Display panel and display device

Abstract

The present application discloses a display panel and a display device, wherein the display panel includes: a first electrode, a second electrode, and a first color light-emitting layer; the first color light-emitting layer includes a first host material and a second host material; the hole mobility of the first host material is higher than the hole mobility of the second host material; the absolute value of the difference between the electron mobilities of the first host material and the second host material, to the ratio of the smaller electron mobility, is smaller than the ratio of the absolute value of the difference between the hole mobilities of the first host material and the second host material to the hole mobility of the second host material; and / or the absolute value of the difference between the electron mobilities of the first host material and the second host material, to the ratio of the larger electron mobility, is smaller than the ratio of the absolute value of the difference between the hole mobilities of the first host material and the second host material to the hole mobility of the first host material. The present application can simultaneously improve color shift and efficiency roll-off problems.

Description

Technical Field

[0001] The present application relates to the technical field of display devices, and in particular to display panels and display devices. Background Art

[0002] Flexible OLED (Organic Light-Emitting Diode) has the advantages of self-luminescence, fast response, wide viewing angle, high contrast, light weight and can be made on flexible substrates, and is widely used in the display field.

[0003] However, the flexible OLED still needs improvement. Summary of the Invention

[0004] In order to solve the above problems or other problems, this application provides the following technical solutions.

[0005] To solve the above technical problems, the first technical solution adopted in the present application is to provide a display panel, comprising: a first electrode and a second electrode arranged opposite to each other; at least one first color light-emitting layer, arranged between the first electrode and the second electrode; at least one first color light-emitting layer comprising a first host material and a second host material; wherein the hole mobility of the first host material is higher than the hole mobility of the second host material; the absolute value of the difference between the electron mobility of the first host material and the second host material, and the ratio of the smaller electron mobility between the electron mobility of the first host material and the electron mobility of the second host material, is less than the ratio of the absolute value of the difference between the hole mobility of the first host material and the second host material to the hole mobility of the second host material; and / or the absolute value of the difference between the electron mobility of the first host material and the second host material, and the ratio of the larger electron mobility between the electron mobility of the first host material and the electron mobility of the second host material, is less than the ratio of the absolute value of the difference between the hole mobility of the first host material and the second host material to the hole mobility of the first host material.

[0006] The first color light emitting layer includes a mixture of a first host material and a second host material.

[0007] wherein, the first color light-emitting layer includes a first sublayer and a second sublayer that are stacked, and the first sublayer is located between the first electrode and the second sublayer; at least one of the first sublayer and the second sublayer includes a first main material, and at least one includes a second main material; wherein, the first sublayer and the second sublayer both include a mixed first main material and a second main material, and the mass fraction of the first main material in the first sublayer is different from the mass fraction of the first main material in the second sublayer; wherein, the first sublayer includes a mixed first main material and a second main material, and the second sublayer includes the first main material or the second main material; wherein, the first sublayer includes the first main material or the second main material, and the second sublayer includes a mixed first main material and a second main material; wherein, the first sublayer includes the first main material, and the second sublayer includes the second main material; wherein, the first sublayer includes the second main material, and the second sublayer includes the first main material.

[0008] Among them, at least one first color light-emitting layer includes multiple first color light-emitting layers, and a charge generation layer is arranged between two adjacent first color light-emitting layers; among them, some of the multiple first color light-emitting layers include a first host material and a second host material.

[0009] Among them, the display panel also includes other color light-emitting layers and charge generation layers, other color light-emitting layers are provided on at least one side of the first color light-emitting layer, and a charge generation layer is provided between the first color light-emitting layer and the other color light-emitting layer; wherein, the other color light-emitting layers include a second color light-emitting layer and / or a third color light-emitting layer.

[0010] wherein the absolute value of the difference in electron mobility between the first host material and the second host material, and the ratio of the smaller electron mobility between the electron mobility of the first host material and the electron mobility of the second host material is greater than or equal to 0 and less than or equal to 99; and / or the absolute value of the difference in electron mobility between the first host material and the second host material, and the ratio of the larger electron mobility between the electron mobility of the first host material and the electron mobility of the second host material is greater than or equal to 0 and less than or equal to 0.99; wherein the absolute value of the difference in electron mobility between the first host material and the second host material, and the ratio of the smaller electron mobility between the electron mobility of the first host material and the electron mobility of the second host material is greater than or equal to 0. The ratio of the absolute value of the difference between the hole mobility of the first host material and the second host material to the hole mobility of the second host material is greater than 0 and less than or equal to 9999; the ratio of the absolute value of the difference between the hole mobility of the first host material and the second host material to the hole mobility of the second host material is greater than 0 and less than or equal to 99; the ratio of the absolute value of the difference between the hole mobility of the first host material and the second host material to the hole mobility of the first host material is greater than 0 and less than or equal to 0.9999; the absolute value of the difference between the electron mobility of the first host material and the electron mobility of the second host material is greater than or equal to 0 and less than or equal to 0.0099 cm 2 / Vs; wherein the absolute value of the difference between the hole mobility of the first host material and the hole mobility of the second host material is greater than 0 and less than or equal to 0.0009999m 2 / Vs; wherein the electron mobility range of the first host material is 10 -4 ~10 -2 cm 2 / Vs; wherein the electron mobility range of the second host material is 10 -4 ~10 -2 cm 2 / Vs; wherein the hole mobility range of the first host material is 10 -5 ~10 -3 cm 2 / Vs; wherein the hole mobility range of the second host material is 10 -7 ~10 -5 cm 2 / Vs; wherein the first color light-emitting layer is a blue light-emitting layer.

[0011] In which, the display panel includes an electron blocking layer and a hole blocking layer, the electron blocking layer is located between the first electrode and the first color light-emitting layer, and the hole blocking layer is located between the second electrode and the first color light-emitting layer; the HOMO energy level of at least one of the first host material and the second host material is less than or equal to the HOMO energy level of the electron blocking layer; and / or, the LUMO energy level of at least one of the first host material and the second host material is greater than or equal to the LUMO energy level of the hole blocking layer; wherein the absolute value of the energy difference between the HOMO energy level of at least one of the first host material and the second host material and the HOMO energy level of the electron blocking layer is less than or equal to 0.3eV; wherein the absolute value of the energy difference between the LUMO energy level of at least one of the first host material and the second host material and the LUMO energy level of the hole blocking layer is less than or equal to 0.3eV.

[0012] In which, the LUMO level of the first host material is greater than the HOMO energy level of the second host material; and / or, the HOMO energy level of the first host material is less than the LUMO energy level of the second host material; in which, the absolute value of the energy difference between the LUMO energy level of the first host material and the HOMO energy level of the second host material is less than 2.8 eV; and / or, the absolute value of the energy difference between the HOMO energy level of the first host material and the LUMO energy level of the second host material is less than 2.8 eV.

[0013] wherein the volume ratio of the first main material to the second main material is 2:8 to 8:2; wherein the absolute value of the temperature difference between the sublimation temperature of the first main material and the sublimation temperature of the second main material is less than or equal to 20°; wherein the first color light-emitting layer also includes a guest material; wherein the guest material includes at least one of an organic dye, a fluorescent material or a phosphorescent material.

[0014] In order to solve the above technical problems, the second technical solution adopted in this application is to provide a display panel, including: a first electrode and a second electrode arranged opposite to each other; at least one first color light-emitting layer, arranged between the first electrode and the second electrode; at least one first color light-emitting layer includes a first main material and a second main material; a hole transport layer, arranged between the first electrode and the first color light-emitting layer; an electron transport layer, arranged between the second electrode and the first color light-emitting layer; wherein the hole mobility of the first main material is higher than the hole mobility of the second main material; the absolute value of the difference between the electron mobility of the first main material and the second main material, and the ratio of the smaller electron mobility between the electron mobility of the first main material and the electron mobility of the second main material is greater than or equal to 0 and less than or equal to 99.

