Organic light-emitting device, display panel and display device

Abstract

The invention provides an organic light-emitting device, a display panel and a display device.The organic light-emitting device comprises an anode, at least two light-emitting units and a cathode which are arranged in a stacked mode, the adjacent light-emitting units are connected through a charge generation layer, and the charge generation layer comprises an N-type charge generation layer, a middle layer and a P-type charge generation layer which are arranged in a stacked mode; the N-type charge generation layer comprises a first electron transport type organic material and an N-type dopant; the P-type charge generation layer comprises a first hole transport type organic material and a P-type dopant; the middle layer has the performance of transmitting electrons and / or holes, and the problems that in the prior art, an organic light-emitting device is high in driving voltage, low in efficiency and poor in device stability are solved.

Description

Technical Field

[0001] The present invention relates to the field of organic light emitting technology, and in particular to an organic light emitting device, a display panel and a display apparatus. Background Art

[0002] As a new generation of display technology, organic electroluminescent materials (OLEDs) have the advantages of ultra-thinness, self-luminescence, wide viewing angle, fast response, high luminous efficiency, good temperature adaptability, simple production process, low driving voltage, and low energy consumption. They have been widely used in industries such as flat panel displays, flexible displays, solid-state lighting, and vehicle-mounted displays. Stacked OLED devices are an effective means to improve the efficiency and life of OLEDs. Specifically, a device is composed of two or more electroluminescent units stacked vertically, and each light-emitting unit is connected by a charge generation layer. Compared with traditional OLEDs, stacked OLEDs have higher luminous brightness and current efficiency, and their luminous brightness and current efficiency increase exponentially with the increase in the number of series-connected light-emitting units. However, like traditional OLEDs, stacked OLEDs have aging problems and face the problem of reduced stability. Therefore, the performance of stacked OLED devices still needs to be further improved. Summary of the invention

[0003] The main purpose of the present invention is to provide an organic light-emitting device, a display panel and a display apparatus to solve the problems of high driving voltage, low efficiency and poor device stability of the organic light-emitting device in the prior art.

[0004] To achieve the above object, according to one aspect of the present invention, an organic light-emitting device is provided, comprising a stacked anode, at least two light-emitting units and a cathode, wherein adjacent light-emitting units are connected via a charge generation layer, and the charge generation layer comprises a stacked N-type charge generation layer, an intermediate layer and a P-type charge generation layer;

[0005] The N-type charge generation layer includes a first electron transport type organic material and an N-type dopant;

[0006] The P-type charge generation layer includes a first hole transport type organic material and a P-type dopant;

[0007] The interlayer has the property of transporting electrons and / or holes.

[0008] Furthermore, the intermediate layer includes a first material, and the first material is a second electron transport type organic material and / or a second hole transport type organic material.

[0009] Furthermore, the first material includes a second electron transport type organic material and a second hole transport type organic material, wherein an N-type charge generation layer, a second electron transport type organic material, a second hole transport type organic material, and a P-type charge generation layer are stacked in sequence.

[0010] Furthermore, the first electron transport material and the second electron transport material are the same material.

[0011] Furthermore, the first hole transport type organic material and the second hole transport type organic material are the same material.

[0012] Furthermore, the middle layer is a metal thin layer.

[0013] Furthermore, the thickness of the middle layer is

[0014] Further, the energy level difference between the HOMO energy level of the first hole transport type organic material and the LUMO energy level of the first electron transport type organic material is ≤0.8 eV.

[0015] Furthermore, the light-emitting unit also includes an organic light-emitting layer and an electron transport layer, the electron transport layer is located between the organic light-emitting layer and the N-type charge transport layer or between the organic light-emitting layer and the cathode, and the energy level difference between the LUMO energy level of the N-type charge transport layer and the LUMO energy level of the electron transport layer is ≤0.5eV.

[0016] Furthermore, the first electron transport type organic material is selected from the structure shown in formula (I):

[0017]

[0018] Wherein, X, Y, and Z are independently selected from one of C and N, and at least one of X, Y, and Z is N;

[0019] R1 is selected from at least one of H, phenyl, pyridyl, and pyridylphenyl;

[0020] Ar is selected from substituted or unsubstituted phenyl, anthracenyl, phenanthrenyl, pyrene, triphenylenyl, pyridyl, o-phenanthroline, naphthoxazolyl, naphthoimidazolyl, naphthothiazolyl, wherein the substituent is at least one of -CN, phenyl, and o-phenanthroline.

[0021] Furthermore, a hole blocking layer is further included between the organic light-emitting layer and the electron transport layer, and the energy level difference between the LUMO energy level of the hole blocking layer and the LUMO energy level of the electron transport layer is greater than 0.5 eV and not greater than 1.0 eV.

[0022] Preferably, the electron mobility of the hole blocking layer is smaller than the electron mobility of the electron transporting layer.

[0023] Preferably, the electron mobility of the hole blocking layer is 1.0 -9 ~1.0 -8 cm 2 / Vs.

[0024] Preferably, the hole blocking layer comprises a triazine-based bipolar electron transport material having at least one of a triarylamine group, a carbazole group, and a phenoloxazine group.

[0025] Preferably, the triazine bipolar electron transport material is selected from at least one of the structures shown in Formula III and Formula IV:

[0026]

[0027] Wherein, R1' is selected from one of substituted or unsubstituted phenyl, naphthyl, and dibenzofuran, and the substituent is an aromatic group, and the aromatic group is selected from one of phenyl, biphenyl, and dibenzofuran;

[0028] R2' and R3' are independently selected from one of an alkyl group and a phenyl group, or R2' and R3' are independently selected from one of an alkylene group and a phenylene group, and R2' and R3' and Si connected to the two together form a five-membered ring;

[0029] m is selected from a single bond or a phenylene group;

[0030] n1 is a single bond, an S atom, or one of the atoms;

[0031] R4' is selected from one of substituted or unsubstituted phenyl, naphthyl, and dibenzofuran, the substituted substituent is an aromatic group, and the aromatic group is selected from one of phenyl, biphenyl, and dibenzofuran;

[0032] R5' and R6' are independently selected from one of an alkyl group and a phenyl group, or R2' and R3' are independently selected from one of an alkylene group and a phenylene group, and R5' and R6' and Si connected to the two together form a five-membered ring;

[0033] n2 is selected from a single bond, a S atom or an O atom.

