Light-emitting device, display panel and display device

Abstract

The invention relates to a light-emitting device, a display panel and a display device. The light-emitting device comprises an anode, a cathode, a first light-emitting unit and a second light-emitting unit, wherein the first light-emitting unit and the second light-emitting unit are located between the anode and the cathode; the light-emitting device further comprises at least one charge generation layer, the charge generation layer is located between the first light-emitting unit and the second light-emitting unit, the charge generation layer comprises a P-type charge generation sub-layer and an N-type charge generation sub-layer, and the P-type charge generation sub-layer is located on the side closer to the cathode than the N-type charge generation sub-layer. Wherein the P-type charge generation sub-layer comprises a hole transport material, and a first hole injection material and a second hole injection material which are doped in the hole transport material, and the absolute value of the lowest unoccupied molecular orbital energy level of the second hole injection material is smaller than the absolute value of the lowest unoccupied molecular orbital energy level of the first hole injection material. The driving voltage of the laminated light-emitting device can be reduced, the light-emitting efficiency is improved, transverse electric leakage is improved, and the stability of the device is improved.

Description

Technical Field

[0001] The present application relates to the field of display technology, and in particular to a 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, stacked OLEDs have the problem of high driving voltage and low luminous efficiency of light-emitting devices. Therefore, the performance of stacked OLED devices still needs to be further improved. Summary of the invention

[0003] Based on this, it is necessary to provide a light-emitting device, a display panel and a display apparatus, aiming to solve the problems of high driving voltage and low luminous efficiency of the light-emitting device in the prior art stacked OLED.

[0004] In a first aspect, an embodiment of the present application provides a light-emitting device, comprising an anode and a cathode, and a first light-emitting unit and a second light-emitting unit located between the anode and the cathode;

[0005] The light emitting device further comprises at least one charge generating layer, the charge generating layer being located between the first light emitting unit and the second light emitting unit, the charge generating layer comprising a P-type charge generating sublayer and an N-type charge generating sublayer, the P-type charge generating sublayer being located on a side of the N-type charge generating sublayer close to the cathode;

[0006] Among them, the P-type charge generating sublayer includes a hole transport material, and a first hole injection material and a second hole injection material doped in the hole transport material, and the absolute value of the lowest unoccupied molecular orbital energy level of the second hole injection material is smaller than the absolute value of the lowest unoccupied molecular orbital energy level of the first hole injection material.

[0007] In a second aspect, an embodiment of the present application further provides a display panel, which includes the light-emitting device provided in the first aspect.

[0008] In a third aspect, an embodiment of the present application further provides a display device, which includes the display panel provided in the second aspect.

[0009] In some embodiments of the present application, a first hole injection material and a second hole injection material are doped in a P-type charge generation sublayer, and the absolute value of the lowest unoccupied molecular orbital energy level of the second hole injection material is less than the absolute value of the lowest unoccupied molecular orbital energy level of the first hole injection material, so that the P-type charge generation sublayer has multiple energy levels. On the one hand, the multiple energy levels of the P-type charge generation sublayer can be well matched with the energy levels of the adjacent film layers, providing more channels (multi-stage carrier separation channels) for charge migration, and the P-type charge generation sublayer also has a stronger charge separation ability, which improves the charge transfer rate between the first light-emitting unit and the second light-emitting unit, and reduces the charge lateral transfer ability of the charge generation layer, so that a smaller driving voltage is required to drive the light-emitting device, thereby improving the luminous efficiency of the light-emitting device. On the second hand, the hole transport material included in the P-type charge generation sublayer produces a stronger π-π interaction with the first hole injection material and the second hole injection material, thereby reducing the device driving voltage. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the conventional technology, the drawings required for use in the embodiments or the conventional technology descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0011] Figure 1 A first structural schematic diagram of a light-emitting device provided in some embodiments of the present application.

[0012] Figure 2 A second structural schematic diagram of a light-emitting device provided in some embodiments of the present application.

[0013] Figure 3 A third structural schematic diagram of a light-emitting device provided in some embodiments of the present application.

[0014] Figure 4 A fourth structural schematic diagram of a light-emitting device provided in some embodiments of the present application.

[0015] Figure 5 A fifth structural schematic diagram of a light-emitting device provided in some embodiments of the present application.

[0016] Figure 6 The figure is a schematic diagram of energy levels of an existing light-emitting device.

[0017] Figure 7 An energy level diagram of a light-emitting device provided in some embodiments of the present application.

[0018] Figure 8 A schematic diagram of a display panel provided for some embodiments of the present application.

[0019] Fig. 9 A schematic diagram of a display device provided in some embodiments of the present application.

[0020] Fig.10 A schematic diagram of a substrate structure selected for leakage current testing provided in some embodiments of the present application.

[0021] Reference numerals:

[0022] Display device 300; display panel 200; light emitting device 100; anode 101; cathode 102; first light emitting unit 10; second light emitting unit 20; charge generation layer 30; P-type charge generation sublayer 32; N-type charge generation sublayer 31; first intermediate sublayer 33; second intermediate sublayer 34;

[0023] The highest occupied molecular orbital energy level NCGL_HOMO of the N-type charge generation sublayer; the lowest unoccupied molecular orbital energy level NCGL_LUMO of the N-type charge generation sublayer; the highest occupied molecular orbital energy level PD1_HOMO of the first hole injection material; the lowest unoccupied molecular orbital energy level PD1_LUMO of the first hole injection material; the highest occupied molecular orbital energy level PD2_HOMO of the second hole injection material; the lowest unoccupied molecular orbital energy level PD2_LUMO of the second hole injection material; the highest occupied molecular orbital energy level HT_HOMO of the hole transport material included in the P-type charge generation sublayer; the lowest unoccupied molecular orbital energy level HT_LUMO of the hole transport material included in the P-type charge generation sublayer;

[0024] Hole injection layer 12; first hole transport layer 13; first light-emitting layer 14; first hole blocking layer 15; first electron transport layer 16; second hole transport layer 22; second light-emitting layer 23; second hole blocking layer 24; second electron transport layer 25; electron injection layer 26; capping layer 41; evaporation area 700; hollow area 800. DETAILED DESCRIPTION

[0025] In order to facilitate the understanding of the present application, the present application will be described more fully below with reference to the relevant drawings. The preferred embodiments of the present application are provided in the drawings. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present application more thorough and comprehensive.

[0026] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0027] When describing positional relationships, unless otherwise specified, when an element such as a layer, film, or substrate is referred to as being "on" another element, it can be directly on the other element or there may be intervening elements. Further, when a layer is referred to as being "under" another layer, it can be directly under or there may be one or more intervening elements. It is also understood that when a layer is referred to as being "between" two layers, it can be the only layer between the two layers or there may be one or more intervening elements.

[0028] In the case of using “including”, “having”, and “comprising” described herein, another component may be added unless a clear limiting term such as “only”, “consisting of”, etc. is used. Unless mentioned otherwise, a term in the singular form may include a plural form and should not be understood as being one in number.

[0029] It should be understood that although the terms "first", "second", etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another element. For example, a first element may be referred to as a second element, and similarly, a second element may be referred to as a first element without departing from the scope of the present application.

