Organic light emitting display panel and display device

Abstract

The application provides an organic light-emitting display panel and a display device. The organic light-emitting display panel comprises a substrate and a light-emitting layer arranged on the substrate. The light-emitting layer comprises at least two light-emitting units arranged in layers, the light-emitting unit comprises a first light-emitting sublayer, a second light-emitting sublayer and a third light-emitting sublayer, the third light-emitting sublayer is arranged between the first light-emitting sublayer and the second light-emitting sublayer, the first light-emitting sublayer and the second light-emitting sublayer are both one of a host material layer and a guest material layer, and the third light-emitting sublayer is the other of the host material layer and the guest material layer. The application forms a plurality of dispersed exciton recombination regions in the light-emitting layer, reduces the concentration of excitons in the recombination region, can reduce exciton quenching and thermal radiation, and effectively prolongs the service life.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of display, in particular to an organic light emitting display panel and a display device. BACKGROUND

[0002] Compared with liquid crystal display screens, organic light emitting diode (OLED) display screens have the advantages of lightness and thinness, good display effect, high resolution, wide color gamut, energy saving, flexibility and the like. In recent years, organic light emitting display technology has developed rapidly and has become the first choice for screens of terminal products such as mobile phones.

[0003] At present, the light emitting layer in the organic light emitting diode light emitting device is almost doped with guest light emitting materials in the host material, and the energy is transferred from the host material with larger energy to the guest light emitting material to emit light. In the organic light emitting display device with the light emitting layer doped with host and guest, long service life is one of the important indicators of excellent performance. SUMMARY

[0004] Therefore, the present application aims to provide an organic light emitting display panel and a display device capable of prolonging service life.

[0005] The present application provides an organic light emitting display panel, which comprises:

[0006] a substrate;

[0007] a first electrode disposed on the substrate;

[0008] a second electrode disposed on a side of the first electrode away from the substrate and opposite to the first electrode; and

[0009] a light emitting layer disposed between the first electrode and the second electrode, the light emitting layer comprising at least two light emitting units stacked, the light emitting unit comprising a first light emitting sub-layer, a second light emitting sub-layer and a third light emitting sub-layer, the third light emitting sub-layer being disposed between the first light emitting sub-layer and the second light emitting sub-layer;

[0010] wherein the first light emitting sub-layer and the second light emitting sub-layer are one of a host material layer and a guest material layer, and the third light emitting sub-layer is the other of the host material layer and the guest material layer.

[0011] Optionally, in an embodiment, in each of the light emitting units, the first light emitting sub-layer and the second light emitting sub-layer are of the same material, and the thickness difference is not more than 10 nm.

[0012] Optionally, in an embodiment, in two adjacent light-emitting units, the adjacent first light-emitting sub-layer and the second light-emitting sub-layer are both host material layers, and the sum of the thicknesses of the adjacent first light-emitting sub-layer and the second light-emitting sub-layer is greater than or equal to or

[0013] In two adjacent light-emitting units, the adjacent first light-emitting sub-layer and the second light-emitting sub-layer are both guest material layers, and the sum of the thicknesses of the adjacent first light-emitting sub-layer and the second light-emitting sub-layer is greater than or equal to

[0014] Optionally, in an embodiment, in two adjacent light-emitting units, the thicknesses of the adjacent first light-emitting sub-layer and the second light-emitting sub-layer are the same.

[0015] Optionally, in an embodiment, in two adjacent light-emitting units, the thicknesses of the adjacent first light-emitting sub-layer and the second light-emitting sub-layer are different.

[0016] Optionally, in an embodiment, the thickness of the light-emitting unit is greater than or equal to 2 nm, and the thickness ratio of the guest material layer to the host material layer is less than or equal to 0.25.

[0017] Optionally, in an embodiment, the thickness of the light-emitting unit is greater than or equal to 2 nm, and the light-emitting layer includes 2 to 10 light-emitting units.

[0018] Optionally, in an embodiment, the thickness of the light-emitting layer ranges from to

[0019] Optionally, in an embodiment, the energy level difference between the lowest unoccupied molecular orbital energy level of the host material in the host material layer and the lowest unoccupied molecular orbital energy level of the guest material in the guest material layer is greater than 0 and less than or equal to 0.3 eV; and / or

[0020] The energy level difference between the highest occupied molecular orbital energy level of the guest material in the guest material layer and the highest occupied molecular orbital energy level of the host material in the host material layer is greater than 0 and less than or equal to 0.3 eV.

