KR20160064961A - Delayed Fluorescence compound, and Organic light emitting diode device and Display device using the same - Google Patents

Abstract

Provided is a delayed fluorescence compound having a molecular structure in which acridine as an electron doner moiety forms a bond with an electron acceptor moiety directly or through a substituted or unsubstituted benzene linker. The electron acceptor moiety is selected from substituted or unsubstituted triazine, substituted or unsubstituted dibenzothiophene, substituted or unsubstituted diphenylsulfone, substituted or unsubstituted 4-azabenzimidazole, and substituted or unsubstituted benzimidazole.

Description

TECHNICAL FIELD [0001] The present invention relates to an organic light emitting diode (OLED) device and a display device including the same,

The present invention relates to a luminescent material. More particularly, the present invention relates to a retardation fluorescent compound having improved luminous efficiency by intramolecular charge transfer, an organic light emitting diode device including the same, and a display device.

Recently, the demand for a flat display device having a small space occupancy has been increased due to the enlargement of a display device. The technology of an organic light emitting diode device, which is also called an organic light emitting diode (OLED) .

An organic light-emitting diode device is a device that emits light when electrons and holes are injected from a cathode and an anode into a light emitting material layer formed between an electron injection electrode (cathode) and a hole injection electrode (anode) . The device can be formed not only on a flexible transparent substrate such as a plastic but also can be driven at a low voltage (10 V or less), has relatively low power consumption, and is excellent in color.

The organic light emitting diode device includes a first electrode that is an anode, a second electrode that faces the first electrode, and an organic light emitting layer that is disposed between the first electrode and the second electrode.

In order to improve the luminous efficiency, the organic light emitting layer may include a hole injection layer (HIL), a hole transporting layer (HTL), an emitting material layer (EML) , An electron transporting layer (ETL), and an electron injection layer (EIL).

The holes are moved from the first electrode as the anode to the light emitting material layer through the hole injecting layer and the hole transporting layer and electrons are moved from the second electrode as the cathode to the light emitting material layer through the electron injecting layer and the electron transporting layer.

The holes and electrons transferred to the light emitting material layer combine with each other to form an exciton, which excites into an unstable energy state, and returns to a stable energy state to emit light.

The external quantum efficiency (eta _ext ) of the luminescent material used in the luminescent material layer can be obtained by the following equation.

η _ext = η _int × г × Φ × η _{out - coupling}

(Η _int : internal quantum efficiency, Φ: radiative quantum efficiency, η _{out - coupling} : out coupling efficiency)

The charge balance factor (г) is the balance between hole and electron forming the exciton, and generally has a value of 1 assuming 100% 1: 1 matching. Radiative quantum efficiency (Φ) is a value related to the luminescence efficiency of a practical luminescent material, and depends on the fluorescence quantum efficiency of the dopant in the host-dopant system.

The internal quantum efficiency (eta _int ) has a limiting value of 0.25 at maximum for the fluorescent material, at a rate at which the generated excitons are converted to the form of light. When excitons are formed by the combination of holes and electrons, a singlet exciton and a triplet exciton are generated at a ratio of 1: 3 according to the arrangement of the spin. However, in the fluorescent material, only the single-exciton participates in the luminescence and the remaining 75% of the triplet exciton does not participate in the luminescence.

Out coupling efficiency (η _{out - coupling} ) is the ratio of light extracted to the outside of the emitted light. In general, when an isotropic molecule is thermally deposited to form a thin film, the individual luminescent molecules do not have a certain directionality and exist in a disordered state. The out coupling efficiency in this random orientation state is generally assumed to be 0.2.

Therefore, the maximum luminous efficiency of the organic light emitting diode device using the fluorescent material is about 5% or less.

In order to overcome the low efficiency problem of the fluorescent material as described above, a phosphorescent material having a light emitting mechanism that converts both singlet excitons and triplet excitons to light has been developed.

In the case of red and green phosphors having high luminous efficiency have been developed, phosphors that satisfy the required luminous efficiency and reliability in the case of blue have not been developed.

Therefore, in a fluorescent material satisfying reliability, development of a material capable of increasing the luminous efficiency by increasing the quantum efficiency is required.

The present invention aims at solving the problem of low quantum efficiency of fluorescent materials.

In order to solve the above problems, the present invention provides a delayed fluorescent compound of molecular formula in which an electron acceptor moiety is bonded directly or via a linker to an acridine electron donating moiety.

The electron acceptor moiety may be substituted or unsubstituted triazine, substituted or unsubstituted dibenzothiophenesulfone, substituted or unsubstituted diphenylsulfone, substituted or unsubstituted 4-azabenzimidazole, substituted or unsubstituted Benzimidazole. ≪ / RTI >

That is, the retarding fluorescent compound of the present invention is represented by the following formula, n is 0 or 1, X is substituted or unsubstituted triazine, substituted or unsubstituted dibenzothiophenesulfone, substituted or unsubstituted di Phenylsulfone, substituted or unsubstituted 4-azabenzimidazole, substituted or unsubstituted benzimidazole, and Y is substituted or unsubstituted benzene.

In addition, the present invention provides an organic light emitting diode device and a display device, wherein the organic light emitting layer includes the above retarded fluorescent compound.

The retarded fluorescent compound of the present invention has a structure in which an electron donor moiety is bonded to an electron acceptor moiety by a linker, so that the charge can easily migrate in the molecule and the light emitting efficiency is improved. Particularly, in the retarded fluorescent compound of the present invention, since the triplet exciton is used for luminescence, the luminescent efficiency of the retarded fluorescent compound is improved.

Further, acridine having a hexagonal structure is used as an electron donor moiety, so that the steric hindrance with the electron acceptor moiety becomes large, and the angle between the acridine electron donor moiety and the electron acceptor moiety increases. Therefore, the conjugation formation between the electron donor moiety and the electron acceptor moiety is restricted, and the separation between the HOMO and the LUMO occurs smoothly, thereby further enhancing the luminous efficiency.

Further, a dipole is formed from the electron donor moiety to the electron acceptor moiety to increase the dipole moment inside the molecule, thereby further increasing the luminous efficiency.

