WO2015099481A1 - Organic electroluminescent device - Google Patents

Abstract

The present invention provides an organic electroluminescent device comprising: an anode; a cathode; and one or more organic layers which are disposed between the anode and the cathode, and which comprise one or more selected from the group consisting of a hole injection layer, a hole transporting layer, a luminescent layer, an electron transporting layer, and an electron injection layer and further comprise a lifetime enhancement layer between the luminescent layer and the electron transporting layer.

Description

Organic electroluminescent element

The present invention relates to an organic electroluminescent device comprising at least one organic material layer.

In 1965, research on organic electroluminescent (EL) devices led to blue electroluminescence using anthracene single crystals was continued.In 1987, Tang formed a hole layer (NPB) and a light emitting layer (Alq ₃ ). An organic electroluminescent device having a layered structure has been proposed. Afterwards, the organic electroluminescent device generates electroluminescence by combining the organic layer, which is responsible for hole injection and transport, and the organic layer, which is responsible for electron injection and transport, and holes and electrons, in order to realize high efficiency and long life characteristics required for commercialization. Forms of multi-layered laminate structures have been proposed that impart respective distinctive and granular functions, such as inducing organic layers. The introduction of the multilayered laminate structure improves the performance of the organic electroluminescent device to commercialization characteristics, and has expanded its application range from portable radio display products in 1997 to portable information display devices and TV display devices.

The demand for larger displays and higher resolutions has led to problems of high efficiency and long life of organic EL devices. In particular, in the case of high resolution achieved through the formation of more pixels in the same area, the result is a reduction in the emission area of the organic electroluminescent pixels, which inevitably leads to a reduction in the lifetime, and is the most important technology that the organic electroluminescent device must overcome. It became a task.

In the organic electroluminescent device, when current or voltage is applied to two electrodes, holes are injected into the organic material layer at the anode, and electrons are injected into the organic material layer at the cathode. When the injected holes and electrons meet, an exciton is formed, and the exciton falls to the ground and shines. In this case, the organic EL device may be classified into a fluorescent EL device in which singlet excitons contribute to light emission and a phosphorescent EL device in which triplet excitons contribute to light emission, depending on the electron spin type of the formed exciton.

The electron spin of excitons, formed by the recombination of electrons and holes, produces 25% and 75% of singlet excitons and triplet excitons. In the fluorescent electroluminescent device which emits light by singlet excitons, the internal quantum efficiency cannot theoretically exceed 25% according to the production rate, and the external quantum efficiency is accepted as a limit of 5%. Phosphorescent electroluminescent devices that emit light by triplet excitons exhibit luminous efficiency up to four times higher than fluorescence when a metal complex compound containing transition metal heavy atoms such as Ir and Pt is used as the phosphorescent dopant. Can be improved.

As described above, the phosphorescent electroluminescent device exhibits higher efficiency than fluorescence in terms of luminous efficiency on the basis of the theoretical fact. However, in the blue phosphorescent device except green and red, a phosphorescent dopant having a deep blue color purity and a high efficiency is satisfied. Since the development level of the host of the energy gap is insufficient, the blue phosphor is not commercialized yet, and the blue phosphor is used in the product.

In order to improve the characteristics of the organic EL device, research has been reported to increase the stability of the device by preventing the diffusion of holes into the electron transport layer. By using a material such as BCP or BPhen between the light emitting layer and the electron transporting layer, a technique for preventing holes from diffusing into the electron transporting layer and limiting the inside of the light emitting layer to effectively increase the probability of recombination of holes and electrons has been proposed. However, derivatives such as BCP and BPhen have poor oxidative stability to holes and poor heat resistance, and as a result, have not been commercialized by reducing the lifetime of organic EL devices. In addition, these materials simply block holes, thereby inhibiting the movement of electrons, thereby increasing the driving voltage of the organic EL device.

The present invention has been made to solve the above problems, and an object thereof is to provide an organic electroluminescent device having high efficiency, low voltage, and long life.

The present invention is an anode; cathode; And at least one organic material layer selected from the group consisting of a hole injection layer, a hole transport layer, a light emitting layer, an electron transport layer, and an electron injection layer between the anode and the cathode, and a lifetime improvement layer (Lifetime) between the light emitting layer and the electron transport layer. It provides an organic electroluminescent device further comprising an Enhancement Layer (LEL).

Here, the life improvement layer (LEL) includes a bipolar compound having both an electron attractor (EWG) having a high electron absorption and an electron donor (EDG) having a large electron donor, wherein the bipolar compound includes the following (a) ) To (d) all of the conditions are characterized.

(a) ionization potential [Ip (LEL)] is at least 5.5 eV,

(b) E _HOMO- E _LUMO > 2.9 eV,

(c) the triplet energy is at least 2.3 eV,

(d) ΔEst <0.5 eV (ΔEst represents the difference between the singlet and triplet energies of the compound)

1 is a cross-sectional view illustrating an organic EL device according to an exemplary embodiment of the present invention.

<Short description of symbols>

100: anode 200: cathode

301: hole injection layer 302: hole transport layer

303: light emitting layer 304: life improvement layer

305: electron transport layer 306: electron injection layer

Hereinafter, the present invention will be described.

The present invention is an anode; cathode; And an organic material layer interposed between the anode and the cathode, wherein the organic material layer includes at least one selected from the group consisting of a hole injection layer, a hole transport layer, a light emitting layer, a life improvement layer, an electron transport layer, and an electron injection layer. In addition, the Lifetime Enhancement Layer (LEL) is an organic electroluminescent device including a bipolar compound having both an electron attractor (EWG) having high electron absorption and an electron donor (EDG) having a large electron donor. It is about.

Herein, the bipolar compound may be used as a material of an electron transport layer, an electron injection layer, or both, in addition to the life improvement layer.

Hereinafter, description will be given with reference to FIG. 1.

In the organic electroluminescent device according to the present invention, the anode 100 serves to inject holes into the organic material layer 300.

The material constituting the positive electrode 100 is not particularly limited, and conventional materials known in the art may be used. Non-limiting examples thereof include metals such as vanadium, chromium, copper, zinc and gold; Alloys thereof; Metal oxides such as zinc oxide, indium oxide, indium tin oxide (ITO) and indium zinc oxide (IZO); Combinations of metals and oxides such as ZnO: Al and SnO ₂ : Sb; Conductive polymers such as polythiophene, poly (3-methylthiophene), poly [3,4- (ethylene-1,2-dioxy) thiophene] (PEDT), polypyrrole and polyaniline; And carbon black.

The method of manufacturing the positive electrode 100 is not particularly limited, and may be prepared according to conventional methods known in the art. As an example, a method of coating an anode material on a substrate made of a silicon wafer, quartz, glass plate, metal plate or plastic film may be mentioned.

In the organic electroluminescent device according to the present invention, the cathode 200 serves to inject electrons into the organic material layer 300.

The material constituting the cathode 200 is not particularly limited, and conventional materials known in the art may be used. Non-limiting examples thereof include metals such as magnesium, calcium, sodium, potassium, titanium, indium, yttrium, lithium, gadolinium, aluminum, silver, tin, and lead; Alloys thereof; And multilayer structure materials such as LiF / Al and LiO ₂ / Al.

In addition, the method of manufacturing the cathode 200 is also not particularly limited, and may be manufactured according to methods known in the art.

The organic material layer 300 included in the organic electroluminescent device according to the present invention can be used as an organic material layer of the existing organic electroluminescent device without limitation, for example, a hole injection layer 301, a hole transport layer 302, a light emitting layer ( 303), the life improvement layer 304, the electron transport layer 305 and the electron injection layer 306 may include one or more selected from the group. At this time, in consideration of the characteristics of the organic EL device, it is preferable to include all the above-mentioned organic material layers.

The hole injection layer 301 and the hole transport layer 302 included in the organic material layer 300 of the present invention serve to move the holes injected from the anode 100 to the light emitting layer 303. The material forming the hole injection layer 301 and the hole transport layer 302 is not particularly limited as long as the hole injection barrier is low and the hole mobility is high, and the hole injection layer / transport layer material used in the art can be used without limitation. have. Non-limiting examples thereof include arylamine derivatives.

In addition, the light emitting layer 303 included in the organic material layer 300 of the present invention is a layer in which holes and electrons meet to form an exciton, and the color of light emitted from the organic EL device according to the material forming the light emitting layer 303. This may vary. The light emitting layer 303 may include a host and a dopant, and the host may be included in the range of 70 to 99.9 wt%, and the dopant may be included in the range of 0.1 to 30 wt%.

More specifically, when the light emitting layer 303 is blue fluorescence, green fluorescence or red fluorescence, the host may be included in the range of 80 to 99.9% by weight and the dopant in the range of 0.1 to 20% by weight. In addition, when the emission layer 303 is blue fluorescence, green fluorescence or red phosphorescence, the host may be included in the range of 70 to 99 wt% and the dopant in the range of 1 to 30 wt%.