[0021] Optionally, in an embodiment, the guest material layer is a phosphorescent material layer or a fluorescent material layer.

[0022] Optionally, in an embodiment, the wavelength of the light-emitting peak of the guest material layer is between 450 nm and 475 nm, the half-width of the guest material layer is less than or equal to 35 nm, and the film-state light-emitting quantum yield of the guest material layer is greater than or equal to 60%.

[0023] This application provides an organic light-emitting display device, which includes a processor and an organic light-emitting display panel as described in any of the preceding claims, wherein the organic light-emitting display panel is electrically connected to the processor.

[0024] The organic light-emitting display panel of this application uses multiple stacked light-emitting units to form the light-emitting layer of the device. Each light-emitting unit has a structure of either two host material layers sandwiching a guest material layer or two guest material layers sandwiching a host material layer. In each light-emitting unit, an exciton recombination region is formed only at the interface between the host material layer and the guest material layer. Multiple dispersed exciton recombination regions are formed in the light-emitting layer, reducing the concentration of excitons in the recombination regions, which can reduce exciton quenching and thermal radiation, and effectively extend the service life. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in this application, the drawings used in the description of 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 from these drawings without creative effort.

[0026] Figure 1 This is a schematic diagram of the structure of the organic light-emitting display panel of this application.

[0027] Figure 2 yes Figure 1 A schematic diagram of the first structure of the light-emitting layer in an organic light-emitting display panel.

[0028] Figure 3 yes Figure 1 A schematic diagram of a second structure of the light-emitting layer in an organic light-emitting display panel.

[0029] Figures 4(a) to 4(e) This is a schematic diagram of some manufacturing steps of the light-emitting layer in the organic light-emitting display panel of this application.

[0030] Figure 5 for Figure 2 A schematic diagram of the energy level difference between the host material layer and the guest material layer in the luminescent layer.

[0031] Figure 6 for Figure 3 A schematic diagram of the energy level difference between the host material layer and the guest material layer in the luminescent layer.

[0032] Figure 7 This is a schematic diagram of the organic light-emitting display device of this application. Detailed Implementation

[0033] The technical solutions in the present application will be clearly and completely described below with reference to 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 the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0034] In the present application, unless explicitly specified and limited, "on" or "under" of a first feature to a second feature can include that the first and the second features are directly connected, or that the first and the second features are not directly connected but are in contact through another feature between them. Moreover, "on", "above" and "over" of the first feature to the second feature includes that the first feature is directly above and obliquely above the second feature, or only indicates that the first feature is higher than the second feature in horizontal height. "Under", "below" and "underneath" of the first feature to the second feature includes that the first feature is directly below and obliquely below the second feature, or only indicates that the first feature is lower than the second feature in horizontal height. In addition, the terms "first", "second" are only for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined with "first", "second" can explicitly or implicitly include one or more features.

[0035] The present application provides an organic light emitting display panel and an organic light emitting display device. The organic light emitting display panel comprises a substrate and a light emitting layer disposed on the substrate. The light emitting layer comprises at least two light emitting units stacked, the light emitting unit comprising a first light emitting sub-layer, a second light emitting sub-layer and a third light emitting sub-layer, the third light emitting sub-layer being disposed between the first light emitting sub-layer and the second light emitting sub-layer, the first light emitting sub-layer and the second light emitting sub-layer being one of a host material layer and a guest material layer, and the third light emitting sub-layer being the other of the host material layer and the guest material layer.

[0036] In the prior art single-layer doped light emitting layer, the host material and the guest material are uniformly mixed together. During the operation of the doped light emitting layer, the concentration of excitons is too high, the exciton recombination region is concentrated, causing serious exciton quenching, thereby reducing the service life of the device. In the organic light emitting display device of the present application, the light emitting layer in the device is formed by adopting a plurality of light emitting units stacked, the structure of each light emitting unit is that one guest material layer is sandwiched between two host material layers or one host material layer is sandwiched between two guest material layers. In each light emitting unit, the exciton recombination region is formed only at the interface between the host material layer and the guest material layer, a plurality of dispersed exciton recombination regions are formed in the light emitting layer, the concentration of excitons in the recombination region is reduced, exciton quenching and thermal radiation are reduced, and the service life is effectively prolonged. On the other hand, due to the reduction of exciton quenching, the light emitting efficiency of the device is also improved.

