Display panel and display device

Abstract

The invention provides a display panel and a display device. The display panel comprises at least two light-emitting structure layers which are arranged in a stacked mode. The P-type charge generation layer and the N-type charge generation layer are arranged between the two adjacent light-emitting structure layers; wherein one side, far away from the P-type charge generation layer, of the N-type charge generation layer is provided with a first transition layer, and one side, close to the P-type charge generation layer, of the N-type charge generation layer is provided with a second transition layer. According to the display panel, the first transition layer and the second transition layer are prepared on the two sides of the N-type charge generation layer respectively, the voltage of the display panel is reduced, and the stability of the display panel is improved.

Description

Technical Field

[0001] The present application relates to the field of display technology, and in particular to a display panel and a display device. Background Art

[0002] Tandem OLED is a high-efficiency OLED device structure formed by stacking multiple traditional OLED devices in series through a connecting layer. Compared with traditional OLED, tandem OLED has extremely high current luminous power efficiency, and its current luminous power efficiency can increase exponentially with the number of devices in series. However, the driving voltage of the light-emitting device of this stacked structure will also increase exponentially with the number of devices in series. When running at high temperature, there is a phenomenon of excessive driving voltage, which leads to stability defects such as high power consumption and low luminous efficiency. Summary of the invention

[0003] The embodiments of the present application provide a display panel and a display device to solve the problems of high voltage and poor stability of tandem OLED in the related art.

[0004] To solve the above problems, the technical solutions provided by this application are as follows:

[0005] In a first aspect, the present application provides a display panel, the display panel comprising at least two stacked light emitting structure layers;

[0006] A P-type charge generation layer and an N-type charge generation layer are arranged between two adjacent light-emitting structure layers;

[0007] A first transition layer is disposed on a side of the N-type charge generation layer away from the P-type charge generation layer, and a second transition layer is disposed on a side of the N-type charge generation layer close to the P-type charge generation layer.

[0008] In one embodiment, the N-type charge generation layer, the first transition layer, and the second transition layer all contain metal materials.

[0009] In one embodiment, the metal doping concentration of the N-type charge generation layer is 1% to 10%.

[0010] In one embodiment, the metal doping concentration of the first transition layer is 0% to 10%.

[0011] In one embodiment, the metal doping concentration of the second transition layer is 0% to 2%.

[0012] In one embodiment, the display panel also includes: a first electrode; a second electrode, arranged opposite to the first electrode; the light-emitting structure layer is arranged between the first electrode and the second electrode, and the light-emitting structure layer includes: a first light-emitting structure layer, arranged between the N-type charge generation layer and the first electrode; and a second light-emitting structure layer, arranged between the P-type charge generation layer and the second electrode.

[0013] In one embodiment, the first light-emitting structure layer includes: a first compensation layer, which is arranged on a side of the first light-emitting structure layer close to the first electrode; a first light-emitting layer, which is arranged on a side of the first light-emitting structure layer close to the second electrode; wherein the first compensation layer includes a first red compensation layer, a first green compensation layer and a first blue compensation layer; and the first light-emitting layer includes a first red light-emitting layer, a first green light-emitting layer and a first blue light-emitting layer.

[0014] In one embodiment, the second light-emitting structure layer includes: a second compensation layer, which is arranged on a side of the second light-emitting structure layer close to the first electrode; a second light-emitting layer, which is arranged on a side of the second light-emitting structure layer close to the second electrode; wherein the second compensation layer includes a second red compensation layer, a second green compensation layer and a second blue compensation layer; and the second light-emitting layer includes a second red light-emitting layer, a second green light-emitting layer and a second blue light-emitting layer.

