Compound and light-emitting element

Abstract

The invention provides a compound, a photoelectric conversion element containing the same, and a light-emitting element. The compound according to the present invention has a specific structure of an azabenzene-based host and a dibenzoheterocycle host, and the specific structure is represented by general formula 1. According to the present invention, an organic thin-film light-emitting element can be provided which simultaneously achieves high light-emitting efficiency, low driving voltage, and long endurance life.

Description

Technical Field

[0001] This invention relates to the field of organic electroluminescence technology, and more specifically to a compound and a light-emitting element comprising said compound that can convert electrical energy into light. Background Technology

[0002] OLED devices are organic thin-film light-emitting elements containing an anode, a cathode, and an organic layer between them. These elements emit light when electrons injected from the cathode recombine with holes injected from the anode within the organic light-emitting body sandwiched between the two electrodes. OLEDs are characterized by their small thickness, high brightness at low driving voltages, and the ability to achieve multi-color emission through the selection of light-emitting materials, thus attracting considerable attention. In recent years, OLED devices have been used in displays for televisions, smartphones, and other devices, gradually entering the practical application stage. However, existing OLED devices still face many technical challenges. Among these, simultaneously achieving low driving voltage, high luminous efficiency, and long lifetime has become a major research focus.

[0003] OLEDs must achieve improved luminous efficiency, reduced driving voltage, and increased durability. Achieving both luminous efficiency and durability simultaneously is a significant challenge. However, existing technologies (Patent Documents 1-6) make it difficult to significantly reduce driving voltage while maintaining both luminous efficiency and durability. Furthermore, as OLEDs increasingly replace LCDs and gain market share in the display industry, simpler manufacturing processes that reduce overall factory operation complexity and costs have become crucial technical indicators.

[0004] [Existing technical documents]

[0005] [Patent Literature]

[0006] [Patent Document 1] International Publication No. 2008 / 059713

[0007] [Patent Document 2] International Publication No. 2007 / 100010

[0008] [Patent Document 3] International Publication No. 2012 / 108388

[0009] [Patent Document 4] International Publication No. 2013 / 065213

[0010] [Patent Document 5] International Publication No. 2014 / 057874

[0011] [Patent Document 6] International Publication No. 2015 / 182547. Summary of the Invention

[0012] The purpose of this invention is to solve the problems of the prior art and provide an organic thin-film light-emitting element with improved luminous efficiency, driving voltage, and durability, and with a simple manufacturing process.

[0013] This invention controls the amount of electrons capable of transporting electrons in the molecule by adjusting the linking groups and linkage mode between the azirbenzene host and the dibenzoheterocyclic host in the compound, as well as adjusting the nitrogen content of the electron-transferring groups, thereby regulating the luminous efficiency, driving voltage, and durability.

[0014] To address the aforementioned issues, the present invention comprises the following:

[0015] [1] A compound represented by the following general formula 1,

[0016]

[0017] Among them, X1, X2, X3, X4 or X5 may be the same or different, each being a nitrogen atom or CR1, CR2 or CR3, and at least two of them are nitrogen atoms;

[0018] L is independently selected from aryl groups having 6 to 40 substituted carbon atoms or heteroaryl groups having 2 to 40 substituted carbon atoms;

[0019] n is 4, 5, 6, or 7;

[0020] Any one of Q1, Q2, Q3, Q4, Q5, Q6, Q7, or Q8 is connected to L, and the others are CR4, CR5, CR6, CR7, CR8, CR9, or CR 10 ;

[0021] The R1, R2, R3, R4, R5, R6, R7, R8, R9, or R 10 It is independently selected from hydrogen, deuterium, cyano, substituted alkyl, substituted cycloalkyl, substituted heterocyclic, substituted alkenyl, substituted cycloalkenyl, substituted alkynyl, substituted alkoxy, substituted alkylthio, substituted aryl ether, substituted aryl thioether, substituted aryl, substituted heteroaryl, substituted carbonyl, substituted carboxyl, substituted oxycarbonyl, substituted carbamoyl, substituted silyl, substituted alkylamino, or substituted arylamino;

[0022] Y represents an oxygen atom or a sulfur atom;

[0023] Each of the substituted groups is independently selected from one or more of hydrogen, deuterium, cyano, substituted alkyl, substituted cycloalkyl, substituted heterocyclic, substituted alkenyl, substituted cycloalkenyl, substituted alkynyl, substituted alkoxy, substituted alkylthio, substituted aryl ether, substituted aryl thioether, substituted aryl, substituted heteroaryl, substituted carbonyl, substituted carboxyl, substituted oxycarbonyl, substituted carbamoyl, substituted silyl, substituted alkylamino, or substituted arylamino.

[0024] [2] According to the compound described in [1], one of Q2, Q3, Q6 or Q7 is connected to L.

[0025] [3] According to the compound described in [1], X1, X3 and X5 are nitrogen atoms, and X2 or X4 are CR1 or CR2 respectively.

[0026] [4] According to the compound described in [1], any two of X1, X3 or X5 are nitrogen atoms, and the remaining one is a nitrogen atom.

[0027] It is CR3, and X2 or X4 is CR1 or CR2 respectively.

[0028] [5] According to the compound described in [1], n is equal to 4 or 5.

[0029] [6] According to the compound described in [5], where n equals 4, general formula 1 is represented by the following general formula 2.

[0030]

[0031] L1, L2, L3, or L4 are each independently selected from substituted phenyl, substituted pyridyl, or substituted pyrimidinyl groups.

[0032] [7] In the compound according to [6], L1, L2 or L4 are each independently selected from substituted phenyl, substituted pyridyl or substituted pyrimidinyl groups.

[0033] The L3 is selected from phenylene, pyridinyl, or pyrimidinyl.

[0034] [8] According to the compound described in [7], L1, L2, L3 or L4 are all phenylene.

[0035] [9] According to the compound described in [8], the connection site of any one of L1, L2, L3 or L4 with its adjacent group is either ortho or para.

[0036]

[10] According to the compound described in [5], where n equals 5, general formula 1 is represented by the following general formula 3.

[0037]

[0038] L5, L6, L7, L8, or L9 are each independently selected from substituted phenyl, substituted pyridyl, or substituted pyrimidinyl groups.

[0039]

[11] According to the compound described in

[10] , L5, L6, L7, L8 or L9 are independently selected from phenylene, pyridylene or pyrimidinylene.

[0040]

[12] According to the compound described in

[11] , L5, L6, L7, L8 or L9 are all phenylene.

[0041]

[13] In the compound described in [1], Y is an oxygen atom.

[0042]

[14] According to the compound described in [1], R4, R5, R6, R7, R8, R9, or R 10 Each is independently selected from hydrogen, deuterium, cyano or phenyl.

[0043]

[15] According to the compound described in

[14] , R4, R5, R6, R7, R8, R9, or R 10 Selected from hydrogen.

[0044]

[16] A light-emitting element comprising an organic layer between an anode and a cathode, wherein, in the organic layer...

[0045] The organic layer contains any one of the compounds described in [1]-

[15] .

[0046]

[17] According to the light-emitting element described in

[16] above, wherein the organic layer includes an electron transport layer,

[0047] The electron transport layer contains any one of the compounds described in [1]-

[15] .

[0048] This invention provides an organic thin-film light-emitting element that simultaneously achieves high luminous efficiency, low driving voltage, long lifespan, and simple fabrication process. Detailed Implementation

[0049] The specific embodiments of the compound and light-emitting element provided by the present invention will be described in detail below. However, the present invention is not limited to the following embodiments, and the implementation methods can be modified according to the purpose and use.

[0050] The specific embodiments of the present invention will be described in detail below.

[0051] The term "substitutable" in this article means that a certain group can be substituted or not substituted. "Not substituted" refers to the case where a hydrogen atom or a deuterium atom forms a bond with it.

[0052] In all the substituents mentioned in this article, the hydrogen atom can also be a deuterium atom.

[0053] The various substituents that appear in this article will be explained below.

[0054] The term "alkyl" refers to saturated aliphatic hydrocarbon groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, or tert-butyl, which may or may not have substituents. There are no particular limitations on the additional substituents added when substituted; examples include alkyl, aryl, and heteroaryl groups, and this will be used in the following description. Furthermore, there is no particular limitation on the number of carbon atoms in the alkyl group; however, considering the ease of obtaining materials and cost, a number of 1 to 20 carbon atoms is preferred.

[0055] The cycloalkyl group refers to saturated aliphatic cycloalkyl groups such as cyclopropyl, cyclohexyl, norbornyl, or adamantyl, which may or may not have substituents. The number of carbon atoms in the alkyl moiety is not particularly limited, but a range of 3 to 20 is preferred considering the ease of material availability and cost.

[0056] The alkenyl group refers to an unsaturated aliphatic hydrocarbon group containing a double bond, such as vinyl, allyl, or butadiene, which may or may not have substituents. The number of carbon atoms in the alkenyl group is not particularly limited, but considering the ease of material availability and cost, a range of 3 to 20 is preferred.

[0057] The cycloalkenyl group refers to an unsaturated aliphatic hydrocarbon group containing a double bond, such as cyclopentenyl, cyclopentadienyl, or cyclohexenyl, which may or may not have substituents. The number of carbon atoms in the cycloalkenyl group is not particularly limited; however, considering the ease of material availability and cost, a range of 3 to 20 atoms is preferred.

[0058] The alkynyl group refers to an unsaturated aliphatic hydrocarbon group containing a triple bond, such as ethynyl, which may or may not have substituents. The number of carbon atoms in the alkynyl group is not particularly limited, but considering the ease of material availability and cost, a range of 3 to 20 is preferred.

[0059] The alkoxy group refers to a functional group consisting of an aliphatic hydrocarbon group, such as methoxy, ethoxy, or propoxy, bonded via an ether bond. This aliphatic hydrocarbon group may or may not have substituents. The number of carbon atoms in the alkoxy group is not particularly limited, but considering the ease of material availability and cost, a range of 1 to 20 is preferred.