[0037] Hereinafter, the embodiments of the present application will be described with reference to the accompanying drawings.

[0038] Please refer to Figure 1 The organic light-emitting display panel 100 includes a substrate S and an organic light-emitting display device D disposed on the substrate S.

[0039] According to the driving type, the organic light-emitting display panel 100 can be an active matrix organic light-emitting diode (AMOLED) display panel or a passive matrix organic light-emitting diode (PMOLED) display panel. It should be noted that although not shown, a driving circuit layer for driving the organic light-emitting display device D to emit light is further disposed between the substrate S and the organic light-emitting display device D of the organic light-emitting display panel 100, and the driving circuit layer includes an active matrix driving circuit or a passive matrix driving circuit. In addition, the organic light-emitting display panel 100 further includes a pixel definition layer and an encapsulation layer and other functional structures not shown.

[0040] The organic light-emitting display panel 100 can be a rigid display panel or a flexible display panel. According to the type thereof, the substrate S of the organic light-emitting display panel 100 can be glass, plastic, or a flexible substrate S. The flexible substrate can include two flexible substrates and a barrier layer disposed between the two flexible substrates. The materials of the two flexible substrates are independently selected from one of polyimide (PI), polyethylene naphthalate (PEN), polyethylene terephthalate (PET), polyarylate (PAR), polycarbonate (PC), polyetherimide (PEI), and polyethersulfone (PES). The material of the barrier layer can be selected from inorganic materials such as silicon oxide (SiOx), silicon nitride (SiNx), silicon oxynitride (SiON) and a stack thereof, for preventing water vapor from diffusing from the flexible substrate to the driving circuit layer. Optionally, the substrate S of the present embodiment is glass.

[0041] The organic light-emitting display device D includes a first electrode 10, a second electrode 20, and a light-emitting layer 30. The first electrode 10 is disposed on the substrate S. The second electrode 20 is disposed on the side of the first electrode 10 away from the substrate S and is disposed opposite to the first electrode 10.

[0042] Optionally, the first electrode 10 is an anode, which can be a transparent or non-transparent electrode. The anode can include a metal and / or a metal oxide. The metal can be aluminum, gold, silver, or the like. The metal oxide can be indium tin oxide, tin oxide, or the like. The second electrode 20 is a cathode, which can be a transparent or non-transparent electrode. The cathode can include a metal and / or a metal oxide. The metal can be a metal with a low work function, such as lithium, magnesium, calcium, strontium, aluminum, or indium, or an alloy of these metals with copper, gold, or silver. The metal oxide can be indium tin oxide, tin oxide, or the like. The organic light-emitting display device D can be a top-emitting OLED (TE OLED) device or a bottom-emitting OLED (BE OLED) device. In the present embodiment, the organic light-emitting display device D is a top-emitting device. The anode is a metal electrode, and the cathode is a transparent electrode.

[0043] It can be understood that, in other embodiments, the organic light-emitting display device D can be an inverted OLED device, i.e., the first electrode 10 is a cathode, and the second electrode 20 is an anode.

[0044] The light-emitting layer 30 is disposed between the first electrode 10 and the second electrode 20. The light-emitting layer 30 includes at least two light-emitting units 31 stacked together. The light-emitting unit 31 includes a first light-emitting sub-layer 311, a second light-emitting sub-layer 312, and a third light-emitting sub-layer 313. The third light-emitting sub-layer 313 is disposed between the first light-emitting sub-layer 311 and the second light-emitting sub-layer 312.

[0045] The first light-emitting sub-layer 311 and the second light-emitting sub-layer 312 are both one of a host material layer and a guest material layer, and the third light-emitting sub-layer 313 is the other of the host material layer and the guest material layer. Specifically, please refer to Figure 2 In one embodiment, the first light-emitting sub-layer 311 and the second light-emitting sub-layer 312 are both host material layers, and the third light-emitting sub-layer 313 is a guest material layer. Taking the light-emitting layer 30 including at least three light-emitting units 31 as an example, in the direction from the first electrode 10 to the second electrode 20, the structure of the light-emitting layer 30 is: host material layer-guest material layer-host material layer-host material layer-guest material layer-host material layer-(intermediate omissions)-host material layer-guest material layer. In this embodiment, the light-emitting material layers in contact between two adjacent light-emitting units 31 are both host material layers. Moreover, the number of host material layers in the light-emitting layer 30 is twice the number of guest material layers.

