OLED display panel with improved display quality

Abstract

The present disclosure relates to an OLED display panel with improved display quality. The present disclosure achieves the following effects: (1) limiting the refractive index difference of the cover layer (CPL) for red and green (GR) pixel light, reducing the green (G) light extraction ratio; (2) limiting the energy level and mobility relationship of the CPL material, the red light main component, and the green light main component, adjusting the carrier balance of the red and green OLED device, reducing the G light OLED device lifetime, adjusting the red and green OLED device lifetime curve, matching the GR light lifetime trend, and reducing the G light extraction ratio after long-time lighting; (3) limiting the physical property relationship of the CPL material and LiF, reducing the degradation of LiF to the CPL material to avoid local CPL material cracking, reducing the refractive index, and generating black spots, improving the green phenomenon of the OLED white display picture, reducing the dark spot generation, and improving the OLED display quality.

Description

Technical Field

[0001] This disclosure belongs to the field of organic electroluminescent materials technology, and specifically relates to an OLED display panel with improved OLED display image quality. Background Technology

[0002] Organic light-emitting diode (OLED) display panels have advantages such as self-illumination, low energy consumption, high luminous efficiency, fast response speed, wide viewing angle, low driving voltage, high contrast, fast response speed, more realistic color display, easier to achieve thinness and flexibility, and low production cost. They have been widely used in display fields such as mobile phones, automotive displays, camera panels, and computer panels.

[0003] Currently, mass-produced OLED display panels are prone to dark spots, and white images may appear greenish, affecting the display effect. Summary of the Invention

[0004] The inventors have discovered that (1) by limiting the refractive index difference of the capping layer (CPL) for red and green (GR) pixel light, the proportion of green (G) light extraction can be reduced; (2) by limiting the energy level and mobility relationship of the CPL material, the red light main N-type component RH-N, and the green light main N-type component GH-N, the carrier balance of the red and green OLED devices can be adjusted, reducing the lifetime of the G light OLED device, adjusting the downward trend of the lifetime curve of the red and green OLED devices, matching the lifetime trend of GR light, and reducing the proportion of G light extraction after long-term illumination; (3) by limiting the physical property relationship between the CPL material and LiF, the degrading effect of LiF on the CPL material can be reduced. This degrading effect leads to local CPL material decomposition, which in turn leads to a decrease in refractive index and the generation of black spots. Therefore, by taking one or more of the above measures (1), (2), and (3), the phenomenon of green tint in OLED white display can be improved, the generation of dark spots can be reduced, and the image quality of OLED display can be improved.

[0005] One object of this disclosure is to provide an OLED display panel that has improved display quality. In some embodiments, the OLED display panel according to this disclosure improves the greenish tint in OLED white displays. In some embodiments, the OLED display panel according to this disclosure reduces the generation of dark spots. In some embodiments, the OLED display panel according to this disclosure simultaneously possesses both of the aforementioned technical effects.

[0006] Another object of this disclosure is to provide a display device that includes the aforementioned OLED display panel.

[0007] On one hand, this disclosure provides an OLED display panel, comprising a red OLED device, a green OLED device, and a substrate. The red and green OLED devices each include a capping layer, a cathode, and a light-emitting layer, wherein the light-emitting layer, cathode, and capping layer are sequentially arranged in a direction away from the substrate. The peak emission wavelength of the red OLED device is 610-630 nm, and the peak emission wavelength of the green OLED device is 520-540 nm. The capping layer and the light-emitting layer have the following relationship:

[0008] 0.03≤n1(530nm)-n2(620nm)≤0.12 (1)

[0009] Where n1 (530nm) represents the refractive index of the capping layer at 530nm for light emitted by the light-emitting layer of the green OLED device;

[0010] n2(620nm) represents the refractive index of the capping layer at 620nm for the light emitted by the light-emitting layer of the red OLED device.

