KR20160045570A - Delayed Fluorescence compound, and Organic light emitting diode device and Display device using the same - Google Patents

Abstract

Provided in the present invention is a delayed fluorescence compound having molecular formula that an electron-donating moiety of indolo-[3,2,1-j,k]carbazole and an electron-accepting moiety selected from pyridine, diphenyl pyrimidine, and diphenyl triazine are linked by a linker which is substituted or unsubstituted benzene. The delayed fluorescence compound in the present invention solves a problem of low quantum efficiency of a fluorescence substance.

Description

TECHNICAL FIELD [0001] The present invention relates to a retardation fluorescent compound, an organic light emitting diode (OLED) device, and a display device using the retardation fluorescent compound.

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 retarding fluorescent compound of the present invention has a molecular formula in which an electron donor moiety of an indolo- [3,2,1-j, k] carbazole and an electron acceptor moiety are bonded by a linker .

The electron acceptor moiety may be selected from pyridine, diphenylpyrimidine, diphenyltriazine, and the linker may be substituted or unsubstituted benzene.

That is, the retarding fluorescent compound of the present invention is represented by the following formula, A may be one of pyridine, diphenylpyrimidine, and diphenyltriazine, and L may be substituted or unsubstituted benzene.

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

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 retardation fluorescent compound of the present invention has a structure in which an electron donor moiety and an electron acceptor moiety are bonded by a linker, so that the charge can easily move within the molecule and the light emission 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, since indolocarbazole having high triplet energy and excellent hole properties is used as an electron donor moiety, the luminous efficiency is further improved.

In addition, a dipole is formed from one or more electron donor moieties to electron acceptor moieties to increase the dipole moment inside the molecule, 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 A field activated delayed fluorescence complex is formed to further improve the luminous efficiency of the retarded fluorescent compound. The overlap of HOMO and LUMO of the molecule can be increased by introducing the linker, but since the molecule is folded by the linker, overlapping of HOMO and LUMO is suppressed, and it is possible to form an electric field activation delayed fluorescent complex.

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.

Accordingly, the luminous efficiency of the organic light emitting diode device and the display device including the retarded fluorescent compound of the present invention is also improved.

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 graphs showing delayed fluorescence characteristics of a retarded fluorescent compound according to an embodiment of the present invention.
3 is a Lippert-Mataga plot of a retarded fluorescent compound according to an embodiment of the present invention.
4 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 indole- [3,2,1-j, k] carbazole from electron donating moieties selected from pyridine, diphenyl pyrimidine and diphenyl triazine Wherein the electron acceptor moiety is bonded by a linker that is a substituted or unsubstituted benzene.

로 표시되며, A는

에서 선택되고, L은

인 지연 형광 화합물을 제공한다. (여기서, X, Y, Z 각각은 독립적으로 탄소 또는 질소이며, X, Y, Z는 같거나 다를 수 있고, X, Y, Z 중 적어도 둘은 질소이며, R은 C1~C10의 알킬이다.)In another aspect,

And A is

L < / RTI >

≪ / RTI > Wherein X, Y and Z are each independently carbon or nitrogen, and X, Y and Z may be the same or different and at least two of X, Y and Z are nitrogen and R is C1-C10 alkyl. )

The retarding fluorescent compound may be any one of the following compounds.

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

According to another aspect of the present invention, there is provided 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, - an electron donor moiety selected from the electron acceptor moiety of [3,2,1-j, k] carbazole and pyridine, diphenyl pyrimidine and diphenyl triazine, And a delayed fluorescent compound having a molecular formula which is bonded by a linker that is substituted or unsubstituted benzene.

로 표시되며, A는 According to another aspect of the present invention, there is provided 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,

And A is

에서 선택되고, L은

인 지연 형광 화합물을 포함하는 유기발광다이오드소자를 제공한다. (여기서, X, Y, Z 각각은 독립적으로 탄소 또는 질소이며, X, Y, Z는 같거나 다를 수 있고, X, Y, Z 중 적어도 둘은 질소이며, R은 C1~C10의 알킬이다.)

L < / RTI >

Lt; RTI ID = 0.0 > fluorescent < / RTI > compound. Wherein X, Y and Z are each independently carbon or nitrogen, and X, Y and Z may be the same or different and at least two of X, Y and Z are nitrogen and R is C1-C10 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.

The present invention also provides a display device including the above-described organic light emitting diode positioned on a substrate, an encapsulation film covering the organic light emitting diode, and a cover window on the encapsulation film.

