Organic electroluminescent element

Abstract

To provide an organic electroluminescent element which can exercise a high light-emission efficiency, a low driving voltage, and a long life at the same time.SOLUTION: A light-emitting layer 320 includes a plurality of hosts and dopants. One of the hosts is made of the same material as that of an electron transfer support layer 331 in an electron transfer region 330.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an organic electroluminescent device that simultaneously exhibits high luminous efficiency, low driving voltage, long life, etc.

Background Art

[0002] Generally, in an organic electroluminescent device (hereinafter referred to as "organic EL device"), 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. The injected holes and electrons combine to generate excitons, and light is emitted when these excitons return to the ground state.

[0003] Such an organic EL device is classified into a fluorescent EL device in which singlet excitons contribute to light emission and a phosphorescent EL device in which triplet excitons contribute to light emission depending on the electron spin state of the excitons.

[0004] In the case of a fluorescent EL device, theoretically, the maximum internal quantum efficiency is limited to about 25% depending on the generation rate, but in the case of a phosphorescent EL device, the internal quantum efficiency can be up to 100%. In the case of phosphorescence, the triplet and singlet states are involved in the internal quantum efficiency to obtain a high internal quantum efficiency. However, in the case of fluorescence, since only singlet transitions occur, the maximum internal quantum efficiency is only one-fourth of that of phosphorescence. Thus, theoretically, the phosphorescent EL device has a higher luminous efficiency than fluorescence.

[0005] However, unlike green and red phosphorescent EL devices, blue phosphorescent EL devices have insufficient development levels regarding phosphorescent dopants with high deep blue color purity and high efficiency, and hosts with a wide energy gap, and have not been commercialized. Therefore, instead of blue phosphorescent EL, ​​​​​​​A blue fluorescent EL element is used.

[0006] In recent years, due to the trend of increasing size and resolution of displays, there is a demand for the development of organic EL elements having high efficiency and long life. In particular, the increase in the resolution of a display can be realized by forming more pixels in the same area. As a result, the light-emitting area of the organic EL element decreases, and such a decrease in the light-emitting area causes a reduction in the life of the organic EL element. Therefore, various studies have been conducted to improve the characteristics of organic EL elements, but satisfactory results have not been obtained so far.

Summary of the Invention

Problems to be Solved by the Invention

[0007] An object of the present invention is to provide an organic electroluminescent element having effects such as a low driving voltage, high luminous efficiency, and long life by including a plurality of hosts and dopants in a light-emitting layer, and one of the plurality of hosts including the same material as the material of an electron transport auxiliary layer.

Means for Solving the Problems

[0008] To achieve the above object, the present invention includes an anode; a cathode disposed opposite to the anode; and an organic layer interposed between the anode and the cathode and including a hole transport region, a light-emitting layer, and an electron transport region sequentially disposed on the anode, wherein the electron transport region includes an electron transport auxiliary layer, an electron transport layer, and an electron injection layer sequentially disposed on the light-emitting layer, the light-emitting layer includes a plurality of hosts and dopants, and one of the plurality of hosts is made of the same material as the material of the electron transport auxiliary layer, and provides an organic electroluminescent element.

Effects of the Invention

[0009] In the present invention, a light-emitting layer including a plurality of hosts and dopants is provided, and among the plurality of hosts by applying the same material as the material of the electron transport auxiliary layer to one of them, an organic electroluminescent device having effects such as a low driving voltage , high luminous efficiency, and long life can be provided.

[0010] Further, by applying the organic electroluminescent device of the present invention to a display panel, a display panel with improved performance and life can be provided.

Brief Description of Drawings

[0011]

Figure 1

Figure 2

Figure 3

Figure 4

Description of Reference Numerals

[0012] 100: Anode, 200: Cathode, 300: Organic layer, 310: Hole transport region, 311: Hole injection layer, 312: Hole transport layer, 313: Hole transport auxiliary layer, 320: Light-emitting layer, 330: Electron transport region, 331: Electron transport auxiliary layer, 332: Electron transport layer, 333: Electron injection layer

Embodiments for Carrying Out the Invention

[0013] The advantages and features of the present invention, and the method for achieving them, will become clear by referring to the embodiments described in detail below together with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, and is embodied in various different forms, and the following embodiments are merely provided so that the disclosure of the present invention is complete and that those with ordinary knowledge in the technical field to which the present invention pertains are fully informed of the scope of the invention. The present invention is defined only by the scope of the claims. Therefore, in some embodiments, well-known element structures and well-known techniques, such as well-known process steps, are not specifically described in order to avoid the present invention being ambiguously interpreted. Throughout the specification, the same reference numerals refer to the same components. Without further definition, all terms (including technical and scientific terms) used in this specification can be used in a commonly understood meaning by those with ordinary knowledge in the technical field to which the present invention pertains. Terms defined in commonly used dictionaries should not be ideally or overly interpreted unless otherwise described. The organic electroluminescent device according to the present invention includes an anode; a cathode disposed opposite to the anode; and one or more organic layers interposed between the anode and the cathode and including a hole transport region, a light-emitting layer, and an electron transport region; and applies the material of the electron transport auxiliary layer in the electron transport region to one of the plurality of hosts in the light-emitting layer. Thereby, the organic electroluminescent device of the present invention can have characteristics of a low driving voltage, a high luminous efficiency, and a long lifespan. However, the present invention is not limited to the embodiments disclosed below, and is embodied in various different forms, and the following embodiments are merely provided so that the disclosure of the present invention is complete and that those with ordinary knowledge in the technical field to which the present invention pertains are fully informed of the scope of the invention. The present invention is defined only by the scope of the claims. Therefore, in some embodiments, well-known element structures and well-known techniques, such as well-known process steps, are not specifically described in order to avoid the present invention being ambiguously interpreted. Throughout the specification, the same reference numerals refer to the same components. However, the present invention is not limited to the embodiments disclosed below, and is embodied in various different forms, and the following embodiments are merely provided so that the disclosure of the present invention is complete and that those with ordinary knowledge in the technical field to which the present invention pertains are fully informed of the scope of the invention. The present invention is defined only by the scope of the claims. Therefore, in some embodiments, well-known element structures and well-known techniques, such as well-known process steps, are not specifically described in order to avoid the present invention being ambiguously interpreted. Throughout the specification, the same reference numerals refer to the same components. However, the present invention is not limited to the embodiments disclosed below, and is embodied in various different forms, and the following embodiments are merely provided so that the disclosure of the present invention is complete and that those with ordinary knowledge in the technical field to which the present invention pertains are fully informed of the scope of the invention. The present invention is defined only by the scope of the claims. Therefore, in some embodiments, well-known element structures and well-known techniques, such as well-known process steps, are not specifically described in order to avoid the present invention being ambiguously interpreted. Throughout the specification, the same reference numerals refer to the same components. However, the present invention is not limited to the embodiments disclosed below, and is embodied in various different forms, and the following embodiments are merely provided so that the disclosure of the present invention is complete and that those with ordinary knowledge in the technical field to which the present invention pertains are fully informed of the scope of the invention. The present invention is defined only by the scope of the claims. Therefore, in some embodiments, well-known element structures and well-known techniques, such as well-known process steps, are not specifically described in order to avoid the present invention being ambiguously interpreted. Throughout the specification, the same reference numerals refer to the same components. However, the present invention is not limited to the embodiments disclosed below, and is embodied in various different forms, and the following embodiments are merely provided so that the disclosure of the present invention is complete and that those with ordinary knowledge in the technical field to which the present invention pertains are fully informed of the scope of the invention. The present invention is defined only by the scope of the claims. Therefore, in some embodiments, well-known element structures and well-known techniques, such as well-known process steps, are not specifically described in order to avoid the present invention being ambiguously interpreted. Throughout the specification, the same reference numerals refer to the same components.