The electron donor moiety and the electron acceptor moiety are bonded in the molecule and the superposition of the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) is reduced A field activated delayed fluorescence complex is formed to further improve the luminous efficiency of the retarded fluorescent compound.

By increasing the distance between the electron donor moiety and the electron donor moiety by the linker, the overlap between HOMO and LUMO is reduced, which can reduce the difference between triplet energy and singlet energy (ΔE _ST ).

In addition, the problem of red shift of light emitted from the light emitting layer including the retarded fluorescent compound can be minimized by steric hindrance of the linker.

Therefore, the organic light emitting diode device and the display device including the retarded fluorescent compound of the present invention can improve the luminous efficiency and realize a high quality image.

1 is a view for explaining an emission mechanism of a retardation fluorescent compound according to an embodiment of the present invention.
2A and 2B are diagrams for explaining the molecular structure of a compound containing a carbazole electron donating moiety.
FIGS. 3A and 3B are diagrams illustrating the molecular structure of a compound containing an acridine electron donating moiety. FIG.
4A to 4D are graphs showing delayed fluorescence characteristics of a retarded fluorescent compound according to an embodiment of the present invention.
5 is a schematic cross-sectional view of an organic light emitting diode device according to an embodiment of the present invention.

The present invention relates to a process for the preparation of substituted or unsubstituted dibenzothiophenesulfone or substituted or unsubstituted dibenzothiophenesulfone, which is substituted or unsubstituted through a benzene linker, an electron acceptor selected from dibenzothiophene, substituted or unsubstituted diphenylsulfone, substituted or unsubstituted 4-azabenzimidazole, substituted or unsubstituted benzimidazole, Lt; RTI ID = 0.0 > formula < / RTI >

In another aspect, the present invention provides a retarded fluorescent compound represented by the following formula (1), wherein X is selected from the following formula (2) and Y is selected from the following formula (3). (n is 0 or 1)

[Chemical Formula 1]

(2)

(3)

Wherein each of R 1 to R 4 is independently selected from substituted or unsubstituted aryl, and each of R 5 and R 6 is independently selected from hydrogen or C 1 to C 10 alkyl.

The delayed minerals of the present invention may be any of the following compounds.

In the delayed minerals of the present invention, the difference between the singlet energy and the triplet energy of the delayed fluorescent compound may be 0.3 eV or less.

In another aspect, the present invention provides an organic electroluminescent device comprising a first electrode, a second electrode facing the first electrode, and an organic light emitting layer positioned between the first and second electrodes, triazine, substituted or unsubstituted dibenzothiophene substituted or unsubstituted, substituted or unsubstituted benzene linker directly or through a substituted or unsubstituted benzene linker, acridine, A molecular formula of a structure to be bonded to an electron acceptor moiety selected from unsubstituted diphenylsulfone, substituted or unsubstituted 4-azabenzimidazole, substituted or unsubstituted benzimidazole, And a retardation fluorescent compound having a light-emitting property.

According to another aspect of the present invention, there is provided a light emitting device comprising a first electrode, a second electrode facing the first electrode, and an organic light emitting layer positioned between the first and second electrodes, , X is selected from the following formula (2), and Y is selected from the following formula (3). (n is 0 or 1)

[Chemical Formula 1]

(2)

(3)

Wherein each of R 1 to R 4 is independently selected from substituted or unsubstituted aryl, and each of R 5 and R 6 is independently selected from hydrogen or C 1 to C 10 alkyl.

In the organic light-emitting diode device of the present invention, the retarded fluorescent compound may be any one of the following compounds.

In the organic light emitting diode device of the present invention, the difference between the singlet energy and the triplet energy of the delayed fluorescent compound may be 0.3 eV or less.

In the organic light emitting diode device of the present invention, the delayed fluorescent compound may be used as a dopant, and the organic light emitting layer may further include a host.

In the organic light emitting diode device of the present invention, the difference between the highest level occupied molecular orbital level (HOMO _Host ) of the _host and the highest level occupied molecular orbital level (HOMO _Dopant ) of the _dopant (| HOMO _Host- HOMO _Dopant | the lowest level unoccupied molecular orbital level (LUMO _Host) and the lowest unoccupied molecular orbital level level (LUMO _dopant) of the dopant, the difference (| LUMO _{Host dopant} -LUMO |) may be equal to or less than 0.5eV.

In the organic light emitting diode device of the present invention, the delayed fluorescent compound may be used as a host, and the organic light emitting layer may further include a dopant.

In the organic light emitting diode device of the present invention, the delayed fluorescent compound is used as a first dopant, and the organic light emitting layer further comprises a host and a second dopant, wherein the first triplet energy of the first dopant is May be less than the second triplet energy and greater than the third triplet energy of the second dopant.

In the organic light emitting diode device of the present invention, the organic light emitting layer may include a hole injecting layer, a hole transporting layer, a light emitting material layer, an electron transporting layer, and an electron injecting layer, wherein the hole injecting layer, At least one of the electron transport layer and the electron injection layer may include the retarded fluorescent compound.

In another aspect, the present invention provides a light emitting device comprising a substrate, an organic light emitting diode device disposed on the substrate, an encapsulation film covering the organic light emitting diode device, and a cover window on the encapsulation film, A display device is provided.

Hereinafter, a structure of a retarded fluorescent compound according to an embodiment of the present invention, a synthesis example thereof, and an organic light emitting diode device using the same will be described.

The retarded fluorescent compound according to an embodiment of the present invention has a molecular formula of a structure in which an electron donor moiety, which is an acridine, is bonded to a electron acceptor moiety through a linker or directly to an electron acceptor moiety , Represented by the following formula (1).

