Organic electroluminescent device

Abstract

The present invention provides an organic electroluminescent device having improved properties such as low driving voltage, high luminous efficiency, and long life by including a hybrid electron transport layer containing a dimer controlled to have predetermined physical properties.

Description

[Technical Field]

[0001] The present invention relates to an organic electroluminescent device having improved properties such as low driving voltage, high luminous efficiency, and long life by including a hybrid electron transport layer containing a dimer controlled to have predetermined physical properties. [Background technology]

[0002] In 1965, research on organic electroluminescent (EL) elements (hereafter simply referred to as "OLEDs") using anthracene single crystals led to blue electroluminescence. In 1987, Tang proposed an OLED element with a two-layer structure consisting of a hole layer (NPB) and an emissive layer (Alq3). Subsequently, to achieve the high efficiency and long life required for commercialization, a multilayer structure was proposed, with each layer having its own distinctive and specialized functions: an organic layer responsible for hole injection and transport, an organic layer responsible for electron injection and transport, and an organic layer responsible for inducing electroluminescence through the recombination of holes and electrons. The introduction of the multilayer structure improved the performance of OLEDs to a level that allowed them to be commercially viable, and their range of applications has expanded, from in-car radio display products in 1997 to portable information displays and television display elements.

[0003] The demand for larger displays and higher resolutions poses the challenge of improving the efficiency and lifespan of organic EL elements. In particular, when higher resolution is achieved by forming more pixels in the same area, this results in a reduction in the light-emitting area of ​​the organic EL pixel, which inevitably shortens its lifespan. This is the most important technical challenge that organic EL elements must overcome.

[0004] When a current or voltage is applied to two electrodes in an organic EL element, holes are injected into the organic layer from the anode, and electrons are injected into the organic layer from the cathode. The injected holes and electrons combine to form excitons, which emit light when they return to their ground state. Depending on the type of electron spin of the excitons formed, organic EL elements can be divided 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 at a rate of 25% as singlet excitons and 75% as triplet excitons. Fluorescent EL elements that emit light from singlet excitons theoretically cannot exceed an internal quantum efficiency of 25% due to the generation rate, and their external quantum efficiency is said to be limited to 5%. Phosphorescent EL elements that emit light from triplet excitons can improve their luminous efficiency by up to four times compared to fluorescence when using a metal complex compound containing heavy atoms of transition metals such as Ir or Pt as a phosphorescent dopant.

[0006] As described above, based on theoretical facts, phosphorescent EL devices exhibit higher luminous efficiency than fluorescent devices. However, in the case of blue phosphorescent devices (excluding green and red), the color purity of deep blue, the development level of highly efficient phosphorescent dopants, and hosts with wide energy gaps to satisfy the dopants are insufficient. As a result, blue phosphorescent devices have not yet been commercialized, and blue fluorescent devices are still used in products.

[0007] In order to improve the characteristics of the organic EL device, research results have been reported to prevent holes from diffusing into the electron transport layer and increase the stability of the device, but satisfactory results have not been obtained to date. Summary of the Invention [Problem to be solved by the invention]

[0008] The present invention has been made to solve the above-mentioned problems, and aims to provide an organic EL device that simultaneously exhibits high efficiency, low voltage, and long life by including a hybrid electron transport layer containing a dimer with predetermined physical properties as one component of at least two electron transport regions.

[0009] Other objects and advantages of the present invention will be more clearly explained from the detailed description and claims that follow. [Means for solving the problem]

[0010] In order to achieve the above technical object, the present invention provides an organic electroluminescent device having an anode, a hole transport region, a light emitting layer, an electron transport region, and a cathode stacked in this order, wherein the electron transport region comprises a hybrid electron transport layer (Hybrid ETL), and the hybrid ETL contains a dimer derived from at least two organic materials including a first monomer and a second monomer; The LUMO density of states (LUMO-DOS) of the hybrid electron transport layer Dimer )teeth, (i) LUMO density of states of the first monomer (LUMO-DOS ET1 ); (ii) LUMO density of states 1-1 of the isomorphous first dimer (LUMO-DOS ET1_ET1_Dimer ); (iii) LUMO density of states of the second monomer (LUMO-DOS ET2 ); (iv) LUMO density of states 2-2 of the isomorphous second dimer (LUMO-DOS ET2_ET2_Dimer ); and (v) LUMO density of states 3 (LUMO-DOS) of the heteromorphic third dimer consisting of the first and second monomers ET1_ET2_Dimer ); (vi) the absolute value of the LUMO energy level of the first monomer is lower than the absolute value of the LUMO energy level of the second monomer; (vii) the LUMO density of states 3 (LUMO-DOS) of the heteromorphic third dimer ET1_ET2_Dimer) is the LUMO density of states 1 (LUMO-DOS) of the first monomer. ET1 ) and the LUMO density of states 2 (LUMO-DOS ET2 The present invention provides an organic electroluminescent device that overlaps with at least one of the following:

[0011] According to one embodiment of the present invention, the LUMO density of states 3 (LUMO-DOS) of the heteromorphic third dimer is ET1_ET2_Dimer ) is the LUMO density of states 1-1 (LUMO-DOS) of the first isomorphic dimer. ET1_ET1_Dimer ) and the LUMO density of states of the isomorphic second dimer 2-2 (LUMO-DOS ET2_ET2_Dimer ) may be overlapped with at least one of

[0012] According to one embodiment of the present invention, the difference in absolute value between the first LUMO energy level (ET1_LUMO) of the first monomer and the second LUMO energy level (ET2_LUMO) of the second monomer may be greater than 0 and less than or equal to 2.0 eV.

[0013] According to one embodiment of the present invention, the LUMO density of states 3 (LUMO-DOS) of the heteromorphic third dimer is ET1_ET2_Dimer ) and the LUMO density of states 2 (LUMO-DOS ET2 ) may have an overlap rate of more than 0% and 80% or less.

[0014] According to an embodiment of the present invention, the dimer may include a first monomer and a second monomer, and may be formed by co-deposition thereof.

[0015] According to one embodiment of the present invention, the hybrid electron transport layer (Hybrid-ETL) may be an organic layer that does not contain a metal complex.

[0016] According to one embodiment of the present invention, the electron transport region includes at least two layers, and may include at least one of a hybrid electron transport layer (Hybrid-ETL) and an electron transport auxiliary layer and an electron injection layer.

[0017] According to one embodiment of the present invention, the electron transport auxiliary layer may be disposed between the light-emitting layer and the hybrid electron transport layer, and the electron injection layer may be disposed between the hybrid electron transport layer and the cathode.

[0018] According to one embodiment of the present invention, the LUMO density of states (LUMO-DOS) of the hybrid electron transport layer Dimer ) may overlap with the LUMO density of states (LUMO-DOSAETL) of the electron transport supporting layer.

[0019] According to one embodiment of the present invention, the difference in absolute value between the LUMO energy level of the first monomer and the LUMO energy level of the electron transporting supporting layer may be more than 0 eV and not more than 1.5 eV.

