Light-emitting device, display panel and display device

Abstract

The embodiment of the invention provides a light-emitting device, a display panel and a display device.The light-emitting device comprises a first carrier layer, a light-emitting layer and a second carrier layer which are sequentially arranged in a stacked mode, the first carrier layer is used for transmitting holes, the second carrier layer is used for transmitting electrons, and the light-emitting layer is used for emitting light. The light-emitting layer comprises a first light-emitting sub-layer and a second light-emitting sub-layer which are stacked in the direction from the first carrier layer to the second carrier layer, the excited state energy level of the first light-emitting sub-layer is larger than the excited state energy level of the second light-emitting sub-layer, and the HOMO energy level of the first light-emitting sub-layer is larger than the HOMO energy level of the second light-emitting sub-layer. According to the light-emitting device, holes and electrons are easily compounded in the first light-emitting sub-layer to generate triplet excitons, and the excitons are easily transferred to the second light-emitting sub-layer and are evolved from the triplet state to the singlet state, so that charge recombination and exciton change can be mutually isolated, the conversion efficiency can be improved, and the light-emitting efficiency of the light-emitting device is further improved.

Description

Technical Field

[0001] The present application relates to the technical field of display devices, and in particular to a light-emitting device, a display panel, and a display apparatus. Background Art

[0002] Organic Light Emitting Display (OLED) and flat-panel display devices based on technologies such as Light Emitting Diode (LED) have been widely used in various consumer electronic products such as mobile phones, televisions, laptops, and desktop computers due to their advantages such as high image quality, power saving, thin body, and wide range of applications, becoming the mainstream display device.

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

[0004] The embodiments of the present application provide a light-emitting device, a display panel, and a display apparatus, aiming to improve the performance of display products.

[0005] An embodiment of the first aspect of the present application provides a light-emitting device, which includes a first carrier layer, a light-emitting layer, and a second carrier layer stacked in sequence, wherein the first carrier layer is used to transport holes, and the second carrier layer is used to transport electrons, and the light-emitting layer includes a first sub-light-emitting layer and a second sub-light-emitting layer stacked in the direction from the first carrier layer to the second carrier layer, wherein the excited state energy level of the first sub-light-emitting layer is greater than the excited state energy level of the second sub-light-emitting layer, and the HOMO energy level of the first sub-light-emitting layer is greater than the HOMO energy level of the second sub-light-emitting layer.

[0006] An embodiment of the first aspect of the present application also provides a light-emitting device, which includes a first carrier layer, a light-emitting layer, and a second carrier layer stacked in sequence, wherein the first carrier layer is used to transport holes, and the second carrier layer is used to transport electrons, and the light-emitting layer includes a first sub-light-emitting layer and a second sub-light-emitting layer stacked in the direction from the first carrier layer to the second carrier layer, wherein the excited state energy level of the first sub-light-emitting layer is greater than the excited state energy level of the second sub-light-emitting layer, and the LUMO energy level of the first sub-light-emitting layer is lower than the LUMO energy level of the second sub-light-emitting layer.

[0007] An embodiment of the second aspect of the present application also provides a light-emitting device, which includes a first carrier layer, a light-emitting layer, and a second carrier layer stacked in sequence, wherein the first carrier layer is used to transport holes, and the second carrier layer is used to transport electrons, and the light-emitting layer includes a first sub-light-emitting layer and a second sub-light-emitting layer stacked in the direction from the first carrier layer to the second carrier layer, wherein the excited state energy level of the first sub-light-emitting layer is lower than the excited state energy level of the second sub-light-emitting layer, and the HOMO energy level of the first sub-light-emitting layer is lower than the HOMO energy level of the second sub-light-emitting layer.

[0008] An embodiment of the second aspect of the present application also provides a light-emitting device, which includes a first carrier layer, a light-emitting layer, and a second carrier layer stacked in sequence, wherein the first carrier layer is used to transport holes, and the second carrier layer is used to transport electrons, and the light-emitting layer includes a first sub-light-emitting layer and a second sub-light-emitting layer stacked in the direction from the first carrier layer to the second carrier layer, wherein the excited state energy level of the first sub-light-emitting layer is lower than the excited state energy level of the second sub-light-emitting layer, and the LUMO energy level of the first sub-light-emitting layer is greater than the LUMO energy level of the second sub-light-emitting layer.

[0009] An embodiment of the third aspect of the present application further provides a display panel, comprising a light-emitting device according to any one of the above-mentioned embodiments of the first aspect.

[0010] An embodiment of the fourth aspect of the present application further provides a display device, comprising a display panel according to any one of the above-mentioned embodiments of the second aspect.

[0011] In the light-emitting device provided in the embodiment of the present application, the light-emitting device includes a first carrier layer, a second carrier layer, and a first sub-light-emitting layer and a second sub-light-emitting layer located between the first carrier layer and the second carrier layer. The first sub-light-emitting layer and the second sub-light-emitting layer are both used for emitting light, the first carrier layer is used for transporting holes, and the second carrier layer is used for transporting electrons. In the first sub-light-emitting layer and the second sub-light-emitting layer, the HOMO energy level of the first sub-light-emitting layer is greater than the HOMO energy level of the second sub-light-emitting layer, making it difficult for holes to be transported from the first sub-light-emitting layer to the second sub-light-emitting layer, and more holes can be retained in the first sub-light-emitting layer. Holes and electrons are easily recombined in the first sub-light-emitting layer to produce triplet excitons. The excited state energy level of the first sub-light-emitting layer is greater than the excited state energy level of the second sub-light-emitting layer, and the excitons are easily transferred to the second sub-light-emitting layer and evolve from triplet to singlet. Therefore, charge recombination and exciton changes can be isolated from each other, which can improve the conversion efficiency and thus improve the luminous efficiency of the light-emitting device. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Other features, objects and advantages of the present application will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings, in which the same or similar reference numerals represent the same or similar features.

[0013] Figure 1 is a schematic structural diagram of a light-emitting device in an embodiment;

[0014] Figure 2 is a schematic diagram of the connection structure of a light emitting device in an embodiment;

[0015] Figure 3 This is a schematic structural diagram of a light-emitting device provided in an embodiment of the present application;

[0016] Figure 4 This is a schematic diagram of the energy level structure of a light-emitting device provided in an embodiment of the first aspect of the present application;

[0017] Figure 5 This is a schematic diagram of the energy level structure of a light-emitting device provided by another embodiment of the first aspect of the present application;

[0018] Figure 6 This is a schematic diagram of the energy level structure of a light-emitting device provided in yet another embodiment of the first aspect of the present application;

[0019] Figure 7 This is a schematic diagram of the energy level structure of a light-emitting device provided in an embodiment of the second aspect of the present application;

[0020] Figure 8 This is a schematic diagram of the energy level structure of a light-emitting device provided in another embodiment of the second aspect of the present application;

[0021] Figure 9 This is a schematic diagram of the energy level structure of a light-emitting device provided in yet another embodiment of the second aspect of the present application.

[0022] Description of reference numerals:

[0023] 10. a first electrode;

[0024] 20. First carrier layer; 21. Hole injection layer; 22. Hole transport layer; 23. Electron blocking layer;

[0025] 30. Light-emitting layer; 31. First sub-light-emitting layer; 32. Second sub-light-emitting layer;

[0026] 40. Second carrier layer; 41. Hole blocking layer; 42. Electron transport layer; 43. Electron injection layer;

[0027] 50. Second electrode. DETAILED DESCRIPTION

[0028] The features and exemplary embodiments of various aspects of the present application will be described in detail below. In the detailed description below, many specific details are set forth in order to provide a comprehensive understanding of the present application. However, it will be apparent to those skilled in the art that the present application can be implemented without some of these specific details. The following description of the embodiments is merely intended to provide a better understanding of the present application by illustrating examples of the present application. In the accompanying drawings and the following description, at least some of the well-known structures and technologies are not shown in order to avoid unnecessary ambiguity in the present application; and, for clarity, the sizes of some structures may be exaggerated. In addition, the features, structures, or characteristics described below may be combined in any suitable manner in one or more embodiments.

