Organic electroluminescent device and display device

Abstract

The present invention provides an organic electroluminescent device and a display device. The organic electroluminescent device includes a charge generation layer, which includes an organic compound having a structure shown in Formula 1: #imgabs0# Ar1 and Ar2 are each independently selected from a group having a structure shown in Formula 2 or Formula 3: #imgabs1# wherein * represents a connection site with the pyridine group in Formula 1; Y1, Y2, Y3, and Y4 are each independently selected from N or -CR; and R, R1, R2, R3, R4, R5, R6, R7, R8, and R9 are each independently selected from hydrogen, deuterium, tritium, a substituted or unsubstituted C1-C20 alkyl group, a substituted or unsubstituted C1-C20 alkoxy group, a substituted or unsubstituted C5-C60 aryl group, or a substituted or unsubstituted C4-C60 heteroaryl group. The present invention introduces the organic compound shown in Formula 1 into the charge generation layer of an OLED, which is not easily degraded or deteriorated during the operation of the OLED, thereby improving the efficiency, stability, and lifespan of the OLED.

Description

Technical Field

[0001] The present invention relates to an organic electroluminescent device and a display apparatus, belonging to the technical field of organic electroluminescence. Background Art

[0002] Organic Light Emitting Diodes (OLEDs) are devices that emit light through electric current. They offer advantages such as lightness, flexibility, high contrast, and a wide color gamut. Due to their high current efficiency and long lifespan, stacked OLEDs have gradually become a research focus. These devices include a charge generation layer (CGL) placed between a first and second light-emitting stack to ensure efficient charge distribution across the stack while improving the current efficiency of each layer. However, during the use of OLEDs, especially during long-term operation, the materials in the charge generation layer are susceptible to degradation or deterioration, resulting in reduced performance and lifespan. Summary of the Invention

[0003] The present invention provides an organic electroluminescent device and a display apparatus to at least solve the technical problem that the material of the charge generation layer is easily degraded or deteriorated, and the resulting reduction in OLED performance and lifespan.

[0004] In one aspect of the present invention, an organic electroluminescent device is provided, comprising a charge generation layer, wherein the charge generation layer comprises an organic compound having a structure represented by Formula 1 below:

[0005]

[0006] Ar1 and Ar2 are each independently selected from the group represented by the structure of Formula 2 or Formula 3:

[0007]

[0008] Wherein, * represents the connection site with the pyridine group in Formula 1;

[0009] Y1, Y2, Y3, and Y4 are each independently selected from N or -CR;

[0010] R, R1, R2, R3, R4, R5, R6, R7, R8, and R9 are each independently selected from hydrogen, deuterium, tritium, substituted or unsubstituted C1-C20 alkyl, substituted or unsubstituted C1-C20 alkoxy, substituted or unsubstituted C5-C60 aryl, and substituted or unsubstituted C4-C60 heteroaryl.

[0011] Optionally, Ar1 and Ar2 are both groups of the structure shown in Formula 2, or Ar1 and Ar2 are both groups of the structure shown in Formula 3.

[0012] Optionally, in Formula 3, three of Y1, Y2, Y3, and Y4 are -CR, and the remaining one is N; or, Y1, Y2, Y3, and Y4 are all -CR.

[0013] Optionally, in Formula 1, R1 and / or R3 are hydrogen; and / or, in Formula 2, three of R4, R5, R6, and R7 are hydrogen; and / or, in Formula 3, R8 and / or R9 are hydrogen.

[0014] Optionally, the substituted or unsubstituted C5-C60 aryl group, substituted or unsubstituted C4-C60 heteroaryl group is selected from the following substituents: phenyl, alkylphenyl, biphenyl, alkylbiphenyl, halogenated phenyl, alkoxyphenyl, halogenated alkoxyphenyl, cyanophenyl, silylphenyl, naphthyl, alkylnaphthyl, halogenated naphthyl, cyanonaphthyl, silylnaphthyl, phenylnaphthyl, pyridyl, alkylpyridyl, halogenated pyridyl, cyanopyridyl, alkoxypyridyl, silylpyridyl, phenyl Pyridyl, pyrimidinyl, halogenated pyrimidinyl, cyanopyrimidinyl, alkoxypyrimidinyl, phenylpyrimidinyl, quinolyl, isoquinolyl, phenylquinolyl, quinoxalinyl, pyrazinyl, quinazolinyl, naphthyridinyl, benzothiophenyl, benzofuranyl, dibenzothiophenyl, arylthiazolyl, dibenzofuranyl, fluorenyl, carbazolyl, imidazolyl, carbolinyl, phenanthryl, terphenyl, bipyridyl, terpyridyl, phenylterpyridyl, triphenylene, anthracenyl, fluoranthenyl, diazafluorenyl, phenanthroline.

