CN109166905B - Display panel and display device thereof - Google Patents
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- CN109166905B CN109166905B CN201811081462.5A CN201811081462A CN109166905B CN 109166905 B CN109166905 B CN 109166905B CN 201811081462 A CN201811081462 A CN 201811081462A CN 109166905 B CN109166905 B CN 109166905B
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- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
- H10K59/00—Integrated devices, or assemblies of multiple devices, comprising at least one organic light-emitting element covered by group H10K50/00
- H10K59/10—OLED displays
- H10K59/12—Active-matrix OLED [AMOLED] displays
- H10K59/122—Pixel-defining structures or layers, e.g. banks
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- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
- H10K59/00—Integrated devices, or assemblies of multiple devices, comprising at least one organic light-emitting element covered by group H10K50/00
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- H10K59/88—Dummy elements, i.e. elements having non-functional features
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Abstract
The invention provides a display panel and a display device thereof, relates to the technical field of display, and is used for improving voltage drop, improving the uniformity of driving signals received by light-emitting elements at all positions and improving the display effect. The display panel is a top light emitting structure, and the display panel includes: the pixel definition layer comprises an opening area and a non-opening area, and the opening area and the non-opening area are not overlapped; a plurality of light emitting elements corresponding to the opening regions of the pixel defining layer, the light emitting elements including an anode, a light emitting layer and a first cathode, wherein the light emitting layer is positioned within the opening regions of the pixel defining layer; the cap layer is positioned on one side, away from the substrate, of the first cathode, and covers the plurality of light-emitting elements; the cap layer includes a first dopant including an alkaline earth metal element or a transition metal element. The display panel is suitable for display devices.
Description
[ technical field ] A method for producing a semiconductor device
The invention relates to the technical field of display, in particular to a display panel and a display device thereof.
[ background of the invention ]
Compared with many display panels, an OLED (Organic Light-Emitting Diode) display panel has many advantages such as active Light emission, high contrast, no viewing angle limitation, and the like. The OLED display panel is thinner and thinner in volume and lower in power consumption than other display devices, so that the endurance of the display device is improved, and therefore the OLED display panel is widely applied to the technical field of display and will become a mainstream product of the display device in the future.
With the advent of the full-screen and large-size display era, when driving signals are provided to the cathodes of the light emitting elements due to different positions of the light emitting elements, the driving signals received by the light emitting elements are different due to voltage drop, so that the brightness of the light emitting elements is uneven, and the display effect is affected.
Therefore, how to improve the voltage drop so that the driving signals received by the light emitting elements at various positions are uniform and consistent, and improving the display effect is a major technical problem currently faced in the industry.
[ summary of the invention ]
In view of this, embodiments of the present invention provide a display panel and a display device thereof, which are used to improve a voltage drop, improve uniformity of driving signals received by light emitting elements at various positions, and improve a display effect.
In one aspect, the present invention provides a display panel, which is a top emission structure, and includes:
a substrate base plate, a first substrate base plate,
a pixel defining layer on one side of the substrate base plate, the pixel defining layer including an open area and a non-open area, the open area and the non-open area not overlapping;
a plurality of light emitting elements corresponding to the opening regions of the pixel defining layer, the light emitting elements including an anode, a light emitting layer and a first cathode, wherein the light emitting layer is positioned within the opening regions of the pixel defining layer;
the cap layer is positioned on one side, away from the substrate, of the first cathode, and covers the plurality of light-emitting elements;
the cap layer includes a first dopant including an alkaline earth metal element or a transition metal element.
Optionally, the alkaline earth metal element comprises Mg and/or Ca.
Optionally, the transition metal element includes any one or more of Ag, Sm, Gd, Tm, Yb and Lu.
Optionally, the doping volume ratio of the first dopant ranges from 3% to 50%.
Optionally, the display panel further includes:
the second cathode is arranged on one side, away from the substrate base plate, of the cover cap layer, and the orthographic projection of the second cathode on the plane of the non-opening area is located in the non-opening area.
Optionally, in a direction perpendicular to the display panel, a thickness of the first cathode is smaller than a thickness of the second cathode.
Optionally, the thickness of the second cathode is C2, wherein C2 is not less than 10nm and not more than 50 nm.
Optionally, the resistivity of the second cathode is less than the resistivity of the first cathode.
