CN114784080A - Display panel and display device - Google Patents
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- CN114784080A CN114784080A CN202210575960.5A CN202210575960A CN114784080A CN 114784080 A CN114784080 A CN 114784080A CN 202210575960 A CN202210575960 A CN 202210575960A CN 114784080 A CN114784080 A CN 114784080A
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- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
- H10K59/00—Integrated devices, or assemblies of multiple devices, comprising at least one organic light-emitting element covered by group H10K50/00
- H10K59/30—Devices specially adapted for multicolour light emission
- H10K59/32—Stacked devices having two or more layers, each emitting at different wavelengths
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- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
- H10K59/00—Integrated devices, or assemblies of multiple devices, comprising at least one organic light-emitting element covered by group H10K50/00
- H10K59/10—OLED displays
- H10K59/12—Active-matrix OLED [AMOLED] displays
- H10K59/122—Pixel-defining structures or layers, e.g. banks
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Abstract
The application provides a display panel and a display device. The display panel includes a plurality of light emitting devices, at least one of which includes an anode, a cathode, at least two light emitting units, a charge generation layer, and a functional layer. At least two light emitting units are positioned between the anode and the cathode. The charge generation layer includes metal particles and is located between any adjacent two of the at least two light emitting cells. The functional layer includes a hole transport type material and is in contact with the charge generation layer. The functional layer in the display panel is arranged, so that the problem of transverse crosstalk of the display panel is solved, and the phenomenon of display color cast of the display panel is improved.
Description
Technical Field
The invention relates to the technical field of display, in particular to a display panel and a display device with the same.
Background
The Light Emitting principle of an Organic Light-Emitting Diode (OLED) is that an Organic Light-Emitting layer is added between two electrodes, and when electrons and holes meet in the Organic material, Light is emitted. To improve the luminance and efficiency, more than two single-layer OLEDs are connected in series. However, the problem of lateral leakage between different pixels is likely to occur at the connection between two adjacent OLEDs, thereby causing color shift, color mixing, and other undesirable phenomena.
Disclosure of Invention
In view of the above, the present application provides a display panel, in which a functional layer is disposed in contact with metal particles of a charge generation layer between two adjacent light-emitting layers, so as to improve the problem of lateral leakage of the display panel, and further improve the phenomenon of color shift of the display.
A first aspect of the present application provides a display panel. The display panel includes a plurality of light emitting devices, at least one of which includes an anode, a cathode, at least two light emitting units, a charge generation layer, and a functional layer. At least two light emitting units are positioned between the anode and the cathode. The charge generation layer includes metal particles and is located between any adjacent two of the at least two light emitting cells. The functional layer includes a hole transport type material and is in contact with the charge generation layer.
In the scheme, the functional layer of the hole transport type material can be in contact with metal particles in the charge generation layer to form a hole trap, so that the transverse flow of holes is reduced, namely, the transverse resistance between the charge generation layer and the functional layer is increased, and the problem of display color cast of the display panel caused by transverse electric leakage is solved.
In combination with the first aspect, in some embodiments, each charge generation layer includes a first charge generation layer and a second charge generation layer. The first charge generation layer is provided with P-type doping and is positioned between the anode and the cathode, the second charge generation layer is provided with N-type doping and contains metal particles and is positioned between the first charge generation layer and the anode, and the functional layer is in contact with the second charge generation layer.
In the scheme, the functional layer is in direct contact with the second charge generation layer, namely in direct contact with the metal particles, so that the trapping traps of the holes are generated more efficiently, the transverse flow quantity of the holes is reduced more effectively, the transverse crosstalk problem of the display panel is improved, and the bad phenomenon of display color cast is improved efficiently.
In combination with the first aspect, in some embodiments, the functional layer is located between the first charge generation layer and the second charge generation layer.
In the scheme, the functional layer is only in contact with the charge generation layer, so that the color cast phenomenon of the display panel is effectively improved and the user experience is improved while the luminous efficiency of the luminous unit, namely the luminous efficiency of the display panel, is not influenced.
With reference to the first aspect, in some embodiments, the display panel further includes a pixel definition layer including a plurality of openings for defining the light emitting devices and a plurality of pixel defining regions. The orthographic projection of the functional layer on the light-emitting surface of the display panel covers the orthographic projection of the plurality of openings on the light-emitting surface of the display panel and the orthographic projection of the plurality of pixel limiting areas on the light-emitting surface of the display panel.
