An organic electroluminescent blue light-emitting device, display panel and display device

Abstract

The application discloses an organic electroluminescent blue light-emitting device, a display panel and a display device, and belongs to the technical field of display. The organic electroluminescent blue light-emitting device comprises an anode, a hole transport unit, a light-emitting unit, an electron transport unit and a cathode which are arranged in sequence; the light-emitting unit comprises a blue fluorescent light-emitting layer, a barrier layer and a blue phosphorescent light-emitting layer; one of the blue fluorescent light-emitting layer and the blue phosphorescent light-emitting layer is close to the hole transport unit, and the other is close to the electron transport unit; the blue fluorescent light-emitting layer comprises a blue fluorescent host material and a blue fluorescent guest material, and the emission spectrum half-height width of the blue fluorescent guest material is 20 nm to 30 nm; the blue phosphorescent light-emitting layer comprises a blue phosphorescent host material and a blue phosphorescent guest material, and the emission spectrum half-height width of the blue phosphorescent guest material is 40 nm to 60 nm; and the difference between the half-height widths of the blue phosphorescent guest material and the blue fluorescent guest material is 20 nm to 40 nm. The device can reduce blue light color deviation and improve color deviation under different viewing angles.

Description

Technical Field

[0001] This invention relates to the field of display technology, and in particular to an organic electroluminescent blue light-emitting device, a display panel, and a display apparatus. Background Technology

[0002] Organic light-emitting diode (OLED) display panels use three primary colors to achieve color display. They include red sub-pixels, green sub-pixels, and blue sub-pixels, which emit red light (R), green light (G), and blue light (B) respectively and are mixed according to a certain brightness ratio to synthesize different colors of light.

[0003] As the viewing angle changes, the color of the light emitted by different sub-pixels also changes. In particular, the color change of the blue light emitted by the blue sub-pixel is significantly greater than that of the red and green light, exhibiting a large color shift. This leads to excessive blue light shift within a certain viewing angle range, resulting in an imbalance of the white image. Summary of the Invention

[0004] In view of this, the present invention provides an organic electroluminescent blue light-emitting device, a display panel, and a display device, which can solve the technical problems existing in the related art.

[0005] Specifically, the following technical solutions are included:

[0006] On the one hand, an organic electroluminescent blue light-emitting device is provided, the organic electroluminescent blue light-emitting device comprising: an anode, a hole transport unit, a light-emitting unit, an electron transport unit and a cathode arranged in sequence;

[0007] The light-emitting unit includes a blue fluorescent light-emitting layer, a partition layer, and a blue phosphorescent light-emitting layer arranged in sequence. One of the blue fluorescent light-emitting layer and the blue phosphorescent light-emitting layer is close to the hole transport unit, and the other is close to the electron transport unit.

[0008] The blue fluorescent emitting layer comprises a blue fluorescent host material and a blue fluorescent guest material, wherein the emission spectrum of the blue fluorescent guest material has a full width at half maximum (FWHM) of 20 nm to 30 nm.

[0009] The blue phosphorescent emitting layer comprises a blue phosphorescent host material and a blue phosphorescent guest material, wherein the emission spectrum of the blue phosphorescent guest material has a full width at half maximum (FWHM) of 40 nm to 60 nm.

[0010] The difference between the full width at half maximum (FWHM) of the emission spectrum of the blue phosphorescent guest material and the full width at half maximum (FWHM) of the emission spectrum of the blue fluorescent guest material is 20 nm to 40 nm.

[0011] In some possible implementations, the chemical structural formula of the blue fluorescent guest material is shown below:

[0012]

[0013] A is directly attached to the six-membered heterocycle BN. A is a substituted or unsubstituted C6-C60 aryl or cycloalkyl group, a C10-C60 fused aryl group, or a C2-C60 five- or six-membered aromatic heterocyclic group.

[0014] R1, R2, R3, and R4 are each independently hydrogen, deuterium, halogen, nitro, nitrile, substituted or unsubstituted C1-C30 alkyl, substituted or unsubstituted C2-C30 alkenyl, substituted or unsubstituted C1-C30 alkoxy, substituted or unsubstituted C1-C30 thioether, substituted or unsubstituted C6-C50 aryl, or C2-C50 heteroaryl formed from a substituted or unsubstituted C2-C9 ring structure, or substituted or unsubstituted C6-C30 cycloalkyl.

[0015] In some possible implementations, the blue phosphorescent guest material is an iridium complex or a platinum complex.

[0016] In some possible implementations, the separator includes an electron transport material layer.

[0017] In some possible implementations, the material of the interlayer is a benzimidazole derivative, an imidazopyridine derivative, a benzimidazolephenanthridine derivative, a pyrimidine derivative, a triazine derivative, a quinoline derivative, an isoquinoline derivative, or a phenanthridine derivative.

[0018] In some possible implementations, the hole transport unit includes at least one of a hole injection layer, a hole transport layer, and an electron blocking layer;

[0019] The electron transport unit includes at least one of an electron injection layer, an electron transport layer, and a hole blocking layer.

[0020] On the other hand, a display panel is provided, the display panel including red sub-pixels, green sub-pixels and blue sub-pixels, each sub-pixel including an anode, a hole transport unit, a light-emitting layer, an electron transport unit and a cathode arranged in sequence;

[0021] The blue sub-pixel employs any of the aforementioned organic electroluminescent blue light-emitting devices.

[0022] In some possible implementations, the red emitting layer of the red sub-pixel includes a red phosphorescent host material and a red phosphorescent guest material, and the green emitting layer of the green sub-pixel includes a green phosphorescent host material and a green phosphorescent guest material.

[0023] The difference in the full width at half maximum (FWHM) of the emission spectra between the green phosphorescent guest material and the red phosphorescent guest material is less than 45 nm;

[0024] The difference in the full width at half maximum (FWHM) of the emission spectra between the green phosphorescent guest material and the blue phosphorescent guest material is less than 35 nm.

[0025] The difference in the full width at half maximum (FWHM) of the emission spectra between the blue phosphorescent guest material and the red phosphorescent guest material is less than 45 nm.

[0026] In some possible implementations, at least one of the red phosphorescent guest material, the green phosphorescent guest material, and the blue phosphorescent guest material is a platinum complex.

[0027] In some possible implementations, the display panel further includes a light extraction layer stacked on the surface of the cathode facing away from the electron transport unit.

