CN115050799A

CN115050799A - Display panel and display device

Info

Publication number: CN115050799A
Application number: CN202210711648.4A
Authority: CN
Inventors: 林君; 朱凯; 韩振伟; 赵鑫栋; 陈闻凯; 胡小叙
Original assignee: Beijing Visionox Technology Co Ltd
Current assignee: Beijing Visionox Technology Co Ltd
Priority date: 2022-06-22
Filing date: 2022-06-22
Publication date: 2022-09-13

Abstract

The application provides a display panel and a display device. The display panel comprises a plurality of pixel units, each pixel unit comprises a plurality of sub-pixels, the sub-pixels are divided into first sub-pixels and second sub-pixels, and the luminance life of the first sub-pixels is smaller than that of the second sub-pixels. Each sub-pixel comprises a cathode, an anode and a light emitting layer and a carrier transmission layer which are arranged between the cathode and the anode, and the carrier mobility of the carrier transmission layer of the first type of sub-pixel is different from the carrier mobility of the carrier transmission layer of the second type of sub-pixel. By adjusting the mobility of the carriers, the brightness difference of different sub-pixels can be reduced, and the problem of color cast of display can be improved.

Description

Display panel and display device

Technical Field

The application relates to the technical field of display, in particular to a display panel and a display device with the same.

Background

An Organic Light-Emitting Display (OLED for short) is an active Light-Emitting Display device, and is expected to become the next-generation mainstream flat panel Display technology due to its advantages of simple preparation process, low cost, easy color Display, large screen Display, flexible Display, and the like. At present, the OLED usually adopts different colors as primary colors, and generates a true color by adjusting a color mixing ratio of different color combinations, and finally realizes display. However, since there is a difference between the luminance lifetimes of different colors, especially in the high-luminance mode, the difference in luminance lifetimes of different colors increases, and thus, after a time display, a color shift problem occurs.

Disclosure of Invention

A first aspect of the present application provides a display panel. The display panel comprises a plurality of pixel units, each pixel unit comprises a plurality of sub-pixels, the sub-pixels are divided into first sub-pixels and second sub-pixels, and the luminance life of the first sub-pixels is smaller than that of the second sub-pixels. Each sub-pixel comprises a cathode, an anode and a light emitting layer and a carrier transmission layer which are arranged between the cathode and the anode, and the carrier mobility of the carrier transmission layer of the first type of sub-pixel is different from the carrier mobility of the carrier transmission layer of the second type of sub-pixel.

In the scheme, the mobility rates of carriers in the carrier transmission layers corresponding to the first-class sub-pixels and the second sub-pixels with different brightness lives are designed to be different, and the size of a carrier combination area of the first-class sub-pixels/the second sub-pixels in the corresponding light emitting layers is adjusted, so that the difference between the brightness lives of the first-class sub-pixels and the second sub-pixels is reduced, and the problem of color cast of display is solved.

In combination with the first aspect, in some embodiments, the carrier transport layer includes an electron transport layer located between the cathode and the light emitting layer, and the electron mobility of the electron transport layer of the first type of sub-pixel is smaller than the mobility of the electron transport layer of the second type of sub-pixel.

In the above scheme, the electron mobility of the electron transport layer of the first-type sub-pixel is smaller than that of the electron transport layer of the second-type sub-pixel, so that the brightness life of the first-type sub-pixel with short brightness life is prolonged, and the display color cast problem of the display panel is improved.

With reference to the first aspect, in some embodiments, the electron transport layer of the first type of sub-pixel and the electron transport layer of the second type of sub-pixel both include a first film layer, the electron transport layer of the first type of sub-pixel further includes a second film layer, and the second film layer has an electron mobility smaller than that of the first film layer and is located between the first film layer and the light emitting layer of the first type of sub-pixel. Furthermore, the first-type sub-pixels comprise a plurality of sub-pixels which emit light with different wavelengths, and the thickness of the second film layer of the sub-pixels with the larger wavelength of the emitted light is larger.

In the above scheme, the second film layer with small electron mobility is only arranged between the first film layer of the electron transport layer of the first-type sub-pixel with small brightness life and the light emitting layer, so that the carrier recombination zone of the light emitting layer of the first-type sub-pixel is increased, more electrons and holes are recombined to generate more excitons, and the brightness life of the first-type sub-pixel is prolonged.

With reference to the first aspect, in some embodiments, the electron transport layer of the first type of sub-pixel and the electron transport layer of the second type of sub-pixel both include a first film layer, and the electron transport layer of the second type of sub-pixel further includes a second film layer, where the second film layer has an electron mobility greater than that of the first film layer and is located between the first film layer and the light emitting layer of the second type of sub-pixel. Further, the second type of sub-pixel includes a plurality of sub-pixels emitting light of different wavelengths, and the sub-pixels emitting light of a larger wavelength have a smaller thickness of the second film layer.

In the above scheme, the second film layer with high electron mobility is arranged in the second type of sub-pixel, so that a carrier recombination region in a light emitting layer of the second type of sub-pixel is reduced, the brightness life of the second type of sub-pixel is further reduced, the difference of the brightness life between the first type of sub-pixel and the second type of sub-pixel is finally reduced, and the problem of display color cast is improved.

With reference to the first aspect, in some embodiments, the electron transport layer of the first type of sub-pixel and the electron transport layer of the second type of sub-pixel both include a first film layer and a second film layer, the electron mobility of the second film layer is smaller than that of the first film layer, the second film layer is respectively located between the first film layer and the light emitting layers of the first type of sub-pixel and the second type of sub-pixel, and the thickness of the second film layer of the first type of sub-pixel is greater than that of the second film layer of the second type of sub-pixel. Furthermore, the first-type sub-pixels comprise a plurality of sub-pixels for emitting light with different wavelengths, and the second film layer of the sub-pixels with the larger wavelength of the emitted light is thicker; and/or the second type of sub-pixel comprises a plurality of sub-pixels emitting light with different wavelengths, and the second film layer of the sub-pixel emitting light with the larger wavelength is thicker.

In the scheme, the brightness life of all the sub-pixels in the pixel is adjusted, so that the difference of the brightness life of the sub-pixels with different colors can be balanced, and the problem of color cast in display can be improved more efficiently.

With reference to the first aspect, in some embodiments, in a case where the electron transport layer of the first type of sub-pixel and the electron transport layer of the second type of sub-pixel both include the first film layer and the second film layer, the total thicknesses of the first film layer and the second film layer between different sub-pixels are equal, and the thickness of the second film layer of the first type of sub-pixel is greater than the thickness of the second film layer of the second type of sub-pixel.

In the above scheme, the thickness of the first film layer and the thickness of the second film layer between the first sub-pixel and the second sub-pixel are designed, so that more electrons enter the light-emitting layer at a slow speed by the first sub-pixel, and more electrons and more holes are recombined, thereby improving the brightness life of the first sub-pixel to a greater extent and shortening the difference of the brightness life between the first sub-pixel and the second sub-pixel. And, the setting of first rete and second rete, the production and processing of display panel has been practiced thrift manufacturing cost to the be convenient for.

With reference to the first aspect, in some embodiments, the material of the electron transport layer of the first-type sub-pixel is a substrate layer doped with a second-type material, the substrate layer is made of the first-type material, the material of the electron transport layer of the second-type sub-pixel is the first-type material, the second-type material is doped on the side, facing the light emitting layer, of the substrate layer of the first-type sub-pixel, and the electron mobility of the second-type material is smaller than that of the first-type material. Furthermore, the first-type sub-pixels comprise a plurality of sub-pixels which emit light with different wavelengths, and the doping concentration of the second-type material of the sub-pixels with the larger wavelength of the emitted light is larger.

In the scheme, the electron mobility of the electron transmission layer corresponding to the first-class pixels is reduced in a doping mode, the size of a carrier recombination region is increased, the brightness service life of the first-class sub-pixels is prolonged, the brightness difference between the first-class sub-pixels and the second-class sub-pixels is reduced, and the problem of color cast in display is solved. And the doping mode is simple and convenient to realize, and the production cost is saved. Furthermore, all the sub-pixels contained in the first type of sub-pixels are doped, so that the problem of color cast in display is effectively relieved.

With reference to the first aspect, in some embodiments, the material of the electron transport layer of the first-type sub-pixel is a first-type material, the material of the electron transport layer of the second-type sub-pixel is a substrate layer doped with a second-type material, the substrate layer is made of the first-type material, the second-type material is doped on a side, facing the light emitting layer, of the substrate layer of the second-type sub-pixel, and the electron mobility of the second-type material is greater than that of the first-type material. Further, the second-type sub-pixel includes a plurality of sub-pixels emitting light of different wavelengths, and the sub-pixels emitting light of a larger wavelength have a smaller doping concentration of the second-type material.

In the above scheme, the electron transport layer of the second type of sub-pixel is doped with the second type of material with high electron mobility, so that the brightness life of the second type of sub-pixel is reduced. Furthermore, the second material with different concentrations is doped according to the wavelength of the light emitted by all the sub-pixels in the second sub-pixels, so that the brightness life of all the sub-pixels of the second sub-pixels is reasonably reduced, and the problem of color cast of display is effectively relieved.

