KR101835934B1 - Oled having host exhibiting delayed fluorescence - Google Patents

Abstract

Thereby providing an organic light emitting diode. The organic light emitting diodes include an anode and a cathode. A light emitting layer containing a host and a dopant is disposed between the anode and the cathode. Said host is a material that exhibits a delayed fluorescence, of the host T ₁ level (T ₁ ^H), S ₁ levels (S ₁ ^H) of the host, and the T ₁ level (T ₁ ^D) of the dopant is to equation 1 and 2, respectively.
&Quot; (1) "
T ₁ ^H ? T ₁ ^D
&Quot; (2) "
S ₁ ^H > T ₁ ^D

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an OLED (Organic Light Emitting Diode)

The present invention relates to an organic photoelectric device, and more particularly to an organic light emitting diode.

An organic light emitting diode (OLED) is a self-luminous type device having a wide viewing angle, excellent contrast, fast response time, excellent luminance, driving voltage and response speed characteristics, and multi-coloring.

A typical organic light emitting diode may include an anode and a cathode and an organic layer interposed between the anode and the cathode. The organic layer may include an electron injecting layer, a hole transporting layer, a light emitting layer, an electron transporting layer, and an electron injecting layer. When a voltage is applied between the anode and the cathode, holes injected from the anode move to the light emitting layer via the hole transporting layer, and electrons injected from the cathode move to the light emitting layer via the electron transporting layer. Carriers such as holes and electrons recombine in the light emitting layer region to generate an exiton, which is converted to a base state and light is generated.

Among organic light emitting diodes, an organic light emitting diode using a phosphorescent light emitting layer is theoretically capable of achieving a quantum efficiency of 100%. The phosphorescent light-emitting layer contains a host and a dopant. It is known that a host must have a triplet energy higher than that of a dopant so that the exciton can be transferred from the host to the dopant to realize high efficiency. However, in the case of a host having a high triplet energy, the singlet energy is also high, which may cause a rise in driving voltage.

An object of the present invention is to provide an organic light emitting diode having a low driving voltage and improved efficiency.

According to an aspect of the present invention, there is provided an organic light emitting diode. The organic light emitting diodes include an anode and a cathode. A light emitting layer containing a host and a dopant is disposed between the anode and the cathode. Said host is a material that exhibits a delayed fluorescence, of the host T ₁ level (T ₁ ^H), S ₁ levels (S ₁ ^H) of the host, and the T ₁ level (T ₁ ^D) of the dopant is to equation 1 and 2, respectively.

&Quot; (1) "

T ₁ ^H ? T ₁ ^D

&Quot; (2) "

S ₁ ^H > T ₁ ^D

According to an aspect of the present invention, there is provided an organic light emitting diode. The organic light emitting diode includes an anode and a cathode. A light emitting layer containing a host and a dopant is disposed between the anode and the cathode. The host is a substance represented by the following formula (1).

[Chemical Formula 1]

In Formula 1,

R ₁ and R ₂ are each independently a C5 to C30 aryl group or a C5 to C30 alkylaryl group and R ₁ and R ₂ are not fused to each other or fused together with the nitrogen to which they are attached to form a saturated or unsaturated ring Lt; / RTI >

n is an integer of 2 or 3,

R ₃ to R ₁₂ are each independently hydrogen, deuterium, a C 1 to C 30 alkyl group, or NR ₁₃ R ₁₄ ,

R ₁₃ and R ₁₄ are each independently an aryl group of C5 to C30, or C5 to an alkylaryl group of C30, R ₁₃ and R ₁₄ are either not fused together or fused to a saturated or unsaturated ring together with the to which they are attached to a nitrogen .

The dopant may be a phosphorescent dopant.

According to the embodiments of the present invention, the luminous efficiency can be maintained or improved as a part of the triplet exciton of the luminescent dopant is transferred to the singlet of the luminescent host and then transferred to the triplet of the luminescent dopant. In addition, the triplet energy and singlet energy of the host is relatively low and the driving voltage can also be lowered.

1 is a cross-sectional view illustrating an organic light emitting diode according to an exemplary embodiment of the present invention.
Fig. 2 schematically shows the energy levels of the luminescent host and the luminescent dopant in the luminescent layer.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the present invention is not limited to the embodiments described herein but may be embodied in other forms. Like reference numerals designate like elements throughout the specification.

As used herein, unless otherwise defined, the term "alkyl group" means an aliphatic hydrocarbon group. The alkyl group may be a "saturated alkyl group" which does not contain any double or triple bonds. The alkyl group may be an "unsaturated alkyl group" comprising at least one double bond or triple bond. The alkyl group, whether saturated or unsaturated, can be branched, straight chain or cyclic. For example, the C1 to C4 alkyl group may be selected from the group consisting of methyl, ethyl, propyl, iso-propyl, n-butyl, iso-butyl, sec-butyl and t-butyl.

As used herein, the term "aryl group" means a polycyclic aromatic compound composed of a monocyclic aromatic compound or a fused aromatic ring unless otherwise defined, and includes a heteroaryl group.

The term "heteroaryl group ", as used herein, unless otherwise defined, includes at least one heteroatom selected from the group consisting of N, O, S, Se, and P in at least one ring, Means a polycyclic aromatic compound consisting of a phosphorus, monocyclic aromatic compound or fused aromatic rings.

