Display panel, test method thereof and display device

Abstract

The invention relates to the technical field of display, in particular to a display panel, a test method thereof and a display device. The display panel comprises a substrate and a plurality of sub-pixels located on one side of the substrate. The ratio of capacitance change values of two sub-pixels with different light emitting colors is larger than or equal to a first threshold value and smaller than or equal to a second threshold value, the first threshold value is smaller than or equal to 1, the second threshold value is larger than or equal to 1, the capacitance change values are used for representing the difference between the initial capacitance and the first capacitance of the sub-pixels, and the second threshold value is used for representing the difference between the initial capacitance and the first capacitance of the sub-pixels. The initial capacitance is the capacitance of the sub-pixel when the brightness of the display panel is initial brightness, and the first capacitance is the capacitance of the sub-pixel when the brightness of the display panel is attenuated to target brightness.

Description

Display panel, testing method thereof, and display device

[0001] This disclosure claims priority to the PCT international patent application filed with the China Patent Office on May 18, 2023, with application number PCT / CN2023 / 095139 and titled “Display Panel, Test Method Thereof, and Display Device,” the entire contents of which are incorporated by reference into this disclosure. Technical Field

[0002] The embodiments of the present disclosure relate to the field of display technology, and in particular, to a display panel and a testing method thereof, and a display device. Background Art

[0003] Organic light-emitting diodes (OLEDs) offer a wide range of applications due to their solid-state, autonomous illumination, high brightness, high resolution, wide viewing angle, fast response, thinness, compact size, light weight, flexible substrate compatibility, low-voltage DC drive, low power consumption, and wide operating temperature range. The numerous layered structures of OLED devices make the interface structure crucial to device performance (such as current density, brightness, luminous efficiency, and stability).

[0004] Summary of the Invention

[0005] This disclosure adopts the following technical solutions:

[0006] A first aspect of the present disclosure provides a display panel, comprising:

[0007] a substrate and a plurality of sub-pixels located on one side of the substrate;

[0008] The ratio of the capacitance change values ​​of two sub-pixels with different luminous colors is greater than or equal to a first threshold and less than or equal to a second threshold, the first threshold is less than or equal to 1, and the second threshold is greater than or equal to 1, wherein the capacitance change value is used to characterize the difference between the initial capacitance of the sub-pixel and the first capacitance, the initial capacitance is the capacitance of the sub-pixel when the brightness of the display panel is the initial brightness, and the first capacitance is the capacitance of the sub-pixel when the brightness of the display panel decays to the target brightness.

[0009] In an optional implementation, a brightness ratio of the target brightness to the initial brightness is greater than or equal to 50% and less than or equal to 90%.

[0010] In an optional implementation, the first threshold is greater than or equal to 0.7 and less than or equal to 1; the second threshold is greater than or equal to 1 and less than or equal to 1.3.

[0011] In an optional implementation, the sub-pixel includes:

[0012] A first electrode, a light-emitting layer, and a second electrode are sequentially stacked on one side of the substrate;

[0013] a first carrier layer and a second carrier layer, wherein the first carrier layer is disposed between the first electrode and the light-emitting layer, and the second carrier layer is disposed between the second electrode and the light-emitting layer.

[0014] In an optional embodiment, when the first electrode is an anode and the second electrode is a cathode, the first carrier layer includes:

[0015] at least one layer of a hole injection layer, a hole transport layer, and an electron blocking layer, wherein the hole injection layer, the hole transport layer, and the electron blocking layer are sequentially stacked between the anode and the light-emitting layer along a first direction, wherein the first direction is a direction from the anode to the cathode;

[0016] The second carrier layer includes:

[0017] At least one layer of a hole blocking layer, an electron transport layer, and an electron injection layer, wherein the hole blocking layer, the electron transport layer, and the electron injection layer are sequentially stacked along the first direction between the light emitting layer and the cathode.

[0018] In an optional embodiment, the HOMO energy level of the hole transport layer is greater than or equal to -5.8 eV and less than or equal to -5.0 eV.

[0019] In an optional embodiment, the HOMO energy level of the electron blocking layer is greater than or equal to -5.8 eV and less than or equal to -5.0 eV.

[0020] In an optional embodiment, the LUMO energy level of the hole blocking layer is greater than or equal to -3.5 eV and less than or equal to -2.5 eV.

[0021] In an optional embodiment, the LUMO energy level of the electron transport layer is greater than or equal to -3.5 eV and less than or equal to -2.5 eV.

[0022] In an optional embodiment, the material of the electron injection layer includes any one or more of a low work function metal electron injection material and a metal salt electron injection material.

[0023] In an optional embodiment, the material of the hole injection layer includes any one or more of a hole injection material and a P-type doping material, and the hole injection material includes any one or more of copper phthalocyanine, 2,3,6,7,10,11-hexacyano-1,4,5,8,9,12-hexaazatriphenylene, and MnO3.

[0024] In an optional embodiment, the sub-pixels include at least a red sub-pixel, a green sub-pixel, and a blue sub-pixel, the material of the light-emitting layer of the red sub-pixel includes a red light-emitting material, the material of the light-emitting layer of the green sub-pixel includes a green light-emitting material, and the material of the light-emitting layer of the blue sub-pixel includes a blue light-emitting material;

[0025] The red luminescent material includes any one or more of a DCM series of red luminescent materials and a metal complex series of red luminescent materials;

[0026] The blue luminescent material includes any one or more of pyrene derivative blue luminescent materials, anthracene derivative blue luminescent materials, fluorene derivative blue luminescent materials, perylene derivative blue luminescent materials, styrylamine derivative blue luminescent materials and metal complex blue luminescent materials;

[0027] The green luminescent material includes any one or more of coumarin dye green luminescent materials, quinacridone copper derivative green luminescent materials, polycyclic aromatic hydrocarbon green luminescent materials, diamine anthracene derivative green luminescent materials, carbazole derivative green luminescent materials and metal complex green luminescent materials.

[0028] In an optional embodiment, the red light-emitting material includes any one or more of 4-(dicyanomethylene)-2-methyl-6-(4-dimethylaminophenylvinyl)-4H-pyran, 4-(dicyanomethylene)-2-tert-butyl-6-(1,1,7,7-tetramethyljulonidine-9-enyl)-4H-pyran, bis(1-phenylisoquinoline)(acetylacetonate)iridium(III), octaethylporphyrin platinum, and bis(2-(2'-benzothienyl)pyridine-N,C3')(acetylacetonate)iridium.

[0029] In an optional embodiment, the green light-emitting material includes any one or more of coumarin 6, coumarin 545T, quinacridone copper, N,N'-dimethylquinacridone, 5,12-diphenylnaphthyl naphthalene, N10,N10'-diphenyl-N10,N10'-diphthaloyl-9,9'-dianthracene-10,10'-diamine, tris(8-hydroxyquinoline)aluminum(III), tris(2-phenylpyridine)iridium, and di(2-phenylpyridine)iridium acetylacetonate.

[0030] In an optional embodiment, the blue light-emitting material includes any one or more of N1,N6-di([1,1'-biphenyl]-2-yl)-N1,N6-di([1,1'-biphenyl]-4-yl)pyrene-1,6-diamine, 9,10-di-(2-naphthyl)anthracene, 2-methyl-9,10-di-2-naphthylanthracene, 2,5,8,11-tetra-tert-butylperylene, 4,4'-bis[4-(diphenylamino)phenylvinyl]biphenyl, 4,4'-bis[4-(di-p-tolylamino)phenylvinyl]biphenyl, and bis(4,6-difluorophenylpyridine-C2,N)picolinyliridium.

[0031] Based on the same inventive concept, a second aspect of the present disclosure provides a display device, comprising the display panel as described in any one of the first aspects;

[0032] a driving circuit, configured to provide a driving signal to the display panel;

[0033] A power supply circuit is used to provide a power signal to the display panel.

[0034] Based on the same inventive concept, a third aspect of the present disclosure provides a method for testing a display panel, the display panel comprising a substrate and a plurality of sub-pixels located on one side of the substrate, the method comprising:

[0035] When the brightness of the display panel is at an initial brightness, obtaining an initial capacitance of the sub-pixel;

[0036] When the brightness of the display panel is at a target brightness, obtaining a first capacitance of the sub-pixel;

[0037] Comparing the initial capacitance of the sub-pixel with the first capacitance to obtain a capacitance change value of the sub-pixel;

[0038] Calculating a ratio of capacitance change values ​​of two sub-pixels of different colors;

[0039] If the ratio is greater than or equal to a first threshold and less than or equal to a second threshold, it is determined that the display panel test has passed.

