Material screening method, light-emitting device and display panel

Abstract

The present invention discloses a material screening method, a light-emitting device, and a display panel. The screening method includes: providing a plurality of materials to be screened; using each material to be screened as a light-emitting layer material, producing a plurality of first single-electron devices, each of which includes a monochromatic light-emitting layer and a first hole blocking layer, wherein the first hole blocking layer is the same and the material of the monochromatic light-emitting layer is different among the plurality of first single-electron devices; providing a second single-electron device including a second hole blocking layer, wherein the first hole blocking layer and the second hole blocking layer are the same; obtaining a first activation energy Ea of each first single-electron device. i and the second activation energy Ea of the second single-electron device c ; According to the first activation energy Ea corresponding to each first single-electron device i and the second activation energy Ea of the second single-electron device c A plurality of first target light-emitting layer materials are screened and used as the main material of the light-emitting layer of the light-emitting device, thereby increasing the light-emitting life of the light-emitting device and improving the overall life of the display panel.

Description

Technical Field

[0001] The present invention relates to the field of display, and in particular to a material screening method, a light-emitting device and a display panel. Background Art

[0002] With the rapid development of electronic devices, users have higher and higher requirements for screen-to-body ratio, making the full-screen display of electronic devices receive more and more attention in the industry.

[0003] Organic Light-Emitting Diode (OLED) display panels have the advantages of high image quality, power saving, thin body and wide application range. They are widely used in various consumer electronic products such as mobile phones, televisions, personal digital assistants, digital cameras, laptops, desktop computers, etc., becoming the mainstream display panel in the display field.

[0004] However, in the process of emitting white light from a general OLED display panel, the luminance of the green light-emitting device accounts for the highest proportion among the red, green, and blue light-emitting devices. Therefore, in order to improve the quality and life of the white light emitted by the OLED display panel, it is necessary to focus on improving the luminous life of the green light-emitting device.

[0005] Therefore, there is an urgent need for a material screening method, a light-emitting device and a display panel. Summary of the Invention

[0006] The present invention provides a material screening method, a light-emitting device, and a display panel. The light-emitting layer material screened by the material screening method provided in the present invention can increase the light-emitting life of the light-emitting device, thereby improving the overall life of the display panel and enhancing the user experience.

[0007] In a first aspect, an embodiment of the present application provides a material screening method for screening a main material of a light-emitting layer of a light-emitting device. The screening method includes:

[0008] Provide multiple materials to be screened;

[0009] Using each material to be screened as a light-emitting layer material, a plurality of first single-electron devices are manufactured, each of the first single-electron devices comprising a monochromatic light-emitting layer and a first hole-blocking layer, wherein the first hole-blocking layers of the plurality of first single-electron devices are the same and the materials of the monochromatic light-emitting layers are different;

[0010] providing a second single-electron device, the second single-electron device comprising a second hole blocking layer, wherein the first hole blocking layer is the same as the second hole blocking layer;

[0011] Obtain the first activation energy Ea of each first single-electron device i and the second activation energy Ea of the second single-electron device c ;

[0012] According to the first activation energy Ea corresponding to each first single-electron device i and the second activation energy Ea of the second single-electron device c A plurality of first target light-emitting layer materials are screened and obtained to be used as the main light-emitting layer materials of the light-emitting device.

[0013] In a possible implementation of the first aspect of the embodiment of the present application, according to the first activation energy Ea corresponding to each first single-electron device i and the second activation energy Ea of the second single-electron device c The step of screening and obtaining a plurality of first target light-emitting layer materials for use as the main material of the light-emitting layer of the light-emitting device comprises:

[0014] Using each first activation energy Ea i and the second activation energy Ea c The activation energy difference ΔEa between the first hole blocking layer and the monochromatic light-emitting layer in each first single-electron device is calculated. i ;

[0015] A plurality of first target light-emitting layer materials are screened using the first standard activation energy difference ΔEaa.

