CN110635061A - Display panel and display device - Google Patents
Display panel and display device Download PDFInfo
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- CN110635061A CN110635061A CN201911013641.XA CN201911013641A CN110635061A CN 110635061 A CN110635061 A CN 110635061A CN 201911013641 A CN201911013641 A CN 201911013641A CN 110635061 A CN110635061 A CN 110635061A
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- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
- H10K50/00—Organic light-emitting devices
- H10K50/10—OLEDs or polymer light-emitting diodes [PLED]
- H10K50/11—OLEDs or polymer light-emitting diodes [PLED] characterised by the electroluminescent [EL] layers
- H10K50/125—OLEDs or polymer light-emitting diodes [PLED] characterised by the electroluminescent [EL] layers specially adapted for multicolour light emission, e.g. for emitting white light
- H10K50/13—OLEDs or polymer light-emitting diodes [PLED] characterised by the electroluminescent [EL] layers specially adapted for multicolour light emission, e.g. for emitting white light comprising stacked EL layers within one EL unit
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- H—ELECTRICITY
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- 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
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Abstract
The invention discloses a display panel and a display device. The display panel includes: a first electrode and a second electrode which are oppositely arranged; a light emitting layer disposed between the first electrode and the second electrode, wherein the light emitting layer includes at least one first sub light emitting layer, at least one second sub light emitting layer, and at least one third sub light emitting layer; the first sub-luminescent layer is positioned between the first electrode and the second sub-luminescent layer, and the main body material of the first sub-luminescent layer is in a partial cavity type; the third sub-luminescent layer is positioned between the second electrode and the second sub-luminescent layer, and the main body material of the third sub-luminescent layer is in a bias electron type. The display panel can adjust the position of the exciton recombination zone, and the service life and the luminous efficiency of the display panel are improved.
Description
Technical Field
The embodiment of the invention relates to the technical field of display, in particular to a display panel and a display device.
Background
The Organic Light-Emitting Diode (OLED) display technology is a display technology with great development prospect, and a display panel manufactured by using the technology has the advantages of self-luminescence, ultra-lightness, thinness, wide viewing angle, high response speed, low power consumption, capability of realizing flexible display and the like, and is widely applied to the display field.
The pixel structure of the conventional display panel is a stacked structure of an anode, an organic light emitting material and a cathode, wherein the organic light emitting material is generally a single light emitting layer structure. However, the difference between the electron mobility and the hole mobility may cause the exciton recombination region not to be located at the center of the light emitting region, which may result in the decrease of the light emitting efficiency, and the lifetime of the display panel may also be shortened due to the bombardment of carriers on the interface of the organic film layer.
Disclosure of Invention
The invention provides a display panel and a display device, which can adjust the position of an exciton recombination zone and improve the service life and the luminous efficiency of the display panel.
In a first aspect, an embodiment of the present invention provides a display panel, including:
a first electrode and a second electrode which are oppositely arranged;
a light emitting layer disposed between the first electrode and the second electrode, wherein the light emitting layer includes at least one first sub light emitting layer, at least one second sub light emitting layer, and at least one third sub light emitting layer; the first sub-luminescent layer is positioned between the first electrode and the second sub-luminescent layer, and the main body material of the first sub-luminescent layer is in a partial cavity type; the third sub-luminescent layer is positioned between the second electrode and the second sub-luminescent layer, and the main body material of the third sub-luminescent layer is in a bias electron type.
Optionally, the light emitting layer includes a first sub light emitting layer, a second sub light emitting layer, and a third sub light emitting layer.
Optionally, the host material of the first sub-light emitting layer is a hole-type host material, and the host material of the third sub-light emitting layer is an electron-type host material.
Optionally, the host material of the first sub-emission layer includes a hole-type host material and an electron-type host material, and the proportion of the hole-type host material is greater than that of the electron-type host material; the host material of the third sub-emission layer includes a hole-type host material and an electron-type host material, and the proportion of the hole-type host material is smaller than that of the electron-type host material.
Optionally, the proportion of the hole-type host material in the first sub-light emitting layer gradually decreases and/or the proportion of the electron-type host material in the third sub-light emitting layer gradually increases in a direction in which the first electrode points to the second electrode.
Optionally, the light emitting layer includes at least two first sub light emitting layers, one second sub light emitting layer, and at least two third sub light emitting layers.
Optionally, the host materials of the first sub-light emitting layers include a hole-type host material and an electron-type host material, the proportion of the hole-type host material is greater than that of the electron-type host material, and the proportion of the hole-type host material in at least two layers of the first sub-light emitting layers is gradually reduced along the direction from the first electrode to the second electrode;
the host materials of the third sub-luminescent layers comprise hole type host materials and electron type host materials, the proportion of the hole type host materials is smaller than that of the electron type host materials, and the proportion of the electron type host materials in at least two layers of the third sub-luminescent layers is gradually increased along the direction from the first electrode to the second electrode.