[Chemical Formula 1]

Wherein n is 0 or 1. That is, as shown in the following formula (2-1), the electron donating moiety, which is an acridine, may be bonded to the electron acceptor moiety X via the linker Y, or may have a structure in which acridine And the electron donor moiety may be directly coupled to the electron acceptor moiety X. [

[Formula 2-1]

[Formula 2-2]

In the above Chemical Formulas 1, 2-1 and 2-2, the electron acceptor moiety X is a substituted or unsubstituted triazine, a substituted or unsubstituted dibenzothiophene, a substituted or unsubstituted Is selected from diphenylsulfone, substituted or unsubstituted 4-azabenzimidazole, and substituted or unsubstituted benzimidazole. For example, the electron acceptor moiety X may be selected from the materials represented by the following formula (3).

(3)

In Formula 3, each of R 1 to R 4 may be independently substituted or unsubstituted aryl. For example, each of R < 1 > to R < 4 > may be unsubstituted phenyl.

In the above general formulas (1), (2-1) and (2-2), Y as the linker is substituted or unsubstituted benzene. For example, the linker Y may be selected from the materials represented by the following formula (4).

[Chemical Formula 4]

In Formula 4, R5 and R6 each independently may be hydrogen or C1-C10 alkyl. For example, each of R5 and R6 can be independently hydrogen or methyl.

Such a retarded fluorescent compound includes both an electron donor moiety and an electron acceptor moiety so that the charge can easily move in the molecule and the light emission efficiency is improved. Further, a dipole is formed from the electron donor moiety to the electron acceptor moiety to increase the dipole moment inside the molecule, thereby further increasing the luminous efficiency.

Particularly, in the retarded fluorescent compound of the present invention, since the triplet exciton is used for luminescence, the luminescent efficiency of the retarded fluorescent compound is improved.

Further, acridine having a hexagonal structure is used as an electron donor moiety, so that the steric hindrance with the electron acceptor moiety becomes large, and the angle between the acridine electron donor moiety and the electron acceptor moiety increases. Therefore, the conjugation formation between the electron donor moiety and the electron acceptor moiety is restricted, and the separation between the HOMO and the LUMO occurs smoothly, thereby further enhancing the luminous efficiency.

The electron donor moiety and the electron acceptor moiety are bonded in the molecule and the superposition of the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) is reduced An electric field activating complex is formed and the luminous efficiency of the retarded fluorescent compound is further improved.

By increasing the distance between the electron donor moiety and the electron donor moiety by the linker, the overlap between HOMO and LUMO is reduced, which can reduce the difference between triplet energy and singlet energy (ΔE _ST ).

In addition, the problem of red shift of light emitted from the light emitting layer including the retarded fluorescent compound can be minimized by steric hindrance of the linker.

1, which is a drawing for explaining the luminescent mechanism of a retarding fluorescent compound according to an embodiment of the present invention, in the retarding fluorescent compound of the present invention, both singlet excitons and triplet excitons participate in luminescence, thereby improving quantum efficiency do.

That is, the delayed fluorescent compound of the present invention activates the triplet exciton by the electric field so that the triplet exciton and the singlet exciton move to the intermediate state (I ₁ ) and the ground state (S ₀ ) And emits light. In other words, the transition from singlet state (S ₁ ) and triplet state (T ₁ ) to intermediate state (I ₁ ) occurs (S ₁ -> I ₁ <-T ₁ ), and both singlet excitons and triplet excitons The light emitting efficiency is improved. This is referred to as FADF (filed activated delayed fluorescence) compound.

Conventional fluorescent materials are unable to switch between single-state and triplet states because HOMO and LUMO are distributed throughout the molecule. (selection rule)

However, in the FADF compound as in the present invention, the interactions between HOMO and LUMO are small because the overlapping of HOMO and LUMO in the molecule is small. Therefore, the change in the spin state of the electrons does not affect other electrons, and a new charge transfer band that does not follow the selection rule is formed.

In addition, since the electron acceptor moiety and the electron donor moiety are spaced apart in the molecule, the dipole moment in the molecule is present in a polarized form. In the state where the dipole moment is polarized, the interaction between HOMO and LUMO becomes small and the selection rule may not be followed. Therefore, in the FADF compound, a transition to the triplet state (T ₁₎ and the intermediate states (I ₁₎ in a singlet state (S ₁₎ becomes possible, triplet exciton is involved in light emission.

When the organic light emitting diode device is driven, 25% of singlet state excitons (S ₁ ) excitons and 75% of triplet excitons (T ₁ ) excitons cause an interstage transition to an intermediate state (I ₁ ) ₀ ), the internal quantum efficiency is theoretically 100%.

For example, the retarded fluorescent compound of formula (1) may be any of the compounds of formula (5).

[Chemical Formula 5]

The delayed fluorescent compound of the present invention includes acridine as an electron donating moiety, whereby the steric hindrance between the electron donating moiety and the electron accepting moiety becomes large, and the back angle between the electron donating moiety and the electron accepting moiety becomes .

FIGS. 2A and 2B are diagrams for explaining the molecular structure of a compound containing a carbazole electron donating moiety, and FIGS. 3A and 3B are diagrams for explaining the molecular structure of a compound containing an acridine electron donating moiety FIG.

Referring to Figs. 2A and 2B, when a carbazole is used as an electron donor moiety, the dihedral angle between the pole donut moiety and the electron acceptor moiety is about 44 degrees.

3A and 3B, when acridine is used as an electron donor moiety, the dihedral angle between the pole donut moiety and the electron acceptor moiety is about 89 degrees. That is, when acridine is included as the electron donor moiety, the back angle between the electron donor moiety and the electron acceptor moiety increases, and the conjugation formation between the electron donor moiety and the electron acceptor moiety is restricted. Therefore, in the compound containing an acridine electron donor moiety, the separation between HOMO and LUMO occurs smoothly and the luminous efficiency is further enhanced as compared with the compound containing carbazole.

Hereinafter, examples of synthesis of a retarded fluorescent compound according to an embodiment of the present invention will be described.

- Synthesis Example -

1. Synthesis of Compound 1

(1) Synthesis of compound a

[Reaction Scheme 1-1]

2,8-Dibromodibenzothiophene (14.6 mmol) and acetic acid solvent were stirred in a nitrogen atmosphere. Hydrogen peroxide (64.8 mmol) was further added thereto. The mixture was stirred at room temperature for about 30 minutes, and then refluxed for 12 hours or more. After completion of the reaction, 50 ml of distilled water was added thereto, followed by stirring and washing. After filtration, the solid was washed with an excess of hydrogen peroxide for a second time (holding for 30 minutes and 1 hour) and washed with distilled water. Filtered and dried to obtain Compound (a) in the form of a white solid (yield: 90%).

