KR20060120984A - Phosphorescent host materials with aluminium complex containing 9-phenanthrol and organic electroluminescent device using this material - Google Patents

Abstract

Provided is a phosphorescent host material, which comprises a phosphorescent host material having suitable hole transportability and hole blocking capability to minimize a triplet-triplet quenching phenomenon, and imparts high luminance, improved lifespan and stability and low drive voltage to an organic light emitting device. The phosphorescent host material is an aluminum complex containing a phenanthrol represented by the following formula 1 as a ligand. In the formula 1, each of R1 and R2 is independently selected from the group consisting of H, halogen atoms, substituted or non-substituted C1-C18 alkyl groups, substituted or non-substituted C1-C18 alkoxy groups, aromatic heterocyclic groups and substituted or non-substituted C6-C18 aryl groups. The phosphorescent host material is incorporated into a light emitting layer after being doped with a red phosphorescent material.

Description

Phosphorescent Host Materials with Aluminum Complex Containing 9-Phenanthrol And Organic Electroluminescent Device using this material}

1 and 2 are schematic cross-sectional views of a phosphorescent light emitting device according to an embodiment of the present invention.

3 is a graph showing the voltage-luminance characteristics of the phosphorescent light emitting device according to the embodiment of the present invention.

4 is a graph showing the voltage-efficiency characteristics of the phosphorescent light emitting device according to the embodiment of the present invention.

<Description of Signs of Major Parts of Drawings>

11, 21: transparent electrode (anode) 12, 22: hole injection layer

13, 23: hole transport layer 14, 24: light emitting layer

15, 25: electron transport layer 16, 26: electron injection layer

17, 27: metal electrode (cathode) 28, 38: hole blocking layer

The present invention relates to a phosphorescent host material comprising phenanthrol and an organic electroluminescent device using the same, and more particularly, using an aluminum complex containing a phenanthrol ligand as a phosphorescent host material, wherein the aluminum complex is used alone or in red phosphorescence. When the light emitting layer is formed by doping a material and then applied to the organic electroluminescent device, the organic electroluminescent device can be provided with long life, high efficiency and high brightness, low voltage driving and improved stability of the device.

Recently, the flat panel display device plays a very important role as a device supporting a highly visual information society based on the Internet, which is rapidly growing.

In particular, an organic electroluminescent device (organic EL device) capable of low voltage driving with a self-emission type has an excellent viewing angle and contrast ratio compared to a liquid crystal display (LCD), which is a mainstream of flat panel display devices. It is light and thin because no backlight is required, and it is advantageous in terms of power consumption. In addition, the fast response speed and wide color reproduction range have attracted attention as a next generation display device.

In general, an organic EL device is formed on a glass substrate in order of an anode made of a transparent electrode, an organic thin film including a light emitting region, and a metal electrode. In this case, the organic thin film may include a hole injection layer (HIL), a hole transport layer (HTL), an electron transport layer (ETL), or an electron injection layer (EML) in addition to the light emitting layer (EML). Electron Injection Layer (EIL), and may include an electron blocking layer (EBL) or a hole blocking layer (HBL) due to the light emission characteristics of the light emitting layer.

When an electric field is applied to the organic EL device having such a structure, holes are injected from the anode, electrons are injected from the cathode, and holes and electrons are recombined in the light emitting layer through the hole transport layer and the electron transport layer, respectively, thereby emitting excitons. ). The formed light exciton emits light as it transitions to ground states. At this time, the excitons are formed in the opposite direction of the spin direction, that is, the singlet state and the spin direction of the same direction, that is, the triplet state is generated at a ratio of 25% and 75%, respectively.

Among the above-mentioned exciton states, the use of a singlet state for luminescence is called fluorescence, and the use of a triplet state generated at a 75% ratio for luminescence is called phosphescence. In some cases, the singlet excited excitons can be transferred to the triplet state by spin-orbit coupling (intersystem crossing), so that the phosphorescent material is theoretically used for organic electroluminescent devices. All 100% excitons can be used for light emission, making it possible to manufacture devices with high efficiency.