Optionally, the host material of the first sub-light emitting layer close to the first electrode is a hole-type host material, the host materials of the remaining first sub-light emitting layers include a hole-type host material and an electron-type host material, the proportion of the hole-type host material is greater than that of the electron-type host material, and the proportion of the hole-type host material in the first sub-light emitting layer is gradually reduced along the direction from the first electrode to the second electrode;
the main body material of the third sub-luminescent layer close to the second electrode is an electron-type main body material, the main body materials of the rest third sub-luminescent layers comprise a hole-type main body material and an electron-type main body material, the proportion of the hole-type main body material is smaller than that of the electron-type main body material, and the proportion of the electron-type main body material in the third sub-luminescent layer is gradually increased along the direction from the first electrode to the second electrode.
Optionally, the method further includes:
a hole injection layer, a hole transport layer and an electron blocking layer which are arranged between the first electrode and the luminescent layer in sequence;
and the hole blocking layer, the electron transport layer and the electron injection layer are sequentially arranged between the light-emitting layer and the second electrode.
In a second aspect, an embodiment of the present invention further provides a display device, which includes a display panel having any one of the features of the first aspect.
The invention provides a display panel and a display device, wherein a luminescent layer is designed to comprise at least one first sub-luminescent layer, at least one second sub-luminescent layer and at least one third sub-luminescent layer. Because the first sub-luminescent layer is positioned between the first electrode and the second sub-luminescent layer, the main material of the first sub-luminescent layer is in a partial hole type, the hole transmission capability can be improved, and meanwhile, the excess electrons transmitted by the second electrode side are captured; the third sub-luminescent layer is positioned between the second electrode and the second sub-luminescent layer, and the main material of the third sub-luminescent layer is in a polarized electron type, so that the electron transmission capability can be improved, and meanwhile, excess holes transmitted by the first electrode side are captured. And then the position of the exciton recombination zone is adjusted, and the service life and the luminous efficiency of the display panel are improved.
Drawings
Fig. 1 is a schematic cross-sectional view illustrating a display panel according to an embodiment of the present invention;
fig. 2 is a schematic cross-sectional view of another display panel according to an embodiment of the invention;
fig. 3 is a schematic cross-sectional view of another display panel according to an embodiment of the invention.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings and examples. It is to be understood that the specific embodiments described herein are merely illustrative of the invention and are not limiting of the invention. It should be further noted that, for the convenience of description, only some of the structures related to the present invention are shown in the drawings, not all of the structures.
Also, the drawings and description of the embodiments are to be regarded as illustrative in nature, and not as restrictive. Like reference numerals refer to like elements throughout the specification. In addition, the thickness of some layers, films, panels, regions, etc. may be exaggerated in the drawings for understanding and ease of description. It will also be understood that when an element such as a layer, film, region, or substrate is referred to as being "on" another element, it can be directly on the other element or intervening elements may also be present. In addition, "on … …" means that an element is positioned on or under another element, but does not essentially mean that it is positioned on the upper side of the other element according to the direction of gravity. For ease of understanding, the figures of the present invention depict one element on top of another.
Additionally, unless explicitly described to the contrary, the word "comprise", and variations such as "comprises" or "comprising", will be understood to imply the inclusion of stated elements but not the exclusion of any other elements.
It should also be noted that references to "and/or" in embodiments of the invention are intended to include any and all combinations of one or more of the associated listed items. Various components are described in embodiments of the present invention with "first", "second", "third", and the like, but these components should not be limited by these terms. These terms are only used to distinguish one component from another. Also, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.
While certain embodiments may be practiced differently, the specific process sequence may be performed differently than described. For example, two processes described consecutively may be performed at substantially the same time or in an order reverse to that described.
The pixel structure of the conventional display panel is a stacked structure of an anode, an organic light emitting material and a cathode, wherein the organic light emitting material is generally a single light emitting layer structure. However, the difference between the electron mobility and the hole mobility may cause the exciton recombination region not to be located at the center of the light emitting region, which may result in the decrease of the light emitting efficiency, and the lifetime of the display panel may also be shortened due to the bombardment of carriers on the interface of the organic film layer. Therefore, embodiments of the present invention provide a display panel and a display device, which can adjust a position of an exciton recombination region, and improve a lifetime and a light emitting efficiency of the display panel.
Next, the structure of the display panel and its technical effects are described in detail.
An embodiment of the present invention provides a display panel, including: a first electrode and a second electrode which are oppositely arranged; a light emitting layer disposed between the first electrode and the second electrode, wherein the light emitting layer includes at least one first sub light emitting layer, at least one second sub light emitting layer, and at least one third sub light emitting layer; the first sub-luminescent layer is positioned between the first electrode and the second sub-luminescent layer, and the main body material of the first sub-luminescent layer is in a partial cavity type; the third sub-luminescent layer is positioned between the second electrode and the second sub-luminescent layer, and the main body material of the third sub-luminescent layer is in a bias electron type.
