CN110854282A - Organic light-emitting diode, organic light-emitting display substrate, preparation method and display device - Google Patents
Organic light-emitting diode, organic light-emitting display substrate, preparation method and display device Download PDFInfo
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Abstract
The invention discloses an organic light-emitting diode, an organic light-emitting display substrate, a preparation method and a display device. The organic light emitting diode includes: a first electrode; a hole transport layer; a light emitting layer; an electron-regulating layer on a side of the light-emitting layer remote from the hole-transporting layer, the electron-regulating layer configured to reduce a transport rate of electrons; an electron transport layer; and the second electrode is positioned on one side of the electron transmission layer far away from the electron regulation layer. Therefore, the organic light-emitting diode can moderately reduce the transmission rate of electrons, prevent the balance of electrons and holes from being broken due to the fact that holes are difficult to inject into a light-emitting layer after long-term use, and further relieve the influence of material degradation on light emission after long-term use of a light-emitting device.
Description
Technical Field
The invention relates to the field of display, in particular to an organic light-emitting diode, an organic light-emitting display substrate, a preparation method and a display device.
Background
Organic Light Emitting Devices (OLEDs) have the advantages of high efficiency, high brightness, low driving voltage, fast response speed, and capability of realizing large-area photoelectric display, and are increasingly applied to the display field. With the development of electronic technology, the requirements of electronic devices such as mobile phones on the power consumption of display components are becoming more stringent, so that electroluminescent devices (EL devices, such as OLEDs) are required to have higher luminous efficiency. For this reason, in the current EL device, an Electron Transport Layer (ETL) is often formed using an electron transport material having a high electron mobility.
However, the current organic light emitting diode, organic light emitting display substrate, manufacturing method thereof and display device still need to be improved.
Disclosure of Invention
In the related art, the OLED-based display device is prone to white frame color shift after long-term use. This is mainly due to the phenomenon of non-uniform drop in RGB efficiency after long-term use of the device. This phenomenon is particularly pronounced at low grey levels. Especially, in the blue device, the luminance drop is particularly serious at low gray scale than at high gray scale. Therefore, the light emitting efficiency of R (red), G (green), and B (blue) is not uniform at a low gray scale, and the white screen exhibits color shift. The inventors have found that this is mainly due to the poor electron stability of the hole transport layer after using a hole transport material having a high transport rate, and that slow cleavage easily occurs at the interface between the hole transport layer and the light emitting layer. Therefore, holes are difficult to inject into the light-emitting layer under low gray scale after long-term use, the balance of the holes and electrons is broken, electrons of the device are excessive, and the efficiency of the device is seriously reduced under low gray scale. Particularly, the electron blocking layer of the blue light device is very thin, so that the influence of material degradation on light emission is greater after the blue light device is used for a long time, resulting in non-uniformity in the decrease of RGB efficiency at low gray scale.
The present invention aims to alleviate or solve at least to some extent at least one of the above mentioned problems.
In view of the above, in one aspect of the present invention, an organic light emitting diode for display is provided. The organic light emitting diode includes: a first electrode; a hole transport layer on one side of the first electrode; the light-emitting layer is positioned on one side, far away from the first electrode, of the hole transport layer; an electron-regulating layer on a side of the light-emitting layer remote from the hole-transporting layer, the electron-regulating layer configured to reduce a transport rate of electrons; the electron transport layer is positioned on one side, far away from the light emitting layer, of the electron adjusting layer; and the second electrode is positioned on one side of the electron transmission layer far away from the electron regulation layer. Therefore, the organic light-emitting diode can moderately reduce the transmission rate of electrons, prevent the balance of electrons and holes from being broken due to the fact that holes are difficult to inject into a light-emitting layer after long-term use, and further relieve the influence of material degradation on light emission after long-term use of a light-emitting device.
According to the embodiment of the invention, when the organic light emitting diode is used for displaying, multi-level gray scale display can be realized, the gray scale comprises L0-L255, and the material forming the electronic regulation layer is configured to reduce the transmission rate of electrons when the gray scale is less than or equal to L16. Therefore, the defect of color cast of the white picture under low gray scale can be relieved.
According to the embodiment of the invention, the material forming the electron adjusting layer is configured to keep the transmission rate of the electrons from being reduced when the gray scale is larger than L16. Therefore, the luminous efficiency of the device can be prevented from being hatched under high gray scale.