In the scheme, the functional layer covers the upper end face of the second charge generation layer far away from the pixel defining layer, so that on one hand, the transverse movement of a cavity is prevented more effectively, and the phenomenon of color cast is improved. On the other hand, the design scheme of the functional layer is simple in process, and the production cost is saved.
In some embodiments in combination with the first aspect, each light-emitting unit includes a hole transport layer between the anode and the cathode. The absolute value of the HOMO level of the material of the functional layer is less than or equal to the absolute value of the HOMO level of the material of the hole transport layer, and the mobility of the material of the functional layer is greater than or equal to the mobility of the material of the hole transport layer.
In the above scheme, the functional layer is made of the material according to the above requirements, so that the number of hole transverse transmission can be reduced, the color cast problem of the display panel can be improved, the transmission efficiency of electrons between the two light-emitting units can be increased, and the light-emitting efficiency of the display panel can be improved.
In combination with the first aspect, in some embodiments, the material of the functional layer is an aromatic amine derivative. Further, for example, the material of the functional layer is any of 4,4' -cyclohexylbis [ N, N-bis (4-methylphenyl) aniline ], N ' -diphenyl-N, N ' - (1-naphthyl) -1,1' -biphenyl-4, 4' -diamine.
In the scheme, the functional layer is prepared by using the existing aromatic amine derivative, so that the functional layer has the characteristic of reducing the number of transverse hole transport and has the characteristic of not influencing longitudinal electron transport. Therefore, on the basis of the existing material, the material of the functional layer does not need to be additionally processed and designed, the production procedure of the display panel is simplified, and the production cost is saved.
In combination with the first aspect, in some embodiments, the functional layer is located between the second charge generation layer and the anode and in contact with the second charge generation layer.
In the scheme, the functional layer is directly contacted with the second charge generation layer containing the metal particles, so that the number of trapping traps of the holes generated on the functional layer is increased, the transverse transmission of the holes is reduced, and the phenomenon of color cast of the display panel is effectively improved.
In combination with the first aspect, in some embodiments, the display panel further includes a pixel definition layer including a plurality of openings for defining the light emitting devices and a plurality of pixel defining regions. The orthographic projection of the functional layer on the light-emitting surface of the display panel is superposed with the orthographic projection of the pixel limiting areas on the light-emitting surface of the display panel.
In the above scheme, the functional layer only covers the lower part of the plurality of pixel limited areas corresponding to the charge generation layer, so that the influence on the luminous efficiency and the service life of the display panel is reduced, and the problem of display color cast caused by transverse leakage is relieved.
With reference to the first aspect, in some embodiments, the lateral resistance of the material of the functional layer is greater than the lateral resistance of the material of the second charge generation layer, and the mobility of the material of the functional layer is less than the mobility of the material of the second charge generation layer.
In the scheme, the material of the functional layer can be designed according to the requirements in the scheme, and the existing hole transport type material is not required to be researched and developed, so that the production process of the display panel is simplified, and the production cost is saved.
In combination with the first aspect, in some embodiments, the material of the functional layer is an aromatic amine derivative having a lateral resistance greater than 1E +10 Ω/□. For example, the material of the functional layer is any one of 4,4',4 ″ -tris (carbazol-9-yl) triphenylamine and 4,4', -bis (9-carbazol) biphenyl.
In some embodiments, in combination with the first aspect, each light-emitting unit includes a hole injection layer and a hole transport layer between the anode and the cathode, and an electron transport layer between the hole transport layer and the cathode. The first charge generation layer is formed by doping a P-type semiconductor material on a first base material layer, and the material of the first base material layer is the same as that of the hole transport layer. The second charge generation layer is formed by doping a metal material in a second base material layer, and the material of the second base material layer is an electronic material. Further, the material of the second base material layer is the same as that of the electron transport layer.
In the above-described aspect, the selection of materials for the first charge generation layer and the second charge generation layer not only further reduces the generation of lateral current, but also improves the efficiency of the light emitting unit and effectively reduces the driving voltage.
In combination with the first aspect, in some embodiments, the material of the first charge generation layer is the same as the material of the hole injection layer.
A second aspect of the present application provides a display device. The display device includes the display panel of any one of the first aspect provided above.
Drawings
Fig. 1 is a schematic structural diagram of at least one light emitting device in a display panel according to an embodiment of the present application.
