Display panel and display device

Abstract

The invention provides a display panel and a display device. The display panel comprises a light-emitting layer, a first electrode and a first common layer. The first electrode provides a first type of carriers; the first common layer is located between the light-emitting layer and the film layer where the first electrode is located; the light emitting layer receives the first type of carriers through the first common layer. The first common layer comprises a first material and a second material, the lowest unoccupied molecular orbital energy level of the first material to the first type of carriers is P1, the lowest unoccupied molecular orbital energy level of the second material to the first type of carriers is P2, and P1 is lower than P2. The first common layer comprises a first part and a second part, and the first part is located on the side, away from the light-emitting layer, of the second part; wherein the concentration ratio of the first material in the first part is greater than the concentration ratio of the first material in the second part. According to the design mode of the invention, the mobility of the first type of carriers passing through the first common layer to be transferred to the light-emitting layer can be improved, the ghost phenomenon can be improved, and the image display quality can be improved.

Description

Technical Field

[0001] This application relates to the field of display technology, specifically to a display panel and display device. Background Technology

[0002] With the continuous development of display technology, the quality requirements for image display are gradually increasing, and the smoothness of screen transitions is becoming an important standard for measuring the performance of display devices. However, in actual display processes, when a display device is in a static display state for a long time, the distribution of charge carriers and trapped states in some film layers within the panel tends to be relatively "fixed". At this time, if the display screen switches from the current static screen, the aforementioned "fixed" distribution of charge carriers and trapped states cannot respond in time, resulting in uneven brightness phenomena such as ghosting during screen transitions, reducing the smoothness of screen transitions and affecting image display quality. Summary of the Invention

[0003] In view of this, this application provides a display panel and display device to help solve the above-mentioned uneven brightness phenomenon caused by the untimely response of carrier distribution and trapped state distribution.

[0004] In a first aspect, this application provides a display panel, including a light-emitting layer; The first electrode provides the first type of charge carriers; The first common layer is located between the light-emitting layer and the film layer containing the first electrode; the light-emitting layer receives first-type charge carriers through the first common layer. The first common layer includes a first material and a second material, wherein the lowest unoccupied molecular orbital energy level of the first material for the first-type charge carriers is P1, and the lowest unoccupied molecular orbital energy level of the second material for the first-type charge carriers is P2, where P1 is lower than P2. The first common layer includes a first part and a second part, with the first part located on the side of the second part away from the light-emitting layer; The concentration of the first material in the first part is greater than that in the second part.

[0005] Based on the same inventive concept, this application also provides a display device, including the above-mentioned display panel.

[0006] Compared with the prior art, the display panel and display device provided by the present invention achieve at least the following beneficial effects: The design of this application helps to increase the mobility of the first type of charge carriers transferring through the first common layer to the light-emitting layer, reduces the risk of the first type of charge carriers accumulating at the interface, and thus helps to improve the aforementioned image retention phenomenon and improve the image display quality. Attached Figure Description

[0007] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0008] Figure 1 This is a structural diagram of a portion of the display panel in related technologies; Figure 2 This is a schematic diagram illustrating the state of an existing display panel before and after screen switching in related technologies; Figure 3 A partial structure of a display panel provided in this application; Figure 4 This is a schematic diagram showing the energy level differences corresponding to each film layer material in the display panel. Figure 5 A schematic diagram of a partial structure of a display panel provided in this application; Figure 6 for Figure 5 The diagram shows the energy level differences corresponding to each film layer material in the display panel. Figure 7 A schematic diagram of a partial structure of a display panel provided in this application; Figure 8 for Figure 7 The diagram shows the energy level differences corresponding to each film layer material in the display panel. Figure 9 This is a schematic diagram showing the energy level differences corresponding to each film layer material in the display panel. Figure 10 A schematic diagram of a partial structure of a display panel provided in this application; Figure 11 for Figure 10 The diagram shows the energy level differences corresponding to each film layer material in the display panel. Figure 12 This is a schematic diagram of a display device provided in this application. Detailed Implementation

[0009] To better understand the technical solution of this application, the embodiments of this application will be described in detail below with reference to the accompanying drawings.

[0010] It should be understood that the described embodiments are merely some, not all, of the embodiments in this application. All other embodiments obtained by those skilled in the art based on the embodiments in this application without inventive effort are within the scope of protection of this application.