According to an embodiment of the present invention, a material forming the electron-adjusting layer includes at least one of an azole compound, a quinine derivative, a quinoxaline derivative, and a diazaanthracene derivative. This can further improve the performance of the electron control layer.
According to an embodiment of the present invention, the organic light emitting diode further comprises at least one of the following structures: an electron injection layer between the second electrode and the electron transport layer; a hole blocking layer located between the light emitting layer and the electron adjusting layer; an electron blocking layer between the light emitting layer and the hole transport layer; a hole transport auxiliary layer between the hole transport layer and the first electrode; the metal reflecting layer is positioned on one side of the first electrode, which is far away from the light emitting layer; and the light extraction layer is positioned on one side of the second electrode, which is far away from the light-emitting layer. Thereby, the performance of the organic light emitting diode can be further improved.
According to an embodiment of the present invention, the hole transport auxiliary layer is formed by P-type doping of a material forming the hole transport layer. Therefore, the interface state between the first electrode and the hole transport layer can be improved, and the capability of injecting holes into the light emitting layer is improved.
According to an embodiment of the present invention, the light emitting layer is a blue light emitting layer. Thereby, the performance of the organic light emitting diode can be further improved.
In yet another aspect of the present invention, an organic light emitting display substrate is provided. The organic light emitting display substrate comprises a plurality of organic light emitting diodes with different light emitting colors, and at least one of the organic light emitting diodes is the same as the organic light emitting diode. Therefore, the organic light emitting display substrate has all the features and advantages of the organic light emitting diode described above, and thus, the description thereof is omitted. In general, after the organic light-emitting display substrate is used for a period of time, the problem that the white picture is prone to color cast under low gray scale can be relieved.
According to an embodiment of the present invention, an organic light emitting display substrate includes: the organic light emitting diode comprises a red organic light emitting diode, a green organic light emitting diode and a blue organic light emitting diode, wherein the blue organic light emitting diode is the organic light emitting diode, light emitting layers of the red organic light emitting diode, the green organic light emitting diode and the blue organic light emitting diode are arranged on the same layer, and the red organic light emitting diode, the green organic light emitting diode and the blue organic light emitting diode share an electron transport layer and a hole transport layer. Thus, the performance of the organic light emitting display substrate can be improved.
According to an embodiment of the present invention, an orthographic projection of the electron-adjusting layer of the blue organic light emitting diode on the first electrode covers an orthographic projection of the light emitting layer of the red organic light emitting diode on the first electrode, an orthographic projection of the light emitting layer of the green organic light emitting diode on the first electrode, and an orthographic projection of the light emitting layer of the blue organic light emitting diode on the first electrode. Thus, the performance of the organic light emitting display substrate can be improved.
According to an embodiment of the present invention, an orthographic projection of the electron-adjusting layer of the blue organic light emitting diode on the second electrode coincides with an orthographic projection of the light emitting layer of the blue organic light emitting diode on the second electrode.
In still another aspect of the present invention, the present invention provides a method of preparing the organic light emitting display substrate described above, the method comprising: a plurality of organic light emitting diodes not all having the same emission color are formed, and an electron adjusting layer is formed between a light emitting layer and an electron transporting layer when at least one of the organic light emitting diodes is formed. The method can simply and conveniently obtain the organic light-emitting display substrate, and the prepared organic light-emitting display substrate can relieve the problem that a white picture is easy to have color cast under low gray scale after being used for a period of time.
According to an embodiment of the present invention, the method includes forming a first electrode; forming a blue light emitting layer, a red light emitting layer and a green light emitting layer on one side of the first electrode, wherein the blue light emitting layer, the red light emitting layer and the green light emitting layer are arranged in the same layer; and forming the electronic regulation layer on the side of the blue light-emitting layer far away from the first electrode by using a fine metal mask. Therefore, the electron transmission rate of the blue light-emitting diode can be regulated.
According to an embodiment of the present invention, the method includes forming a first electrode; forming a blue light emitting layer, a red light emitting layer and a green light emitting layer on one side of the first electrode, wherein the blue light emitting layer, the red light emitting layer and the green light emitting layer are arranged in the same layer; the electronic adjusting layer is formed on one side of the blue light emitting layer far away from the first electrode, and the orthographic projection of the electronic adjusting layer on the first electrode covers the orthographic projection of the red light emitting layer on the first electrode, the orthographic projection of the green light emitting layer on the first electrode and the orthographic projection of the blue light emitting layer on the first electrode. Therefore, the manufacturing process of the method can be simplified, and the use times of the mask plate can be reduced.
