Organic electroluminescent devices and display panels

Abstract

This invention provides an organic electroluminescent device, comprising: a first electrode, at least one light-emitting unit, and a second electrode. The at least one light-emitting unit is located above the first electrode, and the second electrode is located above the at least one light-emitting unit. The at least one light-emitting unit includes a light-emitting layer and at least one adjustment layer, which is located between the light-emitting layer and the first electrode. The adjustment layer comprises a material with molecular dipole orientation. This invention, through the adjustment layer with molecular dipole orientation, regulates the carriers, adjusting the carrier injection and transport characteristics, thereby adjusting the capacitance curve of the organic electroluminescent device and improving the image trailing problem of the organic electroluminescent device.

Description

Technical Field

[0001] This invention belongs to the field of display technology, specifically relating to an organic electroluminescent device and a display panel. Background Technology

[0002] Organic light-emitting diode (OLED) and flat panel displays based on light-emitting diode (LED) technologies are widely used in various consumer electronics products such as mobile phones, televisions, laptops, and desktop computers due to their advantages such as high image quality, energy saving, thin body and wide range of applications, becoming the mainstream of display panels.

[0003] However, the performance of current OLED display products needs to be improved. Summary of the Invention

[0004] In view of this, the embodiments of this application aim to provide an organic electroluminescent device and a display panel, which can effectively solve the ghosting problem of organic electroluminescent devices by regulating the charge carriers.

[0005] The first aspect of this application provides an organic electroluminescent device, comprising:

[0006] First electrode, At least one light-emitting unit, the at least one light-emitting unit being located above the first electrode, and The second electrode is located above the at least one light-emitting unit. Wherein, at least one of the light-emitting units includes a light-emitting layer and at least one adjustment layer, the at least one adjustment layer being located between the light-emitting layer and the first electrode, the adjustment layer comprising a material having a molecular dipole orientation.

[0007] Optionally, in some embodiments of this application, the molecular dipole moment of the material of the adjustment layer is 1 to 4 Debye; preferably, the molecular dipole moment of the material of the adjustment layer is 2 to 3 Debye.

[0008] Preferably, in some embodiments of this application, the hole mobility of the material of the adjustment layer is 4.0 × 10⁻⁶. -7 ~6.0×10 -4 cm² / (V•s).

[0009] Preferably, in some embodiments of this application, the hole mobility of the material of the adjustment layer is 5.0 × 10⁻⁶. -6 ~8.0×10 -5 cm² / (V•s).

[0010] Optionally, in some embodiments of this application, the material of the adjustment layer includes a polar hole transport material or a polar electron transport material.

[0011] Preferably, in some embodiments of this application, the material of the adjustment layer includes aromatic amine derivatives, star-shaped aromatic amines, benzene ring derivatives containing imidazole groups, phenololine derivatives, or benzene ring derivatives containing pyridine groups.

[0012] Optionally, in some embodiments of this application, the material of the adjustment layer includes at least one of the following compounds:

[0013] .

[0014] Optionally, in some embodiments of this application, the light-emitting unit further includes a hole transport region located between the light-emitting layer and the first electrode, and the adjustment layer located between the light-emitting layer and the hole transport region; or, the adjustment layer located between the hole transport region and the first electrode; or, the adjustment layer located within the hole transport region.

[0015] Preferably, in some embodiments of this application, the hole transport region includes one or more of a hole injection layer, a hole transport layer, and an electron blocking layer.

[0016] Optionally, in some embodiments of this application, the at least one light-emitting unit includes a first light-emitting unit and a second light-emitting unit stacked together, the second light-emitting unit being located on the side of the first light-emitting unit away from the first electrode, a charge-generating layer being disposed between the first light-emitting unit and the second light-emitting unit, the first light-emitting unit including a first light-emitting layer and a first adjustment layer, the second light-emitting unit including a second light-emitting layer and a second adjustment layer, the first adjustment layer being located between the first electrode and the first light-emitting layer, and the second adjustment layer being located between the charge-generating layer and the second light-emitting layer.

[0017] Optionally, in some embodiments of this application, the thickness of the adjustment layer is 1 to 15 nm.

[0018] Optionally, in some embodiments of this application, the adjustment layer is located between the hole injection layer and the hole transport layer, and the thickness of the adjustment layer is 1 to 5 nm.

[0019] Optionally, in some embodiments of this application, the adjustment layer is located between the hole transport layer and the electron blocking layer, and the thickness of the adjustment layer is 7-11 nm.

[0020] Optionally, in some embodiments of this application, the adjustment layer is located between the electron blocking layer and the light-emitting layer, and the thickness of the adjustment layer is 12-14 nm.

[0021] A second aspect of this application provides a display panel including the organic electroluminescent device described in the above embodiments.