[0046] Please refer to Figure 3In another embodiment, the first light-emitting sub-layer 311 and the second light-emitting sub-layer 312 are both guest material layers, and the third light-emitting sub-layer 313 is a host material layer. Taking the light-emitting layer 30 including at least three light-emitting units 31 as an example, from the first electrode 10 to the second electrode 20, the structure of the light-emitting layer 30 is: guest material layer-host material layer-guest material layer-guest material layer-host material layer-guest material layer-(intermediate omissions)-guest material layer-host material layer-guest material layer. In this embodiment, the light-emitting material layers in contact between two adjacent light-emitting units 31 are both guest material layers. Moreover, the number of guest material layers in the light-emitting layer 30 is twice the number of host material layers.

[0047] In Figure 2 and Figure 3 embodiments, the exciton recombination region is only formed at the interface between the host material layer and the guest material layer, and since the first light-emitting sub-layer 311 and the second light-emitting sub-layer 312 of two adjacent light-emitting units 31 are both host material layers or both guest material layers, no exciton recombination region is formed between them. Therefore, the adjacent exciton recombination regions (or interfaces) between two adjacent light-emitting units 31 are separated by a first light-emitting sub-layer 311 and a second light-emitting sub-layer 312, and the adjacent exciton recombination regions between two adjacent light-emitting units 31 are pulled apart by two light-emitting sub-layers, thereby further reducing exciton quenching and improving service life.

[0048] Optionally, in each light-emitting unit 31, the first light-emitting sub-layer 311 and the second light-emitting sub-layer 312 are made of the same material, and the thickness of the first light-emitting sub-layer 311 and the second light-emitting sub-layer 312 is substantially equal. Substantially equal means that the first light-emitting sub-layer 311 and the second light-emitting sub-layer 312 can be formed under the same process conditions, parameters and designed thickness, but due to process errors, the thicknesses can be slightly different. Quantitatively, the difference between the thicknesses of the first light-emitting sub-layer 311 and the second light-emitting sub-layer 312 does not exceed 10% of the thickness of the first light-emitting sub-layer 311 or the second light-emitting sub-layer 312. In actual products, the delamination of the light-emitting layer 30 in contact between two adjacent light-emitting units 31 is not obvious, and therefore, the first light-emitting sub-layer 311 and the second light-emitting sub-layer 312 in contact between two adjacent light-emitting units 31 can be regarded as a common light-emitting layer CL. In the case where the thicknesses of the first light-emitting sub-layer 311 and the second light-emitting sub-layer 312 are substantially equal, the thickness of the common light-emitting layer CL between two adjacent light-emitting units 31 is approximately twice the thickness of the first light-emitting sub-layer 311 closest to the first electrode 10 in the light-emitting layer 30 and the second light-emitting sub-layer 312 closest to the second electrode 20 in the light-emitting layer 30 (i.e., the first light-emitting sub-layer 311 and the second light-emitting sub-layer 312 located at the two ends of the light-emitting layer 30, respectively).