In yet another aspect of the present invention, a display device is provided. The display device includes the organic light emitting display substrate described above. The display device has all the characteristics and advantages of the display substrate described above, and thus, the description thereof is omitted. In general, the display device can relieve the problem that the white picture is easy to have color cast under low gray scale after being used for a period of time.
Drawings
The above and/or additional aspects and advantages of the present invention will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:
fig. 1 shows a schematic structural view of an organic light emitting diode according to an embodiment of the present invention;
fig. 2 shows a schematic structural view of an organic light emitting diode according to another embodiment of the present invention;
fig. 3 shows a schematic structural view of an organic light emitting display substrate according to an embodiment of the present invention;
fig. 4 shows a schematic structural view of an organic light emitting display substrate according to another embodiment of the present invention;
fig. 5 is a graph showing a current density test result of an organic light emitting diode according to a comparative example of the present invention;
fig. 6 is a graph showing a current density test result of an organic light emitting diode according to an embodiment of the present invention.
Detailed Description
Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the accompanying drawings are illustrative only for the purpose of explaining the present invention, and are not to be construed as limiting the present invention.
In one aspect of the present invention, an organic light emitting diode for display is provided. Referring to fig. 1, the organic light emitting diode includes a first electrode 100, a second electrode 200, and a light emitting layer 300, a hole transport layer 400, and an electron transport layer 500 between the first electrode 100 and the second electrode 200. The hole transport layer 400 is positioned between the light emitting layer 300 and the first electrode 100, and the electron transport layer 500 is positioned between the light emitting layer 300 and the second electrode 200. An electron adjusting layer 600 is provided between the light emitting layer 300 and the electron transport layer 500. Also, the electron regulation layer 600 is configured to reduce the transport rate of electrons. Therefore, the organic light-emitting diode can moderately reduce the transmission rate of electrons, prevent the balance of electrons and holes from being broken due to the fact that holes are difficult to inject into a light-emitting layer after long-term use, and further relieve the influence of material degradation on light emission after long-term use of a light-emitting device.
In the present invention, the first electrode and the second electrode are only used for distinguishing two electrodes in the organic light emitting diode. The first electrode and the second electrode are one of an anode and the other of a cathode, and the positions of the two electrodes are not particularly limited and may be interchanged. For example, the first electrode may be an anode and the second electrode may be a cathode. The electron transport layer 500 and the electron adjusting layer 600 are located between the cathode and the light emitting layer. The light emitting direction of the organic light emitting diode is not particularly limited, for example, the light emitting direction of the organic light emitting diode may be from the second electrode 200 side, for example, above the marked position in fig. 1.
For convenience of understanding, the following first briefly explains the principle that the organic light emitting diode according to the embodiment of the present invention can achieve the above-mentioned advantageous effects:
as described above, the color cast and other defects of the white picture in the low gray scale are mainly caused by the balance between holes and electrons in the light emitting layer in the low gray scale after long-term use. The electron stability of the hole transport layer of the organic light-emitting device is poor, the electron blocking layer is very thin, and particularly, the balance between holes and electrons of the light-emitting layer is easily broken under the condition of low gray scale after the blue light device is used for a long time. That is, after the device is used for a long period of time, since holes are difficult to inject into the light emitting layer, the balance of electrons and holes is broken and the light emitting efficiency of the blue device is seriously lowered at a low gray scale. The inventor researches to find that the luminous efficiency of the blue light emitting device is remarkably reduced at low gray scale because the electron blocking layer of the blue light emitting device is thin, and the blue light emitting device is related to the active material of the blue light emitting layer. The currently used blue light emitting layer is mostly composed of a single type of light emitting material, and the light emitting layers of red, green, and the like are mostly formed of a composite material. Therefore, the balance between holes and electrons of the blue light-emitting layer is more easily broken. Thereby causing the emission efficiency of the light emitting layers of different colors to be inconsistently attenuated at low gray scales. Further, in this case, a phenomenon of color shift occurs by a mixture of lights emitted from the light emitting layers of the plurality of colors. The phenomenon can be relieved to a certain extent under the high gray scale, and the problem of difficult hole injection can be relieved mainly because the voltage applied to the device under the high gray scale is larger. Therefore, the white screen color shift mainly occurs in low gray scale display. In addition, in consideration of improving the overall luminous efficiency of the device, a hole transport layer material with a slow transport rate and good electron stability cannot be replaced. Therefore, if a layer of material can be added between the blue light-emitting layer and the electron transport layer to control the electron transport rate, the above problem can be greatly alleviated: although the device still has difficulty in hole injection at low voltage due to slow cracking of the hole transport layer material after a period of use, the hole and electron in the light emitting layer can still be balanced at this time because the electron transport rate is slowed at low voltage. Therefore, the problems of color cast and the like caused by the balance of electrons and holes are broken can be relieved to a certain extent and even solved.