[0060] The alkathio group is formed by replacing the oxygen atom in the ether bond of the alkoxy group with a sulfur atom. The hydrocarbon group of the alkathio group may or may not have substituents. There is no particular limitation on the number of carbon atoms in the alkathio group, but considering the ease of material acquisition and cost, a range of 1 to 20 is preferred.

[0061] The aryl ether group refers to a functional group consisting of an aromatic hydrocarbon group, such as a phenoxy group, bonded via an ether bond. The aromatic hydrocarbon group may or may not have substituents. There is no particular limitation on the number of carbon atoms in the aryl ether group, but considering the ease of material availability and cost, a range of 6 to 40 is preferred.

[0062] The aryl thioether group is formed by replacing the oxygen atom of the ether bond in the aryl ether group with a sulfur atom. The aromatic hydrocarbon group in the aryl thioether group may or may not have substituents. There is no particular limitation on the number of carbon atoms in the aryl thioether group, but considering the ease of material acquisition and cost, a range of 6 to 40 is preferred.

[0063] The aryl group refers to aromatic hydrocarbon groups such as phenyl, naphthyl, biphenyl, phenanthryl, triphenyl, pyrene, or 1,2-benzoacenaphthene. The aryl group may or may not have substituents. The number of carbon atoms in the aryl group is not particularly limited; however, considering the ease of obtaining materials and cost, a range of 6 to 40 atoms is preferred.

[0064] The heteroaryl group refers to a cyclic aromatic group such as furanyl, thiophenyl, pyridyl, quinolinyl, isoquinolinyl, pyrazinyl, or pyrimidinyl, which has atoms other than carbon atoms in one ring. It may be unsubstituted or substituted. The number of carbon atoms in the heteroaryl group is not particularly limited; however, considering the ease of material acquisition and cost, a range of 2 to 40 is preferred.

[0065] The groups include carbonyl, carboxyl, oxycarbonyl, and carbamoyl groups, and may or may not have substituents. Examples of substituents include alkyl, cycloalkyl, aryl, and heteroaryl groups, which may be further substituted.

[0066] The terms phenylene, pyridylene, or pyrimidinylene refer to divalent groups derived from phenyl, pyridyl, or pyrimidinyl groups, and do not contain substituents.

[0067] Next, the compounds having the structure shown in Formula 1 provided by the present invention will be described in detail.

[0068]

[0069] The structure represented by General Formula 1 illustrates a dual-host structure consisting of an azirbenzene host and a dibenzo[a]heterocyclic host. The azirbenzene host is an azirbenzene containing multiple nitrogen atoms. In the azirbenzene system, the large π bond of benzene itself can move throughout the molecular domain. Adding nitrogen to the azirbenzene host further increases the delocalized electrons in the large π bond due to the lone pairs of nitrogen atoms, thus enhancing electron transport capability. The electrons in the azirbenzene host are less attracted to the atomic nucleus, while the dibenzo[a]heterocyclic host has a tendency to attract electrons. This creates a tendency for electrons to move towards the dibenzo[a]heterocyclic host throughout the molecule (even though the molecule itself is neutral). When such molecules accumulate to form a film, they can, to some extent, mimic the electron delocalization in metallic bonds, thereby providing electron transport capability.

[0070] In this structure, X1, X2, X3, X4, or X5 may be the same or different, each independently being a nitrogen atom or CR1, CR2, or CR3, with at least two being nitrogen atoms. Excessive nitrogen will excessively lower the LUMO, causing a mismatch between the energy level of the electron transport layer and the surrounding material. Therefore, it is preferable that two or three of X1, X2, X3, X4, or X5 are nitrogen atoms, specifically in the following two cases: first, X1, X3, and X5 are nitrogen atoms, and X2 or X4 is CR1 or CR2 respectively. This symmetrical structure results in a more uniform electron cloud distribution in the azirbenzene matrix, allowing molecules to stack stably, increasing film stability during evaporation, resulting in a longer lifetime, and better matching between the electron transport layer and the hole blocking layer. Furthermore, because the amount of lone pair electrons provided by the three nitrogen atoms is appropriate, the electron transport performance matches the hole blocking layer better, allowing electrons to pass through smoothly, thus achieving a lower driving voltage and higher efficiency. The second scenario involves any two of X1, X3, or X5 being nitrogen atoms, with the remaining one being CR3, and X2 or X4 being CR1 or CR2, respectively. This also creates a symmetrical structure, resulting in a more uniform electron cloud distribution in the azirbenzene matrix, better matching of electron transport performance with the electron injection layer, allowing electrons to pass through smoothly, leading to lower driving voltage and higher luminous efficiency, and better matching between the electron transport layer and the electron injection layer.

[0071] L is independently selected from aryl groups with 6 to 60 substituted carbon atoms or heteroaryl groups with 6 to 60 substituted carbon atoms. By using aryl or heteroaryl groups within the aforementioned carbon number range, the spatial configuration between the azirbenzene host and the dibenzoheterocyclic host is adjusted, thereby allowing electrons to move more smoothly from the azirbenzene host to the dibenzoheterocyclic host within the molecule. This enables the molecules to mimic electron delocalization in metallic bonds to some extent when accumulating into a film, thus providing electron transport capability.

[0072] Any one of Q1, Q2, Q3, Q4, Q5, Q6, Q7, or Q8 is connected to L, and the others are CR4, CR5, CR6, CR7, CR8, CR9, CR 10 Further preferably, if one of Q2, Q3, Q6, or Q7 is connected to L, the voltage of the light-emitting element can be further reduced, and the efficiency and lifetime can be further improved. This is because the four sites Q2, Q3, Q6, or Q7 are located at the para and meta positions of the carbon atoms connected to the Y atom, and are spatially farther from the central Y atom. In this way, the L chain has less impact on the electron cloud density near the central Y atom, and electrons can move more smoothly within the molecule, improving electron transport performance. Therefore, a lower driving voltage and higher efficiency can be obtained. From the perspective of steric hindrance, being located at the far end of the central Y atom results in less steric hindrance within the synthesized molecule and higher stability.

[0073] The R1, R2, R3, R4, R5, R6, R7, R8, R9, or R 10 Independently selected from hydrogen, deuterium, cyano, substituted alkyl, substituted cycloalkyl, substituted heterocyclic, substituted alkenyl, substituted cycloalkenyl, substituted alkynyl, substituted alkoxy, substituted alkylthio, substituted aryl ether, substituted aryl thioether, substituted aryl, substituted heteroaryl, substituted carbonyl, substituted carboxyl, substituted oxycarbonyl, substituted carbamoyl, substituted silyl, substituted alkylamino, or substituted arylamino; further, R4, R5, R6, R7, R8, R9, or R 10 Each substituent is preferably derived independently from hydrogen, deuterium, cyano, or phenyl. In this case, the structure of the substituents on the dibenzo[a]cyclic heterocycle is relatively simple, which is beneficial for improving molecular stability and avoiding excessive substituents from disrupting the electron cloud distribution of the dibenzo[a]cyclic heterocycle and affecting electron transport efficiency. From the perspective of molecular stability and ease of synthesis, further substituents such as R4, R5, R6, R7, R8, R9, or R[a] are preferred. 10 It is preferably derived from hydrogen.

[0074] Y is an oxygen atom or a sulfur atom. In this case, the electron cloud density of the ring containing the oxygen or sulfur atom is higher than that of the two surrounding benzene rings, forming a high-density electron cloud center, which improves the intermolecular electron transport capability. Since the electronegativity of the oxygen atom is greater than that of sulfur, the electron cloud near the oxygen atom is more concentrated, making the tendency for electron movement between the two main bodies within the molecule more pronounced, thus improving the molecule's ability to transport electrons. Therefore, it is preferable that Y is an oxygen atom.

[0075] Based on molecular weight and vapor deposition stability, n is 4, 5, 6, or 7; more preferably, n is 4 or 5. When n is 4 or 5, on the one hand, the molecular weight is reduced, making vapor deposition easier; on the other hand, the chain length is at a moderate level, allowing electrons to move more smoothly between the two main bodies, increasing electron transport performance and compensating for the electrons that combine with holes at the light-emitting layer. Therefore, in the light-emitting element, this results in lower voltage and higher efficiency; at the same time, due to the improved molecular stability, the lifetime is longer.

[0076] When n equals 4, general formula 1 is represented by the following general formula 2.

[0077]

[0078] From the perspective of ease of synthesis and film-forming properties, the main chain of L1, L2, L3, or L4, which connects the azirbenzene host and the dibenzoheterocyclic host, should not have overly complex branching structures. This is because overly complex substituents can affect electron transport between the two hosts. Therefore, L1, L2, L3, or L4 are independently selected from substituted phenyl, substituted pyridyl, or substituted pyrimidinyl groups. More preferably, L1, L2, or L4 are independently selected from substituted phenyl, substituted pyridyl, or substituted pyrimidinyl groups, and L3 is selected from phenylene, pyridinyl, or pyrimidinyl groups. The reason why the absence of substituents in L3 alone can produce such an effect is that, if L1 or L2 were unsubstituents, electrons would be affected by substituents in the later stages of the L1→L2→L3→L4 sequence, thus disrupting their movement speed. If L4 were unsubstituents, electrons would be significantly affected by substituents in the first three stages, and even without substituents at L4, the overall electron movement speed would be insufficient, resulting in inadequate electron transport performance. Compared to the above two cases, when there are no substituents at L3, electrons are less interfered with by other substituents as they move towards the dibenzohexane host, resulting in strong electron transport performance. More electrons combine with holes in the luminescent layer, thus resulting in lower voltage and higher efficiency in the light-emitting element. More preferably, L1, L2, L3, or L4 are all phenylene compounds, which have a simpler structure and smoother intermolecular stacking, further improving electron transport performance, reducing driving voltage, and increasing luminous efficiency.

[0079] From the perspective of the substitution and directing effect of the benzene ring, L1, L2, L3, or L4 are all phenylene, and the connection site between any one of L1, L2, L3, or L4 and its adjacent group is preferably ortho or para, which makes the synthesized molecule more stable and the light-emitting element has a better lifespan. On the one hand, para substitution makes the molecular backbone more extended and improves electron transport performance; on the other hand, the increase of ortho substitution tends to slow down the electron transport speed. In light-emitting elements, the electron transport speed needs to be adjusted according to the energy levels of adjacent organic layers. Therefore, it is further preferred to use a combination of ortho and para substitution to make the molecules stack tightly, improve the evaporation stability while maintaining the backbone extension and good electron transport performance, thereby improving the overall element performance.

