Phenanthrol-containing compounds, charge transport materials, and stacked organic electroluminescent devices

Abstract

The application discloses a phenanthroline-containing compound, a charge transport material and a laminated organic electroluminescent device, and belongs to the technical field of display. The chemical structural formula of the compound is shown in the following: one or two of Z1 to Z3 are N, and the rest are CH; R1 is C5-C30 pyridyl, C4-C30 pyrimidyl, C7-C30 quinolyl or C7-C30 isoquinolyl; Ar is hydrogen, deuterium, halogen, cyano, C1-C30 alkyl, C6-C30 aryl or C3-C30 heteroaryl; L, Ar1 and Ar2 are a single bond, C6-C30 arylene or C3-C30 heteroarylene; and R is hydrogen, deuterium, cyano, fluorine, trifluoromethyl, C1-C30 alkyl, C6-C30 aryl or C3-C30 heteroaryl. The compound is suitable for preparing an electron transport layer or an N-type charge generation layer of an OLED device, improves the efficiency and service life of the device, and reduces the voltage of the device.

Description

Technical Field

[0001] This invention relates to the field of display technology, and in particular to compounds containing phenanthroline, charge transport materials, and stacked organic electroluminescent devices. Background Technology

[0002] Organic light-emitting diode (OLED) devices include a light-emitting unit located between an anode and a cathode. The light-emitting unit includes an electron transport functional layer, a light-emitting layer, and a hole transport functional layer arranged in sequence.

[0003] To achieve high luminous brightness in OLED devices at relatively low operating current densities, at least two light-emitting units can be stacked in series to form a stacked organic light-emitting device (referred to as a stacked OLED or tandem OLED). Stacked OLEDs possess high luminous efficiency and lifetime, with luminous efficiency increasing as the number of light-emitting units increases. In stacked OLEDs, adjacent light-emitting units are connected by a charge generating layer (CGL), which includes an N-type charge generating layer and a P-type charge generating layer.

[0004] However, current stacked OLEDs have the problem of needing to improve efficiency. Summary of the Invention

[0005] In view of this, the present invention provides compounds containing phenanthroline, charge transport materials, and stacked organic electroluminescent devices, which can solve the technical problems existing in related technologies.

[0006] Specifically, the following technical solutions are included: On the one hand, a phenanthroline-containing compound is provided, the chemical structural formula of which is shown below:

[0007] Among them, one or both of Z1 to Z3 are N, and the rest are CH; R1 is one of the following: a substituted or unsubstituted pyridinyl group of C5-C30, a substituted or unsubstituted pyrimidinyl group of C4-C30, a substituted or unsubstituted quinolinyl group of C7-C30, or a substituted or unsubstituted isoquinolinyl group of C7-C30. Ar is one of hydrogen, deuterium, halogen, cyano, substituted or unsubstituted C1-C30 alkyl, substituted or unsubstituted C6-C30 aryl, or substituted or unsubstituted C3-C30 heteroaryl. L, Ar1, and Ar2 are each independently one of a single bond, a substituted or unsubstituted C6-C30 arylene, or a substituted or unsubstituted C3-C30 heteroarylene, and at least one of L and Ar is an aryl or heteroarylene. R is one of hydrogen, deuterium, cyanide, fluorine, trifluoromethyl, C1-C30 alkyl, substituted or unsubstituted C6-C30 aryl, or substituted or unsubstituted C3-C30 heteroaryl, and when R is a non-hydrogen group, n is an integer from 1 to 7.

[0008] In some possible implementations, L is one of a single bond, phenylene, naphthylene, pyridylene, pyrimidinylene, or piperidinylene; and, Ar is one of hydrogen, methyl, ethyl, propyl, isopropyl, cyano, adamantyl, phenyl, 1-5 deuterated phenyl, naphthyl, 1-7 deuterated naphthyl, biphenyl, terphenyl, naphthylphenyl, dibenzofuranyl, dibenzothiopheneyl, benzofuranyl, benzothiopheneyl, benzonitrile, pyridyl, 9,9-dialkylfluorenyl, 9,9-diarylfluorenyl, phenanthrene, phenylphenanthrene, triphenylene, anthracene, pyrene, phenyl, fluoranyl, acenaphthene, acenaphthene, benzo[anthracene], tetraphenyl, phenylnaphthyl, deuterated phenylnaphthyl, naphthylnaphthyl, pyridylnaphthyl, and benzonitrile-naphthyl.

[0009] In some possible implementations, Ar1 and Ar2 are each independently one of a single bond, a phenylene group, a naphthylene group, a pyridylene group, a pyrimidinylene group, or a piperidinylene group.