[0015] wherein the ratio of the absolute value of the difference between the hole mobility of the first host material and the second host material to the hole mobility of the second host material is greater than 0 and less than or equal to 9999; wherein the ratio of the absolute value of the difference between the hole mobility of the first host material and the second host material to the hole mobility of the second host material is greater than 0 and less than or equal to 99; wherein the ratio of the absolute value of the difference between the electron mobility of the first host material and the second host material to the smaller electron mobility of the electron mobility of the first host material and the electron mobility of the second host material is greater than or equal to 0 and less than or equal to 9; wherein the electron mobility range of the first host material is 10 -4 ~10 -2 cm 2 / Vs; wherein the electron mobility range of the second host material is 10 -4 ~10 -2 cm 2 / Vs; wherein the hole mobility range of the first host material is 10 -5 ~10 -3 cm 2 / Vs; wherein the hole mobility range of the second host material is 10 -7 ~10 -5 cm 2 / Vs.

[0016] In order to solve the above technical problems, the third technical solution adopted in this application is to provide a display device including the above display panel.

[0017] The beneficial effect of the present application is: different from the related art, the present application provides a display panel and a display device, which can improve the electron transmission capability at low grayscale, thereby improving the low grayscale efficiency of the first color light-emitting layer, and then improving the color deviation problem. At the same time, it can also improve the efficiency roll-off problem. Furthermore, by making the absolute value of the difference in electron mobility between the two main materials and the ratio of the electron mobility with the smaller electron mobility between the two smaller than the ratio of the absolute value of the difference in hole mobility between the two main materials and the hole mobility of the second main material, and / or by making the absolute value of the difference in electron mobility between the two main materials and the ratio of the electron mobility with the larger electron mobility between the two smaller than the ratio of the absolute value of the difference in hole mobility between the two main materials and the hole mobility of the first main material, the two main materials can have the same or similar electron transport characteristics and very different hole transport characteristics, so that the stronger electron transport characteristics of the two main materials can offset the enhanced hole transport ability of the first main material at low grayscale due to its strong hole performance, thereby balancing the electron transport ability and hole transport ability at low grayscale, to ensure that the low grayscale efficiency of the first color light-emitting layer will not be affected, and then the display panel has better electron-hole balance characteristics and better display effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the example description. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0019] Figure 1 It is a schematic diagram of the overall structure of the display panel in this application;

[0020] Figure 2 is a schematic cross-sectional structural diagram of an embodiment of a display area in a display panel of the present application;

[0021] Figure 3 This is a schematic structural diagram of the first embodiment of the light-emitting device of the present application;

[0022] Figure 4 This is a schematic structural diagram of a second embodiment of the light-emitting device of the present application;

[0023] Figure 5 This is a schematic structural diagram of a third embodiment of the light-emitting device of the present application;

[0024] Figure 6 This is a schematic structural diagram of a fourth embodiment of the light-emitting device of the present application;

[0025] Figure 7 This is a schematic structural diagram of a fifth embodiment of the light-emitting device of the present application;

[0026] Figure 8 It is a comparative diagram of the normalized efficiency and efficiency corresponding to the light-emitting functional layer in the comparative example and the embodiment of the present application. DETAILED DESCRIPTION

[0027] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0028] The terms used in the examples of this application are for the purpose of describing specific embodiments only and are not intended to limit this application. The singular forms "a," "the," and "the" used in the examples of this application and the appended claims are also intended to include plural forms. Unless otherwise clearly indicated above, "a plurality" generally includes at least two, but does not exclude the inclusion of at least one.

[0029] It should be understood that the term "and / or" as used herein is merely a description of the relationship between associated objects, indicating that three possible relationships exist. For example, "A and / or B" can represent: A exists alone, A and B exist simultaneously, or B exists alone. Furthermore, the character " / " in this document generally indicates that the associated objects are in an "or" relationship.

[0030] It should be understood that the terms "comprises," "comprising," or any other variations used herein are intended to encompass non-exclusive inclusion, such that a process, method, article, or apparatus that includes a list of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus. In the absence of further limitations, an element defined by the phrase "comprising..." does not preclude the presence of additional identical elements in the process, method, article, or apparatus that includes the element.

[0031] In the related art, an OLED device generally includes an organic light-emitting layer made of an organic light-emitting material arranged between an anode and a cathode. When current is applied to the anode, holes injected from the anode move to the organic light-emitting layer through a hole injection layer (HIL) and a hole transport layer (HTL), and electrons injected from the cathode move to the organic light-emitting layer through an electron injection layer (EIL) and an electron transport layer (ETL). The holes and electrons interact, and the organic light-emitting layer emits light for display.

[0032] However, the low-grayscale efficiency of red, green, and blue sub-pixels varies, making low-grayscale color shift more likely. Related art attempts to improve low-grayscale characteristics by adjusting the properties of the blue-light-bearing material of the blue sub-pixel. However, this adjustment method in related art can result in a roll-off in high-grayscale efficiency.

[0033] Based on the above situation, the present application provides a display panel and a display device, which can solve the problem of the above-mentioned related art that cannot take into account both the color cast problem and the efficiency roll-off problem of the display panel.

[0034] The display panel provided in the present application includes: a first electrode and a second electrode arranged opposite to each other; at least one first color light-emitting layer, arranged between the first electrode and the second electrode; at least one first color light-emitting layer includes a first host material and a second host material; wherein the hole mobility of the first host material is higher than the hole mobility of the second host material; the absolute value of the difference between the electron mobility of the first host material and the second host material, and the ratio of the smaller electron mobility between the electron mobility of the first host material and the electron mobility of the second host material is less than the ratio of the absolute value of the difference between the hole mobility of the first host material and the second host material to the hole mobility of the second host material; and / or the absolute value of the difference between the electron mobility of the first host material and the second host material, and the ratio of the larger electron mobility between the electron mobility of the first host material and the electron mobility of the second host material is less than the ratio of the absolute value of the difference between the hole mobility of the first host material and the second host material to the hole mobility of the first host material.

[0035] To illustrate the specific structure of the display panel of this application, please refer to Figure 1 and Figure 2 , Figure 1 is a schematic diagram of the overall structure of the display panel in this application, Figure 2 It is a schematic cross-sectional structure diagram of an embodiment of the display area in the display panel of the present application.

[0036] In this embodiment, the display panel 100 has a display area a and a non-display area b surrounding the display area a. The display panel 100 includes a substrate 10 , a first insulating layer 20 , a second insulating layer 21 , a light emitting device layer, and a thin film encapsulation layer 30 .

[0037] In this embodiment, the light-emitting device layer includes a plurality of light-emitting devices 40, each of which includes a first electrode 41, a light-emitting functional layer 42, and a second electrode 43 stacked in a direction away from the substrate 10. The first electrode 41 and the light-emitting functional layer 42 of the light-emitting device layer are located only in the display area a, and only the second electrode 403 extends toward the non-display area b.

[0038] The first electrode 41 is an anode, and the second electrode 43 is a cathode.

[0039] In some embodiments, the first electrode 41 is made of a transparent conductive material, such as tin oxide, indium oxide, zinc oxide, ITO (indium tin oxide), IZO (indium zinc oxide), or other transparent conductive oxides. As will be appreciated, using a transparent conductive material for the first electrode 41 can improve the light transmittance and electrical conductivity of the display panel 100.

[0040] In some embodiments, the second electrode 43 may be made of a highly conductive material and a low work function material, such as Yb (ytterbium), Mg (magnesium), Ag (aluminum), Cr (chromium), Au (gold), and the like.