[0020] According to one embodiment of the present invention, the difference in absolute value between the LUMO energy level of the second monomer and the work function of the cathode may be more than 0.5 eV and not more than 2.5 eV.

[0021] According to one embodiment of the present invention, the difference in absolute value of the molecular weight (MW) between the first monomer and the second monomer may be 0 to 600 g / mol.

[0022] According to one embodiment of the present invention, the triplet energy (T1) of the hybrid electron transport layer (Hybrid-ETL) may be 1.5 eV or more.

[0023] According to one embodiment of the present invention, the singlet energy (S1) of the hybrid electron transport layer (Hybrid-ETL) may be 2.0 eV or more.

[0024] According to one embodiment of the present invention, the absolute value of the HOMO energy of the hybrid electron transport layer (Hybrid-ETL) may be 4.0 eV or more.

[0025] According to an embodiment of the present invention, the lowest energy level of the ground state bond dissociation energy (BDE) of the hybrid-electron transport layer (Hybrid-ETL) may be 0.8 eV or more.

[0026] According to one embodiment of the present invention, the hybrid electron transport layer (Hybrid-ETL) may have a refractive index (n) of 0.7 or more in the blue wavelength region of 400 to 470 nm.

[0027] According to one embodiment of the present invention, the difference in refractive index between the first monomer and the second monomer may be 0 or more and 2 or less in the blue wavelength region of 400 to 470 nm.

[0028] According to one embodiment of the present invention, the hybrid-electron transport layer (Hybrid-ETL) may have a dipole moment greater than zero.

[0029] According to one embodiment of the present invention, the hybrid-electron transport layer (Hybrid-ETL) may have an electron affinity (EA) of 0.2 eV or more.

[0030] According to one embodiment of the present invention, the hybrid electron transport layer (Hybrid-ETL) has a zero-field conductivity of at least 1×10 -8 cm 2 The electron mobility (μ) may be equal to or greater than 1 / Vs.

[0031] According to one embodiment of the present invention, the light-emitting layer includes a host and a dopant, and the mixing ratio of the host to the dopant may be 70 to 99.5:0.5 to 30 by weight.

[0032] According to one embodiment of the present invention, the organic electroluminescent device may include a multi-emissive layer stack including at least one emissive layer. [Effects of the Invention]

[0033] According to one embodiment of the present invention, an organic electroluminescent device having a low driving voltage, high efficiency, and long life can be provided by providing a hybrid electron transport layer (Hybrid-ETL) containing a dimer formed by the bonding of at least two or more molecules and adjusted to have predetermined physical properties as a component of an electron transport region, thereby suppressing hole / electron leakage and efficiently injecting carriers from an electrode.

[0034] The effects of the present invention are not limited to the above-mentioned examples, and various other effects are included in this specification. [Brief explanation of the drawings]

[0035] [Figure 1] 1 is a cross-sectional view showing a structure of an organic electroluminescent device according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0036] The advantages and features of the present invention, as well as methods for achieving them, will become more apparent from the following detailed description of the embodiments in conjunction with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, and can be realized in various different forms. The present embodiments are provided solely to ensure that the disclosure of the present invention is complete and to fully convey the scope of the invention to those skilled in the art to which the present invention pertains. The present invention is defined solely by the scope of the claims. Therefore, in some embodiments, well-known process steps, well-known device structures, and well-known techniques are not specifically described to avoid ambiguous interpretation of the present invention. The same reference numerals refer to the same elements throughout the specification.

[0037] Unless otherwise defined, all terms (including technical and scientific terms) used in this specification can be used in a manner commonly understood by a person of ordinary skill in the art to which the present invention belongs. Furthermore, terms defined in commonly used dictionaries should not be interpreted ideally or excessively unless explicitly defined otherwise.

[0038] Furthermore, throughout the specification, when a part "comprises" a certain element, it does not mean excluding other elements, but may further include other elements, unless otherwise specified. Furthermore, throughout the specification, "above" or "on top" means not only being located above or below the part in question, but also including cases where there are other elements therebetween, and does not necessarily mean being located on the upper side based on the direction of gravity. Furthermore, throughout the specification, terms such as "first" and "second" do not indicate any order or importance, but are used to distinguish elements from each other.

[0039] Throughout this specification, the term "density of states (DOS)" can be defined as the number of allowed occupied electronic states at a particular energy level such as HOMO or LUMO. The HOMO density of states (HOMO DOS) and LUMO density of states (LUMO DOS) of each material can be obtained by the method described below.

[0040] <Organic electroluminescent device> Hereinafter, preferred embodiments of the organic electroluminescent device according to the present invention will be described with reference to the accompanying drawings. However, the present invention may be modified into various different forms, and the scope of the present invention is not limited to the following embodiments.

[0041] FIG. 1 is a cross-sectional view schematically illustrating the structure of an organic electroluminescent device 100 according to one embodiment of the present invention.

[0042] Referring to FIG. 1, the organic electroluminescent device 100 includes an anode 10, a cathode 20, an emissive layer 40 disposed between the anode 10 and the cathode 20, a hole transport region 30 disposed between the anode 10 and the emissive layer 40, and an electron transport region 50 disposed between the emissive layer 40 and the cathode 20. The electron transport region 50 includes at least two layers, each of which includes a hybrid electron transport layer (Hybrid-ETL) 52, which includes a dimer derived from at least two organic monomers and in which the LUMO density of states (LUMO-DOS) of the dimer is controlled within a specific range.

[0043] When electrons / holes accumulate in the light-emitting layer (e.g., host), they migrate or diffuse into adjacent layers, resulting in leakage, which adversely affects the efficiency and lifetime of the device. To prevent this leakage, a functional layer composed of a single organic molecule, such as a hole leakage suppression layer, has been placed between the light-emitting layer and the electron transport region, or two organic materials have simply been mixed. However, this approach has made it difficult to achieve the desired efficiency improvement. Furthermore, while metal complexes such as Liq have traditionally been included as components of the electron transport layer, this requires a separate process for handling the metal complex.

[0044] The present invention is differentiated from conventional electron transport layers containing a single molecule or a single molecule and a metal complex (Liq) in that a hybrid electron transport layer (Hybrid-ETL) 51 containing a dimer derived from at least two organic materials is disposed as one layer of two or more electron transport regions 50. In particular, the hybrid electron transport layer 52 of the present invention does not contain a metal or metal complex and is entirely composed of an organic material layer, fundamentally resolving the aforementioned problems associated with the use of metals. In addition, the various energy levels of the organic materials used can be adjusted to rapidly transport electrons from the electrode to the host of the light-emitting layer 40.

[0045] In addition, electrons move along the LUMO energy level. From the viewpoint of LUMO-DOS, the LUMO density of states (DOS) of a conventional electron transport layer made of a single molecule (e.g., ET1) is limited to the LUMO-DOS of the first monomer (e.g., ET1) or the isomorphous first dimer (e.g., ET1-ET1 dimer), and electron transport occurs through the superposition of one or two such LUMO-DOS.