The specific color of the light-emitting layer 300 is not particularly limited, and may be, for example, a blue light-emitting layer or a light-emitting layer having another light-emitting color. Although the problem of difficulty in hole injection at a low voltage is more serious in the blue light emitting layer than in the light emitting layers of other colors, the organic light emitting diode of other colors, in which the problem is not serious, may also have the electron regulation layer according to the embodiment of the present invention. Therefore, when the organic light emitting diode and the blue light emitting layer jointly form the display panel, the organic light emitting diodes with different colors can have better structural consistency, and the production process is further facilitated to be simplified.
For simplicity of description, the following describes each structure of the organic light emitting diode according to the embodiment of the present invention in detail, taking the light emitting layer as a blue light emitting layer as an example:
according to the embodiment of the invention, when the organic light emitting diode is used for displaying, multi-level gray scale display can be realized, and the gray scale can specifically comprise L0-L255 gray scales. The inventors have found that the material forming the electron adjusting layer 600 can be selected to reduce the electron transport rate at a gray scale of L16 or less by selecting the material forming the electron adjusting layer 600. The inventors have found that the above problem of difficulty in injecting holes is significant when the gray scale is L16 or less. Therefore, when the gray level is less than or equal to L16, the problem of white frame color shift under low gray level can be alleviated by reducing the electron transmission rate. And also can prevent the electron transmission rate from being reduced under excessive gray scale to cause great reduction of the luminous efficiency of the device.
According to some embodiments of the present invention, it is preferable that the material forming the electron adjusting layer reduces the electron transport rate when the gray scale is equal to or less than L16 and keeps the electron transport rate from being reduced when the gray scale is greater than L16. Therefore, the problem of white picture color cast under low gray scale can be relieved, and the current efficiency of the device under high gray scale is not influenced. According to an embodiment of the present invention, the material forming the electron adjusting layer may specifically include at least one of an azole compound, a quinine derivative, a quinoxaline derivative, and a diazaanthracene derivative. The materials can well reduce the electron rate at low gray levels without significantly affecting the overall efficiency of the device.
According to the embodiment of the invention, the organic light emitting diode can further comprise other structures which are commonly used in the organic light emitting diode and improve the performance of the device. For example, referring to fig. 2, an electron blocking layer 900 may be further provided between the hole transport layer 400 and the blue light emitting layer 300, and a hole transport auxiliary layer 10 may be further provided between the first electrode 100 and the hole transport layer in order to further improve hole transport ability. According to a specific embodiment of the present application, the hole transport assist layer may be a P-doped hole transport assist layer. More specifically, the hole assist layer may be formed of a hole transport layer material that is P-type doped. That is, the materials of the hole transport layer and the hole transport layer are the same, and the difference between the two layers is that the hole transport layer is doped P-type. Therefore, the interface state between the first electrode and the hole transport layer can be improved, and the capability of injecting holes into the light emitting layer is improved. In general, the above structure can improve the hole transport capability, block electrons, and reduce the probability of recombination of holes at positions other than the blue light emitting layer 300. Specific materials for forming the hole transport layer 400 and the hole transport auxiliary layer 10 are not particularly limited, and those skilled in the art can select a commonly used hole transport material.
Similarly, the blue light emitting layer 300 may have a structure of a hole blocking layer 700 and an electron injection layer 800 on a side facing the second electrode 200. Thereby, the electron transport ability can be improved, and the probability of recombination of electrons and holes at a position between the light-emitting layer and the second electrode can be reduced. The materials of the hole transport layer 400, the electron blocking layer 900, the hole transport auxiliary layer 10, the hole blocking layer 700, and the electron injection layer 800 are not particularly limited, and those skilled in the art may select them according to the specific light emitting requirements of the organic light emitting diode and the specific material of the blue light emitting layer 300.