[0049] Please refer to Figures 4(a) to 4(e)The reason for this design is that the inventor found that the display device with the multiple light emitting units 31 structure of the present application has the highest production efficiency in the process of evaporation production design. Please refer to Fig. 4(a), when evaporating the light emitting units 31 on the intermediate substrate S1, the intermediate substrate S1 is set in the evaporation chamber and kept stationary. The host material evaporation source SH and the guest material evaporation source SD are fixedly arranged along the direction from left to right in the figure, at the left side of the intermediate substrate S1, and start to evaporate the host material HM and the guest material DM on the intermediate substrate S1 from left to right. Please refer to Fig. 4(b), when passing under the intermediate substrate S1 for the first time, a layer of host material HM is evaporated first, and then a layer of guest material DM is evaporated on the evaporated host material HM. Please refer to Fig. 4(c), when the host material evaporation source SH and the guest material evaporation source SD move to the right side of the intermediate substrate S1, a layer of host material HM and a layer of guest material DM are formed on the intermediate substrate S1. Then, please refer to Fig. 4(d), the host material evaporation source SH and the guest material evaporation source SD start to return to the starting point from right to left, passing under the intermediate substrate S1 to evaporate the guest material DM and the host material HM on the intermediate substrate S1. When passing under the intermediate substrate S1 for the second time, a layer of guest material DM is evaporated first on the guest material DM formed by the first evaporation, and then a layer of host material HM is evaporated on the evaporated guest material DM. Please refer to Fig. 4(e), when the host material evaporation source SH and the guest material evaporation source SD return to the left side of the intermediate substrate S1, the following structure is formed on the intermediate substrate S1: host material layer-guest material layer-guest material layer-host material layer, i.e., Figure 3 the structure of the light emitting layer 30 except for the guest material layers at the two ends. The host material evaporation source SH and the guest material evaporation source SD can obtain the above structure by running one round, and by continuously and uninterruptedly running the host material evaporation source SH and the guest material evaporation source SD multiple times, the multiple light emitting units 31 in the light emitting layer 30 of the present application: guest material layer-host material layer-guest material layer can be obtained. In this process, without adjusting any execution parameters, neither stopping the movement of the host material evaporation source SH and the guest material evaporation source SD, nor resetting the host material evaporation source SH and the guest material evaporation source SD to the left side after moving to the right side each time, can complete the evaporation of the light emitting units 31, save the time required for evaporation, and greatly improve the production capacity. It can be understood that by exchanging the positions of the host material evaporation source SH and the guest material evaporation source SD, the light emitting units 31 of the present application can be obtained. Figure 3 Figure 2

[0050] ​​It should be noted that in other embodiments of the present application, the materials of the first light-emitting sub-layer 311 and the second light-emitting sub-layer 312 of each light-emitting unit 31 can also be different, and the thicknesses can also be unequal, for example, set to be gradiently changed according to actual needs.

[0051] On the other hand, in the present application, one first light-emitting sub-layer 311 and one second light-emitting sub-layer 312 are arranged between two adjacent light-emitting units 31, and the optical path difference of the light emitted in the exciton recombination region below can be accurately adjusted by adjusting the thicknesses of the first light-emitting sub-layer 311 and the second light-emitting sub-layer 312 between the two adjacent light-emitting units 31. When the optical path difference of the two beams of light reaches an integer multiple of the wavelength, the interference is strengthened, the light extraction efficiency is improved, and the brightness is increased. Moreover, the thickness adjustment of the two adjacent light-emitting layers can be completed in one round of operation of the host material evaporation source SH and the guest material evaporation source SD, which is convenient for accurate control. Optionally, the thicknesses of the adjacent first light-emitting sub-layer 311 and the second light-emitting sub-layer 312 in the two adjacent light-emitting units 31 are the same. Optionally, the thicknesses of the adjacent first light-emitting sub-layer 311 and the second light-emitting sub-layer 312 in the two adjacent light-emitting units 31 are different, so as to finely adjust the optical path difference of the light by forming two film layers with different thicknesses.

[0052] Optionally, in order to ensure the microcavity effect and the host-guest ratio, the adjacent first light-emitting sub-layer 311 and the second light-emitting sub-layer 312 in the two adjacent light-emitting units 31 are both host material layers, and the sum of the thicknesses of the adjacent first light-emitting sub-layer 311 and the second light-emitting sub-layer 312 is greater than or equal to For example, in the embodiment of Figure 2 , the thickness of the common light-emitting layer CL is greater than or equal to

[0053] Optionally, the adjacent first light-emitting sub-layer 311 and the second light-emitting sub-layer 312 in the two adjacent light-emitting units 31 are both guest material layers, and the sum of the thicknesses of the adjacent first light-emitting sub-layer 311 and the second light-emitting sub-layer 312 is greater than or equal to For example, in the embodiment of Figure 3 , the thickness of the common light-emitting layer CL is greater than or equal to

[0054] Optionally, the guest material layer is a phosphor material layer or a fluorescent material layer. That is, the structure of the light-emitting layer of the present application can be used for phosphor light-emitting materials and fluorescent light-emitting materials, and both can improve the service life and light-emitting efficiency of the device.