[0030] It should also be understood that when interpreting an element, even if not explicitly described, the element is interpreted as including a range of error, which should be within the acceptable deviation range of the specific value determined by those skilled in the art. For example, "approximately", "approximately" or "substantially" can mean within one or more standard deviations, which are not limited here.

[0031] Furthermore, in the specification, the phrase “planar distribution schematic diagram” refers to a drawing when a target portion is viewed from above, and the phrase “cross-sectional schematic diagram” refers to a drawing when a section taken by vertically cutting the target portion is viewed from the side.

[0032] In addition, the drawings are not drawn to a 1:1 scale, and the relative sizes of the elements in the drawings are drawn only as examples and not necessarily according to the true scale.

[0033] 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.

[0034] As described in the background technology section, the existing stacked OLED has the problem of high driving voltage and low luminous efficiency of the light-emitting device. The inventor found that the reason for the above phenomenon is that in the stacked light-emitting device (Tandem device structure) in the prior art, the charge generation layer (CGL) layer often uses an organic material doped film layer to achieve carrier generation and separation, but in the prior art, due to the material characteristics of the charge generation layer itself and the poor matching of the energy levels of the charge generation layer and the adjacent layers, the charge generation layer in the prior art has a strong lateral charge transfer capability and a large lateral leakage current, so that a larger driving voltage is required to obtain the required brightness, which reduces the luminous efficiency of the light-emitting device.

[0035] It should be noted that the highest occupied molecular orbital energy level (HOMO energy level) and the lowest unoccupied molecular orbital energy level (LUMO energy level) 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.

[0036] It should be noted that the electron mobility mentioned in the present application can be measured by the space confinement current method.

[0037] Based on this, the inventors further studied the technical solutions of the embodiments of the present application. Specifically, the light-emitting device provided in the embodiments of the present application includes a charge generation layer, and the charge generation layer includes a P-type charge generation sublayer and an N-type charge generation sublayer, and the P-type charge generation sublayer is located on the side of the N-type charge generation sublayer close to the cathode; wherein the P-type charge generation sublayer includes a hole transport material, and a first hole injection material and a second hole injection material doped in the hole transport material, and the absolute value of the lowest unoccupied molecular orbital energy level of the second hole injection material is less than the absolute value of the lowest unoccupied molecular orbital energy level of the first hole injection material. The present application doped the first hole injection material and the second hole injection material in the P-type charge generation sublayer, and the absolute value of the lowest unoccupied molecular orbital energy level of the second hole injection material is less than the absolute value of the lowest unoccupied molecular orbital energy level of the first hole injection material, so that the P-type charge generation sublayer has multiple energy levels. On the one hand, the multiple energy levels of the P-type charge generation sublayer can be well matched with the energy levels of the adjacent film layers, providing more channels for charge migration (multi-stage carrier separation channels), and the P-type charge generation sublayer also has a stronger charge separation ability, which improves the charge transfer rate between the first light-emitting unit and the second light-emitting unit, and reduces the lateral charge transfer capacity of the charge generation layer, so that a smaller driving voltage is required to drive the light-emitting device, thereby improving the luminous efficiency of the light-emitting device. On the other hand, the hole transport material included in the P-type charge generation sublayer produces a stronger π-π interaction with the first hole injection material and the second hole injection material, thereby reducing the device driving voltage.

[0038] The above is the core idea of ​​this application. The technical solutions in the embodiments of this application will be described clearly and completely below in conjunction with the drawings in the embodiments of this application. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0039] See also Figures 1 to 5 . Figure 1 A first structural schematic diagram of a light-emitting device provided in some embodiments of the present application. Figure 2 A second structural schematic diagram of a light-emitting device provided in some embodiments of the present application. Figure 3 A third structural schematic diagram of a light-emitting device provided in some embodiments of the present application. Figure 4 A fourth structural schematic diagram of a light-emitting device provided in some embodiments of the present application. Figure 5 A fifth structural schematic diagram of a light-emitting device provided in some embodiments of the present application. Figure 1 The simple structure of the first light emitting unit and the second light emitting unit is shown in FIG. Figures 2 to 5 The detailed structure of the first light emitting unit and the second light emitting unit is illustrated by way of example, but the detailed structure of the first light emitting unit and the second light emitting unit is not limited to Figures 2 to 5 Example. Figures 2 to 5 Examples of different structures of the charge generation layer are also illustrated.

[0040] See also Figure 6 and Figure 7 . Figure 6 The figure is a schematic diagram of energy levels of an existing light-emitting device. Figure 7 An energy level diagram of a light-emitting device provided in some embodiments of the present application.

[0041] The present application provides a light emitting device 100, such as Figure 1 and Figure 2As shown, the light-emitting device 100 includes an anode 101 and a cathode 102, and a first light-emitting unit 10 and a second light-emitting unit 20 located between the anode 101 and the cathode 102; the light-emitting device 100 also includes at least one charge generation layer 30, the charge generation layer 30 is located between the first light-emitting unit 10 and the second light-emitting unit 20, the charge generation layer 30 includes a P-type charge generation sublayer 32 and an N-type charge generation sublayer 31, and the P-type charge generation sublayer 32 is located on the side of the N-type charge generation sublayer 31 close to the cathode 102; wherein the P-type charge generation sublayer 32 includes a hole transport material, and a first hole injection material and a second hole injection material doped in the hole transport material, and the absolute value of the lowest unoccupied molecular orbital energy level of the second hole injection material is less than the absolute value of the lowest unoccupied molecular orbital energy level of the first hole injection material.

[0042] For example, the charge generation layer (CGL) 30 includes a P-type charge generation sublayer (PCGL) 32 and an N-type charge generation sublayer (NCGL) 31. The P-type charge generation sublayer (PCGL) 32 can generate holes, and the N-type charge generation sublayer (NCGL) 31 can generate electrons. The charge generation layer (CGL) 30 can generate holes and electrons under the drive of the voltage loaded by the anode 101 and the cathode 102 to excite each light-emitting unit (the first light-emitting unit 10 and the second light-emitting unit 20) to emit light.

[0043] For example, in Figure 6 and Figure 7 Schematically shown are the highest occupied molecular orbital energy level (NCGL_HOMO) of the N-type charge generation sublayer 31, and the lowest unoccupied molecular orbital energy level (NCGL_LUMO) of the N-type charge generation sublayer 31. The highest occupied molecular orbital energy level (PD1_HOMO) of the first hole injection material, and the lowest unoccupied molecular orbital energy level (PD1_LUMO) of the first hole injection material. The highest occupied molecular orbital energy level (PD2_HOMO) of the second hole injection material, and the lowest unoccupied molecular orbital energy level (PD2_LUMO) of the second hole injection material. The highest occupied molecular orbital energy level (HT_HOMO) of the hole transport material included in the P-type charge generation sublayer 32, and the lowest unoccupied molecular orbital energy level (HT_LUMO) of the hole transport material included in the P-type charge generation sublayer 32. Figure 6 The P-type charge generating sublayer (PCGL) 32 only includes the first hole injection material as an example, so as to facilitate the comparison between the present application and the related art.

