Light-emitting device and display apparatus

Abstract

The present disclosure provides a light-emitting device and a display device, the light-emitting device comprising a plurality of functional layers stacked in sequence, the plurality of functional layers comprising an anode, a hole transport layer, an electron blocking layer, a light-emitting layer, a hole blocking layer, an electron transport layer and a cathode, the light-emitting layer comprising at least two light-emitting bodies, different light-emitting bodies corresponding to different color sub-pixels; the light-emitting device further comprising at least one energy level transition film layer, the energy level transition film layer being arranged between at least one light-emitting body and the hole transport layer and / or the hole blocking layer, wherein the energy band gap difference between two functional film layers adjacent to the energy level transition film layer is greater than a predetermined value, and the energy level of the energy level transition film layer is between the two functional film layers adjacent thereto. The light-emitting device and the display device provided by the embodiments of the present disclosure can improve the light-emitting efficiency of the light-emitting body, so as to improve the problems such as poor display caused by the difference in light-emitting characteristics of RGB three sub-pixels.

Description

Technical Field

[0001] This disclosure relates to the field of display technology, and in particular to a light-emitting device and a display apparatus. Background Technology

[0002] AMOLED (Active-matrix organic light-emitting diode) is a display technology that uses a self-emissive emission method, displaying different colors through a combination of different RGB light-emitting elements. However, the different light-emitting materials and characteristics of the RGB elements make them difficult to coordinate, resulting in poor image display. Summary of the Invention

[0003] This disclosure provides a light-emitting device and a display apparatus that can improve the luminous efficiency of the light-emitting body, thereby improving problems such as poor image display caused by the difference in luminous characteristics of the RGB three sub-pixels.

[0004] The technical solutions provided in this disclosure are as follows:

[0005] In a first aspect, embodiments of this disclosure provide a light-emitting device comprising multiple functional layers stacked sequentially, the multiple functional layers including an anode, a hole transport layer, an electron blocking layer, a light-emitting layer, a hole blocking layer, an electron transport layer, and a cathode, the light-emitting layer including at least two light emitters, different light emitters corresponding to sub-pixels of different colors; the light-emitting device further includes at least one energy level transition film layer, the energy level transition film layer being disposed between at least one of the light emitters and the hole transport layer and / or the hole blocking layer, wherein the energy level band gap difference between two functional film layers adjacent to the energy level transition film layer is greater than a predetermined value, and the energy level of the energy level transition film layer is between the two functional film layers adjacent to it.

[0006] For example, the HOMO bandgap difference between the electron blocking layer and at least one of the light emitters is greater than the predetermined value, and at least one energy level transition film layer includes a first energy level transition film layer, which is disposed between the electron blocking layer and the at least one light emitter, and the HOMO energy level of the first energy level transition film layer is between the at least one light emitter and the electron blocking layer.

[0007] For example, the difference in the HOMO level bandgap between the electron blocking layer and the hole transport layer is less than or equal to the predetermined value.

[0008] For example, the HOMO bandgap difference between the electron blocking layer and the hole transport layer is greater than the predetermined value, and at least one of the energy level transition layers includes a second energy level transition layer, which is disposed between the electron blocking layer and the at least one light emitter, and the LUMO energy level of the second energy level transition layer is between the hole transport layer and the electron blocking layer.

[0009] For example, the HOMO band gap difference between the electron blocking layer and at least one of the light emitters is less than or equal to the predetermined value.

[0010] For example, at least two of the light emitters have different material luminous efficiencies, wherein the light emitter with the lowest luminous efficiency is the first light emitter, and the energy level transition film layer is disposed between the first light emitter and the hole transport layer, and / or between the first light emitter and the hole blocking layer.

[0011] For example, the material of the first light-emitting body is a fluorescent material.

[0012] For example, at least two of the light emitters also include a second light emitter and a third light emitter, wherein the second light emitter and the third light emitter are made of phosphorescent material.

[0013] For example, at least two of the light emitters have different LUMO bandgap differences with the hole blocking layer, wherein the light emitter with the largest LUMO bandgap difference with the hole blocking layer is the first light emitter, and at least one energy level transition film layer includes a third energy level transition film layer, which is disposed between the first light emitter and the hole blocking layer.