[0040] In an optional embodiment, the plurality of sub-pixels include a first color sub-pixel, and the step of obtaining the initial capacitance of the sub-pixel when the brightness of the display panel is at an initial brightness includes:

[0041] When the brightness of the display panel is at an initial brightness, controlling a first color sub-pixel in the display panel to emit light;

[0042] testing a capacitance-voltage relationship of the first color sub-pixel;

[0043] An initial capacitance of the first color sub-pixel is obtained according to the capacitance-voltage relationship of the first color sub-pixel.

[0044] In an optional embodiment, the plurality of sub-pixels include a second color sub-pixel, and the step of obtaining the first capacitance of the sub-pixel when the brightness of the display panel is a target brightness includes:

[0045] When the brightness of the display panel is at a target brightness, controlling the second color sub-pixel in the display panel to emit light;

[0046] testing a capacitance-voltage relationship of the second color sub-pixel;

[0047] The first capacitance of the second color sub-pixel is obtained according to the capacitance-voltage relationship of the second color sub-pixel.

[0048] In an optional implementation, the step of comparing the initial capacitance of the sub-pixel with the first capacitance to obtain the capacitance change value of the sub-pixel includes:

[0049] The ratio of the initial capacitance of the sub-pixel to the first capacitance is calculated to obtain a capacitance change value of the sub-pixel.

[0050] The above description is only an overview of the technical solution of the present disclosure. In order to more clearly understand the technical means of the present disclosure, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present disclosure more obvious and easy to understand, the specific implementation methods of the present disclosure are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] In order to more clearly illustrate the technical solutions in the embodiments of the present disclosure or related technologies, the following is a brief introduction to the drawings required for use in the embodiments or related technical descriptions. Obviously, the drawings described below are some embodiments of the present disclosure. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0052] FIG1 schematically shows a structural diagram of a display panel proposed in the present disclosure;

[0053] FIG2 schematically shows a capacitance-voltage relationship curve of a red sub-pixel in a display panel of a comparative example proposed in the present disclosure;

[0054] FIG3 schematically shows a capacitance-voltage relationship curve of a green sub-pixel in a display panel of a comparative example proposed in the present disclosure;

[0055] FIG4 schematically shows a capacitance-voltage relationship curve of a blue sub-pixel in a display panel of a comparative example proposed in the present disclosure;

[0056] FIG5 schematically shows a capacitance-voltage relationship curve of a green sub-pixel in a display panel according to Example 1 of the present disclosure;

[0057] FIG6 schematically shows a flow chart of a display panel testing method proposed in the present disclosure.

[0058] Description of the drawings: 11. Substrate; 12. Pixel defining layer; 13. Sub-pixel; 13R. Red sub-pixel; 13G. Green sub-pixel; 13B. Blue sub-pixel; 131. First electrode; 132. Second electrode; 133. Light-emitting layer; 134. Hole transport layer; 135. Electron transport layer; 136. Hole injection layer; 137. Electron injection layer; 138. Electron blocking layer; 139. Hole blocking layer; 10R. Red driving circuit; 10G. Green driving circuit; 10B. Blue driving circuit; Q. Opening. Specific embodiments

[0059] To make the objectives, technical solutions, and advantages of the embodiments of the present disclosure more clear, the technical solutions in the embodiments of the present disclosure will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present disclosure, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present disclosure without making any creative efforts shall fall within the scope of protection of the present disclosure.

[0060] Display screens are continuously developing towards high pixels, large color gamut, and low power consumption. OLED (organic light-emitting diode) flexible displays have significant advantages over TFT-LCDs, such as foldability and bendability, making flexible screens a trend in display screen development and highly favored by electronic device enthusiasts. Therefore, the requirements for the efficiency and lifespan of OLED devices in the field are becoming increasingly higher. Although many high-efficiency, long-life OLED devices that meet practical needs have been developed, in actual use, they still cannot fully meet the display effects currently sought after in the industry. In addition to pursuing color saturation and brightness, color display accuracy has become a key focus today.

[0061] OLED devices have numerous layered structures. Due to the differences in the physical and chemical properties of the various layers of materials that make up OLED devices, the OLED devices themselves have two-dimensional interfaces with a thickness of several to dozens of atoms, such as the anode / organic layer interface, the organic layer / organic layer interface, the organic layer / cathode interface, and the intra-layer interface. These interface structures are important components of the device structure. Since the various interfaces of the device directly affect the injection, transport, and diffusion of carriers within the device, as well as the formation, diffusion, and quenching of excitons, the interface structure in OLED devices plays a decisive role in device performance (such as current density, luminous brightness, luminous efficiency, and stability).

[0062] However, these numerous layered structures also lead to the existence of interface barriers, especially the inevitable accumulation of charge at the interface during operation, which can cause changes in device performance. A color display panel is composed of multiple sub-pixels (such as RGB sub-pixels) with different luminous colors. Due to the electric field within the OLED or the electric field changes caused by charge accumulation at the interface during use, the balance between sub-pixels with different luminous colors is disrupted. In other words, the efficiency or operating voltage of sub-pixels with different luminous colors vary, resulting in color display accuracy issues such as color difference, which seriously affects the consumer experience.

[0063] In view of this, the present disclosure proposes a display panel. FIG1 schematically shows a structural diagram of a display panel proposed in the present disclosure. As shown in FIG1 , the display panel includes:

[0064] A substrate 11; a plurality of sub-pixels 13 (taking the RGB sub-pixels in FIG1 as an example, including a blue sub-pixel 13B, a green sub-pixel 13G, and a red sub-pixel 13R), wherein the sub-pixels are located on one side of the substrate 11, wherein the plurality of sub-pixels 13 may be all or part of the sub-pixels included in the display substrate.

[0065] In the embodiment of the present disclosure, the display panel can be a display panel that emits white light, or a display panel that emits colored light (color-adjustable light). The display panel can emit white light or colored light by controlling the luminous brightness of multiple sub-pixels with different luminous colors. Taking the RGB sub-pixels in Figure 1 as an example, by controlling the blue sub-pixel 13B, the red sub-pixel 13R, and the green sub-pixel 13G to emit light at the same time, the display panel can display mixed light of the blue sub-pixel 13B, the red sub-pixel 13R, and the green sub-pixel 13G, so that the light-emitting substrate 1 presents white light; by controlling the luminous brightness of the blue sub-pixel 13B, the red sub-pixel 13R, and the green sub-pixel 13G, the color and brightness of the mixed light emitted by the display panel can be controlled, thereby achieving colored light emission.

[0066] In the embodiment of the present disclosure, the ratio of the capacitance change values ​​of two sub-pixels with different luminous colors is greater than or equal to a first threshold value and less than or equal to a second threshold value, the first threshold value is less than or equal to 1, and the second threshold value is greater than or equal to 1, wherein the capacitance change value is used to characterize the difference between the initial capacitance of the sub-pixel and the first capacitance, the initial capacitance is the capacitance of the sub-pixel when the brightness of the display panel is the initial brightness, and the first capacitance is the capacitance of the sub-pixel when the brightness of the display panel decays to the target brightness. The initial capacitance can be the capacitance of the sub-pixel at the target voltage when the brightness of the display panel is the initial brightness, and the first capacitance can be the capacitance of the sub-pixel at the target voltage when the brightness of the display panel decays to the target brightness; preferably, the initial capacitance is the maximum capacitance of the sub-pixel at each voltage when the brightness of the display panel is the initial brightness, and the first capacitance is the maximum capacitance of the sub-pixel at each voltage when the brightness of the display panel decays to the target brightness.

[0067] In an embodiment of the present disclosure, when the brightness of the display panel is the initial brightness or the target brightness, in the process of applying the target voltage to the sub-pixels of the display panel, the holes generated by the anode and the electrons generated by the cathode move to the light-emitting layer in the sub-pixel through the organic layer structure of the sub-pixel. At the target voltage, the holes and the electrons are concentrated on the interface between different hierarchical structures, wherein a plurality of capacitors in parallel are formed between the hierarchical structure interface where the electrons are distributed and the hierarchical structure interface where the holes are distributed, and the above-mentioned multiple capacitors at the target voltage are combined into the initial capacitor.

[0068] Among them, the initial capacitance can be the capacitance of a single sub-pixel when the brightness of the display panel is the initial brightness, or it can be the capacitance of the display panel (all luminous sub-pixels) when the brightness of the display panel is the initial brightness; the initial capacitance can be the capacitance of a single sub-pixel when the brightness of the display panel is the target brightness, or it can be the capacitance of the display panel (all luminous sub-pixels) when the brightness of the display panel is the target brightness.

