Novel compound and organic light-emitting element comprising same

Abstract

The present invention relates to a novel compound and an organic light-emitting element comprising same and, more specifically, to: a novel compound which is represented by chemical formula 1 and has 4,5-diazaspirobifluorene as a central core and can thus be applied to a charge generation layer (CGL) in a tandem element and particularly, to a host of an n-type charge generation layer (nCGL); and a tandem organic light-emitting element comprising same, and can achieve a low voltage, high efficiency, and a long lifespan.

Description

Novel compound and organic light-emitting device containing the same

[0001] The present invention relates to a novel compound and an organic light-emitting device comprising the same, and more particularly, to a novel compound applicable to a host of a charge generation layer (CGL), particularly an N-type charge generation layer (N-CGL), in a tandem-type organic light-emitting device comprising a plurality of light-emitting layers and having 4,5-diazaspirobifluorene as a core, and an organic light-emitting device comprising the same.

[0002] The technology of organic light emitting devices (OLEDs), one of the currently widely used flat panel display devices, is developing rapidly.

[0003] In general, an organic light-emitting device has an organic thin film layer including a light-emitting layer formed between an anode (hole injection electrode) and a cathode (electron injection electrode), and has a principle of emitting light when holes injected from the anode and electrons injected from the cathode pair up in the light-emitting layer and then disappear.

[0004] More specifically, the organic light-emitting device is configured to include an organic thin film layer formed between an anode and a cathode, and the organic thin film layer may be configured to include a hole injection layer, a hole transport layer, a light-emitting layer, an electron transport layer, and an electron injection layer sequentially laminated on the anode, and holes injected from the anode and electrons injected from the cathode combine in the light-emitting layer to form excitons, which enter an unstable energy state (excited state) and then return to a stable ground state to emit light.

[0005] In the development of organic light-emitting devices, high efficiency, long lifespan, color purity, color stability according to changes in current and voltage, and ease of device manufacturing are important, so research and development are in progress according to each method. The structure of organic light-emitting devices can be broadly divided into a single-layer light-emitting structure with one light-emitting layer and a multilayer light-emitting structure with two or more light-emitting layers. Among these, a tandem structure of a multilayer light-emitting structure that stacks two or more light-emitting layers is mainly adopted for organic light-emitting devices with long lifespan.

[0006] Meanwhile, an organic light-emitting device having a tandem structure such as this is provided with a charge generation layer (CGL) between the light-emitting layers to double the current efficiency generated in the light-emitting layer and to facilitate charge distribution. This charge generation layer is a layer that generates charges, that is, electrons and holes, and performs the role of preventing an increase in the driving voltage by doubling the current efficiency generated in the light-emitting layer and facilitating charge distribution. This charge generation layer is generally composed of a P-type charge generation layer and an N-type charge generation layer.

[0007] Currently, most compounds used as hosts for charge generation layers, especially N-type charge generation layers, have phenanthroline (1,10-phenanthroline) as their core. However, as the development of high-performance devices is increasingly required, there is a need to develop new cores that can exhibit superior performance to the phenanthroline core.

[0008] An object of the present invention is to provide a novel compound suitable for a host material of a charge generation layer, particularly an N-type charge generation layer, in a tandem organic light-emitting device including a plurality of light-emitting layers, and an organic light-emitting device including the same.

[0009] The above object of the present invention is achieved through a novel compound represented by the following chemical formula 1 and an organic light-emitting device comprising the same, and the novel compound of the present invention can be applied to a charge generation layer of a tandem organic light-emitting device comprising two or more light-emitting layers.

[0010]

[0011] In the above chemical formula 1,

[0012] L1 and L2 are each independently a direct bond, a substituted or unsubstituted arylene group, or a substituted or unsubstituted heteroarylene group,

[0013] Ar1 and Ar2 are each independently selected from the group consisting of deuterium, halogen, cyano group, nitro group, nitrile group, substituted or unsubstituted alkyl group, substituted or unsubstituted alkenyl group, substituted or unsubstituted alkynyl group, substituted or unsubstituted cycloalkyl group, substituted or unsubstituted heterocycloalkyl group, substituted or unsubstituted alkoxy group, substituted or unsubstituted sulfide group, substituted or unsubstituted aryl group, substituted or unsubstituted heteroaryl group, substituted or unsubstituted aryloxy group, substituted or unsubstituted heteroaryloxy group, substituted or unsubstituted thio group, substituted or unsubstituted amine group, substituted or unsubstituted silyl group, and substituted or unsubstituted phosphine oxide group,

[0014] m and n are each independently integers from 1 to 3.

[0015] The compound of the present invention has 4,5-diazaspirobifluorene, in which N is applied to the 4th and 5th positions of spirobifluorene, as a core, and can provide a novel compound applicable to an N-type charge generation layer in a tandem device, and an organic light-emitting device including the same. Such a 4,5-diazaspirobifluorene core introduces an SP3 hybrid orbital carbon into the phenanthroline core, which is widely used in the existing N-type charge generation layer, thereby preventing an increase in the conjugation length, thereby reducing electron absorption and improving electron mobility, resulting in an increase in the efficiency and lifespan of the device and a decrease in the driving voltage, making it more suitable for an N-type charge generation layer.

[0016] FIG. 1 is a schematic diagram schematically showing a tandem organic light-emitting device according to one embodiment of the present invention.

[0017] In this specification, when a part is said to 'include' a certain component, this does not mean that other components are excluded, but rather that other components may be included, unless otherwise specifically stated.

[0018] In this specification, when it is said that a member is located 'on' another member, this includes not only cases where a member is in contact with another member, but also cases where another member exists between the two members.

[0019] In this specification, examples of substituents are described below, but are not limited thereto.

[0020] As used herein, the term "substitution" refers to the replacement of a hydrogen atom bonded to a carbon atom of a compound with another substituent. The position of substitution is not particularly limited as long as it is a position where substitution is possible, and when substitution is made with two or more substituents, the substituents may be the same or different.

[0021] In this specification, the term 'substituted or unsubstituted' means that it is substituted with one or more substituents selected from the group consisting of deuterium, halogen, cyano, nitro, nitrile, alkyl, alkenyl, alkynyl, cycloalkyl, heterocycloalkyl, alkoxy, sulfide, aryloxy, heteroaryloxy, thio, amine, silyl, phosphine oxide, aryl, and heteroaryl groups, or is substituted with a substituent in which two or more substituents selected from the above group are connected, or has no substituents, and the selected substituents may or may not form a ring by combining with each other. An example of a substituent in which two or more substituents are connected is a biphenyl group. That is, a biphenyl group may correspond to an aryl group and at the same time correspond to a substituent having two phenyl groups connected, and at the same time correspond to an aryl group having one phenyl group substituted.