[0014] For example, the HOMO energy level of the third energy level transition film is larger than the HOMO energy level of the hole blocking layer.

[0015] For example, the energy level band gap difference between the energy level transition film layer and one of the two adjacent functional film layers is a first difference value, and the energy level band gap difference between the energy level transition film layer and the other of the two adjacent functional film layers is a second difference value, and the difference between the first difference value and the second difference value is less than a predetermined threshold value.

[0016] Secondly, embodiments of this disclosure also provide a display device, including the light-emitting device described above.

[0017] The beneficial effects of the embodiments disclosed herein are as follows:

[0018] In the above scheme, a level transition film layer is inserted into at least one side of the hole side and electron side of at least one of the light-emitting elements in the light-emitting device. The level transition film layer is located between two functional film layers with a band gap difference greater than a predetermined value, and the energy level of the level transition film layer is between the two functional film layers. In this way, the insertion of the level transition film layer makes the energy levels between the functional film layers with a large band gap difference more matched. When the level transition film layer is located on the hole side of the light-emitting element, it is more conducive to the injection and transport of holes on the hole side, thereby reducing the turn-on voltage of the corresponding light-emitting element and improving the light-emitting performance of the light-emitting element at low brightness. When the level transition film layer is located on the electron side of the light-emitting element, it is more conducive to the injection and transport of electrons on the electron side, while blocking the transport of holes to the electron side, so that more charge carriers recombine in the light-emitting region to form excitons, thereby improving the light-emitting efficiency of the corresponding light-emitting element. Therefore, by inserting the energy level transition film layer between two functional film layers with a large energy level band gap difference, the luminous performance and luminous efficiency of the corresponding light-emitting body can be adjusted to coordinate the luminous characteristics of different color light-emitting bodies for different application scenarios, thereby improving problems such as poor image quality. Attached Figure Description

[0019] Figure 1 This graph shows the measured IV characteristics of the luminescent material of an AMOLED display with three sub-pixels in the relevant technology.

[0020] Figure 2 This is a comparison of the TFT characteristic curves of the third thin-film transistor T3 in an AMOLED display before and after a reliability test (THO), where curve a represents the reliability test before the test and curve b represents the reliability test after the test.

[0021] Figure 3 This diagram illustrates the structure of a light-emitting device in one embodiment of the present disclosure.

[0022] Figure 4 This figure shows a comparison of the IV characteristic curves of light-emitting devices in related technologies and light-emitting devices in the embodiments of this disclosure. Curve 1 in the figure is the IV characteristic curve of the light-emitting device in related technologies, and Curve 2 is the IV characteristic curve of the light-emitting device provided in the embodiments of this disclosure.

[0023] Figure 5 This is a schematic diagram showing the structure of a light-emitting device in another embodiment of the present disclosure;

[0024] Figure 6 This is a schematic diagram showing the structure of a light-emitting device in another embodiment of the present disclosure;

[0025] Figure 7 This is a schematic diagram showing the structure of a light-emitting device in another embodiment of the present disclosure;

[0026] Figure 8 This is a schematic diagram showing the structure of a light-emitting device in another embodiment of the present disclosure;

[0027] Figure 9 This is a schematic diagram showing the structure of a light-emitting device in another embodiment of the present disclosure. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of the embodiments of this disclosure clearer, the technical solutions of the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this disclosure. All other embodiments obtained by those skilled in the art based on the described embodiments of this disclosure without creative effort are within the scope of protection of this disclosure.

[0029] Unless otherwise defined, the technical or scientific terms used in this disclosure shall have the ordinary meaning understood by one of ordinary skill in the art to which this disclosure pertains. The terms “first,” “second,” and similar terms used in this disclosure do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Similarly, the terms “an,” “a,” or “the,” and similar terms do not indicate a quantity limitation, but rather indicate the presence of at least one. The terms “including,” “comprising,” or “containing,” and similar terms mean that the element or object preceding the word encompasses the elements or objects listed following the word and their equivalents, without excluding other elements or objects. The terms “connected,” “linked,” or similar terms are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. The terms “upper,” “lower,” “left,” and “right,” etc., are used only to indicate relative positional relationships, and these relative positional relationships may change accordingly when the absolute position of the described objects changes.