[0015] In one embodiment, the display panel further includes: a hole injection layer, which is arranged on a side of the first electrode close to the second electrode; a first hole transport layer, which is arranged on a side of the hole injection layer away from the first electrode, and the first light-emitting structure layer is arranged on a side of the first hole transport layer away from the first electrode; a first hole blocking layer, which is arranged on a side of the first light-emitting structure layer away from the first electrode; a first electron transport layer, which is arranged on a side of the first hole blocking layer away from the first electrode, and the first transition layer is arranged on a side of the first electron transport layer away from the first electrode; a second hole transport layer, which is arranged on a side of the P-type charge generating layer away from the first electrode, and the second light-emitting structure layer is arranged on a side of the second hole transport layer away from the first electrode. a second hole blocking layer disposed on a side of the second light emitting structure layer away from the first electrode; a second electron transport layer disposed on a side of the second hole blocking layer away from the first electrode; an electron injection layer disposed on a side of the second electron transport layer away from the first electrode, and the second electrode disposed on a side of the electron injection layer away from the first electrode; a light extraction layer disposed on a side of the second electrode away from the first electrode; and an encapsulation layer disposed on a side of the light extraction layer away from the first electrode; wherein the first hole blocking layer, the first electron transport layer, the second hole blocking layer and the second electron transport layer include compounds that react with metal ions and / or compounds that absorb metal ions.

[0016] In a second aspect, the present application provides a display device, comprising the display panel described in any one of the above embodiments.

[0017] The embodiment of the present application provides a display panel and a display device, wherein the display panel includes a P-type charge generation layer and an N-type charge generation layer, a first transition layer is provided on a side of the N-type charge generation layer away from the P-type charge generation layer, and a second transition layer is provided on a side of the N-type charge generation layer close to the P-type charge generation layer. Through the above solution, the voltage of the display panel is reduced and the stability of the display panel is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0019] Attached Figure 1 This is a schematic diagram of a cross-sectional structure of an optional display panel in an embodiment of the present application;

[0020] Attached Figure 2This is a schematic diagram of a partial cross-sectional structure of an optional display panel in an embodiment of the present application;

[0021] Attached Figure 3 A schematic diagram of an optional evaporation method in an embodiment of the present application;

[0022] Attached Figure 4 A schematic diagram of another optional evaporation method in an embodiment of the present application;

[0023] Attached Figure 5 Schematic diagram of the structure of an optional display device in one embodiment of the present application.

[0024] Description of reference numerals in the figures:

[0025] 1. Display device; 100. Display panel; 101. First electrode; 102. Hole injection layer; 103. First hole transport layer; 104. First light emitting structure layer; 105. First hole blocking layer; 106. First electron transport layer; 107. First transition layer; 108. N-type charge generation layer; 109. Second transition layer; 110. P-type charge generation layer; 111. Second hole transport layer; 112. Second light emitting structure layer; 113. Second hole blocking layer; 114. Second electron transport layer; 115. Electron injection layer; 116. Second electrode; 117. Light extraction layer; 118. Encapsulation layer. DETAILED DESCRIPTION

[0026] The technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present application.

[0027] Reference Figure 1 The present application provides a display panel 100, comprising at least two stacked light-emitting structure layers; a P-type charge generation layer and an N-type charge generation layer, arranged between two adjacent light-emitting structure layers; wherein a first transition layer is arranged on the side of the N-type charge generation layer away from the P-type charge generation layer, and a second transition layer is arranged on the side of the N-type charge generation layer close to the P-type charge generation layer. This solution can reduce the driving voltage of the series display panel and improve the stability of the display panel at high temperatures.

[0028] More specifically, the display panel 100 includes:

[0029] The first electrode 101 may be an anode of an organic light emitting diode of the display panel 100 , and provide holes for the light emitting structure.

[0030] A hole injection layer 102 is provided on a side of the first electrode 101 close to the second electrode 116;

[0031] A first hole transport layer 103, disposed on a side of the hole injection layer 102 away from the first electrode 101;

