Organic electroluminescence element

Abstract

The present invention provides an organic electroluminescence device that has at least two electron transport layers, a first layer that is disposed adjacent to an emitting layer and made of a single compound, and a second layer that is disposed adjacent to a negative electrode and made of at least two kinds of organic compounds, and that simultaneously exhibits a low driving voltage and high luminous efficiency.

Description

[Technical field]

[0001] The present invention relates to an organic electroluminescence device having at least two electron transport layers, a first layer disposed adjacent to an emitting layer and composed of unit compounds, and a second layer disposed adjacent to a negative electrode and composed of at least two kinds of organic compounds, and having improved properties such as low driving voltage and high luminous efficiency. [Background technology]

[0002] Following the blue electroluminescence using anthracene single crystal in 1965, research on organic electroluminescent (EL) elements (hereinafter sometimes abbreviated as "organic EL elements") continued, and in 1987, Tang presented an organic EL element with a two-layer laminate structure consisting of a hole layer (NPB) and an emission layer (Alq3). After that, in order to realize the high efficiency and long life characteristics required for commercialization of organic EL elements, a multi-layer laminate structure was proposed in which each layer has its own characteristic and specialized functions, such as an organic layer that injects and transports holes, an organic layer that injects and transports electrons, and an organic layer that induces electroluminescence by the combination of holes and electrons. With the introduction of the multi-layer laminate structure, the performance of organic EL elements was improved to characteristics suitable for commercialization, and their range of application is expanding, starting with car-mounted radio display products in 1977, to portable information display devices and display elements for televisions.

[0003] As displays become larger and more highly detailed, organic EL elements are faced with the challenge of improving their efficiency and extending their lifespan. In particular, when higher resolution is achieved by forming more pixels in the same area, the light-emitting area of ​​the organic EL pixel is reduced, which shortens the lifespan. This is said to be the most important challenge that organic EL elements must overcome.

[0004] In an organic EL element, when a current or voltage is applied to both electrodes, holes are injected from the anode into the organic layer, and electrons are injected from the cathode into the organic layer. When the injected holes and electrons meet, excitons are formed, and when these excitons return to the ground state, they emit light. Depending on the type of electron spin of the excitons formed, organic EL elements are classified into fluorescent EL elements, in which singlet excitons contribute to light emission, and phosphorescent EL elements, in which triplet excitons contribute to light emission.

[0005] The electron spin of excitons formed by the recombination of electrons and holes is generated as singlet excitons and triplet excitons in a ratio of 25%:75%. Fluorescent EL elements that emit light from singlet excitons theoretically cannot exceed an internal quantum efficiency of 25% depending on the generation ratio, and external quantum efficiency is said to be limited to 5%. In phosphorescent EL elements that emit light from triplet excitons, when a metal complex compound containing heavy atoms of transition metals such as Ir and Pt is used as a phosphorescent dopant, the luminous efficiency can be improved up to four times compared to fluorescence.

[0006] In addition, conventional organic EL elements use an electron transport layer doped with a lithium compound to facilitate the injection of electrons from the negative electrode. Since such an electron transport layer contains metal, it is fundamentally prone to oxidation, which leads to a shortened lifespan of the organic EL element. Summary of the Invention [Problem to be solved by the invention]

[0007] The present invention has been devised to solve the above-mentioned problems, and an object of the present invention is to provide an organic EL device which has at least two electron transport layers composed only of organic compounds, with the first layer being composed of a single compound in a region of the electron transport layer adjacent to the light-emitting layer, and the second layer being composed of a mixture of at least two organic compounds in a region of the electron transport layer adjacent to the negative electrode, thereby simultaneously exhibiting high efficiency, low voltage, and long life characteristics.

[0008] Other objects and advantages of the present invention will become more apparent from the following detailed description and claims. [Means for solving the problem]

[0009] In order to solve the above-mentioned technical problems, the present invention provides an organic electroluminescence device comprising: a positive electrode; a negative electrode disposed opposite to the positive electrode; a light-emitting layer disposed between the positive electrode and the negative electrode; and an electron transport layer disposed between the light-emitting layer and the negative electrode; wherein the electron transport layer has at least two layers including a first layer and a second layer, wherein of the at least two layers, the first layer in contact with the light-emitting layer is composed of a first compound, and of the at least two layers, the second layer disposed adjacent to the negative electrode is composed of at least two organic compounds including a second compound and a third compound, and any one of the second compound and the third compound is the same as or different from the first compound.

[0010] In one embodiment of the present invention, the electron transport layer including at least two layers does not contain metal and is made of an organic material.

[0011] In one embodiment of the present invention, the HOMO energy level of the first layer is greater than or equal to 5.4 eV.

[0012] In one embodiment of the present invention, the band gap energy of the first layer is 2.7 eV or more.

[0013] In one embodiment of the present invention, the triplet energy of the first layer is 1.5 eV or more.

[0014] In one embodiment of the present invention, the singlet energy of the first layer is greater than or equal to 2.5 eV.

[0015] In one embodiment of the present invention, the HOMO energy level of the second layer is greater than or equal to 5.6 eV.

[0016] In one embodiment of the present invention, the band gap energy of the second layer is 2.5 eV or more.

[0017] In one embodiment of the present invention, the triplet energy of the second layer is 1.7 eV or more. In one embodiment of the present invention, the vector sum (D) of the first and second layer coupling moments is 3.336×10 -31 C·m or more. (The vector sum (D) of the bond moments is obtained from the results of geometry optimization calculations based on the density function calculation B3LYP / 6-31G*.)

[0018] In one embodiment of the present invention, the second layer is a co-deposition of a second compound and a third compound which are different from each other.

[0019] In one embodiment of the present invention, the first compound, the second compound, and the third compound are different substances.

[0020] In one embodiment of the present invention, the vector sum (D2) of the bond moments of any one of the second and third compounds constituting the second layer is greater than the vector sum (D1) of the bond moments of the first compound.

[0021] In one embodiment of the present invention, one of the second compound and the third compound is the same material as the first compound, and the other is a material different from the first compound.

[0022] In one embodiment of the present invention, the vector sum (D2) of the bond moments of the second and third compounds, which are different from the first compound, is greater than the vector sum (D1) of the bond moments of the first compound.

[0023] In one embodiment of the present invention, the second compound and the third compound have a higher content of a substance different from the first compound than a content of a substance the same as the first compound.

[0024] In one embodiment of the present invention, the mixing ratio of the second compound to the third compound is 50:50 to 90:10 by weight based on the total weight of the second layer.

[0025] In one embodiment of the present invention, the device further comprises a hole transport region disposed between the anode and the light emitting layer, the hole transport region comprising at least one of a hole injection layer and a hole transport layer.