[0044] In the embodiment of the present application, the P-type charge generating sublayer 32 includes a hole transport material, and a first hole injection material and a second hole injection material doped in the hole transport material, and the absolute value of the lowest unoccupied molecular orbital energy level of the second hole injection material is less than the absolute value of the lowest unoccupied molecular orbital energy level of the first hole injection material. Figure 6 and Figure 7 ,like Figure 6 In the prior art shown in FIG. 1 , the energy level of the charge generation layer 30 is relatively single, and it is difficult to match the energy level of the charge generation layer 30 with the film layers of the light-emitting units on both sides. Figure 7 As shown, the present application doped the first hole injection material and the second hole injection material in the P-type charge generation sublayer 32, and the absolute value of the lowest unoccupied molecular orbital energy level of the second hole injection material is less than the absolute value of the lowest unoccupied molecular orbital energy level of the first hole injection material, so that the P-type charge generation sublayer 32 has multiple energy levels. On the one hand, the multiple energy levels of the P-type charge generation sublayer 32 can be well matched with the energy levels of the adjacent film layers, providing more channels (multi-stage carrier separation channels) for charge migration, and the P-type charge generation sublayer 32 also has a stronger charge separation ability, which improves the charge transfer rate between the first light-emitting unit 10 and the second light-emitting unit 20, so that a smaller driving voltage is required to drive the light-emitting device 100, and the luminous efficiency of the light-emitting device 100 is improved. On the second hand, the hole transport material included in the P-type charge generation sublayer 32 produces a stronger π-π interaction with the first hole injection material and the second hole injection material, thereby reducing the device driving voltage. The subsequent experimental data and analysis results of the specific embodiments 1 also prove that the embodiments of the present application have lower operating voltage and higher current efficiency, indicating that the use of the technical solution of the application can improve the performance of the device and is expected to significantly reduce the power consumption of the device.

[0045] In some embodiments, the absolute value of the lowest unoccupied molecular orbital energy level of the second hole injection material is less than or equal to 4.8 eV; and / or the absolute value of the lowest unoccupied molecular orbital energy level of the first hole injection material is greater than or equal to 4.8 eV.

[0046] For example, it has been verified by the inventors that when the absolute value of the lowest unoccupied molecular orbital energy level of the second hole injection material is less than or equal to 4.8 eV; and / or when the absolute value of the lowest unoccupied molecular orbital energy level of the first hole injection material is greater than or equal to 4.8 eV, the P-type charge generation sublayer 32 can have multiple energy levels, and the multiple energy levels of the P-type charge generation sublayer 32 can be well matched with the energy levels of the adjacent film layers on both sides.

[0047] Illustratively, the absolute value of the lowest unoccupied molecular orbital energy level of the second hole injection material is less than or equal to 4.8 eV, for example, the absolute value of the lowest unoccupied molecular orbital energy level of the second hole injection material is any one of 4.8 eV, 4.5 eV, 4.2 eV, 4.0 eV, 3.8 eV and 3.5 eV.

[0048] For example, the absolute value of the lowest unoccupied molecular orbital energy level of the first hole injection material is greater than or equal to 4.8 eV. For example, the absolute value of the lowest unoccupied molecular orbital energy level of the first hole injection material is any one of 4.8 eV, 5 eV, 5.2 eV, 5.5 eV, 5.8 eV and 6 eV.

[0049] In some embodiments, the absolute value of the difference between the lowest unoccupied molecular orbital energy level of the first hole injection material and the highest occupied molecular orbital energy level of the hole transport material is less than or equal to 0.5 eV. Avoiding excessive difference between the lowest unoccupied molecular orbital energy level of the first hole injection material and the highest occupied molecular orbital energy level of the hole transport material can help inject holes into the highest occupied molecular orbital of the hole transport material, thereby improving charge transfer capability.

[0050] For example, the absolute value of the difference between the LUMO energy level of the first hole injection material and the HOMO energy level of the hole transport material is defined as: PD1_LUMO-HT_HOMO, and the positive and negative values ​​of the difference are not limited, and the absolute value of the difference is less than or equal to 0.5 eV.

[0051] It should be noted that, in the present application, the absolute value of the difference in energy levels can be understood as: first taking the difference and then taking the absolute value.

[0052] Optionally, the absolute value of the difference between the lowest unoccupied molecular orbital energy level of the second hole injection material and the highest occupied molecular orbital energy level of the hole transport material is less than or equal to 2 eV. Avoiding excessive difference between the lowest unoccupied molecular orbital energy level of the second hole injection material and the highest occupied molecular orbital energy level of the hole transport material can help charge separation, thereby helping to increase the driving voltage.

[0053] In some embodiments, the absolute value of the highest occupied molecular orbital energy level of the hole transport material is less than or equal to 5.2 eV, which can help the P-type charge generation sublayer 32 to achieve energy level matching with other adjacent film layers.

[0054] In some embodiments, the N-type charge generation sublayer 31 includes a first electron transport material; the absolute value of the lowest unoccupied molecular orbital energy level of the N-type charge generation sublayer 31 is 1.58 eV to 2 eV, which can help inject electrons into the lowest unoccupied molecular orbital of the N-type charge generation sublayer 31, thereby improving the charge transfer capability.

[0055] In some embodiments, the mass percentage of the hole transport material is 78% to 96%.

[0056] For example, after verification by the inventor, the mass percentage of the hole transport material is 78% to 96%, which can well adjust the multiple energy levels of the P-type charge generating sublayer 32 to match the energy levels of the adjacent film layers, and well form a multi-stage carrier separation channel, thereby improving the charge transfer rate between the first light-emitting unit 10 and the second light-emitting unit 20. For example, the mass percentage of the hole transport material can be any value of 78%, 80%, 85%, 90%, 93% and 96%. In the subsequent experimental data and specific embodiments, examples are given of the specific implementation of the mass percentage of the hole transport material being 90% and 88% (the proportion of the PCGL main material), and the analysis results 1-4 can illustrate the beneficial effects of the mass percentage of the hole transport material being 78% to 96%.

[0057] In some embodiments, the mass percentage of the first hole injection material is 2% to 12%.

[0058] For example, after verification by the inventor, the mass percentage of the first hole injection material is 2% to 12%, which can well adjust the multiple energy levels of the P-type charge generating sublayer 32 to match the energy levels of the adjacent film layers, and well form a multi-stage carrier separation channel, thereby improving the charge transfer rate between the first light-emitting unit 10 and the second light-emitting unit 20. For example, the mass percentage of the first hole injection material can be any value of 2%, 5%, 7%, 8%, 10% and 12%. In the subsequent experimental data and specific embodiments, the specific implementation of the mass percentage of the first hole injection material of 6% and 4% (the proportion of PCGL doping material 1) is listed as an example, and the analysis results 1-4 can illustrate the beneficial effect of the mass percentage of the first hole injection material of 2% to 12%.

[0059] In some embodiments, the mass percentage of the second hole injection material is 1% to 10%.

[0060] For example, after verification by the inventor, the mass percentage of the second hole injection material is 1% to 10%, which can well adjust the multiple energy levels of the P-type charge generating sublayer 32 to match the energy levels of the adjacent film layers, and well form a multi-stage carrier separation channel, thereby improving the charge transfer rate between the first light-emitting unit 10 and the second light-emitting unit 20. For example, the mass percentage of the second hole injection material can be any value of 1%, 2%, 5%, 7%, 8% and 10%. In the subsequent experimental data and specific embodiments, the specific implementation of the mass percentage of the second hole injection material of 6% and 4% (the proportion of PCGL doping material 2) is listed as an example, and the analysis results 1-4 can illustrate the beneficial effect of the mass percentage of the second hole injection material of 1% to 10%.