[0015] Optionally, the organic compound is a compound having one of the following general formulas:

[0016]

[0017] Optionally, the organic compound is selected from the following compounds:

[0018]

[0019]

[0020]

[0021]

[0022] Optionally, the charge generation layer includes a p-type charge generation layer and an n-type charge generation layer, and the n-type charge generation layer includes the organic compound.

[0023] Optionally, the n-type charge generation layer further comprises a metal material, and the metal material comprises at least one of an alkali metal, an alkaline earth metal, and a transition metal.

[0024] Optionally, the metal material includes at least one metal selected from the group consisting of lithium, ytterbium, and silver.

[0025] Another aspect of the present invention provides a display device comprising the organic electroluminescent device.

[0026] The organic electroluminescent device provided by the present invention has an organic compound having a structure shown in Formula 1 introduced into its charge generation layer. The nitrogen atoms on the three aromatic heterocyclic rings of the organic compound can form multiple coordination with metal atoms, resulting in a stable structure and good thermal / electrical stability. It is not easily degraded or deteriorated during the operation of the OLED, thereby improving the efficiency, stability, lifespan and other performance of the OLED. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a schematic structural diagram of a stacked OLED according to an embodiment of the present invention;

[0028] Figure 2 is the H NMR spectrum of compound M-2d 1 HNMR spectrum;

[0029] Figure 3 Compound M-3f 1 HNMR spectrum. DETAILED DESCRIPTION

[0030] The inventors have discovered that the materials used for the charge generation layer have poor thermal and electrical stability, which affects the efficiency and lifespan of OLEDs. Specifically, the charge generation layer has a PN junction, in which an n-type charge generation layer and a p-type charge generation layer are stacked in sequence. Typically, in the charge generation layer of a stacked OLED device, due to the energy level difference between the n-type charge generation layer and the p-type charge generation layer, charges are generated at the interface between the p-type charge generation layer and the adjacent film layer (such as the hole injection layer or hole transport layer), resulting in degraded electron injection in the n-type charge generation layer. When the n-type charge generation layer is doped with a metal, the metal easily diffuses into the p-type charge generation layer, resulting in a reduced lifespan of the OLED. Therefore, long-term operation of the OLED leads to degradation or deterioration of the material of the charge generation layer. As a result, not only is the electron injection efficiency from the interface between the p-type charge generation layer and the adjacent film layer (such as the hole injection layer or hole transport layer) to the n-type charge generation layer significantly reduced, but the electron injection efficiency from the n-type charge generation layer to the adjacent electron transport layer is also significantly reduced, resulting in reduced performance and lifespan of the OLED.

[0031] In view of the above problems, an embodiment of the present invention provides an organic electroluminescent device, which includes a charge generation layer, and the charge generation layer includes an organic compound having a structure shown in Formula 1 below:

[0032]

[0033] Ar1 and Ar2 are each independently selected from the group represented by the structure of Formula 2 or Formula 3:

[0034]

[0035] Wherein, * represents the connection site with the pyridine group in Formula 1; Y1, Y2, Y3, and Y4 are each independently selected from N or -CR; R, R1, R2, R3, R4, R5, R6, R7, R8, and R9 are each independently selected from hydrogen, deuterium, tritium, substituted or unsubstituted C1-C20 alkyl, substituted or unsubstituted C1-C20 alkoxy, substituted or unsubstituted C5-C60 aryl, and substituted or unsubstituted C4-C60 heteroaryl.

[0036] The organic compound shown in Formula 1 can react with metal atoms to obtain electrons to form negative ions, thereby forming n-type doping. The nitrogen atoms (N) on the three aromatic heterocyclic rings can form multiple coordination with the metal, resulting in a stable structure, good thermal / electrical stability, and resistance to degradation or deterioration. It is also conducive to electron transport, and can therefore be used in the charge generation layer of a stacked OLED device to improve the efficiency, stability, and lifespan of the OLED.