The host included in the light emitting layer 303 is not particularly limited as long as it is known in the art, and non-limiting examples thereof include alkali metal complex compounds; Alkaline earth metal complexes; Or condensed aromatic ring derivatives.

More specifically, the host material may be an aluminum complex, a beryllium complex, anthracene derivative, pyrene derivative, triphenylene derivative, carbazole derivative, dibenzofuran derivative, di Preference is given to using benzothiophene derivatives or one or more combinations thereof.

In addition, the dopant included in the emission layer 303 is not particularly limited as long as it is known in the art, and non-limiting examples thereof include anthracene derivative, pyrene derivative, arylamine derivative, iridium (Ir) or platinum (Pt). The metal complex compound etc. which are included are mentioned.

The light emitting layer 303 may be a single layer or two or more layers. When the light emitting layer 303 is a plurality of layers, the organic light emitting diode may emit light of various colors. Specifically, the present invention includes a light emitting layer made of a plurality of single materials between the hole transport layer 302 and the life improvement layer 304, or an organic electroluminescent device having a mixed color by having a light emitting layer made of different materials in series. Can be provided. In addition, when the plurality of light emitting layers is included, the driving voltage of the device is increased, but the current value in the organic light emitting device is constant, thereby providing an organic EL device having improved light emission efficiency by the number of light emitting layers.

The lifespan improvement layer 304 included in the organic material layer 300 of the present invention is to improve the lifespan of the organic EL device and is provided between the light emitting layer 303 and the electron transport layer 305.

The material constituting the life improvement layer 304 is not particularly limited, but is preferably a bipolar compound having both an electron attractor (EWG) having high electron absorption and an electron donor (EDG) having a large electron donor. .

More specifically, the bipolar compound has an ionization potential of 5.5 eV or more, specifically, may be in the range of 5.5 to 7.0 eV, preferably in the range of 5.5 to 6.5 eV.

In addition, the difference between the HOMO value and the LUMO value (E _HOMO -E _LUMO ) of the bipolar compound may be greater than 2.9 eV, specifically, greater than 2.9 eV and less than 3.5 eV.

In this case, the triplet energy may be 2.3 eV or more, specifically, 2.3 to 3.5 eV, and preferably 2.3 to 3.0 eV. In addition, the singlet energy and triplet energy difference ΔEst of the bipolar compound is less than 0.5 eV, specifically, the compound is less than 0.5 eV, 0.01 eV or more range.

That is, the holes move in the organic electroluminescent device at the ionization potential level. When the holes diffuse or move to the electron transport layer 305 beyond the light emitting layer 303, an irreversible decomposition reaction by oxidation occurs, which causes organic electroluminescence. The lifetime of the device is reduced.

In contrast, in the present invention, since the life improvement layer 304 made of a bipolar compound having an ionization potential [Ip (LEL)] of 5.5 eV or more is provided, the hole is prevented from diffusing or moving to the electron transport layer 305, and thus the organic electric field. The life of the light emitting device can be improved. That is, the holes are blocked by the high energy barrier of the life improvement layer 304, and thus do not diffuse or move to the electron transport layer 305, but remain in the light emitting layer 303.

Here, when the light emitting layer 303 is made of a red phosphorescent material, the ionization potential of the bipolar compound included in the life improvement layer 304 may be just 5.5 eV or more, but the light emitting layer 303 may be a green phosphor or a blue phosphorescent light. In the case of the material, the ionization potential of the bipolar compound is preferably 6.0 eV or more.

Meanwhile, the bipolar compound has a difference between HOMO and LUMO (E _HOMO -E _LUMO ) of more than 2.9 eV, triplet energy of 2.3 eV or more, singlet energy and triplet energy difference (ΔEst) of less than 0.5 eV. Therefore, when it is used for the life improvement layer 304, the exciton formed in the light emitting layer 303 is prevented from diffusing into the electron transporting layer 305, and light emission occurs at the interface between the light emitting layer 303 and the electron transporting layer 305. You can also stop. As a result, it is possible to prevent spectral mixing of the organic EL device and to improve stability, thereby improving the life of the organic EL device.

More specifically, the bipolar compound has both the electron attracting force (EWG) and the electron donor (EDG) with the high electron donor (EDG) has a characteristic that the electron cloud of HOMO and LUMO is separated. As a result, the difference between the triplet energy and the singlet energy of the compound (ΔEst) is small, which satisfies the relationship of ΔEst <0.5 eV, and thus the difference between the HOMO value and the LUMO value (E _HOMO -E _LUMO ) is higher than 2.9 eV. It may have a triplet energy (T1).

When the light emitting layer 303 is made of a red phosphorescent material, the triplet energy of the bipolar compound included in the lifespan improvement layer 304 may be 2.3 eV or more, but when the light emitting layer 303 is made of green phosphorescent material, In the case of 2.5 eV or more and a blue phosphor, it is preferably 2.7 eV or more.

On the other hand, if the balance between electrons and holes is not corrected due to the difference between the number of holes injected from the anode 100 and the number of electrons injected from the cathode 200, the electrons or holes that do not form excitons by recombination may be light emitting layers 303. Stacked). Electrons or holes accumulated in the light emitting layer 303 may prevent oxidation and reduction from occurring smoothly in the light emitting layer 303 or may affect adjacent layers to reduce the lifespan of the organic EL device.

In contrast, since the bipolar compound has a hole mobility and an electron mobility of 1 × 10 ⁻⁶ cm ² / V · s or more at room temperature, when used in the life improvement layer 304, holes injected from the anode 100 are used. The life of the organic EL device can be improved by preventing the injection of electrons to be delayed compared to the number of.

In fact, the bipolar compound included in the life improvement layer 304 of the present invention exhibits hole mobility of 1 × 10 ⁻⁶ cm ² / V · s or more at room temperature by an electron donor (EDG), EWG) results in electron mobility of 1 × 10 ⁻⁶ cm ² / V · s or more at room temperature. Therefore, when it is used for the lifespan improvement layer 304, electrons can be effectively injected into the light emitting layer 303. As such, when the electron injection into the light emitting layer 303 is smooth, the formation efficiency of the exciton in the light emitting layer 303 may be improved, thereby improving the life of the organic EL device.

The bipolar compound included in the life improvement layer 304 of the present invention has a moiety having an electron attracting (EWG) characteristic with high electron absorption and a moiety having a large electron donor (EDG) characteristic with an electron donor. Is formed by combining. In this case, the electron drawer (EWG) is characterized in that it comprises one or more electron drawer (EWG) moiety represented by the following formula.

Where

A ₁ to A ₁₁ are the same as or different from each other, each independently N or C (R), and at least one is N, wherein a plurality of R's are the same or different, respectively, even if the same are indicated, and they are condensed with adjacent groups May form a ring. For example, in the case of plural C (R), A ₁ and A ₂ , A ₂ and A ₃ , A ₃ and A ₄ , A ₄ and A ₅ , A ₅ and A ₆ , or A ₆ and A ₁ are bonded to each other Condensed ring can be formed, and A ₇ and A ₈ , A ₈ and A ₉ , A ₉ and A ₁₀ , A ₁₀ and A ₁₁ , A ₁₁ and A ₇ can be combined with each other to form a condensed ring. .

R is hydrogen, deuterium, halogen group, cyano group, nitro group, amino group, C ₁ ~ C ₄₀ alkyl group, C ₂ ~ C ₄₀ alkenyl group, C ₂ ~ C ₄₀ alkynyl group, C ₃ ~ C ₄₀ Cycloalkyl group, heterocycloalkyl group of 3 to 40 nuclear atoms, aryl group of C ₆ to C ₆₀ , heteroaryl group of 5 to 60 nuclear atoms, alkyloxy group of C ₁ to C ₄₀ , C ₆ to C ₆₀ Aryloxy group, C ₁ to C ₄₀ alkylsilyl group, C ₆ to C ₆₀ arylsilyl group, C ₁ to C ₄₀ alkyl boron group, C ₆ to C ₆₀ aryl boron group, C ₁ to C ₄₀ A phosphine group, a C ₁ to C ₄₀ phosphine oxide group and a C ₆ to C ₆₀ arylamine group,

Alkyl group, alkenyl group, alkynyl group, cycloalkyl group, heterocycloalkyl group, aryl group, heteroaryl group, alkyloxy group, aryloxy group, alkylsilyl group, arylsilyl group, alkyl boron group, aryl boron group, force of the above R The pin group, the phosphine oxide group and the arylamine group are each independently deuterium, halogen group, cyano group, nitro group, amino group, C ₁ ~ C ₄₀ alkyl group, C ₂ ~ C ₄₀ alkenyl group, C ₂ ~ C ₄₀ alkynyl group, C ₃ ~ C ₄₀ cycloalkyl group, nuclear atoms, 3 to 40 heterocycloalkyl group, C ₆ ~ C ₄₀ aryl group, nuclear atoms aryl of from 5 to 40 heteroaryl group, a C ₁ ~ C ₄₀ alkyl Oxy group, C ₆ ~ C ₆₀ aryloxy group, C ₁ ~ C ₄₀ alkylsilyl group, C ₆ ~ C ₆₀ arylsilyl group, C ₁ ~ C ₄₀ alkyl boron group, C ₆ ~ C ₆₀ aryl boron group, C ₁ ~ C ₄₀ of the phosphine group, C ₁ ~ C ₄₀ phosphine oxide group, and a C ₆ ~ by at least one member selected from the group consisting of an aryl amine of the C ₆₀ substituted or unsubstituted of .