[0069] The capacitance change value of a subpixel is used to represent the difference between the initial capacitance and the first capacitance, thereby measuring the capacitance state of the subpixel in the display panel after brightness decay based on the pixel change value. The capacitance change value can be the difference between the initial capacitance of the subpixel and the first capacitance, or the ratio between the initial capacitance of the subpixel and the first capacitance. The specific capacitance change value can be determined based on actual conditions and is not limited by this disclosure.

[0070] The initial brightness is the brightness of the display device in the initial state, and the initial state is the luminous state of the display device when the brightness of the display panel has not decayed; the target brightness is the brightness of the display device after the initial brightness decays. In an optional embodiment, the brightness ratio of the target brightness to the initial brightness is greater than or equal to 50%, and less than or equal to 90%. For example, the target brightness is 90% of the initial brightness, indicating that the target brightness is the brightness when the brightness of the display panel of the display device in the initial state decays to 90% of the initial brightness. It should be noted that the above example is only an optional solution proposed by the present disclosure to enable those skilled in the art to better understand the specific brightness ratio of the target brightness to the initial brightness. The present disclosure does not limit this.

[0071] In an optional embodiment, the first threshold value is greater than or equal to 0.7 and less than or equal to 1; the second threshold value is greater than or equal to 1 and less than or equal to 1.3. The ratio of the capacitance change value between two sub-pixels with different luminous colors in the display panel described in the present disclosure is greater than or equal to the first threshold value and less than or equal to the second threshold value. Preferably, the first threshold value is 0.8, the second threshold value is 1.25, and the ratio of the capacitance change value between two sub-pixels with different luminous colors in the display panel described in the present disclosure is greater than or equal to 0.8 and less than or equal to 1.25.

[0072] In the case of a display panel using the present disclosure, the ratio of the capacitance change between two sub-pixels of different luminous colors is between a first threshold value and a second threshold value. This indicates that the color display effect of a display device using the display panel described in the present disclosure remains essentially unchanged in its initial state and during use, indicating that the capacitance change between sub-pixels of different luminous colors in the display panel described in the present disclosure is in a relatively balanced state, that is, the efficiency or operating voltage change levels of sub-pixels of different luminous colors are essentially the same, and color display accuracy issues such as color difference will not occur, greatly improving the user experience. In contrast, in a display device that does not use the display panel described in the present disclosure, the ratio of the capacitance change between two sub-pixels of different luminous colors is not within the range between the first threshold value and the second threshold value. This disrupts the capacitance balance between sub-pixels of different luminous colors, and the efficiency or operating voltage change levels of sub-pixels of different luminous colors are inconsistent, resulting in undesirable phenomena such as color difference, which seriously affects the user experience.

[0073] The display panel provided by the present disclosure features capacitance variations that differ depending on the layer structures within different subpixels. By adjusting the materials within each layer within the subpixel, the ratio of capacitance variations between two subpixels emitting different colors on the display panel is adjusted to fall within a range between a first threshold and a second threshold, thereby preventing inaccurate color display on the display panel. The subpixel layer structure is described in detail below.

[0074] In an optional embodiment, as shown in FIG1 , the sub-pixel 13 includes a first electrode 131, a second electrode 132, and a light-emitting layer 133, wherein the first electrode 131, the light-emitting layer 133, and the second electrode 132 are sequentially stacked on one side of the substrate 11; a first carrier layer, wherein the first carrier layer is disposed between the first electrode 131 and the light-emitting layer 133; and a second carrier layer, wherein the second carrier layer is disposed between the second electrode 132 and the light-emitting layer 133. It should be noted that one of the first electrode and the second electrode is an anode and the other is a cathode. When the first electrode is an anode and the second electrode is a cathode, the corresponding display panel is a display panel of a top-emitting display device; when the first electrode is a cathode and the second electrode is an anode, the corresponding display panel is a display panel of a bottom-emitting display device. The specific first electrode and the second electrode can be determined according to actual conditions, and the present disclosure does not limit this.

[0075] Next, we will use the display panel of a top-emission display device as an example to describe the layer structures that may be included in the first and second carrier layers. As shown in Figure 1, when the first electrode 131 is an anode and the second electrode 132 is a cathode, the first carrier layer includes at least one of a hole injection layer (HIL) 136, a hole transport layer (HTL) 134, and an electron block layer (EBL) 138. The hole injection layer 136, the hole transport layer 134, and the electron block layer 138 are stacked in sequence between the first electrode 131 (anode) and the light-emitting layer 133 along a first direction, where the first direction is from the first electrode 131 (anode) to the second electrode 132 (cathode). The electron block layer 138 blocks the diffusion of electrons transmitted by the light-emitting layer 133, confining electrons and holes to the light-emitting layer. This lowers the injection barrier and reduces charge accumulation at the interface, slowing interface degradation and thereby extending the life of the sub-pixel. It should be noted that the first carrier layer may include only any one layer among the hole injection layer 136, the hole transport layer 134 and the electron blocking layer 138, or may include any two layers among the hole injection layer 136, the hole transport layer 134 and the electron blocking layer 138, or may include the hole injection layer 136, the hole transport layer 134 and the electron blocking layer 138. The specific first carrier layer can be set according to actual conditions, and the present disclosure does not limit this.

[0076] Preferably, the first carrier layer includes a hole injection layer 136, which is arranged on the side of the first electrode 131 away from the substrate 11; a hole transport layer 134, which is arranged on the side of the hole injection layer 136 away from the substrate 11; and an electron blocking layer 138, which is arranged on the side of the hole transport layer 134 away from the substrate 11.

[0077] As shown in FIG1 , when the first electrode 131 is an anode and the second electrode 132 is a cathode, the second carrier layer includes at least one of a hole blocking layer (HBL) 139, an electron transport layer (ETL) 135, and an electron injection layer (EIL) 137. The hole blocking layer 139, the electron transport layer 135, and the electron injection layer 137 are sequentially stacked along the first direction between the light-emitting layer 133 and the second electrode 132 (cathode). The hole blocking layer 139 can block the diffusion of holes transmitted by the light-emitting layer 133, confining the holes to the light-emitting layer, while lowering the injection barrier, reducing interface charge accumulation, and delaying interface degradation, thereby extending the life of the pixel. It should be noted that the second carrier layer may include only any one layer among the hole blocking layer 139, the electron transport layer 135, and the electron injection layer 137, or may include any two layers among the hole blocking layer 139, the electron transport layer 135, and the electron injection layer 137, or may include the hole blocking layer 139, the electron transport layer 135, and the electron injection layer 137. The specific second carrier layer can be set according to actual conditions, and the present disclosure does not impose any restrictions on this.

[0078] Preferably, the second carrier layer includes a hole blocking layer 139, which is arranged on the side of the light-emitting layer 133 away from the substrate 11; an electron transport layer 135, which is arranged on the side of the hole blocking layer 139 away from the substrate 11; and an electron injection layer 137, which is arranged on the side of the electron transport layer 135 away from the substrate 11.

[0079] In an optional embodiment, the anode may be a material having a high work function. For example, the anode may be any one or more of ITO (Indium Tin Oxides), IZO (Indium Zinc Oxide), and composite materials (such as Ag / ITO, Al / ITO, Ag / IZO, Al / IZO, etc., where Ag / ITO is a laminated structure of a metal silver electrode and an ITO electrode).

[0080] In an optional embodiment, the cathode may be a material with a low work function. For example, the cathode may be any one or more of Al, Ag, Mg, and a metal alloy material with a low work function (such as magnesium-aluminum alloy, magnesium-silver alloy, etc.).

[0081] In an optional embodiment, the HOMO energy level of the hole transport layer is greater than or equal to -5.8 eV and less than or equal to -5.0 eV. Using a hole transport material within this HOMO energy level range as a sub-pixel of the hole transport layer makes it easier for the display panel to meet the requirement that the ratio of capacitance change between two sub-pixels of different luminous colors is between a first threshold and a second threshold. Therefore, the hole transport layer is preferably made of a material within this energy level range. Exemplarily, the hole transport layer can be a P-type doped material containing aromatic amine.

[0082] In an optional embodiment, the HOMO energy level of the electron blocking layer is greater than or equal to -5.8eV and less than or equal to -5.0eV. Using an electron blocking material within this HOMO energy level range as a sub-pixel of the electron blocking layer makes it easier for the display panel to meet the requirement that the ratio of the capacitance change value between two sub-pixels with different luminous colors is between a first threshold value and a second threshold value. Therefore, the electron blocking layer is preferably made of a material within this energy level range. Exemplarily, the electron blocking layer can be a P-type doped material containing aromatic amine. The HOMO energy level of the electron blocking layer is preferably greater than or equal to -5.2eV and less than or equal to -5.4eV, so that the display panel can meet the requirement that the ratio of the capacitance change value between two sub-pixels with different luminous colors is more easily between the first threshold value and the second threshold value.