[0034] Furthermore, a hole blocking layer is further included between the organic light-emitting layer and the electron transport layer, and the energy level difference between the LUMO energy level of the hole blocking layer and the LUMO energy level of the electron transport layer is ≤0.4 eV.

[0035] Preferably, the electron mobility of the hole blocking layer is 1.0 -7 ~1.0 -6 cm 2 / Vs.

[0036] Preferably, the hole blocking layer comprises a triazine-based strong electron transport material, and the structure of the triazine-based strong electron transport material is as follows:

[0037]

[0038] A is selected from one of substituted or unsubstituted phenyl, biphenyl, naphthyl, anthracenyl, phenanthrenyl, triphenylene, azaphenanthrenyl, 9,9-dimethylacridinyl, dibenzofuranyl, and dibenzothiophenyl, and the substituted substituent is at least one of phenyl, naphthyl, pyridyl, pyridylphenyl, and quinolyl;

[0039] R1" is selected from substituted or unsubstituted dibenzofuranyl and dibenzothiophenyl, wherein the substituted substituent is at least one of an alkyl, a phenyl, and a phenylene group;

[0040] R2" and R3" are independently selected from one of alkyl and phenyl groups, or R2" and R3" are independently selected from one of alkylene and phenyl groups, and R2" and R3" and Si to which they are connected together form a five-membered ring.

[0041] According to another aspect of the present invention, there is provided a display panel comprising the above organic light emitting device.

[0042] According to yet another aspect of the present invention, a display device is provided, comprising the above display panel.

[0043] By applying the technical solution of the present invention, the charge generation layer includes an N-type charge generation layer (NCGL), an intermediate layer and a P-type charge generation layer (PCGL). Introducing the intermediate layer between the NCGL and PCGL device structures can prevent the N-type dopant and the P-type dopant from diffusing with each other, prevent the N-type dopant from directly contacting with the P-type dopant to react and destroy the interface, thereby improving the interface stability. The intermediate layer has the performance of transmitting electrons and / or holes, which can reduce the driving voltage of the device and improve the device efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] The drawings constituting a part of the present application are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0045] Figure 1 A schematic structural diagram of an organic light-emitting device according to an embodiment of the present invention is shown.

[0046] The above drawings include the following reference numerals:

[0047] 1. Anode;

[0048] 2. Hole injection layer;

[0049] 31, first light-emitting unit; 311, first hole transport layer; 312, first light-emitting layer; 313, first hole blocking layer; 314, first electron transport layer; 32, second light-emitting unit; 321, second hole transport layer; 322, second light-emitting layer; 323, second hole blocking layer; 324, second electron transport layer;

[0050] 4. Charge generation layer; 41. N-type charge generation layer; 42. Intermediate layer; 43. P-type charge generation layer;

[0051] 5. Electron injection layer;

[0052] 6. Cathode;

[0053] 7. Capping layer. DETAILED DESCRIPTION

[0054] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0055] It should be noted that the highest occupied molecular orbital (HOMO) energy level value and the lowest unoccupied molecular orbital energy level value (LUMO) mentioned in this article can be calculated by Gaussian software. In this article, the larger the absolute value of the "HOMO" and "LUMO" energy level values, the deeper the energy level.

[0056] It should be noted that the electron mobility mentioned in the present invention can be measured by a space-confined current method.

[0057] As described in the background art, the organic light-emitting devices in the prior art have the problems of high driving voltage, low efficiency and poor device stability. In order to solve the above problems, Figure 1 As shown, the present invention provides an organic light-emitting device, comprising a stacked anode 1, at least two light-emitting units and a cathode 6, adjacent light-emitting units are connected through a charge generation layer 4, and the charge generation layer comprises a stacked N-type charge generation layer 41, an intermediate layer 42 and a P-type charge generation layer 43;

[0058] The N-type charge generation layer 41 includes a first electron transport type organic material and an N-type dopant;

[0059] The P-type charge generation layer 43 includes a first hole transport type organic material and a P-type dopant;

[0060] The intermediate layer 42 has the property of transporting electrons and / or holes.

[0061] In order to reduce the device driving voltage, improve the device efficiency and improve the device stability, the present invention provides an organic light-emitting device, wherein the charge generation layer 4 includes an N-type charge generation layer (NCGL) 41, an intermediate layer 42 and a P-type charge generation layer (PCGL) 43. The intermediate layer 42 is introduced between the NCGL and PCGL device structures to prevent the N-type dopant and the P-type dopant from diffusing with each other, prevent the N-type dopant and the P-type dopant from directly contacting and reacting to destroy the interface, thereby improving the interface stability. The intermediate layer 42 has the performance of transmitting electrons and / or holes, thereby reducing the device driving voltage and improving the device efficiency.

[0062] In some embodiments, the intermediate layer 42 includes a first material, and the first material is a second electron transport type organic material and / or a second hole transport type organic material. Due to the difference in conductivity type, the main material for the N-type doped layer is different from the main material for the P-type doped layer. Some organic materials can be used as the main material of the N-type doped organic layer, and these materials can support the transmission of electrons. Some organic materials can be used as the main material of the P-type doped organic layer, and these materials can support the transmission of holes. In conventional OLED devices, the electron transport type organic material used represents a class of main materials that can be used for the N-type doped organic layer, for example, it can be a metal chelated oxine compound, such as tris (8-hydroxyquinoline) aluminum, or it can be a triazine, a hydroxyquinoline derivative, an indole derivative, or a silacyclopentene derivative. The hole transport type organic material used represents a class of main materials that can be used for the P-type doped organic layer, for example, an aromatic tertiary amine having at least one trivalent nitrogen atom bonded only to a carbon atom, such as a monoaromatic amine, a diaromatic amine, a triaromatic amine, or a polyaromatic amine. The middle layer 42 is made of electron transport organic material and / or hole transport organic material, which can prevent the N-type dopant and the P-type dopant from directly contacting and reacting to destroy the interface, thereby improving the interface stability. The middle layer 42 has electron transport or hole transport performance, which reduces the driving voltage of the device and improves the device efficiency.