[0014] Without further definition, all terms (including technical and scientific terms) used in this specification can be used in a commonly understood meaning by those with ordinary knowledge in the technical field to which the present invention pertains. Terms defined in commonly used dictionaries should not be ideally or overly interpreted unless otherwise described. Without further definition, all terms (including technical and scientific terms) used in this specification can be used in a commonly understood meaning by those with ordinary knowledge in the technical field to which the present invention pertains. Terms defined in commonly used dictionaries should not be ideally or overly interpreted unless otherwise described. Without further definition, all terms (including technical and scientific terms) used in this specification can be used in a commonly understood meaning by those with ordinary knowledge in the technical field to which the present invention pertains. Terms defined in commonly used dictionaries should not be ideally or overly interpreted unless otherwise described. Without further definition, all terms (including technical and scientific terms) used in this specification can be used in a commonly understood meaning by those with ordinary knowledge in the technical field to which the present invention pertains. Terms defined in commonly used dictionaries should not be ideally or overly interpreted unless otherwise described.

[0015] The organic electroluminescent device according to the present invention includes an anode; a cathode disposed opposite to the anode; and one or more organic layers interposed between the anode and the cathode and including a hole transport region, a light-emitting layer, and an electron transport region; and applies the material of the electron transport auxiliary layer in the electron transport region to one of the plurality of hosts in the light-emitting layer. Thereby, the organic electroluminescent device of the present invention can have characteristics of a low driving voltage, a high luminous efficiency, and a long lifespan. The organic electroluminescent device according to the present invention includes an anode; a cathode disposed opposite to the anode; and one or more organic layers interposed between the anode and the cathode and including a hole transport region, a light-emitting layer, and an electron transport region; and applies the material of the electron transport auxiliary layer in the electron transport region to one of the plurality of hosts in the light-emitting layer. Thereby, the organic electroluminescent device of the present invention can have characteristics of a low driving voltage, a high luminous efficiency, and a long lifespan. The organic electroluminescent device according to the present invention includes an anode; a cathode disposed opposite to the anode; and one or more organic layers interposed between the anode and the cathode and including a hole transport region, a light-emitting layer, and an electron transport region; and applies the material of the electron transport auxiliary layer in the electron transport region to one of the plurality of hosts in the light-emitting layer. Thereby, the organic electroluminescent device of the present invention can have characteristics of a low driving voltage, a high luminous efficiency, and a long lifespan. The organic electroluminescent device according to the present invention includes an anode; a cathode disposed opposite to the anode; and one or more organic layers interposed between the anode and the cathode and including a hole transport region, a light-emitting layer, and an electron transport region; and applies the material of the electron transport auxiliary layer in the electron transport region to one of the plurality of hosts in the light-emitting layer. Thereby, the organic electroluminescent device of the present invention can have characteristics of a low driving voltage, a high luminous efficiency, and a long lifespan. The organic electroluminescent device according to the present invention includes an anode; a cathode disposed opposite to the anode; and one or more organic layers interposed between the anode and the cathode and including a hole transport region, a light-emitting layer, and an electron transport region; and applies the material of the electron transport auxiliary layer in the electron transport region to one of the plurality of hosts in the light-emitting layer. Thereby, the organic electroluminescent device of the present invention can have characteristics of a low driving voltage, a high luminous efficiency, and a long lifespan.

[0016] Specifically, in the organic electroluminescent device of the present invention, the light-emitting layer includes a plurality of hosts, for example, mutually different first host and second host, thereby improving the recombination efficiency of holes and electrons while preventing the phenomenon that excitons transferred from the host to the dopant move back to the host. It can be prevented.

[0017] At this time, an electron transport auxiliary layer is disposed between the light-emitting layer and the electron transport layer, and any one of the plurality of hosts is the same as the material of the electron transport auxiliary layer, so that the electron injection barrier between the light-emitting layer and the electron transport layer is lowered, and a barrier-free effect is exerted between the light-emitting layer and the electron transport auxiliary layer, and electrons injected from the electron transport layer can be smoothly supplied to the light-emitting layer through the electron transport auxiliary layer. As a result thereby, the organic electroluminescent device of the present invention has improved luminous efficiency, low driving voltage, and significantly improved lifetime characteristics. Thereby, the electrons injected from the electron transport layer can be smoothly supplied to the light-emitting layer through the electron transport auxiliary layer. As a result thereby, the organic electroluminescent device of the present invention has improved luminous efficiency, low driving voltage, and significantly improved lifetime characteristics. is significantly improved.

[0018] Hereinafter, a preferred embodiment of the organic electroluminescent device according to the present invention will be described with reference to the accompanying drawings. It should be noted that the embodiments of the present invention can be implemented with various modifications, and the scope of the present invention is not limited to the subsequent embodiments. is not limited to the following embodiments.

[0019] FIG. 1 is a cross-sectional view schematically showing the structure of an organic light-emitting device according to an embodiment, and FIG. 2 is a cross-sectional view schematically showing the structure of an organic light-emitting device according to another embodiment.

[0020] Referring to FIGS. 1 and 2, the organic electroluminescent device sequentially includes an anode 100, one or more organic layers 300, and a cathode 200, and the organic layer 300 It includes a hole transport region 310, a light emitting layer 320, and an electron transport region 330. Optionally, the above described organic light emitting device may further include a capping layer (not shown) disposed on the second electrode 200. It can be included therein.

[0021] Hereinafter, each component of the organic light emitting device according to the present invention will be described in detail.

[0022] (1) Anode The organic electroluminescent device of the present invention includes an anode 100. The above anode 100 is disposed on a substrate, electrically connected to a driving thin film transistor, and can receive a driving current from the driving thin film transistor. Such an anode 100 is formed of a material with a relatively high work function, so that holes are injected into an adjacent organic layer, that is, into the hole transport region 310 (for example, the hole injection layer 311).

[0023] The material for forming such an anode is not particularly limited, and those well-known in the art can be used. For example, metals such as vanadium, chromium, copper, zinc, gold; alloys of these; metal oxides such as zinc oxide, indium oxide, indium tin oxide (ITO), indium zinc oxide (IZO); combinations of metals and oxides such as ZnO:Al, SnO 2 :Sb; conductive polymers such as polythiophene, poly(3-methylthiophene), poly[3,4-(ethylene-1,2-dioxy)thiophene] (PEDT), polypyrrole, polyaniline; and carbon black, etc., but not limited thereto.

[0024] The method for manufacturing the above anode is not particularly limited, and it can be manufactured by a conventional method well-known in the art. It can be formed by coating the above anode material on a substrate by a known thin film forming method such as sputtering method, ion plating method, vacuum evaporation method, spin coating method, etc. It can be formed by coating the above anode material on a substrate by a known thin film forming method such as sputtering method, ion plating method, vacuum evaporation method, spin coating method, etc. It can be done.