[0083] In an optional embodiment, the LUMO energy level of the hole blocking layer is greater than or equal to -3.5eV and less than or equal to -2.5eV. Using a hole blocking material within this LUMO energy level range as a sub-pixel of the hole blocking layer makes it easier for the display panel to satisfy the ratio of the capacitance change value between two sub-pixels with different luminous colors between the first threshold and the second threshold. Therefore, the hole blocking layer is preferably made of a material within this energy level range, and the thickness of the hole blocking layer is between 10nm and 70nm. Exemplarily, the hole blocking layer can be an organic material doped with LiQ (structural formula as follows), Li, and Ca.

[0084] In an optional embodiment, the LUMO energy level of the electron transport layer is greater than or equal to -3.5eV and less than or equal to -2.5eV. Using electron transport materials within this LUMO energy level range as sub-pixels of the electron transport layer makes it easier for the display panel to meet the requirement that the ratio of the capacitance change value between two sub-pixels with different luminous colors is between the first threshold and the second threshold. Therefore, the electron transport layer is preferably made of materials within this energy level range, and the thickness of the electron transport layer is between 10nm and 70nm. For example, the electron transport layer can be an organic material doped with LiQ, Li, and Ca.

[0085] In an optional embodiment, the material of the electron injection layer includes any one or more of a low work function metal electron injection material and a metal salt electron injection material, and the thickness of the electron injection layer is between 0.5 nm and 2 nm. The electron injection material selected from this category is used as a sub-pixel of the electron injection layer, which makes it easier for the display panel to meet the ratio of the capacitance change value between two sub-pixels with different luminous colors between the first threshold and the second threshold. Exemplarily, the electron injection material can be a low work function metal electron injection material such as Li, Ca and Yb, or a metal salt electron injection material such as metal salt LiF, LiQ (structural formula as above).

[0086] In an optional embodiment, the hole injection layer comprises one or more of a hole injection material and a P-type dopant material. The hole injection material comprises one or more of copper phthalocyanine, 2,3,6,7,10,11-hexacyano-1,4,5,8,9,12-hexaazatriphenylene, and MnO3. The thickness of the hole injection layer is between 5 nm and 30 nm. The P-type dopant material is a material obtained by P-doping a hole transport material. Using a hole injection layer material selected from this category as a sub-pixel of the hole injection layer makes it easier for the display panel to meet the requirement that the ratio of capacitance change between two sub-pixels of different luminous colors is between a first threshold and a second threshold.

[0087] In an optional embodiment, the sub-pixels include at least a red sub-pixel, a green sub-pixel and a blue sub-pixel, the material of the light-emitting layer of the red sub-pixel includes a red light-emitting material, the material of the light-emitting layer of the green sub-pixel includes a green light-emitting material, and the material of the light-emitting layer of the blue sub-pixel includes a blue light-emitting material.

[0088] The red light-emitting material includes any one or more of a DCM series of red light-emitting materials and a metal complex red light-emitting material. A red light-emitting material selected from this category is used as a red sub-pixel of the light-emitting layer, which makes it easier for the display panel to meet the ratio of the capacitance change value between two sub-pixels with different luminous colors between the first threshold and the second threshold. Exemplarily, the red light-emitting material includes 4-(dicyanomethylene)-2-methyl-6-(4-dimethylaminophenyl)-4H-pyran, 4-(dicyanomethylene)-2-tert-butyl-6-(1,1,7,7-tetramethyljulonitrile-9-enyl)-4H-pyran, bis(1-phenylisoquinoline)(acetylacetonate)iridium(III), octaethylporphyrin platinum, bis(2-(2'-benzothienyl)pyridine-N,C3')(acetylacetonate)iridium.

[0089] The blue luminescent material includes any one or more of a pyrene derivative, anthracene derivative, fluorene derivative, perylene derivative, styrylamine derivative, and metal complex blue luminescent material. Using a blue luminescent material selected from these categories as a blue sub-pixel in the luminescent layer makes it easier for the display panel to meet a requirement that the ratio of capacitance change between two sub-pixels emitting different colors is between a first threshold and a second threshold. Illustratively, the blue light-emitting material includes any one or more of N1,N6-di([1,1'-biphenyl]-2-yl)-N1,N6-di([1,1'-biphenyl]-4-yl)pyrene-1,6-diamine, 9,10-di-(2-naphthyl)anthracene, 2-methyl-9,10-di-2-naphthylanthracene, 2,5,8,11-tetra-tert-butylperylene, 4,4'-bis[4-(diphenylamino)phenylvinyl]biphenyl, 4,4'-bis[4-(di-p-tolylamino)phenylvinyl]biphenyl, and bis(4,6-difluorophenylpyridine-C2,N)picolinyliridium.

[0090] The green luminescent material includes any one or more of a coumarin dye green luminescent material, a quinacridone copper derivative green luminescent material, a polycyclic aromatic hydrocarbon green luminescent material, a diamine anthracene derivative green luminescent material, a carbazole derivative green luminescent material, and a metal complex green luminescent material. The green luminescent material selected from this category is used as a green sub-pixel of the light-emitting layer, which makes it easier for the display panel to meet the requirement that the ratio of the capacitance change value between two sub-pixels with different luminescent colors is between a first threshold and a second threshold. Exemplarily, the green luminescent material includes any one or more of coumarin 6, coumarin 545T, quinacridone copper, N,N'-dimethylquinacridone, 5,12-diphenylnaphthonaphthalene, N10,N10'-diphenyl-N10,N10'-diphthaloyl-9,9'-dianthracene-10,10'-diamine, tris(8-hydroxyquinoline)aluminum(III), tris(2-phenylpyridine)iridium, and di(2-phenylpyridine)iridium acetylacetonate.

[0091] The embodiment of the present disclosure determines the layer structure materials in the sub-pixels of each luminous color according to the range of the above-mentioned layer structure materials, and a plurality of sub-pixels of different luminous colors are composed of these layer structures. The ratio of the capacitance change values ​​between any two sub-pixels of different luminous colors is greater than or equal to the first threshold value and less than or equal to the second threshold value, thereby ensuring that the capacitance change values ​​between the sub-pixels of different luminous colors in the display panel composed of these sub-pixels are in a relatively balanced state, so that the display panel will not have color display accuracy problems such as color difference, thereby improving the user experience.

[0092] In an optional embodiment, as shown in Figure 1, the display panel also includes a pixel defining layer 12, the pixel defining layer 12 has a plurality of openings Q, the plurality of sub-pixels 13 are arranged in the pixel defining layer 12 corresponding to the plurality of openings Q, and the plurality of openings Q can be all or part of the openings on the pixel defining layer 12.

[0093] The present disclosure provides a display substrate, which includes: a substrate and a plurality of sub-pixels located on one side of the substrate; a ratio of capacitance change values ​​of two sub-pixels with different luminous colors is greater than or equal to a first threshold and less than or equal to a second threshold, the first threshold is less than or equal to 1, and the second threshold is greater than or equal to 1, wherein the capacitance change value is used to characterize the difference between the initial capacitance of the sub-pixel and the first capacitance, the initial capacitance is the capacitance of the sub-pixel when the brightness of the display panel is the initial brightness, and the first capacitance is the capacitance of the sub-pixel when the brightness of the display panel decays to the target brightness.

[0094] The present disclosure adjusts the material combination of different layer structures in each sub-pixel to set different sub-pixels so that the ratio of the capacitance change values ​​of two sub-pixels with different luminous colors is greater than or equal to a first threshold and less than or equal to a second threshold, thereby making the differences in capacitance change between different sub-pixels close to consistent, thereby avoiding the problem of inaccurate color display on the display panel.

[0095] Based on the same inventive concept, the present disclosure provides a display device, comprising a display panel as described in the embodiments of the present disclosure. The display panel further comprises a drive circuit (taking FIG. 1 as an example, the drive circuit comprises drive circuits corresponding to RGB sub-pixels, and a red drive circuit 10R, a green drive circuit 10G, and a blue drive circuit 10B), and a power supply circuit. The drive circuit is configured to provide a drive signal to the display panel. The power supply circuit is configured to provide a power supply signal to the display panel.

[0096] In the embodiments of the present disclosure, the display device may be a display or a product including a display. The display may be a flat panel display (FPD), a microdisplay, or the like. Based on whether the user can see the back of the display, the display may be a transparent display or an opaque display. It should be noted that the specific display device may be determined based on actual circumstances and is not limited in this disclosure.