[0063] In some embodiments, the first material includes a second electron transport type organic material and a second hole transport type organic material, wherein an N-type charge generation layer 41, a second electron transport type organic material, a second hole transport type organic material, and a P-type charge generation layer 43 are stacked in sequence. The intermediate layer 42 uses the first electron transport type organic material and the first hole transport type organic material to be stacked in sequence, which not only has good electron transport or hole transport performance, reduces the driving voltage of the device, and improves the efficiency of the device, but also uses the same type of organic material as the main material of the adjacent NCGL film layer and the main material of the adjacent PCGL film layer as the intermediate layer 42, which can improve the interface stability.

[0064] In order to further reduce the driving voltage of the device and improve the efficiency of the device, in some embodiments, the first electron transport material and the second electron transport material are the same material.

[0065] In order to further reduce the driving voltage of the device and improve the efficiency of the device, in some embodiments, the first hole transport type organic material and the second hole transport type organic material are the same material.

[0066] In some embodiments, the intermediate layer 42 is a metal thin layer. The intermediate layer 42 is a metal thin layer, which has good electron transmission performance, reduces the driving voltage of the device, and improves the efficiency of the device. The intermediate layer 42 can specifically include Ti, Zr, Nb, Ta, Cr, Mo, W, Re, Fe, Ru, Os, Co, Rh, Ir, Ni, Pd, Pt, Cu, Ag, Au, Zn, Al, In, Sn or their alloys.

[0067] The thickness of the intermediate layer 42 affects the driving voltage of the device, and affects its film forming effect and thus the stability of the device. In order to obtain a lower driving voltage and a higher device stability, further, in some embodiments, the thickness of the intermediate layer 42 is

[0069] In some embodiments, the thickness of the N-type charge generation layer 41 is The thickness of the P-type charge generation layer 43 is

[0071] In conventional OLED devices, the N-type dopant used for the N-type charge generation layer can be an alkali metal, an alkali metal compound, an alkaline earth metal, an alkaline earth metal compound, for example, Li, Na, K, Rb, Cs, Mg, Mg, Ca, Sr, Ba, La, Ce, Sm, Eu, Tb, Dy, Yb or their inorganic or organic compounds, and the N-type dopant of the N-type charge generation layer can also be an organic reducing agent with strong electron donating properties, for example, bis(ethylenedisulfide)-tetrathiafulvalene, tetrathiafulvalene or their derivatives.

[0072] In some embodiments, the doping amount of the N-type dopant in the N-type charge generation layer 41 is 1% to 6% by weight, which is beneficial to the generation of carriers in the charge generation layer.

[0073] In conventional OLED devices, the P-type dopant used for the P-type charge generation layer is an oxidant with strong electron-withdrawing properties, for example, 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinone (F4-TCNQ) or other TCNQ derivatives, for example, inorganic oxidants such as iodine, FeCl3, FeF3, SbC 15 Or some other metal halide.

[0074] In some embodiments, the doping amount of the P-type dopant in the P-type charge generation layer 43 is 3% to 12% by weight, which is beneficial to the generation of carriers in the charge generation layer.

[0075] In some embodiments, the energy level difference between the HOMO energy level of the first hole transport type organic material and the LUMO energy level of the first electron transport type organic material is ≤0.8ev. The HOMO energy level of the first hole transport type organic material as the main material of the N-type charge generation layer 41 and the LUMO energy level difference of the first electron transport type organic material as the main material of the P-type charge generation layer 43 are controlled to improve the matching degree between the two, so that the charge generation and migration have a better balance, and a charge generation layer with a larger current can be formed under a certain voltage, which effectively reduces the driving voltage of the device, and can effectively reduce power loss and improve device efficiency while achieving an increase in luminous brightness and current efficiency.

[0076] In some embodiments, the light-emitting unit further includes an organic light-emitting layer and an electron transport layer, the electron transport layer is located between the organic light-emitting layer and the N-type charge transport layer or between the organic light-emitting layer and the cathode, and the energy level difference between the LUMO energy level of the first electron transport type organic material and the LUMO energy level of the electron transport layer is ≤0.5eV. It is defined that the energy level difference between the LUMO energy level of the first hole transport type organic material, which is the main material of the N-type charge transport layer, and the LUMO energy level of the electron transport layer is within the above range, so as to facilitate better injection of electrons into the electron transport layer after separation and reduce the operating voltage of the device.

[0077] In some embodiments, the first electron transport type organic material is selected from the structure shown in formula (I):

[0078]

[0079] Wherein, X, Y, Z are independently selected from one of C or N, and at least one of X, Y, Z is N; R1 is selected from at least one of H, phenyl, pyridyl, and pyridylphenyl; Ar is selected from substituted or unsubstituted phenyl, anthracene, phenanthrenyl, pyrenyl, triphenylene, pyridyl, o-phenanthroline, naphthoxazolyl, naphthoimidazolyl, and naphthothiazolyl, wherein the substituent used for substitution is at least one of -CN, phenyl, and o-phenanthroline; the phenanthroline connected with the above-mentioned N aromatic ring is used as the main structure, and the substituent is limited to obtain a material with good electron transport performance, which is used for the intermediate layer material, so that the charge migration and injection have a good balance, and a charge generation layer with a large current can be formed under a certain voltage, which effectively reduces the driving voltage of the device, and while achieving an increase in luminous brightness and current efficiency, it can effectively reduce power loss and improve device efficiency, and can effectively block the diffusion of dopants and improve device stability; preferably Ar is selected from -CN, phenyl, at least one substituted or unsubstituted phenyl selected from the group consisting of o-phenanthroline, -CN, phenyl, at least one substituted or unsubstituted anthracenyl selected from the group consisting of o-phenanthroline, -CN, phenyl, at least one substituted or unsubstituted phenanthrenyl selected from the group consisting of o-phenanthroline, -CN, phenyl, at least one substituted or unsubstituted pyrenyl selected from the group consisting of o-phenanthroline, -CN, phenyl, at least one substituted or unsubstituted triphenylene selected from the group consisting of o-phenanthroline, -CN, phenyl, at least one substituted or unsubstituted pyridyl selected from the group consisting of o-phenanthroline, -CN, phenyl, at least one substituted or unsubstituted o-phenanthroline selected from the group consisting of o-phenanthroline, -CN, phenyl, at least one substituted or unsubstituted naphthoxazolyl selected from the group consisting of o-phenanthroline, -CN, phenyl, at least one substituted or unsubstituted naphthoimidazolyl selected from the group consisting of o-phenanthroline, -CN, phenyl, at least one substituted or unsubstituted naphthiazolyl selected from the group consisting of o-phenanthroline; more preferably, the first electron transport type organic material is selected from at least one of the following structures:

[0080]

[0081]

[0082] In some embodiments, the first hole transport type organic material is selected from at least one of the following structures:

[0083]

[0084]

[0085]

[0086]

[0087]

[0088] For devices such as automotive devices that have high requirements for component life, OLEDs have high requirements for low energy consumption and low voltage.

[0089] Specifically, in some embodiments, a hole blocking layer is further included between the organic light-emitting layer and the electron transport layer, and the energy level difference between the LUMO energy level of the hole blocking layer and the LUMO energy level of the electron transport layer is greater than 0.5 eV and less than 1.0 eV. The large LUMO energy level difference between the hole blocking layer material and the electron transport layer can effectively control the injection of electrons into the light-emitting layer, and construct a multi-hole system of the light-emitting layer (EML) to improve the high-temperature stability and life of the device, which is of great significance for vehicles and other devices with high life requirements.

[0090] Preferably, the electron mobility of the hole blocking layer is lower than that of the electron transport layer. The lower electron mobility of the hole blocking layer and the higher mobility of the electron transport layer can effectively control the electron injection into the light-emitting layer, thereby improving the high temperature stability and life of the device.

[0091] Preferably, the electron mobility of the hole blocking layer is 1.0 -9 ~1.0 -8 cm 2 / Vs. The lower mobility of the hole blocking layer can improve the high temperature stability and life of the device.

[0092] Preferably, the hole blocking layer comprises a triazine bipolar electron transport material having at least one of a triarylamine group, a carbazole group, and a phenoloxazine group. The triazine bipolar electron transport material of the above-mentioned HB material with shallow LUMO and slow transmission can effectively control the electron injection into the light-emitting layer.

[0093] Preferably, the triazine bipolar electron transport material is selected from at least one of the structures shown in Formula III and Formula IV:

[0094]

[0095] Wherein, R1' is selected from one of substituted or unsubstituted phenyl, naphthyl, and dibenzofuran, and the substituent is an aromatic group, and the aromatic group is selected from one of phenyl, biphenyl, and dibenzofuran;

[0096] R2' and R3' are independently selected from one of an alkyl group and a phenyl group, or R2' and R3' are independently selected from one of an alkylene group and a phenylene group, and R2' and R3' and Si connected to the two together form a five-membered ring;

[0097] m is selected from a single bond or a phenylene group;

[0098] n1 is a single bond, a S atom or an O atom;

[0099] R4' is selected from one of substituted or unsubstituted phenyl, naphthyl, and dibenzofuran, the substituted substituent is an aromatic group, and the aromatic group is selected from one of phenyl, biphenyl, and dibenzofuran;

[0100] R5' and R6' are independently selected from one of an alkyl group and a phenyl group, or R2' and R3' are independently selected from one of an alkylene group and a phenylene group, and R5' and R6' and Si connected to the two together form a five-membered ring;

[0101] n2 is selected from a single bond, a S atom or an O atom.

[0102] Preferably, the triazine bipolar electron transport material is selected from at least one of the following structures:

[0103]

[0104] The use of the above triazine bipolar electron transport material can effectively control the electron injection into the light-emitting layer and has a suitable LUMO energy level, and can meet the energy level matching requirements with common electron transport layer materials on the market and the matching degree is good.

[0105] For mobile phones, tablets and other devices that have high requirements for reducing energy consumption, OLEDs have high requirements for low energy consumption and low voltage.

[0106] Specifically, in some embodiments, a hole blocking layer is further included between the organic light-emitting layer and the electron transport layer, and the energy level difference between the LUMO energy level of the hole blocking layer and the LUMO energy level of the electron transport layer is ≤0.4 eV. By using a smaller LUMO difference between the hole blocking layer material and the electron transport layer material, an EML multi-electron system is constructed to reduce the voltage of the device and improve efficiency, which is of great significance for devices such as mobile phones and tablets that have high requirements for reducing energy consumption.

[0107] Preferably, the electron mobility of the hole blocking layer is 1.0 -7 ~1.0 -6 cm 2 / Vs. The higher mobility of the hole blocking layer accelerates the injection of electrons into the light-emitting layer, which is beneficial to reducing the voltage of the device and improving the efficiency.

[0108] Preferably, the hole blocking layer comprises a triazine-based strong electron transport material, and the structure of the triazine-based strong electron transport material is as follows:

[0109]

[0110] A is selected from one of substituted or unsubstituted phenyl, biphenyl, naphthyl, anthracenyl, phenanthrenyl, triphenylene, azaphenanthrenyl, 9,9-dimethylacridinyl, dibenzofuranyl, and dibenzothienyl, and the substituted substituent is at least one of phenyl, naphthyl, pyridyl, pyridylphenyl, and quinolyl; R1" is selected from substituted or unsubstituted dibenzofuranyl and dibenzothienyl, and the substituted substituent is at least one of alkyl, phenyl, and phenylene; R2" and R3" are independently selected from one of alkyl and phenyl, or R2" and R3" are independently selected from one of alkylene and phenyl, and R2" and R3" and Si connected to the two form a five-membered ring. The hole blocking material uses a triazine-type strong electron transport material with a deep LUMO and fast transmission having the above structure, which can accelerate electron injection and luminescence, reduce the voltage of the device, and improve efficiency.