[0041] In some embodiments, an active layer P-Si is provided on the substrate 10 of the display area a, and the active layer includes a source region (S) and a drain region (D). A wiring connecting the drain region and the first electrode 41 is provided in the conductive layer M4 for transmitting signals to the light-emitting device 40.

[0042] In some embodiments, the display panel 100 further includes an active layer P-Si, a gate insulating layer, a gate layer M1, a capacitor dielectric layer, a capacitor plate layer M2, a first interlayer insulating layer, a source-drain layer M3, a second interlayer insulating layer, a fourth conductive layer M4, and a first insulating layer 20, which are stacked in sequence in a direction away from the substrate 10.

[0043] In some embodiments, the first insulating layer 20 is an organic planarization layer, and the organic planarization layer is located in the display area a and the non-display area b.

[0044] The second insulating layer 21 is a pixel defining layer (PDL), which has multiple pixel openings in the display area a. The light-emitting functional layer 42 is located in the pixel openings. The upper surface of the light-emitting functional layer 42 in the pixel openings is covered with a cathode, and the lower surface is provided with an anode, thereby forming a light-emitting device 40.

[0045] In some embodiments, the substrate 10 may be a flexible substrate or a rigid substrate. In one specific implementation scenario, the substrate 10 may be a polymer substrate, a plastic substrate, or an ultra-thin glass substrate. In another specific implementation scenario, the substrate 10 may be a glass substrate. This application is not limited to this.

[0046] In some embodiments, the material of the organic planarization layer may be polyimide (PI).

[0047] In some embodiments, the thin film encapsulation layer 30 includes a stacked first inorganic encapsulation layer 31, an organic encapsulation layer 32, and a second inorganic encapsulation layer 33. The first and second inorganic encapsulation layers 31, 33 are primary water vapor barrier layers, while the organic encapsulation layer 32 is used to extend the water vapor transmission path and relieve stress in the first and second inorganic encapsulation layers 31, 33.

[0048] In this embodiment, the light emitting device 40 includes a red (Red, R) light emitting device, a green (Green, G) light emitting device, and a blue (Blue, B) light emitting device.

[0049] In some embodiments, the light-emitting device 40 is a blue light-emitting device, and the light-emitting functional layer 42 includes a blue light-emitting layer. In other embodiments, the light-emitting device 40 is a green light-emitting device, and the light-emitting functional layer 42 includes a green light-emitting layer. In still other embodiments, the light-emitting device 40 is a red light-emitting device, and the light-emitting functional layer 42 includes a red light-emitting layer.

[0050] In this embodiment, the blue light-emitting layer is defined as the first color light-emitting layer.

[0051] In this embodiment, both the first host material and the second host material are electronic materials.

[0052] Among them, electronic materials are materials with electron transport properties and high electron mobility. Among them, the electron mobility of electronic materials is higher than the hole mobility.

[0053] In this embodiment, the hole mobility of the first host material is higher than the hole mobility of the second host material.

[0054] In this embodiment, the ratio of the absolute value of the difference in electron mobility between the first host material and the second host material to the smaller electron mobility of the electron mobility of the first host material and the electron mobility of the second host material is smaller than the ratio of the absolute value of the difference in hole mobility between the first host material and the second host material to the hole mobility of the second host material. And / or the ratio of the absolute value of the difference in electron mobility between the first host material and the second host material to the larger electron mobility of the electron mobility of the first host material and the electron mobility of the second host material is smaller than the ratio of the absolute value of the difference in hole mobility between the first host material and the second host material to the hole mobility of the first host material.

[0055] It can be understood that by making the hole mobility of the first main material higher than the hole mobility of the second main material, and making the ratio of the absolute value of the difference in the electron mobilities of the two to the smaller electron mobility of the two smaller than the ratio of the absolute value of the difference in the hole mobilities of the two to the hole mobility of the second main material, and / or making the ratio of the absolute value of the difference in the electron mobilities of the two to the larger electron mobility of the two smaller than the ratio of the absolute value of the difference in the hole mobilities of the two to the hole mobility of the first main material, the electron mobility of the first main material can be made the same or close to the electron mobility of the second main material, the first main material and the second main material have the same or close electron transport characteristics, and at the same time, the first main material and the second main material have hole transport characteristics that are quite different.

[0056] In some embodiments, the electron mobility of the first host material is the same as the electron mobility of the second host material. In other embodiments, the electron mobility of the first host material is close to the electron mobility of the second host material, and the electron mobility of the first host material is slightly less than or slightly greater than the electron mobility of the second host material, which is not limited in this application.

[0057] In some embodiments, the first host material and the second host material are both anthracene compounds. Specifically, the first host material can be selected from the following compounds A1 to A8:

[0058]

[0059] The second host material can be selected from the following compounds B1 to B7:

[0060]

[0061]

[0062] It can be understood that by making the first host material and the second host material included in the first color light-emitting layer both electronic materials, the electron transmission capability can be improved at low grayscale, thereby improving the low grayscale efficiency of the blue light-emitting layer and further improving the color shift problem.

[0063] In related technologies, only the electronic properties of the blue light host material are usually enhanced to improve the low grayscale characteristics. However, if only the electronic performance is enhanced and the hole performance is weak, the efficiency will roll off at high grayscales due to insufficient holes.

[0064] Different from the related art, this embodiment enables the first main material to have better hole performance than the second main material by making the hole mobility of the first main material higher than the hole mobility of the second main material, thereby improving the hole transmission capacity of the first color light-emitting layer at high grayscale, and then improving the efficiency roll-off problem.

[0065] Furthermore, by making the absolute value of the difference in electron mobility between the two main materials and the ratio of the electron mobility of the smaller electron mobility between the two less than the ratio of the absolute value of the difference in hole mobility between the two main materials and the hole mobility of the second main material, and / or by making the absolute value of the difference in electron mobility between the two main materials and the ratio of the electron mobility of the larger electron mobility between the two less than the ratio of the absolute value of the difference in hole mobility between the two main materials and the hole mobility of the first main material, the two main materials can have the same or similar electron transport characteristics and very different hole transport characteristics, so that the stronger electron transport characteristics of the two main materials can offset the enhanced hole transport ability of the first main material at low grayscale due to its strong hole performance, thereby balancing the electron transport ability and hole transport ability at low grayscale, to ensure that the low grayscale efficiency of the first color light-emitting layer will not be affected, and then the display panel 100 has better electron-hole balance characteristics and better display effect.

[0066] In this embodiment, the light emitting device 40 may be a single-layer OLED device or a stacked-layer OLED device.

[0067] See also Figure 3 , Figure 3 This is a schematic diagram of the structure of the first embodiment of the light-emitting device of the present application. In this embodiment, the light-emitting device 40 is a single-layer OLED device, and the light-emitting functional layer 42 includes a hole injection layer 421, a hole transport layer 422, a first color light-emitting layer 420, an electron transport layer 425, and an electron injection layer 426, which are arranged in this order.

[0068] In this embodiment, the first color light emitting layer 420 includes a mixture of a first host material and a second host material. Specifically, the mixture of the first host material and the second host material can be formed by a co-evaporation process.

[0069] In some embodiments, the volume ratio of the first host material to the second host material is 2:8 to 8:2. It is understood that within an appropriate range, as the amount of the second host material increases, the high brightness efficiency ratio of the first color light emitting layer 420 gradually increases, and the roll-off efficiency characteristics gradually improve.