[0026] In one embodiment of the present invention, the organic electroluminescent device comprises a plurality of light-emitting stacks, each of which includes at least one light-emitting layer. Effect of the Invention

[0027] According to one embodiment of the present invention, at least two electron transport layers are formed from only organic compounds. In the electron transport layer, a first layer made from a single compound is disposed in one region adjacent to the light-emitting layer, and a second layer made from at least two organic mixtures is disposed in another region adjacent to the negative electrode. This allows the organic electroluminescence element to exhibit low voltage, high efficiency, and long life characteristics compared to an organic electroluminescence element employing an electron transport layer containing a metal.

[0028] The effects of the present invention are not limited to the above-mentioned contents, and more various effects are included in the present specification. [Brief description of the drawings]

[0029] [Figure 1] 1 is a cross-sectional view showing a structure of an organic electroluminescence element according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0030] The advantages and features of the present invention, as well as the methods for achieving them, will be apparent from the embodiments described in detail with reference to the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, and can be modified and embodied in various different forms. However, the embodiments described below are provided for the purpose of complete disclosure of the present invention, and for those skilled in the art to which the present invention pertains to fully understand the scope of the invention, and the present invention should be defined by the scope of the claims. Therefore, in some embodiments, detailed descriptions of well-known processes and steps, well-known device structures, and well-known techniques will be omitted to avoid ambiguous interpretation of the present invention. The same reference numerals refer to the same components throughout this specification.

[0031] Unless otherwise defined, all terms (including technical and scientific terms) used in this specification have the meaning commonly understood by those having ordinary knowledge in the technical field to which the present invention belongs. In addition, terms defined in commonly used dictionaries are not interpreted ideally or excessively unless otherwise specified.

[0032] In addition, throughout this specification, when a part "includes" a certain component, it does not mean that the part excludes other components, but that the part may further include other components, unless otherwise specified. In addition, throughout this specification, "above" or "on" includes not only the case where the part is located above or below the target part, but also the case where there is another part in between, and does not necessarily mean that the part is located above the direction of gravity. In addition, in this specification, terms such as "first" and "second" are used to distinguish between components, without indicating any order or importance.

[0033] <Organic electroluminescence element> FIG. 1 is a cross-sectional view illustrating a schematic structure of an organic electroluminescence element 100 according to a first embodiment of the present invention.

[0034] As shown in FIG. 1, an organic electroluminescence device 100 according to an embodiment of the present invention includes a positive electrode 10; a negative electrode 20; an emitting layer 40 located between the positive electrode 10 and the negative electrode 20; a hole transport region 30 located between the positive electrode 10 and the emitting layer 40; and an electron transport region 50 located between the emitting layer 40 and the negative electrode 20. The electron transport region 50 includes at least two electron transport layers 51, and has a structure in which a first layer 51a made of a first compound is disposed in one region of the electron transport layer 51 in contact with the emitting layer 40, and a second layer 51b made of at least two organic mixtures is disposed in another region of the electron transport layer 51 disposed adjacent to the negative electrode 20.

[0035] Hereinafter, preferred embodiments of the organic electroluminescence element according to the present invention will be described with reference to the accompanying drawings. However, the embodiments of the present invention can be implemented in various modifications, and the scope of the present invention is not limited to the embodiments described below.

[0036] positive electrode In the organic electroluminescence device 100 according to the present invention, the positive electrode 10 serves to inject holes into the organic layer A.

[0037] The material constituting the positive electrode 10 is not particularly limited, and any material known in the art can be used. For example, metals such as vanadium, chromium, copper, zinc, and gold and their alloys; 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 SnO2:Sb; conductive polymers such as polythiophene, poly(3-methylthiophene), poly[3,4-(ethylene-1,2-dioxy)thiophene] (PEDT), polypyrrole, and polyaniline; carbon black; and the like can be used, but are not limited thereto.

[0038] The method for producing the positive electrode 10 is not particularly limited and may be a method commonly used in the art, such as coating a positive electrode material onto a substrate made of a silicon wafer, quartz, a glass plate, a metal plate, or a plastic film.

[0039] negative electrode In the organic electroluminescence device 100 according to the present invention, the negative electrode 20 serves to inject electrons into the organic layer A.

[0040] The material constituting the negative electrode 20 is not particularly limited, and any material known in the art can be used. Examples include, but are not limited to, metals such as magnesium, calcium, sodium, potassium, titanium, indium, yttrium, lithium, gadolinium, aluminum, silver, tin, and lead, and alloys thereof; and materials having a multilayer structure such as LiF / Al and LiO2 / Al.

[0041] The method for producing the negative electrode 20 is not particularly limited, and the negative electrode 20 can be produced by a method commonly used in the art.

[0042] organic layer As the organic layer A contained in the organic electroluminescence device according to the present invention, any organic layer commonly used in organic EL devices can be used without limitation, and as an example, it may contain one or more selected from the group consisting of a hole transport region 30, a light emitting layer 40, and an electron transport region 50. In this case, it is preferable to contain all of the above-mentioned organic layers in consideration of the characteristics of the organic electroluminescence device.

[0043] Hole Transport Region The hole transport region 30 included in the organic layer A according to the present invention plays a role in moving holes injected from the positive electrode 10 to the light emitting layer 40. Such a hole transport region 30 may include one or more layers selected from the group consisting of a hole injection layer 31 and a hole transport layer 32. In this case, it is preferable to include both the hole injection layer 31 and the hole transport layer 32 described above in consideration of the characteristics of the organic electroluminescence device.

[0044] The materials constituting the hole injection layer 31 and the hole transport layer 32 are not particularly limited as long as they have a low hole injection barrier and high hole mobility, and any hole injection layer / transport layer materials used in the relevant technical field can be used without limitation. In this case, the materials constituting the hole injection layer 31 and the hole transport layer 32 may be the same or different from each other.

[0045] The hole injection material may be any hole injection material known in the art. Examples of hole injection materials that may be used include phthalocyanine compounds such as copper phthalocyanine; DNTPD (N,N'-diphenyl-N,N'-bis-[4-(phenyl-m-tolyl-amino)-phenyl]-biphenyl-4,4'-diamine), m-MTDATA (4,4',4"-tris(3-methylphenylphenylamino)triphenylamine), TDATA (4,4',4"-tris(N,N-diphenylamino)triphenylamine), 2TNATA (4,4',4"-tris{N, Examples of the polyaniline / poly(4-styrenesulfonate) include, but are not limited to, polyaniline / dodecylbenzenesulfonic acid (PANI / DBSA), polyaniline / camphorsulfonic acid (PANI / CSA), and polyaniline / PSS (polyaniline) / poly(4-styrenesulfonate). These may be used alone or in combination of two or more.