[0011] Here, the sequential arrangement of the light-emitting layer, cathode, and capping layer along the direction away from the substrate only indicates the order of these three elements. It does not preclude the existence of other layers between these layers, such as hole blocking layer (HBL), electron transport layer (ETL), electron injection layer (EIL), etc.

[0012] In related technologies, the main reason for the green tint in white displays is the difference in refractive index of the capping layer material for BGR light (i.e., the same capping layer material has different refractive indices for light of a specific wavelength corresponding to a BGR sub-pixel), resulting in an increased proportion of green light. In particular, the difference Δn (n1(530nm)-n2(620nm)) between the capping layer's refractive index for green OLED device light emitted by the emitting layer and its refractive index for red OLED device light emitted by the emitting layer is relatively large. Figure 1 As shown, in this situation, the proportion of green light extraction increases, causing the originally white screen to appear greenish. In this disclosure, by limiting Δn(n1(530nm)-n2(620nm)) to the range of 0.03 to 0.12, the proportion of green light extraction can be reduced, thereby reducing the greenish appearance of the white screen.

[0013] Specifically, △n(n1(530nm)-n2(620nm)) can be any value in the range of 0.03 to 0.12 or any subrange thereof, such as 0.03, 0.04, 0.05, 0.06, 0.07, 0.07, 0.09, 0.10, 0.11, 0.12, etc.

[0014] In some embodiments, the capping layer comprises a capping material, the emissive layer of the red OLED device comprises a red-light-dominant N-type component RH-N, and the emissive layer of the green OLED device comprises a green-light-dominant N-type component GH-N, wherein the LUMO energy levels of the capping material, RH-N, and GH-N satisfy the following relationship:

[0015] |LUMO(GH-N)|≤|LUMO(CPL)|≤|LUMO(RH-N)| (2)

[0016] Among them, LUMO(RH-N) is the lowest unoccupied orbital level of RH-N, LUMO(CPL) is the lowest unoccupied orbital level of the capping material, and LUMO(GH-N) is the lowest unoccupied orbital level of GH-N.

[0017] In this disclosure, by setting the LUMO energy level relationship of the capping material, RH-N and GH-N to satisfy the above relationship (2), the proportion of green light extraction can be reduced, thereby reducing the phenomenon of greening of white screen display.

[0018] In some embodiments, the electron mobilities (μe) of RH-N and GH-N further satisfy the following relationship:

[0019] 1≤μe(RH-N) / μe(GH-N)≤100 (3)

[0020] Where μe(GH-N) is the electron mobility of GH-N, and μe(RH-N) is the electron mobility of RH-N.

[0021] Specifically, μe(RH-N) / μe(GH-N) can be any value in the range of 1 to 100 or any subrange thereof, such as 1.5, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, 9.0, 10.0, 15, 20, 30, 40, 50, 60, 70, 80, 90, 95, etc.

[0022] like Figure 2 As shown, according to current research results, when the exciton recombination region is located on the side of the EML layer biased towards the Prime layer, the recombination region is narrow, the energy density is high, the host-guest energy transfer efficiency is high, and the efficiency performance is good. However, when the exciton recombination region is located in the middle of the EML layer, the exciton recombination region is wide, the energy density is low, the degradation effect on organic molecules is weak, and the lifetime performance is good.

[0023] like Figure 1As shown, in related technologies, in green OLED devices, the exciton recombination region is located on the Prime side of the green EML (G-EML) layer, resulting in good green light efficiency; while in red OLED devices, the exciton recombination region is located in the middle of the red EML (R-EML) layer, resulting in moderate red light efficiency. In this invention, by making the electron mobility of RH-N and GH-N satisfy the above relationship (3), the exciton recombination regions of green and red OLED devices can be reversed. This results in the exciton recombination region being located in the middle of the green EML (G-EML) layer in the green OLED device, resulting in moderate green light efficiency; while in the red OLED device, the exciton recombination region is located on the Prime side of the red EML (R-EML) layer, resulting in good red light efficiency. This reduces the proportion of green light extraction, thereby reducing the phenomenon of greening in white screen displays.