[0055] Optionally, the guest material layer is a blue phosphor material layer. The structure of the light-emitting layer of the present application is particularly suitable for blue phosphor light-emitting materials. The reason is that the current OLED display screen is composed of red, green and blue (RGB) pixels. Among them, the light-emitting efficiency of the blue pixel has the greatest impact on the power consumption of the OLED display screen. The light-emitting guest in the red and green light-emitting layer is a phosphor material, and the theoretical internal quantum efficiency (IQE) is 100%. However, the light-emitting guest in the blue light-emitting layer is a fluorescent material, and the theoretical internal quantum efficiency is only 25%. Based on the light-emitting principle and internal quantum efficiency, the light-emitting efficiency of the fluorescent material is lower than that of the phosphor material. However, the blue phosphor material cannot be applied to mass production due to its short lifetime. By forming the blue phosphor host material and the guest material into the light-emitting unit 31 of the present application and stacking multiple light-emitting units 31 to form a light-emitting layer, multiple dispersed exciton recombination regions are formed in the light-emitting layer, the concentration of excitons in the recombination region is reduced, exciton quenching and thermal radiation are reduced, and the lifetime of the blue phosphor light-emitting material is effectively prolonged. The improvement of the lifetime of the blue phosphor light-emitting material can promote the use of the blue phosphor material to replace the blue fluorescent material in the mass production of organic light-emitting display devices D.

[0056] It should be noted that the host material layer and the guest material layer can also be other colors, such as red, green, yellow, white phosphor light-emitting layers or fluorescent light-emitting layers. The present application does not limit this.

[0057] Optionally, the thickness of each light-emitting unit 31 is greater than or equal to 2 nm. In each light-emitting unit 31, the thickness ratio of the guest material layer to the host material layer is less than or equal to 0.25. Specifically, the thickness of the guest material layer is m, and the thickness of the host material layer is L, then 0 < m / L ≤ 0.25. If m / L is greater than 0.25, the thickness of the guest material layer is too thick, the light-emitting layer can be regarded as a pure light-emitting material layer, the exciton quenching is serious, and the light-emitting efficiency is low. By making the thickness ratio of the guest material layer to the host material layer less than or equal to 0.25, a higher light-emitting efficiency can be ensured.

[0058] Optionally, the light-emitting layer includes 2 to 10 light-emitting units 31. Since the total thickness of the light-emitting layer is in the range of to If the number of light-emitting units 31 is too large, the thickness of the single-layer light-emitting layer 30 is too thin, which will shorten the service life of the light-emitting layer. Therefore, the number of light-emitting units 31 cannot be too large.

[0059] Optionally, the thickness of the light-emitting layer 30 is in the range of to The greater the thickness of the light-emitting layer 30, the greater the driving voltage, and the thinner the light-emitting layer 30, the shorter the service life. When the thickness of the light-emitting layer 30 is in the range of to At this time, a relatively appropriate driving voltage and service life can be obtained. Alternatively, refer to Figure 5 and Figure 6 , Figure 5 and Figure 6 In the formula, n represents the number of the light emitting units 31. The LUMO (Lowest Unoccupied Molecular Orbital) energy level of the host material of the host material layer and the LUMO energy level of the guest material of the guest material layer have an energy level difference ΔE1 greater than 0 and less than or equal to 0.3 eV; and / or, the HOMO (Highest Occupied Molecular Orbital) energy level of the guest material of the guest material layer and the HOMO energy level of the host material of the host material layer have an energy level difference ΔE2 greater than 0 and less than or equal to 0.3 eV. Specifically, the HOMO energy level of the guest material is greater than the HOMO energy level of the host material layer, and the LUMO energy level of the host material is greater than the LUMO energy level of the guest material layer. However, the HOMO energy level difference and the LUMO energy level difference of the host material and the guest material are set to be less than or equal to 0.3 eV, and the smaller the energy level difference, the more easily the holes and the electrons can jump between the light emitting units 31, and the holes and the electrons can pass between the adjacent light emitting units 31 and recombine, thereby improving the light emitting efficiency. It should be noted that the host material layer can include one or more than one host material, and the guest material layer can also include one or more than one guest material, and the energy level relationship between each host material and each guest material meets the above energy level difference requirements.