(2) Synthesis of compound b

[Reaction Scheme 1-2]

N-phenylanthranilic acid (46.9 mmol) was mixed in a methanol solvent and stirred in a nitrogen atmosphere. After further stirring at 0 ° C for 10 minutes, thionyl chloride (21.2 mmol) was slowly added dropwise. The mixed solution was stirred at 90 ° C for 12 hours or more. After completion of the reaction, the solvent was removed, and distilled water and ethyl acetate were added to extract. Water was removed from the extracted organic layer using magnesium sulfate and the solvent was removed. The residue was subjected to wet-refinement by column chromatography using hexane and ethyl acetate to obtain a dark yellow liquid-state compound b. (Yield: 81%).

(3) Synthesis of Compound c

[Reaction 1 - 3]

Compound b (38.1 mmol) was stirred in a tetrahydrofuran solvent in a nitrogen atmosphere. Methyl magnesium bromide (4.6 equivalents) was slowly dropped and reacted by stirring at room temperature for 12 hours or longer. After completion of the reaction, distilled water was slowly added thereto and extracted with ethyl acetate. Water was removed from the organic layer extracted with magnesium sulfate and the solvent was removed. The product was subjected to wet purification through column chromatography using hexane and ethyl acetate to obtain a yellow liquid compound c. (Yield: 87%).

(4) Synthesis of compound d

[Reaction Scheme 1-4]

Compound c (33.1 mmol) was added to an excess of phosphoric acid (160 ml) and stirred at room temperature. After stirring for more than 16 hours, 200 ~ 250 ml of distilled water was slowly added. After stirring for 0.5 to 1 hour, the precipitated solid was filtered. The filtered solid was extracted with an aqueous solution of sodium hydroxide and dichloromethane. Water was removed from the organic layer extracted with magnesium sulfate and the organic solvent was removed to obtain a white solid compound d. (Yield: 69%).

(5) Synthesis of Compound e

[Reaction Scheme 1-5]

Compound a was dissolved in a toluene solvent under a nitrogen atmosphere, and then phenylboronic acid (0.9 equivalent) was added. K ₂ CO ₃ (4 eq) was dissolved in distilled water and then added to the reaction mixture. A tetrahydrofuran solvent was added and palladium (Pd, 0.05 eq.) Was added. The reaction mixture was then stirred at reflux at 80 &lt; 0 &gt; C. After completion of the reaction, extraction was performed using an ethyl acetate solvent and distilled water, and water was removed from the extracted organic layer using magnesium sulfate. The remaining organic solvent was removed and purified by column chromatography using ethyl acetate and hexane to obtain Compound e in a solid state. (Yield: 68%).

(6) Synthesis of compound 1

[Reaction Scheme 1-6]

Pd (OAc) ₂ (0.019 eq.), P (t-Bu) ₃ (50 wt%, 0.046 eq.) And sodium tert-butoxide (1.9 eq.) Were dissolved in toluene Was added to the solvent and stirred. And the mixture was refluxed and stirred at 120 ° C for 12 hours. After completion of the reaction, the reaction mixture was cooled to room temperature and extracted with water and ethyl acetate. Water was removed from the extracted organic layer with magnesium sulfate, and the remaining organic solvent was removed. Compound 1 was obtained by wet purification through column chromatography using hexane and ethyl acetate. (Yield: 55%).

2. Synthesis of Compound 2

(1) Synthesis of compound f

[Reaction Scheme 2-1]

(23.9 mmol), 1,4-dibromobenzene (35.8 mmol), palladium (II) acetate (2 mol%), tri-tertiary-butyl phosphate (5 mol%), sodium tert- Butoxide (2.03 equivalents) were mixed in a toluene solvent and stirred. The mixed solution was stirred under reflux and reacted for 12 hours. After completion of the reaction, the mixture was extracted with distilled water and ethyl acetate, and water was removed from the extracted organic layer using magnesium sulfate. The remaining organic solvent was removed, and the residue was subjected to column chromatography wet purification using ethyl acetate and hexane to obtain Compound (f). (Yield: 81%).

(2) Synthesis of Compound g

[Reaction Scheme 2-2]

In a nitrogen atmosphere, the compound f, bis (pinacolate) diboron (1.2 eq), [1,1-bis (diphenylphosphineo) ferrocene] palladium (II), dichloride dichloromethane, 1,1- Was mixed with 1,4-dioxane / toluene (1: 1) solvent in a flask which was shut off and stirred. When all the bubbles had disappeared, the mixture was stirred at 120 ° C for 17 hours. After the reaction is completed, the reaction mixture is cooled to room temperature, and then the solvent is removed and washed with toluene. Thereafter, the compound g was obtained by purification. (Yield: 90%).

(3) Synthesis of Compound 2

[Reaction Scheme 2-3]

Compound e was dissolved in a toluene solvent in a nitrogen atmosphere, and then compound g (1.2 eq.) Was added. Potassium carbonate (K ₂ CO ₃ , 8.8 equivalents) was dissolved in distilled water and then added to the reaction mixture. After additional addition of tetrahydrofuran, palladium (Pd, 0.1 eq) was added. The reaction mixture was stirred at reflux at 80 &lt; 0 &gt; C. After completion of the reaction, extraction was performed using an aqueous solution of sodium hydroxide and toluene, and water was removed from the extracted organic layer using magnesium sulfate. The remaining organic solvent was removed and purified by column chromatography using hexane. By recrystallization, Compound 2 was obtained. (Yield: 56%)

3. Synthesis of Compound 3

(1) Synthesis of compound h

[Reaction Scheme 3-1]

4-phenylbromosulfone was dissolved in a toluene solvent in a nitrogen atmosphere, and then phenylboronic acid (0.9 equivalent) was added. K ₂ CO ₃ (4 eq) was dissolved in distilled water and then added to the reaction mixture. A tetrahydrofuran solvent was added and palladium (Pd, 0.05 eq.) Was added. The reaction mixture is then stirred at reflux at 80 &lt; 0 &gt; C. After completion of the reaction, extraction was performed using an ethyl acetate solvent and distilled water, and water was removed from the extracted organic layer using magnesium sulfate. The remaining organic solvent was removed and purified by column chromatography using ethyl acetate and hexane to obtain a solid compound h. (Yield: 75%).

