Light emitting structure, display panel and display device

Abstract

A light-emitting structure, a display panel and a display device. The light-emitting structure includes a first light-emitting element; the first light-emitting element includes a first light-emitting layer, a first electron transport layer and a first cathode; the first cathode is arranged in contact with the first electron transport layer, the conduction band bottom energy level of the first electron transport layer is greater than the Fermi level of the first cathode, and the difference between the conduction band bottom energy level of the first electron transport layer and the Fermi level of the first cathode is in the range of 0.3-0.6eV. In the light-emitting structure, the electron injection efficiency of the first light-emitting element can be appropriately reduced and matched with the hole injection efficiency of the first light-emitting element, thereby improving the luminous efficiency and stability of the first light-emitting element.

Description

Technical Field

[0001] Embodiments of the present disclosure relate to a light emitting structure, a display panel, and a display device. Background Art

[0002] With the continuous development of display technology, there are more and more types of display devices. Light Emitting Diode (LED) display devices have attracted widespread attention in the industry due to their advantages such as self-luminescence, high brightness, low operating voltage, low power consumption, long life, impact resistance and stable performance. In addition, since LED display devices do not require additional backlight modules, they are lighter in weight, which is conducive to the thinning of display devices, and therefore have good market prospects.

[0003] Quantum Dot (QD) is a new type of luminescent material with the advantages of high light color purity, high light quantum efficiency, adjustable light color, and long service life. It has become a research hotspot for new LED luminescent materials. Therefore, quantum dot light emitting diodes (QLED) with quantum dot materials as the light-emitting layer have become the main research direction of new display devices. Summary of the invention

[0004] The disclosed embodiments provide a light-emitting structure, a display panel and a display device. The light-emitting structure includes a first light-emitting element; the first light-emitting element includes a first light-emitting layer, a first electron transport layer and a first cathode; the first cathode is arranged in contact with the first electron transport layer, the conduction band bottom energy level of the first electron transport layer is greater than the Fermi level of the first cathode, and the difference between the conduction band bottom energy level of the first electron transport layer and the Fermi level of the first cathode is in the range of 0.3-0.6eV. In the light-emitting structure, since the conduction band bottom energy level of the first electron transport layer is greater than the Fermi level of the first cathode, electrons need to cross a potential barrier from the first cathode to the first electron transport layer, and the difference between the conduction band bottom energy level of the first electron transport layer and the Fermi level of the first cathode is in the range of 0.3-0.6eV, so that the electron injection efficiency of the first light-emitting element can be appropriately reduced and matched with the hole injection efficiency of the first light-emitting element, thereby improving the luminous efficiency and stability of the first light-emitting element.

[0005] At least one embodiment of the present disclosure provides a light-emitting structure, which includes: a first light-emitting element, including a first light-emitting layer, a first electron transport layer and a first cathode, the first cathode is arranged in contact with the first electron transport layer, the conduction band bottom energy level of the first electron transport layer is greater than the Fermi level of the first cathode, and the difference between the conduction band bottom energy level of the first electron transport layer and the Fermi level of the first cathode is in the range of 0.3-0.6eV.

[0006] For example, in a light-emitting structure provided in an embodiment of the present disclosure, the material of the first light-emitting layer includes a cadmium-free quantum dot material, the first electron transport layer includes ZnMgO nanoparticles, and the molar percentage of Mg in the first electron transport layer is 10%-20%.

[0007] For example, in a light-emitting structure provided in an embodiment of the present disclosure, the material of the first light-emitting layer includes indium phosphide.

[0008] For example, in a light-emitting structure provided in an embodiment of the present disclosure, the molar percentage of Mg in the first electron transport layer is 13%-16%.

[0009] For example, the light-emitting structure provided by one embodiment of the present disclosure also includes: a second light-emitting element, including a second light-emitting layer, a second electron transport layer and a second cathode, the second cathode is arranged in contact with the second electron transport layer, the conduction band bottom energy level of the first light-emitting layer is less than the conduction band bottom energy level of the second light-emitting layer, and the conduction band bottom energy level of the first electron transport layer is greater than the conduction band bottom energy level of the second electron transport layer.

[0010] For example, in the light-emitting structure provided in an embodiment of the present disclosure, the potential barrier of electrons from the first cathode to the first electron transport layer is greater than the potential barrier of electrons from the second cathode to the second electron transport layer.

[0011] For example, in the light-emitting structure provided in one embodiment of the present disclosure, the conduction band bottom energy level of the first light-emitting layer is lower than the conduction band bottom energy level of the first electron transport layer, the conduction band bottom energy level of the second light-emitting layer is higher than the conduction band bottom energy level of the second electron transport layer, and the Fermi level of the second cathode is approximately equal to the conduction band bottom energy level of the second electron transport layer.

[0012] For example, in a light-emitting structure provided in an embodiment of the present disclosure, the first electron transport layer includes ZnMgO nanoparticles, the second electron transport layer includes ZnO nanoparticles or ZnMgO nanoparticles, and the molar percentage of Mg in the first electron transport layer is greater than the molar percentage of Mg in the second electron transport layer.

[0013] For example, in the light-emitting structure provided in an embodiment of the present disclosure, the molar percentage of Mg in the first electron transport layer is 10%-20%, and the molar percentage of Mg in the second electron transport layer is less than 5%.

[0014] For example, in a light-emitting structure provided in an embodiment of the present disclosure, at least one of the first light-emitting layer and the second light-emitting layer is a quantum dot light-emitting layer, and the first cathode and the second cathode are the same conductive layer.

[0015] For example, the light-emitting structure provided by one embodiment of the present disclosure also includes: a third light-emitting element, including a third light-emitting layer, a third electron transport layer and a third cathode, the third cathode is arranged in contact with the third electron transport layer, the conduction band bottom energy level of the third light-emitting layer is greater than the conduction band bottom energy level of the first light-emitting layer, and less than the conduction band bottom energy level of the second light-emitting layer, the conduction band bottom energy level of the third electron transport layer is less than the conduction band bottom energy level of the first electron transport layer, and the conduction band bottom energy level of the third electron transport layer is greater than the conduction band bottom energy level of the second electron transport layer.

[0016] For example, in the light-emitting structure provided in one embodiment of the present disclosure, the potential barrier for electrons from the third cathode to the third electron transport layer is greater than the potential barrier for electrons from the second cathode to the second electron transport layer, and is smaller than the potential barrier for electrons from the first cathode to the first electron transport layer.