[0046] In contrast, the hybrid electron transport layer 52 according to the present invention contains at least two or more organic molecules, for example, a first monomer (e.g., ET1) and a second monomer (ET2), or is formed by combining these. Since the hybrid electron transport layer 52 contains not only two types of monomers (e.g., ET1 and ET2) but also various forms of dimers derived therefrom (e.g., ET1-ET1, ET2-ET2, ET1-ET2, etc.), the LUMO-DOS (e.g., LUMO-DOS) of the various monomers can be varied within the electron transport region. ET1 , LUMO-DOS ET2 ), the LUMO-DOS of the homomorphic dimer (e.g., ET1_ET1_Dimer , LUMO-DOS ET2_ET2_Dimer ), and the LUMO-DOS of heterodimers (e.g., LUMO-DOS ET1_ET2_Dimer Unlike metal complexes with a single energy level (e.g., Liq), the LUMO-DOS of the above-mentioned homodimer and heterodimer is the same as that of the conventional first and second monomers (e.g., LUMO-DOS ET1 , LUMO-DOS ET2 ) will be generated and exist as a new energy level between the dimers, and such a distribution of the LUMO-DOS of the dimers will act as a bridge for electron transfer and increase the rapid electron transfer effect from the electrode to the host. In this way, the distribution of the LUMO-DOS of various monomers and the LUMO-DOS of the dimers will relatively increase the overlap rate between these densities of state, and in particular, the heterodimers (LUMO-DOS ET1_ET2_DimerThe presence or absence of a specific range of the component (a) can further increase the efficient electron transfer effect from the hybrid electron transport layer 52 to the host, thereby realizing the synergistic effects of increased efficiency, low driving voltage, and long life characteristics of the organic electroluminescent device.

[0047] According to one embodiment, the hybrid-electron transport layer (Hybrid-ETL) 52 includes a dimer derived from at least two organic materials including a first monomer and a second monomer, and the LUMO density of states (LUMO-DOS) of the hybrid-electron transport layer is Dimer ) is (i) the LUMO density of states 1 (LUMO-DOS) of the first monomer ET1 (ii) LUMO density of states 1-1 of the isomorphous first dimer (LUMO-DOS ET1_ET1_Dimer (iii) LUMO density of states 2 (LUMO-DOS) of the second monomer ET2 (iv) LUMO density of states 2-2 of the isomorphous second dimer (LUMO-DOS ET2_ET2_Dimer and (v) the LUMO density of states 3 (LUMO-DOS) of the heteromorphic third dimer consisting of the first and second monomers. ET1_ET2_Dimer (vi) the absolute value of the LUMO energy level of the first monomer is lower than the absolute value of the LUMO energy level of the second monomer; and (vii) the LUMO density of states 3 (LUMO-DOS) of the heteromorphic third dimer is ET1_ET2_Dimer ) is the LUMO density of states 1 (LUMO-DOS) of the first monomer. ET1 ) and the LUMO density of states 2 (LUMO-DOS ET2 ) overlaps with at least one of

[0048] Here, the LUMO density of states of the heteromorphic third dimer is ET1_ET2_Dimer ) and the LUMO density of states of the first monomer (LUMO-DOS ET1 ), or the LUMO density of states of the heteromorphic third dimer (LUMO-DOS ET1_ET2_Dimer ) and the LUMO density of states of the second monomer (LUMO-DOS ET2The overlapping ratio (degree of overlap) of the LUMO density of states 3 (LUMO-DOS) of the heteromorphic third dimer is not particularly limited and can be adjusted appropriately in consideration of the above-mentioned carrier mobility. As an example, the overlapping ratio may be more than 0%, specifically more than 0% and not more than 100%, and more specifically 1 to 95%. In the present invention, the LUMO density of states 3 (LUMO-DOS) of the heteromorphic third dimer is ET1_ET2_Dimer ), LUMO density of states of the first monomer 1 (LUMO-DOS ET1 ), and the LUMO density of states of the second monomer (LUMO-DOS ET2 ) preferably overlap at least partially at the same time.

[0049] According to another embodiment, the LUMO density of states 3 (LUMO-DOS) of the heteromorphic third dimer ET1_ET2_Dimer ) is the LUMO density of states 1-1 (LUMO-DOS) of the first isomorphic dimer. ET1-ET1 ) and the LUMO density of states 2-2 of the isomorphous second dimer (LUMO-DOS ET2-ET2 ) may be overlapped with at least one of

[0050] Here, the LUMO density of states of the heteromorphic third dimer is ET1_ET2_Dimer ) and the LUMO density of states 1-1 (LUMO-DOS ET1-ET1 ); or the LUMO density of states of the heteromorphic third dimer (LUMO-DOS ET1_ET2_Dimer ) and the LUMO density of states of the isomorphic second dimer 2-2 (LUMO-DOS ET2-ET2 The overlapping ratio (degree of overlap) of the LUMO density of states of the dimer between the heterocyclic third dimer and the heterocyclic third dimer is not particularly limited and can be adjusted appropriately taking into consideration the carrier mobility described above. As an example, the overlapping ratio may be more than 0%, specifically more than 0% and up to 100%, and more specifically 1 to 95%. Specifically, the LUMO density of states 3 (LUMO-DOS) of the heterocyclic third dimer is ET1_ET2_Dimer ), the LUMO density of states of the first isomorphous dimer 1-1 (LUMO-DOS ET1-ET1 ); and the LUMO density of states of the isomorphous second dimer 2-2 (LUMO-DOS ET2-ET2 ) preferably overlap at least partially at the same time.

[0051] According to another embodiment, the LUMO density of states 3 (LUMO-DOS) of the heteromorphic third dimer ET1_ET2_Dimer ) and the LUMO density of states 2 (LUMO-DOS) of the second monomer in the hybrid-electron transport layer (Hybrid-ETL) 52 that has the largest absolute value. ET2 ) may be more than 0% and not more than 80%, and specifically may be more than 0% and not more than 50%.

[0052] On the other hand, the density of states (LUMO-DOS) of the dimers in the hybrid electron transport layer 52 Dimer At least one of the LUMO densities of states (LUMO-DOS) may overlap with a region of the electron transport region 50, specifically, with the LUMO density of states (LUMO-DOS) of the electron transport auxiliary layer 53 adjacent to the light-emitting layer among at least two electron transport regions. In this manner, a new energy level density of states is generated by the dimer, which improves electron mobility between the hybrid electron transport layer 52 and the electron transport auxiliary layer 53, thereby achieving a synergy effect. The overlapping ratio of the LUMO densities of states (LUMO-DOS) of the electron transport region 50 and the hybrid electron transport layer 52 is not particularly limited and can be appropriately adjusted in consideration of the aforementioned physical property improvement effect. In this case, when the electron transport region 50 has a multilayer structure, the overlapping region of the electron transport region 50 may refer to a layer that directly contacts the hybrid electron transport layer 52.