[0010] In some possible implementations, R is one of hydrogen, deuterium, cyanide, fluorine, trifluoromethyl, C1-C30 alkyl, substituted or unsubstituted C6-C30 aryl, or substituted or unsubstituted C3-C30 heteroaryl.

[0011] On the other hand, a charge transport material is provided, the charge transport material comprising the phenanthroline-containing compound described in the first aspect.

[0012] In another aspect, a stacked organic electroluminescent device is provided, the stacked organic electroluminescent device comprising: an anode, a cathode, and a plurality of light-emitting units disposed between the anode and the cathode, each of the light-emitting units comprising at least an electron transport layer; A charge generation layer is provided between any two adjacent light-emitting units, and the charge generation layer includes an N-type charge generation layer and a P-type charge generation layer; The electron transport layer and the N-type charge generation layer in the light-emitting unit closest to the anode both include the charge transport material described in the second aspect.

[0013] In some possible implementations, the electron transport layer and the N-type charge generation layer contain the same phenanthroline-containing compound.

[0014] In some possible implementations, the electron transport layer further includes a first dopant, which is a metal chelate.

[0015] In some possible implementations, the N-type charge generation layer further includes a second dopant selected from at least one of alkali metals, alkaline earth metals, and rare earth metals.

[0016] In some possible implementations, the light-emitting unit includes an electron transport functional layer, which includes the electron transport layer and further includes at least one of an electron injection layer and a hole blocking layer; and the light-emitting unit includes a hole transport functional layer, which includes at least one of a hole transport layer, a hole injection layer, and an electron blocking layer.

[0017] The technical solutions described in the embodiments of the present invention have at least the following beneficial effects: The phenanthroline-containing compound provided in this invention, based on its chemical composition, introduces an L group and an Ar group into the nitrogen heterocyclic groups Z1 to Z3, one of which is an aryl or heteroaryl group. This can increase the film-forming properties of the compound and the mutual stacking of molecules in the thin film morphology. Combined with the strong charge transport and generation capabilities of the phenanthroline group, they work synergistically to enhance the compound's electron and N-type charge generation capabilities, electron injection and transport capabilities. This makes the compound suitable for preparing electron transport layers or N-type charge generation layers for OLED devices, thereby improving the efficiency and lifespan of OLED devices and reducing their operating voltage. Detailed Implementation

[0018] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] Organic light-emitting devices (OLEDs), also known as organic light-emitting diodes, have advantages such as self-illumination, low power consumption, wide viewing angle, light weight, thinness, fast response, high contrast, low driving voltage, and flexibility, and are widely used in the fields of displays and lighting.

[0020] OLED devices are typically fabricated by vacuum evaporation or spin-coating of multiple layers of organic materials between two electrodes, resulting in a sandwich-like multilayer structure. For example, an OLED device includes a conductive glass anode and a metal cathode, as well as a light-emitting unit disposed between them. Along the direction close to the metal cathode, the light-emitting unit includes a hole transport functional layer, a light-emitting layer, and an electron transport functional layer stacked together.

[0021] The working mechanism of an OLED device is as follows: Under the action of an applied electric field, holes generated by the anode and electrons generated by the cathode are injected through the hole (electron) injection layer, then transported through the hole (electron) transport layer, and recombine in the emissive layer to generate excitons. The excitons excite the ground-state electrons in the emissive material of the emissive layer to the excited state, and finally the excited-state electrons return to the ground state, thus emitting light. The color (wavelength) of light emitted by an OLED device can be adjusted by changing the material of the emissive layer; for example, it can emit red, green, blue, and white light.

[0022] OLED devices are driven by current; the higher the current density, the higher the brightness. Typically, to achieve the high brightness required for practical applications, OLED devices must operate at high current densities for extended periods, preventing them from operating within their most efficient brightness range. More importantly, this significantly shortens the lifespan of OLED devices. Therefore, achieving both high luminous brightness and high current efficiency while operating at low current densities would significantly extend the lifespan of OLED devices, an effect that multilayer OLED devices can achieve.

[0023] A stacked OLED device comprises two or more light-emitting units connected in series and stacked. The light emitted by the multiple light-emitting units may be the same or different colors, and any two adjacent light-emitting units are connected by a charge generating layer (CGL). The multiple light-emitting units do not affect each other. The charge generating layer includes an N-type charge generating layer and a P-type charge generating layer.

[0024] In traditional OLED devices, electrons and holes injected from the two electrodes recombine in the light-emitting region to form excitons; a pair of electron-hole pairs can only form one pair of excitons. In stacked OLED devices, taking a bilayer example, the injected electrons and holes recombine with the electrons and holes generated in the CGL layer in the two light-emitting layers, forming two pairs of excitons.