[0097] Based on the same inventive concept, embodiments of the present disclosure provide a display panel testing method. Based on this display panel testing method, the display panel described in the embodiments of the present disclosure is determined. The display panel includes a substrate and a plurality of sub-pixels located on one side of the substrate. FIG6 schematically shows a flow chart of a display panel testing method proposed in the present disclosure. As shown in FIG6 , the testing method includes the following steps:

[0098] S101 . When the brightness of the display panel is at an initial brightness, obtain the initial capacitance of the sub-pixel.

[0099] The plurality of sub-pixels include a first color sub-pixel, and the first color sub-pixel is any one of a red sub-pixel, a blue sub-pixel, and a green sub-pixel. Specifically, when implementing step S101, the display panel is first adjusted to an initial state (the initial state is the luminous state of the display device when the brightness of the display panel is not attenuated, and the brightness at this time is the initial brightness). When the brightness of the display panel is at the initial brightness, the first color sub-pixel in the display panel is controlled to emit light. Subsequently, the capacitance-voltage relationship of the first color sub-pixel is tested when the brightness of the display panel is at the initial brightness, and the initial capacitance of the first color sub-pixel is obtained based on the capacitance-voltage relationship of the first color sub-pixel. In which, the capacitance-voltage relationship of the first color sub-pixel can be a capacitance-voltage curve of the first color sub-pixel, which is used to characterize a capacitance value change curve of the first color sub-pixel at different voltages in the state of initial brightness; the initial capacitance can be the capacitance of a single first color sub-pixel at the target voltage when the brightness of the display panel is the initial brightness, or it can be the capacitance of all first color sub-pixels in the display panel at the target voltage when the brightness of the display panel is the initial brightness. Preferably, the initial capacitance is the maximum capacitance of all first color sub-pixels in the display panel at each voltage when the brightness of the display panel is the initial brightness.

[0100] In an embodiment of the present application, when the brightness of the display panel is the initial brightness, in the process of applying the target voltage to the first color sub-pixel of the display panel, the holes generated by the anode move through the first carrier layer to the light-emitting layer in the first color sub-pixel, and in this process, the holes may be distributed at the interface of one or more hierarchical structures in the first carrier layer; the electrons generated by the cathode move through the second carrier layer to the light-emitting layer in the first color sub-pixel, and in this process, the electrons may be distributed at the interface of one or more hierarchical structures in the second carrier layer; therefore, when the target voltage is reached, the holes and electrons are concentrated on the interface between different hierarchical structures, wherein a plurality of capacitors in parallel are formed between the hierarchical structure interface where the electrons are distributed and the hierarchical structure interface where the holes are distributed, and the above-mentioned multiple capacitors under the target voltage are combined into the initial capacitance of the first color sub-pixel, and based on the initial capacitance under different target voltages, the capacitance-voltage curve of the first color sub-pixel in the initial brightness state is obtained.

[0101] For example, taking the display panel shown in FIG1 as an example, when the target voltage is in the range of -1V to 0V, holes and electrons have not started to move toward the light-emitting layer, holes are concentrated in the anode 131, and electrons are concentrated in the cathode 132. The initial capacitance at this time is the capacitance between the cathode 132 and the anode 131; when the target voltage is in the range of 0V to 1V, electrons have not started to move toward the light-emitting layer, and holes move toward the light-emitting layer via the hole injection layer 136, the hole transport layer 134, and the electron blocking layer 138. When the target voltage is 1V, holes are concentrated at the interface between the hole transport layer 134 and the electron blocking layer 138 (referred to as the hole interface). At this time, the capacitance between the hole interface and the cathode 132, and the capacitance between the cathode 132 and the anode 131 exist in parallel. The sum of the two parallel capacitance values ​​is calculated. As the initial capacitance of the first color sub-pixel at a target voltage of 1V; when the target voltage is in the range of 1V to 1.5V, electrons also begin to move toward the light-emitting layer. When the target voltage is 1.5V, electrons are concentrated at the interface between the electron injection layer 137 and the electron transport layer 135 (referred to as the electron interface), and holes are concentrated at the interface between the hole transport layer 134 and the electron blocking layer 138 (referred to as the hole interface). At this time, the capacitance between the electron interface and the anode 131, the capacitance between the hole interface and the cathode 132, the capacitance between the anode 131 and the cathode 132, and the capacitance between the electron interface and the hole interface all exist in parallel. The sum of the above-mentioned parallel capacitance values ​​is taken as the initial capacitance of the first color sub-pixel at the initial brightness at a target voltage of 1.5V.

[0102] It should be noted that the above example is only a specific case given to enable those skilled in the art to better understand the capacitor formation process of the present disclosure. The positions of the electron interface and the hole interface are determined according to actual conditions and are not limited to the case in the above example. For example, at the target voltage, when the display panel is the display panel shown in FIG1 , the hole interface can be the interface between the hole transport layer 134 and the electron blocking layer 138, the interface between the hole injection layer 136 and the hole transport layer 134, the interface between the anode 131 and the hole injection layer 136, the interface between the electron blocking layer 138 and the light emitting layer 133, and the interface between the electron blocking layer 138 and the light emitting layer 133. The electronic interface can be one or more of the interfaces between the cathode 132 and the electron injection layer 137, the interface between the electron injection layer 137 and the electron transport layer 135, the interface between the electron transport layer 135 and the hole blocking layer 139, the interface between the hole blocking layer 139 and the light-emitting layer 133, and the interface between the light-emitting layer 133 and the electron blocking layer 138; the sum of the capacitances of the parallel capacitances formed between all the electronic interfaces and the hole interfaces is used as the initial capacitance of the first color sub-pixel at the initial brightness.

[0103] S102 : When the brightness of the display panel is at a target brightness, obtain a first capacitance of the sub-pixel.

[0104] The plurality of sub-pixels include a second color sub-pixel, which is any one of a red sub-pixel, a blue sub-pixel, and a green sub-pixel. Specifically, in step S102, the display panel, which is originally in an initial state, is first adjusted to a first state (the first state is a state in which the brightness of the display panel is attenuated to a target brightness). When the brightness of the display panel is at the target brightness, the second color sub-pixel in the display panel is controlled to emit light. Subsequently, the capacitance-voltage relationship of the second color sub-pixel is tested when the brightness of the display panel is at the target brightness, and the first capacitance of the second color sub-pixel is obtained based on the capacitance-voltage relationship of the second color sub-pixel. In which, the capacitance-voltage relationship of the second color sub-pixel can be a capacitance-voltage curve of the second color sub-pixel, which is used to characterize a capacitance value change curve of the second color sub-pixel at different voltages under the target brightness state; the first capacitance can be the capacitance of a single second color sub-pixel at the target voltage when the brightness of the display panel decays to the target brightness, or it can be the capacitance of all second color sub-pixels in the display panel at the target voltage when the brightness of the display panel decays to the target brightness. Preferably, the first capacitance is the maximum capacitance of all second color sub-pixels in the display panel at each voltage when the brightness of the display panel decays to the target brightness.

[0105] In an embodiment of the present application, when the brightness of the display panel is the target brightness, in the process of applying the target voltage to the second color sub-pixel of the display panel, the holes generated by the anode move through the first carrier layer to the light-emitting layer in the second color sub-pixel, and in this process, the holes may be distributed at the interface of one or more hierarchical structures in the first carrier layer; the electrons generated by the cathode move through the second carrier layer to the light-emitting layer in the first color sub-pixel, and in this process, the electrons may be distributed at the interface of one or more hierarchical structures in the second carrier layer; therefore, when the target voltage is reached, the holes and electrons are concentrated on the interface between different hierarchical structures, wherein a plurality of capacitors in parallel are formed between the hierarchical structure interface where the electrons are distributed and the hierarchical structure interface where the holes are distributed, and the above-mentioned multiple capacitors under the target voltage are combined into the first capacitor of the second color sub-pixel, and based on the first capacitors under different target voltages, the capacitance-voltage curve of the second color sub-pixel under the target brightness state is obtained.

[0106] S103 : Compare the initial capacitance of the sub-pixel with the first capacitance to obtain a capacitance change value of the sub-pixel.