[0025] The above substrate is a plate-like member that supports the organic electroluminescent element. For example, silicon wafers, quartz, glass plates, metal plates, plastic films, and sheets, etc. can be mentioned, but it is not limited to these.

[0026] (2) Cathode In the organic electroluminescent element of the present invention, the cathode 200 is arranged opposite to the anode and is specifically arranged on the electron transport region 330. Such a cathode 20 0 is made of a material with a relatively low work function, so electrons are injected into the adjacent organic layer, that is, the electron transport region 330 (for example, the electron injection layer 333).

[0027] The material for forming such a cathode is not particularly limited, and those well-known in the art can be used For example, metals such as magnesium, calcium, sodium, potassium, titanium um, indium, yttrium, lithium, gadolinium, aluminum, silver (Ag) , tin, lead, etc.; alloys of these; and multi-layer structured 2 materials such as LiF / Al, LiO / Al, etc. can be mentioned, but it is not limited to these.

[0028] The method for manufacturing the above cathode is not particularly limited. Similar to the anode, it can be manufactured by a conventional method well-known in the art For example, by the above-mentioned thin film forming method, the above cathode material is coated on one or more of the following organic layers 300, specifically on the electron transport region, for example, the electron injection layer 333 above. It can be formed by coating.

[0029] (3) Organic layer In the organic electroluminescent device of the present invention, one or more organic layers 300 are disposed between the anode 100 and the cathode 200.

[0030] Such an organic layer 300 includes a hole transport region 310, a light emitting layer 320, and an electron transport region 330.

[0031] As an example, as shown in FIG. 1, one or more organic layers 300 are sequentially disposed on the anode 1000 and include a hole injection layer 311, a hole transport layer 312, a hole transport auxiliary layer 313, a light emitting layer 320, an electron transport auxiliary layer 331, an electron transport layer 332, and an electron injection layer 333. It can be. done.

[0032] As another example, as shown in FIG. 2, one or more organic layers 300 are sequentially disposed on the anode 100 and include a hole main injection layer 311, a hole transport layer 312, a hole transport auxiliary layer 313, a light emitting layer 320, an electron transport auxiliary layer 331, an electron transport layer 332, and an electron injection layer 333. It can be done.

[0033] Hereinafter, each organic layer will be described.

[0034] 1) Hole transport region In the organic light emitting device 100 of the present invention, the hole transport region 310 is a part of the organic layer 300 disposed on the anode 100, and plays a role of moving holes injected from the anode 100 to another adjacent organic layer, specifically the light emitting layer 320. Such a hole transport region 310 can include one or more selected from the group consisting of a hole injection layer 311, a hole transport layer 312, and a hole transport auxiliary layer 313. be included.

[0035] As an example, as shown in FIG. 1, the hole transport region 310 can include a hole injection layer 311 and a hole transport layer 312 that are sequentially stacked on the anode 100. It can include a hole injection layer 311 and a hole transport layer 312 that are sequentially stacked.

[0036] As another example, as shown in FIG. 2, the hole transport region 310 can include a hole injection layer 311, a hole transport layer 312, and a hole transport auxiliary layer 313 that are sequentially stacked on the anode 100. It can include a hole injection layer 311, a hole transport layer 312, and a hole transport auxiliary layer 313 that are sequentially stacked. It can be like this.

[0037] As the materials for forming the hole injection layer 311 and the hole transport layer 312 of the present invention, there is no particular limitation as long as they are materials with a low hole injection barrier and a high hole mobility, and the materials of the hole injection layer / transport layer used in the art can be used without limitation. In addition, the materials for forming the hole injection layer 311 and the hole transport layer 312 can be the same as or different from each other. As long as the hole injection barrier is low and the hole mobility is high, there is no particular limitation, and the materials of the hole injection layer / transport layer used in the art can be used without limitation. Note that the materials for forming the hole injection layer 311 and the hole transport layer 312 can be the same as or different from each other. Specifically, the hole injection layer 311 contains a hole injection material known in the art. As the hole injection material, for example, phthalocyanine compounds such as copper phthalocyanine; DNTP D(N,N'-diphenyl-N,N'-bis-[4-(phenyl-m-tolyl-amino)

[0038] -phenyl]-biphenyl-4,4'-diamine), m-MTDATA(4,4',4' '-tris(3-methylphenylphenylamino)triphenylamine), TDATA( 4,4',4''-tris(N,N-diphenylamino)triphenylamine), 2TN ATA(4,4',4''-tris{N,-(2-naphthyl)-N-phenylamino}- -biphenyl-4,4'-diamine), m-MTDATA(4,4',4' '-tris(3-methylphenylphenylamino)triphenylamine), TDATA( 4,4',4''-tris(N,N-diphenylamino)triphenylamine), 2TN ATA(4,4',4''-tris{N,-(2-naphthyl)-N-phenylamino}- Triphenylamine), PEDOT / PSS (poly(3,4-ethylenedioxythiophene ) / poly(4-styrenesulfonate), PANI / DBSA (polyaniline / dodecyl benzenesulfonic acid), PANI / CSA (polyaniline / camphorsulfonic acid), PANI / PSS ((polyaniline) / poly(4-styrenesulfonate)) and the like can be mentioned, but are not limited thereto. These can be used alone or in a mixture of two or more types.

[0039] The above hole transport layer 312 contains a hole transport material known in the art. The above hole transport materials include, for example, carbazole-based derivatives such as N-phenylcarbazole and polyvinylcarbazole; fluorene-based derivatives; amine-based derivatives; TPD ( N,N’-bis(3-methylphenyl)-N,N’-diphenyl-[1,1-biphenyl -4,4’-diamine), TCTA (4,4’,4’’-tris(N-carbazolyl) triphenylamine) and other triphenylamine-based derivatives such as NPB (N,N’-di (1-naphthyl)-N,N’-diphenylbenzidine), TAPC (4,4’-cyclohe xylylidene bis[N,N’-bis(4-methylphenyl)benzenamine]) and the like can be mentioned, but are not limited thereto. These can be used alone or in a mixture of two or more types.

[0040] The above hole transport auxiliary layer 313 can prevent excitons or electrons generated in the light emitting layer 320 from diffusing (moving) into the hole transport region 310. As the material of such a hole transport auxiliary layer 313, any material having hole transport characteristics well-known in the art can be used without limitation in this regard. if it has hole transport characteristics well-known in the art. Yes, for example, it can be the hole transporting material described above.

[0041] The above-described hole transport region 310 can be manufactured by a conventional method well-known in the art. For example, vacuum evaporation method, spin coating method, casting method, LB (Langmuir-Blod gett) method, inkjet printing method, laser printing method, laser thermal transfer method (Las er Induced Thermal Imaging, LITI), etc. can be mentioned but are not limited thereto.