[0029] In the description of this application, it should be noted that, unless otherwise specified, "plurality" means more than two; terms such as "upper," "lower," "left," "right," "inner," and "outer" indicating directions or positional relationships are merely for the purpose of facilitating the description of this application and simplifying the description. They do not indicate or imply that the devices or components referred to must have a specific orientation, be constructed, or operate in a specific orientation, and therefore should not be construed as limiting this application. Furthermore, terms such as "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0030] The directional words appearing in the following description are all directions shown in the figures, and do not limit the specific structure of the embodiments of this application. In the description of this application, it should also be noted that, unless otherwise clearly specified and limited, the terms "installation" and "connection" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected or indirectly connected. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to the specific circumstances.

[0031] like Figure 1 As shown in FIG, a schematic diagram of the structure of a light-emitting device provided by the related art. In the light-emitting device, the light-emitting device includes an anode 10', a hole transport layer 22', an electron blocking layer 23', a light-emitting layer 30', a hole blocking layer 41', an electron transport layer 42' and a cathode 20' which are stacked in sequence. The anode 10' is used to generate holes, and the cathode 20' is used to generate electrons. Figure 2As shown, holes and electrons recombine within the light-emitting layer 30 to form excitons, including triplet excitons T1. Triplet-to-triplet annihilation (TTA) occurs, converting triplet excitons T1 into singlet excitons, thereby improving efficiency. However, some of the triplet excitons T1 lose their energy due to charge quenching within the light-emitting layer 30', affecting efficiency. Furthermore, a high concentration of triplet excitons in the light-emitting layer 30' can affect the stability of nearby materials, such as the interface between the electron blocking layer 23' and the light-emitting layer 30', leading to degradation of the electron blocking layer 23'.

[0032] In order to solve the above technical problems, this application is proposed. In order to better understand this application, Figure 3 and Figure 4 The light-emitting device, display panel and display apparatus provided in the embodiments of the present application are described in detail.

[0033] Please also refer to Figure 3 and Figure 4 , Figure 3 This is a schematic structural diagram of a light-emitting device provided in an embodiment of the present application; Figure 4 This is a schematic diagram of the energy level structure of a light-emitting device provided in an embodiment of the present application.

[0034] like Figure 3 and Figure 4 As shown, an embodiment of the first aspect of the present application provides a light-emitting device, which includes a first carrier layer 20, a light-emitting layer 30, and a second carrier layer 40 stacked in sequence, wherein the first carrier layer 20 is used to transport holes, and the second carrier layer 40 is used to transport electrons, and the light-emitting layer 30 includes a first sub-light-emitting layer 31 and a second sub-light-emitting layer 32 stacked in the direction from the first carrier layer 20 to the second carrier layer 40, wherein the excited state energy level of the first sub-light-emitting layer 31 is greater than the excited state energy level of the second sub-light-emitting layer 32, and the HOMO energy level of the first sub-light-emitting layer 31 is greater than the HOMO energy level of the second sub-light-emitting layer 32.

[0035] In the light-emitting device provided in the embodiment of the present application, the light-emitting device includes a first carrier layer 20, a second carrier layer 40, and a first sub-light-emitting layer 31 and a second sub-light-emitting layer 32 located between the first carrier layer 20 and the second carrier layer 40. The first sub-light-emitting layer 31 and the second sub-light-emitting layer 32 are both used for emitting light, the first carrier layer 20 is used for transporting holes, and the second carrier layer 40 is used for transporting electrons. In the first sub-light-emitting layer 31 and the second sub-light-emitting layer 32, the HOMO energy level of the first sub-light-emitting layer 31 is greater than the HOMO energy level of the second sub-light-emitting layer 32, making it difficult for holes to be transferred from the first sub-light-emitting layer 31 to the second sub-light-emitting layer 32, and more holes can be retained in the first sub-light-emitting layer 31. Therefore, holes and electrons are easily recombined in the first sub-light-emitting layer 31 to produce triplet excitons T1. The excited state energy level of the first sub-light-emitting layer 31 is greater than the excited state energy level of the second sub-light-emitting layer 32. The triplet exciton T1 is easily transferred to the second sub-light-emitting layer 32 and evolves from triplet to singlet state. Therefore, the charge recombination and the change of the triplet exciton T1 can be isolated from each other, which can improve the conversion efficiency and thus improve the luminous efficiency of the light-emitting device.

[0036] In the embodiments of this application, Figure 4 As shown, electrons and holes recombine in the first sub-light-emitting layer 31, while the evolution (TTA) of the triplet exciton T1 from the triplet state to the singlet state is in the second sub-light-emitting layer 32. The charge and the triplet exciton T1 are in different layer structures, which can increase the distance between the charge and the triplet exciton T1, improve the energy and charge quenching loss of some triplet excitons T1, and thus improve the luminescence efficiency. Figure 4 The dotted box in the figure illustrates the triplet exciton T1 evolution region.

[0037] Optionally, the light-emitting device further includes a first electrode 10 and a second electrode 50. The first electrode 10 is located on a side of the first carrier layer 20 facing away from the light-emitting layer 30, and the second electrode 50 is located on a side of the second carrier layer 40 facing away from the light-emitting layer 30. The first electrode 10 is, for example, an anode, and the second electrode 50 is, for example, a cathode, such that the first electrode 10 can generate holes and the second electrode 50 can generate electrons.

[0038] In some optional embodiments, the mobility of electrons in the light-emitting layer 30 is greater than the mobility of holes in the light-emitting layer 30 .

[0039] In these optional embodiments, since the migration rate of electrons is faster and the migration rate of holes is slower, the path length of electron movement is greater than the path length of hole movement in the same time. Therefore, in the same time period, electrons are more likely to pass through the second sub-light-emitting layer 32 to move to the first sub-light-emitting layer 31, and holes move to the first sub-light-emitting layer 31. Electrons and holes are more likely to meet and recombine in the first sub-light-emitting layer 31 close to the side of the first carrier layer 20.

[0040] Optionally, the material of the first sub-light-emitting layer 31 includes a first host material and a light-emitting material, and the material of the second sub-light-emitting layer 32 includes a second host material and a light-emitting material. Optionally, the mobility of electrons in the first host material is greater than the mobility of holes in the first host material, the mobility of electrons in the second host material and the mobility of holes in the second host material may be equal, or the mobility of electrons in the second host material is greater than the mobility of holes in the second host material.

[0041] In some optional embodiments, the HOMO energy level of the first host material is greater than the HOMO energy level of the second host material.

[0042] In these optional embodiments, the first host material accounts for a larger proportion in the first sub-light-emitting layer 31, and the second host material accounts for a larger proportion in the second sub-light-emitting layer 32. Therefore, the HOMO energy level of the first host material is greater than the HOMO energy level of the second host material, which helps to make the HOMO energy level of the first sub-light-emitting layer 31 greater than the HOMO energy level of the second sub-light-emitting layer 32. Optionally, the HOMO energy level H1 of the first host material and the HOMO energy level H2 of the second host material satisfy: 0.1 eV ≤ H1-H2 ≤ 0.6 eV.

[0043] In these optional embodiments, when the HOMO energy level H1 of the first host material and the HOMO energy level H2 of the second host material meet the above range, it can not only improve the excessive amount of holes transferred to the second sub-light-emitting layer 32 due to the small difference between the HOMO energy level H1 of the first host material and the HOMO energy level H2 of the second host material; it can also improve the overall luminous effect of the light-emitting layer 30 affected by the large difference between the HOMO energy level H1 of the first host material and the HOMO energy level H2 of the second host material.

[0044] In some optional embodiments, in the first light-emitting sub-layer 31 , the mass ratio of the light-emitting material to the first host material is 1% to 4%, so as to ensure good carrier transport and light-emitting effects.

[0045] In some optional embodiments, the excited state energy level of the first host material is greater than the excited state energy level of the second host material.