Fig. 2 is a schematic structural diagram of at least one light emitting device in a display panel according to another embodiment of the present application.
Fig. 3 is a schematic structural diagram of at least one light emitting device in a display panel according to another embodiment of the present application.
Fig. 4 is a cross-sectional view of at least one light emitting device in a display panel according to an embodiment of the present application.
Fig. 5 is a cross-sectional view of at least one light emitting device in a display panel according to another embodiment of the present application.
Fig. 6 is a cross-sectional view of at least one light emitting device in a display panel according to another embodiment of the present application.
Fig. 7 is a schematic structural diagram of at least one light-emitting device in the display panel according to the embodiment of the present application, which does not include a functional layer.
Fig. 8 is a schematic structural diagram of at least one light-emitting device including a functional layer in a display panel according to an embodiment of the present application.
Fig. 9 is a voltage-current density curve of a light emitting device including a functional layer and a light emitting device not including a functional layer according to an embodiment of the present application.
Fig. 10 is a current density-current efficiency curve of a light emitting device including a functional layer and a light emitting device not including a functional layer according to an embodiment of the present application.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
As demands for brightness, efficiency, and lifespan of organic light emitting diodes have increased, stacked organic light emitting diodes (TOLEDs), which are organic light emitting diodes in which a plurality of light emitting cells are connected in series through a Charge Generation Layer (CGL), have come into play. The charge generation layer can not only connect the respective light emitting cells, but also generate charges, and rapidly transfer and inject the generated charges into the light emitting cells, and thus, the charge generation layer has an important effect on the performance of the stacked device.
Currently, the more charge generation layers used are n-type doped organic layers/p-type doped organic layers, but the CGL materials used for mass production, i.e., p-doped or n-doped, have a strong lateral leakage phenomenon due to their high lateral conductivity. For example, Alq3:Li/NPB:FeCl3The transverse resistance of the doped Li and the material of the hole injection layer for mass production is small, which easily causes the transverse transmission of carriers in the CGL layer, and the formation of a circuit causes the transverse electric leakage problem among sub-pixels with different colors, thereby causing the problems of poor display color cast, color mixing and the like of the laminated organic light emitting diode.
The embodiment of the application provides a display panel. A charge generation layer containing metal particles is arranged between at least two adjacent light-emitting units in a plurality of light-emitting units in the display panel, and a functional layer of a hole transport type material is in contact with the metal particles in the charge generation layer to form a hole trapping trap, so that the transverse transport of holes is reduced, and the phenomenon of display color cast of the display panel caused by transverse electric leakage is relieved.
Hereinafter, a display panel and a display device according to at least one embodiment of the present application will be described in detail with reference to the accompanying drawings.
As shown in fig. 1, in some embodiments, the display panel includes a plurality of light emitting devices, at least one of which includes an anode 1, a cathode 2, at least two light emitting units, e.g., a first light emitting unit 31 and a second light emitting unit 32, charge generation layers, e.g., a first charge generation layer 4 and a second charge generation layer 5, and a functional layer 6. At least two light emitting cells are located between the anode 1 and the cathode 2. The charge generation layer includes metal particles and is located between any adjacent two of the at least two light emitting cells. The functional layer 6 includes a hole transport type material and is in contact with the charge generation layer. The functional layer of the hole-transporting material can be in contact with metal particles in the charge generation layer to form a hole trap, so that the transverse flow of holes is prevented, the transverse flow quantity of the holes is reduced, namely, the transverse resistance between the charge generation layer and the functional layer is increased, and the problem of display color cast of the display panel caused by transverse crosstalk is solved.
It should be understood that the functional layer only needs to be disposed to contact with the metal particles in the charge generation layer, and may be disposed on the surface and/or inside of the charge generation layer laterally between the sub-pixels of the display panel, and may be specifically designed according to the functional requirements of the display panel and the limitations of the production process.
