Blue light organic electroluminescent device and display device comprising same

Abstract

The invention relates to a blue light organic electroluminescent device and a display device comprising the same, and belongs to the technical field of organic electroluminescent devices. Comprising an anode, a hole transmission unit, a light-emitting unit, an electron transmission unit and a cathode which are sequentially arranged in a stacked mode, and a light-emitting material of the light-emitting unit comprises a host material and a guest material. At least one of a material included in the hole transport unit and / or a material included in the electron transport unit and the host material form an interface exciplex; the emission spectrum of the interface exciplex is different from the emission spectrum of the host material, and at least one of the material of the hole transport unit and the material of the electron transport unit is different from the host material; by introducing the interface exciplex, the overall energy of the device can be reduced, the carrier injection can be improved, the service life of the blue organic light-emitting device can be prolonged, and the light-emitting efficiency of the blue organic light-emitting device can be improved.

Description

Technical Field

[0001] The present invention relates to the technical field of organic electroluminescent devices, and in particular to a blue organic electroluminescent device and a display device comprising the same. Background Art

[0002] At present, the luminescent materials used in organic light emitting devices (OLED devices) include red luminescent materials, green luminescent materials and blue luminescent materials. Among them, the red luminescent materials and green luminescent materials are both phosphorescent luminescent materials, which can meet the requirements of commercial service life and when both are applied to OLED devices, they have high luminous efficiency and low power consumption; while the blue luminescent materials are generally fluorescent materials, which can meet the requirements of service life, but are limited by the low utilization rate of triplet excitons, resulting in low luminous efficiency and high power consumption of OLED display panels using them; and the blue phosphorescent materials cannot meet the application requirements due to their short service life.

[0003] CN117979728A discloses an organic electroluminescent blue light-emitting device, a display panel, and a display apparatus. 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, an interlayer, and a blue phosphorescent light-emitting layer, one of the blue fluorescent and phosphorescent light-emitting layers is close to the hole transport unit, and the other is close to the electron transport unit; the blue fluorescent light-emitting layer includes a blue fluorescent host material and a blue fluorescent guest material, and the half-maximum width of the emission spectrum of the blue fluorescent guest material is 20 to 30 nm; the blue phosphorescent light-emitting layer includes a blue phosphorescent host material and a blue phosphorescent guest material, and the half-maximum width of the emission spectrum of the blue phosphorescent guest material is 40 to 60 nm; the difference in half-maximum width between the blue phosphorescent and fluorescent guest materials is 20 to 40 nm, which can reduce the color deviation of blue light and improve color shift under different viewing angles. CN118714869A discloses an organic light-emitting device, a display panel, and a display apparatus. The organic light-emitting device includes: a first electrode; a second electrode; at least one light-emitting layer located between the first electrode and the second electrode; the light-emitting layer includes a host material and at least two guest light-emitting materials; the wavelengths of the light-emitting spectrum peaks of the at least two guest light-emitting materials are different, and the at least two guest light-emitting materials are selected from the same light-emitting color, wherein any light-emitting layer is doped with two or more guest light-emitting materials with different light-emitting spectra, which can change the intrinsic spectral characteristics of the guest light-emitting materials in the light-emitting layer, thereby changing the light-emitting spectrum of the light-emitting layer, adjusting the color deviation, and making the light-emitting layer meet the predetermined color track requirements in the chromaticity diagram at different viewing angles. CN108807710A discloses a non-doped and doped complementary white light tandem organic electroluminescent device and a preparation method. The device includes a substrate, an anode, a cathode, and an organic functional layer between the anode and the cathode; the organic functional layer includes multiple white light emitting units, and the multiple white light emitting units are connected in series to form multiple white light emitting areas; the triplet energy levels of blue phosphorescent materials and blue delayed fluorescent materials are generally high. In order to meet the requirements of these materials, the main bodies of these materials are required to have higher triplet energy levels, which undoubtedly increases the difficulty of synthesizing high-energy-level materials.