[0037] Specifically, the substituted or unsubstituted C5-C60 aryl group and the substituted or unsubstituted C4-C60 heteroaryl group as described above can be selected from the following substituents: phenyl, alkylphenyl, biphenyl, alkylbiphenyl, halogenated phenyl, alkoxyphenyl, halogenated alkoxyphenyl, cyanophenyl, silylphenyl, naphthyl, alkylnaphthyl, halogenated naphthyl, cyanonaphthyl, silylnaphthyl, phenylnaphthyl, pyridyl, alkylpyridyl, halogenated pyridyl, cyanopyridyl, alkoxypyridyl, silylpyridyl , phenylpyridyl, pyrimidinyl, halogenated pyrimidinyl, cyanopyrimidinyl, alkoxypyrimidinyl, phenylpyrimidinyl, quinolyl, isoquinolyl, phenylquinolyl, quinoxalinyl, pyrazinyl, quinazolinyl, naphthyridinyl, benzothiophenyl, benzofuranyl, dibenzothiophenyl, arylthiazolyl, dibenzofuranyl, fluorenyl, carbazolyl, imidazolyl, carbolinyl, phenanthrenyl, terphenyl, bipyridyl, terpyridyl, phenylterpyridyl, triphenylene, anthracenyl, fluoranthenyl, diazafluorenyl, phenanthroline. The halo refers to halogen substitution, and the halogen is, for example, selected from F, Cl, Br, I, and the like.

[0038] For example, the substituted or unsubstituted C5-C60 aryl group and the substituted or unsubstituted C4-C60 heteroaryl group as described above may be selected from the following groups:

[0039]

[0040]

[0041]

[0042]

[0043] In addition, Ar1 and Ar2 can be the same or different groups, preferably the same group, which is beneficial to the preparation efficiency and purity of the compound and further improves its stability and electron transport properties after forming n-type doping with metal.

[0044] For example, in some embodiments, Ar1 and Ar2 are both groups of the structure shown in Formula 2. In this case, the organic compound shown in Formula 1 has the structure shown in Formula 1-1 below:

[0045]

[0046] The organic compound shown in Formula 1-1 is a terpyridine derivative, which has terpyridine as its core structure. The energy level and transmission characteristics of the organic compound are modified by R1 to R7 modification groups, which can improve its stability after forming n-type doping with low-function metals, improve the stability of the charge generation layer, and thus improve the stability of the stacked device and other performance.

[0047] In other embodiments, Ar1 and Ar2 are both groups of the structure shown in Formula 3. In this case, the organic compound shown in Formula 1 has the structure shown in Formula 1-2 below:

[0048]

[0049] Generally, in Formula 3 / Formula 1-2, at least three of Y1, Y2, Y3, and Y4 are -CR, and the others may be N or -CR.

[0050] Illustratively, Y1, Y2, Y3, and Y4 are all -CR.

[0051] Preferably, three of Y1, Y2, Y3, and Y4 are -CR, and the remaining one is N. In this way, by using 2,6-di(naphthyridine)pyridine as the core structure and modifying the energy level and transmission characteristics of the organic compound through the R1 to R9 modification groups, its stability after forming n-type doping with low-function metals can be improved, the stability of the charge generation layer can be improved, and thus the stability and other performance of the stacked device can be improved.

[0052] Taking into account factors such as steric hindrance, two of the above R1, R2, and R3 are hydrogen, and preferably R1 and / or R3 are hydrogen.

[0053] Furthermore, three of R4, R5, R6, and R7 are hydrogen.

[0054] Furthermore, R8 and / or R9 are hydrogen, ie one or both of them are hydrogen.

[0055] Furthermore, R in -CR is a substituent, which may be hydrogen.

[0056] In some specific embodiments, the organic compound is a compound having one of the following general formulas:

[0057]

[0058]

[0059] In some embodiments, the organic compound having the structure shown in Formula 1 is selected from the following compounds:

[0060]

[0061]

[0062]

[0063] The organic compound represented by Formula 1 can be prepared by a Suzuki reaction, which may specifically include: subjecting a halogenated aromatic hydrocarbon / halogenated heteroaromatic hydrocarbon to a Suzuki reaction with an aromatic hydrocarbon / heteroaromatic hydrocarbon substituted with a borate group to connect the aryl group in the halogenated aromatic hydrocarbon / heteroaromatic hydrocarbon with the aryl group in the borate group-substituted aromatic hydrocarbon / heteroaromatic hydrocarbon substituted with the borate group to introduce a substituted or unsubstituted aryl group / heteroaromatic group to prepare the organic compound represented by Formula 1.

[0064] Illustratively, Ar1 and Ar2 are the same, and the compound having the structure represented by Formula 4 can be reacted with the compound having the structure represented by Formula 5 to prepare the compound represented by Formula 1.

[0065] A r1 -Y formula 4

[0066]

[0067] Wherein, Y is a borate group X is a halogen; or, Y is a halogen, and X is a borate group. The halogen can be specifically selected from F, Cl, Br, and I.