[0016] In a possible implementation of the first aspect of the embodiments of the present application, the monochromatic light-emitting layer is a green light-emitting layer, and the absolute value of the first standard activation energy difference ΔEaa ranges from 0.1 eV to 0.2 eV.

[0017] In a possible implementation of the first aspect of the embodiment of the present application, the step of obtaining the first standard activation energy difference ΔEaa includes:

[0018] Producing a plurality of test monochromatic light-emitting devices, each test monochromatic light-emitting device comprising a third hole blocking layer identical to the first hole blocking layer and a test monochromatic light-emitting layer, wherein the main material of the light-emitting layer of each test monochromatic light-emitting device is different from each other;

[0019] Acquire test parameters of each tested monochromatic light-emitting device, and screen and obtain a plurality of second target light-emitting layer host materials using the first standard test parameters;

[0020] Obtain the test activation energy difference ΔEa between the third hole blocking layer and the main material of the test monochromatic light-emitting layer in the test monochromatic light-emitting device corresponding to each second target light-emitting layer main material k , and according to the test activation energy difference ΔEa k Obtain the first standard activation energy difference ΔEaa.

[0021] In a possible implementation of the first aspect of the embodiment of the present application, in the step of obtaining test parameters of each test monochromatic light-emitting device and screening a plurality of second target light-emitting layer materials using the first standard test parameters,

[0022] The first standard test parameter is the lifespan parameter of the light emitting device.

[0023] In a possible implementation of the first aspect of the embodiments of the present application, the screening method is used to screen the main material of the light-emitting layer of a green light-emitting device.

[0024] The second aspect of the embodiment of the present application provides a light-emitting device, comprising a monochromatic light-emitting layer and a hole blocking layer stacked, wherein the monochromatic light-emitting layer is a green light-emitting layer, and the monochromatic light-emitting layer comprises a host material, wherein the host material has a first activation energy Ea x , the hole blocking layer has a second activation energy Ea y , the first activation energy Ea x and the second activation energy Ea y The following relationship (1) is satisfied:

[0025] 0.1eV≤|Ea x -Ea y |≤0.2eV Formula (1).

[0026] In a possible implementation of the second aspect of the embodiments of the present application, the monochromatic light-emitting layer further has a guest material doped in the host material.

[0027] In a possible implementation of the second aspect of the embodiments of the present application, the light-emitting device further includes an electron transport layer stacked on the electron injection side of the hole blocking layer, and the activation energy of the host material is greater than the activation energy of the electron transport layer;

[0028] Moreover, the activation energy of the hole blocking layer is greater than the activation energy of the main material and the electron transport layer.

[0029] A third aspect of an embodiment of the present application provides a display panel, comprising the light-emitting device according to the second aspect of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Other features, objects and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings, in which like or similar reference numerals designate like or similar features and which are not drawn to scale.

[0031] Figure 1 This is a flow chart of the material screening method in the first aspect of the embodiment of the present application;

[0032] Figure 2 This is another flow chart of the material screening method in the first aspect of the embodiment of the present application;

[0033] Figure 3 This is another flow chart of the material screening method in the first aspect of the embodiment of the present application;

[0034] Figure 4 This is another flow chart of the material screening method in the first aspect of the embodiment of the present application;

[0035] Figure 5 This is a diagram showing the Ea energy level relationship of some functional layers of the light-emitting device in the second aspect of the embodiment of the present application.

[0036] In the picture:

[0037] A: electron injection direction in the light-emitting device;

[0038] B: hole injection direction in the light-emitting device;

[0039] GH-green host material; HB-hole blocking layer; ET-electron transport layer. DETAILED DESCRIPTION

[0040] The features and exemplary embodiments of various aspects of the present invention will be described in detail below. In order to make the objects, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only configured to explain the present invention and are not configured to limit the present invention. For those skilled in the art, the present invention can be implemented without the need for some of these specific details. The following description of the embodiments is merely to provide a better understanding of the present invention by illustrating examples of the present invention.