In the present specification, when "Cx to Cy" is described, it is to be interpreted that the number of carbon atoms corresponding to all integers between the number of carbon atoms x and the number of carbon atoms y is also described.

Organic light emitting diode

1 is a cross-sectional view illustrating an organic light emitting diode according to an exemplary embodiment of the present invention.

Referring to FIG. 1, the organic light emitting diode includes an anode 10, a cathode 70, and a light emitting layer 40 disposed between the two electrodes.

When a forward bias is applied to the organic light emitting diode, holes are injected from the anode 10 into the light emitting layer 40, and electrons from the cathode 70 are injected into the light emitting layer 40. Electrons and holes injected into the light emitting layer 40 are combined with each other to form excitons, and light is emitted while the excitons transition to the ground state.

The light emitting layer 40 may include a light emitting host and a light emitting dopant. The luminescent dopant may be a fluorescent or phosphorescent dopant. As an example, the luminescent dopant may be a phosphorescent dopant. The light emitting host material may be a host material capable of exhibiting delayed fluorescence, specifically thermally activated delayed fluorescence (TADF).

Fig. 2 schematically shows the energy levels of the luminescent host and the luminescent dopant in the luminescent layer.

1 and 2, the T ₁ level (T ₁ ^H ), the S ₁ level (S ₁ ^H ) and the T ₁ level (T ₁ ^D ) of the luminescent host can satisfy the following equations .

&Quot; (1) "

T ₁ ^H ? T ₁ ^D

&Quot; (2) "

S ₁ ^H > T ₁ ^D

&Quot; (3) "

S ₁ ^H - T ₁ ^H ? 0.3 eV

The electrons and holes injected into the light emitting layer 40 are combined at the light emitting host to form excitons, and then the excitons can be transferred to the light emitting dopant and transferred to the ground state. Specifically, an exciton generated in the light emitting host can move to the energy level T ₁ (T ₁ ^D) or S ₁ levels (S ₁ ^D) of the light-emitting dopant (path ①). The excitons at the T ₁ level (T ₁ ^D ) of the luminescent dopant can transfer energy to the S ₀ level while emitting phosphorescence.

On the other hand, as shown in Equation (1), the T ₁ level (T ₁ ^H ) of the light emitting host is equal to or lower than the T ₁ level (T ₁ ^D ) of the phosphorescent dopant. As the T ₁ level (T ₁ ^H ) of the luminescent host is lowered, the S ₁ level (S ₁ ^H ) of the luminescent host can be lowered. As a result, the electrons and holes can easily flow into the luminescent layer 40, Can be lowered. In addition, the exciton at the T ₁ level (T ₁ ^D ) of the luminescent dopant can transfer energy to the T ₁ level (T ₁ ^H ) of the luminescent host (path 2) instead of emitting phosphorescence. Of the light emitting host T ₁ level (T ₁ ^H) and S ₁ levels (S ₁ ^H), that is, a light emitting host when the light emitting host, which may indicate a delayed fluorescence, the emission host T ₁ level that satisfies the formula (3) (T ₁ ^H ) can be transited back to the S ₁ level (S ₁ ^H ) by heat (path ③). Then, the excitons are in the light-emitting dopant in the S ₁ level (S ₁ ^H) of the host T ₁ level (T ₁ ^D) or S ₁ level (S ₁ ^D) energy transfer one (path ①) to the post, T ₁ level ( T ₁ ^D ), energy can be transferred to the S ₀ level while emitting phosphorescence. In other words, the luminous efficiency can be maintained or improved as a part of the triplet exciton of the luminescent dopant is transferred to the singlet state of the luminescent host, and then transferred to the triplet of the luminescent dopant and released as phosphorescent light.

As described above, the emission host is a luminescent host capable of exhibiting delayed fluorescence (Equation 3), and the T ₁ level (T ₁ ^H ) and the S ₁ level (S ₁ ^H ) of the luminescent host and the T ₁ level (T ₁ ^D ) satisfies the above-described expressions (1) and (2), the driving voltage can be reduced while maintaining or improving the luminous efficiency.

The luminescent host satisfying this requirement may be an organic material represented by the following formula (1).

In Formula 1,

R ₁ and R ₂ are each independently a C5 to C30 aryl group or a C5 to C30 alkylaryl group and R ₁ and R ₂ are not fused to each other or fused together with the nitrogen to which they are attached to form a saturated or unsaturated ring Lt; / RTI >

n may be an integer of 2 or 3,

R ₃ to R ₁₂ each independently may be hydrogen, deuterium, a C 1 to C 30 alkyl group, or NR ₁₃ R ₁₄ . R ₁₃ and R ₁₄ are each independently a C5 to the aryl group of the C30, or C5 to may be an alkyl aryl of C30, R ₁₃ and R ₁₄ is a saturated or unsaturated ring together with the nitrogen to which they are attached to, or not fused together or fused Can be formed.