With reference to the first aspect, in some embodiments, the material of the electron transport layer of the first-type sub-pixel and the material of the electron transport layer of the first-type sub-pixel are both substrate layers doped with a second-type material, the substrate layers are made of the first-type material, the second-type material is doped on the sides, facing the light emitting layer, of the substrate layers of the first-type sub-pixel and the substrate layers of the second-type sub-pixel, the electron mobility of the second-type material is smaller than that of the first-type material, and the doping concentration of the second-type material in the substrate layer of the first-type sub-pixel is greater than that in the substrate layer of the second-type sub-pixel. Furthermore, the first-class sub-pixels comprise a plurality of sub-pixels for emitting light with different wavelengths, and the doping concentration of the second-class material of the sub-pixels with the larger wavelength of the emitted light is larger; and/or the second-type sub-pixel comprises a plurality of sub-pixels which emit light with different wavelengths, and the doping concentration of the second-type material of the sub-pixel with the larger wavelength of the emitted light is larger.

In the scheme, the electron transmission layers of the first-class sub-pixels and the second-class sub-pixels are doped with the second-class materials with different concentrations and small electron mobility, so that the brightness service life of the first-class sub-pixels is prolonged, and the problem of color cast in display is solved. Furthermore, doping treatment is carried out on all the sub-pixels, and the concentration of the doped second material is adjusted according to different wavelength relations of light emitted by the sub-pixels, so that the problem of color cast of the display is improved more efficiently.

In combination with the first aspect, in some embodiments, the carrier transport layer includes a hole transport layer between the anode and the light emitting layer, and the hole transport layer of the first type of sub-pixel has a hole mobility greater than the hole transport layer of the second type of sub-pixel.

In the scheme, the hole mobility of the hole transport layer of the first-class sub-pixel is limited to be larger than that of the hole transport layer of the second-class sub-pixel, the carrier recombination efficiency of the first-class sub-pixel is improved, more excitons are generated, and the brightness service life of the first-class sub-pixel is further prolonged.

With reference to the first aspect, in some embodiments, the hole transport layer of the first-type sub-pixel and the hole transport layer of the second-type sub-pixel both include a third film layer, the hole transport layer of the first-type sub-pixel further includes a fourth film layer, and the fourth film layer has a hole mobility greater than that of the third film layer and is located between the third film layer and the light emitting layer of the first-type sub-pixel. Furthermore, the first-type sub-pixels comprise a plurality of sub-pixels for emitting light with different wavelengths, and the thickness of the fourth film layer of the sub-pixels with the larger wavelength of the emitted light is larger.

In the above scheme, the size of the carrier recombination region in the light emitting layer is increased by the design of the recombination film layer of the hole transport layer corresponding to the first-type sub-pixel, and the brightness life of the first-type sub-pixel is prolonged. Furthermore, the thickness of the fourth film layer is designed according to the wavelength of emergent light of all the sub-pixels in the first type of sub-pixels, so that the problem of color cast in display is effectively solved.

With reference to the first aspect, in some embodiments, the hole transport layer of the first type of sub-pixel and the hole transport layer of the second type of sub-pixel both include a third film layer, and the hole transport layer of the second type of sub-pixel further includes a fourth film layer, and the fourth film layer has a hole mobility smaller than that of the third film layer and is located between the third film layer and the light emitting layer of the second type of sub-pixel. Further, the second type of sub-pixel includes a plurality of sub-pixels emitting light of different wavelengths, and the thickness of the fourth film layer of the sub-pixel, which emits light of a larger wavelength, is smaller.

In the above scheme, the fourth film layer with low hole mobility provided in the second type of sub-pixel allows holes to enter the light-emitting layer at a slow speed, and also reduces the number of holes entering the light-emitting layer of the second type of sub-pixel per unit time, and reduces the size of the carrier recombination region, thereby reducing the luminance lifetime of the second type of sub-pixel.

With reference to the first aspect, in some embodiments, the hole transport layer of the first-type sub-pixel and the hole transport layer of the second-type sub-pixel both include a third film layer and a fourth film layer, the fourth film layer has a hole mobility greater than that of the third film layer and is respectively located between the third film layer and the light emitting layers of the first-type sub-pixel and the second-type sub-pixel, and the fourth film layer of the first-type sub-pixel has a thickness greater than that of the fourth film layer of the second-type sub-pixel. Further, the first type of sub-pixels comprise a plurality of sub-pixels emitting light with different wavelengths, the thickness of the fourth film layer of the sub-pixels emitting light with larger wavelength is larger, and/or the second type of sub-pixels comprise a plurality of sub-pixels emitting light with different wavelengths, and the thickness of the fourth film layer of the sub-pixels emitting light with larger wavelength is larger.

In the above scheme, the design of the hole transport layers corresponding to the first-type sub-pixels and the second-type sub-pixels not only reduces the difference of the brightness service life between the first-type sub-pixels and the second-type sub-pixels, improves the luminous efficiency of the display panel, but also is convenient for production and saves the cost. Further, the problem of color cast of the display is more effectively improved for all pixels according to the thin film.

With reference to the first aspect, in a case that the hole transport layer of the first type of sub-pixel and the hole transport layer of the second type of sub-pixel both include the third film layer and the fourth film layer, the total thicknesses of the third film layer and the fourth film layer between different sub-pixels are equal, and the thickness of the fourth film layer of the first type of sub-pixel is greater than the thickness of the fourth film layer of the second type of sub-pixel.

In the scheme, more holes enter the first-class sub-pixels at a high speed, so that the brightness service life of the first-class sub-pixels is prolonged, the processing technology of the hole injection layer is simplified, and the production is facilitated.

With reference to the first aspect, in some embodiments, the material of the hole transport layer of the first-type sub-pixel is a substrate layer doped with a fourth-type material, the substrate layer is made of the third-type material, the material of the hole transport layer of the second-type sub-pixel is the third-type material, the fourth-type material is doped on the side, facing the light-emitting layer, of the substrate layer of the first-type sub-pixel, and the hole mobility of the fourth-type material is greater than that of the third-type material. Furthermore, the first-type sub-pixels comprise a plurality of sub-pixels which emit light with different wavelengths, and the doping concentration of the fourth-type material of the sub-pixels with the larger wavelength of the emitted light is larger.

In the scheme, the doping process is simple, and the production cost is saved. Furthermore, doping with different concentrations is carried out on sub-pixels with different brightness lifetimes, so that the difference of the brightness lifetimes among the different sub-pixels can be improved, and the problem of color cast in display can be effectively solved.

With reference to the first aspect, in some embodiments, the material of the hole transport layer of the first-type sub-pixel is a third-type material, the material of the hole transport layer of the second-type sub-pixel is a base material layer doped with a fourth-type material, the base material layer is composed of the third-type material, the fourth-type material is doped on the side, facing the light-emitting layer, of the base material layer of the second-type sub-pixel, and the hole mobility of the fourth-type material is smaller than that of the third-type material. Further, the second type sub-pixel includes a plurality of sub-pixels emitting light of different wavelengths, and the sub-pixels emitting light of a larger wavelength have a smaller doping concentration of the fourth type material.

In the scheme, the brightness service life of the second type of sub-pixels is reduced through doping, the brightness difference between the first type of sub-pixels and the second type of sub-pixels is reduced, and the problem of color cast of display is improved. Furthermore, the brightness life of the second type of sub-pixels is reasonably reduced, and the problem of color cast of display is better improved.

With reference to the first aspect, in some embodiments, the material of the hole transport layer of the first-type sub-pixel and the material of the hole transport layer of the first-type sub-pixel are both substrate layers doped with a fourth-type material, the substrate layers are composed of a third-type material, the fourth-type material is doped on the side, facing the light-emitting layer, of the substrate layers of the first-type sub-pixel and the substrate layers of the second-type sub-pixel, the hole mobility of the fourth-type material is greater than the hole mobility of the third-type material, and the doping concentration of the fourth-type material in the substrate layer of the first-type sub-pixel is greater than the doping concentration in the substrate layer of the second-type sub-pixel. Furthermore, the first-class sub-pixels comprise a plurality of sub-pixels for emitting light with different wavelengths, and the doping concentration of the fourth-class material of the sub-pixels with the larger wavelength of the emitted light is larger; and/or the second type of sub-pixel comprises a plurality of sub-pixels for emitting light with different wavelengths, and the doping concentration of the fourth type of material of the sub-pixels with larger wavelength of the emitted light is larger.

In the scheme, the fourth material with different concentrations is doped aiming at the sub-pixels with different brightness service lives, so that the brightness difference among all the sub-pixels can be effectively reduced, and the problem of color cast in display can be effectively solved.

A second aspect of the present application provides a display device. The display device comprises any one of the display panels provided by the first aspect.