[0060] Alternatively, in a specific embodiment, the host material layer includes at least one blue fluorescent or blue phosphorescent host material, and the mass percentage of each host material is greater than or equal to 10%, so as to balance the carrier concentration. Further, the hole mobility of each host material is greater than 10 -3 cm 2 *V -1 *S -1 , and the electron mobility is greater than 10 -5 cm 2 *V -1 *S -1 . The guest material layer is composed of one guest material, which is a blue fluorescent or blue phosphorescent light emitting material, the wavelength of the light emitting peak of the guest material is between 450 nm and 475 nm, the half-peak width of the guest material is less than or equal to 35 nm, and the film-state light emitting quantum yield of the guest material is greater than or equal to 60%.

[0061] Alternatively, refer to Figure 1The organic light emitting display panel 100 further includes a hole injection layer 40 and a hole transport layer 50 which are sequentially stacked between the first electrode 10 and the light emitting layer 30, and an electron injection layer 60 and an electron transport layer 70 which are sequentially stacked between the second electrode 20 and the light emitting layer 30. The hole injection layer 40 can include a p-type dopant. The hole injection layer 40 can include HATCN. The hole transport layer 50 can include NPB. The electron injection layer 60 can be LiQ. The electron transport layer 70 can include TPBI and LiQ. The electron injection layer 60.

[0062] Further, the organic light emitting display panel 100 further includes an electron blocking layer 80 disposed between the hole transport layer 50 and the light emitting layer 30, and a hole blocking layer 90 disposed between the electron transport layer 70 and the light emitting layer 30. The electron blocking layer 80 can include an electron blocking material or an exciton blocking material. The hole blocking layer 90 includes a hole blocking material or an exciton blocking material.

[0063] Please refer to Figure 7 The present application also provides an organic light emitting display device 1. The organic light emitting display device 1 in the embodiments of the present application can be a mobile phone, a tablet computer, an electronic reader, an electronic display screen, a notebook computer, a mobile phone, an augmented reality (AR) / virtual reality (VR) device, a media player, a wearable device, a digital camera, a car navigation device, etc. The organic light emitting display device 1 includes a processor 200 and the organic light emitting display panel 100 provided by the present application, and the organic light emitting display panel 100 is connected to the processor 200. The processor 200 can include a driving chip or the like which drives the organic light emitting display panel 100 to emit light.

[0064] In the following, the organic light emitting device of the present application will be described in conjunction with specific embodiments.

[0065] Embodiment 1

[0066] An organic light-emitting display device was prepared according to the method disclosed in reference Xiang et al., Acceptor plane expansion enhances horizontal orientation of thermally activated delayed fluorescence emitters, Sci. Adv. 2020; Vol 6, Issue 41, DOI: 10.1126 / sciadv.aba7855. Specifically, a glass was used as a substrate, and ITO was used as an anode. In a high vacuum condition, a hole injection layer, a hole transport layer, a light-emitting layer, an electron transport layer, an electron injection layer, and a cathode were sequentially vapor-deposited on a cleaned conductive glass (ITO) substrate. The hole injection layer was 10 nm of HATCN, the hole transport layer was 100 nm of NPB, and the light-emitting layer used a light-emitting unit 31 structure of a host material layer-guest material layer-host material layer. The total thickness of the light-emitting layer was 20 nm, the thickness L of the host material layer in contact with the hole transport layer was 2.25 nm, the thickness m of the guest material layer was 0.5 nm, and the number of repeating units was 4. The electron transport layer was vapor-deposited by TPBI and LiQ at a ratio of 1:1, and the thickness was 30 nm. The electron injection layer was 1 nm of LiQ. The cathode was 100 nm of Al. The device structure can be represented as: glass / ITO / HATCN (10 nm) / NPB (100 nm) / light-emitting layer (2.25 nm) / TPBI+LiQ (30 nm) / LiQ (1 nm) / Al (100 nm). The structures of the materials in each layer can be referred to the following chemical formula. The luminescent properties of the prepared device were recorded under a current density of 10 mA / cm 2 .

[0067]

[0068] Comparative Example 1

[0069] Except that the light-emitting layer with a total thickness of 20 nm was co-vapor-deposited by the guest material and the host material at a thickness ratio of 20:180 to form a light-emitting layer with a total thickness of 20 nm, the materials and parameters of other structures were the same as those in Example 1. The luminescent properties of the prepared device were recorded under a current density of 10 mA / cm 2 .