Recently, research has been actively conducted to apply not only fluorescent light emitting materials but also phosphorescent light emitting materials to light emitting layers of organic EL devices (DF O'Brien and MA Baldo et al. "Improved energy transfer in electrophosphorescent devices" Applied Physics Letter Vol 74 No. 3, pp 442-444, Jan. 18, 1999; MA Baldo et al. "Very high-efficiency green organic light-emitting devices based on electrophosphorescence" Applied Physics letters Vol. 75 No. 1, pp 4- 6, Jul. 5, 1999).

However, in such phosphorescence emission, since the triplet excitons cannot directly transition to the ground state (spin forbidden), the process of transition to the ground state after the flipping of the electron spin proceeds, so that the phosphorescence is longer than the fluorescence Has a characteristic of long life.

That is, the emission duration corresponds to several nanoseconds in the case of fluorescent emission, and the phosphorescence emission corresponds to several micro seconds in a relatively long time. The long duration of light emission causes various problems when phosphorescence is applied to an organic light emitting device. A representative problem is triplet-triplet annihilation, which is a triplet state. Reacts with each other, meaning that it is extinguished and is represented by Equation 1 below.

In Equation 1, J is an efficiency half current density, q is the electron charge, d is a recombination area, τ is a life time, and kq is a triplet. Triplet-Triplet Annihilation Rate Const.

According to Equation 1, in order to minimize the triplet-triple extinction phenomenon, it is necessary to maximize the recombination area, that is, the light emitting area, and minimize the lifetime of the light emitter. Through this, the current density at which the efficiency is halved can be increased.

Therefore, the phosphorescent light emitting host uses a material having a relatively large emission area, that is, a material having a large hole-diffusion phenomenon, and thus, it is possible to use a host material that can minimize the triplet-triplet disappearance by increasing the emission area. Typical and representative substance is CBP (4,4-N, N'-dicarbazolebiphenyl). However, since these materials have a large hole flow phenomenon, in order to maximize efficiency, a hole blocking layer is additionally inserted into the device structure, thereby shortening the life of the device.

In the case of an electrophosphorescent device, in order to obtain high luminous efficiency, the selection of a phosphorescent host material has a direct effect.

Since the phosphor emits from the triplet, the triplet energy of the host must be greater than the triplet energy of the phosphor in order for the triplet energy transfer from the host to the guest phosphor to occur effectively.

In general, triplet energy is about 1 eV lower than singlet energy, so the highest occupied molecular orbital (HOMO) -lowest unoccupied molecular orbital (LUMO) gap is larger than the fluorescent material. It is preferably used as a host material. When the triplet of the host is lower than the triplet energy of the phosphorescent dye, endothermic energy transfer should be used. In this case, the external luminous efficiency is relatively low while the triplet of the host is higher than the triplet energy of the phosphor. The exothermic energy transfer results in high quantum efficiency.

In order to realize such a high-efficiency, full-color organic EL device, it is required to introduce a new electron injection (transport) and hole injection (transport) layer or to develop a new material having excellent luminous efficiency.

Accordingly, the inventors of the present invention have made an effort to solve the above problems, and as a result, an organic compound layer formed by using an aluminum complex containing a phenanthrol ligand as a host material and doped with a red phosphorescent material is provided as a light emitting layer of an organic EL device. In this case, the host material has an appropriate hole flow phenomenon and a hole blocking ability, thereby minimizing triplet-triple terminology phenomena, and it is possible to manufacture high-efficiency phosphorescent EL devices without introducing a hole blocking layer. Knowing to complete the present invention.

Accordingly, the present invention provides a red phosphorescent host material including a phenanthrol that can provide an organic electroluminescent device that exhibits characteristics such as long life, high efficiency and high brightness when applied to the light emitting layer of an organic EL device, and has improved low voltage driving and stability. It is an object to provide an organic electroluminescent device using the same.

The present invention is characterized by a phosphorescent host material which is an aluminum complex containing a phenanthrol ligand represented by the following formula (1).

[Formula 1]

In Formula 1, R ₁ and R ₂ are a hydrogen atom, a halogen atom, a substituted or unsubstituted C _1-18 alkyl group, a substituted or unsubstituted C _1-18 alkoxy group, an aromatic heterocyclic group and a substituted or unsubstituted It is selected from cyclic C _6-18 aryl group.

The present invention also includes an organic EL device comprising the aluminum complex as a phosphorescent host material.