The structure of the light emitting layer mainly comprises any one of the following two scenes:
scene one, the light emitting layer includes a first sub light emitting layer, a second sub light emitting layer and a third sub light emitting layer.
In the first scenario, because only one layer is arranged on each of the first sub-light-emitting layer, the second sub-light-emitting layer and the third sub-light-emitting layer, the thickness of the light-emitting layer is easy to control in actual production, the position of an exciton recombination zone of the display panel is convenient to adjust, and the manufacturing process is simple.
And in a second scenario, the light emitting layer comprises at least two first sub light emitting layers, one second sub light emitting layer and at least two third sub light emitting layers.
Specifically, the light emitting layer includes at least two first sub-light emitting layers and at least two third sub-light emitting layers including, but not limited to, the following two cases:
a: the light emitting layer comprises N first sub light emitting layers and N third sub light emitting layers, wherein N is larger than or equal to 2.
B: the light-emitting layer comprises N first sub light-emitting layers and M third sub light-emitting layers, wherein N is larger than or equal to 2, M is larger than or equal to 2, and N is not equal to M.
In the second scenario, since the first sub-light emitting layer and the third sub-light emitting layer are of a multilayer structure, the accuracy of adjusting the position of the exciton recombination zone can be improved by designing the first sub-light emitting layer and the third sub-light emitting layer, so that the service life of the display panel is further prolonged, and the light emitting efficiency of the display panel is further improved.
In addition, the above scenarios are all exemplified by taking the second sub-light emitting layer as one layer, and in practical applications, the second sub-light emitting layer may also be a multi-layer structure, which is not particularly limited in the present invention. Meanwhile, in order to more clearly describe the light emitting layer in the display panel, the following drawings of the embodiments of the present invention correspondingly adjust the size of each structure in the display panel.
Fig. 1 is a schematic cross-sectional view illustrating a display panel according to an embodiment of the present invention. Illustratively, the display panel includes a first electrode 11 and a second electrode 12 disposed opposite to each other; and a light emitting layer 13 disposed between the first electrode 11 and the second electrode 12. Wherein the light emitting layer 13 includes a first sub-light emitting layer 131, a second sub-light emitting layer 132, and a third sub-light emitting layer 133; the first sub-emission layer 131 is positioned between the first electrode 11 and the second sub-emission layer 132, and the third sub-emission layer 133 is positioned between the second electrode 12 and the second sub-emission layer 132.
Optionally, the first electrode 11 is an anode and the second electrode 12 is a cathode. The material of the first electrode 11 comprises indium tin oxide or indium zinc oxide, the material of the second electrode 12 comprises a metal material or a metal alloy material, and the thickness of the metal film layer or the metal alloy film layer of the second electrode 12 is very thin, so that the second electrode 12 can exhibit semi-permeability to allow light to pass through. In the present invention, the materials of the first electrode 11 and the second electrode 12 include, but are not limited to, the above examples, and the relevant practitioner can select the materials of the first electrode 11 and the second electrode 12 according to the light emitting mode of the product, and the invention is not limited in particular.
Further, the display panel further includes: a hole injection layer 14 and a hole transport layer 15 which are provided in this order between the first electrode 11 and the light-emitting layer 13; an electron transport layer 16 and an electron injection layer 17 which are sequentially disposed between the light emitting layer 13 and the second electrode 12.
Optionally, the display panel further includes: an electron blocking layer 18 provided between the hole transport layer 15 and the light emitting layer 13; and a hole blocking layer 19 disposed between the light-emitting layer 13 and the electron transport layer 16.
The host material of the first sub-emission layer 131 is hole-biased type, and the host material of the third sub-emission layer 133 is electron-biased type. Generally, the main material has a good electron or hole transport property, the main material is in a partial hole type, which means that the main material is biased to the hole transport property between the electron transport property and the hole transport property, and the main material in the partial hole type is beneficial to improving the injection transport property of holes and limiting electron transport; the main body material is in a bias electron type, which means that the main body material is biased to an electron transport property between the electron transport property and a hole transport property, and the bias electron type main body material is beneficial to improving the injection transport property of electrons and limiting hole transport.
It is to be understood that the host material and the hole transport type material (e.g., at least one of the hole injection layer 14, the hole transport layer 15, and the electron blocking layer 18) in the form of a partial hole, the host material and the electron transport type material (e.g., at least one of the electron transport layer 16, the electron injection layer 17, and the hole blocking layer 19) in the form of a partial electron, and both of them may be selected from the same materials in terms of material use. However, from the viewpoint of overall performance of the device, more factors such as mobility and energy level matching may be considered, and therefore, the preferred collocation is to select different materials from two groups.