[0070] In some embodiments, the absolute value of the temperature difference between the sublimation temperature of the first host material and the sublimation temperature of the second host material is less than or equal to 20°, for example, 5°, 10°, etc. In some embodiments, the sublimation temperature of the first host material is greater than the sublimation temperature of the second host material. In other embodiments, the sublimation temperature of the second host material is greater than the sublimation temperature of the first host material.

[0071] It can be understood that by controlling the absolute value of the temperature difference between the sublimation temperatures of the two main materials to be less than 20°, it is possible to facilitate the mixed steaming process, thereby making the distribution of the mixed materials more uniform.

[0072] In some embodiments, the first color light emitting layer 420 further includes a guest material. In some specific embodiments, the guest material includes at least one of an organic dye, a fluorescent material, or a phosphorescent material, which is not limited in this application.

[0073] In this embodiment, the ratio of the absolute value of the difference between the electron mobility of the first main material and the second main material to the smaller electron mobility of the electron mobility of the first main material and the electron mobility of the second main material is greater than or equal to 0 and less than or equal to 99, for example, it can be 0, 50, 99, etc.

[0074] In some embodiments, the ratio of the absolute value of the difference between the electron mobility of the first host material and the second host material to the smaller electron mobility between the electron mobility of the first host material and the electron mobility of the second host material is greater than or equal to 0 and less than or equal to 9, for example, it can be 3, 5, 7, 9, etc.

[0075] In some embodiments, if the electron mobility of the first host material is less than that of the second host material, the ratio is calculated by dividing the absolute value of the difference between the electron mobilities of the first and second host materials by the electron mobility of the first host material. In other embodiments, if the electron mobility of the second host material is less than that of the first host material, the ratio is calculated by dividing the absolute value of the difference between the electron mobilities of the first and second host materials by the electron mobility of the second host material.

[0076] In some embodiments, the ratio of the absolute value of the difference in electron mobility between the first host material and the second host material to the larger electron mobility of the first host material and the second host material is greater than or equal to 0 and less than or equal to 0.99, for example, and may be 0.92, 0.96, etc. Furthermore, the ratio of the absolute value of the difference in electron mobility between the first host material and the second host material to the larger electron mobility of the first host material and the second host material is greater than or equal to 0 and less than or equal to 0.9, for example, and may be 0, 0.50, 0.90, etc.

[0077] In some embodiments, if the electron mobility of the first host material is less than that of the second host material, the ratio is calculated by dividing the absolute value of the difference between the electron mobilities of the first and second host materials by the electron mobility of the second host material. In other embodiments, if the electron mobility of the second host material is less than that of the first host material, the ratio is calculated by dividing the absolute value of the difference between the electron mobilities of the first and second host materials by the electron mobility of the first host material.

[0078] In this embodiment, the ratio of the absolute value of the difference between the hole mobility of the first host material and the second host material to the hole mobility of the second host material is greater than 0 and less than or equal to 9999, for example, 100, 2000, 5000, etc.

[0079] In some embodiments, the ratio of the absolute value of the difference in hole mobility between the first host material and the second host material to the hole mobility of the second host material is greater than 0 and less than or equal to 99, for example, 10, 50, 90, etc.

[0080] In some embodiments, the electron mobility of the first host material is in the range of 10 -4 ~10 -2 cm 2 / Vs, the hole mobility range of the first host material is 10 -5 ~10 -3 cm 2 / Vs. The electron mobility of the second host material ranges from 10 -4 ~10 - 2 cm 2 / Vs, the hole mobility of the second host material is in the range of 10 -7 ~10 -5 cm 2 / Vs.

[0081] Among them, the electron mobility range of the first host material is 10 -4 ~10 -2 cm 2 / Vs means that the electron mobility of the first host material is greater than or equal to 10 -4 cm 2 / Vs, and less than or equal to 10 -2 cm 2 / Vs. The hole mobility of the first host material is in the range of 10 -5 ~10 -3 cm 2 / Vs means that the hole mobility of the first host material is greater than or equal to 10 -5 cm 2 / Vs, and less than or equal to 10 -3 cm 2 / Vs.

[0082] Among them, the electron mobility range of the second host material is 10 -4 ~10 -2 cm 2 / Vs means that the electron mobility of the second host material is greater than or equal to 10 -4 cm 2 / Vs, and less than or equal to 10 -2 cm 2 / Vs. The hole mobility of the second host material ranges from 10 -7 ~10 -5 cm 2 / Vs refers to the hole mobility of the second host material being greater than or equal to 10 -7 cm 2 / Vs, and less than or equal to 10 -5 cm 2 / Vs.

[0083] In some embodiments, the absolute value of the difference between the electron mobility of the first host material and the electron mobility of the second host material is greater than or equal to 0 and less than or equal to 0.0099 cm 2 / Vs, for example, can be 0.0025cm 2 / Vs, 0.0050m 2 / Vs, 0.0090m 2 / Vs, etc.

[0084] In some embodiments, the absolute value of the difference between the hole mobility of the first host material and the hole mobility of the second host material is greater than 0 and less than or equal to 0.0009999m 2 / Vs, for example, can be 0.0001000m 2 / Vs, 0.0006999m 2 / Vs, 0.0000900m 2 / Vs, etc.

[0085] In some embodiments, the electron mobility of the first host material is 10 -2 cm 2 / Vs, the hole mobility of the first host material is 10 -3 cm 2 / Vs. The electron mobility of the second host material is 10 -2 cm 2 / Vs, the hole mobility of the second host material is 10 -5 cm 2 / Vs. The absolute value of the difference in electron mobility between the first host material and the second host material is 0, and the ratio of this absolute value to the electron mobility of the first host material or the second host material is 0. The absolute value of the difference in hole mobility between the first host material and the second host material is 0. 2 / Vs, the ratio of the absolute value to the hole mobility of the second host material is 99, and the ratio of the absolute value to the hole mobility of the first host material is 0.99.

[0086] In some other specific embodiments, the electron mobility of the first host material is 5×10 -3 cm 2 / Vs, the hole mobility of the first host material is 7×10 -4 cm 2 / Vs. The electron mobility of the second host material is 4×10 -3 cm 2 / Vs, the hole mobility of the second host material is 5×10 -6 cm 2 / Vs. The absolute value of the difference in electron mobility between the first host material and the second host material is 0.001cm 2 / Vs, the ratio of this absolute value to the electron mobility of the second host material is 0.25, and the ratio of this absolute value to the electron mobility of the first host material is 0.2. The absolute value of the difference between the hole mobility of the first host material and the second host material is 0.000695cm 2 / Vs, the ratio of the absolute value to the hole mobility of the second host material is 139, and the ratio of the absolute value to the hole mobility of the first host material is 0.9926.

[0087] In some further embodiments, the electron mobility of the first host material is 6×10 -3 cm 2 / Vs, the hole mobility of the first host material is 9×10 -4 cm 2 / Vs. The electron mobility of the second host material is 8×10 -3 cm 2 / Vs, the hole mobility of the second host material is 7×10 -6 cm 2 / Vs. The absolute value of the difference in electron mobility between the first host material and the second host material is 0.002cm 2 / Vs, the absolute value of the difference between the electron mobility of the first host material and the electron mobility of the second host material is 0.33, and the absolute value of the difference between the hole mobility of the first host material and the second host material is 0.25. 2 / Vs, the ratio of the absolute value to the hole mobility of the second host material is 127.57, and the ratio of the absolute value to the hole mobility of the first host material is 0.9922.