[0061] In some embodiments, the thickness of the P-type charge generation sublayer 32 is 50 angstroms to 200 angstroms.

[0062] For example, after verification by the inventor, the thickness of the P-type charge generating sublayer 32 is 50 angstroms to 200 angstroms. The thickness of the P-type charge generating sublayer 32 is appropriate, which can avoid the thickness of the P-type charge generating sublayer 32 being too small and unable to effectively regulate the energy level, and can avoid the thickness of the P-type charge generating sublayer 32 being too large, thereby avoiding the resistance of the P-type charge generating sublayer 32 being too large. For example, the thickness of the P-type charge generating sublayer 32 can be any value of 50 angstroms, 80 angstroms, 100 angstroms, 120 angstroms, 150 angstroms, 180 angstroms and 200 angstroms. In the subsequent experimental data and specific embodiments, the specific implementation of the thickness of the P-type charge generating sublayer 32 of 100 angstroms, 110 angstroms, 114 angstroms and 120 angstroms (PCGL layer thickness) is listed as an example, and the analysis results 1-4 can illustrate the beneficial effect of the thickness of the P-type charge generating sublayer 32 being 50 angstroms to 200 angstroms.

[0063] For example, in some embodiments, such as subsequent experimental data and specific embodiments, verified by the inventors, the mass percentage of the hole transport material is 78% to 96%, the mass percentage of the first hole injection material is 2% to 12%, the mass percentage of the second hole injection material is 1% to 10%, and the thickness of the P-type charge generation sublayer 32 is 50 angstroms to 200 angstroms. When these conditions are met at the same time, the multiple energy levels of the P-type charge generation sublayer 32 can best match the energy levels of adjacent film layers, thereby better improving the charge transfer rate between the first light-emitting unit 10 and the second light-emitting unit 20, and better reducing the lateral charge transfer capability of the charge generation layer 30, thereby requiring a smaller driving voltage to drive the light-emitting device 100, thereby better improving the luminous efficiency of the light-emitting device 100.

[0064] In some embodiments, the second hole injection material includes at least one of the following A1 to A39 materials:

[0065] .

[0067] For example, although some materials and molecular formulas of the second hole injection material are listed as examples here, the material of the second hole injection material is not limited to the materials and molecular formulas of the second hole injection material listed here as examples.

[0068] In some embodiments, the first hole injection material includes a compound having Formula 1:

[0069]

[0070] wherein X and Y are identically or differently selected at each occurrence from CR"R"', NR', O, S or Se;

[0071] wherein Z1 and Z2 are selected, identically or differently, from O, S or Se at each occurrence;

[0072] R, R', R" and R'" are each identically or differently selected from the group consisting of hydrogen, deuterium, halogen, nitroso, nitro, acyl, carbonyl, carboxylic acid, ester, cyano, isocyano, SCN, OCN, SF5, borane, sulfinyl, sulfonyl, phosphino, substituted or unsubstituted alkyl having 1-20 carbon atoms, substituted or unsubstituted cycloalkyl having 3-20 ring carbon atoms, substituted or unsubstituted heteroalkyl having 1-20 carbon atoms, substituted or unsubstituted aralkyl having 7-30 carbon atoms substituted or unsubstituted alkoxy groups having 1 to 20 carbon atoms, substituted or unsubstituted aryloxy groups having 6 to 30 carbon atoms, substituted or unsubstituted alkenyl groups having 2 to 20 carbon atoms, substituted or unsubstituted alkynyl groups having 2 to 20 carbon atoms, substituted or unsubstituted aryl groups having 6 to 30 carbon atoms, substituted or unsubstituted heteroaryl groups having 3 to 30 carbon atoms, substituted or unsubstituted alkylsilyl groups having 3 to 20 carbon atoms, substituted or unsubstituted arylsilyl groups having 6 to 20 carbon atoms, and combinations thereof;

[0073] wherein each R may be the same or different, and at least one of R, R', R", and R'" is a group having at least one electron withdrawing group;

[0074] Adjacent substituents may be optionally linked to form a ring.

[0075] For example, in some embodiments, in the compound of Formula 1, wherein X and Y are identically or differently selected from CR"R"' or NR' at each occurrence, R', R" and R"' are groups having at least one electron-withdrawing group; alternatively, R, R', R" and R"' are groups having at least one electron-withdrawing group.

[0076] For example, in some embodiments, in the compound of Formula 1, wherein X and Y are identically or differently selected from O, S or Se at each occurrence, at least one of R is a group having at least one electron withdrawing group; alternatively, all R are groups having at least one electron withdrawing group.

[0077] For example, in some embodiments, in the compound of Formula 1, the Hammett constant of the electron-withdrawing group is ≥0.05, optionally ≥0.3, optionally ≥0.5.

[0078] For example, in some embodiments, in the compound of Formula 1, the electron withdrawing group is selected from the group consisting of halogen, nitroso, nitro, acyl, carbonyl, carboxylic acid, ester, cyano, isocyano, SCN, OCN, SF5, borane, sulfinyl, sulfonyl, phosphino, azaaromatic ring group, and any of the following groups substituted by one or more of halogen, nitroso, nitro, acyl, carbonyl, carboxylic acid, ester, cyano, isocyano, SCN, OCN, SF5, borane, sulfinyl, sulfonyl, phosphino, azaaromatic ring group: an alkyl group having 1-20 carbon atoms, a cycloalkyl group having 3-20 ring carbon atoms, a cycloalkyl group having 1-20 ring carbon atoms, a cycloalkyl group having 1-20 ring carbon atoms, a cycloalkyl group having 2-3 ... 20 carbon atoms, heteroalkyl groups, arylalkyl groups, alkoxy groups, aryloxy groups, alkenyl groups, alkynyl groups, aryl groups, heteroaryl groups, alkylsilyl groups, arylsilyl groups, and combinations thereof; optionally, the electron withdrawing group is selected from the group consisting of F, CF3, OCF3, SF5, SO2CF3, cyano, isocyano, SCN, OCN, pyrimidinyl, triazine, and combinations thereof.

[0079] In some embodiments, the first hole injection material includes at least one of the following B1 to B30:

[0080]

[0081]

[0082]

[0083] For example, although some materials and molecular formulas of the first hole injection material are listed as examples here, the material of the first hole injection material is not limited to the materials and molecular formulas of the first hole injection material listed as examples here.

[0084] In some embodiments, the hole transport material included in the P-type charge generation sublayer 32 includes at least one of the following C1 to C55:

[0085]

[0086]

[0087]

[0088]

[0089] In some embodiments, Figure 3 As shown, the charge generation layer 30 also includes a first intermediate sublayer 33 arranged between the P-type charge generation sublayer 32 and the N-type charge generation sublayer 31, and the first intermediate sublayer 33 includes a third hole injection material, and the absolute value of the lowest unoccupied molecular orbital energy level of the third hole injection material is smaller than the absolute value of the lowest unoccupied molecular orbital energy level of the first hole injection material.