[0080] When n equals 5, general formula 1 is represented by the following general formula 3.

[0081]

[0082] L5, L6, L7, L8, or L9 are each independently selected from substituted phenyl, substituted pyridyl, or substituted pyrimidinyl groups. Similar to the case where n equals 4, when n equals 5, the substituents of L5, L6, L7, L8, or L9 as the main chain should not be too complex. Therefore, it is preferable that they are independently selected as phenylene, pyridylene, or pyrimidinyl groups. In this case, due to the relatively simple structure and smooth intermolecular stacking, the electron transport performance is further improved, resulting in a lower driving voltage and higher luminous efficiency. Even more preferably, L5, L6, L7, L8, or L9 are all phenylene. In this case, the number of nitrogen atoms inside the molecule is only provided by the azirbenzene host, resulting in a moderate electron transport capability, better matching, and better device performance.

[0083] The substituted groups described above are each independently selected from one or more of hydrogen, deuterium, cyano, substituted alkyl, substituted cycloalkyl, substituted heterocyclic, substituted alkenyl, substituted cycloalkenyl, substituted alkynyl, substituted alkoxy, substituted alkylthio, substituted aryl ether, substituted aryl thioether, substituted aryl, substituted heteroaryl, substituted carbonyl, substituted carboxyl, substituted oxycarbonyl, substituted carbamoyl, substituted silyl, substituted alkylamino, or substituted arylamino.

[0084] Through practice, we believe that the following molecular structures and their derivatives can achieve excellent overall performance in terms of efficiency, voltage, and lifetime, depending on the specific device structure and application. Therefore, the following compounds are preferred. The following are merely examples; compounds other than those in the examples, as long as they conform to general formula 1, are also within the scope of this invention.

[0085]

[0086]

[0087]

[0088]

[0089]

[0090]

[0091]

[0092]

[0093]

[0094]

[0095]

[0096]

[0097]

[0098]

[0099]

[0100]

[0101]

[0102]

[0103]

[0104]

[0105]

[0106] The present invention also discloses a light-emitting element, wherein there is an organic layer between the anode and the cathode, the organic layer being divided into two layers: a layer responsible for light emission and / or a layer responsible for processing electrons or holes, wherein the organic layer contains the aforementioned compound.

[0107] Considering the ability of this type of material to process electrons, it is preferable that the organic layer has an electron transport layer containing the compounds described above.

[0108] Known methods can be used in the synthesis of the compounds of the present invention. Examples of methods for introducing an azirbenzene host into the compound skeleton include coupling reactions of a substituted or unsubstituted halobenzofuran or dibenzothiophene host with a substituted or unsubstituted azirbenzene host under a palladium or nickel catalyst, but these methods are not limited to. Furthermore, when introducing the azirbenzene host into the compound via an arylene or heteroarylene, the azirbenzene host may be a substituted arylboronic acid or heteroarylboronic acid, or a dibenzofuran or dibenzothiophene host substituted with a halogenated aryl group may also be used. Moreover, borate esters may be used instead of the aforementioned borate acids.

[0109] Light-emitting element

[0110] This invention is implemented in the form of a light-emitting element, which includes an anode and a cathode, and an organic layer between the anode and the cathode. This organic layer can emit light using electrical energy. Such a light-emitting element is referred to below as an "OLED device".

[0111] In OLED devices, the organic layer between the anode and cathode can be stacked in the following ways, in addition to the light-emitting layer alone: ​​1) light-emitting layer / electron transport layer, 2) hole transport layer / light-emitting layer, 3) hole transport layer / light-emitting layer / electron transport layer, 4) hole injection layer / hole transport layer / light-emitting layer / electron transport layer, 5) hole transport layer / light-emitting layer / electron transport layer / electron injection layer, 6) hole injection layer / hole transport layer / light-emitting layer / electron transport layer / electron injection layer, or 7) hole injection layer / hole transport layer / light-emitting layer / hole blocking layer / electron transport layer / electron injection layer, etc.

[0112] Alternatively, the above-mentioned stacked layer structure can be connected by intermediate layers to form multiple stacked layer structures, which are called stacked devices. The intermediate layer can also be called an intermediate electrode, intermediate conductive layer, charge generation layer, electron extraction layer, connection layer, or intermediate insulating layer, etc. The intermediate layer can use known materials. Specific examples of stacked devices include: 8) hole transport layer / light emission layer / electron transport layer / charge generation layer / hole transport layer / light emission layer / electron transport layer or 9) hole injection layer / hole transport layer / light emission layer / electron transport layer / electron injection layer / charge generation layer / hole injection layer / hole transport layer / light emission layer / electron transport layer / electron injection layer, etc. The characteristic of these examples is that an intermediate layer exists between the anode and cathode; this intermediate layer is often called a charge generation layer.

[0113] Furthermore, the aforementioned layers can be single-layered or multi-layered, and can be doped. In particular, the electron injection layer and charge generation layer are preferably metal-doped layers, which improves electron transport capability and the ability to inject electrons into other adjacent layers. In addition to the aforementioned layers, a protective layer can also be provided, which can further improve luminous efficiency through optical interference effects.

[0114] The compounds of the present invention can be used in any layer in the above-described component configuration, but they have high electron transport capability, fluorescence quantum yield and thin film stability, so they are preferred as electron transport layers.

[0115] In the light-emitting element of the present invention, the anode and cathode serve to supply sufficient current for the element to emit light. For light emission, at least one is preferably transparent or semi-transparent. Depending on the actual application and device design, a transparent anode or a transparent cathode can be used.

[0116] substrate

[0117] To maintain the mechanical strength of OLED devices, it is preferable to form the OLED devices on a substrate. As the substrate, various types can be used, such as glass substrates (e.g., soda-lime glass or alkali-free glass) or plastic substrates. The thickness of the glass substrate should be sufficient to maintain mechanical strength, requiring a thickness of 0.5 mm or more. As for the glass material, alkali-free glass with low ion leaching is preferred. Alternatively, commercially available soda-lime glass coated with a barrier coating such as SiO2 can also be used.

[0118] anode

[0119] The material used for the anode is preferably one that can efficiently inject holes into the organic layer. Furthermore, to allow light to be emitted outside the device, a transparent or translucent material is preferred. Examples of materials used for the anode include: conductive metal oxides such as zinc oxide, tin oxide, indium oxide, indium tin oxide (ITO), or indium zinc oxide (IZO); metals such as gold, silver, or chromium; inorganic conductive materials such as copper iodide or copper sulfide; and conductive polymers such as polythiophene, polypyrrole, or polyaniline. ITO glass or Nesa glass is preferred. These electrode materials can be used individually, or multiple materials can be stacked or mixed.

[0120] cathode

[0121] The materials used for the cathode are not particularly limited, as long as they can efficiently inject electrons into the light-emitting layer. Examples of materials for the cathode include metals such as platinum, gold, silver, copper, iron, tin, aluminum, or indium, or alloys or multilayer stacked materials of these metals and low work function metals such as lithium, sodium, potassium, calcium, or magnesium. Among these, considering factors such as resistance, ease of film formation, film stability, and luminous efficiency, aluminum, silver, and magnesium are preferred as the main components. Furthermore, considering the ease of electron injection into the electron transport layer and electron injection layer, a composition of magnesium and silver is more preferred.

[0122] protective layer

[0123] To protect the cathode, a protective layer, also known as a capping layer, is preferably stacked on it. There are no particular limitations on the materials constituting the protective layer; examples include metals such as platinum, gold, silver, copper, iron, tin, aluminum, or indium; alloys using these metals; inorganic materials such as silicon dioxide, titanium dioxide, or silicon nitride; and organic polymers such as polyvinyl alcohol, polyvinyl chloride, or hydrocarbon-based polymers. Additionally, compounds represented by general formula 1 can also be used as materials for the protective layer. However, when the OLED device is a device structure that extracts light from the cathode side (top-emitting structure), the material of the protective layer is preferably a material that is transparent in the visible light region.

[0124] Hole injection layer

[0125] The hole injection layer is a layer inserted between the anode and the hole transport layer. The hole injection layer can be a single layer or multiple layers stacked together. When a hole injection layer exists between the hole transport layer and the anode, not only can a lower drive voltage and longer lifetime be achieved, but the carrier balance of the device can also be improved and the luminous efficiency increased; therefore, this layer is preferred.

[0126] The material for the hole injection layer can be known materials, such as benzidine derivatives, starburst aromatic amine materials, triaromatic amine derivatives, biscarbazole derivatives, pyrazoline derivatives, diphenylethylene compounds, fluorene compounds, hydrazine compounds, benzofuran derivatives, thiophene derivatives, oxadiazole derivatives, phthalocyanine derivatives, or porphyrin derivative heterocyclic compounds, as well as derivatives of the above compounds, or polymers with side chains of polycarbonate, styrene derivatives, polythiophene, polyaniline, polyfluorene, polyvinylcarbazole, or polysilane. From the viewpoint of efficiently injecting and transporting holes from the anode to the hole transport layer, benzidine derivatives, starburst aromatic amine materials, or fluorene compounds are preferred.

[0127] These materials can be used alone or in combination of two or more, or multiple materials can be stacked to form a hole injection layer. Furthermore, to more significantly achieve the above effects, the hole injection layer is more preferably composed solely of acceptor compounds, or in the form of hole injection materials doped with acceptor compounds. The acceptor compound refers to the material used in a monolayer film, or the dopant material used in a doped film. When these materials are used, the conductivity of the hole injection layer is improved, which helps to further reduce the device's driving voltage and further improve luminous efficiency and lifetime.