Drawings

Fig. 1 is a schematic structural diagram of a pixel of a display panel according to an embodiment of the present application.

Fig. 2 is a schematic structural diagram of a pixel of a display panel according to an embodiment of the present application.

Fig. 3 is a schematic structural diagram of a pixel of a display panel according to an embodiment of the present application.

Fig. 4 is a schematic structural diagram of a pixel of a display panel according to another embodiment of the present application.

Fig. 5 is a schematic structural diagram of a pixel of a display panel according to another embodiment of the present application.

Fig. 6 is a schematic structural diagram of a pixel of a display panel according to another embodiment of the present application.

Fig. 7 is a schematic structural diagram of a pixel of a display panel according to another embodiment of the present disclosure.

Fig. 8 is a schematic structural diagram of a pixel of a display panel according to another embodiment of the present application.

Fig. 9 is a schematic structural diagram of a pixel of a display panel according to an embodiment of the present application.

FIG. 10 is a schematic diagram of a pixel structure of a display panel according to another embodiment of the present application

Fig. 11 is a schematic structural diagram of a pixel of a display panel according to another embodiment of the present disclosure.

Fig. 12 is a schematic structural diagram of a pixel of a display panel according to another embodiment of the present application.

Fig. 13 is a schematic structural diagram of a pixel of a display panel according to another embodiment of the present application.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Due to the limitation of material characteristics, the brightness life corresponding to the sub-pixels with different colors in the display panel is inconsistent, after the lighting time reaches the time limit, the sub-pixels with certain colors reach the service life, the brightness gradually attenuates, the normal display cannot be realized, and finally, an abnormal display area appears on the display panel. Therefore, the problem of display abnormity, such as display color cast, on the display panel can be relieved by adjusting the brightness life of the sub-pixels with different colors.

The embodiment of the application provides a display panel, which changes the size of a carrier recombination region corresponding to sub-pixels with brightness difference by enabling the mobility of carriers corresponding to the sub-pixels with brightness difference to be different, so as to improve the problem of display color cast.

As shown in fig. 1, the display panel includes a plurality of pixel units, each pixel unit includes a plurality of sub-pixels, the sub-pixels are divided into sub-pixels of a first type and sub-pixels of a second type, and the luminance lifetime of the sub-pixels of the first type is smaller than that of the sub-pixels of the second type. Each sub-pixel comprises a cathode 1, an anode 2, and a light-emitting layer 3 and a carrier transport layer 4 located between the cathode 1 and the anode 2. The carrier transport layer is located between the light emitting layer and the anode or between the light emitting layer and the cathode. The carrier mobility of the carrier transmission layer of the first type of sub-pixel is different from the carrier mobility of the carrier transmission layer of the second type of sub-pixel.

Sub-pixel based light emission mechanism: when the voltage is applied, carriers, that is, holes of the anode and electrons of the cathode, are transferred to the light emitting layer and are recombined to generate excitons, and the regions where the excitons are generated become carrier recombination regions. The size of the recombination region is related to the carrier transport capability, so that different carriers can pass through the light-emitting layer quickly to reach other functional film layers such as a carrier blocking layer or a counter electrode to cause quenching. Therefore, adjusting the transmission capability of carriers corresponding to different sub-pixels can adjust the brightness life of different sub-pixels, thereby alleviating the occurrence of display abnormalities such as display color cast.

Specifically, as shown in fig. 2, each pixel unit includes three sub-pixels, i.e., a sub-pixel R, a sub-pixel G, and a sub-pixel B, where the sub-pixel B is a first type sub-pixel, and the sub-pixel R and the sub-pixel G are a second type sub-pixel. The carrier transport layer includes a hole transport layer and an electron transport layer. The sub-pixel R includes a cathode 1, an anode 2, a light emitting layer (R-EML) between the cathode 1 and the anode 2, a hole transport layer 42 (R-HTL) between the light emitting layer 3 and the anode 2, and an electron transport layer 41 (R-ETL) between the light emitting layer 3 and the cathode 1. The sub-pixel G includes a cathode 1, an anode 2, a light emitting layer 3 (abbreviated as G-EML) between the cathode 1 and the anode 2, a hole transport layer 42 (abbreviated as G-HTL) between the light emitting layer 3 and the anode 2, and an electron transport layer 41 (abbreviated as G-ETL) between the light emitting layer 2 and the cathode 1. The sub-pixel B includes a cathode 1, an anode 2, an emitting layer 3 (referred to as B-EML) between the cathode 1 and the anode 2, a hole transport layer 42 (referred to as B-HTL) between the emitting layer 3 and the anode 2, and an electron transport layer 41 (referred to as B-ETL) between the emitting layer 3 and the cathode 1. According to the brightness life of the sub-pixels of three different colors of RGB, the carrier mobility corresponding to B-EML in the sub-pixel B with the minimum brightness is different from the carrier mobility corresponding to R-EML in the sub-pixel R and the carrier mobility corresponding to G-EML in the sub-pixel G, namely, the brightness life of the sub-pixel B with the minimum life is prolonged, the brightness difference among the sub-pixels with different colors is reduced, and the problem of display color cast caused by the fact that the brightness life of the sub-pixels with different colors of a display panel is different is solved.

It should be understood that the first type of sub-pixel and/or the second type of sub-pixel represents two types of sub-pixels having a relationship of luminance lifetime, and does not only include a single sub-pixel of a certain color. For example, the first sub-pixel may include a sub-pixel emitting blue light (abbreviated as "B"), the second sub-pixel may include a sub-pixel emitting green light (abbreviated as "G") and/or a sub-pixel emitting red light (abbreviated as "R"), and the luminance lifetimes of the sub-pixels BG and/or BR are less than that of the sub-pixel BB. Similarly, the first type of sub-pixel may include not only a sub-pixel containing one color, such as sub-pixel B, but also at least one sub-pixel of another color, such as sub-pixel G. Meanwhile, the number and color of the sub-pixels included in each pixel unit are not limited to the scheme described in fig. 2, and other design schemes may be included, for example, each pixel includes a plurality of sub-pixels arranged in RGBG. The design can be made according to the actual requirements of the display panel.

In the display panel, carriers comprise holes and electrons, so that the difference of the brightness life time among the sub-pixels with different colors can be changed by changing the hole mobility, or changing the electron mobility, or simultaneously changing the hole mobility or the electron mobility, and the problem of display color cast of the display panel is improved. The following is a detailed description of different schemes for varying electron mobility and causing electron mobility in different electron transport layers in different color sub-pixels.

Considering that the electron mobility is greater than the hole mobility in the same light-emitting layer, in order to increase the amount of recombination of electrons and holes injected into the light-emitting layer, the electron mobility can be reduced so that more electrons can still migrate in the light-emitting layer and not pass through the light-emitting layer when holes reach the light-emitting layer. In some embodiments, the carrier transport layer comprises an electron transport layer located between the cathode and the light emitting layer, and the electron mobility of the electron transport layer of the first type of sub-pixel is less than the mobility of the electron transport layer of the second type of sub-pixel.

By defining that the electron mobility of the electron transport layer of the first type sub-pixel is smaller than that of the electron transport layer of the second type sub-pixel, the carrier recombination zone in the light emitting layer corresponding to the first type sub-pixel is enlarged, i.e. more electrons and holes are recombined to generate excitons. The increase of the number of excitons improves the brightness service life of the first-class sub-pixels, so that the difference between the brightness service life of the first-class sub-pixels and the brightness service life of the second-class sub-pixels is reduced, and the problem of color cast of the display panel is relieved.

Specifically, as shown in fig. 2, in the RBG three-color pixel, the sub-pixel B is a first type sub-pixel, the sub-pixels R and G are a second type sub-pixel, and the electron mobility of the corresponding B-ETL is smaller than that of the R-ETL and G-ETL. This makes the carrier recombination region of the sub-pixel B having the smallest luminance lifetime large, improves the lifetime of the sub-pixel B, and reduces the luminance difference between the sub-pixel B and the sub-pixels R and G.

Of course, the RGB sub-pixels may be reclassified according to the luminance lifetime between the sub-pixels with different luminance. Specifically, as shown in fig. 2, in the RBG three-color pixel, the sub-pixel B and the sub-pixel G are sub-pixels of a first type, the sub-pixel R is a sub-pixel of a second type, and the electron mobility of B-ETL and R-ETL is smaller than that of G-ETL. Meanwhile, the brightness service life of the sub-pixels which are relatively small is prolonged, the difference of the brightness service life of the sub-pixels with the maximum brightness service life is shortened, and the problem of color cast of display is relieved.

In the same pixel, there are various ways to realize that the electron mobility of the electron transport layer of the first type sub-pixel is smaller than that of the second type sub-pixel, and the scheme of making the electron mobility of the electron transport layer of the first type sub-pixel smaller and/or making the electron mobility of the electron transport layer of the second type sub-pixel larger is all possible. The following description is made in detail with respect to the design of the electron transport layer of the first type of sub-pixels and/or the second type of sub-pixels.