The electron attracting (EWG) moiety is a nitrogen-containing heteroaromatic hydrocarbon having 5 or 6 nuclear atoms in which 1-3 carbons are substituted with nitrogen. In addition, the EWG moiety may have a form in which two or more rings are simply attached to or condensed with each other, or in the form of an aryl group.

In the present invention, the electron attracting moiety (EWG) moiety may be more embodied in a structure represented by the following formula, it is preferable when the six-membered nitrogen heteroaromatic hydrocarbon containing 1 to 3 nitrogen. Non-limiting examples of preferred EWG moieties include pyridine, pyrimidine, triazine, pyrazine and the like.

In the present invention, the carbon or nitrogen atom of the moiety having the electron-extracting (EWG) property having high electron absorption forms a bond with the moiety having the electron donor (EDG) property having a large electron donating property.

The bipolar compound included in the lifespan improvement layer 304 of the present invention is characterized by including an electron donor (EDG) moiety represented by the following Chemical Formula 1.

As such, non-limiting examples of moieties having large electron donor (EDG) characteristics of electron donors include condensed nitrogen heteroaromatic rings such as indole, carbazole, and azepine; Alternatively, condensed polycyclic aromatic rings such as biphenyl, triphenylene, and fluoranthene may be used, and more specifically, may be represented by the following Chemical Formula 1.

[Formula 1]

In Chemical Formula 1,

X ₁ is selected from the group consisting of O, S, Se, N (Ar ₁ ), C (Ar ₂ ) (Ar ₃ ) and Si (Ar ₄ ) (Ar ₅ ),

Y ₁ to Y ₄ are the same as or different from each other, and each independently N or C (R ₁ ), wherein a plurality of R ₁ are each the same or different even if represented the same, and they may form a condensed ring with an adjacent group And

X ₂ and X ₃ are the same as or different from each other, and each independently N or C (R ₂ ), wherein a plurality of R ₂ are the same or different, even though they are the same, and they may form condensed rings with adjacent groups And

R ₁ to R ₂ and Ar ₁ to Ar ₅ are the same as or different from each other, and each independently, hydrogen, deuterium, a halogen group, a cyano group, a nitro group, an amino group, a C ₁ to C ₄₀ alkyl group, C ₂ to C ₄₀ alkenyl group, C ₂ to C ₄₀ alkynyl group, C ₃ to C ₄₀ cycloalkyl group, nuclear atom 3 to 40 heterocycloalkyl group, C ₆ to C ₆₀ aryl group, nuclear atom 5 to 60 Heteroaryl group, C ₁ ~ C ₄₀ alkyloxy group, C ₆ ~ C ₆₀ aryloxy group, C ₁ ~ C ₄₀ alkylsilyl group, C ₆ ~ C ₆₀ arylsilyl group, C ₁ ~ C ₄₀ alkyl boron group, is selected from the group consisting of C ₆ ~ C group ₆₀ arylboronic of, C ₁ ~ C ₄₀ of the phosphine group, C ₁ ~ C ₄₀ phosphine oxide group, and a C ₆ ~ with an aryl amine of the C ₆₀ of,

The alkyl group, alkenyl group, alkynyl group, cycloalkyl group, heterocycloalkyl group, aryl group, heteroaryl group, alkyloxy group, aryloxy group, alkylsilyl group, arylsilyl group of R ₁ to R ₂ and Ar ₁ to Ar ₅ , Alkyl boron group, aryl boron group, phosphine group, phosphine oxide group and arylamine group are each independently deuterium, halogen group, cyano group, nitro group, amino group, C ₁ ~ C ₄₀ alkyl group, C ₂ ~ C ₄₀ Alkenyl group, C ₂ to C ₄₀ alkynyl group, C ₃ to C ₄₀ cycloalkyl group, nuclear atom 3 to 40 heterocycloalkyl group, C ₆ to C ₄₀ aryl group, nuclear atom 5 to 40 hetero aryl group, C ₁ ~ C ₄₀ of the alkyloxy group, C ₆ ~ C ₆₀ of the aryloxy group, C ₁ ~ C ₄₀ alkyl silyl group, the group C ₆ ~ C ₆₀ aryl silyl, C ₁ ~ C ₄₀ alkyl boron group, C ₆ ~ C ₆₀ aryl group of boron, C ₁ ~ C ₄₀ of the phosphine group, C ₁ ~ C ₄₀ of the phosphine oxide group, and a C ₆ ~ at least one selected from the group consisting of C ₆₀ arylamine Substituted or unsubstituted.

In the present invention, Chemical Formula 1 may be more embodied as any one of the following A-1 to A-24. However, it is not limited thereto.

In the above A-1 to A-24,

The definitions of R ₂ , Y ₁ to Y _4, and Ar ₁ to Ar ₅ are the same as those of Formula 1 described above. In consideration of the physical and chemical properties of the compound, the electron donor (EDG) moiety is preferably A-1 to A-6.

On the other hand, in the present invention, Formula 1, which is an electron donor (EDG) moiety, may be used alone or as a condensed structure in combination with Formula 2 or Formula 3 below.

More specifically, in Formula 1, Y ₁ to Y ₄ are each independently N or C (R ₁ ), and when they are a plurality of C (R ₁ ), Y ₁ and Y ₂ , Y ₂ and Y ₃ or Y ₃ And one of Y ₄ forms a condensed ring with Formula 2 below. In this case, a plurality of R ₁ may be the same or different, respectively.

In addition, when both X ₂ And X _{3 In} Formula 1 is C (R ₂ ), a plurality of R ₂ may be combined with Formula 2 or Formula 3, respectively, to form a condensed ring.

[Formula 2]

[Formula 3]

In Chemical Formulas 2 and 3,

Y ₅ to Y ₁₄ are the same as or different from each other, and each independently N or C (R ₃ ), wherein when a plurality of C (R ₃ ) is a plurality of R ₃ are the same or different, respectively, and are bonded to the formula (1) To form a condensed ring,

X ₄ is the same as X ₁ , wherein a plurality of Ar ₁ to Ar ₅ are the same or different, respectively.

A plurality of R ₃ non-forming a condensed ring may be the same or different from each other even if they are the same, and each independently represent hydrogen, deuterium, a halogen group, a cyano group, a nitro group, an amino group, a C ₁ to C ₄₀ alkyl group, C ₂ ~ C ₄₀ alkenyl group, C ₂ ~ C ₄₀ of the alkynyl group, C ₃ ~ C ₄₀ cycloalkyl group, a number of nuclear atoms of 3 to 40 heterocycloalkyl group, C ₆ ~ C ₆₀ aryl group, a nuclear Heteroaryl group of 5 to 60 atoms, C ₁ ~ C ₄₀ alkyloxy group, C ₆ ~ C ₆₀ aryloxy group, C ₁ ~ C ₄₀ alkylsilyl group, C ₆ ~ C ₆₀ arylsilyl group, C ₁ ~ alkyl boron C ₄₀ group, C ₆ ~ C ₆₀ aryl boron group, C ₁ ~ C ₄₀ of the phosphine group, C ₁ ~ C ₄₀ phosphine configured groups oxide groups and C ₆ ~ arylamine of the C ₆₀ of the Selected from the military,

Alkyl group of the R _3, an alkenyl group, an alkynyl group, a cycloalkyl group, a heterocycloalkyl group, an aryl group, a heteroaryl group, an alkyloxy group, an aryloxy group, an alkylsilyl group, an arylsilyl group, an alkyl boron group, an aryl boron group, The phosphine group, the phosphine oxide group and the arylamine group are each independently deuterium, halogen group, cyano group, nitro group, amino group, C ₁ ~ C ₄₀ alkyl group, C ₂ ~ C ₄₀ alkenyl group, C ₂ ~ C ₄₀ Alkynyl group, C ₃ to C ₄₀ cycloalkyl group, nuclear atom 3 to 40 heterocycloalkyl group, C ₆ to C ₄₀ aryl group, nuclear atom 5 to 40 heteroaryl group, C ₁ to C ₄₀ Alkyloxy group, C ₆ ~ C ₆₀ aryloxy group, C ₁ ~ C ₄₀ alkylsilyl group, C ₆ ~ C ₆₀ arylsilyl group, C ₁ ~ C ₄₀ alkyl boron group, C ₆ ~ C ₆₀ aryl boron group, C ₁ ~ C ₄₀ of the phosphine group, C ₁ ~ C ₄₀ phosphine oxide group, and a C ₆ ~ substituted by one or more selected from the group consisting of C ₆₀ aryl amine, or unsubstituted of The.