[0128] The acceptor compound can be made of known materials, such as metal oxides like metal chlorides or molybdenum oxide, charge transfer ligands, or organic compounds containing nitro, cyano, halogen, or trifluoromethyl groups, quinone compounds, acid anhydride compounds, or fullerenes. Metal oxides or cyano-containing compounds are preferred because they are easy to process and deposit, thus readily achieving the aforementioned effects. In cases where the hole injection layer consists solely of the acceptor compound or where the hole injection layer is doped with the acceptor compound, the hole injection layer can be a single layer or multiple layers stacked together.

[0129] Hole transport layer

[0130] The hole transport layer is the layer that transports holes injected from the anode to the light-emitting layer. The hole transport layer can be a single layer or composed of multiple stacked layers.

[0131] The materials used in the hole injection layer described above can also be used as hole transport layer materials. From the viewpoint of efficiently injecting and transporting holes into the light-emitting layer, triarylamine derivatives or benzidine derivatives are preferred.

[0132] Emissive layer

[0133] The light-emitting layer can be a single layer or multiple layers. The light-emitting layer is formed of a light-emitting material, which can be a mixture of a host material and a dopant material, a single host material, or a mixture of two types of host materials and one type of dopant material. That is, in the OLED device according to the present invention, in each light-emitting layer, only the host material or the dopant material may emit light, or both the host material and the dopant material may emit light. From the viewpoint of efficiently utilizing electrical energy and obtaining light with high color purity, the light-emitting layer is preferably a mixture of a host material and a dopant material. Furthermore, the host material and the dopant material can each be one type, or a combination of multiple types. The dopant material can be completely or partially contained in the host material. The dopant material can be layered or dispersed. The dopant material can control the color of the emitted light. From the viewpoint of suppressing concentration quenching, the amount of dopant material relative to the host material is preferably 30% by weight or less, more preferably 20% by weight or less. As for the doping method, it can be formed by co-evaporation with the host material, or it can be pre-mixed with the host material and then simultaneously evaporated.

[0134] The luminescent material can be any known material. For example, polymers such as anthracene or pyrene fused-ring derivatives, metal chelate hydroxy compounds such as tris(8-hydroxyquinoline)aluminum, bis(styrene) derivatives such as bis(styrene)anthracene or styrenebenzene derivatives, tetraphenylbutadiene derivatives, indene derivatives, coumarin derivatives, oxadiazole derivatives, pyrrolopyridine derivatives, pyloridenone derivatives, cyclopentadiene derivatives, thiadiazopyridine derivatives, dibenzofuran derivatives, carbazole derivatives, indolecarbazole derivatives, poly(p-styrene) derivatives, poly(p-phenylene)benzene derivatives, or polythiophene derivatives are known as luminescent substances.

[0135] The host material in a luminescent material can be a single compound, a mixture of multiple compounds, or a stacked arrangement. The host material can be any known material without particular limitation, such as naphthalene, anthracene, phenanthrene, pyrene, etc. Compounds and their derivatives with fused aromatic rings such as tetraphenyl, triphenylene, perylene, fluoranthene, fluorene, or indene; aromatic amine compounds such as N,N'-dinaphthyl-N,N'-diphenyl-4,4'-diphenyl-1,1'-diamine; metal-chelated oxinoid compounds such as tris(8-quinoline)aluminum(III); or bis(styrene)benzene derivatives; tetraphenylbutadiene derivatives; indene derivatives; coumarin derivatives; oxadiazole derivatives; pyrrolopyridine derivatives; pylrinone derivatives; cyclopentadiene derivatives; pyrrolopyrrole derivatives; thiadiazopyridine derivatives; dibenzofuran derivatives; carbazole derivatives; indolecarbazole derivatives; triazine derivatives; poly(p-styrene) derivatives; poly(p-phenylene) derivatives; polyfluorene derivatives; polyvinylcarbazole derivatives; or polythiophene derivatives; and other polymers. Among them, the main material used in the light-emitting layer structure using triplet light (phosphorescence) is preferably a metal-chelated hydroxyquinoline compound, a dibenzofuran derivative, a dibenzothiophene derivative, a carbazole derivative, an indole-carbazole derivative, a triazine derivative, or a triphenylene derivative.

[0136] Dopant materials contained in luminescent materials can include: compounds with aromatic rings and their derivatives, compounds with heteroaromatic rings and their derivatives, stilbene derivatives, aldazine derivatives, pyrrolemethane derivatives, tetraphenylbutadiene derivatives, zirconia derivatives, aldehyde-pyrazine derivatives, pyrrolemethylene derivatives, diketopyrrolo[3,4-c]pyrrole derivatives, coumarin derivatives, azole derivatives, aromatic amine derivatives, metal ligands of all the above compounds, or compounds represented by the following general formula 4, etc. Among them, dopant materials containing a diamine skeleton and dopant materials containing a fluoranthene skeleton can further improve luminescence efficiency, and compounds represented by the following general formula 4 can further improve luminescence efficiency and lifetime.

[0137]

[0138] In general formula 4, the Za ring, Zb ring, and Zc ring are each independently selected from substituted or unsubstituted aromatic rings with 6 to 30 cyclic carbon atoms, or heteroaromatic rings with substituted or unsubstituted cyclic carbon atoms, respectively. 1 and Z 2 Each atom is independently selected from oxygen, N-Ra (nitrogen atom with substituent Ra), or sulfur. When Z 1 When it is N-Ra, Ra can combine with Za or Zb rings to form a ring, or it can not form a ring. 2 When it is N-Ra, Ra can combine with Zb or Zc rings to form a ring, or it may not form a ring. When Z... 1 and Z 2When N-Ra, each is independently selected from substituted or unsubstituted aryl groups having 6 to 30 cyclic carbon atoms, substituted or unsubstituted heteroaryl groups having 5 to 30 cyclic carbon atoms, or substituted or unsubstituted alkyl groups having 1 to 30 cyclic carbon atoms. In general formula 4, Z 1 and Z 2 All are N-Ra, and Ra is preferably an aryl group with 6 to 30 cyclic carbon atoms, either substituted or unsubstituted. In general formula 4, U is a boron atom, a phosphorus atom, Si-Rb (a silicon atom with a substituent Rb), P=O, or P=S. Rb is selected from substituted or unsubstituted aryl groups with 6 to 30 cyclic carbon atoms, substituted or unsubstituted heteroaryl groups with 5 to 30 cyclic carbon atoms, or substituted or unsubstituted alkyl groups with 1 to 30 cyclic carbon atoms; preferably, Y is a boron atom. Among all the above groups, the substituent is preferably an alkyl, cycloalkyl, heteroalicylic, alkenyl, cycloalkenyl, alkynyl, aryl, heteroaryl, hydroxyl, thiol, alkoxy, alkylthio, aryl ether, aryl thioether, halogen, cyano, aldehyde, acyl, carboxyl, ester, amide, sulfonyl, sulfonate, sulfonamide, amino, nitro, silyl, siloxane, boron, or oxo. Furthermore, these substituents can be further replaced by the aforementioned substituents.

[0139] The alkyl, cycloalkyl, alkoxy, alkylthio, aryl ether, aryl thioether, aryl and heteroaryl groups can be exemplified by the substituents listed above.

[0140] The heteroaliphatic cyclic group includes, for example, an aliphatic ring having atoms other than carbon within the ring, such as a pyran ring, a piperidine ring, or a cyclic amide. It may or may not have substituents. The number of cyclic atoms is not particularly limited, but is preferably in the range of 3 or more and 20 or less.

[0141] The alkenyl group includes, for example, unsaturated aliphatic hydrocarbon groups containing double bonds such as vinyl, allyl, or butadienyl, and may or may not have substituents. The number of carbon atoms in the alkenyl group is not particularly limited, but is preferably in the range of 2 to 20.

[0142] The cycloalkenyl group includes, for example, unsaturated aliphatic cycloalkyl groups containing double bonds such as cyclopentenyl, cyclopentadienyl, or cyclohexenyl, and may or may not have substituents.

[0143] The alkynyl group includes, for example, an ethynyl group, an unsaturated aliphatic hydrocarbon group containing a triple bond, and may or may not have substituents. The number of carbon atoms in the alkynyl group is not particularly limited, but is preferably in the range of 2 to 20.

[0144] Halogens refer to fluorine, chlorine, bromine, or iodine.

[0145] The acyl group includes functional groups such as acetyl, propionyl, benzoyl, or acryloyl, which are carbonyl groups bonded to alkyl, cycloalkyl, alkenyl, alkynyl, aryl, or heteroaryl groups, and may or may not have substituents. The number of carbon atoms in the acyl group is not particularly limited, but is preferably 2 or more and 40 or less, more preferably 2 or more and 30 or less.

[0146] The ester group includes functional groups such as alkyl, cycloalkyl, aryl, or heteroaryl groups bonded by ester bonds, and may or may not have substituents. The number of carbon atoms in the ester group is not particularly limited, but is preferably in the range of 1 to 20. Specifically, examples include methyl ester groups such as methoxycarbonyl, ethyl ester groups such as ethoxycarbonyl, propyl ester groups such as propoxycarbonyl, butyl ester groups such as butoxycarbonyl, isopropyl groups such as isopropoxymethoxycarbonyl, isopropyl ester groups such as cyclohexyloxycarbonyl, or phenyl ester groups such as phenoxycarbonyl.

[0147] The amide group includes functional groups such as alkyl, cycloalkyl, aryl, or heteroaryl groups linked by an amide bond, and may or may not have substituents. The number of carbon atoms in the amide group is not particularly limited, but is preferably in the range of 1 to 20. Specifically, examples include methylamide, ethylamide, propylamide, butylamide, isopropylamide, hexylamide, or phenylamide.

[0148] The sulfonyl group refers to a functional group in which, for example, alkyl, cycloalkyl, aryl, or heteroaryl groups are bonded by a -S(=O)2- bond, and may or may not have substituents. There is no particular limitation on the number of carbon atoms in the sulfonyl group, but it is preferably in the range of 1 to 20.

[0149] The sulfonate group includes functional groups such as alkyl, cycloalkyl, aryl, or heteroaryl groups bonded by a sulfonate bond, and may or may not have substituents. The sulfonate bond is a carbonyl moiety, that is, an ester bond in which -C(=O)- is replaced by a sulfonyl group -S(=O)2-. There is no particular limitation on the number of carbon atoms in the sulfonate group, but it is preferably in the range of 1 to 20.

