Display panel and display device

Abstract

This invention provides a display panel comprising at least one organic light-emitting device (OLED), which includes a first electrode, a second electrode, and at least one light-emitting layer. The light-emitting layer is located on the first electrode and comprises a first material and a second material, wherein the triplet energy level of the first material is higher than that of the second material. The second electrode is located on the at least one light-emitting layer and further comprises a third material, wherein the singlet energy level of the second material is higher than that of the third material. The light-emitting layer includes the third material, and / or, at least one light-emitting layer comprises a first light-emitting layer and a second light-emitting layer stacked together, with a third material layer disposed between the first and second light-emitting layers. The third material includes a perovskite material. This invention improves the exciton utilization rate of the display panel by disposing of a perovskite material within the light-emitting layer and / or between two light-emitting layers, achieving a narrowed emission spectrum and ultimately realizing a wide color gamut display.

Description

Technical Field

[0001] This invention belongs to the field of display technology, specifically relating to a display panel and a display device. 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 application range, becoming the mainstream display panel. However, the performance of current OLED display products still needs improvement. Summary of the Invention

[0003] In view of this, embodiments of the present invention aim to provide a display panel and display device that can effectively improve exciton utilization and achieve wide color gamut display of the display panel.

[0004] A first aspect of the present invention provides a display panel including at least one organic electroluminescent device, the organic electroluminescent device comprising:

[0005] First electrode, At least one light-emitting layer is located on the first electrode. The light-emitting layer comprises a first material and a second material, wherein the triplet energy level of the first material is higher than the triplet energy level of the second material. The second electrode is located on the at least one light-emitting layer. The third material includes a perovskite material, wherein the singlet energy level of the second material is higher than that of the third material. Wherein, the light-emitting layer includes the third material, and / or, the at least one light-emitting layer includes a first light-emitting layer and a second light-emitting layer stacked together, with the third material layer disposed between the first light-emitting layer and the second light-emitting layer.

[0006] Optionally, in some embodiments of the present invention, the third material comprises a narrow-spectrum perovskite material, preferably, the full width at half maximum (FWHM) of the third material is less than or equal to 30 nm.

[0007] Optionally, in some embodiments of the present invention, the band gap of the perovskite material is 1.3 eV to 3.3 eV.

[0008] Optionally, in some embodiments of the present invention, at least one organic electroluminescent device includes a first light-emitting device, a second light-emitting device, and a third light-emitting device. The first light-emitting device includes at least one first light-emitting sublayer, the second light-emitting device includes at least one second light-emitting sublayer, and the third light-emitting device includes at least one third light-emitting sublayer. The first light-emitting sublayer emits red light, the second light-emitting sublayer emits green light, and the third light-emitting sublayer emits blue light. The band gap of the third material in the first light-emitting sublayer is 1.5 eV to 2.5 eV; and / or, the band gap of the third material in the second light-emitting sublayer is 1.88 eV to 2.88 eV; and / or, the band gap of the third material in the third light-emitting sublayer is 2.2 eV to 3.2 eV.

[0009] Optionally, in some embodiments of the present invention, the perovskite material has the chemical formula ABX3, wherein A is a cation, B is a metal cation, and X is an anion; A is selected from cesium and formamidinium; B is selected from lead and tin; and X is selected from halogens.

[0010] Preferably, in some embodiments of the present invention, X is selected from iodine, bromine, and chlorine.

[0011] Optionally, in some embodiments of the present invention, the mass of the third material accounts for 0.25% to 15% of the mass of the light-emitting layer.

[0012] Preferably, in some embodiments of the present invention, the mass of the third material accounts for 0.5% to 10% of the mass of the light-emitting layer.

[0013] Optionally, in some embodiments of the present invention, the light-emitting layer includes a first material, a second material, a third material, and a fourth material, wherein the first material is a host material, the second material is a phosphorescent material, and the fourth material is a fluorescent material.

[0014] Preferably, in some embodiments of the present invention, the triplet energy level of the third material is lower than the triplet energy level of the fourth material, and the singlet energy level of the third material is lower than the singlet energy level of the second material.