[0024] In some embodiments, the OLED display panel according to this disclosure has a LiF layer on the side of the capping layer away from the substrate, wherein the LUMO energy level of the capping layer material and the work function of LiF satisfy the following relationship:

[0025] 0.2eV≤WF(LiF)-|LUMO(CPL)|≤0.7eV (4)

[0026] Where WF(LiF) represents the work function of LiF;

[0027] LUMO (CPL) is the lowest unoccupied orbital energy level of capping material.

[0028] In related technologies, the main reason for the tendency to generate dark spots is that, in current mass production processes, LiF needs to be deposited on the CPL after the capping layer (CPL) material is deposited on the OLED device. On one hand, LiF can adjust the microcavity length and top reflectivity / transmittance. Simultaneously, LiF has a low refractive index for light emitted from the emissive layer, which, combined with the high refractive index of the CPL material, further enhances the light extraction effect. On the other hand, LiF provides a certain degree of UV protection, reducing the degradation of organic materials in the OLED device caused by external UV light.

[0029] However, in related technologies, the work function difference between LiF and the LUMO energy level of the capping material, WF(LiF)-|LUMO(CPL)|, is too small. In this case, due to the inherent instability of LiF, high-energy plasma is generated during CVD preparation. Once this plasma reaches a certain level, it induces interaction between LiF and the adjacent CPL. The F ions released by LiF drift, leading to the degradation of the capping material. This degradation results in a significant decrease in the refractive index of the CPL for light emitted from the emissive layer. Compared to the undegraded areas of the CPL, the light extraction efficiency is greatly reduced, leading to localized dark spots and poor display quality.

[0030] In this disclosure, by setting the LUMO energy level of the capping material and the work function of LiF to satisfy the above relationship (4), the cracking of the capping material caused by LiF can be significantly reduced, thereby avoiding the generation of local dark spots and affecting the display effect.

[0031] Based on the above-mentioned inventive concept, those skilled in the art can select suitable capping material, red light main N-type component RH-N and green light main N-type component GH-N to prepare the OLED display panel according to the present invention.

[0032] In some embodiments, the capping material comprises a structure of formula I, and at least one of the green light host N-type component GH-N and the red light host N-type component RH-N comprises a structure of formula I:

[0033]

[0034] in,

[0035] X is independently selected from CR2 or N;

[0036] Y is selected from O, S, NR3;

[0037] R1, R2, and R3 are independently selected from hydrogen, deuterium, C1-C6 alkyl, C3-C6 cycloalkyl, phenyl, biphenyl, naphthyl, phenanthryl, dibenzofuranyl, dibenzothiophene, dimethylfluorenyl, and diphenylfluorenyl.

[0038] Alternatively, two adjacent R2 atoms can form a ring with the attached carbon atom to form a benzene ring, naphthalene ring, C3-C6 cycloalkane ring, oxazole ring, or thiazole ring.

[0039] Formula (I) is connected to the main structure through one of R1, R2, R3 or two adjacent R2s and a site on the ring formed by the connected carbon atoms.

[0040] In some embodiments,

[0041] R1 is selected from the linking bond and phenyl group;

[0042] X is selected from CR2;

[0043] R2 is selected from linking bonds, hydrogen, and deuterium;

[0044] Alternatively, two adjacent R2 atoms can form a ring with the connected carbon atom to form a benzene ring or a naphthalene ring, wherein the benzene ring or naphthalene ring is connected to the main structure;

[0045] Y is selected from O, S, and NR3;

[0046] R3 is phenyl, biphenyl, naphthyl, phenanthryl, dibenzofuranyl, dibenzothiophene, dimethylfluorenyl, or diphenylfluorenyl.

[0047] In some embodiments, both the green light host N-type component GH-N and the red light host N-type component RH-N contain the structure of Formula I.