[0028] In another aspect, a display device is provided, the display device comprising any of the display panels described above.

[0029] The beneficial effects of the technical solutions provided in the embodiments of the present invention include at least the following:

[0030] The organic electroluminescent blue light-emitting device provided in this embodiment of the invention comprises a blue fluorescent light-emitting layer and a blue phosphorescent light-emitting layer. By setting the full width at half maximum (FWHM) of the emission spectrum of the blue fluorescent guest material to 20 nm to 30 nm and the FWHM of the emission spectrum of the blue phosphorescent guest material to 40 nm to 60 nm, and the difference between the FWHM of the emission spectrum of the blue phosphorescent guest material and the FWHM of the emission spectrum of the blue fluorescent guest material to 20 nm to 40 nm, the emission spectrum of the organic electroluminescent blue light-emitting device can be optimized. When applied to a three-primary-color light-emitting device, it can optimize the overall emission spectrum, thereby reducing the blue light color shift and improving the color shift under different viewing angles. Attached Figure Description

[0031] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0032] Figure 1 A schematic diagram of the structure of an exemplary organic electroluminescent blue light-emitting device provided by the present invention;

[0033] Figure 2The color shift curves of the blue light emitted by the organic electroluminescent blue light-emitting devices of Example 1 and Comparative Example 1 provided for Test Example 2 as a function of viewing angle.

[0034] Figure 3 Color shift curves of red, green and blue light emitted by the display substrates of Example 1 and Comparative Example 1 as a function of viewing angle, provided for Test Example 2.

[0035] Figure 4 The color shift curves of the white light emitted by the display substrates of Example 1 and Comparative Example 1 provided for Test Example 2 are shown as a function of viewing angle.

[0036] The reference numerals in the attached figures represent:

[0037] 100, Anode; 201, Hole injection layer; 202, Hole transport layer; 203, Electron blocking layer; 301, Blue fluorescent luminescent layer; 302, Interlayer; 303, Blue phosphorescent luminescent layer; 401, Hole blocking layer; 402, Electron transport layer; 403, Electron injection layer; 500, Cathode; 600, Light extraction layer.

[0038] The accompanying drawings have illustrated specific embodiments of the invention, which will be described in more detail below. These drawings and descriptions are not intended to limit the scope of the invention in any way, but rather to illustrate the concept of the invention to those skilled in the art through reference to particular embodiments. Detailed Implementation

[0039] The technical solutions of the embodiments of the present invention 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 the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0040] To address the technical problem of excessive blue light shift in organic electroluminescent devices leading to an imbalance in white images, embodiments of this invention provide an organic electroluminescent blue light-emitting device, as shown in the attached figure. Figure 1 As shown, the organic electroluminescent blue light-emitting device includes an anode, a hole transport unit, a light-emitting unit, an electron transport unit, and a cathode arranged in sequence.

[0041] The light-emitting unit includes a blue fluorescent light-emitting layer, a partition layer, and a blue phosphorescent light-emitting layer arranged in sequence. One of the blue fluorescent light-emitting layer and the blue phosphorescent light-emitting layer is close to the hole transport unit, and the other is close to the electron transport unit.

[0042] The blue fluorescent emitting layer comprises a blue fluorescent host material and a blue fluorescent guest material, with the emission spectrum of the blue fluorescent guest material having a full width at half maximum (FWHM) of 20 nm to 30 nm; the blue phosphorescent emitting layer comprises a blue phosphorescent host material and a blue phosphorescent guest material, with the emission spectrum of the blue phosphorescent guest material having a FWHM of 40 nm to 60 nm; and the difference between the FWHM of the emission spectrum of the blue phosphorescent guest material and the FWHM of the emission spectrum of the blue fluorescent guest material is 20 nm to 40 nm.

[0043] As an example, the light-emitting unit includes a blue fluorescent light-emitting layer, a spacer layer, and a blue phosphorescent light-emitting layer arranged in sequence. The blue fluorescent light-emitting layer is close to the hole transport unit, and the blue phosphorescent light-emitting layer is close to the electron transport unit. That is, the anode, hole transport unit, blue fluorescent light-emitting layer, spacer layer, blue phosphorescent light-emitting layer, electron transport unit, and cathode are arranged in sequence.

[0044] As another example, the light-emitting unit includes a blue phosphorescent light-emitting layer, a spacer layer, and a blue fluorescent light-emitting layer arranged in sequence. The blue phosphorescent light-emitting layer is close to the hole transport unit, and the blue fluorescent light-emitting layer is close to the electron transport unit. That is, the anode, hole transport unit, blue phosphorescent light-emitting layer, spacer layer, blue fluorescent light-emitting layer, electron transport unit, and cathode are arranged in sequence.

[0045] The organic electroluminescent blue light-emitting device provided in this embodiment of the invention comprises a blue fluorescent light-emitting layer and a blue phosphorescent light-emitting layer. By setting the full width at half maximum (FWHM) of the emission spectrum of the blue fluorescent guest material to 20 nm to 30 nm and the FWHM of the emission spectrum of the blue phosphorescent guest material to 40 nm to 60 nm, and the difference between the FWHM of the emission spectrum of the blue phosphorescent guest material and the FWHM of the emission spectrum of the blue fluorescent guest material to 20 nm to 40 nm, the emission spectrum of the organic electroluminescent blue light-emitting device can be optimized. When applied to a three-primary-color light-emitting device, it can optimize the overall emission spectrum, thereby reducing the blue light color shift and improving the color shift under different viewing angles.

[0046] Specifically, blue fluorescent materials have a relatively narrow half-width at half-maximum (HWHM) of emission, resulting in relatively large changes in brightness and color with varying viewing angles; however, they also exhibit good lifetime. Blue phosphorescent materials, on the other hand, have a relatively wide HWHM of emission, exhibiting relatively small changes in brightness and color with varying viewing angles; however, they also have shorter lifetimes. This invention, through the synergistic effect of blue fluorescent and blue phosphorescent guest materials with the aforementioned HWHM ranges, optimizes the spectrum, reduces color shift, and facilitates a higher lifetime.

[0047] In some examples, embodiments of the present invention provide an organic electroluminescent blue light-emitting device in which an anode, a hole transport unit, a blue fluorescent light-emitting layer, a separator, a blue phosphorescent light-emitting layer, an electron transport unit, and a cathode are sequentially stacked. In this device structure, the blue phosphorescent light-emitting layer is positioned close to the electron transport unit because the main material of the blue phosphorescent light-emitting layer is typically designed to include both N-type and P-type materials. The content of the N-type material is relatively lower than that of the main material of the blue fluorescent light-emitting layer. By placing the blue phosphorescent light-emitting layer close to the electron transport unit, electron transport is more facilitated, ensuring that the device has both high luminous efficiency and longevity.

