert-butyl group.
Another object of the present invention is to provide a method for preparing a thermally activated delayed fluorescence material, the method comprising the steps of:
reacting a compound of formula (b) with a compound of formula (c) to produce the thermally activated delayed fluorescence material of formula (I);
the structural formulas of the compound of formula (b) and the compound of formula (c) are respectively as follows:
Figure BDA0002002302790000062
wherein, in the formula (b), R1’、R2’、R3' and R4' are each independently a bromine atom orA hydrogen atom, and R1’、R2’、R3' and R4At least one of them is a bromine atom; r5' and R6' are each independently a hydrogen atom or an alkyl group having 1 to 4 carbon atoms;
in the formula (c), Ar1And Ar2Independently selected from H or alkyl with 1-24 carbon atoms, and Ar1And Ar2At least one of which is an alkyl group; or, Ar1And Ar2Independently selected from substituted or unsubstituted phenyl; or, Ar1And Ar2Independently selected from substituted or unsubstituted phenyl, wherein Ar1、Ar2To the N atom to form a five-membered ring, or Ar1、Ar2N atom and independently of said Ar1And Ar2The other atom of the group is connected to a six-membered ring, said other atom being C, N, S, O or Si; and when the other atom is C, N or Si, the six membered ring is substituted or unsubstituted.
In one embodiment, R is1’、R2’、R3' and R4Two of which are bromine atoms and the other two are hydrogen atoms.
In one embodiment, in formula (b), R1' and R2' are all bromine atoms, R3' and R4' are both hydrogen atoms; or, R1' and R2' are both hydrogen atoms, R3' and R4Both are bromine atoms.
It is still another object of the present invention to provide an organic electroluminescent device comprising a cathode, an anode and a light-emitting layer disposed between the cathode and the anode, wherein the light-emitting layer material comprises a host material and a guest material, and the guest material is a compound having a structure of formula (I):
Figure BDA0002002302790000071
in the formula (I), R1、R2、R3And R4Each independently a nitrogen-containing electron donating group or a hydrogen atom, and R1、R2、R3And R4At least one of the nitrogen-containing electron donating groups is a nitrogen-containing electron donating group, and the nitrogen-containing electron donating group is connected with a corresponding benzene ring through an N atom; r5And R6Each independently a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.
In one embodiment, the nitrogen-containing electron donating group has the structure
Figure BDA0002002302790000072
Wherein Ar is1And Ar2Independently selected from H or alkyl with 1-24 carbon atoms, and Ar1And Ar2At least one of which is an alkyl group;
or, Ar1And Ar2Independently selected from substituted or unsubstituted phenyl;
or, Ar1And Ar2Independently selected from substituted or unsubstituted phenyl, wherein Ar1、Ar2To the N atom to form a five-membered ring, or Ar1、Ar2N atom and independently of said Ar1And Ar2The other atom of the group is connected to a six-membered ring, said other atom being C, N, S, O or Si; and when the other atom is C, N or Si, the six membered ring is substituted or unsubstituted.
In one embodiment, the guest material is selected from one of the compounds having the structure of formula M1-formula M30 above.
In one embodiment, the guest material is present in the light-emitting layer in a proportion of 1 wt% to 40 wt%.
The invention has the following beneficial effects:
1) the three-dimensional structure of the thermal activation delayed fluorescence material contains sulfone group and nitrogen-containing electron-donating group, wherein the heterocyclic ring containing the sulfone group positioned in the middle of the three-dimensional structure is used as an electron acceptor (A), the nitrogen-containing electron-donating group part is used as an electron donor (D) to form a D-A structure, the steric hindrance between the electron donor part and the electron acceptor part of the series of materials is large, and the energy level difference between the triplet state energy level and the singlet state energy level can be reduced, so that the external quantum efficiency of light emission of a device can be improved.
2) The six-membered ring of the sulfone group is a non-conjugated ring (the six-membered ring is connected with two alkyls which break conjugation), and the six-membered ring of the sulfone group and the two benzene rings connected with the six-membered ring are also non-conjugated, so that the problem of red shift of a light band when a conjugated structure polymer material emits blue light can be effectively avoided.
3) The series of materials contain six-membered heterocyclic rings containing sulfonyl groups and nitrogen-containing electron-donating groups at two sides to form a D-A-D structure, and the structure is favorable for horizontal dipole orientation, so that the external quantum efficiency can be further improved, and the light-emitting rate of the device is improved; in addition, the thermal activation delayed fluorescence material with the D-A-D structure has good stability, so that the stability of a device can be improved.
4) The thermal activation delayed fluorescent material is applied to an organic electroluminescent device, the luminous quantum efficiency of the device can reach 8% or more, and the CIE of the materialy＜0.10。
Drawings
Fig. 1 is a schematic structural diagram of an organic electroluminescent device according to an embodiment of the present invention.
Detailed Description
In order that the invention may be more fully understood, a more particular description of the invention will now be rendered by reference to specific embodiments thereof that are illustrated in the appended drawings. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.