[0088] It can be understood that by ensuring that both the first and second host materials have high electron mobility, electron transport capacity can be enhanced at low grayscales, thereby improving the low-grayscale efficiency of the first-color light-emitting layer and, in turn, alleviating color shift. Furthermore, by ensuring that the hole mobility of the first host material is higher than that of the second host material, the first host material can have better hole performance relative to the second host material, thereby improving the hole transport capacity of the first-color light-emitting layer at high grayscales and, in turn, alleviating efficiency roll-off. Furthermore, by making the absolute value of the difference in electron mobility between the two main materials and the ratio of the electron mobility of the smaller electron mobility between the two less than the ratio of the absolute value of the difference in hole mobility between the two main materials and the hole mobility of the second main material, and / or by making the absolute value of the difference in electron mobility between the two main materials and the ratio of the electron mobility of the larger electron mobility between the two less than the ratio of the absolute value of the difference in hole mobility between the two main materials and the hole mobility of the first main material, the two main materials can have the same or similar electron transport characteristics and very different hole transport characteristics, so that the stronger electron transport characteristics of the two main materials can offset the enhanced hole transport ability of the first main material at low grayscale due to its strong hole performance, thereby balancing the electron transport ability and hole transport ability at low grayscale, to ensure that the low grayscale efficiency of the first color light-emitting layer will not be affected, and then the display panel 100 has better electron-hole balance characteristics and better display effect.

[0089] In some embodiments, the display panel 100 includes an electron blocking layer and a hole blocking layer. The electron blocking layer is located between the first electrode 41 and the first color light emitting layer 420 , and the hole blocking layer is located between the second electrode 43 and the first color light emitting layer 420 .

[0090] In other embodiments, the display panel 100 may include only an electron blocking layer or only a hole blocking layer, which is not limited in this application.

[0091] Specifically, see Figure 4 , Figure 4Schematic diagram of the structure of the second embodiment of the light-emitting device of the present application. In this embodiment, the light-emitting device 40 is a single-layer OLED device. The light-emitting functional layer 42, the first electrode 41, and the second electrode 43 form a single-layer light-emitting unit. The light-emitting functional layer 42 includes a hole injection layer 421, a hole transport layer 422, an electron blocking layer 423, a first color light-emitting layer 420, a hole blocking layer 424, an electron transport layer 425, and an electron injection layer 426, which are arranged in this order.

[0092] It can be understood that the electron blocking layer 423 can block or slow down the continued transmission of electrons, thereby reducing electron leakage current and protecting the hole transport material from being damaged.

[0093] It can be understood that the hole blocking layer 424 can block or slow down the continued transmission of holes, thereby reducing the hole leakage current, and then balancing the carriers in the light-emitting functional layer 42 and improving the light-emitting efficiency.

[0094] In this embodiment, the HOMO energy level of at least one of the first host material and the second host material is less than or equal to the HOMO energy level of the electron blocking layer 423 .

[0095] The HOMO energy level of at least one of the first host material and the second host material is less than or equal to the HOMO energy level of the electron blocking layer 423 , which means that the HOMO energy level of at least one of the first host material and the second host material is deeper than the HOMO energy level of the electron blocking layer 423 .

[0096] In some embodiments, only the HOMO energy level of the first host material is less than or equal to the HOMO energy level of the electron blocking layer 423. In other embodiments, only the HOMO energy level of the second host material is less than or equal to the HOMO energy level of the electron blocking layer 423. In still other embodiments, the HOMO energy level of both the first host material and the second host material is less than or equal to the HOMO energy level of the electron blocking layer 423, which is not limited in this application.

[0097] Furthermore, the absolute value of the energy difference between the HOMO energy level of at least one of the first host material and the second host material and the HOMO energy level of the electron blocking layer 423 is less than or equal to 0.3 eV, for example, it can be 0.1 eV, 0.2 eV, etc. In some embodiments, only the absolute value of the energy difference between the HOMO energy level of the first host material and the HOMO energy level of the electron blocking layer 423 is less than or equal to 0.3 eV, for example, it can be 0.1 eV, 0.2 eV, etc. In other embodiments, only the absolute value of the energy difference between the HOMO energy level of the second host material and the HOMO energy level of the electron blocking layer 423 is less than or equal to 0.3 eV, for example, it can be 0.05 eV, 0.15 eV, etc. In some other embodiments, the absolute value of the energy difference between the HOMO energy level of the first host material, the HOMO energy level of the second host material and the HOMO energy level of the electron blocking layer 423 is less than or equal to 0.3 eV, for example, it can be 0.18 eV, 0.28 eV, etc., which is not limited in this application.

[0098] In some specific embodiments, the HOMO energy level of the first host material is -5.4 eV, and the HOMO energy level of the electron blocking layer 423 is -5.1 eV, that is, the HOMO energy level of the first host material is lower than the HOMO energy level of the electron blocking layer 423, and the absolute value of the energy difference between the HOMO energy levels of the two is 0.3 eV.

[0099] It can be understood that by making the HOMO energy level of at least one of the first host material and the second host material less than or equal to the HOMO energy level of the electron blocking layer 423 , electron injection between the electron blocking layer 423 and the first color light emitting layer 420 is facilitated.

[0100] In this embodiment, the LUMO energy level of at least one of the first host material and the second host material is greater than or equal to the LUMO energy level of the hole blocking layer 424. In some embodiments, only the LUMO energy level of the first host material is greater than or equal to the LUMO energy level of the hole blocking layer 424. In other embodiments, only the LUMO energy level of the second host material is greater than or equal to the LUMO energy level of the hole blocking layer 424. In still other embodiments, the LUMO energy level of both the first host material and the second host material is greater than or equal to the LUMO energy level of the hole blocking layer 424, which is not limited in this application.

[0101] Furthermore, the absolute value of the energy difference between the LUMO energy level of at least one of the first host material and the second host material and the LUMO energy level of the hole blocking layer 424 is less than or equal to 0.3 eV. In some embodiments, only the absolute value of the energy difference between the LUMO energy level of the first host material and the LUMO energy level of the hole blocking layer 424 is less than or equal to 0.3 eV, for example, 0.1 eV, 0.2 eV, etc. In other embodiments, only the absolute value of the energy difference between the LUMO energy level of the second host material and the LUMO energy level of the hole blocking layer 424 is less than or equal to 0.3 eV, for example, 0.15 eV, 0.25 eV, etc. In still other embodiments, the absolute value of the energy difference between the LUMO energy level of the first host material and the LUMO energy level of the second host material and the LUMO energy level of the hole blocking layer 424 is less than or equal to 0.3 eV, for example, 0.05 eV, 0.23 eV, etc., which is not limited in this application.

[0102] In some specific embodiments, the LUMO energy level of the second host material is -2.4eV, and the LUMO energy level of the hole blocking layer 424 is -2.6eV, that is, the LUMO energy level of the second host material is greater than the LUMO energy level of the hole blocking layer 424, and the absolute value of the energy difference between the LUMO energy levels of the two is 0.2eV.

[0103] It can be understood that by making the LUMO energy level of at least one of the first host material and the second host material greater than or equal to the LUMO energy level of the hole blocking layer 424 , it is beneficial to inject holes between the first color light emitting layer 420 and the hole blocking layer 424 .

[0104] In this embodiment, the LUMO level of the first host material is greater than the HOMO level of the second host material; and / or the HOMO level of the first host material is less than the LUMO level of the second host material.

[0105] In some embodiments, the LUMO level of the first host material is greater than the HOMO level of the second host material, and the HOMO level of the first host material is less than the LUMO level of the second host material. In other embodiments, only the LUMO level of the first host material is greater than the HOMO level of the second host material. In still other embodiments, only the HOMO level of the first host material is less than the LUMO level of the second host material.