[0046] In addition, as the hole transport material, any hole transport material known in the art can be used without limitation. Examples of usable hole transport materials include, but are not limited to, carbazole derivatives such as phenylcarbazole and polyvinylcarbazole, fluorene derivatives, triphenylamine derivatives such as TPD (N,N'-bis(3-methylphenyl)-N,N'-diphenyl-[1,1-biphenyl]-4,4'-diamine) and TCTA (4,4'-4"-tris(N-carbazolyl)triphenylamine), NPB (N,N'-di(1-naphthyl)-N,N'-diphenylbenzidine), and TAPC (4,4'-cyclohexylidenebis[N,N-bis(4-methylphenyl)benzeneamine]). These may be used alone or in combination of two or more.

[0047] The hole transport region 30 can be manufactured by a conventional method in the art, such as, but not limited to, vacuum deposition, spin coating, casting, Langmuir-Blodgett (LB) method, inkjet printing, laser printing, and laser induced thermal imaging (LITI).

[0048] Emitting layer The light-emitting layer 40 included in the organic layer A of the present invention is a layer where holes and electrons meet to form excitons, and the color of the light emitted by the organic electroluminescence element changes depending on the material that constitutes the light-emitting layer 40.

[0049] The light-emitting layer 40 includes a host and a dopant, and the mixing ratio between them may be appropriately adjusted within a range known in the art. As an example, the light-emitting layer 40 may include 70 to 99.9 parts by weight of the host and 0.1 to 30 parts by weight of the dopant, based on the total weight of the light-emitting layer 40. More specifically, when the light-emitting layer 40 is blue fluorescent, green fluorescent, or red fluorescent, it may include 80 to 99.9 parts by weight of the host and 0.1 to 20 parts by weight of the dopant. When the light-emitting layer 40 is blue fluorescent, green fluorescent, or red phosphorescent, it may include 70 to 99 parts by weight of the host and 1 to 30 parts by weight of the dopant.

[0050] The host contained in the light-emitting layer 40 of the present invention is not particularly limited as long as it is known in the technical field, and examples thereof include, but are not limited to, alkali metal complex compounds; alkaline earth metal complex compounds; and fused aromatic ring derivatives.

[0051] More specifically, as the host material, it is preferable to use an aluminum complex compound, a beryllium complex compound, an anthracene derivative, a pyrene derivative, a triphenylene derivative, a carbazole derivative, a dibenzofuran derivative, a dibenzothiophene derivative, or a combination of one or more of these, which can extend the luminous efficiency and life of the organic electroluminescence element.

[0052] Furthermore, the dopant contained in the light-emitting layer 40 of the present invention is not particularly limited as long as it is known in the art, and examples thereof include, but are not limited to, anthracene derivatives, pyrene derivatives, arylamine derivatives, and metal complex compounds containing iridium (Ir) or platinum (Pt).

[0053] The dopants are classified into red, green, and blue dopants, and any red, green, and blue dopants known in the art may be used without any particular limitation.

[0054] Specific examples of red dopants include, but are not limited to, PtOEP (Pt(II) octaethylporphine), Ir(piq)3 (tris(2-phenylisoquinoline)iridium, Btp2Ir(acac) (bis(2-(2'-benzothienyl)-pyridinato-N,C3')iridium(acetylacetonate), or a mixture of two or more of these.

[0055] Examples of the green dopant include, but are not limited to, Ir(ppy)3 (tris(2-phenylpyridine)iridium, Ir(ppy)2(acac) (bis(2-phenylpyridine)(acetylacetonato)iridium(III)), Ir(mppy)3 (tris(2-(4-tolyl)phenylpyridine)iridium, C545T (10-(2-benzothiazolyl)-1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H,11H-[1]benzopyrano[6,7,8-ij]-quinolizin-11-one, or a mixture of two or more of these.

[0056] Examples of the blue dopant include, but are not limited to, F2Irpic (bis[3,5-difluoro-2-(2-pyridyl)phenyl](picolinato)iridium(III)), (F2ppy)2Ir(tmd), Ir(dfppz)3, DPVBi (4,4'-bis(2,2'-diphenylethen-1-yl)biphenyl, DPAVBi (4,4'-bis[4-(diphenylamino)styryl]biphenyl, TBPe (2,5,8,11-tetra-tert-butylperylene), or a mixture of two or more of these.

[0057] The light-emitting layer 40 according to the present invention may be a red light-emitting layer containing a red phosphorescent material, a green light-emitting layer containing a green phosphorescent material, or a blue light-emitting layer containing a blue phosphorescent material or a blue fluorescent material, and is preferably a light-emitting layer containing a blue fluorescent material.

[0058] The light-emitting layer 40 may be a single layer made of one material, a single layer made of a plurality of different materials, or a plurality of layers made of two or more different materials. When the light-emitting layer 40 is made of a plurality of layers, the organic electroluminescent element can emit light of various colors. Specifically, the present invention can provide an organic electroluminescent element having a plurality of light-emitting layers made of different materials in series and exhibiting a mixed color. In addition, when the light-emitting layer is made of a plurality of light-emitting layers, the driving voltage of the element increases, but the current value in the organic electroluminescent element becomes constant, and an organic electroluminescent element with improved luminous efficiency can be provided in proportion to the number of light-emitting layers.

[0059] Although not shown, the organic electroluminescent device 100 may include a plurality of light-emitting stacks (not shown) each including at least one light-emitting layer.

[0060] The plurality of light-emitting layers included in such a light-emitting stack may be light-emitting layers that emit light of different colors or light-emitting layers that emit light of the same color. That is, the emission color changes depending on the material that constitutes the light-emitting layer. As an example, the plurality of light-emitting stacks include materials that emit blue, green, red, yellow, white, etc., and are formed using phosphorescent or fluorescent materials. In this case, the colors exhibited by each light-emitting layer may be complementary to each other. In addition, colors may be selected as a combination of colors that emit white. Each of such light-emitting layers may include a phosphorescent or fluorescent dopant that corresponds to the selected color.

[0061] Although not shown, the organic electroluminescent device 100 may further include a charge generation layer (not shown) disposed between and connecting adjacent ones of the plurality of light-emitting stacks.

[0062] A charge generation layer (CGL) refers to a layer that separates adjacently arranged light emitting stacks without directly contacting two electrodes (e.g., anode and cathode) in an organic light emitting device having a plurality of light emitting stacks. Such a charge generation layer is disposed between two adjacent light emitting stacks, and serves as a cathode by generating electrons for one light emitting stack and serves as an anode by generating holes for the other light emitting stack. As such a charge generation layer, any charge generation layer (CGL) material known in the art can be used without limitation. In addition, the charge generation layer material may be doped with a conventional n-type material and / or p-type material known in the art.