Also, since the organic material has two or more donor units such as NR ₁ R ₂ connected to the benzene ring, and triazine, which is an exocenter unit having excellent structural stability, is connected to the benzene ring, the electron- And a charge transfer complex form is formed in the molecular structure, so that the difference between the singlet energy (S ₁ ) and the triplet energy (T ₁ ), that is, the narrow Δ Est, may be exhibited. Therefore, the organic material can realize delayed fluorescence and improve the quantum efficiency and lifetime of the organic light emitting diode.

In the above formula (1), NR ₁ R ₂ or NR ₁₃ R ₁₄ may be the following functional groups regardless of each other.

In the functional group 1, the functional group 2, or the functional group 3, A ₁ and A ₂ may be hydrogen, deuterium, or a C1 to C4 alkyl group, regardless of each other.

Specific examples of the organic material represented by the formula (1) may be represented by the following formulas (2) and (3).

In the general formula 2 or general formula _{3, R 1a, R 2a,} R 1b, R 2b, R 1c, and R _2c are each independently selected from C5 to the aryl group of the C30, or C5 to may be an alkyl aryl of C30, R _1a And R < _2a > may not be fused or fused to form a saturated or unsaturated ring together with the nitrogen to which they are attached, and R _{< 1b} > and R < _{2b >} are not fused to each other or fused to form a saturated or unsaturated ring And R _1c and R _2c may not fuse with each other or may fuse together with the nitrogen to which they are attached to form a saturated or unsaturated ring,

R ₃ to R ₁₂ may be the same as defined in formula (1).

In the general formula (2) or (3), NR _1a R _2a , NR _1b R _2b , and NR _1c R _2c may each independently be the functional group 1 or the functional group 2.

In the above formulas 1 to 3, R ₉ and R ₁₁ may each independently be the functional group 1 or the functional group 2. In this case, R ₃ to R ₈ , R ₁₀ , and R ₁₂ may be hydrogen.

  The following compounds 1-7 represent organic materials according to one embodiment of the present invention.

In addition, the luminescent dopant that can satisfy the above equations (specifically, Equations 1 and 2) in addition to the light emitting host is FIrpic (iridium (III) bis (4,6- (di- fluorophenyl) -pyridinato-N , C ') picolinate, tris (phenylmethyl-benzimidazolyl) iridium (III), Ir (dbfmi) (mer-tris (Ndibenzofuranyl- -methylimidazole) iridium (III)), Ir (dfppz) 3 (tris (4,6-difluorophenylpyrazolyl) iridium (III)), Ir (dbi) 3 [fac -tris [1- (2,4-dii-sopropyldibenzo [ 2-phenyl-1H-imidazole (III)], fac-Ir (mpim) ₃ [fac-tris ) Or Ir (dmp) ₃ (iridium (III) tris [3- (2,6-dimethylphenyl) -7-methylimidazo [1,2-f] phenanthridine].

Referring again to FIG. 1, a hole conduction layer 20 may be disposed between the anode 10 and the light emitting layer 40. Further, the electron conduction layer 50 may be disposed between the light emitting layer 40 and the cathode 70. [ The hole transport layer 20 may include a hole transport layer 25 for transporting holes and a hole injection layer 23 for facilitating injection of holes. In addition, the electron conduction layer 50 may include an electron transport layer 55 for transporting electrons and an electron injection layer 53 for facilitating injection of electrons. In addition, a first exciton blocking layer (not shown) may be disposed between the light emitting layer 40 and the hole transport layer 25. A second exciton blocking layer (not shown) may be disposed between the light emitting layer 40 and the electron transporting layer 55. Alternatively, however, the present invention is not limited to this, and the electron transport layer 55 may serve as a second exciton blocking layer, or the hole transport layer 25 may serve as a first electron blocking layer.

The anode 10 may be a conductive metal oxide, a metal, a metal alloy, or a carbon material. The conductive metal oxide is indium tin oxide (indium tin oxide: ITO), fluorine tin oxide (fluorine tin oxide: FTO), antimony tin oxide (antimony tin oxide, ATO), fluorine-doped tin oxide (FTO), SnO _2, ZnO , Or a combination thereof. The metal or metal alloy suitable as the anode 10 may be Au and CuI. The carbon material may be graphite, graphene, or carbon nanotubes.

The hole injection layer 23 and / or the hole transport layer 25 are layers having a HOMO level between the work function level of the anode 10 and the HOMO level of the light emitting layer 40, The hole injection or transport efficiency of the hole is enhanced. The electron injection layer 53 and / or the electron transport layer 55 are layers having a LUMO level between the work function level of the cathode 70 and the LUMO level of the light emitting layer 40, ) In order to increase the injection or transport efficiency of electrons.