One embodiment of the present invention provides a thermally activated delayed fluorescence material, which is a heterocyclic derivative containing a sulfone group and has a structure shown in general formula (I),
Figure BDA0002002302790000091
in the formula (I), R1、R2、R3And R4Each independently a nitrogen-containing electron donating group or a hydrogen atom, and R1、R2、R3And R4At least one of the nitrogen-containing electron donating groups is a nitrogen-containing electron donating group, and the nitrogen-containing electron donating group is connected with a corresponding benzene ring through an N atom; r5And R6Each independently a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.
The thermal activation delayed fluorescent material is a pure organic thermal activation delayed fluorescent material, the three-dimensional structure of the series of materials contains sulfone group and nitrogen-containing electron-donating group, wherein a heterocyclic ring containing the sulfone group positioned in the middle of the three-dimensional structure is used as an electron acceptor (A), and a nitrogen-containing electron-donating group part is used as an electron donor (D) to form a D-A structure.
In one embodiment, the nitrogen-containing electron donating group has the structure
Figure BDA0002002302790000101
Wherein Ar is1And Ar2Independently selected from H or alkyl with 1-24 carbon atoms, and Ar1And Ar2At least one of which is an alkyl group; or, Ar1And Ar2Independently selected from substituted or unsubstituted phenyl; or, Ar1And Ar2Independently selected from substituted or unsubstituted phenyl, wherein Ar1、Ar2To the N atom to form a five-membered ring, or Ar1、Ar2N atom and independently of said Ar1And Ar2The other atom of the group is connected to a six-membered ring, the other atom being C, N, S, O or Si; and when the other atom is C, N or Si, the six membered ring is substituted or unsubstituted.
It is noted that when the other atom is C, N or Si, the six membered ring can be substituted or unsubstituted; when the six-membered ring is substituted, the substituent group thereon is attached to the other atom (C, N or Si atom) on the six-membered ring.
In one embodiment, Ar1And Ar2Independently selected from substituted or unsubstituted phenyl; or, Ar1And Ar2Independently selected from substituted or unsubstituted phenyl, wherein Ar1、Ar2To the N atom to form a five-membered ring, or Ar1、Ar2N atom and independently of said Ar1And Ar2The other atom of the group is connected to a six-membered ring, the other atom being C, N, S, O or Si.
In one embodiment, the nitrogen-containing electron donating group is selected from one of the following groups:
Figure BDA0002002302790000102
Figure BDA0002002302790000111
wherein, R 'and R' are respectively and independently selected from one of hydrogen atom, methyl, tertiary butyl and aromatic amine group.
In one embodiment, R1、R2、R3And R4Two of them are nitrogen-containing electron donating groups, and the other two are hydrogen atoms.
Therefore, the thermal activation delayed fluorescence material containing the sulfone group has a D-A-D structure, and can further improve the external quantum efficiency.
In one embodiment, R1And R2Is a nitrogen-containing electron donating group, R3And R4Is a hydrogen atom, or, R1And R2Is a hydrogen atom, R3And R4Is a nitrogen-containing electron donating group.
Further, R1And R2Same as R3And R4Same as R5And R6Are all methyl.
In one embodiment, the thermally activated delayed fluorescence material (TADF) is selected from one of compounds having the following structures M1 to M30:
Figure BDA0002002302790000112
Figure BDA0002002302790000121
Figure BDA0002002302790000131
Figure BDA0002002302790000141
preferably, the thermally activated delayed fluorescence material is one selected from compounds having the structures of the above formula M11, formula M12, formula M13, formula M14 and formula M15.
Another embodiment of the present invention provides a method for preparing a thermally activated delayed fluorescent material having the formula (I-1), which includes the following steps S11 to S13.
S11, carrying out a light-shielding reaction on 9, 9-dimethyl-9 h-thioxanthene and N-bromosuccinimide (NBS) to generate a compound shown in a formula (a), wherein the reaction formula is as follows:
Figure BDA0002002302790000142
in one embodiment, 9-dimethyl-9 h-thioxanthene and N-bromosuccinimide (NBS) are fed according to the molar ratio of 1 (2-2.5) and react in a dark place to generate the compound shown in the formula (a).
Specifically, according to the molar ratio of 9, 9-dimethyl-9 h-thioxanthe to N-bromosuccinimide (NBS) being 1 (2-2.5), 9-dimethyl-9 h-thioxanthe dissolved in an organic solvent is mixed with NBS, and the mixture is reacted for 10-14 hours at room temperature in a dark place.
S12, oxidizing the compound of formula (a) to produce a compound of formula (b-1), the reaction formula being:
Figure BDA0002002302790000151
in one embodiment, the oxidizing agent used to oxidize the compound of formula (a) to produce the compound of formula (b-1) is selected from sodium metaperiodate and potassium metaperiodate, and the catalyst used is Ru-Al2O3。
Specifically, the compound of the formula (a), an oxidant, a catalyst and an organic solvent are mixed and reacted at room temperature, after the reaction is finished, the reaction product is filtered, and water and the organic solvent are removed from the obtained filtrate, and the obtained filtrate is separated and purified to obtain the compound of the formula (b-1).
