Light-emitting device and display panel

Abstract

The present application provides a light-emitting device and a display panel. The light-emitting device includes a light-emitting layer, a hole transport layer, and a light-assisting layer. The light-assisting layer is located between the light-emitting layer and the hole transport layer. The light-assisting layer comprises a mixed material layer of a hole transport material and a light-assisting material. The light-assisting layer is disposed between the light-emitting layer and the hole transport layer of the light-emitting device. By providing the light-assisting layer with a mixed material layer of a hole transport material and a light-assisting material, the large amount of carriers accumulated at the adjacent interface of the light-emitting layer and the hole transport layer in existing light-emitting devices is reduced or eliminated.

Description

Technical Field

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

[0002] Organic Light-Emitting Diode (OLED) is an organic thin-film electroluminescent device that is widely used in display panels due to its advantages such as simple preparation process, low cost and flexible display.

[0003] However, due to limitations of their own materials or structures, the light-emitting devices in current display panels may produce ghosting when the display panel switches between screens, such as switching from a black screen to a low-grayscale screen, thereby affecting display quality. Summary of the Invention

[0004] In view of this, the present application provides a light-emitting device and a display panel, in which a light-emitting auxiliary layer is arranged between the light-emitting layer and the hole transport layer of the light-emitting device. By utilizing the hole transport material and the light-emitting auxiliary material in the light-emitting auxiliary layer, a large number of carriers accumulated at the adjacent interface of the existing light-emitting device due to the adjacent light-emitting layer and the hole transport layer are reduced or eliminated, thereby reducing the capacitance of the light-emitting device, which is beneficial to improving the smear phenomenon and improving the display quality.

[0005] In a first aspect, the present application provides a light-emitting device comprising a light-emitting layer, a hole transport layer, and a light-assisting layer. The light-assisting layer is located between the light-emitting layer and the hole transport layer. The light-assisting layer comprises a mixed material layer of a hole transport material and a light-assisting material.

[0006] In the above scheme, by setting a light-emitting auxiliary layer including a mixed material layer of hole transport material and light-emitting auxiliary material, a transition structure for carrier transport is formed between the light-emitting layer and the hole transport layer, which is beneficial to reducing or eliminating the carriers accumulated at the adjacent interface of the existing light-emitting device due to the adjacent light-emitting layer and the hole transport layer, thereby reducing the capacitance of the light-emitting device, improving the ghosting phenomenon, and improving the display quality.

[0007] In a specific embodiment of the first aspect of the present application, the mixed material layer includes a first side facing the light-emitting layer and a second side facing the hole transport layer. Along the direction from the second side to the first side, the doping ratio of the hole transport material gradually decreases according to a first preset gradient rule, and / or the doping ratio of the light-emitting auxiliary material gradually increases according to a second preset gradient rule.

[0008] In the above scheme, this doping gradient method is used to gradually blur the interface between the light-emitting layer and the hole transport layer, so that the carrier transmission rate gradually changes, thereby reducing or eliminating to a greater extent the carriers accumulated at the adjacent interface between the existing light-emitting layer and the hole transport layer, thereby reducing the capacitance of the light-emitting device.

[0009] In a specific embodiment of the first aspect of the present application, the first preset variation rule includes a step-by-step decrease, a linear decrease, an arc-shaped decrease or an S-shaped decrease, and / or the second preset variation rule includes a step-by-step increase, a linear increase, an arc-shaped increase or an S-shaped increase.

[0010] In a specific embodiment of the first aspect of the present application, in the mixed material layer, the ratio between the total doping amount of the hole transport material and the total doping amount of the luminescence auxiliary material is in the range of 2:1 to 1:2.

[0011] In a specific embodiment of the first aspect of the present application, the light-emitting auxiliary layer further includes a first sub-film layer. The first sub-film layer is located between the mixed material layer and the hole transport layer. The material of the first sub-film layer is all hole transport material.

[0012] In a specific embodiment of the first aspect of the present application, the luminescence-assisting layer further includes a second sub-film layer. The second sub-film layer is located between the mixed material layer and the luminescence layer. The material of the second sub-film layer is all luminescence-assisting material.