The hole injecting layer 23 or the hole transporting layer 25 may include a material commonly used as a hole transporting material and one layer may have a different hole transporting material layer. The hole-transporting material may be, for example, mCP (N, N-dicarbazolyl-3,5-benzene); PEDOT: PSS (poly (3,4-ethylenedioxythiophene): polystyrenesulfonate); NPD (N, N'-di (1-naphthyl) -N, N'-diphenylbenzidine); N, N'-diphenyl-N, N'-di (3-methylphenyl) -4,4'-diaminobiphenyl (TPD); N, N'-diphenyl-N, N'-dinaphthyl-4,4'-diaminobiphenyl; N, N, N'N'-tetra-p-tolyl-4,4'-diaminobiphenyl; N, N, N'N'-tetraphenyl-4,4'-diaminobiphenyl; Porphyrin compound derivatives such as copper (II) 1,10,15,20-tetraphenyl-21H, 23H-porphyrin and the like; TAPC (1,1-Bis [4- [N, N'-Di (p-tolyl) Amino] Phenyl] cyclohexane; Triarylamine derivatives such as N, N, N-tri (p-tolyl) amine and 4,4 ', 4'-tris [N- (3-methylphenyl) -N-phenylamino] triphenylamine; Carbazole derivatives such as N-phenylcarbazole and polyvinylcarbazole; Phthalocyanine derivatives such as nonmetal phthalocyanine and copper phthalocyanine; Starburst amine derivatives; Enamnstilbene derivatives; Derivatives of aromatic tertiary amines and styryl amine compounds; And polysilane. The hole transporting material may serve as a first exciton blocking layer.

The second exciton blocking layer serves to prevent the triplet excitons or holes from diffusing toward the cathode 70, and may be selected arbitrarily from known hole blocking materials. For example, oxadiazole derivatives, triazole derivatives, phenanthroline derivatives, and the like can be used.

The electron transporting layer 55 may be formed of at least one selected from the group consisting of diphenylphosphine oxide-4- (triphenylsilyl) phenyl, TPBi (1,3,5-tris (N-phenylbenzimidazol- ), Aluminum (Alq3), 2,5-diarylsilole derivative (PyPySPyPy), perfluorinated compound (PF-6P), COTs (Octasubstituted cyclooctatetraene), TAZ (4,7-diphenyl-1,10-phenanthroline), BCP (see the following chemical formula), or Balq (see the following chemical formula).

The electron injection layer 53 may be, for example, LiF, NaCl, CsF, Li2O, BaO, BaF2, or Liq (lithium quinolate).

The cathode 70 is a conductive film having a lower work function than the anode 70 and is made of a metal such as aluminum, magnesium, calcium, sodium, potassium, indium, yttrium, lithium, May be formed using a combination of two or more of them.

The anode 10 and the cathode 70 may be formed using a sputtering method, a vapor deposition method, or an ion beam deposition method. The hole injecting layer 23, the hole transporting layer 25, the light emitting layer 40, the hole blocking layer, the electron transporting layer 55 and the electron injecting layer 53 are formed by a vapor deposition method or a coating method, , Spin coating, dipping, printing, doctor blading, or electrophoresis.

The organic light emitting diode may be disposed on a substrate (not shown), which may be disposed under the anode 10 or above the cathode 70. In other words, the anode 10 may be formed on the substrate before the cathode 70, or the cathode 70 may be formed before the anode 10.

The substrate may be a light-transmissive substrate as a flat plate member, in which case the substrate may be glass; Ceramics material; And may be made of a polymer material such as polycarbonate (PC), polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyimide (PI), polypropylene (PP) However, the present invention is not limited to this, and the substrate may be a metal substrate capable of light reflection.

Hereinafter, exemplary embodiments of the present invention will be described in order to facilitate understanding of the present invention. It should be understood, however, that the following examples are intended to aid in the understanding of the present invention and are not intended to limit the scope of the present invention.

[Experimental Examples; Examples]

Intermediate Synthesis Example 1: Intermediate 1

[Reaction Scheme 1]

(10.65 g, 39.80 mmol), (3,4,5-trifluorophenyl) boronic acid (7.00 g, 39.80 mmol) was added to a solution of 2- Dissolved in 210 ml of tetrahydrofuran and dissolved by stirring in a nitrogen stream. Potassium carbonate (16.50 g, 119.39 mmol) was dissolved in distilled water (70 ml) and added to the above reaction solution. Tetrakis (triphenylphosphine) palladium (0) (2.30 g, 2.00 mmol) was added thereto, and the mixture was heated to reflux and stirred. After 12 hours, the temperature of the reactant was lowered to room temperature and the precipitate was filtered. The filtered solid was washed with EA (ethylacetate) to give 12.50 g of pure white solid intermediate 1 in 86% yield.

Intermediate Synthesis Example 2: Intermediate 2

[Reaction Scheme 2]

9 H -carbazole (0.22 g, 1.32 mmol) was dissolved in 10 ml of tetrahydrofuran and slowly added to a flask under a stream of nitrogen containing sodium hydride (0.05 g, 2.20 mmol). After stirring for 30 minutes, Intermediate 1 (0.40 g, 1.10 mmol) was dissolved in 10 ml of tetrahydrofuran and added to the above flask. The temperature of the reaction mixture was raised, and the mixture was refluxed for 2 hours. After completion of the reaction, the reaction mixture was distilled under reduced pressure to remove the solvent. The resulting solid material was washed with distilled water and then backwashed with EA. Finally, recrystallization on toluene afforded 0.35 g of pure white solid intermediate 2 in 62% yield.