[0004] That is, current blue light devices are limited by the emission of high triplet energy levels. The injection barrier between the light-emitting layer and the adjacent functional layer is high, and the transmission performance is poor, which causes carriers to easily accumulate and quench at the interface, which is not conducive to achieving high performance and long life requirements. Therefore, the development of a high-efficiency, long-life blue light device is still a research difficulty and hot spot in the OLED field. Summary of the Invention

[0005] To solve the above technical problems, the present invention provides a blue organic electroluminescent device and a display device including the same. The blue organic electroluminescent device provided by the present invention can reduce the overall device energy, improve carrier injection, and increase the device's luminescence life.

[0006] In a first aspect, the present invention provides a blue organic electroluminescent device, comprising an anode, a hole transport unit, a light-emitting unit, an electron transport unit, and a cathode stacked in sequence, wherein:

[0007] The light-emitting material of the light-emitting unit includes a host material and a guest material, and at least one of the materials included in the hole transport unit and / or the materials included in the electron transport unit forms an interface exciplex with the host material;

[0008] The luminescence spectrum of the interfacial exciplex is different from the emission spectrum of the host material, and at least one of the material of the hole transport unit and the material of the electron transport unit is different from the host material.

[0009] In a second aspect, the present invention provides an organic light-emitting display device comprising the blue organic electroluminescent device described in the first aspect.

[0010] The technical solution provided by the embodiment of the present invention has the following advantages compared with the existing technology:

[0011] The present invention can reduce the overall energy of the device and improve carrier injection by introducing an interfacial exciplex, thereby significantly enhancing the service life and luminous efficiency of the blue organic electroluminescent device, and selectively improving the stability of the device without significantly affecting the color purity of the device. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0013] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0014] Figure 1 A schematic structural diagram of a blue organic electroluminescent device according to some embodiments of the present invention;

[0015] Figure 2 Another structural schematic diagram of a blue organic electroluminescent device according to some embodiments of the present invention;

[0016] Among them, 1-anode; 2-hole transport unit; 201-hole injection layer; 202-first hole transport layer; 203-second hole transport layer; 3-light-emitting unit; 4-electron transport unit; 401-electron injection layer; 402-first electron transport layer; 403-second electron transport layer; 5-cathode; 6-capping layer;

[0017] Figure 3 The emission spectra of monomer films of some compounds in some embodiments of the present invention are shown;

[0018] Figure 4 This is the emission spectrum of the mixed film of compounds 5 and 6 in Example 1 of the present invention;

[0019] Figure 5 This is the emission spectrum of the mixed film of compounds 4 and 6 in Example 1 of the present invention;

[0020] Figure 6 : This is the emission spectrum of the mixed film of compounds 5 and 7 in Example 1 of the present invention;

[0021] Figure 7 This is the emission spectrum of the mixed film of compounds 6 and 11 in Example 2 of the present invention;

[0022] Figure 8 This is the emission spectrum of the mixed film of compounds 5 and 12 in Example 3 of the present invention;

[0023] Figure 9 Emission spectra of the devices provided in Examples 1-3 of the present invention and Comparative Example 1. DETAILED DESCRIPTION

[0024] In order to more clearly understand the above-mentioned objectives, features and advantages of the present invention, the scheme of the present invention will be further described below. It should be noted that, in the absence of conflict, the embodiments of the present invention and the features therein can be combined with each other.

[0025] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein; it is obvious that the embodiments in the specification are only part of the embodiments of the present invention, rather than all the embodiments.

[0026] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this application belongs. The terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0027] Current blue organic electroluminescent devices using fluorescent materials have a lifespan that meets requirements, but the utilization rate of their triplet excitons is low; while the service life and high triplet energy level luminescence of phosphorescent materials cannot meet application requirements. Based on this, the present invention provides a blue organic electroluminescent device that can reduce the overall device energy, improve carrier injection, and increase the luminescence lifespan of the organic electroluminescent device, thereby solving the problems of short lifespan and low efficiency of blue phosphorescent materials used in blue organic electroluminescent devices in the prior art.

[0028] In a first aspect, the present invention provides a blue organic electroluminescent device, such as Figure 1 As shown, it includes an anode 1, a hole transport unit 2, a light-emitting unit 3, an electron transport unit 4 and a cathode 5 stacked in sequence, wherein:

[0029] The light-emitting material of the light-emitting unit includes a host material and a guest material, and at least one of the materials included in the hole transport unit and / or the materials included in the electron transport unit forms an interface exciplex with the host material;

[0030] The luminescence spectrum of the interfacial exciplex is different from the emission spectrum of the host material, and at least one of the material of the hole transport unit and the material of the electron transport unit is different from the host material.