Optionally, the second cathode is a metal or a metal alloy.
Optionally, the thickness of the cap layer is H, wherein H is greater than or equal to 30nm and less than or equal to 90 nm.
Another aspect of the present invention provides a display device comprising the display panel of the previous aspect.
Any one of the above technical solutions has the following beneficial effects:
in this embodiment, the cap layer located at the first cathode and away from the substrate base plate 1 serves as an auxiliary cathode, and the conductivity of the cap layer 4 is increased by doping the first dopant 41. As can be seen from the formula σ of the conductivity being 1/ρ, the conductivity σ is inversely proportional to the resistivity ρ, and the resistivity ρ decreases as the conductivity σ increases. As can be seen from the resistance formula, R ═ ρ L/S, where R denotes resistance, ρ denotes resistivity, L denotes length, and S denotes cross-sectional area. The lower the resistivity ρ, the lower the resistance R of the corresponding cap layer 4. That is to say, equivalent thickness of the cathode (the first cathode and the cap layer) in the display panel is increased, so that when the driving signal is provided to the cathode of each light-emitting element, since resistance of the equivalent cathode (the first cathode and the cap layer) is reduced, the condition of voltage drop is improved or even avoided, and therefore, the driving signals received by the light-emitting elements at each position on the display panel are uniform, and the display effect of the display panel is improved.
[ description of the drawings ]
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without inventive labor.
Fig. 1 is a schematic structural diagram of a display panel according to an embodiment of the present invention;
FIG. 2 is a cross-sectional view at the AA' position of FIG. 1 according to an embodiment of the present invention;
FIG. 3 is a graph comparing doped and undoped I-V of a cap layer in an embodiment of the present invention;
FIG. 4 is another cross-sectional view at the AA' position of FIG. 1 in accordance with an embodiment of the present invention;
FIG. 5 is another cross-sectional view at the AA' position of FIG. 1 in accordance with an embodiment of the present invention;
FIG. 6 is a graph illustrating an embodiment of the present invention;
fig. 7 is a schematic structural diagram of a display device according to an embodiment of the present invention.
[ detailed description ] embodiments
For better understanding of the technical solutions of the present invention, the following detailed descriptions of the embodiments of the present invention are provided with reference to the accompanying drawings.
It should be understood that the described embodiments are only some embodiments of the invention, and not all 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.
The terminology used in the embodiments of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used in the examples of the present invention and the appended claims, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.
It should be understood that the term "and/or" as used herein is merely one type of association that describes an associated object, meaning that three relationships may exist, e.g., a and/or B may mean: a exists alone, A and B exist simultaneously, and B exists alone. In addition, the character "/" herein generally indicates that the former and latter related objects are in an "or" relationship.
It should be understood that although the terms first, second, etc. may be used to describe the cathodes in embodiments of the present invention, the cathodes should not be limited by these terms. These terms are only used to distinguish the cathodes from each other. For example, a first cathode may also be referred to as a second cathode, and similarly, a second cathode may also be referred to as a first cathode, without departing from the scope of embodiments of the present invention.
It should be noted that the terms "upper", "lower", "left", "right", and the like used in the description of the embodiments of the present invention are used in the angle shown in the drawings, and should not be construed as limiting the embodiments of the present invention. In addition, in this context, it is also to be understood that when an element is referred to as being "on" or "under" another element, it can be directly formed on "or" under "the other element or be indirectly formed on" or "under" the other element through an intermediate element.
Before the technical solution of the present embodiment is explained in detail, the technical context of the present invention is briefly introduced:
the display panel referred to in the present embodiment may be understood as an organic light emitting display panel including an anode, a cathode, and an organic layer disposed therebetween. The organic layer may emit light at a luminance level corresponding to a current flowing between the anode and the cathode. The organic light emitting display panel displays a desired image by controlling a current flowing between an anode and a cathode.