[0048] In this embodiment of the invention, the emission spectrum of the blue fluorescent guest material has a full width at half maximum (FWHM) of 20 nm to 30 nm, including but not limited to: 20 nm to 29 nm, 20 nm to 28 nm, 20 nm to 27 nm, 20 nm to 26 nm, 20 nm to 25 nm, 25 nm to 30 nm, 26 nm to 30 nm, 27 nm to 30 nm, 28 nm to 30 nm, 29 nm to 30 nm, etc.

[0049] In some examples, the chemical structural formulas of blue fluorescent guest materials with a full width at half maximum (FWHM) of the emission spectrum described above are shown below:

[0050]

[0051] In this case, A is directly attached to the six-membered heterocycle BN, and A is a substituted or unsubstituted C6-C60 aryl or cycloalkyl, a C10-C60 fused aryl, or a C2-C60 five- or six-membered aromatic heterocyclic group.

[0052] For the aforementioned "C6-C60 aryl groups," C6-C60 represents the number of carbon atoms in the unsubstituted aryl group. When the aryl group has substituents, this does not include the number of carbon atoms in the substituents. Similarly, the number of carbon atoms in other groups is interpreted in the same way.

[0053] For example, aryl groups of C6 to C60 include, but are not limited to: phenyl, biphenyl, terphenyl, naphthyl, phenanthryl, anthracene, triphenylene, fluorenyl, benzofluorenyl, spirodifluorenyl, spiroanthrenefluorenyl, pyrene, and fluoranthyl.

[0054] Cycloalkyl groups of C6 to C60 include, but are not limited to: cyclohexyl, cycloheptyl, cyclopentenyl, cyclohexenyl, adamantyl, norbornelyl, camphenyl, fentanyl, isocamphenyl, etc.

[0055] Examples of the C10-C60 fused aryl groups mentioned above include, but are not limited to: carbazolyl, pyridinyl, pyrimidinyl, pyrazinyl, pyridazinyl, triazinyl, quinolinyl, isoquinolinyl, quinazolinyl, quinoxalinyl, etc.

[0056] The aforementioned five- or six-membered aromatic heterocyclic groups of C2 to C60 refer to monovalent groups in which at least one carbon atom of the aryl group is replaced by a heteroatom, wherein the heteroatom includes, but is not limited to, O, S, N, Si, B, P, etc.

[0057] Examples of heteroaryl groups include, but are not limited to, the following groups: benzofuranyl, naphthofuranyl, phenanthrofuranyl, dibenzofuranyl, benzodibenzofuranyl, benzothiophene, naphthothiophene, phenanthiophene, dibenzothiophene, benzodibenzothiophene, indolyl, naphthoindolyl, carbazoyl, benzocarbazoyl, spirofluorenexanthracene, spirofluorenexanthracene, spirofluorenexanthracene, spirofluorenexanthracene, benzodioxonyl, benzodisulfide, dihydroisobenzofuranyl, dihydrobenzofuranyl, dihydrobenzothiophene, dihydroisobenzothiophene, phenoxazinyl, phenthiazinyl, dihydroacridyl, pyridinyl, pyrazinyl, pyridazinyl, triazinyl, quinolinyl, isoquinolinyl, quinazolinyl, quinoxalinyl, etc.

[0058] R1, R2, R3, and R4 are each independently hydrogen, deuterium, halogen, nitro, nitrile, substituted or unsubstituted C1-C30 alkyl, substituted or unsubstituted C2-C30 alkenyl, substituted or unsubstituted C1-C30 alkoxy, substituted or unsubstituted C1-C30 thioether, substituted or unsubstituted C6-C50 aryl, or C2-C50 heteroaryl formed from a substituted or unsubstituted C2-C9 ring structure, or substituted or unsubstituted C6-C30 cycloalkyl.

[0059] For R4, its position on the benzene ring is not fixed, meaning it can be attached to any of the corresponding optional sites on the benzene ring.

[0060] For the C1-C30 alkyl groups involved in R1, R2, R3, and R4, they refer to hydrocarbon groups formed by removing one hydrogen atom from an alkane molecule. The alkyl group can be a straight-chain alkyl group or a branched-chain alkyl group. When the chain alkyl group described in this invention has three or more carbon atoms, it includes its isomers; for example, propyl includes n-propyl and isopropyl; butyl includes n-butyl, isobutyl, sec-butyl, tert-butyl, and so on. Examples of alkyl groups include, but are not limited to, the following groups: methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, etc.

[0061] Examples of alkenyl groups include, but are not limited to, the following groups: vinyl, propenyl, butenyl, pentenyl, hexenyl, heptenyl, octenyl, etc.

[0062] Examples of aryl, heteroaryl, and cycloalkyl groups can be found in the examples of aryl, heteroaryl, and cycloalkyl groups in ring A above, and will not be repeated here.

[0063] It should be noted that, in the above description, "substitution" means that the hydrogen atom bonded to the carbon atom of the compound becomes another substituent, and there are no restrictions on the position of substitution, as long as the position is where the hydrogen atom is substituted (i.e., the position where the substituent can substitute). Furthermore, when two or more substituents are substituted, the two or more substituents can be the same as or different from each other. The substituent group includes, but is not limited to, alkyl groups from C1 to C30, such as methyl, ethyl, isopropyl, tert-butyl, etc.

[0064] In this embodiment of the invention, the blue fluorescent emitting layer comprises a blue fluorescent host material and a blue fluorescent guest material. Some suitable blue fluorescent host materials may be anthracene derivatives, fluorene derivatives, perylene derivatives, or styrylamine derivatives. Further examples include, but are not limited to, 9-(4-naphthyl-1-yl-phenyl)-10-phenyl-anthracene, 1,6-diamine, 9,10-di-(2-naphthyl)anthracene (ADN), 2-methyl-9,10-di-2-naphthylanthracene (MADN), 2,5,8,11-tetra-tert-butylperylene (TBPe), 4,4'-bis[4-(diphenylamino)styryl]biphenyl (BDAVBi), and 4,4'-bis[4-(di-p-tolylamino)styryl]biphenyl (DPAVBi). The blue fluorescent host material may be selected from one or more of these materials.