Hereinafter, the present invention will be described in detail.

The present invention exhibits long life, high efficiency and high brightness by using an aluminum complex containing a phenanthrol ligand as a phosphorescent host material and forming a light emitting layer doped with a red phosphor, and applying the same to an organic electroluminescent device. And it is proposed to provide an organic EL device with improved stability of the device.

The phosphorescent host material of the present invention is an aluminum complex represented by Formula 1, wherein R ₁ and R ₂ are hydrogen atoms, halogen atoms, substituted or unsubstituted C _1-18 alkyl groups, substituted or unsubstituted C _1-18 And an alkoxy group, an aromatic heterocyclic group and a substituted or unsubstituted C _6-18 aryl group may be used. Preferably, R ₁ and R ₂ are a hydrogen atom, phenyl, 4-alkyllay. In the case of a compound selected from tide phenyl, 1-naphthyl, 2-naphthyl, anthracenyl and the like, more preferably, it is preferably selected from the compounds represented by the following formulas 1a to 1d.

[Formula 1a]

[Formula 1b]

[Formula 1c]

[Formula 1d]

Compounds 1a to 1d are introduced by introducing two 8-hydroxyquinolidine main ligands and one 9-phenanthrol derivative as an auxiliary ligand to an aluminum central metal ion. It was produced and can be simply represented by the following scheme 1.

Under a nitrogen atmosphere, triethylaluminum (Formula 3) is added to a toluene solution. The 9-phenanthrol (Formula 2) derivative is dissolved in toluene, and then slowly added to the reaction vessel and stirred for 1 hour. Hydroxyquinalidine (Formula 4) was dissolved in toluene and slowly added dropwise, stirred for 3 hours and then filtered. The filtered solid can be recrystallized in methylene chloride to obtain the final compound (Formula 1) [(1) Guang Wang, Fushun Liang, Zhiyuan Xie, Guangping Su, Lixiang Wang, Xiabin Jing, Fosong Wang, Synthetic Metal. 131 (2002) 1-5; (2) Y. Qiu, Y. Shao, D.Q. Zhang, X.Y. Hong, Jpn. J. Appl. Phys. 39 (2002) 1151.

In addition, the present invention provides an organic EL device comprising the phosphorescent host material, the phosphorescent host material may be included in the light emitting layer.

That is, a structure having a single layer or an organic thin film (light emitting layer) including the aluminum complex as a light emitting material between the anode, the cathode, and the two electrodes as a single layer or a multilayer with the charge transport layer. The organic EL device can be manufactured.

In general, a stacked device in which a light emitting layer and a charge transport layer are combined is superior to a single layer device having only a light emitting layer. This is because an appropriate combination of the light emitting material and the charge transport material reduces the energy barrier when charge is injected from the electrode, and the charge transport layer binds the holes or electrons injected from the electrode to the light emitting layer region to balance the number of holes and electrons injected. This is because it helps to achieve.

A schematic cross-sectional view of an organic EL device according to an embodiment of the present invention is shown in Figs.

The organic EL device shown in FIG. 1 includes transparent electrodes (anodes) 11 and 21, hole injection layers 12 and 22, hole transport layers 13 and 23, light emitting layers 14 and 24, and electron transport layers 15 and 25. ), The electron injection layers 16 and 26 and the metal electrodes (cathodes) 17 and 27 are sequentially stacked.

The organic EL device illustrated in FIG. 2 includes transparent electrodes (anodes) 11 and 21, hole injection layers 12 and 22, hole transport layers 13 and 23, light emitting layers 14 and 24, and hole blocking layers 28. The electron transport layers 15 and 25, the electron injection layers 16 and 26, and the metal electrodes (cathodes) 17 and 27 are sequentially stacked.

The transparent electrodes (anodes) 11 and 21 and the metal electrodes (cathodes) 17 and 27 are conventional electrode materials, for example, the transparent electrodes are made of indium tin oxide (ITO) or SnO ₂ , and the metal electrodes The metal may be made of a metal such as Li, Mg, Ca, Ag, Al, In, or an alloy thereof, and the metal electrode may have a single layer or a multilayer structure of two or more layers.