[0022] In the present specification, the alkyl group may be a straight or branched chain having 1 to 60 carbon atoms, and specific examples thereof include methyl, ethyl, propyl, n-propyl, isopropyl, butyl, n-butyl, isobutyl, tert-butyl, sec-butyl, 1-methylbutyl, 1-ethylbutyl, pentyl, n-pentyl, isopentyl, neopentyl, tert-pentyl, hexyl, n-hexyl, 1-methylpentyl, 2-methylpentyl, 3,3-dimethylbutyl, 2-ethylbutyl, heptyl, n-heptyl, 1-methylhexyl, cyclopentylmethyl, cyclohexylmethyl, octyl, n-octyl, tert-octyl, 1-methylheptyl, 2-ethylhexyl, 2-propylpentyl, n-nonyl, 2,2-dimethylheptyl, 1-ethylpropyl, Examples thereof include, but are not limited to, 1,1-dimethylpropyl, isohexyl, 2-methylpentyl, 4-methylhexyl, and 5-methylhexyl. Specifically, the alkyl group may have 1 to 30 carbon atoms, and more specifically, 1 to 20 carbon atoms.

[0023] In the present specification, the alkenyl group may be a straight or branched chain having 2 to 60 carbon atoms, and specific examples thereof include, but are not limited to, a vinyl group, a 1-propenyl group, an isopropenyl group, a 1-butenyl group, a 2-butenyl group, a 3-butenyl group, a 1-pentenyl group, a 2-pentenyl group, a 3-pentenyl group, a 3-methyl-1-butenyl group, a 1,3-butadienyl group, an allyl group, a 1-phenylvinyl-1-yl group, a 2-phenylvinyl-1-yl group, a 2,2-diphenylvinyl-1-yl group, a 2-phenyl-2-(naphthyl-1-yl)vinyl-1-yl group, a 2,2-bis(diphenyl-1-yl)vinyl-1-yl group, a stilbenyl group, and a styrenyl group. Specifically, the number of carbon atoms in the alkenyl group may be 2 to 30, and more specifically, 2 to 20.

[0024] In the present specification, the alkynyl group may be a straight or branched chain having 2 to 60 carbon atoms. Specifically, the alkynyl group may have 2 to 30 carbon atoms, and more specifically, 2 to 20 carbon atoms.

[0025] In the present specification, the alkoxy group may be a straight chain, branched chain or cyclic chain having 1 to 60 carbon atoms, and specific examples thereof include, but are not limited to, methoxy, ethoxy, n-propoxy, isopropoxy, i-propyloxy, n-butoxy, isobutoxy, tert-butoxy, sec-butoxy, n-pentyloxy, neopentyloxy, isopentyloxy, n-hexyloxy, 3,3-dimethylbutyloxy, 2-ethylbutyloxy, n-octyloxy, n-nonyloxy, n-decyloxy, benzyloxy, p-methylbenzyloxy, etc. Specifically, the alkoxy group may have 1 to 30 carbon atoms, and more specifically, 1 to 20 carbon atoms.

[0026] In the present specification, the cycloalkyl group may be monocyclic or polycyclic having 3 to 60 carbon atoms, and specific examples thereof include, but are not limited to, cyclopropyl, cyclobutyl, cyclopentyl, 3-methylcyclopentyl, 2,3-dimethylcyclopentyl, cyclohexyl, 3-methylcyclohexyl, 4-methylcyclohexyl, 2,3-dimethylcyclohexyl, 3,4,5-trimethylcyclohexyl, 4-tert-butylcyclohexyl, cycloheptyl, and cyclooctyl. Specifically, the cycloalkyl group may have 3 to 30 carbon atoms, and more specifically, 3 to 20 carbon atoms.

[0027] In the present specification, a heterocycloalkyl group is a group that contains at least one non-carbon atom, i.e., a heteroatom, and specifically, may be a cycloalkyl group that contains at least one heteroatom selected from the group consisting of O, N, S, Se, etc., and may be a monocyclic or polycyclic group having 2 to 60 carbon atoms. Specifically, the heterocycloalkyl group may have 2 to 30 carbon atoms, and more specifically, may have 2 to 20 carbon atoms.

[0028] In the present specification, a sulfide group includes S and may have 1 to 60 carbon atoms. Specific examples include, but are not limited to, an alkyl sulfide group such as a dimethyl sulfide group, an aryl sulfide group such as diphenyl sulfide, and a heteroaryl sulfide group substituted with a heteroaryl group. Specifically, the sulfide group may have 1 to 30 carbon atoms, and more specifically, 1 to 20 carbon atoms.

[0029] In the present specification, the aryloxy group may be a substituent that contains O, and the O atom may be directly connected as a radical, and may have 6 to 60 carbon atoms. Specific examples include phenoxy groups, naphthoxy groups, biphenoxy groups, etc., which are oxy groups substituted with aryl groups, but are not limited thereto. The heteroaryloxy group is an oxy group substituted with heteroaryl groups, and may have 2 to 60 carbon atoms. Specifically, the aryloxy group may have 6 to 30 carbon atoms, and more specifically, may have 6 to 20 carbon atoms.

[0030] In the present specification, the thio group includes S and may have 1 to 60 carbon atoms. Specific examples include, but are not limited to, alkylthio groups such as methylthio, ethylthio, butylthio, pentylthio, and hexylthio, arylthio groups such as phenylthio, and naphthylthio, and heteroarylthio groups substituted with heteroaryl groups. Specifically, the thio group may have 1 to 30 carbon atoms, and more specifically, 1 to 20 carbon atoms.

[0031] In the present specification, the silyl group may be a substituent containing Si, and the Si atom may be directly connected as a radical, and may have 1 to 60 carbon atoms. Specific examples thereof include, but are not limited to, alkylsilyl groups such as trimethylsilyl, triethylsilyl, t-butyldimethylsilyl, vinyldimethylsilyl, and propyldimethylsilyl groups, arylsilyl groups such as triphenylsilyl, diphenylsilyl, and phenylsilyl groups, and heteroarylsilyl groups substituted with heteroaryl groups. Specifically, the silyl group may have 1 to 30 carbon atoms, and more specifically, 1 to 20 carbon atoms.

[0032] In the present specification, the phosphine oxide group includes P=O and may have 1 to 60 carbon atoms. Specific examples include, but are not limited to, an alkylphosphine oxide group such as a dimethylphosphine oxide group, an arylphosphine oxide group such as a diphenylphosphine oxide group and a dinaphthylphosphine oxide group, and a heteroarylphosphine oxide group substituted with a heteroaryl group. Specifically, the phosphine oxide group may have 1 to 30 carbon atoms, and more specifically, 1 to 20 carbon atoms.

[0033] In the present specification, the aryl group may be monocyclic or polycyclic and have 6 to 60 carbon atoms. In the case of a monocyclic aryl group, specific examples thereof include a phenyl group, a biphenyl group, a terphenyl group, etc., but are not limited thereto. In the case of a polycyclic aryl group, specific examples thereof include a naphthyl group, anthracenyl group, a phenanthrenyl group, a triphenylenyl group, a pyrenyl group, a fluorenyl group, etc., but are not limited thereto. Specifically, the aryl group may have 6 to 50 carbon atoms, and more specifically, 6 to 30 carbon atoms.