[0046] In these optional embodiments, the first main material in the first sub-light-emitting layer 31 accounts for a larger proportion, and the second main material in the second sub-light-emitting layer 32 accounts for a larger proportion. Therefore, the excited state energy level of the first main material is greater than the excited state energy level of the second main material, which can make the excited state energy level of the first sub-light-emitting layer 31 greater than the excited state energy level of the second sub-light-emitting layer 32.

[0047] In some optional embodiments, in the second light-emitting sub-layer 32 , the mass ratio of the light-emitting material to the first host material is 1% to 4%, so as to ensure good carrier transport and light-emitting effects.

[0048] Optionally, the luminescent material is used to emit blue light, thereby improving the luminous efficiency of the blue light-emitting device and thereby increasing the service life of the blue light-emitting unit. When the display panel includes red, blue, and green light-emitting devices, the service lives of the light-emitting devices of different colors are similar.

[0049] Optionally, the triplet excited state energy level E of the first host material T1 Greater than the triplet excited state energy level E of the second host material T2 .

[0050] In these optional embodiments, the triplet excitons evolve into singlet excitons, and the luminescent material uses the singlet excitons to emit light of corresponding colors. T1 Greater than the triplet excited state energy level E of the second host material T2 When the triplet excitons are more easily transferred from the first sub-light-emitting layer 31 to the second sub-light-emitting layer 32 , the triplet excitons are more easily evolved into singlet excitons in the second sub-light-emitting layer 32 .

[0051] Optionally, the triplet excited state energy level E of the first host material T1 and the triplet excited state energy level E of the second host material T2 Satisfies: 0.1eV≤E T1 -E T2 ≤0.6eV.

[0052] In these optional embodiments, the triplet excited state energy level E of the first host material can be improved. T1 and the triplet excited state energy level E of the second host material T2 If the difference between them is too small, triplet excitons are likely to remain in the first sub-light-emitting layer 31, affecting the luminous efficiency. It can also improve the triplet excited state energy level E of the first host material. T1 and the triplet excited state energy level E of the second host material T2 The difference between them is too large, which affects the overall luminous effect of the luminous layer 30.

[0053] In some optional embodiments, the triplet excited state energy level E T Greater than the triplet excited state energy level E of the second host material T2 The first sub-light emitting layer 31 and the second sub-light emitting layer 32 are both provided with light emitting materials. When the triplet excited state energy level E T Greater than the triplet excited state energy level E of the second host material T2When , the excitons are more likely to evolve into singlet excitons in the second light-emitting sub-layer 32 .

[0054] Optionally, the triplet excited state energy level E of the luminescent material T and the triplet excited state energy level E of the second host material T2 Satisfies: 0.1eV≤E T -E T2 ≤0.6eV. To improve the triplet excited state energy level E of the luminescent material T and the triplet excited state energy level E of the second host material T2 If the difference is too small, it will affect the evolution of excitons in the second sub-light-emitting layer 32; it can also improve the triplet excited state energy level E of the light-emitting material. T and the triplet excited state energy level E of the second host material T2 A large difference affects the overall performance of the light-emitting layer 30 .

[0055] In some optional embodiments, the singlet excited state energy level E of the second host material is S2 Greater than the singlet excited state energy level E of the luminescent material S When the exciton evolves to a singlet exciton, the energy can be more easily transferred to the luminescent material to achieve the purpose of luminescence.

[0056] Optionally, the singlet excited state energy level E of the second host material S2 and the singlet excited state energy level E of the luminescent material S Satisfies: 0.1eV≤E S2 -E S ≤0.6eV. To improve the singlet excited state energy level E of the second host material S2 and the singlet excited state energy level E of the luminescent material S A small difference affects the energy transfer to the luminescent material; it can also improve the singlet excited state energy level E of the second host material. S2 and the singlet excited state energy level E of the luminescent material S A large difference affects the overall performance of the light-emitting layer 30 .

[0057] Optional, such as Figure 5 and Figure 6 As shown, the LUMO energy level of the first sub-light emitting layer 31 may be lower than the LUMO energy level of the second sub-light emitting layer 32 .

[0058] In some other optional embodiments, the LUMO energy level of the first sub-light-emitting layer 31 is lower than the LUMO energy level of the second sub-light-emitting layer 32. This makes it easier for electrons to transfer from the second sub-light-emitting layer 32 to the first sub-light-emitting layer 31, so that more electrons can be transferred to the first sub-light-emitting layer 31 to recombine with holes in the first sub-light-emitting layer 31 to form excitons.

[0059] Optionally, referring to the above, the material of the first sub-light-emitting layer 31 includes a first host material and a light-emitting material, the material of the second sub-light-emitting layer 32 includes a second host material and a light-emitting material, and the LUMO energy level of the first host material is lower than the LUMO energy level of the second host material.

[0060] In these optional embodiments, the weight proportion of the first main material in the first sub-light-emitting layer 31 is relatively high, and the weight proportion of the second main material in the second sub-light-emitting layer 32 is relatively high, so that the LUMO energy level of the first main material is lower than the LUMO energy level of the second main material, which is beneficial to making the LUMO energy level of the first sub-light-emitting layer 31 lower than the LUMO energy level of the second sub-light-emitting layer 32.

[0061] Optionally, the LUMO energy level L1 of the first host material and the LUMO energy level L2 of the second host material satisfy the following conditions: 0.1 eV ≤ L2 - L1 ≤ 0.6 eV. This can improve the overall performance of the light-emitting layer 30 due to an excessively large difference between the LUMO energy levels L1 and L2 of the first host material, or improve the overall performance of the light-emitting layer 30 due to an excessively small difference between the LUMO energy levels L1 and L2 of the first host material, which can affect the movement of electrons from the second sub-light-emitting layer 32 to the first sub-light-emitting layer 31.

[0062] In some optional embodiments, the thickness of the first sub-light-emitting layer 31 is less than the thickness of the second sub-light-emitting layer 32. The thickness of the first sub-light-emitting layer 31 refers to the extension of the first sub-light-emitting layer 31 in the direction from the first carrier layer 20 to the second carrier layer 40. Similarly, the thickness of the second sub-light-emitting layer 32 refers to the extension of the second sub-light-emitting layer 32 in the direction from the first carrier layer 20 to the second carrier layer 40.

[0063] In these optional embodiments, the thickness of the first sub-light-emitting layer 31 is relatively small, and the thickness of the second sub-light-emitting layer 32 is relatively large, so that excitons can fully evolve in the second sub-light-emitting layer 32 .

[0064] Optionally, the thickness of the light-emitting layer 30 is 20 nm to 27 nm. That is, the sum of the thicknesses of the first sub-light-emitting layer 31 and the second sub-light-emitting layer 32 is 20 nm to 27 nm. This can improve both the luminous efficiency affected by a too thin light-emitting layer 30 and the luminous efficiency affected by an excessively thick light-emitting layer 30, which results in a long travel distance for holes and electrons, hindering their full recombination.

[0065] Optionally, the thickness of the first light-emitting sub-layer 31 is 2 nm to 8 nm. This can improve the problem of insufficient recombination of holes and electrons due to the first light-emitting sub-layer 31 being too thin, and can also improve the problem of insufficient exciton evolution due to the first light-emitting sub-layer 31 being too thick, squeezing the space in the second light-emitting sub-layer 32 and affecting the luminous efficiency.

[0066] Optionally, the thickness of the second light-emitting sub-layer 32 is 12 nm to 25 nm. This can improve the problem of insufficient exciton evolution and thus poor luminous efficiency due to a too small thickness of the second light-emitting sub-layer 32, and can also improve the problem of insufficient recombination of holes and electrons due to the second light-emitting sub-layer 32 squeezing the space in the first light-emitting sub-layer 31.