Further, the oxidant is sodium metaperiodate, preferably, the oxidant is supported on gamma-alumina; the catalyst is Ru-Al2O3(ii) a The organic solvent is dipotassium carbonate.
S13, reacting the compound of the formula (b-1) with the compound of the formula (c) to obtain the thermal activation delayed fluorescence material of the following formula (I-1); the structural formulas of the compound of formula (c) and the thermally activated delayed fluorescence material of formula (I-1) are respectively as follows:
Figure BDA0002002302790000152
wherein, in formula (c), Ar1And Ar2Independently selected from H or alkyl with 1-24 carbon atoms, and Ar1And Ar2At least one of which is an alkyl group; or, Ar1And Ar2Independently selected from substituted or unsubstituted phenyl; or, Ar1And Ar2Independently selected from substituted or unsubstituted phenyl, wherein Ar1、Ar2To the N atom to form a five-membered ring, or Ar1、Ar2N atom and independently of said Ar1And Ar2Radical of another atomAnd the other atom is C, N, S, O or Si; and when the other atom is C, N or Si, the six membered ring is substituted or unsubstituted.
In the formula (I-1), R1And R2Is structured as
Figure BDA0002002302790000161
And R is1And R2The same is true.
Specifically, the compound of the formula (b-1) and the compound of the formula (c) are mixed and react under the action of strong alkali at the temperature of 98-102 ℃ to generate the heat-activated delayed fluorescent material of the formula (I-1).
In one embodiment, Ar1And Ar2Independently selected from substituted or unsubstituted phenyl; or, Ar1And Ar2Independently selected from substituted or unsubstituted phenyl, wherein Ar1、Ar2To the N atom to form a five-membered ring, or Ar1、Ar2N atom and independently of said Ar1And Ar2The other atom of the group is connected to a six-membered ring, the other atom being C, N, S, O or Si.
Further, the compound of formula (c) may be selected from one of the compounds having the following structural formula:
Figure BDA0002002302790000162
another embodiment of the present invention also provides a method for preparing a thermally activated delayed fluorescence material having the formula (I-2), which includes the following steps S21 to S24.
S21, carrying out a light-shielding reaction on 9, 9-dimethyl-9 h-thioxanthene and N-bromosuccinimide (NBS) to generate a compound shown in a formula (d), wherein the reaction formula is as follows:
Figure BDA0002002302790000163
in one embodiment, 9-dimethyl-9 h-thioxanthene and N-bromosuccinimide (NBS) are fed according to the molar ratio of 1 (4-4.5) and react in a dark place to generate the compound shown in the formula (d).
Specifically, according to the molar ratio of 9, 9-dimethyl-9 h-thioxanthe to N-bromosuccinimide (NBS) being 1 (4-4.5), 9-dimethyl-9 h-thioxanthe dissolved in an organic solvent is mixed with NBS, and the mixture is reacted for 10-14 hours at room temperature in a dark place.
S22, reacting the compound of the formula (d) with n-butyl lithium and acetic acid to generate the compound of the formula (e).
Specifically, in an inert protective gas atmosphere, dissolving the compound of the formula (d) in an organic solvent such as Tetrahydrofuran (THF) and the like, adding n-butyllithium (n-BuLi) at the temperature of-80 to-75 ℃, reacting for 1.5 to 2.5 hours at the temperature, and then adding a silicon-containing catalyst of trimethylchlorosilane ((CH)3)3SiCl) is uniformly stirred, and after the reaction is carried out for 22-26 hours at room temperature, water is used for quenching, then acetic acid is added, and the reaction is carried out for 22-26 hours, so as to generate the compound shown in the formula (e). The reaction formula is as follows:
Figure BDA0002002302790000171
s23, oxidizing the compound of formula (e) to generate a compound of formula (b-2), wherein the reaction formula is as follows:
Figure BDA0002002302790000172
in one embodiment, the oxidizing agent used to oxidize the compound of formula (e) to produce the compound of formula (b-2) is sodium metaperiodate or potassium metaperiodate, and the catalyst used is Ru-Al2O3。
Specifically, the compound of formula (e), an oxidant, a catalyst and an organic solvent are mixed and reacted at room temperature, after the reaction is completed, the reaction product is filtered, and the obtained filtrate is subjected to water and organic solvent removal, separation and purification to obtain the compound of formula (b-2).
Further, the oxidant is sodium metaperiodate, preferably, the oxidant is supported on gamma-alumina; the catalyst is Ru-Al2O3(ii) a The organic solvent is dipotassium carbonate.
Specifically, gamma-alumina and metaperiodic acid as oxidantSodium, catalyst Ru-Al2O3And water, adding an organic solvent dimethyl carbonate and the compound of the formula (e), and reacting at room temperature for 2-3 hours to generate the compound of the formula (b-2).