[0017] For example, in a light-emitting structure provided in an embodiment of the present disclosure, the first electron transport layer includes ZnMgO nanoparticles, the second electron transport layer includes ZnO nanoparticles or ZnMgO nanoparticles, the third electron transport layer includes ZnMgO nanoparticles, and the molar percentage of Mg in the third electron transport layer is less than the molar percentage of Mg in the first electron transport layer, and greater than the molar percentage of Mg in the second electron transport layer.

[0018] For example, in the light-emitting structure provided in one embodiment of the present disclosure, the molar percentage of Mg in the first electron transport layer is 10%-20%, the molar percentage of Mg in the second electron transport layer is less than 5%, and the molar percentage of Mg in the third electron transport layer is 5%-10%.

[0019] For example, in a light-emitting structure provided in an embodiment of the present disclosure, the electron mobility of the first electron transport layer is less than the electron mobility of the second electron transport layer.

[0020] For example, in the light-emitting structure provided in an embodiment of the present disclosure, the electron mobility of the third electron transport layer is greater than the electron mobility of the second electron transport layer, and is less than the electron mobility of the second electron transport layer.

[0021] For example, in a light-emitting structure provided in an embodiment of the present disclosure, the first light-emitting layer is configured to emit red light, and the second light-emitting layer is configured to emit blue light.

[0022] For example, in the light-emitting structure provided in an embodiment of the present disclosure, the first light-emitting layer is configured to emit red light, the second light-emitting layer is configured to emit blue light, and the third light-emitting layer is configured to emit green light.

[0023] At least one embodiment of the present disclosure further provides a display panel, comprising a plurality of light-emitting structures arranged in an array, each of the light-emitting structures being the light-emitting structure described above.

[0024] At least one embodiment of the present disclosure further provides a display device, comprising the above-mentioned display panel. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions of the embodiments of the present disclosure, the drawings of the embodiments will be briefly introduced below. Obviously, the drawings in the following description only relate to some embodiments of the present disclosure, but are not intended to limit the present disclosure.

[0026] Figure 1 A schematic diagram of a light-emitting structure provided according to an embodiment of the present disclosure;

[0027] Figure 2 A comparison diagram of electron injection efficiency and hole injection efficiency of a first light-emitting element of a light-emitting structure provided according to an embodiment of the present disclosure using different electron transport layers;

[0028] Figure 3 A comparison diagram of current efficiencies of different electron transport layers used in a first light-emitting element of a light-emitting structure provided according to an embodiment of the present disclosure;

[0029] Figure 4 A schematic diagram of energy levels of different light-emitting layers and different electron transport layers in a light-emitting structure provided according to an embodiment of the present disclosure; and

[0030] Figure 5 This is a schematic diagram of energy levels of different light-emitting layers and different electron transport layers in another light-emitting structure provided according to an embodiment of the present disclosure. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical solution and advantages of the embodiments of the present disclosure clearer, the technical solution of the embodiments of the present disclosure will be clearly and completely described below in conjunction with the drawings of the embodiments of the present disclosure. Obviously, the described embodiments are part of the embodiments of the present disclosure, not all of the embodiments. Based on the described embodiments of the present disclosure, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present disclosure.

[0032] Unless otherwise defined, the technical terms or scientific terms used in the present disclosure should be understood by people with ordinary skills in the field to which the present disclosure belongs. "First", "second" and similar words used in the present disclosure do not indicate any order, quantity or importance, but are only used to distinguish different components. "Include" or "comprise" and similar words mean that the elements or objects appearing before the word cover the elements or objects listed after the word and their equivalents, without excluding other elements or objects. "Connect" or "connected" and similar words are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect.

[0033] In common QLED devices, due to the energy level position of quantum dot materials and other reasons, the electron injection efficiency of the red and green quantum dot light-emitting layers is generally better than the hole injection efficiency, resulting in the number of electrons in the carriers of the red and green quantum dot light-emitting layers being greater than the number of holes; on the contrary, the electron injection efficiency of the blue quantum dot light-emitting layer is weaker than the hole injection efficiency, resulting in the number of holes in the carriers of the blue quantum dot light-emitting layer being greater than the number of electrons. Therefore, the imbalance of electrons and holes in the quantum dot light-emitting layer in the QLED device, and the imbalance of electrons and holes will not only reduce the ability of the injected charge to be converted into excitons, but also cause the charge to accumulate in the QLED device, increase the non-radiative transition of the charged excitons, reduce the efficiency and attenuate the service life, thus becoming a bottleneck limiting the further improvement of the efficiency and stability of QLED devices.

[0034] In this regard, the embodiments of the present disclosure provide a light-emitting structure, a display panel and a display device. The light-emitting structure includes a first light-emitting element; the first light-emitting element includes a first light-emitting layer, a first electron transport layer and a first cathode; the first cathode is arranged in contact with the first electron transport layer, the conduction band bottom energy level of the first electron transport layer is greater than the Fermi level of the first cathode, and the difference between the conduction band bottom energy level of the first electron transport layer and the Fermi level of the first cathode is in the range of 0.3-0.6eV. In the light-emitting structure, since the conduction band bottom energy level of the first electron transport layer is greater than the Fermi level of the first cathode, electrons need to cross a potential barrier from the first cathode to the first electron transport layer, and the difference between the conduction band bottom energy level of the first electron transport layer and the Fermi level of the first cathode is in the range of 0.3-0.6eV, so that the electron injection efficiency of the first light-emitting element can be appropriately reduced and matched with the hole injection efficiency of the first light-emitting element, thereby improving the luminous efficiency and stability of the first light-emitting element.

[0035] The light emitting structure, display panel and display device provided by the embodiments of the present disclosure are described below with reference to the accompanying drawings.

[0036] Figure 1 FIG. 1 is a schematic diagram of a light emitting structure provided according to an embodiment of the present disclosure. Figure 1As shown, the light emitting structure 100 includes a first light emitting element 110; the first light emitting element 110 includes a first light emitting layer 111, a first electron transport layer 112 and a first cathode 113; the first cathode 113 is arranged in contact with the first electron transport layer 112, and when the first light emitting element 110 emits light, the first cathode 113 is used to provide electrons. The conduction band bottom energy level of the first electron transport layer 112 is greater than the Fermi level of the first cathode 113, and the difference between the conduction band bottom energy level of the first electron transport layer 112 and the Fermi level of the first cathode 113 is in the range of 0.3-0.6eV.