[0107] When specifically implementing step S103, based on the difference between the initial capacitance and the first capacitance of the sub-pixel (including the first color sub-pixel and the second color sub-pixel), the capacitance change value corresponding to the sub-pixel is obtained. The capacitance change value is used to measure the capacitance state of the sub-pixel after brightness attenuation in the display panel. The capacitance change value can be the difference between the initial capacitance and the first capacitance of the sub-pixel, or the ratio between the initial capacitance and the first capacitance of the sub-pixel. The specific capacitance change value can be determined according to actual conditions and is not limited by the present disclosure. For example, for the RGB sub-pixels in the display panel, the capacitance change value of each sub-pixel is obtained according to the following process: the red sub-pixel, the green sub-pixel, and the blue sub-pixel are respectively used as the first color sub-pixel, and the initial capacitance C of the red sub-pixel is obtained. R-0 , the initial capacitance C of the green sub-pixel G-0 and the initial capacitance C of the blue sub-pixel B-0 ; The red sub-pixel, the green sub-pixel and the blue sub-pixel are respectively used as the second color sub-pixel, and the first capacitance C of the red sub-pixel is obtained R-1 , the first capacitor C of the green sub-pixel G-1 and the first capacitor C of the blue sub-pixel B-1 Calculate the ratio of the initial capacitance of the sub-pixel to the first capacitance to obtain the capacitance change value of the sub-pixel, and obtain the capacitance change value of each sub-pixel according to the following formula: R R =C R-0 / C R-1 ; R G =C G-0 / C G-1 ; R B =C B-0 / C B-1 ;

[0108] Among them, R R is the capacitance change value of the red sub-pixel; R G is the capacitance change value of the green sub-pixel; R B is the capacitance change value of the blue sub-pixel; C R-0 is the initial capacitance of the red sub-pixel; C R-1 is the first capacitor of the red sub-pixel; C G-0 is the initial capacitance of the green sub-pixel; C G-1 is the first capacitor of the green sub-pixel; C B-0 is the initial capacitance of the blue sub-pixel; C B-1 is the first capacitor of the blue sub-pixel.

[0109] S104 , calculating a ratio of capacitance change values ​​of two sub-pixels of different colors.

[0110] When step S104 is specifically implemented, after obtaining the capacitance change values ​​of multiple sub-pixels with different luminous colors, the capacitance change value of each sub-pixel represents the capacitance state of the sub-pixel after brightness attenuation. When the difference in capacitance states of sub-pixels with different luminous colors when decaying to the same target brightness is small, it indicates that the capacitance change values ​​between the sub-pixels with different luminous colors in the display panel are in a relatively balanced state.

[0111] Specifically, the ratio of the capacitance change values ​​of the two sub-pixels of different colors is calculated, and the ratio is used to represent the difference in the change amplitude of the capacitance state of the sub-pixels of different luminous colors when they decay to the same target brightness. For example, the display panel includes a red sub-pixel, a green sub-pixel, and a blue sub-pixel. Based on the above steps, the capacitance change value R of the red sub-pixel is obtained. R , the capacitance change value R of the green sub-pixel G And the capacitance change value R of the blue sub-pixel B Then, the ratio R of the capacitance change value of the red sub-pixel and the blue sub-pixel is calculated respectively. R / R B , the ratio of the capacitance change of the red sub-pixel to the green sub-pixel R R / R G , the ratio of the capacitance change of the blue sub-pixel to the green sub-pixel R B / R G .

[0112] S105 : If the ratio is greater than or equal to the first threshold and less than or equal to the second threshold, determine that the display panel test is qualified.

[0113] When specifically implementing step S105, it is determined whether the ratio of the capacitance change values ​​of two sub-pixels with different luminous colors is within the range between the first threshold and the second threshold. If the ratio of the capacitance change values ​​is less than the first threshold or greater than the second threshold, it means that the capacitance state change amplitudes of the sub-pixels with different luminous colors are relatively different when the brightness of the display panel decays, and the display panel will have problems such as color difference and other inaccurate color display during operation, and the display panel is determined to be unqualified for the test; if the ratio of the capacitance change values ​​is greater than or equal to the first threshold and less than or equal to the second threshold, it means that the capacitance state change amplitudes of the sub-pixels with different luminous colors are relatively small when the brightness of the display panel decays, and the display panel has accurate color display during operation, and the display panel is determined to be qualified for the test. For example, the display panel includes a red sub-pixel, a green sub-pixel, and a blue sub-pixel, the first threshold is 0.8, the second threshold is 1.25, and the ratio of the capacitance change values ​​of the two sub-pixels with different luminous colors is determined according to the following formula: 0.8≤R R / R B ≤1.25; 0.8≤R R / R G ≤1.25; 0.8≤R B / R G ≤1.25;

[0114] Among them, R R is the capacitance change value of the red sub-pixel, R G is the capacitance change value of the green sub-pixel, R B is the capacitance change value of the blue sub-pixel.

[0115] In an optional embodiment, when the display panel is determined to have failed the test, the problem sub-pixel is determined based on the ratio of the capacitance change values ​​that are not within the range between the first threshold and the second threshold, the combination of the layer structure materials in the problem sub-pixel is replaced from the range of the above-mentioned layer structure materials, and the above-mentioned steps S101-S105 are repeated until the display panel is determined to have passed the test.

[0116] In order to enable those skilled in the art to more clearly understand the present disclosure, the test method of the display panel described in the present disclosure is now described in detail through the following embodiments.

[0117] A display panel of a comparative example was obtained and first adjusted to an initial state. When the brightness of the display panel was at the initial brightness, the red, green, and blue sub-pixels in the display panel were controlled to emit light, and the capacitance-voltage curves of the red, green, and blue sub-pixels were measured when the brightness of the display panel was at the initial brightness. The brightness of the display panel was then decayed to a target brightness (90% of the initial brightness), and the capacitance-voltage curves of the red, green, and blue sub-pixels were measured when the brightness of the display panel was at the target brightness.

[0118] FIG2 schematically shows a capacitance-voltage curve of a red sub-pixel in a display panel of a comparative example proposed in the present disclosure. As shown in FIG2 , the solid line is the voltage-capacitance curve of the red sub-pixel at the initial brightness, and the dotted line is the voltage-capacitance curve of the red sub-pixel at the target brightness. The maximum capacitance in the voltage-capacitance curve of the red sub-pixel at the initial brightness (the peak value of the solid line in FIG2 ) is taken as the initial capacitance C of the red sub-pixel. R-0 , the maximum capacitance in the voltage-capacitance curve of the red sub-pixel at the target brightness (the peak value of the dotted line in Figure 2) is taken as the first capacitance C of the red sub-pixel R-1 Calculate the ratio of the initial capacitance of the red sub-pixel to the first capacitance to obtain the pixel change value R of the red sub-pixel R , R R =C R-0 / C R-1 .

[0119] FIG3 schematically shows a capacitance-voltage relationship curve of a green sub-pixel in a display panel of a comparative example proposed in the present disclosure. As shown in FIG3 , the solid line is the voltage-capacitance curve of the green sub-pixel at the initial brightness, and the dotted line is the voltage-capacitance curve of the green sub-pixel at the target brightness. The maximum capacitance in the voltage-capacitance curve of the green sub-pixel at the initial brightness (the peak value of the solid line in FIG3 ) is taken as the initial capacitance C of the green sub-pixel. G-0 , the maximum capacitance in the voltage-capacitance curve of the green sub-pixel at the target brightness (the peak value of the dotted line in FIG3 ) is taken as the first capacitance C of the green sub-pixel G-1 Calculate the ratio of the initial capacitance of the green sub-pixel to the first capacitance to obtain the pixel change value R of the green sub-pixel G , R G =C G-0 / C G-1 .

[0120] FIG4 schematically shows a capacitance-voltage relationship curve of a blue sub-pixel in a display panel of a comparative example proposed in the present disclosure. As shown in FIG4 , the solid line is the voltage-capacitance curve of the blue sub-pixel at the initial brightness, and the dotted line is the voltage-capacitance curve of the blue sub-pixel at the target brightness. The maximum capacitance in the voltage-capacitance curve of the blue sub-pixel at the initial brightness (the peak value of the solid line in FIG4 ) is taken as the initial capacitance C of the blue sub-pixel. B-0 , the maximum capacitance in the voltage-capacitance curve of the blue sub-pixel at the target brightness (the peak value of the dotted line in FIG4 ) is taken as the first capacitance C of the blue sub-pixel B-1 Calculate the ratio of the initial capacitance of the blue sub-pixel to the first capacitance to obtain the pixel change value R of the blue sub-pixel B , R B =C B-0 / C B-1 .

[0121] Table 1 shows the pixel change values ​​of the sub-pixels in the display panel of the comparative example. As shown in Table 1, in the display panel of the comparative example, the pixel change value R of the red sub-pixel is R is 1.28, and the pixel change value R of the green sub-pixel G is 1.88, and the pixel change value R of the blue sub-pixel B It is 1.11.