[0022] The beneficial effects of this application are as follows: This application provides an organic electroluminescent device, comprising a first electrode stacked thereon, at least one light-emitting unit, and a second electrode. The light-emitting unit includes a light-emitting layer and at least one adjustment layer. The adjustment layer is disposed between the light-emitting layer and the first electrode, and the adjustment layer comprises a material with molecular dipole orientation. This invention, through the adjustment layer with molecular dipole orientation, regulates the charge carriers, adjusts the injection and transport characteristics of the charge carriers, thereby adjusting the capacitance curve of the organic electroluminescent device and improving the image trailing problem of the organic electroluminescent device. Attached Figure Description

[0023] One or more embodiments are illustrated by way of example with reference numerals in the accompanying drawings. These illustrations do not constitute a limitation on the embodiments. Elements with the same reference numerals in the drawings are denoted as similar elements. Unless otherwise stated, the figures in the drawings are not to be limited by scale.

[0024] Figure 1 This is a schematic diagram of an organic electroluminescent device according to one embodiment of the present invention; Figure 2 This is a schematic diagram of an organic electroluminescent device according to one embodiment of the present invention; Figure 3 This is a schematic diagram of an organic electroluminescent device according to one embodiment of the present invention; Figure 4 This is a schematic diagram of an organic electroluminescent device according to one embodiment of the present invention; Figure 5 This is a schematic diagram of an organic electroluminescent device according to one embodiment of the present invention; Figure 6 This is a schematic diagram of an organic electroluminescent device according to one embodiment of the present invention; Figure 7 These are the capacitance-voltage curves of Example 1 and Comparative Example 1.

[0025] Explanation of reference numerals in the attached figures: 100-Organic electroluminescent devices, 01-First electrode, 02-Second electrode, 03-Light-emitting unit / first light-emitting unit, 04-Second light-emitting unit, 31-Light-emitting layer, 311-First light-emitting layer, 312-Second light-emitting layer 32 - Adjustment layer, 321 - First adjustment layer / first adjustment sublayer, 322 - Second adjustment layer / second adjustment sublayer, 323 - Third adjustment sublayer. 33-Hole transport region, 331-Hole injection layer, 332-Hole transport layer, 3321-First hole transport sublayer, 3322-Second hole transport sublayer, 333-Electron blocking layer. 051-n type charge generation layer, 052-p type charge generation layer. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0027] Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0028] It should be noted that similar reference numerals and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures. It should be noted that, unless otherwise specified, different features in the embodiments of this application can be combined with each other.

[0029] For ease of understanding, the accompanying diagram shows the mutually orthogonal X-axis, Y-axis, and Z-axis. The direction along the X-axis is called the X-direction, the direction along the Y-axis is called the Y-direction, and the direction along the Z-axis is called the Z-direction. The Z-direction is the normal direction relative to the plane containing the X and Y directions. Furthermore, a view where various elements are observed parallel to the plane containing the X and Y directions is called a top view. Alternatively, the planes in the X and Y directions can be planes parallel to the display surface of the display panel, and the Z-direction can be a direction parallel to the thickness direction of the display panel.

[0030] For certain elements, terms like "above" or "overhead" are sometimes used when describing the position of an element in the Z direction, and "below" or "under" are used when describing the position of an element in the opposite direction. Furthermore, when using terms like "above," "overhead," "below," "under," or "relative" to define the positional relationship between two elements, this includes not only the state where the two elements are directly adjacent, but also the state where the two elements are separated by gaps or other elements. Additionally, terms like "first," "second," and "third" are used only for distinguishing descriptions and should not be interpreted as indicating or implying relative importance.

[0031] Organic electroluminescent devices (OLEDs) typically consist of an anode, a light-emitting layer, and a cathode stacked sequentially. Organic functional layers, such as hole injection layers, hole transport layers, electron blocking layers, electron transport layers, and electron injection layers, are placed between the anode and the light-emitting layer, and between the cathode and the light-emitting layer. Under the influence of an applied electric field, holes are injected from the anode, and electrons are injected from the cathode. Through this opposite movement, electrons and holes recombine in the light-emitting layer to form electron-hole pairs (excitons) at bound energy levels. These excitons radiate and de-excite, emitting photons and producing visible light. The inventors of this application have discovered that existing organic electroluminescent devices, due to their inherent characteristics, possess device capacitance; that is, the anode, cathode, and the organic functional layer located between the two electrodes form a parallel-plate capacitor. When an external electric field is applied through a driving circuit to drive the organic electroluminescent device to emit light, due to the device capacitance, the device itself needs to be filled with charge before it can emit light. This time period, typically called the turn-on time, occurs between the application of the electric field and the device emitting light. Organic electroluminescent devices (OLEDs) of different emission colors have different capacitance values, which in turn result in different turn-on times. When OLEDs are used in display panels, the difference in turn-on time can cause ghosting issues on the display panel.