[0063] electron transport area In the organic electroluminescence device 100 according to the present invention, the electron transport region 50 included in the organic layer A plays a role in transporting electrons injected from the negative electrode 20 to the light emitting layer 40 .

[0064] Such an electron transport region 50 includes at least two or more multi-layer electron transport layers 51, or the multi-layer electron transport layer 51 and the electron injection layer 52. If necessary, it may further include an electron transport auxiliary layer (not shown).

[0065] Conventionally, in order to improve the electron injection characteristics of the electron transport layer 51, a layer containing a lithium compound such as Li, LiF, or LiQ may be formed together with the electron transport layer material. The electron transport layer doped with such a lithium compound is prone to oxidation over time because it contains metal, which is highly likely to fundamentally cause a reduction in the life span of the organic electroluminescence device.

[0066] The present invention aims to fundamentally solve the problems of metal-containing electron transport layers by providing an electron transport layer composed only of organic compounds instead of lithium compounds, and at the same time, to achieve low voltage, high efficiency, and long life characteristics superior to those of conventional organic electroluminescence devices using such metal-containing electron transport layers by forming an electron transport layer having a predetermined multi-layer structure using organic materials with high electron injection ability.

[0067] Specifically, in the present invention, the electron transport layer 51 is configured to have at least two layers that do not contain metal. In the electron transport layer 51, a first layer 51a composed of a single compound (e.g., a first compound) is disposed in one region adjacent to the light-emitting layer 40, and a second layer 51b composed of at least two kinds of organic mixtures (e.g., second and third compounds) is disposed in another region adjacent to the negative electrode 20.

[0068] Here, the single compound (e.g., the first compound) constituting the first layer 51a and one of the organic mixtures (e.g., the second and third compounds) constituting the second layer 51b may be the same or different from each other.

[0069] In the electron transport layer 51 according to the present invention, the first layer 51a is a single layer made of one organic compound that maintains a stable structure during electron transport. The first layer 51a blocks holes from the light-emitting layer, increases the density of excitons in the light-emitting layer, and improves the efficiency of the device. The first layer 51a also plays a role in increasing the mobility of electrons transferred from the second layer 51b so that they can be quickly transported to the light-emitting layer 40.

[0070] The first layer 51a is composed of a specific single organic compound, which not only improves the performance of the element as described above, but also exhibits low driving voltage and high efficiency characteristics, and therefore can further satisfy at least one of the physical properties described below.

[0071] In one specific example, the HOMO (Highest Occupied Molecular Orbital) energy level of the first layer 51a is 5.4 eV or more, preferably 5.4 to 6.5 eV, and more preferably 5.4 to 6.3 eV. Within such a range of HOMO energy values, it is possible to prevent the diffusion or movement of holes transferred to the light-emitting layer 40 to other electron transport regions. This increases the probability of recombination between holes and electrons in the light-emitting layer 40, thereby improving the luminous efficiency of the organic electroluminescence device. In addition, it is possible to solve the irreversible decomposition reaction caused by oxidation when holes diffuse or move beyond the light-emitting layer 40 to other layers, and the resulting decrease in the life of the organic electroluminescence device, thereby improving the life characteristics of the device. Here, the HOMO energy level may mean the magnitude of the absolute value of the HOMO.

[0072] In another embodiment, the band gap energy (E bg ) is 2.7 eV or more, preferably 2.7 to 4.0 eV, and more preferably 2.7 to 3.8 eV. When the first layer 51a has the above-mentioned band gap energy, high efficiency characteristics can be exhibited.

[0073] In another specific example, the triplet energy (T1) of the first layer 51a is 1.5 eV or more, preferably 1.5 to 3.3 eV, and more preferably 1.6 to 3.3 eV, which can prevent excitons from moving to other layers and significantly improve the efficiency of the organic electroluminescence element.

[0074] In another specific example, the singlet energy (S1) of the first layer 51a is 2.5 eV or more, preferably 2.5 to 3.5 eV, and more preferably 2.7 to 3.5 eV. The diffusion of singlet excitons to adjacent interfaces and / or other layers, or the emission phenomenon at the interfaces, is prevented, and the singlet excitons are efficiently bound. This increases the amount of excitons, and improves the luminous efficiency of the organic electroluminescence element. As a result, the spectral color mixing of the organic electroluminescence element is prevented, the stability is improved, and the efficiency and life characteristics of the organic electroluminescence element are improved.

[0075] In the electron transport layer 51 according to the present invention, the second layer 51b is a single layer formed by mixing two or more specific organic substances (e.g., second and third compounds) having high electron injection ability instead of a metal, for example, a lithium compound. In particular, in the present invention, the organic mixture constituting the second layer 51b contains an organic substance having a life-improving effect (e.g., second compound) and an organic substance having an efficiency-improving effect (e.g., third compound) in a predetermined mixture ratio, thereby improving both the efficiency and the life of the element.

[0076] The second layer 51b comprises an organic mixture of a second compound and a third compound that are different from each other, which may be co-evaporated or formed by any other method known in the art.

[0077] In the second layer 51b according to the present invention, the mixing ratio of the second compound and the third compound is not particularly limited, and is, for example, a weight ratio of 50:50 to 90:10 with respect to the total weight of the second layer 51b. In the second layer 51b, of the second compound and the third compound, the substance with a higher content mainly plays a role of electron transport that moves electrons injected from the negative electrode 20 to the light-emitting layer 40, and the substance with a lower content plays a role of supporting the electron transport layer.

[0078] The second layer 51b, which is made of a predetermined organic mixture, preferably further satisfies at least one of the physical properties described below, so as to obtain the effect of improving the performance of the element by eliminating the use of metals, and to obtain the low voltage, high efficiency, and long life characteristics of the element.

[0079] In a specific example, the HOMO energy level of the second layer 51b may be higher than the HOMO energy level of the first layer 51a. For example, it is 5.6 eV or higher, preferably 5.6 to 6.5 eV, and more preferably 5.6 to 6.3 eV. Here, the HOMO energy level may refer to the magnitude of the absolute value of the HOMO.

[0080] In another specific example, the band gap energy of the second layer 51b may be smaller than the band gap energy of the first layer 51a described above. For example, the band gap energy is 2.5 eV or more, preferably 2.5 to 3.7 eV, and more preferably 2.5 to 3.5 eV.

[0081] In another specific example, the triplet energy of the second layer 51b may be larger than the triplet energy of the first layer 51a described above. For example, the triplet energy is 1.7 eV or more, preferably 1.7 to 3.3 eV, and more preferably 1.7 to 3.1 eV.

[0082] In another specific example, the vector sum (D) of the bond moments of the first layer 51a and the second layer 51b is 3.336×10 -31 C·m or more. Here, the vector sum of bond moments (D) may refer to a value obtained by performing a structural optimization calculation based on density function calculation B3LYP / 6-31G* on the compounds constituting each of the layers 51a and 51b.