In the present invention, the compound formed by condensation of Chemical Formula 1 and Chemical Formula 2 may be embodied in any one of the compounds represented by the following Chemical Formulas 1a to 1f.

[Formula 1a]

[Formula 1b]

[Formula 1c]

[Formula 1d]

[Formula 1e]

[Formula 1f]

In Chemical Formulas 1a to 1f,

X ₁ to X ₄ and Y ₁ to Y ₈ are as defined in the formula (1) and (2).

According to a preferred embodiment of the present invention, Y ₁ to Y ₄ which form a condensed ring are N or C (R ₁ ), all of which are preferred when C (R ₁ ), and Y ₅ to Y ₈ are N Or C (R ₃ ), all of which are C (R ₃ ). In this case, a plurality of R ₁ and R ₃ are the same or different, respectively.

Compounds of the present invention in which Formula 1 and Formula 2 are condensed may be embodied as any one of the following Formulas B-1 to B-30. However, it is not limited to this.

In Chemical Formulas B-1 to B-30,

Ar ₁ and R ₁ to R ₃ are the same as defined in the formula (1) and (2).

More specifically, Ar ₁ is a substituted or unsubstituted C ₆ ~ C ₄₀ aryl group, or a substituted or unsubstituted heteroaryl group having 5 to 40 nuclear atoms,

R ₁ to R ₃ are each independently hydrogen, a substituted or unsubstituted C ₁ to C ₄₀ alkyl group, a substituted or unsubstituted C ₆ to C ₄₀ aryl group, or a substituted or unsubstituted nuclear atom 5 to 40 It is preferable when it is a heteroaryl group of.

Here, Formulas B-1 to B-30 having a condensed structure of Formulas 1 and 2 include one or more condensed indole or condensed carbazole moieties.

In addition, in the present invention, the compound formed by condensation of Formula 1 and Formula 3 may be embodied as any one of the compounds represented by the following Formulas 1g to 1n.

[Formula 1g]

[Formula 1h]

Formula 1i]

[Formula 1j]

[Formula 1k]

[Formula 1l]

[Formula 1m]

[Formula 1n]

In Formula 1g to 1n,

X ₁ , X ₃ to X ₄ and Y ₁ to Y ₁₄ are the same as defined in Formula 1 and Formula 3.

More specifically, X ₁ and X ₄ are the same as or different from each other, preferably each independently O, S or N (Ar ₁ ), more preferably all N (Ar ₁ ). At this time, a plurality of Ar ₁ is the same or different.

Y ₁ to Y ₄ are the same as or different from each other, and each independently N or C (R ₁ ), preferably all of C (R ₁ ). In this case, a plurality of R ₁ are the same or different.

X ₃ are each independently N or C (R ₂ ),

Y ₅ to Y ₁₄ are the same as or different from each other, and each independently N or C (R ₃ ), preferably all of C (R ₃ ). In this case, a plurality of R ₃ are the same or different.

Here, Ar ₁ and R ₁ to R ₃ are as defined in the formula (1) and (3).

According to one embodiment of the present invention, in Formulas 1a to 1n, X ₁ and X ₄ are each independently N (Ar ₁ ) or S. That is, it is preferable that X ₁ is N (Ar ₁ ) and X ₄ is S, X ₁ is S and X ₄ is N (Ar ₁ ), or both X ₁ and X ₄ are N (Ar ₁ ).

In addition, in Formula 1a to Formula 1n, Ar ₁ is preferably a substituted or unsubstituted C ₆ ~ C ₆₀ aryl group, or a substituted or unsubstituted heteroaryl group having 5 to 60 nuclear atoms, Ar ₂ to Ar ₅ is the same as or different from each other, and each independently represent a substituted or unsubstituted C ₁ to C ₄₀ alkyl group (specifically, a methyl group) or a substituted or unsubstituted C ₆ to C ₆₀ aryl group (specifically, a phenyl group) desirable.

Here, the chemical formulas having the condensed structure of Chemical Formulas 1 and 3 have the characteristics of an electron donor (EDG) having a large electron donor including one or more condensed azepine moieties.

Meanwhile, in the present invention, the bipolar compound included as a material for the lifespan improvement layer may include a moiety having an electron donor (EDG) characteristic of which the electron donor represented by the following Chemical Formula 4 is large.

[Formula 4]

In Chemical Formula 4,

L ₁ to L ₃ are the same as or different from each other, and each independently selected from the group consisting of a single bond, a C ₆ to C ₆₀ arylene group, a heteroarylene group having 5 to 60 nuclear atoms,

Ar ₆ to Ar ₈ are the same as or different from each other, and are each independently selected from the group consisting of hydrogen, deuterium, an aryl group having ₆ to ₄₀ carbon atoms and a heteroaryl group having 5 to 40 nuclear atoms, provided that Ar ₆ to Ar Except when ₈ are all the same,

R ₄ to R ₆ are the same or different, each independently, hydrogen, deuterium, a halogen group, a cyano group, a nitro group, an amino group, an alkenyl group of C ₁ ~ C ₄₀ alkyl group, C ₂ ~ C ₄₀ of, C ₂ Alkynyl group of ˜C ₄₀ , cycloalkyl group of C ₃ ˜C ₄₀ , heterocycloalkyl group of 3 to 40 nuclear atoms, aryl group of C ₆ ˜C ₆₀ , heteroaryl group of 5 to 60 nuclear atoms, C ₁ ˜ C ₄₀ alkyloxy group, C ₆ ~ C ₆₀ aryloxy group, C ₁ ~ C ₄₀ alkylsilyl group, C ₆ ~ C ₆₀ arylsilyl group, C ₁ ~ C ₄₀ alkyl boron group, C ₆ ~ is selected from the group consisting of C ₆₀ aryl boron group, C ₁ ~ C ₄₀ of the phosphine group, C ₁ ~ C ₄₀ phosphine oxide group, and a C ₆ ~ C ₆₀ aryl group of an amine of,

a to c are each independently an integer of 0 to 3,

The arylene group, heteroarylene group, alkyl group, alkenyl group, alkynyl group, cycloalkyl group, heterocycloalkyl group, aryl group, heteroaryl group, alkyl jade of L ₁ to L ₃ , R ₄ to R ₆ and Ar ₆ to Ar ₈ The time period, aryloxy group, alkylsilyl group, arylsilyl group, alkyl boron group, aryl boron group, phosphine group, phosphine oxide group and arylamine group are each independently deuterium, halogen group, cyano group, nitro group, amino group, C ₁ ~ C ₄₀ Alkyl group, C ₂ ~ C ₄₀ Alkenyl group, C ₂ ~ C ₄₀ Alkynyl group, C ₃ ~ C ₄₀ Cycloalkyl group, C ₃ ~ 40 Heterocycloalkyl group, C ₆ ~ C ₄₀ aryl group, nuclear atom 5 to 40 heteroaryl group, C ₁ ~ C ₄₀ alkyloxy group, C ₆ ~ C ₆₀ aryloxy group, C ₁ ~ C ₄₀ alkylsilyl group, C ₆ ~ C ₆₀ arylsilyl group, a alkyl boronic of _{C 1 ~ C 40, C 6} ~ C group ₆₀ arylboronic of, C ₁ ~ C ₄₀ of the phosphine group, C ₁ ~ phosphine oxide of a C ₄₀ group, and a C ₆ ~ C ₆₀ of Arya Substituted or unsubstituted with one or more selected from the group consisting of min groups.

More specifically, in Formula 4, L _{One To} L _{3 It} is preferably each independently a single bond, phenylene, biphenylene, or carbazolylene.

Ar ₆ to Ar ₈ are the same as or different from each other, and are each independently selected from the group consisting of hydrogen, deuterium, an aryl group having ₆ to ₄₀ carbon atoms and a heteroaryl group having 5 to 40 nuclear atoms, wherein Ar ₆ to At least one of Ar ₈ is preferably selected from a heteroaryl group having 5 to 40 nuclear atoms including at least one element selected from the group consisting of N, O, and S. However, the case where Ar ₆ to Ar ₈ are all the same is excluded.

In the present invention, in the compounds represented by Formula 1a to Formula 1n and Formula 4, at least one of R ₁ to R ₆ and Ar ₁ to Ar ₈ is the moiety having an electron-withdrawing (EWG) property of high electron absorption Form a bond with.

Alkyl in the present invention is a monovalent substituent derived from a straight or branched chain saturated hydrocarbon having 1 to 40 carbon atoms, and examples thereof include methyl, ethyl, propyl, isobutyl, sec-butyl, pentyl, iso-amyl, hexyl and the like. Can be mentioned.

Alkenyl in the present invention is a monovalent substituent derived from a straight or branched chain unsaturated hydrocarbon having 2 to 40 carbon atoms having one or more carbon-carbon double bonds. Examples thereof include vinyl and allyl. ), Isopropenyl, 2-butenyl, and the like.