[0090] For example, on the first hand, the first intermediate sublayer 33 is between the P-type charge generating sublayer 32 and the N-type charge generating sublayer 31, which reduces the energy gap between the P-type charge generating sublayer 32 and the N-type charge generating sublayer 31, making the electron injection transmission smoother, thereby reducing the driving voltage of the light-emitting device 100. On the second hand, the first intermediate sublayer 33 is thinner, which increases the lateral resistance of the light-emitting device (the resistance in the direction perpendicular to the thickness of the light-emitting device, or the resistance in the direction parallel to the plane where the anode is located), thereby reducing the lateral flow of charge in the light-emitting device, thereby reducing the lateral leakage current of the light-emitting device. In the subsequent experimental data and the analysis results 2 of the specific embodiment, it is also proved that the setting of adding the first intermediate sublayer 33 makes the light-emitting device have a lower operating voltage and higher current efficiency, and also achieves a smaller lateral leakage current, further improving the overall performance of the device.

[0091] For example, in some embodiments, the first intermediate sublayer 33 is a pure third hole injection material.

[0092] In some embodiments, Figure 3 As shown, the third hole injection material and the second hole injection material are the same material, which can reduce the types of material selection, thereby reducing production costs and production difficulties.

[0093] For example, in some embodiments, the first intermediate sublayer 33 is a pure second hole injection material.

[0094] In some embodiments, Figure 3 Therefore, the thickness of the first intermediate sublayer 33 is less than or equal to 10 angstroms.

[0095] For example, after verification by the inventor, if Figure 3Therefore, the thickness of the first intermediate sublayer 33 is less than or equal to 10 angstroms, which can prevent the thickness of the first intermediate sublayer 33 from being too large, thereby preventing the resistance of the charge generation layer 30 from being too large.

[0096] In some embodiments, Figure 4 or Figure 5 As shown, the N-type charge generating sublayer 31 includes a first electron transport material and an N-type dopant; the charge generating layer 30 also includes a second intermediate sublayer 34 arranged between the P-type charge generating sublayer 32 and the N-type charge generating sublayer 31, and the second intermediate sublayer 34 is arranged in contact with the N-type charge generating sublayer 31, and the material of the second intermediate sublayer 34 is a second electron transport material.

[0097] For example, Figure 4 As shown, the charge generation layer 30 of the light emitting device 100 includes an N-type charge generation sublayer 31 , a second intermediate sublayer 34 , and a P-type charge generation sublayer 32 which are sequentially stacked on the anode 101 .

[0098] For example, Figure 4 As shown, the introduction of a second intermediate sublayer 34 between the P-type charge generating sublayer 32 and the N-type charge generating sublayer 31 can prevent the diffusion of metal in the N-type dopant in the N-type charge generating sublayer 31, for example, slowing down the diffusion of ytterbium (Yb) from the N-type charge generating sublayer to the P-type charge generating sublayer, and at the same time preventing the N-type dopant in the N-type charge generating sublayer 31 from directly contacting with the P-type dopant in the P-type charge generating sublayer 32 to react and destroy the interface, thereby reducing the drift voltage of the device (testing the life of the light-emitting device at a certain temperature and current density, and the voltage difference before and after the light-emitting device is tested for the life), and improving the stability of the light-emitting device. In the subsequent experimental data and the analysis results of the specific embodiment 3, it is also proved that the setting of adding the second intermediate sublayer 34 makes the light-emitting device have a lower operating voltage and a higher current efficiency, and also achieves a smaller drift voltage, further improving the stability of the device.

[0099] For example, Figure 5 As shown, the charge generation layer 30 of the light emitting device 100 includes an N-type charge generation sublayer 31 , a second intermediate sublayer 34 , a first intermediate sublayer 33 and a P-type charge generation sublayer 32 which are sequentially stacked on the anode 101 .

[0100] For example, Figure 5As shown, the second intermediate sublayer 34 is introduced between the first intermediate sublayer 33 and the N-type charge generating sublayer 31, which can prevent the metal diffusion in the N-type dopant in the N-type charge generating sublayer 31, for example, slowing down the diffusion of ytterbium (Yb) from the N-type charge generating sublayer to the P-type charge generating sublayer, and at the same time prevent the N-type dopant in the N-type charge generating sublayer 31 from directly contacting with the P-type dopant in the P-type charge generating sublayer 32 to react and destroy the interface, thereby reducing the drift voltage of the device (testing the life of the light-emitting device at a certain temperature and current density, and the voltage difference before and after the light-emitting device is tested for the life), and improving the stability of the light-emitting device. In the subsequent experimental data and the analysis results of the specific embodiment 4, it is also proved that the setting of adding the second intermediate sublayer 34 makes the light-emitting device have a lower operating voltage and a higher current efficiency, and also achieves a smaller drift voltage and a smaller lateral leakage current, which not only reduces the power consumption of the device and reduces the lateral leakage, but also improves the stability of the device, and significantly optimizes the overall performance of the device.

[0101] For example, in some embodiments, the material of the second intermediate sublayer 34 only includes the second electron transport material.

[0102] In some embodiments, Figure 4 or Figure 5 As shown, the second electron transport material and the first electron transport material are the same material, which can reduce the types of material selection, thereby reducing production costs and production difficulties.

[0103] In some embodiments, the second intermediate sublayer 34 has a thickness of 5 angstroms to 20 angstroms.

[0104] For example, after verification by the inventor, the thickness of the second intermediate sublayer 34 is 5 angstroms to 20 angstroms. The thickness of the second intermediate sublayer 34 is appropriate, which can avoid the thickness of the second intermediate sublayer 34 being too small to effectively adjust the energy level, can avoid the thickness of the second intermediate sublayer 34 being too small to prevent the metal diffusion in the N-type dopant in the N-type charge generation sublayer 31, and can avoid the thickness of the second intermediate sublayer 34 being too large, thereby avoiding excessive resistance of the charge generation layer 30. For example, the thickness of the second intermediate sublayer 34 can be any value of 5 angstroms, 8 angstroms, 10 angstroms, 12 angstroms, 15 angstroms, 18 angstroms and 20 angstroms.

[0105] It should be noted that if Figures 2 to 5As shown, the first light-emitting unit 10 and the second light-emitting unit 20 may both include a light-emitting layer (Emission layer, EML), and the first light-emitting unit 10 and the second light-emitting unit 20 may both include other film layers besides the light-emitting layer (Emission layer, EML), for example, may also include one or more of a hole injection layer (HIL), a hole transport layer (HTL), an electron injection layer (EIL), an electron transport layer (ETL), a hole blocking layer (HBL) and an electron blocking layer (EBL).

[0106] It should be noted that if Figures 2 to 5 As shown, the light emitting device 100 (stacked OLED device) includes the following structures arranged in order from bottom to top: an anode 101, a hole injection layer 12, a first hole transport layer 13, a first light emitting layer 14, a first hole blocking layer 15, a first electron transport layer 16, a charge generation layer 30, a second hole transport layer 22, a second light emitting layer 23, a second hole blocking layer 24, a second electron transport layer 25, an electron injection layer 26, a cathode 102 and a capping layer 41. However, the structures of the first light emitting unit 10 and the second light emitting unit 20 are not limited to Figures 2 to 5 Example.

[0107] In some embodiments, a cap layer 41 is disposed on the upper surface of the cathode 102 , and the cap layer 41 covers the cathode 102 to reduce light loss of the device.