The formation of the trap of the hole depends on the formation of the functional layer in contact with the metal particles, and the structure of the charge generation layer and the distribution of the metal particles have a direct influence on the provision of the functional layer. As shown in fig. 1, in some embodiments, each charge generation layer 4, 5 includes a first charge generation layer 4 and a second charge generation layer 5. The first charge generation layer 4 has a P-type doping and is located between the anode 1 and the cathode 2. The second charge generation layer 5, which has N-type doping and contains metal particles, is located between the first charge generation layer 4 and the anode 1, and the functional layer 6 is in contact with the second charge generation layer 5. Specifically, the N-type doped second charge generation layer 5 of the multi-layered charge generation layers comprises a metal material, which may include a metal, a metal oxide, a metal halide, a metal silicide, or a combination thereof. The functional layer 6 is in direct contact with the second charge generation layer 5 containing metal particles, so that more metal particles are in direct contact with the hole transport type material, the number of trapping traps of holes formed on the contact surface of the functional layer 6 and the second charge generation layer 5 is increased, the transverse flow of the holes is effectively reduced, the transverse electric leakage problem of the display panel is effectively improved, and the bad phenomenon of display color cast is effectively improved.
It should be understood that the specific structure and number of layers of the charge generation layer are not limited to the double-layer structure in the above embodiments, and may be a single-layer structure, or a multi-layer structure larger than two, for example, the functional layer is a three-layer structure or the functional layer is a four-layer structure, which may be selected according to the functional requirements of the display panel. Meanwhile, the design of the charge generation layer is not limited to the double-layer structure in the above embodiments, and may be a single-layer, three-layer, four-layer or more-layer structure design, and meanwhile, the selection of the concentration and the material of the P-type doping and/or the N-type doping in the charge generation is not limited, and these may be specifically designed according to the functional requirements of the display panel.
The functional layer is in contact with the metal particles to form trap traps for holes, so that the metal particles, which are the purpose of reducing the number of hole lateral transport, are mainly distributed in the second charge generation layer, and the position of the functional layer relative to the second charge generation layer is designed as follows in consideration of the influence of the arrangement of the functional layer on the luminous efficiency and the service life of the display panel.
As shown in fig. 1, in some embodiments, the display panel includes at least one functional layer, namely a first functional layer 6, disposed between the first charge generation layer 4 and the second charge generation layer 5. At this time, the first functional layer 6 is only in contact with the charge generating layer, and is not in contact with the functional film layers in the light emitting units 31 and 32, that is, the electron transport layer and the hole transport layer are in direct contact with each other, so that the display color shift phenomenon of the display panel is effectively improved while the light emitting efficiency of the light emitting units 31 and 32, that is, the light emitting efficiency of the display panel, is not affected, and the user experience is improved.
As shown in fig. 2, in some embodiments, the display panel includes at least one functional layer, i.e., the second functional layer 7, which is located between the second light emitting unit 32 and the second charge generation layer 5 and is in contact with a lower end surface of the second charge generation layer 5 facing the second light emitting unit 32. Therefore, the metal particles in the second charge generation layer 5 are diffused to the second functional layer 7, and the second functional layer 7 is in contact with the metal particles to form a hole trap, so that the hole transverse transmission is reduced, the problem of transverse series flow between different sub-pixels in the display panel is solved, and the phenomenon of display color cast of the display panel is improved.
As shown in fig. 3, in some embodiments, the display panel includes at least two functional layers, i.e., a first functional layer 6 is located between the first charge generation layer 4 and the second charge generation layer 5, and a second functional layer 7 is located between the second charge generation layer 5 and the second light emitting unit 32 and is in contact with the second charge generation layer 5 toward the lower end surface of the second light emitting unit 32. The two functional layers 6 and 7 are respectively in contact with the upper and lower surfaces of the second charge generator 5 in the transverse direction, and can form more trapping traps of holes with metal particles therein, so that the problem of transverse crosstalk is effectively improved, and the problem of display color cast of the display panel is effectively improved.
As shown in fig. 4, 5 and 6, the display panel further includes a pixel defining layer 8 on the substrate 9, the pixel defining layer 8 including a plurality of openings 81 for defining the light emitting devices and a plurality of pixel defining regions. The first charge generation layer 4 and the second charge generation layer 5 are sequentially overlaid on the pixel defining layer 8. And as shown in fig. 4, 5 and 6, only a schematic structural view of the second light emitting unit 32 located in the opening 81 is given, and as for the structure of the first light emitting unit, which is not shown in fig. 4, 5 and 6, reference may be made to fig. 7 and 8 for the structural relationship between the first light emitting unit and the second light emitting unit 32. In order to reduce the lateral transport amount of holes at the contact surface between the functional layers 6 and 7 and the second charge generation layer 5 and to reduce the influence on the light emission efficiency of the display panel, the specific arrangement of the functional layers 6 and 7 is designed.