[0065] In some examples, for the blue fluorescent emitting layer composed of the aforementioned blue fluorescent host material and blue fluorescent guest material, the mass percentage of the blue fluorescent guest material in the material system can be 3% to 10%, including but not limited to: 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, etc.

[0066] By limiting the composition and ratio of the blue fluorescent host material and the blue fluorescent guest material as described above, the embodiments of the present invention can achieve the goal of balancing device lifespan and efficiency, so that the device has both excellent lifespan and efficiency.

[0067] In this embodiment of the invention, the emission spectrum of the blue phosphorescent guest material has a full width at half maximum (FWHM) of 40 nm to 60 nm, including but not limited to: 40 nm to 59 nm, 40 nm to 58 nm, 40 nm to 57 nm, 40 nm to 56 nm, 40 nm to 55 nm, 55 nm to 60 nm, 56 nm to 60 nm, 57 nm to 60 nm, 58 nm to 60 nm, 59 nm to 60 nm, etc.

[0068] In some examples, the blue phosphorescent guest material that satisfies the above emission spectrum at half maximum width can be an iridium complex or a platinum complex.

[0069] For example, an example of an iridium complex could be bis(4,6-difluorophenylpyridine-C2,N)pyridinecarboxyiridium (FIrpic), and an example of a platinum complex could be the phosphorescent BD compound described in Example 1 below.

[0070] In this embodiment of the invention, the blue phosphorescent emitting layer includes a blue phosphorescent host material and a blue phosphorescent guest material. Some suitable blue phosphorescent host materials may be anthracene derivatives, fluorene derivatives, styrene-based amine derivatives, carbazole derivatives, or triazine derivatives.

[0071] Examples of blue phosphorescent host materials include: 9,10-di-(2-naphthyl)anthracene (ADN), 2-methyl-9,10-di-2-naphthylanthracene (MADN), 4,4'-bis[4-(diphenylamino)styryl]biphenyl (BDAV Bi), 4,4'-bis[4-(di-p-tolylamino)styryl]biphenyl (DPAV Bi), 9-(4-(triphenylsilyl)phenyl)-9H-3,9'-dicarbazole (SiCzCz), and 9,9'-(6-(3-(phenylsilyl)phenyl)-1,3,5-triazine-2,4-disubstituted)bis(9H-carbazole) (SiTrzCz2), etc. The blue phosphorescent host material can be selected from one or more of these materials.

[0072] In some examples, for the blue phosphorescent emitting layer composed of the aforementioned blue phosphorescent host material and blue phosphorescent guest material, the mass percentage of the blue phosphorescent guest material in the material system can be 3% to 10%, including but not limited to: 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, etc.

[0073] By limiting the composition and ratio of the blue phosphorescent host material and the blue phosphorescent guest material as described above, the embodiments of the present invention can achieve the goal of balancing device lifespan and efficiency, so that the device has both excellent lifespan and efficiency.

[0074] The separator is used to form a barrier between the blue fluorescent emitting layer and the blue phosphorescent emitting layer to ensure that the two emitting layers operate independently and reliably. Furthermore, since the blue fluorescent host material and the blue phosphorescent host material corresponding to the blue fluorescent emitting layer are usually N-type materials, in order to achieve good electron transport between the blue fluorescent emitting layer and the blue phosphorescent host material, the embodiments of the present invention make the separator a functional layer with electron transport function.

[0075] In some examples, the interlayer includes an electron transport material layer, which, based on the electron transport properties of the electron transport material layer, promotes electron transport between the blue fluorescent emitting layer and the blue phosphorescent emitting layer, thereby improving device efficiency.

[0076] In some examples, suitable materials for preparing separators with electron transport capabilities can be nitrogen-containing six-membered ring structures or compounds with phosphine oxide substituents on heterocycles, including but not limited to: benzimidazole derivatives, imidazopyridine derivatives, benzimidazolephenanthridine derivatives, pyrimidine derivatives, triazine derivatives, quinoline derivatives, isoquinoline derivatives, or phenanthreneroline derivatives, etc.

[0077] Examples of interlayer materials include 2-(4-biphenyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (PBD), 1,3-bis[5-(p-tert-butylphenyl)-1,3,4-oxadiazole-2-yl]benzene (OXD-7), 3-(4-tert-butylphenyl)-4-phenyl-5-(4-biphenyl)-1,2,4-triazole (TAZ), and 3-(4-tert-butylphenyl)-1,2,4-triazole. 4-(4-ethylphenyl)-5-(4-biphenyl)-1,2,4-triazole (p-EtTAZ), phenanthroline (BPhen), 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP), 4,4'-bis(5-methylbenzoxazol-2-yl)stilbene (BzOs), 1,3,5-tris(1-phenyl-1H-benzimidazol-2-yl)benzene (TPBI), etc.

[0078] The organic electroluminescent blue light-emitting device provided in this disclosure includes a hole transport unit comprising at least one of a hole injection layer, a hole transport layer, and an electron blocking layer; and an electron transport unit comprising at least one of an electron injection layer, an electron transport layer, and a hole blocking layer.

[0079] In some examples, the hole transport unit includes a hole transport layer, wherein the anode, the hole transport layer, and the light-emitting unit are stacked in sequence.

[0080] In some examples, the hole transport unit includes a hole injection layer and a hole transport layer, wherein the anode, the hole injection layer, the hole transport layer, and the light-emitting unit are stacked in sequence.

[0081] In some examples, the hole transport unit includes a hole transport layer and an electron blocking layer, wherein the anode, hole transport layer, electron blocking layer and light-emitting unit are stacked in sequence.

[0082] In some examples, the hole transport unit includes a hole transport layer, an electron blocking layer, and a hole injection layer, wherein the anode, hole injection layer, hole transport layer, electron blocking layer, and light-emitting unit are stacked in sequence.

[0083] In some examples, the electron transport unit includes an electron transport layer, wherein the cathode, the electron transport layer, and the light-emitting unit are stacked in sequence.

[0084] In some examples, the electron transport unit includes an electron transport layer and an electron injection layer, wherein the cathode, electron injection layer, electron transport layer, and light-emitting unit are stacked in sequence.

[0085] In some examples, the electron transport unit includes an electron transport layer and a hole blocking layer, wherein the cathode, electron transport layer, hole blocking layer and light-emitting unit are stacked in sequence.