The light emitting layers 14 and 24 may be composed of a single layer or a multilayer of two or more layers including the compound of Formula 1 of the present invention, preferably, the compounds of Formulas 1a to 1d as phosphorescent host materials, and other phosphorescent host materials. Specifically, for example, CBP, which is a representative phosphorescent host material represented by the following Chemical Formula 5, may be configured by stacking a single layer or a multilayer of two or more layers.

[Formula 5]

The compound of formula 1 of the present invention, preferably the compounds of formulas 1a to 1d, may be used alone in the light emitting layer, and in particular may be used in combination with a red phosphorescent dopant. As a compound proposed by the applicant as a dopant, for example, it may be used in combination with a red phosphorescent dopant (Korean Patent Application No. 10-2004-91680) represented by the following formula (6).

[Formula 6]

The hole transport layers 13 and 23 are conventional hole transport materials, for example, 4,4-bis [N- (1-naphthyl) -N-phenyl-amine] biphenyl (α-NPD) of Formula 7, N, N-diphenyl-N, N-bis (3-methylphenyl) -1,1-biphenyl-4,4-diamine (TPD) and poly- (N-vinylcarbazole) (PVCz) These may be constituted alone or in combination of two or more thereof, or may be two or more layers in which other layers are laminated.

[Formula 7]

[Formula 8]

The hole blocking layers 18 and 28 may have a LUMO value of 5.5 to 7.0, and may be composed of a material having excellent electron transport ability with a marked drop in hole transport capacity. Bathocuproine, BCP), 3- (4-biphenylyl) -4-phenyl-5- (4-t-butylphenyl) -1,2,4-triazole (TAZ) Bis (8-hydroxy-2-methylquinolinato) -aluminum biphenoxide (BAlq) is suitable.

[Formula 9]

[Formula 10]

[Formula 11]

The electron transporting layers (electron transporting emissive layers) 15 and 25 are conventional electron transporting materials, for example, tris (8-quinolinolato) aluminum (Alq3), rubrene, etc. alone or in combination of two or more. It may be configured, and may be two or more layers in which other layers are laminated.

In addition, in order to improve device characteristics such as efficiency and lifespan, a conventional copper phthalocyanine (CuPc) is included between the anodes 11 and 21 and the hole transport layers 13 and 23 as necessary. Hole injection layers 12 and 22 may be inserted, and conventional electron injection layers 16 and 26 including, for example, LiF may be inserted between cathodes 17 and 27 and electron transport layers 15 and 25. can do.

The positive electrode, the negative electrode, and various organic thin films may be formed by conventional deposition methods well known in the art.

The organic EL device using the aluminum complex containing the phenanthrol ligand of the present invention as a phosphorescent host material can be expected to greatly improve the lifespan and efficiency, and to improve low voltage driving and stability of the device.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited by the following Examples.

Example 1:

1) Preparation of Red Phosphorescent Host Material of Formula 1a

The red phosphorescent host material of Chemical Formula 1a was prepared by the following Scheme 2.

Under a nitrogen atmosphere, 1.14 g of triethylaluminum (3) was added to a 20 mL toluene solution in a 100 mL round flask. 1.94 g of 9-phenanthrol (2a) was dissolved in 15 mL of toluene, slowly added to a reaction vessel and stirred for 1 hour, and hydroxyquinalidine (4) in 20 mL of toluene. ) 3.2 g was slowly added dropwise, stirred for 3 hours, and then filtered.

The filtered solid was recrystallized in methylene chloride to obtain the final compound (Formula 1a) [1) Guang Wang, Fushun Liang, Zhiyuan Xie, Guangping Su, Lixiang Wang, Xiabin Jing, Fosong Wang, Synthetic Metal. 131 (2002) 1-5 .; (2) Y. Qiu, Y. Shao, D.Q. Zhang, X.Y. Hong, Jpn. J. Appl. Phys. 39 (2002) 1151, and then, the NMR result of Chemical Formula 1a is shown.

¹ H-NMR (300 MHz, CDCl ₃ ) δ 8.5-8.1 (m, 5H), 7.5-6.9 (m, 13H), 6.1 (s, 1H), 2.8 (s, 6H); ¹³ C-NMR (300 MHz, CDCl ₃ ) δ 160.1, 160, 155.4, 152, 148, 139, 137.6, 135, 133.3, 132.7, 131.5, 128.3, 127, 126.8, 126.3, 125, 124.5, 124.4, 123.9; FAB-MS: Calcd. MW 551.59, m / e = 551.19.