(2) Synthesis of Compound 3

[Reaction Scheme 3-2]

Pd (OAc) ₂ (0.019 eq.), P (t-Bu) ₃ (50 wt%, 0.046 eq.) And sodium tert-butoxide (1.9 eq.) Were dissolved in toluene Was added to the solvent and stirred. And the mixture was refluxed and stirred at 120 ° C for 12 hours. After completion of the reaction, the reaction mixture was cooled to room temperature and extracted with water and ethyl acetate. Water was removed from the extracted organic layer with magnesium sulfate, and the remaining organic solvent was removed. Compound 3 was obtained by wet purification through column chromatography using hexane and ethyl acetate. (Yield: 65%).

4. Synthesis of Compound 4

[Reaction Scheme 4]

Compound h was dissolved in a toluene solvent in a nitrogen atmosphere, and then compound g (1.2 eq.) Was added. Potassium carbonate (K ₂ CO ₃ , 8.8 eq.) Was dissolved in distilled water and then added to the reaction mixture. After additional addition of tetrahydrofuran, palladium (Pd, 0.1 eq) was added. The reaction mixture was stirred at reflux at 80 &lt; 0 &gt; C. After completion of the reaction, extraction was performed using an aqueous solution of sodium hydroxide and toluene, and water was removed from the extracted organic layer using magnesium sulfate. The remaining organic solvent was removed and purified by column chromatography using hexane. By recrystallization, Compound 4 was obtained. (Yield: 60%).

5. Synthesis of Compound 5

[Reaction Scheme 5]

In a nitrogen atmosphere, catalyst Pd (dba) ₂ (5% mol) and P (t-Bu) ₃ (4% mol) were added to a toluene solvent and stirred for about 15 minutes. 2-chloro-4,6-diphenyl-1,3,5-triazine (33.8 mmol), compound d (33.8 mmol) and NaOt-Bu (60.6 mmol) were further added thereto and stirred at 90 ° C for 5 hours. After the completion of the reaction, the celite was filtered to remove the remaining organic solvent. The filtered solid was purified by column chromatography using hexane and dichloromethane and recrystallized with hexane to obtain compound 5 by wet purification. (Yield: 59%)

6. Synthesis of Compound 6

[Reaction Scheme 6]

(1.1 eq.), Na ₂ CO ₃ (5 eq.) And NH ₄ Cl were dissolved in toluene / distilled water (1: 1) in a nitrogen atmosphere. Was added to the solvent and stirred. After stirring for 30 minutes while maintaining the nitrogen environment, tetrakis (triphenylphosphine) Pd (O) (0.05 equivalent) was added to the reaction mixture. The mixture was stirred for 10 minutes and then at 100 ° C for 16 hours. After completion of the reaction, the reaction mixture was cooled to room temperature and extracted with dichloromethane. Water was removed from the extracted organic layer using magnesium sulfate, and the remaining organic solvent was removed. The residue was purified by column chromatography using dichloromethane and hexane and then recrystallized with chloroform to obtain solid compound 6. (Yield: 70%).

7. Synthesis of Compound 7

(1) Synthesis of compound i

[Reaction Scheme 7-1]

4-azobenzimidazole, 1-bromo-4-iodobenzene (1.2 equivalents) and cesium carbonate (2 equivalents) were added to a dimethylformamide (DMF) solvent in which copper iodide (0.1 eq.) And 1,10-phenanthroline ) Were added. And the mixture was refluxed and stirred at 110 ° C for 16 hours. After completion of the reaction, the DMF solvent was removed and extracted with dichloromethane. Water was removed from the extracted organic layer with magnesium sulfate, and the remaining solvent was removed. Compound i was obtained by wet purification through column chromatography using ethyl acetate and hexane and recrystallization using dichloromethane. (Yield: 78%).

(2) Synthesis of Compound 7

[Reaction Scheme 7-2]

Pd (OAc) ₂ (0.019 eq.), P (t-Bu) ₃ (50 wt%, 0.046 eq.) And sodium tert-butoxide (1.9 eq.) Were dissolved in toluene Was added to the solvent and stirred. And the mixture was refluxed and stirred at 120 ° C for 12 hours. After completion of the reaction, the reaction mixture was cooled to room temperature and extracted with water and ethyl acetate. Water was removed from the extracted organic layer with magnesium sulfate, and the remaining organic solvent was removed. Compound 7 was obtained by wet purification through column chromatography using hexane and ethyl acetate. (Yield: 60%).

8. Synthesis of Compound 8

(1) Synthesis of compound j

[Reaction Scheme 8-1]

In a nitrogen atmosphere, 4-azabenzimidazole, 1-bromo-3,5-dimethyl-4-iodobenzene (1.3 equivalents) and cesium carbonate (2 equivalents) were added to a DMF solvent mixed with copper iodide (0.1 eq.) And 1,10-phenanthroline Equivalent) was further added. And the mixture was refluxed and stirred at 110 ° C for 16 hours. After completion of the reaction, the DMF solvent was removed and extracted with dichloromethane. Water was removed from the extracted organic layer with magnesium sulfate, and the remaining solvent was removed. Compound (j) was obtained by wet purification through column chromatography using ethyl acetate and hexane and recrystallization using dichloromethane. (Yield: 60%).