[0086] In some examples, the electron transport unit includes an electron transport layer, a hole blocking layer, and an electron injection layer, wherein the cathode, electron injection layer, electron transport layer, hole blocking layer, and light-emitting unit are stacked in sequence.

[0087] The hole transport unit, electron transport unit, anode, and cathode can all be made of currently known materials, which are described by example below.

[0088] The hole injection layer can be an inorganic oxide, such as oxides of metals like molybdenum, titanium, vanadium, rhenium, ruthenium, chromium, zirconium, hafnium, tantalum, silver, tungsten, and manganese. It can also be a p-type dopant with a strong electron-withdrawing system, for example, including but not limited to: hexacyanohexaazatriphenylene, 2,3,5,6-tetrafluoro-7,7,8,8-tetracyano-p-quinone dimethyl ether (F4TCNQ), 2,3,6,7,10,11-hexacyano-1,4,5,8,9,12-hexaazabenzophenanthrene (HAT-CN), and 1,2,3-tris[(cyano)(4-cyano-2,3,5,6-tetrafluorophenyl)methylene]cyclopropane, etc. Hole injection layers can also be prepared by p-type doping of hole transport materials, for example, by doping 4,4',4'-tris(N-3-methylphenyl-N-phenylamino)triphenylamine (m-MTDATA) with F4TCNQ. In some examples, the thickness of the hole injection layer can be 5 nm to 40 nm.

[0089] For the hole transport layer, it has good hole transport characteristics. For example, it can be an aromatic amine, dimethylfluorene, or carbazole material, including but not limited to: 4,4',4'-tris(N-3-methylphenyl-N-phenylamino)triphenylamine (m-MTDATA), 4,4'-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (NPB), N,N'-bis(3-methylphenyl)-N,N'-diphenyl-[1,1'- Examples of hole transport layers include [-biphenyl]-4,4'-diamine (TPD), 4-phenyl-4'-(9-phenylfluorene-9-yl)triphenylamine (BAFLP), 4,4'-bis[N-(9,9-dimethylfluorene-2-yl)-N-phenylamino]biphenyl (DFLDPBi), 4,4'-bis(9-carbazolyl)biphenyl (CBP), and 9-phenyl-3-[4-(10-phenyl-9-anthrayl)phenyl]-9H-carbazole (PCzPA). In some examples, the thickness of the hole transport layer can be 20 nm-200 nm.

[0090] For electron blocking layers, the electron blocking layer can also be an aromatic amine, dimethylfluorene, or carbazole material. However, when both an electron blocking layer and a hole transport layer exist, different materials are chosen for each to correspond to different functions according to actual needs. Some examples of electron blocking materials include, but are not limited to: 4,4',4'-tris(N-3-methylphenyl-N-phenylamino)triphenylamine (m-MTDATA), 4,4'-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (NPB), N,N'-bis(3-methylphenyl)-N,N'-diphenyl-[1,1'-biphenyl]-4,4'-diamine (TPD), and 4-phenyl-4'-(9-phenylfluorene-9-yl)triphenylamine (BAF). Examples of electron blocking layers include LP), 4,4'-bis[N-(9,9-dimethylfluorene-2-yl)-N-phenylamino]biphenyl (DFLDPBi), 4,4',4”-tris(carbazole-9-yl)triphenylamine (TCTA), 4,4'-bis(9-carbazole)biphenyl (CBP), and 9-phenyl-3-[4-(10-phenyl-9-anthrayl)phenyl]-9H-carbazole (PCzPA). In some examples, the thickness of the electron blocking layer can be 5 nm-100 nm.

[0091] The electron-injected layer is typically an alkali metal, a metal, or an oxide thereof, such as, but not limited to, LiF, Yb, Mg, Ca, and their oxides. In some examples, the thickness of the electron-injected layer can be 1 nm to 20 nm.

[0092] For the electron transport layer and hole blocking layer, it can be a compound with a nitrogen-containing six-membered ring structure, or a compound with phosphine oxide substituents on a heterocycle, including but not limited to: benzimidazole derivatives, imidazopyridine derivatives, benzimidazolephenanthridine derivatives, pyrimidine derivatives, triazine derivatives, quinoline derivatives, isoquinoline derivatives, or phenanthrene derivatives, etc.

[0093] When at least two of the electron transport layer, hole blocking layer, and separator are present, they are each made of different materials to correspond to different functions according to actual needs.

[0094] Examples of electron transport layers and hole blocking layers include 2-(4-biphenyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (PBD), 1,3-bis[5-(p-tert-butylphenyl)-1,3,4-oxadiazole-2-yl]benzene (OXD-7), 3-(4-tert-butylphenyl)-4-phenyl-5-(4-biphenyl)-1,2,4-triazole (TAZ), and 3-(4-tert-butylphenyl)-1,2,4-triazole (TAZ). Examples of electron transport layers include p-EtTAZ (4-(4-ethylphenyl)-5-(4-biphenyl)-1,2,4-triazole), BPhen (red phenanthroline), BCP (2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline), BzOs (4,4'-bis(5-methylbenzoxazol-2-yl)stilbene), and TPBI (1,3,5-tris(1-phenyl-1H-benzimidazol-2-yl)benzene). In some examples, the thickness of the electron transport layer or hole blocking layer is 20 nm to 200 nm.

[0095] Electron transport layers can also be prepared by N-type doping of electron transport materials, for example, by doping 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP) with lithium 8-hydroxyquinoline (Liq).

[0096] The anode mentioned above can be a single-layer structure or a multi-layer structure. For a multi-layer anode, it includes a reflective layer (or a transmissive-reflective layer) and a transmissive conductive layer stacked thereon. The transmissive conductive layer can be prepared using ITO, IZO, ZnO, or ITZO.

[0097] The reflective layer (or transflective layer) can be made of metal, metal alloy, or metal compound, for example, including but not limited to: at least one of silver (Ag), magnesium (Mg), copper (Cu), aluminum (Al), platinum (Pt), palladium (Pd), gold (Au), nickel (Ni), neodymium (Nd), iridium (Ir), chromium (Cr), lithium (Li), calcium (Ca), LiF / Ca, LiF / Al, molybdenum (Mo), titanium (Ti), and their alloys or compounds. One example is a three-layer structure of ITO / Ag / ITO as the anode.