[0011] The terminology used in the embodiments of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of this application. The singular forms “a,” “the,” and “the” used in the embodiments of this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0012] It should be understood that the term "and / or" used in this article is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, the character " / " in this article generally indicates that the preceding and following related objects have an "or" relationship.

[0013] Figure 1 This is a structural diagram of a portion of the display panel in related technologies.

[0014] In related technologies, such as Figure 1 As shown, the existing display panel 10' includes a first electrode 01', a second electrode 02', and a light-emitting layer 03'. The first electrode 01' can be a cathode, the second electrode 02' can be an anode, and the light-emitting layer 03' is located between the first electrode 01' and the second electrode 02'. The charge carriers provided by the first electrode 01' and the second electrode 02' can combine in the light-emitting layer 03' to achieve light emission. The space between the light-emitting layer 03' and the first electrode 01' may include multiple common layers 04' (including an electron injection layer 041' and an electron transport layer 042'), and the space between the light-emitting layer 03' and the second electrode 02' may also include multiple common layers 04' (including a hole injection layer 043' and a hole transport layer 044').

[0015] Figure 2 This is a diagram illustrating the state of an existing display panel before and after screen switching in related technologies. For ease of understanding, Figure 2 The example illustrates the situation of an existing display panel before and after switching from a static image to another image.

[0016] During the period when the existing display panel 10' is displaying a static image for an extended period, since the displayed image can be considered unchanged during this time, the carrier distribution and trap state distribution in the aforementioned common layer 04' are also in a fixed state for a long time (hereinafter described as a quasi-fixed state). The longer the static image display duration, the more difficult it is to change the aforementioned fixed state quickly, that is, the longer the response time required for changes in the carrier distribution and trap state distribution. Therefore, during the process of the existing display panel 10' switching from displaying a static image for a long time to displaying another image, such as Figure 2 As shown, the aforementioned fixed state makes it difficult for the carrier distribution and trap state distribution to change in a timely manner, thus causing image retention (such as...) in the displayed image. Figure 2As shown in the figure, image residue (a) appears after the image changes from a circular dark spot that has been displayed for a long time to a square pattern, which reduces the smoothness of the screen transition and affects the image display quality.

[0017] In particular, considering the low electron mobility, high injection barrier, and high density of deep traps at the interface of the organic layer 04', electrons are more easily trapped by interface traps and accumulate compared to holes. This characteristic is also the main cause of the above-mentioned afterimage phenomenon.

[0018] Figure 3 This application provides a partial structure of a display panel.

[0019] In response to the above problems, such as Figure 3 As shown, this application provides a display panel 10, which includes a light-emitting layer 01, a first electrode 02, and a first common layer 03. The first electrode 02 provides a first type of charge carrier, and the first electrode 02 can be a cathode. Correspondingly, the first type of charge carrier can be electrons. The first common layer 03 is located between the light-emitting layer 01 and the film layer containing the first electrode 02, and the first common layer 03 can be an electron transport layer 301. The light-emitting layer 01 receives the first type of charge carrier through the first common layer 03, wherein the first type of charge carrier can combine with other charge carriers in the light-emitting layer 01 to achieve the light emission process.

[0020] It should be noted that during the diffusion of the first type of charge carriers from the first electrode 02 to the light-emitting layer 01, they need to pass through the first common layer 03. During this process, the first type of charge carriers must cross the interface between the first common layer 03 and other adjacent film layers. Since deep traps are typically distributed near the interfaces of other film layers in the first common layer 03, the first type of charge carriers are at high risk of being captured by these deep traps. Therefore, to avoid the accumulation of the first type of charge carriers near the interface of the first common layer 03, this application chooses to dope the first common layer 03 with a specific material to improve this problem. The specific solution is as follows.