[0013] In a specific embodiment of the first aspect of the present application, the thickness of the mixed material layer is greater than or equal to the thickness of the first sub-film layer. Further, the thickness of the first sub-film layer is not less than

[0014] In a specific embodiment of the first aspect of the present application, the highest occupied molecular orbital of the material of the light-emitting auxiliary layer facing the light-emitting layer matches the highest occupied molecular orbital of the light-emitting host material of the light-emitting layer. Furthermore, the difference between the highest occupied molecular orbital of the material of the light-emitting auxiliary layer facing the light-emitting layer and the highest occupied molecular orbital of the light-emitting host material of the light-emitting layer is no greater than 0.2 eV.

[0015] In a specific embodiment of the first aspect of the present application, the light-emitting device further includes: an anode and a cathode, and at least one of a hole injection layer, a hole blocking layer, an electron transport layer and an electron injection layer arranged between the anode and the cathode.

[0016] A second aspect of the present application provides a display panel, which may include a light-emitting device as described in any specific embodiment of the first aspect. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1Shown is a schematic structural diagram of a light-emitting device provided in one embodiment of the present application.

[0018] Figure 2 Shown is a schematic structural diagram of a light-emitting device provided in another embodiment of the present application.

[0019] Figure 3 Shown is a schematic structural diagram of a light-emitting device provided in yet another embodiment of the present application.

[0020] Figure 4 Shown is a schematic structural diagram of a light-emitting device provided in yet another embodiment of the present application.

[0021] Figure 5 Shown is a schematic structural diagram of a light-emitting device provided in yet another embodiment of the present application.

[0022] Figure 6 Shown is a schematic structural diagram of a light-emitting device provided in yet another embodiment of the present application.

[0023] Figure 7A The figure shows a schematic diagram of the change in the doping ratio of the hole transport material and the light-emitting auxiliary material in each film layer of the light-emitting auxiliary layer provided in one embodiment of the present application.

[0024] Figure 7B The figure shows a schematic diagram of the change in the doping ratio of the hole transport material and the luminescence auxiliary material in each film layer of the luminescence auxiliary layer provided by another embodiment of the present application.

[0025] Figure 7C The figure shows a schematic diagram of the change in the doping ratio of the hole transport material and the luminescence auxiliary material in each film layer of the luminescence auxiliary layer provided in another embodiment of the present application.

[0026] Figure 7D The figure shows a schematic diagram of the change in the doping ratio of the hole transport material and the luminescence auxiliary material in each film layer of the luminescence auxiliary layer provided in another embodiment of the present application.

[0027] Figure 8 FIG2 is a schematic diagram of an evaporation device used to prepare a light-emitting auxiliary layer according to an embodiment of the present application.

[0028] Figure 9 Schematic diagram showing the energy level relationship of each film layer in a light-emitting device provided in one embodiment of the present application. DETAILED DESCRIPTION

[0029] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0030] The display panel based on the organic light-emitting diode (OLED) is driven by current, and the brightness of the light-emitting device in the display panel is determined by the magnitude of the current passing through. The light-emitting layer and the hole transport layer in the light-emitting device are usually directly adjacent. Assuming that the grayscale range of the display panel is 0 to 255, when the display panel switches from a black screen (for example, a screen corresponding to a grayscale of 0) to a low grayscale screen (for example, a screen corresponding to a grayscale range of 1 to 64), due to the low driving current under the low grayscale screen and the different materials of the hole transport layer and the light-emitting layer, the sudden change of the material at the interface between the hole transport layer and the light-emitting layer will cause serious accumulation of carriers such as holes and electrons, thereby causing the light-emitting device to have a large capacitance, which will in turn cause the first frame brightness of the light-emitting device to be low. In addition, if the proportion of the low first frame brightness of light-emitting devices of different colors in the display panel is different, the display panel will produce color deviation, which will cause the display panel to have a ghosting phenomenon.