In order to improve the light extraction efficiency, a microcavity structure of a top emission mode is adopted to obtain a higher light extraction amount. In the top emission structure, the anode can be a total reflection anode, and the cathode can be a semitransparent cathode, wherein the total reflection anode and the semitransparent cathode form a microcavity (resonant cavity), and when the microcavity length and the wavelength of light waves satisfy a certain relationship, light with a specific wavelength (the wavelength of a certain monochromatic light) can be enhanced, the spectrum is narrowed, and a microcavity effect occurs. The microcavity effect has functions of selecting, narrowing, and enhancing a light source, and is often used to improve chromaticity of an organic light emitting device, enhance emission intensity of a specific wavelength, change a light emitting color of the organic light emitting device, and the like, because emitted light needs to be emitted through a cathode, the thickness of the cathode is thin in order to increase transmittance of the emitted light.
However, the cathode material is made of a transparent conductive material, and the thickness of the cathode material is thin, so that the sheet resistance of the cathode material is large, and particularly when the cathode material is applied to a light emitting element with a large size, a large voltage drop is generated, so that driving signals received by the light emitting elements at different positions are different, the display brightness is uneven, and the display effect is affected.
In order to solve the problem that the voltage drop of the light-emitting device causes the uneven brightness of the display panel, the inventor proposes the following technical scheme:
in the present embodiment, a display panel is provided, as shown in fig. 1 and fig. 2, fig. 1 is a schematic structural diagram of the display panel provided in the embodiment of the present invention, fig. 2 is a cross-sectional view of an AA' position in fig. 1 provided in the embodiment of the present invention, and the display panel 100 in the present embodiment can be understood as an organic light emitting display panel, in which the display panel 100 is a top emission structure, and the display panel 100 includes a substrate 1. The substrate 1 in this embodiment may be a flexible substrate, and the corresponding display panel 100 may be a flexible organic light emitting display panel, which has special effects of low power consumption and being bendable, and is suitable for various display devices, especially for wearable display devices. Optionally, the flexible substrate is made of polyester imide or polyethylene terephthalate resin. In addition, the substrate 1 may also be a rigid substrate, and the corresponding display panel 100 is a rigid organic light emitting display panel. In fact, the material of the organic light emitting display panel is not particularly limited in this embodiment.
As shown in fig. 2, the display panel 100 further includes a pixel defining layer 3 on one side of the substrate 1, the pixel defining layer 3 including an open area 31 and a non-open area 32, the open area 31 not overlapping the non-open area 32. The display panel 100 further includes a plurality of light emitting elements 2, the light emitting elements 2 corresponding to the opening areas 31 of the pixel defining layer 3, the light emitting elements 2 including an anode RE, a light emitting layer 25, and a first cathode 23, wherein the light emitting layer 25 is positioned within the opening areas 31 of the pixel defining layer 3. The pixel defining layer 3 serves to define the positions of the respective light emitting elements 2. The pixel defining layer 3 can adjust the light emitting area of each light emitting element 2, and illustratively, the larger the area of the non-opening region 32, the smaller the light emitting opening of the light emitting element 2; conversely, the smaller the area of the non-opening region 32, the larger the light exit of the light emitting element 2, and the more light is emitted. In fact, the light emitting area of each light emitting element 2 is not particularly limited in this embodiment, and the specific value may be determined according to different products.
With continued reference to fig. 2, the display panel 100 further includes a cap layer 4 located on a side of the first cathode 23 facing away from the substrate 1, the cap layer 4 covering the plurality of light emitting elements 2. It is understood that the orthographic projection of the cap layer 4 on the base substrate 1 covers the orthographic projection of the light emitting element 2 on the base substrate 1 in the direction perpendicular to the display panel 100. The cap layer 4 has a large refractive index and diffuses light emitted from the light-emitting layer 25 to the periphery. Wherein the cap layer 4 includes a first dopant 41, and the first dopant 41 includes an alkaline earth metal element or a transition metal element. It should be noted that the first dopant 41 may be a compound or a simple metal or an alloy in the cap layer 4, and is not particularly limited in this embodiment. And fig. 2 illustrates a square shape as the shape of the first dopant, in fact, fig. 2 is only for facilitating the intuitive understanding of the present solution by those skilled in the art, and it is not intended to be the shape of the first dopant 41 in the cap layer, and the present embodiment does not make any particular limitation on the shape of the first dopant 41.