[0030] Before providing a detailed description of the light-emitting device and display apparatus provided in the embodiments of this disclosure, it is necessary to explain the related technologies as follows:

[0031] In related technologies, AMOLED display technology adopts a self-emissive method, displaying different colors through different combinations of RGB light emitters. However, the display screen has display defects such as yellowing of white screens at low grayscale levels. In particular, after conducting a reliability test (Temp Humidity Operation, or THO for short), the yellowing of white screens at low grayscale levels is particularly noticeable.

[0032] To solve the above problems, the inventors of this disclosure have discovered through research that the reason for poor image display is that the light-emitting materials of the three sub-pixels R (red), G (green), and B (blue) are different. Typically, R and G sub-pixels use phosphorescent materials with high luminous efficiency, while B sub-pixels use fluorescent materials with low luminous efficiency. This results in a significant difference between the light-emitting characteristics of B sub-pixels and those of R and G sub-pixels. One such difference is reflected in the difference in IV (current-voltage) characteristics at low brightness.

[0033] The measured IV characteristic curves of the luminescent materials of the RGB three sub-pixels of an AMOLED display, based on relevant technologies, are shown below. Figure 1 As shown. The inventor of this disclosure, through... Figure 1 Analysis of the test results revealed that at high brightness (255 grayscale) display, the driving voltages of the RGB three sub-pixels were comparable at the corresponding current density (shown in dashed box A). However, at low brightness display (shown in dashed box B), the IV curves of the RGB three sub-pixels showed significant differences, with the B sub-pixel exhibiting the highest driving voltage at the same current density. Furthermore, after the reliability test, the threshold voltage (Vth) of the TFT circuit drifted. With the same voltage change, the brightness changes of the R and G sub-pixels were significantly greater than those of the B sub-pixel, resulting in a noticeable yellowing of the white screen after the reliability test.

[0034] Reliability testing was conducted on the AMOLED display in the relevant technology, and the changes in TFT characteristics before and after the reliability test are shown in Table 1. Table 1 shows the changes in threshold voltage (Vth) and DR range of the first thin-film transistor T1, the second thin-film transistor T2, and the third thin-film transistor T3 in the AMOLED display before and after the reliability test (THO). Figure 2 This graph shows a comparison of the TFT characteristic curves of the third thin-film transistor T3 in the AMOLED display before and after the reliability test (THO), where curve a represents the curve before the reliability test and curve b represents the curve after the reliability test.

[0035] It should be noted that on the TFT transfer curve, at a specific source-drain voltage Vds, different data voltages Vdata correspond to different currents Ids, thus corresponding to different brightness levels. DR range, or Data Range, refers to the difference in Vgs values ​​corresponding to the currents Ids for two brightness levels. The larger this value, the smaller the change in current Ids caused by the data voltage Vdata error, and the smaller the corresponding brightness error.

[0036] Table 1

[0037]

[0038] As shown in Table 1 above, after the reliability test (THO), the threshold voltage Vth of the first thin-film transistor T1, the second thin-film transistor T2, and the third thin-film transistor T3 all showed different degrees of positive bias, and the DR range all increased to different degrees, with the third thin-film transistor T3 showing the most significant change.

[0039] Depend on Figure 1 As can be seen, after the reliability test, the threshold voltage Vth of the third thin-film transistor T3 is forward biased by 0.8V, and the DR range increases by 0.16V. A forward bias of the threshold voltage Vth and an increase in the DR range will increase brightness. When the changes in Vth and DR range of the RGB sub-pixels are roughly equivalent after the reliability test, due to the differences in the light-emitting characteristics of the luminescent materials of the RGB sub-pixels, the brightness increase of the R and G sub-pixels will be significantly greater than that of the B sub-pixel. This leads to an imbalance in the white screen ratio, resulting in a yellowish white screen display.