[0034] In the present specification, a heteroaryl group includes at least one non-carbon atom, i.e., a heteroatom, and may specifically include at least one heteroatom selected from the group consisting of O, N, S, and Se, and may be a monocyclic or polycyclic group having 2 to 60 carbon atoms. Specific examples include a thiophenyl group, a furanyl group, a pyrrolyl group, an imidazolyl group, a thiazolyl group, an oxazolyl group, an oxadiazolyl group, a pyridinyl group, a bipyridinyl group, a pyrimidinyl group, a pyrimidinyl group, a pyrazinyl group, a quinolinyl group, a quinazolyl group, a quinoxalinyl group, a phthalazinyl group, a pyridopyrimidinyl group, a pyridopyrazinyl group, a pyrazinopyrazinyl group, a pyridoindolyl group, a benzothienopyrimidyl group, an indenocarbazolyl group, an isoquinolinyl group, an indolyl group, a carbazolyl group, a benzoxazolyl group, a benzimidazolyl group, a benzothiazolyl group, a benzocarbazolyl group, a benzothiophenyl group, Examples thereof include, but are not limited to, a dibenzothiophenyl group, a benzofuranyl group, a phenanthridinyl group, a phenanthrolinyl group, an isoxazolyl group, a thiadiazolyl group, a phenothiazinyl group, and a dibenzofuranyl group. Specifically, the heteroaryl group may have 2 to 50 carbon atoms, and more specifically, 2 to 30 carbon atoms.

[0035] In the present specification, the amine group may be selected from the group consisting of -NH2, an alkylamine group, an N-alkylarylamine group, an arylamine group, an N-arylheteroarylamine group, an N-alkylheteroarylamine group, and a heteroarylamine group.

[0036] In this specification, an arylene group refers to a divalent aryl group having two bonding positions to an aryl group, and a heteroarylene group also refers to a divalent heteroaryl group having two bonding positions to a heteroaryl group. The descriptions of the aryl group and heteroaryl group described above can be applied to these groups, except that they are each divalent groups.

[0037] In the chemical formula or structural formula in this specification, * or indicates the binding position.

[0038] In this specification, diazaspirobifluorene means a structure in which nitrogen (N) is substituted at two carbon positions of spirobifluorene, and 4,5-diazaspirobifluorene means a structure in which nitrogen (N) is substituted at the carbon positions at positions 4 and 5 based on the spirobifluorene diagram shown below.

[0039]

[0040] The present invention will be described in detail below.

[0041] The novel compound according to the present invention is represented by the following chemical formula 1, and is characterized in that it is applied to a charge generation layer, particularly an N-type charge generation layer, of a tandem organic light-emitting device including two or more light-emitting layers.

[0042]

[0043] In the above chemical formula 1,

[0044] L1 and L2 are each independently a direct bond, a substituted or unsubstituted arylene group, or a substituted or unsubstituted heteroarylene group,

[0045] Ar1 and Ar2 are each independently selected from the group consisting of deuterium, halogen, cyano group, nitro group, nitrile group, substituted or unsubstituted alkyl group, substituted or unsubstituted alkenyl group, substituted or unsubstituted alkynyl group, substituted or unsubstituted cycloalkyl group, substituted or unsubstituted heterocycloalkyl group, substituted or unsubstituted alkoxy group, substituted or unsubstituted sulfide group, substituted or unsubstituted aryl group, substituted or unsubstituted heteroaryl group, substituted or unsubstituted aryloxy group, substituted or unsubstituted heteroaryloxy group, substituted or unsubstituted thio group, substituted or unsubstituted amine group, substituted or unsubstituted silyl group, and substituted or unsubstituted phosphine oxide group,

[0046] m and n are each independently integers from 1 to 3.

[0047] The compound of the present invention is characterized by a structure in which 4,5-diazaspirobifluorene is used as a core, and at least one substituent is bonded to each of the two pyridine rings below.

[0048] The above L1 and L2 may specifically be a direct bond, a substituted or unsubstituted C6~C30 arylene group, or a substituted or unsubstituted C2~C30 heteroarylene group, and more specifically may be a direct bond, a substituted or unsubstituted C6~C20 arylene group, or a substituted or unsubstituted C2~20 heteroarylene group. L1 and L2 may be the same as or different from each other, and L1 groups or L2 groups may also be the same as or different from each other.

[0049] The above Ar1 and Ar2 may specifically be a substituted or unsubstituted C1~C30 alkyl group, a substituted or unsubstituted C3~C30 cycloalkyl group, a substituted or unsubstituted C2~C30 heterocycloalkyl group, a substituted or unsubstituted C6~C30 aryl group, or a substituted or unsubstituted C2~C30 heteroaryl group, and more specifically, may be a substituted or unsubstituted C6~C30 aryl group, or a substituted or unsubstituted C2~C30 heteroaryl group. Even more specifically, may be a substituted or unsubstituted C6~C20 aryl group, or a substituted or unsubstituted C2~C20 heteroaryl group. Ar1 and Ar2 may be the same as or different from each other, and Ar1 and Ar2 may also be the same as or different from each other.

[0050] The substituents that can be substituted for the above Ar1, Ar2, L1 and L2 may be at least one selected from among deuterium, a halogen group, a cyano group, a nitro group, a nitrile group, a C1~C20 alkyl group, a C3~C20 cycloalkyl group, a C6~C20 aryl group, a C6~C20 aryl group substituted with deuterium, a C6~C20 fused ring group in which an aryl group and a cycloalkyl group are fused, a C2~C20 heteroaryl group and a C2~C20 heteroaryl group substituted with deuterium, and more specifically, a deuterium, a halogen group, a cyano group, a nitro group, a nitrile group, a C1~C10 alkyl group, a C3~C10 cycloalkyl group, a C6~C10 aryl group, a C6~C10 aryl group substituted with deuterium, and a C6~C10 aryl group in which an aryl group and a cycloalkyl group are fused. It may be at least one selected from a C6~C10 fused ring group, a C2~C10 heteroaryl group, and a C2~C10 heteroaryl group substituted with deuterium. According to one embodiment, examples thereof include, but are not particularly limited to, deuterium, a fluorine group (-F), a cyano group (-CN), a methyl group, an ethyl group, a t-butyl group, an adamantyl group, a phenyl group, a phenyl group substituted with deuterium, a biphenyl group, a naphthyl group, a deuterium-substituted naphthyl group, a pyridine group, a pyrimidine group, a quinoline group, an isoquinoline group, a dibenzofuran group, a dibenzothiophene group, a benzoxazole group, or a benzothiazole group.

[0051] As used herein, including the above, the term "fused ring group" includes a fused ring group in which an aryl group and a cycloalkyl group are fused, a fused ring group in which a heteroaryl group and a cycloalkyl group are fused, a fused ring group in which an aryl group and a heterocycloalkyl group are fused, or a fused ring group in which a heteroaryl group and a heterocycloalkyl group are fused. In one embodiment, the tetralin group represented by the structural formula below corresponds to one of the fused ring groups in which an aryl group and a cycloalkyl group are fused.

[0052]

[0053] The above m and n can be specifically 1 or 2, and more specifically both m and n can be 1.

[0054] According to the above, chemical formula 1 can be represented by chemical formula 2 below. That is, both m and n can be 1.

[0055]

[0056] In the above chemical formula 2, L1, L2, Ar1 and Ar2 may be the same as defined in the above chemical formula 1.

[0057] According to one embodiment of the present invention, the substituents *-L1-Ar1 and *-L2-Ar2 bonded to the pyridine rings on both sides may have different structures. That is, the compound of the present invention may have an asymmetric structure centered on the 4,5-diazaspirobifluorene core (based on the symmetry axis X in the chemical formula below).