[0070] The experimental results of Example 1 and Comparative Example 1 are as follows:

[0071] Table 1 Comparison of performance parameters of Example 1 and Comparative Example 1

[0072]

[0073] The lifetime of the organic light emitting material is usually tested by measuring the curve of the luminance changing with time after a certain constant current is applied to the OLED device, and then we distinguish the lifetime according to the target value of the luminance reduction. The time from the initial luminance (100%) to 95% is called LT95. Compared with Comparative Example 1, the maximum external quantum efficiency of Example 1 using the device structure of the present application is increased by 35.7% compared with Comparative Example 1, and the service life of the device is more than doubled according to the LT95 standard.

[0074] The above provides a detailed description of the embodiments of the present application, and the principles and embodiments of the present application are described by applying specific examples. The above description of the embodiments is only used to help understand the present application. Meanwhile, for those skilled in the art, the specific embodiments and application scope will be changed according to the idea of the present application. In summary, the content of the description should not be understood as a limitation of the present application.

Claims

1. An organic light-emitting display panel, characterized in that, include: substrate; A first electrode is disposed on the substrate; The second electrode is disposed on the side of the first electrode away from the substrate and is disposed opposite to the first electrode; as well as A light-emitting layer is disposed between the first electrode and the second electrode. The light-emitting layer includes at least two light-emitting units stacked together. Each light-emitting unit includes a first light-emitting sub-layer, a second light-emitting sub-layer, and a third light-emitting sub-layer. The third light-emitting sub-layer is disposed between the first light-emitting sub-layer and the second light-emitting sub-layer. Wherein, the first light-emitting sublayer and the second light-emitting sublayer are both one of the host material layer and the guest material layer, and the third light-emitting sublayer is the other of the host material layer and the guest material layer; In each of the light-emitting units, the first light-emitting sublayer and the second light-emitting sublayer are made of the same material, and the thickness difference does not exceed 5 Å; In two adjacent light-emitting units, the adjacent first light-emitting sublayer and the adjacent second light-emitting sublayer are both main material layers, and the sum of the thicknesses of the adjacent first light-emitting sublayer and the adjacent second light-emitting sublayer is greater than or equal to 15 Å; or In two adjacent light-emitting units, the adjacent first light-emitting sublayer and the adjacent second light-emitting sublayer are both guest material layers, and the sum of the thicknesses of the adjacent first light-emitting sublayer and the adjacent second light-emitting sublayer is greater than or equal to 3 Å.

2. The organic light-emitting display panel as described in claim 1, characterized in that, In two adjacent light-emitting units, the thickness of the adjacent first light-emitting sub-layer and the second light-emitting sub-layer is the same.

3. The organic light-emitting display panel as described in claim 1, characterized in that, In two adjacent light-emitting units, the thicknesses of the adjacent first light-emitting sub-layer and the second light-emitting sub-layer are different.

4. The organic light-emitting display panel as described in claim 1, characterized in that, The thickness ratio of the object material layer to the body material layer is less than or equal to 0.

25.

5. The organic light-emitting display panel as described in claim 4, characterized in that, The thickness of the light-emitting unit is greater than or equal to 2 nm, and the light-emitting layer includes 2 to 10 light-emitting units.

6. The organic light-emitting display panel as described in claim 4, characterized in that, The thickness of the light-emitting layer ranges from 150 Å to 250 Å.

7. The organic light-emitting display panel as described in claim 1, characterized in that, The energy level difference between the lowest unoccupied molecular orbital energy level of the host material in the host material layer and the lowest unoccupied molecular orbital energy level of the guest material in the guest material layer is greater than 0 and less than or equal to 0.3 eV; And / or, The energy level difference between the highest occupied molecular orbital energy level of the guest material in the guest material layer and the highest occupied molecular orbital energy level of the host material in the host material layer is greater than 0 and less than or equal to 0.3 eV.

8. The organic light-emitting display panel as described in claim 1, characterized in that, The guest material layers are either all phosphorescent material layers or all fluorescent material layers.

9. The organic light-emitting display panel as described in claim 8, characterized in that, The wavelength of the emission peak of the guest material layer is between 450 nm and 475 nm, the half-width at half maximum (WHM) of the guest material layer is less than or equal to 35 nm, and the quantum yield of the film-state emission of the guest material layer is greater than or equal to 60%.

10. An organic light-emitting display device, characterized in that, It includes a processor and an organic light-emitting display panel as described in any one of claims 1 to 9, wherein the organic light-emitting display panel is electrically connected to the processor.

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