[0067] There are various ways to configure the first carrier layer 20 and the second carrier layer 40. For example, the first carrier layer 20 includes a hole injection layer 21, which can extract holes from the first electrode 10. The first carrier layer 20 may also include a hole transport layer 22, which is located on the side of the hole injection layer 21 facing away from the first electrode 10, so that the holes extracted by the hole injection layer 21 are transported to the light-emitting layer 30 via the hole transport layer 22.

[0068] Optionally, the first carrier layer 20 may further include an electron blocking layer 23, which is located between the hole transport layer 22 and the first sub-light-emitting layer 31. The electron blocking layer 23 is used to block electrons that overflow from the first sub-light-emitting layer 31 toward the hole transport layer 22, thereby improving the situation where electrons and holes meet and recombine on the hole transport layer 22 side, thereby improving the luminous efficiency.

[0069] The contact interface between the electron blocking layer 23 and the light-emitting layer 30 is a sensitive interface. The exciton evolution process releases a large amount of energy, and this high energy may damage the sensitive interface. In the embodiment of the present application, the light-emitting layer 30 is divided into a first sub-light-emitting layer 31 and a second sub-light-emitting layer 32. The first sub-light-emitting layer 31 is a charge recombination layer. That is, holes and electrons recombine to form excitons within the first sub-light-emitting layer 31. The excitons are then transferred to the second sub-light-emitting layer 32 for evolution. Therefore, the distance between the exciton evolution and the sensitive interface is relatively large, which can effectively reduce the damage to the sensitive interface caused by the exciton evolution, thereby increasing the service life of the light-emitting device.

[0070] Optionally, the second carrier layer 40 includes an electron injection layer 43, which is used to extract electrons from the second electrode 50. Optionally, the second carrier layer 40 also includes an electron transport layer 42, which is located on the side of the electron injection layer 43 away from the second electrode 50, so that the electrons extracted by the electron injection layer 43 can be transferred to the light-emitting layer 30 via the electron transport layer 42.

[0071] Optionally, the second carrier layer 40 further includes a hole blocking layer 41, which is located between the second sub-light-emitting layer 32 and the electron transport layer 42. The hole blocking layer 41 is used to block holes that overflow from the light-emitting layer 30 toward the electron transport layer 42, thereby improving the situation where holes meet and recombine with electrons in the electron transport layer 42, thereby improving the luminous efficiency.

[0072] Optionally, the thickness of the hole transport layer 22 is greater than the thickness of the electron transport layer 42 .

[0073] In these optional embodiments, the thickness of the hole transport layer 22 is larger, and the time for holes to be transported in the hole transport layer 22 is longer. The thickness of the electron transport layer 42 is smaller, and the time for electrons to be transported in the electron transport layer 42 is shorter. The electrons can enter the light-emitting layer 30 before the holes. When the electrons continue to move to the first sub-light-emitting layer 31, the holes move to the first sub-light-emitting layer 31, so that more electrons and holes can meet and recombine in the first sub-light-emitting layer 31.

[0074] Alternatively, in other embodiments, the mobility of holes in the hole transport layer 22 is less than the mobility of electrons in the electron transport layer 42. In these optional embodiments, the thickness of the hole transport layer 22 and the thickness of the electron transport layer 42 can be equal. In fact, by adjusting the mobility of holes in the hole transport layer 22 and the mobility of electrons in the electron transport layer 42, the thickness of the hole transport layer 22 can be less than the thickness of the electron transport layer 42, and holes and electrons can still meet in the first sub-light-emitting layer 31.

[0075] In order to further illustrate the beneficial effects of the present application, comparative experiments were conducted. A light-emitting device embodiment 1 and comparative example 1 for emitting blue light are provided. The light-emitting device of embodiment 1 includes a first electrode 10, a hole injection layer 21, a hole transport layer 22, an electron blocking layer 23, a first sub-light-emitting layer 31, a second sub-light-emitting layer 32, a hole blocking layer 41, an electron transport layer 42, an electron injection layer 43, and a second electrode 50, which are stacked in sequence. The light-emitting device of comparative example 1 includes a first electrode 10, a hole injection layer 21, a hole transport layer 22, an electron blocking layer 23, a single-layer light-emitting layer 30, a hole blocking layer 41, an electron transport layer 42, an electron injection layer 43, and a second electrode 50, which are stacked in sequence. The total thickness of the first sub-light-emitting layer 31 and the second sub-light-emitting layer 32 in embodiment 1 is the same as the thickness of the single-layer light-emitting layer 30 in comparative example 1. The material of the second sub-light-emitting layer 32 in embodiment 1 is the same as the material of the single-layer light-emitting layer 30 in comparative example 1. The difference is that in Comparative Example 1, a first sub-light emitting layer 31 is provided, and the triplet excited state energy level E T1 and the triplet excited state energy level E of the second host material of the second sub-light emitting layer 32 T2 Satisfaction: E T1 -E T2 =0.3 eV. The following table is obtained by measuring the driving voltage, luminous efficiency and life of Example 1 and Comparative Example 1:

[0076] Driving voltage efficiency life Example 1 99.7％ 104.8％ 211％ Comparative Example 1 100％ 100％ 100％

[0077] As shown in the table above, by adding the first sub-light-emitting layer 31, the driving voltage of the light-emitting device decreases by 0.3%, the efficiency increases by 4.8%, and the lifespan increases by 111%, without changing the overall thickness of the light-emitting layer 30. Therefore, by providing a two-light-emitting layer 30 structure, first and second sub-light-emitting layers 31, 32, holes and electrons recombine in the first sub-light-emitting layer 31, and exciton evolution occurs in the second sub-light-emitting layer 32. This isolates charge recombination and exciton evolution, effectively improving the efficiency and lifespan of the light-emitting device.

[0078] Furthermore, a light-emitting device embodiment 2 and comparative example 2 for emitting blue light are provided. The light-emitting device of embodiment 2 includes a first electrode 10, a hole injection layer 21, a hole transport layer 22, an electron blocking layer 23, a first sub-light-emitting layer 31, a second sub-light-emitting layer 32, a hole blocking layer 41, an electron transport layer 42, an electron injection layer 43, and a second electrode 50, which are stacked in sequence. The light-emitting device of comparative example 2 includes a first electrode 10, a hole injection layer 21, a hole transport layer 22, an electron blocking layer 23, a single-layer light-emitting layer 30, a hole blocking layer 41, an electron transport layer 42, an electron injection layer 43, and a second electrode 50, which are stacked in sequence. The total thickness of the first sub-light-emitting layer 31 and the second sub-light-emitting layer 32 in embodiment 2 is the same as the thickness of the single-layer light-emitting layer 30 in comparative example 2. The material of the second sub-light-emitting layer 32 in embodiment 2 is the same as the material of the single-layer light-emitting layer 30 in comparative example 2. The difference is that in Comparative Example 2, a first sub-light emitting layer 33 is provided, and the triplet excited state energy level E T1 and the triplet excited state energy level E of the second host material of the second sub-light emitting layer 32 T2 Satisfaction: E T1 -E T2 =0.2eV.

[0079] The following table is obtained by measuring the driving voltage, luminous efficiency and life of Example 2 and Comparative Example 2:

[0080] Driving voltage efficiency life Example 2 89.9％ 106.8％ 150％ Comparative Example 2 100％ 100％ 100％

[0081] As can be seen from the table above, by adding the first sub-light-emitting layer 31, without changing the overall thickness of the light-emitting layer 30, the driving voltage of the light-emitting device decreases by 10.1%, the efficiency increases by 6.8%, and the lifespan increases by 50%. Therefore, by providing a two-light-emitting layer 30 structure, first and second sub-light-emitting layers 31, 32, holes and electrons recombine in the first sub-light-emitting layer 31, and exciton evolution occurs in the second sub-light-emitting layer 32. This isolates charge recombination and exciton evolution, effectively improving the efficiency and lifespan of the light-emitting device.