Wherein the feeding molar ratio of the oxidant to the compound of the formula (e) is 1 (2.5-3.5).
S24, reacting the compound of the formula (b-2) with the compound of the formula (c) to obtain the heat-activated delayed fluorescence material of the formula (I-2); the structural formulas of the thermal activation delayed fluorescence material with the formula (I-2) are respectively as follows:
Figure BDA0002002302790000181
wherein R is3And R4Is structured as
Figure BDA0002002302790000182
And R is3And R4The same is true.
Specifically, the compound of the formula (b-2) and the compound of the formula (c) are mixed and react under the action of strong alkali at the temperature of 98-102 ℃ to generate the heat-activated delayed fluorescent material of the formula (I-2).
In one embodiment, the method further comprises the step of synthesizing 9, 9-dimethyl-9 h-thioxanthene by using dibenzothiapyran as a starting material, wherein the reaction formula is as follows:
Figure BDA0002002302790000183
specifically, dibenzothiapiprazole is dissolved in an organic solvent in a nitrogen atmosphere, then the temperature is reduced to minus 80 ℃ to minus 78 ℃, n-butyllithium (n-BuLi) is added, the reaction is carried out at a constant temperature of minus 80 ℃ to minus 78 ℃, methyl bromide is added after the reaction is finished, and the reaction is carried out at room temperature to generate 9, 9-dimethyl-9 h-thioxanthene.
Furthermore, the molar ratio of dibenzothiapiprazole, n-butyl lithium and methyl bromide is 1 (2-2.2) to (2-2.2).
Another embodiment of the present invention also provides an organic electroluminescent device. The organic electroluminescent device comprises a cathode, an anode and a luminescent layer arranged between the cathode and the anode, wherein the luminescent layer material comprises a host material and a guest material, and the host material is one of the thermal activation delayed fluorescence materials.
It is understood that the organic electroluminescent device may have one of the hole transport layer, the light emitting layer and the electron transport layer, and two or three of the hole transport layer, the light emitting layer and the electron transport layer; when the organic electroluminescent element has only one layer, the above thermally activated delayed fluorescence material is one of the materials forming the layer; when the organic electroluminescent device has two or three layers, any one of the layers may contain the above thermally activated delayed fluorescent material, or both of the two or three layers may contain the above thermally activated delayed fluorescent material.
In one embodiment, the guest material is present in the light-emitting layer in a mass ratio of 1 wt% to 40 wt%.
Preferably, the guest material accounts for 5 wt% to 20 wt% of the light-emitting layer.
As shown in fig. 1, an organic light emitting diode device according to an embodiment of the present invention includes an Anode (Anode), a Hole Injection Layer (HIL), a Hole Transport Layer (HTL), an emission layer (EML), a Hole Blocking Layer (HBL), an Electron Transport Layer (ETL), an Electron Injection Layer (EIL), a Cathode (Cathode), and a light extraction layer (CPL) sequentially formed on a substrate (substrate), and at least one of the hole transport layer, the emission layer, and the electron transport layer includes at least one TADF material.
The anode may be made of ITO, IGZO, or the like.
the material of the hole injection layer may be α -NPD, TCNQ, HAT-CN, or the like.
The material of the hole transport layer may be TCTA, NPB, TPD, TAPC, or the like.
The material of the light-emitting layer takes the thermally activated delayed fluorescence material as a guest material, takes DPEPO, CBP, mCP and the like as host materials, and the mass ratio of the guest material is 1-40%.
The hole blocking layer may be BCP, TPBi, BPhen, or the like.
The material of the electron transport layer may be TPBi, Alq, Znq, Gaq, Bebq, Balq, PBD, or the like.
The material of the electron injection layer may be NaF, LiF, CsF, or the like.
The cathode material can be Ag, Al, Ag, Mg and other metals, or the low work function composite metal such as Mg-Ag and the like.
Specifically, the preparation method of the organic electroluminescent device comprises the following steps:
firstly, the ITO substrate is cleaned according to the following sequence: 5% KOH solution is subjected to ultrasonic treatment for 15min, pure water is subjected to ultrasonic treatment for 15min, isopropanol is subjected to ultrasonic treatment for 15min, and the mixture is dried in an oven for 1 h; the substrate was then transferred to a UV-ozon apparatus for surface treatment for 15min and immediately transferred to a glove box after treatment. Then, evaporation film forming is carried out: adding the required organic, inorganic and metal materials, and vacuumizing to 10 DEG- 7Torr, then slowly increase the current value, slowly increase the rate to
Figure BDA0002002302790000201
And opening the baffle after the speed is stable to perform evaporation coating of each layer in sequence. And finally, carrying out UV curing packaging, and baking at 70 ℃ for 20 min.
The 9, 9-dimethyl-9 h-thioxanthene used in the examples of the present invention can be obtained by commercially available or synthetic reactions.