Intermediate Synthesis Example 3: Intermediate 3

[Reaction Scheme 3]

3,6-dimethyl -9 H - a carbazole (1.61 g, 8.26 mmol) was slowly added to sodium hydride (0.40 g, 16.51 mmol) the flask under a nitrogen gas stream containing dissolved in 50 ml of tetrahydrofuran. After stirring for 30 minutes, Intermediate 1 (3.00 g, 8.26 mmol) was dissolved in 30 ml of tetrahydrofuran and introduced into the above flask. The temperature of the reaction mixture was raised, and the mixture was refluxed for 2 hours. After completion of the reaction, the reaction mixture was distilled under reduced pressure to remove the solvent. The resulting solid material was washed with distilled water and then backwashed with EA. Finally, recrystallization on toluene afforded 3.60 g of pure, light yellow solid intermediate 3 in 81% yield.

Compound Synthesis Example 1: Compound 1

[Reaction Scheme 4]

9 H -carbazole (0.55 g, 3.30 mmol) was dissolved in 10 ml of dimethylformamide and slowly added to a flask under a stream of nitrogen containing sodium hydride (0.09 g, 3.72 mmol). After stirring for 30 minutes, Intermediate 1 (0.30 g, 0.83 mmol) was dissolved in 10 ml of dimethylformamide and introduced into the above flask. The temperature of the reaction mixture was raised, and the mixture was refluxed for 2 hours. After completion of the reaction, the reaction mixture was distilled under reduced pressure to remove the solvent. The resulting solid material was washed with distilled water and then backwashed with EA. Subsequently, sublimation purification was carried out to obtain 0.48 g of a pure greenish yellow solid compound 1 in 72% yield.

Compound 1 : Mass spectrometry (FAB) m / z 804 [(M + H) <^+> ]. ^{1 H NMR (400 MHz, DMSO} ): δ6.68 (t, 2H, J = 8.2Hz), 6.78 (t, 2H, J = 7.0Hz), 7.05 ~ 7.08 (m, 8H), 7.25 (d, 2H J = 8.4 Hz), 7.43-7.49 (m, 6H), 7.56 (t, 4H, J = 7.8Hz), 7.65 (d, 4H, J = 8.8 Hz), 9.18 (s, 2H)

Compound Synthesis Example 2: Compound 2

[Reaction Scheme 5]

3,6-dimethyl -9 H - carbazole (0.71 g, 3.63 mmol) was slowly added to sodium hydride (0.13 g, 5.50 mmol) the flask under a nitrogen gas stream containing dissolved in 10 ml of dimethylformamide. After stirring for 30 minutes, Intermediate 1 (0.40 g, 1.10 mmol) was dissolved in 10 ml of dimethylformamide and introduced into the above flask. The temperature of the reaction mixture was raised, and the mixture was refluxed for 2 hours. After completion of the reaction, the reaction mixture was distilled under reduced pressure to remove the solvent. The resulting solid material was washed with distilled water and then backwashed with EA. Subsequently, sublimation purification was carried out to obtain 0.83 g of a pure yellow solid compound 2 in a yield of 85%.

Compound 2 : Mass Spec (FAB) m / z 888 [(M + H) &lt; ⁺ & gt ^; ]. ^{1 H NMR (400 MHz, CDCl} 3): δ 2.18 (s, 6H), 2.38 (s, 12H), 6.48 (d, 2H, J = 9.6Hz), 6.85 (t, 6H, J = 6.6Hz), 2H, J = 8.8 Hz), 9.12 (s, 2H), 7.12 (d, 6H, J = 8.4 Hz), 7.49-7.59

Compound Synthesis Example 3: Compound 3

[Reaction Scheme 6]

9,9-Dimethyl-9,10-dihydroacridine (0.89 g, 4.24 mmol) was dissolved in 15 ml of dimethylformamide and slowly added to a flask under a stream of nitrogen containing sodium hydride (0.16 g, 6.74 mmol) Respectively. After stirring for 30 minutes, intermediate 2 (0.70 g, 1.93 mmol) was dissolved in 15 ml of dimethylformamide and introduced into the above flask. The temperature of the reaction mixture was raised, and the mixture was refluxed for 8 hours. After completion of the reaction, the reaction mixture was distilled under reduced pressure to remove the solvent. The resulting solid material was washed with distilled water and then backwashed with EA. Finally, sublimation purification was carried out to obtain 0.28 g of a pure yellow solid compound 3 in a yield of 16%.

Compound 3 : Mass spectrometry (FAB) m / z 888 [(M + H) &lt; ⁺ & gt ^; ]. ^{1 H NMR (400 MHz, CDCl} 3): δ-0.16 (s, 6H), 1.60 (s, 6H), 6.64 (t, 2H, J = 7.2Hz), 6.71 (d, 2H, J = 7.6Hz) , 6.77 (d, 4H, J = 9.2 Hz), 7.04 (t, 4H, J = 8.6 Hz), 7.17 (d, 4H, J = 9.2 Hz), 7.52-7.61 (m, 8H)

Synthesis Example 4: Intermediate 4 (9,9 '- (5-bromo-1,3-phenylene) bis (9H-carbazole)

10 g of 1,3,5-tribromobenzene, 11.95 g of 9H-carbazole, 9.87 g of potassium carbonate and 1.29 g of 1,10-petatroline were dissolved in 120 ml of dimethylformamide, and then cooper ion And the mixture was refluxed at a temperature of 180 ° C or more for 12 hours. After the temperature was lowered to room temperature, distilled water was poured to terminate the reaction, and the reaction was terminated. The reaction mixture was extracted with methylene chloride, and the solvent was dried and purified by column chromatography (MC: HEX). As a result, Intermediate 4 (9,9 '- (5-bromo-1,3-phenylene) bis (9H-carbazole)) was obtained (6 g).