As described above, the light emitting direction of the organic light emitting diode according to the embodiment of the present invention may be a direction of the second electrode 200 side, as shown above in fig. 2. In order to improve the light extraction efficiency of the organic light emitting diode, a metal reflective layer 20 having a high light reflection rate may be further disposed on a side of the first electrode 100 away from the light emitting layer, where the metal reflective layer is located on a side of the first electrode 100 away from the blue light emitting layer 300, so as to reflect a portion of light emitted by the light emitting layer and propagating toward the first electrode 100. Similarly, in order to improve light extraction efficiency, a light extraction layer 30 may be provided on a side of the second electrode 200 away from the light emitting layer. The specific structure of the light extraction layer 30 is not particularly limited, and those skilled in the art can adopt a commonly used light extraction layer structure.
In yet another aspect of the present invention, an organic light emitting display substrate is provided. According to an embodiment of the present invention, the organic light emitting display substrate includes a plurality of organic light emitting diodes having different emission colors, and at least one of the plurality of organic light emitting diodes is as described above. Therefore, the organic light emitting display substrate has all the features and advantages of the organic light emitting diode described above, and thus, the description thereof is omitted. For example, after the display substrate is used for a period of time, the picture under a low gray scale can keep a better color, and the defect of color cast of a white picture can be greatly relieved.
According to a specific embodiment of the present invention, the specific number and color of the organic light emitting diodes included on the organic light emitting display substrate are not particularly limited as long as the organic light emitting diodes emitting blue light described above are provided. For example, there may be red, green, and blue organic light emitting diodes, or red, green, yellow, blue organic light emitting diodes, etc., according to other embodiments of the present application. For simplicity of description, the respective structures of the organic light emitting display substrate will be described in detail below by taking as an example that the display substrate includes red, green, and blue organic light emitting diodes.
Referring to fig. 3 and 4, according to an embodiment of the present invention, the light emitting layers of the plurality of organic light emitting diodes on the organic light emitting display substrate may be disposed in the same layer, as illustrated in the drawing as a light emitting layer 300A of a blue organic light emitting diode, a light emitting layer 300B of a green organic light emitting diode, and a light emitting layer 300C of a red organic light emitting diode. The hole transport layer 400, the electron transport layer 500, and the like may be commonly used for three types of light emitting organic light emitting diodes.
It will be appreciated by those skilled in the art that, for example, to achieve a controllable color display, the plurality of organic light emitting diodes on the organic light emitting display substrate that emit light of different colors need to be individually controllable. Therefore, the red organic light emitting diode, the green organic light emitting diode, and the blue organic light emitting diode cannot share one first electrode and one second electrode at the same time. For example, as shown in fig. 4, the first electrode may be a pixel anode of the organic light emitting display substrate, and the organic light emitting diodes of different light emitting colors correspond to different first electrodes, such as 100A, 100B, and 100C shown in the figure. At this time, a plurality of organic light emitting diodes may share one cathode, for example, the second electrode 200 shown in fig. 4.
According to some embodiments of the present invention, referring to fig. 3, in order to simplify the manufacturing process, the orthographic projection of the electronic regulation layer of the blue organic light emitting diode on the first electrode, the orthographic projection of the light emitting layer 300C of the red organic light emitting diode on the first electrode 100, the orthographic projection of the light emitting layer 300B of the green organic light emitting diode on the first electrode, and the orthographic projection of the light emitting layer 300C of the blue organic light emitting diode on the first electrode may be covered. That is, the electronic adjustment layer of the blue organic light emitting diode may cover the region where the green organic light emitting diode and the red organic light emitting diode are located. Thus, when the electro-regulation layer 600 is formed, it is not necessary to particularly control the position of the electro-regulation layer 600. Although this solution can reduce the electron transport rate of the green organic light emitting diode and the red organic light emitting diode at the low gray scale simultaneously, as mentioned above, the electron adjusting layer only plays a role of reducing the electron transport rate at the low gray scale, and thus does not significantly affect the light emitting efficiency of the display substrate. In addition, although the electron transport rates of the organic light emitting diodes with different light emitting colors are all reduced, the electrons and the holes at the interface of the light emitting layer are still in a balanced state, so that the problem that the light emitting efficiency of the diodes with different light emitting colors is reduced in inconsistent manner due to the reduction of the electron transport rates of the organic light emitting diodes with multiple colors is solved.