The following are specific examples
EXAMPLE 1 Synthesis of Compound of formula (M11)
1) Synthesis of 9, 9-dimethyl-9 h-thioxanthene
Adding 15mmol of sulfur-containing heterocyclic compound dibenzothiapipran into a 50mL two-neck bottle, adding a stirring magneton, vacuumizing and changing nitrogen for three times, putting the reaction bottle in a nitrogen atmosphere, adding 30mL of Tetrahydrofuran (THF), stirring at room temperature to dissolve dibenzothiapipran solid, then reducing the temperature to-78 ℃, adding 32mmol of n-butyl lithium (n-BuLi), carrying out constant-temperature reaction at-78 ℃ in a low-temperature reaction kettle for 2 hours, then dropwise adding 32mmol of methyl bromide, continuing stirring for 1 hour, and then returning to room temperature to react for 24 hours. After the reaction is finished, separating and purifying by using a silica gel chromatographic column, using normal hexane/dichloromethane as an eluent, and performing rotary evaporation and removalThe product 9, 9-dimethyl-9 h-thioxanthene was collected as solvent and finally dried in vacuo at room temperature for 12h and weighed. The calculated yield was 75%. The nmr results of the product were:1H NMR(500MHz,CDCl3),δ(TMS,ppm):7.69(m,2H),7.34(m,2H),7.11(m,4H),1.72(s,6H)。
2) preparation of the Compound of formula (a)
Adding 10mmol of 9, 9-dimethyl-9 h-thioxanthene synthesized in the step 1) into a 50mL two-neck flask, adding stirring magnetons, adding 30mL of Tetrahydrofuran (THF) serving as a solvent, stirring and dissolving at room temperature, adding 12.5mmol of N-bromosuccinimide (NBS) twice every 15min, adding 25mmol of NBS in total, and taking care of the reaction and keeping out of the light. The reaction was carried out at room temperature for 12 hours. After the reaction is finished, separating and purifying by using a silica gel chromatographic column, removing the solvent by rotary evaporation by using normal hexane/dichloromethane as an eluent, collecting the product, and finally drying in vacuum at room temperature for 12 hours to obtain the compound of the formula (a), weighing, and calculating the yield to be 70%. The nmr results of the product were:1H NMR(500MHz,CDCl3),δ(TMS,ppm):7.53(m,2H),7.25(m,2H),7.22(m,2H),1.72(s,6H)。
3) preparation of the compound of formula (b-1)
Adding 2g of gamma-alumina and 3mmol of sodium metaperiodate into a 50ml round-neck flask, adding a stirring magneton, and then adding Ru-Al2O320mg of catalyst and 1ml of water were added. Stirring for 2-3 min, adding 8ml of dimethyl carbonate (DMC) solvent, and adding 1mmol of the compound of the formula (a) prepared in the step 2). Stirring for 2.5h at room temperature, after confirming that the reaction is finished, filtering, rinsing filter residues by using ethyl acetate to obtain a filtrate containing a product, drying by using anhydrous sodium sulfate to remove water, spin-drying a solvent, separating and purifying by using a silica gel chromatographic column, using normal hexane/ethyl acetate as an eluent, spin-evaporating to remove the solvent, collecting the product, finally drying in vacuum for 12h at room temperature, and weighing. The calculated yield was 84%. The nmr results of the product were:1H NMR(500MHz,CDCl3),δ(TMS,ppm):7.64(d,2H),7.62(s,2H),7.59(d,2H),1.72(s,6H)。
4) synthesis of Compound of formula (M11)
The reaction formula is as follows:
Figure BDA0002002302790000221
adding 30mmol of sodium hydride (NaH) into a 50mL two-neck flask, adding 30mL of anhydrous N, N-Dimethylformamide (DMF), adding stirring magnetons, stirring for dissolving, adding 15mmol of amine electron donor of the formula (c-1), and stirring for reacting for 30 min; then, 7.5mmol of the compound of the formula (b-1) obtained in step 3) was dissolved in anhydrous DMF, and then added dropwise to the reaction solution, and reacted at 100 ℃ for 2 hours. And after the reaction is finished, adding water into the solution to finish the reaction, and then filtering and drying to obtain a crude product. Further purifying the crude product with silica gel chromatography column, removing the solvent by rotary evaporation using n-hexane/ethyl acetate as eluent, collecting the product, vacuum drying at room temperature for 12h to obtain (M11) compound, weighing, calculating the yield to be 65%, and the result of nuclear magnetic resonance of the product is:1H NMR(500MHz,CDCl3),δ(TMS,ppm):8.43(s,3H),7.58(d,6H),7.01(d,12H),6.80(d,6H),6.55(d,12H),1.35(s,54H)。
EXAMPLE 2 Synthesis of Compound of formula (M12)
The embodiment 2 is basically the same as the embodiment 1, except that the step 4) specifically comprises the following steps:
the reaction scheme for the synthesis of compound of formula (M12) is:
Figure BDA0002002302790000222