[0108] In some embodiments, the material of the anode 101 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 101 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 101.

[0109] In some embodiments, the material of cathode 102 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 cathode 102 can also be a material that facilitates electron injection and a combination thereof, including known materials suitable for cathode 102.

[0110] In some embodiments, the hole injection layer 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.

[0111] In some embodiments, the electron injection layer may include at least one of Yb, Li, Cs, and Cs2CO3, but is not limited to the above materials.

[0112] In some embodiments, the light-emitting layer (the first light-emitting layer 14 and the second light-emitting layer 23) 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, a green light doping, and a blue light doping, 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-diphenylsilane, (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, but not limited to the above materials.

[0113] See also Figure 8 and Fig. 9 , Figure 8 A schematic diagram of a display panel provided for some embodiments of the present application. Fig. 9 A schematic diagram of a display device provided in some embodiments of the present application.

[0114] The present application also provides a display panel 200, such as Figure 8 As shown, the display panel 200 includes any one of the above-mentioned light-emitting devices 100, or a light-emitting device 100 combining any of the above-mentioned features.

[0115] For example, the display panel 200 also has the beneficial effects of the light emitting device 100 in the above embodiment. The similarities can be understood by referring to the above explanation of the light emitting device 100, which will not be repeated here.

[0116] The present application also provides a display device 300, such as Fig. 9 As shown, the display device 300 includes any one of the display panels 200 described above, or the display device 300 includes a display panel 200 having any combination of the features described above.

[0117] For example, the display device 300 also has the beneficial effects of the display panel 200 or the light-emitting device 100 in the above embodiments. The similarities can be understood by referring to the above explanation of the display panel 200 or the light-emitting device 100, which will not be repeated here.

[0118] For example, the display device 300 provided in the embodiment of the present application can be Fig. 9 The mobile phone shown can also be any electronic product with a display function, including but not limited to the following categories: televisions, laptops, desktop displays, tablet computers, digital cameras, smart bracelets, smart glasses, car displays, industrial control equipment, medical display screens, touch interactive terminals, etc. The embodiments of the present application do not specifically limit this.

[0119] Experimental data and specific examples

[0120] The present application is further described in detail below in combination with experimental data and specific examples. These specific examples should not be construed as limiting the scope of protection claimed in the present application.

[0121] Example 1

[0122] A light-emitting device 100 (stacked light-emitting device) includes the following structures arranged in sequence from bottom to top: an anode 101, a hole injection layer 12, a first hole transport layer 13, a first light-emitting layer 14, a first hole blocking layer 15, a first electron transport layer 16, a charge generation layer 30, a second hole transport layer 22, a second light-emitting layer 23, a second hole blocking layer 24, a second electron transport layer 25, an electron injection layer 26, a cathode 102 and a capping layer 41.

[0123] This embodiment provides a stacked OLED, and the specific preparation steps include:

[0124] Step (1), cutting the glass substrate into a size of 50 mm×50 mm×0.7 mm, ultrasonically treating in isopropyl alcohol and deionized water for 30 min respectively, and then exposing to ozone for cleaning for 10 min; installing the glass substrate with an ITO anode obtained by magnetron sputtering on a vacuum deposition device;

[0125] Step (2), preparing a hole injection layer, vacuum evaporating compounds C54 and B10 on the ITO anode layer at a vacuum degree of 2×10-6Pa, wherein C54 is used as a main material, B10 is used as a doping material, the mass ratio of C54 to B10 is 97:3, and the thickness is 10nm, as a hole injection layer;

[0126] Step (3), preparing a first hole transport layer, vacuum evaporating compound C54 on the hole injection layer as the first hole transport layer, with a thickness of 25 nm;

[0127] Step (4), vacuum evaporating a first light-emitting layer on the first hole transport layer, using an organic compound BH-1 as a main material, BD-1 as a doping material, the mass ratio of BH-1 to BD-1 is 98:2, and the thickness of the first light-emitting layer is 20 nm;

[0128] Step (5), preparing a first hole blocking layer, vacuum evaporating compound HB-1 on the first light-emitting layer as the first hole blocking layer, with a thickness of 5 nm;

[0129] Step (6), preparing a first electron transport layer, vacuum evaporating compounds ET-1 and LiQ on the first hole blocking layer as the first electron transport layer, the mass ratio of ET-1 to LiQ is 1:1, and the thickness is 10 nm;

[0130] Step (7), preparing an N-type charge generation layer, vacuum evaporating compounds NCGL-1 and Yb on the first electron transport layer as an N-type charge generation layer, the mass ratio of NCGL-1 to Yb is 97:3, and the thickness is 12 nm;

[0131] Step (8), preparing a P-type charge generation layer, vacuum evaporating compounds C54, B10 and A5 on the N-type charge generation layer as a P-type charge generation layer, wherein C54 is used as a main material, B10 and A5 are used as doping materials, the mass ratio of C54, B10 and A5 is 90:6:4, and the thickness is 12nm;

[0132] Step (9), preparing a second hole transport layer, vacuum evaporating compound C54 on the P-type charge generation layer as the second hole transport layer, with a thickness of 45 nm;

[0133] Step (10), preparing a second light-emitting layer, vacuum evaporating the second light-emitting layer on the second hole transport layer, using compound BH-1 as the main material, BD-1 as the doping material, the mass ratio of BH-1 to BD-1 is 98:2, and the thickness is 20 nm;

[0134] Step (11), preparing a second hole blocking layer, vacuum evaporating compound HB-1 on the second light-emitting layer as the second hole blocking layer, with a thickness of 5 nm;

[0135] Step (12), preparing a second electron transport layer, vacuum evaporating compounds ET-1 and LiQ on the second hole blocking layer as the second electron transport layer, the mass ratio of ET-1 to LiQ is 1:1, and the thickness is 30 nm;

[0136] Step (13), preparing an electron injection layer, vacuum evaporating Yb on the second electron transport layer as an electron injection layer with a thickness of 1 nm;

[0137] Step (14), preparing a cathode, vacuum evaporating a magnesium-silver electrode on the electron injection layer as the cathode, the mass ratio of Mg to Ag being 1:9, and the thickness being 12 nm;

[0138] Step (15), preparing a covering layer (capping layer 41), vacuum evaporating compound CPL-1 on the cathode with a thickness of 60 nm as a covering layer, and obtaining the Tandem OLED device.

[0139] Example 2 to Example 7

[0140] The difference between this embodiment and Example 1 is that the type or proportion of the main material or doping material used in the P-type charge generation layer in step (8) is adjusted. The specific differences are shown in Table 1.

[0141] Example 8 to Example 12

[0142] The difference between it and Example 1 is that after step (7) is completed, a thin layer of PCGL doping material 2 (A5 or A7) is evaporated with a thickness of 10 angstroms or 6 angstroms, and then the type or proportion of the main material or doping material used in the P-type charge generation layer (PCGL layer) in step (8) is adjusted. The total thickness of the P-type charge generation layer and the thin layer is controlled to be 120 angstroms in the entire process. The specific differences are shown in Table 1.