As shown in fig. 4, in some embodiments, the first functional layer 6 is disposed between the first charge generation layer 4 and the second charge generation layer 5, which is not in direct contact with the functional film layers of the light emitting units 31, 32, i.e., does not participate in the transport of carriers between the charge generation layers and the light emitting units 31, 32. Therefore, in order to simplify the processing process of the first functional layer 6, the first functional layer 6 covers the pixel defining layer 8 entirely, that is, the orthographic projection of the first functional layer 6 on the light emitting surface of the display panel coincides with the orthographic projection of the plurality of openings 81 and the orthographic projection of the plurality of pixel defining areas on the light emitting surface of the display panel, respectively. The design scheme of the functional layer realizes the largest area contact with the metal particles, so that more trapping traps of holes are generated, the transverse movement of the holes is more effectively prevented, the problem of transverse leakage among the non-used sub-pixels in the display panel is more effectively solved, and the phenomenon of display color cast is improved. On the other hand, the corresponding production process of the technical scheme that the first functional layer 6 completely covers the pixel defining layer 8 is simple, and the production cost is saved. For example, the first functional layer 6 may be directly evaporated on the second charge generation layer 5 as a common film layer.
It should be understood that the design scheme of the first functional layer 6 is not limited to the scheme of covering the pixel defining layer 8 on the whole, and the scheme that the first functional layer 6 only covers at least part of the plurality of openings 81, or the scheme that the first functional layer 6 only covers at least part of the plurality of pixel defining areas can also be adopted.
As shown in fig. 5, in other embodiments, when the second functional layer 7 is located between the second charge generation layer 5 and the second light emitting unit 4 and is in contact with the second charge generation layer 5, the second functional layer 7 covers the second charge generation layer 5 below the plurality of pixel defining regions, and does not cover the second charge generation layer 5 above the plurality of openings 81. That is, the second functional layer 7 does not participate in the longitudinal transport of electrons between the charge generation layers, e.g., the first and second charge generation layers 4 and 5, and the adjacent light emitting units 31 and 32, so as not to affect the light emitting efficiency of the display panel.
As shown in fig. 6, in other embodiments, when the display panel includes at least two functional layers, such as a first functional layer 6 and a second functional layer 7, the first functional layer 6 is located between the first charge generation layer 4 and the second charge generation layer 5, and the second functional layer 6 is located between the second charge generation layer 5 and the second light emitting unit 32 and is in contact with the second light emitting unit 32, the first functional layer 6 covers the second charge generation layer 5 corresponding to the pixel defining regions 7 and the openings, i.e., completely covers the pixel defining layer 8; the second functional layer 7 is covered under the second charge generation layer 5 corresponding to the plurality of pixel defining regions. The arrangement mode of the functional layer can more efficiently reduce the transverse flow of the cavity, thereby more effectively improving the problem of transverse electric leakage in the display panel, further relieving the phenomenon of displaying the color surface and improving the user experience.
It should be understood that the arrangement of the functional layer is not limited to the design scheme that the functional layer is located between the first charge generation layer and the second charge generation layer and/or the functional layer is located between the second charge generation layer and the second light-emitting unit, and other schemes, such as arrangement between the first charge generation layer and the first light-emitting unit and contact with the first charge generation layer, or arrangement of a metal film layer alone such that the functional layer contacts with the first charge generation layer to form more hole trapping traps, etc., may also be adopted. Meanwhile, the functional layer is not limited to the structural design of a single-layer or double-layer film layer, and the structural design of more layers of film layers, such as three layers, four layers and the like, can also be adopted. The functional layer can be designed specifically according to the functional requirements of the display panel.
Similarly, the functional layer is provided at a different position from the charge generation layer, and the selection of the material is also influenced. Each light-emitting unit includes a hole transport layer between an anode and a cathode, and the material of the functional layer is selected differently according to the position where the functional layer is disposed.
As shown in fig. 1 or fig. 3, in some embodiments, when the first functional layer 6 is positioned between the first charge generation layer 4 and the second charge generation layer 5, the absolute value of the HOMO level of the material of the first functional layer is equal to or less than the absolute value of the HOMO level of the material of the hole transport layer, and the mobility of the material of the first functional layer is equal to or greater than the mobility of the material of the hole transport layer. The selection of the material of the first functional layer enables the functional layer to cooperate with the metal particles to increase the resistance of hole transverse transmission, improve the color shift of the display panel, reduce the energy level of electron transmission between the first charge generation layer and the second charge generation layer, and increase the electron longitudinal transmission efficiency, namely, increase the transmission efficiency of electrons between two light-emitting units, thereby increasing the luminous efficiency of the display panel.