2) Fabrication of organic electroluminescent device using compound of formula 1a as host material

150 nm ITO (indium tin oxide) -coated glass substrate (Asahi Glass Co., Ltd., sheet resistance 8 ° / cm 2) was ultrasonically cleaned sequentially with water-based detergent, ultrapure water, isopropyl alcohol and methanol The transparent electrodes 11 and 21 were produced.

Copper phthalocyanine (CuPc) was deposited on the transparent electrodes 11 and 21 to form the hole injection layers 12 and 22 at 20 nm, and thereafter, 4,4-bis [N− was formed on the hole injection layers 12 and 22. (1-naphthyl) -N-phenyl-amine] biphenyl (α-NPD) was deposited to form 20 nm hole transport layers 13 and 23.

Subsequently, the prepared phosphorescent host material of Formula 1a and the phosphorescent dopant material of Formula 3 were deposited on the hole transport layers 13 and 23 at a rate of 1 nm / sec using a weight ratio of 10: 1 to emit light layer 14 of 30 nm. , 24). After the completion of the co-deposition, tris (8-quinolinolato) aluminum (Alq3) was deposited thereon to form electron transport layers 15 and 25 at 40 nm, and LiF was deposited to form an electron injection layer at 16 nm. , 26).

An organic EL device was fabricated by depositing Al on the electron injection layers 16 and 26 to form a cathode of 150 nm.

The organic EL device manufactured was [ITO transparent electrode (150 nm) / CuPc hole injection layer (20 nm) / α-NPD hole transport layer (40 nm) / light emitting layer (30 nm) / Alq3 consisting of the compound of formula 1a and formula (6). The electron transport layer (40 nm) / LiF electron injection layer (1 nm) / Al electrode (150 nm)] has a structure in which the layers are sequentially stacked from below, and the structural cross section thereof is shown in FIG.

In addition, when the emission layer is formed, the compound of Formula 1a and the compound of Formula 6 are doped at a weight ratio of 10% to form a light emitting layer.

Example 2:

1) Preparation of Red Phosphorescent Host Material of Formula 1b

The red phosphorescent host material of Chemical Formula 1b was prepared by the following Scheme 3.

Under a nitrogen atmosphere, 1.14 g of triethylaluminum (3) was added to a 30 mL toluene solution in a 100 mL round flask. 2.7 g of 2-phenyl-9-phenanthrol (2b) was dissolved in 20 mL of toluene, slowly added to the reaction vessel, and stirred for 1 hour, and hydroxyqui was dissolved in 20 mL of toluene. 3.2 g of nalidine (hydroxyquinalidine, (4)) was dissolved, slowly added dropwise, stirred for 3 hours, and filtered.

The filtered solid was recrystallized from methylene chloride to obtain the final compound (Formula 1b) [1) Guang Wang, Fushun Liang, Zhiyuan Xie, Guangping Su, Lixiang Wang, Xiabin Jing, Fosong Wang, Synthetic Metal. 131 (2002) 1-5 .; (2) Y. Qiu, Y. Shao, D.Q. Zhang, X.Y. Hong, Jpn. J. Appl. Phys. 39 (2002) 1151], and then the NMR result of Chemical Formula 1b is shown.

¹ H-NMR (300 MHz, CDCl ₃ ) δ 8.5-8.1 (m, 5H), 7.8-6.9 (m, 17H), 6.1 (s, 1H), 2.8 (s, 6H); _¹³ C-NMR (300 MHz, CDCl ₃ ) δ 160.1, 155.4, 148, 137.6, 136.6, 134.4, 133.3, 132.7, 132, 129, 129, 128.3, 127.4, 127.2, 126.8, 126.3, 125.2, 124.4, 123.9, 123.4 , 122.9, 122.4, 120.1, 117.3, 113.8, 111.3, 35.2, 14.8; FAB-MS: Calcd. MW 627.69, m / e = 627.22.