The effect of doping the cap layer with the first dopant is briefly described below by taking fig. 3 as an example:
as shown in fig. 3, which is a graph comparing doped and undoped I-V of the cap layer in the embodiment of the present invention, an undoped curve represents an I-V curve of the cap layer without doping, and a doped curve represents an I-V curve of the cap layer after doping, wherein the doped curve represents doping of the lanthanide metal Yb in the cap layer, that is, the dopant Yb. The I-V curve represents a current-voltage curve, the current is an abscissa, and the voltage is an ordinate, and it is intuitively seen from FIG. 3 that the turn-on voltage in the undoped curve is about 8V, and the turn-on voltage after doping is about 2.2V, so that the voltage range of the cap layer containing the dopant can be obviously reduced, and the voltage drop of the light emitting element can be improved. In addition, for the same current density, the voltage of the doped cap layer 4 is lower, which can indicate that the corresponding conductivity is improved, so that the mobility rate of carriers is increased, and the resistance value of the doped cap layer 4 is reduced.
Therefore, the cap layer 4 located at the position of the first cathode 23 away from the substrate 1 serves as an auxiliary cathode, so that the thickness of the equivalent cathode (the first cathode 23 and the cap layer 4) of the display panel 100 can be increased, the resistance value of the equivalent cathode (the first cathode 23 and the cap layer 4) can be reduced, and when the driving signal is provided to the light emitting elements 2, the voltage drop can be improved or even avoided, so that the driving signals received by the light emitting elements 2 are consistent, the light emitting brightness is uniform and consistent, and the display effect of the display panel 100 is effectively improved.
In the prior art, the cap layer is a layer of organic material and is not conductive enough, so that the cathode has a high resistance and a large turn-on voltage, and a voltage drop occurs during signal transmission, so that the luminance of the light-emitting elements at various positions in the display panel is not uniform.
However, in the present embodiment, since the first dopant 41 is doped in the cap layer 4, the conductivity thereof is increased. As can be seen from the formula σ of the conductivity being 1/ρ, the conductivity σ is inversely proportional to the resistivity ρ, and the resistivity ρ decreases as the conductivity σ increases. As can be seen from the resistance formula, R ═ ρ L/S, where R denotes resistance, ρ denotes resistivity, L denotes length, and S denotes cross-sectional area. The lower the resistivity ρ, the lower the resistance R of the corresponding cap layer 4. That is, the equivalent thickness of the cathode (the first cathode 23 and the cap layer 4) in the display panel 100 is increased, so that when the driving signal is provided to the cathode of each light emitting element 2, the resistance of the equivalent cathode (the first cathode 23 and the cap layer 4) is reduced, and the condition of voltage drop is improved or even avoided, so that the driving signals received by the light emitting elements 2 at each position on the display panel 100 are uniform, and the display effect of the display panel 100 is improved.
The display panel in this embodiment can be understood as an organic light emitting display panel, and the light emitting principle of the organic light emitting display panel is briefly described as follows:
with continued reference to fig. 2, under the action of the applied electric field, electrons are injected from the first cathode 23 into the light-emitting layer 25, and holes are injected from the anode RE into the light-emitting layer 25. The injected electrons and the injected holes generate excitons after recombination in the light-emitting layer 25. The excitons migrate under the action of the electric field, transferring energy to the organic light emitting molecules in the light emitting layer 25, electrons of the organic light emitting molecules transition from a ground state to an excited state and release energy, and finally the energy is released in the form of photons and emits light.
In an implementation manner, as shown in fig. 4, according to another cross-sectional view at AA' position in fig. 1 provided by the embodiment of the present invention, the display panel 100 further includes a second cathode 5, the second cathode 5 is disposed on a side of the cap layer 4 facing away from the substrate base plate 1, and an orthographic projection of the second cathode 5 on a plane where the non-open area 32 is located in the non-open area 32.
As can be seen from the resistance formula, R ═ ρ L/S, where R denotes resistance, ρ denotes resistivity, L denotes length, and S denotes cross-sectional area. In this embodiment, the second cathode 5 is disposed on a side of the cap layer 4 away from the substrate 1, so that the thicknesses of the equivalent cathodes (the first cathode 23, the cap layer 4, and the second cathode 5) of the display panel 100 are increased, that is, the cross-sectional area S is increased, and the resistances R of the equivalent cathodes (the first cathode 23, the cap layer 4, and the second cathode 5) are reduced, and further when the driving signals are provided to the cathodes of the light emitting elements 2, the resistances of the equivalent cathodes (the first cathode 23, the cap layer 4, and the second cathode 5) are reduced, so that the voltage drop is improved or even avoided, and therefore, the driving signals received by the light emitting elements 2 at various positions on the display panel 100 are uniform and consistent, and the display effect of the display panel 100 is improved.