Alternatively, according to other embodiments of the present invention, referring to fig. 4, the electronic adjustment layer 600 may be formed only in the region where the blue organic light emitting diode is located. That is, the orthographic projection of the electron adjustment layer 600 of the blue organic light emitting diode on the second electrode (or the first electrode 100) may coincide with the area where the orthographic projection of the light emitting layer 300A of the blue organic light emitting diode on the second electrode (or the first electrode 100) is located. Therefore, the electron transmission rate of the blue organic light emitting diode can be controlled, and the influence on the efficiency of the light emitting diodes of other colors can be avoided.
It should be particularly noted that, in the organic light emitting display substrate according to the embodiment of the present invention, in addition to the light emitting layer, the first electrode and the electronic adjustment layer, other structures in the organic light emitting diodes described above may be shared by a plurality of organic light emitting diodes, as long as the light emitting of each organic light emitting diode can be controlled individually, and thus, the detailed description is omitted here.
In still another aspect of the present invention, the present invention provides a method of preparing the foregoing organic light emitting display substrate. According to an embodiment of the present invention, the method includes a step of forming a plurality of organic light emitting diodes which do not all have the same emission color. And forming an electron adjusting layer between the light emitting layer and the electron transporting layer when forming the at least one organic light emitting diode. For example, when a blue organic light emitting diode is formed, an electron adjusting layer may be formed between the blue light emitting layer and the electron transporting layer.
According to an embodiment of the present invention, the method includes forming a first electrode; forming a blue light emitting layer, a red light emitting layer and a green light emitting layer on one side of the first electrode, wherein the blue light emitting layer, the red light emitting layer and the green light emitting layer are arranged in the same layer; an electron adjusting layer is formed on the blue light emitting layer on the side away from the first electrode using a fine metal mask. The method can simply and conveniently obtain the organic light-emitting display substrate, and the prepared organic light-emitting display substrate can relieve the problem that a white picture is easy to have color cast under low gray scale after being used for a period of time.
According to an embodiment of the invention, the method may comprise the steps of: the first electrode is formed, for example, on the substrate by means including, but not limited to, depositing a metal. Subsequently, formation of a hole transport auxiliary layer, a hole transport layer, an electron blocking layer, and the like may be sequentially performed. The above-described structure of the plurality of organic light emitting diodes may be common except for the first electrode. Subsequently, an operation of forming the light emitting layers may be performed, for example, the blue light emitting layer, the red light emitting layer, and the green light emitting layer may be formed at corresponding positions through a fine metal mask (FMM mask), and the blue light emitting layer, the red light emitting layer, and the green light emitting layer may be disposed at the same layer. And then, forming structures such as a hole blocking layer, an electron regulating layer, an electron transport layer, an electron injection layer and the like on the side of the light-emitting layer far away from the first electrode, and forming a second electrode. The second electrode and the hole blocking layer, the electron transport layer, and the electron injection layer may be shared by a plurality of organic light emitting diodes. And finally, a light extraction layer can be formed on one side of the second electrode far away from the electron injection layer.
In some embodiments of the present invention, the electron-modulating layer may also cover the light-emitting layers of the plurality of organic light-emitting diodes. That is, the electronic adjustment layer may also be shared by a plurality of organic light emitting diodes, not just in the area where the blue organic light emitting diode is located. In other words, the orthographic projection of the electron regulation layer formed in this step on the first electrode covers the orthographic projection of the red light emitting layer on the first electrode, the orthographic projection of the green light emitting layer on the first electrode, and the orthographic projection of the blue light emitting layer on the first electrode. A schematic structural view of the finally obtained organic light emitting display substrate may be as shown in fig. 3. Therefore, when the electronic adjusting layer is formed, a mask is not required to be introduced to limit the position of the electronic adjusting layer, and the number of times of using the mask in the method can be reduced, so that the production process can be simplified, and the production cost can be reduced.
Alternatively, according to other embodiments of the present invention, the electronic adjustment layer may be disposed only at the position corresponding to the blue organic light emitting diode. Specifically, when the electron adjusting layer is formed, a fine metal mask for forming the blue light emitting layer (or a mask having a shape conforming to the mask for forming the blue light emitting layer) may be used, and the electron adjusting layer may be formed in a specific region. A schematic view of the structure of the finally obtained organic light emitting display substrate may be as shown in fig. 4. Therefore, the electronic adjusting layer can be formed only in the area where the blue organic light emitting diode is located, and the influence on the light emitting efficiency of the red organic light emitting diode and the green organic light emitting diode under the low gray scale can be further avoided.