[0015] Optionally, in some embodiments of the present invention, the at least one light-emitting layer includes a first light-emitting layer and a second light-emitting layer stacked together, with the third material layer disposed between the first light-emitting layer and the second light-emitting layer, and the second light-emitting layer disposed on the side of the first light-emitting layer away from the first electrode; it also includes a hole blocking layer and an electron blocking layer, the hole blocking layer being located on the side of the second light-emitting layer near the second electrode, and the electron blocking layer being located on the side of the first light-emitting layer near the first electrode.

[0016] Optionally, in some embodiments of the present invention, the surface of the third material layer near the first electrode is a first surface, the distance between the first surface and the electron blocking layer is h, the surface of the third material layer near the second electrode is a second surface, and when the second surface is in direct contact with the hole blocking layer, the distance between the first surface and the electron blocking layer is hmax, and h / hmax is 0 to 1.

[0017] Preferably, in some embodiments of the present invention, h / hmax is 0.2 to 0.4.

[0018] A second aspect of the present invention provides a display device including the display panel described in the above embodiments.

[0019] The beneficial effects of this invention are as follows: A display panel provided by this invention includes at least one organic light-emitting device (OLED). The OLED includes a first electrode, a second electrode, and at least one light-emitting layer. The light-emitting layer is located on the first electrode and includes a first material and a second material. The triplet energy level of the first material is higher than that of the second material. The second electrode is located on the at least one light-emitting layer and also includes a third material. The singlet energy level of the second material is higher than that of the third material. The light-emitting layer includes the third material, and / or the at least one light-emitting layer includes a first light-emitting layer and a second light-emitting layer stacked together, with the third material layer disposed between the first and second light-emitting layers. The third material includes a perovskite material. This invention improves the exciton utilization rate in the display panel by doping within the light-emitting layer and / or separately disposing of a perovskite material layer between the two light-emitting layers, achieving a narrowed emission spectrum and ultimately realizing a wide color gamut display. Attached Figure Description

[0020] 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.

[0021] Figure 1 This is a schematic diagram of a display panel according to one embodiment of the present invention; Figure 2 This is a schematic diagram of a display panel according to another embodiment of the present invention; Figure 3 This is a schematic diagram of a display panel according to another embodiment of the present invention; Figure 4 This is a schematic diagram of a display panel according to another embodiment of the present invention; Figure 5 This is a schematic diagram of a display panel according to another embodiment of the present invention.

[0022] Explanation of reference numerals in the attached figures: 1: Display panel; 10: Substrate. 100: Organic electroluminescent device; 101: First light-emitting device; 102: Second light-emitting device; 103: Third light-emitting device; 01: First electrode; 02: Second electrode; 03: Light-emitting layer / first light-emitting layer; 04: Second light-emitting layer; 031: First light-emitting sublayer; 032: Second light-emitting sublayer; 033: Third light-emitting sublayer; 05: Third material layer; 06: Electron blocking layer; 07: Hole blocking layer. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0024] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0025] 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 the present invention can be combined with each other.

[0026] 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.

[0027] 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.

[0028] Existing organic light-emitting diodes (OLEDs) typically consist of an anode, an emissive 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 emissive layer, and between the cathode and the emissive 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 emissive layer to form electron-hole pairs, i.e., excitons, at bound energy levels. These excitons radiate and de-excite, emitting photons and producing visible light. With the current high market demand for OLED displays, higher requirements are being placed on the color gamut of OLED displays.

[0029] The inventors of this invention have discovered that existing solutions for achieving wide color gamut display in display panels generally fall into two categories. One is a pure phosphorescence emission scheme, where green and red organic light-emitting devices (OLEDs) use phosphorescent materials for emission, while blue OLEDs use fluorescent materials. However, this scheme achieves poor wide color gamut display results. The inventors' research and analysis indicate that this is due to the inherent luminescence characteristics of phosphorescent materials; their intrinsic spectrum is broad, resulting in an emission spectrum even wider than fluorescence, making it difficult to achieve a narrow spectrum. Even if the required color points are met, the efficiency loss is significant. The other approach is a phosphorescence sensitization scheme, where green and red OLEDs use phosphorescent materials as sensitizers and fluorescent materials as guest materials, converting phosphorescence into fluorescence to narrow the emission spectrum and ultimately achieve wide color gamut display. However, the inventors have found that this scheme is limited by the materials used in phosphorescence and fluorescence.

[0030] To address the aforementioned problems, the inventors, through extensive research, have innovatively proposed a display panel and display device. The technical solution of this invention will be explained in detail below with reference to the accompanying drawings.