[0042] 2) Light-emitting layer In the organic electroluminescent device of the present invention, the light-emitting layer 320 is a part of the organic layer 300 interposed between the anode 100 and the cathode 200, and is specifically disposed on the above-described hole transport region 320 . Specifically, the light-emitting layer 320 is disposed on the hole transport layer 312 or on the hole transport auxiliary layer 3 13 (see FIGS. 1 and 2). Such a light-emitting layer 320 is a layer in which holes and electrons respectively injected from the anode and the cathode are combined to form excitons, and the color of the light emitted by the organic electroluminescent device can change depending on the material forming the light-emitting layer 320. The light-emitting layer 320 of the present invention contains a plurality of hosts and dopants. At this time, any one of the plurality of hosts

[0043] is the same as the material forming the electron transport auxiliary layer (hereinafter referred to as "electron transport auxiliary layer material").

[0044] As an example, the plurality of hosts can include a first host that is the same as the electron transport auxiliary layer material and a second host that is different from the first host. In this way, when one of the plurality of hosts is the same as the electron transport auxiliary layer material, between the light-emitting layer and the electron transport auxiliary layer The barrier-free effect is achieved, and the device can obtain low driving voltage, high luminous efficiency, and long lifespan characteristics. obtained.

[0045] The first host of the present invention is made of the same material as the electron transport auxiliary layer material. Specifically, the first host is a compound containing one or more moieties selected from the group consisting of the moieties represented by the following Chemical Formula 1 and Chemical Formula 2, and more specifically, is a compound represented by any one of the following Chemical Formulas 4 to 6, and even more specifically, may be selected from the group consisting of the compounds represented by the following Chemical Formulas A-1 to A-16. For example, the first host may be selected from the group consisting of the compounds represented by the following Chemical Formulas B-1 to B-9. As an example, the first host of the present invention may be any one of the following Compounds 1 to 14 obtained. Such compounds will be described in detail in the part of the electron transport auxiliary layer described later. As an example, the first host of the present invention is any one of the following Compounds 1 to 14 obtained. Such compounds will be described in detail in the part of the electron transport auxiliary layer described later.

[0046] The second host of the present invention is different from the first host described above, and is not particularly limited as long as it is known as a host material in the art. For example, it may include alkali metal complex compounds; alkaline earth metal complex compounds; or condensed aromatic ring derivatives, etc., but is not limited thereto. Specifically, examples of the second host include aluminum complex compounds, beryllium complex compounds, iridium compounds, anthracene derivatives, pyrene derivatives, triphenylene derivatives, carbazole derivatives, dibenzofuran derivatives, dibenzothiophene derivatives, fluorene derivatives, nitrogen-containing heterocyclic derivatives, or combinations of one or more of these, which can improve the luminous efficiency and lifespan of the organic electroluminescent device. derivatives, or combinations of one or more of these.

[0047] However, in the present invention, the number of excitons in the light-emitting layer is significantly increased and the back migration of excitons is improved. In order to prevent this phenomenon, when selecting the second host, the HOMO energy of the first host is It is necessary to take into account differences in physical properties such as energy level difference and LUMO energy level difference.

[0048] In one example, the second host can be a material that satisfies relationships 1 and 2 below:

[0049]

number

[0050] Specifically, the absolute value of the LUMO energy level of the second host and the absolute value of the LUMO energy level of the first host The difference between the absolute value of the LUMO energy level of is in the range of more than 0 eV to 1.0 eV or less, The absolute value of the HOMO energy level of the second host and the HOMO energy level of the first host are The difference from the absolute value of the energy level can be in the range of more than 0 eV to 1.0 eV or less.

[0051] Among the above multiple hosts, the host that is the same as the electron transport auxiliary layer material (for example, the first host The content of the host may be in the range of about 30 to 90% by weight based on the total amount of the entire host. As an example, a first host in which the plurality of hosts are the same as the electron transport auxiliary layer material and the first In the case where a second host different from the first host is included, the use of the first host and the second host The usage ratio is not particularly limited and can be, for example, a weight ratio of 30:70 to 90:10. Also, when the usage ratio of the first host and the second host is within the above range, while further improving the barrier-free effect between the light-emitting layer and the electron transport auxiliary layer, the phenomenon of reverse transfer of excited electrons from the dopant to the host can be more efficiently prevented.

[0052] Optionally, the light-emitting layer of the present invention can further include one or more other hosts (for example, a third host) different from the above-described first host and second host. At this time, since the example of the third host is the same as that of the second host, the description thereof is omitted.

[0053] In the light-emitting layer of the present invention, the dopant is not particularly limited as long as it is well-known in the art. Such dopants are classified into fluorescent dopants and phosphorescent dopants. However, the phosphorescent dopant can be an organometallic complex containing Ir, Pt, Os, Re, Ti, Zr, Hf, or a combination of two or more of these, but is not limited thereto.

[0054] In addition, the above dopants are classified into red dopants, green dopants, and blue dopants, and well-known red dopants, green dopants, and blue dopants in the art can be used without particular limitation.

[0055] Specifically, examples of the above red dopants include, for example, PtOEP (Pt(II)octa ethylporphine: Pt(II) octaethylporphine), Ir(piq) 3 (tris(2-phenylisoquinoline)iridium: tris( 2-phenylquinoline) iridium), Btp2 Ir(acac)(bis(2-(2’ -benzothienyl)-pyridinato-N,C3’)iridium( acetylacetonate): bis(2-(2'-benzothienyl)pyridinato- N,C3’)iridium(acetylacetonate)), and the like, but are not limited thereto. These can be used alone or in combination of two or more thereof.

[0056] In addition, examples of the green dopant include, for example, Ir(ppy) 3 (tris(2-ph enylpyridine)iridium: tris(2-phenylpyridine)iridium ), Ir(ppy) 2 (acac)(Bis(2-phenylpyridine)( Acetylacetonato)iridium(III): bis(2-phenylpyr idine)(acetylacetonato)iridium(III)), Ir(mppy) 3 (tris- (2-(4-tolyl)phenylpyridine)iridium: tris(2 -(4-tolyl)phenylpyridine)iridium), C545T(10-(2-benz othiazolyl)-1,1,7,7-tetramethyl-2,3,6,7- tetrahydro-1H,5H,11H-[1]benzopyrano[6,7, 8-ij]-quinolizin-11-one: 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), and the like, but are not limited thereto. These can be used alone or in combination of two or more thereof. It is possible.

[0057] In addition, as the above blue dopant, for example, F 2 Irpic (Bis[3,5-di fluoro-2-(2-pyridyl)phenyl](picolinato)i ridium)(III): Bis[3,5-difluoro-2-(2-pyridyl)phenyl (picolinato)iridium(III)), (F 2 ppy) 2 Ir(tmd), Ir(d fppz) 3 、DPVBi(4,4’-bis(2,2’-diphenylethen -1-yl)biphenyl: 4,4’-bis(2,2’-diphenylethene-1-yl )biphenyl), DPAVBi(4,4’-Bis[4-(diphenylamin o)styryl]biphenyl: 4,4’-bis(4-diphenylaminostyryl )biphenyl), TBPe(2,5,8,11-tetra-tert-butylpe rylene: 2,5,8,11-tetra-tert-butylperylene), etc. can be mentioned However, it is not limited to these. These can be used alone or in combination of two or more It is possible.

[0058] The content of such a dopant is not particularly limited and can be appropriately adjusted within the range known in the art It is possible.