[0032] Further research and analysis by the inventors revealed that, due to the inherent characteristics of the organic functional layer materials in the device, hole transport speed is typically faster than electron transport speed, making the device capacitance characteristics more significantly affected by hole carriers. Based on the above research and analysis, the inventors creatively proposed adjusting the device capacitance of the organic electroluminescent device by controlling the injection and transport of charge carriers, ultimately solving the ghosting problem of the display panel.

[0033] To address the aforementioned problems, the inventors, through extensive research, have innovatively proposed an organic electroluminescent device and display panel. The technical solution of this invention will be explained in detail below with reference to the accompanying drawings.

[0034] A first aspect of this application provides an organic electroluminescent device, comprising: a first electrode; at least one light-emitting unit located above the first electrode; and a second electrode located above the at least one light-emitting unit. The at least one light-emitting unit includes a light-emitting layer and at least one adjustment layer, the at least one adjustment layer being located between the light-emitting layer and the first electrode, and the adjustment layer comprising a material having a molecular dipole orientation. With this configuration, when an external electric field is applied to the organic electroluminescent device, the built-in electric field formed by the material with the molecular dipole orientation, whose direction is the same as or opposite to the direction of the external electric field, adjusts the carrier injection and transport characteristics, thereby solving the ghosting problem of display panels using this organic electroluminescent device.

[0035] Specifically, one embodiment is illustrated by an organic electroluminescent device comprising a light-emitting unit, wherein the light-emitting unit includes an adjustment layer. (See reference...) Figure 1 The organic electroluminescent device 100 includes a first electrode 01, a light-emitting unit 03, and a second electrode 02. The light-emitting unit 03 is disposed above the first electrode 01, and the second electrode 02 is disposed above the light-emitting unit 03. In this embodiment, the first electrode 01 is described as the anode and the second electrode 02 as the cathode. In other embodiments, the first electrode 01 can be the cathode, and the second electrode 02 can be the anode.

[0036] The light-emitting unit 03 includes a light-emitting layer 31 and an adjustment layer 32, with the adjustment layer 32 disposed between the light-emitting layer 31 and the first electrode 01. The adjustment layer 32 comprises a material with molecular dipole orientation. In this embodiment, an adjustment layer 32 containing a material with molecular dipole orientation is disposed between the light-emitting layer 31 and the first electrode 01. On the one hand, the characteristics of the material with molecular dipole orientation are used to adjust the injection and transport characteristics of hole carriers, thereby adjusting the capacitance of the organic electroluminescent device. On the other hand, the addition of the adjustment layer between the first electrode and the second electrode increases the distance between the two electrodes, further adjusting the capacitance of the organic electroluminescent device. By adjusting the capacitance of the device, the turn-on time of the organic electroluminescent device is adjusted, and ultimately the ghosting problem of the display panel using this organic electroluminescent device is improved.

[0037] In some embodiments of this application, the molecular dipole moment of the material of the adjustment layer 32 is 1 to 4 Debyes. Using a material with a molecular dipole moment within this range can effectively adjust the injection and transport characteristics of hole carriers, thereby adjusting the capacitance of the organic light-emitting device (OLED), effectively adjusting the turn-on time of the OLED, and improving the display panel ghosting problem. Further, in other embodiments of this application, the molecular dipole moment of the material of the adjustment layer 32 is 2 to 3 Debyes. Using a material with this molecular dipole moment range can better adjust the injection and transport characteristics of hole carriers, thereby effectively adjusting the turn-on time of the OLED, and better improving the display panel ghosting problem. Specifically, the molecular dipole moment of the material of the adjustment layer 32 can be 1 Debye, 1.5 Debye, 2 Debye, 2.2 Debye, 2.5 Debye, 2.7 Debye, 3 Debye, 3.5 Debye, 3.7 Debye, or 4 Debye.

[0038] In some embodiments of this application, the hole mobility of the material of the adjustment layer 32 is 4.0 × 10⁻⁶. -7 ~6.0×10 -4 cm² / (V•s). Based on materials with molecular dipole moments, further selecting materials with specific hole mobility conditions as the adjustment layer material can better improve the injection and transport characteristics of hole carriers. Furthermore, in some embodiments of this application, the hole mobility of the adjustment layer 32 material is 5.0 × 10⁻⁶ cm² / (V•s). -6 ~8.0×10 -5 cm² / (V•s). Using materials within this hole mobility range as the adjustment layer material is more conducive to adjusting the injection and transport characteristics of hole carriers in organic electroluminescent devices, and ultimately improving the ghosting problem of display panels. Specifically, the hole mobility of the material in the adjustment layer 32 can be 4.0 × 10⁻⁶ cm² / (V•s). -7 cm² / (V•s), 4.5×10 -7 cm² / (V•s), 8.0×10 -7 cm² / (V•s), 1.0×10 -6 cm² / (V•s), 2.5×10 -6 cm² / (V•s), 4.0×10 -6 cm² / (V•s), 5.0×10 -6 cm² / (V•s), 6.3×10 -6 cm² / (V•s), 9.2×10 -6 cm² / (V•s), 3.3×10 -5 cm² / (V•s), 5.8×10-5 cm² / (V•s), 7.2×10 -5 cm² / (V•s), 8.0×10 -5 cm² / (V•s), 1.2×10 -4 cm² / (V•s), 4.7×10 -4 cm² / (V•s), 6.0×10 -4 cm² / (V•s).