[0031] A first aspect of this invention provides a display panel including at least one organic electroluminescent device (OLED). The OLED includes a first electrode, at least one light-emitting layer, and a second electrode. The light-emitting layer is located above the first electrode, and the second electrode is located above the light-emitting layer. The light-emitting layer includes a first material and a second material, wherein the triplet energy level of the first material is higher than that of the second material. The OLED further includes a third material, which includes a perovskite material.

[0032] The following description uses an example of a display panel incorporating an organic electroluminescent device and a light-emitting layer. Specifically, in some embodiments of the present invention, see [link to relevant documentation]. Figure 1 The display panel 1 includes a substrate 10, and an organic light-emitting device 100 is disposed on the substrate 10. The organic light-emitting device 100 includes a first electrode 01, a light-emitting layer 03, and a second electrode 02. The light-emitting layer 03 is disposed above the first electrode 01, and the second electrode 02 is disposed above the light-emitting layer 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.

[0033] The light-emitting layer 03 includes a first material and a second material, wherein the triplet energy level of the first material is higher than that of the second material. Optionally, the singlet energy level of the first material is higher than that of the second material. The light-emitting layer 03 also includes a third material, which includes a perovskite material, wherein the singlet energy level of the second material is higher than that of the third material. Optionally, the triplet energy level of the second material is higher than that of the third material. In this embodiment, perovskite material is doped into the first and second materials in the light-emitting layer. By using the perovskite material as the light-emitting guest, the exciton utilization rate is improved. At the same time, the perovskite light-emitting material itself can also conduct holes and electrons, thereby ensuring the exciton recombination rate. This can achieve the effect of narrowing the emission spectrum and ultimately realize the wide color gamut display of the display panel.

[0034] In other embodiments of the present invention, the light-emitting layer may be two, three, or more layers. The following description uses a two-layer light-emitting layer as an example. Specifically, see... Figure 2The display panel 1 includes a substrate 10, and an organic electroluminescent device 100 is disposed on the substrate 10. The organic electroluminescent device 100 includes a first electrode 01, a first light-emitting layer 03, a second light-emitting layer 04, a second electrode 02, and a third material layer 05. The first light-emitting layer 03 is disposed above the first electrode 01, the second light-emitting layer 04 is disposed on the side of the first light-emitting layer 03 away from the first electrode 01, and the second electrode 02 is disposed on the side of the second light-emitting layer 04 away from the first light-emitting layer 03. The first light-emitting layer 03 includes a first material and a second material, and the second light-emitting layer 04 includes both a first material and a second material, wherein the triplet energy level of the first material is higher than the triplet energy level of the second material. Optionally, the singlet energy level of the first material is higher than the singlet energy level of the second material.

[0035] A third material layer 05 is disposed between the first light-emitting layer 03 and the second light-emitting layer 04. The third material in the third material layer 05 includes a perovskite material, and the singlet energy level of the second material is higher than that of the third material. Optionally, the triplet energy level of the second material is higher than that of the third material. In this embodiment, a third material layer is disposed between the stacked light-emitting layers. The third material layer uses a perovskite material. After exciton recombination occurs in the light-emitting layer, the exciton energy is transferred to the perovskite film to excite light emission, achieving a narrowed emission spectrum and ultimately realizing a wide color gamut display of the display panel. Simultaneously, independently disposing of the third material layer between the stacked light-emitting layers avoids defect states generated when the perovskite material is mixed with other materials, improving the performance of the display panel.

[0036] Optionally, in some embodiments of the present invention, the first material can be used as the host material, the second material can be used as the sensitizer, and the third material can be used as the guest material.

[0037] Optionally, in some embodiments of the present invention, the third material includes a narrow-spectrum perovskite material. Selecting a perovskite material with specific properties can further achieve the effect of narrowing the emission spectrum. Optionally, the full width at half maximum (FWHM) of the third material is less than or equal to 30 nm. Further, the FWHM of the third material can be 15 nm to 30 nm. Selecting a perovskite material with a specific FWHM can further improve exciton utilization, enhance the effect of narrowing the emission spectrum, and ultimately achieve a wide color gamut display for the display panel. Specifically, the FWHM of the third material can be 15 nm, 17 nm, 20 nm, 23 nm, 25 nm, 26 nm, or 30 nm.