[0106] Furthermore, in some embodiments, the absolute value of the energy difference between the LUMO energy level of the first host material and the HOMO energy level of the second host material is less than 2.8 eV, for example, it can be 1.0 eV, 2.0 eV, etc. In other embodiments, the absolute value of the energy difference between the HOMO energy level of the first host material and the LUMO energy level of the second host material is less than 2.8 eV, for example, it can be 0.5 eV, 2.5 eV, etc. In still other embodiments, the absolute value of the energy difference between the LUMO energy level of the first host material and the HOMO energy level of the second host material is less than 2.8 eV, and the absolute value of the energy difference between the HOMO energy level of the first host material and the LUMO energy level of the second host material is less than 2.8 eV, for example, it can be 0.1 eV, 1.5 eV, etc., and this application is not limited to this.

[0107] In some specific embodiments, the LUMO level of the first host material is -2.8 eV, the HOMO level of the first host material is -5.1 eV, the LUMO level of the second host material is -2.4 eV, and the HOMO level of the first host material is -5.0 eV. That is, the LUMO level of the first host material is greater than the HOMO level of the second host material, and the HOMO level of the first host material is less than the LUMO level of the second host material. At the same time, the absolute value of the energy difference between the LUMO energy level of the first host material and the HOMO energy level of the second host material is 2.2 eV (less than 2.8 eV), and the absolute value of the energy difference between the HOMO energy level of the first host material and the LUMO energy level of the second host material is 2.7 eV (less than 2.8 eV).

[0108] It can be understood that by controlling the energy level difference between the LUMO energy level and the HOMO energy level of the two blue light host materials, the overall carrier injection performance in the light-emitting device 40 can be improved, thereby further improving the luminous efficiency of the light-emitting device 40.

[0109] In some embodiments, at least one first color light emitting layer includes a plurality of first color light emitting layers, and a charge generation layer is disposed between two adjacent first color light emitting layers. Figure 5 , Figure 5 It is a structural schematic diagram of the third embodiment of the light-emitting device of the present application.

[0110] In this embodiment, the light-emitting device 40 is a stacked OLED device, and the light-emitting functional layer 42, the first electrode 41 and the second electrode 43 form a stacked light-emitting unit. The light-emitting functional layer 42 includes two first color light-emitting layers 420, and a charge generation layer 427 is arranged between the two first color light-emitting layers 420.

[0111] Specifically, the light-emitting functional layer 42 includes a hole injection layer 421, a first hole transport layer 4221, a first color light-emitting layer 420, a first electron transport layer 4251, a charge generation layer 427, a second hole transport layer 4222, a first color light-emitting layer 420, a second electron transport layer 4252 and an electron injection layer 426, which are arranged in sequence.

[0112] In this embodiment, at least one of the two first color light emitting layers 420 includes a mixture of a first host material and a second host material, and the other includes at least one of the first host material and the second host material.

[0113] In some embodiments, both first color light-emitting layers 420 include a mixture of a first host material and a second host material. In other embodiments, one first color light-emitting layer 420 includes a mixture of the first host material and the second host material, and the other first color light-emitting layer 420 includes the first host material. In still other embodiments, one first color light-emitting layer 420 includes a mixture of the first host material and the second host material, and the other first color light-emitting layer 420 includes the second host material.

[0114] See also Figure 6 , Figure 6 This is a schematic diagram of the structure of the fourth embodiment of the light-emitting device of the present application. In this embodiment, the light-emitting device 40 is a dual-light-emitting layer device. The light-emitting functional layer 42, the first electrode 41, and the second electrode 43 form a stacked light-emitting unit. The first color light-emitting layer includes a first sublayer 4203 and a second sublayer 4204 arranged in a stacked manner.

[0115] Specifically, the light-emitting functional layer 42 includes a hole injection layer 421 , a hole transport layer 422 , a first sublayer 4203 , a second sublayer 4204 , an electron transport layer 425 and an electron injection layer 426 , which are arranged in sequence.

[0116] In this embodiment, at least one of the first sub-layer 4203 and the second sub-layer 4204 includes a first host material, and at least one includes a second host material.

[0117] In some embodiments, both the first sublayer 4203 and the second sublayer 4204 include a mixture of the first host material and the second host material, and the mass fraction of the first host material in the first sublayer 4203 is different from the mass fraction of the first host material in the second sublayer 4204. Specifically, the mass fraction of the first host material in the first sublayer 4203 is less than the mass fraction of the first host material in the second sublayer 4204. For example, both the first sublayer 4203 and the second sublayer 4204 include a mixture of the first host material and the second host material, but the mass fraction of the first host material in the first sublayer 4203 is 20% or 30%, while the mass fraction of the first host material in the second sublayer 4204 is 60% or 70%.

[0118] In other embodiments, the first sub-layer 4203 includes a mixture of the first host material and the second host material, and the second sub-layer 4204 includes the first host material.

[0119] In some further embodiments, the first sub-layer 4203 includes a mixture of the first host material and the second host material, and the second sub-layer 4204 includes the second host material.

[0120] In some other embodiments, the first sub-layer 4203 includes a first host material, and the second sub-layer 4204 includes a mixture of the first host material and the second host material.

[0121] In some further embodiments, the first sub-layer 4203 includes the second host material, and the second sub-layer 4204 includes a mixture of the first host material and the second host material.

[0122] In other embodiments, the first sub-layer 4203 includes a first host material, and the second sub-layer 4204 includes a second host material.

[0123] In some other embodiments, the first sub-layer 4203 includes the second main material, and the second sub-layer 4204 includes the first main material, which is not limited in this application.

[0124] In some embodiments, the display panel 100 further includes other color light-emitting layers and a charge generation layer. The other color light-emitting layer is disposed on at least one side of the first color light-emitting layer 420, and the charge generation layer is disposed between the first color light-emitting layer 420 and the other color light-emitting layer. Figure 7 , Figure 7Schematic diagram of the structure of the fifth embodiment of the light-emitting device of the present application. In this embodiment, the light-emitting functional layer 42 includes a hole injection layer 421, a first hole transport layer 4221, a second color light-emitting layer 428, a first electron transport layer 4251, a first charge generation layer 4271, a second hole transport layer 4222, a first color light-emitting layer 420, a second electron transport layer 4252, a second charge generation layer 4272, a third hole transport layer 4223, a third color light-emitting layer 429, a third electron transport layer 4253, and an electron injection layer 426, arranged in this order.

[0125] In this embodiment, the first color light emitting layer 420 includes a mixture of a first host material and a second host material.

[0126] In some embodiments, the second color light emitting layer 428 is a red light emitting layer, and the third color light emitting layer 429 is a green light emitting layer. In other embodiments, the second color light emitting layer 428 is a green light emitting layer, and the third color light emitting layer 429 is a red light emitting layer, which is not limited in this application.

[0127] Correspondingly, the present application provides a display panel, comprising: a first electrode and a second electrode disposed opposite each other; at least one first-color light-emitting layer disposed between the first electrode and the second electrode; the at least one first-color light-emitting layer comprising a first host material and a second host material; a hole transport layer disposed between the first electrode and the first-color light-emitting layer; and an electron transport layer disposed between the second electrode and the first-color light-emitting layer; wherein the hole mobility of the first host material is higher than the hole mobility of the second host material; and the ratio of the absolute value of the difference between the electron mobilities of the first host material and the second host material to the smaller electron mobility of the electron mobility of the first host material and the electron mobility of the second host material is greater than or equal to 0 and less than or equal to 99, for example, 10, 40, etc. Furthermore, the ratio of the absolute value of the difference between the electron mobilities of the first host material and the second host material to the smaller electron mobility of the electron mobility of the first host material and the electron mobility of the second host material is greater than or equal to 0 and less than or equal to 9, for example, 2, 3, etc.