[0058]

[0059] Specifically, the substituent bonded to either of the pyridine rings may be fixed as a substituted or unsubstituted phenyl group or a substituted or unsubstituted naphthyl group. More specifically, *-L2-Ar2 may be a substituted or unsubstituted phenyl group or a substituted or unsubstituted naphthyl group. In this case, the substituent that may be substituted on the phenyl group or naphthyl group may include one or more deuterium or phenyl groups. More specifically, *-L2-Ar2 may be a substituted or unsubstituted phenyl group.

[0060] According to the above, chemical formula 2 can be represented by the following chemical formula 3.

[0061]

[0062] In the above chemical formula 3, L1 and Ar1 have the same definitions as in the above chemical formula 1, R is each independently deuterium or a phenyl group, and o can be an integer from 0 to 5. Specifically, R can be a phenyl group, and o can be 0 or 1.

[0063] According to one embodiment of the present invention, chemical formula 3 may be represented by the following chemical formula 4. That is, in chemical formula 3, o is 0, and the position of the phenyl group may be the position right next to nitrogen (N) (number 3).

[0064]

[0065] In the above chemical formula 4, L1 and Ar1 may be the same as defined in the above chemical formula 1.

[0066] More specifically, chemical formula 4 can be represented by chemical formula 5 below. That is, the bonding position of the substituent bonded to the other pyridine ring can also be the position right next to nitrogen (N) (position 6).

[0067]

[0068] In the above chemical formula 5, L1 and Ar1 may be the same as defined in the above chemical formula 1.

[0069] According to one embodiment of the present invention, the Ar1 is a phenyl group, a naphthyl group, an anthracene group, a phenanthrene group, a pyrene group, a benzophenanthrene group, a benzoanthracene group, a chrysene group, a triphenylene group, a spirobifluorene group, a fluoranthene group, a dimethylfluorene group, a diphenylfluorene group, a dibenzofuran group, a dibenzothiophene group, a benzofuropyridine group, a benzothienopyridine group, a benzofuropyrimidine group, a benzothienopyrimidine group, a furodipyridine group, a thienodipyridine group, a benzoxazole group, a benzothiazole group, a naphthooxazole group, a naphthothiazole group, a phenanthrooxazole group, a phenanthrothiazole group, a benznaphthooxazole group, a benznaphthothiazole group, a carbazole group, which is substituted or unsubstituted with one or more substituents that are the same or different. It may be any one of a carboline group, a diazacabazole group, a benzocarbazole group, a benzoimidazole group, a naphthoimidazole group, a pyridine group, a pyrimidine group, a pyridazine group, a pyrazine group, a triazine group, a quinoline group, an isoquinoline group, a quinazoline group, a quinoxaline group, a phthalazine group, a cinnoline group, a 1,5-naphthyridine group, a 1,6-naphthyridine group, a 1,7-naphthyridine group, a 1,8-naphthyridine group, a 2,7-naphthyridine group, a benzoquinoline group, a benzoquinazoline group, a 1,4-phenanthroline group, a 1,10-phenanthroline group, or a triphenylsilane group.

[0070] Substituents that can be substituted for Ar1 include deuterium, a halogen group, a cyano group, a C1 to C10 alkyl group, a C6 to C10 aryl group, or a C2 to C10 heteroaryl group, and in one embodiment, deuterium, a fluorine group (-F), a cyano group (-CN), a methyl group, an ethyl group, a t-butyl group, a phenyl group, a biphenyl group, a naphthyl group, a pyridine group, a pyrimidine group, a quinoline group, an isoquinoline group, a dibenzofuran group, a dibenzothiophene group, a benzoxazole group, or a benzothiazole group, but are not limited thereto.

[0071] According to one embodiment of the present invention, both L1 and Ar1 may not contain heteroatoms such as N, O, and S. Accordingly, L1 may be a direct bond or an arylene group unsubstituted or substituted with one or more substituents selected from deuterium, an alkyl group, and an aryl group. And Ar1 may be an aryl group unsubstituted or substituted with one or more substituents selected from deuterium, an alkyl group, and an aryl group. According to one embodiment, among the substituents, the alkyl group may include a methyl group, an ethyl group, a t-butyl group, etc., and the aryl group may include a phenyl group, a naphthyl group, etc., but the types of the substituents are not particularly limited thereto.

[0072] Specifically, Ar1 may be a fused aryl group having a carbon number of C10 or higher. Here, the fused aryl group refers to an aryl group in which two or more hydrocarbon rings, which are the same or different, are fused.

[0073] More specifically, Ar1 may be one of a naphthyl group, a phenanthrene group, a pyrene group, a benzophenanthrene group, a benzoanthracene group, a chrysene group, a triphenylene group, a spirobifluorene group, and a fluoranthene group, and even more specifically, may be a condensed aryl group having more than C10 in which three or more hydrocarbon rings, which are the same or different, are condensed, such as a phenanthrene group, a pyrene group, a benzophenanthrene group, a benzoanthracene group, a chrysene group, a triphenylene group, a spirobifluorene group, or a fluoranthene group.

[0074] According to one embodiment of the present invention, the L1 may be a direct bond, or may be formed by combining two or more of the structural formulae L-1 to L-30 below. Here, the meaning of formed by combining two or more means a combination of two or more of the same or different structural formulae, and in one embodiment, the case where three structural formulae L-1 are combined, the case where structural formulae L-1 and L-2 are combined, the case where two structural formulae L-1 and one structural formula L-2 are combined, etc. may be included. In this case, the order of combination is not particularly determined, and combinations in all possible cases are possible.

[0075]

[0076] More specifically, L1 may be a direct bond, or a substituted or unsubstituted phenylene, or a substituted or unsubstituted naphthylene, and when substituted, the substituent may be a phenyl group, a pyridine group, or a pyrimidine group. Even more specifically, L1 may be a direct bond, or one of phenylene and naphthylene, or a combination of two or more. According to one embodiment, L1 may be one of the following structural formulas, or a combination of two or more.

[0077]

[0078] According to one embodiment of the present invention, the compound represented by the chemical formula 1 may be selected from compounds 1 to 228 below.

[0079]

[0080]

[0081]

[0082]

[0083]

[0084]

[0085]

[0086]

[0087]

[0088] The 4,5-diazaspirobifluorene core, which is the core of the present invention, introduces SP3 hybrid orbital carbon into the phenanthroline core, which is widely used as a host material for existing N-type charge generation layers, thereby preventing an increase in conjugation length, thereby reducing electron absorption and improving electron mobility, resulting in an increase in device efficiency and a decrease in operating voltage, and thus having characteristics more suitable for N-type charge generation layers.

[0089] The N-type charge generation layer containing the novel compound according to the present invention as a host has the effect of increasing electron injection into the electron transport layer by facilitating electron injection more smoothly, thereby achieving a balance with the large amount of holes injected from the cathode.

[0090] Additionally, it has the effect of lowering the driving voltage of the device by lowering the energy barrier felt by electrons.

[0091] In addition, it is possible to implement an organic light-emitting device with excellent luminous efficiency and a lower operating voltage by maximizing the tunneling effect in the junction region of electrons and holes, thereby improving the efficiency of the light-emitting layer.