[0031] In organic electroluminescent devices, both holes and electrons need to overcome potential barriers to transfer to the light-emitting unit, recombine to form excitons, and then radiate to emit photons. However, due to the high injection barrier between the light-emitting unit and the adjacent functional layer in current blue phosphorescent organic electroluminescent devices, the transmission performance is poor, and carriers are easily accumulated and quenched at the interface, resulting in poor device performance and lifespan. However, the present invention forms an interfacial exciplex by contacting at least one of the materials of the electron transport unit and the hole transport unit with the main material in the light-emitting unit. The interfacial exciplex can reduce the carrier injection barrier and aggregation density. Therefore, the blue light organic electroluminescent device provided by the present invention can mitigate the quenching effect and improve the performance and lifespan of the device.

[0032] The anode 1 of the present invention can be a single-layer structure or a multi-layer structure. For the multi-layer structure anode, it can include a reflective layer (or a transflective layer) and a transmissive conductive layer stacked therewith; wherein the transmissive conductive layer can be prepared by ITO, IZO, ZnO or ITZO, but the present invention is not limited to the listed contents, and other contents not listed within the scope are also applicable.

[0033] The reflective layer (or transflective layer) can be made of a metal, metal alloy, or metal compound. The present invention lists the following metals, including but not limited to: 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 alloys or compounds thereof. However, the present invention is not limited to the listed metals, and other metals not listed within the scope are also applicable.

[0034] In some embodiments of the present invention, the anode 1 includes an ITO layer and a glass substrate layer stacked together.

[0035] Regarding the hole transport unit 2 of the present invention:

[0036] In some embodiments of the present invention, the hole transport unit 2 may include a hole injection layer, a hole transport layer, and may further include an electron blocking layer.

[0037] In some embodiments of the present invention, the hole transport unit 2 includes a hole injection layer, a first hole transport layer and a second hole transport layer arranged in sequence, the hole injection layer is close to the anode side, and at least one of the materials of the second hole transport layer contacts the second main material to form a first interface excited radical complex.

[0038] In the present invention, two different hole transport layers are introduced at the same time. The first hole transport layer can play a regulating role. The second hole transport layer plays a regulating role. At the same time, the material included in the second hole transport layer can form an interface excimer complex with the main material, thereby reducing the carrier injection barrier and aggregation density.

[0039] In some embodiments of the present invention, the hole injection layer may be an inorganic oxide, such as an oxide of a metal such as molybdenum, titanium, vanadium, rhenium, ruthenium, chromium, zirconium, hafnium, tantalum, silver, tungsten, or manganese; or a p-type dopant of a strong electron-withdrawing system, such as, but not limited to, hexacyanohexaazatriphenylene, 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4TCNQ), 2,3,6,7,10,11-hexacyanoquinodimethane (F4TCNQ), The hole injection layer can also be prepared by p-doping the hole transport material, for example, by doping 4,4',4'-tris(N-3-methylphenyl-N-phenylamino)triphenylamine (m-MTDATA) with F4TCNQ. However, the present invention is not limited to the listed contents, and other contents not listed within the scope are also applicable.

[0040] In some embodiments of the present invention, the thickness of the hole injection layer may be 2 to 200 nm, for example, 2 nm, 5 nm, 10 nm, 20 nm, 40 nm, 60 nm, 80 nm, 100 nm, 120 nm, 140 nm, 160 nm, 180 nm, 200 nm, etc. However, the present invention is not limited to the listed values, and other values ​​not listed within the range are also applicable.

[0041] In some embodiments of the present invention, the first hole transport layer has excellent hole transport properties. For example, it can be an aromatic amine or carbazole material, including but not limited to: 4,4',4'-tris(N-3-methylphenyl-N-phenylamino)triphenylamine (m-MTDATA), NPB, TPD, BAFLP, DFLDPBi, etc. However, the present invention is not limited to the listed materials, and other materials not listed within the scope are also applicable.

[0042] In some embodiments of the present invention, the material of the second hole transport layer includes at least one of a compound containing a carbazole group, an aromatic amine group, a phenoxazine group, a carbazole derivative group, an aromatic amine derivative group, and a phenoxazine derivative group, and the triplet energy level of the material of the second hole transport layer is higher than 2.5 eV.