In addition, in order to ensure that the light-emitting layer 13 emits light normally, the light-emitting layer 13 includes a guest material in addition to any of the host materials described above. In this embodiment, the guest material used in the light-emitting layer 13 is not particularly limited, and may be, for example, a phosphorescent material, a fluorescent material, or a mixture of a phosphorescent material and a fluorescent material.
In one possible implementation, the host material of the first sub-light-emitting layer 131 is selected to be a hole-type host material (i.e., a host material having a better hole-transporting property), and the host material of the third sub-light-emitting layer 133 is selected to be an electron-type host material (i.e., a host material having a better electron-transporting property). In this way, the first sub-light emitting layer 131 can improve the injection transport capability of holes, and capture electrons that are transported excessively on the cathode side (i.e., limit the electron transport); the third sub-light emitting layer 133 can improve the injection transport capability of electrons and capture the holes transported in excess on the anode side (i.e., limit the hole transport). Therefore, the exciton recombination zone is limited at the position of the second sub-luminescent layer 132 (namely, close to the center of the luminescent layer 13), the bombardment of excitons on the electron blocking layer 18/luminescent layer 13 interface and the hole blocking layer 19/luminescent layer 13 interface is reduced, and the service life and the luminous efficiency of the display panel are improved.
Alternatively, the void type host material may include, but is not limited to, the following materials: organic derivatives containing triarylamines and carbazole groups, such as CBP, NBP, mCP (conventional materials), and the like; the electronic host material may include, but is not limited to, the following: organic derivatives containing triazine, pyridine, pyrimidine group, such as BCP, TPBi, TCNQ (conventional material), etc.
In another possible implementation, the host material of the first sub-emitting layer 131 includes a hole-type host material (i.e., a host material with a better hole transport property) and an electron-type host material (i.e., a host material with a better electron transport property), and the proportion of the hole-type host material is greater than that of the electron-type host material, so that the property of the host material of the first sub-emitting layer 131 is hole-biased, and the first sub-emitting layer 131 can improve the injection transport capability of holes and capture the electrons that are transported to the cathode side (i.e., limit the electron transport); similarly, the host material of the third sub-luminescent layer 133 includes a hole-type host material and an electron-type host material, and the ratio of the hole-type host material is smaller than that of the electron-type host material, so that the host material of the third sub-luminescent layer 133 is of a biased electron type, and the third sub-luminescent layer 133 can improve the injection and transport capability of electrons and capture the excess holes transported on the anode side (i.e., limit the hole transport). Therefore, the exciton recombination zone is limited at the position of the second sub-luminescent layer 132 (namely, close to the center of the luminescent layer 13), the bombardment of excitons on the electron blocking layer 18/luminescent layer 13 interface and the hole blocking layer 19/luminescent layer 13 interface is reduced, and the service life and the luminous efficiency of the display panel are improved.
Hole-type host material: the range of values for the electron-type host material may be from 0:1 to 1: 0. Illustratively, when the proportion of the hole-type host material is smaller than that of the electron-type host material, the hole-type host material: electronic host material is 3:7 or 4: 6; when the proportion of the hole-type host material is larger than that of the electron-type host material, the ratio of the hole-type host material: the electronic host material is 6:4 or 7: 3.
It should be noted that the proportion of the materials mentioned in the embodiment of the present invention may be a mass ratio or a volume ratio, and may be specifically selected according to a practical production situation, and the embodiment of the present invention is not particularly limited thereto.
Alternatively, the proportion of the hole-type host material in the first sub-emission layer 131 gradually decreases and/or the proportion of the electron-type host material in the third sub-emission layer 133 gradually increases in a direction in which the first electrode 11 is directed to the second electrode 12. Wherein the proportion of the hole-type host material in the first sub-emission layer 131 is gradually decreased to ensure the transport rate of holes in the first sub-emission layer 131; the proportion of the electron-type host material in the third sub light-emitting layer 133 is gradually increased to secure the transport rate of electrons in the third sub light-emitting layer 133.
The thicknesses of the first, second, and third sub-light emitting layers 131, 132, and 133 may be design-selected according to actual requirements. In order to secure the microcavity thickness of the display panel, the overall thickness of the light-emitting layer 13 is generally designed to be about 40 nm. So as to avoid uneven doping of the hole type main body material and the electron type main body material in the sub-luminescent layer and unevenness of the film layer, and simultaneously avoid the influence of too thick film layer on the whole thickness of the display panel.
In addition, the light-emitting layer 13 may be formed by an evaporation process, one evaporation source being used for placing a hole-type host material, and the other evaporation source being used for placing an electron-type host material.
When the first sub-light emitting layer 131 selects a hole type host material and the third sub-light emitting layer 133 selects an electron type host material, an evaporation source in which the hole type host material is placed is turned on when the first sub-light emitting layer 131 is formed, and an evaporation source in which the electron type host material is placed is turned on when the third sub-light emitting layer 133 is formed.