[0059] As an example, based on the total amount of the light-emitting layer, the plurality of hosts and dopants can be contained in a weight ratio of 70:30 ~99.9:0.1. Specifically, when the light-emitting layer 320 is blue fluorescence , green fluorescence, or red fluorescence, the plurality of hosts and dopants are 80:20~9 It can be included in a weight ratio of 9.9:0.1. Also, when the light-emitting layer 320 is blue fluorescence, green fluorescence, or red phosphorescence, the plurality of hosts and dopants can be included in a weight ratio of 70:30 to 99:1. When the light-emitting layer 320 is blue fluorescence, green fluorescence, or red phosphorescence, the plurality of hosts and dopants can be included in a weight ratio of 70:30 to 99:1. It can be included in a weight ratio of 70:30 to 99:1.

[0060] As another example, the content of the dopant can be in the range of about 0 to 30 parts by weight, specifically more than 0 parts by weight to 20 parts by weight, more specifically about 0.1 to 15 parts by weight, based on 100 parts by weight in total of the first host and the second host. As another example, the content of the dopant can be in the range of about 0 to 30 parts by weight, specifically more than 0 parts by weight to 20 parts by weight, more specifically about 0.1 to 15 parts by weight, based on 100 parts by weight in total of the first host and the second host. It can be in the range of about 0.1 to 15 parts by weight.

[0061] The above-described light-emitting layer 320 can be a single layer or composed of two or more layers. When the light-emitting layer 320 is a plurality of layers, the organic electroluminescent device can emit various colors of light. Specifically, the present invention can provide an organic electroluminescent device that exhibits a mixed color by providing a plurality of light-emitting layers made of different materials in series. When including a plurality of light-emitting layers, although the driving voltage of the device increases, the current value in the organic electroluminescent device becomes constant, and an organic electroluminescent device with improved luminous efficiency by the number of light-emitting layers can be provided. When the light-emitting layer 320 is a plurality of layers, the organic electroluminescent device can emit various colors of light. Specifically, the present invention can provide an organic electroluminescent device that exhibits a mixed color by providing a plurality of light-emitting layers made of different materials in series. When including a plurality of light-emitting layers, although the driving voltage of the device increases, the current value in the organic electroluminescent device becomes constant, and an organic electroluminescent device with improved luminous efficiency by the number of light-emitting layers can be provided. Specifically, the present invention can provide an organic electroluminescent device that exhibits a mixed color by providing a plurality of light-emitting layers made of different materials in series. When including a plurality of light-emitting layers, although the driving voltage of the device increases, the current value in the organic electroluminescent device becomes constant, and an organic electroluminescent device with improved luminous efficiency by the number of light-emitting layers can be provided. When including a plurality of light-emitting layers, although the driving voltage of the device increases, the current value in the organic electroluminescent device becomes constant, and an organic electroluminescent device with improved luminous efficiency by the number of light-emitting layers can be provided. It can provide an organic electroluminescent device with improved luminous efficiency by the number of light-emitting layers.

[0062] Such a light-emitting layer 320 can be manufactured by a conventional method well-known in the art. For example, the vacuum evaporation method, spin coating method, casting method, LB (Langmuir-Blodgett) method, inkjet printing method, laser printing method, laser thermal transfer method (Laser Induced Thermal Imaging, LITI), etc. can be mentioned, but it is not limited thereto. As an example, the light-emitting layer is formed by mixing a plurality of hosts (for example, the first host and the second host) with each other and co-depositing them. For example, the vacuum evaporation method, spin coating method, casting method, LB (Langmuir-Blodgett) method, inkjet printing method, laser printing method, laser thermal transfer method (Laser Induced Thermal Imaging, LITI), etc. can be mentioned, but it is not limited thereto. For example, the vacuum evaporation method, spin coating method, casting method, LB (Langmuir-Blodgett) method, inkjet printing method, laser printing method, laser thermal transfer method (Laser Induced Thermal Imaging, LITI), etc. can be mentioned, but it is not limited thereto. For example, the vacuum evaporation method, spin coating method, casting method, LB (Langmuir-Blodgett) method, inkjet printing method, laser printing method, laser thermal transfer method (Laser Induced Thermal Imaging, LITI), etc. can be mentioned, but it is not limited thereto. As an example, the light-emitting layer is formed by mixing a plurality of hosts (for example, the first host and the second host) with each other and co-depositing them. As an example, the light-emitting layer is formed by mixing a plurality of hosts (for example, the first host and the second host) with each other and co-depositing them. It is formed by co-depositing them.

[0063] 3) Electron transport region In the organic electroluminescent device according to the present invention, the electron transport region 330 is an organic layer disposed on the light-emitting layer 320, and moves electrons injected from the cathode 200 to the light-emitting layer 320. Such an electron transport region 330 includes an electron transport auxiliary layer 331, an electron transport layer 332, and an electron injection layer 333, which are sequentially disposed on the light-emitting layer 320.

[0064]

[0065] The electron transport auxiliary layer 331 according to the present invention can easily move electrons from the electron transport layer 332 to the light-emitting layer 320, while preventing excitons generated in the light-emitting layer 320 and holes injected into the light-emitting layer 320 from diffusing (moving) to the electron transport layer 332. The material forming such an electron transport auxiliary layer 331 is not particularly limited as long as it has a low electron injection barrier and a high electron mobility, and those known in the art can be used without limitation.

[0066] However, in the present invention, in order to exhibit a barrier-free effect between the light-emitting layer and the electron transport auxiliary layer, the electron transport auxiliary layer material is the same material as one of the plurality of hosts in the light-emitting layer (for example, the first host). In particular, among the plurality of hosts in the light-emitting layer, a host having a low electron injection barrier and a high electron mobility is used to form the electron transport auxiliary layer. As a result, in the organic electroluminescent device of the present invention, electrons injected from the electron transport layer are smoothly supplied to the light-emitting layer through the electron transport auxiliary layer, the coupling rate of holes and electrons is increased, and the number of excitons is significantly increased. Therefore, the organic electroluminescent device of the present invention exhibits high-efficiency light-emitting characteristics, has a low driving voltage, and significantly improves the lifetime characteristics.

[0067] ​​​​​​​​​​​​​ At this time, the barrier-free effect between the electron transport auxiliary layer 331 and the light-emitting layer 320 is exerted and the electron injection barrier between the electron transport auxiliary layer 331 and the electron transport layer 332 is lowered. Therefore, the material of the electron transport auxiliary layer 331 needs to be selected in consideration of physical properties such as the HOMO energy level difference and the LUMO energy level difference between the electron transport auxiliary layer 331 and the electron transport layer 332 and the light-emitting layer 320.

[0068] In one example, the electron transport auxiliary layer material is selected so that the electron transport auxiliary layer 331 of the present invention satisfies the following relational expression 3 (see FIG. 3).

[0069] [Number] (In the formula, HOMO αETL is the HOMO energy level of the electron transport auxiliary layer, HOMO EL is the HOMO energy level of the light-emitting layer.)

[0070] Specifically, the difference between the absolute value of the HOMO energy level of the electron transport auxiliary layer 331 and the absolute value of the HOMO energy level of the light-emitting layer 320 can be in the range of more than 0 eV to 1.0 eV or less.