[0037] In the light-emitting structure provided in the embodiment of the present disclosure, when the electron injection efficiency of the first light-emitting layer is better than the hole injection efficiency, since the conduction band bottom energy level of the first electron transport layer is greater than the Fermi level of the first cathode, the electrons need to cross a potential barrier from the first cathode to the first electron transport layer, and the difference between the conduction band bottom energy level of the first electron transport layer and the Fermi level of the first cathode is in the range of 0.3-0.6 eV, thereby appropriately reducing the electron injection efficiency of the first light-emitting element and matching it with the hole injection efficiency of the first light-emitting element, thereby improving the luminous efficiency and stability of the first light-emitting element.

[0038] For example, in some examples, such as Figure 1 As shown, the first light-emitting layer 111 and the first electron transport layer 112 are arranged in contact, that is, the first light-emitting element 110 is not provided with an electron injection layer, so that the thickness of the first light-emitting element 110 can be reduced while reducing the electron injection efficiency of the first light-emitting element 110, thereby providing a light and thin light-emitting structure.

[0039] For example, in some examples, the first light-emitting layer 111 may be a red quantum dot light-emitting layer. Since the electron injection efficiency of a common red quantum dot light-emitting layer is generally better than the hole injection efficiency, the holes and electrons in the carriers of the red quantum dot light-emitting layer are very unbalanced; and the light-emitting structure provided in the embodiment of the present disclosure selects suitable materials so that the conduction band bottom energy level of the first electron transport layer is greater than the Fermi level of the first cathode, and the difference between the conduction band bottom energy level of the first electron transport layer and the Fermi level of the first cathode is in the range of 0.3-0.6eV, so that the electron injection efficiency and hole injection efficiency of the first light-emitting element are matched, thereby improving the luminous efficiency and stability of the first light-emitting element.

[0040] For example, in some examples, the material of the first light emitting layer 111 may include a cadmium-free quantum dot material, thereby reducing pollution to the environment. The first electron transport layer 112 includes ZnMgO nanoparticles, i.e., ZnO nanoparticles doped with Mg, and the molar percentage of Mg in the first electron transport layer 112 is 10%-20%, so that the difference between the conduction band bottom energy level of the first electron transport layer 112 and the Fermi level of the first cathode 113 can be in the range of 0.3-0.6 eV.

[0041] For example, in some examples, the material of the first cathode 113 may be silver or aluminum. Thus, the Fermi level of the first cathode 113 may be in the range of -4.3 to -4.2 eV.

[0042] For example, in some examples, the material of the first light emitting layer 111 may include indium phosphide (InP), and the molar percentage of Mg in the first electron transport layer 112 is 13%-16%. At this time, the conduction band bottom energy level of the first electron transport layer 112 is approximately -3.83eV, and the Fermi level of the first cathode 113 may range from -4.3 to -4.2eV, so that the difference between the conduction band bottom energy level of the first electron transport layer 112 and the Fermi level of the first cathode 113 is approximately 0.37-0.47eV. At this time, the luminous efficiency and stability of the first light emitting element 110 can be greatly increased.

[0043] Figure 2 A comparison diagram of electron injection efficiency and hole injection efficiency of a first light-emitting element of a light-emitting structure provided according to an embodiment of the present disclosure using different electron transport layers; Figure 3 This is a comparison diagram of the current efficiencies of the first light-emitting element of a light-emitting structure provided according to an embodiment of the present disclosure using different electron transport layers. Figure 2 and Figure 3 The first light-emitting element is a red quantum dot light-emitting element, and the first light-emitting layer is made of indium phosphide (InP).

[0044] like Figure 2 As shown, curve 1 is the hole injection efficiency of the first light-emitting element; curve 2 is the electron injection efficiency of the first light-emitting element using ZnMgO nanoparticles with a Mg molar percentage of 15% in the electron transport layer; curve 3 is the electron injection efficiency of the first light-emitting element using ZnMgO nanoparticles with a Mg molar percentage of 5% in the electron transport layer; curve 4 is the electron injection efficiency of the first light-emitting element using ZnO nanoparticles or ZnMgO nanoparticles with a Mg molar percentage of 0%, i.e., ZnO nanoparticles. The experimental results show that the electron injection efficiency shown in curve 2 is more matched with the hole injection efficiency shown in curve 1, which is conducive to improving the luminous efficiency and stability of the first light-emitting element. It should be noted that the hole injection efficiency of curve 1 is a curve measured when the first light-emitting element only includes a light-emitting layer and a hole transport layer; the electron injection efficiency of curve 2 is a curve measured when the first light-emitting element only includes a light-emitting layer and an electron transport layer; the electron injection efficiency of curve 3 is a curve measured when the first light-emitting element only includes a light-emitting layer and an electron transport layer; the electron injection efficiency of curve 4 is a curve measured when the first light-emitting element only includes a light-emitting layer and an electron transport layer.

[0045] like Figure 3As shown, curve 5 is the current efficiency of the first light-emitting element whose electron transport layer adopts ZnMgO nanoparticles with a molar percentage of Mg of 15%; curve 6 is the current efficiency of the first light-emitting element whose electron transport layer adopts ZnMgO nanoparticles with a molar percentage of Mg of 5%; curve 7 is the current efficiency of the first light-emitting element whose electron transport layer adopts ZnO nanoparticles or ZnMgO nanoparticles with a molar percentage of Mg of 0%, i.e., ZnO nanoparticles. The experimental results show that the current efficiency of the first light-emitting element shown in curve 5 is significantly higher than that of curves 6 and 7; and, as the molar percentage of Mg increases, the current efficiency of the first light-emitting element shown in curve 5 does not increase linearly, but suddenly increases, which is much higher than curves 6 and 7. Therefore, when the electron transport layer adopts ZnMgO nanoparticles with a molar percentage of Mg of 15%, the first light-emitting element has a higher current efficiency. It should be noted that the other film layers (for example, hole transport layer, etc.) of the first light-emitting element shown in curves 5, 6 and 7 all adopt the same materials and structures.

[0046] For example, in some examples, such as Figure 1 As shown, the first light-emitting element 110 further includes a first hole transport layer 114, a first hole injection layer 115 and a first anode 116. The first hole transport layer 114 is disposed on a side of the first light-emitting layer 111 away from the first electron transport layer 112, the first hole injection layer 115 is disposed on a side of the first hole transport layer 114 away from the first light-emitting layer 111, and the first anode 116 is disposed on a side of the first hole injection layer 115 away from the first hole transport layer 114.

[0047] For example, the first anode 116 may be made of a transparent conductive oxide or a conductive polymer. The transparent conductive oxide may be indium tin oxide (ITO), FTO (SnO 2 ) etc. In addition, the materials of the first hole transport layer 114 and the first hole injection layer 115 can be selected according to actual conditions, and the embodiments of the present disclosure are not limited thereto.