[0043] In some embodiments of the present invention, the thickness of the first hole transport layer is greater than the thickness of the second hole transport layer.

[0044] In some embodiments of the present invention, the thickness of the first hole transport layer may be 20 to 200 nm, for example, 20 nm, 40 nm, 60 nm, 80 nm, 100 nm, 120 nm, 140 nm, 160 nm, 180 nm, 200 nm, etc. However, the present invention is not limited to the listed values, and other values ​​not listed within the range are also applicable.

[0045] In some embodiments of the present invention, the thickness of the second hole transport layer may be 2 to 200 nm, for example, 2 nm, 5 nm, 10 nm, 20 nm, 40 nm, 60 nm, 80 nm, 100 nm, 120 nm, 140 nm, 160 nm, 180 nm, 200 nm, etc., and the thickness of the first hole transport layer is greater than the thickness of the second hole transport layer. However, the present invention is not limited to the listed values, and other values ​​not listed within this range are also applicable.

[0046] The light-emitting unit 3 described in the present invention may be a separate blue light-emitting layer, in which the components include a host material and a guest material.

[0047] In some embodiments of the present invention, the peak emission spectrum of the host material is 380 to 500 nm, for example, 380 nm, 400 nm, 420 nm, 450 nm, 480 nm, 500 nm, etc., but the present invention is not limited to the listed values, and other unlisted values ​​within the range are also applicable, preferably 410 to 470 nm; the full width at half maximum of the emission spectrum is 30 to 120 nm, for example, 30 nm, 50 nm, 70 nm, 80 nm, 100 nm, 120 nm, etc., but the present invention is not limited to the listed values, and other unlisted values ​​within the range are also applicable, preferably 30 to 70 nm.

[0048] In some embodiments of the present invention, at least one of the materials included in the hole transport unit 2 and / or the materials included in the electron transport unit 4 forms an interfacial exciplex with the host material.

[0049] In some embodiments of the present invention, the peak value of the luminescence spectrum of the interfacial exciplex is 380 to 500 nm, for example, 380 nm, 400 nm, 420 nm, 450 nm, 480 nm, 500 nm, etc., but the present invention is not limited to the listed values, and other unlisted values ​​within the range are also applicable, preferably 410 to 480 nm; the full width at half maximum of the emission spectrum is 30 to 120 nm, for example, 30 nm, 50 nm, 70 nm, 80 nm, 100 nm, 120 nm, etc., but the present invention is not limited to the listed values, and other unlisted values ​​within the range are also applicable, preferably 60 to 90 nm.

[0050] In some embodiments of the present invention, the luminescence spectrum of the interfacial exciplex is different from the emission spectrum of the host material.

[0051] In some embodiments of the present invention, the blue organic electroluminescent device satisfies: |λ peak 界面激基复合物 -λ peak 主体材料 |≥5nm, that is, |λ peak 界面激基复合物 -λ peak 主体材料 | can be 5nm, 6nm, 8nm, 10nm, 15nm, 20nm, 25nm, etc., but the present invention is not limited to the listed values, and other values ​​not listed in the range are also applicable. Preferably |λ peak 界面激基复合物 -λ peak 主体材料 |≥20nm.

[0052] In some embodiments of the present invention, the host material is selected from at least one of a hole transport material, an electron transport material, and a bipolar material.

[0053] In some embodiments of the present invention, the host material includes a first host material and a second host material, and the mass ratio of the first host material to the second host material is 10:(1~100), for example, 10:1, 10:5, 10:10, 10:20, 10:30, 10:40, 10:50, 10:60, 10:70, 10:80, 10:90, 10:100, etc., but the present invention is not limited to the listed values, and other unlisted values ​​within this range are also applicable; the first host material and the second host material are different and the triplet energy levels are both higher than 2.5eV.

[0054] As a preferred technical solution of the present invention, the first host material is selected from at least one compound containing a carbazole group, an aromatic amine group, a phenoxazine group, a carbazole derivative group, an aromatic amine derivative group and a phenoxazine derivative group.

[0055] As a preferred technical solution of the present invention, the second main material is selected from at least one compound containing a triazine group, a phosphorus oxygen group, a benzimidazole group, a triazine derivative group, a phosphorus oxygen derivative group, and a benzimidazole derivative group.