[0048] The structure shown in Formula I above belongs to benzoxazole / thiazole / imidazolium and its derivatives, which are characterized by inexpensive raw materials and high synthesis yield. Simultaneously, benzoxazole / thiazole / imidazolium and its derivatives have high polarizability and small size. When used in CPL material molecules, they can significantly increase the refractive index of the CPL material for the light emitted from the emissive layer (high molecular polarizability and small size result in a higher refractive index), preventing the LUMO value of the CPL material from becoming too deep and reducing the degrading effect of LiF on the CPL material. Furthermore, benzoxazole / thiazole / imidazolium and its derivatives possess certain electron transport capabilities. By adjusting the electron mobility of their N-type components in the red and green substrates, the exciton recombination region in the red and green devices can be adjusted as described above, improving carrier balance, adjusting the light emission efficiency and device lifetime curves, achieving a better balance in the red and green light devices, and improving the problem of a greenish tint in the display.

[0049] In some embodiments, the capping material is a compound represented by Formula II:

[0050]

[0051] in,

[0052] L1 is selected from phenylene, biphenylene, naphthylene, dibenzofuranylene, and dibenzothiopheneylene;

[0053] L2 and L3 are independently selected from phenylene, biphenylene, naphthylene, and C1-C3 alkylene;

[0054] n1 and n2 are independently 0 or 1;

[0055] R4 and R5 are independently selected from phenyl and biphenyl;

[0056] R6 and R7 are independently selected from phenyl, biphenyl, and structures of Formula I above; and at least one of R6 and R7 is a structure of Formula I.

[0057] In some embodiments, the capping material is selected from the following materials:

[0058]

[0059] In some embodiments, RH-N is a compound represented by Formula III:

[0060]

[0061] in,

[0062] R8 is selected from phenyl or biphenyl;

[0063] R9 and R 10 Independently selected from: phenyl, biphenyl, terphenyl, and structures of formula I above; wherein R9 and R 10 At least one of them is a structure of formula I.

[0064] In some embodiments, the red light-bearing N-type component RH-N is selected from the following materials:

[0065]

[0066] In some embodiments, GH-N is a compound represented by Formula IV:

[0067]

[0068] in,

[0069] R 11 and R 12 Independently selected from phenyl and biphenyl;

[0070] R 13 This is the structure of Equation I.

[0071] In some embodiments, GH-N is selected from the following materials:

[0072]

[0073] In addition to the components described above, the OLED display panel and its included red OLED device, green OLED device, and substrate according to this disclosure can have conventional compositions. For example, the OLED device may include a first electrode layer (anode), a hole injection layer (HIL), a hole transport layer (HTL), a prime layer, an emissive layer (EML), a hole blocking layer (HBL), an electron transport layer (ETL), an electron injection layer (EIL), a cathode, a capping layer (CPL), a LiF layer, and an encapsulation layer. The display panel may include a TFT substrate, a first electrode layer (anode), a planarization layer, a pixel definition layer, etc. Except for satisfying the relationships described above or using the materials described above, the specific structure, material composition, and fabrication method of the cathode, anode, electron blocking layer, electron transport layer, electron injection layer, hole injection layer, hole transport layer, hole blocking layer, capping layer, LiF layer, encapsulation layer, TFT substrate, planarization layer, pixel definition layer, etc., can adopt any suitable structure, material composition, and fabrication method without particular limitation. This disclosure does not involve improvements to these components; therefore, these components are not described in detail to avoid obscuring the main technical concept of this disclosure.

[0074] On the other hand, this disclosure also provides a display device, including the aforementioned display panel. This display device can be any product or component with a display function, such as a mobile phone, tablet computer, television, monitor, laptop computer, digital photo frame, navigator, smartwatch, fitness wristband, or personal digital assistant. Other essential components of the display device are readily understood by those skilled in the art and will not be described in detail here, nor should they be construed as limiting the invention.