Alkynyl in the present invention is a monovalent substituent derived from a C2-C40 straight or branched chain unsaturated hydrocarbon having one or more carbon-carbon triple bonds. Examples thereof include ethynyl, 2- Propanyl (2-propynyl) etc. are mentioned.

Aryl in the present invention means a monovalent substituent derived from an aromatic hydrocarbon having 6 to 60 carbon atoms combined with a single ring or two or more rings. In addition, a form in which two or more rings are attached to each other (pendant) or condensed may also be included. Examples of such aryls include phenyl, naphthyl, phenanthryl, anthryl and the like.

Heteroaryl in the present invention means a monovalent substituent derived from monoheterocyclic or polyheterocyclic aromatic hydrocarbon having 5 to 60 nuclear atoms. At least one carbon in the ring, preferably 1 to 3 carbons, is substituted with a heteroatom such as N, O, S or Se. In addition, a form in which two or more rings are pendant or condensed with each other may also be included, and may also include a form condensed with an aryl group. Examples of such heteroaryl include 6-membered monocyclic rings such as pyridyl, pyrazinyl, pyrimidinyl, pyridazinyl, triazinyl, phenoxathienyl, indolinzinyl, indolyl ( polycyclic rings such as indolyl, purinyl, quinolyl, benzothiazole, carbazolyl, 2-furanyl, N-imidazolyl, 2-isoxazolyl , 2-pyridinyl, 2-pyrimidinyl, and the like.

Aryloxy in the present invention is a monovalent substituent represented by RO-, wherein R means aryl having 6 to 60 carbon atoms. Examples of such aryloxy include phenyloxy, naphthyloxy, diphenyloxy and the like.

Alkyloxy in the present invention is a monovalent substituent represented by R'O-, wherein R 'means 1 to 40 alkyl, and includes a linear, branched or cyclic structure It is interpreted as. Examples of such alkyloxy include methoxy, ethoxy, n-propoxy, 1-propoxy, t-butoxy, n-butoxy, pentoxy and the like.

Arylamine in the present invention means an amine substituted with aryl having 6 to 60 carbon atoms.

Cycloalkyl in the present invention means a monovalent substituent derived from a monocyclic or polycyclic non-aromatic hydrocarbon having 3 to 40 carbon atoms. Examples of such cycloalkyl include cyclopropyl, cyclopentyl, cyclohexyl, norbornyl, adamantine and the like.

Heterocycloalkyl in the present invention means a monovalent substituent derived from a non-aromatic hydrocarbon having 3 to 40 nuclear atoms, wherein at least one carbon in the ring, preferably 1 to 3 carbons is N, O, S or Substituted with a hetero atom such as Se. Examples of such heterocycloalkyl include morpholine, piperazine and the like.

Alkylsilyl in the present invention is silyl substituted with alkyl having 1 to 40 carbon atoms, arylsilyl means silyl substituted with aryl having 6 to 40 carbon atoms.

Condensed ring in the present invention means a condensed aliphatic ring, a condensed aromatic ring, a condensed heteroaliphatic ring, a condensed heteroaromatic ring or a combination thereof.

In the organic electroluminescent device according to the present invention, the electron transport layer 305 and the electron injection layer 306 included in the organic material layer 300 serves to move the electrons injected from the cathode 200 to the light emitting layer 303. do.

The material constituting the electron transport layer 305 and the electron injection layer 306 is not particularly limited as long as it is easy to inject electrons and has high electron mobility, but is not limited thereto. The bipolar compound, anthracene derivative, and heteroaromatic compound may be used. And alkali metal complex compounds.

More specifically, the electron transport layer 305 and / or the electron injection layer 306 of the present invention is preferably made of the same bipolar material, that is, the bipolar compound represented by the formula (1). In addition, the electron transport layer 305 and / or the electron injection layer 306 may be a co-deposited alkali metal complex compound to facilitate the injection of electrons from the cathode. In this case, the alkali metal complex compound may be an alkali metal, an alkaline earth metal or a rare earth metal.

The organic material layer 300 of the present invention as described above may further include an organic film layer (not shown) for blocking electrons and excitons between the hole transport layer 302 and the light emitting layer 303.

The organic layer has a high LUMO value to prevent electrons from moving to the hole transport layer 302, and has a high triplet energy to prevent the excitons of the light emitting layer 303 from diffusing into the hole transport layer 302. The material constituting such an organic film layer is not particularly limited, and examples thereof include carbazole derivatives or arylamine derivatives.

The method of manufacturing the organic material layer 300 of the present invention is not particularly limited, but non-limiting examples include a vacuum deposition method and a solution coating method. Examples of the solution coating method may be spin coating, dip coating, doctor blading, inkjet printing, thermal transfer method and the like.

The organic electroluminescent device of the present invention has a structure in which the anode 100, the organic material layer 300 and the cathode 200 are sequentially stacked, between the anode 100 and the organic material layer 300 or between the cathode 200 and the organic material layer The insulating layer or the adhesive layer may be further included between the 300. Such an organic electroluminescent device of the present invention may have excellent lifespan characteristics since life time of initial brightness is increased while maintaining the maximum luminous efficiency when voltage, current, or both are applied.

Hereinafter, the present invention will be described in detail with reference to Examples, but the following Examples are merely illustrative of the present invention, and the present invention is not limited by the following Examples.

Preparation Examples 1 to 36 Preparation of Compounds LE-01 to LE-36

Compounds represented by the following LE-01 to LE-36 were prepared as the bipolar compound of the present invention, and ΔEst, triplet energy, ionization potential, E _HOMO- E _LUMO , electron mobility, and hole mobility were prepared in the art. Each measured by a known method is shown in Table 1 below.

The bipolar compounds LE-01 to LE-36 are shown below, respectively.

Table 1

	Calculated Value (B3LYP / 6-31G *)		Actual value
Bipolar compound	ΔEst (S1-T1)	Triplet energy	Ionization potential	E HOMO -E LUMO	Electron mobility	Hole mobility
LE-01	0.058	2.39	5.54	3.55	8.9Ｘ10 -5	5.5Ｘ10 -5
LE-02	0.168	2.45	5.50	3.47	5.8Ｘ10 -5	3.3Ｘ10 -5
LE-03	0.355	2.54	5.71	3.3	8.8Ｘ10 -4	1.1Ｘ10 -5
LE-04	0.059	2.53	5.6	3.37	7.6Ｘ10 -4	1.2Ｘ10 -5
LE-05	0.138	2.65	5.58	3.43	7.5Ｘ10 -4	9.0Ｘ10 -5
LE-06	0.177	2.50	5.64	3.07	9.6Ｘ10 -4	9.9Ｘ10 -5
LE-07	0.121	2.48	5.65	3.42	9.2Ｘ10 -4	9.6Ｘ10 -5
LE-08	0.298	2.74	6.01	3.33	5.1Ｘ10 -5	5.5Ｘ10 -5
LE-09	0.291	2.38	5.71	3.32	9.9Ｘ10 -4	2.5Ｘ10 -5
LE-10	0.321	2.35	5.69	3.31	1.0Ｘ10 -5	6.5Ｘ10 -5
LE-11	0.261	2.81	6.01	3.36	9.9Ｘ10 -5	4.1Ｘ10 -5
LE-12	0.340	2.78	6.05	3.23	1.1Ｘ10 -6	5.4Ｘ10 -5
LE-13	0.235	2.59	5.50	3.51	1.3Ｘ10 -6	1.1Ｘ10 -5
LE-14	0.265	2.51	5.51	3.41	2.1Ｘ10 -6	1.6Ｘ10 -5
LE-15	0.049	2.59	5.56	3.50	7.5Ｘ10 -5	5.5Ｘ10 -5
LE-16	0.051	2.54	5.51	3.49	8.5Ｘ10 -6	4.5Ｘ10 -5
LE-17	0.058	2.43	5.64	3.15	7.8Ｘ10 -5	5.0Ｘ10 -5
LE-18	0.074	2.50	5.68	3.24	6.5Ｘ10 -4	4.2Ｘ10 -5
LE-19	0.082	2.45	5.73	3.20	7.5Ｘ10 -4	8.5Ｘ10 -5
LE-20	0.168	2.56	5.70	3.17	5.8Ｘ10 -5	3.3Ｘ10 -5
LE-21	0.235	2.48	5.60	3.14	6.4Ｘ10 -4	6.1Ｘ10 -5
LE-22	0.129	2.57	5.70	2.93	7.0Ｘ10 -4	4.2Ｘ10 -5
LE-23	0.090	2.53	5.83	3.54	7.0Ｘ10 -5	5.5Ｘ10 -5
LE-24	0.044	2.47	5.69	3.06	6.6Ｘ10 -3	9.1Ｘ10 -5
LE-25	0.157	2.43	5.99	3.10	8.1Ｘ10 -4	7.9Ｘ10 -5
LE-26	0.054	2.39	5.82	3.23	9.5Ｘ10 -3	9.4Ｘ10 -5
LE-27	0.121	2.41	5.75	3.12	3.7Ｘ10 -4	4.8Ｘ10 -5
LE-28	0.057	2.50	6.01	3.33	5.1Ｘ10 -5	5.5Ｘ10 -5
LE-29	0.045	2.37	6.19	3.36	3.9Ｘ10 -4	8.1Ｘ10 -5
LE-30	0.244	2.45	6.09	3.35	5.6Ｘ10 -4	7.5Ｘ10 -5
LE-31	0.235	2.40	5.70	3.14	6.4Ｘ10 -4	6.1Ｘ10 -5
LE-32	0.129	2.34	5.68	2.93	7.0Ｘ10 -4	4.2Ｘ10 -5
LE-33	0.342	2.55	6.21	3.23	7.5Ｘ10 -4	5.9Ｘ10 -5
LE-34	0.295	2.47	6.15	3.06	6.6Ｘ10 -3	9.1Ｘ10 -5
LE-35	0.310	2.43	6.09	3.10	8.1Ｘ10 -4	7.9Ｘ10 -5
LE-36	0.265	2.39	6.18	3.23	9.5Ｘ10 -3	9.4Ｘ10 -5
Hole mobility and electron mobility measure the transit time of carrier by depositing bipolar compound into 1㎛ thickness.