[0083] Specifically, the vector sum (D2) of the bond moments of the second layer 51b disposed at a predetermined distance from the light-emitting layer 40 may be greater than the vector sum (D1) of the bond moments of the first layer 51a disposed adjacent to the light-emitting layer 40. When the vector sum (D) of the bond moments between the first layer 51a and the second layer 51b has the above-mentioned configuration, the loss of excitons at the interface between the light-emitting layer 40 and the electron transport layer 51 is prevented, and the efficiency of the device is improved. As an example, the difference (D2-D1) of the vector sum of the bond moments between the second layer 51b and the first layer 51a may exceed 0.

[0084] In addition, the more similar the moieties of the first compound contained in the first layer 51a and the second and third compounds contained in the second layer 51b are, the smoother the transfer of electrons from the negative electrode to the electron transport layer (second layer) to the electron transport layer (first layer) to the light emitting layer. For this reason, it is necessary that the substances contained in the first layer 51a and the second layer 51b contain similar moieties and have a vector sum (D) of bond moments within the above-mentioned numerical range. The moieties of the first compound, the second compound, and the third compound constituting the electron transport layer 51 will be described in detail later.

[0085] In the at least two electron transport layers 51 according to the present invention, the first compound constituting the first layer 51a and the second and third compounds constituting the second layer 51b may be the same or all of them may be different.

[0086] In one embodiment, when the first compound constituting the first layer 51a and the second and third compounds constituting the second layer 51b are different from each other, the vector sum (D2) of the bond moments of any one of the second and third compounds constituting the second layer 51b is larger than the vector sum (D1) of the bond moments of the first compound, but is not limited thereto.

[0087] In another embodiment, one of the second compound and the third compound constituting the second layer 51b may be the same material as the first compound contained in the first layer 51a, and the other may be a material different from the first compound.

[0088] In a specific embodiment, the vector sum (D2) of the bond moments of the second and third compounds that are different from the first compound in the first layer 51a may be greater than the vector sum (D1) of the bond moments of the first compound. Also, the content of the second and third compounds that are different from the first compound may be greater than the content of the same material as the first compound.

[0089] The first layer 51a and the second layer 51b constituting the electron transport layer according to the present invention have the above-mentioned configuration, and as long as the parameters and / or numerical ranges are within the specified ranges, the detailed configuration of the compound constituting the electron transport layer 51, for example, the type of moiety (e.g., EDG group, EWG group) contained in the compound and its bonding position, the introduction position of the linker, and its composition, are not particularly limited.

[0090] In one specific example, the first compound constituting the first layer 51a and the second and third compounds constituting the second layer 51b may be bipolar compounds that simultaneously contain a moiety having the characteristics of an electron-withdrawing group (EWG) with high electron-withdrawing ability and a moiety having the characteristics of an electron-donating group (EDG) with high electron-donating ability.

[0091] More specifically, the first compound, the second compound, and the third compound (material) may contain at least one electron-withdrawing group (EWG) moiety selected from the 6-membered moiety, the 5-membered moiety, and the polycyclic moiety in which the 6-membered moiety and the 5-membered moiety are condensed, as described below.

[0092] As an example, the first compound, the second compound, and the third compound each include at least one first moiety represented by the following chemical formula:

[0093] [ka]

[0094] In the above formula, X1~X 10 and Y1 to Y5 are the same or different and each independently represents N or C(R), provided that the monocyclic or polycyclic moiety contains at least one N; When the above C(R) is plural, the plural R are the same or different and each independently represents a hydrogen atom, a deuterium atom, a halogen group, a cyano group, a nitro group, an amino group, a C1 to C 40 Alkyl groups of C2 to C 40 Alkenyl groups, C2-C 40 Alkynyl groups, C3-C 40 Cycloalkyl groups having 3 to 40 ring atoms, heterocycloalkyl groups having 6 to 40 ring atoms, 60 aryl groups, heteroaryl groups with 5 to 60 ring atoms, C1 to C 40 Alkyloxy groups, C6-C 60 Aryloxy groups, C1-C 40 Alkylsilyl groups, C6-C 60 Arylsilyl groups, C1-C 40 Alkylboron groups, C6-C 60 Arylboron groups, C6-C 60 Arylphosphine groups, C6-C 60 Arylphosphine oxide groups, and C6-C 60 or which may be joined to adjacent groups to form a fused ring; The alkyl group, alkenyl group, alkynyl group, aryl group, heteroaryl group, aryloxy group, alkyloxy group, cycloalkyl group, heterocycloalkyl group, arylamine group, alkylsilyl group, alkylboron group, arylboron group, arylphosphine group, arylphosphine oxide group, and arylamine group of R each independently represent hydrogen, deuterium (D), halogen, cyano group, nitro group, C1 to C6 40 Alkyl groups of C2 to C 40Alkenyl groups, C2-C 40 Alkynyl groups, C3-C 40 Cycloalkyl groups having 3 to 40 ring atoms, heterocycloalkyl groups having 6 to 40 ring atoms, 60 aryl groups, heteroaryl groups with 5 to 60 ring atoms, C1 to C 40 Alkyloxy groups, C6-C 60 Aryloxy groups, C1-C 40 Alkylsilyl groups, C6-C 60 Arylsilyl groups, C1-C 40 Alkylboron groups, C6-C 60 Arylboron groups, C6-C 60 Arylphosphine groups, C6-C 60 Arylphosphine oxide groups, and C6-C 60 In the case where there are a plurality of the above-mentioned substituents, they may be the same or different.

[0095] The first compound, the second compound, and the third compound (material) each contain at least one nitrogen-containing heteroaromatic ring containing at least one nitrogen (N) in the molecular structure, i.e., one or more electron-withdrawing groups (EWGs), and thus have excellent electronic properties. Therefore, when a compound having the above-mentioned six-membered moiety, five-membered moiety, or a polycyclic moiety in which these are condensed is used as a material for the multilayer electron transport layer 51, the electrons can be efficiently accommodated from the negative electrode 20 and smoothly transferred to the light-emitting layer 40, thereby lowering the driving voltage of the device 100 and realizing high efficiency and long life.

[0096] In addition, the material of the electron transport layer 51 has a high triplet energy, and by controlling the type and position of various substituents introduced into the mother nucleus, the molecular weight of the compound is significantly increased, and an improved glass transition temperature and high thermal stability are obtained. In addition, it is also effective in suppressing the crystallization of the organic layer, so that the durability and life characteristics of the organic electroluminescence device 100 including the same are greatly improved.

[0097] According to an embodiment of the present invention, the moiety of the electron-withdrawing group (EWG) of the first compound, the second compound, and the third compound constituting the electron transport layer 51 may be embodied as any one selected from the following structural formulas, but is not limited thereto.