[0111] Preferably, the triazine strong electron transport material is selected from at least one of the following structures:

[0112]

[0113] The above triazine-based strong electron transport material has excellent electron transport properties and a suitable LUMO energy level, and can meet the energy level matching requirements with common electron transport layer materials on the market and the matching degree is relatively good.

[0114] In some embodiments, the electron transport layer material is selected from 2,8-bis(diphenylphosphinyl)dibenzothiophene (PPT), 1,3,5-tri(1-phenyl-1H-benzimidazol-2-yl)benzene (TPBi), 2,8-bis(diphenylphosphinyl)dibenzofuran (PPF), bis(2-diphenylphosphinyl)diphenyl ether (DPEPO), lithium fluoride (LiF), 4,6-bis(3,5-di(3-pyridyl)phenyl)-2-methylpyrimidine (B3PYMPM), 4,7-diphenyl-1,10-phenanthroline (Bphen), 1,3,5-tris[(3-pyridyl)-3-phenyl]benzene ( TmPyBP), 1,3,5-tris(p-pyridin-3-yl-phenyl)benzene (TpPyPB), tris[2,4,6-trimethyl-3-(3-pyridinyl)phenyl]borane (3TPYMB), 1,3-bis(3,5-bipyridin-3-ylphenyl)benzene (B3PYPB), 1,3-bis[3,5-bi(pyridin-3-yl)phenyl]benzene (BMPYPHB), 2,4,6-tris(biphenyl-3-yl)-1,3,5-triazine (T2T), diphenylbis[4-(pyridin-3-yl)phenyl]silane (DPPS), bis(2-methyl-8-hydroxyquinoline-N1,O8)-( 1,1'-biphenyl-4-hydroxy)aluminum (BAlq), 8-hydroxyquinoline-lithium (Liq), tris(8-hydroxyquinoline)aluminum (Alq3), 2-biphenyl-4-yl-5-(4-tert-butylphenyl)-1,3,4-triazole (PBD), spiro-PBD, 2,9-bis(naphthalene-2-yl)4,7-diphenyl-1,10-phenanthroline (NBphen), 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP), 3-(4-biphenyl)-4-phenyl-5-tert-butylphenyl-1,2,4-triazole (TAZ), 4-(naphthalene-1-yl)-3,5-diphenyl-4 At least one of H-1,2,4-triazole (NTAZ), 2,4,6-tris(3'-(pyridin-3-yl)biphenyl-3-yl)1,3,5-triazine (TmPPPyTz), poly[9,9-bis(3'-(N,N-dimethyl)-N-ethylammonium)-propyl)-2,7-fluorene]-alternating-2,7-(9,9-dioctylfluorene)] (PFNBr), tris(phenylquinoxaline) (TPQ), TSPO1, 2-[4-(9,10-di-2-naphthalene-2-yl-2-anthracen-2-yl)phenyl]-1-phenyl-1H-benzimidazole (ZADN), but not limited to the above materials.

[0115] In some embodiments, the N-type dopant can be selected from alkali metals, alkaline earth metals, rare earth metals or their compounds, for example, lithium (Li), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), magnesium (Mg), calcium (Ca), ytterbium (Yb), Cs2CO3, etc.

[0116] In some embodiments, the P-type dopant is selected from at least one of the following structures:

[0117]

[0118]

[0119] But it is not limited to the above materials.

[0120] In some embodiments, a cap layer 7 is disposed on the upper surface of the cathode 6 , and the cap layer 7 covers the cathode 6 to reduce light loss of the device.

[0121] In some embodiments, the material of the anode 1 can be selected from metals such as copper, gold, silver, iron, chromium, nickel, manganese, palladium, platinum or alloys thereof, or metal oxides such as indium oxide, zinc oxide, indium tin oxide (ITO), indium zinc oxide (IZO), etc., or conductive polymers such as polyaniline, polypyrrole, poly (3-methylthiophene), etc. In addition, the material of the anode 1 can also be selected from materials other than the materials listed above that facilitate hole injection and combinations thereof, including known materials suitable for the anode 1.

[0122] In some embodiments, the material of the cathode can be selected from metals such as aluminum, magnesium, silver, calcium, indium, tin, titanium, etc. or alloys thereof, and can also be selected from multilayer metal materials such as LiF / Al, LiO2 / Al, BaF2 / Al, etc. In addition to the materials listed above, the material of the cathode can also be a material that facilitates electron injection and a combination thereof, including known materials suitable for the cathode.

[0123] In some embodiments, the organic light-emitting device further includes a hole injection layer 2 and an electron injection layer 5, and each light-emitting unit includes a stacked hole transport layer, a light-emitting layer, a hole blocking layer and an electron transport layer.