[0021] The first common layer 03 includes a first material 03a and a second material 03b. The lowest unoccupied molecular orbital (LUMO) energy level of the first material 03a for the first type of charge carriers is P1, and the lowest unoccupied molecular orbital energy level of the second material 03b for the first type of charge carriers is P2, where P1 is lower than P2. The first material 03a can be the selectively doped organic semiconductor material TPBi, with the chemical formula C. 45 H 30 N6, the LUMO level P1 corresponding to the first material 03a can be -2.7 eV. The second material 03b can be the organic semiconductor material TmPyPB, with the chemical formula C.39 H 27 The LUMO level P2 corresponding to the second material 03b can be -2.4 eV. It is important to note that the lower the LUMO level of a material, the stronger its trapping ability for type I carriers. Therefore, the trapping effect of the first material 03a in this application on type I carriers is stronger than that of the second material 03b. That is, compared to existing designs, the design of doping the first material 03a in the first common layer 03 helps to utilize the trapping ability of the first material 03a to guide type I carriers accumulated at the interface into the first common layer 03. Specifically, during the transfer of type I carriers from the first electrode 02 to the first common layer 03, the presence of the first material 03a helps to increase the probability of type I carriers crossing the membrane interface and transferring into the first common layer 03.

[0022] It should be clarified that the trap states corresponding to the first material 03a are mostly shallow traps, and these shallow traps can also capture the first type of charge carriers. However, the difference between these shallow traps and the deep traps corresponding to the membrane interface is that when captured by these shallow traps, the first type of charge carriers can easily escape the control of these shallow traps through thermal excitation or tunneling.

[0023] The first common layer 03 includes a first part 031 and a second part 032, with the first part 031 located on the side of the second part 032 away from the light-emitting layer 01. The concentration of the first material 03a in the first part 031 is greater than the concentration of the first material 03a in the second part 032.

[0024] In this embodiment, a higher concentration of the first material 03a indicates a stronger ability to capture first-type carriers. When the concentration of the first material 03a in the first part 031 is greater than that in the second part 032, the doping concentration of the first material 03a decreases along the first direction X in the first common layer 03, forming a gradient concentration doping design along the first direction X; the first direction X can be the direction from the first electrode 02 to the light-emitting layer 01. Therefore, during the transfer of first-type carriers from the first electrode 02 to the light-emitting layer 01, the higher concentration of the first material 03a doping design in the first part 031 makes it easier for first-type carriers to break through the deep traps at the film interface and be captured by the corresponding high-density shallow traps in the first part 031, thus entering the first common layer 03. Furthermore, the gradient concentration doping design of the first material 03a in the first common layer 03 along the first direction X allows the first type of charge carriers trapped by the shallow traps in the first part 031 to transfer to the second part 032 through thermal excitation and tunneling, thus realizing the migration of the first type of charge carriers along the first direction X. In addition, the doping concentration of the first material 03a in the first common layer 03 can decrease along the first direction X. Specifically, in the first common layer 03, in the part corresponding to the film interface near the light-emitting layer 01 (hereinafter referred to as the first lower boundary part), the doping concentration of the first material 03a can be smaller, that is, the shallow trap density in the first lower boundary part can be smaller. At this time, the effect of the shallow traps binding the first type of charge carriers in the first lower boundary part is weaker, which means that the first type of charge carriers are more likely to detach from the first common layer 03 and migrate further towards the light-emitting layer 01. For example, in the first lower boundary portion mentioned above, the doping concentration of the first material 03a can be reduced along the first direction X. For the edge region of the first lower boundary portion near the light-emitting layer 01, the doping concentration of the first material 03a can be as low as 0 (i.e., the first material 03a is not doped in this region), which is beneficial to further improve the departure of the first type of charge carriers from the first common layer 03 along the first direction X and enhance the overall migration efficiency.

[0025] In one possible implementation, the first common layer 03 can be an electron transport layer 301 or an electron injection layer 302. Accordingly, both the electron transport layer 301 and the electron injection layer 302 can be doped with the first material 03a (the figure does not show the case where the electron injection layer 302 is doped with the first material 03a, but this does not mean that this application is limited to the case where the electron injection layer 302 is not doped with the first material 03a), and the first material 03a can be doped in both layers according to the gradient concentration doping method described above.

[0026] Figure 4 This is a schematic diagram showing the energy level differences corresponding to each film layer material in the display panel. Figure 4 The paper illustrates the differences in the LUMO energy levels of the first type of charge carriers among the materials of the first electrode, electron injection layer, electron transport layer, and light-emitting layer when the first material is doped in the electron transport layer.