[0075] In this disclosure, the description used "independently" should be interpreted broadly. It can mean that the specific options expressed by the same symbols in different groups do not affect each other, or that the specific options expressed by the same symbols in the same group do not affect each other.

[0076] In this disclosure, the word “including” or variations thereof, such as “comprising,” “containing,” or “having,” will be understood to include the stated elements, integers, or steps, or combinations thereof, but does not preclude the addition of other elements, integers, or steps, or combinations thereof.

[0077] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains. While those similar to or equivalent to the methods and materials described herein may be used in practice or testing of this disclosure, suitable methods and materials are described below. In case of conflict, this specification (including definitions) shall prevail. Furthermore, the materials, methods, and embodiments described are illustrative only and not intended to be limiting.

[0078] "At least one of A, B and C" has the same meaning as "at least one of A, B or C", both including the following combinations of A, B and C: only A, only B, only C, combinations of A and B, combinations of A and C, combinations of B and C, and combinations of A, B and C.

[0079] "A and / or B" includes the following three combinations: A only, B only, and a combination of A and B.

[0080] In this disclosure, unless otherwise stated, "multiple" means two or more. Attached Figure Description

[0081] Figure 1 This is a schematic diagram illustrating the differences between the inventive concept of this disclosure and related technologies.

[0082] Figure 2 This is a schematic diagram showing the effect of the location of the exciton recombination region on efficiency and lifetime.

[0083] Figure 3 This is a diagram showing the display effect of the display panel in Comparison 1. Detailed Implementation

[0084] Example

[0085] To objectively evaluate the technical effects of the embodiments of this disclosure, the technical solutions provided by this disclosure will be described in detail and by way of examples below. These embodiments are provided to make this disclosure more comprehensive and complete, and to fully convey the concept of exemplary embodiments to those skilled in the art. The features, structures, or characteristics described in these exemplary embodiments can be combined in any suitable manner in one or more embodiments, thereby enabling implementation in various forms, and therefore should not be construed as limited to the examples set forth herein. Obviously, the described embodiments are merely some embodiments of this disclosure, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments provided by this disclosure are within the scope of protection of this disclosure.

[0086] The following provides the synthesis process of compounds containing benzo[a]heterocyclic structures according to some exemplary embodiments of this disclosure, as well as the results of testing and comparison of the performance of the prepared electroluminescent devices.

[0087] Example 1

[0088] The display panel comprises a TFT substrate, a first electrode layer (anode), a planarization layer, and a pixel definition layer, which are stacked sequentially. The pixel definition layer can be used to fabricate red, green, and blue (RGB) pixel pits; RGB EL devices are then fabricated sequentially within the RGB pixel pits using a fine metal mask (FMM). After the capping layer (CPL) is deposited, LiF is deposited on top, followed by TFE encapsulation.

[0089] The EL device fabrication process is as follows:

[0090] Blue OLED device fabrication: ITO glass is placed in a vacuum evaporation equipment and HIL, HTL, B', B-EML (BH:BD(1%)), HBL, ETL, EIL, cathode, and CPL1 are deposited sequentially.

[0091] Fabrication of green OLED devices: ITO glass was placed in a vacuum evaporation equipment and HIL, HTL, G', G-EML (GH-P:GH-N1 (6:4):GD (10%)), HBL, ETL, EIL, cathode, and CPL1 were deposited sequentially.

[0092] Red OLED device fabrication: ITO glass is placed in a vacuum evaporation equipment and HIL, HTL, R', R-EML (RH-P:RH-N1(4:6):RD(2%)), HBL, ETL, EIL, cathode, and CPL1 are deposited sequentially.

[0093] Example 2

[0094] Except for the preparation of green and red OLED devices as described below, everything else is the same as in Example 1.