[0032] The first light-emitting structure layer 104 is arranged on the side of the first hole transport layer 103 away from the first electrode 101. Specifically, in some embodiments of the present application, the first light-emitting structure layer 104 includes a first compensation layer and a first light-emitting layer, wherein the first compensation layer is arranged on the side of the first light-emitting structure layer 104 close to the first electrode 101; the first light-emitting layer is arranged on the side of the first light-emitting structure layer 104 close to the second electrode 116. More specifically, the first compensation layer includes a first red compensation layer, a first green compensation layer and a first blue compensation layer; the first light-emitting layer includes a first red light-emitting layer, a first green light-emitting layer and a first blue light-emitting layer. In this embodiment, the first blue light-emitting layer can be a fluorescent material, a TADF (thermally activated delayed fluorescence) material, a super fluorescent material, etc., and the first red light-emitting layer and the first green light-emitting layer can use a Single Host-Dopant (single host dopant) phosphorescent type material or a Pre-mix Host-Dopant (premixed host dopant) material. It should be noted that in some examples, the first red compensation layer, the first green compensation layer and the first blue compensation layer have the same thickness.

[0033] A first hole blocking layer 105 is disposed on a side of the first light emitting structure layer 104 away from the first electrode 101;

[0034] The first electron transport layer 106 is disposed on the side of the first hole blocking layer 105 away from the first electrode 101. The material of the first electron transport layer 106 is a material having charge transport capability, including at least one of a metal compound, an alkaline metal, and an inorganic compound. Specifically, it may include one or more of silver, lithium, ytterbium, magnesium, gold, barium, calcium, aluminum, indium, lithium fluoride, indium tin oxide, and indium zinc oxide.

[0035] The first transition layer 107 is disposed on a side of the first electron transport layer 106 away from the first electrode 101, and the first transition layer 107 is doped with a metal material. Specifically, in some embodiments of the present application, the metal doping concentration of the first transition layer is 0% to 10%.

[0036] The N-type charge generation layer 108 is disposed on a side of the first transition layer 107 away from the first electrode 101 and is doped with a metal material. Specifically, in some embodiments of the present application, the metal doping concentration of the N-type charge generation layer is 1% to 10%.

[0037] The second transition layer 109 is disposed on a side of the N-type charge generation layer 108 away from the first electrode 101, and the second transition layer 109 is doped with a metal material. Specifically, in some embodiments of the present application, the metal doping concentration of the second transition layer is 0% to 2%.

[0038] It should be noted that in some embodiments of the present application, the first transition layer and the second transition layer may be insulating or may have a certain degree of metal doping. In some examples, the metal doping concentration of the N-type charge generation layer 108 is greater than the metal doping concentration of the first transition layer 107 and the second transition layer 109, thereby reducing the voltage of the display panel and improving the stability of the display panel.

[0039] Among them, the N-type charge generation layer with a relatively high metal doping concentration can generate more charges, but due to the high metal doping concentration of the N-type charge generation layer, its energy band structure will form a high energy barrier, and a high driving voltage is required to allow electrons to pass through the electron transport layer; and the first transition layer between the N-type charge generation layer and the first electron transport layer has a shallower LUMO energy level after being doped with a metal with a relatively low concentration, that is, the first transition layer forms a lower energy barrier, and electrons can more easily pass through the first electron transport layer. Therefore, setting the first transition layer is beneficial to reducing the driving voltage of the display panel. In addition, the first transition layer with a relatively low metal doping concentration also reduces the penetration of the high-concentration doped metal in the N-type charge generation layer into the first electron transport layer, which is beneficial to improving the stability of the display panel.

[0040] The P-type charge generation layer 110 is disposed on the side of the second transition layer 109 away from the first electrode 101. By selecting a suitable material or doping method, the P-type charge generation layer has a lower energy band structure, thereby reducing the energy required for charge injection, that is, reducing the driving voltage of the display panel.

[0041] It should be noted that when the display panel is working, there is an electric field at the interface between the N-type charge generation layer and the P-type charge generation layer. This electric field causes metal ions to migrate in the N-type charge generation layer and eventually enter the P-type charge generation layer. When the metal ions enter the P-type charge generation layer, it will cause charge imbalance and energy level imbalance, thereby affecting the performance and stability of the display panel. By setting a second transition layer with a lower metal doping concentration between the N-type charge generation layer and the P-type charge generation layer, the migration and diffusion of metal ions can be limited, wherein the lower the metal doping concentration of the second transition layer, the lower the migration speed of the metal ions. In some examples, the second transition layer may not have metal doping. In some cases, an appropriate amount of metal doping may help optimize device performance, such as improving carrier injection and transmission characteristics. Whether the doping concentration of the second transition layer is doped with metal can be comprehensively considered according to the specific display panel structure and performance requirements. In summary, setting a second transition layer can reduce the possibility of metal ions migrating to the P-type charge generation layer, thereby improving the stability and life of the display panel.