In some embodiments, the electron transport layer of the first type of sub-pixel and the electron transport layer of the second type of sub-pixel both include a first film layer, and the electron transport layer of the first type of sub-pixel further includes a second film layer, the second film layer having an electron mobility less than the electron mobility of the first film layer and being located between the first film layer and the light emitting layer of the first type of sub-pixel. Furthermore, the first-type sub-pixels comprise a plurality of sub-pixels which emit light with different wavelengths, and the thickness of the second film layer of the sub-pixels with the larger wavelength of the emitted light is larger.

Only the electron transport layer of the first-class sub-pixel with the short brightness life in the pixel is set to be a composite film layer, and the film layer with the small electron mobility is compounded on one side, facing the light emitting layer, of the original first film layer, so that electrons in the first-class pixel enter the light emitting layer at a slow speed relative to electrons in the second-class pixel and are longitudinally transported in the light emitting layer at the slow speed, a carrier composite area is increased, the number of electrons passing through the light emitting layer of the first-class sub-pixel in unit time is reduced, more electrons and holes are compounded to generate more excitons, and the brightness life of the first-class sub-pixel is prolonged. Furthermore, the thickness of the second film layer added in the first-class sub-pixels is designed according to the wavelength of emergent light, so that the brightness difference among all the sub-pixels of the display panel is improved, and the problem of color cast of display is effectively solved.

As shown in fig. 3, in the RBG three-color pixel, the sub-pixel B is a first sub-pixel, the sub-pixels R and G are second sub-pixels, the electron transport layers corresponding to the three sub-pixels R, B, G each include a first film 411, and a second film 412 with smaller electron mobility is disposed between the B-ETL layer and the B-EML layer. The first film layer 411 having a high electron mobility is positioned between the cathode 1 and the B-EML, and the second film layer 412 having a low electron mobility is positioned between the first film layer 411 and the B-EML. The electron mobility in the film layer structure close to or adjacent to the B-EML is reduced from large, electrons enter the B-EML at a slow speed, and a carrier recombination region of the B-EML moves and becomes large from the outer edge of the B-EML close to the cathode 1 to the direction close to the anode 2, so that the carrier recombination efficiency is improved even if the recombination region moves towards the middle position of the B-EML, and the brightness service life of the sub-pixel B is prolonged.

The RGB sub-pixels may be further classified again according to the magnitude relationship of the luminance lifetime, specifically, as shown in fig. 4, the sub-pixels B and G are first type sub-pixels, and the sub-pixel R is a second type sub-pixel. Then the second film layer 412 having small electron mobility is disposed between the first film layer 411 and the light emitting layers (B-EML and G-EML) of the B-ETL layer and the G-ETL layer, respectively, and the luminance life of the sub-pixels B and G is improved by reducing the electron mobility of the sub-pixels B and G to reduce the luminance difference between the RGB pixels. Meanwhile, considering that the luminance lifetime of the sub-pixel B is less than that of the sub-pixel G, the thickness D of the second film layer 411 of the sub-pixel B, in which the wavelength of the outgoing light is large _B2 Thickness D of second film layer 412 of sub-pixel G with wavelength larger than that of emergent light _G2 I.e. D _B2 ＞D _G2 Within the first class of sub-pixels is reducedThe difference of the brightness service life between the sub-pixels emitting light with different colors further reduces the difference of the brightness service life of different sub-pixels in the same pixel, and further relieves the problem of color cast.

In addition to increasing the luminance lifetime of the first type of sub-pixels, decreasing the luminance lifetime of the second type of sub-pixels also reduces the luminance difference between the first type of sub-pixels and the second type of sub-pixels. In other embodiments, the electron transport layer of the first type of sub-pixel and the electron transport layer of the second type of sub-pixel both include a first film layer, and the electron transport layer of the second type of sub-pixel further includes a second film layer, the second film layer having an electron mobility greater than the electron mobility of the first film layer and being located between the first film layer and the light emitting layer of the second type of sub-pixel. Further, the second type of sub-pixel includes a plurality of sub-pixels emitting light of different wavelengths, and the sub-pixels emitting light of a larger wavelength have a smaller thickness of the second film layer.

An electron transmission layer with high electron mobility, namely a second film layer, which is larger than the first film layer is added between the first film layer of the electron transmission layer corresponding to the second type of sub-pixel and the light emitting layer of the second type of sub-pixel, so that the electron mobility of the first type of sub-pixel is not influenced, the average electron mobility of electrons corresponding to the second type of sub-pixel entering the transmission layer is increased, more electrons pass through the light emitting layer and do not participate in carrier recombination, therefore, the carrier recombination zone in the light emitting layer of the second type of sub-pixel is reduced, the total quantity of exciton recombination in the light emitting layer of the second type of sub-pixel is also reduced, the brightness life of the second type of sub-pixel is further reduced, the difference of the brightness life between the first type of sub-pixel and the second type of sub-pixel is finally reduced, and the problem of color cast of display is improved.

The three RGB sub-pixels are divided into two classes of sub-pixels according to the luminance lifetime of the different sub-pixels, which include two classification schemes, as follows.

In the first scheme, as shown in fig. 5, the sub-pixels B and G are divided into sub-pixels of a first type, and the sub-pixels R are divided into sub-pixels of a second type. The second film layer 422 with high electron mobility is arranged between the first film layer 411 of the R-ETL and the R-EML, and is not arranged between the first film layer 411 of the G-ETL and the G-EML as well as between the first film layer 411 of the B-ETL and the G-BML, so that the electron mobility of the sub-pixel R is increased, the number of electrons staying in the sub-pixel R in unit time is reduced, the moving speed of the electrons in the R-EML layer is higher, a carrier recombination area is reduced, and the brightness life of the sub-pixel R is shortened.

In the second scheme, as shown in fig. 6, in the RGB pixel, the sub-pixel B is a first-type sub-pixel, the sub-pixel R and the sub-pixel G are a second-type sub-pixel, and the electron transport layers of the three sub-pixels each include a first film layer 411, and the electron transport layers of the sub-pixel R and the sub-pixel G are further provided with a second film layer 412 with high electron mobility between the R-EML and the first film layer 411, and between the G-EML and the first film layer 411. The electron transfer speed of the sub-pixel R and the sub-pixel G is improved, and the brightness service life of the sub-pixel R and the sub-pixel G is reduced. Although the R-ETL includes the first film 411 and the second film 412, and the G-ETL also includes the first film 411 and the second film 412, the second films 412 of the sub-pixels R and G are set to different film thicknesses in order to further reduce the difference in luminance lifetime of all sub-pixels in the pixel, considering that the luminance lifetime of the sub-pixel R is greater than that of the sub-pixel G. The wavelength of the light emitted from the sub-pixel G is large, so the thickness D of the second film layer of the sub-pixel G is large _G2 Thickness D of second film layer smaller than sub-pixel R _R2 That is, the thickness of the second film 412 of the sub-pixel G with a short luminance lifetime is small, so that fewer electrons are accelerated relative to the sub-pixel R, and the lifetime of the sub-pixel G is reduced less than that of the sub-pixel R, which is more beneficial to balancing the difference of luminance lifetimes between sub-pixels with different luminance lifetimes, and further improving the problem of color cast.

In order to improve the problem of color cast more effectively, in other embodiments, the electron transport layer of the first type of sub-pixel and the electron transport layer of the second type of sub-pixel both include a first film layer and a second film layer, the electron mobility of the second film layer is smaller than that of the first film layer, and the second film layer is respectively located between the first film layer and the light emitting layers of the first type of sub-pixel and the second type of sub-pixel; the thickness of the second film layer of the first-type sub-pixel is larger than that of the second film layer of the second-type sub-pixel. Furthermore, the first-type sub-pixels comprise a plurality of sub-pixels for emitting light with different wavelengths, and the second film layer of the sub-pixels with the larger wavelength of the emitted light is thicker; and/or the second type of sub-pixel comprises a plurality of sub-pixels emitting light with different wavelengths, and the second film layer of the sub-pixel emitting light with the larger wavelength is thicker.

In the above scheme, the design scheme that the electron transport layer of the first-type sub-pixel and the electron transport layer of the second-type sub-pixel are both provided with the second film layer with small electron mobility makes more electrons in the first-type sub-pixel enter the light emitting layer at a slow speed, so that a carrier recombination region is enlarged, more electrons participate in recombination to generate excitons, and the service life of the brightness of the first-type sub-pixel is prolonged. And the electron transmission layers of different sub-pixels are limited by the same film layer structure, so that the production is convenient, and the cost is saved. Furthermore, the thicknesses of the second film layers arranged among the sub-pixels with different light emitting colors in the same type of sub-pixels are different according to the wavelength of light emitted among the sub-pixels, so that the difference of the brightness service lives of the sub-pixels with different colors in the same type of sub-pixels is reduced, the design is more refined, the difference of the brightness service lives of the different sub-pixels in the pixels is reduced more uniformly, and the problem of color cast in display is further effectively relieved.