[0040] As can be seen from the above analysis, to solve the problem of yellowing on white screens, we can address the TFT characteristic drift issue after reliability testing, and improve the light-emitting characteristics of the light-emitting device by reducing the turn-on voltage of the low-efficiency light-emitting element and improving its IV characteristics at low gray levels.

[0041] This disclosure provides a light-emitting device and display apparatus that improves the light-emitting characteristics of light-emitting devices and enhances the IV characteristics of light-emitting bodies with low luminous efficiency under low grayscale display conditions. This improves the problem of poor screen display caused by the differences in the light-emitting characteristics of RGB light-emitting bodies.

[0042] like Figures 3 to 9 As shown, the light-emitting device provided in this embodiment includes an anode 100, a hole-side functional film layer 200, an emission layer (EML) 300, an electron-side functional film layer 400, and a cathode (ctd) 500 stacked sequentially.

[0043] The light-emitting layer 300 includes at least two light emitters 310, with different light emitters 310 corresponding to sub-pixels of different colors. For example, in some embodiments, the at least two light emitters 310 include a first light emitter 311, a second light emitter 312, and a third light emitter 313 that can correspond to sub-pixels of different colors. The first light emitter 311, the second light emitter 312, and the third light emitter 313 can emit light of different colors respectively. The light-emitting materials selected for different sub-pixels can be different. The luminous efficiency of the light-emitting material of at least one light emitter 310 is lower than that of the light-emitting materials of other light emitters 310, and the relative energy levels of the different light emitters 310 can also be different. For example, the luminous efficiency of the light-emitting material of the first light emitter 311 is lower than that of the light-emitting materials of the second light emitter 312 and the third light emitter 313.

[0044] The hole-side functional film layer 200 may include a hole transport layer (HTL) 210 and an electron block layer (EBL) 220 located between the hole transport layer 210 and the light-emitting layer 300. The electron block layer 220 may include at least two electron blocking regions corresponding to different light-emitting elements 310, for example... Figure 3 The first electron blocking region 221, the second electron blocking region 222, and the third electron blocking region 223 are included in the light-emitting layer 300; the electron-side functional film layer 400 may include an electron transport layer (ETL) 410 and a hole blocking layer (HBL) 420 located between the electron transport layer 410 and the light-emitting layer 300.

[0045] The light-emitting device further includes at least one energy level transition film layer 600, wherein the at least one energy level transition film layer 600 is disposed between at least one light-emitting element 310 and the anode 100, that is, at least one energy level transition film layer 600 is disposed on the hole side of at least one light-emitting element 310; and / or, at least one energy level transition film layer 600 is disposed between at least one light-emitting element 310 and the cathode 500 layer, that is, at least one energy level transition film layer 600 is disposed on the electron side of at least one light-emitting element 310. Furthermore, the band gap difference between two functional films adjacent to the energy level transition film layer 600 is greater than a predetermined value, and the energy level of the energy level transition film layer 600 is between the two adjacent functional films, that is, the energy level transition film layer 600 is located between two functional films with a band gap difference greater than a predetermined value, and the energy level of the energy level transition film layer 600 is between these two functional films.

[0046] In the above scheme, a level transition film layer 600 is inserted into at least one side of the light-emitting device, either the hole side or the electron side. This level transition film layer 600 is located between two functional films with a band gap difference greater than a predetermined value, and its energy level is between these two functional films. Thus, the insertion of the level transition film layer 600 improves the energy level matching between the functional films with a large band gap difference. When the level transition film layer 600 is located on the hole side of the light-emitting device 310, it facilitates hole injection and transport, reducing the turn-on voltage of the corresponding light-emitting device 310 and improving its luminous performance at low brightness. When the level transition film layer 600 is located on the electron side of the light-emitting device 310, it facilitates electron injection and transport while blocking hole transport to the electron side, allowing more charge carriers to recombine in the luminous region to form excitons, thereby improving the luminous efficiency of the corresponding light-emitting device 310. Therefore, by inserting the energy level transition film layer 600 between two functional film layers with a large energy level band gap, the luminous performance and luminous efficiency of the corresponding light emitter 310 can be adjusted to coordinate the luminous characteristics of different color light emitters 310 for different application scenarios, so as to improve problems such as poor image quality.