[0092] In addition, since smooth interaction with dopants such as alkali metals, alkali metal compounds, alkaline earth metals, or alkaline earth metal compounds is possible, charge generation and mobility can be further improved, and the diffusion of dopants from the N-type charge generation layer to other layers such as the P-type charge generation layer can be effectively prevented, thereby solving problems such as a decrease in lifespan due to diffused dopants. Here, interaction with a dopant may mean bonding with a dopant, and the compound of the present invention is effective in improving the lifespan of a device by bonding with a dopant to form a stable and smooth gap state.

[0093] Meanwhile, the present invention further includes a tandem organic light-emitting element, and further includes a tandem organic light-emitting element that can be included in a display device applied to various electronic devices such as mobile communication terminals such as mobile phones, PDAs, electronic dictionaries, PMPs, remote controls, navigation systems, game consoles, various TVs, and various computers.

[0094] Hereinafter, the tandem organic light-emitting device according to the present invention will be described in more detail.

[0095] The present invention includes a tandem organic light-emitting device comprising a first electrode, a second electrode, a plurality of light-emitting units positioned between the first electrode and the second electrode, and a charge generation layer positioned at at least one position between two adjacent light-emitting units, wherein at least one of the charge generation layers comprises the compound according to the present invention described above. Specifically, the N-type charge generation layer comprises the compound according to the present invention.

[0096] According to one embodiment, a plurality of light-emitting units means two or more light-emitting units. When there are two light-emitting units, there is one charge generation layer. When there are three light-emitting units, there are two charge generation layers. When there are four light-emitting units, there are three charge generation layers. That is, when the number of light-emitting units is n, the number of charge generation layers is n-1 (n is 2 or greater), and at least one of the n-1 charge generation layers may include the compound according to the present invention.

[0097] FIG. 1 is a schematic diagram showing an organic light-emitting device according to one embodiment of the present invention, and specifically, a schematic diagram showing a tandem organic light-emitting device having two light-emitting parts.

[0098] As illustrated in FIG. 1, an organic light-emitting device (1000) according to an embodiment of the present invention may be configured to include a first electrode (100), a second electrode (200), and an organic layer (300) positioned between the first electrode and the second electrode.

[0099] According to one embodiment, the first electrode (100) may be an anode electrode and the second electrode (200) may be a cathode electrode, or vice versa. Also, according to one embodiment, the first electrode (100) may be a transparent electrode and the second electrode (200) may be a reflective electrode, or vice versa.

[0100] The organic layer (300) is a layer positioned between the first electrode (100) and the second electrode (200) and includes one or more organic layers, and may be composed of two or more layers.

[0101] Specifically, the organic layer (300) may be configured to include a first light-emitting portion (310), a second light-emitting portion (320), and a charge generation layer (330) positioned between the first light-emitting portion (310) and the second light-emitting portion (320).

[0102] The first light-emitting portion (310) includes a first light-emitting layer (311). According to one embodiment, the first light-emitting layer (311) may include a host material and a dopant material.

[0103] In addition, the first light-emitting portion (310) may additionally include a first hole transport region (312) that transports holes to the first light-emitting layer (311) and a second electron transport region (313) that transports electrons to the first light-emitting layer (311).

[0104] The above first hole transport region (312) may be configured to include at least one of a hole injection layer, a hole transport layer, a hole functional layer, and an electron blocking layer. Here, the hole functional layer refers to a layer that simultaneously injects and transports holes. In addition, one or more auxiliary layers may be additionally included.

[0105] The above first electron transport region (313) may be configured to include one or more of an electron injection layer, an electron transport layer, an electron functional layer, and a hole blocking layer. Here, the electron functional layer refers to a layer that simultaneously injects and transports electrons. In addition, one or more auxiliary layers may be additionally included.

[0106] Meanwhile, the second light-emitting portion (320) also includes a second light-emitting layer (321) like the first light-emitting portion (310). According to one embodiment, the second light-emitting layer (321) may include a host material and a dopant material.

[0107] This second light-emitting portion (320) may also additionally include a second hole transport region (322) that transports holes to the second light-emitting layer (321) and a second electron transport region (323) that transports electrons to the second light-emitting layer (321).

[0108] The second hole transport region (322) may be configured to include at least one of a hole injection layer, a hole transport layer, a hole functional layer, and an electron blocking layer. The hole functional layer is omitted as it is the same as described above.

[0109] The second electron transport region (323) may be configured to include at least one of an electron injection layer, an electron transport layer, an electron functional layer, and a hole blocking layer. The electron functional layer is the same as described above and is therefore omitted.

[0110] Of course, both the second hole transport region (322) and the second electron transport region (323) may additionally include one or more auxiliary layers in addition to the aforementioned layers.

[0111] The tandem organic light-emitting device according to the present invention has a first light-emitting part (310) and a second light-emitting part (320) configured as described above, so that holes and electrons transferred from the first electrode (100) and the second electrode (200) meet in the first light-emitting layer (311) and the second light-emitting layer (321) to emit light.

[0112] Meanwhile, the charge generation layer (330) is positioned between two adjacent light-emitting parts (310, 320) and serves to increase the current efficiency of the light-emitting layer by smoothly distributing charges. Specifically, the charge generation layer (330) may be configured to include a P-type charge generation layer and an N-type charge generation layer to smoothly distribute charges. When the first electrode (100) is an anode electrode and the second electrode (200) is a cathode electrode, the layer (331) positioned close to the anode electrode becomes an N-type charge generation layer, and the layer (332) positioned close to the cathode electrode becomes a P-type charge generation layer.

[0113] Such an N-type charge generation layer and a P-type charge generation layer may be laminated in direct contact as shown in FIG. 1, or may be laminated with one or more layers between the N-type charge generation layer and the P-type charge generation layer. That is, although not shown in FIG. 1, the charge generation layer (330) may further include one or more layers positioned between the two layers (331, 332). According to one embodiment, a layer including a metal may be positioned between the N-type charge generation layer and the P-type charge generation layer.

[0114] Meanwhile, FIG. 1 illustrates a tandem organic light-emitting device having two light-emitting parts, but the embodiments of the present invention are not limited to a tandem organic light-emitting device including two light-emitting parts, and it is natural that a tandem organic light-emitting device including three, four, five or more light-emitting parts is also included in the embodiments of the present invention.

[0115] According to one embodiment, when the organic light-emitting device of the present invention includes three light-emitting parts, which are referred to as a first light-emitting part, a second light-emitting part, and a third light-emitting part, the charge generation layer may include a first charge generation layer positioned between the first light-emitting part and the second light-emitting part, and a second charge generation layer positioned between the second light-emitting part and the third light-emitting part. In addition, the first charge generation layer and the second charge generation layer may include an N-type charge generation layer and a P-type charge generation layer, respectively.

[0116] According to an embodiment, two or more light-emitting units or two or more charge-generation layers may be configured with the same structure or different structures. In addition, they may be configured with the same material or different materials. According to an embodiment, when a tandem organic light-emitting device includes three light-emitting layers and two charge-generation layers, the three light-emitting layers may be the same or different in structure or material, and the two charge-generation layers may also be the same or different in structure or material.