[0143] Example 13 to Example 14

[0144] The difference between it and Example 1 is that after step (7), a thin layer of NCGL-1 material is evaporated with a thickness of 10 angstroms, and then the type or proportion of the main material or doping material used in the P-type charge generation layer (PCGL layer) in step (8) is adjusted. The total thickness of the P-type charge generation layer and the thin layer is controlled to be 120 angstroms in the whole process. The specific differences are shown in Table 1.

[0145] Example 15 to Example 16

[0146] The difference between it and Example 1 is that after completing step (7), a thin layer of NCGL-1 material is evaporated with a thickness of 10 angstroms, and then a thin layer of PCGL doping material 2 (A5) is evaporated with a thickness of 10 angstroms on the thin layer of NCGL-1 material, and then the type of main material used in the P-type charge generation layer (PCGL layer) in step (8) is adjusted. During the whole process, the thickness of the P-type charge generation layer and the sum of the thickness of the two thin layers are controlled to be 120 angstroms. The specific differences are shown in Table 1.

[0147] Comparative Example 1

[0148] The difference from Example 1 is that the PCGL layer in step (8) is adjusted, that is, the vacuum evaporated compounds C54 and B10 are used as the P-type charge generating layer, wherein C54 is used as the main material and B10 is used as the doping material, the mass ratio of C54 and B10 is 94:6, and the thickness is 120 angstroms. The specific differences are shown in Table 1.

[0149] Comparative Example 2

[0150] The difference from Example 1 is that the PCGL layer in step (8) is adjusted, that is, the vacuum evaporated compounds C54 and B10 are used as the P-type charge generating layer, wherein C54 is used as the main material and B10 is used as the doping material, the mass ratio of C54 and B10 is 90:10, and the thickness is 120 angstroms. The specific differences are shown in Table 1.

[0151] Comparative Example 3

[0152] The difference between it and Example 1 is that after step (7), NCGL-1 material is evaporated to a thickness of 10 angstroms, and then the PCGL layer in step (8) is adjusted, that is, vacuum evaporated compounds C54 and B10 are used as a P-type charge generating layer, wherein C54 is used as the main material and B10 is used as the doping material, the mass ratio of C54 and B10 is 90:10, and the thickness is 110 angstroms. The specific differences are shown in Table 1.

[0153] The structure of the compound used in the Tandem OLED device of the above embodiment or comparative example is as follows:

[0154]

[0155]

[0156] Table 1: Charge generation layer structures of various embodiments and comparative examples

[0157]

[0158]

[0159] It should be noted that in the above-mentioned specific embodiments and comparative examples, the PCGL main material represents the hole transport material included in the P-type charge generating sublayer; the PCGL doped material 1 represents the first hole injection material; the PCGL doped material 2 represents the second hole injection material; the NCGL-1 represents the second electron transport material; and the thin layer material represents the first intermediate sublayer, the second intermediate sublayer, or the first intermediate sublayer and the second intermediate sublayer.

[0160] It should be noted that the first intermediate sublayer is not provided in the embodiments 1 to 7. Figure 2 Specific experimental examples of examples.

[0161] It should be noted that the first intermediate sublayer is provided in Embodiments 8 to 12, that is, Embodiments 8 to 12 are Figure 3 Specific experimental examples of examples.

[0162] It should be noted that, in Example 13 and Example 14, the first intermediate sublayer is not provided, but the second intermediate sublayer is provided. Figure 4 Specific experimental examples of examples.

[0163] It should be noted that the first intermediate sublayer and the second intermediate sublayer are provided in Embodiment 15 and Embodiment 16. Figure 5 Specific experimental examples of examples.

[0164] Device performance testing

[0165] 1) Working voltage and current efficiency detection; The stacked organic light-emitting devices prepared in the embodiments and comparative examples were tested with a Keithley 2365A digital nanovoltmeter for the current of the devices of the embodiments and comparative examples at different voltages, and then the current was divided by the luminescent area to obtain the current density of the devices at different voltages; the brightness and radiant energy flux density of the devices at different voltages were tested with a Konicaminolta CS-2000 spectroradiometer; based on the current density and brightness of the devices at different voltages, the working voltage V and current efficiency BI (Cd / A / CIEy) at the same current density (10 mA / cm2) were obtained.

[0166] The working voltage detected in Comparative Example 1 is recorded as 100%. The value of the working voltage of the embodiment or the comparative example = the working voltage of the embodiment / the working voltage of Comparative Example 1×100%.

[0167] The current efficiency detected in Comparative Example 1 was recorded as 100%. The value of the current efficiency of the example or the comparative example=the current efficiency of the example or the comparative example / the current efficiency of Comparative Example 1×100%.

[0168] A lower operating voltage means that the device requires less power to operate under the same conditions. This reduces power consumption, improves energy efficiency, and extends battery life.

[0169] Current efficiency refers to the light output or other effective output that a device can produce under a given current input. High current efficiency means that the device can output more light or higher performance under the same input current.

[0170] 2) Drift voltage of the device: The high temperature life LT95 of the device is tested at 30 mA / cm2 and 85°C. The drift voltage of the device is calculated based on the working voltage of the device before and after the life LT95 (△V, the working voltage difference of the device before and after the life, △V = working voltage after the life - working voltage before the life, in V). The drift voltage of Comparative Example 1 is 100%, and the drift voltage value of the embodiment or comparative example = drift voltage of the embodiment or comparative example / drift voltage of Comparative Example 1 × 100%. The magnitude of the offset voltage reflects the stability of the device.

[0171] 3) Test of lateral leakage current: The glass substrate of the laminated electroluminescent organic light-emitting device of the above embodiment or comparative example is replaced with a substrate having Fig.10 structure( Fig.10 The substrate is prepared on a substrate having a structure diagram of a substrate selected for leakage current testing provided in some embodiments of the present application, and the local morphology of the substrate is referenced Fig.10 , wherein the pattern-filled area is the vapor deposition area 700 where each stacked electroluminescent organic light-emitting device is vapor-deposited, and the vapor deposition area 700 is a solid part; the white-filled area is the hollow area 800 of the substrate body. After the device is prepared, a voltage of -10V to +10V is applied to both sides of the two electrodes (anode and cathode), and the current of the devices of the embodiment and the comparative example at different voltages is tested using a Keithley 2365A digital nanovoltmeter, and the leakage current of the comparative example 1 at 10V is recorded as 100%, and the leakage current value of the embodiment or the comparative example (the relative size of the leakage current under the same conditions) = the leakage current of the embodiment or the comparative example / the leakage current of the comparative example 1×100%. The device performance results are obtained as shown in Table 2.

[0172] Table 2: Performance results of various embodiments and comparative examples

[0173]

[0174] Analysis result 1: According to the data of Examples 1-7 and Comparative Examples 1-2, in the light-emitting devices of Examples 1-7 ( Figure 2In the example light-emitting device), the P-type charge generating sublayer 32 includes a hole transport material, and a first hole injection material and a second hole injection material doped in the hole transport material (that is, the P-type charge generating sublayer is doped with a PCGL main material and a double hole injection material in an appropriate proportion), and embodiments 1-7 have a lower operating voltage and a higher current efficiency. This shows that the use of this solution can improve the performance of the device and is expected to significantly reduce the power consumption of the device.