[0039] In some embodiments of this application, the material of the adjustment layer 32 includes a polar hole transport material or a polar electron transport material. Further, in other embodiments of this application, the material of the adjustment layer 32 includes a polar electron transport material with a positive orientation polarization. In some embodiments of this application, the material of the adjustment layer 32 includes aromatic amine derivatives, star-shaped aromatic amines, benzene ring derivatives containing imidazole groups (phenololine derivatives), or benzene ring derivatives containing pyridine groups. Specifically, the polar hole transport material can be an aromatic amine derivative, such as TAPC (di-[4-(N,N-dimethylamino)phenyl]cyclohexane), NPB (N,N'-di(1-naphthyl)-N,N'-diphenylbenzidine); or a star-shaped aromatic amine, such as m-MTDATA (4,4',4''-tris(N-3-methylphenyl-N-phenylamino)triphenylamine). Polar electron transport materials with spontaneous orientation polarization of positive values ​​can be selected from benzene ring derivatives containing imidazole groups, such as TPBi (1,3,5-tris(1-phenyl-1H-benzimidazol-2-yl)benzene); phenanthrene derivatives, such as Bphen (4,7-diphenyl-1,10-phenanthroline); and benzene ring derivatives containing pyridine groups, such as TmPyPB (1,3,5-tris(m-pyridin-3-ylphenyl)benzene). The display panel includes multiple organic light-emitting diodes (OLEDs). Based on the differences in the device capacitance of different OLEDs, the above-mentioned materials are selected as adjustment layer materials to regulate the hole carrier injection and transport characteristics in different OLEDs. That is, some devices require adjustment layers that promote hole carrier injection and transport, while others require adjustment layers that hinder hole carrier injection and transport. By using the above materials, the injection and transport characteristics of hole carriers can be better adjusted according to actual needs, thereby better adjusting the capacitance of the organic electroluminescent device and ultimately improving the ghosting problem of the display panel using the organic electroluminescent device.

[0040] Furthermore, in some embodiments of this application, the material of the adjustment layer 32 includes at least one of the following compounds:

[0041] .

[0042] In some embodiments of this application, see Figure 2 The light-emitting unit 03 also includes a hole transport region 33, which is located between the light-emitting layer 31 and the first electrode 01. An adjustment layer 32 is located between the light-emitting layer 31 and the hole transport region 33. That is, the adjustment layer 32 is located between the layer in the hole transport region 33 closest to the light-emitting layer 31 and the light-emitting layer 31. Further, the hole transport region 33 may include one or more of a hole injection layer, a hole transport layer, and an electron blocking layer. Specifically, see [link to documentation]. Figure 2 The hole transport region 33 includes a hole injection layer 331, a hole transport layer 332, and an electron blocking layer 333. The hole injection layer 331 is located above the first electrode 01, the hole transport layer 332 is located above the hole injection layer 331, and the electron blocking layer 333 is located above the hole transport layer 332. The adjustment layer 32 is located between the light-emitting layer 31 and the electron blocking layer 333. In other embodiments of this application, the hole transport region 33 may contain one of the hole injection layer, the hole transport layer, and the electron blocking layer, or two or more of these layers. It is understood that when the hole transport region 33 contains only one hole injection layer 331, the adjustment layer 32 is located between the hole injection layer 331 and the light-emitting layer 31; when the hole transport region 33 contains two layers stacked along the direction away from the first electrode 01, namely the hole injection layer 331 and the hole transport layer 332, the adjustment layer 32 is located between the hole transport layer 332 and the light-emitting layer 31. An adjustment layer is placed between the light-emitting layer and the hole transport region. On one hand, the properties of the material with molecular dipole orientation are used to adjust the injection and transport characteristics of hole carriers, thereby adjusting the capacitance of the organic light-emitting device (OLED). On the other hand, the distance between the two electrodes is increased, further adjusting the capacitance of the OLED. By controlling the device capacitance, the turn-on time of the OLED is adjusted, ultimately improving the ghosting problem on display panels using this OLED.