[0038] Optionally, in some embodiments of the present invention, the third material includes a perovskite material with a band gap of 1.3 eV to 3.3 eV. Selecting a perovskite material with a specific band gap can improve exciton utilization and achieve the effect of narrowing the emission spectrum.

[0039] Furthermore, in some embodiments of the present invention, the display panel may include two, three, or more organic electroluminescent devices. This embodiment is illustrated by example, where three organic electroluminescent devices are disposed in the display panel, and each organic electroluminescent device has a light-emitting layer. Specifically, see [link to documentation]. Figure 3 The display panel 1 includes a substrate 10, a first light-emitting device 101, a second light-emitting device 102, and a third light-emitting device 103. The first light-emitting device 101, the second light-emitting device 102, and the third light-emitting device 103 are disposed on the substrate 10. The first light-emitting device 101 includes a first light-emitting sublayer 031, the second light-emitting device 102 includes a second light-emitting sublayer 032, and the third light-emitting device 103 includes a third light-emitting sublayer 033. The first light-emitting sublayer 031 emits red light, the second light-emitting sublayer 032 emits green light, and the third light-emitting sublayer 033 emits blue light. At least one of the first, second, and third light-emitting sublayers includes a third material. In this embodiment, it is described as an example where all three light-emitting sublayers include a third material. Specifically, the bandgap of the third material in the first light-emitting sublayer is 1.5 eV to 2.5 eV; and / or, the bandgap of the third material in the second light-emitting sublayer is 1.88 eV to 2.88 eV; and / or, the bandgap of the third material in the third light-emitting sublayer is 2.2 eV to 3.2 eV. In this embodiment, by using third materials with different bandgap widths in the light-emitting sublayers of different emission colors, more precise control of the exciton utilization rate of light-emitting devices of different emission colors is achieved, ensuring the exciton recombination rate in light-emitting devices of different emission colors, further adjusting the effect of narrowing the emission spectrum of each color light-emitting device, and ultimately achieving a wide color gamut display on the display panel. It should be noted that although each film layer in the three light-emitting devices shown in the figure is independently set, in reality, some common layers, such as the cathode, can be fabricated in the same process or as a single layer. The attached figures are for illustrative purposes only.

[0040] Understandably, in other embodiments of the present invention, at least one of the first, second, and third light-emitting sub-layers of different emitting colors can be configured as two-layer stacked light-emitting layers, or as three or more-layer stacked light-emitting layers. When the first, second, and third light-emitting sub-layers are configured as two-layer stacked light-emitting layers, the third material layer is disposed between the two stacked light-emitting layers. Understandably, when three or more light-emitting layers are stacked, the third material layer can be disposed between the stacked multiple light-emitting layers.

[0041] Optionally, in some embodiments of the present invention, the third material includes a perovskite material with the chemical formula ABX3, wherein A is a cation, B is a metal cation, and X is an anion. Specifically, A can be an organic cation or an inorganic cation. Further, in some embodiments of the present invention, A is selected from cesium and formamidinium; B is selected from lead and tin; and X is selected from halogens. Optionally, in some embodiments of the present invention, X is selected from iodine, bromine, and chlorine. A is located at the vertex of the cube in the crystal structure, B is located at the center of the cube in the crystal structure, and X is located at the face center of the cube in the crystal structure, connecting adjacent B-position cations. The synthesis route of perovskite material is simple, and different emission spectra can be obtained by changing the proportion of X in the perovskite material structure, which is more conducive to the adjustment and application of the emission spectra of different light-emitting devices in display panels.

[0042] Optionally, in some embodiments of the present invention, the light-emitting layer 03 includes a first material, a second material, and a third material, wherein the mass of the third material accounts for 0.25% to 15% of the mass of the light-emitting layer, that is, the mass ratio of the third material to the light-emitting layer is 0.25% to 15%. Adjusting the mass ratio of the third material in the light-emitting layer can improve exciton utilization while avoiding the generation of defect states in the third material, ensuring the effect of narrowing the emission spectrum. Further, in some other embodiments of the present invention, the mass of the third material accounts for 0.5% to 10% of the mass of the light-emitting layer. This setting can further ensure the exciton recombination rate and improve exciton utilization. Specifically, the mass ratio of the third material in the mass of the light-emitting layer can be 0.25%, 0.35%, 0.5%, 0.9%, 1.5%, 2.8%, 4%, 6%, 7.5%, 8%, 10%, 11.5%, 13.7%, or 15%.