[0082] like Figure 6As shown, an embodiment of the first aspect of the present application further provides a light-emitting device, which includes a first carrier layer 20, a light-emitting layer 30, and a second carrier layer 40 stacked in sequence, wherein the first carrier layer 20 is used to transport holes, and the second carrier layer 40 is used to transport electrons, and the light-emitting layer 30 includes a first sub-light-emitting layer 31 and a second sub-light-emitting layer 32 stacked in the direction from the first carrier layer 20 to the second carrier layer 40, wherein the excited state energy level of the first sub-light-emitting layer 31 is greater than the excited state energy level of the second sub-light-emitting layer 32, and the LUMO energy level of the first sub-light-emitting layer 31 is lower than the LUMO energy level of the second sub-light-emitting layer 32.

[0083] In the light-emitting device provided in the embodiment of the present application, the light-emitting device includes a first carrier layer 20, a second carrier layer 40, and a first sub-light-emitting layer 31 and a second sub-light-emitting layer 32 located between the first carrier layer 20 and the second carrier layer 40. The first sub-light-emitting layer 31 and the second sub-light-emitting layer 32 are both used for emitting light, the first carrier layer 20 is used for transporting holes, and the second carrier layer 40 is used for transporting electrons. In the first sub-light-emitting layer 31 and the second sub-light-emitting layer 32, the LUMO energy level of the first sub-light-emitting layer 31 is lower than the LUMO energy level of the second sub-light-emitting layer 32, so that electrons can more easily move from the second sub-light-emitting layer 32 to the first sub-light-emitting layer 31, and more electrons can move to the first sub-light-emitting layer 31. Holes and electrons can easily recombine in the first sub-light-emitting layer 31 to produce triplet excitons. The excited state energy level of the first sub-light-emitting layer 31 is greater than the excited state energy level of the second sub-light-emitting layer 32, and the excitons can be easily transferred to the second sub-light-emitting layer 32 and evolve from triplet to singlet. Therefore, charge recombination and exciton changes can be isolated from each other, which can improve the conversion efficiency and thus improve the luminous efficiency of the light-emitting device.

[0084] Please also refer to Figures 3 to 6 The light-emitting device of the embodiment of the present application and the light-emitting device of any of the above-mentioned first aspect embodiments can be cross-referenced with each other. For example, in the light-emitting device of the embodiment of the present application, the material of the first sub-light-emitting layer 31 includes the above-mentioned first main material and the light-emitting material, the material of the second sub-light-emitting layer 32 includes the above-mentioned second main material and the light-emitting material, the LUMO energy level of the first main material is lower than the LUMO energy level of the second main material, etc.

[0085] like Figure 1 and Figure 7As shown, an embodiment of the second aspect of the present application further provides a light-emitting device, which includes a first carrier layer 20, a light-emitting layer 30, and a second carrier layer 40 stacked in sequence, wherein the first carrier layer 20 is used to transport holes, and the second carrier layer 40 is used to transport electrons, and the light-emitting layer 30 includes a first sub-light-emitting layer 31 and a second sub-light-emitting layer 32 stacked in the direction from the first carrier layer 20 to the second carrier layer 40, wherein the excited state energy level of the first sub-light-emitting layer 31 is lower than the excited state energy level of the second sub-light-emitting layer 32, and the HOMO energy level of the first sub-light-emitting layer 31 is lower than the HOMO energy level of the second sub-light-emitting layer 32.

[0086] In the light-emitting device provided in the embodiment of the present application, the light-emitting device includes a first carrier layer 20, a second carrier layer 40, and a first sub-light-emitting layer 31 and a second sub-light-emitting layer 32 located between the first carrier layer 20 and the second carrier layer 40. The first sub-light-emitting layer 31 and the second sub-light-emitting layer 32 are both used for emitting light, the first carrier layer 20 is used for transporting holes, and the second carrier layer 40 is used for transporting electrons. In the first sub-light-emitting layer 31 and the second sub-light-emitting layer 32, the HOMO energy level of the first sub-light-emitting layer 31 is lower than the HOMO energy level of the second sub-light-emitting layer 32, so that holes can more easily move from the first sub-light-emitting layer 31 to the second sub-light-emitting layer 32, and more holes can move to the second sub-light-emitting layer 32. Holes and electrons are easily recombined in the second sub-light-emitting layer 32 to produce triplet excitons. The excited state energy level of the first sub-light-emitting layer 31 is lower than the excited state energy level of the second sub-light-emitting layer 32, and the excitons are easily transferred to the first sub-light-emitting layer 31 and evolve from triplet to singlet. Therefore, charge recombination and exciton changes can be isolated from each other, which can improve the conversion efficiency and thus improve the luminous efficiency of the light-emitting device.

[0087] The difference between the light-emitting device provided by the embodiment of the second aspect of the present application and the light-emitting device provided by the embodiment of the first aspect mentioned above is that, in the light-emitting device provided by the embodiment of the first aspect, the first sub-light-emitting layer 31 is a composite layer in which holes and electrons recombine to form excitons, and the second sub-light-emitting layer 32 is a variable layer in which the excitons change and transfer energy to the light-emitting material. In the light-emitting device provided by the embodiment of the second aspect, the opposite is true. The first sub-light-emitting layer 31 is a variable layer in which the excitons change and transfer energy to the light-emitting material, and the second sub-light-emitting layer 32 is a composite layer in which holes and electrons recombine to form excitons. Therefore, in the light-emitting device provided by the embodiment of the second aspect of the present application, the comparison of the HOMO energy level of the first sub-light-emitting layer 31 and the HOMO energy level of the second sub-light-emitting layer 32 is opposite to that of the light-emitting device provided by the embodiment of the first aspect. Similarly, the comparison of the excited state energy level of the first sub-light-emitting layer 31 and the excited state energy level of the second sub-light-emitting layer 32 is also opposite to that of the light-emitting device provided by the embodiment of the first aspect. In addition, in order to further ensure that holes and electrons recombine in the second sub-light-emitting layer 32 and excitons change in the first sub-light-emitting layer 31, the relevant performance of the first sub-light-emitting layer 31 and the second sub-light-emitting layer 32 provided in the second aspect embodiment is opposite to the relevant performance of the first sub-light-emitting layer 31 and the second sub-light-emitting layer 32 provided in the first aspect embodiment.

[0088] For example, in some optional embodiments, the mobility of electrons in the light-emitting layer 30 is lower than the mobility of holes in the light-emitting layer 30 , so that holes and electrons can easily move to the second light-emitting sub-layer 32 .

[0089] In some optional embodiments, the material of the first sub-light-emitting layer 31 includes a first main material and a light-emitting material, and the material of the second sub-light-emitting layer 32 includes a second main material and a light-emitting material, and the HOMO energy level of the first main material is lower than the HOMO energy level of the second main material, so as to facilitate making the HOMO energy level of the first sub-light-emitting layer 31 lower than the HOMO energy level of the second sub-light-emitting layer 32.

[0090] Optionally, the HOMO energy level H1 of the first host material and the HOMO energy level H2 of the second host material satisfy the following conditions: 0.1 eV ≤ H2 - H1 ≤ 0.6 eV. This can improve the situation where the difference between the HOMO energy level H1 of the first host material and the HOMO energy level H2 of the second host material is too small, which makes it difficult for holes to accumulate in the second sub-light-emitting layer 32; or improve the situation where the difference between the HOMO energy level H1 of the first host material and the HOMO energy level H2 of the second host material is too large, which affects the overall device performance of the light-emitting layer 30.

[0091] Optionally, the excited state energy level of the first host material is lower than the excited state energy level of the second host material, so as to facilitate the excited state energy level of the first sub-light-emitting layer 31 to be lower than the excited state energy level of the second sub-light-emitting layer 32 .

[0092] Optionally, the luminescent material is used to emit blue light, so as to improve the performance of the blue light emitting device.

[0093] Optionally, the triplet excited state energy level E of the first host material T1 Less than the triplet excited state energy level E of the second host material T2 . This makes it easier for the excitons to move to the first sub-light-emitting layer 31 .