[0098] [ka]

[0099] In the above formula, * denotes a binding site for any one of the first compound, the second compound, and the third compound.

[0100] Although not specifically shown in the above structural formula, at least one substituent known in the art (for example, the same as the definition of R) may be substituted. In addition, although only one bonding site (*) with the compound constituting the exciton binding layer is shown in the above structural formula, the present invention also falls within the scope of the present invention when two bonding sites are included.

[0101] In one embodiment of the present invention, the first compound, the second compound, and the third compound constituting the at least two electron transport layers 51 may include at least one conventional electron donating group (EDG) moiety known in the art that is different from the electron withdrawing group (EWG) described above and has a higher electron donating ability than the electron withdrawing group (EWG).

[0102] For example, each of the first compound, the second compound, and the third compound includes at least one second moiety (eg, EDG) represented by the following chemical formula:

[0103] [ka]

[0104] In the above formula, * denotes a binding site for any one of the first compound, the second compound, and the third compound.

[0105] Although not specifically shown in the above structural formula, at least one substituent known in the art (e.g., the same as the defined portion of R) may be substituted. In addition, although only one bonding site (*) to at least one of the first compound, the second compound, and the third compound is shown in the above structural formula, the present invention also falls within the scope of the present invention when two bonding sites are included. Compounds that can be used as materials for the electron transport layer 51 of the present invention as described above are embodied by the compounds exemplified below. However, the first compound, second compound, and third compound according to the present invention are not limited to those exemplified below. In particular, as long as the compound satisfies the above-mentioned configuration and / or physical properties of the electron transport layer, the type of moiety (e.g., EDG group, EWG group) contained in the compound, its bonding position, and the position of introduction of the linker are not particularly limited, and compounds whose chemical structures have been modified in various ways also fall within the scope of the present invention.

[0106] The electron transport layer 51 according to the present invention may be formed by a method well known in the art, such as vacuum deposition, spin coating, casting, Langmuir-Blodgett (LB) method, inkjet printing, laser printing, or laser induced thermal imaging (LITI), but is not limited to these.

[0107] In the electron transport region 50 according to the present invention, the material of the electron injection layer 52 can be any electron injection material that is easy to inject electrons and has high electron mobility, without any restrictions. Examples of electron injection materials that can be used include, but are not limited to, the bipolar compounds, anthracene derivatives, heteroaromatic compounds, and alkali metal complex compounds. Specific examples include LiF, Li2O, BaO, NaCl, and CsF; lanthanum group metals such as Yb; and metal halides such as RbCl and RbI. These may be used alone or in combination of two or more.

[0108] The electron transport region 50 according to the present invention, specifically the electron injection layer 52, may be co-deposited with an n-type dopant so that electrons can be easily injected from the negative electrode. In this case, the n-type dopant may be any alkali metal complex compound known in the art, such as an alkali metal, an alkaline earth metal, or a rare earth metal.

[0109] The electron transport region 50 can be manufactured by a conventional method in the art, such as, but not limited to, vacuum deposition, spin coating, casting, Langmuir-Blodgett (LB) method, inkjet printing, laser printing, and laser induced thermal imaging (LITI).

[0110] Light-emitting auxiliary layer Optionally, the organic light emitting device 100 of the present invention may further include a light emitting auxiliary layer (not shown) disposed between the hole transport region 30 and the light emitting layer 40 .

[0111] The light-emitting auxiliary layer serves to transport holes moving from the hole transport region 30 to the light-emitting layer 40 and to adjust the thickness of the organic layer A. Such a light-emitting auxiliary layer has a high LUMO value, and therefore blocks the movement of electrons to the hole transport layer 32, and also has a high triplet energy, and therefore blocks the diffusion of excitons from the light-emitting layer 40 to the hole transport layer 32.

[0112] The light-emitting auxiliary layer may include a hole transport material and may be made of the same material as the hole transport region. The light-emitting auxiliary layers of the red, green, and blue organic light-emitting devices may be made of the same material.

[0113] The light-emitting auxiliary layer material is not particularly limited, and examples thereof include carbazole derivatives and arylamine derivatives. Usable light-emitting auxiliary layer materials include, but are not limited to, NPD (N,N-dinaphthyl-N,N'-diphenylbenzidine), TPD (N,N'-bis(3-methylphenyl)-N,N'-bis(phenyl)-benzidine), s-TAD, and MTDATA (4,4',4"-tris(N-3-methylphenyl-N-phenyl-amino)-triphenylamine). These may be used alone or in combination of two or more. The light-emitting auxiliary layer may contain a p-type dopant in addition to the above-mentioned materials. As the p-type dopant, a p-type dopant known in the art may be used.

[0114] Capping Layer Optionally, the organic electroluminescence device 100 of the present invention may further include a capping layer (not shown) disposed on the above-mentioned negative electrode 20. The capping layer serves to protect the organic light emitting device and to facilitate efficient external emission of light emitted from the organic material layer.

[0115] The capping layer may be at least one selected from the group consisting of tris-8-hydroxyquinoline aluminum (Alq3), ZnSe, 2,5-bis(6'-(2',2"-bipyridyl)-1,1-dimethyl-3,4-diphenylsilole, 4'-bis[N-(1-naphthyl)-N-phenyl-amino]biphenyl (α-NPD), N,N'-diphenyl-N,N'-bis(3-methylphenyl)-1,1'-biphenyl-4,4'-diamine (TPD), and 1,1'-bis(di-4-tolylaminophenyl)cyclohexane (TAPC). Such a material for forming the capping layer is less expensive than the materials for forming other layers of the organic light-emitting device.

[0116] Such a capping layer may be a single layer, but may also include two or more layers having different refractive indices such that the refractive index changes gradually through the two or more layers.

[0117] The capping layer can be produced by various methods commonly used in the art, such as vacuum deposition, spin coating, casting, or the LB method.

[0118] The organic light emitting device of the present invention having the above-mentioned configuration can be manufactured by a conventional method in the art. For example, an organic light emitting device can be manufactured by vacuum depositing a cathode material on a substrate, and then vacuum depositing a hole transport region material, a light emitting layer material, an electron transport region material, and an anode material on the anode.

[0119] The organic electroluminescence device 100, 200 according to the present invention has a structure in which a positive electrode 10, an organic layer A, and a negative electrode 20 are laminated in this order, and may further include an insulating layer or an adhesive layer between the positive electrode 10 and the organic layer A, or between the negative electrode 20 and the organic layer A. When a voltage, a current, or both are applied, the organic electroluminescence device according to the present invention has an increased half-life time of the initial luminance while maintaining the maximum luminous efficiency, and thus has excellent life characteristics.