[0071] Thus, when the absolute value of the HOMO energy level of the electron transport auxiliary layer 331 is greater than the absolute value of the HOMO energy level of the light-emitting layer 32 0, holes present in the light-emitting layer are prevented from moving to the electron transport auxiliary layer by being blocked by the energy barrier of the electron transport auxiliary layer, and thereby the combination of electrons and holes in the light-emitting layer is increased.

[0072] In another example, the electron transport auxiliary layer 331 of the present invention satisfies the following relational expression 4 so that the electron transport​​​​ Select an auxiliary layer material (see FIG. 4).

[0073] [Number] (In the formula, LUMO ETL is the LUMO energy level of the electron transport layer, LUMO αETL is the LUMO energy level of the electron transport auxiliary layer, LUMO EL is the LUMO energy level of the light-emitting layer.)

[0074] Specifically, the difference between the absolute value of the LUMO energy level of the electron transport auxiliary layer 331 and the absolute value of the LUMO energy level of the electron transport layer 332 can be in the range of more than 0 eV to 1.0 eV or less. Also, the difference between the absolute value of the LUMO energy level of the electron transport auxiliary layer 331 and the absolute value of the LUMO energy level of the light-emitting layer 320 can be in the range of more than 0 eV to 1.0 eV or less.

[0075] Thus, when the absolute value of the LUMO energy level of the electron transport auxiliary layer 331 exists between the absolute value of the LUMO energy level of the electron transport layer 332 and the absolute value of the LUMO energy level of the light-emitting layer 320, the LUMO energy level will have a stepped arrangement, and electrons injected from the cathode can be smoothly injected from the electron transport layer to the light-emitting layer.

[0076] Any material having physical properties such as the HOMO energy level and the LUMO energy level described above can be used as the electron transport auxiliary layer material of the present invention. Any material having physical properties such as the HOMO energy level and the LUMO energy level described above can be used as the electron transport auxiliary layer material of the present invention.

[0077] As an example, the material of the electron transport auxiliary layer 331 of the present invention is represented by the following Chemical Formula 1 and Chemical Formula 2 A compound containing one or more moieties selected from the group consisting of the moieties to be used (hereinafter referred to as "compound containing one or more moieties"). It may be.

[0078]

Chemical formula

[0079] In the above Chemical Formula 1, when R 1 binds to an adjacent group to form a condensed ring, the moiety represented by the above Chemical Formula 1 can be the moiety represented by the following Chemical Formula 3, but is not limited thereto.

[0080]

Chemical Formula

[0081] The one or more moiety-containing compounds described above may be the moieties in Formula 1 and Formula 2. Therefore, the above-mentioned one or more types of electron-withdrawing groups (EWGs) have high electron-withdrawing properties. The moiety-containing compound is not only an electron transport auxiliary layer material but also one of the hosts in the light-emitting layer. When applied simultaneously to one of the two layers, the electrons injected from the cathode are circularly transported from the electron transport layer to the light-emitting layer. This allows the driving voltage of the organic electroluminescent device to be lowered and the efficiency and and can induce longevity.

[0082] In addition, the one or more moiety-containing compounds may be the moieties in Formula 1 and Formula 2. The molecular weight of the compound can be adjusted by adjusting the type and position of various substituents introduced into the tee. Since the glass transition temperature is significantly increased, the thermal stability of the organic electroluminescent device is improved. At the same time, the crystallization of the organic layer is suppressed, and the durability and life characteristics of the element are greatly improved. It can be improved.

[0083] Specifically, the one or more moiety-containing compounds are represented by any one of the following chemical formulas 4 to 6: The compound may be, but is not limited to, one of the compounds shown in the above.

[0084] [ka] In Chemical Formulas 4 to 6, X 1 ~X 5 , Y 1 ~Y 4 , Z 1 and Z 3 are as defined in Chemical Formulas 1 to 3, respectively. the law of nature, L 1 ~L 3is the same as or different from each other, and each independently is a single bond or a C 6 ~C 18 arylene group or a heteroarylene group having 5 to 18 ring atoms, selected from the group consisting of , specifically a single bond, a phenylene group, a biphenylene group (biphenylene grou p), a terphenylene group, a divalent naphthyl group , a divalent phenanthryl group, a divalent anthracene group, a divalent pyrene group, a divalent chrysene group , a divalent carbazole group, a divalent dibenzofuran group, a divalent dibenzothiophene group, divalent fluorene group, a divalent fluoranthene group, a divalent triphenylene group, a divalent furan group, a divalent indole group, a divalent indene group, a divalent thiophene group, a divalent benzofuran group, a divalent benzothiophene group, a divalent benzoindenyl group, and a combination of two or more thereof selected from the group consisting of; Ar 1 ~A 3 is the same as or different from each other, and each independently is a substituent selected from the group consisting of substituents represented by the following chemical formulas S1 to S9, wherein

Chemical formula

[0085] Specifically, the compound represented by any one of the above Chemical Formulas 4 to 6 may be selected from the group consisting of the compounds represented by the following Chemical Formulas A -1 to A-16, but is not limited thereto.

[0086]

Chemical Formula

[0087] More specifically, the compound represented by any one of the above chemical formulas 4 to 6 can be represented by the following chemical formula: The compound may be selected from the group consisting of compounds represented by formulas B-1 to B-9. Not limited to.

[0088] [ka] In chemical formulas B-1 to B-9, X 1 , X 3 , X 5 , R 1 are as defined in the above formulas 1 to 3, L 1 and L 3 is as defined in Chemical Formulas 4 to 6 above, A 1 ~A 5 , A 7 , A 9 , R 4 ~R 16 , R 21 , R 23 , a to h are the above formulas, As defined in formulas S1 to S9, n6 and n7 are as defined in the above chemical formulae A-1 to A-16, respectively.

[0089] The above-described compound containing one or more moieties can be embodied in the following Compounds 1 to 14, but is not limited thereto.

[0090] [Chemical formula]

[0091] In the electron transport region 330 according to the present invention, the electron transport layer 332 can be used without limitation as long as it is an electron transport material that facilitates electron injection and has a high electron mobility. Examples of such electron transport materials include, for example, oxazole-based compounds, isoxazole-based compounds, triazole-based compounds, isothiazole-based compounds, oxadiazole -based compounds, thiadiazole-based compounds, perylene -based compounds, aluminum complexes [for example, Alq (tris(8-quinolinolato)-aluminum: tris-(8-quinolinolato)-aluminum 3 (tris(8-quinolinolato)-aluminum: tris-(8-quinolinolato)-aluminum nium), BAlq, SAlq, Alph nium), BAlq, SAlq, Alph 3 , Almq 3 , gallium complexes (for example, Gaq’2OPiv, Gaq’2OAc, 2(Gaq’2)), etc., but is not limited thereto. These can be used alone or in combination of two or more.

[0092] In addition, the electron injection layer 333 can be used without limitation as long as it is an electron injection material that facilitates electron injection and has a high electron mobility. Examples of the above electron injection materials include, for example, LiF, Li O 2 O , BaO, NaCl, CsF; lanthanide metals such as Yb; or RbCl, Rb Examples of the metal halide include, but are not limited to, those such as I. These can be used alone or in combination of two or more.