Specifically, as shown in fig. 7, the first sub-pixel includes a sub-pixel B, the second sub-pixel includes a sub-pixel R and a sub-pixel G, the electron transport layers corresponding to the sub-pixels of different colors each include a first film layer 411 and a second film layer 412 with small electron mobility, and the thickness D of the second film layer 412 corresponding to the sub-pixel B with the largest wavelength of the emitted light is arranged according to the wavelength of the light emitted from the sub-pixel R, G, B, that is, R < G < B _B2 The thickness D of the second film 412 corresponding to the sub-pixel R with the largest wavelength of the emitted light _R2 And minimum. The design ensures that the brightness service life of all the sub-pixels in the pixel is adjusted, is favorable for balancing the brightness service life difference among the sub-pixels with different colors, and effectively improves the problem of color cast of display.

In order to save the production process, in some embodiments, in the case that the electron transport layer of the first type of sub-pixel and the electron transport layer of the second type of sub-pixel both include the first film layer and the second film layer, the total thicknesses of the first film layer and the second film layer between different sub-pixels are equal, and the thickness of the second film layer of the first type of sub-pixel is greater than that of the second film layer of the second type of sub-pixel.

Specifically, as shown in fig. 7, the electron transport layers 41 corresponding to the three sub-pixels R, G and B respectively include a first film layer 411 and a second film layer 412 having a small electron mobility. The first film layer 411 of different sub-pixels and the second film layer 412 of different sub-pixels are made of the same material and have the same thickness, i.e. D _R1 +D _R2 ＝D _G1 +D _G2 ＝D _B1 +D _B2 Whether the thicknesses of the different film layers of the electron transport layer 41 corresponding to the sub-pixels R, G and B are related to their own luminance lifetimes, the thicker the higher the luminance lifetime, the thicker the higher the mobility sub-pixel, and the thinner the corresponding mobility sub-film, i.e., D _B1 ＜D _G1 ＜D _R1 ，D _B2 ＞D _G2 ＞D _R2 . According to the display requirement calculation of the display panel, the following results are obtained:

D _B1 ＝π/2*D _EBL ，D _B2 ＝πN/2*D _EBL +D _BML

n, K, the modulation coefficients of the results of the Hole Only Device (HOD) and the Electron Only Device (EOD), N is the refractive index, K is the extinction coefficient, the two change with the change of the material and thickness of the Electron transport layer, D _EBL Thickness of the electronic component monolayer, D _BML The thickness of the blue light emitting layer. The calculation method is also applicable to the calculation of the thicknesses of the corresponding electron transport layers in the red sub-pixel and the green sub-pixel.

In addition to the addition of the composite film layer, in other embodiments, a doping method may be further considered to be used to reduce the luminance lifetime between the first-type sub-pixel and the second-type sub-pixel by changing the electron mobility of the electron transport layer of the first-type sub-pixel and/or the second-type sub-pixel.

In the first scheme, the electron transport layer of the first-type sub-pixel is made of a base material layer doped with a second-type material, the base material layer is made of the first-type material, the electron transport layer of the second-type sub-pixel is made of the first-type material, the second-type material is doped on the side, facing the light emitting layer, of the base material layer of the first-type sub-pixel, and the electron mobility of the second-type material is smaller than that of the first-type material. Specifically, as shown in fig. 2, the second type of material with small electron mobility is doped only on the side of the B-ETL of the sub-pixel B located at the B-EML, increasing the luminance lifetime of the sub-pixel B.

Further, the first-type sub-pixels include a plurality of sub-pixels emitting light of different wavelengths, and the sub-pixels emitting light of longer wavelengths have higher doping concentrations of the second-type material. Specifically, as shown in fig. 2, the second type material is doped at a first concentration on the side of the sub-pixel B where the B-ETL is located at the B-EML, and the second type material is doped at a second concentration on the side of the sub-pixel G where the G-ETL is located at the G-EML, and the first concentration is greater than the second concentration because the wavelength of the light emitted from the sub-pixel B is greater than that of the light emitted from the sub-pixel G. And meanwhile, doping treatment with different concentrations is carried out on all the sub-pixels in the first type of sub-pixels, so that the difference of brightness service life among the sub-pixels in the first type of sub-pixels is reduced, and the problem of color cast in display is better solved.

In the first scheme, the electron mobility of the electron transport layer corresponding to the first-class pixels is reduced in a doping mode, electrons corresponding to the first-class pixels enter the light emitting layer at a slow speed, the size of a carrier recombination region is increased, more electrons and holes are recombined, the brightness service life of the first-class sub-pixels is prolonged, the brightness difference between the first-class sub-pixels and the second-class sub-pixels is reduced, and the problem of color cast in display is solved. And the doping mode is simple and convenient to realize, and the production cost is saved. Furthermore, doping treatment is performed on all the sub-pixels included in the first sub-pixel, so that the brightness life difference between the first sub-pixel and the second sub-pixel can be improved in a balanced manner, and the problem of color cast in display is relieved more effectively.

In the second scheme, the material of the electron transport layer of the first-type sub-pixel is a first-type material, the material of the electron transport layer of the second-type sub-pixel is a substrate layer doped with a second-type material, the substrate layer is composed of the first-type material, the second-type material is doped on the side, facing the light emitting layer, of the substrate layer of the second-type sub-pixel, and the electron mobility of the second-type material is greater than that of the first-type material. For example, as shown in FIG. 2, the second type of material with high electron mobility is doped only on the side of R-ETL of R located at R-EML, reducing the luminance lifetime of R.

Further, the second-type sub-pixel includes a plurality of sub-pixels emitting light of different wavelengths, and the sub-pixels emitting light of a larger wavelength have a smaller doping concentration of the second-type material. Specifically, as shown in fig. 2, the second type of material is doped at a first concentration on the side of the R-ETL of the sub-pixel R located at the R-EML, and the second type of material is doped at a second concentration on the side of the G-ETL of the sub-pixel G located at the G-EML, and the second concentration is less than the first concentration because the wavelength of the light emitted from the sub-pixel G is greater than the wavelength of the light emitted from the sub-pixel R.

In the second scheme, the second type of material with high electron mobility is doped in the electron transport layer of the second type of sub-pixels, so that the brightness life of the second type of sub-pixels is reduced. Furthermore, the second materials with different concentrations are doped according to the wavelengths of the light emitted by all the sub-pixels in the second sub-pixels, so that the brightness life of all the sub-pixels of the second sub-pixels can be reasonably reduced, the reduction of the brightness life difference between the first sub-pixels and the second sub-pixels is facilitated, and the problem of color cast in display is effectively solved.

In a third aspect, in some embodiments, the material of the electron transport layer of the first-type sub-pixel and the material of the electron transport layer of the first-type sub-pixel are both substrate layers doped with a second-type material, the substrate layers are composed of the first-type material, the second-type material is doped on the side, facing the light emitting layer, of the substrate layers of the first-type sub-pixel and the second-type sub-pixel, the electron mobility of the second-type material is smaller than that of the first-type material, and the doping concentration of the second-type material in the substrate layer of the first-type sub-pixel is greater than that in the substrate layer of the second-type sub-pixel. Furthermore, the first-class sub-pixels comprise a plurality of sub-pixels for emitting light with different wavelengths, and the doping concentration of the second-class material of the sub-pixels with the larger wavelength of the emitted light is larger; and/or the second-type sub-pixel comprises a plurality of sub-pixels which emit light with different wavelengths, and the doping concentration of the second-type material of the sub-pixel with the larger wavelength of the emitted light is larger.

Specifically, as shown in FIG. 2, the second type of material is doped at a first concentration on the side of the R-ETL of the sub-pixel R where the R-ETL is located, the second type of material is doped at a second concentration on the side of the G-ETL of the sub-pixel G where the G-EML is located, and the second type of material is doped at a third concentration on the side of the B-ETL of the sub-pixel B where the B-EML is located. Since the wavelength of light emitted from the sub-pixel B is longer than that of light emitted from the sub-pixel G, and the wavelength of light emitted from the sub-pixel G is longer than that of light emitted from the sub-pixel R, the third concentration is higher than the second concentration, and the second concentration is higher than the first concentration.

In the third scheme, the electron transport layers of the first-class sub-pixels and the second-class sub-pixels are doped with the second-class material with low electron mobility, but the doping concentration of the first-class sub-pixels is greater than that of the second-class sub-pixels, so that the medium electrons of the first-class sub-pixels enter the light emitting layer at a slower speed, the brightness life of the first-class sub-pixels is prolonged, and the problem of display color cast is improved. Furthermore, doping treatment is carried out on all the sub-pixels, and the concentration of the doped second material is adjusted according to different wavelength relations of light emitted by the sub-pixels, so that the difference of brightness service life among all the sub-pixels can be effectively reduced, and the problem of color cast of display can be effectively improved.