Intermediate 5 Synthesis of Intermediate 5 (9,9 '- (5- (4,4,5,5-tetramethyl-1,3,2-dioxaballolan-2-yl) Bis (9H-carbazole)

(Intermediate 3), 1.89 g of bispinacolatodiaboron, 1.69 g of potassium acetate, 1.9 g of 1,1'- (5-bromo-1,3-phenylene) 0.14 g of bis [(diphenylphosphino) ferrocene] dichloropalladium (II) was dried in vacuum and dissolved in 60 ml of 1,4-dioxane. The mixture was maintained under a nitrogen atmosphere for 30 minutes, Respectively. After the temperature was lowered to room temperature, distilled water was poured to terminate the reaction, and the reaction was terminated. The reaction mixture was extracted with methylene chloride, and the solvent was dried and purified by column chromatography (MC: HEX). As a result, a solution of Intermediate 5 (9,9 '- (5- (4,4,5,5-tetramethyl-1,3,2-dioxaballol-2-yl) Carbazole)) (2.3 g was obtained).

Compound Synthesis Example 4: Compound 4 (9,9 '- (5- (4,6-diphenyl-1,3,5-triazine-2-yl) Sol))

[Reaction Scheme 7]

9,9 '- (5- (4,4,5,5-tetramethyl-1,3,2-dioxaballol-2-yl) -1,3-phenylene) bis (9H- carbazole) 1.55 0.6 g of 2-chloro-4,6-diphenyl-1,3,5-triazine, 0.16 g of tetrakis (triphenylphosphine) palladium (0), 10 ml of a 2 mol potassium carbonate aqueous solution, 20 ml of tetrahydrofuran was refluxed at a temperature of 100 DEG C or higher for 2 hours. After the temperature was lowered to room temperature, the reaction was terminated. The extracted powder was filtered, washed with water, methylene chloride, and hexane, and purified. Finally, sublimation purification was performed to obtain 1.3 g of a greenish compound 4 in 91% yield.

Compound 4 : mass spectrometry (FAB) m / z 639 [(M + H) &lt; ⁺ & gt ^; ]. ^{1 H NMR (400 MHz, CDCl} 3): δ9.11 (s, 2H), 8.74 (d, 4H, J = 8.4Hz), 8.21 (d, 4H, J = 8.0Hz), 8.05 (s, 1H) , 7.64-7.47 (m, 14H), 7.36 (t, 4H, J = 16.0 Hz).

Compound Synthesis Example 5: Compound 5 (9,9 '- (5- (4,6-diphenyl-1,3,5-triazine-2-yl) Sol))

[Reaction Scheme 8]

9,9 '- (5- (4,4,5,5-tetramethyl-1,3,2-dioxaballol-2-yl) -1,3- phenylene) bis (9H- carbazole) 1.63 0.3 g of 2,4-dichloro-6-phenyl-1,3,5-triazine, 0.09 g of tetrakis (triphenylphosphine) palladium (0), 10 ml of a 2 mol potassium carbonate aqueous solution, 30 ml of tetrahydrofuran was refluxed at a temperature of 100 DEG C or higher for 2 hours. After the temperature was lowered to room temperature, the reaction was terminated. The extracted powder was filtered, washed with water, methylene chloride, and hexane, and purified. Finally, sublimation purification was performed to obtain 1.1 g of 85% of compound 5 in white light.

Compound 5 : mass spectrometry (FAB) m / z 971 [(M + H) <^+> ]. ^{1 H NMR (400 MHz, CDCl} 3): δ9.04 (s, 4H), 8.69 (d, 2H, J = 7.6Hz), 8.16 (d, 7H, J = 7.2Hz), 8.05 (m, 2H) , 7.59 (d, 9H, J = 7.6Hz), 7.52-7.48 (m, 2H), 7.37-7.28 (m, 17H).

Compound Synthesis Example 6: Compound 6

[Reaction Scheme 9]

9 H -carbazole (0.58 g, 3.44 mmol) was dissolved in 10 ml of dimethylformamide and slowly added to a flask under a stream of nitrogen containing sodium hydride (0.10 g, 4.13 mmol). After stirring for 30 minutes, Intermediate 3 (0.50 g, 1.38 mmol) was dissolved in 10 ml of dimethylformamide and added to the above flask. The temperature of the reaction mixture was raised, and the mixture was refluxed for 2 hours. After completion of the reaction, the reaction mixture was distilled under reduced pressure to remove the solvent. The resulting solid material was washed with distilled water and then backwashed with EA. Subsequently, sublimation purification was carried out to obtain 0.67 g of a pure greenish solid compound 6 in a yield of 58%.