[0120] The present invention will be described in detail below based on examples. However, the examples described below are merely illustrative of the present invention, and the present invention is not limited to these examples. EXAMPLES

[0121] [Preparation example] Compounds 1-30 The compounds according to the present invention were prepared as follows, and the vector sum of their bond moments, HOMO, triplet energy, and singlet energy were measured by methods commonly used in the art. The results are shown in Table 1 below. HOMO may refer to an energy level measured by a cyclic voltammetry (CV) method, in which the energy level is determined from a relative potential value with respect to a reference electrode whose electrode potential value is known. For example, the HOMO energy level of a certain substance can be measured by using ferrocene, whose oxidation potential and reduction potential values ​​are known, as the reference electrode. The vector sum of bond moments, HOMO energy, triplet energy, and singlet energy were calculated based on the formula B3LYP / 6-31G* using a calculation program from Gaussian.

[0122] [Table 1]

[0123] The structures of compounds 1 to 30 shown in Table 1 above are as follows.

[0124] [ka]

[0125] [Examples 1 to 15] Fabrication of blue organic EL elements Compounds 1 to 15 were purified to high purity by sublimation in a conventional manner, and then blue organic EL devices were fabricated according to the following process.

[0126] First, a glass substrate coated with a thin film of ITO (Indium Tin Oxide) at a thickness of 1500 Å was ultrasonically cleaned with distilled water. After cleaning with distilled water, the substrate was ultrasonically cleaned with solvents such as isopropyl alcohol, acetone, and methanol, dried, and then transferred to a UV ozone cleaner (Power sonic 405, manufactured by Fashintech Co., Ltd.) and cleaned with UV for 5 minutes before being transferred to a vacuum deposition machine.

[0127] On the ITO transparent electrode prepared as described above, DS-205 (Doosan Electronics Co., Ltd., 80 nm) / NPB (15 nm) / ADN+5% DS-405 (Doosan Electronics Co., Ltd., 30 nm) / compounds shown in Table 3 below (first layer: 5 nm, second layer: 25 nm) / LiF (1 nm) / Al (200 nm) were laminated in this order to fabricate an organic EL device (see Table 2 below).

[0128] [Table 2]

[0129] [Comparative Example 1] Fabrication of blue organic EL element A blue organic light-emitting device of Comparative Example 1 was produced in the same manner as in Example 1 above, except that the first compound and the third compound were not used, and Alq3 was used alone as the second compound constituting the second layer.

[0130] [Comparative Example 2] Fabrication of blue organic EL element A blue organic light-emitting device of Comparative Example 2 was produced in the same manner as in Example 1, except that no first compound was used, and Alq3 and LiQ were used as the second and third compounds constituting the second layer.

[0131] [Comparative Example 3] Fabrication of blue organic EL element A blue organic light-emitting device of Comparative Example 3 was produced in the same manner as in Example 1 above, except that the first compound was not used, and compounds 16 and 17 were used as the second and third compounds constituting the second layer.

[0132] [Comparative Example 4] Fabrication of blue organic EL element A blue organic light-emitting device of Comparative Example 4 was produced in the same manner as in Example 1, except that the first compound was not used.

[0133] [Comparative Example 5] Fabrication of blue organic EL element A blue organic light-emitting device of Comparative Example 5 was produced in the same manner as in Example 1 above, except that Alq3 was used instead of compound 16 as the second compound constituting the second layer, and no third compound was included.

[0134] [Comparative Example 6] Fabrication of blue organic EL element A blue organic light-emitting device of Comparative Example 6 was produced in the same manner as in Example 1, except that Alq3 and LiQ were used as the second compound and the third compound constituting the second layer.

[0135] [Evaluation example 1] For each of the blue organic EL devices fabricated in Examples 1 to 15 and Comparative Examples 1 to 6, a current density of 10 mA / cm 2 The driving voltage, current efficiency, and emission peak were measured at 200 V, and the results are shown in Table 3 below.

[0136] [Table 3]

[0137] As shown in Table 3 above, it was confirmed that the blue organic light-emitting device of the present invention, which has at least two electron transport layers, a first layer composed of a single specific compound (e.g., compounds 1 to 15) and a second layer containing a mixture of two specific compounds (e.g., compounds 16 to 30), exhibits superior performance in terms of the driving voltage and current efficiency of the device compared to a control group not containing this.

[0138] Specifically, among Comparative Examples 1 to 4 that do not include a first layer, Comparative Examples 3 and 4 that have an electron transport layer made of an organic compound as the electron transport layer material were found to have improved element driving voltage and efficiency characteristics compared to Comparative Examples 1 and 2 that include a metal as the electron transport layer material.

[0139] Moreover, it was found that in Comparative Examples 5 and 6, which had two electron transport layers, the driving voltage and efficiency characteristics of the device were improved compared to Comparative Examples 1 and 2, which had a single electron transport layer.

[0140] In addition, Comparative Example 7, which has two electron transport layers, with the first and second layers each using one type of organic material, and Comparative Example 8, which has the first layer made of one type of organic material and the second layer containing one type of organic material and a metal, were found to exhibit performance equivalent to or better than those of Comparative Examples 1 and 2, which have a single electron transport layer, in terms of device driving voltage and efficiency characteristics.

[0141] [Examples 16 to 30] Fabrication of blue organic EL elements Compounds 1 to 15 were purified to high purity by sublimation in a conventional manner, and then blue organic EL devices were fabricated according to the following process.

[0142] First, a glass substrate coated with a thin film of ITO (Indium Tin Oxide) at a thickness of 1500 Å was ultrasonically cleaned with distilled water. After cleaning with distilled water, the substrate was ultrasonically cleaned with solvents such as isopropyl alcohol, acetone, and methanol, dried, and then transferred to a UV ozone cleaner (Power sonic 405, manufactured by Fashintech Co., Ltd.) and cleaned with UV for 5 minutes before being transferred to a vacuum deposition machine.

[0143] On the ITO transparent electrode prepared as described above, DS-205 (Doosan Electronics Co., Ltd., 80 nm) / NPB (15 nm) / ADN+5% DS-405 (Doosan Electronics Co., Ltd., 30 nm) / compounds shown in Table 5 below (first layer: 5 nm, second layer: 25 nm) / LiF (1 nm) / Al (200 nm) were laminated in this order to fabricate an organic EL device (see Table 4 below).

[0144] [Table 4]

[0145] [Evaluation example 2] For each of the blue organic EL devices fabricated in Examples 16 to 30 and Comparative Example 7, a current density of 10 mA / cm 2 The driving voltage, current efficiency, and emission peak were measured at 200 V, and the results are shown in Table 5 below.