[0031] In one method, the capacitance of the light emitting device is reduced by reducing the aperture ratio of the light emitting device. However, the reduction in the aperture ratio in this method may result in a reduction in the life of the light emitting device.

[0032] In another method, the brightness of the light-emitting device in the first frame is increased by increasing the reference voltage Vref corresponding to the light-emitting device. However, this method may easily cause current crosstalk between adjacent light-emitting devices.

[0033] In view of this, at least one embodiment of the present application provides a light-emitting device and a display panel that can at least solve the above-mentioned problems. The present application sets a light-emitting auxiliary layer between the light-emitting layer and the hole transport layer of the light-emitting device. By setting the light-emitting auxiliary layer to include a mixed material layer of hole transport material and light-emitting auxiliary material, a transition structure for carrier transport is formed between the light-emitting layer and the hole transport layer using the mixed material layer, which is beneficial to reducing or eliminating the carriers accumulated at the adjacent interfaces of the existing light-emitting layer and the hole transport layer, thereby reducing the capacitance of the light-emitting device, improving the smear phenomenon, and improving the display quality. In addition, since the technical solution of the present application does not reduce the aperture ratio corresponding to the light-emitting device and does not increase the Vref corresponding to the light-emitting device, it will not lead to a decrease in the life of the light-emitting device and will not cause current crosstalk between adjacent light-emitting devices.

[0034] The following describes a light-emitting device and a display panel according to at least one embodiment of the present application, with reference to the accompanying drawings. Furthermore, in these drawings, a spatial rectangular coordinate system is established with reference to the plane of the display panel to assist in explaining the positional relationship between the light-emitting device and the various film layers in the display panel. In this spatial rectangular coordinate system, the X-axis is parallel to the plane of the display panel, the Y-axis is perpendicular to the plane of the display panel, and "thickness" is defined with reference to the hole transport layer. For example, for an object located on one side of the hole transport layer, the difference between the perpendicular distance from the end of the object farthest from the hole transport layer to the hole transport layer and the perpendicular distance from the end of the object closest to the hole transport layer to the hole transport layer is the thickness of the object.

[0035] At least one embodiment of the present application provides a light emitting device. Figures 1 to 6 The light-emitting device 100 includes a light-emitting layer 110, a hole transport layer 120 and a light-emitting auxiliary layer 130. The light-emitting auxiliary layer 130 is located between the light-emitting layer 110 and the hole transport layer 120. The light-emitting auxiliary layer 130 includes a mixed material layer 131 of hole transport material a and light-emitting auxiliary material b. In this way, a light-emitting auxiliary layer is provided between the light-emitting layer and the hole transport layer of the light-emitting device. By providing the light-emitting auxiliary layer including a mixed material layer of hole transport material and light-emitting auxiliary material, a transition structure for carrier transport is formed between the light-emitting layer and the hole transport layer using the mixed material layer, which is beneficial to reducing or eliminating the carriers accumulated at the adjacent interface where the existing light-emitting layer and the hole transport layer are directly adjacent, thereby reducing the capacitance of the light-emitting device, improving the smear phenomenon, and improving the display quality.

[0036] It should be noted that Figures 1 to 6 In the figure, the thickness of the light-emitting layer 110, the thickness of the hole transport layer 120, and the thickness of the light-emitting auxiliary layer 130 are merely illustrative. For example, the thickness of the light-emitting auxiliary layer 130 may be smaller than the thickness of the light-emitting layer 110 or the thickness of the hole transport layer 120. The material of the light-emitting layer 110 may include a light-emitting host material (Host material) and a light-emitting dopant material (Dopant material), and may further include a light-emitting auxiliary material (Prime material). Figures 1 to 6 In the figure, for example, the hole transport material a is represented by a small black dot, and the luminescence auxiliary material b is represented by a small black triangle, which is not used to limit the number and shape of the hole transport material a and the luminescence auxiliary material b.