In combination with the above embodiments, since the cap layer 4 and the second cathode 5 on the side of the first cathode away from the substrate 1 are both used as auxiliary cathodes, the thickness of the equivalent cathode of the display panel 100 is increased, the resistance of the equivalent cathode is further reduced, and the uniformity of the driving signal received by the light emitting element 2 is improved.
In one embodiment, the second cathode 5 in this embodiment may be a metal or a metal alloy, and the material of the second cathode 5 in this embodiment may be, for example, a magnesium-silver alloy or magnesium metal. The work functions of the magnesium-silver alloy and the metal magnesium are low, so that transition of electrons generated by the second cathode 5 to the light-emitting layer 25 is facilitated, the recombination rate of the electrons and holes is further improved, and the light-emitting efficiency is improved. And the conductivity of the two is good, the price is low, and the cost is saved.
The material of the first cathode 23 may be the same as the material of the second cathode 5, or may be different from the material of the first cathode, and the material is not particularly limited in this embodiment and may be determined according to specific products.
Further, as shown in fig. 4, in the direction perpendicular to the display panel 100, the thickness of the first cathode 23 is C1, and the thickness of the second cathode 5 is C2, wherein the thickness C1 of the first cathode 23 is less than the thickness C2 of the second cathode 5. On one hand, the embodiment ensures that the first cathode and the anode RE form a microcavity structure, which is beneficial to emitting light generated by the light-emitting layer 25; on the other hand, the first cathode 23, which is thin, has a high transmittance and increases the amount of light emitted.
In an alternative embodiment, the thickness C2 of the second cathode 5 ranges between 10nm C2 nm 50 nm. The larger the thickness of the second cathode 5, the lower the resistance to the display panel 100 composed of it and the first cathode 23, which is more advantageous for the improvement of voltage drop. However, the increase in thickness increases the overall thickness of the display panel 100, which is contrary to the popular trend, so that the range of the second cathode 5 in this embodiment is between 10nm and 50nm, which reduces the resistance of the cathode formed by the first cathode 23 and the second cathode 5, improves the voltage drop, makes the driving signals received by the light emitting elements 2 at various positions on the display panel 100 uniform, and improves the display effect; on the other hand, further increase of the thickness is avoided from influencing the use of customers.
It should be added that the thickness of the second cathode can be adjusted according to the collected voltage drop of each light emitting element 2 of the display panel 100. Illustratively, the light emitting element 2 has a larger voltage drop, which may result in an increased thickness of the auxiliary cathode at the light emitting element 2, which may be the cap layer 4 and/or the second cathode 5.
The voltage drop can be understood as a difference between the voltage value of the first cathode 23 received by the light emitting element 2 and the voltage value output by the driving terminal.
In another alternative embodiment, the resistivity at the second cathode 5 is less than the resistivity at the first cathode 23. As can be seen from the resistance formula, R ═ ρ L/S, where R denotes resistance, ρ denotes resistivity, L denotes length, and S denotes cross-sectional area. As the resistivity ρ is smaller and the corresponding resistance is smaller, it can be understood that the resistance of the second cathode 5 is smaller than the resistance of the first cathode 23, so that the overall resistance of the cathode composed of the first cathode 23 and the second cathode 5 is reduced, and when the driving signal is provided to the cathode of each light emitting element 2, since the resistance of the cathode (the first cathode 23 and the second cathode 5) of the display panel 100 is reduced, the situation of voltage drop is improved or even avoided, so that the driving signals received by the light emitting elements 2 at each position on the display panel 100 are uniform, and the display effect of the display panel 100 is improved.
The doping in the cap layer 4 is described in detail below:
in another alternative implementation, referring to FIG. 5, which is another cross-sectional view taken at AA' of FIG. 1 provided by an embodiment of the present invention, the capping layer has a thickness H, where H is 30nm ≦ H ≦ 90 nm. In this embodiment, since the cap layer 4 covers the light emitting element 2, the thickness of the cap layer 4 is not too high, which may affect the transmittance of the light emitted from the light emitting layer 25, and the thickness H of the cap layer 4 is set between 30nm and 90nm in this embodiment, which helps to reduce the resistance of the cathodes (the first cathode 23 and the second cathode 5) of the display panel 100 and improve the light emission amount.