[0025] Therefore, compared to traditional OLED devices, stacked OLED devices can achieve higher luminous brightness at the same current density. As the number of stacked light-emitting units increases, the current efficiency can increase exponentially. In other words, at the same brightness, the operating current density of stacked light-emitting units can be lower, thus significantly improving their lifetime. Furthermore, since each light-emitting unit in a stacked OLED emits light normally, the emission spectrum of the stacked OLED is the superposition of the emission spectra of all the units.

[0026] For stacked OLED devices, the selection of the charge transport layer (CGL) used to connect the various light-emitting sub-units is crucial. It is desirable for the CGL layer to not only efficiently generate charge but also to rapidly transport and inject the generated charge into the light-emitting layer. Therefore, it is necessary to provide a charge transport material that possesses high charge generation, charge transport, and charge injection rates, thereby improving not only the efficiency of the OLED device but also its cycle life.

[0027] To address the aforementioned technical problems, embodiments of the present invention provide a phenanthroline-containing compound suitable as a charge transport material. The chemical structural formula of the phenanthroline-containing compound is shown below:

[0028] In this configuration, one or both of Z1 to Z3 are nitrogen (N), and the rest are carbonyl (CH). For example, if one of Z1-Z3 is nitrogen (e.g., Z2 or Z3 is nitrogen), and the other two are carbonyl (CH), the nitrogen heterocyclic group containing all three is called a pyridinyl group. If two of Z1-Z3 are nitrogen (e.g., Z2 and Z3 are nitrogen), and the remaining one is carbonyl (CH), the nitrogen heterocyclic group containing all three can be pyridazinyl, pyrimidinyl, or pyrazinyl.

[0029] R1 is one of the following: a substituted or unsubstituted pyridinyl group of C5-C30, a substituted or unsubstituted pyrimidinyl group of C4-C30, a substituted or unsubstituted quinolinyl group of C7-C30, or a substituted or unsubstituted isoquinolinyl group of C7-C30.

[0030] Ar is one of hydrogen, deuterium, halogen, cyano, substituted or unsubstituted C1-C30 alkyl, substituted or unsubstituted C6-C30 aryl, or substituted or unsubstituted C3-C30 heteroaryl.

[0031] L, Ar1, and Ar2 are each independently one of a single bond, a substituted or unsubstituted C6-C30 aryl group, or a substituted or unsubstituted C3-C30 heteroaryl group, and at least one of L and Ar is an aryl or heteroaryl group.

[0032] R is one of hydrogen, deuterium, cyanide, fluorine, trifluoromethyl, C1-C30 alkyl, substituted or unsubstituted C6-C30 aryl, substituted or unsubstituted C3-C30 heteroaryl, and when R is a non-hydrogen group, n is an integer from 1 to 7, that is, it can be 1, 2, 3, 4, 5, 6 or 7.

[0033] It should be noted that the "hydrogen atom" involved in the embodiments of the present invention can be any isotope with different numbers of ions, namely protium, deuterium, and tritium.

[0034] In the embodiments of this invention, "alkyl" refers to a straight-chain or branched saturated hydrocarbon. The alkyl group can be a chain alkyl group or a cyclic alkyl group.

[0035] Examples of chain alkyl groups include, for example, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, sec-butyl, 1-methylbutyl, 1-ethylbutyl, n-pentyl, isopentyl, neopentyl, n-hexyl, 1-methylpentyl, 2-methylpentyl, 4-methylpentyl, 3,3-dimethylbutyl, 2-ethylbutyl, heptyl, n-octyl, tert-octyl, 1-methylheptyl, 2-ethylhexyl, 2-propylpentyl, 1-ethylpropyl, 1,1-dimethylpropyl, isohexyl, 4-methylhexyl, 5-methylhexyl, etc.

[0036] In this invention, the term "aryl" refers to an aromatic hydrocarbon group derived from an aromatic ring compound by removing one hydrogen atom. This can be a monocyclic aryl, a fused-ring aryl, or a polycyclic aryl. For polycyclic compounds, at least one ring must be an aromatic ring system. For example, "C6-C30 aryl" refers to an aryl group containing 6-30 carbon atoms. Each occurrence can be independently C5, C6, C7, C8, C9, C10, C12, C14, C18, C20, C25, or C30 aryl. Suitable examples include, but are not limited to, benzene, biphenyl, naphthalene, anthracene, phenanthrene, dinaphthalene, triphenylene oxide, and their derivatives. Understandably, multiple aryl groups can also be interrupted by short non-aromatic units (e.g., <10% non-H atoms, such as C, N, or O atoms), specifically acenaphthene, fluorene, or 9,9-diarylfluorene, triarylamine, and diaryl ether systems should also be included in the definition of aryl.