adding 30mmol of sodium hydride (NaH) into a 50mL two-neck flask, adding 30mL of anhydrous N, N-Dimethylformamide (DMF), adding stirring magnetons, stirring for dissolving, adding 15mmol of amine electron donor of the formula (c-2), and stirring for reacting for 30 min; then, 7.5mmol of the compound of formula (b) obtained in step 3) was dissolved in anhydrous DMF, and then added dropwise to the reaction solution, and reacted at 100 ℃ for 2 hours. And after the reaction is finished, adding water into the solution to finish the reaction, and then filtering and drying to obtain a crude product. Further purifying the crude product with silica gel chromatography column, removing solvent with n-hexane/ethyl acetate as eluent by rotary evaporation, collecting the product, vacuum drying at room temperature for 12h to obtain (M12) compound, weighing, calculating yield to 70%, and performing nuclear magnetic resonance on the product：1H NMR(500MHz,CDCl3),δ(TMS,ppm):7.5(m,4H),7.01(m,8H),6.79(m,2H),6.55(m,8H),1.72(s,6H),1.35(s,36H)。
EXAMPLE 3 Synthesis of Compound of formula (M13)
Example 3 is substantially the same as example 1, except for step 4), specifically:
the reaction scheme for the synthesis of compound of formula (M13) is:
Figure BDA0002002302790000231
adding 30mmol of sodium hydride (NaH) into a 50mL two-neck flask, adding 30mL of anhydrous N, N-Dimethylformamide (DMF), adding stirring magnetons, stirring for dissolving, adding 15mmol of amine electron donor of the formula (c-3), and stirring for reacting for 30 min; then, 7.5mmol of the compound of formula (b) obtained in step 3) was dissolved in anhydrous DMF, and then added dropwise to the reaction solution, and reacted at 100 ℃ for 2 hours. And after the reaction is finished, adding water into the solution to finish the reaction, and then filtering and drying to obtain a crude product. Further purifying the crude product with silica gel chromatography column, removing solvent by rotary evaporation using n-hexane/ethyl acetate as eluent, collecting the product, vacuum drying at room temperature for 12h to obtain (M13) compound, weighing, calculating the yield to be 75%, and the result of nuclear magnetic resonance of the product is:1H NMR(500MHz,CDCl3),δ(TMS,ppm):7.50(d,2H),7.12(d,4H),7.02(d,4H),6.94(s,4H),6.62(d,2H),1.72(s,6H),1.35(s,36H)。
EXAMPLE 4 Synthesis of Compound of formula (M14)
Example 4 is substantially the same as example 1, except for step 4), specifically:
the reaction scheme for the synthesis of compound of formula (M14) is:
Figure BDA0002002302790000241
adding 30mmol sodium hydride (NaH) into a 50mL two-neck flask, adding 30mL anhydrous N, N-Dimethylformamide (DMF), adding stirring magneton, stirring to dissolve, adding 15mmol amine electron donor of formula (c-4), and stirring to reactThe time is 30 min; then, 7.5mmol of the compound of formula (b) obtained in step 3) was dissolved in anhydrous DMF, and then added dropwise to the reaction solution, and reacted at 100 ℃ for 2 hours. And after the reaction is finished, adding water into the solution to finish the reaction, and then filtering and drying to obtain a crude product. Further purifying the crude product with silica gel chromatography column, removing solvent by rotary evaporation using n-hexane/ethyl acetate as eluent, collecting the product, vacuum drying at room temperature for 12h to obtain (M14) compound, weighing, calculating the yield to be 75%, and the result of nuclear magnetic resonance of the product is:1H NMR(500MHz,CDCl3),δ(TMS,ppm):7.50(d,2H),7.14(s,4H),6.79(d,4H),6.73(d,4H),6.62(d,2H),6.51(d,4H),1.72(s,6H),1.35(s,36H)。
EXAMPLE 5 Synthesis of Compound of formula (M15)
Example 5 is substantially the same as example 1, except for step 4), specifically:
the reaction scheme for the synthesis of compound of formula (M15) is:
Figure BDA0002002302790000242
adding 30mmol of sodium hydride (NaH) into a 50mL two-neck flask, adding 30mL of anhydrous N, N-Dimethylformamide (DMF), adding stirring magnetons, stirring for dissolving, adding 15mmol of amine electron donor of the formula (c-5), and stirring for reacting for 30 min; then, 7.5mmol of the compound of formula (b) obtained in step 3) was dissolved in anhydrous DMF, and then added dropwise to the reaction solution, and reacted at 100 ℃ for 2 hours. And after the reaction is finished, adding water into the solution to finish the reaction, and then filtering and drying to obtain a crude product. Further purifying the crude product with silica gel chromatography column, removing solvent by rotary evaporation using n-hexane/ethyl acetate as eluent, collecting the product, vacuum drying at room temperature for 12h to obtain (M15) compound, weighing, calculating the yield to be 75%, and the result of nuclear magnetic resonance of the product is:1H NMR(500MHz,CDCl3),δ(TMS,ppm):7.50(d,2H),7.15(s,4H),6.83(d,4H),6.79(s,2H),6.62(d,2H),6.47(d,4H),1.72(s,18H),1.35(s,36H)。
embodiment 6 an organic light emitting diode device
The device structure of the embodiment is as follows:
ITO/α-NPD(30nm)/TCTA(20nm)/mCP:M13，7wt％(20nm)/DPEPO(10nm)/TPBi(20nm)/NaF(3nm)/Al。
the anode is ITO, the hole injection layer is α -NPD, the hole transport layer is made of TCTA, the light emitting layer is made of mCP (metal doped polysilicon) M13, the mCP serves as a host material and a barrier layer material, the M2 serves as a guest material, the M13 material accounts for 7 wt% of the layer, the hole barrier layer is made of DPEPO, the electron transport layer is made of TPBi, the electron injection layer is made of NaF, and the cathode is made of Al.