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 is an electron donor which is an indolo- [3,2,1-j, k] carbazole (indolo- [3,2,1- The moiety has a structure in which the electron acceptor moiety is bonded to the electron acceptor moiety via a linker.

[Chemical Formula 1]

In the above formula (1), The electron acceptor moiety A may be selected from the substances represented by the following formula (2-1).

[Formula 2-1]

In Formula 2-1, each of X, Y and Z may independently be carbon or nitrogen, and X, Y and Z may be the same or different, and at least two of them may be nitrogen.

For example, the electron acceptor moiety A may be selected from the substances represented by the following formula (2-2). That is, the electron acceptor moiety A may be selected from pyridine, diphenyl pyrimidine, and diphenyl triazine

[Formula 2-2]

In the above formula (1), the linker L may be represented by the following formula (3-1).

[Formula 3-1]

In Formula 3-1, R may be C1-C10 alkyl.

For example, the linker L may be selected from the materials represented by the following formula (3-2). That is, the linker L may be selected from substituted or unsubstituted benzene.

[Formula 3-2]

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, since indolo- [3,2,1-j, k] carbazole, which has high triplet energy and excellent hole properties, is used as an electron donor moiety, the luminous efficiency is further improved. (HOMO: -5.56 eV, LUMO: -1.25 eV, E _T = 3.04 eV)

Further, since the intramolecular vibration is reduced by the formation of a rigid structure by indolo- [3,2,1-j, k] carbazole, the red shift problem is reduced. That is, the color purity improves. Further, since the molecular weight is large, the thermal stability of the compound is increased.

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.

Further, the problem of red shift of the light emitted from the light emitting layer containing the retarded fluorescent compound is further reduced by the steric hindrance of the linker. That is, when the retarding fluorescent compound of the present invention is used, deep blue light emission can be obtained.

On the other hand, the introduction of the linker can increase the superposition of HOMO and LUMO of the molecule, but since the molecule has a structure bent by the linker, the overlapping of HOMO and LUMO is suppressed, and the formation of the electric field activating complex becomes possible.

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 delayed fluorescent compound of formula (1) may be any of the compounds of formula (4). (Compound 1 to Compound 7 in this order)

[Chemical Formula 4]

Further, the retarded fluorescent compound of the present invention has a wide energy band gap, and the luminous efficiency of the organic light emitting diode device including the same is further improved.

The HOMO, LUMO, and energy bandgaps of the compounds 1 to 7 are shown in Table 1.

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

Synthetic example

1. Synthesis of Compound 1

(1) Synthesis of Compound C

Scheme 1

Compound A, 1.1 equivalents of compound B and 1.5 equivalents of cesium carbonate were placed in dimethylsulfoxide under N2 purging and stirred. After stirring at room temperature for about 2 hours, the mixture was placed in a 60 degree oil bath and stirred. After 8 hours, the reaction was added dropwise to Ice DI water to give a yellow solid. The filtered solid was extracted with dichloromethane and DI water, and water was removed with MgSO ₄ . After removal of the organic solvent, recrystallization was carried out using dichloromethane / methanol to obtain the compound C.

(2) Synthesis of Compound D

Scheme 2

Under a nitrogen atmosphere, Compound C, 3 equivalents of SnCl ₂ .H ₂ O were added to ethanol and stirred at 70 ° C for 8 hours. After completion of the reaction, the reaction mixture was cooled to room temperature, and then added dropwise to an aqueous 1N sodium hydroxide solution to obtain a solid. The solids were filtered and redissolved in dichloromethane and extracted with 1N aqueous sodium hydroxide solution. The aqueous layer was removed, and the organic layer was re-extracted with DI water and water was removed with MgSO ₄ . The organic solvent was removed to obtain a precipitate, Compound D.

(3) Synthesis of Compound E

Scheme 3

Compound D was placed in acetic acid in an ice bath environment, sulfuric acid was added dropwise, and the mixture was stirred. 1.1 equivalents of sodium nitrite were dissolved in DI water, then slowly added dropwise to the flask with compound D for 15 minutes and further stirred for 10 minutes. The flask was placed in an oil bath and allowed to react at 130 ° C for 20 minutes before the reaction was terminated. After cooling to room temperature, DI water was added to the reaction product to obtain a precipitate. The precipitate was filtered, rinsed with methanol, and the filtered material was recrystallized using a column and dichloromethane / methanol to obtain Compound E.