[0041] It should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article, or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or elements inherent to such process, method, article, or device. In the absence of further limitations, the elements defined by the phrase "comprising..." do not exclude the presence of other identical elements in the process, method, article, or device comprising the elements.

[0042] It should be understood that when describing the structure of a component, when a layer or a region is referred to as being "on" or "over" another layer or region, it may mean that it is directly on the other layer or region, or that other layers or regions are included between it and the other layer or region. Furthermore, if the component is turned over, the layer or region will be "below" or "beneath" the other layer or region.

[0043] During their research, the inventors discovered that when an OLED display panel displays a white screen, or emits white light, the green light-emitting device has the highest luminance among the three primary light-emitting devices: red, green, and blue. Therefore, to improve the quality and lifespan of the white light emitted by an OLED display panel, it is necessary to focus on increasing the lifespan of the green light-emitting device.

[0044] Furthermore, the inventors have discovered that improving the luminous life of green light-emitting devices can effectively improve the life of green light-emitting devices by reducing the electron injection and transport of green light-emitting devices to a certain extent. In addition to the light-emitting layer, each individual light-emitting device in the OLED display panel also has multiple carrier layers stacked on top of each other, such as a hole blocking layer and an electron transport layer arranged on the electron injection side of the light-emitting layer. In general, in order to improve the production efficiency of the display panel, the hole blocking layer and the electron transport layer are both produced by a whole-layer evaporation method. Therefore, the materials of the hole blocking layer and the electron transport layer and the parameters during the evaporation production must simultaneously consider the requirements of electron injection and transport of red, green and blue light-emitting devices. Therefore, in order to maintain good luminous display quality of blue and red light-emitting devices when the display panel is performing a white screen display, improving the life of the green light-emitting device requires focusing on the improvement of the light-emitting layer of the green light-emitting device itself. Based on the understanding and discovery of the above problems, the inventors propose a method for material screening in the first aspect of the embodiment of the present application for screening the material of the light-emitting layer in the green light-emitting device to screen out light-emitting materials that can improve the life of the green light-emitting device.

[0045] The material screening method proposed in the first aspect of the embodiments of the present application is used to screen the light-emitting layer materials of a light-emitting device. In some embodiments, the material screening method is used to screen the light-emitting layer materials of a green light-emitting device.

[0046] In some optional embodiments, see Figure 1 The material screening method is used to screen the main material of the light-emitting layer of the light-emitting device, and the material screening method includes:

[0047] Step S10: providing a plurality of materials to be screened.

[0048] In step S20, a plurality of first single-electron devices are prepared using each of the materials to be screened as the light-emitting layer material. Each first single-electron device includes a monochromatic light-emitting layer and a first hole blocking layer. The first hole blocking layers of the plurality of first single-electron devices are the same, and the materials of the monochromatic light-emitting layers are different.

[0049] Step S30 , providing a second single-electron device, the second single-electron device comprising a second hole blocking layer, the first hole blocking layer being the same as the second hole blocking layer.

[0050] Step S40, obtaining the first activation energy Ea of each first single-electron device i and the second activation energy Ea of the second single-electron device c .

[0051] Step S50: according to the first activation energy Ea corresponding to each first single electron device i and the second activation energy Ea of the second single-electron device c A plurality of first target light-emitting layer materials are screened and obtained to be used as the main light-emitting layer materials of the light-emitting device.

[0052] It should be noted that in the embodiment of the present application, the first hole blocking layer and the second hole blocking layer are the same, which can be understood as: the physical and chemical parameters of the first hole blocking layer and the second hole blocking layer are the same, and under the same test conditions, the activation energy of the first hole blocking layer is the same as the activation energy of the second hole blocking layer.

[0053] It should be noted that in the embodiments of the present application, the single-electron device only allows electrons to pass through. In some embodiments, the first single-electron device comprises a stacked cathode, a first hole-blocking layer, a monochromatic light-emitting layer, and an anode, wherein the monochromatic light-emitting layer is connected to the anode, and the first hole-blocking layer is connected to the cathode. In some embodiments, the first single-electron device further comprises at least one of an electron transport layer and an electron injection layer.