[0098] The cathode can be of various types, including but not limited to: a transmission electrode, a transmission-reflection electrode, or a reflection electrode. For a transmission electrode, it can include transparent metal oxides such as ITO, IZO, ZnO, ITZO, etc. For a transmission-reflection electrode or a reflection electrode, the raw materials used in its preparation can include at least one of Ag, Mg, Cu, Al, Pt, Pd, Au, Ni, Nd, Ir, Cr, Li, Ca, LiF / Ca, LiF / Al, Mo, Ti, and their compounds or alloys.

[0099] The functional layers mentioned above in the organic electroluminescent blue light-emitting device can be prepared by vacuum evaporation process, and the organic electroluminescent blue light-emitting device can be designed as a top-emitting device.

[0100] On the other hand, embodiments of the present invention also provide a display panel, which includes a red sub-pixel, a green sub-pixel, and a blue sub-pixel. Each sub-pixel includes an anode, a hole transport unit, a light-emitting layer, an electron transport unit, and a cathode arranged in sequence. The blue sub-pixel employs any of the organic electroluminescent blue light-emitting devices described above.

[0101] The display panel provided in this embodiment of the invention uses the organic electroluminescent blue light-emitting device mentioned above, which can effectively improve the problem of blue light color shift under different viewing angles, and also has excellent efficiency and lifespan.

[0102] The structures of the light-emitting devices upon which the red and green sub-pixels are based, except that the light-emitting layer is a single layer, can refer to the structure of the aforementioned organic electroluminescent blue light-emitting device. Furthermore, the materials of the anode, hole injection layer, hole transport layer, electron blocking layer, electron injection layer, electron transport layer, hole blocking layer, and cathode involved in the red and green sub-pixels can all be the same as the corresponding layers in the organic electroluminescent blue light-emitting device, and will not be elaborated further here.

[0103] In some examples, the red emitting layer of the red subpixel comprises a red phosphorescent host material and a red phosphorescent guest material, and the green emitting layer of the green subpixel comprises a green phosphorescent host material and a green phosphorescent guest material. Specifically, the difference in the full width at half maximum (FWHM) of the emission spectra between the green and red phosphorescent guest materials is less than 45 nm (FWHM(G) - FWHM(R) < 45 nm); the difference in the FWHM of the emission spectra between the green and blue phosphorescent guest materials is less than 35 nm (FWHM(G) - FWHM(B) < 35 nm); and the difference in the FWHM of the emission spectra between the blue and red phosphorescent guest materials is less than 45 nm (FWHM(B) - FWHM(R) < 45 nm).

[0104] By limiting the emission spectrum of each object material as described above, the color matching degree of the red, green and blue light emitted by the display panel can be improved, thereby further reducing the color deviation of the three and improving the color deviation of white light.

[0105] Among them, at least one of the red phosphorescent guest material, green phosphorescent guest material, and blue phosphorescent guest material is a platinum complex, thereby achieving the purpose of improving the efficiency and lifespan of the display panel.

[0106] The red emitting layer of the red subpixel includes a red phosphorescent host material and a red phosphorescent guest material. Some suitable red phosphorescent host materials can be carbazole derivatives, aromatic amine derivatives, CM series materials, etc. For further examples, examples of red phosphorescent host materials include, but are not limited to: 3,3'-bis(9H-carbazole-9-yl)-1,1'-biphenyl (MCBP), 4-(dicyanomethylene)-2-methyl-6-(4-dimethylaminostyryl)-4H-pyran (DCM), and 4-(dicyanomethylene)-2-tert-butyl-6-(1,1,7,7-tetramethyljulonidin-9-enyl)-4H-pyran (DCJTB). The red phosphorescent host material can be selected from one or more of these materials.

[0107] Some suitable red phosphorescent guest materials can be metal complexes. Further examples of red phosphorescent guest materials include, but are not limited to: bis(1-phenylisoquinoline)(acetylacetone)iridium(III))(Ir(piq)2(acac)), octaethylporphyrin platinum (PtOEP), bis(2-(2'-benzothiophene)pyridine-N,C3')(acetylacetone)iridium (Ir(btp)2(acac), etc.

[0108] In some examples, for the red luminescent layer composed of the aforementioned red phosphorescent host material and red phosphorescent guest material, the mass percentage of the red phosphorescent guest material in the material system can be 1% to 10%, including but not limited to: 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, etc.

[0109] By limiting the composition and ratio of the red phosphorescent host material and the red phosphorescent guest material as described above, the embodiments of the present invention can achieve the goal of balancing device lifespan and efficiency, so that the device has both excellent lifespan and efficiency.

[0110] The green emitting layer of the green subpixel includes a green phosphorescent host material and a green phosphorescent guest material. Some suitable green phosphorescent host materials can be polycyclic aromatic hydrocarbons, diamine anthracene derivatives, carbazole derivatives, aromatic amine derivatives, etc. For further examples, examples of green phosphorescent host materials include, but are not limited to: 3,3'-bis(9H-carbazole-9-yl)-1,1'-biphenyl (mCBP), N10,N10'-diphenyl-N10,N10'-diphenyldicarboxyyl-9,9'-dianthracene-10,10'-diamine (abbreviated as: BA-NPB), etc. The green phosphorescent host material can be selected from one or more of these materials.

[0111] Some suitable green phosphorescent guest materials can be metal complexes. Further examples of green phosphorescent guest materials include, but are not limited to, tris(2-phenylpyridine)iridium (Ir(ppy)3) and bis(2-phenylpyridine)iridium acetylacetonate (Ir(ppy)2(acac)).

[0112] In some examples, for the green luminescent layer composed of the aforementioned green phosphorescent host material and green phosphorescent guest material, the mass percentage of the green phosphorescent guest material in the material system can be 1% to 10%, including but not limited to: 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, etc.

[0113] By limiting the composition and ratio of the green phosphorescent host material and the green phosphorescent guest material as described above, the embodiments of the present invention can achieve the goal of balancing device lifespan and efficiency, so that the device has both excellent lifespan and efficiency.

[0114] In some examples, the display panel provided in this embodiment of the invention further includes a light extraction layer (CPL), which is stacked on the surface of the cathode away from the electron transport unit. By providing the light extraction layer, the light emission mode of the display panel can be improved, and the light extraction efficiency of the display panel can be increased.