[0043] Optionally, in some embodiments of the present invention, the light-emitting layer includes a first material, a second material, a third material, and a fourth material. The first material serves as the host material, the second material is a phosphorescent material, and the fourth material is a fluorescent material. Adding perovskite material to a display device employing the host material, phosphorescent material, and fluorescent material can also improve exciton utilization and achieve a narrowed emission spectrum. Further, in some embodiments of the present invention, the triplet energy level of the third material is lower than that of the fourth material, and the singlet energy level of the third material is lower than that of the second material. This configuration avoids energy transfer between the third and fourth materials, improves exciton utilization, achieves a narrowed emission spectrum, and ultimately enables a wide color gamut display on the display panel.

[0044] Alternatively, in some embodiments of the present invention, see [reference needed]. Figure 4The following explanation uses a two-layer light-emitting structure as an example. Specifically, the display panel 1 includes a substrate 10, and an organic electroluminescent device 100 is disposed on the substrate 10. The organic electroluminescent device 100 includes a first electrode 01, a first light-emitting layer 03, a second light-emitting layer 04, a second electrode 02, and a third material layer 05. The first light-emitting layer 03 is disposed above the first electrode 01, the second light-emitting layer 04 is disposed on the side of the first light-emitting layer 03 away from the first electrode 01, and the second electrode 02 is disposed on the side of the second light-emitting layer 04 away from the first light-emitting layer 03. The first light-emitting layer 03 includes a first material and a second material, and the second light-emitting layer 04 includes both a first material and a second material. The triplet energy level of the first material is higher than that of the second material, and the singlet energy level of the first material is higher than that of the second material. The third material layer 05 is disposed between the first light-emitting layer 03 and the second light-emitting layer 04. The third material in the third material layer 05 includes a perovskite material, and the singlet energy level of the second material is higher than that of the third material, and the triplet energy level of the second material is higher than that of the third material.

[0045] In this embodiment, the organic electroluminescent device 100 further includes an electron blocking layer 06 and a hole blocking layer 07. The hole blocking layer 07 is located on the side of the second light-emitting layer 04 near the second electrode 02, and the electron blocking layer 06 is located on the side of the first light-emitting layer 03 near the first electrode 01. The surface of the third material layer 05 near the first electrode 01 is the first surface, and the distance between the first surface and the electron blocking layer 06 is h. The surface of the third material layer near the second electrode is the second surface. When the second surface is in direct contact with the hole blocking layer, the distance between the first surface and the electron blocking layer is hmax, and the ratio of h to hmax is 0 to 1. With this configuration, the performance of the display panel can be improved by adjusting the position of the third material layer. Further, in some embodiments of the present invention, the ratio of h to hmax is 0.2 to 0.4. Setting the position of the third material layer within this range allows it to be closer to the peak region of the exciton recombination region, thereby improving exciton utilization. Specifically, the ratio of h to hmax can be 0.16, 0.2, 0.27, 0.35, 0.4, 0.58, 0.65, or 0.8.