[0054] In some embodiments, the second single-electron device comprises a cathode, a second hole blocking layer, and an anode arranged in a stacked manner. In some embodiments, the second single-electron device further comprises at least one of an electron transport layer and an electron injection layer.

[0055] In some optional embodiments, see Figure 2 , step S40 also includes:

[0056] Step S41, using each first activation energy Ea i and the second activation energy Ea c The activation energy difference ΔEa between the first hole blocking layer and the monochromatic light-emitting layer in each first single-electron device is calculated. i , i≥1, i is an integer.

[0057] Step S42 : screening and obtaining a plurality of first target light-emitting layer materials using the first standard activation energy difference ΔEaa.

[0058] In some optional embodiments, the monochromatic light-emitting layer is a green light-emitting layer, and the absolute value of the first standard activation energy difference ΔEaa ranges from 0.1 eV to 0.2 eV.

[0059] In some optional embodiments, the material screened in the material screening method of the first aspect is a main material of the light-emitting device.

[0060] In other optional embodiments, such as Figure 3 As shown, the steps of obtaining the first standard activation energy difference ΔEaa include:

[0061] S01, manufacturing a plurality of test monochromatic light-emitting devices, each test monochromatic light-emitting device comprising a third hole blocking layer identical to the first hole blocking layer and a test monochromatic light-emitting layer, wherein the main material of the light-emitting layer of each test monochromatic light-emitting device is different from each other;

[0062] S02, obtaining test parameters of each tested single-color light-emitting device, and screening a plurality of second target light-emitting layer host materials using the first standard test parameters;

[0063] S03, obtaining a test activation energy difference ΔEa between the third hole blocking layer and the main material of the test single-color light-emitting layer in the test single-color light-emitting device corresponding to each second target light-emitting layer main material. k , and according to the test activation energy difference ΔEa k Obtain the first standard activation energy difference ΔEaa.

[0064] In some optional embodiments, the first standard test parameter in step S02 is a lifetime parameter of a light-emitting device. In these embodiments, a plurality of second target light-emitting layer host materials are obtained based on the lifetime parameter of the light-emitting device as the first standard test parameter. In some examples, the lifetime parameter of the light-emitting device is determined based on the average lifetime requirement of the green light-emitting device in the display panel, or may be determined based on other parameters related to the lifetime of the green light-emitting device in the display panel.

[0065] In the embodiments of the present application, activation energy refers to the potential barrier that electrons or holes need to overcome when transferring between different functional layers of the light-emitting device. In the embodiments of the present application, the activation energy of a single layer or multiple functional layers can be understood as the potential barrier that electrons (or holes) need to overcome when flowing from the cathode side (or anode side) through the single layer or multiple functional layers, wherein the functional layer refers to the carrier layer and the light-emitting layer in the light-emitting device. The carrier layer in the light-emitting device includes an electron transport layer, a hole blocking layer, a compensation layer, a hole transport layer, and a hole injection layer, etc. Alternatively, the activation energy in the embodiments of the present application can also be understood as the energy required for electrons to flow from the cathode side through the functional layer carrying electrons, and the energy required for holes to flow from the anode side through the functional layer carrying holes.

[0066] When the functional layer is composed of a single material, the activation energy Ea of that material is the activation energy Ea corresponding to the functional layer. When the functional layer is composed of two or more materials, the activation energy of the functional layer can be calculated by first obtaining the product of the activation energy of each material and the corresponding molar mass fraction of each material; then summing these products to obtain the overall activation energy of the functional layer.

[0067] The activation energy can be calculated using the Arrhenius formula: Ea = E0 + mRT, where Ea is the activation energy, E0 and m are temperature-independent constants, T is the temperature, and R is the molar gas constant. This formula shows that the activation energy is temperature-dependent. Furthermore, the activation energy obtained using the above formula is expressed in joules (J). This can be converted to electron volts (eV) using a simple conversion formula: 1eV = 1.602176565*10 -19 J. It will be understood that a basic formula for calculating Ea is given in the embodiments of the present application, and those skilled in the art can calculate Ea based on the basic Arrhenius formula given in the embodiments of the present application or by various variations of the Arrhenius formula.