[0027] like Figure 4 As shown, the LUMO energy level of the material included in the first electrode 02 is P01, the LUMO energy level of the material included in the electron injection layer 302 is P6, the LUMO energy levels of the first material 03a and the second material 03b included in the electron transport layer 301 are P1 and P2 respectively, and the LUMO energy level of the material included in the light-emitting layer 01 is P4. The order of increasing LUMO energy levels satisfies: P01, P6, P1, P2, P4. It is important to note that the greater the difference in LUMO energy levels between the two materials, the more difficult it is for type I carriers to migrate from the lower LUMO energy level material to the higher LUMO energy level material. Therefore, doping the electron transport layer 301 with the first material 03a, whose LUMO energy level is between P6 and P2, means that the first type of charge carriers only need to reach the energy level corresponding to P1 to migrate from the electron injection layer 302 to the electron transport layer 301. This helps to reduce the difficulty of the first type of charge carriers migrating from the electron injection layer 302 to the electron transport layer 301, and is beneficial to improving the migration efficiency of the first type of charge carriers to the light-emitting layer 01.

[0028] In summary, the design of this embodiment helps to increase the mobility of the first type of charge carriers transferring through the first common layer 03 to the light-emitting layer 01, reduces the risk of the first type of charge carriers accumulating at the interface, and thus helps to improve the aforementioned image retention phenomenon and improve the image display quality.

[0029] In one embodiment of this application, 0.1eV≤∣P1∣-∣P2∣≤0.6eV.

[0030] In this embodiment, the design of |P1|-|P2|≥0.1eV helps ensure that the first material 03a has a stronger carrier affinity than the second material 03b, thereby ensuring that the first type of carriers can be effectively captured by the shallow traps in the first common layer 03. Furthermore, the aforementioned LUMO energy level difference range of |P1|-|P2|≤0.6eV helps to achieve a finite difference between the affinity of the first material 03a for the first type of carriers and the affinity of the second material 03b for the first type of carriers, avoiding an excessive difference in carrier affinity between the two materials that would affect the migration efficiency of the first type of carriers in the first common layer 03. Figure 5 This is a schematic diagram of a partial structure of a display panel provided in this application. Figure 6 for Figure 5The diagram shows the energy level differences corresponding to each film layer material in the display panel. Figure 6 The paper illustrates the differences in the LUMO energy levels of the first type of charge carriers among the materials of the first electrode, electron injection layer, electron transport layer, buffer layer, and light-emitting layer when the electron transport layer is doped with the first material.

[0031] In one embodiment of this application, such as Figure 5 As shown, the display panel 10 also includes a buffer layer 05, which is located between the first common layer 03 and the light-emitting layer 01. The buffer layer 05 includes a third material 05a, and the lowest unoccupied molecular orbital energy level (LUMO level) of the third material 05a for the first type of charge carrier is P3. Combination Figure 5 and Figure 6 The light-emitting layer 01 includes a fourth material 01a, and the lowest unoccupied molecular orbital energy level (LUMO energy level) of the fourth material 01a for the first type of charge carrier is P4; wherein, P4 is higher than P3 and P3 is higher than P2.

[0032] In this embodiment, P4 being higher than P3 and P3 being higher than P2 means that the LUMO energy level of the third material 05a is between the LUMO energy levels corresponding to the second material 03b and the fourth material 01a, respectively. The buffer layer 05 provides an intermediate energy level step between P2 and P4. That is, compared to the first type of charge carriers migrating directly from the first common layer 03 (which can refer to the electron transport layer 301) to the luminescent layer 01, the migration difficulty of the first type of charge carriers migrating from the first common layer 03 to the buffer layer 05 and then to the luminescent layer 01 is lower. Therefore, this embodiment design helps to further reduce the migration difficulty of the first type of charge carriers. In one embodiment of this application, the third material 05a can be a bipolar material, specifically including the organic fluorescent material CBP (molecular formula C). 36 H 24 N2), organic intermediate material mCP (molecular formula C 30 H 20 Materials such as N2 and its derivatives. Compared to other materials, the bipolar materials to which the third material 05a belongs can simultaneously transport both electrons and holes as charge carriers.