[0037] In the embodiments of this invention, "heteroaryl" refers to an aryl group in which at least one carbon atom is replaced by a non-carbon atom, which can be an N atom, an O atom, an S atom, etc. For example, "C3~C30 heteroaryl" refers to a heteroaryl group containing 3 to 30 carbon atoms, and each occurrence can be independently C3 heteroaryl, C4 heteroaryl, C5 heteroaryl, C6 heteroaryl, C7 heteroaryl, C8 heteroaryl, C9 heteroaryl, C10 heteroaryl, C11 heteroaryl, C12 heteroaryl, C14 heteroaryl, C18 heteroaryl, C20 heteroaryl, C25 heteroaryl, and C30 heteroaryl. Suitable examples include, but are not limited to: furan, benzofuran, thiophene, benzothiophene, pyrrole, pyrazole, triazole, imidazole, oxazole, oxadiazole, thiazole, tetrazolium, indole, carbazole, pyrrole-imidazolium, pyrrole-pyrrole, thiophene-pyrrole, thiophene-thiophene, furan-pyrrole, furan-furan, thiophene-furan, benzoisoxazole, benzoisothiazolium, pyridine, pyrazine, pyrimidine, triazine, quinoline, isoquinoline, o-diazonine, quinoxaline, phenanthridine, primidine, quinazoline, and quinazolineone.

[0038] "Aromaticyl" and "heteroaryl" refer to the subunits of aryl and heteroaryl groups, respectively. For the meanings and explanations of the aryl and heteroaryl groups involved, please refer to the relevant explanations of aryl and heteroaryl groups mentioned above.

[0039] The phenanthroline-containing compound provided in this invention, based on its chemical composition, introduces an L group and an Ar group into the nitrogen heterocyclic groups Z1 to Z3, one of which is an aryl or heteroaryl group. This can increase the film-forming properties of the compound and the mutual stacking of molecules in the thin film morphology. Combined with the strong charge transport and generation capabilities of the phenanthroline group, they work synergistically to enhance the compound's electron and N-type charge generation capabilities, electron injection and transport capabilities. This makes the compound suitable for preparing electron transport layers or N-type charge generation layers for OLED devices, thereby improving the efficiency and lifespan of OLED devices and reducing their operating voltage.

[0040] In some examples, L is one of a single bond, phenylene, naphthylene, pyridylene, pyrimidinylene, or piperidinylene. This can maintain the molecular planarity and conjugation length of the compound, avoid excessive steric hindrance, ensure smooth electron transport, and thus improve the electron mobility of the compound.

[0041] In some examples, Ar is one of hydrogen, methyl, ethyl, propyl, isopropyl, cyano, adamantyl, phenyl, 1-5 deuterated phenyl, naphthyl, 1-7 deuterated naphthyl, biphenyl, terphenyl, naphthylphenyl, dibenzofuranyl, dibenzothiopheneyl, benzofuranyl, benzothiopheneyl, benzonitrile, pyridyl, 9,9-dialkylfluorenyl, 9,9-diarylfluorenyl, phenanthrene, phenylphenanthrene, triphenylene, anthracene, pyrene, phenyl, fluoranyl, acenaphthene, acenaphthene, benzo[anthracene], tetraphenyl, phenylnaphthyl, deuterated phenylnaphthyl, naphthylnaphthyl, pyridylnaphthyl, and benzonitrile-naphthyl.

[0042] In some examples, Ar1 and Ar2 are each independently one of a single bond, phenylene, naphthylene, pyridylene, pyrimidinylene, or piperidinylene. This can maintain the molecular planarity and moderate conjugation length of the compound, avoid excessive steric hindrance, ensure smooth electron transport, and thus improve the electron mobility of the compound.

[0043] In some examples, one of Ar1 and Ar2 is a single bond and the other is a phenylene; or both Ar1 and Ar2 are phenylene.

[0044] When one of Ar1 and Ar2 is a single bond and the other is a phenylene, the steric hindrance is small, the overall conjugated structure is not destroyed, the electron transport path is short, electron transport is smoother, and the mobility is higher. When both Ar1 and Ar2 are phenylene, the conjugation length is moderate, the energy level is easier to control, and the symmetrical structure of the two phenylene compounds can make π-π stacking more stable, resulting in better film-forming properties of the compound.