[0042] A second hole transport layer 111 is disposed on a side of the P-type charge generation layer 110 away from the first electrode 101;

[0043] The second light-emitting structure layer 112 is arranged on the side of the second hole transport layer 111 away from the first electrode 101. The second light-emitting structure layer 112 includes: a second compensation layer and a second light-emitting layer, wherein the second compensation layer is arranged on the side of the second light-emitting structure layer 112 close to the first electrode 101, and the second light-emitting layer is arranged on the side of the second light-emitting structure layer 112 close to the second electrode 116. More specifically, the second compensation layer includes a second red compensation layer, a second green compensation layer and a second blue compensation layer, and the second light-emitting layer includes a second red light-emitting layer, a second green light-emitting layer and a second blue light-emitting layer. It should be noted that in some examples, because the wavelength of red light is greater than the wavelength of green light, and the wavelength of green light is greater than the wavelength of blue light, the thickness of the second red compensation layer is greater than the thickness of the second green compensation layer, and the thickness of the second green compensation layer is greater than the thickness of the second blue compensation layer. In this way, the optical path of the second light-emitting layer can be adjusted so that the optical paths of red light, green light and blue light are the same, forming a microcavity effect and improving the light-emitting effect of the second light-emitting layer.

[0044] A second hole blocking layer 113, disposed on a side of the second light emitting structure layer 112 away from the first electrode 101;

[0045] The second electron transport layer 114 is disposed on the side of the second hole blocking layer 113 away from the first electrode 101; the material of the second electron transport layer 114 is a material having charge transport capability, including at least one of a metal compound, an alkaline metal and an inorganic compound. Specifically, it may include one or more of silver, lithium, ytterbium, magnesium, gold, barium, calcium, aluminum, indium, lithium fluoride, indium tin oxide, and indium zinc oxide.

[0046] An electron injection layer 115 is disposed on a side of the second electron transport layer 114 away from the first electrode 101;

[0047] The second electrode 116 is arranged opposite to the first electrode 101. Specifically, the second electrode 116 is arranged on the side of the electron injection layer 115 away from the first electrode 101; wherein the second electrode 116 is the cathode of the organic light-emitting diode, providing electrons to the light-emitting structure. Therefore, the first electrode 101, the organic emission layer and the second electrode 116 form an organic light-emitting element, and the organic emission layer includes the above-mentioned one or more light-emitting structure layers, the hole injection layer 102, the hole transport layer, the electron transport layer and the electron injection layer 115.

[0048] The light extraction layer 117 is formed on the second electrode 116. In some embodiments, the light extraction layer 117 is similar in structure to the first hole transport layer 103, but has better planarity and a high refractive index. It can reduce the loss of light caused by repeated reflection of light emitted by the light-emitting structure between the first electrode 101 and the second electrode 116, thereby improving the light extraction efficiency of the display panel.

[0049] The encapsulation layer 118 is disposed on a side of the light extraction layer 117 away from the first electrode 101. The encapsulation layer 118 may be formed of an inorganic layer to prevent moisture from being transmitted to the inside of the organic light emitting diode display. The encapsulation layer may include at least one sandwich structure, in which at least one organic layer is inserted between at least two inorganic layers. In addition, the encapsulation layer 118 may include at least one sandwich structure, in which at least one inorganic layer is inserted between at least two organic layers.

[0050] Optionally, in some embodiments of the present application, the materials of the hole blocking layer and the electron transport layer include compounds that react with metal ions, or / and compounds that absorb metal ions. Using this material, some ions in the hole blocking layer and the electron transport layer can react with N-type doped ions or some metal ions to form free radical anions. The formed free radical anions can prevent the diffusion of metal ions and have good electron transport properties. In this way, the N-type doped ions in the charge generation layer can be effectively blocked from migrating to the electron transport layer and the electron injection layer 115, and the transmission efficiency of electrons from the charge generation layer to the electron transport layer and the electron injection layer 115 can also be improved, which can effectively reduce the driving voltage of the device, slow down the aging rate of the device, and improve the high temperature life of the device.