[0068] In other embodiments, the activation energy of the functional layer can be obtained using thermogravimetric analysis. For example, thermogravimetric analysis can be performed on the entire first hole blocking layer, the second hole blocking layer, or the monochromatic light-emitting layer, and the activation energy of each functional layer can be directly calculated based on the thermogravimetric analysis results. Thermogravimetric analysis is a method for determining the relationship between the mass of a substance and temperature (or time) under a program-controlled temperature. After obtaining a thermogravimetric curve using thermogravimetric analysis, the average activation energy can be calculated using the Freeman-Carroll method or the OWAZa method.

[0069] In the prior art, the highest occupied energy orbital (HOMO) and the lowest occupied energy orbital (LUMO) are generally used to measure the energy level matching of each functional layer in a light-emitting device. However, the HOMO and LUMO only consider the carrier injection efficiency. In the embodiments of the present application, the light-emitting layer host material is screened based on the activation energy of the light-emitting layer host material and the hole blocking layer. This allows for comprehensive consideration of the impact of multiple factors, such as carrier injection and carrier transport between the functional layers, and temperature, on the light-emitting layer host material and the luminescent lifetime of the light-emitting device ultimately fabricated using the light-emitting layer host material. When screening light-emitting layer host materials, a comprehensive evaluation of the light-emitting layer host material based solely on the activation energy Ea can be achieved, effectively selecting light-emitting layer host materials that can improve the luminescence lifetime of green light-emitting devices. This allows the display panel to display normal white light while displaying a white screen, improving the display quality and performance of the display panel. Selecting light-emitting layer host materials according to the embodiments of the present application can effectively improve the luminescence lifetime of green light-emitting devices, avoiding the problem of color shift in the display panel after long-term use due to the short life of green light-emitting devices, and overall improving the luminescence lifetime of the display panel.

[0070] Furthermore, the inventors discovered through long-term research that the screening of the main materials for the light-emitting layer in light-emitting devices, especially the main materials for the light-emitting layer in green light-emitting devices, only needs to consider the matching relationship between the activation energy of the hole-blocking layer and the main materials for the light-emitting layer. Although the light-emitting devices of display panels generally include multiple functional layers for carrying holes or electrons, it is only necessary to consider the matching relationship between the activation energy of the hole-blocking layer in the light-emitting device and the activation energy of the main materials for the light-emitting layer to screen out the main materials for the light-emitting layer that increase the luminous life of the light-emitting device. Therefore, the screening efficiency of the main materials for the light-emitting layer is greatly improved, the types and number of single-electron devices produced are reduced, the cost of the material screening process is reduced, and the production cost of display panels is further reduced.

[0071] In some optional embodiments, see Figure 4 , step S30 also includes step S31 and step S32.

[0072] In step S31, the first single-electron device is subjected to a power-on test to obtain an IV curve of the first single-electron device, that is, a current-voltage curve of the first single-electron device. According to the current-voltage curve of the first single-electron device during the test, the first activation energy Ea of the first single-electron device can be calculated using the Arrhenius formula. i .

[0073] The first single-electron device includes a monochromatic light-emitting layer and a first hole blocking layer. The first single-electron device is a test device. When the first single-electron device is powered on for testing, the first single-electron device does not emit light. Therefore, in these embodiments, the first activation energy Ea i is the activation energy of the monochromatic light-emitting layer and the first hole blocking layer in the first monolithic device. It can be understood that the first activation energy Ea i It is the energy required for electrons to flow from the cathode side through the first hole blocking layer and the monochromatic light-emitting layer in sequence in the single-electron device.