Examples 1 to 36 Fabrication of Blue Fluorescent Organic Electroluminescent Devices

The glass substrate coated with ITO (Indium tin oxide) with a thickness of 1500Å was ultrasonically washed with distilled water. After washing the distilled water, ultrasonic cleaning with a solvent such as isopropyl alcohol, acetone, methanol, dried, transferred to a UV OZONE cleaner (Power sonic 405, Hwasin Tech), and then the substrate is cleaned for 5 minutes by UV The substrate was transferred to a vacuum evaporator.

A device was manufactured by sequentially depositing a hole injection layer, a hole transport layer, a light emitting layer, a life improvement layer, an electron transport layer, an electron injection layer, and a cathode on an ITO transparent electrode (substrate) prepared as described above. The structure of the manufactured device is shown in Table 2 below.

TABLE 2

	compound	thickness
Hole injection layer	DS-205 (Doosan Corporation)	80 nm
Hole transport layer	NPB	15 nm
Light emitting layer	ADN + 5% DS-405 (Doosan Corporation)	30 nm
Life Improvement Layer	LE-01 to LE-36	5 nm
Electron transport layer	Alq 3	25 nm
Electron injection layer	LiF	1nm
cathode	Al
	200 nm

As used in Table 2, the structure of NPB, ADN and Alq ₃ is as follows.

Comparative Example 1 Fabrication of Blue Fluorescent Organic Electroluminescent Device

A device was manufactured in the same manner as in Example 1, except that the electron transport layer was deposited at 30 nm without using the life improving layer.

Comparative Example 2 Fabrication of Blue Fluorescent Organic Electroluminescent Device

A device was manufactured in the same manner as in Example 1, except that BCP having the following structure instead of LE-01 was used.

Experimental Example 1

For each device manufactured in Examples 1 to 36 and Comparative Examples 1 and 2, the driving voltage, current efficiency, light emission wavelength, and lifetime (T ₉₇ ) at a current density of 10 mA / cm ² were measured. Table 3 shows.

TABLE 3

	compound	Driving voltage (V)	Current efficiency (cd / A)	Emission Peak (nm)	Life (hr)
Example 1	LE-01	4.5	5.9	458	45
Example 2	LE-02	4.7	5.6	458	50
Example 3	LE-03	4.5	5.9	458	75
Example 4	LE-04	4.2	6.0	458	54
Example 5	LE-05	4.1	5.7	458	42
Example 6	LE-06	4.3	6.1	458	78
Example 7	LE-07	4.2	6.0	458	75
Example 8	LE-08	4.7	5.7	457	82
Example 9	LE-09	4.4	6.1	458	51
Example 10	LE-10	4.1	5.7	458	39
Example 11	LE-11	4.9	5.4	458	103
Example 12	LE-12	5.0	5.3	457	88
Example 13	LE-13	5.0	5.5	458	39
Example 14	LE-14	4.9	5.6	458	40
Example 15	LE-15	4.2	6.1	458	59
Example 16	LE-16	4.6	5.7	458	45
Example 17	LE-17	4.5	6.1	458	55
Example 18	LE-18	4.3	6.5	458	59
Example 19	LE-19	4.4	6.4	457	60
Example 20	LE-20	4.7	6.0	458	50
Example 21	LE-21	4.5	6.2	458	75
Example 22	LE-22	4.2	6.6	458	55
Example 23	LE-23	4.1	6.6	458	92
Example 24	LE-24	4.4	6.2	457	45
Example 25	LE-25	4.3	6.1	458	78
Example 26	LE-26	4.1	6.2	458	64
Example 27	LE-27	4.2	6.0	458	75
Example 28	LE-28	4.7	6.4	457	85
Example 29	LE-29	4.3	6.0	458	62
Example 30	LE-30	4.5	6.3	458	60
Example 31	LE-31	4.6	6.2	458	55
Example 32	LE-32	4.5	6.4	457	59
Example 33	LE-33	4.4	6.3	458	81
Example 34	LE-34	4.5	6.3	458	70
Example 35	LE-35	4.5	6.3	458	83
Example 36	LE-36	4.5	6.2	457	92
Comparative Example 1	-	4.7	5.6	458	32
Comparative Example 2	BCP	5.3	5.9	458	28
Life time measures the time when the luminance is 97%

Looking at the Table 3, it can be seen that the organic EL device of Examples 1 to 12 including the life improvement layer of the present invention is superior in current efficiency, driving voltage and life than the organic EL device of Comparative Examples 1 and 2 there was.

Examples 37 to 51 Fabrication of Green Phosphorescent Organic Electroluminescent Device

The glass substrate coated with ITO (Indium tin oxide) with a thickness of 1500Å was ultrasonically washed with distilled water. After washing the distilled water, ultrasonic cleaning with a solvent such as isopropyl alcohol, acetone, methanol, dried and transferred to a UV OZONE cleaner (Power sonic 405, Hwasin Tech), and then wash the substrate for 5 minutes by UV and vacuum The substrate was transferred to the evaporator.

A device was manufactured by sequentially depositing a hole injection layer, a hole transport layer, a light emitting layer, a life improvement layer, an electron transport layer, an electron injection layer, and a cathode on an ITO transparent electrode (substrate) prepared as described above. The structure of the manufactured device is shown in Table 4 below.

Table 4

	compound	thickness
Hole injection layer	m-MTDATA	60 nm
Hole transport layer	TCTA	80 nm
Light emitting layer	CBP + 10% Ir (ppy) 3	30 nm
Life Improvement Layer	See Table 5 below	5 nm
Electron transport layer	Alq 3	25 nm
Electron injection layer	LiF	1nm
cathode	Al
	200 nm

As used in Table 4, m-MTDATA, TCTA, Ir (ppy) ₃ and the structure of the CBP is as follows.

Comparative Example 3 Fabrication of Green Phosphorescent Organic Electroluminescent Device

A device was manufactured in the same manner as in Example 37, except that an electron transport layer was deposited at 30 nm without using a lifetime improving layer.

Comparative Example 4 Fabrication of Green Phosphorescent Organic Electroluminescent Device

A device was manufactured in the same manner as in Example 37, except for using the BCP used in Comparative Example 2 instead of LE-02.

Experimental Example 2

For each device manufactured in Examples 37 to 51 and Comparative Examples 3 and 4, the driving voltage, current efficiency, light emission wavelength, and lifetime (T ₉₇ ) at a current density of 10 mA / cm ² were measured. Table 5 shows.

Table 5

	compound	Driving voltage (V)	Current efficiency (cd / A)	Light emitting peak (nm)	Life (hr, T 97 )
Example 37	LE-02	7.3	37.0	516	49
Example 38	LE-07	7.2	36.9	516	65
Example 39	LE-08	7.4	37.0	517	85
Example 40	LE-09	7.1	37.8	516	55
Example 41	LE-10	7.0	35.3	515	54
Example 42	LE-11	7.4	36.9	516	98
Example 43	LE-12	7.3	37.1	516	103
Example 44	LE-17	7.3	37.0	516	51
Example 45	LE-18	7.1	38.2	516	49
Example 46	LE-19	7.2	36.9	516	68
Example 47	LE-22	7.4	37.0	517	59
Example 48	LE-23	7.1	40.1	516	95
Example 49	LE-25	7.0	35.3	515	66
Example 50	LE-26	7.4	36.9	516	74
Example 51	LE-28	6.8	39.8	516	103
Comparative Example 3	-	7.2	36.8	516	45
Comparative Example 4	BCP	7.9	40.2	516	40
Life span measures the time when the luminance is 97%

Looking at Table 5, it can be seen that the organic electroluminescent devices of Examples 37 to 51 including the life improvement layer of the present invention are superior in current efficiency, driving voltage and lifetime than the organic electroluminescent devices of Comparative Examples 3 and 4. there was.