Compound 6 : Mass Spec (FAB) m / z 832 [(M + H) <^+> ]. ^{1 H NMR (400 MHz, CDCl} 3): δ2.16 (s, 6H), 6.43 (d, 2H, J = 8.4Hz), 6.83 (d, 2H, J = 8.4Hz), 7.04 ~ 7.11 (m, (M, 4H), 7.51 (t, 4H, J = 8.0 Hz), 7.59 (t, 2H, J = 8.0 Hz), 7.82-7.84 J = 8.8 Hz), 9.25 (s, 2H)

Compound Synthesis Example 7: Compound 7

[Reaction Scheme 10]

Diphenylamine (0.93 g, 5.50 mmol) was dissolved in 15 ml of dimethylformamide and slowly added to a flask under a stream of nitrogen containing sodium hydride (0.21 g, 8.61 mmol). After stirring for 30 minutes, Intermediate 2 (0.50 g, 1.38 mmol) was dissolved in 15 ml of dimethylformamide and introduced into the above flask. The temperature of the reaction mixture was raised, and the mixture was refluxed for 8 hours. After completion of the reaction, the reaction mixture was distilled under reduced pressure to remove the solvent. The resulting solid material was washed with distilled water and then backwashed with EA. Subsequently, sublimation purification was carried out to obtain 0.21 g of a pure yellow solid compound 7 in a yield of 19%.

Compound 7 : Mass Spec (FAB) m / z 808 [(M + H) &lt; ⁺ & gt ^; ]. ^{1 H NMR (400 MHz, CDCl} 3): δ6.63 ~ 6.66 (m, 12H), 6.85 (t, 8H, J = 8.00Hz), 6.95 (t, 2H, J = 7.8Hz), 7.00 ~ 7.54 ( (m, 4H), 7.52 (t, 4H, J = 7.4Hz), 7.57-7.61 (m, 4H), 8.56

Production Example 1: Production of retarded fluorescent organic light emitting diode

(ITO / PEDOT: PSS / TAPC / mCP / Compound 4: FIrpic / TSPO1 / TPBI / LiF / Al)

The glass substrate on which the anode, ITO, was deposited was ultrasonically cleaned for 30 minutes using pure water and isopropyl alcohol. The cleaned ITO substrate was surface-treated with ultraviolet rays of short wavelength, and then a hole injection layer was formed by spin coating PEDOT: PSS (poly (3,4-ethylenedioxythiophene): poly (styrenesulfonate)) to a thickness of 60 nm. Thereafter, TAPC (1,1-Bis [4- [N, N'-Di (p-tolyl) Amino] Phenyl] Cyclohexane) was deposited at a pressure of 1 × 10 ^-6 torr at a rate of 0.1 nm / Thereby forming a hole transporting layer. Then, mCP (N, N-dicarbazolyl-3,5-benzene) was deposited at a pressure of 1 × 10 ^-6 torr at a rate of 0.1 nm / s to form a first exciton blocking layer having a thickness of 10 nm. Subsequently, Compound 4 synthesized through Synthesis Example 1 as a host material under a pressure of 1 x 10 ^-6 torr was co-deposited at a rate of 0.1 nm / s and FIrpic as a dopant at a rate of 0.01 nm / s to form a host dopant To form a 10% doped luminescent layer. TSPO1 (diphenylphosphine oxide-4- (triphenylsilyl) phenyl) and TPBi (1,3,5-tris (N-phenylbenzimidazol-2-yl) benzene) at a pressure of 1 × 10 ^-6 torr at a rate of 0.1 nm / s To form a second exciton blocking layer and an electron transporting layer of 5 nm and 30 nm, respectively. Thereafter, LiF as an electron injecting material was vapor-deposited at a pressure of ¹ x 10 ^-6 torr at a rate of 0.01 nm / s to form an electron injecting layer of 1 nm. Thereafter, Al was vapor-deposited at a rate of 0.5 nm / sec under a pressure of ¹ x 10 ^-6 torr to form a cathode of 100 nm, thereby forming an organic light-emitting diode. After the device was formed, the device was sealed using a CaO wetting agent and a glass cover glass.

The organic light emitting diode manufactured through Production Example 1 exhibited a quantum efficiency of 16.4% at a driving voltage of 6.5 V (@ 1,000 cd / m ² ), showing excellent efficiency characteristics.

Comparative Example 1: Manufacture of organic light emitting diode

(ITO / PEDOT: PSS / TAPC / mCP / Compound A: FIrpic / TSPO1 / TPBI / LiF / Al)

An organic light emitting diode was prepared and sealed in the same manner as in Production Example 1, except that Compound A, which does not exhibit retardation fluorescence properties, was used instead of Compound 4 as a host material in the light emitting layer.

The organic light emitting diode manufactured through the comparative example exhibited a quantum efficiency of 8% at a driving voltage of 6.7 V (@ 1,000 cd / m ² ).

<Compound A>

The triplet energy (T ₁ ^H ), the singlet energy (S ₁ ^H ), and the efficiency and driving voltage of the organic light emitting diodes according to the above embodiments and comparative examples .