[0043] In some embodiments of this application, the adjustment layer 32 is located between the hole transport region 33 and the first electrode 01. That is, the adjustment layer is located between the layer in the hole transport region 33 closest to the first electrode 01 and the first electrode 01. Specifically, see [link to relevant documentation]. Figure 3 The adjustment layer 32 is located between the hole injection layer 331 and the first electrode 01. Understandably, when the hole transport region 33 has only one electron blocking layer 333, the adjustment layer 32 is located between the electron blocking layer 333 and the first electrode 01. When the hole transport region 33 has two layers stacked in a direction away from the first electrode 01—a hole transport layer 332 and an electron blocking layer 333—the adjustment layer 32 is located between the hole transport layer 332 and the first electrode 01.

[0044] In some embodiments of this application, the adjustment layer 32 is located within the hole transport region 33. Specifically, an example is taken where a hole injection layer 331, a hole transport layer 332, and an electron blocking layer 333 are stacked in the hole transport region 33 along a direction away from the first electrode 01. See also Figure 4 The adjustment layer 32 is disposed between the hole transport layer 332 and the electron blocking layer 333. Understandably, the adjustment layer 32 may also be disposed between the hole injection layer 331 and the hole transport layer 332.

[0045] In some other embodiments of this application, at least one of the hole injection layer 331, hole transport layer 332, and electron blocking layer 333 may be arranged in a stacked configuration of two or more layers. Taking a two-layer stacked configuration as an example, the hole injection layer 331 may include a first hole injection sub-layer and a second hole injection sub-layer stacked together; or, the hole transport layer 332 may include a first hole transport sub-layer and a second hole transport sub-layer stacked together; or, the electron blocking layer 333 may include a first electron blocking sub-layer and a second electron blocking sub-layer stacked together. In this case, the adjustment layer 32 may be located between the first hole injection sub-layer and the second hole injection sub-layer, or between the first hole transport sub-layer and the second hole transport sub-layer, or between the first electron blocking sub-layer and the second electron blocking sub-layer.

[0046] In some embodiments of this application, the light-emitting unit 03 may be provided with two, three, or more adjustment layers 32. Specifically, see [link to relevant documentation]. Figure 5The light-emitting unit 03 includes a hole injection layer 331, a first hole transport sublayer 3321, a second hole transport sublayer 3322, an electron blocking layer 333, and an adjustment layer 32. The hole injection layer 331, the first hole transport sublayer 3321, the second hole transport sublayer 3322, and the electron blocking layer 333 are stacked along a direction away from the first electrode 01. The adjustment layer 32 includes a first adjustment sublayer 321, a second adjustment sublayer 322, and a third adjustment sublayer 323. The first adjustment sublayer 321 is located between the electron blocking layer 333 and the light-emitting layer 31; the second adjustment sublayer 322 is located between the hole injection layer 331 and the first hole transport sublayer 3321; and the third adjustment sublayer 323 is located between the first hole transport sublayer 3321 and the second hole transport sublayer 3322. By adopting the configuration method of this embodiment, multiple adjustment layers are set, which can further adjust the injection and transport characteristics of hole carriers at different positions, thereby effectively controlling the capacitance of the organic electroluminescent device as a whole. The setting of multiple adjustment layers further increases the distance between the two electrodes, further adjusting the capacitance of the organic electroluminescent device, and ultimately improving the ghosting problem of the display panel using the organic electroluminescent device.

[0047] In some embodiments of this application, the light-emitting unit 03 may further include an electron transport region located between the light-emitting layer and the second electrode. The electron transport region may include one or more of an electron injection layer, an electron transport layer, and a hole blocking layer.

[0048] In some embodiments of this application, the organic electroluminescent device has two, three, or more light-emitting units. This embodiment is described using two light-emitting units as an example. Specifically, see... Figure 6The organic electroluminescent device 100 includes a first electrode 01, a first light-emitting unit 03, a second light-emitting unit 04, and a second electrode 02. The first light-emitting unit 03 and the second light-emitting unit 04 are located between the first electrode 01 and the second electrode 02, with the second light-emitting unit 04 located on the side of the first light-emitting unit 03 away from the first electrode 01. A charge-generating layer is disposed between the first light-emitting unit 03 and the second light-emitting unit 04. The charge-generating layer includes an n-type charge-generating layer 051 and a p-type charge-generating layer 052, with the p-type charge-generating layer 052 located on the side of the n-type charge-generating layer 051 away from the first electrode 01. The first light-emitting unit 03 includes a first light-emitting layer 311 and a first adjustment layer 321, and the second light-emitting unit 04 includes a second light-emitting layer 312 and a second adjustment layer 322. The first adjustment layer 321 is located between the first electrode 01 and the first light-emitting layer 311. The second adjustment layer 322 is located between the charge-generating layer and the second light-emitting layer 312. When multiple light-emitting units are involved, each unit can have its own independent adjustment layer. This allows for the individual adjustment of hole carrier injection and transport characteristics within each unit using materials with molecular dipole orientation, thereby synchronously adjusting the capacitance of the organic light-emitting device (OLED). Simultaneously, increasing the distance between the two electrodes further effectively adjusts the OLED's capacitance. By controlling the device capacitance, the turn-on time of the OLED is adjusted, ultimately improving the ghosting problem on display panels using this OLED.