[0074] In step S32, the second single-electron device is subjected to a power-on test to obtain an IV curve of the second single-electron device, that is, a current-voltage curve of the second single-electron device. According to the current-voltage curve of the second single-electron device during the test, the second activation energy Ea of the second single-electron device can be calculated using the Arrhenius formula. c The second single-electron device includes a second hole blocking layer, and the second single-electron device is a test device. When the second single-electron device is powered on for testing, the second single-electron device does not emit light. Therefore, in these embodiments, the second activation energy Ea c is the activation energy of the second hole blocking layer in the second monolithic device. It can be understood that the second activation energy Ea c It is the energy required for electrons to flow from the cathode side through the second hole blocking layer carrying electrons in the second monolithic device.

[0075] In step S41, according to the formula ΔEa i =Ea i -Ea c , that is, the first activation energy Ea can be used i and the second activation energy Ea c The activation energy difference ΔEa between the first hole blocking layer and the monochromatic light-emitting layer in each first single-electron device is calculated. i , i≥1, i is an integer.

[0076] It is understandable that ΔEa i If it is greater than zero, then in the electron flow direction of the first single-electron device (electrons flow from the cathode side through the first hole blocking layer and the monochromatic light-emitting layer carrying electrons in sequence), the activation energy of the monochromatic light-emitting layer is greater than the activation energy of the first hole blocking layer.

[0077] ΔEa i If it is less than zero, then in the electron flow direction of the first single-electron device (electrons flow from the cathode side through the first hole blocking layer and the monochromatic light-emitting layer carrying electrons in sequence), the activation energy of the monochromatic light-emitting layer is less than the activation energy of the first hole blocking layer.

[0078] In order to demonstrate the effect of the material screening method of the first aspect of the present application on improving the life of light-emitting devices, especially green light-emitting devices, the following comparative example 1 and experimental example 1 were designed.

[0079] In Comparative Example 1, a first host material was selected to form a monochromatic light-emitting layer of a first monochromatic light-emitting device, wherein the first monochromatic light-emitting device emits green light. The first monochromatic light-emitting device also includes a hole-blocking layer stacked on the monochromatic light-emitting layer. The absolute value of the activation energy difference ΔEa between the first host material and the hole-blocking layer in the first monochromatic light-emitting device is 0.06 eV.

[0080] In Experimental Example 1, a second host material is selected to fabricate a monochromatic light-emitting layer of a second monochromatic light-emitting device, wherein the second monochromatic light-emitting device also emits green light. The second monochromatic light-emitting device further includes a hole blocking layer stacked on the monochromatic light-emitting layer. The absolute value of the activation energy difference ΔEa between the second host material and the hole blocking layer of the second monochromatic light-emitting device in the second monochromatic light-emitting device is 0.13 eV. That is, the activation energy difference ΔEa between the second host material and the hole blocking layer in the second monochromatic light-emitting device falls within the absolute value range of the first standard activation energy difference ΔEaa of 0.1 eV to 0.2 eV. The second host material in Experimental Example 1 is the target light-emitting layer material screened by the material screening method provided in the first aspect of the embodiment of the present application.

[0081] Among them, the hole blocking layer of the first monochromatic light-emitting device in Comparative Example 1 is the same as the hole blocking layer of the second monochromatic light-emitting device in Experimental Example 1, and the first monochromatic light-emitting device and the second monochromatic light-emitting device are subjected to the same experimental conditions during the life test, and the life test is performed only with the main material of the monochromatic light-emitting layer in the monochromatic light-emitting device as a variable.

[0082] The life test results of the first monochromatic light-emitting device corresponding to Comparative Example 1 and the second monochromatic light-emitting device corresponding to Experimental Example 1 are shown in Table 1 below.