[0048] For example, in some examples, such as Figure 1 As shown, the light emitting structure further includes a base substrate 101 for carrying the above-mentioned first light emitting element 110. For example, the base substrate 101 may be a transparent substrate, such as a glass substrate, a quartz substrate, a plastic substrate, etc. The base substrate 101 may also be a flexible transparent substrate, such as a polyethylene terephthalate plastic (PET) substrate.

[0049] For example, in some examples, such as Figure 1As shown, the light emitting structure 100 further includes a second light emitting element 120; the first light emitting element 110 and the second light emitting element 120 can be used to emit light of different colors. The second light emitting element 120 includes a second light emitting layer 121, a second electron transport layer 122 and a second cathode 123. The second cathode 123 is arranged in contact with the second electron transport layer 122, the conduction band bottom energy level of the first light emitting layer 111 is lower than the conduction band bottom energy level of the second light emitting layer 121, and the conduction band bottom energy level of the first electron transport layer 112 is higher than the conduction band bottom energy level of the second electron transport layer 122.

[0050] In the light-emitting structure provided in this example, different light-emitting elements (such as the first light-emitting element and the second light-emitting element) use electron transport layers made of different materials. Since the bottom energy level of the conduction band of the first light-emitting layer 111 is lower than the bottom energy level of the conduction band of the second light-emitting layer 121, the difficulty of electrons from the first electron transport layer 112 to the first light-emitting layer 111 is lower than the difficulty of electrons from the second electron transport layer 122 to the second light-emitting layer 121. At this time, since the bottom energy level of the conduction band of the first electron transport layer 112 is higher than the bottom energy level of the conduction band of the second electron transport layer 122, when the Fermi levels of the first cathode 113 and the second cathode 123 are approximately the same, the potential barrier of electrons from the first cathode 113 to the first transport layer 112 is higher than the potential barrier of electrons from the second cathode 123 to the second electron transport layer 122, thereby to a certain extent The efficiency of electron injection into the first light-emitting layer 111 is reduced to a certain extent, thereby achieving a balance with the hole injection efficiency in the first light-emitting layer 111; and, since the bottom energy level of the conduction band of the first electron transport layer 112 is greater than the bottom energy level of the conduction band of the second electron transport layer 122, the light-emitting structure provided in this example can also reduce the potential barrier of electrons from the second cathode 123 to the second electron transport layer 122, thereby improving the efficiency of electron injection into the second light-emitting layer 121 to a certain extent, thereby achieving a balance with the hole injection efficiency in the second light-emitting layer 121, thereby simultaneously improving the luminous efficiency and stability of the first light-emitting element 110 and the second light-emitting element 120.

[0051] For example, in some examples, the first cathode 113 and the second cathode 123 are the same conductive layer, that is, the first light-emitting element 110 and the second light-emitting element 120 share a cathode layer. At this time, the potential barrier of electrons from the first cathode 113 to the first electron transport layer 112 is greater than the potential barrier of electrons from the second cathode 123 to the second electron transport layer 122.

[0052] Figure 4 Schematic diagram of energy levels of different light-emitting layers and different electron transport layers in a light-emitting structure provided according to an embodiment of the present disclosure. Figure 4As shown, the conduction band bottom energy level of the first light-emitting layer 111 is less than the conduction band bottom energy level of the first electron transport layer 112, and the conduction band bottom energy level of the second light-emitting layer 121 is greater than the conduction band bottom energy level of the second electron transport layer 122, that is, there is no or almost no potential barrier for electrons to travel from the first electron transport layer 112 to the first light-emitting layer 111, while electrons need to cross a potential barrier from the second electron transport layer 122 to the second light-emitting layer 121. At this time, the Fermi level of the second cathode 123 is roughly equal to the conduction band bottom energy level of the second electron transport layer 122, that is, there is no or almost no potential barrier for electrons to travel from the second cathode 123 to the second electron transport layer 122. As a result, the light-emitting structure can improve the electron injection efficiency from the second cathode 123 to the second light-emitting layer 121 to a certain extent, thereby achieving a balance with the hole injection efficiency in the second light-emitting layer 121, thereby improving the luminous efficiency and stability of the second light-emitting element 120. It should be noted that the Fermi level of the second cathode and the conduction band bottom energy level of the second electron transport layer being approximately equal means that the ratio of the difference between the Fermi level of the second cathode and the conduction band bottom energy level of the second electron transport layer to the absolute value of the Fermi level of the second cathode is within 4%.

[0053] For example, in some examples, the first electron transport layer 112 includes ZnMgO nanoparticles, the second electron transport layer 122 includes ZnO nanoparticles or ZnMgO nanoparticles, and the molar percentage of Mg in the first electron transport layer 112 is greater than the molar percentage of Mg in the second electron transport layer 122 .

[0054] For example, in some examples, the molar percentage of Mg in the first electron transport layer 112 is 10%-20%, and the molar percentage of Mg in the second electron transport layer 122 is less than 5%. It should be noted that when the second electron transport layer 122 is ZnO nanoparticles, it can be considered that the second electron transport layer 122 is ZnMgO nanoparticles with a molar percentage of Mg of 0.

[0055] Table 1 is an energy level data table of an electron transport layer provided according to an embodiment of the present disclosure. In Table 1, the first electron transport layer 112 is ZnMgO nanoparticles with a molar percentage of Mg of 15%, and the second electron transport layer 122 is ZnMgO nanoparticles with a molar percentage of Mg of 0%. It can be seen that the conduction band bottom energy level of the first electron transport layer 112 is greater than the conduction band bottom energy level of the second electron transport layer 122. When the Fermi level of the first cathode 113 and the second cathode 123 ranges from -4.3 to -4.2 eV, the difference between the conduction band bottom energy level of the first electron transport layer 112 and the Fermi level of the first cathode 113 is approximately 0.37-0.47 eV, and the difference between the conduction band bottom energy level of the second electron transport layer 122 and the Fermi level of the second cathode 123 is less than 0.1 eV. Therefore, the light-emitting structure can reduce the efficiency of electron injection into the first light-emitting layer 111 to a certain extent, thereby achieving a balance with the hole injection efficiency in the first light-emitting layer 111; and improve the efficiency of electron injection into the second light-emitting layer 121 to a certain extent, thereby achieving a balance with the hole injection efficiency in the second light-emitting layer 121.