[0037] The luminescent auxiliary layer 130 can simultaneously assist hole transport and block electron transport, and the luminescent auxiliary layer 130 can further reduce or eliminate the carriers accumulated at the adjacent interface between the existing luminescent layer 110 and the hole transport layer 120. The hole transporting material (HTM) is a material with hole transport properties, for example, it can be an aromatic amine derivative. The luminescent auxiliary material is a material with both electron blocking properties and hole transport properties, for example, it can be a carbazole or aromatic amine derivative. The luminescent auxiliary layer 130 can be a method of co-evaporation using the hole transport material a and the luminescent auxiliary material b as evaporation sources (reference Figure 8 ), or the hole transport material a and the luminescent auxiliary material b may be mixed first and then evaporated to form the mixture, or other methods may be used.

[0038] Below, the mixing method of the mixed material layer 131 provided in at least one embodiment of the present application is described with examples.

[0039] In at least one embodiment of the present application, illustratively, reference is made to Figures 2 to 6 , the mixed material layer 131 includes a first side 1 facing the light-emitting layer 110 and a second side 2 facing the hole transport layer 120. Along the direction from the second side 2 to the first side 1 (that is, along the positive direction of the Y-axis), the doping ratio of the hole transport material a gradually decreases according to a first preset gradient rule, and / or the doping ratio of the light-emitting auxiliary material b gradually increases according to a second preset gradient rule. In this way, if the doping ratio of the hole transport material a gradually decreases along the direction from the second side 2 to the first side 1, the accumulation of holes caused at the interface where the doping ratio of the hole transport material a changes too much during the hole transmission process can be avoided. If the doping ratio of the light-emitting auxiliary material b gradually increases along the direction from the second side 2 to the first side 1, the accumulation of electrons caused at the interface where the doping ratio of the light-emitting auxiliary material b changes too much during the electron transmission process can be avoided. By setting the doping ratio of the hole transport material a and / or the light-emitting auxiliary material b to gradually change, the interface between the light-emitting layer and the hole transport layer is gradually blurred in this doping gradient manner, so that the carrier transmission rate gradually changes, thereby reducing or eliminating the accumulated carriers between the existing light-emitting layer and the hole transport layer to a greater extent, thereby reducing the capacitance of the light-emitting device.

[0040] It should be noted that the doping ratio of the hole transport material a and / or the light-emitting auxiliary material b gradually changes along the direction from the second side 2 to the first side 1. The light-emitting auxiliary layer 130 can be divided into multiple film layers of equal or unequal thickness along the direction from the second side 2 to the first side 1, and the doping ratio of the hole transport material a in the multiple film layers of equal or unequal thickness gradually becomes smaller, and / or the doping ratio of the light-emitting auxiliary material b gradually becomes larger.

[0041] The doping ratio may be a mass doping ratio, a thickness doping ratio, or other types of doping ratios. In order to gradually change the doping ratio of the hole transport material a and / or the luminescence-assisting material b, in some embodiments, the doping ratio of the hole transport material a and / or the luminescence-assisting material b may be adjusted by adjusting the height of the angle limiting plate of the evaporation source and the distance between the angle limiting plate and the evaporation source. In other embodiments, the hole transport material a and the luminescence-assisting material b may be first mixed at different doping ratios to obtain a plurality of mixed materials, and then the plurality of mixed materials may be separately evaporated.

[0042] Taking the thickness doping ratio as an example, the thickness doping ratio can be understood as the ratio of the thickness of the hole transport material a or the light-emitting auxiliary material b that can be formed to the thickness corresponding to the same thickness range on the light-emitting auxiliary layer 130. For example, assuming that the thickness corresponding to the same thickness range is The thickness of the hole transport material a is 90% doping ratio, so the thickness of the hole transport material a can be formed to be Other materials such as light-emitting auxiliary material b can be formed to a thickness of It can be called Angstrom,

[0043] In at least one embodiment of the present application, the first preset gradual change rule includes a step-by-step decrease (refer to Figure 7A ), linearly decreasing (reference Figure 7B ), arc-shaped decrease (reference Figure 7C ) or S-shaped decrease (reference Figure 7D ), and / or, the second preset gradual change rule includes a step-by-step increase (reference Figure 7A ), linear increase (reference Figure 7B ), arc-shaped increase (reference Figure 7C ) or S-shaped increase (reference Figure 7D In this way, the gradual change in the doping ratio of the hole transport material a and / or the light-emitting auxiliary material b is slow, and the interface between the light-emitting layer and the hole transport layer becomes further blurred, which is beneficial to reducing or eliminating the carriers accumulated at the interface when the existing light-emitting layer and the hole transport layer are adjacent.