[0047] For example, the band gap difference between the energy level transition film layer 600 and one of the two adjacent functional film layers is a first difference, and the band gap difference between the energy level transition film layer 600 and the other of the two adjacent functional film layers is a second difference, wherein the difference between the first difference and the second difference is less than a predetermined threshold.

[0048] Using the above scheme, the predetermined threshold can be 0 or a very small value, so that the energy level of the energy level transition film layer 600 is as close as possible to the center of the energy levels of its two adjacent functional films. In other words, the energy level of the energy level transition film layer 600 and the energy level difference of its two adjacent functional films are approximately the same.

[0049] The light-emitting device provided in the embodiments of this disclosure will be described in more detail below with reference to the accompanying drawings.

[0050] Figure 3 The diagram shown is a schematic diagram of the structure of a light-emitting device provided in some embodiments of this disclosure.

[0051] like Figure 3As shown, in this embodiment, the HOMO bandgap difference between the electron blocking layer 220 and at least one of the light emitters 310 is greater than the predetermined value. At least one energy level transition film layer 600 includes a first energy level transition film layer 610, which is disposed between the electron blocking layer 220 and the at least one light emitter 310. That is, the first energy level transition film layer 610 is disposed between at least one light emitter 310 and its corresponding electron blocking region, and the HOMO energy level of the first energy level transition film layer 610 is between the at least one light emitter 310 and the electron blocking layer 220.

[0052] In related technologies, an electron blocking layer 220 is typically provided between the hole transport layer 210 and the light emitter 310. Because different sub-pixels have different material choices for their light emitters 310, the energy levels of the light emitters 310 relative to the electron blocking layer 220 differ, making it impossible to guarantee a perfect energy level match between the various functional film layers. When the energy level bandgap difference between the luminescent material of a certain light emitter 310 and the electron blocking layer 220 is large, the hole injection barrier between the electron blocking layer 220 and the light emitter 310 is high. This results in holes from the anode 100 via the hole transport layer 210 needing to overcome a relatively high barrier to inject into the light emitter 310, naturally increasing the turn-on voltage of the light emitter 310 and reducing the concentration of luminescent carriers. At low brightness, the effect is even more pronounced due to the low number and concentration of carriers.

[0053] By adopting the above scheme, when the energy level bandgap difference between the electron blocking layer 220 and at least one light emitter 310 is greater than a predetermined value, a first energy level transition film layer 610 with matching energy level can be inserted between the electron blocking layer 220 and the at least one light emitter 310. The HOMO energy level of the first energy level transition film layer 610 is between the at least one light emitter 310 and the corresponding electron blocking region. In this way, it is equivalent to constructing two energy level transition film layers 600 between the at least one light emitter 310 and the hole transport layer 210, namely the electron blocking region and the first energy level transition film layer 610, which reduces the energy level difference between layers and makes the energy levels between hole-side layers more matched. Compared with the related technology, which does not set an energy level transition film layer 600 between the hole transport layer 210 and the light emitter 310, it is more conducive to hole injection and transport, can reduce the turn-on voltage of the light emitter 310, improve the light emission performance of the light emitter 310 at low brightness, and can achieve the purpose of coordinating the light emission characteristics of different sub-pixels.

[0054] It should be noted that, in the above scheme, due to the setting of the first energy level transition film layer 610, even under low brightness conditions of the light-emitting device, or even in the initial stage when the light-emitting device is just lit, a small number of charge carriers can be injected and transported in the device more easily, thereby improving the IV characteristics of the light-emitting body 310 with the first energy level transition film layer 610 in low brightness display.