The present invention can provide an organic EL device having excellent driving voltage, luminous efficiency and lifetime by introducing a lifetime improving layer, an electron transporting layer, or an electron injection layer formed of a bipolar compound having specific physical properties into the organic EL device. have. In addition, as the organic electroluminescent device of the present invention is applied to a display panel, a display panel having improved performance and lifespan can be provided.

Claims (20)

1. anode;

   cathode; And

   At least one organic material layer selected from the group consisting of a hole injection layer, a hole transport layer, a light emitting layer, an electron transport layer and an electron injection layer is provided between the anode and the cathode,

   An organic electroluminescent device further comprising a Lifetime Enhancement Layer (LEL) between the light emitting layer and the electron transport layer.

   The lifespan improvement layer includes a bipolar compound having an electron attractor (EWG) having a high electron absorption and an electron donor (EDG) having a large electron donor,

   The bipolar compound is an organic electroluminescent device, characterized in that to satisfy the following conditions (a) to (d):

   (a) ionization potential [Ip (LEL)] is 5.5 eV or more,

   (b) E _HOMO- E _LUMO > 2.9 eV,

   (c) triplet energy is 2.3 eV or greater,

   (d) ΔEst <0.5 eV (ΔEst represents the difference between the singlet and triplet energies of the compound)
2. The method of claim 1,

   When the light emitting layer is blue fluorescence, green fluorescence, or red phosphorescence, the triplet energy of the bipolar compound included in the lifespan improvement layer is 2.3 eV or more.
3. The method of claim 1,

   When the light emitting layer is green phosphorescence, the triplet energy of the bipolar compound included in the life improvement layer is 2.5 eV or more, the ionization potential is 6.0 eV or more, characterized in that the organic electroluminescent device.
4. The method of claim 1,

   When the light emitting layer is blue phosphorescence, the triplet energy of the bipolar compound included in the life improvement layer is 2.7 eV or more, the ionization potential is 6.0 eV or more, characterized in that the organic electroluminescent device.
5. The method of claim 1,

   The electron mobility and the hole mobility of the bipolar compound included in the life improvement layer are at least 1 × 10 ⁻⁶ cm ² / V · s at room temperature, respectively.
6. The method of claim 1,

   The bipolar compound is an organic electroluminescent device, characterized in that it comprises one or more electron attracting (EWG) moiety represented by the following formula.

   

   Where

   A ₁ to A ₁₁ are the same as or different from each other, and each independently N or C (R), at least one is N, and when there are a plurality of C (R), they are the same or different from each other,

   R is each independently hydrogen, deuterium, halogen, cyano, nitro, amino, C ₁ -C ₄₀ alkyl, C ₂ -C ₄₀ alkenyl, C ₂ -C ₄₀ alkynyl, C ₃ ~ C ₄₀ cycloalkyl group, the number of nuclear atoms of 3 to 40 of the heterocycloalkyl of the alkyl group, C ₆ ~ C ₆₀ aryl group, the number of nuclear atoms of 5 to 60 heteroaryl group, C ₁ ~ alkyloxy group of C _40, C ₆ Aryloxy group of ~ C ₆₀ , C ₁ ~ C ₄₀ alkylsilyl group, C ₆ ~ C ₆₀ arylsilyl group, C ₁ ~ C ₄₀ alkyl boron group, C ₆ ~ C ₆₀ aryl boron group, C ₁ ~ C ₄₀ of the phosphine group, C ₁ ~ C ₄₀ phosphine oxide group, and a C ₆ ~, or selected from the group consisting of an aryl amine of the C ₆₀ of the adjacent group to form a condensed ring,

   Alkyl group, alkenyl group, alkynyl group, cycloalkyl group, heterocycloalkyl group, aryl group, heteroaryl group, alkyloxy group, aryloxy group, alkylsilyl group, arylsilyl group, alkyl boron group, aryl boron group, force of the above R The pin group, the phosphine oxide group and the arylamine group are each independently deuterium, halogen group, cyano group, nitro group, amino group, C ₁ ~ C ₄₀ alkyl group, C ₂ ~ C ₄₀ alkenyl group, C ₂ ~ C ₄₀ alkynyl group, C ₃ ~ C ₄₀ cycloalkyl group, nuclear atoms, 3 to 40 heterocycloalkyl group, C ₆ ~ C ₄₀ aryl group, nuclear atoms aryl of from 5 to 40 heteroaryl group, a C ₁ ~ C ₄₀ alkyl Oxy group, C ₆ ~ C ₆₀ aryloxy group, C ₁ ~ C ₄₀ alkylsilyl group, C ₆ ~ C ₆₀ arylsilyl group, C ₁ ~ C ₄₀ alkyl boron group, C ₆ ~ C ₆₀ aryl boron group, C ₁ ~ C ₄₀ of the phosphine group, C ₁ ~ C ₄₀ phosphine oxide group, and a C ₆ ~ by at least one member selected from the group consisting of an aryl amine of the C ₆₀ substituted or unsubstituted of .
7. The method of claim 6,

   The bipolar compound is an organic electroluminescent device, characterized in that it comprises one or more electron attracting (EWG) moiety represented by the following formula.

   
8. The method of claim 1,

   The bipolar compound is an organic electroluminescent device comprising an electron donor (EDG) moiety represented by the formula (1).

   [Formula 1]

   

   In Chemical Formula 1,

   X ₁ is selected from the group consisting of O, S, Se, N (Ar ₁ ), C (Ar ₂ ) (Ar ₃ ) and Si (Ar ₄ ) (Ar ₅ ),

   Y ₁ to Y ₄ are the same as or different from each other, and each independently N or C (R ₁ ), wherein a plurality of R ₁ are the same or different from each other, and they may form a condensed ring with an adjacent group,

   X ₂ and X ₃ are the same as or different from each other, and each independently N or C (R ₂ ), wherein a plurality of R ₂ are the same or different from each other, and they may form a condensed ring with an adjacent group,

   R ₁ to R ₂ and Ar ₁ to Ar ₅ are the same as or different from each other, and each independently, hydrogen, deuterium, halogen, cyano group, nitro group, amino group, C ₁ ~ C ₄₀ alkyl group, C ₂ ~ C ₄₀ alkenyl group, C ₂ to C ₄₀ alkynyl group, C ₃ to C ₄₀ cycloalkyl group, nuclear atom 3 to 40 heterocycloalkyl group, C ₆ to C ₆₀ aryl group, nuclear atom 5 to 60 Heteroaryl group, C ₁ ~ C ₄₀ alkyloxy group, C ₆ ~ C ₆₀ aryloxy group, C ₁ ~ C ₄₀ alkylsilyl group, C ₆ ~ C ₆₀ arylsilyl group, C ₁ ~ C ₄₀ is selected from the group consisting of alkyl boron group, C ₆ ~ C ₆₀ aryl group of boron, C ₁ ~ C ₄₀ of the phosphine group, C ₁ ~ C ₄₀ phosphine oxide group, and a C ₆ ~ C ₆₀ aryl group of an amine of,

   The alkyl group, alkenyl group, alkynyl group, cycloalkyl group, heterocycloalkyl group, aryl group, heteroaryl group, alkyloxy group, aryloxy group, alkylsilyl group, arylsilyl group of R ₁ to R ₂ and Ar ₁ to Ar ₅ , Alkyl boron group, aryl boron group, phosphine group, phosphine oxide group and arylamine group are each independently deuterium, halogen group, cyano group, nitro group, amino group, C ₁ ~ C ₄₀ alkyl group, C ₂ ~ C ₄₀ Alkenyl group, C ₂ to C ₄₀ alkynyl group, C ₃ to C ₄₀ cycloalkyl group, nuclear atom 3 to 40 heterocycloalkyl group, C ₆ to C ₄₀ aryl group, nuclear atom 5 to 40 hetero aryl group, C ₁ ~ C ₄₀ of the alkyloxy group, C ₆ ~ C ₆₀ of the aryloxy group, C ₁ ~ C ₄₀ alkyl silyl group, the group C ₆ ~ C ₆₀ aryl silyl, C ₁ ~ C ₄₀ alkyl boron group, C ₆ ~ C ₆₀ aryl group of boron, C ₁ ~ C ₄₀ of the phosphine group, C ₁ ~ C ₄₀ of the phosphine oxide group, and a C ₆ ~ at least one selected from the group consisting of C ₆₀ arylamine Substituted or unsubstituted.
9. The method of claim 8,

   The compound represented by Chemical Formula 1 is represented by any one of the following A-1 to A-24.

   

   Wherein R ₂ , Y ₁ to Y ₄ and Ar ₁ to Ar ₅ are the same as defined in claim 8.
10. The method of claim 1,

    The bipolar compound includes an organic electroluminescent device comprising a moiety in which Formula 1 and Formula 2, or Formula 1 and Formula 3 combine with each other to form a condensed ring.