[0128] The ratio of the absolute value of the difference between the hole mobility of the first main material and the second main material to the hole mobility of the second main material is greater than 0 and less than or equal to 9999, for example, it can be 999, 4000, etc.; further, the ratio of the absolute value of the difference between the hole mobility of the first main material and the second main material to the hole mobility of the second main material is greater than 0 and less than or equal to 99, for example, it can be 9, 48, etc.

[0129] In addition, the ratio of the absolute value of the difference in hole mobility between the first host material and the second host material to the hole mobility of the first host material is greater than 0 and less than or equal to 0.9999, for example, it can be 0.999, 0.686, etc. Further, the ratio of the absolute value of the difference in hole mobility between the first host material and the second host material to the hole mobility of the first host material is greater than 0 and less than or equal to 0.99, for example, it can be 0.9, 0.6, etc.

[0130] Specifically, the electron mobility of the first host material is in the range of 10 -4 ~10 -2 cm 2 / Vs; the electron mobility of the second host material is in the range of 10 -4 ~10 -2 cm 2 / Vs; the hole mobility of the first host material is in the range of 10 -5 ~10 -3 cm 2 / Vs; the hole mobility of the second host material is in the range of 10 -7 ~10 -5 cm 2 / Vs.

[0131] Correspondingly, the present application provides a display device comprising any one of the above-mentioned display panels.

[0132] To facilitate understanding of the embodiments of the present application, the present application provides the following non-limiting embodiments to further illustrate the present application in detail.

[0133] Comparative Example 1

[0134] A light-emitting device was prepared, which included an anode, a cathode, and a light-emitting functional layer located between the anode and the cathode. The light-emitting functional layer only included a blue light-emitting host material (BH1), which had both high electron mobility and hole mobility. The electron mobility of BH1 was 2×10 -3 cm 2 / Vs, the hole mobility is 4×10 -5 cm 2 / Vs.

[0135] Comparative Example 2

[0136] A light-emitting device was prepared, which included an anode, a cathode, and a light-emitting functional layer located between the anode and the cathode. The light-emitting functional layer only included a blue light-emitting host material (BH2), which has a high electron mobility and a low hole mobility. The electron mobility of BH2 is 4×10 -3 cm 2 / Vs, the hole mobility is 7×10-7 cm 2 / Vs.

[0137] Comparative Example 3

[0138] A light-emitting device is prepared, which includes an anode, a cathode, and a light-emitting functional layer located between the anode and the cathode. The light-emitting functional layer includes a mixture of two blue light-emitting host materials (BH3 and BH4). The electron mobility of BH3 and BH4 is quite different, while the hole mobility is relatively close. Among them, the electron mobility of BH3 is 10 -2 cm 2 / Vs, the hole mobility is 5×10 -7 cm 2 / Vs. The electron mobility of BH4 is 4×10 -4 cm 2 / Vs, the hole mobility is 2×10 -7 cm 2 / Vs.

[0139] Example

[0140] A light-emitting device is prepared, which includes an anode, a cathode, and a light-emitting functional layer located between the anode and the cathode. The light-emitting functional layer includes a mixture of two blue light-emitting host materials (BH5 and BH6), both of which are electronic materials with high electron mobility, and the electron mobility of BH5 and BH6 is 10 -3 cm 2 / Vs, the hole mobility of BH5 is 10 -6 cm 2 / Vs, the hole mobility of BH6 is 10 -4 cm 2 / Vs. BH5 is the second host material in this application, and BH6 is the first host material in this application.

[0141] The light-emitting functional layers corresponding to Comparative Examples 1, 2, and 3 and the embodiment were tested at low grayscale and high grayscale, and the test results are shown in Table 1:

[0142] Table 1

[0143]

[0144]

[0145] Among them, the low grayscale efficiency ratio is equal to the current density of 0.1mA / cm 2 The efficiency under the grayscale is divided by the maximum efficiency; the high grayscale efficiency ratio is equal to the current density of 20mA / cm 2The efficiency under the condition of 15mA / cm2 is divided by the maximum efficiency; the efficiency is the efficiency value of the current density, and LT95 (the time taken for the brightness to decay to 95% of the initial brightness, the table shows the normalized value) is the efficiency under the condition of 15mA / cm2 2 The results of the conditional delivery.

[0146] Please refer to Figure 8 , Figure 8 This is a comparative diagram of the normalized efficiency and efficiency of the light-emitting functional layer in the comparative example and the embodiment of the present application. Among them, the normalized efficiency comparison diagram is used to intuitively reflect the proportion of low grayscale efficiency and high grayscale efficiency, and the efficiency comparison diagram is used to reflect the change in efficiency.

[0147] From the above table and Figure 8 It can be seen that the light-emitting functional layer in Comparative Example 1 has a lower efficiency at low grayscale and a higher efficiency at high grayscale, that is, the use of a single bipolar host material can improve the efficiency roll-off, but cannot improve the color deviation. The light-emitting functional layer in Comparative Example 2 has a higher efficiency at low grayscale, but a significant efficiency roll-off at high grayscale, that is, the use of only electronic materials can improve the color deviation, but cannot improve the efficiency roll-off. The light-emitting functional layer in Comparative Example 3 has a lower efficiency at low grayscale and a higher efficiency at high grayscale, that is, the use of two electronic materials with a large difference in electron mobility and close hole mobility can improve the efficiency roll-off, but cannot improve the color deviation. The light-emitting functional layer in the embodiment has a higher efficiency at low grayscale and is still relatively high at high grayscale, that is, the use of two electronic materials with the same electron mobility and one of which has a higher hole mobility in this application can improve both the color deviation and the efficiency roll-off.

[0148] The reason why the above comparative example cannot simultaneously improve both color cast and efficiency roll-off is as follows:

[0149] In Comparative Example 1, the electronic and hole properties of BH1 are relatively strong. At high grayscale, the higher hole mobility provided by BH1 can improve the efficiency roll-off caused by insufficient holes. At the same time, the hole transport layer is close to the anode, and its hole injection ability is inherently strong. When the current density is low, due to the weak electron transport ability, the higher hole mobility of BH1 will cause excess holes, further hindering electron transport, resulting in low efficiency at low grayscale.

[0150] In Comparative Example 2, BH2 has stronger electron performance and weaker hole performance. Because the electron performance is stronger than the hole performance, it can ensure electron transmission capacity at low grayscales, thereby improving low grayscale efficiency. However, this will lead to weak hole transmission capacity at high grayscales, which in turn causes a significant efficiency roll-off.

[0151] In Comparative Example 3, BH3 and BH4 have different electronic properties: one has stronger electronic properties, the other has weaker ones, and both have similar hole properties. This is equivalent to enhancing the hole properties in terms of the relative properties of holes and electrons, resulting in similar properties as in Comparative Example 1. That is, when the hole properties of two host materials are similar, if the electronic properties of one host material are relatively weak, the low grayscale efficiency caused by the strong hole properties at low current density cannot be offset. Therefore, both host materials must have high and similar electron transport properties, as embodied in the examples.

[0152] Furthermore, it can be seen from the above table that compared with the lifespan of the light-emitting functional layer in comparative example 1, the lifespan of the light-emitting functional layer in comparative examples 2 and 3 is significantly reduced, while the lifespan of the light-emitting functional layer in the embodiment is not significantly reduced. Therefore, the present application can take into account both improving color deviation and improving efficiency roll-off while avoiding reducing the service life, thereby enabling the display panel to have better electron-hole balance characteristics and better display effects.