When the host materials of the first and third sub-light emitting layers 131 and 133 each include a hole-type host material and an electron-type host material, the angle of the angle limiting plate and the evaporation rate may be controlled to control the ratio of the hole-type host material and the electron-type host material when the first and third sub-light emitting layers 131 and 133 are respectively evaporated, so that the ratio adjustment of the hole-type host material and the electron-type host material may be realized. Illustratively, the adjustment of the ratio of the hole-type host material in the first sub-emission layer 131 is described by taking the adjustment of the evaporation rate as an example. When the ratio of the hole-type host material in the first sub-light-emitting layer 131 is gradually decreased, the evaporation rate of the evaporation source in which the hole-type host material is placed may be controlled to decrease, and/or the evaporation rate of the evaporation source in which the electron-type host material is placed may be controlled to increase, so that the evaporation rate of the hole-type host material decreases and the evaporation rate of the electron-type host material increases, and thus the ratio of the hole-type host material may be gradually decreased within the same evaporation time. Similarly, the evaporation method for increasing the proportion of the electron-type host material in the third sub-luminescent layer 133 is similar to that described above, and for brevity, the description thereof is omitted here.
Fig. 2 is a schematic cross-sectional view illustrating another display panel according to an embodiment of the present invention. Illustratively, the display panel includes a first electrode 11 and a second electrode 12 disposed opposite to each other; and a light emitting layer 13 disposed between the first electrode 11 and the second electrode 12. Wherein the light emitting layer 13 includes two first sub-light emitting layers 131 (respectively denoted as 131a and 131b in fig. 2), one second sub-light emitting layer 132, and two third sub-light emitting layers 133 (respectively denoted as 133a and 133b in fig. 2); the first sub-emission layer 131 is positioned between the first electrode 11 and the second sub-emission layer 132, and the third sub-emission layer 133 is positioned between the second electrode 12 and the second sub-emission layer 132.
Optionally, the first electrode 11 is an anode and the second electrode 12 is a cathode. The material of the first electrode 11 comprises indium tin oxide or indium zinc oxide, the material of the second electrode 12 comprises a metal material or a metal alloy material, and the thickness of the metal film layer or the metal alloy film layer of the second electrode 12 is very thin, so that the second electrode 12 can exhibit semi-permeability to allow light to pass through. In the present invention, the materials of the first electrode 11 and the second electrode 12 include, but are not limited to, the above examples, and the relevant practitioner can select the materials of the first electrode 11 and the second electrode 12 according to the light emitting mode of the product, and the invention is not limited in particular.
Further, the display panel further includes: a hole injection layer 14 and a hole transport layer 15 which are provided in this order between the first electrode 11 and the light-emitting layer 13; an electron transport layer 16 and an electron injection layer 17 which are sequentially disposed between the light emitting layer 13 and the second electrode 12.
Optionally, the display panel further includes: an electron blocking layer 18 provided between the hole transport layer 15 and the light emitting layer 13; and a hole blocking layer 19 disposed between the light-emitting layer 13 and the electron transport layer 16.
The host material of the first sub-emission layer 131 is hole-biased type, and the host material of the third sub-emission layer 133 is electron-biased type. Generally, the main material has a good electron or hole transport property, the main material is in a partial hole type, which means that the main material is biased to the hole transport property between the electron transport property and the hole transport property, and the main material in the partial hole type is beneficial to improving the injection transport property of holes and limiting electron transport; the main body material is in a bias electron type, which means that the main body material is biased to an electron transport property between the electron transport property and a hole transport property, and the bias electron type main body material is beneficial to improving the injection transport property of electrons and limiting hole transport.
It is to be understood that the host material and the hole transport type material (e.g., at least one of the hole injection layer 14, the hole transport layer 15, and the electron blocking layer 18) in the form of a partial hole, the host material and the electron transport type material (e.g., at least one of the electron transport layer 16, the electron injection layer 17, and the hole blocking layer 19) in the form of a partial electron, and both of them may be selected from the same materials in terms of material use. However, from the viewpoint of overall performance of the device, more factors such as mobility and energy level matching may be considered, and therefore, the preferred collocation is to select different materials from two groups.
In addition, in order to ensure that the light-emitting layer 13 emits light normally, the light-emitting layer 13 includes a guest material in addition to any of the host materials described above. In this embodiment, the guest material used in the light-emitting layer 13 is not particularly limited, and may be, for example, a phosphorescent material, a fluorescent material, or a mixture of a phosphorescent material and a fluorescent material.
In one possible implementation scheme, the host material of the first sub-light-emitting layer 131 includes a hole-type host material and an electron-type host material, and the proportion of the hole-type host material is greater than that of the electron-type host material, so that the host material of the first sub-light-emitting layer 131 is of a hole-biased type, and the first sub-light-emitting layer 131 can improve the injection and transport capabilities of holes and capture (i.e., limit) electrons that are transported excessively on the cathode side. The occupation ratio of the hole-type host material in the two first sub-light emitting layers 131 gradually decreases in the direction from the first electrode 11 toward the second electrode 12 (i.e., the occupation ratio of the hole-type host material in 131a is greater than that of the hole-type host material in 131b, for example, 7:3 for the hole-type host material in 131a and 6:4 for the electron-type host material in 131b), so as to ensure the transport rate of holes in the first sub-light emitting layers 131.