[0146] [Table 5]

[0147] As shown in Table 5 above, it was confirmed that the blue organic light-emitting device of the present invention, which has at least two electron transport layers, a first layer composed of a single specific compound (e.g., compounds 1 to 15) and a second layer containing a mixture of two specific compounds (e.g., compounds 1 to 30), exhibits superior performance in terms of the driving voltage and current efficiency of the device compared to a control group not containing this.

[0148] Specifically, it was found that even when a single organic material is used as a mixture component in the second layer of at least two electron transport layers, the device exhibits excellent performance in terms of driving voltage and current efficiency characteristics. [Explanation of symbols]

[0149] 100: Organic electroluminescence element A:Organic layer 10: Positive electrode 20: Negative electrode 30: Hole transport region 31: Hole injection layer 32: Hole transport layer 40: Light-emitting layer 50: Electron transport region 51: Electron transport layer 51a: 1st layer 51b: 2nd layer 52: Electron injection layer

Claims

1. Positive electrode; a negative electrode disposed opposite the positive electrode; a light-emitting layer disposed between the positive electrode and the negative electrode; and an electron transport layer disposed between the light-emitting layer and the negative electrode; Including, The electron transport layer comprises at least two layers including a first layer and a second layer; Of the at least two layers, a first layer in contact with the light-emitting layer is composed of a first compound, Of the at least two layers, a second layer disposed adjacent to the negative electrode is composed of at least two organic mixtures including a second compound and a third compound; An organic electroluminescence device, wherein one of the second compound and the third compound is the same as or different from the first compound.

2. The organic electroluminescence device according to claim 1 , wherein the electron transport layer including at least two layers does not contain a metal.

3. The organic electroluminescence device according to claim 1 , wherein the first layer has a HOMO energy level of 5.4 eV or higher.

4. The organic electroluminescence device according to claim 1 , wherein the first layer has a band gap energy of 2.7 eV or more.

5. The organic electroluminescence device according to claim 1 , wherein the triplet energy of the first layer is 1.5 eV or more.

6. The organic electroluminescence device according to claim 1 , wherein the singlet energy of the first layer is 2.5 eV or more.

7. The organic electroluminescence device according to claim 1 , wherein the HOMO energy level of the second layer is 5.6 eV or higher.

8. The organic electroluminescence device according to claim 1 , wherein the band gap energy of the second layer is 2.5 eV or more.

9. The organic electroluminescence device according to claim 1 , wherein the triplet energy of the second layer is 1.7 eV or more.

10. The vector sum (D) of the joint moments of the first and second layers is 3.336×10 －３１ The organic electroluminescence device according to claim 1 , wherein the electroluminescence coefficient is C·m or more.

11. the second layer is formed by co-deposition of a second compound and a third compound, The organic electroluminescence device according to claim 1 , wherein the first compound, the second compound, and the third compound are different substances from each other.

12. The vector sum (D ２ ) is the sum of the bond moment vectors of the first compound (D １ 12. The organic electroluminescence device according to claim 11, wherein the thickness of the first insulating film is greater than the thickness of the second insulating film.

13. the second layer is formed by co-deposition of a second compound and a third compound, The organic electroluminescence device according to claim 1 , wherein one of the second compound and the third compound is the same material as the first compound, and the other is a material different from the first compound.

14. The vector sum (D ２ ) is the vector sum of the bond moments of the first compound (D １ 14. The organic electroluminescence device according to claim 13, wherein the thickness of the first insulating film is greater than the thickness of the second insulating film.

15. The organic electroluminescence element according to claim 13 , wherein the second compound and the third compound each have a content of a substance different from that of the first compound that is greater than a content of the same substance as that of the first compound.

16. 2. The organic electroluminescence device according to claim 1, wherein a mixing ratio of the second compound to the third compound is from 50:50 to 90:10 by weight with respect to a total weight of the second layer.

17. The organic electroluminescence element according to claim 1 , wherein the first compound, the second compound, and the third compound constituting the first layer and the second layer each contain at least one first moiety represented by the following chemical formula: 【Chemistry 1】 (In the formula, X １ ~X １０ and Y １ ~Y ５ are the same or different and each independently is N or C(R), provided that the monocyclic or polycyclic moiety contains at least one N; When the above C(R) is plural, the plural R are the same or different and each independently represent a hydrogen atom, a deuterium atom, a halogen group, a cyano group, a nitro group, an amino group, C １ ~C ４０ Alkyl groups of C ２ ~C ４０ an alkenyl group of C ２ ~C ４０ an alkynyl group of C ３ ~C ４０ a cycloalkyl group having 3 to 40 ring atoms; ６ ~C ６０ an aryl group having 5 to 60 ring atoms; １ ~C ４０ an alkyloxy group of C ６ ~C ６０ an aryloxy group of C １ ~C ４０ an alkylsilyl group of C ６ ~C ６０ an arylsilyl group of C １ ~C ４０ an alkylboron group of C ６ ~C ６０ Arylboron groups of C ６ ~C ６０ an arylphosphine group of C ６ ~C ６０ and an arylphosphine oxide group of C ６ ~C ６０ or which may be joined to adjacent groups to form a fused ring; The alkyl group, alkenyl group, alkynyl group, aryl group, heteroaryl group, aryloxy group, alkyloxy group, cycloalkyl group, heterocycloalkyl group, arylamine group, alkylsilyl group, alkylboron group, arylboron group, arylphosphine group, arylphosphine oxide group, and arylamine group of R each independently represent hydrogen, deuterium (D), halogen, cyano group, nitro group, C １ ~C ４０ Alkyl groups of C ２ ~C ４０ an alkenyl group of C ２ ~C ４０ an alkynyl group of C ３ ~C ４０ a cycloalkyl group having 3 to 40 ring atoms; ６ ~C ６０ an aryl group having 5 to 60 ring atoms; １ ~C ４０ an alkyloxy group of C ６ ~C ６０ an aryloxy group of C １ ~C ４０ an alkylsilyl group of C ６ ~C ６０ an arylsilyl group of C １ ~C ４０ an alkylboron group of C ６ ~C ６０ Arylboron groups of C ６ ~C ６０ an arylphosphine group of C ６ ~C ６０ and an arylphosphine oxide group of C ６ ~C ６０ In this case, when there are a plurality of the above-mentioned substituents, they may be the same or different from each other.)

18. The organic electroluminescence element according to claim 1 , wherein the first compound, the second compound, and the third compound constituting the first layer and the second layer each contain at least one second moiety represented by the following chemical formula: 【Chemistry 3】

19. a hole transport region disposed between the positive electrode and the light emitting layer; The organic electroluminescent device according to claim 1 , wherein the hole transport region includes at least one of a hole injection layer and a hole transport layer.

20. 10. The organic electroluminescent device of claim 1, wherein the organic electroluminescent device comprises a plurality of emissive stacks, each including at least one emissive layer.

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