In yet another aspect of the present invention, a display device is provided. The display device includes the organic light emitting display substrate described above. For example, the display device may be a display panel, a display screen of an electronic device such as a computer, a mobile phone, a PAD, or a notebook computer, or a device such as a television or a display screen. The display device has all the features and advantages of the display substrate described above, and thus, the description thereof is omitted. In general, the display device can relieve the problem that the white picture is easy to have color cast under low gray scale after being used for a period of time.
The present invention is illustrated below by specific examples, and it will be understood by those skilled in the art that the following specific examples are for illustrative purposes only and do not limit the scope of the present invention in any way. In addition, in the following examples, materials and equipment used are commercially available unless otherwise specified. If in the following examples, specific treatment conditions and treatment methods are not explicitly described, the treatment may be performed using conditions and methods well known in the art.
Example 1
Preparing a diode comprising a metal reflecting layer, an anode, a P-doped-blue hole transmission auxiliary layer, a hole transmission layer, an electron blocking layer, a blue light emitting layer, a hole blocking layer, an electron adjusting layer, an electron transmission layer, an electron injection layer, a cathode and a light extraction layer. Wherein the electronic regulating layer is azole compound.
Example 2
The other structure was the same as in example 1, except that a quinine derivative was used for the electron-regulating layer.
Example 3
The other structure was the same as in example 1, except that an oxinoid derivative was used for the electron control layer.
Example 4
The remaining structure was the same as in example 1, except that a diazaanthracene derivative was used for the electron adjusting layer.
Comparative example 1
The remaining structure was the same as in example 1, except that no electron adjusting layer was provided between the hole-blocking layer and the electron-transporting layer.
The organic light emitting diodes prepared in examples 1 to 4 and comparative example 1 were tested for current Efficiency (Efficiency) at different current densities. Referring to fig. 5, the current efficiency curve of the device of comparative example 1 was significantly changed before and after use (after the diode was continuously lit until the luminance decayed to 95% of the initial luminance), and the current efficiency decayed severely after use. Referring to fig. 6, the current efficiency of the diode prepared in example 1 was tested, and the current efficiency was slightly attenuated after use (after the diode was continuously lit until the luminance was attenuated to 95% of the initial luminance), but the degree of attenuation was greatly improved as compared to comparative example 1. The same tests were carried out on the devices obtained in examples 2 to 4, and the test results were similar to those of example 1, and the current efficiency decay of the devices after use was all better than that of the comparative examples.
In the description of the present invention, the terms "upper", "lower", and the like indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience of describing the present invention but do not require that the present invention must be constructed and operated in a specific orientation, and thus, should not be construed as limiting the present invention. The terms "first", "second", etc. are used merely to distinguish between different features and should not be construed as limiting in importance or number thereof. The description of the terms "one embodiment," "another embodiment," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment is included in at least one embodiment of the invention. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, various embodiments or examples and features of different embodiments or examples described in this specification can be combined and combined by one skilled in the art without contradiction.
Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention, and that variations, modifications, substitutions and alterations can be made to the above embodiments by those of ordinary skill in the art within the scope of the present invention.
Claims (15)
1. An organic light emitting diode for display, comprising:
a first electrode;
a hole transport layer on one side of the first electrode;
the light-emitting layer is positioned on one side, far away from the first electrode, of the hole transport layer;
an electron-regulating layer on a side of the light-emitting layer remote from the hole-transporting layer, the electron-regulating layer configured to reduce a transport rate of electrons;
the electron transport layer is positioned on one side, far away from the light emitting layer, of the electron adjusting layer; and
and the second electrode is positioned on one side of the electron transmission layer, which is far away from the electron regulation layer.
2. The OLED as claimed in claim 1, wherein the OLED is used for displaying multi-level gray scale, the gray scale includes L0-L255, and the material forming the electron adjusting layer is configured to reduce the electron transmission rate when the gray scale is equal to or less than L16.
3. The OLED of claim 2, wherein the material forming the electron-modulating layer is configured to keep the electron transport rate from decreasing when the gray scale is greater than L16.