[0122] Table 1 Pixel change values ​​of sub-pixels in the display panel of the comparative example

[0123] After obtaining the capacitance change values ​​of the red sub-pixel, the green sub-pixel, and the blue sub-pixel, the ratio R of the capacitance change values ​​of the red sub-pixel to the blue sub-pixel is calculated. R / R B, the ratio of the capacitance change of the red sub-pixel to the green sub-pixel R R / R G , the ratio of the capacitance change of the blue sub-pixel to the green sub-pixel R B / R G Table 2 shows the pixel change value ratio of two sub-pixels with different luminous colors in the display panel of the comparative example. As shown in Table 2, the pixel change value ratio R between the red sub-pixel and the blue sub-pixel is R / R B is 1.15, the ratio of the pixel change value between the red sub-pixel and the green sub-pixel R R / R G The ratio of the pixel change value between the blue sub-pixel and the green sub-pixel is 0.68. B / R G It is 0.59.

[0124] Table 2 Pixel change ratio of two sub-pixels with different luminous colors in the display panel of the comparative example

[0125] Given the first threshold value is 0.8, the second threshold value is 1.25, according to the pixel change value ratio of two sub-pixels with different luminous colors in the display panel of the above comparative example, it can be known that the pixel change value ratio R between the red sub-pixel and the green sub-pixel in the comparative example is R / R G , the ratio of the pixel change value between the blue sub-pixel and the green sub-pixel R B / R G It is not within the range between the first threshold and the second threshold, which means that the capacitance state change amplitudes of sub-pixels of different luminous colors are quite different when the brightness of the display panel decays. The display panel will have inaccurate color display problems such as color difference during operation. At this time, the display panel of this comparison ratio is judged to have failed the test.

[0126] Based on the calculation results of Table 2, it can be seen that the relative value of the capacitance change of the green sub-pixel included in the comparative example is relatively small. It is determined that the capacitance of the green sub-pixel in the display panel of the comparative example has a large difference in the layer structure interface accumulation during operation from the red sub-pixel and the blue sub-pixel, resulting in a large difference in the capacitance change during operation. Therefore, the layer structure material used for the green sub-pixel in the display panel of the comparative example is obtained, and the hierarchical structure of the green sub-pixel in the display panel of the comparative example is: anode / HIL / HTL / EBL / GH:GD / HBL / ETL / EIL / cathode. Table 3 shows the chemical structure of some materials used for the green sub-pixel in the display panel of the comparative example. As shown in Table 3:

[0127] Table 3 Chemical structures of some materials used in the green sub-pixel of the display panel of the comparative example

[0128] The green light-emitting host material, hole transport material, and electron blocking material in the green sub-pixel of the display panel of the comparative example are replaced within the range of layered structure materials given in the embodiments of the present disclosure to obtain the display panel of Example 1. The layered structure of the green sub-pixel in the display panel of Example 1 is: anode / HIL / HTL / EBL-1 / EBL-2 / GH-1:GH-2:GD / HBL / ETL / EIL / cathode. Table 4 shows the chemical structures of some of the materials used in the green sub-pixel of the display panel of Example 1, as shown in Table 4:

[0129] Table 4 Chemical structures of some materials used in the green sub-pixel of the display panel of Example 1

[0130] The display panel of Example 1 is obtained and adjusted to an initial state. When the brightness of the display panel is at the initial brightness, the red sub-pixel, the green sub-pixel, and the blue sub-pixel in the display panel are respectively controlled to emit light, and the capacitance-voltage curve of the red sub-pixel, the capacitance-voltage curve of the green sub-pixel, and the capacitance-voltage curve of the blue sub-pixel are tested when the brightness of the display panel is at the initial brightness. The brightness of the display panel is decayed to a target brightness (90% of the initial brightness), and the capacitance-voltage curve of the red sub-pixel, the capacitance-voltage curve of the green sub-pixel, and the capacitance-voltage curve of the blue sub-pixel are tested when the brightness of the display panel is at the target brightness.

[0131] Taking the green sub-pixel with a replaced layer structure material as an example, FIG5 schematically shows the capacitance-voltage relationship curve of the green sub-pixel in the display panel of Example 1 proposed in the present disclosure. As shown in FIG5, the solid line is the voltage-capacitance curve of the green sub-pixel at the initial brightness, and the dotted line is the voltage-capacitance curve of the green sub-pixel at the target brightness. The maximum capacitance in the voltage-capacitance curve of the green sub-pixel at the initial brightness (the peak value of the solid line in FIG5) is taken as the initial capacitance C of the green sub-pixel. G-0 , the maximum capacitance in the voltage-capacitance curve of the green sub-pixel at the target brightness (the peak value of the dotted line in FIG5 ) is taken as the first capacitance C of the green sub-pixel G-1 Calculate the ratio of the initial capacitance of the green sub-pixel to the first capacitance to obtain the pixel change value R of the green sub-pixel in the display panel of Example 1. R , R R =C R-0 / C R-1 .

[0132] Table 5 shows the pixel change values ​​of the sub-pixels in the display panel of Example 1. As shown in Table 5, in the display panel of the comparative example, the pixel change value R of the red sub-pixel is R is 1.28, and the pixel change value R of the blue sub-pixel B The pixel change value of the green sub-pixel is 1.11 due to the replacement of the layer structure material R G becomes 1.25.

[0133] Table 5 Pixel change values ​​of sub-pixels in the display panel of Example 1

[0134] After obtaining the capacitance change values ​​of the red sub-pixel, the green sub-pixel, and the blue sub-pixel, the ratio R of the capacitance change values ​​of the red sub-pixel to the blue sub-pixel is calculated. R / R B , the ratio of the capacitance change of the red sub-pixel to the green sub-pixel R R / R G , the ratio of the capacitance change of the blue sub-pixel to the green sub-pixel R B / R G Table 6 shows the pixel change value ratio of two sub-pixels with different luminous colors in the display panel of Example 1. As shown in Table 6, the pixel change value ratio R between the red sub-pixel and the blue sub-pixel is R / R B is 1.15, the ratio of the pixel change value between the red sub-pixel and the green sub-pixel R R / R G is 1.03, the ratio of the pixel change value between the blue sub-pixel and the green sub-pixel R B / R G It is 0.89.

[0135] Table 6 Pixel change ratio of two sub-pixels with different luminous colors in the display panel of Example 1

[0136] For a given first threshold of 0.8 and a second threshold of 1.25, according to the pixel change value ratio of two sub-pixels with different luminous colors in the display panel of the above embodiment 1, by replacing the layer structure material of the green sub-pixel, the ratio R of the capacitance change value of the red sub-pixel and the blue sub-pixel in embodiment 1 is increased. R / R B , the ratio of the pixel change value between the red sub-pixel and the green sub-pixel R R / R G And the ratio R between the pixel change values ​​of the blue sub-pixel and the green sub-pixel B / R GThey are all within the range between the first threshold and the second threshold, indicating that the capacitance state change amplitudes of sub-pixels of different luminous colors are almost consistent when the brightness of the display panel decays. The display panel of Example 1 will not have the problem of inaccurate color display during operation. At this time, it is determined that the display panel of Example 1 has passed the test.

[0137] Table 7 shows the energy level simulation data of the electron blocking layer materials of the comparative example and Example 1. The HOMO energy level and LUMO energy level in Table 7 are simulated and calculated, and there is a fixed Gap with the measured value, which is about -0.55eV to -0.6eV. As shown in Table 7, the simulated HOMO energy level of the electron blocking layer material of the comparative example is -4.6eV, and the experimental test value corresponding to the electron blocking layer material of the comparative example is about -5.15eV to -5.2eV. The HOMO energy level is the optional energy level range of the electron blocking material described in the embodiment of the present disclosure, between -5.8eV and -5.0eV. When it is determined that the layer material of the green sub-pixel in the comparative example needs to be replaced, The simulated HOMO energy level of the material of the electron blocking layer EBL-1 used in the replaced embodiment 1 is -4.68eV, and the corresponding experimental test value is approximately -5.23eV to -5.28eV. The simulated HOMO energy level of the material of the electron blocking layer EBL-2 used in the replaced embodiment 1 is -4.79eV, and the corresponding experimental test value is approximately -5.34eV to -5.38eV. The electron blocking layer materials EBL-1 and EBL-2 are also materials that meet the optional energy level range of the electron blocking materials described in the embodiments of the present disclosure, which is between -5.8eV and -5.0eV. After the layer structure materials are replaced, the embodiment 1 is judged to be qualified in the test.

[0138] Table 7 Energy level simulation data of electron blocking layer materials of comparative example and embodiment 1

[0139] References herein to "one embodiment," "an embodiment," or "one or more embodiments" mean that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present disclosure. Furthermore, please note that instances of the phrase "in one embodiment" do not necessarily all refer to the same embodiment.