[0124] In some embodiments, the hole injection layer 2 and the hole transport layer may independently include 4,4'4"-tris(3-methylphenylamino)triphenylamine (MTDATA), 4,4',4"-tris(N,N-diphenyl-amino)triphenylamine (NATA), 4,4',4"-tris(N-(naphthalene-1-yl)-N-phenyl-amino)triphenylamine (1T-NATA), 4,4',4"-tris(N-(naphthalene-2-yl)-N-phenyl-amino)triphenylamine (2TNATA), copper phthalocyanine (CuPc), 1,3,5-tris[4-(diphenylamino)phenyl]benzene (TDAPB), 2,2'-dimethyl-N,N'-di-1-naphthyl-N,N'-diphenyl[1,1'-biphenyl]-4, 4'-diamine (α-NPD), 4,4',4"-tri(carbazole-9-yl)triphenylamine (TCTA), 1,3-dicarbazole-9-ylbenzene (mCP), 4,4'-di(9-carbazole)biphenyl (CBP), 3,3'-di(N-carbazolyl)-1,1'-biphenyl (mCBP), 2,3,6,7,10,11-hexacyano-1,4,5,8,9,12-hexaazatriphenylene (HATCN), 4,4'-cyclohexylbis[N,N-di(4-methylphenyl)aniline (TAPC), N,N'-diphenyl-N,N'-(1-naphthyl)-1,1'-biphenyl-4,4'-diamine (α-NPB), N,N'-di(naphthalene-2-yl)-N,N'-di(phenyl)-1,1'-biphenyl-4,4'-diamine ) biphenyl-4,4'-diamine (NPB), poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid (PEDOT:PSS), 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4TCNQ), N-(biphenyl-4-yl)-9,9-dimethyl-N-(4-(9-phenyl-9H-carbazole-3-yl)phenyl)-9H-fluorene-2-amine polyvinylcarbazole (PVK), 4,4'-bis(N-carbazolyl)-1,1'-biphenyl (CBP), poly[N,N'-bis(4-butylphenyl)-N,N'-bis(phenyl)-benzidine] (poly-TPD), poly[(9,9-dioctylfluorenyl-2,7-diyl)-co-(4,4'-(N-(4-sec- 1,1-bis[4-(N,N'-di(p-tolyl)amino)phenyl)cyclohexane (TAPC), 3,5-bis(9H-carbazole-9-yl)-N,N-diphenylaniline (DCDPA), N-(biphenyl-4-yl)-9,9-dimethyl-N-(4-(9-phenyl-9H-carbazole-3-yl)phenyl)-9H-fluoren-2-amine, N-(biphenyl-4-yl)-N-(4-(9-phenyl-9H-carbazole-3-yl)phenyl)biphenyl-4-amine, N-([1,1'-biphenyl]-4-yl)-9,9-dimethyl-N-(4-(9-phenyl-9H-carbazole-3-yl)phenyl)-9H-fluoren-2-amine, N4,At least one of N4, N4', N4'-tetrakis([1,1'-biphenyl]-4-yl)-[1,1'-biphenyl]-4,4'-diamine) 9-phenyl-3,9-bicarbazole (CCP), molybdenum trioxide (MoO3), but not limited to the above materials.

[0125] In some embodiments, the electron injection layer 5 may include at least one of Yb, Li, Cs, and Cs2CO3, but is not limited to the above materials.

[0126] In some embodiments, the light-emitting layer includes a main material and a doping material, the main material includes a red light main material, a green light main material, and a blue light main material, the doping material includes a red light doping material, a green light doping material, and a blue light doping material, and the specific doping material can be selected from at least one of a fluorescent material, a phosphorescent material, a thermally activated delayed fluorescent material, and an induced luminescent material; the specific main material can be selected from 2,8-bis(diphenylphosphinyl)dibenzothiophene, 4,4'-bis(9-carbazole)biphenyl, 3,3'-bis(N-carbazolyl)-1,1'-biphenyl, 2,8-bis(diphenylphosphinoyl)dibenzofuran, bis(4-(9H-carbazolyl-9-yl)phenyl)diphenylsilane, 9-(4-tert-butylphenyl)-3,6-bis(triphenylsilyl)- )-9H-carbazole, bis(2-diphenylphosphine oxide)diphenyl ether, 1,3-bis[3,5-di(pyridin-3-yl)phenyl]benzene, 4,6-bis(3,5-di(3-pyridinyl)phenyl)-2-methylpyrimidine, 9-(3-(9H-carbazyl-9-yl)phenyl)-9H-carbazole-3-cyano, 9-phenyl-9-[4-(triphenylsilyl)phenyl]-9H-fluorene, 1,3,5-tri(1-phenyl-1H-benzimidazol-2-yl)benzene, diphenyl[4-(triphenylsilyl)phenyl]phosphine oxide, 4,4',4"-tri(carbazole-9-yl)triphenylamine, 2,6-dicarbazole-1,5-pyridine, polyvinylcarbazole and polyfluorene at least one of the above materials, but are not limited to the above materials.

[0127] Based on the same inventive concept, the present invention provides a display panel, including the above organic light emitting device. The implementation principle and beneficial effects thereof are similar and will not be described in detail here.

[0128] Furthermore, in some embodiments, the display panel may be a flexible panel, a curved panel, etc.

[0129] Based on the same inventive concept, the present invention provides a display device, including the above display panel. The implementation principle and beneficial effects thereof are similar and will not be described in detail here.

[0130] The present application is further described in detail below in conjunction with specific embodiments. These embodiments should not be construed as limiting the scope of protection claimed in the present application.

[0131] Example 1

[0132] A stacked OLED device comprises a stacked anode 1, at least two light-emitting units (a first light-emitting unit 31 and a second light-emitting unit 32) and a cathode 6, wherein the two light-emitting units are connected via a charge generation layer 4. Specifically, the stacked OLED device comprises the following structures arranged in sequence from bottom to top: an anode 1, a hole injection layer 2, a first hole transport layer 311, a first light-emitting layer 312, a first hole blocking layer 313, a first electron transport layer 314, an N-type charge generation layer 41, an intermediate layer 42, a P-type charge generation layer 43, a second hole transport layer 321, a second light-emitting layer 322, a second hole blocking layer 323, a second electron transport layer 324, an electron injection layer 5, a cathode 6 (magnesium silver electrode) and a capping layer 7.