[0045] It should be noted that when one of Ar1 and Ar2 is phenylene or both are phenylene, the nitrogen heterocyclic groups of Z1-Z3 and phenanthroline can be located at the para or meta position of the phenylene. This helps to maintain molecular planarity, avoid steric hindrance, ensure smooth electron transport, and thus improve electron mobility.

[0046] In some examples, R is one of hydrogen, deuterium, cyanide, fluorine, trifluoromethyl, C1-C30 alkyl, substituted or unsubstituted C6-C30 aryl, or substituted or unsubstituted C3-C30 heteroaryl.

[0047] The aforementioned substituents have moderate steric hindrance, which can further improve the thermal stability of the compound without destroying molecular conjugation and planarity. Among them, deuteration can significantly extend the device lifetime.

[0048] In some examples, R is hydrogen, methyl, ethyl, or phenyl.

[0049] When R is methyl, n is 1 or 2, and R is located on the nitrogen-containing benzene ring in the phenanthroline group.

[0050] When R is ethyl or phenyl, n is 1, and R is located on the nitrogen-containing benzene ring in the phenanthroline group.

[0051] When R is methyl, ethyl, or phenyl and n is 1, R can be located on a nitrogen-containing benzene ring in the phenanthroline group that is far from the nitrogen heterocyclic groups of Z1-Z3. This can keep R away from the core sites of electron transport and charge generation, avoiding adverse effects on the conjugated structure and planarity of the molecule. At the same time, it can effectively improve the film-forming properties and thermal stability of the compound with less steric hindrance.

[0052] When R is a methyl group and n is 2, these two methyl groups can simultaneously reside on the nitrogen-containing benzene ring of the phenanthroline group that is farther from the nitrogen-containing heterocyclic groups of Z1-Z3, or they can each reside on one of the two nitrogen-containing benzene rings of the phenanthroline group. When the two methyl groups reside on the two nitrogen-containing benzene rings of the phenanthroline group, the molecular symmetry can be optimized, resulting in a more uniform electron distribution, which is more beneficial for improving the stability of the compound.

[0053] In some examples, R1 is pyridyl or pyrimidinyl. Both pyridyl and pyrimidinyl groups are electron-deficient nitrogen-containing aromatic rings with a strong electron-withdrawing nitrogen atom, which can significantly enhance electron affinity. Furthermore, they synergistically interact with phenanthroline to accelerate electron generation, electron transport, and electron injection rates, making them suitable for electron transport layers or N-type charge generation layers in OLED devices, thereby improving the current efficiency and power efficiency of OLED devices. Moreover, pyridyl and pyrimidinyl groups are rigid aromatic ring structures with high molecular rigidity. Combined with fused-ring aryl groups, they can significantly increase the glass transition temperature and thermal decomposition temperature of the compound, thus improving the thermal stability of the device.

[0054] It should be noted that, for the phenanthroline-containing compounds involved in the embodiments of this application, each group can be arbitrarily combined according to the conditions defined above, and any combination obtained is within the protection scope of this application.

[0055] Regarding the phenanthroline-containing compounds mentioned above, some examples of these compounds are listed below, see compounds 1-165.

[0056]

[0057] Secondly, embodiments of the present invention also provide a charge transport material comprising any of the phenanthroline-containing compounds mentioned above. That is, embodiments of the present invention provide the application of the aforementioned phenanthroline-containing compounds in charge transport materials.

[0058] The charge transport material provided in this embodiment of the invention has all the advantages of the phenanthroline-containing compounds involved in this embodiment of the invention.

[0059] The embodiments of the present invention also provide the application of the above-mentioned charge transport materials in organic electroluminescent devices, organic solar cells, organic thin-film transistors, organic photodetectors, organic field-effect transistors, organic integrated circuits, or organic photosensors.

[0060] Thirdly, embodiments of the present invention provide a stacked organic electroluminescent device, which includes: an anode, a cathode, and a plurality of light-emitting units disposed between the anode and the cathode, each light-emitting unit including at least an electron transport layer; a charge generation layer is provided between any two adjacent light-emitting units, the charge generation layer including an N-type charge generation layer and a P-type charge generation layer; wherein, the electron transport layer and the N-type charge generation layer in the light-emitting unit closest to the anode both include the aforementioned charge transport material.

[0061] The stacked organic electroluminescent device provided in this embodiment of the invention includes the aforementioned charge transport material in both the electron transport layer and the N-type charge generation layer in the light-emitting unit closest to the anode. This allows the electron transport layer and the N-type charge generation layer to have similar energy levels, which helps to reduce the energy barrier between layers, thereby reducing the operating voltage and energy consumption of the device, and achieving the goal of improving device efficiency and device lifespan.