[0046] Furthermore, in some other embodiments of the present invention, the example is described by providing three organic electroluminescent devices in a display panel, each organic electroluminescent device having two light-emitting layers. Specifically, see [link to documentation]. Figure 5The display panel 1 includes a substrate 10, a first light-emitting device 101, a second light-emitting device 102, and a third light-emitting device 103. The first light-emitting device 101, the second light-emitting device 102, and the third light-emitting device 103 are disposed on the substrate 10. The first light-emitting device 101 includes two stacked first light-emitting sub-layers 031, the second light-emitting device 102 includes two stacked second light-emitting sub-layers 032, and the third light-emitting device 103 includes two stacked third light-emitting sub-layers 033. The first light-emitting sub-layers 031 emit red light, the second light-emitting sub-layers 032 emit green light, and the third light-emitting sub-layers 033 emit blue light. The first light-emitting device 101, the second light-emitting device 102, and the third light-emitting device 103 also include an electron blocking layer 06 and a hole blocking layer 07, with the two first light-emitting sub-layers 031, the two second light-emitting sub-layers 032, and the two third light-emitting sub-layers 033 respectively located between the electron blocking layer 06 and the hole blocking layer 07. In this embodiment, a third material layer 05 is disposed between the two stacked first light-emitting sublayers 031, the two stacked second light-emitting sublayers 032, and the two stacked third light-emitting sublayers 033. The surface of the third material layer 05 closest to the first electrode is the first surface, and the distance between the first surface and the electron blocking layer 06 is h. The surface of the third material layer 05 closest to the second electrode is the second surface, and when the second surface is in direct contact with the hole blocking layer 07, the distance between the first surface and the electron blocking layer 06 is hmax. The ratio of h to hmax can be the same in the first light-emitting device 101, the second light-emitting device 102, and the third light-emitting device 103. In this embodiment, all light-emitting devices of different colors adopt a two-layer stacked arrangement of light-emitting sublayers, and a perovskite material layer is disposed between the two light-emitting sublayers. The perovskite material layer is disposed in the same position in all different color light-emitting devices, which can improve exciton utilization while simplifying the fabrication process. It should be noted that although the film layers in the three light-emitting devices shown in the figure are independently configured, in practice, for some common layers, such as the electron blocking layer, hole blocking layer, and cathode, the cathode can be fabricated in the same process or as a single layer. The attached figure is for illustrative purposes only.

[0047] Furthermore, in some other embodiments of the present invention, the ratio of h to hmax in the first light-emitting device 101 is 0.1 to 0.4, the ratio of h to hmax in the second light-emitting device 102 is 0.2 to 0.85, and the ratio of h to hmax in the third light-emitting device 103 is 0.2 to 0.85. Specifically, the ratio of h to hmax in the first light-emitting device 101 can be 0.2, the ratio of h to hmax in the second light-emitting device can be 0.35, and the ratio of h to hmax in the third light-emitting device 103 can be 0.6. It is understood that each light-emitting device can also be set with other ratios. In this embodiment, in the different color light-emitting devices with two layers of light-emitting sub-layers stacked together, the perovskite material layer has its own preferred setting position, which can better adjust the exciton utilization rate of different light-emitting devices, achieve the effect of narrowing the emission spectrum, and ultimately achieve a wide color gamut display of the display panel.

[0048] 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.

[0049] 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.

[0050] 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.

[0051] A second aspect of this invention provides a display device, which may include the display panel 1 described in the above embodiments. The display device may be an electronic paper device, mobile phone, tablet computer, television, monitor, laptop computer, digital photo frame, smart bracelet, smartwatch, supercomputer, navigator, wireless device, personal digital assistant (PDA), handheld or portable computer, GPS receiver / navigator, camera, MP4 video player, camcorder, game console, clock, calculator, television monitor, computer monitor, automotive display (e.g., odometer display), cockpit controller and / or display, camera view display (e.g., display of a rearview camera in a vehicle), electronic billboard or sign, projector, or other mobile or fixed terminal. Since this display device includes the display panel described in this application, it has the same effect as the display panel 1 in the above embodiments, enabling wide color gamut display.

[0052] The inventors conducted experimental research to obtain the implementation scheme of this application. The technical effects of the present invention will be described below in conjunction with the experimental results.

[0053] The following examples were prepared according to 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.

[0054] 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.

[0055] 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, a light-emitting layer, a hole blocking layer, an electron transport layer, and an electron injection layer can be deposited sequentially.

[0056] Step 104: Fabricate a cathode on the electron injection layer. Specifically, a Mg-Ag alloy can be vapor-deposited to form the cathode.

[0057] An organic light-emitting device (OLED) can be formed using steps 101-104, such as forming a blue OLED. When it is necessary to form other colored OLEDs, such as green or red OLEDs, the above steps can be followed. Understandably, when fabricating display panels with different colored OLEDs, different colored light-emitting layers need to be fabricated separately for each OLED, while common layers, such as the anode and cathode, can be fabricated in the same process.

[0058] Furthermore, the fabrication steps of an organic electroluminescent device may also include: Step 105: Prepare a light extraction layer (CPL) above the cathode.

[0059] Step 106: Prepare an encapsulation layer above the CPL layer. The encapsulation layer can be a thin-film encapsulation layer (TFE), which typically has a structure consisting of a first inorganic encapsulation layer, an organic encapsulation layer, and a second inorganic encapsulation layer stacked together.