[0094] Optionally, the triplet excited state energy level E of the first host material T1 and the triplet excited state energy level E of the second host material T2 Satisfies: 0.1eV≤E T2 -E T1 ≤0.6eV. To improve the triplet excited state energy level E of the first host material T1 and the triplet excited state energy level E of the second host material T2 The difference is too small, which affects the movement of excitons to the first sub-light-emitting layer 31; it can also improve the triplet excited state energy level E of the first host material. T1 and the triplet excited state energy level E of the second host material T2 If the difference is too large, the overall performance of the light-emitting layer 30 will be affected.

[0095] Optionally, the triplet excited state energy level E of the luminescent material T Less than the triplet excited state energy level E of the second host material T2 This is beneficial for the excitons to move to the first sub-light-emitting layer 31 .

[0096] Optionally, the triplet excited state energy level E of the luminescent material T and the triplet excited state energy level E of the second host material T2 Satisfies: 0.1eV≤E T2 -E T ≤0.6eV. To improve the triplet excited state energy level E of the luminescent material T and the triplet excited state energy level E of the second host material T2 If the difference is too small, it will affect the movement of excitons to the first sub-light-emitting layer 31; it can also improve the triplet excited state energy level E of the light-emitting material. T and the triplet excited state energy level E of the second host material T2 If the difference is too large, the overall performance of the light-emitting layer 30 will be affected.

[0097] Optionally, the singlet excited state energy level E of the second host material S2 Less than the singlet excited state energy level E of the luminescent material S When the exciton changes, the energy can be transferred to the luminescent material, thereby improving the luminescence effect.

[0098] Optionally, the singlet excited state energy level E of the second host material S2and the singlet excited state energy level E of the luminescent material S Satisfies: 0.1eV≤E S -E S2 ≤0.6eV. To improve the singlet excited state energy level E of the second host material S2 and the singlet excited state energy level E of the luminescent material S The difference is too small to affect the transfer of exciton energy to the luminescent material; it can also improve the singlet excited state energy level E of the second host material. S2 and the singlet excited state energy level E of the luminescent material S A large difference will affect the overall performance of the light-emitting layer 30.

[0099] In some embodiments, as Figure 8 As shown, the LUMO energy level of the first sub-light emitting layer 31 is lower than the LUMO energy level of the second sub-light emitting layer 32 .

[0100] Optional, such as Figure 7 As shown, the LUMO energy level of the first sub-light emitting layer 31 is greater than the LUMO energy level of the second sub-light emitting layer 32. This makes it difficult for electrons to move from the second sub-light emitting layer 32 to the first sub-light emitting layer 31, and more electrons remain in the second sub-light emitting layer 32 to recombine with holes to form excitons.

[0101] Optionally, the LUMO energy level L1 of the first host material and the LUMO energy level L2 of the second host material satisfy the following: 0.1 eV ≤ L1 - L2 ≤ 0.6 eV. This can improve the overall performance of the light-emitting layer 30 due to a large difference between the LUMO energy level L2 of the second host material and the LUMO energy level L1 of the first host material, or improve the electron mobility due to a small difference between the LUMO energy level L2 of the second host material and the LUMO energy level L1 of the first host material.

[0102] like Figure 1 and Figure 9 As shown, an embodiment of the second aspect of the present application further provides a light-emitting device, which includes a first carrier layer 20, a light-emitting layer 30, and a second carrier layer 40 stacked in sequence, wherein the first carrier layer 20 is used to transport holes, and the second carrier layer 40 is used to transport electrons, and the light-emitting layer 30 includes a first sub-light-emitting layer 31 and a second sub-light-emitting layer 32 stacked in the direction from the first carrier layer 20 to the second carrier layer 40, wherein the excited state energy level of the first sub-light-emitting layer 31 is less than the excited state energy level of the second sub-light-emitting layer 32, and the LUMO energy level of the first sub-light-emitting layer 31 is greater than the LUMO energy level of the second sub-light-emitting layer 32.

[0103] In the light-emitting device provided in the embodiment of the present application, the light-emitting device includes a first carrier layer 20, a second carrier layer 40, and a first sub-light-emitting layer 31 and a second sub-light-emitting layer 32 located between the first carrier layer 20 and the second carrier layer 40. The first sub-light-emitting layer 31 and the second sub-light-emitting layer 32 are both used for emitting light, the first carrier layer 20 is used for transporting holes, and the second carrier layer 40 is used for transporting electrons. In the first sub-light-emitting layer 31 and the second sub-light-emitting layer 32, the LUMO energy level of the first sub-light-emitting layer 31 is greater than the LUMO energy level of the second sub-light-emitting layer 32, making it difficult for electrons to move from the second sub-light-emitting layer 32 to the first sub-light-emitting layer 31, and more electrons can remain in the second sub-light-emitting layer 32. Holes and electrons are easily recombined in the second sub-light-emitting layer 32 to produce triplet excitons. The excited state energy level of the first sub-light-emitting layer 31 is lower than the excited state energy level of the second sub-light-emitting layer 32, and the excitons are easily transferred to the first sub-light-emitting layer 31 and evolve from triplet to singlet. Therefore, charge recombination and exciton changes can be isolated from each other, which can improve the conversion efficiency and thereby improve the luminous efficiency of the light-emitting device.

[0104] like Figure 1 、 Figures 7 to 9 As shown, the light-emitting device of the embodiment of the present application and the light-emitting device provided by any of the above-mentioned second aspects of the embodiment can be cross-referenced with each other. For example, in the light-emitting device provided by the embodiment of the present application, the material of the first sub-light-emitting layer 31 includes a first host material and a light-emitting material, the material of the second sub-light-emitting layer 32 includes a second host material and a light-emitting material, and the LUMO energy level of the first host material is greater than the LUMO energy level of the second host material.

[0105] In the light-emitting device provided by the embodiment of the second aspect, optionally, the thickness of the first sub-light-emitting layer 31 is greater than the thickness of the second sub-light-emitting layer 32. In these optional embodiments, the thickness of the first sub-light-emitting layer 31 is larger and the thickness of the second sub-light-emitting layer 32 is smaller, so that excitons can fully evolve in the first sub-light-emitting layer 31.

[0106] In the light-emitting device provided in the second embodiment, the thickness of the light-emitting layer 30 is optionally 20 nm to 27 nm. That is, the sum of the thicknesses of the first sub-light-emitting layer 31 and the second sub-light-emitting layer 32 is 20 nm to 27 nm. This can improve both the luminous efficiency affected by a too thin light-emitting layer 30 and the luminous efficiency affected by an excessively thick light-emitting layer 30, which results in a long travel distance for holes and electrons to move, hindering sufficient recombination.

[0107] In the light-emitting device provided by the embodiment of the second aspect, the thickness of the second sub-light-emitting layer 32 is optionally 2 nm to 8 nm. This can improve the problem of insufficient recombination of holes and electrons due to the second sub-light-emitting layer 32 being too thin, and can also improve the problem of insufficient exciton evolution due to the second sub-light-emitting layer 32 being too thick, squeezing the space in the first sub-light-emitting layer 31 and thus affecting the luminous efficiency.

[0108] In the light-emitting device provided in the embodiment of the second aspect, the thickness of the first light-emitting sub-layer 31 is optionally 12 nm to 25 nm. This can improve the problem of insufficient exciton evolution and thus poor luminous efficiency due to a too thin first light-emitting sub-layer 31, and also improve the problem of insufficient recombination of holes and electrons due to the first light-emitting sub-layer 31 being too thick, which squeezes the space in the second light-emitting sub-layer 32.

[0109] In the light-emitting device provided in the second embodiment, the configuration of the first carrier layer 20 and the second carrier layer 40 can refer to the light-emitting device provided in the first embodiment. For example, the first carrier layer 20 includes at least one of a hole injection layer 21, a hole transport layer 22, and an electron blocking layer 23. Optionally, the second carrier layer 40 includes at least one of an electron injection layer 43, an electron transport layer 42, and a hole blocking layer 41.