The host material of the third sub-luminescent layer 133 includes a hole-type host material and an electron-type host material, and the ratio of the hole-type host material is smaller than that of the electron-type host material, so that the host material of the third sub-luminescent layer 133 is electron-biased, and the third sub-luminescent layer 133 can improve the injection and transport capability of electrons and capture the excess holes transported on the anode side (i.e., limit the hole transport). The occupation ratio of the electron-type host materials in the two third sub-light emitting layers 133 is gradually increased along the direction from the first electrode 11 to the second electrode 12 (i.e., the occupation ratio of the electron-type host materials in 133a is smaller than that of the electron-type host materials in 133b, for example, the hole-type host materials: electron-type host materials: 4:6 in 133a, and the hole-type host materials: electron-type host materials: 3:7 in 133b) to ensure the electron transport rate in the third sub-light emitting layers 133.
Alternatively, the void type host material may include, but is not limited to, the following materials: organic derivatives containing triarylamines and carbazole groups, such as CBP, NBP, mCP (conventional materials), and the like; the electronic host material may include, but is not limited to, the following: organic derivatives containing triazine, pyridine, pyrimidine group, such as BCP, TPBi, TCNQ (conventional material), etc.
The structure can limit the exciton recombination zone at the position of the second sub-luminescent layer 132 (namely, close to the center of the luminescent layer 13), reduce the bombardment of excitons on the electron blocking layer 18/luminescent layer 13 interface and the hole blocking layer 19/luminescent layer 13 interface, and improve the service life and the luminous efficiency of the display panel.
In addition, the light-emitting layer 13 may be formed by an evaporation process, one evaporation source being used for placing a hole-type host material, and the other evaporation source being used for placing an electron-type host material. Since the host materials of the first and third sub-light emitting layers 131 and 133 each include a hole type host material and an electron type host material, the angles and evaporation rates of the angle limiting plates can be controlled to evaporate 131a, 131b, 133a, and 133b, respectively, according to the occupation ratios of the hole type host material and the electron type host material in 131a, 131b, 133a, and 133b, respectively.
Fig. 3 is a schematic cross-sectional view illustrating a display panel according to another embodiment of the present invention. Illustratively, the display panel includes a first electrode 11 and a second electrode 12 disposed opposite to each other; and a light emitting layer 13 disposed between the first electrode 11 and the second electrode 12. Wherein the light emitting layer 13 includes three first sub-light emitting layers 131 (respectively denoted as 131a, 131b, and 131c in fig. 3), one second sub-light emitting layer 132, and three third sub-light emitting layers 133 (respectively denoted as 133a, 133b, and 133c in fig. 3); the first sub-emission layer 131 is positioned between the first electrode 11 and the second sub-emission layer 132, and the third sub-emission layer 133 is positioned between the second electrode 12 and the second sub-emission layer 132.
Optionally, the first electrode 11 is an anode and the second electrode 12 is a cathode. The material of the first electrode 11 comprises indium tin oxide or indium zinc oxide, the material of the second electrode 12 comprises a metal material or a metal alloy material, and the thickness of the metal film layer or the metal alloy film layer of the second electrode 12 is very thin, so that the second electrode 12 can exhibit semi-permeability to allow light to pass through. In the present invention, the materials of the first electrode 11 and the second electrode 12 include, but are not limited to, the above examples, and the relevant practitioner can select the materials of the first electrode 11 and the second electrode 12 according to the light emitting mode of the product, and the invention is not limited in particular.
Further, the display panel further includes: a hole injection layer 14 and a hole transport layer 15 which are provided in this order between the first electrode 11 and the light-emitting layer 13; an electron transport layer 16 and an electron injection layer 17 which are sequentially disposed between the light emitting layer 13 and the second electrode 12.
Optionally, the display panel further includes: an electron blocking layer 18 provided between the hole transport layer 15 and the light emitting layer 13; and a hole blocking layer 19 disposed between the light-emitting layer 13 and the electron transport layer 16.
The host material of the first sub-emission layer 131 is hole-biased type, and the host material of the third sub-emission layer 133 is electron-biased type. Generally, the main material has a good electron or hole transport property, the main material is in a partial hole type, which means that the main material is biased to the hole transport property between the electron transport property and the hole transport property, and the main material in the partial hole type is beneficial to improving the injection transport property of holes and limiting electron transport; the main body material is in a bias electron type, which means that the main body material is biased to an electron transport property between the electron transport property and a hole transport property, and the bias electron type main body material is beneficial to improving the injection transport property of electrons and limiting hole transport.