[0093] The electron transport region 330 according to the present invention, specifically the electron transport layer 332 and / or the electron injection layer 3 33 can also be used as a co-evaporated material with an n-type dopant so that electron injection from the cathode is easy. At this time, as the n-type dopant, known alkali metal complexes can be used without limitation. As an example, alkali metals, alkaline earth metals, or rare earth metals, etc. can be mentioned.

[0094] The above electron transport region 330 can be manufactured by a conventional method well-known in the art. For example , vacuum evaporation method, spin coating method, casting method, LB (Langmuir-Blodget t) method, inkjet printing method, laser printing method, laser thermal transfer method (Laser Induced Thermal Imaging, LITI), etc. can be mentioned, but it is not limited to these.

[0095] 4) Light emission auxiliary layer Optionally, the organic electroluminescent device 100 of the present invention can further include a light emission auxiliary layer (not shown) disposed between the hole transport region 310 and the light emission layer 32 0.

[0096] The light emission auxiliary layer transports the holes moved from the hole transport region 310 to the light emission layer 320, or , while blocking the movement of electrons and / or excitons, plays a role in adjusting the thickness of the organic layer 300. In particular, the light emission auxiliary layer has a high LUMO value to prevent electrons from moving to the hole transport layer 312 (or the hole transport auxiliary layer 313), and has a high triplet energy to emit while preventing the movement of electrons to the hole transport layer 312 (or the hole transport auxiliary layer 313), and has a high triplet energy to emit The excitons in the light-emitting layer 320 can be prevented from diffusing into the hole transport layer 312 (or the hole transport auxiliary layer 313). This can be prevented.

[0097] Such a light-emitting auxiliary layer can contain a hole transport material and can be made of the same material as the hole transport region. In addition, the light-emitting auxiliary layers of red, green, and blue organic light-emitting devices can be made of the same kind of material.

[0098] The material of the light-emitting auxiliary layer is not particularly limited, and examples thereof include carbazole derivatives and arylamine derivatives. Specifically, examples of the light-emitting auxiliary layer include NPD (N,N-dinaphthyl-N,N'-diphenylbenzidine), TPD (N,N'-bis-(3-methylphenyl)-N,N'-bis(phenyl)-benzidine), s-TAD, MTDATA (4 ,4',4''-tris(N-3-methylphenyl-N-phenyl-amino)-triphenylamine), etc., but are not limited thereto. These can be used alone or in combination of two or more. ,4’,4’’-tris(N-3-methylphenyl-N-phenyl-amino)-triphenyl lamine), etc., but are not limited thereto. These can be used alone or in combination of two or more. These can be used alone or in combination of two or more.

[0099] In addition to the above-mentioned substances, the light-emitting auxiliary layer can further contain a p-type dopant. As the p-type dopant that can be used in the present invention, any p-type dopant well-known in the art can be used without particular limitation. At this time, the content of the p-type dopant can be appropriately adjusted within the range known in the art. For example, it can be about 0.5 to 50 parts by weight with respect to 100 parts by weight of the hole transport material. At this time, the content of the p-type dopant can be appropriately adjusted within the range known in the art. For example, it can be about 0.5 to 50 parts by weight with respect to 100 parts by weight of the hole transport material. It can be about 0.5 to 50 parts by weight with respect to 100 parts by weight of the hole transport material.

[0100] As is well-known in the art, the above-mentioned light-emitting auxiliary layer can be formed by a vacuum evaporation method, a spin coating method, a casting method, etc. The STO method, LB (Langmuir-Blodgett) method, inkjet printing method, laser printing method, laser thermal transfer method (Laser Induced Thermal I maging, LITI) can be used, but is not limited thereto.

[0101] (4) Capping layer Optionally, the organic electroluminescent device 100 of the present invention can further include a capping layer (not shown) disposed on the cathode 200.

[0102] The capping layer protects the organic electroluminescent device and plays a role in assisting the efficient external emission of light generated from the organic layer.

[0103] Examples of the capping layer include tris-8-hydroxyquinoline aluminum (Alq 3 ), 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-methyl phenyl)-1,1'-biphenyl-4,4'-diamine (TPD), 1,1'-bi (di-4-tolylaminophenyl)cyclohexane (TAPC), and one or more selected from the group consisting of these. Substances for forming such a capping layer are less expensive than other materials of the organic electroluminescent device.

[0104] Such a capping layer can be a single layer, or can be composed of two or more layers having different refractive indices, and the refractive index can be gradually changed while passing through the two or more layers.

[0105] The capping layer can be manufactured by a conventional method well-known in the art. For example, it can be manufactured by various methods such as vacuum evaporation method, spin coating method, casting method, or LB (Langmuir-Blodget t) method.

[0106] As described above, the organic electroluminescent device according to the present invention has a structure in which an anode 100, an organic layer 300, and a cathode 200 are sequentially laminated. If necessary, an insulating layer (not shown) or an adhesive layer ( not shown) can be further included between the anode 100 and the organic layer 3 00, or between the cathode 200 and the organic layer 300. Such an organic electroluminescent device of the present invention maintains the maximum luminous efficiency when voltage and current are applied, and the half-life time (Life time) of the initial brightness is increased, so excellent lifetime characteristics can be obtained.

[0107] The organic electroluminescent device of the present invention described above can be manufactured by a conventional method well-known in the art. For example, after vacuum depositing an anode material on a substrate, materials of a hole transport region material, a light emitting layer material, an electron transport region material, and a cathode material are sequentially vacuum deposited on the anode to manufacture an organic light emitting device can be manufactured.

Example

[0108] Hereinafter, the present invention will be described in detail based on examples. However, the following examples are merely illustrative of the present invention and the present invention is not limited by these examples.

[0109] [Preparation Examples 1 to 14] Measurement of HOMO, LUMO, and triplet energy of Compounds 1 to 20 As materials for the first host and the electron transport auxiliary layer of the present invention, the following Compounds 1 to 14 were prepared , these HOMO and LUMO were measured respectively by methods known in the art and are shown in Table 1 below. Note that, as a control group, ADN and Alq were used. 3

[0110] In Table 1, each HOMO energy level and LUMO energy level are shown as absolute values.

[0111] 1) HOMO energy level The HOMO energy level of each compound was measured by the CV (cyclic voltammetry y) method.

[0112] 2) LUMO energy level After obtaining the band gap energy of each compound by UV spectrum, the LUMO energy level was obtained from the difference between the band gap energy and the HOMO energy level.

[0113]

Chemical formula

[0114]

Table 1

[0115] [Example 1] Fabrication of a blue organic electroluminescent device Compound 1 prepared in Preparation Example 1 was subjected to high-purity sublimation purification by a conventional method and then a blue organic electroluminescent device was fabricated according to the following process. First, a glass substrate coated with a 1500 Å-thick ITO (Indium Tin Oxide e) thin film was washed with distilled water ultrasonic. After the distilled water washing was completed, it was ultrasonicated with solvents such as isopropyl alcohol, acetone, and methanol . After performing wave cleaning and drying, it was transferred to a UV Ozone cleaner (Power sonic 40 5, manufactured by Hwashin Tech Co., Ltd.), and then the substrate was cleaned with UV for 5 minutes and the substrate was transferred to a vacuum evaporator.