(2) Synthesis of Compound 8

[Reaction Scheme 8-2]

Pd (OAc) ₂ (0.019 eq.), P (t-Bu) ₃ (50 wt%, 0.046 eq.) And sodium tert-butoxide (1.9 eq.) Were dissolved in toluene Was added to the solvent and stirred. And the mixture was refluxed and stirred at 120 ° C for 12 hours. After completion of the reaction, the reaction mixture was cooled to room temperature and extracted with water and ethyl acetate. Water was removed from the extracted organic layer with magnesium sulfate, and the remaining organic solvent was removed. Compound 8 was obtained by wet purification through column chromatography using hexane and ethyl acetate. (Yield: 50%).

9. Synthesis of Compound 9

(1) Synthesis of compound k

[Reaction Scheme 9-1]

Benzimidazole, 1-bromo-4-iodobenzene (1.2 eq.) And cesium carbonate (2 eq.) Were added to the DMF solvent in which copper iodide (0.1 eq.) And 1,10-phenanthroline . And the mixture was refluxed and stirred at 110 ° C for 16 hours. After completion of the reaction, the DMF solvent was removed and extracted with dichloromethane. Water was removed from the extracted organic layer using magnesium sulfate, and the remaining solvent was removed. Compound k was obtained by wet purification through column chromatography using ethyl acetate and hexane and recrystallization using dichloromethane. (Yield: 80%).

(2) Synthesis of Compound 9

[Reaction Scheme 9-2]

In a nitrogen atmosphere, compound k, compound d (1.1 _{eq), Pd (OAc) 2 (} 0.019 eq.) And _{P (t-Bu) 3 (} 50 wt%, 0.046 equivalent), NaOt-Bu (sodium tert-butoxide, 1.9 Equivalent) was added to a toluene solvent and stirred. And the mixture was refluxed and stirred at 120 ° C for 12 hours. After completion of the reaction, the reaction mixture was allowed to cool to room temperature and extracted with water and ethyl acetate. Water was removed from the extracted organic layer with magnesium sulfate, and the remaining organic solvent was removed. Compound 9 was obtained by wet purification through column chromatography using hexane and ethyl acetate. (Yield: 62%).

10. Synthesis of Compound 10

(1) Synthesis of compound 1

[Reaction Scheme 10-1]

Benzimidazole, 1-bromo-3,5-dimethyl-4-iodobenzene (1.3 eq.) And cesium carbonate (2 eq.) Were added to a DMF solvent in which copper iodide (0.1 eq.) And 1,10-phenanthroline Were added. And the mixture was refluxed and stirred at 110 ° C for 16 hours. After completion of the reaction, the DMF solvent was removed and extracted with dichloromethane. Water was removed from the extracted organic layer with magnesium sulfate, and the remaining solvent was removed. Compound 1 was obtained by wet purification through column chromatography using ethyl acetate and hexane and recrystallization using dichloromethane. (Yield: 58%).

(2) Synthesis of Compound 10

[Reaction formula 10-2]

In a nitrogen atmosphere, the compound l, compound d (1.1 _{eq), Pd (OAc) 2 (} 0.019 eq.) And _{P (t-Bu) 3 (} 50 wt%, 0.046 equivalent), NaOt-Bu (sodium tert-butoxide, 1.9 Equivalent) was added to a toluene solvent and stirred. And the mixture was refluxed and stirred at 120 ° C for 12 hours. After completion of the reaction, the reaction mixture was allowed to cool to room temperature and extracted with water and ethyl acetate. Water was removed from the extracted organic layer with magnesium sulfate, and the remaining organic solvent was removed. Compound 10 was obtained by wet purification through column chromatography using hexane and ethyl acetate. (Yield: 46%).

The mass spectrometry results of the compounds 1 to 10 are shown in Table 1.

The emission characteristics of the compounds 3, 6, 7, and 9 (Com3, Com6, Com7, and Com9) were measured under the O ₂ free condition using a Quantarus tau equipment manufactured by Hamamatsu Co. The measurement results are shown in Tables 2 and 4A to 4D .

Compounds 3, 6, 7 and 9 (Com3, Com6, Com7 and Com9), which are retarding fluorescent compounds according to the present invention, each have a number of nanoseconds (ns) of several hundreds to tens of thousands as shown in Table 2 and FIGS. Delayed fluorescence.

As described above, the retarded fluorescent compound of the present invention is field activated to convert monophasic state (S ₁ ) excitons and triplet state (T ₁ ) excitons to intermediate states (I ₁ ) .

Such a field activating complex is a monomolecular compound having an electron donating moiety and an electron accepting moiety at the same time in one molecule, and electrons can easily migrate within the molecule. The electric field activating complexes may under certain conditions migrate electrons from the electron donor moiety to the electron acceptor moiety, resulting in the separation of charges within the molecule.

The electroluminescent complex to be elected is formed by the external environment, which can be easily confirmed by comparing the absorption wavelength and the emission wavelength in the solution state using various solvents.

In the above equation, Δν is the stock shift value, and νabs and νfl are the wavenumber of the maximum absorption wavelength and the maximum emission wavelength, respectively. H is the Plank? Constant, c is the velocity of light, a is the onsager cavity radius, and? Μ is the difference between the dipole moment of the exited state and the dipole moment of the ground state (Δμ = μ _{e- g} ).

Δf is the value representing the orientational polarizability of the solvent and is expressed by the dielectric constant (ε) and the refractive index (n) of the solvent as shown in the following equation.

The formation of the field activation complex can be confirmed by comparing the absorption wavelength and the emission wavelength in the solution state using various solvents. This is because the degree of polarization (magnitude of the dipole moment) when excited is determined by the surrounding polarity.

The directional polarization degree of the mixed solvent, Δf, can be calculated by calculating the ratio of the polarizability of the pure solvent to the mole fraction, respectively. The presence or absence of the electric field activating complex can be calculated using the above equation (Lippert-Mataga equation) By plotting and plotting a linear relationship.

That is, the electric field activating complex is stabilized according to the directional polarization degree of the solvent, and the emission wavelength shifts to a long wavelength according to the stabilization degree. Therefore, when an electric field activating complex is formed, Δf and Δν form a linear graph. Conversely, when Δf and Δν form a linear graph, the light emitting material is an electric field activating complex.