[0068] In general, considering factors such as steric hindrance, when the number of aromatic rings in the compound represented by Formula 5 is greater than that in the compound represented by Formula 4, Y is a borate group. X is a halogen; when the number of aromatic rings of the compound represented by Formula 4 is greater than the number of aromatic rings of the compound represented by Formula 5, Y is a halogen and X is a borate group.

[0069] For further example, Formula 1-2 can be prepared by subjecting the compound represented by Formula 4-1 and the compound represented by Formula 5-1 to Suzuki reaction:

[0070]

[0071] Specifically, the charge generation layer includes a p-type charge generation layer (or hole auxiliary layer, p-CGL) and an n-type charge generation layer (or electron auxiliary layer, n-CGL), and the n-type charge generation layer includes the organic compound having the structure shown in Formula 1.

[0072] In addition, the n-type charge generation layer further comprises a metal, and the above-mentioned organic compound reacts with the metal to form n-type doping, which has good thermal / electrical stability and is conducive to electron transport.

[0073] Optionally, the metal in the n-type charge generation layer includes at least one of an alkali metal, an alkaline earth metal, and a transition metal. Specifically, the metal in the n-type charge generation layer may include a low work function metal (such as lithium, ytterbium, etc.) or a non-low work function metal (such as silver).

[0074] In some preferred embodiments, the metal in the n-type charge generation layer includes at least one of lithium (Li), ytterbium (Yb), and silver (Ag), which is more conducive to cooperating with the organic compound shown in Formula 1 to improve the electron transport performance of the n-type charge generation layer.

[0075] In some embodiments, the volume percentage (doping concentration) of the metal in the n-type charge generation layer is 0.5% to 5%, for example, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, etc.

[0076] Specifically, the organic electroluminescent device is a stacked OLED, which includes an anode, a cathode, and at least two light-emitting stacks disposed between the anode and the cathode, and a charge generation layer is disposed between two adjacent light-emitting stacks.

[0077] Among them, each light-emitting stack independently includes a hole transport region, an organic light-emitting layer, and an electron transport region stacked in sequence. In two adjacent light-emitting stacks, the n-type charge generation layer is arranged between the p-type charge generation layer and the electron transport region of one light-emitting stack, and the p-type charge generation layer is arranged between the n-type charge generation layer and the hole transport region of the other light-emitting stack.

[0078] The hole transport region can be a single-layer hole transport layer (HTL), including single-layer hole transport layers containing only one compound and single-layer hole transport layers containing multiple compounds. The hole transport region can also be a multi-layer structure including at least one of a hole injection layer (HIL), a hole transport layer (HTL), and an electron blocking layer (EBL).

[0079] The electron transport region can be a single-layer electron transport layer (ETL), including a single-layer electron transport layer containing only one compound and a single-layer electron transport layer containing multiple compounds. The electron transport region can also be a multi-layer structure including at least one of an electron injection layer (EIL), an electron transport layer (ETL), and a hole blocking layer (HBL).

[0080] Below, Figure 1 The stacked OLED of the embodiment shown is specifically introduced as follows: Figure 1 As shown, the stacked OLED includes two light-emitting stacks, namely a first light-emitting stack and a second light-emitting stack. The first light-emitting stack includes a first hole transport layer HTL-1, a first electron blocking layer EBL-1, a first organic light-emitting layer EML-1, a first hole blocking layer HBL-1, and a first electron transport layer ETL-1. The second light-emitting stack includes a second hole transport layer HTL-2, a second electron blocking layer EBL-2, a second organic light-emitting layer EML-2, a second hole blocking layer HBL-2, and a second electron transport layer ETL-2. The stacked OLED also includes a hole injection layer H IL and electron injection layer EIL, anode, hole injection layer HIL, first hole transport layer HTL-1, first electron blocking layer EBL-1, first organic light-emitting layer EML-1, first hole blocking layer HBL-1, first electron transport layer ETL-1, n-type charge generation layer n-CGL, p-type charge generation layer p-CGL, second hole transport layer HTL-2, second electron blocking layer EBL-2, second organic light-emitting layer EML-2, second hole blocking layer HBL-2, second electron transport layer ETL-2, electron injection layer EIL, and cathode are stacked in sequence.

[0081] The thickness of each of the above layers can adopt the conventional thickness of these layers in this field; unless otherwise specified, the material of each of the above layers can be the conventional material of these layers in this field.