[0115] The material of the light extraction layer can be an aromatic amine material with hole transport properties, a dimethylfluorene light extraction layer, or a carbazole material. For example, this includes, but is not limited to, 4,4'-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (NPB), N,N'-bis(3-methylphenyl)-N,N'-diphenyl-[1,1'-biphenyl]-4,4'-diamine (TPD), etc. The above materials have a high refractive index.

[0116] In another aspect, embodiments of the present invention also provide a display device, which includes any of the display panels described above.

[0117] The display device provided in this embodiment of the invention has all the advantages of the display panel mentioned above.

[0118] For example, the display device includes, but is not limited to, mobile phone displays, computer displays, television displays, smartwatch displays, smart car displays, VR or AR headset displays, etc.

[0119] Exemplary embodiments of the present invention will now be described in more detail. While exemplary embodiments of the present invention are described below, it should be understood that the present invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Where specific techniques or conditions are not specified in the embodiments, they are performed in accordance with techniques or conditions described in the literature in the art or according to product instructions. Reagents or instruments used, unless otherwise specified, are all commercially available conventional products.

[0120] The chemical structural formulas of some of the materials involved in the following embodiments are shown below:

[0121]

[0122]

[0123] Example 1

[0124] Example 1 provides a display substrate, which includes a red sub-pixel, a green sub-pixel and a blue sub-pixel, each sub-pixel including an anode, a hole transport unit, a light-emitting layer, an electron transport unit and a cathode arranged in sequence.

[0125] For the blue sub-pixel, see Figure 1 The structure of the organic electroluminescent blue light-emitting device used is as follows: anode 100 / hole injection layer 201 / hole transport layer 202 / electron blocking layer 203 / blue fluorescent light-emitting layer 301 / separator 302 / blue phosphorescent light-emitting layer 303 / hole blocking layer 401 / electron transport layer 402 / electron injection layer 403 / cathode 500 / light extraction layer 600.

[0126] The anode is made of ITO; the hole injection layer is made of m-MTDATA+F4TCNQ, with F4TCNQ accounting for 3% of the mass and having a thickness of 10 nm; the hole transport layer is made of m-MTDATA and has a thickness of 100 nm; the electron blocking layer is made of CBP and has a thickness of 10 nm; the blue phosphorescent layer is made of fluorescent BH+fluorescent BD1, with fluorescent BD1 accounting for 5% of the mass and having a thickness of 10 nm; the separator is made of TPBI and has a thickness of 5 nm; and the blue phosphorescent layer... The material of the light-emitting layer is phosphorescent BH1:phosphorescent BH2:phosphorescent BD 5%, where the mass ratio of BH1 to BH2 is 1:1, the mass percentage of phosphorescent BD is 5%, and its thickness is 10nm; the material of the hole-blocking layer is TPBI, and its thickness is 5nm; the material of the electron transport layer is BCP+Liq with a mass ratio of 1:1, and its thickness is 30nm; the material of the electron injection layer is Yb, and its thickness is 1nm; the material of the cathode is Mg / Ag alloy, and its thickness is 13nm; the material of the light extraction layer is CPL, and its thickness is 65nm.

[0127] For the green sub-pixel, the structure of the organic electroluminescent green light-emitting device used is as follows: anode / hole injection layer / hole transport layer / electron blocking layer / blue light-emitting layer / hole blocking layer / electron transport layer / electron injection layer / cathode / light extraction layer.

[0128] The anode is made of ITO; the hole injection layer is made of m-MTDATA+F4TCNQ with F4TCNQ accounting for 3% of the mass and has a thickness of 10 nm; the hole transport layer is made of m-MTDATA with a thickness of 100 nm; the electron blocking layer is made of CBP with a thickness of 45 nm; the green emitting layer is made of GH+GD with GD accounting for 10% of the mass and has a thickness of 40 nm; the hole blocking layer is made of TPBI with a thickness of 5 nm; the electron transport layer is made of BCP+Liq with a mass ratio of 1:1 and has a thickness of 30 nm; the electron injection layer is made of Yb with a thickness of 1 nm; the cathode is made of Mg / Ag alloy with a thickness of 13 nm; and the light extraction layer is made of CPL with a thickness of 65 nm.

[0129] For the red sub-pixel, the structure of the organic electroluminescent red light-emitting device used is as follows: anode / hole injection layer / hole transport layer / electron blocking layer / blue light-emitting layer / hole blocking layer / electron transport layer / electron injection layer / cathode / light extraction layer.

[0130] The anode is made of ITO; the hole injection layer is made of m-MTDATA+F4TCNQ with F4TCNQ accounting for 3% of the mass and has a thickness of 10 nm; the hole transport layer is made of m-MTDATA with a thickness of 100 nm; the electron blocking layer is made of CBP with a thickness of 75 nm; the red emitting layer is made of RH+RD with RD accounting for 3% of the mass and has a thickness of 45 nm; the hole blocking layer is made of TPBI with a thickness of 5 nm; the electron transport layer is made of BCP+Liq with a mass ratio of 1:1 and has a thickness of 30 nm; the electron injection layer is made of Yb with a thickness of 1 nm; the cathode is made of Mg / Ag alloy with a thickness of 13 nm; and the light extraction layer is made of CPL with a thickness of 65 nm.

[0131] The full width at half maximum (FWHM) of the emission spectrum of the aforementioned blue fluorescent guest material (fluorescent BD) is 23 nm, the full width at half maximum (FWHM) of the emission spectrum of the blue phosphorescent guest material (phosphorescent BD) is 53 nm, the full width at half maximum (FWHM) of the emission spectrum of the green phosphorescent guest material (GD) is 56 nm, and the full width at half maximum (FWHM) of the emission spectrum of the red phosphorescent guest material (RD) is 32 nm.

[0132] Comparative Example 1

[0133] Comparative Example 1 provides a comparative display substrate for comparison with Example 1. The difference between this display substrate and Example 1 is that the blue light-emitting layer in the blue sub-pixel is different. Comparative Example 1 only uses a blue fluorescent light-emitting layer. The material of the blue fluorescent light-emitting layer is fluorescent BH+ fluorescent BD2, and the mass percentage of fluorescent BD2 is 5%, and its thickness is 20nm.

[0134] Test Example 1

[0135] Test Example 1 tests the performance of the organic electroluminescent blue light-emitting devices in the display substrates provided in Example 1 and Comparative Example 1. The test items include: operating voltage (in V), luminous efficiency (in cd / A) and lifespan LT. The specific test results are shown in Table 1.