[0055] In this embodiment, for example, at least two of the light emitters 310 have different luminous efficiencies, with the light emitter 310 having the lowest luminous efficiency being the first light emitter 311. The energy level transition film layer 600 is disposed between the first light emitter 311 and the electron blocking layer 220. Specifically, in some embodiments, at least two light emitters 310 include a first light emitter 311, a second light emitter 312, and a third light emitter 313. The first light emitter 311 may be made of a low-efficiency fluorescent material, and the energy level band gap difference between the first light emitter 311 and the corresponding electron blocking region is greater than a predetermined value. The second light emitter 312 and the third light emitter 313 are made of high-efficiency phosphorescent materials, and the energy level band gap difference between the second light emitter 312 and the third light emitter 313 and the corresponding electron blocking region is less than or equal to a predetermined value. Therefore, the first energy level transition film layer 610 may be disposed between the first light emitter 311 and the corresponding electron blocking region.

[0056] For example, the first light emitter 311 can be a blue light emitter 310, the second light emitter 312 can be a red light emitter 310, and the third light emitter 313 can be a green light emitter 310. This reduces the turn-on voltage of the blue light emitter 310, improves the light-emitting performance of the B sub-pixel at low brightness, and makes the IV characteristics of the B sub-pixel better matched with those of the R and G sub-pixels, effectively improving the problem of yellowing in low grayscale white images after reliability testing.

[0057] It should be noted that the above description is based on the example of setting a first energy level transition film layer 610 between the blue light emitter 310 and the corresponding electron blocking region. In practical applications, the energy level transition layer is also applicable to the red light emitter 310 and the green light emitter 310 to improve the light emission performance of a single monochromatic light, so that the light emission performance of the RGB three sub-pixels is more matched and the display effect of white light is balanced.

[0058] For the light-emitting device provided in this embodiment, IVL performance testing was performed. During the test, the HOMO and LUMO energy level parameters of the light-emitting device were used as variables, and the electrical module of the Setfos simulation software was used for simulation to obtain the following results: Figure 2 The simulated curves of IVL characteristics are shown.

[0059] from Figure 2As can be seen, the light-emitting device provided in this embodiment can significantly reduce the energy level barrier between the layers due to the addition of the first energy level transition film layer 610. The IV characteristics of the B sub-pixel under low voltage are significantly improved, which is more in line with the IV characteristics of R and G in the pixel.

[0060] In addition, the following combination Figure 4 This explains how improving the IV characteristics of the B sub-pixel at low brightness can alleviate the yellowing phenomenon of white screens after low grayscale reliability testing. Assuming Curve 1 represents the IV characteristic curve of a light-emitting device in related technologies, and Curve 2 represents the IV curve of the light-emitting device provided in this embodiment, the TFT characteristics of the light-emitting device provided in this embodiment drift by ΔV before and after reliability testing. Therefore, the brightness change of the B sub-pixel in the related technologies after reliability testing is Δ1, while the brightness change of the B sub-pixel in the light-emitting device provided in this embodiment is Δ2. Clearly, the change in Δ2 is significantly greater than Δ1. This solves the problem that the brightness increase of blue light after reliability testing is less than that of red and green light, making the brightness changes of the RGB three sub-pixels as close as possible to each other after reliability testing, thereby solving the problem of yellowing of white screens after reliability testing at low grayscale levels.

[0061] Furthermore, it should be noted that the light-emitting device provided in this embodiment can use a material with high carrier mobility for the energy level transition film layer 600, which can also increase the carrier concentration in the device, increase the recombination probability of excitons, further improve the luminous efficiency and lifespan of the light-emitting device under high brightness, and reduce color shift after long-term display.

[0062] Figure 5 The diagram shown is a schematic diagram of the structure of a light-emitting device provided in another embodiment of this disclosure.

[0063] like Figure 5 As shown, in this embodiment, when the HOMO bandgap difference between the electron blocking layer 220 and the light emitter 310 is less than or equal to a predetermined value, and the HOMO bandgap difference between the electron blocking layer 220 and the hole transport layer 210 is greater than the predetermined value, at least one of the energy level transition film layers 600 includes a second energy level transition film layer 620. The second energy level transition film layer 620 is disposed between the electron blocking layer 220 and the at least one light emitter 310, and the LUMO energy level of the second energy level transition film layer 620 is between the hole transport layer 210 and the electron blocking layer 220.