[0110] In the light-emitting device provided in the embodiment of the second aspect, optionally, the thickness of the hole transport layer 22 is less than the thickness of the electron transport layer 42 .

[0111] In these optional embodiments, the thickness of the hole transport layer 22 is relatively small, and the time for holes to be transported in the hole transport layer 22 is relatively short. The thickness of the electron transport layer 42 is relatively large, and the time for electrons to be transported in the electron transport layer 42 is relatively long. Holes can enter the light-emitting layer 30 before electrons. When the holes continue to move to the second sub-light-emitting layer 32, the electrons move to the second sub-light-emitting layer 32, so that more electrons and holes can meet and recombine in the second sub-light-emitting layer 32.

[0112] In the light-emitting device provided by the embodiment of the second aspect, optionally, in other embodiments, the mobility of holes in the hole transport layer 22 is greater than the mobility of electrons in the electron transport layer 42. In these optional embodiments, the thickness of the hole transport layer 22 and the thickness of the electron transport layer 42 can be equal. In fact, by adjusting the mobility of holes in the hole transport layer 22 and the mobility of electrons in the electron transport layer 42, the thickness of the hole transport layer 22 can be greater than the thickness of the electron transport layer 42, and holes and electrons still meet in the second sub-light-emitting layer 32.

[0113] In any of the above embodiments, the light-emitting material may include a fluorescent material, so that the light-emitting layer 30 can emit light of different colors.

[0114] Optionally, the luminescent material includes one of the following four categories:

[0115] Category 1: fluorescent materials;

[0116] Category 2: Multi-resonance materials;

[0117] Category 3: Boron and nitrogen materials;

[0118] Category 4: Non-boron-nitrogen boron-oxygen and boron-sulfur materials.

[0119] In these optional embodiments, the selection range of luminescent materials is wider, and users can select luminescent materials with high yield and long life according to actual usage requirements to reduce the manufacturing cost of the display panel and increase the service life of the display panel.

[0120] Alternatively, the multi-resonance material includes a multi-resonance material in which the boron-nitrogen (BN) atoms on either side are not ringed. Alternatively, the fluorescent material includes phenanthrene, fluorene, anthracene, and pyrene fluorescent materials. Alternatively, the boron-nitrogen material includes a material in which the nitrogen atoms on either side are ringed, a polynary boron-nitrogen ring, or a polynary boron-nitrogen ring with different positions. This enriches the variety of luminescent materials.

[0121] Preferably, the luminescent material includes at least one of the following materials:

[0122]

[0123]

[0124]

[0125] Optionally, the first host material and the second host material may be anthracene-based compounds, for example:

[0126]

[0127] The embodiments of the third aspect of the present application further provide a display panel, comprising the light-emitting device of any of the above-mentioned embodiments of the first aspect or the light-emitting device provided by any of the above-mentioned embodiments of the second aspect. Since the display panel provided by the embodiments of the third aspect of the present application comprises the light-emitting device of any of the above-mentioned embodiments of the first aspect or the light-emitting device provided by any of the above-mentioned embodiments of the second aspect, the display panel provided by the embodiments of the second aspect of the present application has the beneficial effects of the light-emitting device of any of the above-mentioned embodiments of the first aspect or the light-emitting device provided by any of the above-mentioned embodiments of the second aspect, and no further details are given here.

[0128] The fourth aspect of the present application also provides a display device, including the display panel of any of the third aspect embodiments. Since the display device provided by the fourth aspect of the present application includes the display panel of any of the three aspects, the display device provided by the fourth aspect of the present application has the beneficial effects of the display panel of any of the third aspects, and will not be further elaborated here.

[0129] The display device in the embodiments of the present application includes but is not limited to mobile phones, personal digital assistants (PDAs), tablet computers, e-books, televisions, access control systems, smart landline phones, consoles, and other devices with display functions.

[0130] Although the present application has been described with reference to preferred embodiments, various modifications may be made thereto and components may be substituted with equivalents without departing from the scope of the present application. In particular, the various technical features described in the various embodiments may be combined in any manner as long as there are no structural conflicts. The present application is not limited to the specific embodiments disclosed herein, but encompasses all technical solutions within the scope of the claims.

Claims

1. A light emitting device, characterized in that: The light-emitting device includes a first carrier layer, a light-emitting layer, and a second carrier layer stacked in sequence, wherein the first carrier layer is used to transport holes, the second carrier layer is used to transport electrons, and the light-emitting layer includes a first sub-light-emitting layer and a second sub-light-emitting layer stacked in a direction from the first carrier layer to the second carrier layer. The excited state energy level of the first light-emitting sub-layer is greater than the excited state energy level of the second light-emitting sub-layer, and the HOMO energy level of the first light-emitting sub-layer is greater than the HOMO energy level of the second light-emitting sub-layer.

2. The light emitting device according to claim 1, wherein The mobility of electrons in the light-emitting layer is greater than the mobility of holes in the light-emitting layer.

3. The light emitting device according to claim 1, wherein The material of the first sub-light-emitting layer includes a first host material and a light-emitting material, the material of the second sub-light-emitting layer includes a second host material and the light-emitting material, and the HOMO energy level of the first host material is greater than the HOMO energy level of the second host material; Preferably, the HOMO energy level H1 of the first host material and the HOMO energy level H2 of the second host material satisfy: 0.1 eV≤H1-H2≤0.6 eV; Preferably, in the first sub-light-emitting layer, the mass ratio of the light-emitting material to the first host material is 1% to 4%.

4. The light emitting device according to claim 3, characterized in that The excited state energy level of the first host material is greater than the excited state energy level of the second host material; Preferably, the luminescent material is used to emit blue light; Preferably, the triplet excited state energy level E of the first host material is T1 greater than the triplet excited state energy level E of the second host material T2 ; Preferably, the triplet excited state energy level E of the first host material is T1 and the triplet excited state energy level E of the second host material T2 Satisfies: 0.1eV≤E T1 -E T2 ≤0.6eV; Preferably, in the second light-emitting sub-layer, the mass ratio of the light-emitting material to the second host material is 1% to 4%.

5. The light emitting device according to claim 3, characterized in that The triplet excited state energy level E of the luminescent material T greater than the triplet excited state energy level E of the second host material T2 ; Preferably, the triplet excited state energy level E of the luminescent material T and the triplet excited state energy level E of the second host material T2 Satisfies: 0.1eV≤E T -E T2 ≤0.6eV; Preferably, the luminescent material includes one of the following four categories: Category 1: fluorescent materials; Category 2: Multi-resonance materials; Category 3: Boron and nitrogen materials; Category 4: Non-boron-nitrogen boron-oxygen and boron-sulfur materials; Preferably, the multi-resonance material comprises a multi-resonance material in which the boron-nitrogen-N atoms on both sides do not form a ring; Preferably, the fluorescent material includes phenanthrene, fluorene, anthracene and pyrene fluorescent materials; Preferably, the boron-nitrogen materials include boron-nitrogen materials with nitrogen atoms forming rings on both sides, polynary boron-nitrogen rings, and polynary boron-nitrogen rings with different positions. The light emitting device according to claim 3 , wherein: The singlet excited state energy level E of the second host material S2 Greater than the singlet excited state energy level E of the luminescent material S ; Preferably, the singlet excited state energy level E of the second host material S2 and the singlet excited state energy level E of the luminescent material S Satisfies: 0.1eV≤E S2 -E S ≤0.6eV.

7. The light emitting device according to claim 1, characterized in that The LUMO energy level of the first sub-light-emitting layer is lower than the LUMO energy level of the second sub-light-emitting layer; Preferably, the material of the first sub-light-emitting layer includes a first host material and a light-emitting material, the material of the second sub-light-emitting layer includes a second host material and the light-emitting material, and the LUMO energy level of the first host material is lower than the LUMO energy level of the second host material; Preferably, the LUMO energy level L1 of the first host material and the LUMO energy level L2 of the second host material satisfy: 0.1 eV≤L2-L1≤0.6 eV.