[0056]

[0057] Table 1 - Energy level data table of electron transport layer

[0058] For example, in some examples, the electron mobility of the first electron transport layer 112 is less than the electron mobility of the second electron transport layer 122, thereby reducing the efficiency of electron injection into the first light-emitting layer 111 to a certain extent, thereby achieving a balance with the hole injection efficiency in the first light-emitting layer 111; and improving the efficiency of electron injection into the second light-emitting layer 121 to a certain extent, thereby achieving a balance with the hole injection efficiency in the second light-emitting layer 121. For example, when the first electron transport layer 112 is ZnMgO nanoparticles with a molar percentage of Mg of 15%, and the second electron transport layer 122 is ZnMgO nanoparticles with a molar percentage of Mg of 0%, the electron mobility of the first electron transport layer 112 is less than the electron mobility of the second electron transport layer 122.

[0059] For example, in some examples, at least one of the first light-emitting layer and the second light-emitting layer is a quantum dot light-emitting layer. For example, the first light-emitting layer may be a red quantum dot light-emitting layer, and the second light-emitting layer may be a blue quantum dot light-emitting layer; the first light-emitting layer may use a red cadmium-free quantum dot light-emitting material, such as indium phosphide (InP), such as InP / ZnS core-shell quantum dot material; the second light-emitting layer may use a blue quantum dot light-emitting material, such as cadmium selenide (CdSe), such as CdSe / ZnS core-shell quantum dot material.

[0060] For example, in some examples, such as Figure 1As shown, the second light-emitting element 120 further includes a second hole transport layer 124, a second hole injection layer 125 and a second anode 116. The second hole transport layer 124 is disposed on a side of the second light-emitting layer 121 away from the second electron transport layer 122, the second hole injection layer 125 is disposed on a side of the second hole transport layer 124 away from the second light-emitting layer 121, and the second anode 126 is disposed on a side of the second hole injection layer 125 away from the second hole transport layer 124.

[0061] For example, the second anode 126 may be made of a transparent conductive oxide or a conductive polymer, and the transparent conductive oxide may be indium tin oxide (ITO), FTO (SnO2), etc. In addition, the materials of the second hole transport layer 124 and the second hole injection layer 125 may be selected according to actual conditions, and the embodiments of the present disclosure are not limited thereto.

[0062] For example, in some examples, such as Figure 1 As shown, the first light-emitting element 110 and the second light-emitting element 120 are arranged on the base substrate 101 in the same layer. That is to say, the first anode 116 of the first light-emitting element 110 and the second anode 126 of the second light-emitting element 120 can be arranged in the same layer; the first hole injection layer 115 of the first light-emitting element 110 and the second hole injection layer 125 of the second light-emitting element 120 can be arranged in the same layer; the first hole transport layer 114 of the first light-emitting element 110 and the second hole transport layer 124 of the second light-emitting element 120 can be arranged in the same layer; the first light-emitting layer 111 of the first light-emitting element 110 and the second light-emitting layer 121 of the second light-emitting element 120 can be arranged in the same layer; the first electron transport layer 112 of the first light-emitting element 110 and the second electron transport layer 122 of the second light-emitting element 120 can be arranged in the same layer. It should be noted that the first hole injection layer 115 and the second hole injection layer 125 can have different thicknesses according to actual conditions; the first hole transport layer 114 and the second hole transport layer 124 can have different thicknesses according to actual conditions.

[0063] For example, since the first anode 116 and the second anode 126 may be made of the same material, the first anode 116 and the second anode 126 may be formed by patterning the same conductive layer.

[0064] For example, the base substrate 101 may be a transparent substrate, such as a glass substrate, a quartz substrate, a plastic substrate, etc. The base substrate 101 may also be a flexible transparent substrate, such as a polyethylene terephthalate (PET) substrate.

[0065] For example, in some examples, such as Figure 1As shown, the light emitting structure 100 further includes a third light emitting element 130; the third light emitting element 130 includes a third light emitting layer 131, a third electron transport layer 132 and a third cathode 133. The third cathode 133 is arranged in contact with the third electron transport layer 132, the conduction band bottom energy level of the third light emitting layer 131 is greater than the conduction band bottom energy level of the first light emitting layer 111, and less than the conduction band bottom energy level of the second light emitting layer 121, the conduction band bottom energy level of the third electron transport layer 132 is less than the conduction band bottom energy level of the first electron transport layer 112, and the conduction band bottom energy level of the third electron transport layer 132 is greater than the conduction band bottom energy level of the second electron transport layer 122.

[0066] In the light-emitting structure provided in this example, different light-emitting elements (for example, the first light-emitting element and the second light-emitting element) use electron transport layers of different materials. Since the conduction band bottom energy level of the third light-emitting layer 131 is greater than the conduction band bottom energy level of the first light-emitting layer 111, and less than the conduction band bottom energy level of the second light-emitting layer 121, that is, the conduction band bottom energy level of the third light-emitting layer 131 is between the first light-emitting layer 111 and the second light-emitting layer 121, the difficulty of electrons from the third electron transport layer 132 to the third light-emitting layer 131 is also between the difficulty of electrons from the first electron transport layer 112 to the first light-emitting layer 111 and the difficulty of electrons from the second electron transport layer 122 to the second light-emitting layer 121. At this time, since the conduction band bottom energy level of the third electron transport layer 132 is less than the conduction band bottom energy level of the first electron transport layer 112, and greater than the conduction band bottom energy level of the second electron transport layer When the Fermi levels of the first cathode 113, the second cathode 123 and the third cathode 133 are approximately the same, the potential barrier for electrons from the third cathode 133 to the third transport layer 132 is smaller than the potential barrier for electrons from the first cathode 113 to the first electron transport layer 112, and is larger than the potential barrier for electrons from the second cathode 123 to the second electron transport layer 122, thereby reducing the efficiency of electron injection into the third light-emitting layer 131 to a certain extent, thereby achieving a balance with the hole injection efficiency in the third light-emitting layer 131, and further improving the luminous efficiency and stability of the first light-emitting element 110, the second light-emitting element 120 and the third light-emitting element 130 at the same time.

[0067] For example, in some examples, the first cathode 113, the second cathode 123, and the third cathode 133 are the same conductive layer, that is, the first light-emitting element 110, the second light-emitting element 120, and the third light-emitting element 130 share a cathode layer. The potential barrier of electrons from the third cathode 133 to the third electron transport layer 132 is greater than the potential barrier of electrons from the second cathode 123 to the second electron transport layer 122, and is less than the potential barrier of electrons from the first cathode 113 to the first electron transport layer 112.