[0062] In some examples, the electron transport layer and the N-type charge generation layer use the same phenanthroline-containing compound, which makes the energy levels between the electron transport layer and the N-type charge generation layer closer, or even identical. This is more advantageous for improving device efficiency and lifetime, and reducing its operating voltage. Furthermore, because the same phenanthroline-containing compound is used, the number of evaporation sources can be reduced, improving device fabrication efficiency and lowering costs.

[0063] In some examples, the electron transport layer further includes a first dopant, which is a metal chelate, to optimize its electron transport performance. For example, the metal chelate is selected from at least one of lithium hydroxyquinoline and its derivatives, and more specifically, the lithium hydroxyquinoline is 8-hydroxyquinoline lithium.

[0064] The mass percentage of the first dopant in the electron transport layer is 1% to 70%, further 5% to 50%, including but not limited to one or any two of the following values: 2%, 4%, 6%, 8%, 10%, 12%, 14%, 16%, 18%, 20%, 22%, 24%, 26%, 28%, 29%, 30%, 32%, 34%, 36%, 38%, 40%, 42%, 44%, 46%, 48%, 50%, 52%, 54%, 56%, 58%, 60%, 62%, 64%, 66%, 68%, 69%, 70%, etc.

[0065] In some examples, the N-type charge generation layer further includes a second dopant selected from at least one of alkali metals, alkaline earth metals, and rare earth metals.

[0066] For example, the second dopant is at least one of Li, Na, Cs, Mg, Ca, Sr and Yb, and more specifically, the second dopant is at least one of Li and Yb, to optimize the electron injection and transport performance of the N-type charge generation layer, while improving the device efficiency through synergistic effects with phenanthroline-containing compounds.

[0067] The mass percentage of the second dopant in the N-type charge generation layer can be 1% to 50%, or more specifically 1% to 20%, which can be any of the following values ​​or any range of two values: 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 6%, 7%, 8%, 9%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, etc.

[0068] In some examples of the aforementioned multilayer organic electroluminescent devices, the light-emitting unit includes an electron transport functional layer, which further includes an electron transport layer and at least one of an electron injection layer and a hole blocking layer. For example, the electron transport functional layer includes an electron injection layer and an electron transport layer stacked sequentially, or the electron transport functional layer includes an electron injection layer, an electron transport layer, and a hole blocking layer stacked sequentially.

[0069] In some examples of the aforementioned multilayer organic light-emitting devices, the light-emitting unit includes a hole transport functional layer, which comprises at least one of a hole transport layer, a hole injection layer, and an electron blocking layer. For example, the hole transport functional layer comprises a hole injection layer and a hole transport layer stacked sequentially. Alternatively, the hole transport functional layer comprises a hole injection layer, a hole transport layer, and an electron blocking layer stacked sequentially.

[0070] It should be noted that the organic electroluminescent devices involved in the embodiments of the present invention can be prepared by vacuum evaporation, molecular beam evaporation, solvent-based dip coating, spin coating, rod coating or inkjet printing. Metal electrodes can be prepared by evaporation or sputtering.

[0071] This invention also provides a display device, which includes the stacked organic electroluminescent device described above.

[0072] For example, the display device may be a mobile phone, tablet, laptop, wearable device, television, electronic screen, vehicle display, special display device, etc.

[0073] The specific embodiments of the present invention will now be described in more detail. While specific embodiments of the present invention are described below, it should be understood that the present invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Where specific techniques or conditions are not specified in the embodiments, they are performed in accordance with the techniques or conditions described in the literature in the art or according to the product instructions. Reagents or instruments whose manufacturers are not specified are all conventional products that can be obtained commercially.

[0074] It should be noted that the serial numbers of the compounds provided in the following embodiments are the same as the compounds with the same serial numbers among the aforementioned compounds 1-165.

[0075] Example 1 The following examples 1-6 and comparative examples 1-9 illustrate the role of the phenanthroline-containing compounds provided in the embodiments of the present invention in stacked OLED devices.

[0076] The stacked OLED devices involved in Examples 1-6 and Comparative Examples 1-9 have the same fabrication process, use the same substrate material and electrode material, and the film thickness of the electrode material is also consistent. The difference is that the electron transport layer and N-type charge generation layer of the different OLED devices are different.