Further, the material of the first functional layer is an aromatic amine derivative. For example, the material of the first functional layer is any one of 4,4' -cyclohexylbis [ N, N-bis (4-methylphenyl) aniline ], N ' -diphenyl-N, N ' - (1-naphthyl) -1,1' -biphenyl-4, 4' -diamine.
As shown in fig. 2 or 3, in some embodiments, when the second functional layer 7 is positioned between the second charge generation layer 5 and the second light emitting unit 32 and in contact with the second charge generation layer 5, the lateral resistance of the material of the second functional layer 7 is greater than the lateral resistance of the material of the second charge generation layer, and the mobility of the material of the second functional layer is less than the mobility of the material of the second charge generation layer. Further, the material of the second functional layer is aromatic amine derivative with transverse resistance larger than 1E +10 omega/□. For example, the material of the second functional layer is any one of 4,4',4 ″ -tris (carbazol-9-yl) triphenylamine and 4,4', -bis (9-carbazol) biphenyl.
The material of the first functional layer and the material of the second functional layer can be designed according to the requirements in the scheme, the existing hole transmission type material is not required to be researched and developed, the production process is simplified, and the production cost is saved. It should be understood that the material of the first functional layer and the material of the second functional layer are not limited to the materials in the above solution, and the materials based on the hole type material may be designed according to the specific requirements of the display panel for the functional layer, such as a doping process or a recombination process, so as to obtain the material of the functional layer meeting the requirements.
In some embodiments, each light-emitting unit includes a hole injection layer and a hole transport layer between the anode and the cathode, and an electron transport layer between the hole transport layer and the cathode. The first charge generation layer is formed by doping a first base material layer with a P-type semiconductor material, and the material of the first base material layer is the same as that of the hole transport layer. The second charge generation layer is formed by doping a metal material on a second base material layer, and the material of the second base material layer is an electronic material.
The second charge generation layer contains metal particles with positive charges, so that the polarities inside the adjacent first charge generation layers, namely the P-type doping layers, can be separated, holes can be transmitted from the first charge generation layers to the adjacent light emitting layers without introducing P-type dopants, and current leakage caused by introducing the P-type dopants is reduced. On the other hand, the first charge generation layer includes the same kind of material as the hole transport layer in the adjacent light emitting unit, and the second charge generation layer includes the same kind of material as the electron type material, for example, the electron transport layer, in the adjacent light emitting unit, it is possible to improve the efficiency of the light emitting unit and effectively reduce the driving voltage.
In other embodiments, the material of the first charge generation layer is the same as the material of the hole injection layer. In other embodiments, the second charge generation layer is formed by doping a metal material with the material of the electron transport layer as a base material.
In some embodiments, the functional layer has a thickness of
For example further as
And so on. Thus, in consideration of light emissionThe light-emitting efficiency of the efficiency, the size of the product and the packaging process design the thickness of the functional layer, and the cost performance of the display panel is improved. It should be understood that the thickness of the functional layer is not limited to the above value, and may be increased or decreased according to the product requirement to meet the functional requirement of the display panel.
In order to verify that providing a functional layer in a light emitting device of a display panel can improve the problem of display color shift due to lateral leakage, a light emitting device including no functional layer was also provided as a comparative example, and a light emitting device including a functional layer was provided as an experimental example, as follows.
As shown in fig. 7, at least one light emitting device in a display panel including two light emitting units, e.g., a first light emitting unit 31 and a second light emitting unit 32, disposed in a stack in order between an anode 1 and a cathode 2, and a charge generation layer, e.g., a first charge generation layer 4 and a second charge generation layer 5, for connecting the two light emitting units is provided as a comparative example in some embodiments. Specifically, the first light-emitting unit 31 includes an electron injection layer 311, a first electron transport layer 312, a first hole blocking layer 313, a first light-emitting layer 314, a first electron blocking layer 315, and a first hole transport layer 316, which are sequentially stacked between the cathode 2 and the first charge generation layer 4, and the electron injection layer 311 is located between the cathode 2 and the first light-emitting layer 314. The second light emitting unit 32 includes a second electron transport layer 321, a second hole blocking layer 322, a second light emitting layer 323, a second electron blocking layer 324, a second hole transport layer 325, and a hole injection layer 326 sequentially stacked between the second charge generation layer 5 and the anode 1, and the hole injection layer 326 is located between the second light emitting layer 323 and the anode 1. The charge generation layers 4, 5 are for 31, 32 of two light emitting cells in series. The charge generation layers 4, 5 include a first charge generation layer 4 and a second charge generation layer 5 including metal particles, and the first charge generation layer 4 is located between the anode 1 and the first light emitting cell 31 and is in contact with the first hole transport layer 316 in the first light emitting cell 31. The second charge generation layer 5 is positioned between the first charge generation layer 4 and the anode 1, and is in contact with the second electron transport layer 321 positioned in the second light emitting unit 32.