[0150] The sulfonamide group includes functional groups such as alkyl, cycloalkyl, aryl, or heteroaryl groups linked by a sulfonamide bond, and may or may not have substituents. Here, the sulfonamide bond is an amide bond in which the carbonyl portion (i.e., -C(=O)-) of the amide bond is replaced by a sulfonyl group (-S(=O)2-). The number of carbon atoms in the sulfonamide group is not particularly limited, but is preferably in the range of 1 to 20.

[0151] The amino group may or may not have substituents. The number of carbon atoms in the amino group is not particularly limited, but is preferably in the range of 2 to 50, more preferably in the range of 6 to 40, and even more preferably in the range of 6 to 30.

[0152] The silicon group refers to a functional group bonded with substituted or unsubstituted silicon atoms, including, for example, alkylsilyl groups such as trimethylsilyl, triethylsilyl, tert-butyldimethylsilyl, propyldimethylsilyl, or vinyldimethylsilyl, and arylsilyl groups such as phenyldimethylsilyl, tert-butyldiphenylsilyl, triphenylsilyl, or trinaphthylsilyl. The silicon group may or may not have substituents. There is no particular limitation on the number of carbon atoms in the silicon group, but it is preferably in the range of 1 to 30.

[0153] The siloxane group refers to a silicon compound group formed by an ether bond, including, for example, trimethylsiloxane. Siloxane groups may or may not have substituents.

[0154] Boron groups may or may not have substituents.

[0155] The compounds described by general formula 4 can be exemplified by the following examples.

[0156]

[0157] In the OLED device provided by this invention, the emissive layer preferably contains a material capable of triplet emission. The dopant material used when the emissive layer emits triplet light (phosphorescence) is preferably a metal coordination compound containing at least one metal selected from iridium (Ir), ruthenium (Ru), palladium (Pd), platinum (Pt), osmium (Os), or rhenium (Re). The ligand constituting the metal coordination compound preferably has a nitrogen-containing aromatic heterocycle such as a phenylpyridine backbone, a phenylquinoline backbone, or a carbene backbone. However, the ligand is not limited to these, and suitable ligands can be selected based on the desired emission color, device performance, and relationship with the host material. Specifically, the following compounds can be listed: tris(2-phenylpyridyl)iridium ligand, tris{2-(2-thienyl)pyridyl}iridium ligand, tris{2-(2-benzothienyl)pyridyl}iridium ligand, tris(2-phenylbenzothiazole)iridium ligand, tris(2-phenylbenzoxazole)iridium ligand, tribenzoquinone iridium ligand, bis(2-phenylpyridyl)(acetylacetone)iridium ligand, bis{2-(2-thienyl)pyridyl}iridium ligand, bis{2-(2-benzothienyl)pyridine}(acetylacetone)iridium ligand, bis(2-phenylbenzothiazole)(acetylacetone)iridium ligand Phosphorescent dopant materials, such as bis(2-phenylbenzoxazole)(acetylacetone)iridium ligand, bisbenzoquinone(acetylacetone)iridium ligand, bis{2-(2,4-difluorophenyl))pyridine}(acetylacetone)iridium ligand, tetraethylporphyrin platinum ligand, {tris(difluoroselenodioxide-trifluoroacetone))mono(1,10-phenanthroline)} europium complex, {tris(difluoroselenodioxide-trifluoroacetone)mono(4,7-diphenyl-1,10-phenanthroline)} europium complex, {tris(1,3-diphenyl-1,3-propanedione)mono(1,10-phenanthroline)} europium complex, or triacetylacetone terbium complex, are preferred. Alternatively, phosphorescent dopant materials described in Japanese Patent Application Publication No. 2009-130141 may also be preferred. Iridium or platinum ligands are preferred to further improve luminescence efficiency.

[0158] The triplet luminescent material used as a dopant can be contained in the luminescent layer as a single type, or two or more types can be used in combination. When two or more triplet luminescent materials are used, the total weight of the dopant material is preferably less than 30% by weight relative to the host material, more preferably less than 20% by weight.

[0159] There are no particular limitations on the preferred host and dopant materials in triplet luminescent systems; specific examples include the following compounds:

[0160]

[0161]

[0162] Furthermore, the luminescent layer preferably contains a thermally activated delayed fluorescence (TADF) material. This TADF material is explained on pages 87-103 of *The Most Advanced Organic Electron Technology* (edited by Chinatsu Adachi and Hiroshi Fujimoto, published by CES). In that document, the TADF material is described as follows: This invention increases the probability of reverse energy transfer from the excited triplet state to the excited singlet state, which originally had a very low transfer probability, by bringing the energy levels of the excited singlet and excited triplet states of the fluorescent material closer together. Furthermore, Figure 5 in that document explains the mechanism of delayed fluorescence generation. Delayed fluorescence emission can be confirmed by transient PL (Photoluminescence) testing.

[0163] The thermally activated delayed fluorescence (TADF) material is also commonly referred to as a TADF material. The TADF material can be a single material exhibiting TADF or multiple materials exhibiting TADF. When multiple materials are used, they can be used as a mixture or as stacked layers made from each material. Known materials can be used as TADF materials, including but not limited to benzonitrile derivatives, triazine derivatives, disulfoxide derivatives, carbazole derivatives, indole-carbazole derivatives, dihydrophenazine derivatives, thiazole derivatives, or oxadiazole derivatives.

[0164] The preferred device contains a light-emitting layer with TADF material, which also includes a fluorescent dopant material. This is because when triplet excitons are converted into singlet excitons by the TADF material, and these singlet excitons are then received by the fluorescent dopant material, higher luminous efficiency and longer lifetime can be achieved.

[0165] Electron transport layer

[0166] In this invention, the electron transport layer is a layer that further transports electrons injected from the cathode. An ideal electron transport layer can achieve high electron injection efficiency and efficient transport of the injected electrons. Therefore, the electron transport layer is preferably composed of a material with the following properties: high electron affinity, high electron mobility, and excellent stability, making it difficult to generate impurities that could become traps during manufacturing and use. However, considering the balance of hole and electron transport, if the electron transport layer primarily functions to efficiently prevent holes from the anode from recombinizing and flowing to the cathode side, then even if it is composed of a material with relatively low electron transport capability, the effect of improving luminous efficiency becomes equivalent to that of a material with high electron transport capability. Therefore, the electron transport layer in this invention also includes a material synonymous with a hole blocking layer that efficiently prevents hole migration.

[0167] The electron transport materials used in the electron transport layer can include condensed polycyclic aromatic derivatives such as naphthalene and anthracene, styrene-based aromatic ring derivatives represented by 4,4′-bis(diphenylvinyl)biphenyl, quinone derivatives such as anthraquinone or bi-benzoquinone, phosphorus oxide derivatives, hydroxyquinoline complexes such as tris(8-hydroxyquinoline)aluminum(III), benzo(hydroxyquinoline) complexes, hydroxyazole complexes, azomethine complexes, tropolone metal complexes, and flavonol metal complexes, etc. Considering the need to reduce the driving voltage and obtain high-efficiency luminescence, it is preferable to use compounds with heteroaryl ring structures. The heteroaryl ring structures are composed of elements selected from carbon, hydrogen, nitrogen, oxygen, silicon, and phosphorus, and include electron-accepting nitrogen.

[0168] Aromatic heterocycles containing electron-accepting nitrogen exhibit high electron affinity. Electron transport materials containing electron-accepting nitrogen readily accept electrons from cathodes with high electron affinity, enabling lower voltage driving. Furthermore, the lone pairs of electrons in electron-accepting nitrogen, after incorporating into the large π bond, can accommodate more electrons, increasing electron load and improving electron transport capability. Moreover, the increased electron supply to the luminescent layer leads to a higher recombination probability, thus improving luminescence efficiency.

[0169] Examples of heteroaryl rings containing electron-accepting nitrogen include pyridine rings, pyrazine rings, pyrimidine rings, quinoline rings, quinoxaline rings, naphthidine rings, pyrimidine rings, benzoquinoline rings, phenanthroline rings, imidazole rings, oxazole rings, oxadiazole rings, triazole rings, thiazole rings, thiadiazole rings, benzoxazole rings, benzothiazole rings, benzimidazole rings, or phenanthiazole rings.

[0170] Compounds having these heteroaryl ring structures include, for example, benzimidazole derivatives, benzoxazole derivatives, benzothiazole derivatives, oxadiazole derivatives, thiadiazole derivatives, triazole derivatives, pyrazine derivatives, phenanthroline derivatives, quinoxaline derivatives, quinoline derivatives, benzoquinoline derivatives, oligopyridine derivatives such as bipyridine or terpyridine, quinoxaline derivatives, and naphthidine derivatives as preferred compounds. From the viewpoint of self-electron transport capability, preferably used compounds include imidazole derivatives such as tris(N-phenylbenzimidazole-2-yl)benzene, oxadiazole derivatives such as 1,3-bis[(4-tert-butylphenyl)1,3,4-oxadiazole]benzene, triazole derivatives such as N-naphthyl-2,5-diphenyl-1,3,4-triazole, phenanthroline derivatives such as bathcuproine or 1,3-bis(1,10-phenanthroline-9-yl)benzene, and 2... Benzoquinoline derivatives such as 2′-bis(benzo[h]quinoline-2-yl)-9,9′-spirodifluorene, bipyridine derivatives such as 2,5-bis(6′-(2′,2″-bipyridine))-1,1-dimethyl-3,4-diphenylsilanecyclopentadiene, terpyridine derivatives such as 1,3-bis(4′-(2,2′:6′2″-terpyridyl))benzene, and naphthidine derivatives such as bis(1-naphthyl)-4-(1,8-naphthidin-2-yl)phenylphosphine oxide are preferred. Furthermore, if these derivatives have a condensed polycyclic aromatic skeleton, the glass transfer temperature is increased, the electron mobility is also increased, and the low-voltage effect of the light-emitting element is greater. Additionally, considering improved element lifespan, ease of synthesis, and availability of raw materials, anthracene, pyrene, or phenanthroline skeletons are particularly preferred for condensed polycyclic aromatic skeletons. The aforementioned electron transport materials can be used alone, or two or more of the aforementioned electron transport materials can be used in combination, or one or more other electron transport materials can be mixed into the aforementioned electron transport materials. The compounds of the present invention have high electron injection transport capabilities, and therefore can be used as electron transport materials.