[0053] According to one specific example, the difference in absolute value between the LUMO energy level of the first monomer having the smallest absolute value in the hybrid-electron transport layer (Hybrid-ETL) 52 and the LUMO energy level of the electron transport assistance layer 53 may be greater than 0 eV and less than or equal to 1.5 eV, specifically, 0.05 to 1.0 eV.

[0054] According to another specific example, the difference in absolute value between the LUMO energy level of the second monomer having the largest absolute value in the hybrid-electron transport layer (Hybrid-ETL) and the work function of the cathode 20 may be more than 0.5 eV and not more than 2.5 eV, specifically, 1.0 to 2.0 eV.

[0055] The hybrid electron transport layer (Hybrid-ETL) 52 according to the present invention preferably further satisfies at least one of the following physical properties in order to achieve low driving voltage and high efficiency, in addition to controlling the overlap of the LUMO density of states (LUMO DOS) of the dimers described above, thereby preventing leakage and increasing electron mobility:

[0056] According to one embodiment, the singlet energy (S1) of the hybrid electron transport layer (Hybrid-ETL) 52 may be 2.0 eV or more, specifically 2.0 to 4.5 eV, more specifically 2.0 to 4.0 eV. This effectively binds singlet excitons, preventing them from diffusing to adjacent interfaces and / or other layers or from emitting light at the interfaces. This increases the number of excitons, improving the luminous efficiency of the organic electroluminescent device. As a result, spectral color mixing of the organic electroluminescent device is prevented, stability is improved, and the efficiency and lifetime of the organic electroluminescent device are improved.

[0057] According to another specific example, the triplet energy (T1) of the hybrid-electron transport layer (Hybrid-ETL) 52 may be 1.5 eV or more, specifically 1.5 to 4.5 eV, more specifically 1.5 to 4.0 eV, which can prevent excitons from migrating to other layers, thereby significantly increasing the efficiency of the organic electroluminescent device.

[0058] According to another embodiment, the absolute value of the HOMO (Highest Occupied Molecular Orbital) energy of the hybrid-electron transport layer (Hybrid-ETL) 52 may be 4.0 eV or more, specifically 4.0 to 7.0 eV, more specifically 4.5 to 6.5 eV. Such a HOMO energy value can prevent holes transferred to the light-emitting layer 40 from diffusing or migrating to another electron transport region, such as the electron transport layer 51. This increases the probability of hole-electron recombination within the light-emitting layer 40, thereby further improving the luminous efficiency of the organic electroluminescent device. Furthermore, the irreversible decomposition reaction due to oxidation that occurs when holes diffuse or migrate beyond the light-emitting layer 40 to the electron transport layer 51, and the resulting reduction in the lifespan of the organic electroluminescent device, can be prevented, thereby improving the lifespan of the device.

[0059] According to another specific example, the absolute value of the LUMO (Lowest Unoccupied Molecular Orbital) energy of the hybrid-electron transport layer (Hybrid-ETL) 52 may be 1.0 eV or more, specifically 1.0 to 3.5 eV, and more specifically 1.0 to 3.0 eV. For efficient electron generation, the band gap energy of the hybrid-electron transport layer (Hybrid-ETL) 52 may be 2.0 eV or more, specifically 2.0 to 4.5 eV.

[0060] According to another example, the hybrid-electron transport layer (Hybrid-ETL) 52 may have a ground state bond dissociation energy (BDE) of 0.8 eV or more, specifically 1.0 to 6.0 eV, more specifically 1.5 to 6.0 eV, at its lowest energy level. Here, the bond dissociation energy (BDE) can be interpreted as the energy required to break a specific chemical bond. Generally, the stronger the bond, the more closely the bond dissociation energy (BDE) is related to molecular stability, and therefore, it may act as a factor affecting the lifetime.

[0061] According to another specific example, the hybrid-electron transport layer (Hybrid-ETL) 52 may have an electron affinity (EA) of at least 0.2 eV or more, specifically 0.5 to 3.0 eV. When the hybrid-ETL has the above-described electron affinity, high electron injection efficiency can be obtained.

[0062] According to another specific example, when the light-emitting layer 40 is a blue light-emitting layer containing a fluorescent blue light-emitting material, the hybrid-electron-transporting layer (Hybrid-ETL) 52 may have a refractive index (n) of at least 0.7 or more, specifically 0.7 to 3.5, in the blue wavelength region of 400 to 470 nm.

[0063] According to another embodiment, the hybrid-electron transport layer (Hybrid-ETL) 52 may have a dipole moment greater than 0, specifically, 0-10.

[0064] Meanwhile, if the balance between electrons and holes is not achieved due to the difference between the number of holes injected from the anode 10 and the number of electrons injected from the cathode 20, the electrons or holes that cannot recombine to form excitons will accumulate in the light-emitting layer 40. The electrons or holes accumulated in the light-emitting layer 40 may hinder smooth oxidation and reduction in the light-emitting layer 40 or may affect adjacent layers, thereby reducing the lifespan of the organic electroluminescent device. In contrast, the hybrid-electron transport layer (Hybrid-ETL) 52 has a density of at least 1×10 at room temperature and zero-field. -8 cm 2 By having an electron mobility (μ) of 1 / Vs or more, the injection of electrons is prevented from becoming slow compared to the number of holes injected from the anode 10, and electrons are smoothly injected into the light-emitting layer 40, which increases the efficiency of exciton formation in the light-emitting layer 40 and improves the life of the organic electroluminescent device.

[0065] Hereinafter, the configuration of the organic electroluminescent device 100 including the hybrid-electron transport layer (Hybrid-ETL) 52 according to one embodiment of the present invention will be described in more detail.

[0066] anode In the organic electroluminescent device 100 according to the present invention, the anode 10 plays a role in injecting holes into the organic layer (A).

[0067] The material for the anode 10 is not particularly limited, and may be any material known in the art, including, but not limited to, 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:Sb; conductive polymers such as polythiophene, poly(3-methylthiophene), poly[3,4-(ethylene-1,2-dioxy)thiophene] (PEDT), polypyrrole, and polyaniline; and carbon black.

[0068] The method for manufacturing the anode 10 is not particularly limited, and may be a conventional method well known in the art, such as a method of coating an anode material onto a substrate made of a silicon wafer, quartz, glass plate, metal plate, or plastic film.

[0069] cathode In the organic electroluminescent device 100 according to the present invention, the cathode 20 plays a role of injecting electrons into the organic layer (A).

[0070] The material for the cathode 20 is not particularly limited, and may be any material known in the art, such as, but not limited to, metals such as magnesium, calcium, sodium, potassium, titanium, indium, yttrium, lithium, gadolinium, aluminum, silver, tin, and lead; alloys thereof; and multilayer structures such as LiF / Al and LiO / Al.