[0044] It should be noted that the type of preset transition rule can be as follows: Figure 7A As shown, it changes gradually in a step-by-step manner, or it can be as follows Figures 7B to 7D The type of the first preset gradual change rule and the type of the second preset gradual change rule can be the same, for example, both are step-shaped, linear, arc-shaped or S-shaped, etc., or they can be different, for example, the type of the first preset gradual change rule is step-shaped, and the type of the second preset gradual change rule is S-shaped. The specific design can be based on actual needs.

[0045] In some embodiments, the doping ratio of the hole transport material a to the light-emitting auxiliary material b in the mixed material layer 131 varies in a range of 1:0 to 0:1. For example, the ratios may vary from 0.9:0 to 0:0.9, 0.7:0 to 0:0.9, or 0.6:0 to 0:0.4. This range is not limited to any specific variations as long as they vary gradually.

[0046] In at least one embodiment of the present application, in the mixed material layer 131, the ratio between the total doping amount of the hole transport material a and the total doping amount of the luminescence auxiliary material b is in the range of 2:1 to 1:2. In this way, if the ratio range is too small, the hole transport material a in the luminescence auxiliary layer 130 will be less, and the gradual change of the hole transport material a may be large, resulting in an excessive number of holes at the position where the change of the hole transport material a is large. If the ratio range is too large, the luminescence auxiliary material b in the mixed material layer 131 will be less, and the gradual change of the luminescence auxiliary material b may be large, resulting in an excessive number of electrons at the position where the change of the luminescence auxiliary material b is large. Therefore, by setting the ratio range of the total doping amount of the hole transport material a to the total doping amount of the luminescence auxiliary material b to 2:1 to 1:2, it is beneficial for the doping ratio of the hole transport material a and the doping ratio of the luminescence auxiliary material b to change slowly, effectively avoiding the accumulation of more carriers due to the large change of each material when the ratio range deviates.

[0047] The light-emitting auxiliary layer 130 may be a single film layer (refer to Figures 1 to 3 、 Figure 6 ), or a laminated multilayer film (reference Figure 4 and Figure 5 Hereinafter, the structure of the light-emitting auxiliary layer provided in at least one embodiment of the present application, when the light-emitting auxiliary layer is a stacked multi-layer film layer, will be described by way of example.

[0048] In at least one embodiment of the present application, reference is made to Figure 4The light-emitting auxiliary layer 130 also includes a first sub-film layer 132. The first sub-film layer 132 is located between the mixed material layer 131 and the hole transport layer 120. The material of the first sub-film layer 132 is hole transport material a. In this way, since the material of the hole transport layer 120 is the same as or has similar performance to the hole transport material a, it is beneficial for the highest occupied molecular orbital (HOMO) of the material of the light-emitting auxiliary layer 130 close to the hole transport layer 120 to match the highest occupied molecular orbital of the material of the hole transport layer 120, which will avoid the accumulation of holes at the interface between the hole transport layer 120 and the light-emitting auxiliary layer 130 due to the large difference in materials between the hole transport layer 120 and the light-emitting auxiliary layer 130.

[0049] In at least one embodiment of the present application, reference is made to Figure 5 The luminescence-assisting layer 130 further includes a second sub-layer 133. This second sub-layer 133 is located between the mixed material layer 131 and the luminescent layer 110. The material of the second sub-layer 133 is entirely luminescence-assisting material b. Because the material of the luminescent layer 110 is the same as or has similar properties to that of the luminescence-assisting material b, electrons are prevented from accumulating at the interface between the luminescent layer 110 and the luminescence-assisting layer 130 due to the significant material difference between the two layers.