[0133] The method for preparing the Tandem OLED device includes:

[0134] Step 1: Cut the glass substrate into a size of 50 mm × 50 mm × 0.7 mm, ultrasonically treat in isopropanol and deionized water for 30 min respectively, and then expose to ozone for cleaning for 10 min; install the glass substrate with ITO obtained by magnetron sputtering on a vacuum deposition device as an anode;

[0135] Step 2: Preparation of hole injection layer: Under vacuum degree of 2×10 -6 Under Pa, compounds PCGL and PD were vacuum evaporated on the ITO anode layer, wherein PCGL was used as the main material, PD was used as the doping material, the mass ratio of PCGL to PD was 96:4, and the thickness was 10 nm, as a hole injection layer;

[0136] Step 3: Prepare the first hole transport layer: vacuum evaporate the compound PCGL on the hole injection layer as the first hole transport layer with a thickness of 20 nm;

[0137] Step 4: vacuum evaporating a first light-emitting layer on the first hole transport layer, wherein the organic compound BH is used as a main material, BD is used as a doping material, the mass ratio of BH to BD is 98:2, and the thickness of the first light-emitting layer is 20 nm;

[0138] Step 5, preparing a first hole blocking layer: vacuum evaporating compound HB on the first light-emitting layer as the first hole blocking layer with a thickness of 5 nm;

[0139] Step 6: vacuum evaporating compounds ET and Alq3 on the first hole blocking layer as a first electron transport layer, the mass ratio of ET to Alq3 is 1:1, and the thickness is 10 nm;

[0140] Step 7: vacuum evaporate an N-type charge generation layer on the first electron transport layer. The main material is NCGL I-1, the N-type dopant is Yb, the mass ratio of NCGL to Yb is 96:4, and the thickness is

[0141] Step 8: Vacuum evaporate NCGL I-1 on the N-type charge generation layer to a thickness of As the middle layer;

[0142] Step 9: vacuum evaporate a P-type charge generation layer on the middle layer. The main material is PCGL, the P-type dopant is PD, the mass ratio of PCGL to PD is 90:10, and the thickness is

[0143] Step 10: vacuum evaporating compound PCGL on the P-type charge generation layer as a second hole transport layer with a thickness of 40 nm;

[0144] Step 11, vacuum evaporating a second light-emitting layer on the second hole transport layer, wherein the compound BH is used as a main material, BD is used as a doping material, the mass ratio of BH to BD is 98:2, and the thickness is 20 nm;

[0145] Step 12: vacuum-evaporating compound HB on the second light-emitting layer as a second hole blocking layer with a thickness of 5 nm;

[0146] Step 13: vacuum evaporating compounds ET and Alq3 on the second hole blocking layer as a second electron transport layer, with a mass ratio of ET to Alq3 of 1:1 and a thickness of 30 nm;

[0147] Step 14: vacuum evaporating Yb on the second electron transport layer as an electron injection layer with a thickness of 1 nm;

[0148] Step 15, vacuum evaporating a magnesium-silver electrode as a cathode on the electron injection layer, with a mass ratio of Mg to Ag being 1:9 and a thickness of 14 nm;

[0149] Step 16: vacuum evaporate compound CPL on the cathode with a thickness of 70 nm as a capping layer to obtain a Tandem OLED device.

[0150] The structures of the compounds used in Tandem OLED devices are as follows:

[0151]

[0152] Embodiment 2-10

[0153] The only difference between it and Example 1 is that the material used for the intermediate layer in step eight is different, as shown in Table 1 for details.

[0154] Embodiment 11

[0155] The only difference between this embodiment and the first embodiment is that the material used for the intermediate layer in step eight is different. The specific steps of step eight are as follows:

[0156] NCGL I-1 (thickness: ) and PCGL II-49 (thickness is ), as the middle layer.

[0157] Example 12

[0158] The only difference between it and Example 1 is that the intermediate layer in step eight is a Ti metal thin layer. The specific steps of step eight are as follows:

[0159] A thin Ti metal layer with a thickness of 1000 mm was vacuum-deposited on the N-type charge generation layer. As the middle layer.

[0160] Examples 13-15

[0161] The only difference between it and Example 1 is that in step 12, the material of the second hole blocking layer vacuum-deposited is different, as shown in Table 2 for details.

[0162] Examples 16-19

[0163] The only difference between it and Example 1 is that in step 12, the material of the second hole blocking layer vacuum-deposited is different, as shown in Table 3 for details.

[0164] Comparative Example 1

[0165] The only difference from Example 1 is that there is no intermediate layer.

[0166] Performance evaluation of OLED devices:

[0167] The current of the OLED device at different voltages was tested using a Keithley 2365A digital nanovoltmeter, and the current was then divided by the luminous area to obtain the current density of the OLED device at different voltages. The brightness and radiant energy flux density of the OLED device at different voltages were tested using a Konicaminolta CS-2000 spectroradiometer. Based on the current density and brightness of the OLED device at different voltages, the current density (10 mA / cm 2 ) and BI value (current efficiency BI, unit cd / A / CIEy); high temperature life LT95 (at 85°C, 50mA / cm 2Under test conditions), the drift voltage of the device is calculated according to the working voltage of the device before and after the high temperature life test (△V, the working voltage difference of the device before and after the life, △V = the working voltage after high temperature life - the working voltage before high temperature life, in V); taking the test values ​​of V, BI, LT95@85℃, and △V of the device in Comparative Example 1 as 100%, the ratio of the performance test values ​​of other devices to the test values ​​of the device in Comparative Example 1 is calculated, and the results are shown in Tables 1 and 2.

[0168] Table 1

[0169]

[0170]

[0171] Table 2

[0172]

[0173] Table 3

[0174]

[0175] It can be seen from Table 1 that compared with Comparative Example 1, the organic light-emitting devices prepared in Examples 1-19 have lower operating voltage, higher current efficiency, higher lifespan and device stability. The introduction of an intermediate layer between the NCGL and PCGL structures can prevent metal diffusion in the N-type dopant, and prevent the N-type dopant from directly contacting with the P-type dopant to react and destroy the interface, thereby improving the stability of the device. The introduction of the intermediate layer can effectively reduce the driving voltage of the device, while achieving an increase in luminous brightness and current efficiency, and can effectively reduce power loss and improve device efficiency.

[0176] Compared with Examples 13-15, the organic light-emitting devices prepared in Examples 16-19 have longer lifespan and device stability, and have better application prospects in equipment with high requirements for lifespan, such as in-vehicle devices.

[0177] Compared with Examples 16-19, the organic light-emitting devices prepared in Examples 13-15 have lower operating voltage and higher current efficiency, and have better application prospects in mobile phones, tablets and other devices that have high requirements for reducing energy consumption.