In one embodiment, the alkaline earth metal element comprises Mg and/or Ca. Since the alkaline earth metal elements Mg and Ca are common metal elements, the yield is high, the price is low, the voltage drop of the display panel is improved, the driving signals received by the light emitting elements 2 at various positions are uniform, and the production cost is saved.
In another embodiment, the transition metal element comprises any one or more of Ag, Sm, Gd, Tm, Yb and Lu. The work functions of the transition metal element Ag and the lanthanide metals Sm, Gd, Tm, Yb, and Lu are small, and the small work functions increase the mobility of electrons, that is, increase the conductivity of the cap layer 4. As can be seen from the formula σ of the conductivity being 1/ρ, the conductivity σ is inversely proportional to the resistivity ρ, and the larger the conductivity σ, the smaller the resistivity ρ, and the smaller the corresponding resistance R, so that when the driving signal is provided to the light emitting elements 2, the voltage drop is improved or even avoided, and thus, the driving signals received by the light emitting elements 2 are consistent, and the light emitting brightness is uniform, thereby effectively improving the display effect of the display panel 100.
In another embodiment, the doping volume ratio of the first dopant 41 ranges from 3% to 50%.
In this embodiment, the larger the doping volume ratio of the dopant 41 is, the lower the corresponding transmittance is; however, the larger the doping volume, the faster the sheet resistance decreases, which is beneficial to reducing the resistance of the cap layer 4, so in this embodiment, after considering the transmittance and the sheet resistance, the doping volume ratio of the first dopant 41 is between 3% and 50%, inclusive.
It should be added that the sheet resistance is understood to be the film resistance, which is only related to the film thickness. That is, square measurements of arbitrary size are the same, e.g., the sheet resistance is the same for both sides regardless of whether the side is 1 meter or 0.1 meter.
The above embodiment is supported by specific data, and the cap layer 4 and the second cathode 5 are used as auxiliary cathodes, wherein the dopant in the cap layer 4 is metal Yb, and the second cathode is Ag. As shown in fig. 6, which is a graph provided by the embodiment of the present invention, it can be seen from fig. 6 that as the thickness of the auxiliary cathode increases, the sheet resistance R/□ decreases, that is, the resistance of the equivalent cathode (the auxiliary cathode and the first cathode) included in the display panel 100 decreases, and the display effect of the display panel 100 is improved by using the driving signals received by the light emitting elements 2 at the respective positions to be uniform. However, as the thickness of the auxiliary cathode increases, the transmittance Tr thereof decreases, which is not favorable for emitting light, so in this embodiment, the doping range of the first dopant in the cap layer is limited by combining the above two factors.
As shown in table 1 below, the cap layer and the second cathode constitute an auxiliary cathode, and the second cathode is Ag and the first dopant is Yb for example, to describe the relationship between doping and sheet resistance and the relationship between doping and transmittance. As can be seen from table 1, in example 1, the sheet resistance of the second cathode Ag is so large that no specific value can be found out, and the transmittance is also lower to 26.6% when the cap layer is absent, it can be understood that, when the first cathode and the second cathode are taken as the equivalent cathode, the sheet resistance of the equivalent cathode is not significantly reduced, which is not beneficial to improving the voltage drop. When the cap layer without the dopant and the second cathode are used as the auxiliary cathode, see example 2, the sheet resistance R/□ is 25.6, and the transmittance is increased to 49.575%. Further, after the capping layer is doped with 5%, 9% and 15% by volume respectively (see embodiments 3 to 5), the sheet resistance R/□ is gradually reduced, thereby ensuring that the resistance of the equivalent cathodes (the auxiliary cathode and the first cathode) of the display panel is reduced, and facilitating improvement of the voltage drop. However, as the doping percentage increases, the transmittance decreases, so the doping ratio may need to consider the factors of both sheet resistance and transmittance, and the specific doping percentage may be determined according to the specific product.