In the retarded fluorescent compound of the present invention, 25% of the singlet-state excitons and 75% of the triplet-state excitons are excited by an electromagnetic field generated in the external environment, for example, an organic light-emitting diode device, And the quantum efficiency is improved because light is emitted from the intermediate state to the ground state. That is, in the fluorescent material, as well as singlet state excitons, triplet state excitons participate in luminescence, thereby improving the luminous efficiency.

Hereinafter, the performance of the organic light emitting diode using the retardation fluorescent compound of the present invention and the organic light emitting diode using the comparative substance of the formula (6) will be compared.

Device fabrication

The ITO substrate was patterned to have a light emitting area of 3 mm x 3 mm and then cleaned. Next, the substrate was transferred into a vacuum deposition chamber. (N, N'-di (naphthalen-1-yl) -N, N'-dicyclohexylcarbodiimide) on the ITO which is the anode after the base pressure is about 10 ^-6 to 10 ^-7 Torr. diphenyl-benzidine), ii) a hole transport layer (100 Å, mCP (N, N'-Dicarbazolyl-3,5-benzene) ] phenyl ether oxide / dopant (6%), iv) an electron transport layer (300 ANGSTROM, phenyl-2-benzimidazole) -benzene, v) an electron injection layer (LiF) (Al) were successively laminated.

(1) Comparative Example (Ref)

In the above-described device, the compound of Chemical Formula 6 was used as a dopant of the light emitting material layer.

(2) Experimental Example 1 (Ex1)

In the above-mentioned device, Compound 3 was used as a dopant of the light emitting material layer.

(3) Experimental Example 2 (Ex2)

In the above-mentioned device, Compound 6 was used as a dopant of the light emitting material layer.

(4) Experimental Example 3 (Ex3)

In the above-mentioned device, Compound 7 was used as a dopant of the light emitting material layer.

(5) Experimental Example 4 (Ex4)

In the above-described device, Compound 9 was used as a dopant of the light emitting material layer.

[Chemical Formula 6]

As can be seen from Table 3, the organic light emitting diode device using the retarded fluorescent compound of the present invention has improved characteristics in terms of driving voltage, luminous efficiency, and the like.

An embodiment of the organic light emitting diode device including the above retarded fluorescent compound is shown in FIG.

As shown in FIG. 5, the organic light emitting diode device includes a light emitting diode (E) located on a substrate (not shown).

The light emitting diode E includes a first electrode 110 serving as an anode, a second electrode 130 serving as a cathode, and an organic light emitting layer 120 formed between the first and second electrodes 110 and 130. Lt; / RTI &gt;

Although not shown, a display device including an encapsulation film including an inorganic layer and an organic layer and covering the light emitting diode E and a cover window on the encapsulation film may be formed. At this time, the substrate and the cover window have flexible characteristics, and a flexible display device can be achieved.

The first electrode 110 is made of a relatively high work function material such as indium-tin-oxide (ITO), and the second electrode 130 is made of a material having a relatively low work function value, For example, aluminum (Al) or an aluminum alloy (AlNd). In addition, the organic light emitting layer 120 may have red, green, and blue organic emission patterns.

The organic light emitting layer 120 may have a single layer structure or the organic light emitting layer 120 may have a multi-layer structure to improve the light emitting efficiency. For example, a hole injection layer (HIL) 121, a hole transporting layer (HTL) 122, an emitting material layer (EML) 122, An electron transport layer (ETL) 124, and an electron injection layer (EIL) 125.

At least one of the hole injecting layer 121, the hole transporting layer 122, the light emitting material layer 123, the electron transporting layer 124, and the electron injecting layer 125 may include a retardation fluorescent compound represented by Formula 1 .

For example, the light emitting material layer 123 may include a retardation fluorescent compound represented by Formula 1. [ The light emitting material layer 123 may include the delayed fluorescent compound of the present invention as a dopant material and may be doped to about 1 to 30 wt% with respect to the host, thereby emitting blue light.

The difference between the highest level occupied molecular orbital level (HOMO _Host ) of the _host and the highest level occupied molecular orbital level (HOMO _Dopant ) of the _dopant (| HOMO _Host- HOMO _Dopant |) or the lowest level non occupied molecular orbital level _Host) and the lowest unoccupied molecular orbital level level (LUMO _dopant) difference (the dopant | LUMO _{Host dopant} -LUMO |) must be greater than 0.5eV. This improves the charge transfer efficiency from the host to the dopant.

For example, as a host satisfying such a condition, any one of the following formula (7) can be used. (DPEPO), 2,8-bis (diphenylphosphoryl) dibenzothiophene (PPT), 2,8-di (9H-carbazol-9-yl) dibenzothiophene (DCzDBT), m 9- (9-phenyl-9H-carbazol-6-yl) -9H-carbazole (CCP) )

(7)

At this time, the triplet energy of the dopant is smaller than the triplet energy of the host, the difference (ΔE _ST) of the singlet energy of the triplet energy of the dopant and the dopant is characterized in that not more than 0.3eV. The smaller the ΔE _ST increase the luminous efficiency, and the delayed fluorescent compound of the invention, the energy difference between the singlet and triplet energy of the dopant (ΔE _ST) is about 0.3eV, even if a relatively large singlet state by an electric field (S ₁ ) the exciton and triplet state (T ₁ ) excitons can transition to the intermediate state (I ₁ ). (ΔE _ST ≤0.3)

Meanwhile, the light emitting material layer 123 may include a dopant that is doped to about 1 to 30 wt% with respect to the host material, and emits blue light. The development of a blue host having excellent properties is not sufficient. Therefore, the degree of freedom in host selection can be increased by using the retarded fluorescent compound of the present invention as a host material.

At this time, the triplet energy of the dopant is smaller than the triplet energy of the host, which is the retarded fluorescent compound of the present invention.

In addition, the light emitting material layer 123 may include a retardation fluorescent compound of the present invention as a first dopant material, and may further include a host material and a second dopant material. The sum of doped first and second dopant materials may be, Doped to about 1 to 30 wt% with respect to the host material, thereby emitting blue light. Since the light emitting material layer 123 includes the host material and the first and second dopant materials, luminous efficiency and color tone are further improved.