[0077] This stacked OLED device comprises the following layers arranged in sequence: anode / substrate - hole injection layer - hole transport layer a - light-emitting layer a - hole blocking layer a - electron transport layer a - N-type charge generation layer - P-type charge generation layer - hole transport layer b - light-emitting layer b - hole blocking layer b - electron transport layer b - electron injection layer - cathode - light extraction layer. The hole injection layer, hole transport layer a, light-emitting layer a, hole blocking layer a, and electron transport layer a together constitute the first light-emitting unit, while the hole transport layer b, light-emitting layer b, hole blocking layer b, electron transport layer b, and electron injection layer together constitute the second light-emitting unit.

[0078] The fabrication method of this stacked OLED device is as follows: The transparent conductive ITO glass substrate (with an anode on its surface, purchased from China Southern Glass Group Co., Ltd.) was ultrasonically treated in a commercial cleaning agent, rinsed in deionized water, and then washed sequentially with ethanol, acetone and deionized water. It was baked in a clean environment until all moisture was removed, cleaned with ultraviolet photosynthetic ozone, and then treated with oxygen plasma for 30 seconds.

[0079] The glass substrate with the anode was placed in a vacuum chamber, and a vacuum was drawn. A 10 nm thick layer of HT:3wt% P-dopant was deposited on ITO as a hole injection layer at a deposition rate of 0.1 nm / s.

[0080] Compound HT was deposited on the surface of the hole injection layer to form a 15 nm thick hole transport layer at a deposition rate of 0.1 nm / s.

[0081] BH:BD (20nm) was deposited on the surface of hole transport layer a as the light-emitting layer a, where BH is the host light-emitting material and BD is doped with 2wt% of fluorescent guest material. The deposition rate was 0.1nm / s.

[0082] HB was deposited on the surface of the light-emitting layer a as a hole blocking layer a (thickness of 5 nm) at a deposition rate of 0.1 nm / s.

[0083] The electron transport layer a is an electron transport layer containing the phenanthroline compound Liq (50% by mass and 15 nm thick) of the present invention, which is deposited on the surface of the hole blocking layer a at a deposition rate of 0.1 nm / s.

[0084] The phenanthroline compound Yb (1% by mass and 10 nm thick) of the present invention was deposited on electron transport layer a as an N-type charge generation layer at a deposition rate of 0.1 nm / s.

[0085] A 7wt% P-dopant (10nm thick) was deposited on the N-type charge generation layer as the P-type charge generation layer.

[0086] A 30 nm thick hole transport layer b is formed by evaporating HT on the surface of the P-type charge generation layer at a deposition rate of 0.1 nm / s.

[0087] BH:BD (20 nm thick) was deposited on the surface of hole transport layer b as light-emitting layer b, where BH is the host light-emitting material and BD is doped with 2 wt% fluorescent guest material. The deposition rate was 0.1 nm / s.

[0088] HB was deposited on the surface of the light-emitting layer 2 as a hole blocking layer b (thickness of 5 nm) at a deposition rate of 0.1 nm / s.

[0089] ET:Liq (50% by mass and 30 nm thick) was deposited on the surface of hole blocking layer b as electron transport layer b at a deposition rate of 0.1 nm / s.

[0090] Yb (1 nm thick) was deposited on the surface of electron transport layer b as an electron injection layer at a deposition rate of 0.1 nm / s.

[0091] Ag:Mg (mass ratio 9:1, thickness 140nm) was vapor-deposited on the surface of the electron injection layer as a cathode.

[0092] A light extraction layer (70 nm thick) is formed on the cathode surface using CPL material.

[0093] The raw material compounds involved in the fabrication process of the above-mentioned stacked OLED devices are shown below:

[0094]

[0095] ,

[0096] The performance of the stacked OLED devices provided in each embodiment and comparative example was tested. During the test, a known driving circuit was used to connect the anode and cathode. The test items and results are shown below.

[0097] (1) Driving voltage and current efficiency: Tested under a current density of 10 mA / cm² using an IVL (current-voltage-luminance) testing system (Guangzhou Jinghe Instrument Co., Ltd.). The driving voltage is in V and the current efficiency is in cd / A.

[0098] (2) Device lifetime: The time it takes for the brightness of the device to decay to 95% of its initial brightness at a current density of 20 mA / cm² (LT95). The lifetime testing system is the M6400 OLED device lifetime tester from MCSCIENCE, South Korea. The unit of device lifetime is Hr.

[0099] The composition of the electron transport layer a and the N-type charge generation layer in the OLED devices prepared in each embodiment and each comparative example is listed in Table 1, and the above performance test results are also listed in Table 1.