[0116] On the ITO transparent electrode prepared as described above, DS-205 (manufactured by Doosan Electronics Co., Ltd.) ( 80 nm) / NPB (15 nm) / Compound 1 + ADN + 5% DS-405 (manufactured by Doosan Electronics Co., Ltd.) ( 30 nm) / Compound 1 (5 nm) / Alq 3 (25 nm) / LiF (1 nm) / Al (200 nm) were laminated in this order to manufacture an organic electroluminescent device. Note that the used NP B, ADN, and Alq 3 structures are as follows. Here, in the light-emitting layer, Compound 1 was used as the first host (\"A\" in Table 2), and ADN was used as the second host (\"B\" in Table 2 ).

[0117] [Examples 2 to 14] Manufacturing of blue organic electroluminescent devices Instead of Compound 1, which was the first host used in forming the light-emitting layer of Example 1, each of the following compounds (\"A\" in Table 2) listed in Table 2 was used, and instead of Compound 1 used in forming the electron transport auxiliary layer, each of the following compounds (\"C\" in Table 2) listed in Table 2 was used, except that blue organic electroluminescent devices of Examples 2 to 14 were manufactured in the same manner as in Example 1.

[0118] [Comparative Example 1] Manufacturing of blue organic electroluminescent devices A blue organic electroluminescent device was manufactured in the same manner as in Example 1, except that Compound 1, which was the first host used in forming the light-emitting layer of Example 1, was not used and only ADN, which is the second host, was used.

[0119] [Comparative Example 2] Fabrication of Blue Organic Electroluminescent Device Without using Compound 1, which is the first host used in the formation of the light-emitting layer in Example 1, and without using ADN, which is the second host, without forming an electron transport auxiliary layer, and without using Alq, which is the electron transport layer material as the electron transport layer material, a blue organic electroluminescent device was fabricated in the same manner as in Example 1, except that Alq was deposited at 30 nm instead of 25 nm. Alq 3 as the electron transport layer material, a blue organic electroluminescent device was fabricated in the same manner as in Example 1, except that Alq was deposited at 30 nm instead of 25 nm. a blue organic electroluminescent device was fabricated.

[0120] [Comparative Example 3] Fabrication of Blue Organic Electroluminescent Device Without using Compound 1, which is the first host used in the formation of the light-emitting layer in Example 1, and using only ADN, which is the second host, without forming an electron transport auxiliary layer, and without using Alq, which is the electron transport layer material a blue organic electroluminescent device was fabricated in the same manner as in Example 1, except that Alq was deposited at 30 nm instead of 25 nm. Alq 3 a blue organic electroluminescent device was fabricated in the same manner as in Example 1, except that Alq was deposited at 30 nm instead of 25 nm. a blue organic electroluminescent device was fabricated.

[0121] [Evaluation Example 1] For the organic electroluminescent devices fabricated in Examples 1 to 16 and Comparative Example 1, the driving voltage, emission wavelength, and current efficiency were measured at a current density of 10 mA / cm², and the results are shown in Table 2 below. at a current density of 10 mA / cm² 2 and the results are shown in Table 2 below. shown in Table 2 below.

[0122]

Table 2

[0123] As shown in Table 2 above, in the blue organic electroluminescent devices of Examples 1 to 14, in which one of the plurality of hosts in the light-emitting layer is made of the same material as the electron transport auxiliary layer, it was found that they exhibit excellent performance in terms of current efficiency, emission peak, and driving voltage compared to the blue organic electroluminescent devices of Comparative Examples 1 to 3. blue organic electroluminescent devices of Examples 1 to 14 showed excellent performance in terms of current efficiency, emission peak, and driving voltage compared to the blue organic electroluminescent devices of Comparative Examples 1 to 3. voltage compared to the blue organic electroluminescent devices of Comparative Examples 1 to 3.

Claims

1. An anode; A cathode disposed opposite to the anode; and, An organic layer interposed between the anode and the cathode and including a hole transport region, a light-emitting layer, and an electron transport region sequentially disposed on the anode; comprising the electron transport region includes an electron transport auxiliary layer, an electron transport layer, and an electron injection layer sequentially disposed on the light-emitting layer, the light-emitting layer includes a plurality of hosts and a dopant, the plurality of hosts includes a first host and a second host different from the first host, the material of the first host and the electron transport auxiliary layer is the same as each other and is selected from the group consisting of Compound 2, Compound 6, and Compound 7 below, the electron transport auxiliary layer satisfies the following relational expression 6, An organic electroluminescent device in which the difference between the absolute value of the LUMO energy level of the electron transport auxiliary layer and the absolute value of the LUMO energy level of the second host is in the range of 0.02 to 0.17 eV. 【Number】 【Number 1】 (In the formula, LUMO ETL is the LUMO energy level of the electron transport layer, LUMO αETL is the LUMO energy level of the electron transport auxiliary layer, LUMO host-2 is the LUMO energy level of the second host.)

2. The organic electroluminescent device according to claim 1, wherein the electron transport auxiliary layer satisfies the following relational expression 5. 【Number 2】 (In the formula, HOMO αＥＴＬ is the HOMO energy level of the electron transport auxiliary layer, HOMO ｈｏｓｔ－２ is the HOMO energy level of the second host.)

3. The organic electroluminescent device according to claim 2, wherein the difference between the absolute value of the HOMO energy level of the electron transport auxiliary layer and the absolute value of the HOMO energy level of the second host is in the range of 0.02 to 0.25 eV.

4. The organic electroluminescent device according to claim 1, wherein the difference between the absolute value of the LUMO energy level of the electron transport auxiliary layer and the absolute value of the LUMO energy level of the electron transport layer is in the range of more than 0 eV to 1.0 eV or less.

5. The organic electroluminescent device according to claim 1, wherein the content of the host that is the same as the material of the electron transport auxiliary layer among the plurality of hosts is in the range of 30 to 90% by weight based on the total amount of all hosts.

6. The organic electroluminescent device according to claim 1, wherein the second host satisfies the following relational expressions 1 and 2. [Number 3] (In the formula, LUMO ｈｏｓｔ－１ is the LUMO energy level of the first host, LUMO ｈｏｓｔ－２ is the LUMO energy level of the second host, and HOMO ｈｏｓｔ－１ is the HOMO energy level of the first host, HOMO ｈｏｓｔ－２ is the HOMO energy level of the second host.)

7. The difference between the absolute value of the LUMO energy level of the second host and the absolute value of the LUMO energy level of the first host is in the range of more than 0 eV to 1.0 eV or less, The difference between the absolute value of the HOMO energy level of the second host and the absolute value of the HOMO energy level of the first host is in the range of more than 0 eV to 1.0 eV or less. The organic electroluminescent device according to claim 6.

8. The usage ratio of the first host and the second host is in the weight ratio of 30:70 to 90:

10. The organic electroluminescent device according to claim 6.

9. The dopant is in the range of more than 0 parts by weight to 20 parts by weight or less with respect to 100 parts by weight of the plurality of hosts. The organic electroluminescent device according to claim 1.

10. The light emitting layer is formed by co-evaporating the plurality of hosts. The organic electroluminescent device according to claim 1.

11. The hole transport region includes one or more selected from the group consisting of a hole injection layer, a hole transport layer, and a hole transport auxiliary layer. The organic electroluminescent device according to claim 1.

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