[0050] In at least one embodiment of the present application, the thickness of the mixed material layer 131 is greater than or equal to the thickness of the first sub-film layer 132. In this way, when the hole transport material a and the light-emitting auxiliary material b in the mixed material layer 131 are gradually doped, it is beneficial to gradually change the doping ratio of the hole transport material a and the thickness of the light-emitting auxiliary material b slowly, thereby improving or avoiding carrier accumulation in the mixed material layer 131 caused by the gradual change of the amplitude being too fast, and further reducing the capacitance of the light-emitting device.

[0051] Furthermore, the thickness of the first sub-layer 132 is not less than In this way, the film-forming property of the first sub-film layer 132 can be ensured, which is beneficial to controlling the thickness of the first sub-film layer 132 in the preparation process of the light-emitting device. At the same time, it is also beneficial to avoid the carrier tunneling effect caused by the thickness of the first sub-film layer 132 being too thin.

[0052] In at least one embodiment of the present application, the highest occupied molecular orbital (HOMO) of the material of the light-emitting auxiliary layer 130 facing the light-emitting layer 110 matches the highest occupied molecular orbital of the light-emitting main material of the light-emitting layer 110, that is, the highest occupied molecular orbital of the material of the light-emitting auxiliary layer 130 facing the light-emitting layer 110 is substantially the same as the highest occupied molecular orbital of the light-emitting main material of the light-emitting layer 110. For example, in some embodiments, with reference to Figure 9 The difference ΔHOMO between the highest occupied molecular orbital of the material of the light-emitting layer 110 on the side of the light-emitting auxiliary layer 130 facing the light-emitting layer 110 and the highest occupied molecular orbital of the light-emitting host material of the light-emitting layer 110 is no greater than 0.2 eV. This helps to further blur the interface between the light-emitting layer 110 and the light-emitting auxiliary layer 130, thereby preventing the accumulation of carriers such as holes at the interface between the light-emitting layer 110 and the light-emitting auxiliary layer 130.

[0053] In at least one specific embodiment of the present application, reference is made to Figure 6 The light emitting device 100 further includes an anode 140 and a cathode 190 , and at least one of a hole injection layer 150 , a hole blocking layer 160 , an electron transport layer 170 and an electron injection layer 180 disposed between the anode 140 and the cathode 190 .

[0054] It should be noted that the hole transport material a can also match the material of the hole injection layer 150, which is beneficial to improving the hole injection efficiency. For example, in some embodiments, the hole transport material a can be made of the same material as the material of the hole injection layer 150, so that the highest occupied molecular orbital difference between the hole transport material a and the material of the hole injection layer 150 is equal to 0 eV. For example, in other embodiments, the hole transport material a can also be made of a material whose highest occupied molecular orbital difference with the material of the hole injection layer 150 is greater than 0 eV but not greater than 0.2 eV. In this way, since the hole transport material a matches the material of the hole injection layer 150, the energy levels at the interface between the hole transport layer 120 and the hole injection layer 150 are the same or similar, which will avoid the accumulation of carriers at the interface between the hole transport layer 120 and the hole injection layer 150 due to the large material difference between the hole transport layer 120 and the light-emitting auxiliary layer 130.

[0055] It should also be noted that the total thickness of the light-emitting auxiliary layer 130 can be determined according to the intrinsic spectrum of the device. For example, after the light-emitting auxiliary layer 130 is added between the light-emitting layer 110 and the hole transport layer 120, an optical microcavity is formed between the anode 140 and the cathode 190. The optical microcavity has a microcavity effect, which can enhance the emission intensity at the emission peak of the optical microcavity and narrow the emission peak spectrum. At the same time, the emission peak can be moved, thereby significantly improving the color purity of the light emitted by the light-emitting device 100.

[0056] At least one embodiment of the present application further provides a display panel, which may include the light-emitting device in any of the above embodiments.

[0057] The light-emitting device may be at least one of a light-emitting device capable of emitting blue light, a light-emitting device capable of emitting red light, a light-emitting device capable of emitting green light, a light-emitting device capable of emitting yellow light, and a light-emitting device capable of emitting cyan light in the display panel. The light-emitting auxiliary materials in the light-emitting devices capable of emitting light of different colors may be different. Specifically, the light-emitting auxiliary material corresponds to the material of the light-emitting layer in the light-emitting device.