[0095] Fabrication of green OLED devices: ITO glass was placed in a vacuum evaporation equipment and HIL, HTL, G', G-EML (GH-P:GH-N2 (6:4):GD (10%)), HBL, ETL, EIL, cathode, and CPL2 were deposited sequentially.

[0096] Red OLED device fabrication: ITO glass is placed in a vacuum evaporation equipment and HIL, HTL, R', R-EML (RH-P:RH-N2(4:6):RD(2%)), HBL, ETL, EIL, cathode, and CPL2 are deposited sequentially.

[0097] Example 3

[0098] Except for the preparation of green and red OLED devices as described below, everything else is the same as in Example 1.

[0099] Fabrication of green OLED devices: ITO glass is placed in a vacuum evaporation equipment and HIL, HTL, G', G-EML (GH-P:GH-N3 (6:4):GD (10%)), HBL, ETL, EIL, cathode, and CPL3 are deposited sequentially.

[0100] Red OLED device fabrication: ITO glass is placed in a vacuum evaporation equipment and HIL, HTL, R', R-EML (RH-P:RH-N3(4:6):RD(2%)), HBL, ETL, EIL, cathode, and CPL3 are deposited sequentially.

[0101] Comparative Example 1

[0102] Except for the preparation of green and red OLED devices as described below, everything else is the same as in Example 1.

[0103] Fabrication of green OLED devices: ITO glass is placed in a vacuum evaporation equipment and HIL, HTL, G', G-EML (GH-P:GH-N4 (6:4):GD (10%)), HBL, ETL, EIL, cathode, and CPL4 are deposited sequentially.

[0104] Red OLED device fabrication: ITO glass is placed in a vacuum evaporation equipment and HIL, HTL, R', R-EML (RH-P:RH-N4(4:6):RD(2%)), HBL, ETL, EIL, cathode, and CPL4 are deposited sequentially.

[0105] The molecular formulas of the materials used in the above embodiments are as follows:

[0106]

[0107]

[0108]

[0109]

[0110]

[0111] The physical property data of the RH-N, GH-N and CPL materials used in the above embodiments are shown in Table 1 below.

[0112] Table 1. Material property data

[0113] HOMO / eV LUMO / eV μe@5000 electric field T1 / eV n1 (530nm) n2 (620nm) RH-N1 5.91 2.81 <![CDATA[8.1x10 -5 ]]> 2.21 - - RH-N2 5.88 2.79 <![CDATA[9.6x10 -5 ]]> 2.20 - - RH-N3 5.86 2.77 <![CDATA[9.1x10 -5 ]]> 2.22 - - RH-N4 5.81 2.72 <![CDATA[4.2x10 -6 ]]> 2.18 - - GH-N1 5.88 2.50 <![CDATA[4.6x10 -5 ]]> 2.36 - - GH-N2 5.86 2.54 <![CDATA[3.6x10 -5 ]]> 2.38 - - GH-N3 5.85 2.52 <![CDATA[5.4x10 -5 ]]> 2.38 - - GH-N4 5.81 2.62 <![CDATA[7.1x10 -6 ]]> 2.32 - - CPL1 5.35 2.58 - - 1.82 1.77 CPL2 5.36 2.60 - - 1.88 1.81 CPL3 5.38 2.62 - - 1.92 1.85 CPL4 5.64 2.91 - - 1.92 1.79

[0114] Calculate the difference Δn (n1(530nm)-n2(620nm)) between the refractive index of the capping layer for light emitted from the green OLED device and the refractive index of the capping layer for light emitted from the red OLED device. Compare the LUMO energy levels of CPL, RH-N, and GH-N materials, the electron mobility (μe) of RH-N and GH-N, and the LUMO energy level of CPL material with the work function of LiF (2.9eV) to determine whether they satisfy relationships (1), (2), (3), and (4):

[0115] 0.03≤n1(530nm)-n2(620nm)≤0.12 (1)

[0116] |LUMO(GH-N)|≤|LUMO(CPL)|≤|LUMO(RH-N)| (2)

[0117] 1≤μe(RH-N) / μe(GH-N)≤100 (3)

[0118] 0.2eV≤WF(LiF)-|LUMO(CPL)|≤0.7eV (4)

[0119] The definitions of each symbol are the same as those described above.