[0033] In this embodiment, taking advantage of the characteristic that the third material 05a can simultaneously transport both electrons and holes, holes and electrons can migrate to and combine within the buffer layer 05. At this time, the combination of the two types of charge carriers within the buffer layer 05 results in a relatively small number of charge carriers inside the buffer layer 05. Therefore, the charge carriers accumulated in the boundary portion of the buffer layer 05 near the adjacent film layer can continuously migrate into the interior of the buffer layer 05 due to the difference in charge carrier concentration between the interior and the boundary portion. This further reduces the number of charge carriers accumulated in the boundary portion of the buffer layer 05, especially the number of first-type charge carriers, thereby enhancing the migration efficiency of first-type charge carriers within the buffer layer 05.

[0034] In one embodiment of this application, such as Figure 5 As shown, the thickness of the first common layer 03 (which can be the electron transport layer 301) is h1, the thickness of the buffer layer 05 is h2, and 0.03≤h2 / h1≤0.17.

[0035] In this embodiment, the buffer layer 05 has a smaller thickness than the first common layer 03. This thin-layer design helps the buffer layer 05 to function as a smooth interface, making the interface between the buffer layer 05 and the first common layer 03 relatively smooth. The smoother the interface between adjacent film layers, the fewer interface trap states appearing in the film layer boundary region. Therefore, the design in this embodiment helps reduce the number of interface trap states appearing in the first common layer 03, which is beneficial to improving the migration efficiency of type I carriers in the first common layer 03. Furthermore, the thin-layer design of the buffer layer 05 also contributes to reducing the overall thickness of the panel.

[0036] Figure 7 This is a schematic diagram of a partial structure of a display panel provided in this application. Figure 8 for Figure 7 The diagram shows the energy level differences corresponding to each film layer material in the display panel. Figure 8 The paper illustrates the differences in the LUMO energy levels of the first type of charge carriers among the materials of the first electrode, electron injection layer, first passivation layer, electron transport layer, buffer layer, and light-emitting layer when the electron transport layer is doped with the first material.

[0037] In one embodiment of this application, such as Figure 7 As shown, the display panel 10 also includes a second common layer 06 and a first passivation layer 07. The second common layer 06 is located between the first common layer 03 and the film layer containing the first electrode 02, and the first passivation layer 07 is located between the first common layer 03 and the second common layer 06. In this case, the first common layer 03 can be an electron transport layer 301, and the second common layer 06 can be an electron injection layer 302.

[0038] Among them, combined Figure 7 and Figure 8 The lowest unoccupied molecular orbital energy level of the material contained in the first passivation layer 07 for the first type of charge carrier is P5, and the lowest unoccupied molecular orbital energy level of the material contained in the second common layer 06 for the first type of charge carrier is P6. P2 is higher than P5 and P5 is higher than P6.

[0039] In this embodiment, P2 being higher than P5 and P5 being higher than P6 means that the LUMO energy level of the material contained in the first passivation layer 07 is between the LUMO energy levels corresponding to the materials contained in the first common layer 03 and the second common layer 06, respectively. The first passivation layer 07 effectively provides an intermediate energy level step between P2 and P6. That is, compared to the direct migration of first-type charge carriers from the second common layer 06 (here referring to the electron injection layer 302) to the first common layer 03 (here referring to the electron transport layer 301), the migration difficulty of first-type charge carriers from the second common layer 06 to the first passivation layer 07 and then to the first common layer 03 is lower. Therefore, this embodiment design helps to further reduce the migration difficulty of first-type charge carriers.

[0040] In one embodiment of this application, the first passivation layer 07 comprises a metal oxide. Specifically, the metal oxide may be an alkali metal / alkaline earth metal oxide (e.g., LiF, CsF, MgF2) or AlO2. x TiO x Materials such as [material name missing]. Furthermore, the thickness h3 of the first passivation layer 07 can satisfy: h3 ≤ 1 nm.

[0041] In this embodiment, adding metal oxide materials to the film layer helps passivate defects such as dangling bonds and trapped states at the film layer interface, effectively reducing the distribution density of trapped states at the interface, with a particularly significant improvement effect on deep trapped states. This embodiment design utilizes the first passivation layer 07 to reduce the number of trapped states at the interfaces between the first common layer 03, the second common layer 06, and the first passivation layer 07, thereby reducing the number of first-type charge carriers trapped by deep traps at the film layer interface. This alleviates the problem that first-type charge carriers cannot quickly release and participate in conduction during screen switching due to being "locked up" by deep traps at the interface, thus improving the display effect.