[0100]

[0101] As shown in Table 1, compared with Comparative Examples 1-9, the stacked OLED device provided in this embodiment of the invention uses the same phenanthroline compound in its electron transport layer a and N-type charge generation layer, which improves the device voltage, device efficiency, and device lifetime. In particular, the device lifetime is significantly improved. This is because the electron transport layer a has a strong electron transport capability and its energy level is basically consistent with that of the N-type charge generation layer, which helps to reduce the interlayer energy barrier, thereby achieving the purpose of reducing the device operating voltage and improving the device efficiency and device lifetime.

[0102] The above description is merely for the purpose of enabling those skilled in the art to understand the technical solutions of the present invention, and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A compound containing phenanthroline, characterized in that, The chemical structural formula of the phenanthroline-containing compound is shown below: Among them, one or both of Z1 to Z3 are N, and the rest are CH; R1 is one of the following: a substituted or unsubstituted pyridinyl group of C5-C30, a substituted or unsubstituted pyrimidinyl group of C4-C30, a substituted or unsubstituted quinolinyl group of C7-C30, or a substituted or unsubstituted isoquinolinyl group of C7-C30. Ar is one of hydrogen, deuterium, halogen, cyano, substituted or unsubstituted C1-C30 alkyl, substituted or unsubstituted C6-C30 aryl, or substituted or unsubstituted C3-C30 heteroaryl. L, Ar1, and Ar2 are each independently one of a single bond, a substituted or unsubstituted C6-C30 arylene, or a substituted or unsubstituted C3-C30 heteroarylene, and at least one of L and Ar is an aryl or heteroarylene. R is one of hydrogen, deuterium, cyanide, fluorine, trifluoromethyl, C1-C30 alkyl, substituted or unsubstituted C6-C30 aryl, or substituted or unsubstituted C3-C30 heteroaryl, and when R is a non-hydrogen group, n is an integer from 1 to 7.

2. The compound containing phenanthroline according to claim 1, characterized in that, L is one of a single bond, phenylene, naphthylene, pyridylene, pyrimidinylene, or piperidinylene; and, Ar is one of hydrogen, methyl, ethyl, propyl, isopropyl, cyano, adamantyl, phenyl, 1-5 deuterated phenyl, naphthyl, 1-7 deuterated naphthyl, biphenyl, terphenyl, naphthylphenyl, dibenzofuranyl, dibenzothiopheneyl, benzofuranyl, benzothiopheneyl, benzonitrile, pyridyl, 9,9-dialkylfluorenyl, 9,9-diarylfluorenyl, phenanthrene, phenylphenanthrene, triphenylene, anthracene, pyrene, phenyl, fluoranyl, acenaphthene, acenaphthene, benzo[anthracene], tetraphenyl, phenylnaphthyl, deuterated phenylnaphthyl, naphthylnaphthyl, pyridylnaphthyl, and benzonitrile-naphthyl.

3. The compound containing phenanthroline according to claim 1, characterized in that, Ar1 and Ar2 are each independently one of a single bond, phenylene, naphthylene, pyridylene, pyrimidinylene, or piperidinylene.

4. The compound containing phenanthroline according to claim 1, characterized in that, R is one of hydrogen, deuterium, cyanide, fluorine, trifluoromethyl, C1-C30 alkyl, substituted or unsubstituted C6-C30 aryl, or substituted or unsubstituted C3-C30 heteroaryl.

5. A charge transport material, characterized in that, The charge transport material includes the phenanthroline-containing compound as described in any one of claims 1-4.

6. A stacked organic electroluminescent device, characterized in that, The stacked organic electroluminescent device includes: an anode, a cathode, and a plurality of light-emitting units disposed between the anode and the cathode, each of the light-emitting units including at least an electron transport layer; A charge generation layer is provided between any two adjacent light-emitting units, and the charge generation layer includes an N-type charge generation layer and a P-type charge generation layer; The electron transport layer and the N-type charge generation layer in the light-emitting unit closest to the anode both include the charge transport material described in claim 5.

7. The stacked organic electroluminescent device according to claim 6, characterized in that, The electron transport layer and the N-type charge generation layer contain the same phenanthroline-containing compound.

8. The stacked organic electroluminescent device according to claim 6, characterized in that, The electron transport layer further includes a first dopant, which is a metal chelate.

9. The stacked organic electroluminescent device according to claim 6, characterized in that, The N-type charge generation layer further includes a second dopant, which is selected from at least one of alkali metals, alkaline earth metals, and rare earth metals.

10. The stacked organic electroluminescent device according to claim 6, characterized in that, The light-emitting unit includes an electron transport functional layer, which includes the electron transport layer and at least one of an electron injection layer and a hole blocking layer; and the light-emitting unit includes a hole transport functional layer, which includes at least one of a hole transport layer, a hole injection layer, and an electron blocking layer.

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