[0064] Figure 6 The diagram shown is a schematic diagram of the structure of a light-emitting device provided in another embodiment of this disclosure.

[0065] like Figure 6As shown, in this embodiment, when the HOMO bandgap difference between the electron blocking layer 220 and the light emitter 310 is greater than a predetermined value, and the HOMO bandgap difference between the electron blocking layer 220 and the light emitter 310 is also greater than a predetermined value, a first energy level transition film layer 610 can be provided between the electron blocking layer 220 and the light emitter 310, and a second energy level transition film layer 620 can be provided between the electron blocking layer 220 and the hole transport layer 210. The second energy level transition film layer 620 is provided between the electron blocking layer 220 and the at least one light emitter 310, and the LUMO energy level of the second energy level transition film layer 620 is between the hole transport layer 210 and the electron blocking layer 220.

[0066] Figure 7 The diagram shown is a schematic diagram of the structure of a light-emitting device provided in another embodiment of this disclosure.

[0067] like Figure 7 As shown, at least two of the light emitters 310 have different LUMO band gaps with the hole blocking layer 420, wherein the light emitter 310 with the largest LUMO band gap with the hole blocking layer 420 is the first light emitter 311, and at least one energy level transition film layer 600 includes a third energy level transition film layer 630, which is disposed between the first light emitter 311 and the hole blocking layer 420.

[0068] Using the above scheme, since the hole blocking layer 420 is formed by evaporation using an open mask and serves as the common layer on the electron side of the RGB three-sub-pixel light emitters 310, it is difficult to ensure that the HOMO and LUMO energy levels of the hole blocking layer 420 are perfectly matched with the HOMO and LUMO energy levels of the RGB three-sub-pixel light emitters 310. Therefore, if the LUMO energy level bandgap difference between the hole blocking layer 420 and the light emitter 310 is large, a third energy level transition film layer 630 can be inserted between the light emitter 310 and the hole blocking layer 420. The third energy level transition film layer 630 should ensure that its LUMO energy level matches the LUMO energy levels of the light emitter 310 and the hole blocking layer 420. As a preferred embodiment, the HOMO energy level of the third energy level transition film layer 630 is larger than the HOMO energy level of the hole blocking layer 420 material. This not only increases the injection and transport of electrons on the electron side, but also effectively blocks the transport of holes on the hole side to the ETL layer, allowing more charge carriers to recombine and form excitons in the light-emitting region, thereby improving the luminous efficiency of blue light devices.

[0069] In this embodiment, for example, at least two of the light emitters 310 have different material luminous efficiencies, wherein the light emitter 310 with the lowest luminous efficiency is the first light emitter 311, and the energy level transition film layer 600 is disposed between the first light emitter 311 and the hole blocking layer 420.

[0070] Figure 8 The diagram shown is a schematic diagram of the structure of a light-emitting device provided in another embodiment of this disclosure. Figure 9 The diagram shown is a schematic diagram of the structure of a light-emitting device provided in another embodiment of this disclosure.

[0071] like Figure 8 and Figure 9 As shown, in this embodiment, an energy level transition film layer 600 can be provided on both the hole side and the electron side of the light emitter 310 to further balance the transport of holes and electrons, so that more charge carriers recombine in the light-emitting region to form excitons, thereby further improving the luminous efficiency of the blue light device.

[0072] It should be noted that in the above embodiments, the description is based on the example of the light-emitting layer 300 including the first light-emitting body 311, the second light-emitting body 312 and the third light-emitting body 313. In order to reduce the turn-on voltage of the B sub-pixel and improve the light-emitting efficiency of the B sub-pixel, the description is based on the example of setting an energy level transition film layer 600 on the hole side and the electron side of the light-emitting body 310 corresponding to the B sub-pixel.

[0073] It should be understood that, in practical applications, an energy level transition film layer 600 can also be provided on the hole side and / or electron side of the luminescent device of the R and B sub-pixels to improve the luminous efficiency of the R and B sub-pixels.

[0074] Furthermore, it should be noted that the light-emitting device provided in this embodiment is an OLED device, which may also include a hole injection layer (P-dopont) 700, a capping layer (CPL) 800, etc.