[0175] Analysis result 2: Compared with Example 1, the light emitting devices of Examples 8-12 ( Figure 3 In the example light-emitting device, a first intermediate sublayer is also set (that is, the P-type charge generation sublayer is doped with PCGL main material and double hole injection material in an appropriate proportion, and a PD thin layer is added). On the basis of lower operating voltage and higher current efficiency, a smaller lateral leakage current is also achieved, further improving the overall performance of the device.

[0176] Analysis result 3, compared with Example 1, the light emitting devices of Examples 13-14 ( Figure 4 In the example light-emitting device, a second intermediate sublayer is also set (that is, the P-type charge generation sublayer is doped with PCGL main material and double hole injection material in an appropriate proportion, and an NCGL-1 thin layer is added). On the basis of lower operating voltage and higher current efficiency, a smaller drift voltage is also achieved, further improving the stability of the device.

[0177] Analysis result 4: Compared with Example 1, the light emitting devices of Examples 15-16 ( Figure 5 In the example light-emitting device, a first intermediate sublayer and a second intermediate sublayer are also provided (i.e., the P-type charge generation sublayer is doped with a PCGL main material and a double hole injection material in an appropriate proportion, and an NCGL-1 thin layer and a PD thin layer are added). On the basis of a lower operating voltage and a higher current efficiency, a smaller drift voltage and a smaller lateral leakage current are achieved, which not only reduces the power consumption of the device and reduces the lateral leakage, but also improves the stability of the device, and significantly optimizes the overall performance of the device.

[0178] Although the present invention has been described with reference to preferred embodiments, various modifications may be made thereto and parts thereof may be replaced by equivalents without departing from the scope of the present invention. In particular, the various technical features mentioned in the various embodiments may be combined in any manner as long as there are no structural conflicts. The present invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

[0179] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0180] The above-mentioned embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application shall be subject to the attached claims.

Claims

1. A light emitting device, characterized in that: comprising an anode and a cathode, and a first light emitting unit and a second light emitting unit located between the anode and the cathode; The light emitting device further comprises at least one charge generating layer, the charge generating layer being located between the first light emitting unit and the second light emitting unit, the charge generating layer comprising a P-type charge generating sublayer and an N-type charge generating sublayer, the P-type charge generating sublayer being located on a side of the N-type charge generating sublayer close to the cathode; Among them, the P-type charge generating sublayer includes a hole transport material, and a first hole injection material and a second hole injection material doped in the hole transport material, and the absolute value of the lowest unoccupied molecular orbital energy level of the second hole injection material is smaller than the absolute value of the lowest unoccupied molecular orbital energy level of the first hole injection material.

2. The light emitting device according to claim 1, characterized in that: The absolute value of the lowest unoccupied molecular orbital energy level of the second hole injection material is less than or equal to 4.8 eV; And / or, the absolute value of the lowest unoccupied molecular orbital energy level of the first hole injection material is greater than or equal to 4.8 eV.

3. The light emitting device according to claim 1, characterized in that: An absolute value of a difference between a lowest unoccupied molecular orbital energy level of the first hole injection material and a highest occupied molecular orbital energy level of the hole transport material is less than or equal to 0.5 eV.

4. The light emitting device according to claim 1, characterized in that: The absolute value of the highest occupied molecular orbital energy level of the hole transport material is less than or equal to 5.2 eV.

5. The light emitting device according to claim 1, characterized in that: The N-type charge generation sublayer includes a first electron transport material; An absolute value of the lowest unoccupied molecular orbital energy level of the N-type charge generation sublayer is 1.58 eV to 2 eV.

6. The light emitting device according to claim 1, characterized in that: The mass percentage of the hole transport material is 78% to 96%; or / and, The mass percentage of the first hole injection material is 2% to 12%; or / and, The mass percentage of the second hole injection material is 1% to 10%; or / and, The thickness of the P-type charge generating sublayer is 50 angstroms to 200 angstroms.

7. The light emitting device according to claim 1, characterized in that: The second hole injection material includes at least one of the following A1 to A39 materials:

8. The light emitting device according to claim 1, characterized in that: The first hole injection material includes a compound having the following formula 1: wherein X and Y are identically or differently selected at each occurrence from CR"R"', NR', O, S or Se; wherein Z1 and Z2 are identically or differently selected from O, S or Se at each occurrence; wherein R, R', R" and R'" are each identically or differently selected from the group consisting of hydrogen, deuterium, halogen, nitroso, nitro, acyl, carbonyl, carboxylic acid, ester, cyano, isocyano, SCN, OCN, SF5, borane, sulfinyl, sulfonyl, phosphino, substituted or unsubstituted alkyl having 1-20 carbon atoms, substituted or unsubstituted cycloalkyl having 3-20 ring carbon atoms, substituted or unsubstituted heteroalkyl having 1-20 carbon atoms, substituted or unsubstituted alkyl having 7-30 carbon atoms Aralkyl, substituted or unsubstituted alkoxy having 1 to 20 carbon atoms, substituted or unsubstituted aryloxy having 6 to 30 carbon atoms, substituted or unsubstituted alkenyl having 2 to 20 carbon atoms, substituted or unsubstituted alkynyl having 2 to 20 carbon atoms, substituted or unsubstituted aryl having 6 to 30 carbon atoms, substituted or unsubstituted heteroaryl having 3 to 30 carbon atoms, substituted or unsubstituted alkylsilyl having 3 to 20 carbon atoms, substituted or unsubstituted arylsilyl having 6 to 20 carbon atoms, and combinations thereof; wherein each R may be the same or different, and at least one of R, R', R", and R'" is a group having at least one electron withdrawing group; Adjacent substituents may be optionally linked to form a ring.

9. The light emitting device according to claim 1, characterized in that: The first hole injection material includes at least one of the following B1 to B30:

10. The light emitting device according to claim 1, characterized in that: The hole transport material included in the P-type charge generation sublayer includes at least one of the following C1 to C55:

11. The light emitting device according to claim 1, characterized in that: The charge generation layer also includes a first intermediate sublayer arranged between the P-type charge generation sublayer and the N-type charge generation sublayer, the first intermediate sublayer includes a third hole injection material, and the absolute value of the lowest unoccupied molecular orbital energy level of the third hole injection material is smaller than the absolute value of the lowest unoccupied molecular orbital energy level of the first hole injection material.

12. The light emitting device according to claim 11, characterized in that: The third hole injection material and the second hole injection material are the same material.

13. The light emitting device according to claim 11, characterized in that: The thickness of the first intermediate sublayer is less than or equal to 10 angstroms.

14. The light emitting device according to claim 1 or 11, characterized in that: The N-type charge generation sublayer includes a first electron transport material and an N-type dopant; The charge generation layer further includes a second intermediate sublayer disposed between the P-type charge generation sublayer and the N-type charge generation sublayer, the second intermediate sublayer being disposed in contact with the N-type charge generation sublayer, and a material of the second intermediate sublayer is a second electron transport material.

15. The light emitting device according to claim 14, characterized in that: The second electron transport material and the first electron transport material are the same material.

16. The light emitting device according to claim 14, characterized in that: The second intermediate sublayer has a thickness of 5 angstroms to 20 angstroms.

17. A display panel, characterized in that: The light emitting device comprises the light emitting device as claimed in any one of claims 1 to 16.

18. A display device, characterized in that: Comprising the display panel as claimed in claim 17.

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