The size factor of the recombination zone of the carriers in the light emitting layer corresponding to the first-type sub-pixel and/or the second sub-pixel is considered to also comprise holes. In some embodiments, the carrier transport layer comprises a hole transport layer between the anode and the light emitting layer, and the hole transport layer of the first type of sub-pixel has a hole mobility greater than the hole transport layer of the second type of sub-pixel. The hole mobility of the hole transport layer of the first-class sub-pixel is limited to be larger than that of the hole transport layer of the second-class sub-pixel, holes corresponding to the first-class sub-pixel can enter the light emitting layer of the first-class sub-pixel more quickly to carry out recombination reaction with electrons, the carrier recombination efficiency of the first-class sub-pixel is improved, more excitons are generated, and the brightness life of the first-class sub-pixel is further prolonged.

Specifically, as shown in FIG. 2, the hole mobility of the B-HTL is greater than the hole mobility of the R-HTL and the G-HTL. This enlarges the carrier recombination region of the sub-pixel B, improves the life of the sub-pixel B, and reduces the luminance difference between the sub-pixel B and the sub-pixels R and G.

Regarding the design of the hole transport layer of the first type of sub-pixel and/or the hole transport layer of the second type of sub-pixel, from the viewpoint of saving the production cost and improving the performance of the display panel, the specific design scheme regarding the hole transport layer is as follows.

In some embodiments, the hole transport layer of the first-type sub-pixel and the hole transport layer of the second-type sub-pixel both include a third film layer, and the hole transport layer of the first-type sub-pixel further includes a fourth film layer, which has a hole mobility greater than that of the third film layer and is located between the third film layer and the light emitting layer of the first-type sub-pixel. Furthermore, the first-type sub-pixels comprise a plurality of sub-pixels for emitting light with different wavelengths, and the thickness of the fourth film layer of the sub-pixels with the larger wavelength of the emitted light is larger.

Due to the design of the composite film layer of the hole transport layer corresponding to the first-class sub-pixel, holes can enter the light emitting layer of the first-class sub-pixel at a high speed, the size of a carrier composite area in the light emitting layer is increased, and the brightness service life of the first-class sub-pixel is prolonged. And the fourth film layer is further designed according to the wavelength of emergent light, namely the brightness service life of all the sub-pixels in the first type of sub-pixels, so that the difference of the brightness service lives of all the sub-pixels of the first type of sub-pixels and the second type of sub-pixels can be improved more uniformly, and the problem of color cast of display can be improved more effectively.

Specifically, as shown in fig. 8, in the RBG three-color pixel, the sub-pixel B is a first-type sub-pixel, the sub-pixels R and G are a second-type sub-pixel, the hole transport layers corresponding to the RBG include a third film 421, and a fourth film 422 with a higher hole mobility is disposed between the B-HTL layer and the B-EML layer. The third film 421 having a small hole mobility is positioned between the anode 2 and the B-EML, and the second film 422 having a large hole mobility is positioned between the first film 421 and the B-EML. The mobility of holes in the film structure close to or close to the B-EML is changed from small to large, so that the holes enter the B-EML at a high speed, the carrier recombination zone of the B-EML moves and becomes large from the outer edge of the B-EML close to the cathode to the direction close to the anode, and even if the recombination zone moves towards the middle position of the B-EML, the carrier recombination efficiency of the sub-pixel B is improved, and the brightness service life of the sub-pixel B is prolonged.

In order to further improve the brightness difference before the RGB sub-pixels and improve the color shift problem, as shown in fig. 9, the sub-pixel B and the sub-pixel G with the brightness lifetime not being the maximum are used as the second type of sub-pixel, the fourth film layer 422 is disposed between the third film layer 421 and the B-EML of the sub-pixel B, the fourth film layer 422 is disposed between the third film layer 421 and the G-EML of the sub-pixel G, and the thickness D of the fourth film layer 421 of the sub-pixel B is larger than the thickness D of the fourth film layer 421 _B4 Thickness D of fourth film layer 422 larger than sub-pixel G _G4 . The difference between the luminance lifetime of the sub-pixel B and the luminance lifetime of the sub-pixel G and the sub-pixel R with the maximum luminance lifetime is reduced, and the problem of color cast in display is effectively improved.

In some embodiments, the hole transport layer of the first type of sub-pixel and the hole transport layer of the second type of sub-pixel both include a third film layer, and the hole transport layer of the second type of sub-pixel further includes a fourth film layer, which has a hole mobility less than that of the third film layer and is located between the third film layer and the light emitting layer of the second type of sub-pixel. Further, the second type of sub-pixel includes a plurality of sub-pixels emitting light of different wavelengths, and the thickness of the fourth film layer of the sub-pixel, which emits light of a larger wavelength, is smaller.

The fourth film layer with low hole mobility arranged in the second sub-pixel enables holes to enter the light emitting layer at a low speed, reduces the number of the holes entering the light emitting layer of the second sub-pixel in unit time, reduces the size of a carrier recombination zone, and reduces the efficiency of carrier recombination, namely reduces the generation of excitons, thereby reducing the brightness life of the second sub-pixel.

Specifically, the RGB pixels are taken as an example, and two cases such as fig. 10 and fig. 11 are included.

In the first case, as shown in fig. 10, the sub-pixels B and G are divided into sub-pixels of a first type, and the sub-pixels R are divided into sub-pixels of a second type. The fourth film layer 422 with small hole mobility is only arranged between the third film layer 421 and the R-EML of the R-HTL, compared with other sub-pixels, the hole mobility of the sub-pixel R is small, the number of holes staying in the sub-pixel R in unit time is small, the moving speed of the holes in the R-EML layer is slower, a carrier recombination area is small, and the brightness life of the sub-pixel R is shortened.

In the second case, as shown in fig. 11, not only the hole transport layer for R but also the G-HTL layer of the sub-pixel G is designed, i.e., a fourth film layer 422 with a smaller hole mobility is disposed between the third film layer 421 and the G-EML of the sub-pixel G. Thus, the types of hole migration of the sub-pixel R and the sub-pixel G are reduced, and the luminance lifetime of the sub-pixel R and the sub-pixel G is reduced. In order to further reduce the difference of the brightness lifetime of all sub-pixels in the pixel, the wavelength of the emitted light is larger than the thickness D of the fourth film layer of the sub-pixel G _G4 Thickness D of fourth film layer smaller than sub-pixel R _R4 Therefore, the speed of the small hole migration is slower than that of the sub-pixel R, and the lifetime of the sub-pixel G is reduced less than that of the sub-pixel R, which is more beneficial to balance the difference of the luminance lifetimes between the sub-pixels with different luminance lifetimes, and effectively improve the problem of color cast.

In some embodiments, the hole transport layer of the first-type sub-pixel and the hole transport layer of the second-type sub-pixel both include a third film layer and a fourth film layer, the fourth film layer has a hole mobility greater than that of the third film layer and is respectively located between the third film layer and the light emitting layers of the first-type sub-pixel and the second-type sub-pixel, and the fourth film layer of the first-type sub-pixel has a thickness greater than that of the fourth film layer of the second-type sub-pixel. Furthermore, the first-type sub-pixels comprise a plurality of sub-pixels for emitting light with different wavelengths, and the thickness of the fourth film layer of the sub-pixels with the larger wavelength of the emitted light is larger; and/or the second type of sub-pixel comprises a plurality of sub-pixels emitting light with different wavelengths, and the thickness of the fourth film layer of the sub-pixel is larger as the wavelength of the emitted light is larger.

Specifically, as shown in fig. 12, in the RGB pixels, the first-type sub-pixel includes a sub-pixel B, the second-type sub-pixel includes a sub-pixel R and a sub-pixel G, the hole transport layers corresponding to the sub-pixels of different colors each include a third film layer and a fourth film layer having a small hole mobility, and according to the arrangement of the wavelength of the light emitted from the sub-pixel R, the sub-pixel G and the sub-pixel B, that is, R < G < B, the thickness of the fourth film layer corresponding to the sub-pixel B having the largest wavelength of the emitted light is the largest, and the thickness of the fourth film layer corresponding to the sub-pixel R having the smallest wavelength of the emitted light is the smallest. The design ensures that the brightness service lives of all the sub-pixels in the pixel are adjusted, thereby being beneficial to balancing the brightness service life difference among the sub-pixels with different colors and effectively improving the problem of color cast.

In order to improve the color cast of the display panel more effectively and reduce the lifetime or brightness of the display panel, in some embodiments, in the case that the hole transport layer of the first type of sub-pixel and the hole transport layer of the second type of sub-pixel both include the third film layer and the fourth film layer, the total thickness of the third film layer and the fourth film layer between different sub-pixels is equal, and the thickness of the fourth film layer of the first type of sub-pixel is greater than that of the fourth film layer of the second type of sub-pixel. More holes enter the first-class sub-pixels at a high speed, so that the brightness service life of the first-class sub-pixels is prolonged, the processing technology of the hole injection layer is simplified, and the production is facilitated.