[0071] The method for manufacturing the cathode 20 is not particularly limited, and the cathode 20 may be manufactured by a method known in the art.

[0072] organic layer The organic layer (A) included in the organic electroluminescent device according to the present invention can be any ordinary structure used as an organic layer in a conventional organic EL device, and may include, for example, 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, in consideration of the properties of the organic electroluminescent device, it is preferable that the organic layer (A) include all of the above-mentioned organic layers.

[0073] hole transport region The hole transport region 30 contained in the organic layer (A) of the present invention plays a role in transferring holes injected from the anode 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, in consideration of the properties of the organic electroluminescent device, it is preferable to include both the hole injection layer 31 and the hole transport layer 32.

[0074] The materials forming 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 commonly used in the art can be used without limitation. In this case, the materials forming the hole injection layer 31 and the hole transport layer 32 may be the same or different.

[0075] The hole injection material may be any hole injection material known in the art, without limitation. Examples of usable hole injection materials 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 suitable polymers include, but are not limited to, PEDOT / PSS (poly(3,4-ethylenedioxythiophene) / poly(4-styrenesulfonate), PANI / DBSA (polyaniline / dodecylbenzenesulfonic acid), PANI / CSA (polyaniline / camphorsulfonic acid), and PANI / PSS (polyaniline) / poly(4-styrenesulfonate). These may be used alone or in combination of two or more.

[0076] The hole transport material may be any hole transport material known in the art. 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)benzenamine]). These may be used alone or in combination.

[0077] The hole transport region 30 may be fabricated by a conventional method known in the art, such as, but not limited to, vacuum deposition, spin coating, casting, Langmuir-Blodgett (LB) printing, inkjet printing, laser printing, and laser induced thermal imaging (LITI).

[0078] Light-emitting layer The light-emitting layer 40 included in the organic material layer (A) of the present invention is a layer in which holes and electrons combine to form excitons, and the color of light emitted by the organic electroluminescent device may vary depending on the material forming the light-emitting layer 40.

[0079] The light-emitting layer 40 may include a host and a dopant, and the mixing ratio thereof can be appropriately adjusted within a range known in the art. For 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.

[0080] 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 art, and examples thereof include, but are not limited to, alkali metal complex compounds; alkaline earth metal complex compounds; and fused aromatic ring derivatives.

[0081] More specifically, it is preferable to use, as the host material, 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 improve the luminous efficiency and lifespan of the organic electroluminescent device.

[0082] 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).

[0083] The dopants can be classified into red dopants, green dopants, and blue dopants, and any red dopants, green dopants, and blue dopants known in the art can be used without any particular limitation.

[0084] Specific examples of red dopants include, but are not limited to, PtOEP (Pt(II) octaethylporphine), Ir(piq) (tris(2-phenylisoquinoline)iridium), BtpIr(acac) (bis(2-(2'-benzothienyl)-pyridinato-N,C3')iridium(acetylacetonate)), or mixtures of two or more thereof.

[0085] Examples of green dopants include Ir(ppy)3 (tris(2-phenylpridine)iridium), Ir(ppy)2(acac) (bis(2-phenylpyridine)(acetylacetonato)iridium(III)), and Ir(mppy)3 (tris(2-(4-tolyl)phenylpridine)iridium). idium), 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 thereof.

[0086] Examples of blue dopants include 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), and the like. perylene), or a mixture of two or more thereof, but are not limited thereto.

[0087] 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. Preferably, the light-emitting layer 40 may be a light-emitting layer containing a blue fluorescent material.

[0088] The light-emitting layer 40 may be a single layer made of one material, a single layer made of multiple different materials, or a multi-layer structure consisting of two or more layers, each made of a different material. When the light-emitting layer 40 is a multi-layer structure, the organic electroluminescent device can emit light of various colors. Specifically, the present invention provides an organic electroluminescent device that includes multiple light-emitting layers made of different materials in series, thereby exhibiting a mixed color. Furthermore, when multiple light-emitting layers are included, the device's driving voltage increases, but the current value within the organic electroluminescent device remains constant, thereby improving the luminous efficiency by the number of light-emitting layers.

[0089] 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.

[0090] The plurality of light-emitting layers included in such a light-emitting stack may emit light of different colors or may emit light of the same color. That is, the emitted color may vary depending on the material constituting the light-emitting layer. For example, the plurality of light-emitting stacks may include materials that emit blue, green, red, yellow, white, etc., and may be formed using phosphorescent or fluorescent materials. In this case, the colors emitted by each light-emitting layer may be complementary to each other. Alternatively, a hue may be selected as a color combination that can emit white light. Each of such light-emitting layers may include a phosphorescent or fluorescent dopant corresponding to the selected hue.

[0091] Although not shown, the organic electroluminescent device 100 may further include a charge generation layer (not shown) disposed between and connecting adjacent stacks among the plurality of light-emitting stacks.

[0092] A charge generation layer (CGL) is a layer that does not directly contact both electrodes (e.g., anode and cathode) in an organic light-emitting device having multiple light-emitting stacks and separates adjacent 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 an anode by generating holes for the other light-emitting stack. Materials known in the art that can be used as charge generation layers (CGLs) can be used without limitation for such a charge generation layer. Materials used for charge generation layers may also be doped with conventional n-type and / or p-type materials known in the art.

[0093] electron transport area In the organic electroluminescent device 100 according to the present invention, the electron transport region 50 contained in the organic layer (A) plays a role in transferring electrons injected from the cathode 20 to the light-emitting layer 40 .

[0094] The electron transport region 50 includes at least two layers, specifically, a hybrid electron transport layer 52 and at least one of an electron injection layer 51 and an electron transport auxiliary layer 53. If necessary, a hole leakage suppression layer (not shown) may be further included.

[0095] Specifically, the electron transport region 50 may have a structure in which a hybrid electron transport layer 52 and an electron injection layer 51 are disposed relative to the light emitting layer 40, or a structure in which an electron transport auxiliary layer 53, a hybrid electron transport layer 52, and an electron injection layer 51 are disposed relative to the light emitting layer 40. In consideration of the characteristics of the organic electroluminescent device, it is preferable that the electron transport auxiliary layer 53, the hybrid electron transport layer (Hybrid-ETL) 52, and the electron injection layer 51 are all disposed.

[0096] The hybrid electron transport layer 52 of the present invention has the above-mentioned dimer LUMO density of states (e.g., LUMO-DOS Dimer ) and its overlapping parameters are satisfied, the detailed structure of the dimer constituting the hybrid-electron transport layer 52, for example, the structure of at least two organic monomers constituting the dimer (e.g., a first monomer and a second monomer), the type of moiety (e.g., an EDG group, an EWG group) and its bonding position contained in the organic monomer, the type of linker and its introduction position, the composition between them, etc., are not particularly limited.