8. The light emitting device according to claim 1, wherein The thickness of the first sub-light emitting layer is smaller than the thickness of the second sub-light emitting layer; Preferably, the thickness of the light-emitting layer is 20 nm to 27 nm; Preferably, the thickness of the first light-emitting sub-layer is 2 nm to 8 nm; Preferably, the thickness of the second light-emitting sub-layer is 12 nm to 25 nm.

9. The light emitting device according to claim 1, wherein The first carrier layer includes a hole transport layer and an electron blocking layer, and the electron blocking layer is located between the hole transport layer and the first sub-light-emitting layer; Preferably, the second carrier layer includes a hole blocking layer and an electron transport layer, and the hole blocking layer is located between the second sub-light-emitting layer and the electron transport layer; Preferably, the thickness of the hole transport layer is greater than the thickness of the electron transport layer.

10. A light emitting device, characterized in that: The light-emitting device includes a first carrier layer, a light-emitting layer, and a second carrier layer stacked in sequence, wherein the first carrier layer is used to transport holes, the second carrier layer is used to transport electrons, and the light-emitting layer includes a first sub-light-emitting layer and a second sub-light-emitting layer stacked in a direction from the first carrier layer to the second carrier layer. The excited state energy level of the first light-emitting sub-layer is greater than the excited state energy level of the second light-emitting sub-layer, and the LUMO energy level of the first light-emitting sub-layer is lower than the LUMO energy level of the second light-emitting sub-layer.

11. The light emitting device according to claim 10, characterized in that The material of the first sub-light-emitting layer includes a first host material and a light-emitting material, the material of the second sub-light-emitting layer includes a second host material and the light-emitting material, and the LUMO energy level of the first host material is lower than the LUMO energy level of the second host material; Preferably, the LUMO energy level L1 of the first host material and the LUMO energy level L2 of the second host material satisfy: 0.1 eV≤L2-L1≤0.6 eV; Preferably, the excited state energy level of the first host material is greater than the excited state energy level of the second host material; Preferably, the luminescent material is used to emit blue light; Preferably, the triplet excited state energy level E of the first host material is T1 greater than the triplet excited state energy level E of the second host material T2 ; Preferably, the triplet excited state energy level E of the first host material is T1 and the triplet excited state energy level E of the second host material T2 Satisfies: 0.1eV≤E T1 -E T2 ≤0.6eV; Preferably, the triplet excited state energy level E of the luminescent material T greater than the triplet excited state energy level E of the second host material T2 ; Preferably, the triplet excited state energy level E of the luminescent material T and the triplet excited state energy level E of the second host material T2 Satisfies: 0.1eV≤E T -E T2 ≤0.6eV; Preferably, the singlet excited state energy level E of the second host material S2 Greater than the singlet excited state energy level E of the luminescent material S ; Preferably, the singlet excited state energy level E of the second host material S2 and the singlet excited state energy level E of the luminescent material S Satisfies: 0.1eV≤E S2 -E S ≤0.6eV.

12. The light emitting device according to claim 10, characterized in that The mobility of electrons in the light-emitting layer is greater than the mobility of holes in the light-emitting layer.

13. A light emitting device, characterized in that: The light-emitting device includes a first carrier layer, a light-emitting layer, and a second carrier layer stacked in sequence, wherein the first carrier layer is used to transport holes, the second carrier layer is used to transport electrons, and the light-emitting layer includes a first sub-light-emitting layer and a second sub-light-emitting layer stacked in a direction from the first carrier layer to the second carrier layer. The excited state energy level of the first sub-light emitting layer is lower than the excited state energy level of the second sub-light emitting layer, and the HOMO energy level of the first sub-light emitting layer is lower than the HOMO energy level of the second sub-light emitting layer.

14. The light emitting device according to claim 13, characterized in that The mobility of electrons in the light emitting layer is lower than the mobility of holes in the light emitting layer.

15. The light emitting device according to claim 13, characterized in that The material of the first sub-light-emitting layer includes a first host material and a light-emitting material, the material of the second sub-light-emitting layer includes a second host material and the light-emitting material, and the HOMO energy level of the first host material is lower than the HOMO energy level of the second host material; Preferably, the HOMO energy level H1 of the first host material and the HOMO energy level H2 of the second host material satisfy: 0.1eV≤H2-H1≤0.6eV; Preferably, the excited state energy level of the first host material is lower than the excited state energy level of the second host material; Preferably, the luminescent material is used to emit blue light; Preferably, the triplet excited state energy level E of the first host material is T1 is less than the triplet excited state energy level E of the second host material T2 ; Preferably, the triplet excited state energy level E of the first host material is T1 and the triplet excited state energy level E of the second host material T2 Satisfies: 0.1eV≤E T2 -E T1 ≤0.6eV; Preferably, the triplet excited state energy level E of the luminescent material T is less than the triplet excited state energy level E of the second host material T2 ; Preferably, the triplet excited state energy level E of the luminescent material T and the triplet excited state energy level E of the second host material T2 Satisfies: 0.1eV≤E T2 -E T ≤0.6eV; Preferably, the singlet excited state energy level E of the second host material S2 Less than the singlet excited state energy level E of the luminescent material S ; Preferably, the singlet excited state energy level E of the second host material S2 and the singlet excited state energy level E of the luminescent material S Satisfies: 0.1eV≤E S -E S2 ≤0.6eV; Preferably, the LUMO energy level of the first sub-light-emitting layer is higher than the LUMO energy level of the second sub-light-emitting layer; Preferably, the LUMO energy level of the first host material is lower than the LUMO energy level of the second host material; Preferably, the LUMO energy level L1 of the first host material and the LUMO energy level L2 of the second host material satisfy: 0.1 eV≤L1-L2≤0.6 eV.

16. A light emitting device board, characterized in that: The light-emitting device includes a first carrier layer, a light-emitting layer, and a second carrier layer stacked in sequence, wherein the first carrier layer is used to transport holes, the second carrier layer is used to transport electrons, and the light-emitting layer includes a first sub-light-emitting layer and a second sub-light-emitting layer stacked in a direction from the first carrier layer to the second carrier layer. The excited state energy level of the first sub-light emitting layer is lower than the excited state energy level of the second sub-light emitting layer, and the LUMO energy level of the first sub-light emitting layer is higher than the LUMO energy level of the second sub-light emitting layer.

17. The light emitting device according to claim 16, characterized in that The material of the first sub-light-emitting layer includes a first host material and a light-emitting material, the material of the second sub-light-emitting layer includes a second host material and the light-emitting material, and the LUMO energy level of the first host material is greater than the LUMO energy level of the second host material; Preferably, the LUMO energy level L1 of the first host material and the LUMO energy level L2 of the second host material satisfy: 0.1 eV≤L1-L2≤0.6 eV; Preferably, the excited state energy level of the first host material is lower than the excited state energy level of the second host material; Preferably, the luminescent material is used to emit blue light; Preferably, the triplet excited state energy level E of the first host material is T1 is less than the triplet excited state energy level E of the second host material T2 ; Preferably, the triplet excited state energy level E of the first host material is T1 and the triplet excited state energy level E of the second host material T2 Satisfies: 0.1eV≤E T2 -E T1 ≤0.6eV; Preferably, the triplet excited state energy level E of the luminescent material T is less than the triplet excited state energy level E of the second host material T2 ; Preferably, the triplet excited state energy level E of the luminescent material T and the triplet excited state energy level E of the second host material T2 Satisfies: 0.1eV≤E T2 -E T1 ≤0.6eV; Preferably, the singlet excited state energy level E of the second host material S2 Less than the singlet excited state energy level E of the luminescent material S ; Preferably, the singlet excited state energy level E of the second host material S2 and the singlet excited state energy level E of the luminescent material S Satisfies: 0.1eV≤E S -E S2 ≤0.6eV.

18. A display panel, characterized in that: The light-emitting device comprises the light-emitting device according to any one of claims 1 to 17.

19. A display device, characterized in that: The display panel according to claim 18 is included.

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