[0051] Based on the above structure, refer to Figure 2 In some embodiments of the present application, the thickness of the N-type charge generation layer 108 is greater than the thickness of the first insulating layer, the first transition layer 107, or the thickness of the second transition layer 109. More specifically, the first transition layer 107 and the second transition layer 109 are prepared by an evaporation process.

[0052] Reference Figure 3 and Figure 4 As shown, in some embodiments of the present application, the evaporation device used in the evaporation process of the first transition layer 107 and the second transition layer 109 includes a first type of evaporation source and a second type of evaporation source, wherein the first type of evaporation source is used to evaporate metal materials, and the second type of evaporation source is used to evaporate NET materials.

[0053] Reference Figure 3 As shown, optionally, in some more specific embodiments, the first type of evaporation source and the second type of evaporation source are respectively provided with one, the evaporation area of ​​the first type of evaporation source covers between the two points A and C in the figure, and the evaporation area of ​​the second type of evaporation source also covers between the two points A and C in the figure, and the evaporation areas of the two overlap, and the substrate to be evaporated moves back and forth horizontally relative to the first type of evaporation source and the second type of evaporation source along the figure (actually the evaporation source is moving). It should be noted that the evaporation area of ​​the first type of evaporation source and the second type of evaporation source only represents the range that can be covered during evaporation rather than the actual coverage range. During actual evaporation, the material can be controlled to be evaporated in any area within the evaporation area, so that in some embodiments, a first transition layer without metal doping and a second transition layer without metal doping can be formed on both sides of the N-type charge generation layer, respectively, or a first transition layer with metal doping and a second transition layer without metal doping can be formed.

[0054] Reference Figure 4As shown, optionally, in some embodiments of the present application, there is one first-type evaporation source, and two second-type evaporation sources are provided, and the two second-type evaporation sources are respectively located on both sides of the first-type evaporation source. The evaporation area of ​​the first-type evaporation source covers between points A and C in the figure, the evaporation area of ​​one of the two second-type evaporation sources covers between points A and B in the figure, and the evaporation area of ​​the other covers between points B and C in the figure. In some embodiments, when forming an N-type charge generation layer, the rates of the two second-type evaporation sources can be kept consistent. The composition of the first transition layer and the second transition layer can be changed by changing the rates of the two second evaporation sources. In some embodiments, a first transition layer and a second transition layer both having a low metal doping concentration can be formed, a first transition layer and a second transition layer both not having metal doping can be formed, or a first transition layer having a low metal doping concentration and a second transition layer not having metal doping can be formed. It should be noted that the first transition layer and the second transition layer of the present application may also have a multi-layer structure, and additional film layers may be arranged between other layers. For example, the first transition layer and the N-type charge generation layer may include in sequence a first layer without a low metal doping concentration and a second layer with a low metal doping concentration, and the N-type charge generation layer and the second transition layer may include in sequence a first layer with a low metal doping concentration and a second layer without a low metal doping concentration.

[0055] The display panel 100 of the present application reduces the voltage of the display panel 100 and improves the stability of the display panel 100 by setting a first transition layer 107 and a second transition layer 109 on both sides of the N-type charge generation layer 108, and the metal doping concentration of the N-type charge generation layer 108 is less than the metal doping concentration of the first transition layer 107 and the second transition layer 109.

[0056] It should be noted that the display panel 100 of the present application also includes other hierarchical structures that complete the display panel 100 , and other film layers can be manufactured using solutions in related technologies, which will not be elaborated in this application.

[0057] Reference Figure 5 As shown, the present application also provides a display device 1, including the display panel 100 described in any of the above embodiments. It should be noted that the display device 1 should also include a system chip, a timing controller, a power management system and a source driver chip, as well as connecting lines and a housing frame for assembling the above chips and the display panel 100, etc., which will not be described in detail here.