In other embodiments, as shown in fig. 8, based on the light emitting device provided in fig. 8, a functional layer 6 is provided between the first charge generation layer 4 and the second charge generation layer 5.
The sheet resistance of the composite film connecting the two light emitting units in fig. 8 and 9 is calculated, where the composite film in fig. 8 is a composite film structure (p-CGL/n-CGL) of the first charge generation layer 4 and the second charge generation layer 5, and the composite film in fig. 9 is a structure (p-CGL/functional layer/n-CGL) in which the first functional layer is disposed between the first charge generation layer and the second charge generation layer. Specifically, the sheet resistance of p-CGL/n-CGL is 1.1 x 1010The sheet resistance of omega/□, p-CGL/functional layer/n-CGL is 1.3 x 1010Ω/□, it can be seen that, after the functional layer is disposed between the first charge generation layer and the second charge generation layer, the sheet resistance between two adjacent light-emitting units of the display panel is increased, that is, the impedance of the leakage current channel between two adjacent light-emitting units is increased, so that the problem of lateral leakage between adjacent pixel regions of the display panel is improved, and the phenomenon of non-uniformity of the display color plane is improved.
Based on the light emitting devices of fig. 7 and 8, the relationship of the voltage-current density curve and the current density-current efficiency curve of the two light emitting devices was tested using a Keithley2400+ PR788 testing apparatus. Specifically, p-CGL/n-CGL represents the light emitting device in FIG. 7 without the functional layer, and p-CGL/HTL/n-CGL represents the light emitting device in FIG. 8 with the functional layer.
As shown in fig. 9, the light emitting device including a functional layer has a small difference in current density-voltage curves at different voltages than the light emitting device including no functional layer, and thus it is known that the light emitting device including a functional layer has a small difference in electrical characteristics from the light emitting device including no functional layer.
As shown in fig. 10, the light emitting device including a functional layer and the light emitting device not including a functional layer both have light emission efficiencies that slowly increase substantially in synchronization with a slow increase in current density. It can be seen that the light emitting device including the functional layer has substantially the same optical performance as the light emitting device not including the functional layer, that is, the increase in the arrangement of the functional layer has substantially no influence on the light emitting efficiency of the light emitting device (display panel).
As described above, although the performance of the display panel after optimization (with the functional layers added in fig. 8) is not much different from the performance of the display panel before optimization (with the functional layers not added in fig. 7), the problem of lateral leakage is improved.
It should be understood that the functional film layers in the first light-emitting unit 31 and/or the second light-emitting unit 32 are not limited to the design in the above scheme, and a part of the functional film layers may be reduced, for example, the hole blocking layers 313 and 322 and/or the electron blocking layers 315 and 324 are not provided, and in the above improved functional film layers, a part and/or all of the film layers may adopt a single film layer or a composite film layer, which is not described herein again. Also, any one of red, green and blue colors or other colors of light may be emitted for the first light emitting unit 31 and the second light emitting unit 32. In general, the specific design scheme for the functional film layer in the first light emitting unit 31 and/or the second light emitting unit 32 may be specifically designed according to the functional requirements of the display panel.
The embodiment of the application also provides a display device. The display device includes the display panel provided in any one of the first aspect. The display device is any product or component with a display function, such as a mobile phone, a tablet computer, a television, a navigator, a vehicle-mounted application and the like.
The above description is only for the specific embodiments of the present application, but the protection scope of the present application is not limited thereto, and any person skilled in the art can think of the changes or substitutions within the technical scope of the present application, and shall be covered by the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.