[0056] In some embodiments of the present invention, the compound containing a carbazole group or a carbazole derivative group may be The compound containing an aromatic amine group or an aromatic amine group derivative can be The compound containing a phenoxazine group or a phenoxazine derivative group can be

[0057] However, the present invention is not limited to the enumerated contents, and other contents not enumerated within the scope are also applicable.

[0058] In some embodiments of the present invention, the compound containing a triazine group or a triazine derivative group may be The compound containing a phosphorus oxygen group or a phosphorus oxygen derivative group can be

[0059] The compound containing a benzimidazole group or a benzimidazole derivative group can be However, the present invention is not limited to the enumerated contents, and other contents not enumerated within the scope are also applicable.

[0060] In some embodiments of the present invention, the interfacial exciplex comprises a first interfacial exciplex and / or a second interfacial exciplex; wherein:

[0061] The first interface exciplex is formed by the contact between the material of the second hole transport layer and the second host material.

[0062] In some embodiments of the present invention, the emission spectrum peak of the first interface exciplex is different from the emission spectrum peak of the second host material; and / or the emission spectrum full width at half maximum of the first interface exciplex is different from the emission spectrum full width at half maximum of the second host material;

[0063] In some embodiments of the present invention, the second interface exciplex is formed by the contact between the material of the second electron transport layer and the first host material.

[0064] In some embodiments of the present invention, the emission spectrum peak of the second interface exciplex is different from the emission spectrum peak of the first host material; and / or the emission spectrum full width at half maximum of the second interface exciplex is different from the emission spectrum full width at half maximum of the first host material.

[0065] It should be noted that, in some embodiments of the present invention, the components of the second hole transport layer may also include compounds containing carbazole groups, aromatic amine groups, phenoxazine groups, carbazole derivative groups, aromatic amine derivative groups and phenoxazine derivative groups, and the components of the second electron transport layer may also be compounds containing triazine groups, phosphorus oxide groups, benzimidazole groups, triazine derivative groups, phosphorus oxide derivative groups, benzimidazole derivative groups, and some of them may be the same or different, but it should be noted that at least one of the materials of the second hole transport layer and / or the second electron transport layer is different from the first host material and / or the second host material.

[0066] In some embodiments of the present invention, the guest material emits blue light, and the peak value of the emission spectrum of the guest material is 400-480 nm, for example, 400 nm, 410 nm, 420 nm, 450 nm, 460 nm, 480 nm, etc., but the present invention is not limited to the listed values, and other unlisted values ​​within the range are also applicable, preferably 450-470 nm; the full width at half maximum of the emission spectrum is 10-40 nm, for example, 10 nm, 15 nm, 20 nm, 25 nm, 30 nm, 40 nm, etc., but the present invention is not limited to the listed values, and other unlisted values ​​within the range are also applicable, preferably 10-40 nm.

[0067] In some embodiments of the present invention, the guest material includes a phosphorescent material.

[0068] In some embodiments of the present invention, the guest material includes a phosphorescent material and a fluorescent material, and the mass ratio of the fluorescent material to the phosphorescent material is 1:2 to 40, for example, 1:2, 1:5, 1:8, 1:10, 1:15, 1:20, 1:25, 1:30, 1:35, 1:40, etc., but the present invention is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0069] In some embodiments of the present invention, the luminescent material further comprises a third component in addition to the host material and the guest material, wherein the third component comprises at least one of a thermally activated delayed fluorescent material and a phosphorescent luminescent material and is different from both the host material and the guest material.

[0070] In some embodiments of the present invention, the mass proportion of the third component in the light-emitting layer is 5% to 40%, for example, 5%, 8%, 10%, 12%, 15%, 18%, 20%, 22%, 25%, 28%, 30%, 32%, 35%, 38%, 40%, etc., but the present invention is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0071] As a preferred technical solution of the present invention, the thickness of the light-emitting unit 3 is 10 to 70 nm, for example, 10 nm, 15 nm, 20 nm, 25 nm, 30 nm, 35 nm, 40 nm, 45 nm, 50 nm, 55 nm, 60 nm, 65 nm, 70 nm, etc., but the present invention is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0072] Regarding the electron transfer unit 4 of the present invention:

[0073] In some embodiments of the present invention, the electron transport unit 4 may include an electron injection layer, an electron transport layer, and may also include a hole blocking layer.