[0042] In one embodiment of this application, such as Figure 3As shown, the display panel 10 also includes a second electrode 08 and a third common layer 09. The second electrode 08 provides a second type of charge carrier, which can be holes. The second type of charge carrier can combine with the first type of charge carrier in the light-emitting layer 01 to achieve light emission. The third common layer 09 is located between the light-emitting layer 01 and the film layer containing the second electrode 08. The third common layer 09 can be a hole transport layer 901. The light-emitting layer 01 receives the second type of charge carrier through the third common layer 09, that is, the second type of charge carrier provided by the second electrode 08 can be transferred to the light-emitting layer 01 via the third common layer 09.

[0043] The third common layer 09 includes the fifth material 09a and the sixth material 09b. The highest occupied molecular orbital energy level (HOMO level) of the fifth material 09a for the second type of charge carriers is P7, and the highest occupied molecular orbital energy level of the sixth material 09b for the second type of charge carriers is P8. P7 is higher than P8.

[0044] It is important to note that the higher the HOMO energy level of a material, the stronger its trapping ability for type II carriers. Therefore, the trapping effect of the fifth material 09a doped in this application on type II carriers is stronger than that of the sixth material 09b. That is, compared to existing designs, the design of doping the third common layer 09 with the fifth material 09a helps to utilize the trapping ability of the fifth material 09a to guide type II carriers accumulated at the interface into the third common layer 09. Specifically, during the transfer of type II carriers from the second electrode 08 to the third common layer 09, the presence of the fifth material 09a helps to increase the probability of type I carriers crossing the membrane interface and transferring into the third common layer 09.

[0045] It should be clarified that the trap states corresponding to the fifth material 09a are mostly shallow traps. These shallow traps can also capture type II carriers. However, unlike the deep traps corresponding to the membrane interface, when captured by these shallow traps, type II carriers can easily escape the control of these shallow traps through thermal excitation or tunneling.

[0046] The third common layer 09 includes a third part 091 and a fourth part 092, with the third part 091 located on the side of the fourth part 092 away from the light-emitting layer 01. The concentration of the fifth material 09a in the third part 091 is greater than the concentration of the sixth material 09b in the fourth part 092.

[0047] In this embodiment, a higher concentration of the fifth material 09a indicates a stronger ability to capture second-type carriers. When the concentration of the fifth material 09a in the third part 091 is greater than that in the fourth part 092, the doping concentration of the fifth material 09a in the third common layer 09 decreases along the second direction Y, forming a gradient concentration doping design along the second direction Y; the second direction Y can be the direction from the second electrode 08 to the light-emitting layer 01. Therefore, during the transfer of second-type carriers from the second electrode 08 to the light-emitting layer 01, the higher concentration of the fifth material 09a doping design in the third part 091 makes it easier for second-type carriers to break through the deep traps at the film interface and be captured by the corresponding high-density shallow traps in the third part 091, thus entering the third common layer 09. Furthermore, the gradient concentration doping design of the fifth material 09a in the third common layer 09 along the second direction Y allows the second type of charge carriers trapped by the shallow traps in the third part 091 to transfer to the fourth part 092 through thermal excitation and tunneling, thus realizing the migration of the second type of charge carriers along the second direction Y. In addition, the doping concentration of the fifth material 09a in the third common layer 09 can decrease along the second direction Y. Specifically, in the third common layer 09, in the portion corresponding to the film interface near the light-emitting layer 01 (hereinafter referred to as the second lower boundary portion), the doping concentration of the fifth material 09a can be smaller, that is, the shallow trap density in the second lower boundary portion can be smaller. At this time, the effect of the shallow traps binding the second type of charge carriers in the second lower boundary portion is weaker, which means that the second type of charge carriers are more likely to detach from the third common layer 09 and migrate further towards the light-emitting layer 01. For example, in the second lower boundary portion mentioned above, the doping concentration of the fifth material 09a can be reduced along the second direction Y. For the edge region of the second lower boundary portion near the light-emitting layer 01, the minimum doping concentration of the fifth material 09a can be 0 (i.e., the fifth material 09a is not doped in this region), which is beneficial to further improve the second type of carriers leaving the third common layer 09 along the second direction Y and enhance the overall migration efficiency.