In particular toAs shown in fig. 12, the electron transport layers corresponding to the three sub-pixels R, G and B each include a third film layer and a fourth film layer, and the thickness of the third film layer and the total thickness of the fourth film layer corresponding to different sub-pixels are equal, i.e. D _R3 +D _R4 ＝D _G3 +D _G4 ＝D _B3 +D _B4 But the thickness of the same film layer varies between sub-pixels. Whether the thicknesses of the different film layers of the electron transport layer 41 corresponding to the sub-pixels R, G and B are related to their own luminance lifetimes, the thicker the higher the luminance lifetime, the thicker the higher the mobility sub-pixel, and the thinner the corresponding mobility sub-film, i.e., D _B3 ＜D _G3 ＜D _R3 ，D _B4 ＞D _G4 ＞D _R4 ，D _B3 Thickness of the third film layer of the sub-pixel B, D _B4 Is the thickness of the fourth film layer of the sub-pixel B, D _G3 Thickness of the third film layer of the sub-pixel G, D _G4 Is the thickness of the fourth film layer of the sub-pixel G, D _R3 Thickness of the third film layer of the sub-pixel R, D _R4 Is the thickness of the fourth film layer of the sub-pixel R. The following are calculated according to the display requirements of the display panel:

D _B3 ＝π/2*D _EBL ，D _B4 ＝πN/2*D _EBL +D _BML

n, K, the modulation coefficients of the results of the Hole Only Device (HOD) and the Electron Only Device (EOD), N is the refractive index, K is the extinction coefficient, the two change with the change of the material and thickness of the Electron transport layer, D _EBL Thickness of the electronic component monolayer, D _BML The thickness of the blue light emitting layer. The calculation method is also suitable for calculating the film thickness of the hole transmission layer in the red sub-pixel and the green sub-pixel.

For the design of the hole transport layer, besides adding the sub-film layers with different hole mobility rates, a doping mode can be adopted to improve the hole mobility rate of the first type of sub-pixels or reduce the hole mobility rate of the second type of sub-pixels, and the specific scheme is as follows.

In some embodiments, the material of the hole transport layer of the first-type sub-pixel is a substrate layer doped with a fourth-type material, the substrate layer is composed of the third-type material, the material of the hole transport layer of the second-type sub-pixel is the third-type material, the fourth-type material is doped on the side, facing the light emitting layer, of the substrate layer of the first-type sub-pixel, and the hole mobility of the fourth-type material is greater than that of the third-type material. Specifically, as shown in fig. 2, the fourth type material having a large hole mobility is doped only on the side of the B-HTL of the sub-pixel B where the B-EML is located. The mobility of holes entering the B-EML layer is improved, the size of a carrier recombination region is increased, and the service life of the sub-pixel B is prolonged.

Furthermore, the first-type sub-pixels comprise a plurality of sub-pixels which emit light with different wavelengths, and the doping concentration of the fourth-type material of the sub-pixels with the larger wavelength of the emitted light is larger. Specifically, as shown in fig. 2, the fourth type material is doped at a first concentration on the side of the sub-pixel B where the B-HTL is located in the B-EML, and the fourth type material is doped at a second concentration on the side of the sub-pixel G where the G-HTL is located in the G-EML, and the first concentration is greater than the second concentration because the wavelength of light emitted from the sub-pixel B is greater than that of light emitted from the sub-pixel G. The brightness difference among all the sub-pixels is reduced, and the problem of display color cast is effectively improved.

In other embodiments, the material of the hole transport layer of the first type of sub-pixel is a third type of material, the material of the hole transport layer of the second type of sub-pixel is a substrate layer doped with a fourth type of material, the substrate layer is composed of the third type of material, the fourth type of material is doped on the side, facing the light emitting layer, of the substrate layer of the second type of sub-pixel, and the hole mobility of the fourth type of material is smaller than that of the third type of material. For example, as shown in FIG. 2, the fourth type of material with low hole mobility is doped only on the side of the R-HTL of the sub-pixel R, which is located on the R-EML side, thereby reducing the luminance lifetime of the sub-pixel R.

Further, the second type sub-pixel includes a plurality of sub-pixels emitting light of different wavelengths, and the sub-pixels emitting light of a larger wavelength have a smaller doping concentration of the fourth type material. Specifically, as shown in fig. 2, the fourth type material is doped at a first concentration on the side of the R-HTL of the sub-pixel R positioned at the R-EML, and the fourth type material is doped at a second concentration on the side of the G-HTL of the sub-pixel G positioned at the G-EML, because the wavelength of the light emitted by the sub-pixel G is greater than that of the light emitted by the sub-pixel R, the second concentration is less than the first concentration, and the luminance lifetimes of the other sub-pixels except for the sub-pixel B with the smallest luminance lifetime are all reduced, so that the difference in luminance lifetimes between all sub-pixels is more effectively reduced, and the problem of color cast is effectively improved.

In other embodiments, the material of the hole transport layer of the first-type sub-pixel and the material of the hole transport layer of the first-type sub-pixel are both substrate layers doped with a fourth-type material, the substrate layers are composed of the third-type material, the fourth-type material is doped on the sides, facing the light-emitting layer, of the substrate layers of the first-type sub-pixel and the substrate layers of the second-type sub-pixel respectively, the hole mobility of the fourth-type material is greater than that of the third-type material, and the doping concentration of the fourth-type material in the substrate layers of the first-type sub-pixel is greater than that in the substrate layers of the second-type sub-pixel; preferably, the first-type sub-pixels comprise a plurality of sub-pixels for emitting light with different wavelengths, and the doping concentration of the fourth-type material of the sub-pixels with larger wavelength of the emitted light is larger; and/or the second type of sub-pixel comprises a plurality of sub-pixels for emitting light with different wavelengths, and the doping concentration of the fourth type of material of the sub-pixels with larger wavelength of the emitted light is larger.

Specifically, as shown in FIG. 2, the R-HTL of R is doped with the fourth type of material at a first concentration on the side of the R-EML, the G-HTL of the sub-pixel G is doped with the fourth type of material at a second concentration on the side of the G-EML, and the B-HTL of the sub-pixel B is doped with the fourth type of material at a third concentration on the side of the B-EML. Since the wavelength of light emitted from the sub-pixel B is longer than that of light emitted from the sub-pixel G, and the wavelength of light emitted from the sub-pixel G is longer than that of light emitted from the sub-pixel R, the third concentration is higher than the second concentration, and the second concentration is higher than the first concentration. The brightness life among different sub-pixels is improved uniformly, the difference of the brightness life among all the sub-pixels is reduced more effectively, and the problem of color cast in display is improved effectively.

It should be understood that the specific types and the specific doping concentrations of the second type material doped for electron transport and the fourth type material doped for hole transport layer, and the differences in doping between different sub-pixels, can be designed according to the functional requirements of the display panel, for example, the electron transport layers of different sub-pixels are doped with the same second type material with different concentrations, or the hole transport layers of different sub-pixels are doped with the same fourth type material with the same concentration. The display panel may further include other functional layer structures such as a hole injection layer between the anode and the hole transport layer, an electron blocking layer between the hole transport layer and the light emitting layer, an electron injection layer between the cathode and the electron transport layer, and a hole blocking layer between the electron transport layer and the light emitting layer. The display panel adopts a multilayer structure, so that current carriers of an anode and a cathode are easier to inject into the organic functional film, and the luminous efficiency of the display panel is improved.

Except that the electron transport layer and the hole transport layer of the sub-pixel can be respectively improved, the design of the electron transport layer and the hole transport layer can be improved at the same time as shown in fig. 13, and the specific scheme is described in detail above, and thus is not described herein again. It should be understood that the scheme for improving both the electron transport layer and the hole transport layer of the sub-pixel is not limited to the scheme in fig. 13, and a certain film layer of the electron transport layer and the hole transport layer may also be improved, and the specific improvement scheme is not described herein again.

The embodiment also provides a display device. The display device comprises any one of the display panels provided by the first aspect. The display device is any product or component with a display function, such as a mobile phone, a tablet computer, a television, a navigator, a vehicle-mounted application and the like.

The above description is only for the specific embodiments of the present application, but the scope of the present application is not limited thereto, and any person skilled in the art can conceive of changes or substitutions within the technical scope of the present application, and shall be covered by the scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.

Claims

1. A display panel, comprising: a plurality of pixel units, each of the pixel units comprising a plurality of sub-pixels, the plurality of sub-pixels being divided into a first type of sub-pixels and a second type of sub-pixels, the luminance lifetime of the first type of sub-pixels being less than the luminance lifetime of the second type of sub-pixels;

each of the sub-pixels includes: a cathode, an anode, and a light emitting layer and a carrier transport layer between the cathode and the anode;

the carrier mobility of the carrier transmission layer of the first type of sub-pixel is different from the carrier mobility of the carrier transmission layer of the second type of sub-pixel.

2. The display panel according to claim 1, wherein the carrier transport layer comprises an electron transport layer between the cathode and the light emitting layer, and wherein the electron mobility of the electron transport layer of the first type of sub-pixel is smaller than the mobility of the electron transport layer of the second type of sub-pixel.