[0075] Furthermore, this disclosure also provides a display device, including the light-emitting device provided in this disclosure.

[0076] The following points need to be explained:

[0077] (1) The accompanying drawings of the embodiments of this disclosure only involve the structures involved in the embodiments of this disclosure. Other structures can be referred to the general design.

[0078] (2) For clarity, the thickness of layers or regions is enlarged or reduced in the drawings used to describe embodiments of the present disclosure, i.e., these drawings are not drawn to actual scale. It will be understood that when an element such as a layer, film, region or substrate is referred to as being “above” or “below” another element, the element may be “directly” located “above” or “below” the other element or there may be intermediate elements.

[0079] (3) Where there is no conflict, the embodiments of this disclosure and the features in the embodiments can be combined with each other to obtain new embodiments.

[0080] The above are merely specific embodiments of this disclosure, but the scope of protection of this disclosure is not limited thereto. The scope of protection of this disclosure shall be determined by the scope of the claims.

Claims

1. A light-emitting device comprising multiple functional layers stacked sequentially, the multiple functional layers including an anode, a hole transport layer, an electron blocking layer, a light-emitting layer, a hole blocking layer, an electron transport layer, and a cathode, the light-emitting layer including at least two light emitters, different light emitters corresponding to sub-pixels of different colors; the light-emitting device further comprising at least one energy level transition film layer, the energy level transition film layer being disposed between at least one of the light emitters and the hole transport layer and / or the hole blocking layer, wherein the band gap difference between two functional layers adjacent to the energy level transition film layer is greater than a predetermined value, and the energy level of the energy level transition film layer is between the two adjacent functional layers; wherein... The materials of at least two of the light emitters have different luminous efficiencies, with the light emitter having the lowest luminous efficiency being the first light emitter. The material of the first light emitter is a fluorescent material. The at least two light emitters also include a second light emitter and a third light emitter, which are made of phosphorescent materials. The energy level transition film layer is disposed only between the first light emitter and the hole transport layer, and / or between the first light emitter and the hole blocking layer.

2. The light-emitting device according to claim 1, characterized in that, The HOMO bandgap difference between the electron blocking layer and at least one of the light emitters is greater than the predetermined value. At least one energy level transition film layer includes a first energy level transition film layer, which is disposed between the electron blocking layer and the at least one light emitter, and the HOMO energy level of the first energy level transition film layer is between the at least one light emitter and the electron blocking layer.

3. The light-emitting device according to claim 2, characterized in that, The difference in the HOMO level bandgap between the electron blocking layer and the hole transport layer is less than or equal to the predetermined value.

4. The light-emitting device according to claim 1, characterized in that, The HOMO bandgap difference between the electron blocking layer and the hole transport layer is greater than the predetermined value, and at least one of the energy level transition layers includes a second energy level transition layer, which is disposed between the electron blocking layer and the hole transport layer, and the LUMO energy level of the second energy level transition layer is between the hole transport layer and the electron blocking layer.

5. The light-emitting device according to claim 4, characterized in that, The difference in the HOMO band gap between the electron blocking layer and at least one of the light emitters is less than or equal to the predetermined value.

6. The light-emitting device according to any one of claims 1 to 5, characterized in that, At least two of the light emitters have different LUMO band gaps with the hole blocking layer, wherein the light emitter with the largest LUMO band gap with the hole blocking layer is the first light emitter, and at least one energy level transition film layer includes a third energy level transition film layer, which is disposed between the first light emitter and the hole blocking layer.

7. The light-emitting device according to claim 6, characterized in that, The HOMO energy level of the third energy level transition film is larger than the HOMO energy level of the hole blocking layer.

8. The light-emitting device according to claim 1, characterized in that, The energy level band gap difference between the energy level transition film layer and one of the two adjacent functional film layers is a first difference value, and the energy level band gap difference between the energy level transition film layer and the other of the two adjacent functional film layers is a second difference value. The difference between the first difference value and the second difference value is less than a predetermined threshold value.

9. A display device, characterized in that, Includes the light-emitting device as described in any one of claims 1 to 8.

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