[0058] It should be understood that the light emitting device in the display panel may also be based on Figures 1 to 6 Any of the light-emitting devices in the illustrated embodiments may be replaced with equivalent or significantly modified light-emitting devices. The display panel may be applied to various electronic display products, including but not limited to at least one of mobile phones, tablet computers, e-book readers, players, digital cameras, laptop computers, car computers, desktop computers, set-top boxes, smart TVs, and wearable devices.

[0059] In addition, according to actual needs, the display panel may also include other structures such as an array substrate for carrying and driving light-emitting devices, an encapsulation layer for encapsulating light-emitting devices, a light extraction layer for guiding or straightening the output light of the light-emitting devices, and other auxiliary optical films such as polarizers.

[0060] Since the display panel of the embodiment of the present application includes the above Figures 1 to 6 All technical solutions of the illustrated embodiment can at least achieve all the above-mentioned technical effects, and will not be described in detail here.

[0061] It should be noted that the combination of the various technical features in this application is not limited to the combination described in the claims of this application or the combination described in the specific embodiments. All technical features described in this application can be freely combined or combined in any way unless there is a contradiction between them.

[0062] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent replacements, etc. made within the spirit and principles of the present application shall be included in the scope of protection of the present application.

Claims

1. A light emitting device, characterized in that: It includes a light-emitting layer, a hole transport layer and a light-emitting auxiliary layer, wherein the light-emitting auxiliary layer is located between the light-emitting layer and the hole transport layer. Wherein, the luminescence auxiliary layer comprises a mixed material layer of a hole transport material and a luminescence auxiliary material; the luminescence auxiliary material is a material having both electron blocking properties and hole transport properties; The highest occupied molecular orbital of the material of the light-emitting auxiliary layer facing the light-emitting layer matches the highest occupied molecular orbital of the light-emitting main material of the light-emitting layer, and the difference between the highest occupied molecular orbital of the material of the light-emitting auxiliary layer facing the light-emitting layer and the highest occupied molecular orbital of the light-emitting main material of the light-emitting layer is not greater than 0.2 eV; The mixed material layer includes a first side facing the light-emitting layer and a second side facing the hole transport layer. Along the direction from the second side to the first side, the doping ratio of the hole transport material gradually decreases according to a first preset gradient rule, and the doping ratio of the light-emitting auxiliary material gradually increases according to a second preset gradient rule.

2. The light emitting device according to claim 1, wherein The first preset changing rule includes step-by-step decrease, linear decrease, arc-shaped decrease or S-shaped decrease, and / or the second preset changing rule includes step-by-step increase, linear increase, arc-shaped increase or S-shaped increase.

3. The light emitting device according to claim 1, wherein In the mixed material layer, the ratio between the total doping amount of the hole transport material and the total doping amount of the luminescence auxiliary material is in a range of 2:1 to 1:

2.

4. The light emitting device according to claim 1, wherein The light-emitting auxiliary layer further includes a first sub-film layer, which is located between the mixed material layer and the hole transport layer. The material of the first sub-film layer is the hole transport material.

5. The light emitting device according to claim 4, characterized in that The light-emitting auxiliary layer further includes a second sub-film layer, which is located between the mixed material layer and the light-emitting layer. The material of the second sub-film layer is all the light-emitting auxiliary material.

6. The light emitting device according to claim 4, characterized in that The thickness of the mixed material layer is greater than or equal to the thickness of the first sub-film layer, The thickness of the first sub-membrane layer is not less than 50Å.

7. The light emitting device according to any one of claims 1 to 6, characterized in that Also includes: anode and cathode, and, At least one of a hole injection layer, a hole blocking layer, an electron transport layer, and an electron injection layer is disposed between the anode and the cathode.

8. A display panel, characterized in that: The light emitting device comprises the light emitting device according to any one of claims 1 to 7.

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