[0060] In the embodiments and comparative examples, the first and second materials of the hole injection layer, hole transport layer, electron blocking layer, and light-emitting layer, as well as the hole blocking layer, electron transport layer, and electron injection layer, are materials commonly used in the art. For example, the hole transport layer uses an aromatic amine compound, the electron transport layer uses a triazine compound, the hole blocking layer uses a triazine compound, and the first material of the light-emitting layer uses a p-type carbazole compound or an n-type triazine compound; the second material uses a metal complex or a boron-nitrogen compound. The first electrode adopts an ITO / Ag / ITO structure. The second electrode uses a Mg-Ag alloy with a Mg:Ag ratio of 1:9.

[0061] Example 1 An organic electroluminescent device has the following structure: a first electrode / hole injection layer (100 Å) / hole transport layer (1200 Å) / electron blocking layer (50 Å) / light-emitting layer (400 Å) / hole blocking layer (50 Å) / electron transport layer (280 Å) / electron injection layer (10 Å) / second electrode. The light-emitting layer uses a first material, a second material, and a third material. The third material is a perovskite material with a full width at half maximum (FWHM) of 30 nm. The mass percentage of the third material in the light-emitting layer is 0.25%.

[0062] Example 2 The difference from Example 1 is that the full width at half maximum (FWHM) of the third material is 15 nm.

[0063] Example 3 The difference from Example 1 is that the full width at half maximum (FWHM) of the third material is 22 nm.

[0064] Example 4 The difference from Example 1 is that the full width at half maximum (FWHM) of the third material is 27 nm.

[0065] Example 5 The difference from Example 1 is that the mass of the third material accounts for 0.4% of the light-emitting layer.

[0066] Example 6 The difference from Example 1 is that the mass of the third material accounts for 0.5% of the light-emitting layer.

[0067] Example 7 The difference from Example 1 is that the mass of the third material accounts for 1.5% of the light-emitting layer.

[0068] Example 8 The difference from Example 1 is that the mass of the third material accounts for 2.8% of the light-emitting layer.

[0069] Example 9 The difference from Example 1 is that the mass of the third material accounts for 6% of the light-emitting layer.

[0070] Example 10 The difference from Example 1 is that the mass of the third material accounts for 8% of the light-emitting layer.

[0071] Example 11 The difference from Example 1 is that the mass of the third material accounts for 10% of the light-emitting layer.

[0072] Example 12 The difference from Example 1 is that the mass of the third material accounts for 13.7% of the light-emitting layer.

[0073] Example 13 The difference from Example 1 is that the mass of the third material accounts for 15% of the light-emitting layer.

[0074] Example 14 The difference from Example 1 is that the mass of the third material accounts for 20% of the light-emitting layer.

[0075] Example 15 The difference from Example 1 is that the mass of the third material accounts for 0.2% of the light-emitting layer.

[0076] Example 16 An organic electroluminescent device has the following structure: a first electrode / hole injection layer / hole transport layer / electron blocking layer / first emitting layer / third material layer / second emitting layer / hole blocking layer / electron transport layer / electron injection layer / second electrode. The first and second emitting layers utilize a first material and a second material, respectively. The third material layer utilizes a perovskite material with a full width at half maximum (FWHM) of 30 nm. The ratio of h to hmax is 0.2.

[0077] Example 17 The difference from Example 16 is that the ratio of h to hmax is 0.28.

[0078] Example 18 The difference from Example 16 is that the ratio of h to hmax is 0.4.

[0079] Example 19 The difference from Example 16 is that the ratio of h to hmax is 0.6.

[0080] Example 20 The difference from Example 16 is that the ratio of h to hmax is 0.13.

[0081] Example 21 The difference from Example 16 is that the ratio of h to hmax is 0.35.

[0082] Example 22 The difference from Example 16 is that the ratio of h to hmax is 0.85.

[0083] Comparative Example 1 The difference from Example 1 is that the light-emitting layer uses a first material and a second material.

[0084] Comparative Example 2 The difference from Example 1 is that the light-emitting layer uses a first material and a second material, and the hole transport layer is doped with a third material. The third material is a perovskite material with a full width at half maximum (FWHM) of 30 nm and a mass ratio of 0.25% in the hole transport layer.