[0140] In the description provided herein, numerous specific details are described. However, it is understood that embodiments of the present disclosure may be practiced without these specific details. In some instances, well-known methods, structures, and techniques are not shown in detail so as not to obscure the understanding of this description.

[0141] In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. The word "comprising" does not exclude the presence of elements or steps not listed in the claim. The word "a" or "an" preceding an element does not exclude the presence of a plurality of such elements. The present disclosure may be implemented by means of hardware comprising several different elements and by means of a suitably programmed computer. In a unit claim enumerating several means, several of these means may be embodied by the same item of hardware. The use of the words first, second, and third etc. does not indicate any order. These words may be interpreted as names.

[0142] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present disclosure, rather than to limit them. Although the present disclosure has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present disclosure.

Claims

1. A display panel, characterized in that: include: A substrate and a plurality of sub-pixels located on one side of the substrate; The ratio of the capacitance change values ​​of two sub-pixels with different luminous colors is greater than or equal to a first threshold and less than or equal to a second threshold, the first threshold is less than or equal to 1, and the second threshold is greater than or equal to 1, wherein the capacitance change value is used to characterize the difference between the initial capacitance of the sub-pixel and the first capacitance, the initial capacitance is the capacitance of the sub-pixel when the brightness of the display panel is the initial brightness, and the first capacitance is the capacitance of the sub-pixel when the brightness of the display panel decays to the target brightness.

2. The display panel according to claim 1, characterized in that: A brightness ratio of the target brightness to the initial brightness is greater than or equal to 50% and less than or equal to 90%.

3. The display panel according to claim 1, characterized in that: The first threshold is greater than or equal to 0.7 and less than or equal to 1; the second threshold is greater than or equal to 1 and less than or equal to 1.

3.

4. The display panel according to claim 1, characterized in that: The sub-pixel comprises: A first electrode, a light-emitting layer, and a second electrode are sequentially stacked on one side of the substrate; A first carrier layer and a second carrier layer, wherein the first carrier layer is disposed between the first electrode and the light-emitting layer, and the second carrier layer is disposed between the second electrode and the light-emitting layer.

5. The display panel according to claim 4, characterized in that: In the case where the first electrode is an anode and the second electrode is a cathode, the first carrier layer includes: at least one of a hole injection layer, a hole transport layer and an electron blocking layer, wherein the hole injection layer, the hole transport layer and the electron blocking layer are sequentially stacked along a first direction between the anode and the light-emitting layer, and the first direction is a direction from the anode to the cathode; The second carrier layer comprises: At least one of a hole blocking layer, an electron transport layer, and an electron injection layer, wherein the hole blocking layer, the electron transport layer, and the electron injection layer are sequentially stacked along the first direction between the light emitting layer and the cathode.

6. The display panel according to claim 5, characterized in that: The HOMO energy level of the hole transport layer is greater than or equal to -5.8 eV and less than or equal to -5.0 eV.

7. The display panel according to claim 5, characterized in that: The HOMO energy level of the electron blocking layer is greater than or equal to -5.8 eV and less than or equal to -5.0 eV.

8. The display panel according to claim 5, characterized in that: The LUMO energy level of the hole blocking layer is greater than or equal to -3.5 eV and less than or equal to -2.5 eV.

9. The display panel according to claim 5, characterized in that: The LUMO energy level of the electron transport layer is greater than or equal to -3.5 eV and less than or equal to -2.5 eV.

10. The display panel according to claim 5, characterized in that: The material of the electron injection layer includes any one or more of a low work function metal electron injection material and a metal salt electron injection material.

11. The display panel according to claim 5, characterized in that: The material of the hole injection layer includes any one or more of a hole injection material and a P-type doping material, and the hole injection material includes any one or more of copper phthalocyanine, 2,3,6,7,10,11-hexacyano-1,4,5,8,9,12-hexaazatriphenylene, and MnO3.

12. The display panel according to claim 4, characterized in that: The sub-pixels at least include a red sub-pixel, a green sub-pixel and a blue sub-pixel, the material of the light-emitting layer of the red sub-pixel includes a red light-emitting material, the material of the light-emitting layer of the green sub-pixel includes a green light-emitting material, and the material of the light-emitting layer of the blue sub-pixel includes a blue light-emitting material; The red luminescent material includes any one or more of DCM series red luminescent materials and metal complex red luminescent materials; The blue luminescent material includes pyrene derivative blue luminescent material, anthracene derivative blue luminescent material, fluorene derivative blue luminescent material, perylene derivative blue luminescent material, styrylamine derivative blue luminescent material, Any one or more of a blue luminescent material of the type of substance and a blue luminescent material of the type of metal complex; The green luminescent material includes any one or more of coumarin dye green luminescent materials, quinacridone copper derivative green luminescent materials, polycyclic aromatic hydrocarbon green luminescent materials, diamine anthracene derivative green luminescent materials, carbazole derivative green luminescent materials and metal complex green luminescent materials.

13. The display panel according to claim 12, characterized in that: The red light-emitting material includes any one or more of 4-(dicyanomethylene)-2-methyl-6-(4-dimethylaminophenylvinyl)-4H-pyran, 4-(dicyanomethylene)-2-tert-butyl-6-(1,1,7,7-tetramethyljulolidine-9-enyl)-4H-pyran, bis(1-phenylisoquinoline)(acetylacetonate)iridium(III), octaethylporphyrin platinum, and bis(2-(2'-benzothienyl)pyridine-N,C3')(acetylacetonate)iridium.

14. The display panel according to claim 12, characterized in that: The green light-emitting material includes any one or more of coumarin 6, coumarin 545T, quinacridone copper, N,N'-dimethylquinacridone, 5,12-diphenylnaphthonaphthone, N10,N10'-diphenyl-N10,N10'-diphthaloyl-9,9'-dianthracene-10,10'-diamine, tris(8-hydroxyquinoline)aluminum(III), tris(2-phenylpyridine)iridium, and acetylacetonate di(2-phenylpyridine)iridium.

15. The display panel according to claim 12, characterized in that: The blue light-emitting material includes any one or more of N1,N6-di([1,1'-biphenyl]-2-yl)-N1,N6-di([1,1'-biphenyl]-4-yl)pyrene-1,6-diamine, 9,10-di-(2-naphthyl)anthracene, 2-methyl-9,10-di-2-naphthylanthracene, 2,5,8,11-tetra-tert-butylperylene, 4,4'-di[4-(diphenylamino)phenylvinyl]biphenyl, 4,4'-di[4-(di-p-tolylamino)phenylvinyl]biphenyl, and bis(4,6-difluorophenylpyridine-C2,N)picolinyliridium.

16. A display device, characterized in that: The display device comprises a display panel according to any one of claims 1 to 15; A driving circuit, used for providing a driving signal to the display panel; A power supply circuit is used to provide a power supply signal to the display panel.

17. A method for testing a display panel, characterized in that: The display panel includes a substrate and a plurality of sub-pixels located on one side of the substrate, and the testing method includes: When the brightness of the display panel is at an initial brightness, obtaining an initial capacitance of the sub-pixel; When the brightness of the display panel is at a target brightness, obtaining a first capacitance of the sub-pixel; Comparing the initial capacitance of the sub-pixel with the first capacitance to obtain a capacitance change value of the sub-pixel; Calculating a ratio of capacitance change values ​​of two sub-pixels of different colors; If the ratio is greater than or equal to the first threshold and less than or equal to the second threshold, it is determined that the display panel test is qualified.

18. The display panel testing method according to claim 17, characterized in that: The plurality of sub-pixels include a first color sub-pixel, and the step of obtaining the initial capacitance of the sub-pixel when the brightness of the display panel is an initial brightness includes: When the brightness of the display panel is at an initial brightness, controlling a first color sub-pixel in the display panel to emit light; testing a capacitance-voltage relationship of the first color sub-pixel; An initial capacitance of the first color sub-pixel is obtained according to the capacitance-voltage relationship of the first color sub-pixel.

19. The display panel testing method according to claim 17, characterized in that: The plurality of sub-pixels include a second color sub-pixel, and the step of obtaining a first capacitance of the sub-pixel when the brightness of the display panel is a target brightness includes: When the brightness of the display panel is at the target brightness, controlling the second color sub-pixel in the display panel to emit light; testing a capacitance-voltage relationship of the second color sub-pixel; The first capacitance of the second color sub-pixel is obtained according to the capacitance-voltage relationship of the second color sub-pixel.

20. The display panel testing method according to claim 17, characterized in that: The step of comparing the initial capacitance of the sub-pixel with the first capacitance to obtain the capacitance change value of the sub-pixel comprises: The ratio of the initial capacitance of the sub-pixel to the first capacitance is calculated to obtain a capacitance change value of the sub-pixel.

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