    [Formula 1]

    

    In Chemical Formula 1,

    X ₁ is selected from the group consisting of O, S, Se, N (Ar ₁ ), C (Ar ₂ ) (Ar ₃ ) and Si (Ar ₄ ) (Ar ₅ ),

    Y ₁ to Y ₄ are the same as or different from each other, and each independently N or C (R ₁ ), wherein _one of Y ₁ and Y ₂ , Y ₂ and Y ₃ or Y ₃ and Y ₄ is represented by the following Formula 2 or Formula Form a condensed ring with 3 (wherein a plurality of R ₁ are the same or different from each other),

    X ₂ and X ₃ are the same as or different from each other, and each independently N or C (R ₂ ), wherein a plurality of R ₂ are the same or different from each other,

    [Formula 2]

    

    [Formula 3]

    

    In Chemical Formulas 2 and 3,

    Y ₅ to Y ₁₄ are the same as or different from each other, and each independently N or C (R ₃ ), wherein a plurality of R ₃ are the same as or different from each other, and may form a condensed ring with Formula 1,

    X ₄ is the same as X ₁ , wherein a plurality of Ar ₁ to Ar ₅ are the same as or different from each other,

    The plurality of R ₃ non-forming condensed rings are the same or different from each other, and each independently hydrogen, deuterium, a halogen group, a cyano group, a nitro group, an amino group, an alkyl group of C ₁ to C ₄₀ , and a C ₂ to C ₄₀ alkenyl group, C ₂ to C ₄₀ alkynyl group, C ₃ to C ₄₀ cycloalkyl group, nuclear atom 3 to 40 heterocycloalkyl group, C ₆ to C ₆₀ aryl group, nuclear atom 5 to 60 Heteroaryl group, C ₁ ~ C ₄₀ alkyloxy group, C ₆ ~ C ₆₀ aryloxy group, C ₁ ~ C ₄₀ alkylsilyl group, C ₆ ~ C ₆₀ arylsilyl group, C ₁ ~ C ₄₀ alkyl boron group, C ₆ ~ C ₆₀ aryl boron group, C ₁ ~ C ₄₀ of the phosphine group, C ₁ ~ C ₄₀ of the phosphine oxide group, and a C ₆ ~ C ₆₀ of is selected from the group consisting of an aryl amine ,

    Alkyl group of the R _3, an alkenyl group, an alkynyl group, a cycloalkyl group, a heterocycloalkyl group, an aryl group, a heteroaryl group, an alkyloxy group, an aryloxy group, an alkylsilyl group, an arylsilyl group, an alkyl boron group, an aryl boron group, The phosphine group, the phosphine oxide group and the arylamine group are each independently deuterium, halogen group, cyano group, nitro group, amino group, C ₁ ~ C ₄₀ alkyl group, C ₂ ~ C ₄₀ alkenyl group, C ₂ ~ C ₄₀ Alkynyl group, C ₃ to C ₄₀ cycloalkyl group, nuclear atom 3 to 40 heterocycloalkyl group, C ₆ to C ₄₀ aryl group, nuclear atom 5 to 40 heteroaryl group, C ₁ to C ₄₀ Alkyloxy group, C ₆ ~ C ₆₀ aryloxy group, C ₁ ~ C ₄₀ alkylsilyl group, C ₆ ~ C ₆₀ arylsilyl group, C ₁ ~ C ₄₀ alkyl boron group, C ₆ ~ C ₆₀ aryl boron group, C ₁ ~ C ₄₀ of the phosphine group, C ₁ ~ C ₄₀ phosphine oxide group, and a C ₆ ~ substituted by one or more selected from the group consisting of C ₆₀ aryl amine, or unsubstituted of The.
11. The method of claim 10,

    The bipolar compound is an organic electroluminescent device, characterized in that it comprises any one of the electron donor (EDG) moiety represented by the formula (1a) to formula (1n).

    [Formula 1a]

    

    [Formula 1b]

    

    [Formula 1c]

    

    [Formula 1d]

    

    [Formula 1e]

    

    [Formula 1f]

    

    [Formula 1g]

    

    [Formula 1h]

    

    Formula 1i]

    

    [Formula 1j]

    

    [Formula 1k]

    

    [Formula 1l]

    

    [Formula 1m]

    

    [Formula 1n]

    

    In Chemical Formulas 1a to 1n,

    X ₁ to X ₄ and Y ₁ to Y ₁₄ are as defined in claim 10.
12. The method of claim 1,

    The bipolar compound is an organic electroluminescent device comprising an electron donor (EDG) moiety represented by the formula (4).

    [Formula 4]

    

    In Chemical Formula 4,

    L ₁ to L ₃ are the same as or different from each other, and each independently selected from the group consisting of a single bond, a C ₆ to C ₆₀ arylene group, and a heteroarylene group having 5 to 60 nuclear atoms,

    Ar ₆ to Ar ₈ are the same as or different from each other, and are each independently selected from hydrogen, deuterium, an aryl group having ₆ to ₄₀ carbon atoms and a heteroaryl group having 5 to 40 nuclear atoms, provided that Ar ₆ to Ar ₈ are all Except in the same case,

    R ₄ to R ₆ are the same or different and are each independently hydrogen, deuterium, halogen group, cyano group, nitro group, amino group, C ₁ ~ alkenyl group of the C ₄₀ alkyl group, C ₂ ~ C ₄₀ of, C ₂ ~ C ₄₀ alkynyl group, C ₃ to C ₄₀ cycloalkyl group, nuclear atom 3 to 40 heterocycloalkyl group, C ₆ to C ₆₀ aryl group, nuclear atom 5 to 60 heteroaryl group, C ₁ to C ₄₀ alkyloxy group, C ₆ ~ C ₆₀ aryloxy group, C ₁ ~ C ₄₀ alkylsilyl group, C ₆ ~ C ₆₀ arylsilyl group, C ₁ ~ C ₄₀ alkyl boron group, C ₆ ~ C a group of the arylboronic _60, is selected from the group consisting of C ₁ ~ C ₄₀ of the phosphine group, C ₁ ~ C ₄₀ phosphine oxide group, and a C ₆ ~ C ₆₀ aryl group of an amine of,

    a to c are each independently an integer of 0 to 3,

    The arylene group, heteroarylene group, alkyl group, alkenyl group, alkynyl group, cycloalkyl group, heterocycloalkyl group, aryl group, heteroaryl group, alkyl jade of L ₁ to L ₃ , R ₄ to R ₆ and Ar ₆ to Ar ₈ The time period, aryloxy group, alkylsilyl group, arylsilyl group, alkyl boron group, aryl boron group, phosphine group, phosphine oxide group and arylamine group are each independently deuterium, halogen group, cyano group, nitro group, amino group, C ₁ ~ C ₄₀ Alkyl group, C ₂ ~ C ₄₀ Alkenyl group, C ₂ ~ C ₄₀ Alkynyl group, C ₃ ~ C ₄₀ Cycloalkyl group, C ₃ ~ 40 Heterocycloalkyl group, C ₆ ~ C ₄₀ aryl group, nuclear atom 5 to 40 heteroaryl group, C ₁ ~ C ₄₀ alkyloxy group, C ₆ ~ C ₆₀ aryloxy group, C ₁ ~ C ₄₀ alkylsilyl group, C ₆ ~ C ₆₀ arylsilyl group, a alkyl boronic of _{C 1 ~ C 40, C 6} ~ C group ₆₀ arylboronic of, C ₁ ~ C ₄₀ of the phosphine group, C ₁ ~ phosphine oxide of a C ₄₀ group, and a C ₆ ~ C ₆₀ of Arya Substituted or unsubstituted with one or more selected from the group consisting of min groups.
13. The method of claim 1,

    The material of the electron transport layer and the material of the life improvement layer is the same.
14. The method of claim 1,

    The material of the electron injection layer and the material of the life improvement layer is the same.
15. The method of claim 1,

    The electron injection layer or the electron transport layer is an organic electroluminescent device, characterized in that the alkali metal complex is provided by co-deposition.
16. The method of claim 1,

    And an organic film layer blocking electrons and excitons between the hole transport layer and the light emitting layer.
17. The method of claim 1,

    The light emitting layer comprises a host material and a dopant material, the organic electroluminescent device, characterized in that it comprises the dopant in the range of 0.1% to 30% by weight.
18. The method of claim 1,

    Organic light emitting device, characterized in that to achieve a mixed color when a voltage, current is applied by sequentially stacking a plurality of light emitting layer between the hole transport layer and the electron transport layer.
19. The method of claim 1,

    Organic electroluminescence characterized in that a plurality of light emitting layers of a single material is laminated between the hole transport layer and the electron transport layer, or a plurality of light emitting layers of different materials are provided in series to implement mixed colors or increase efficiency when voltage and current are applied. device.
20. The method of claim 1,

    When applying voltage, current, or both, the organic EL device characterized in that the half-life (Lifetime) of the initial brightness increases while maintaining the maximum luminous efficiency.

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