M13 has the structural formula:
Figure BDA0002002302790000251
example 7
The device structure of the embodiment is as follows:
ITO/α-NPD(30nm)/TCTA(20nm)/mCP:M11，7wt％(20nm)/DPEPO(10nm)/TPBi(20nm)/NaF(3nm)/Al。
m11 has the structural formula:
Figure BDA0002002302790000261
example 8
The device structure of the embodiment is as follows:
ITO/α-NPD(30nm)/TCTA(20nm)/mCP:M12，7wt％(20nm)/DPEPO(10nm)/TPBi(20nm)/NaF(3nm)/Al。
m12 has the structural formula:
Figure BDA0002002302790000262
example 9
The device structure of the embodiment is as follows:
ITO/α-NPD(30nm)/TCTA(20nm)/mCP:M14，7wt％(20nm)/DPEPO(10nm)/TPBi(20nm)/NaF(3nm)/Al。
m14 has the structural formula:
Figure BDA0002002302790000271
example 10
The device structure of the embodiment is as follows:
ITO/α-NPD(30nm)/TCTA(20nm)/mCP:M15，7wt％(20nm)/DPEPO(10nm)/TPBi(20nm)/NaF(3nm)/Al。
m15 has the structural formula:
Figure BDA0002002302790000272
example 11
The device structure of the embodiment is as follows:
ITO/α-NPD(30nm)/TCTA(20nm)/mCP:M16，7wt％(20nm)/DPEPO(10nm)/TPBi(20nm)/NaF(3nm)/Al。
m16 has the structural formula:
Figure BDA0002002302790000273
comparative example 1
Comparative example 1 is substantially the same as example 1 except that a blue phosphorescent material Ir (fppz)2(dfbdp) as guest material, the device structure of this comparative example was:
ITO/α-NPD(30nm)/TCTA(20nm)/mCP:Ir(fppz)2(dfbdp)，7wt％(30nm)/DPEPO(10nm)/TPBi(20nm)/NaF(3nm)/Al。
the devices of examples 6 to 11 of the present invention and comparative example 1 were subjected to performance tests, and the results are shown in the following table.
Figure BDA0002002302790000281
As can be seen from the above table, the external quantum efficiencies of the devices of examples 7, 8, 10, and 11 according to the present invention are significantly improved, the light emitting efficiencies (external quantum efficiencies) thereof are all 8% or more, and the color coordinate y value (CIE) of the light emission of the devices is significantly increased as compared with the device of comparative example 1y) Are all less than 0.10, indicating that the embodiments of the present invention provide a delay in thermal activationThe fluorescent material can realize high external quantum efficiency in the deep blue region.
The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.
The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.

Claims (12)

1. A thermally activated delayed fluorescence material, wherein the thermally activated delayed fluorescence material is a compound having a structure of formula (I):
Figure FDA0002002302780000011
in the formula (I), R1、R2、R3And R4Each independently a nitrogen-containing electron donating group or a hydrogen atom, and R1、R2、R3And R4At least one of the nitrogen-containing electron donating groups is a nitrogen-containing electron donating group, and the nitrogen-containing electron donating group is connected with a corresponding benzene ring through an N atom; r5And R6Each independently a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.
2. The thermally activated delayed fluorescence material of claim 1, wherein the nitrogen-containing electron donating group has a structure of
Figure FDA0002002302780000012
Wherein Ar is1And Ar2Independently selected from H or alkyl with 1-24 carbon atoms, and Ar1And Ar2At least one of which is an alkyl group;
or, Ar1And Ar2Independently selected from substituted or unsubstituted phenyl;
or, Ar1And Ar2Independently selected from substituted or unsubstituted phenyl, wherein Ar1、Ar2To the N atom to form a five-membered ring, or Ar1、Ar2N atom and independently of said Ar1And Ar2The other atom of the group is connected to a six-membered ring, said other atom being C, N, S, O or Si; and when the other atom is C, N or Si, the six membered ring is substituted or unsubstituted.