In this case, the triplet energy of the first dopant, which is a retarding fluorescent compound of the present invention, is smaller than the triplet energy of the host and is larger than the triplet energy of the second dopant. At this time, the difference in energy singlet and triplet energy of the first dopant of the first dopant (ΔE _ST) is characterized in that not more than 0.3eV. The smaller the ΔE _ST increase the luminous efficiency, and delayed fluorescent compound, which is a difference of energy singlet and triplet energy of the first dopant (ΔE _ST) a singlet by an electric field even if a relatively large about 0.3eV of the invention the state ( S ₁ ) excitons and triplet state (T ₁ ) excitons can transition to the intermediate state (I ₁ ). (ΔE _ST ≤0.3)

As described above, the retarded fluorescent compound of the present invention includes both an electron donor moiety and an electron acceptor moiety, and the electron donor moiety is an electron donor moiety and an electron donor moiety having a large steric hindrance. Since it is Cridine, the luminous efficiency is further improved. Further, a dipole is formed from the electron donor moiety to the electron acceptor moiety to increase the dipole moment inside the molecule, thereby further increasing the luminous efficiency. Further, in the retarding fluorescent compound of the present invention, since the triplet exciton is used for luminescence, the luminescent efficiency is improved.

By increasing the distance between the electron donor moiety and the electron donor moiety by the linker, the overlap between HOMO and LUMO is reduced, which can reduce the difference between triplet energy and singlet energy (ΔE _ST ).

In addition, the problem of red shift of light emitted from the light emitting layer including the retarded fluorescent compound can be minimized by steric hindrance of the linker.

Therefore, the organic light emitting diode device including the retarded fluorescent compound of the present invention can improve the luminous efficiency and realize a high quality image.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention as defined in the appended claims. It can be understood that

110: first electrode 120: organic light emitting layer
121: Hole injection layer 122: Hole transport layer
123: luminescent material layer 124: electron transport layer
125: electron injection layer 130: second electrode
E: organic light emitting diode

Claims (14)

An acridine electron donating moiety is substituted or unsubstituted triazine, substituted or unsubstituted dibenzothiophene via a benzene linker, either directly or through a substituted or unsubstituted benzene linker, , A substituted or unsubstituted diphenylsulfone, a substituted or unsubstituted 4-azabenzimidazole, a substituted or unsubstituted benzimidazole, and the like. Delayed fluorescent compound having molecular formula of structure.
1. A retardation fluorescent compound represented by the following formula (1), wherein X is selected from the following formula (2) and Y is selected from the following formula (3). (n is 0 or 1)
[Chemical Formula 1]

(2)

(3)

Wherein each of R 1 to R 4 is independently selected from substituted or unsubstituted aryl, and each of R 5 and R 6 is independently selected from hydrogen or C 1 to C 10 alkyl.
3. The method of claim 2,
Wherein the delayed fluorescent compound is any one of the following compounds.

3. The method according to claim 1 or 2,
Wherein the difference between the singlet energy and the triplet energy of the retarding fluorescent compound is 0.3 eV or less.
A first electrode;
A second electrode facing the first electrode;
And an organic light emitting layer disposed between the first and second electrodes,
The organic light-
An acridine electron donating moiety is substituted or unsubstituted triazine, substituted or unsubstituted dibenzothiophene via a benzene linker, either directly or through a substituted or unsubstituted benzene linker, , A substituted or unsubstituted diphenylsulfone, a substituted or unsubstituted 4-azabenzimidazole, a substituted or unsubstituted benzimidazole, and the like. Wherein the organic light emitting diode device comprises a retardation fluorescent compound having a molecular formula of the structure.
A first electrode;
A second electrode facing the first electrode;
And an organic light emitting layer disposed between the first and second electrodes,
The organic light-
1. An organic light-emitting diode device comprising a retardation fluorescent compound represented by the following formula (1), X is selected from the following formula (2), and Y is selected from the following formula (3). (n is 0 or 1)
[Chemical Formula 1]

(2)

(3)

Wherein each of R 1 to R 4 is independently selected from substituted or unsubstituted aryl, and each of R 5 and R 6 is independently selected from hydrogen or C 1 to C 10 alkyl.
The method according to claim 6,
Wherein the retarding fluorescent compound is any one of the following compounds.

The method according to claim 5 or 6,
Wherein the difference between the singlet energy and the triplet energy of the retarding fluorescent compound is 0.3 eV or less.
The method according to claim 5 or 6,
Wherein the retarded fluorescent compound is used as a dopant, and the organic light emitting layer further comprises a host.
10. The method of claim 9,
The difference between the highest level occupied molecular orbital level (HOMO _Host ) of the _host and the highest level occupied molecular orbital level (HOMO _Dopant ) of the _dopant (| HOMO _Host- HOMO _Dopant |) or the lowest level non occupied molecular orbital level _Host) and the lowest unoccupied molecular orbital level level (LUMO _dopant) a difference between the dopant (| LUMO _{Host dopant} -LUMO |) is not more than 0.5eV organic light emitting diode device.
The method according to claim 5 or 6,
Wherein the retarded fluorescent compound is used as a host, and the organic light emitting layer further comprises a dopant.
The method according to claim 5 or 6,
Wherein the retarded fluorescent compound is used as a first dopant, the organic light emitting layer further comprises a host and a second dopant,
Wherein the first triplet energy of the first dopant is less than the second triplet energy of the host and greater than the third triplet energy of the second dopant.
The method according to claim 5 or 6,
Wherein the organic light emitting layer includes a hole injection layer, a hole transporting layer, a light emitting material layer, an electron transporting layer, and an electron injection layer,
Wherein at least one of the hole injecting layer, the hole transporting layer, the light emitting material layer, the electron transporting layer, and the electron injecting layer comprises the retarding fluorescent compound.
Claims [1]
The organic light emitting diode device of claim 5 or 6, which is located on the substrate;
An encapsulation film covering the organic light emitting diode device;
And a cover window on the encapsulation film.

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