[0082] Exemplarily, the anode material can be an oxide transparent conductive material such as indium tin oxide (ITO), indium zinc oxide (IZO), tin dioxide (SnO2), zinc oxide (ZnO) and any combination thereof; the cathode material can be a metal or alloy such as magnesium (Mg), silver (Ag), aluminum (Al), aluminum-lithium (Al-Li), calcium (Ca), magnesium-indium (Mg-In), magnesium-silver (Mg-Ag) and any combination thereof.

[0083] Illustratively, the hole injection layer comprises 2,3,6,7,10,11-hexacyano-1,4,5,8,9,12-hexaazatriphenylene (HAT-CN) and 4,4',4"-tris(carbazol-9-yl)triphenylamine (TCTA); the hole transport layer comprises TCTA; the electron blocking layer comprises m-CP; and the P-type charge generation layer comprises HAT-CN and TCTA.

[0084] Illustratively, the organic light-emitting layer includes a blue light-emitting layer, which contains a host material and a guest material, the host material includes an anthracene derivative, for example, the following compound A-1, and the guest material includes a boron nitrogen (BN) resonance fluorescent material, for example, the following compound B-1.

[0085]

[0086] Illustratively, the electron injection layer comprises Yb, the electron transport layer comprises 1,3,5-tris(1-phenyl-1H-benzimidazol-2-yl)benzene (TPBI) and lithium octahydroxyquinoline (LiQ), and the hole blocking layer comprises 2,9-dimethyl-4,7-biphenyl-1,10-phenanthroline (BCP).

[0087] The stacked OLED of the present invention can be produced by conventional methods in the art, such as sequentially depositing each layer on a substrate, and there is no particular limitation on this.

[0088] An embodiment of the present invention further provides a display device comprising the aforementioned organic electroluminescent device. Specifically, the display device may be a display device such as an OLED display, as well as any product or component with a display function, such as a television, digital camera, mobile phone, or tablet computer, that incorporates the display device. The advantages of this display device over the prior art are the same as those of the aforementioned organic electroluminescent device, and are not further elaborated here.

[0089] The organic electroluminescent device of the present invention is further described below through specific examples. Compounds M-2a to M-2j and M-3a to M-3j used in the examples of the present invention were prepared by Suzuki reaction and characterized by nuclear magnetic resonance spectra (such as hydrogen spectrum ( 1 HNMR)) analysis and other methods have been used to determine that it has the corresponding structure (list M-2d 1 HNMR images Figure 2 As shown, the M-3f 1 HNMR images Figure 3 As shown, the peak corresponding to the number in the spectrum represents the hydrogen peak at the position corresponding to the number in the compound structure, for example, Figure 2 In the spectrum, the peaks corresponding to 2, 4, 8, and 12 (around δ8.45) are the peaks of hydrogen at the positions corresponding to 2, 4, 8, and 12 in the compound structure).

[0090] Example 1

[0091] The structure of stacked OLED is as follows Figure 1 The materials and thickness of each layer are shown in Table 1.

[0092] Table 1

[0093]

[0094] * “3% Li” indicates that the Li doping concentration in the N-CGL layer is 3%.

[0095] Examples 2 to 20, Comparative Example 1: The difference from Example 1 is that different organic compounds are used in n-CGL, as shown in Table 2, and the other conditions are the same.

[0096] The performance of the OLEDs of the embodiments and comparative examples was measured, including current density, driving voltage, current efficiency, and LT95 life (the time it takes for the device to decay from an initial brightness of 1000 nit to 95% of the initial brightness). The results are shown in Table 2.

[0097] Table 2

[0098]

[0099] As can be seen, at the same current density, the OLEDs of Examples 1 to 20 have longer lifespans, lower driving voltages, and better current efficiency than those of Comparative Example 1. This demonstrates that M-2a to M-2j and M-3a to M-3j, when used in n-CGLs, exhibit better thermal and electrical stability and are less susceptible to degradation or deterioration during device operation, thereby improving the efficiency, stability, and lifespan of the OLED.

Claims

1. An organic electroluminescent device, characterized in that: The charge generation layer includes a p-type charge generation layer and an n-type charge generation layer, and the n-type charge generation layer includes the organic compound having the structure shown in Formula 1, and the organic compound having the structure shown in Formula 1 is selected from the following compounds: The n-type charge generation layer further comprises a metal material, wherein the metal material comprises at least one metal selected from lithium, ytterbium and silver, and the volume percentage of the metal material in the n-type charge generation layer is 0.5% to 5%.

2. A display device, characterized in that: The organic electroluminescent device according to claim 1 is included.

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