[0171] When using the compounds of the present invention, it is not necessary to limit oneself to one of them; multiple compounds of the present invention may be used in combination, or one or more other electron transport materials may be used in combination with the compounds of the present invention without impairing the effects of the present invention. There are no particular limitations on the miscible electron transport materials, including compounds having condensed aryl rings such as naphthalene, anthracene, and pyrene, or their derivatives; styrene-based aromatic ring derivatives represented by 4,4′-bis(diphenylvinyl)biphenyl; perylene derivatives; violet ring ketone derivatives; coumarin derivatives; naphthalenedicarboximide derivatives; quinone derivatives such as anthraquinone or bi-benzoquinone; phosphorus oxide derivatives; carbazole derivatives and indole derivatives; hydroxyquinoline complexes such as tris(8-hydroxyquinoline)aluminum(III) or hydroxyazole complexes such as hydroxyphenyloxazole complexes; azomethyl complexes; tyrosine metal complexes; and flavonol metal complexes.

[0172] The aforementioned electron transport materials can be used alone, or two or more of the aforementioned electron transport materials can be used in combination, or one or more other electron transport materials can be mixed into the aforementioned electron transport materials. Furthermore, they may contain donor materials. Here, the donor material is a compound that improves the electron injection barrier, facilitating electron injection from the cathode or electron injection layer to the electron transport layer, and further enhancing the conductivity of the electron transport layer.

[0173] Preferred examples of donor materials in this invention include alkali metals, inorganic salts containing alkali metals, complexes of alkali metals and organic compounds, alkaline earth metals, inorganic salts containing alkaline earth metals, or complexes of alkaline earth metals and organic compounds. Preferred types of alkali metals and alkaline earth metals include lithium, sodium, cesium, ytterbium, and other alkali metals and their compounds, which have low work function and significantly improve electron transport capabilities, or magnesium, calcium, and other alkaline earth metals and their compounds.

[0174] The appropriate doping concentration varies depending on the material or the film thickness of the doped region. For example, when the donor material is an inorganic material such as an alkali metal or alkaline earth metal, it is preferable to co-deposit the electron transport layer by a deposition rate ratio of 10000:1 to 2:1 between the electron transport material and the donor material. A more preferred deposition rate ratio is 100:1 to 5:1, and even more preferred is 100:1 to 10:1. Furthermore, when the donor material is a complex of a metal and an organic compound, it is preferable to co-deposit the electron transport layer by a deposition rate ratio of 100:1 to 1:100 between the electron transport material and the donor material. A more preferred deposition rate ratio is 10:1 to 1:10, and even more preferred is 7:3 to 3:7.

[0175] Furthermore, the electron transport layer doped with donor material in the compounds of the present invention as described above can be used as a charge generation layer in a series structure element that connects multiple light-emitting elements.

[0176] The method of improving electron transport capability by doping the electron transport layer with donor materials is particularly effective when the film thickness is relatively thick. It is especially preferred when the combined thickness of the electron transport layer and the emitting layer is 50 nm or more. For example, there are methods that utilize interference effects to improve luminous efficiency, which involve aligning the phase of light directly emitted from the self-emitting layer with the light reflected by the cathode, thereby increasing the light emission efficiency. The optimal conditions vary depending on the emission wavelength; when the combined thickness of the electron transport layer and the emitting layer is 50 nm or more, and the light emits at a red wavelength, a film thickness approaching 100 nm may be possible.

[0177] The thickness of the doped electron transport layer can be arbitrary, consisting of part or all of the electron transport layer. When doping only a portion, it is ideal to have a doped region at least at the electron transport layer / cathode interface; even doping only near the cathode interface can achieve a low-voltage effect. On the other hand, if the donor material is directly in contact with the light-emitting layer, it can have an adverse effect that reduces luminous efficiency. In this case, it is preferable to have an undoped region at the light-emitting layer / electron transport layer interface.

[0178] The aforementioned electron transport materials can be used alone, or two or more of the aforementioned electron transport materials can be mixed, or one or more other electron transport materials can be mixed with the aforementioned electron transport materials.

[0179] The electron transport layer may contain a donor material. The donor material is a compound that improves the electron injection barrier, facilitates the injection of electrons from the cathode or electron injection layer into the electron transport layer, and further improves the conductivity of the electron transport layer.

[0180] From the perspective of reducing the work function and improving electron transport performance, the donor material preferably contains alkali metal atoms, alkaline earth metal atoms, or rare earth metal atoms. From the perspective of further reducing the driving voltage of OLEDs, it is more preferable to contain alkali metal atoms, rare earth metal atoms, or copper group metal atoms.

[0181] Furthermore, considering ease of vapor deposition in a vacuum and convenient operation, the donor material is preferably an inorganic salt or a ligand formed by a metal and an organic compound, rather than a pure metal. Additionally, considering ease of operation in the atmosphere and convenient adjustment of the addition concentration, a ligand formed by a metal and an organic compound is preferred. Examples of inorganic salts include oxides, nitrides, fluorides, or carbonates. Preferred examples of organic compounds that form ligands with organic compounds include hydroxyquinoline, benzo[a]hydroxyquinoline, pyridylphenol, flavonols, hydroxyimidazo[a]pyridine, hydroxybenzo[a]azole, or hydroxytriazole. From the viewpoint of further reducing the driving voltage of OLED devices, ligands formed by alkali metals and organic compounds are preferred. Furthermore, from the viewpoint of ease of synthesis and thermal stability, ligands formed by lithium and organic compounds are more preferred, and lithium hydroxyquinoline (Liq), which can be obtained at a relatively low cost, is particularly preferred.

[0182] There are no particular limitations on the ionization potential of the electron transport layer, but it is preferably 5.6 eV or higher and 8.0 eV or lower, more preferably 5.6 eV or higher and 7.0 eV or lower.

[0183] Electron injection layer

[0184] In this invention, an electron injection layer can be disposed between the cathode and the electron transport layer. Typically, the function of introducing the electron injection layer is to facilitate the injection of electrons from the cathode into the electron transport layer. When using this layer, it can be a compound having a heteroaromatic ring structure containing electron-accepting nitrogen, or it can be a layer containing the aforementioned donor material.

[0185] Alternatively, the electron injection layer can also use inorganic materials such as insulators or semiconductors; well-known materials can be used. By using these materials, short circuits in OLED devices can be suppressed, and electron injection performance can be improved.

[0186] The insulator is preferably at least one metal compound selected from the group consisting of alkali metal chalcogenides, alkaline earth metal chalcogenides, alkali metal halides, or alkaline earth metal halides.

[0187] Furthermore, organic and metallic ligands are also suitable for use. When organic and metallic ligands are used in the electron injection layer, the film thickness can be easily adjusted. Preferred examples of organic compounds in organometallic ligands include hydroxyquinoline, benzo[a]hydroxyquinoline, pyridylphenol, flavonols, hydroxyimidazo[a]pyridine, hydroxybenzo[a]azole, or hydroxytriazole. The methods for forming the above-mentioned layers constituting the light-emitting element are resistance heating evaporation, electron beam evaporation, sputtering, molecular lamination, coating, etc., and there are no particular limitations. Generally, considering the characteristics of the element, resistance heating evaporation or electron beam evaporation is preferred.

[0188] Charge generation layer

[0189] The charge generation layer in this invention typically consists of two layers. Specifically, a PN junction charge generation layer composed of an N-type charge generation layer and a P-type charge generation layer is preferred. When a voltage is applied to the OLED device, the PN junction charge generation layer generates charge, which separates into holes and electrons. The generated holes are injected into the light-emitting layer through the hole transport layer, and the electrons are injected into the light-emitting layer through the electron transport layer. A specific example of the charge generation layer's usage is as follows: In an OLED device with multiple stacked light-emitting layers, this layer is positioned between the multiple light-emitting layers and has a charge generation function. The N-type charge generation layer provides electrons to the first light-emitting layer located on the anode side, and the P-type charge generation layer provides holes to the second light-emitting layer located on the cathode side. Therefore, OLED devices with multiple stacked light-emitting layers can further improve luminous efficiency, reduce driving voltage, and increase lifetime.

[0190] The N-type charge-generating layer is composed of an N-type dopant material and a host material, and conventional materials can be used. For example, alkali metals, alkaline earth metals, or rare earth metals can be used as the N-type dopant material. The host material can be a compound with a nitrogen-containing aromatic heterocycle, such as a phenanthroline derivative or an oligopyridine derivative. In particular, compounds represented by general formula 1 or phenanthroline dimers are preferred because they exhibit excellent host material properties for the N-type charge-generating layer.

[0191] As one embodiment of the charge-generating layer, it is preferable to contain a phenanthroline derivative. Examples of phenanthroline derivatives include the following compounds:

[0192]

[0193] As one embodiment of the charge-generating layer, it preferably contains alkali metal atoms, copper group atoms, or rare earth metal atoms. The alkali metal atoms are preferably Li atoms. The copper group atoms are preferably Ag atoms. The rare earth metal atoms are preferably Yb atoms.

[0194] As one embodiment of the charge generation layer, a structure comprising phenanthroline derivatives and alkali metal atoms, copper group atoms, or rare earth metal atoms is further preferred.

[0195] The p-type charge generation layer is composed of a p-type dopant and a host material, and can be made of conventional materials. For example, the p-type dopant can be tetrafluoro-7,7,8,8-tetracyanoquinone dimethane (F4-TCNQ), a tetracyanoquinone dimethane derivative, an axialene derivative, iodine, FeCl3, FeF3, or SbCl5, etc. An axialene derivative is preferred as the p-type dopant. An arylamine derivative is preferred as the host material.