[0068] Figure 5 FIG. 1 is a schematic diagram of energy levels of different light-emitting layers and different electron transport layers in another light-emitting structure provided according to an embodiment of the present disclosure. Figure 5As shown, the conduction band bottom energy level of the first light-emitting layer 111 is less than the conduction band bottom energy level of the first electron transport layer 112, the conduction band bottom energy level of the second light-emitting layer 121 is greater than the conduction band bottom energy level of the second electron transport layer 122, and the conduction band bottom energy level of the third light-emitting layer 131 is slightly greater than the conduction band bottom energy level of the third electron transport layer 132. In other words, there is no or almost no potential barrier for electrons from the first electron transport layer 112 to the first light-emitting layer 111, and electrons need to cross a larger potential barrier (relative to the third light-emitting element) from the second electron transport layer 122 to the second light-emitting layer 121, and electrons need to cross a smaller potential barrier from the third electron transport layer 132 to the third light-emitting layer 131. At this time, the potential barrier for electrons from the first cathode 113 to the first electron transport layer 112 is large, there is no or almost no potential barrier for electrons from the second cathode 123 to the second electron transport layer 122, and the potential barrier for electrons from the third cathode 133 to the third electron transport layer 132 is small. Thus, the light-emitting structure can significantly improve and reduce the electron injection efficiency of electrons from the first cathode 113 to the first light-emitting layer 111, slightly reduce the electron injection efficiency of electrons from the third cathode 133 to the third light-emitting layer 131, and improve the electron injection efficiency of electrons from the second cathode 123 to the second light-emitting layer 121, thereby simultaneously balancing the hole-electron injection efficiency in the first light-emitting layer 111, the second light-emitting layer 121 and the third light-emitting layer 131, thereby improving the luminescence efficiency and stability of the light-emitting structure.

[0069] For example, in some examples, the first electron transport layer 112 includes ZnMgO nanoparticles, the second electron transport layer 122 includes ZnO nanoparticles or ZnMgO nanoparticles, the third electron transport layer 132 includes ZnMgO nanoparticles, and the molar percentage of Mg in the third electron transport layer 132 is less than the molar percentage of Mg in the first electron transport layer 112 and greater than the molar percentage of Mg in the second electron transport layer 122.

[0070] For example, in some examples, the molar percentage of Mg in the first electron transport layer 112 is 10%-20%, the molar percentage of Mg in the second electron transport layer 122 is less than 5%, and the molar percentage of Mg in the third electron transport layer 132 is 5%-10%. It should be noted that when the second electron transport layer 122 is ZnO nanoparticles, the second electron transport layer 122 can be considered to be ZnMgO nanoparticles with a molar percentage of Mg of 0.

[0071] Table 2 is an energy level data table of another electron transport layer provided according to an embodiment of the present disclosure. In Table 2, the first electron transport layer 112 is ZnMgO nanoparticles with a molar percentage of Mg of 15%, the second electron transport layer 122 is ZnMgO nanoparticles with a molar percentage of Mg of 0%, and the third electron transport layer 132 is ZnMgO nanoparticles with a molar percentage of Mg of 5%. It can be seen that the conduction band bottom energy level of the first electron transport layer 112 is greater than the conduction band bottom energy level of the third electron transport layer 132, and the conduction band bottom energy level of the third electron transport layer 132 is greater than the conduction band bottom energy level of the second electron transport layer 122. When the Fermi levels of the first cathode 113, the second cathode 123 and the third cathode 133 are in the range of -4.3 to -4.2 eV, the difference between the bottom energy level of the conduction band of the first electron transport layer 112 and the Fermi level of the first cathode 113 is approximately 0.37-0.47 eV, the difference between the bottom energy level of the conduction band of the second electron transport layer 122 and the Fermi level of the second cathode 123 is less than 0.1 eV, and the difference between the bottom energy level of the conduction band of the third electron transport layer 132 and the Fermi level of the third cathode 133 is less than 0.2 eV. Thus, the light-emitting structure can reduce the efficiency of electron injection into the first light-emitting layer 111 to a certain extent, thereby achieving a balance with the hole injection efficiency in the first light-emitting layer 111, improve the efficiency of electron injection into the second light-emitting layer 121 to a certain extent, thereby achieving a balance with the hole injection efficiency in the second light-emitting layer 121, and reduce the efficiency of electron injection into the third light-emitting layer 131 to a certain extent, thereby achieving a balance with the hole injection efficiency in the third light-emitting layer 131.

[0072]

[0073] Table 2 - Energy level data table of electron transport layer

[0074] For example, in some examples, the electron mobility of the third electron transport layer 132 is greater than the electron mobility of the second electron transport layer 122, and less than the electron mobility of the second electron transport layer 112. Therefore, the light-emitting structure can further significantly improve and reduce the electron injection efficiency of electrons from the first cathode 113 to the first light-emitting layer 111, slightly reduce the electron injection efficiency of electrons from the third cathode 133 to the third light-emitting layer 131, and improve the electron injection efficiency of electrons from the second cathode 123 to the second light-emitting layer 121, thereby simultaneously balancing the hole-electron injection efficiency in the first light-emitting layer 111, the second light-emitting layer 121, and the third light-emitting layer 131, thereby improving the light-emitting efficiency and stability of the light-emitting structure.

[0075] For example, when the first electron transport layer 112 is ZnMgO nanoparticles with a molar percentage of Mg of 15%, the second electron transport layer 122 is ZnMgO nanoparticles with a molar percentage of Mg of 0%, and the third electron transport layer 132 is ZnMgO nanoparticles with a molar percentage of Mg of 5%, the electron mobility of the third electron transport layer 132 is greater than the electron mobility of the second electron transport layer 122, and less than the electron mobility of the second electron transport layer 112.

[0076] For example, in some examples, the first light-emitting layer may be a red quantum dot light-emitting layer, the second light-emitting layer may be a blue quantum dot light-emitting layer, and the third light-emitting layer may be a green quantum dot light-emitting layer; the first light-emitting layer may use red cadmium-free quantum dot light-emitting materials, such as indium phosphide (InP), such as InP / ZnS core-shell quantum dot materials; the second light-emitting layer may use blue quantum dot light-emitting materials, such as cadmium selenide (CdSe), such as CdSe / ZnS core-shell quantum dot materials; the third light-emitting layer may use green cadmium-free quantum dot light-emitting materials, such as indium phosphide (InP), such as InP / ZnS core-shell quantum dot materials.