It is to be understood that the host material and the hole transport type material (e.g., at least one of the hole injection layer 14, the hole transport layer 15, and the electron blocking layer 18) in the form of a partial hole, the host material and the electron transport type material (e.g., at least one of the electron transport layer 16, the electron injection layer 17, and the hole blocking layer 19) in the form of a partial electron, and both of them may be selected from the same materials in terms of material use. However, from the viewpoint of overall performance of the device, more factors such as mobility and energy level matching may be considered, and therefore, the preferred collocation is to select different materials from two groups.
In addition, in order to ensure that the light-emitting layer 13 emits light normally, the light-emitting layer 13 includes a guest material in addition to any of the host materials described above. In this embodiment, the guest material used in the light-emitting layer 13 is not particularly limited, and may be, for example, a phosphorescent material, a fluorescent material, or a mixture of a phosphorescent material and a fluorescent material.
In one possible implementation scheme, the host material of the first sub-light emitting layer (i.e., 131a) close to the first electrode 11 is a hole-type host material, and the host materials of the remaining first sub-light emitting layers (i.e., 131b and 131c) include a hole-type host material and an electron-type host material, and the proportion of the hole-type host material is greater than that of the electron-type host material, so that the host material of the first sub-light emitting layer 131 is of a partial hole type, and the first sub-light emitting layer 131 can improve the injection transport capability of holes and capture the excess electrons transported on the cathode side (i.e., limit the electron transport). The occupation ratio of the hole-type host material in the first sub-light-emitting layer 131 gradually decreases in the direction from the first electrode 11 toward the second electrode 12 (i.e., the occupation ratio of the hole-type host material in 131a is greater than that of the hole-type host material in 131b, and the occupation ratio of the hole-type host material in 131b is greater than that of the hole-type host material in 131c, for example, the hole-type host material: electron-type host material in 131a is 1:0, the hole-type host material: electron-type host material in 131b is 7:3, and the hole-type host material: electron-type host material in 131c is 6:4), so as to ensure the transport rate of holes in the first sub-light-emitting layer 131.
The host material of the third sub-emitting layer (i.e., 133c) close to the second electrode 12 is an electron-type host material, and the host materials of the remaining third sub-emitting layers (i.e., 133a and 133b) include a hole-type host material and an electron-type host material, and the proportion of the hole-type host material is smaller than that of the electron-type host material, so that the host material of the third sub-emitting layer 133 is electron-biased, and the third sub-emitting layer 133 can improve the injection and transport capabilities of electrons and capture the excess holes transported on the anode side (i.e., limit the hole transport). The occupation ratio of the electron-type host material in the third sub-light emitting layer 133 gradually increases in a direction in which the first electrode 11 is directed toward the second electrode 12 (i.e., the occupation ratio of the electron-type host material in 133a is smaller than that of the electron-type host material in 133b, and the occupation ratio of the electron-type host material in 133b is smaller than that of the electron-type host material in 133c, for example, the hole-type host material: the electron-type host material in 133a is 4:6, the hole-type host material: the electron-type host material in 133b is 3:7, and the hole-type host material: the electron-type host material in 133c is 0:1), so as to ensure the transport rate of electrons in the third sub-light emitting layer 133.
Alternatively, the void type host material may include, but is not limited to, the following materials: organic derivatives containing triarylamines and carbazole groups, such as CBP, NBP, mCP (conventional materials), and the like; the electronic host material may include, but is not limited to, the following: organic derivatives containing triazine, pyridine, pyrimidine group, such as BCP, TPBi, TCNQ (conventional material), etc.
The structure can limit the exciton recombination zone at the position of the second sub-luminescent layer 132 (namely, close to the center of the luminescent layer 13), reduce the bombardment of excitons on the electron blocking layer 18/luminescent layer 13 interface and the hole blocking layer 19/luminescent layer 13 interface, and improve the service life and the luminous efficiency of the display panel.
An embodiment of the present invention provides a display panel, including: a first electrode and a second electrode which are oppositely arranged; a light emitting layer disposed between the first electrode and the second electrode, wherein the light emitting layer includes at least one first sub light emitting layer, at least one second sub light emitting layer, and at least one third sub light emitting layer; the first sub-luminescent layer is positioned between the first electrode and the second sub-luminescent layer, and the main body material of the first sub-luminescent layer is in a partial cavity type; the third sub-luminescent layer is positioned between the second electrode and the second sub-luminescent layer, and the main body material of the third sub-luminescent layer is in a bias electron type. The light emitting layer is designed such that the light emitting layer includes at least one first sub light emitting layer, at least one second sub light emitting layer, and at least one third sub light emitting layer. Because the first sub-luminescent layer is positioned between the first electrode and the second sub-luminescent layer, the main material of the first sub-luminescent layer is in a partial hole type, the hole transmission capability can be improved, and meanwhile, the excess electrons transmitted by the second electrode side are captured; the third sub-luminescent layer is positioned between the second electrode and the second sub-luminescent layer, and the main material of the third sub-luminescent layer is in a polarized electron type, so that the electron transmission capability can be improved, and meanwhile, excess holes transmitted by the first electrode side are captured. And then the position of the exciton recombination zone is adjusted, and the service life and the luminous efficiency of the display panel are improved.