[0117] Meanwhile, the N-type charge generation layer may further include a dopant of one or more of a metal, a metal compound, and an organic complex of a metal, together with the compound of the present invention acting as a host. According to one embodiment, the metal compound may include, but is not limited to, a metal oxide, a metal fluoride, and the like. Specifically, the N-type charge generation layer may further include one or more of an alkali metal, an alkaline earth metal, an alkali metal compound, an alkaline earth metal compound, an organic complex of an alkali metal, and an organic complex of an alkaline earth metal. According to one embodiment, the composition may further include one or more metals, metal compounds and organic complexes of metals selected from lithium (Li), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), ytterbium (Yb), samarium (Sm), tin (Sn), copper (Cu), titanium (Ti), cadmium (Cd), mercury (Hg), lead (Pb), bismuth (Bi), zinc (Zn), iron (Fe), cobalt (Co), nickel (Ni), indium (In), gallium (Ga), thorium (Th), uranium (U), silver (Ag), aluminum (Al), gold (Au), molybdenum (Mo), niobium (Nb), palladium (Pd), platinum (Pt) and europium (Eu). In one embodiment, the metal may be selected from lithium or ytterbium.

[0118] Such metal, metal compound or organic complex of metal may be included in the form of doping in the compound represented by Chemical Formula 1, may be included in the form of a layer, or may be included in both the form of doping and the form of a layer. When included in the form of doping, it may be doped in an amount of 0.1 to 20 wt% based on the compound according to Chemical Formula 1, specifically, may be doped in an amount of 0.5 to 15 wt%, and this may vary depending on the type of metal. In one embodiment, in the case of lithium, the doping amount may be 0.5 to 5 wt%, and in the case of ytterbium, the doping amount may be 5 to 5 wt%. Meanwhile, when included in the form of a layer, it may be located between the layer made of the compound represented by Chemical Formula 1 and the P-type charge generation layer.

[0119] Meanwhile, although not illustrated in FIG. 1, the tandem organic light-emitting device of the present invention may additionally include a capping layer (also referred to as a light efficiency improvement layer) formed on the outer side of at least one of the first electrode (100) and the second electrode (200). Here, the outer side of the electrode means the outer side, not between the two electrodes, when the place where the organic layer exists between the two electrodes is referred to as the inner side of the electrode. According to one embodiment, it may mean the upper side of the second electrode (200) based on FIG. 1.

[0120] Meanwhile, in the tandem organic light-emitting device of the present invention, the first electrode, the second electrode, the light-emitting layer, the hole injection layer, the hole transport layer, the hole functional layer, the electron blocking layer, the electron injection layer, the electron transport layer, the electron functional layer, the hole blocking layer, the P-type charge generation layer, and other auxiliary layers or capping layers are not particularly limited unless otherwise specified, and those known in the art can be used according to the role of each layer.

[0121] Meanwhile, the P-type charge generation layer according to one embodiment of the present invention may further include a compound having one or more cyano groups (-CN) substituted. More specifically, the P-type charge generation layer may include a compound having four or more cyano groups (-CN), and even more specifically, a compound having four to eight cyano groups (-CN).

[0122] More specifically, the compound included in the P-type charge generation layer has a structure in which a core composed of at least one of a C6~C30 aryl group, a C3~C30 cycloalkyl group, a C3~C30 cycloalkenyl group, and a C2~C30 heteroaryl group is substituted with at least one substituent, which is the same or different, wherein the substituent is hydrogen; a halogen group; -F; -Cl; -CF3; -CN; -NC; -NO2; -OCF3; -SCN; -OCN; -SF5; -OC(CH3)3; a C1~C12 alkyl group substituted with at least one of hydrogen, a halogen group, -F, -Cl, -CF3, -CN, -NC, -NO2, -OCF3, -SCN, -OCN, -SF5, and -OC(CH3)3; A C1~C12 alkoxy group substituted with one or more of hydrogen, a halogen group, -F, -Cl, -CF3, -CN, -NC, -NO2, -OCF3, -SCN, -OCN, -SF5, and -OC(CH3)3; A C6~C12 aryl group substituted with one or more of hydrogen, a halogen group, -F, -Cl, -CF3, -CN, -NC, -NO2, -OCF3, -SCN, -OCN, -SF5, and -OC(CH3)3; and a C2~C12 heteroaryl group substituted with one or more of hydrogen, a halogen group, -F, -Cl, -CF3, -CN, -NC, -NO2, -OCF3, -SCN, -OCN, -SF5, and -OC(CH3)3; provided that the compound contains four or more cyano groups (-CN).

[0123] According to one embodiment of the present invention, a compound included in the P-type charge generation layer may be represented by one of the following chemical formulas 19 to 27.

[0124]

[0125] In the above chemical formulas 19 to 27, R is each independently hydrogen; a halogen group; -F; -Cl; -CF3; -CN; -NC; -NO2; -OCF3; -SCN; -OCN; -SF5; -OC(CH3)3; a C1 to C10 alkyl group substituted with one or more of hydrogen, a halogen group, -F, -Cl, -CF3, -CN, -NC, -NO2, -OCF3, -SCN, -OCN, -SF5, and -OC(CH3)3; a C1 to C10 alkoxy group substituted with one or more of hydrogen, a halogen group, -F, -Cl, -CF3, -CN, -NC, -NO2, -OCF3, -SCN, -OCN, -SF5, and -OC(CH3)3; A C6~C10 aryl group substituted with one or more of hydrogen, a halogen group, -F, -Cl, -CF3, -CN, -NC, -NO2, -OCF3, -SCN, -OCN, -SF5 and -OC(CH3)3; and a C2~C10 heteroaryl group substituted with one or more of hydrogen, a halogen group, -F, -Cl, -CF3, -CN, -NC, -NO2, -OCF3, -SCN, -OCN, -SF5 and -OC(CH3)3; wherein each chemical formula contains four or more -CN. Naturally, R in each chemical formula may be the same or different.

[0126] According to one embodiment of the present invention, the compound included in the P-type charge generation layer may be selected from among compounds 6-1 to 6-36 below, but is not limited thereto.

[0127]

[0128]

[0129]

[0130] The P-type charge generation layer according to one embodiment of the present invention may further include a hole transport material having one or more tertiary amines as a core, together with the aforementioned compound. In this case, the hole transport material may be one known in the art that includes a tertiary amine.

[0131] The novel charge generation layer of the tandem organic light-emitting device according to the present invention applies a novel compound having 4,5-diazaspirobifluorene as a core to the N-type charge generation layer, and applies a compound containing one or more cyano groups (-CN) to the P-type charge generation layer. The combination of the two facilitates charge transport and prevents current leakage to the side, thereby lowering the driving voltage of the device and improving efficiency and lifespan.

[0132] Hereinafter, the present invention will be described in more detail with synthetic examples, experimental examples, and practical examples. However, the following contents do not limit the scope of the present invention.

[0133] Synthetic example

[0134] Synthesis of 2-bromo-8-phenylspiro[cyclopenta[2,1-b:3,4-b']dipyridine-5,9'-fluorene]

[0135]

[0136] In a round-bottomed flask, completely dissolve 2-iodo-1,1'-biphenyl (20 g, 71.4 mmol) in 100 mL of THF, cool to -78°C, and stir. Slowly add n-BuLi (1.6 M in hexane, 41.9 mL). Once the addition is complete, stir at -78°C for 2 hours. To this, dissolve 2-bromo-8-phenyl-5H-cyclopenta[2,1-b:3,4-b']dipyridin-5-one (17.3 g, 85.7 mmol) in 50 mL of THF and add dropwise to the reaction solution. Once the addition is complete, raise the temperature to room temperature and stir for 1 hour. When the reaction is complete, add water, stir, and extract using dichloromethane. Dry the organic layer with MgSO4 and concentrate under reduced pressure. Add 100 mL of acetic acid and stir under reflux for 2 hours. After cooling to room temperature, filter. The solid was purified by column chromatography to obtain the target compound (20.5 g, 71%).