[0077] For example, in some examples, such as Figure 1 As shown, the third light-emitting element 130 further includes a third hole transport layer 134, a third hole injection layer 135 and a third anode 136. The third hole transport layer 134 is arranged on a side of the third light-emitting layer 131 away from the third electron transport layer 132, the third hole injection layer 135 is arranged on a side of the third hole transport layer 134 away from the third light-emitting layer 131, and the third anode 136 is arranged on a side of the third hole injection layer 135 away from the third hole transport layer 134.

[0078] For example, the third anode 136 may be made of a transparent conductive oxide or a conductive polymer, and the transparent conductive oxide may be indium tin oxide (ITO), FTO (SnO2), etc. In addition, the materials of the third hole transport layer 134 and the third hole injection layer 135 may be selected according to actual conditions, and the embodiments of the present disclosure are not limited thereto.

[0079] For example, in some examples, such as Figure 1As shown, the first light emitting element 110 , the second light emitting element 120 and the third light emitting element 130 may be disposed on the base substrate 101 in the same layer. That is to say, the first anode 116 of the first light-emitting element 110, the second anode 126 of the second light-emitting element 120 and the third anode 136 of the third light-emitting element 130 can be arranged in the same layer; the first hole injection layer 115 of the first light-emitting element 110, the second hole injection layer 125 of the second light-emitting element 120 and the third hole injection layer 135 of the third light-emitting element 130 can be arranged in the same layer; the first hole transport layer 114 of the first light-emitting element 110, the second hole transport layer 124 of the second light-emitting element 120 and the third hole transport layer 134 of the third light-emitting element 130 can be arranged in the same layer; the first light-emitting layer 111 of the first light-emitting element 110, the second light-emitting layer 121 of the second light-emitting element 120 and the third light-emitting layer 131 of the third light-emitting element 130 can be arranged in the same layer; the first electron transport layer 112 of the first light-emitting element 110, the second electron transport layer 122 of the second light-emitting element 120 and the third electron transport layer 132 of the third light-emitting element 130 can be arranged in the same layer. It should be noted that the first hole injection layer 115, the second hole injection layer 125 and the third hole injection layer 135 can have different thicknesses according to actual conditions; the first hole transport layer 114, the second hole transport layer 124 and the third hole transport layer 134 can have different thicknesses according to actual conditions.

[0080] For example, since the first anode 116 , the second anode 126 , and the third anode 127 may be made of the same material, the first anode 116 , the second anode 126 , and the third anode 137 may be formed by patterning the same conductive layer.

[0081] For example, the base substrate 101 may be a transparent substrate, such as a glass substrate, a quartz substrate, a plastic substrate, etc. The base substrate 101 may also be a flexible transparent substrate, such as a polyethylene terephthalate (PET) substrate.

[0082] For example, Figure 1 As shown, the light-emitting structure 100 also includes a pixel defining layer 180 located between different light-emitting elements (for example, between the first light-emitting element 110 and the second light-emitting element 120, between the second light-emitting element 120 and the third light-emitting element 130, and between the third light-emitting element 130 and the first light-emitting element 110).

[0083] At least one embodiment of the present disclosure provides a method for manufacturing a light emitting structure, which includes the following steps S201-S205.

[0084] Step S201: forming a first anode, a second anode and a third anode on a base substrate.

[0085] For example, a deposition method may be used to form an anode layer on a substrate, and then the anode layer may be patterned to form a first anode, a second anode, and a third anode; the substrate may be a transparent substrate, such as a glass substrate, a quartz substrate, a plastic substrate, etc.; the anode layer may be made of a transparent conductive oxide or a conductive polymer, and the transparent conductive oxide may be indium tin oxide (ITO), FTO (SnO 2 )wait.

[0086] Step S202: forming a first hole injection layer, a second hole injection layer and a third hole injection layer respectively on the side of the first anode, the second anode and the third anode away from the substrate.

[0087] For example, the first hole injection layer, the second hole injection layer and the third hole injection layer can be formed on the side of the first anode, the second anode and the third anode away from the substrate by inkjet printing or nanoimprinting. The materials of the first hole injection layer, the second hole injection layer and the third hole injection layer can be organic hole injection materials, such as PEDOT:PSS (poly (3,4-ethylenedioxythiophene) - polystyrene sulfonic acid), or inorganic oxides, such as molybdenum oxide (MoOx).

[0088] Step S203: forming a first hole transport layer, a second hole transport layer and a third hole transport layer respectively on the sides of the first hole injection layer, the second hole injection layer and the third hole injection layer away from the substrate.

[0089] For example, the first hole transport layer, the second hole transport layer and the third hole transport layer may be organic hole transport materials, such as PVK (polyvinyl carbazole), TFB (poly (9,9-dioctylfluorene-CO-N-(4-butylphenyl) diphenylamine)) and TPD (N,N'-diphenyl-N,N'-bis (3-methyllphenyl) -(1,1'-biphenyl) -4,4'-diamine) and their derivatives, or inorganic hole transport materials, such as nickel oxide (NiOx) and vanadium oxide (VOx).

[0090] Step S204: forming a first light-emitting layer, a second light-emitting layer and a third light-emitting layer respectively on the side of the first hole transport layer, the second hole transport layer and the third hole transport layer away from the base substrate.

[0091] Step S205: forming a first electron transport layer, a second electron transport layer and a third electron transport layer respectively on the side of the first light-emitting layer, the second light-emitting layer and the third light-emitting layer away from the substrate.

[0092] For example, the first electron transport layer is ZnMgO nanoparticles with a Mg molar percentage of 10%-20%, the second electron transport layer is ZnMgO nanoparticles with a Mg molar percentage of less than 5%, and the third electron transport layer is ZnMgO nanoparticles with a Mg molar percentage of 5%-10%.

[0093] Step S206: forming a cathode layer on the side of the first electron transport layer, the second electron transport layer and the third electron transport layer away from the substrate.

[0094] For example, a cathode layer may be formed on the side of the first electron transport layer, the second electron transport layer and the third electron transport layer away from the substrate by evaporation; the material of the cathode layer may be aluminum or silver; and the thickness of the cathode layer may be in the range of 100-150 nanometers.

[0095] At least one embodiment of the present disclosure further provides a display panel. The display panel includes a plurality of light-emitting structures 100 arranged in an array, and the light-emitting structure is the light-emitting structure provided in the above-mentioned embodiment. Thus, the display panel can appropriately reduce the electron injection efficiency of the first light-emitting element and match the hole injection efficiency of the first light-emitting element, thereby improving the luminous efficiency and stability of the first light-emitting element. Moreover, when the display panel adopts the light-emitting structure in which different light-emitting elements adopt different electron transport layers in the above-mentioned embodiment, the display panel can simultaneously improve the luminous efficiency and stability of the first light-emitting element, the second light-emitting element and the third light-emitting element. For details, please refer to the specific description of the embodiment of the light-emitting structure.