[0097] The hybrid electron transport layer 52 is an organic layer containing a dimer derived from at least two organic monomers and does not contain a metal or metal complex. Here, a dimer is a bimolecular substance formed by the bonding or polymerization of two monomolecules. In this case, the monomolecules include all common organic monomers known in the art that can form dimers.

[0098] The first and second monomers capable of forming a dimer may be conventional monomers known in the art, or they may be different from each other. The first and second organic materials may be co-deposited to form a dimer, and dimers formed by other conventional methods known in the art are also within the scope of the present invention. In this case, the first and second monomers must bond or polymerize with each other to form a more stable dimer. To this end, it is preferable to adjust the first and second monomers to have the following desired physical properties.

[0099] According to one specific example, the difference in absolute value between the LUMO energy level (ET1_LUMO) of the first monomer constituting the hybrid-electron transport layer (Hybrid-ETL) 52 and the LUMO energy level (ET2_LUMO) of the second monomer constituting the hybrid-electron transport layer (Hybrid-ETL) 52 may be more than 0 eV and not more than 2.0 eV, specifically, 0.05 to 1.5 eV.

[0100] According to another specific example, the difference in absolute value of the molecular weight (MW) between the first monomer and the second monomer may be 0 to 600 g / mol, specifically 0 to 400 g / mol.

[0101] According to another specific example, the difference in refractive index between the first monomer and the second monomer may be 0 to 2, specifically 0 to 1.5, in the blue wavelength region of 400 to 470 nm.

[0102] The first and second monomers included in the material of the hybrid electron transport layer 52 may each be a compound having at least one moiety bonded thereto that has electron-withdrawing (EWG) characteristics, which are well known in the art, and specifically, may be a bipolar compound that simultaneously contains a moiety having electron-withdrawing (EWG) characteristics, which has high electron absorption, and a moiety having electron-donating (EDG) characteristics, which has high electron donating properties.

[0103] More specifically, in the hybrid electron transport layer 52, the first and second monomers constituting the dimer may each include at least one electron-withdrawing group (EWG) moiety selected from the group consisting of a 6-membered moiety represented by the following Chemical Formula 1, a 5-membered moiety represented by the following Chemical Formula 2, and a polycyclic moiety formed by condensing the 6-membered moiety and the 5-membered moiety:

[0104] [ka]

[0105] [ka]

[0106] In the above Chemical Formula 1 or 2, X1 to X6 and Y1 to Y5 are the same or different and each independently represent N or C(R), provided that at least one of X1 to X6 and Y1 to Y5 is N; When there are a plurality of C(R), the plurality of R may be the same or different and each independently represent hydrogen, deuterium, 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 60or 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 represented by R each independently represent hydrogen, deuterium (D), halogen, cyano group, nitro group, C1 to C6 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 In this case, when there are a plurality of the substituents, they may be the same or different.

[0107] The first and second monomers constituting the dimer contained in the hybrid electron transport layer 52 each contain at least one nitrogen-containing heteroaromatic ring, i.e., one or more electron-withdrawing groups (EWGs), containing at least one nitrogen (N). Therefore, when the first and second organic compounds having the six- or five-membered moiety represented by Formula 1 or 2 or a polycyclic moiety formed by condensing these moieties are used as materials for the hybrid electron transport layer 52, they can efficiently accept electrons from the cathode 20 and smoothly transfer the electrons to the light-emitting layer 40, thereby reducing the driving voltage of the device 100 and achieving high efficiency and a long lifespan.

[0108] In addition, the dimer material contained in the hybrid electron transport layer 52 not only has high triplet energy, but also has an improved glass transition temperature and high thermal stability due to the molecular weight of the compound being significantly increased by controlling the type and position of various substituents introduced into the mother structure. Furthermore, since it is also effective in suppressing crystallization of the organic material layer, the durability and lifespan of the organic electroluminescent device 100 including the same can be significantly improved.

[0109] According to an embodiment of the present invention, the electron-withdrawing group (EWG) moieties contained in the first monomer and the second monomer may be the same or different and may each independently be further embodied as any one selected from the following structural formula group, but are not limited thereto:

[0110] [ka]

[0111] In the above formula, * indicates the portion where bonding with the first monomer and / or the second monomer constituting the hybrid electron transport layer occurs.

[0112] Although not specifically shown in the structural formula, the compound may be substituted with at least one substituent known in the art (e.g., the same as the definition of R). In addition, although the structural formula shows only one moiety (*) connecting to the compound constituting the hybrid-electron transport layer 52, the case where two moieties are included also falls within the scope of the present invention.

[0113] According to one embodiment of the present invention, the first and second monomers constituting the dimer contained in the hybrid electron transport layer 52 may each contain at least one moiety of a conventional electron donating group (EDG) known in the art, which is different from the electron withdrawing group (EWG) described above and has higher electron donating properties than the electron withdrawing group (EWG).

[0114] The first and second monomers usable as dimer materials for the hybrid electron transport layer 52 according to the present invention described above may be further embodied as the exemplified compounds described below. However, the first and second monomers constituting the hybrid electron transport layer 52 according to the present invention are not limited to the exemplified ones below. In particular, the LUMO density of states (LUMO-DOS) of the dimer Dimer As long as the physical properties such as the overlapping ratio between the two moieties are satisfied, the type of moiety (e.g., EDG group, EWG group), the bonding position thereof, and the position at which the linker is introduced are not particularly limited, and compounds with various modifications of their chemical structures also fall within the scope of the present invention.

[0115] The hybrid electron transport layer 52 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) printing, inkjet printing, laser printing, or laser induced thermal imaging (LITI), but is not limited to these.

[0116] In the electron transport region 50 according to the present invention, the material of the electron transport auxiliary layer 53 and / or the electron injection layer 51 used together with the hybrid electron transport layer (Hybrid-ETL) 52 is not particularly limited as long as it is a material that can easily inject electrons and has high electron mobility, and any electron transport layer / electron transport layer material commonly used in the art can be used without limitation.

[0117] Usable electron injection materials include, but are not limited to, anthracene derivatives, heteroaromatic compounds, and alkali metal complex compounds. Specific examples include LiF, LiO, BaO, NaCl, and CsF; lanthanide metals such as Yb; and metal halides such as RbCl and RbI. These may be used alone or in combination of two or more.

[0118] Furthermore, any material known in the art having normal electron transport properties can be used without limitation for the electron transport assisting layer 53. Examples thereof include oxadiazole derivatives, triazole derivatives, phenanthroline derivatives (e.g., BCP), and nitrogen-containing heterocyclic derivatives.

[0119] The electron transport region 50 according to the present invention, specifically the electron injection layer 51, may be co-deposited with an n-type dopant to facilitate electron injection from the cathode. In this case, any alkali metal complex compound known in the art can be used as the n-type dopant without limitation, and examples thereof include alkali metals, alkaline earth metals, and rare earth metals.