4. The organic light-emitting diode according to claim 2 or 3, wherein a material forming the electron adjustment layer includes at least one of an azole compound, a quinine derivative, a quinoxaline derivative, and a diazaanthracene derivative.
5. The organic light-emitting diode of claim 1, further comprising at least one of the following structures:
an electron injection layer between the second electrode and the electron transport layer;
a hole blocking layer located between the light emitting layer and the electron adjusting layer;
an electron blocking layer between the light emitting layer and the hole transport layer;
a hole transport auxiliary layer between the hole transport layer and the first electrode;
the metal reflecting layer is positioned on one side of the first electrode, which is far away from the light emitting layer; and
and the light extraction layer is positioned on one side of the second electrode, which is far away from the light-emitting layer.
6. The OLED of claim 5, wherein the hole transport assisting layer is formed by P-doping the material forming the hole transport layer.
7. The organic light-emitting diode according to any one of claims 1 to 3 and 5 to 6, wherein the light-emitting layer is a blue light-emitting layer.
8. An organic light emitting display substrate, comprising: a plurality of organic light emitting diodes which do not all have the same emission color, at least one of the plurality of organic light emitting diodes being as defined in any one of claims 1 to 7.
9. The organic light-emitting display substrate according to claim 8, comprising:
the organic light emitting diode comprises a red organic light emitting diode, a green organic light emitting diode and a blue organic light emitting diode, wherein the blue organic light emitting diode is as claimed in any one of claims 1 to 7, light emitting layers of the red organic light emitting diode, the green organic light emitting diode and the blue organic light emitting diode are arranged in the same layer, and the red organic light emitting diode, the green organic light emitting diode and the blue organic light emitting diode share a hole transport layer and an electron transport layer.
10. The organic light-emitting display substrate according to claim 9, wherein an orthographic projection of the electron-adjusting layer of the blue organic light-emitting diode on the first electrode covers an orthographic projection of the light-emitting layer of the red organic light-emitting diode on the first electrode, an orthographic projection of the light-emitting layer of the green organic light-emitting diode on the first electrode, and an orthographic projection of the light-emitting layer of the blue organic light-emitting diode on the first electrode.
11. The organic light-emitting display substrate according to claim 9, wherein an orthogonal projection of the electron-adjusting layer of the blue organic light-emitting diode on the second electrode coincides with an orthogonal projection of the light-emitting layer of the blue organic light-emitting diode on the second electrode.
12. A method of making the organic light-emitting display substrate of any of claims 8-11, comprising:
a plurality of organic light emitting diodes not all having the same emission color are formed, and an electron adjusting layer is formed between a light emitting layer and an electron transporting layer when at least one of the organic light emitting diodes is formed.
13. The method of claim 12, comprising:
forming a first electrode;
forming a blue light emitting layer, a red light emitting layer and a green light emitting layer on one side of the first electrode, wherein the blue light emitting layer, the red light emitting layer and the green light emitting layer are arranged in the same layer;
and forming the electronic regulation layer on the side of the blue light-emitting layer far away from the first electrode by using a fine metal mask.
14. The method of claim 12, comprising:
forming a first electrode;
forming a blue light emitting layer, a red light emitting layer and a green light emitting layer on one side of the first electrode, wherein the blue light emitting layer, the red light emitting layer and the green light emitting layer are arranged in the same layer;
the electronic adjusting layer is formed on one side of the blue light emitting layer far away from the first electrode, and the orthographic projection of the electronic adjusting layer on the first electrode covers the orthographic projection of the red light emitting layer on the first electrode, the orthographic projection of the green light emitting layer on the first electrode and the orthographic projection of the blue light emitting layer on the first electrode.
15. A display device comprising the organic light-emitting display substrate according to any one of claims 8 to 11.
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| WO2021103996A1 (en) * | 2019-11-28 | 2021-06-03 | 京东方科技集团股份有限公司 | Organic light-emitting diode, organic light-emitting display substrate and method for preparing same, and display apparatus |
| CN113748517A (en) * | 2020-03-27 | 2021-12-03 | 京东方科技集团股份有限公司 | Display device, display panel and manufacturing method thereof |
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| CN112151690B (en) * | 2020-09-28 | 2024-04-09 | 京东方科技集团股份有限公司 | Organic light emitting diode, preparation method thereof, display panel and display device |
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