[0120] The results are shown in Table 2 below.

[0121] Table 2: Summary of the performance relationships of CPL materials, RH-N and GH-N

[0122] CPL Δn RH-N GH-N Satisfy (1) Satisfy (2) Satisfy (3) Satisfy (4) Example 1 CPL1 0.05 RH-N1 GH-N1 yes yes yes yes Example 2 CPL2 0.07 RH-N2 GH-N2 yes yes yes yes Example 3 CPL3 0.07 RH-N3 GH-N3 yes yes yes yes Comparative Example 1 CPL4 0.13 RH-N4 GH-N4 no no no no

[0123] Performance tests were performed on the display panels prepared in the above embodiments and comparative examples. The tests were conducted using an IVL (I: current; V: voltage; L: brightness) device at a fixed current density of 15 mA / cm². 2 The following test was conducted, and the results are shown in Table 3 below.

[0124] Table 3. Device IVL Data

[0125]

[0126] Where WCIEx: x-coordinate value of white light color coordinates; WCIEy: y-coordinate value of white light color coordinates; WEff: current efficiency value of white light. Dark spot area ratio = dark spot area / total luminous area, indicating the number of dark spots on the luminous area.

[0127] As shown in Table 3, the material combination that meets the requirements of this disclosure can achieve a red light ratio of approximately 1:2 to green light ratio in white light, while the red light ratio of the comparative example that does not meet the requirements of this disclosure is <1:2. This results in an excessively high green light ratio, causing the image to appear greenish. Furthermore, the absolute value of the LUMO of the CPL4 material in the comparative example is close to the work function of LiF. This leads to the generation of high-energy plasma during the CVD preparation of LiF. Once this plasma reaches a certain level, it induces an interaction between LiF and adjacent CPL materials. The F ions released by LiF will drift, causing the CPL material to decompose and producing dark spots, such as… Figure 3 As shown.

[0128] While this disclosure has been described above, the content is merely an embodiment for the purpose of understanding this disclosure and is not intended to limit this disclosure. Any person skilled in the art may make any modifications and changes in the form and details of the implementation without departing from the spirit and scope disclosed herein, but the scope of patent protection of this disclosure shall still be determined by the scope defined in the appended claims.

Claims

1. An OLED display panel, comprising a red OLED device, a green OLED device and a substrate substrate, the red OLED device and the green OLED device comprising a cover layer, a cathode and an emission layer, wherein, The light-emitting layer, the cathode and the cover layer are sequentially arranged in a direction away from the substrate, the red OLED device emits light with a wavelength peak of 610-630 nm, and the green OLED device emits light with a wavelength peak of 520-540 nm, characterized in that the cover layer and the light-emitting layer satisfy the following relationship: 0.03≤n1(530nm)-n2(620nm)≤0.12 (1) wherein n1(530nm) represents the refractive index of the cover layer to the light emitted by the light-emitting layer of the green OLED device at 530 nm; n2(620nm) represents the refractive index of the cover layer to the light emitted by the light-emitting layer of the red OLED device at 620 nm, and the cover layer comprises a cover layer material, the light-emitting layer of the red OLED device comprises a red light host N-type component RH-N, and the light-emitting layer of the green OLED device comprises a green light host N-type component GH-N, wherein the LUMO energy level of the cover layer material, RH-N and GH-N satisfies the following relationship: |LUMO(GH-N)|≤|LUMO(CPL)|≤|LUMO(RH-N)| (2) wherein LUMO(RH-N) is the lowest unoccupied orbital energy level of RH-N, LUMO(CPL) is the lowest unoccupied orbital energy level of the cover layer material, and LUMO(GH-N) is the lowest unoccupied orbital energy level of GH-N.