Embodiments of the present invention also provide a display device including a display panel having any of the features described in the above embodiments.
The display panel may be a flexible display panel or a non-flexible display panel. The light emitting mode of the display panel may be top emission, bottom emission, or both-side emission.
The display device provided by the embodiment of the invention can be applied to intelligent wearable equipment (such as an intelligent bracelet and an intelligent watch) and also can be applied to equipment such as an intelligent mobile phone, a tablet personal computer and a display.
It is to be noted that the foregoing is only illustrative of the preferred embodiments of the present invention and the technical principles employed. It will be understood by those skilled in the art that the present invention is not limited to the particular embodiments described herein, but is capable of various obvious changes, rearrangements and substitutions as will now become apparent to those skilled in the art without departing from the scope of the invention. Therefore, although the present invention has been described in greater detail by the above embodiments, the present invention is not limited to the above embodiments, and may include other equivalent embodiments without departing from the spirit of the present invention, and the scope of the present invention is determined by the scope of the appended claims.
Claims (10)
1. A display panel, comprising:
a first electrode and a second electrode which are oppositely arranged;
a light emitting layer disposed between the first electrode and the second electrode, wherein the light emitting layer includes at least one first sub light emitting layer, at least one second sub light emitting layer, and at least one third sub light emitting layer; the first sub-light-emitting layer is positioned between the first electrode and the second sub-light-emitting layer, and the main body material of the first sub-light-emitting layer is of a partial cavity type; the third sub-luminescent layer is positioned between the second electrode and the second sub-luminescent layer, and the main body material of the third sub-luminescent layer is in a bias electron type.
2. The display panel according to claim 1, wherein the light-emitting layer comprises one layer of the first sub light-emitting layer, one layer of the second sub light-emitting layer, and one layer of the third sub light-emitting layer.
3. The display panel according to claim 2, wherein the host material of the first sub-emission layer is a hole-type host material, and the host material of the third sub-emission layer is an electron-type host material.
4. The display panel according to claim 2, wherein the host material of the first sub-emission layer includes a hole-type host material and an electron-type host material, and a proportion of the hole-type host material is larger than a proportion of the electron-type host material; the host material of the third sub-luminescent layer comprises a hole type host material and an electron type host material, and the proportion of the hole type host material is smaller than that of the electron type host material.
5. The display panel according to claim 4, wherein a ratio of the hole-type host material in the first sub-emission layer is gradually decreased and/or a ratio of the electron-type host material in the third sub-emission layer is gradually increased in a direction in which the first electrode is directed to the second electrode.
6. The display panel according to claim 1, wherein the light emitting layer comprises at least two layers of the first sub light emitting layer, one layer of the second sub light emitting layer, and at least two layers of the third sub light emitting layer.
7. The display panel according to claim 6, wherein the host material of the first sub-emission layer comprises a hole-type host material and an electron-type host material, and the proportion of the hole-type host material is larger than that of the electron-type host material, and the proportion of the hole-type host material in at least two layers of the first sub-emission layer gradually decreases in a direction from the first electrode to the second electrode;
the main body materials of the third sub-luminescent layers comprise hole type main body materials and electron type main body materials, the occupation ratio of the hole type main body materials is smaller than that of the electron type main body materials, and the occupation ratios of the electron type main body materials in at least two layers of the third sub-luminescent layers are gradually increased along the direction from the first electrode to the second electrode.
8. The display panel according to claim 6, wherein the host material of the first sub-emission layer adjacent to the first electrode is a hole-type host material, the host materials of the remaining first sub-emission layers include a hole-type host material and an electron-type host material, and a ratio of the hole-type host material is larger than a ratio of the electron-type host material, and the ratio of the hole-type host material in the first sub-emission layer gradually decreases in a direction from the first electrode to the second electrode;
the main body material of the third sub-luminescent layer close to the second electrode is an electron-type main body material, the main body materials of the rest of the third sub-luminescent layers comprise a hole-type main body material and an electron-type main body material, the proportion of the hole-type main body material is smaller than that of the electron-type main body material, and the proportion of the electron-type main body material in the third sub-luminescent layer is gradually increased along the direction from the first electrode to the second electrode.
9. The display panel according to any one of claims 1 to 8, further comprising:
a hole injection layer, a hole transport layer and an electron blocking layer which are sequentially arranged between the first electrode and the light-emitting layer;
and the hole blocking layer, the electron transport layer and the electron injection layer are sequentially arranged between the light-emitting layer and the second electrode.
10. A display device characterized by comprising the display panel according to any one of claims 1 to 9.
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Application publication date: 20191231 |