[0153] Unlike related art, this application utilizes both the first and second host materials included in the first-color light-emitting layer to be electronic materials, thereby enhancing electron transport capabilities at low grayscales, thereby improving the low-grayscale efficiency of the first-color light-emitting layer and subsequently alleviating color shift issues. Furthermore, by ensuring that the hole mobility of the second host material is higher than that of the first host material, and that the difference in hole mobility between the two host materials is greater than the difference in electron mobility between the two host materials, the second host material can have better hole performance, thereby improving the hole transport capability of the first-color light-emitting layer at high grayscales and subsequently alleviating efficiency roll-off issues. Furthermore, by making the electron mobility of the first main material less than or equal to the electron mobility of the second main material, the electron transport characteristics of the two main materials can be made close to or the same, and then the stronger electron transport characteristics of the two main materials can offset the enhanced hole transport ability of the second main material at low grayscale due to its strong hole performance, thereby balancing the electron transport ability and hole transport ability at low grayscale, thereby ensuring that the low grayscale efficiency of the first color light-emitting layer will not be affected, and then the display panel has better electron-hole balance characteristics and better display effects.

[0154] The above description is only an implementation method of the present application and does not limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made using the contents of the description and drawings of this application, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A display panel, characterized in that: include: a first electrode and a second electrode disposed opposite to each other; At least one first color light-emitting layer is provided between the first electrode and the second electrode; at least one first color light-emitting layer comprises a first host material and a second host material; wherein the hole mobility of the first host material is higher than the hole mobility of the second host material; a ratio of an absolute value of a difference in electron mobility between the first host material and the second host material to the smaller of the electron mobility of the first host material and the electron mobility of the second host material, which is smaller than a ratio of an absolute value of a difference in hole mobility between the first host material and the second host material to the hole mobility of the second host material; and / or, The ratio of the absolute value of the difference between the electron mobility of the first host material and the second host material to the larger electron mobility of the electron mobility of the first host material and the electron mobility of the second host material is smaller than the ratio of the absolute value of the difference between the hole mobility of the first host material and the second host material to the hole mobility of the first host material.

2. The display panel according to claim 1, wherein: The first color light emitting layer includes a mixture of the first host material and the second host material.

3. The display panel according to claim 1, wherein: The first color light-emitting layer includes a first sublayer and a second sublayer that are stacked, and the first sublayer is located between the first electrode and the second sublayer; At least one of the first sublayer and the second sublayer comprises the first host material, and at least one comprises the second host material; Alternatively, the first sublayer and the second sublayer both include a mixture of the first host material and the second host material, and the mass fraction of the first host material in the first sublayer is different from the mass fraction of the first host material in the second sublayer; Alternatively, the first sub-layer includes a mixture of the first host material and the second host material, and the second sub-layer includes the first host material or the second host material; Alternatively, the first sub-layer includes the first host material or the second host material, and the second sub-layer includes a mixture of the first host material and the second host material; Alternatively, the first sublayer comprises a first host material and the second sublayer comprises a second host material; Alternatively, the first sub-layer includes the second host material, and the second sub-layer includes the first host material.

4. The display panel according to claim 1, wherein: The at least one first color light-emitting layer includes a plurality of first color light-emitting layers, and a charge generation layer is provided between two adjacent first color light-emitting layers; Alternatively, some of the first color light-emitting layers in the plurality of first color light-emitting layers include the first host material and the second host material.

5. The display panel according to claim 1, wherein: The display panel further includes another color light-emitting layer and a charge generation layer, wherein the other color light-emitting layer is provided on at least one side of the first color light-emitting layer, and the charge generation layer is provided between the first color light-emitting layer and the other color light-emitting layer; Alternatively, the other color light-emitting layer includes a second color light-emitting layer and / or a third color light-emitting layer.

6. The display panel according to claim 1, wherein: a ratio of an absolute value of a difference between electron mobilities of the first host material and the second host material to the smaller electron mobility of the first host material and the second host material is greater than or equal to 0 and less than or equal to 99; and / or, a ratio of an absolute value of a difference between electron mobilities of the first host material and the second host material to a larger electron mobility of the first host material or the second host material is greater than or equal to 0 and less than or equal to 0.99; Alternatively, a ratio of an absolute value of a difference between the electron mobilities of the first host material and the second host material to the smaller electron mobility of the electron mobility of the first host material and the electron mobility of the second host material is greater than or equal to 0 and less than or equal to 9; Alternatively, a ratio of an absolute value of a difference between electron mobilities of the first host material and the second host material to a larger electron mobility of the first host material or the second host material is greater than or equal to 0 and less than or equal to 0.9; Alternatively, a ratio of an absolute value of a difference in hole mobility between the first host material and the second host material to a hole mobility of the second host material is greater than 0 and less than or equal to 9999; Alternatively, a ratio of an absolute value of a difference in hole mobility between the first host material and the second host material to a hole mobility of the second host material is greater than 0 and less than or equal to 99; Alternatively, a ratio of an absolute value of a difference in hole mobility between the first host material and the second host material to the hole mobility of the first host material is greater than 0 and less than or equal to 0.9999; Alternatively, a ratio of an absolute value of a difference in hole mobility between the first host material and the second host material to the hole mobility of the first host material is greater than 0 and less than or equal to 0.99; Alternatively, the absolute value of the difference between the electron mobility of the first host material and the electron mobility of the second host material is greater than or equal to 0 and less than or equal to 0.0099 cm 2 / Vs; Alternatively, the absolute value of the difference between the hole mobility of the first host material and the hole mobility of the second host material is greater than 0 and less than or equal to 0.0009999m 2 / Vs; Alternatively, the electron mobility of the first host material is in the range of 10 -4 ~10 -2 cm 2 / Vs; Alternatively, the electron mobility of the second host material is in the range of 10 -4 ~10 -2 cm 2 / Vs; Alternatively, the hole mobility of the first host material is in the range of 10 -5 ~10 -3 cm 2 / Vs; Alternatively, the hole mobility of the second host material is in the range of 10 -7 ~10 -5 cm 2 / Vs; Alternatively, the first color light-emitting layer is a blue light-emitting layer.

7. The display panel according to claim 1, wherein: The display panel includes an electron blocking layer and a hole blocking layer, wherein the electron blocking layer is located between the first electrode and the first color light-emitting layer, and the hole blocking layer is located between the second electrode and the first color light-emitting layer; The HOMO energy level of at least one of the first host material and the second host material is less than or equal to the HOMO energy level of the electron blocking layer; and / or, The LUMO energy level of at least one of the first host material and the second host material is greater than or equal to the LUMO energy level of the hole blocking layer; Alternatively, the absolute value of the energy difference between the HOMO energy level of at least one of the first host material and the second host material and the HOMO energy level of the electron blocking layer is less than or equal to 0.3 eV; Alternatively, an absolute value of an energy difference between a LUMO energy level of at least one of the first host material and the second host material and a LUMO energy level of the hole blocking layer is less than or equal to 0.3 eV.

8. The display panel according to claim 1, wherein: The LUMO energy level of the first host material is greater than the HOMO energy level of the second host material; and / or, The HOMO energy level of the first host material is lower than the LUMO energy level of the second host material; Alternatively, the absolute value of the energy difference between the LUMO energy level of the first host material and the HOMO energy level of the second host material is less than 2.8 eV; and / or, An absolute value of an energy difference between a HOMO energy level of the first host material and a LUMO energy level of the second host material is less than 2.8 eV.

9. The display panel according to claim 1, wherein: The first color light-emitting layer further includes a guest material; Alternatively, the volume ratio of the first host material to the second host material is 2:8 to 8:2; Alternatively, the absolute value of the temperature difference between the sublimation temperature of the first host material and the sublimation temperature of the second host material is less than or equal to 20° C.; Alternatively, the guest material includes at least one of an organic dye, a fluorescent material, or a phosphorescent material.

10. A display device, characterized in that: The display panel comprises the display panel according to any one of claims 1 to 9.

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