2) Fabrication of organic electroluminescent device using compound of formula 1b as host material

Using the compound of Formula 1b as a phosphorescent host, an organic EL device was manufactured in the following structure.

Transparent electrode (ITO) 150 nm / hole injection layer material, CuPc, 20 nm / hole transport material, NPB, 20 nm / light emitting layer, 30 nm / electron transport material, Alq3, 40 nm / electron injection layer material, LiF, 1 nm Cathode electrode, Al, 150 nm.

Example 3:

1) Preparation of a Red Phosphorescent Host Compound of Formula 1c

The red phosphorescent host material of Chemical Formula 1c was prepared by the following Scheme 4.

Under a nitrogen atmosphere, 1.14 g of triethylaluminum (3) was added to a 30 mL toluene solution in a 100 mL round flask. 3.5 g of 2,7-diphenyl-9-phenanthrol (2c) was dissolved in 30 mL of toluene, slowly added to a reaction vessel, and stirred for 1 hour. After dissolving 3.2 g of hydroxyquinalidine (4) in toluene, it was slowly added dropwise, stirred for 3 hours, and filtered.

The filtered solid was recrystallized from methylene chloride to obtain the final compound (Formula 1c) [1) Guang Wang, Fushun Liang, Zhiyuan Xie, Guangping Su, Lixiang Wang, Xiabin Jing, Fosong Wang, Synthetic Metal. 131 (2002) 1-5 .; (2) Y. Qiu, Y. Shao, D.Q. Zhang, X.Y. Hong, Jpn. J. Appl. Phys. 39 (2002) 1151, and then, the NMR result of Chemical Formula 1c is shown.

¹ H-NMR (300 MHz, CDCl ₃ ) δ 8.5-8.1 (m, 6H), 7.7-6.9 (m, 20H), 6.1 (s, 1H), 2.8 (s, 6H); ¹³ C-NMR (300 MHz, CDCl ₃ ) δ 160.1, 155.4, 148, 137.6, 136.6, 134.4, 132.7, 132.2, 132, 129, 127.4, 127.2, 126.8, 125.2, 124.4, 123.9, 123.4, 122.9, 120.1, 117.8 ; FAB-MS: Calcd. MW 703.78, m / e = 703.25

2) Fabrication of organic electroluminescent device using compound of formula 1c as host material

Using the compound of Formula 1c as a phosphorescent host, an organic EL device was manufactured in the following structure.

Transparent electrode (ITO) 150 nm / hole injection layer material, CuPc, 20 nm / hole transport material, NPB, 20 nm / light emitting layer, 30 nm / electron transport material, Alq3, 40 nm / electron injection layer material, LiF, 1 nm Cathode electrode, Al, 150 nm.

Example 4:

1) Preparation of Red Phosphorescent Host Compound of Formula 1d

The red phosphorescent host material of Chemical Formula 1d was prepared by the following Scheme 5.

   Under a nitrogen atmosphere, 1.14 g of triethylaluminum (3) was added to a 30 mL toluene solution in a 100 mL round flask. 3.2 g of 2-naphthyl-9-phenanthrol (2d) was dissolved in 30 mL of toluene, slowly added to the reaction vessel, stirred for 1 hour, and hydroxy-hydroxyl to 20 mL of toluene. 3.2 g of quinalidine (hydroxyquinalidine) was dissolved, slowly added dropwise, and stirred for 3 hours, followed by filtration.

The filtered solid was recrystallized in methylene chloride to obtain the final compound (Formula 1d) [1) Guang Wang, Fushun Liang, Zhiyuan Xie, Guangping Su, Lixiang Wang, Xiabin Jing, Fosong Wang, Synthetic Metal. 131 (2002) 1-5 .; (2) Y. Qiu, Y. Shao, D.Q. Zhang, X.Y. Hong, Jpn. J. Appl. Phys. 39 (2002) 1151], and then the NMR result of Chemical Formula 1d is shown.