Of the emitting host
S ₁ ^H (eV) Of the emitting host
T ₁ ^H (eV) Of the luminescent dopant (Firpic)
T ₁ ^D (eV) The driving voltage (V)
(1,000 cd / m ² ) Quantum efficiency
(%) Example 1 2.89 2.64 2.65 6.5 16.4 Comparative Example 3.00 2.69 2.65 6.7 8

Referring to Table 1, it can be seen that the organic light emitting diode according to the experimental example of the present invention has lower driving voltage and significantly improved quantum efficiency as compared with the organic light emitting diode according to the comparative example. This may lower the low driving voltage compared to the compound 4 In other words, the host T ₁ level (T ₁ ^H) is T ₁ level (T ₁ ^D) of the dopant used in the present experimental example, and the host T ₁ level ( T ₁ ^H ) and the S ₁ level (S ₁ ^H ) is 0.3 eV or less, the exciton of the dopant can be emitted as phosphorescence again through the host without passing through the host, thereby improving the quantum efficiency .

The triplet energy (T ₁ ^H ) and singlet energy (S ₁ ^H ) of the compounds 1 to 7 according to each of the above-mentioned compound synthesis examples 1 to 7 are summarized in the following table.

Compound 1 Compound 2 Compound 3 Compound 4 Compound 5 Compound 6 Compound 7 S ₁ ^H (eV) 2.72 2.61 2.35 2.89 2.80 2.66 2.58 T ₁ ^H (eV) 2.56 2.49 2.29 2.64 2.53 2.53 2.34 S ₁ ^H- T ₁ ^H (eV) 0.16 0.12 0.06 0.25 0.27 0.13 0.24

Referring to Table 2, compounds 1 to 3 and compounds 5 to 7, as well as the compound 4 used in the organic light emitting diode according to Production Example 1, and the T ₁ level (T ₁ ^H ) are examples of dopants, Firpic it can be seen in the T ₁ level low compared to the (T ^D _1), it may also be the difference between the T ₁ level (T ^H ₁₎ and the level S ₁ (S ₁ ^H) Al satisfies the following 0.3eV. From this, it is predicted that even when the compounds 1 to 3 and the compounds 5 to 7 are used as a host instead of the compound 4, the driving voltage can be reduced and the luminescence efficiency can be improved as in the case of the compound 4.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, This is possible.

Claims (9)

Anode and cathode
And a light emitting layer disposed between the anode and the cathode, the light emitting layer containing a host and a dopant,
The host is a material exhibiting Thermally Activated Delayed Fluorescence (TADF)
Wherein the T ₁ level (T ₁ ^H ) of the host, the S ₁ level (S ₁ ^H ) of the host and the T ₁ level (T ₁ ^D ) of the dopant satisfy the following equations (1) and :
&Quot; (1) &quot;
T ₁ ^H ? T ₁ ^D
&Quot; (2) &quot;
S ₁ ^H > T ₁ ^D. The method according to claim 1,
Wherein the host is a material represented by the following Formula 1:
[Chemical Formula 1]

In Formula 1,
R ₁ and R ₂ are each independently a C5 to C30 aryl group or a C5 to C30 alkylaryl group and R ₁ and R ₂ are not fused to each other or fused together with the nitrogen to which they are attached to form a saturated or unsaturated ring Lt; / RTI &gt;
n is an integer of 2 or 3,
R ₃ to R ₁₂ are each independently hydrogen, deuterium, a C 1 to C 30 alkyl group, or NR ₁₃ R ₁₄ ,
R ₁₃ and R ₁₄ are each independently an aryl group of C5 to C30, or C5 to an alkylaryl group of C30, R ₁₃ and R ₁₄ are either not fused together or fused to a saturated or unsaturated ring together with the to which they are attached to a nitrogen . The method according to claim 1,
NR &lt; ₁ &gt; R &lt; ₂ &gt; and NR &lt; ₁₃ &gt; R &lt; ₁₄ &gt;

In the functional group 1, the functional group 2, or the functional group 3, A ₁ and A ₂ are each independently hydrogen, deuterium, or a C1 to C4 alkyl group. The method of claim 2,
Wherein the material represented by Formula 1 is a material represented by Formula 2:
(2)

In Formula 2, R _1a , R _2a , R _1b , and R _2b are each independently a C5 to C30 aryl group or a C5 to C30 alkylaryl group; R _1a and R _2a are not fused to each other or fused together with the nitrogen to which they are attached to form a saturated or unsaturated ring; R _1b and R _2b are not fused to each other or fused together with the nitrogen to which they are attached to form a saturated or unsaturated ring,
R ₃ to R ₁₂ are the same as defined in formula (1). The method of claim 4,
Wherein the material represented by Formula 2 is the following Compound 4 or 5:

. The method of claim 2,
Wherein the material represented by Formula 1 is a material represented by Formula 3:
(3)

Wherein R _1a , R _2a , R _1b , R _2b , R _1c and R _2c are each independently a C5 to C30 aryl group or a C5 to C30 alkylaryl group; R _1a and R _2a are not fused to each other or fused together with the nitrogen to which they are attached to form a saturated or unsaturated ring; R _1b and R _2b are not fused to each other or fused together with the nitrogen to which they are attached to form a saturated or unsaturated ring; R _1c and R _2c are not fused to each other or fused together with the nitrogen to which they are attached to form a saturated or unsaturated ring,
R ₃ to R ₁₂ are the same as defined in formula (1). The method of claim 6,
Wherein the material represented by Formula 3 is an organic light emitting diode having the following Formula 1, 2, 3, 6, or 7:

. delete In claim 1,
Wherein the dopant is a phosphorescent dopant.

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