[0083] Table 1

[0084] <![CDATA[ΔEa=Ea (GH) -Yes (HB) ]]> CIEx CIE CE (current efficiency) LT97@24000nits Comparative Example 1 0.06eV 0.255 0.715 100％ 100％ Experimental Example 1 0.13eV 0.251 0.717 100％ 140％

[0085] In Table 1, GH represents a green host material. It should be further clarified that GH refers to the green host material of the monochromatic light-emitting layer in a monochromatic light-emitting device, which includes a green host material and a green guest material. Comparative Example 1 and Experimental Example 1 used the activation energy difference between the green host material and the hole-blocking layer in the light-emitting layer as a variable for experimental comparison. HB represents the hole-blocking layer, CIEx and CIEy represent color coordinates, CE represents current efficiency, and LT97@24000nits represents the time it takes for the brightness of the light-emitting device to decay from 100% of the initial brightness to 97% of the initial brightness at an initial brightness of 24000nits. This can also be understood as the luminescence lifetime. In Table 1, the lifetime T0 of Comparative Example 1 at LT97@24000nits is used as the benchmark and is therefore represented as 100%. The lifetime T1 of Experimental Example 1 at LT97@24000nits is 1.4 times T0, so T1 is represented as 140%.

[0086] Table 1 shows that the color coordinates CIEx and CIEy of the light emitted by the first monochromatic light-emitting device and the second monochromatic light-emitting device are substantially the same, and the current efficiencies of the two monochromatic light-emitting devices are also the same. Furthermore, the luminescence lifetime of the second monochromatic light-emitting device in Experimental Example 1 is 40% longer than that of the first monochromatic light-emitting device in Comparative Example 1. The performance test results of the monochromatic light-emitting devices show that the light-emitting layer materials selected by the material screening method provided in the first aspect of the embodiments of the present application can significantly increase the luminescence lifetime of green light-emitting devices.

[0087] The second aspect of the embodiment of the present application provides a light-emitting device, which includes a monochromatic light-emitting layer and a hole blocking layer stacked with the monochromatic light-emitting layer, wherein the monochromatic light-emitting layer is a green light-emitting layer, and the monochromatic light-emitting layer includes a host material, and the host material has a first activation energy Ea x , the hole blocking layer has a second activation energy Ea y , the first activation energy Ea x and the second activation energy Ea y The following relationship (1) is satisfied:

[0088] 0.1eV≤|Ea x -Ea y |≤0.2eV Formula (1).

[0089] In some optional embodiments, the monochromatic light-emitting layer further comprises a guest material doped in the host material;

[0090] In some optional embodiments, see Figure 5The light-emitting device further includes an electron transport layer stacked on the electron injection side of the hole blocking layer, wherein the activation energy of the host material is greater than the activation energy of the electron transport layer; and the activation energy of the hole blocking layer is greater than the activation energy of both the host material and the electron transport layer. In these embodiments, the activation energy of the hole blocking layer is greater than the activation energy of the host material, which can more effectively regulate the amount of electrons injected into the host material, thereby further effectively improving the life of the green light-emitting device. That is, in these embodiments, the first activation energy Ea x and the second activation energy Ea y Satisfying -0.2eV≤Ea x -Ea y ≤-0.1eV.

[0091] In some optional embodiments, in the light-emitting device of the second aspect of the embodiment of the present application, a hole injection layer, a hole transport layer and an electron blocking layer are stacked on the hole injection side of the monochromatic light-emitting layer and in the hole injection direction.

[0092] A third aspect of the embodiments of the present application provides a display panel comprising the green light-emitting device provided in the second aspect of the present application. The light-emitting device layer of the display panel further includes a red light-emitting device and a blue light-emitting device. The hole-blocking layers of the blue, red, and green light-emitting devices can be formed from the same material. The display panel of the third aspect of the embodiments of the present application exhibits excellent white screen display quality and high color rendering accuracy, avoiding undesirable display issues such as color shift or low brightness caused by the short lifetime of the green light-emitting device.