3. The display panel according to claim 2, wherein the electron transport layer of the first-type sub-pixel and the electron transport layer of the second-type sub-pixel both comprise a first film layer, the electron transport layer of the first-type sub-pixel further comprises a second film layer, the electron mobility of the second film layer is smaller than that of the first film layer and is located between the first film layer and the light emitting layer of the first-type sub-pixel, preferably, the first-type sub-pixel comprises a plurality of sub-pixels emitting light with different wavelengths, and the thickness of the second film layer of the sub-pixel emitting light with the larger wavelength is larger; or

The electron transport layer of the first-type sub-pixel and the electron transport layer of the second-type sub-pixel both comprise a first film layer, the electron transport layer of the second-type sub-pixel further comprises a second film layer, the electron mobility of the second film layer is greater than that of the first film layer, and the second film layer is located between the first film layer and the light emitting layer of the second-type sub-pixel, preferably, the second-type sub-pixel comprises a plurality of sub-pixels emitting light with different wavelengths, and the larger the wavelength of the emitted light, the smaller the thickness of the second film layer of the sub-pixel is; or

The electron transmission layer of the first-type sub-pixel and the electron transmission layer of the second-type sub-pixel both comprise a first film layer and a second film layer, the electron mobility of the second film layer is smaller than that of the first film layer and is respectively positioned between the first film layer and the light emitting layers of the first-type sub-pixel and the second-type sub-pixel, the thickness of the second film layer of the first-type sub-pixel is larger than that of the second film layer of the second-type sub-pixel, preferably, the first-type sub-pixel comprises a plurality of sub-pixels emitting light with different wavelengths, and the second film layer of the sub-pixel emitting light with the larger wavelength is thicker; and/or the second type of sub-pixels comprise a plurality of sub-pixels emitting light with different wavelengths, and the second film layer of the sub-pixel emitting light with the larger wavelength is thicker.

4. The display panel according to claim 3, wherein in the case that the electron transport layer of the first-type sub-pixel and the electron transport layer of the second-type sub-pixel both comprise a first film layer and a second film layer, the total thickness of the first film layer and the second film layer between different sub-pixels is equal, and the thickness of the second film layer of the first-type sub-pixel is greater than that of the second film layer of the second-type sub-pixel.

5. The display panel according to claim 2, wherein the material of the electron transport layer of the first sub-pixel is a substrate layer doped with a second material, the substrate layer is made of a first material, the material of the electron transport layer of the second sub-pixel is the first material, the second material is doped on a side of the substrate layer of the first sub-pixel facing the light emitting layer, the electron mobility of the second material is smaller than that of the first material, preferably, the first sub-pixel comprises a plurality of sub-pixels emitting light with different wavelengths, and the doping concentration of the second material of the sub-pixel emitting light with the larger wavelength is larger; or

The material of the electron transmission layer of the first-class sub-pixel is a first-class material, the material of the electron transmission layer of the second-class sub-pixel is a base material layer doped with a second-class material, the base material layer is composed of the first-class material, the second-class material is doped on one side, facing the light emitting layer, of the base material layer of the second-class sub-pixel, the electron mobility of the second-class material is larger than that of the first-class material, preferably, the second-class sub-pixel comprises a plurality of sub-pixels emitting light with different wavelengths, and the doping concentration of the second-class material of the sub-pixel emitting light with the larger wavelength is smaller; or

The material of the electron transmission layer of the first-class sub-pixel and the material of the electron transmission layer of the first-class sub-pixel are both substrate layers doped with second-class materials, the substrate layers are composed of the first-class materials, the second-class materials are respectively doped on the sides, facing the light emitting layer, of the substrate layers of the first-class sub-pixel and the substrate layers of the second-class sub-pixel, the electron mobility of the second-class materials is smaller than that of the first-class materials, the doping concentration of the second-class materials in the substrate layers of the first-class sub-pixel is larger than that in the substrate layers of the second-class sub-pixel, preferably, the first-class sub-pixel comprises a plurality of sub-pixels emitting light with different wavelengths, the doping concentration of the second-class materials of the sub-pixels emitting light with larger wavelengths is larger, and/or the second-class sub-pixel comprises a plurality of sub-pixels emitting light with different wavelengths, the doping concentration of the second type of material of the sub-pixel with the larger wavelength of the emergent light is larger.

6. The display panel according to any one of claims 1 to 5, wherein the carrier transport layer comprises a hole transport layer between the anode and the light emitting layer, and wherein the hole transport layer of the first type of sub-pixel has a hole mobility greater than the hole transport layer of the second type of sub-pixel.

7. The display panel according to claim 6, wherein the hole transport layer of the first-type sub-pixel and the hole transport layer of the second-type sub-pixel both comprise a third film layer, the hole transport layer of the first-type sub-pixel further comprises a fourth film layer, the hole mobility of the fourth film layer is greater than the hole mobility of the third film layer and is located between the third film layer and the light emitting layer of the first-type sub-pixel, preferably, the first-type sub-pixel comprises a plurality of sub-pixels emitting light with different wavelengths, and the thickness of the fourth film layer of the sub-pixel emitting light with the larger wavelength is larger; or alternatively

The hole transport layer of the first-type sub-pixel and the hole transport layer of the second-type sub-pixel both comprise a third film layer, the hole transport layer of the second-type sub-pixel further comprises a fourth film layer, the hole mobility of the fourth film layer is smaller than that of the third film layer, and the fourth film layer is positioned between the third film layer and the light emitting layer of the second-type sub-pixel, preferably, the second-type sub-pixel comprises a plurality of sub-pixels emitting light with different wavelengths, and the larger the wavelength of the emitted light, the smaller the thickness of the fourth film layer of the sub-pixel; or

The hole transport layer of the first-class sub-pixel and the hole transport layer of the second-class sub-pixel both comprise a third film layer and a fourth film layer, the hole mobility of the fourth film layer is greater than that of the third film layer and is respectively positioned between the third film layer and the luminescent layers of the first-class sub-pixel and the luminescent layers of the second-class sub-pixel, the thickness of the fourth film layer of the first-class sub-pixel is greater than that of the fourth film layer of the second-class sub-pixel, preferably, the first-class sub-pixel comprises a plurality of sub-pixels emitting light with different wavelengths, the larger the wavelength of the emergent light, the larger the thickness of the fourth film layer of the sub-pixel is, and/or the second-class sub-pixel comprises a plurality of sub-pixels emitting light with different wavelengths, and the larger the wavelength of the emergent light, the larger the thickness of the fourth film layer of the sub-pixel is.

8. The display panel according to claim 7, wherein in the case that the hole transport layer of the first type of sub-pixel and the hole transport layer of the second type of sub-pixel both comprise a third film layer and a fourth film layer, the total thickness of the third film layer and the fourth film layer between different sub-pixels is equal, and the thickness of the fourth film layer of the first type of sub-pixel is greater than that of the fourth film layer of the second type of sub-pixel.

9. The display panel according to claim 5, wherein the material of the hole transport layer of the first sub-pixel is a substrate layer doped with a fourth material, the substrate layer is composed of the third material, the material of the hole transport layer of the second sub-pixel is the third material, the fourth material is doped on the side of the substrate layer of the first sub-pixel facing the light emitting layer, and the hole mobility of the fourth material is greater than that of the third material; preferably, the first-type sub-pixels comprise a plurality of sub-pixels for emitting light with different wavelengths, and the doping concentration of the fourth-type material of the sub-pixels for emitting light with larger wavelength is larger; or alternatively

The hole transport layer of the first sub-pixel is made of a third material, the hole transport layer of the second sub-pixel is made of a base material layer doped with a fourth material, the base material layer is made of the third material, the fourth material is doped on one side, facing the light emitting layer, of the base material layer of the second sub-pixel, and the hole mobility of the fourth material is smaller than that of the third material; preferably, the second sub-pixel comprises a plurality of sub-pixels for emitting light with different wavelengths, and the doping concentration of the fourth material of the sub-pixel for emitting light with the larger wavelength is smaller; or

The material of the hole transport layer of the first-class sub-pixel and the material of the hole transport layer of the first-class sub-pixel are both substrate layers formed by doping a fourth-class material, the substrate layers are formed by the third-class material, the fourth-class material is doped on one sides, facing the light emitting layer, of the substrate layers of the first-class sub-pixel and the second-class sub-pixel respectively, the hole mobility of the fourth-class material is larger than that of the third-class material, and the doping concentration of the fourth-class material in the substrate layer of the first-class sub-pixel is larger than that of the second-class sub-pixel; preferably, the first-type sub-pixels comprise a plurality of sub-pixels for emitting light with different wavelengths, and the doping concentration of the fourth-type material of the sub-pixels for emitting light with larger wavelength is larger; and/or the second sub-pixel comprises a plurality of sub-pixels which emit light with different wavelengths, and the doping concentration of the fourth material of the sub-pixel with the larger wavelength of the emitted light is larger.

10. A display device comprising the display panel according to any one of claims 1 to 9.