2. The OLED display panel of claim 1, wherein, The electron mobility μe of RH-N and GH-N further satisfies the following relationship: 1≤μe(RH-N) / μe(GH-N)≤100 (3) wherein μe(GH-N) is the electron mobility of GH-N, and μe(RH-N) is the electron mobility of RH-N.

3. The OLED display panel of claim 1, wherein, The OLED display panel has a LiF layer on the side of the cover layer away from the substrate, wherein the LUMO energy level of the cover layer material and the work function of LiF satisfy the following relationship: 0.2eV≤WF(LiF)-|LUMO(CPL)|≤0.7eV (4) wherein WF(LiF) represents the work function of LiF; LUMO(CPL) is the lowest unoccupied orbital energy level of the cover layer material.

4. The OLED display panel of claim 1, wherein, The cover layer material comprises a structure of formula I, and at least one of the green light host N-type component GH-N and the red light host N-type component RH-N comprises a structure of formula I: wherein, X is independently selected from CR2 or N; Y is selected from O, S, NR3; R1, R2, R3 are independently selected from hydrogen, deuterium, C1-C6 alkyl, C3-C6 cycloalkyl, phenyl, biphenyl, naphthyl, phenanthryl, dibenzofuranyl, dibenzothiophenyl, dimethylfluorenyl, diphenylfluorenyl; or two adjacent R2s form a ring together with the connected carbon atoms into a benzene ring, a naphthalene ring, a C3-C6 cycloalkane ring, an oxazole ring, a thiazole ring; Formula (I) is connected to the host structure through one of R1, R2, R3 or one site on the ring formed by two adjacent R2s and the connected carbon atoms.

5. The OLED display panel according to claim 4, characterized in that, R1 is selected from a connecting bond, a phenyl group; X is selected from CR2; R2 is selected from a connecting bond, hydrogen, deuterium; or two adjacent R2together with the carbon atoms to which they are attached form a ring that is a phenyl ring, a naphthyl ring, said phenyl or naphthyl ring being attached to the host structure; Y is selected from O, S, NR3; R3is phenyl, biphenyl, naphthyl, phenanthryl, dibenzofuranyl, dibenzothiophenyl, dimethylfluorenyl, or diphenylfluorenyl.

6. The OLED display panel of claim 4, wherein, The green host N-type component GH-N and the red host N-type component RH-N both comprise a structure of Formula I.

7. The OLED display panel according to claim 4 or 5, characterized in that, The capping layer material is a compound of Formula II below: wherein, L1is selected from phenylene, biphenylene, naphthylene, dibenzofuranyl, dibenzothiophenyl; L2and L3are independently selected from phenylene, biphenylene, naphthylene, C1-C3 alkylene; n1and n2are independently 0 or 1; R4, R5are independently selected from phenyl, biphenyl; R6and R7are independently selected from phenyl, biphenyl, a structure of Formula I; and at least one of R6and R7is a structure of Formula I. 8.The OLED display panel of claim 7, wherein, The capping layer material is selected from the following materials:

9. The OLED display panel according to claim 4 or 5, characterized in that, RH-N is a compound of Formula III below: wherein, R8is selected from phenyl, biphenyl; R9and R 10 are independently selected from the group consisting of: phenyl, biphenyl, terphenyl, a structure of Formula I; wherein R9and R 10 at least one is a structure of Formula I.

10. The OLED display panel of claim 9, wherein, RH-N is selected from the following materials:

11. The OLED display panel according to claim 4 or 5, characterized in that, GH-N is a compound of Formula IV below: wherein, R 11 and R 12 is independently selected from phenyl, biphenyl; R 13 is the structure of Formula I.

12. The OLED display panel of claim 11, wherein, GH-N is selected from the following materials:

13. A display device comprising the display panel of any one of claims 1-12.

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