[0058] In summary, although the present application has been disclosed as above with preferred embodiments, the above preferred embodiments are not intended to limit the present application. Ordinary technicians in this field can make various changes and modifications without departing from the spirit and scope of the present application. Therefore, the scope of protection of the present application shall be based on the scope defined in the claims.

Claims

1. A display panel, characterized in that: include: At least two stacked light-emitting structure layers; A P-type charge generation layer and an N-type charge generation layer are arranged between two adjacent light-emitting structure layers; A first transition layer is disposed on a side of the N-type charge generation layer away from the P-type charge generation layer, and a second transition layer is disposed on a side of the N-type charge generation layer close to the P-type charge generation layer.

2. The display panel according to claim 1, characterized in that: The N-type charge generation layer, the first transition layer and the second transition layer all contain metal materials.

3. The display panel according to claim 2, characterized in that: The metal doping concentration of the N-type charge generation layer is 1% to 10%.

4. The display panel according to claim 2, characterized in that: The metal doping concentration of the first transition layer is 0% to 10%.

5. The display panel according to claim 2, characterized in that: The metal doping concentration of the second transition layer is 0% to 2%.

6. The display panel according to any one of claims 1 to 5, characterized in that: The display panel further includes: a first electrode; a second electrode, arranged opposite to the first electrode; The light emitting structure layer is disposed between the first electrode and the second electrode, and the light emitting structure layer includes: A first light emitting structure layer, disposed between the N-type charge generation layer and the first electrode; and The second light emitting structure layer is disposed between the P-type charge generating layer and the second electrode.

7. The display panel according to claim 6, characterized in that: The first light emitting structure layer comprises: A first compensation layer, disposed on a side of the first light emitting structure layer close to the first electrode; A first light-emitting layer, arranged on a side of the first light-emitting structure layer close to the second electrode; The first compensation layer includes a first red compensation layer, a first green compensation layer and a first blue compensation layer; the first light-emitting layer includes a first red light-emitting layer, a first green light-emitting layer and a first blue light-emitting layer.

8. The display panel according to claim 6, characterized in that: The second light emitting structure layer comprises: A second compensation layer is arranged on a side of the second light emitting structure layer close to the first electrode; A second light-emitting layer is arranged on a side of the second light-emitting structure layer close to the second electrode; Wherein, the second compensation layer includes a second red compensation layer, a second green compensation layer and a second blue compensation layer; The second light-emitting layer includes a second red light-emitting layer, a second green light-emitting layer, and a second blue light-emitting layer.

9. The display panel according to claim 6, characterized in that: The display panel further includes: A hole injection layer is arranged on a side of the first electrode close to the second electrode; A first hole transport layer is arranged on a side of the hole injection layer away from the first electrode, and the first light emitting structure layer is arranged on a side of the first hole transport layer away from the first electrode; A first hole blocking layer is arranged on a side of the first light emitting structure layer away from the first electrode; A first electron transport layer is arranged on a side of the first hole blocking layer away from the first electrode, and the first transition layer is arranged on a side of the first electron transport layer away from the first electrode; A second hole transport layer is arranged on a side of the P-type charge generation layer away from the first electrode, and the second light-emitting structure layer is arranged on a side of the second hole transport layer away from the first electrode; A second hole blocking layer is arranged on a side of the second light emitting structure layer away from the first electrode; A second electron transport layer is arranged on a side of the second hole blocking layer away from the first electrode; an electron injection layer, arranged on a side of the second electron transport layer away from the first electrode, and the second electrode is arranged on a side of the electron injection layer away from the first electrode; a light extraction layer, disposed on a side of the second electrode away from the first electrode; and An encapsulation layer, disposed on a side of the light extraction layer away from the first electrode; Wherein, the first hole blocking layer, the first electron transport layer, the second hole blocking layer and the second electron transport layer include compounds that react with metal ions and / or compounds that absorb metal ions.

10. A display device, characterized in that: The invention comprises the display panel according to any one of claims 1 to 9.

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