[0196] The thickness of the organic layer is determined by the resistance value of the luminescent material and therefore cannot be limited; preferably, it is 1 nm to 1000 nm. The film thicknesses of the luminescent layer, electron transport layer, and hole transport layer are preferably 1 nm or more and 200 nm or less, respectively, and more preferably 5 nm or more and 100 nm or less.

[0197] There are no particular limitations on the methods for forming the layers that constitute an OLED device. Examples include resistance evaporation, electron beam evaporation, sputtering, molecular lamination, coating, or printing. From the perspective of device characteristics, resistance evaporation or electron beam evaporation is preferred.

[0198] The light-emitting element of this invention has the function of converting electrical energy into light. Here, the electrical energy is mainly direct current, but pulsed current or alternating current can also be used. There are no particular limitations on the current and voltage values; however, when considering the power consumption or lifespan of the element, it should be selected in a way that obtains maximum brightness using the lowest possible energy.

[0199] The light-emitting element of the present invention can also be preferably used as backlighting for various devices, etc. Backlighting is mainly used to improve the visibility of non-self-emissive display devices, and is used in liquid crystal display devices, clocks, audio devices, automotive panels, display boards, and signs, etc. In particular, the light-emitting element of the present invention is preferably used in the backlighting of liquid crystal display devices (especially for personal computers where thinning has been studied), which can provide a thinner and lighter backlight than existing backlights.

[0200] [Example]

[0201] The present invention will now be described with reference to examples, but the invention is not limited to these examples. The materials used in the examples and comparative examples are as follows:

[0202] Toluene, xylene, methanol, etc. were purchased from Sinopharm Company;

[0203] Azabenzene compounds were purchased from TCI;

[0204] Dibenzofurans, dibenzothiophene compounds and other intermediates were purchased from Bid Pharmaceuticals.

[0205] Various catalysts were purchased from Aldrich.

[0206] The evaluation methods for each embodiment and comparative example will be explained below:

[0207] (1) Driving voltage: The OLED devices obtained in the examples and comparative examples were driven at 1000 cd / m². 2 The brightness was measured by the driving voltage. The brightness was obtained using a LUMINANCE METER (BM-9) luminance meter manufactured by TOPCON.

[0208] (2) Luminous efficiency: The OLED devices obtained in the examples and comparative examples were compared at 10 mA / cm². 2 The light was illuminated at a current density, and the external quantum efficiency was measured using a spectrophotometer (manufactured by Conicaminolta Co., Ltd.) to evaluate the luminous efficiency. The higher the external quantum efficiency, the better the luminous efficiency.

[0209] (3) Lifetime: The OLED devices obtained in the examples and comparative examples were subjected to a lifetime of 10 mA / cm². 2 The constant current continuously driven, the time required for the brightness to decrease by 10% from the initial brightness is the lifespan. The brightness is measured by a LUMINANCEMETER (BM-9) luminance meter manufactured by TOPCON.

[0210] Synthesis example 1

[0211] Synthesis of compound [4]

[0212]

[0213] 7.5 g of raw material A, 6.2 g of raw material B, and 7.33 g of potassium carbonate were added to a mixed solvent of 241 mL of DME and 53 mL of water. After purging with nitrogen three times, 0.34 g of di-triphenylphosphine palladium dichloride was added under a nitrogen atmosphere, and the mixture was heated to reflux and stirred for 1 hour. After cooling to room temperature, water was added and stirred for 1 hour, filtered, and then water was added again and stirred for 1 hour. After filtration, the mixture was dried under vacuum to obtain 10.7 g of intermediate A.

[0214] 10.7 g of intermediate A, 6.98 g of pinacol diborate, and 7.36 g of potassium acetate were added to 325 mL of 1,4-dioxane. After purging three times with nitrogen, a mixture of 0.28 g of bis(dibenzylacetone)palladium and 0.52 g of 2-dicyclohexylphosphine-2',4',6'-triisopropylbiphenyl was added under a nitrogen atmosphere. The mixture was then heated under reflux and stirred for 1.5 hours. After cooling to room temperature, water was added and stirred for 1 hour. The mixture was filtered, then water was added again and stirred for 1 hour. After filtration, the mixture was dried under vacuum to obtain 12.91 g of intermediate B.

[0215] 12.91 g of intermediate B, 6.47 g of raw material C, and 14.12 g of potassium phosphate trihydrate were added to a mixed solvent of DME and water. After purging with nitrogen three times, 0.34 g of di-triphenylphosphine palladium dichloride was added under a nitrogen atmosphere, and the mixture was heated to reflux and stirred for 2 hours. After cooling to room temperature, water was added and stirred for 1 hour, filtered, and then water was added again and stirred for 1 hour. After filtration and vacuum drying, 14.39 g of intermediate C was obtained.

[0216] 5.84 g of raw material D, 6.48 g of raw material E, and 7.33 g of potassium carbonate were added to a mixed solvent of 241 mL of DME and 53 mL of water. After purging with nitrogen three times, 0.34 g of di-triphenylphosphine palladium dichloride was added under a nitrogen atmosphere, and the mixture was heated to reflux and stirred for 1 hour. After cooling to room temperature, water was added and stirred for 1 hour, then filtered. Water was added again and stirred for 1 hour, then filtered again and dried under vacuum to obtain 9.30 g of intermediate D.

[0217] 9.3 g of intermediate D, 14.39 g of intermediate C, and 14.12 g of potassium phosphate trihydrate were added to a mixed solvent of 241 mL THF and 53 mL water. After purging with nitrogen three times, 0.34 g of methanesulfonic acid (2-dicyclohexylphosphino-2',4',6'-triisopropyl-1,1'-biphenyl)(2'-amino-1,1'-biphenyl-2-yl)palladium(II) was added under a nitrogen atmosphere. The mixture was then heated under reflux and stirred for 3 hours. After cooling to room temperature, water was added and stirred for 1 hour. The mixture was filtered, and then water was added again and stirred for 1 hour. After filtration, the mixture was dried under vacuum to obtain 21.98 g of crude product. The crude product was recrystallized twice with xylene to obtain 15.88 g of compound 4.

[0218] Using an oil diffusion pump at approximately 320°C, 1×10 -3 Compound 4 was purified by sublimation under a pressure of Pa. The HPLC purity (area %) of compound 4 before sublimation purification was 99.9%. The HPLC purity (area %) of compound 4 after sublimation purification was 99.95%. 14.3 g of compound 4 was obtained after sublimation purification.

[0219] After sublimation purification, the structure of compound 4 was identified by mass spectrometry (MS) and 1H-NMR analysis. The analytical results are shown below.

[0220] MS(m / z): 533[M+H]+

[0221] δ: 9.45-9.42 (m, 1H), 9.20-8.45 (m, 23H), 8.35-8.16 (m, 6H), 8.10-7.88 (m, 4H), 7.78-7.65 (m, 4H), 2.56-2.54 (m, 3H).

[0222] Light-emitting element manufacturing

[0223] A glass substrate (manufactured by Geomatec Co., Ltd., 11Ω / □, sputtered) with a 165nm ITO transparent conductive film deposited on it was cut into 38mm × 46mm pieces and etched. The resulting substrate was ultrasonically cleaned for 15 minutes using SemicoClean 56 (trade name, manufactured by Furuuchi Chemical Co., Ltd.), and then rinsed with ultrapure water. Before component fabrication, the substrate was subjected to a 1-hour ultraviolet (UV)-ozone treatment in a vacuum evaporation apparatus, with exhaust gas applied until the vacuum level reached 5 × 10⁻⁶. -4 Below Pa. Using a resistance heating method, a 75 nm HAT-CN6 layer was first deposited as a hole injection layer, and a 42.5 nm HT-1 layer was deposited as a hole transport layer. Then, the host material H-1 and the dopant material D-1 were deposited at a doping concentration of 5% by weight to a thickness of 20 nm as the light-emitting layer. Next, compound 4 was deposited to a thickness of 30 nm as the electron transport layer. Then, 1 nm of Yb was deposited, followed by 15 nm of Mg / Aa (1:9) as the cathode, to fabricate a 5 mm × 5 mm square element. The film thickness referred to here is the value displayed by a quartz oscillating film thickness monitor (Conltaec's Eon LT). The light-emitting element has a 10 mA / cm² thickness. 2The characteristics at that time were a driving voltage of 3.79V and an efficiency of 7.05cd / A. Furthermore, the initial brightness was set to 10mA / cm. 2 The lifetime was determined by the time it takes for the brightness to decrease by 10% when driven by a constant current, resulting in 233 hours. HAT-CN6, HT-1, H-1, and D-1 are the compounds listed below.

[0224]

[0225] Following the synthesis method described above, suitable raw materials were selected to synthesize other embodiments and fabricate light-emitting elements. The compounds used in the comparative examples are shown below.

[0226]

[0227] Table 1 lists the experimental results of each embodiment and comparative example.