TABLE 1
In this embodiment, as shown in fig. 7, which is a schematic structural diagram of a display device according to an embodiment of the present invention, the display device 500 includes the display panel 100 according to the above embodiment. The display device 500 includes the display panel 100 described above. It should be noted that fig. 7 illustrates a mobile phone as an example of the display device, but the display device 500 is not limited to a mobile phone, and specifically, the display device may include, but is not limited to, any electronic device having a display function, such as a Personal Computer (PC), a Personal Digital Assistant (PDA), a wireless handheld device, a Tablet Computer (Tablet Computer), an MP4 player, or a television.
In this embodiment, the cap layer located at the first cathode and away from the substrate base plate 1 serves as an auxiliary cathode, and the conductivity of the cap layer 4 is increased by doping the first dopant 41. As can be seen from the formula σ of the conductivity being 1/ρ, the conductivity σ is inversely proportional to the resistivity ρ, and the resistivity ρ decreases as the conductivity σ increases. As can be seen from the resistance formula, R ═ ρ L/S, where R denotes resistance, ρ denotes resistivity, L denotes length, and S denotes cross-sectional area. The lower the resistivity ρ, the lower the resistance R of the corresponding cap layer 4. That is to say, equivalent thickness of the cathode (the first cathode and the cap layer) in the display panel is increased, so that when the driving signal is provided to the cathode of each light-emitting element, since resistance of the equivalent cathode (the first cathode and the cap layer) is reduced, the condition of voltage drop is improved or even avoided, and therefore, the driving signals received by the light-emitting elements at each position on the display panel are uniform, and the display effect of the display panel is improved.
Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.
Claims (6)
1. A display panel, the display panel is a top-emitting structure, comprising:
a substrate base plate, a first substrate base plate,
a pixel defining layer on one side of the substrate base plate, the pixel defining layer including an open area and a non-open area, the open area and the non-open area not overlapping;
a plurality of light emitting elements corresponding to the opening regions of the pixel defining layer, the light emitting elements including an anode, a light emitting layer and a first cathode, wherein the light emitting layer is positioned within the opening regions of the pixel defining layer;
the cap layer is positioned on one side, away from the substrate, of the first cathode, and covers the plurality of light-emitting elements;
the cap layer comprises a first dopant, the first dopant comprises an alkaline earth metal element or a transition metal element, and the doping volume ratio of the first dopant ranges from 3% to 50%;
the display panel further comprises a second cathode, the second cathode is arranged on one side, away from the substrate base plate, of the cap layer, the orthographic projection of the second cathode on the plane of the non-opening area is located in the non-opening area, in the direction perpendicular to the display panel, the thickness of the first cathode is smaller than that of the second cathode, the thickness of the second cathode is C2, and C2 is not less than 10nm and not more than 50 nm;
the second cathode has a resistivity less than the resistivity of the first cathode.
2. The display panel according to claim 1,
the alkaline earth metal element includes Mg and/or Ca.
3. The display panel according to claim 1,
the transition metal element comprises any one or more of Ag, Sm, Gd, Tm, Yb and Lu.
4. The display panel of claim 1, wherein the second cathode is a metal or metal alloy.
5. The display panel of claim 1, wherein the capping layer has a thickness H, and wherein H is greater than or equal to 30nm and less than or equal to 90 nm.
6. A display device characterized by comprising the display panel according to any one of claims 1 to 4.
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| CN111524460B (en) * | 2020-04-26 | 2021-10-01 | 武汉华星光电半导体显示技术有限公司 | Display panel, mask plate and manufacturing method of display panel |
| TWI750698B (en) * | 2020-06-17 | 2021-12-21 | 友達光電股份有限公司 | Display panel |
| CN115207253A (en) * | 2020-12-23 | 2022-10-18 | 湖北长江新型显示产业创新中心有限公司 | Display panel and display device |
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| CN107134536B (en) * | 2017-05-10 | 2019-03-01 | 京东方科技集团股份有限公司 | Organic Light Emitting Diode and its manufacturing method, display panel, display device |
| CN108470840B (en) * | 2018-05-31 | 2020-03-17 | 上海天马有机发光显示技术有限公司 | Organic light emitting display panel and display device |
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| CN101221975A (en) * | 2007-01-12 | 2008-07-16 | 索尼株式会社 | display device |
| CN107871824A (en) * | 2016-09-23 | 2018-04-03 | 三星显示有限公司 | Organic light emitting diode display device including cover layer |
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