(4) Synthesis of Compound F

Scheme 4

Under a nitrogen atmosphere, Compound E and 1.1 equivalents of N-Bromosuccinimide were added to dichloromethane in a flask with light shielding and stirred at room temperature for 12 hours. After completion of the reaction, the reaction mixture was extracted with dichloromethane and DI water, and water was removed with MgSO ₄ . The obtained compound was purified to obtain Compound F. [

(5) Synthesis of Compound G

Scheme 5

Under nitrogen atmosphere, Compound F, 1.2 equivalents of bis (pinacolate) diboron, [1,1-bis (diphenylphosphineo) ferrocene] palladium (II), dichloride dichloromethane, 1,1-bis (diphenylphosphino) ferrocene, 1,4-dioxane / toluene (1: 1) in a flask and stirred. After the bubbles were removed, the mixture was stirred in an oil bath at 120 ° C for 17 hours. After completion of the reaction, the reaction mixture was cooled to room temperature, and then the solvent was removed and washed with dichloromethane. The obtained material was purified to obtain a compound G. [

(6) Synthesis of Compound (I)

Scheme 6

Under nitrogen, compound G was dissolved in tetrahydrofuran / toluene (5: 1) and 0.9 equivalent of compound H was added. 4.4 equivalents of potassium carbonate was dissolved in DI water and 0.05 equivalent of Pd was added. The reaction mixture was then refluxed at 80 DEG C and stirred for 24 hours to terminate the reaction. After extraction with an organic solvent, the organic solvent was removed. After the column, Compound I, which is a precipitate, was obtained.

(7) Synthesis of Compound L

Scheme 7

Under a nitrogen atmosphere, two equivalents of compound K were dissolved in tetrahydrofuran in a light-blocked flask at -78 ° C, and then n-butyl lithium was slowly added dropwise. Compound J was dissolved in tetrahydrofuran in another flask under a nitrogen atmosphere. Compound J was added dropwise to a flask containing compound K using a cannula so that the nitrogen environment was maintained, followed by stirring for 8 hours. After completion of the reaction, Compound L was obtained through purification.

(8) Synthesis of compound 1

Scheme 8

Under a nitrogen atmosphere, 1.2 equivalents of Compound I was dissolved in tetrahydrofuran in a light-blocked flask at -78 ° C, and then n-butyl lithium was slowly added dropwise. Compound L was dissolved in tetrahydrofuran in another flask under a nitrogen atmosphere. Compound I was added dropwise to a flask containing compound L using a cannula so that the nitrogen environment was maintained, followed by stirring for 8 hours. After completion of the reaction, purification was conducted to obtain Compound 1.

2. Synthesis of Compound 2

(1) Synthesis of Compound G-1

Scheme 9

Under nitrogen, Compound I, 1.2 equivalents of bis (pinacolate) diboron, [1,1-bis (diphenylphosphineo) ferrocene] palladium (II), dichloride dichloromethane, 1,1-bis (diphenylphosphino) ferrocene, Dioxane / toluene (1/1) solvent in the flask, and stirred. When the bubbles disappeared, the mixture was stirred in an oil bath of 120 degrees for 20 hours. After completion of the reaction, the reaction mixture was cooled to room temperature and then the solvent was removed. washed with toluene and purified to obtain Compound G-1.

(2) Synthesis of Compound 2

Scheme 10

Under a nitrogen atmosphere, Compound K-1 was dissolved in toluene, and 1.2 equivalent of Compound G-1 was added. 4.4 equivalents of potassium carbonate (K ₂ CO ₃₎ was added to the reaction mixture was dissolved in DI water. After addition of tetrahydrofuran, 0.05 equivalent of palladium (Pd) was added. Thereafter, the reaction mixture was refluxed at 80 DEG C and stirred. After extraction, recrystallization was performed for separation from the compound G-1, K-1 and the adduct, and column 2 was obtained by column chromatography with dichloromethane / hexane.

3. Synthesis of Compound 3

Scheme 11

Under a nitrogen atmosphere, Compound K-2 was dissolved in toluene, and 1.2 equivalent of Compound G-1 was added. 4.4 equivalents of potassium carbonate (K ₂ CO ₃₎ was added to the reaction mixture was dissolved in DI water. After addition of tetrahydrofuran, 0.05 equivalent of palladium (Pd) was added. Thereafter, the reaction mixture was refluxed at 80 DEG C and stirred. After extraction, recrystallization was performed for separation from the compounds G-1 and K-2 and adducts, and column 3 was obtained by column chromatography with dichloromethane / hexane.