[0048] In one possible implementation, the third common layer 09 can be a hole transport layer 901 or a hole injection layer 902. Accordingly, both the hole transport layer 901 and the hole injection layer 902 can be doped with a fifth material 09a (the figure does not show the case where the hole injection layer 902 is doped with the fifth material 09a, but this does not mean that this application is limited to the case where the hole injection layer 902 is not doped with the fifth material 09a), and the fifth material 09a can be doped in both layers according to the gradient concentration doping method described above.

[0049] Figure 9 This is a schematic diagram showing the energy level differences corresponding to each film layer material in the display panel. Figure 9 The paper illustrates the differences in the HOMO energy levels of the second type of charge carriers among the materials of the second electrode, hole injection layer, hole transport layer, and light emission layer when the hole transport layer is doped with the first material.

[0050] like Figure 9 As shown, the HOMO energy level of the material included in the second electrode 08 is P02, the HOMO energy level of the material included in the hole injection layer 902 is P11, the HOMO energy levels corresponding to the fifth material 09a and the sixth material 09b included in the hole transport layer 901 are P7 and P8 respectively, and the HOMO energy level of the material included in the light-emitting layer 01 is P12. The order of increasing HOMO energy levels satisfies: P02, P11, P7, P8, P12. It is important to note that the greater the difference in HOMO energy levels between the two materials, the more difficult it is for type II carriers to migrate from the material with the higher HOMO energy level to the material with the lower HOMO energy level. Therefore, doping the hole transport layer 901 with a fifth material 09a whose HOMO energy level is between P11 and P8 means that the second type of charge carriers only need to reach the energy level corresponding to P7 to migrate from the hole injection layer 902 to the hole transport layer 901. This helps to reduce the difficulty of the second type of charge carriers migrating from the hole injection layer 902 to the hole transport layer 901, and is conducive to improving the migration efficiency of the second type of charge carriers to the light-emitting layer 01.

[0051] Figure 10 This is a schematic diagram of a partial structure of a display panel provided in this application. Figure 11 for Figure 10 The diagram shows the energy level differences corresponding to each film layer material in the display panel. Figure 11 The paper illustrates the differences in the HOMO energy levels of the second type of charge carriers among the materials of the second electrode, hole injection layer, hole transport layer, second passivation layer, and light-emitting layer when the hole transport layer is doped with a fifth material.

[0052] In one embodiment of this application, such as Figure 10 As shown, the display panel 10 also includes a second passivation layer 011, which is located between the third common layer 09 and the light-emitting layer 01. The second passivation layer 011 includes a metal oxide; specifically, the metal oxide can be an alkali metal / alkaline earth metal oxide (e.g., LiF, CsF, MgF2) or AlO2. x TiO x Materials such as [material name missing]. Furthermore, the thickness h4 of the second passivation layer 011 can satisfy: h4 ≤ 1 nm.

[0053] Among them, combined Figure 10 and Figure 11The highest occupied molecular orbital energy level (HOMO level) for the second type of charge carriers in the material contained in the second passivation layer 011 is P9, and the highest occupied molecular orbital energy level for the second type of charge carriers in the material contained in the luminescent layer 01 is P10. P8 is higher than P9 and P9 is higher than P10.

[0054] In this embodiment, P8 being higher than P9 and P9 being higher than P10 means that the HOMO energy level of the material contained in the second passivation layer 011 is between the HOMO energy levels of the material contained in the third common layer 09 and the material contained in the light-emitting layer 01, respectively. The setting of the second passivation layer 011 is equivalent to providing an intermediate energy level step between P8 and P10. That is, compared to the second type of charge carriers migrating directly from the third common layer 09 (here referring to the hole transport layer 902) to the light-emitting layer 01, the migration difficulty of the second type of charge carriers migrating from the third common layer 09 to the second passivation layer 011 and then to the light-emitting layer 01 is smaller. In addition, the second passivation layer 011 can reduce the number of trapped states at the interfaces between the third common layer 09, the light-emitting layer 01 and the second passivation layer 011, respectively, thereby reducing the number of second type of charge carriers trapped by deep traps at the film interface, thus alleviating the problem that the second type of charge carriers cannot be quickly released to participate in conduction when the screen is switched due to being "locked" by deep traps at the interface, thereby improving the display effect.