[0178] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. An organic light-emitting device, characterized in that: It includes a stacked anode, at least two light-emitting units and a cathode, wherein adjacent light-emitting units are connected via a charge generation layer, and the charge generation layer includes a stacked N-type charge generation layer, an intermediate layer and a P-type charge generation layer; The N-type charge generation layer includes a first electron transport type organic material and an N-type dopant; The P-type charge generation layer includes a first hole transport type organic material and a P-type dopant; The intermediate layer has the property of transporting electrons and / or holes.

2. The organic light-emitting device according to claim 1, characterized in that: The intermediate layer includes a first material, and the first material is a second electron transport type organic material and / or a second hole transport type organic material.

3. The organic light-emitting device according to claim 2, characterized in that: The first material includes the second electron transport type organic material and the second hole transport type organic material, wherein the N-type charge generation layer, the second electron transport type organic material, the second hole transport type organic material, and the P-type charge generation layer are stacked in sequence.

4. The organic light-emitting device according to claim 2, characterized in that: The first electron transport type material and the second electron transport type material are the same material, and / or the first hole transport type organic material and the second hole transport type organic material are the same material.

5. The organic light-emitting device according to claim 1, characterized in that: The intermediate layer is a metal thin layer.

6. The organic light-emitting device according to claim 1, characterized in that: The thickness of the intermediate layer is 7. The organic light-emitting device according to claim 1, characterized in that: An energy level difference between a HOMO energy level of the first hole transport type organic material and a LUMO energy level of the first electron transport type organic material is ≤0.8 eV.

8. The organic light-emitting device according to claim 7, characterized in that: The light-emitting unit also includes an organic light-emitting layer and an electron transport layer, the electron transport layer is located between the organic light-emitting layer and the N-type charge transport layer or between the organic light-emitting layer and the cathode, and the energy level difference between the LUMO energy level of the first electron transport type organic material and the LUMO energy level of the electron transport layer is ≤0.5eV.

9. The organic light emitting device according to claim 8, characterized in that: The first electron transport type organic material is selected from the structure shown in formula (I): Wherein, X, Y, and Z are independently selected from one of C and N, and at least one of X, Y, and Z is N; R1 is selected from at least one of H, phenyl, pyridyl, and pyridylphenyl; Ar is selected from substituted or unsubstituted phenyl, anthracenyl, phenanthrenyl, pyrene, triphenylenyl, pyridyl, o-phenanthroline, naphthoxazolyl, naphthoimidazolyl, naphthothiazolyl, wherein the substituent is at least one of -CN, phenyl, and o-phenanthroline.

10. The organic light emitting device according to claim 8, characterized in that: A hole blocking layer is further included between the organic light-emitting layer and the electron transport layer, and the energy level difference between the LUMO energy level of the hole blocking layer and the LUMO energy level of the electron transport layer is greater than 0.5 eV and not greater than 1.0 eV.

11. The organic light emitting device according to claim 10, characterized in that: The electron mobility of the hole blocking layer is smaller than the electron mobility of the electron transport layer.

12. The organic light emitting device according to claim 11, characterized in that: The electron mobility of the hole blocking layer is 1.0 -9 ~1.0 -8 cm 2 / Vs.

13. The organic light emitting device according to claim 11, characterized in that: The hole blocking layer comprises a triazine-based bipolar electron transport material having at least one of a triarylamine group, a carbazole group and a phenoloxazine group.

14. The organic light emitting device according to claim 13, characterized in that: The triazine bipolar electron transport material is selected from at least one of the structures shown in Formula III and Formula IV: Wherein, R1' is selected from one of substituted or unsubstituted phenyl, naphthyl, and dibenzofuran, the substituent is an aromatic group, and the aromatic group is selected from one of phenyl, biphenyl, and dibenzofuran; R2' and R3' are independently selected from one of an alkyl group and a phenyl group, or R2' and R3' are independently selected from one of an alkylene group and a phenylene group, and R2' and R3' and Si connected to the two together form a five-membered ring; m is selected from a single bond or a phenylene group; n1 is a single bond, a S atom or an O atom; R4' is selected from one of substituted or unsubstituted phenyl, naphthyl, and dibenzofuran, the substituted substituent is an aromatic group, and the aromatic group is selected from one of phenyl, biphenyl, and dibenzofuran; R5' and R6' are independently selected from one of an alkyl group and a phenyl group, or R2' and R3' are independently selected from one of an alkylene group and a phenylene group, and R5' and R6' and Si connected to the two together form a five-membered ring; n2 is selected from a single bond, a S atom or an O atom.

15. The organic light emitting device according to claim 8, characterized in that: A hole blocking layer is further included between the organic light-emitting layer and the electron transport layer, and the energy level difference between the LUMO energy level of the hole blocking layer and the LUMO energy level of the electron transport layer is ≤0.4 eV.

16. The organic light emitting device according to claim 15, characterized in that: The electron mobility of the hole blocking layer is 1.0 -7 ~1.0 -6 cm 2 / Vs.

17. The organic light emitting device according to claim 16, characterized in that: The hole blocking layer includes a triazine-based strong electron transport material, and the structure of the triazine-based strong electron transport material is as follows: A is selected from one of substituted or unsubstituted phenyl, biphenyl, naphthyl, anthracenyl, phenanthrenyl, triphenylene, azaphenanthrenyl, 9,9-dimethylacridinyl, dibenzofuranyl, and dibenzothienyl, and the substituted substituent is at least one of phenyl, naphthyl, pyridyl, pyridylphenyl, and quinolyl; R1" is selected from substituted or unsubstituted dibenzofuranyl and dibenzothiophenyl, wherein the substituted substituent is at least one of an alkyl, a phenyl, and a phenylene group; R2" and R3" are independently selected from one of alkyl and phenyl groups, or R2" and R3" are independently selected from one of alkylene and phenyl groups, and R2" and R3" and Si to which they are connected together form a five-membered ring.

18. A display panel, characterized in that: An organic light-emitting device comprising any one of claims 1 to 17.

19. A display device, characterized in that: Comprising the display panel as claimed in claim 18.

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