¹ H-NMR (300 MHz, CDCl ₃ ) δ 8.5-8.1 (m, 6H), 7.8-6.9 (m, 18H), 6.1 (s, 1H), 2.8 (s, 6H); ¹³ C-NMR (300 MHz, CDCl ₃ ) δ 160.1, 155.4, 148, 137.6, 136.1, 134.4, 134.1, 133.3, 132.7, 132.5, 132, 128.3, 128, 127.2, 126.9, 126.8, 126.4, 126.3, 125.9, 125.2 , 124.8, 124.4, 123.9, 123.4, 122.9, 122.4, 120.1, 117.3, 113.8, 113.3, 35.2, 14.8; FAB-MS: Calcd. MW 677.74, m / e = 677.24

2) Fabrication of organic electroluminescent device using compound of formula 1d as host material

Using the compound of Formula 1d as a phosphorescent host, an organic EL device was manufactured in the following structure.

Transparent electrode (ITO) 150 nm / hole injection layer material, CuPc, 20 nm / hole transport material, NPB, 20 nm / light emitting layer, 30 nm / electron transport material, Alq3, 40 nm / electron injection layer material, LiF, 1 nm / Cathode electrode, Al, 150 nm.

Comparative example

As a comparative example, CBP of Formula 5 and dopant of Formula 6, which are target host materials capable of maximizing efficiency by minimizing triplet-triple extinction phenomena in organic EL devices, are used, and BCP (bathocuproine) as a hole blocking layer material. , To manufacture an EL device with the structure shown in Figure 2 using the formula (9).

Transparent electrode (ITO) 150 nm / hole injection layer material, CuPc, 20 nm / hole transport material, NPB, 20 nm / light emitting layer, 30 nm / (hole blocking layer material, BCP, 10 nm) / electron transport material, Alq3, 40 nm / electron injection layer material, LiF, 1 nm / cathode electrode, Al, 150 nm.

3, 4, and Table 1, the characteristics of the organic EL devices manufactured by Examples 1 to 4 and Comparative Examples are shown as voltage, current, and luminance correlation.

In the devices of Examples 1 to 4 using the host materials of Formulas 1 to 4 of the present invention, an organic EL device having improved voltage-current-luminance characteristics could be obtained than the comparative example using the CBP host. That is, an organic EL device having a reduced driving voltage of 0.3 to 0.6 may be obtained using the host of Formulas 1 to 4 of the present invention than a comparative example using a CBP host at 10,000 cd / m 2 luminance. In addition, it was possible to obtain an organic electroluminescent device having improved luminous efficiency of 0.2 to 1.6 than the comparative example.

Host-Dopant @ 10,000 cd / ㎡ Voltage (V) Efficiency (cd / A) Color coordinates Comparative example CBP + Formula 2 + BCP 13.1 8.8 0.67, 0.32 Example 1 Formula 1a + Formula 2 12.5 10.4 0.67, 0.34 Example 2 Formula 1b + Formula 2 12.7 9.6 0.67, 0.34 Example 3 Formula 1c + Formula 2 12.8 9.0 0.67, 0.34 Example 4 Formula 1d + Formula 2 12.6 9.8 0.67, 0.34

As described above, the host material using the aluminum complex containing the phenanthrol ligand of the present invention can greatly improve the low-voltage driving and efficiency of the device, and fabricate an organic EL device having greatly improved device stability and lifetime.

Claims (6)

A phosphorescent host material comprising an aluminum complex comprising a phenanthrol ligand represented by Formula 1; [Formula 1]

In Formula 1, R ₁ and R ₂ are a hydrogen atom, a halogen atom, a substituted or unsubstituted C _1-18 alkyl group, a substituted or unsubstituted C _1-18 alkoxy group, an aromatic heterocyclic group and a substituted or unsubstituted It is selected from cyclic C _6-18 aryl group. The phosphorescent host of claim 1, wherein in Formula 1, R ₁ and R ₂ are compounds selected from a hydrogen atom, phenyl, 4-alkylated phenyl, 1-naphthyl, 2-naphthyl, and anthracenyl. matter. The phosphorescent host material of claim 1, wherein the aluminum complex is a compound selected from Formulas 1a to 1d. [Formula 1a]

[Formula 1b]

[Formula 1c]

[Formula 1d]

An organic electroluminescent device comprising a phosphorescent host material selected from claims 1 to 3. The organic electroluminescent device according to claim 4, wherein the phosphorescent host material is included in a light emitting layer. The organic electroluminescent device according to claim 5, wherein the phosphorescent host material is doped with a red phosphor and included in the emission layer.

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