4. Synthesis of Compound 4

Scheme 12

Under a nitrogen atmosphere, Compound K-3 was dissolved in toluene, and 1.2 equivalent of Compound G-1 was added. 4.4 equivalents of potassium carbonate (K ₂ CO ₃₎ was added to the reaction mixture was dissolved in DI water. After addition of tetrahydrofuran, 0.05 equivalent of palladium (Pd) was added. Thereafter, the reaction mixture was refluxed at 80 DEG C and stirred. After the extraction, the compound G-1, K-3 and the addition product were recrystallized for separation, and column 4 was obtained by column chromatography with dichloromethane / hexane.

5. Synthesis of Compound 5

(1) Synthesis of Compound I-1

Scheme 13

Under nitrogen, compound G was dissolved in tetrahydrofuran / toluene (5: 1) and 0.9 equivalent of compound H-1 was added. 4.4 equivalents of potassium carbonate was dissolved in Di water and 0.05 equivalent of Pd was added. The reaction mixture was then refluxed at 80 &lt; 0 &gt; C and stirred for 24 hours to terminate the reaction. After extraction with an organic solvent, the organic solvent was removed. After the column, Compound I-1 as a precipitate was obtained.

(2) Synthesis of Compound 5

Scheme 14

Under a nitrogen atmosphere, 1.2 equivalents of Compound I-1 was dissolved in tetrahydrofuran in a light-blocked flask at -78 ° C, and then n-butyl lithium was slowly added dropwise. Compound L was dissolved in tetrahydrofuran in another flask under a nitrogen atmosphere. Compound I was added dropwise to a flask containing compound L using a cannula so that the nitrogen environment was maintained, followed by stirring for 8 hours. After completion of the reaction, Compound 5 was obtained through purification.

6. Synthesis of Compound 6

(1) Synthesis of Compound G-2

Scheme 15

Under nitrogen, compound I-1 and 1.2 equivalents of bis (pinacolate) diboron, [1,1-bis (diphenylphosphineo) ferrocene] palladium (II), dichloride dichloromethane, 1,1-bis (diphenylphosphino) ferrocene, Dioxane / toluene (1/1) solvent in a flask shielded from light, and stirred. Then, when the air bubbles disappeared, the mixture was stirred in an oil bath of 120 degrees for 20 hours. After completion of the reaction, the reaction mixture was cooled to room temperature, and then the solvent was removed and washed with toluene. To obtain Compound G-2.

(2) Synthesis of Compound 6

Scheme 16

Under a nitrogen atmosphere, Compound K-1 was dissolved in toluene, and 1.2 equivalent of Compound G-2 was added. 4.4 equivalents of potassium carbonate (K ₂ CO ₃₎ was added to the reaction mixture was dissolved in DI water. After addition of tetrahydrofuran, 0.05 equivalent of palladium (Pd) was added. Thereafter, the reaction mixture was refluxed at 80 DEG C and stirred. After extraction, the product was recrystallized for separation from the compound G-2, K-1 and the adduct, and column 6 was obtained by column chromatography with dichloromethane / hexane.

7. Synthesis of Compound 7

Scheme 17

Under a nitrogen atmosphere, Compound K-3 was dissolved in toluene, and 1.2 equivalent of Compound G-2 was added. 4.4 equivalents of potassium carbonate (K ₂ CO ₃₎ was added to the reaction mixture was dissolved in DI water. After addition of tetrahydrofuran, 0.05 equivalent of palladium (Pd) was added. Thereafter, the reaction mixture was refluxed at 80 DEG C and stirred. After extraction, the product was recrystallized for separation from the compound G-2, K-3 and the adduct, and column 7 was obtained by column chromatography with dichloromethane / hexane.

The mass spectrometry results of the compounds 1 to 7 are shown in Table 2.

The emission characteristics of the compounds 1 and 2 (Com1 and Com2) were measured under O ₂ free conditions using a Quantarus tau equipment manufactured by Hamamatsu. The measurement results are shown in Table 3 and FIGS. 2A and 2B.

As shown in Table 3 and FIGS. 2A and 2B, each of the compounds 1 and 2 (Com1 and Com2), which are retarding fluorescent compounds according to the present invention, exhibited a delayed fluorescence phenomenon of hundreds to tens of nanoseconds (ns).