[0055] Figure 12 This is a schematic diagram of a display device provided in this application.

[0056] This application provides a display device 20, such as... Figure 12 As shown, the display device 20 includes the aforementioned display panel 10. The display device 20 can be a mobile phone, or it can also be an electronic device such as a computer or television.

[0057] The display device 20 provided in this application embodiment has greatly improved the problem of uneven brightness, such as ghosting, that occurs when switching from a long-term static image to another image.

[0058] The same or similar parts between the various embodiments in this specification can be referred to mutually. In particular, the device embodiments and terminal embodiments are basically similar to the method embodiments, so the description is relatively simple, and the relevant parts can be referred to the description in the method embodiments.

Claims

1. A display panel, characterized in that, include: Emissive layer; The first electrode provides the first type of charge carriers; The first common layer is located between the light-emitting layer and the film layer containing the first electrode; The light-emitting layer receives the first type of charge carriers through the first common layer; the first common layer includes a first material and a second material, the first material having a lowest unoccupied molecular orbital energy level of P1 for the first type of charge carriers, and the second material having a lowest unoccupied molecular orbital energy level of P2 for the first type of charge carriers, where P1 is lower than P2. The first common layer includes a first part and a second part, wherein the first part is located on the side of the second part away from the light-emitting layer; Wherein, the concentration ratio of the first material in the first part is greater than the concentration ratio of the first material in the second part.

2. The display panel according to claim 1, characterized in that, 0.1eV≤∣P1∣-∣P2∣≤0.6eV.

3. The display panel according to claim 1, characterized in that, The display panel further includes a buffer layer located between the first common layer and the light-emitting layer; the buffer layer includes a third material, wherein the lowest unoccupied molecular orbital energy level of the third material for the first type of charge carriers is P3; The light-emitting layer includes a fourth material, wherein the lowest unoccupied molecular orbital energy level of the fourth material for the first type of charge carriers is P4; Among them, P4 is higher than P3 and P3 is higher than P2.

4. The display panel according to claim 3, characterized in that, The thickness of the first common layer is h1, the thickness of the buffer layer is h2, and 0.03≤h2 / h1≤0.

17.

5. The display panel according to claim 3, characterized in that, The buffer layer comprises a bipolar material.

6. The display panel according to claim 1, characterized in that, The display panel further includes a second common layer and a first passivation layer, wherein the second common layer is located between the first common layer and the film layer containing the first electrode, and the first passivation layer is located between the first common layer and the second common layer; Wherein, the lowest unoccupied molecular orbital energy level of the material contained in the first passivation layer for the first type of charge carrier is P5, the lowest unoccupied molecular orbital energy level of the material contained in the second common layer for the first type of charge carrier is P6, P2 is higher than P5 and P5 is higher than P6.

7. The display panel according to claim 6, characterized in that, The first passivation layer comprises a metal oxide.

8. The display panel according to claim 1, characterized in that, The display panel also includes: The second electrode provides the second type of charge carriers; The third common layer is located between the light-emitting layer and the film layer containing the second electrode; the light-emitting layer receives the second type of charge carriers through the third common layer; the third common layer includes a fifth material and a sixth material, the highest occupied molecular orbital energy level of the fifth material for the second type of charge carriers is P7, and the highest occupied molecular orbital energy level of the sixth material for the second type of charge carriers is P8, where P7 is higher than P8; The third common layer includes a third part and a fourth part, wherein the third part is located on the side of the fourth part away from the light-emitting layer; The concentration ratio of the fifth material in the third part is greater than the concentration ratio of the fifth material in the fourth part.

9. The display panel according to claim 8, characterized in that, The display panel further includes a second passivation layer, which is located between the third common layer and the light-emitting layer; Wherein, the highest occupied molecular orbital energy level of the material contained in the second passivation layer for the second type of charge carriers is P9, and the highest occupied molecular orbital energy level of the material contained in the light-emitting layer for the second type of charge carriers is P10, where P8 is higher than P9 and P9 is higher than P10.

10. A display device, characterized in that, Includes the display panel as described in any one of claims 1-9.

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