[0074] In some embodiments of the present invention, the electron transport unit 4 includes an electron injection layer, a first electron transport layer, and a second electron transport layer, arranged in sequence. The electron injection layer is close to the cathode side, and at least one material of the second electron transport layer contacts the first host material to form a second interfacial exciplex. In the present invention, the material included in the second electron transport layer can form an interfacial exciplex with the host material, thereby reducing the carrier injection barrier and aggregation density.

[0075] In some embodiments of the present invention, the electron injection layer may be an alkali metal, a metal, or an oxide thereof, including but not limited to LiF, Yb, Mg, Ca, and their oxides. In some examples, the thickness of the electron injection layer may be 1 to 20 nm, such as 1 nm, 2 nm, 5 nm, 8 nm, 10 nm, 12 nm, 15 nm, 18 nm, 20 nm, etc. However, the present invention is not limited to the listed values, and other values ​​not listed within the range are also applicable.

[0076] In some embodiments of the present invention, the first electron transport layer can be an aromatic heterocyclic compound, such as imidazole derivatives such as benzimidazole derivatives, imidazopyridine derivatives, and benzimidazolephenanthridine derivatives; oxazine derivatives such as pyrimidine derivatives and triazine derivatives; quinoline derivatives, isoquinoline derivatives, phenanthroline derivatives, and the like containing nitrogen-containing six-membered ring structures, or compounds including phosphine oxide-based substituents on the heterocyclic ring, etc. By further example, the first electron transport layer includes but is not limited to the following: 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), 3-(4-tert-butylphenyl)-4-(4-ethylphenyl)-5-(4-biphenyl)-1,2,4-triazole (p-EtTAZ), bathophenanthroline (BPDen), 4,4'-bis(5-methylbenzoxazol-2-yl)stilbene (BzOs), BCP, TPBi, etc.; it may further include doping materials such as Liq, Yb, etc., so as to enhance the electron injection and transport properties.

[0077] In some embodiments of the present invention, the material of the second electron transport layer is selected from at least one of a triazine group, a phosphorus oxide group, a benzimidazole group, a triazine derivative group, a phosphorus oxide derivative group, and a benzimidazole derivative group, and the triplet energy level of the material of the second electron transport layer is higher than 2.5 eV.

[0078] In some embodiments of the present invention, the thickness of the first electron transport layer is greater than the thickness of the second electron transport layer.

[0079] In some embodiments of the present invention, the thickness of the first electron transport layer may be 20 to 200 nm, for example, 20 nm, 40 nm, 60 nm, 80 nm, 100 nm, 120 nm, 140 nm, 160 nm, 180 nm, 200 nm, etc. However, the present invention is not limited to the listed values, and other values ​​not listed within the range are also applicable.

[0080] In some embodiments of the present invention, the thickness of the second electron transport layer may be 2 to 200 nm, for example, 2 nm, 5 nm, 10 nm, 20 nm, 40 nm, 60 nm, 80 nm, 100 nm, 120 nm, 140 nm, 160 nm, 180 nm, 200 nm, etc., and the thickness of the first electron transport layer is greater than the thickness of the second electron transport layer. However, the present invention is not limited to the listed values, and other values ​​not listed within this range are also applicable.

[0081] The cathode 5 of the present invention may be a transmissive electrode, a transflective electrode, or a reflective electrode. Transmissive electrodes may include transparent metal oxides such as ITO, IZO, ZnO, and ITZO. Transmissive or reflective electrodes may be made from materials selected from Ag, Mg, Cu, Al, Pt, Pd, Au, Ni, Nd, Ir, Cr, Li, Ca, LiF / Ca, LiF / Al, Mo, Ti, and compounds or alloys thereof.

[0082] In some embodiments of the present invention, Figure 2 As shown, the blue organic electroluminescent device includes an anode 1, a hole transport unit 2, a light-emitting unit 3, an electron transport unit 4 and a cathode 5 stacked in sequence, wherein:

[0083] The hole transport unit 2 includes a hole injection layer 201, a first hole transport layer 202 and a second hole transport layer 203 arranged in sequence, and the hole injection layer 201 is close to the side of the anode 1;

[0084] The electron transport unit 4 includes an electron injection layer 401, a first electron transport layer 402 and a second electron transport layer 403 arranged in sequence, and the electron injection layer 401 is close to the cathode 5;

[0085] The structure further comprises a capping layer 6 which is arranged on the outer side of the cathode 5 .