Table 4 shows the maximum absorption wavelength, the maximum emission wavelength, and the Stocks shift value according to the solvent of the compound 1 obtained through the above synthesis example.

As shown in Table 4, the retarded fluorescent compound of the present invention has the maximum absorption wavelength at 338 nm regardless of the kind of solvent, while the emission spectrum varies depending on the kind of solvent. That is, when toluene having a small solvent polarity is used, the retarded fluorescent compound of the present invention has the maximum emission wavelength at 434 nm, but in the CHCl ₃ and THF mixed solvent having a large solvent polarity, And has a wavelength. As described above, the retarded fluorescent compound of the present invention exhibits a red shift in the maximum emission wavelength as the polarity of the solvent increases.

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 donor moiety and an electron acceptor moiety at the same time in one molecule, and electrons can easily migrate in 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 Δμ form a linear graph. Conversely, when Δf and Δμ form a linear graph, the light emitting material is an electric field activating complex.

Referring to the Lippert-Mataga plot of FIG. 3, the directional polarization degree (? F) of the solvent and the stock shift value have a linear relationship (R ² = 0.94), and the retarded fluorescent compound of the present invention has a single relationship with the triplet exciton And all the excitons are fluorescent materials participating in luminescence.

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 device using the delayed fluorescent compound of the present invention and the organic light emitting diode device using the comparative substance of Formula 5 will be described.

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. And the base pressure was about 10 ^-6 to 10 ^-7 Torr. Then, on the anode ITO, i) a hole injecting layer of 40 Å (NPB (N, N'-di (naphthalen- benzidine), ii) mCP (N, N'-Dicarbazolyl-3,5-benzene), iii) luminescent material layer 200 Å (bis {2- {di (phenyl) ether oxide / dopant (15%), iv) phenyl-2-benzimidazole-benzene, v) electron injecting layer 10 Å (LiF) Respectively.

(1) Comparative Example (Ref)

In the above-mentioned device, the compound of Chemical Formula 5 was used as a dopant of the light emitting material layer.

(2) Experimental Example 1 (Ex1)

In the above-mentioned device, Compound 1 was used as a dopant of the light emitting material layer.

(3) Experimental Example 2 (Ex2)

In the above-described device, Compound 2 was used as a dopant of the light emitting material layer.

(4) Experimental Example 3 (Ex3)

In the above-described device, Compound 4 was used as a dopant of the light emitting material layer.

[Chemical Formula 5]

As can be seen from Table 5, 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, color purity, and the like.

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

As shown, 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 (HTL) 121, a hole transporting layer (HIL) 122, an emitting material layer (EML) 122, An electron injection layer 123, an electron transporting layer 124, and an electron injection layer 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 formulas (6) 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) )

[Chemical Formula 6]

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, so that electron movement in a molecule is easily performed and luminous 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. Further, in the retarding fluorescent compound of the present invention, since the triplet exciton is used for luminescence, the luminescent efficiency is improved.

Accordingly, the luminous efficiency of the organic light emitting diode device including the retarded fluorescent compound of the present invention is also improved.

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 (13)

An electron acceptor moiety selected from pyridine, diphenylpyrimidine, and diphenyl triazine, the electron donating moiety of indolo [3,2,1-j, k] carbazole, Is bonded by a linker which is a substituted or unsubstituted benzene.
Wherein A is selected from the following formula (2), and L is selected from the following formula (3).
[Chemical Formula 1]

(2)

(3)

Wherein X, Y and Z are each independently carbon or nitrogen, and X, Y and Z may be the same or different, and at least two of X, Y and Z are nitrogen, and R in the formula (3) To C10 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 electron donor moiety selected from pyrrolidine, diphenylpyrimidine, and diphenyl triazine, the electron acceptor moiety of indolo- [3,2,1-j, k] carbazole, Wherein the organic light-emitting diode device comprises a retardation fluorescent compound having a molecular formula that is bonded by a linker that is substituted or unsubstituted benzene.
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-
Wherein A is selected from the following formula (2), and L is a delayed fluorescent compound selected from the following formula (3).
[Chemical Formula 1]

(2)

(3)

Wherein X, Y and Z are each independently carbon or nitrogen, and X, Y and Z may be the same or different, and at least two of X, Y and Z are nitrogen, and R in the formula (3) To C10 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 - LUMO dopant |} ) 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.
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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