[0137] Synthetic Example 1: Synthesis of Compound 11

[0138]

[0139] In a round-bottomed flask, add 2-bromo-8-phenylspiro[cyclopenta[2,1-b:3,4-b']dipyridine-5,9'-fluorene](10.0 g, 21.1 mmol), 4,4,5,5-tetramethyl-2-(4-(phenanthren-9-yl)phenyl)-1,3,2-dioxaborolane (8.8 g, 23.2 mmol), and tetrakis(triphenylphophine)palladium (1.2 g, 1.1 mmol) to 80 mL of THF and stir. Then, add potassium carbonate (8.8 g, 63.4 mmol) dissolved in 80 mL of H2O and stir under reflux for 8 hours. When the reaction is complete, raise the temperature to room temperature and concentrate under reduced pressure to obtain a filtrate. Extract the obtained filtrate using dichloromethane and water. The organic layer was dehydrated with MgSO4, concentrated under reduced pressure, and the resulting filtrate was purified by column chromatography to obtain compound 11 (11.5 g, 84%).

[0140] Synthesis Example 2: Synthesis of Compound 33

[0141]

[0142] Compound 33 (11.5 g, 81%) was obtained in the same manner as in Synthesis Example 1, except that 4,4,5,5-tetramethyl-2-(4-(pyren-1-yl)phenyl)-1,3,2-dioxaborolane (16.8 g, 23.2 mmol) was used instead of 4,4,5,5-tetramethyl-2-(4-(phenanthren-9-yl)phenyl)-1,3,2-dioxaborolane.

[0143] Synthetic Example 3: Synthesis of Compound 76

[0144]

[0145] Compound 76 (10.3 g, 77%) was obtained by proceeding in the same manner as in Synthesis Example 1, except that 9-(4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phenyl)-9H-pyrido[2,3-b]indole (18.1 g, 23.2 mmol) was used instead of 4,4,5,5-tetramethyl-2-(4-(phenanthren-9-yl)phenyl)-1,3,2-dioxaborolane.

[0146] Synthetic Example 4: Synthesis of Compound 87

[0147]

[0148] Compound 87 (12.3 g, 83%) was obtained in the same manner as in Synthesis Example 1, except that 2,4-diphenyl-6-(3-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phenyl)pyrimidine (18.1 g, 23.2 mmol) was used instead of 4,4,5,5-tetramethyl-2-(4-(phenanthren-9-yl)phenyl)-1,3,2-dioxaborolane.

[0149] Synthetic Example 5: Synthesis of Compound 103

[0150]

[0151] Compound 103 (10.8 g, 79%) was obtained by proceeding in the same manner as in Synthesis Example 1, except that 2-(4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phenyl)-1,10-phenanthroline (18.1 g, 23.2 mmol) was used instead of 4,4,5,5-tetramethyl-2-(4-(phenanthren-9-yl)phenyl)-1,3,2-dioxaborolane.

[0152] Synthetic Example 6: Synthesis of Compound 127

[0153]

[0154] Compound 127 (10.6 g, 72%) was obtained in the same manner as in Synthesis Example 1, except that 7-bromo-2-phenylspiro[cyclopenta[2,1-b:3,4-b']dipyridine-5,9'-fluorene] was used instead of 2-bromo-8-phenylspiro[cyclopenta[2,1-b:3,4-b']dipyridine-5,9'-fluorene] and 4,4,5,5-tetramethyl-2-(4-(phenanthren-9-yl)phenyl)-1,3,2-dioxaborolane (18.1 g, 23.2 mmol) was used instead of 4,4,5,5-tetramethyl-2-(6-(phenanthren-9-yl)naphthalen-2-yl)-1,3,2-dioxaborolane.

[0155] Synthetic Example 7: Synthesis of Compound 215

[0156]

[0157] Compound 215 (11.3 g, 78%) was obtained in the same manner as in Synthesis Example 1, except that 2-bromo-7-phenylspiro[cyclopenta[2,1-b:3,4-b']dipyridine-5,9'-fluorene] was used instead of 2-bromo-8-phenylspio[cyclopenta[2,1-b:3,4-b']dipyridine-5,9'-fluorene] and 2-(4-(dibenzo[b,d]furan-3-yl)naphthalen-1-yl)-4,4,5,5-tetramethyl-1,3,2-dioxaborolane (18.1 g, 23.2 mmol) was used instead of 4,4,5,5-tetramethyl-2-(4-(phenanthren-9-yl)phenyl)-1,3,2-dioxaborolane.

[0158] Synthetic Example 8: Synthesis of Compound 225

[0159]

[0160] Compound 225 (11.4 g, 87%) was obtained in the same manner as in Synthesis Example 1, except that 2,8-dichlorospiro[cyclopenta[2,1-b:3,4-b']dipyridine-5,9'-fluorene] (8.2 g, 21.1 mmol) was used instead of 2-bromo-8-phenylspiro[cyclopenta[2,1-b:3,4-b']dipyridine-5,9'-fluorene] and 2-([1,1'-biphenyl]-4-yl)-4,4,5,5-tetramethyl-1,3,2-dioxaborolane (13 g, 46.4 mmol) was used instead of 4,4,5,5-tetramethyl-2-(4-(phenanthren-9-yl)phenyl)-1,3,2-dioxaborolane.

[0161] LC-MS m / z = 623 (M+H), Tg: 204

[0162] Fabrication of organic light-emitting devices

[0163] Comparative Example 1

[0164] After patterning the ITO substrate to be the anode so that the light-emitting area is 2 mm × 2 mm, it is cleaned with isopropyl alcohol and UV ozone, respectively. After that, the ITO substrate is mounted on the substrate holder of the vacuum deposition device and the vacuum level is 1 × 10 -7The pressure was set to 10 torr. Afterwards, plasma treatment was performed for 3 minutes under a N2 atmosphere. First, the HAT-CN compound was vacuum-deposited to form a first hole injection layer with a thickness of 5 nm. On top of this, the NPB material was vacuum-deposited to form a first hole transport layer with a thickness of 20 nm. Then, the GH-1 material was used as a host and the GD-1 material was used as a dopant and co-deposited to have a mass ratio of approximately 10% to form a green first light-emitting layer with a thickness of 20 nm. On this first light-emitting layer, the TmPyPb compound was vacuum-deposited to form a first electron transport layer with a thickness of 20 nm. Afterwards, the Li material as a dopant was co-deposited to the BPhen material as a host to have a mass ratio of 2% to form an N-type charge generation layer with a thickness of 10 nm. Afterwards, the HAT-CN compound was vacuum-deposited to form a P-type charge generation layer with a thickness of 5 nm. This layer was also used as a second hole injection layer. On this, NPB material was vacuum-deposited to form a second hole transport layer with a thickness of 50 nm. Thereafter, GH-1 material was used as a host and GD-1 material was used as a dopant to co-deposit at a mass ratio of approximately 10% to form a green second light-emitting layer with a thickness of 20 nm. On this light-emitting layer, TmPyPb compound was used as a host and Liq compound was used as a dopant to co-deposit at a mass ratio of approximately 33% to form a second electron transport layer with a thickness of 20 nm. Thereafter, LiF material was vacuum-deposited to form an electron injection layer with a thickness of 1 nm. Finally, aluminum (Al) was deposited at a thickness of 50 nm to form a cathode, thereby fabricating the final tandem organic light-emitting device. The structures of the HAT-CN, NPB, GH-1, GD-1, TmPyPb, BPhen, and Liq materials used previously are shown in Table 1, respectively.