Claims (10)
1. A display panel, comprising: a plurality of light emitting devices, at least one of the light emitting devices comprising:
an anode, a cathode, and at least two light emitting units positioned between the anode and the cathode;
a charge generation layer including metal particles and located between any adjacent two of the at least two light emitting cells;
a functional layer comprising a hole transport type material and in contact with the charge generation layer.
2. The display panel according to claim 1, wherein each of the charge generation layers comprises:
a first charge generation layer having a P-type doping and located between the anode and the cathode;
a second charge generation layer having N-type doping and containing the metal particles, located between the first charge generation layer and the anode;
the functional layer is in contact with the second charge generation layer.
3. The display panel according to claim 2,
the functional layer is located between the first charge generation layer and the second charge generation layer.
4. The display panel according to claim 3, further comprising:
a pixel defining layer including a plurality of openings for defining the light emitting devices and a plurality of pixel defining regions;
the orthographic projection of the functional layer on the light-emitting surface of the display panel covers the orthographic projection of the plurality of openings on the light-emitting surface of the display panel and the orthographic projection of the plurality of pixel limiting areas on the light-emitting surface of the display panel.
5. The display panel according to claim 3 or 4, wherein each of the light emitting units comprises a hole transport layer between the anode and the cathode;
the absolute value of the HOMO level of the material of the functional layer is less than or equal to the absolute value of the HOMO level of the material of the hole transport layer, and the mobility of the material of the functional layer is greater than or equal to the mobility of the material of the hole transport layer,
preferably, the material of the functional layer is an aromatic amine derivative, and preferably, the material of the functional layer is any one of 4,4' -cyclohexylbis [ N, N-bis (4-methylphenyl) aniline ], N ' -diphenyl-N, N ' - (1-naphthyl) -1,1' -biphenyl-4, 4' -diamine.
6. The display panel according to claim 2,
the functional layer is located between the second charge generation layer and the anode and in contact with the second charge generation layer.
7. The display panel according to claim 6, further comprising:
a pixel defining layer including a plurality of openings for defining the light emitting devices and a plurality of pixel defining regions;
and the orthographic projection of the functional layer on the light-emitting surface of the display panel is superposed with the orthographic projection of the pixel limiting areas on the light-emitting surface of the display panel.
8. The display panel according to claim 6 or 7, wherein a lateral resistance of a material of the functional layer is larger than a lateral resistance of a material of the second charge generation layer, and a mobility of the material of the functional layer is smaller than a mobility of the material of the second charge generation layer,
preferably, the material of the functional layer is an aromatic amine derivative with a lateral resistance greater than 1E +10 omega/□, and preferably, the material of the functional layer is any one of 4,4 '-tris (carbazole-9-yl) triphenylamine and 4,4' -bis (9-carbazole) biphenyl.
9. The display panel according to claim 2, wherein each of the light emitting units comprises a hole injection layer and a hole transport layer between the anode and the cathode, and an electron transport layer between the hole transport layer and the cathode,
the first charge generation layer is formed by doping a first base material layer with a P-type semiconductor material, the material of the first base material layer is the same as that of the hole transport layer, the second charge generation layer is formed by doping a second base material layer with a metal material, the material of the second base material layer is an electron-type material,
preferably, the material of the second substrate layer is the same as that of the electron transport layer,
preferably, the material of the first charge generation layer is the same as the material of the hole injection layer.
10. A display device characterized by comprising the display panel according to any one of claims 1 to 9.
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| CN202210575960.5A CN114784080A (en) | 2022-05-25 | 2022-05-25 | Display panel and display device |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117998909A (en) * | 2023-06-25 | 2024-05-07 | 华为技术有限公司 | Display panel, display screen and electronic equipment |
| WO2024113176A1 (en) * | 2022-11-29 | 2024-06-06 | 京东方科技集团股份有限公司 | Organic electroluminescent component and display device |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2024113176A1 (en) * | 2022-11-29 | 2024-06-06 | 京东方科技集团股份有限公司 | Organic electroluminescent component and display device |
| CN117998909A (en) * | 2023-06-25 | 2024-05-07 | 华为技术有限公司 | Display panel, display screen and electronic equipment |
| WO2025001992A1 (en) * | 2023-06-25 | 2025-01-02 | 华为技术有限公司 | Display panel, display screen and electronic device |
| CN117998909B (en) * | 2023-06-25 | 2025-03-18 | 华为技术有限公司 | Display panels, displays and electronic devices |
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