[0096] At least one embodiment of the present disclosure further provides a display device, including the display panel provided by the above embodiment. Thus, the display panel can appropriately reduce the electron injection efficiency of the first light-emitting element and match the hole injection efficiency of the first light-emitting element, thereby improving the luminous efficiency and stability of the first light-emitting element. Moreover, when the display panel adopts the light-emitting structure in which different light-emitting elements adopt different electron transport layers in the above embodiment, the display panel can simultaneously improve the luminous efficiency and stability of the first light-emitting element, the second light-emitting element and the third light-emitting element. For details, please refer to the specific description of the embodiment of the light-emitting structure.

[0097] For example, in some examples, the display device may be any product or component with a display function, such as a smart phone, a tablet computer, a television, a monitor, a laptop computer, a digital photo frame, a navigator, or the like.

[0098] There are a few points to note:

[0099] (1) In the drawings of the embodiments of the present disclosure, only the structures related to the embodiments of the present disclosure are involved, and other structures can refer to the general design.

[0100] (2) In the absence of conflict, features in the same embodiment or in different embodiments of the present disclosure may be combined with each other.

[0101] The above are only specific embodiments of the present disclosure, but the protection scope of the present disclosure is not limited thereto. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in the present disclosure, which should be included in the protection scope of the present disclosure. Therefore, the protection scope of the present disclosure should be based on the protection scope of the claims.

Claims

1. A light-emitting structure, comprising: substrate substrate; The first light-emitting element is located on the substrate and includes a first light-emitting layer, a first electron transport layer and a first cathode. The first cathode is arranged in contact with the first electron transport layer, the conduction band bottom energy level of the first electron transport layer is greater than the Fermi level of the first cathode, and the difference between the conduction band bottom energy level of the first electron transport layer and the Fermi level of the first cathode is in the range of 0.3-0.6 eV. The conduction band bottom energy level of the first light emitting layer is lower than the conduction band bottom energy level of the first electron transport layer. The first electron transport layer comprises ZnMgO nanoparticles. The molar percentage of Mg in the first electron transport layer is 10%-20%.

2. The light emitting structure according to claim 1, wherein: The molar percentage of Mg in the first electron transport layer is 13%-16%.

3. The light emitting structure according to claim 1, wherein: The material of the first light-emitting layer includes red cadmium-free quantum dot material.

4. The light emitting structure according to claim 3, wherein: The material of the first light emitting layer includes indium phosphide.

5. The light emitting structure according to claim 1, further comprising: The second light-emitting element includes a second light-emitting layer, a second electron transport layer, and a second cathode, Among them, the second cathode is arranged in contact with the second electron transport layer, the conduction band bottom energy level of the first light-emitting layer is lower than the conduction band bottom energy level of the second light-emitting layer, and the conduction band bottom energy level of the first electron transport layer is higher than the conduction band bottom energy level of the second electron transport layer.

6. The light emitting structure according to claim 5, wherein: A potential barrier for electrons from the first cathode to the first electron transport layer is greater than a potential barrier for electrons from the second cathode to the second electron transport layer.

7. The light emitting structure according to claim 5, wherein: The conduction band bottom energy level of the first light-emitting layer is lower than the conduction band bottom energy level of the first electron transport layer, the conduction band bottom energy level of the second light-emitting layer is higher than the conduction band bottom energy level of the second electron transport layer, and the Fermi level of the second cathode is approximately equal to the conduction band bottom energy level of the second electron transport layer.

8. The light emitting structure according to any one of claims 5 to 7, wherein: The second electron transport layer includes ZnO nanoparticles or ZnMgO nanoparticles, and the molar percentage of Mg in the first electron transport layer is greater than the molar percentage of Mg in the second electron transport layer.

9. The light emitting structure according to claim 8, wherein: The molar percentage of Mg in the second electron transport layer is less than 5%.

10. The light emitting structure according to any one of claims 5 to 7, wherein: At least one of the first light-emitting layer and the second light-emitting layer is a quantum dot light-emitting layer, and the first cathode and the second cathode are the same conductive layer.

11. The light emitting structure according to any one of claims 5 to 7, further comprising: A third light-emitting element includes a third light-emitting layer, a third electron transport layer and a third cathode, Among them, the third cathode is arranged in contact with the third electron transport layer, the conduction band bottom energy level of the third light-emitting layer is greater than the conduction band bottom energy level of the first light-emitting layer and less than the conduction band bottom energy level of the second light-emitting layer, the conduction band bottom energy level of the third electron transport layer is less than the conduction band bottom energy level of the first electron transport layer, and the conduction band bottom energy level of the third electron transport layer is greater than the conduction band bottom energy level of the second electron transport layer.

12. The light emitting structure according to claim 11, wherein: A potential barrier for electrons from the third cathode to the third electron transport layer is greater than a potential barrier for electrons from the second cathode to the second electron transport layer, and is smaller than a potential barrier for electrons from the first cathode to the first electron transport layer.

13. The light emitting structure according to claim 11, wherein: The second electron transport layer includes ZnO nanoparticles or ZnMgO nanoparticles, the third electron transport layer includes ZnMgO nanoparticles, and the molar percentage of Mg in the third electron transport layer is less than the molar percentage of Mg in the first electron transport layer and greater than the molar percentage of Mg in the second electron transport layer.

14. The light emitting structure according to claim 13, wherein: The molar percentage of Mg in the second electron transport layer is less than 5%, and the molar percentage of Mg in the third electron transport layer is 5%-10%.

15. The light emitting structure according to any one of claims 5 to 7, wherein: The electron mobility of the first electron transport layer is smaller than the electron mobility of the second electron transport layer.

16. The light emitting structure according to claim 11, wherein: The electron mobility of the third electron transport layer is greater than the electron mobility of the second electron transport layer, and is less than the electron mobility of the second electron transport layer.

17. The light emitting structure according to any one of claims 5 to 7, wherein: The first light-emitting layer is configured to emit red light, and the second light-emitting layer is configured to emit blue light.

18. A display panel comprising a plurality of light emitting structures arranged in an array, in, Each of the light-emitting structures is a light-emitting structure according to any one of claims 1-17.

19. A display device comprising the display panel according to claim 18.

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