[0049] In other embodiments of this application, the first light-emitting unit 03 and the second light-emitting unit 04 may further include one or more of a hole injection layer, a hole transport layer, and an electron blocking layer. The first adjustment layer 321 and the second adjustment layer 322 may also be disposed between any two of the hole injection layer, hole transport layer, and electron blocking layer. It is understood that the first adjustment layer 321 and the second adjustment layer 322 may be disposed in any of the aforementioned embodiments.

[0050] In some embodiments of this application, the organic light-emitting device 100 can be a top-emitting organic light-emitting device. In a top-emitting organic light-emitting device, the first electrode 01 is a reflective electrode, and the second electrode 02 is a transmissive electrode or a semi-reflective / semi-transmissive electrode. In some other embodiments of this application, the organic light-emitting device 100 can be a bottom-emitting organic light-emitting device. In a bottom-emitting organic light-emitting device, the first electrode 01 is a transmissive electrode, and the second electrode 02 is a reflective electrode.

[0051] In some embodiments of this application, the thickness of the adjustment layer 32 is 1–15 nm. Based on selecting a material with molecular dipole orientation as the adjustment layer, the thickness of the adjustment layer can be further adjusted. Using the above-mentioned thickness setting method, not only can the characteristics of the material with molecular dipole orientation be utilized to adjust the injection and transport characteristics of hole carriers, thereby adjusting the capacitance of the organic electroluminescent device; but also, by limiting the thickness of the adjustment layer, the capacitance of the organic electroluminescent device can be adjusted more precisely. By controlling the device capacitance, the turn-on time of the organic electroluminescent device is adjusted, and ultimately, the ghosting problem of the display panel using this organic electroluminescent device is improved. Specifically, the thickness of the adjustment layer 32 can be 1 nm, 3 nm, 4 nm, 5 nm, 6 nm, 7 nm, 9 nm, 11 nm, 12 nm, 13 nm, or 14 nm.

[0052] In some embodiments of this application, the adjustment layer 32 is positioned differently, i.e., its thickness varies depending on whether it is located between different film layers. Preferably, when the adjustment layer is located between the hole injection layer and the hole transport layer, its thickness is 1–5 nm. When the adjustment layer is located between the hole transport layer and the electron blocking layer, its thickness is 7–11 nm. When the adjustment layer is located between the electron blocking layer and the light-emitting layer, its thickness is 12–14 nm. By using the configuration described in this embodiment, different thicknesses of the adjustment layer at different locations allow for more precise adjustment of the hole carrier injection and transport characteristics, thereby enabling more precise adjustment of the capacitance of the organic electroluminescent device. By controlling the device capacitance, the turn-on time of the organic electroluminescent device is adjusted, ultimately improving the ghosting problem of the display panel using this organic electroluminescent device.

[0053] In some embodiments of this application, when the first electrode 01 is the anode, the material used for the first electrode 01 can be selected from materials with high work function to facilitate hole injection. The material of the first electrode 01 can be selected from indium tin oxide (ITO), indium zinc oxide (IZO), tin oxide (SnO2), zinc oxide (ZnO), and any combination thereof, but is not limited thereto. The first electrode 01 can have a single-layer structure or a multi-layer structure, such as a three-layer structure of ITO / Ag / ITO. Embodiments of this application are not limited thereto.

[0054] In some embodiments of this application, when the second electrode 02 is a cathode, the material of the second electrode 02 may be selected from at least one of lithium (Li), silver (Ag), magnesium (Mg), aluminum (Al), ytterbium (Yb), aluminum-lithium (Al-Li), calcium (Ca), magnesium-indium (Mg-In), silver-magnesium (Ag-Mg), and silver-ytterbium (Ag-Yb), but is not limited thereto. Similarly, the second electrode 02 may have a single-layer structure or a multi-layer structure.

[0055] A second aspect of this application provides a display panel including the organic light-emitting device of the above embodiments. Specifically, the display panel includes a blue organic light-emitting device, a red organic light-emitting device, and a green organic light-emitting device. At least one of the blue, red, and green organic light-emitting devices employs the organic light-emitting device of the above embodiments.