[0085] The devices from the examples and comparative examples underwent full width at half maximum (FWHM) testing. The FWHM test was conducted at 5000 cd / m². 2 The results were obtained using a Photo Research PR 750 radiometer at the specified brightness. The test results are shown in Table 1.

[0086] Table 1

[0087] As demonstrated in Examples 1-22 and Comparative Example 1, introducing perovskite material within or between the light-emitting layers of an organic electroluminescent device is beneficial for improving exciton utilization and achieving a narrower emission spectrum. As demonstrated in Examples 1-22 and Comparative Example 2, introducing perovskite material within or between the light-emitting layers is more advantageous than doping perovskite material in the hole transport layer.

[0088] 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.

[0089] 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. A display panel, characterized in that, Includes at least one organic electroluminescent device, said organic electroluminescent device comprising: First electrode, At least one light-emitting layer is located on the first electrode. The light-emitting layer comprises a first material and a second material, wherein the triplet energy level of the first material is higher than the triplet energy level of the second material. The second electrode is located on the at least one light-emitting layer. The third material, including perovskite materials, has a higher singlet energy level than the second material. Wherein, the light-emitting layer includes the third material, and / or, the at least one light-emitting layer includes a first light-emitting layer and a second light-emitting layer stacked together, with the third material layer disposed between the first light-emitting layer and the second light-emitting layer.

2. The display panel according to claim 1, characterized in that, The third material includes a narrow-spectrum perovskite material, preferably, the full width at half maximum (FWHM) of the third material is less than or equal to 30 nm.

3. The display panel according to claim 1, characterized in that, The band gap of the perovskite material is 1.3 eV to 3.3 eV.

4. The display panel according to claim 3, characterized in that, At least one organic electroluminescent device includes a first light-emitting device, a second light-emitting device, and a third light-emitting device. The first light-emitting device includes at least one first light-emitting sublayer, the second light-emitting device includes at least one second light-emitting sublayer, and the third light-emitting device includes at least one third light-emitting sublayer. The first light-emitting sublayer emits red light, the second light-emitting sublayer emits green light, and the third light-emitting sublayer emits blue light. The band gap of the third material in the first light-emitting sublayer is 1.5 eV to 2.5 eV; and / or, the band gap of the third material in the second light-emitting sublayer is 1.88 eV to 2.88 eV; and / or, the band gap of the third material in the third light-emitting sublayer is 2.2 eV to 3.2 eV.

5. The display panel according to claim 1, characterized in that, The chemical formula of the perovskite material is ABX3, where A is a cation, B is a metal cation, and X is an anion; A is selected from cesium and formamidinium; B is selected from lead and tin; and X is selected from halogens. Preferably, X is selected from iodine, bromine, and chlorine.

6. The display panel according to claim 1, characterized in that, The mass of the third material accounts for 0.25% to 15% of the mass of the light-emitting layer. Preferably, the mass of the third material accounts for 0.5% to 10% of the mass of the light-emitting layer.

7. The display panel according to claim 1, characterized in that, The light-emitting layer comprises a first material, a second material, a third material, and a fourth material, wherein the first material is the main material, the second material is a phosphorescent material, and the fourth material is a fluorescent material. Preferably, the triplet energy level of the third material is lower than the triplet energy level of the fourth material, and the singlet energy level of the third material is lower than the singlet energy level of the second material.

8. The display panel according to claim 1, characterized in that, The at least one light-emitting layer includes a first light-emitting layer and a second light-emitting layer stacked together, a third material layer is disposed between the first light-emitting layer and the second light-emitting layer, and the second light-emitting layer is disposed on the side of the first light-emitting layer away from the first electrode; It also includes a hole blocking layer and an electron blocking layer, wherein the hole blocking layer is located on the side of the second light-emitting layer near the second electrode, and the electron blocking layer is located on the side of the first light-emitting layer near the first electrode.

9. The display panel according to claim 8, characterized in that, The surface of the third material layer closest to the first electrode is the first surface, and the distance between the first surface and the electron blocking layer is h. The surface of the third material layer closest to the second electrode is the second surface. When the second surface is in direct contact with the hole blocking layer, the distance between the first surface and the electron blocking layer is hmax, and h / hmax is 0 to 1. Preferably, h / hmax is 0.2 to 0.

4.

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

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