3. The thermally activated delayed fluorescence material of claim 2, wherein the Ar is1And Ar2Independently selected from substituted or unsubstituted phenyl;
or, Ar1And Ar2Independently selected from substituted or unsubstituted phenyl, wherein Ar1、Ar2To the N atom to form a five-membered ring, or Ar1、Ar2N atom and independently of said Ar1And Ar2The other atom of the group, which is C, N, S, O or Si, is connected to a six-membered ring.
4. The thermally activated delayed fluorescence material of claim 3, wherein the nitrogen-containing electron donating group is selected from one of the following groups:
Figure FDA0002002302780000021
wherein, R 'and R' are respectively and independently selected from one of hydrogen atom, methyl, tertiary butyl and aromatic amine group.
5. The thermally activated delayed fluorescence according to any of claims 1 to 4Characterized in that R is1、R2、R3And R4Two of them are nitrogen-containing electron donating groups, and the other two are hydrogen atoms.
6. The thermally activated delayed fluorescence material of claim 5, wherein the thermally activated delayed fluorescence material is selected from one of compounds having the following structures of formula M1-formula M30:
Figure FDA0002002302780000022
Figure FDA0002002302780000031
Figure FDA0002002302780000041
Figure FDA0002002302780000051
7. the method for preparing the thermally activated delayed fluorescence material according to any one of claims 1 to 6, comprising the steps of:
reacting a compound of formula (b) with a compound of formula (c) to produce the thermally activated delayed fluorescence material of formula (I);
the structural formulas of the compound of formula (b) and the compound of formula (c) are respectively as follows:
Figure FDA0002002302780000061
wherein, in the formula (b), R1’、R2’、R3' and R4' are each independently a bromine atom or a hydrogen atom, and R1’、R2’、R3' and R4At least one of them is a bromine atom; r5' and R6' are each independently a hydrogen atom or an alkyl group having 1 to 4 carbon atoms;
in the formula (c), Ar1And Ar2Independently selected from H or alkyl with 1-24 carbon atoms, and Ar1And Ar2At least one of which is an alkyl group; or, Ar1And Ar2Independently selected from substituted or unsubstituted phenyl; or, Ar1And Ar2Independently selected from substituted or unsubstituted phenyl, wherein Ar1、Ar2To the N atom to form a five-membered ring, or Ar1、Ar2N atom and independently of said Ar1And Ar2The other atom of the group is connected to a six-membered ring, said other atom being C, N, S, O or Si; and when the other atom is C, N or Si, the six membered ring is substituted or unsubstituted.
8. The method for preparing a thermally activated delayed fluorescence material according to claim 7, wherein R is1’、R2’、R3' and R4Two of which are bromine atoms and the other two are hydrogen atoms.
9. The method for preparing a thermally activated delayed fluorescent material according to claim 8, wherein R in the formula (b)1' and R2' are all bromine atoms, R3' and R4' are both hydrogen atoms; or, R1' and R2' are both hydrogen atoms, R3' and R4Both are bromine atoms.
10. An organic electroluminescent device comprising a cathode, an anode, and a light-emitting layer disposed between the cathode and the anode, wherein the light-emitting layer comprises a host material and a guest material, and the guest material is a compound having a structure of formula (I):
Figure FDA0002002302780000071
formula (I)) In, R1、R2、R3And R4Each independently a nitrogen-containing electron donating group or a hydrogen atom, and R1、R2、R3And R4At least one of the nitrogen-containing electron donating groups is a nitrogen-containing electron donating group, and the nitrogen-containing electron donating group is connected with a corresponding benzene ring through an N atom; r5And R6Each independently a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.
11. The organic electroluminescent device according to claim 10, wherein the guest material is selected from one of compounds having the following structures M1 to M30:
Figure FDA0002002302780000072
Figure FDA0002002302780000081
Figure FDA0002002302780000091
12. the organic electroluminescent device according to claim 10 or 11, wherein the mass ratio of the guest material in the light emitting layer is 1 wt% to 40 wt%, and more preferably, the mass ratio of the guest material in the light emitting layer is 5 wt% to 20 wt%.
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PALOMA L. DOS SANTOS ET AL.: "Optical and Polarity Control of Donor-Acceptor Conformation and Their Charge-Transfer States in Thermally Activated Delayed-Fluorescence Molecules", 《J. PHYS. CHEM. C》 *
PALOMA L. SANTOS ET AL.: "Engineering the singlet-triplet energy splitting in a TADF molecule", 《JOURNAL OF MATERIALS CHEMISTRY C》 *

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113620973A (en) * 2021-07-16 2021-11-09 西北工业大学 Thermal activation delayed fluorescent material and preparation method and application thereof
CN113620973B (en) * 2021-07-16 2024-05-07 西北工业大学 Thermal activation delay fluorescent material and preparation method and application thereof

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Application publication date: 20200519