[0165] [Table 1]

[0166]

[0167] Comparative Examples 2 and 3

[0168] An organic light-emitting device was manufactured in the same manner as in Comparative Example 1, except that Comparative Compounds 1 and 2 in Table 2 below were used instead of BPhen, which was used as the host material of the N-type charge generation layer.

[0169] [Table 2]

[0170]

[0171] Examples 1 to 8

[0172] An organic light-emitting device was manufactured in the same manner as in Comparative Example 1, except that the compounds synthesized in Synthesis Examples 1 to 8 were used instead of BPhen, which was used as the host material of the N-type charge generation layer.

[0173] Experimental Example: Evaluation of Organic Light-Emitting Diodes

[0174] The driving voltage, efficiency, and lifespan of the organic light-emitting devices manufactured in Comparative Examples 1 to 3 and Examples 1 to 8 were evaluated, respectively. The evaluation results are shown in Table 3 below.

[0175] [Table 3]

[0176]

[0177] As shown in Table 3 above, it was confirmed that the organic light-emitting devices of the examples had lower driving voltages and improved efficiency and lifespans compared to the comparative examples. In particular, it was confirmed that the lifespans of the examples using the compounds of the present invention using a 4,5-diazaspirobifluorene compound were significantly improved compared to comparative example 1 using a phenanthroline compound.

[0178] Meanwhile, Comparative Example 2 is a case where an azaspirobifluorene compound with one nitrogen (N) substituted, unlike the present invention, was used, and Comparative Example 3 is a case where a diazaspirobifluorene compound with two nitrogen (N) substituted at different positions from the present invention was used. In both cases, it was confirmed that lower device performance was shown than the compound of the phenanthroline core. This appears to be because the gap state was not formed due to failure to bond with lithium, which is a dopant, and therefore, it can be seen that it is not suitable as a compound for an N-type charge generation layer.

[0179] Meanwhile, it was confirmed that the operating voltage, efficiency, and lifespan of the examples using compounds having an asymmetric structure in which substituents were bonded to positions 3 and 6, which are positions right next to nitrogen (N) of the 4,5-diazaspirobifluorene core, and the substituent bonded to position 3 was fixed as a phenyl group around the 4,5-diazaspirobifluorene core, were all improved compared to the comparative examples.

Claims

1. A compound for a charge generation layer of a tandem organic light-emitting device represented by the following chemical formula 1; In the above chemical formula 1, L1 and L2 are each independently a direct bond, a substituted or unsubstituted arylene group, or a substituted or unsubstituted heteroarylene group, Ar1 and Ar2 are each independently selected from the group consisting of deuterium, halogen, cyano group, nitro group, nitrile group, substituted or unsubstituted alkyl group, substituted or unsubstituted alkenyl group, substituted or unsubstituted alkynyl group, substituted or unsubstituted cycloalkyl group, substituted or unsubstituted heterocycloalkyl group, substituted or unsubstituted alkoxy group, substituted or unsubstituted sulfide group, substituted or unsubstituted aryl group, substituted or unsubstituted heteroaryl group, substituted or unsubstituted aryloxy group, substituted or unsubstituted heteroaryloxy group, substituted or unsubstituted thio group, substituted or unsubstituted amine group, substituted or unsubstituted silyl group, and substituted or unsubstituted phosphine oxide group, m and n are each independently integers from 1 to 3.

2. In paragraph 1, The above chemical formula 1 is characterized by the following chemical formula 2, Compound for charge generation layer of tandem organic light emitting device; In the above chemical formula 2, L1, L2, Ar1 and Ar2 are the same as defined in the above chemical formula 1.

3. In paragraph 2, The above chemical formula 2 is characterized by the following chemical formula 3, Compound for charge generation layer of tandem organic light emitting device; In the above chemical formula 3, L1 and Ar1 are the same as defined in the above chemical formula 1, R is each independently a deuterium or phenyl group, o is an integer from 0 to 5.

4. In paragraph 3, The above chemical formula 3 is characterized by the following chemical formula 4, Compound for charge generation layer of tandem organic light emitting device; In the above chemical formula 4, L1 and Ar1 have the same definitions as in the above chemical formula 1.

5. In paragraph 1, The compound is a compound for a charge generation layer of a tandem organic light-emitting device, characterized in that the compound is asymmetrical around a 4,5-diazaspirobifluorene core.

6. In paragraph 1, The compound represented by the above chemical formula 1 is characterized in that it is one of the compounds 1 to 228 below. Compound for charge generation layer of tandem organic light emitting device; 7. First electrode and second electrode; A plurality of light-emitting parts positioned between the first electrode and the second electrode; and A charge generation layer is included, each of which is located at least one location between two adjacent light-emitting portions; At least one of the charge generation layers comprises a compound represented by the following chemical formula 1. Tandem organic light emitting diode; In the above chemical formula 1, L1 and L2 are each independently a direct bond, a substituted or unsubstituted arylene group, or a substituted or unsubstituted heteroarylene group, Ar1 and Ar2 are each independently selected from the group consisting of deuterium, halogen, cyano group, nitro group, nitrile group, substituted or unsubstituted alkyl group, substituted or unsubstituted alkenyl group, substituted or unsubstituted alkynyl group, substituted or unsubstituted cycloalkyl group, substituted or unsubstituted heterocycloalkyl group, substituted or unsubstituted alkoxy group, substituted or unsubstituted sulfide group, substituted or unsubstituted aryl group, substituted or unsubstituted heteroaryl group, substituted or unsubstituted aryloxy group, substituted or unsubstituted heteroaryloxy group, substituted or unsubstituted thio group, substituted or unsubstituted amine group, substituted or unsubstituted silyl group, and substituted or unsubstituted phosphine oxide group, m and n are each independently integers from 1 to 3.

8. In paragraph 7, A tandem organic light-emitting device, wherein the charge generation layer containing the above compound is an N-type charge generation layer.

9. In paragraph 8, A tandem organic light-emitting device, wherein the N-type charge generation layer further comprises at least one metal, metal compound, and organic complex of metal selected from lithium (Li), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), ytterbium (Yb), samarium (Sm), tin (Sn), copper (Cu), titanium (Ti), cadmium (Cd), mercury (Hg), lead (Pb), bismuth (Bi), zinc (Zn), iron (Fe), cobalt (Co), nickel (Ni), indium (In), gallium (Ga), thorium (Th), uranium (U), silver (Ag), aluminum (Al), gold (Au), molybdenum (Mo), niobium (Nb), palladium (Pd), platinum (Pt), and europium (Eu).

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