[0093] While the embodiments of the present invention are described above, these embodiments do not exhaustively describe all details and do not limit the invention to the specific embodiments described. Obviously, many modifications and variations are possible based on the above description. These embodiments are selected and described in detail in this specification in order to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better utilize the invention and its modifications. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A material screening method for screening a light-emitting layer main material of a light-emitting device, characterized in that: The screening method comprises: Provide multiple materials to be screened; Using each of the materials to be screened as a light-emitting layer material, a plurality of first single-electron devices are manufactured, each of the first single-electron devices comprising a monochromatic light-emitting layer and a first hole-blocking layer, wherein the first hole-blocking layer is the same and the material of the monochromatic light-emitting layer is different among the plurality of first single-electron devices; providing a second single-electron device, the second single-electron device including a second hole blocking layer, the first hole blocking layer being the same as the second hole blocking layer, and the second single-electron device not including the monochromatic light-emitting layer; Obtain the first activation energy Ea of each of the first single-electron devices i and the second activation energy Ea of the second single-electron device c ; According to the first activation energy Ea corresponding to each of the first single-electron devices i and the second activation energy Ea of the second single-electron device c A plurality of first target light-emitting layer materials are screened and obtained to be used as the main light-emitting layer materials of the light-emitting device.

2. The material screening method according to claim 1, characterized in that: The first activation energy Ea corresponding to each of the first single-electron devices i and the second activation energy Ea of the second single-electron device c The step of screening and obtaining a plurality of first target light-emitting layer materials for use as the main material of the light-emitting layer of the light-emitting device comprises: Using the first activation energy Ea i and the second activation energy Ea c The activation energy difference ΔEa between the first hole blocking layer and the monochromatic light emitting layer in each of the first single electron devices is calculated. i ; A plurality of the first target light-emitting layer materials are screened using the first standard activation energy difference ΔEaa.

3. The material screening method according to claim 2, characterized in that: The monochromatic light-emitting layer is a green light-emitting layer, and the absolute value of the first standard activation energy difference ΔEaa ranges from 0.1 eV to 0.2 eV.

4. The material screening method according to claim 2, characterized in that: The step of obtaining the first standard activation energy difference ΔEaa comprises: Producing a plurality of test monochromatic light-emitting devices, each of which includes a third hole blocking layer identical to the first hole blocking layer and a test monochromatic light-emitting layer, wherein the main material of the light-emitting layer of each test monochromatic light-emitting device is different from another; Acquiring test parameters of each of the tested monochromatic light-emitting devices, and screening to obtain a plurality of second target light-emitting layer host materials using the first standard test parameters; Obtain the test activation energy difference ΔEa between the third hole blocking layer and the main material of the test monochromatic light-emitting layer in the test monochromatic light-emitting device corresponding to each second target light-emitting layer main material k , and according to the test activation energy difference ΔEa k Obtain the first standard activation energy difference ΔEaa.

5. The material screening method according to claim 4, characterized in that: In the step of obtaining the test parameters of each of the tested monochromatic light-emitting devices and screening a plurality of second target light-emitting layer materials using the first standard test parameters, The first standard test parameter is a lifespan parameter of the light emitting device.

6. The material screening method according to claim 1, characterized in that: The screening method is used to screen the main material of the light-emitting layer of a green light-emitting device.

7. A light emitting device, characterized in that: The invention comprises a monochromatic light-emitting layer and a hole blocking layer stacked, wherein the monochromatic light-emitting layer is a green light-emitting layer, and the monochromatic light-emitting layer comprises a main material, and the main material has a first activation energy Ea x , the hole blocking layer has a second activation energy Ea y The host material is the first target light-emitting layer material selected by the material screening method according to any one of claims 1 to 6, and the first activation energy Ea x With the second activation energy Ea y The following relationship (1) is satisfied: 0.1 eV 0.2 eV, Equation (1).

8. The light emitting device according to claim 7, characterized in that The monochromatic light-emitting layer further has a guest material doped in the host material.

9. The light emitting device according to claim 7, characterized in that The light-emitting device further comprises an electron transport layer stacked on the electron injection side of the hole blocking layer, and the activation energy of the host material is greater than the activation energy of the electron transport layer; Furthermore, the activation energy of the hole blocking layer is greater than the activation energy of the main material and the electron transport layer.

10. A display panel, characterized in that: A light-emitting device comprising the light-emitting device according to any one of claims 7 to 9.

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