[0056] The inventors conducted experimental research to obtain the implementation scheme of this application. The technical effects of the scheme of this application will be introduced below in conjunction with the experimental results.

[0057] The preparation of the examples and comparative examples uses existing processes. Specifically, taking Example 1 as an example, the preparation includes the following steps: Step 101: A substrate is provided, which can be a TFT backplane with a driving circuit structure. A first electrode 01 is fabricated on the substrate and patterned. Specifically, the first electrode 01 is an anode and a reflective electrode. The first electrode 01 can be an ITO / Ag / ITO structure.

[0058] Step 102: Prepare a pixel define layer (PDL) above the patterned first electrode, and pattern the PDL layer to form a PDL opening that exposes the anode.

[0059] Step 103: Deposit an organic film layer onto the structure obtained in step 102. Specifically, a hole injection layer, a hole transport layer, an electron blocking layer, an adjustment layer, a light-emitting layer, a hole blocking layer, an electron transport layer, and an electron injection layer can be deposited sequentially.

[0060] Step 104: Fabricate a cathode on the electron injection layer. Specifically, a Mg-Ag alloy can be vapor-deposited to form the cathode.

[0061] The specific compositions of Examples 1-19 and Comparative Examples 1-3 are shown below. The first electrode employs an ITO / Ag / ITO structure, and the second electrode employs a Mg-Ag alloy. The hole injection layer, hole transport layer, electron blocking layer, electron transport layer, and electron injection layer all utilize conventional materials in the art.

[0062] Example 1: An organic electroluminescent device, the structure of which is: first electrode / hole injection layer / hole transport layer / electron blocking layer / tuning layer / light-emitting layer / hole blocking layer / electron transport layer / electron injection layer / second electrode. The tuning layer is made of a polar electron transport material. The molecular dipole moment of the tuning layer is 1 Debye, and the tuning layer thickness is 15 nm.

[0063] Example 2: The difference from Example 1 is that the molecular dipole moment of the adjustment layer material is 2 Debye.

[0064] Example 3: The difference from Example 1 is that the molecular dipole moment of the adjustment layer material is 2.2 Debye.

[0065] Example 4: The difference from Example 1 is that the molecular dipole moment of the adjustment layer material is 3 Debye.

[0066] Example 5: The difference from Example 1 is that the molecular dipole moment of the adjustment layer material is 4 Debye.

[0067] Example 6: The difference from Example 1 is that the hole mobility of the adjustment layer material is 4.0 × 10⁻⁶. -7 cm² / (V•s).

[0068] Example 7: The difference from Example 1 is that the hole mobility of the adjustment layer material is 5.0 × 10⁻⁶. -6 cm² / (V•s).

[0069] Example 8: The difference from Example 1 is that the hole mobility of the adjustment layer material is 9.2 × 10⁻⁶. -6 cm² / (V•s).

[0070] Example 9: The difference from Example 1 is that the hole mobility of the adjustment layer material is 8.0 × 10⁻⁶. -5 cm² / (V•s).

[0071] Example 10: The difference from Example 1 is that the hole mobility of the adjustment layer material is 6.0 × 10⁻⁶. -4 cm² / (V•s).

[0072] Example 11: The difference from Example 1 is that the thickness of the adjustment layer is 1 nm.

[0073] Example 12: The difference from Example 1 is that the thickness of the adjustment layer is 3nm.

[0074] Example 13: The difference from Example 1 is that the thickness of the adjustment layer is 10nm.

[0075] Example 14: The difference from Example 1 is that the thickness of the adjustment layer is 12nm.

[0076] Example 15: The difference from Example 1 is that the thickness of the adjustment layer is 14nm.

[0077] Example 16: The difference from Example 1 is that the adjustment layer is located between the hole injection layer and the hole transport layer, and has a thickness of 2nm.

[0078] Example 17: The difference from Example 1 is that the adjustment layer is located between the hole transport layer and the electron blocking layer, and has a thickness of 9nm.

[0079] Example 18: The difference from Example 1 is that two adjustment layers are provided. The first adjustment layer is located between the electron blocking layer and the light emitting layer, with a thickness of 12nm. The second adjustment layer is located between the hole injection layer and the hole transport layer, with a thickness of 2nm.

[0080] Example 19: The difference from Example 1 is that the adjustment layer material is a polar hole transport material.

[0081] Comparative Example 1: An organic electroluminescent device, the structure of which is: first electrode / hole injection layer / hole transport layer / electron blocking layer / light emitting layer / hole blocking layer / electron transport layer / electron injection layer / second electrode. It is basically the same as the device structure and materials in Example 1, the difference being the absence of an adjustment layer.

[0082] Comparative Example 2: The difference from Example 10 is that the thickness of the adjustment layer is 0.5 nm.