[0120] The electron transport region 50 may be fabricated by a conventional method known in the art, such as, but not limited to, vacuum deposition, spin coating, casting, Langmuir-Blodgett (LB) printing, inkjet printing, laser printing, and laser induced thermal imaging (LITI).

[0121] 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 .

[0122] 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, thereby preventing electrons from moving to the hole transport layer 32, and has high triplet energy, thereby preventing excitons in the light-emitting layer 40 from diffusing to the hole transport layer 32.

[0123] The light-emitting auxiliary layer may include a hole-transporting material and may be made of the same material as the hole-transporting region. Also, the light-emitting auxiliary layers of the red, green, and blue organic light-emitting devices may be made of the same material.

[0124] 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 materials may be used alone or in combination of two or more. The light-emitting auxiliary layer may also contain a p-type dopant in addition to the above-mentioned materials. The p-type dopant may be a p-type dopant known in the art.

[0125] Capping Layer Optionally, the organic electroluminescent device 100 of the present invention may further include a capping layer (not shown) disposed on the cathode 20. The capping layer serves to protect the organic electroluminescent device and to help the light generated from the organic material layer to be efficiently emitted to the outside.

[0126] The capping layer may include 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 materials for forming the capping layer are inexpensive compared to the materials for other layers of the organic light-emitting device.

[0127] Such a capping layer may be a single layer, or may include two or more layers having different refractive indices so that the refractive index gradually changes as the light passes through the two or more layers.

[0128] The capping layer may be manufactured by a conventional method known in the art, for example, a vacuum deposition method, a spin coating method, a casting method, or a Langmuir-Blodgett (LB) method.

[0129] The organic light-emitting device of the present invention having the above-described configuration may be fabricated by a conventional method well known in the art. For example, an anode material may be vacuum-deposited on a substrate, and then a hole transport region material, an emitting layer material, an electron transport region material, and a cathode material may be vacuum-deposited on the anode in this order to fabricate the organic light-emitting device.

[0130] 1 illustrates an example in which a first monomer and a second monomer are used as the dimer contained in the hybrid electron transport layer 52. However, the present invention is not limited to the above-described structure, and it is also within the scope of the present invention to form a dimer or a multimer of at least three organic substances and include the dimer or a multimer of at least three organic substances in the hybrid electron transport layer 52.

[0131] The organic electroluminescent device 100 according to the present invention has a structure in which an anode 10, an organic material layer (A), and a cathode 20 are sequentially stacked, and may further include an insulating layer or an adhesive layer between the anode 10 and the organic material layer (A) or between the cathode 20 and the organic material layer (A). When a voltage, a current, or both are applied, the organic electroluminescent device according to the present invention maintains maximum luminous efficiency and has an increased half-life time of the initial brightness, thereby achieving excellent life characteristics. [Example]

[0132] The present invention will be described in detail below with reference to examples. However, the following examples are merely illustrative of the present invention and are not intended to limit the scope of the present invention.

[0133] [Preparation (calculation) example] The compounds according to the present invention were prepared as follows, and their physical properties were measured by methods known in the art. The results are shown in Table 1 below.

[0134] Schroedinger software release 2022-3 was used to calculate the HOMO, LUMO, singlet (S1), and triplet (T1) energies of the organic materials used in the present invention. Specifically, the basic calculation method for each physical property was the B3LYP (Becke, 3-parameter, Lee-Yang-Parr) functional calculation method in density functional theory (DFT), and the molecular structure was optimized using TZV (triple zeta) as the basis set.

[0135] The HOMO and LUMO energies of each compound were calculated in the optimized ground state (S0), and the singlet (S1) and triplet (T1) energies were calculated using the optimized energy differences between the ground state (S0) / singlet (S1) and ground state (S0) / triplet (T1), respectively.

[0136] The density of states (DOS) was calculated using molecular dynamics and quantum mechanics. First, several hundred molecules were simulated (over 100 ns) using molecular dynamics. Then, the HOMO and LUMO energies of each molecule were extracted using quantum mechanics. The DOS was calculated based on this data, and the overlap between the dimer and the monomer was calculated as a percentage. Furthermore, by comparing the sum of the energies for each monomer with the total energy of the dimer, the possibility of a dimer shape could be easily predicted. Furthermore, taking into account the π-π stacking interaction of the dimer, the calculation was performed for dimers with a distance of 5 Å or less relative to the center of the structure. The dimer calculation was performed using the dispersion-corrected DFT method ωB98XD.

[0137] The bond dissociation energy (BDE), refractive index, and dipole moment were calculated using the B3LYP / TZV method as described above. In particular, the bond dissociation energy was calculated by calculating the energy required to break a specific chemical bond in the molecule, and the smallest BDE value was selected.

[0138] [Table 1]

[0139] The structures of the compounds used in Table 1 above are as follows:

[0140] [ka]

[0141] [ka]

[0142] [Examples 1 to 7] Preparation of blue organic electroluminescent devices Each compound was purified to a high purity by sublimation using a conventional method, and then a blue organic electroluminescent device was fabricated by the following process.

[0143] First, a glass substrate coated with a 1500 Å thick indium tin oxide (ITO) thin film was ultrasonically cleaned in distilled water. After the distilled water cleaning, the substrate was ultrasonically cleaned with solvents such as isopropyl alcohol, acetone, and methanol, dried, and then transferred to a UV ozone cleaner (Powersonic 405, manufactured by HWASHIN TECH) and cleaned using UV for 5 minutes before being transferred to a vacuum deposition machine.

[0144] On the ITO transparent glass substrate (electrode) prepared as described above, HI+2wt% HD(100Å) / HI(1400Å) / HT(50Å) / BH+2wt% BD(200Å) / AE(50Å) / ET1+ET2(300Å_1:1) shown in Table 2 below / LiF(10Å) / Al(1000Å) were laminated in this order to prepare an organic electroluminescent device shown in Table 2 below.

[0145] [Table 2]

[0146] Comparative Example 1: Production of blue organic electroluminescent device A blue organic electroluminescent device of Comparative Example 1 was fabricated in the same manner as in Example 1, except that ET+Liq (300 Å_1:1) was used as the hybrid electron transport layer material instead of the compounds ET1 and ET2.

[0147] For reference, the structures of compounds HI, HD, HT, BH, BD, AE, and ET used in Examples 1 to 7 and Comparative Example 1 are as follows:

[0148] [ka]

[0149] [Evaluation example 1] For the organic electroluminescent devices manufactured in Examples 1 to 7 and Comparative Example 1, a current density of 10 mA / cm 2 The driving voltage and current efficiency were measured, and the results are shown in Table 3 below.