[0228] [Table 1]

[0229] Compound numbering Voltage (V) Luminous efficiency (Cd / A) Lifespan (h) Example 1 4 3.79 7.05 233 Example 2 12 3.75 7.08 236 Example 3 14 3.78 7.12 240 Example 4 17 3.80 7.12 236 Example 5 22 3.66 7.35 258 Example 6 26 3.70 7.32 259 Example 7 33 3.71 7.28 264 Example 8 37 3.68 7.30 261 Example 9 42 3.72 7.25 259 Example 10 62 3.66 7.26 263 Example 11 73 3.73 7.33 256 Example 12 78 3.65 7.35 255 Example 13 95 3.70 7.36 258 Example 14 110 3.77 7.28 258 Example 15 111 3.73 7.33 261 Example 16 115 3.69 7.31 263 Example 17 124 3.61 7.42 269 Example 18 134 3.59 7.45 276 Example 19 152 3.58 7.46 273 Example 20 187 3.54 7.49 280 Example 21 200 3.52 7.52 282 Example 22 206 3.51 7.52 282 Example 23 226 3.46 7.66 288 Example 24 230 3.48 7.68 286 Example 25 235 3.48 7.61 289 Example 26 297 3.35 7.79 293 Example 27 309 3.43 7.76 296 Example 28 310 3.36 7.78 299 Example 29 326 3.55 7.49 263 Example 30 329 3.58 7.50 265 Example 31 330 3.54 7.53 266 Example 32 366 3.38 7.58 274 Example 33 375 3.39 7.62 276 Example 34 403 3.42 7.65 274 Example 35 409 3.36 7.78 289 Example 36 430 3.35 7.72 293 Example 37 435 3.36 7.44 288 Example 38 470 3.69 7.33 263 Example 39 475 3.66 7.29 261 Example 40 476 3.67 7.74 261 Example 41 485 3.69 7.39 259 Example 42 489 3.70 7.36 262 Example 43 511 3.62 7.44 269 Example 44 512 3.63 7.46 268 Comparative Example 1 A 3.93 5.30 194 Comparative Example 2 B 3.91 5.19 199 Comparative Example 3 C 4.00 4.90 195 Comparative Example 4 D 3.96 5.12 199 Comparative Example 5 E 4.22 4.95 189 Comparative Example 6 F 4.09 5.23 192 Comparative Example 7 G 4.25 5.00 191 Comparative Example 8 H 4.22 5.16 194

[0230] Comparative Examples 1-7 are known dual-host compounds combining an azirbenzene host and a dibenzoheterocyclic host, while Comparative Example 8 is a commonly used compound in the art consisting of an azirbenzene host and fluoranthene. Comparing the examples with the comparative examples, it can be seen that, overall, the compounds provided by this invention, when used in the electron transport layer of organic light-emitting devices, have the effects of reducing voltage, improving efficiency, and increasing lifetime.

[0231] Compared with Examples 1-4, when the azirbenzene host is connected to one of Q2, Q3, Q6, or Q7 of the dibenzoheterocyclic host via the L chain, the voltage of the light-emitting element is further reduced, and the efficiency and lifespan are further improved.

[0232] Compared with Examples 1-4, Examples 8-10 have a nitrogen content of 3 in the azirbenzene matrix, with each nitrogen atom separated by a carbon atom. This symmetrical structure gives the light-emitting element a longer lifespan, lower driving voltage, and higher luminous efficiency.

[0233] Compared with Examples 1-4, Examples 11-13 contain 2 nitrogen atoms in the azirbenzene matrix, with a carbon atom in between, thus forming a symmetrical structure, resulting in a lower driving voltage and higher luminous efficiency.

[0234] The results from Examples 8-10 and Examples 11-13 also confirm the previous theory: when the amount of nitrogen in the azirbenzene host is 3, the lifetime is relatively longer, and when the amount of nitrogen in the azirbenzene host is 2, the luminous efficiency is relatively higher.

[0235] Compared to Examples 1-4, Examples 14-16 have an L-chain length of n equal to 4 or n equal to 5. Compared to Examples 1-4 where n equals 6 or 7, Examples 14-16 shorten the L-chain length, which reduces the difficulty of vapor deposition while increasing electron transport performance. In light-emitting elements, this results in lower voltage, higher efficiency, and improved molecular stability, thus leading to a longer lifespan.

[0236] Compared to Examples 17-19, Examples 20-22 exhibit a superior lifespan due to the relatively simple composition of the L-chain, making vapor deposition easier. The absence of substituents at L3 minimizes interference from other substituents as electrons move towards the dibenzohexane host, resulting in strong electron transport performance. Furthermore, the increased number of electrons binding with holes at the luminescent layer leads to lower voltage and higher efficiency in the light-emitting element.

[0237] Compared to Examples 20-22, Examples 23-25 ​​have a simpler composition in the L-chain, making vapor deposition easier and thus resulting in a longer lifespan. Furthermore, the relatively simple structure and smooth intermolecular stacking further enhance electron transport performance, leading to a lower driving voltage and higher luminous efficiency.

[0238] Compared with Examples 23-25, Examples 26-28 show that the synthesized molecules are more stable due to the ortho-para substitution effect on the benzene ring, which also results in a better lifespan for the light-emitting element. Furthermore, the combination of ortho-para substitution improves the overall performance of the element.

[0239] Compared to Examples 29-31, Examples 32-34 have a simpler composition in the L-chain, making vapor deposition easier and thus resulting in a longer lifespan. Furthermore, the relatively simple structure and smooth intermolecular stacking further enhance electron transport performance, leading to a lower driving voltage and higher luminous efficiency.

[0240] Compared with Examples 32-34, the L-chain portion of Examples 35-37 is phenylene, and the ability of the molecule to transport electrons is moderate. This makes the compound used in this invention, when used as an electron transport layer, better matched with the surrounding electron injection layer and hole blocking layer, thus achieving better device performance.

[0241] Compared to Examples 1-4, Examples 38-40 confirmed that the heteroatom in the dibenzoheterocyclic host is an oxygen atom, which has a superior electron transport capability. Therefore, superior device performance was obtained.

[0242] Compared with Examples 1-4, Examples 41-42 limit the substituents on the dibenzoheterocyclic host to a relatively simple structural range or to be unsubstituted, which is also beneficial to molecular stability and improves electron transport efficiency. As can be seen from the comparison, Examples 41-42 have superior device performance.

[0243] Compared with Examples 41-42, Examples 43-44 have no other substituents in the main body of the dibenzoheterocyclic ring, and its electron cloud distribution is more uniform and electron transport is more stable, thus exhibiting superior component performance.

[0244] In summary, compared with the compounds provided by this invention, the compounds used in the comparative examples have too short L chains and too small molecular weights in the main chain, resulting in low stability during vapor deposition. In contrast, the compounds provided by this invention have longer L chains, and after being connected to the dual host, they have a moderate molecular weight and smoother intramolecular electron movement, thus resulting in lower driving voltage, higher efficiency, and longer lifespan.

[0245] However, it should be noted that the device is not a linear summation of the properties of each layer of material, but rather a combination of multiple layers. Therefore, when the surrounding materials change, there will be a corresponding optimal electron transport layer material. Thus, this invention provides a series of materials to allow for the adjustment of molecules for different practical devices.

Claims

1. A compound represented by the following general formula 1, in, X1, X2, X3, X4 or X5 may be the same or different, each being a nitrogen atom or CR1, CR2 or CR3, and at least two of them are nitrogen atoms; L is independently selected from aryl groups having 6 to 60 substituted carbon atoms or heteroaryl groups having 2 to 60 substituted carbon atoms; n is 4, 5, 6, or 7; Any one of Q1, Q2, Q3, Q4, Q5, Q6, Q7, or Q8 is connected to L, and the others are CR4, CR5, CR6, CR7, CR8, CR9, or CR 10 ; The R1, R2, R3, R4, R5, R6, R7, R8, R9, or R 10 It is independently selected from hydrogen, deuterium, cyano, substituted alkyl, substituted cycloalkyl, substituted heterocyclic, substituted alkenyl, substituted cycloalkenyl, substituted alkynyl, substituted alkoxy, substituted alkylthio, substituted aryl ether, substituted aryl thioether, substituted aryl, substituted heteroaryl, substituted carbonyl, substituted carboxyl, substituted oxycarbonyl, substituted carbamoyl, substituted silyl, substituted alkylamino, or substituted arylamino; Y represents an oxygen atom or a sulfur atom; Each of the substituted groups is independently selected from one or more of hydrogen, deuterium, cyano, substituted alkyl, substituted cycloalkyl, substituted heterocyclic, substituted alkenyl, substituted cycloalkenyl, substituted alkynyl, substituted alkoxy, substituted alkylthio, substituted aryl ether, substituted aryl thioether, substituted aryl, substituted heteroaryl, substituted carbonyl, substituted carboxyl, substituted oxycarbonyl, substituted carbamoyl, substituted silyl, substituted alkylamino, or substituted arylamino.

2. The compound according to claim 1, characterized in that, One of Q2, Q3, Q6 or Q7 is connected to L.

3. The compound according to claim 1, characterized in that, X1, X3, and X5 are nitrogen atoms, and X2 or X4 are CR1 or CR2, respectively.

4. The compound according to claim 1, characterized in that, Any two of X1, X3, or X5 are nitrogen atoms, the remaining one is CR3, and X2 or X4 are CR1 or CR2 respectively.

5. The compound according to claim 1, characterized in that, The n is equal to 4 or 5.

6. The compound according to claim 5, characterized in that, Where n equals 4, general formula 1 is represented by the following general formula 2. L1, L2, L3, or L4 are each independently selected from substituted phenyl, substituted pyridyl, or substituted pyrimidinyl groups.

7. The compound according to claim 6, characterized in that, The L1, L2, or L4 are each independently selected from substituted phenyl, substituted pyridyl, or substituted pyrimidinyl groups; The L3 is selected from phenylene, pyridinyl, or pyrimidinyl.

8. The compound according to claim 7, characterized in that, L1, L2, L3, or L4 are all phenylene oxides.

9. The compound according to claim 8, characterized in that, The connection site between any one of L1, L2, L3 or L4 and its adjacent group is either ortho or para.

10. The compound according to claim 5, characterized in that, Where n equals 5, general formula 1 is represented by the following general formula 3. L5, L6, L7, L8, or L9 are each independently selected from substituted phenyl, substituted pyridyl, or substituted pyrimidinyl groups.

11. The compound according to claim 10, characterized in that, The L5, L6, L7, L8, or L9 are independently selected from phenylene, pyridinyl, or pyrimidinyl.

12. The compound according to claim 11, characterized in that, L5, L6, L7, L8, or L9 are all phenylene oxides.

13. The compound according to claim 1, characterized in that, The Y is an oxygen atom.

14. The compound according to claim 1, characterized in that, The R4, R5, R6, R7, R8, R9, or R 10 Each is independently selected from hydrogen, deuterium, cyano or phenyl.

15. The compound according to claim 14, characterized in that, The R4, R5, R6, R7, R8, R9, or R 10 Selected from hydrogen.

16. A light-emitting element comprising an organic layer between an anode and a cathode, wherein, The organic layer contains any one of the compounds according to claims 1-15.

17. The light-emitting element according to claim 16, characterized in that, The organic layer includes an electron transport layer, which contains the compound according to any one of claims 1-15.

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