[0083] Comparative Example 3: The difference from Example 10 is that the thickness of the adjustment layer is 20 nm.

[0084] The capacitance-voltage (CV) tests were performed on the organic electroluminescent devices of the examples and comparative examples, and the obtained capacitance-voltage curves are shown below. Figure 7 As shown. The charge amount is obtained by integrating the vertical axis of the curve, using the voltage range from the peak voltage position (1.5V) in the capacitance curve to the turn-on voltage position (2.15V) of the light-emitting device. With the charge amount of the device in Comparative Example 1 as 100%, the relative proportion data of the charge amount in Examples 1-19 are shown in Table 1.

[0085] Table 1

[0086] From Table 1 and Figure 7It can be seen that, under the same start-up voltage, the charge of the device in Comparative Example 1 is 100%, while the charge of the device in Example 1 is 84.3% of that in Comparative Example 1. This demonstrates that the adjustment layer can significantly adjust the capacitance-voltage curve of the device, thus achieving control over the device's capacitance. Examples 2-10 show that, using the same type of adjustment layer material, such as polar electron transport materials, adjusting the dipole moment and hole mobility of the adjustment layer material can achieve more precise control over the device's capacitance to meet the adjustment needs of different devices. Examples 11-19 and Comparative Examples 2-3 show that by setting an adjustment layer at a specific location and simultaneously adjusting its thickness, more precise control over the device's capacitance can be achieved, further meeting the adjustment needs of different devices and ultimately improving the ghosting problem of display panels using this organic electroluminescent device.

[0087] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above 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.

[0088] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. An organic electroluminescent device, characterized in that, include: First electrode, At least one light-emitting unit, the at least one light-emitting unit being located above the first electrode, and The second electrode is located above the at least one light-emitting unit. Wherein, at least one of the light-emitting units includes a light-emitting layer and at least one adjustment layer, the at least one adjustment layer being located between the light-emitting layer and the first electrode, the adjustment layer comprising a material having a molecular dipole orientation.

2. The organic electroluminescent device according to claim 1, characterized in that, The molecular dipole moment of the material in the adjustment layer is 1 to 4 Debye; Preferably, the molecular dipole moment of the material of the adjustment layer is 2 to 3 Debye.

3. The organic electroluminescent device according to claim 1, characterized in that, The hole mobility of the material in the adjustment layer is 4.0 × 10⁻⁶. -7 ~6.0×10 -4 cm² / (V•s); Preferably, the hole mobility of the material in the adjustment layer is 5.0 × 10⁻⁶. -6 ~8.0×10 -5 cm² / (V•s).

4. The organic electroluminescent device according to claim 1, characterized in that, The material of the adjustment layer includes polar hole transport materials or polar electron transport materials; Preferably, the material of the adjustment layer includes aromatic amine derivatives, star-shaped aromatic amines, benzene ring derivatives containing imidazole groups, phenololine derivatives, or benzene ring derivatives containing pyridine groups.

5. The organic electroluminescent device according to claim 1, characterized in that, The material of the adjustment layer includes at least one of the following compounds: 。 6. The organic electroluminescent device according to claim 1, characterized in that, The light-emitting unit further includes a hole transport region located between the light-emitting layer and the first electrode. The adjustment layer is located between the light-emitting layer and the hole transport region. And / or, the adjustment layer is located between the hole transport region and the first electrode. And / or, the adjustment layer is located within the hole transport region; Preferably, the hole transport region includes one or more of a hole injection layer, a hole transport layer, and an electron blocking layer.

7. The organic electroluminescent device according to claim 1, characterized in that, The at least one light-emitting unit includes a first light-emitting unit and a second light-emitting unit stacked together, the second light-emitting unit being located on the side of the first light-emitting unit away from the first electrode, and a charge generation layer being disposed between the first light-emitting unit and the second light-emitting unit. The first light-emitting unit includes a first light-emitting layer and a first adjustment layer, and the second light-emitting unit includes a second light-emitting layer and a second adjustment layer. The first adjustment layer is located between the first electrode and the first light-emitting layer, and the second adjustment layer is located between the charge generation layer and the second light-emitting layer.

8. The organic electroluminescent device according to any one of claims 1-7, characterized in that, The thickness of the adjustment layer is 1–15 nm.

9. The organic electroluminescent device according to claim 8, characterized in that, The adjustment layer is located between the hole injection layer and the hole transport layer, and the thickness of the adjustment layer is 1-5 nm; And / or, the adjustment layer is located between the hole transport layer and the electron blocking layer, and the thickness of the adjustment layer is 7–11 nm; And / or, the adjustment layer is located between the electron blocking layer and the light-emitting layer, and the thickness of the adjustment layer is 12-14 nm.

10. A display panel, characterized in that, Including the organic electroluminescent device as described in any one of claims 1-9.

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