[0150] [Table 3]

[0151] As shown in Table 3, the organic electroluminescent devices of Examples 1 to 7, which have a dimer-containing hybrid electron transport layer controlled to predetermined physical properties, exhibit significantly superior performance in terms of current efficiency and driving voltage compared to the blue organic electroluminescent device of Comparative Example 1, which uses a single organic molecule and a metal complex (Liq) as the electron transport layer material. [Explanation of symbols]

[0152] 100 Organic electroluminescent device A...Organic layer 10...Anode 20...Cathode 30 ···Hole transport region 31 Hole injection layer 32 Hole transport layer 40 Emitting layer 50...electron transport region 51...electron injection layer 52 Hybrid Electron Transport Layer 53...electron transport auxiliary layer

Claims

1. An organic electroluminescent device having an anode, a hole transport region, a light emitting layer, an electron transport region, and a cathode stacked in this order, the electron transport region comprises a hybrid electron transport layer (Hybrid ETL); the hybrid electron transport layer contains a dimer derived from at least two organic materials, the dimer including a first monomer and a second monomer; The LUMO density of states (LUMO-DOS) of the hybrid electron transport layer Ｄｉｍｅｒ )teeth, (i) LUMO density of states 1 (LUMO-DOS) of the first monomer ＥＴ１ ); (ii) LUMO density of states 1-1 (LUMO-DOS) of the first isomorphic dimer ＥＴ１＿ＥＴ１＿Ｄｉｍｅｒ ); (iii) LUMO density of states 2 (LUMO-DOS) of the second monomer ＥＴ２ ); (iv) LUMO density of states 2-2 of the isomorphous second dimer (LUMO-DOS ＥＴ２＿ＥＴ２＿Ｄｉｍｅｒ ); and (v) LUMO density of states 3 (LUMO-DOS) of the heteromorphic third dimer consisting of the first monomer and the second monomer ＥＴ１＿ＥＴ２＿Ｄｉｍｅｒ ); (vi) the absolute value of the LUMO energy level of the first monomer is lower than the absolute value of the LUMO energy level of the second monomer; (vii) LUMO density of states 3 (LUMO-DOS) of the heteromorphic third dimer ＥＴ１＿ＥＴ２＿Ｄｉｍｅｒ ) is the LUMO density of states 1 (LUMO-DOS) of the first monomer. ＥＴ１ ) and the LUMO density of states 2 (LUMO-DOS) of the second monomer ＥＴ２ ) and at least one of the organic electroluminescent element.

2. The LUMO density of states 3 (LUMO-DOS ＥＴ１＿ＥＴ２＿Ｄｉｍｅｒ ) is the density of states 1-1 (LUMO-DOS) of the LUMO of the first isomorphic dimer. ＥＴ１－ＥＴ１ ) and the LUMO density of states 2-2 (LUMO-DOS) of the second isomorphic dimer ＥＴ２－ＥＴ２ 2. The organic electroluminescent device according to claim 1, wherein the organic electroluminescent device overlaps with at least one of the following:

3. The organic electroluminescent device according to claim 1 , wherein a difference in absolute value between a LUMO energy level (ET1_LUMO) of the first monomer and a LUMO energy level (ET2_LUMO) of the second monomer is greater than 0 eV and equal to or less than 2.0 eV.

4. The LUMO density of states 3 (LUMO-DOS ＥＴ１＿ＥＴ２＿Ｄｉｍｅｒ ) and the LUMO density of states 2 (LUMO-DOS) of the second monomer ＥＴ２ 2. The organic electroluminescent device according to claim 1, wherein an overlapping ratio with the first and second layers is more than 0% and 80% or less.

5. 2. The organic electroluminescent device of claim 1, wherein the dimer comprises a first monomer and a second monomer, and is formed by co-deposition of the first monomer and the second monomer.

6. The organic electroluminescent device according to claim 1 , wherein the hybrid electron transport layer is an organic layer that does not contain a metal complex.

7. the electron transport region comprises at least two layers; a hybrid electron transport layer; and The organic electroluminescent device according to claim 1 , comprising at least one of an electron transporting layer and an electron injecting layer.

8. the electron transport auxiliary layer is disposed between the light-emitting layer and the hybrid electron transport layer; The organic electroluminescent device according to claim 7 , wherein the electron injection layer is disposed between the hybrid electron transport layer and the cathode.

9. The LUMO density of states (LUMO-DOS) of the hybrid electron transport layer Ｄｉｍｅｒ 8. The organic electroluminescent device according to claim 7, wherein at least one of the LUMO density of states (LUMO-DOSAETL) of the electron transport supporting layer overlaps with the LUMO density of states (LUMO-DOSAETL) of the electron transport supporting layer.

10. The organic electroluminescent device according to claim 7 , wherein a difference in absolute value between a LUMO energy level of the first monomer and a LUMO energy level of the electron transporting supporting layer is more than 0 eV and 1.5 eV or less.

11. The organic electroluminescent device according to claim 1 , wherein a difference in absolute value between the LUMO energy level of the second monomer and the work function of the cathode is more than 0.5 eV and not more than 2.5 eV.

12. 2. The organic electroluminescent device of claim 1, wherein the difference in absolute value of the molecular weight (MW) between the first monomer and the second monomer is 0 to 600 g / mol.

13. 2. The organic electroluminescent device according to claim 1, wherein the triplet energy (T1) of the hybrid-electron transport layer (Hybrid-ETL) is 1.5 eV or more.

14. 2. The organic electroluminescent device according to claim 1, wherein the singlet energy (S1) of the hybrid-electron transport layer (Hybrid-ETL) is 2.0 eV or more.

15. 2. The organic electroluminescent device according to claim 1, wherein the absolute value of the HOMO energy of the hybrid-electron transport layer (Hybrid-ETL) is 4.0 eV or more.

16. 2. The organic electroluminescent device of claim 1, wherein the lowest energy level of the ground state bond dissociation energy (BDE) of the hybrid-electron transport layer (Hybrid-ETL) is 0.8 eV or more.

17. 2. The organic electroluminescent device according to claim 1, wherein the hybrid-electron transport layer (Hybrid-ETL) has a refractive index (n) of 0.7 or more in a blue wavelength region of 400 to 470 nm.

18. 2. The organic electroluminescent device according to claim 1, wherein a difference in refractive index between the first monomer and the second monomer is 0 to 2 in a blue wavelength region of 400 to 470 nm.

19. 2. The organic electroluminescent device of claim 1, wherein the hybrid-electron transport layer (Hybrid-ETL) has a dipole moment greater than zero.

20. 2. The organic electroluminescent device of claim 1, wherein the hybrid-electron transport layer (Hybrid-ETL) has an electron affinity (EA) of 0.2 eV or more.

21. The hybrid electron transport layer (Hybrid-ETL) has a zero-field conductivity of at least 1×10 －８ cm ２ 2. The organic electroluminescent device according to claim 1, having an electron mobility (μ) of 1 / Vs or more.

22. 2. The organic electroluminescent device according to claim 1, wherein the light-emitting layer comprises a host and a dopant, and the mixing ratio of the host to the dopant is 70 to 99.5:0.5 to 30 by weight.

23. The organic electroluminescent device of claim 1 , wherein the organic electroluminescent device comprises a plurality of light-emitting layer stacks including at least one light-emitting layer.

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