[0136] The lifespan is characterized by LT95@1000nit, which refers to the time required for the brightness of each organic electroluminescent device to decay to 95% of its initial brightness, based on an initial brightness of 1000nit.

[0137] Table 1 is obtained by normalizing the data in Comparative Example 1 using the normalization unit %, which is the corresponding data.

[0138] Table 1

[0139]

[0140] As shown in Table 1, the display substrate provided in Example 1 exhibits higher luminous efficiency and longer lifespan compared to Comparative Example 1.

[0141] Test Example 2

[0142] Test Example 2 tested the color shift data of the organic electroluminescent blue light-emitting devices involved in the display substrates of Example 1 and Comparative Example 1. The test results are shown in [reference needed]. Figure 2 , Figure 2 The curve showing the color shift of blue light as a function of viewing angle is shown. Figure 2 It can be seen that, compared with Comparative Example 1, the optimized organic electroluminescent blue light-emitting device in Example 1 has a smaller overall color shift value as the viewing angle changes, and the change range of its color shift also decreases accordingly as the viewing angle changes.

[0143] This test example 2 also tested the color deviation data of the RGB three colors in the display substrate of Example 1. The test results are shown in [link to test results]. Figure 3 , Figure 3 The color shift curves for red, green, and blue light as a function of viewing angle are shown. Figure 3 It can be seen that after optimization, the organic electroluminescent blue light-emitting device in Example 1 has a higher degree of matching of the color deviation data of the RGB three colors with the viewing angle, and the change trend of the RGB three colors is more consistent.

[0144] This test example 2 also tested the white light color shift data emitted by the display substrates of Example 1 and Comparative Example 1. The test results are shown in [reference needed]. Figure 4 , Figure 4 The curve showing the color cast of white light as a function of viewing angle is provided. Figure 4 It can be seen that after optimization, the white light color deviation of the organic electroluminescent blue light-emitting device in Example 1 is reduced.

[0145] The above description is merely for the purpose of enabling those skilled in the art to understand the technical solutions of the present invention, and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An organic electroluminescent blue light-emitting device, characterized in that, The organic electroluminescent blue light-emitting device includes: an anode, a hole transport unit, a light-emitting unit, an electron transport unit, and a cathode arranged in sequence; the light-emitting unit includes a blue fluorescent light-emitting layer, a spacer layer, and a blue phosphorescent light-emitting layer arranged in sequence, the blue fluorescent light-emitting layer being close to the hole transport unit, and the blue phosphorescent light-emitting layer being close to the electron transport unit; The blue fluorescent emitting layer comprises a blue fluorescent host material and a blue fluorescent guest material. The emission spectrum of the blue fluorescent guest material has a full width at half maximum (FWHM) of 20 nm to 30 nm, and the blue fluorescent host material is an N-type material. The blue phosphorescent emitting layer comprises a blue phosphorescent host material and a blue phosphorescent guest material. The emission spectrum of the blue phosphorescent guest material has a full width at half maximum (FWHM) of 40 nm to 60 nm. The blue phosphorescent host material comprises N-type material and P-type material. The difference between the full width at half maximum (FWHM) of the emission spectrum of the blue phosphorescent guest material and the full width at half maximum (FWHM) of the emission spectrum of the blue fluorescent guest material is 20 nm to 40 nm. The partition includes an electron transport material layer.

2. The organic electroluminescent blue light-emitting device according to claim 1, characterized in that, The chemical structural formula of the blue fluorescent guest material is shown below: A is directly attached to the six-membered heterocycle BN. A is a substituted or unsubstituted C6~C60 aryl or cycloalkyl group, a C10~C60 fused aryl group, or a C2~C60 five-membered or six-membered aromatic heterocyclic group. R1, R2, R3, and R4 are each independently hydrogen, deuterium, halogen, nitro, nitrile, substituted or unsubstituted C1-C30 alkyl, substituted or unsubstituted C2-C30 alkenyl, substituted or unsubstituted C1-C30 alkoxy, substituted or unsubstituted C1-C30 thioether, substituted or unsubstituted C6-C50 aryl, or C2-C50 heteroaryl formed from a substituted or unsubstituted C2-C9 ring structure, or substituted or unsubstituted C6-C30 cycloalkyl.

3. The organic electroluminescent blue light-emitting device according to claim 1, characterized in that, The blue phosphorescent guest material is an iridium complex or a platinum complex.

4. The organic electroluminescent blue light-emitting device according to claim 1, characterized in that, The material of the partition is a benzimidazole derivative, an imidazopyridine derivative, a benzimidazole phenanthridine derivative, a pyrimidine derivative, a triazine derivative, a quinoline derivative, an isoquinoline derivative, or a phenanthridine derivative.

5. The organic electroluminescent blue light-emitting device according to claim 4, characterized in that, The hole transport unit includes at least one of a hole injection layer, a hole transport layer, and an electron blocking layer; The electron transport unit includes at least one of an electron injection layer, an electron transport layer, and a hole blocking layer.

6. A display panel, characterized in that, The display panel includes red sub-pixels, green sub-pixels and blue sub-pixels, and each sub-pixel includes an anode, a hole transport unit, a light-emitting layer, an electron transport unit and a cathode arranged in sequence. The blue sub-pixel is an organic electroluminescent blue light-emitting device as described in any one of claims 1-5.

7. The display panel according to claim 6, characterized in that, The red emitting layer of the red sub-pixel includes a red phosphorescent host material and a red phosphorescent guest material, and the green emitting layer of the green sub-pixel includes a green phosphorescent host material and a green phosphorescent guest material. The difference in the full width at half maximum (FWHM) of the emission spectra between the green phosphorescent guest material and the red phosphorescent guest material is less than 45 nm; The difference in the full width at half maximum (FWHM) of the emission spectra between the green phosphorescent guest material and the blue phosphorescent guest material is less than 35 nm. The difference in the full width at half maximum (FWHM) of the emission spectra between the blue phosphorescent guest material and the red phosphorescent guest material is less than 45 nm.

8. The display panel according to claim 7, characterized in that, At least one of the red phosphorescent guest material, the green phosphorescent guest material, and the blue phosphorescent guest material is a platinum complex.

9. The display panel according to any one of claims 6-8, characterized in that, The display panel further includes a light extraction layer, which is stacked on the surface of the cathode facing away from the electron transmission unit.

10. A display device, characterized in that, The display device includes the display panel as described in any one of claims 6-9.

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