[0086] The blue organic electroluminescent device provided by the present invention can significantly enhance the service life and luminous efficiency of the blue OLED device after introducing the interfacial exciplex, without significantly affecting the color purity of the device and selectively improving the stability of the device.

[0087] In a second aspect, the present invention provides an organic light-emitting display device comprising the blue organic electroluminescent device described in the first aspect.

[0088] In order to make the technical problems, technical solutions and beneficial effects solved by the present invention clearer, the present invention will be further described in detail with reference to the following embodiments. Obviously, the embodiments described are only some embodiments of the present invention, rather than all embodiments. The following description of at least one exemplary embodiment is actually only illustrative and in no way serves as any limitation on the present invention and its applications. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0089] If no specific techniques or conditions are specified in the examples, the experiments were carried out according to conventional techniques or conditions in the art, or those described in the literature, or the product instructions. Reagents or instruments used without manufacturer specified were all commercially available conventional products.

[0090] The structural formulas of the compounds involved in the examples are as follows, and the emission spectra of the monomer films of some of the compounds are shown in Figure 3 :

[0091]

[0092]

[0093] Example 1

[0094] This embodiment provides a blue organic electroluminescent device and a preparation method thereof as follows:

[0095] (1) A glass substrate was cut into pieces of 50 mm × 50 mm × 0.7 mm in size, ultrasonically treated in isopropyl alcohol and deionized water for 30 min, respectively, and then exposed to ozone for about 10 min for cleaning to obtain a substrate. The obtained glass substrate with a 10 nm indium tin oxide (ITO) anode was mounted on a vacuum deposition apparatus.

[0096] (2) On the ITO anode layer, the hole injection layer material compound 2 and the p-doping material compound 1 were co-deposited by vacuum evaporation with a doping ratio of 3 wt % and a thickness of 5 nm to serve as the hole injection layer.

[0097] (3) Compound 3, a hole transport layer material, was vacuum-deposited on the hole injection layer to a thickness of 100 nm to form the first hole transport layer.

[0098] (4) Hole transport type material compound 4 was vacuum evaporated on the first hole transport layer to a thickness of 5 nm to serve as the second hole transport layer.

[0099] (5) A light-emitting layer was vacuum-deposited on the second hole transport layer, with compounds 5 and 6 as the main materials (46%:46%), compound t-Pt-Ad (7%) as the exciton utilization agent, and TBE-02 as the guest light-emitting material. The doping ratio was 1 wt% and the thickness was 30 nm.

[0100] (6) Electron transport material compound 7 was vacuum evaporated on the light emitting layer to a thickness of 5 nm to serve as the second electron transport layer.

[0101] (7) Electron transport materials Compound 8 and Compound 9 were co-evaporated on the electron transport layer in a vacuum manner with a doping mass ratio of 1:1 and a thickness of 30 nm to serve as the first electron transport layer.

[0102] (8) Electron Transport Layer: Compound 9 was evaporated to a thickness of 1 nm to serve as an electron injection layer.

[0103] (9) A magnesium-silver electrode with a Mg:Ag ratio of 1:9 and a thickness of 10 nm was vacuum-deposited on the electron injection layer as a cathode.

[0104] (10) Compound 10 was vacuum evaporated on the cathode to a thickness of 70 nm to serve as a capping layer.

[0105] In this embodiment, compound 6, as the second host material, can form an interfacial exciplex with compound 4 of the second hole transport layer, and compound 5, as the first host material, can form an interfacial exciplex with compound 7 of the second electron transport layer.

[0106] Example 2

[0107] This embodiment provides a blue organic electroluminescent device.

[0108] The only difference from Example 1 is that, in this example, Compound 4 is replaced by Compound 11, and Compound 11 and Compound 6 cannot form an interfacial exciplex.

[0109] Example 3

[0110] This embodiment provides a blue organic electroluminescent device.

[0111] The only difference from Example 1 is that, in this example, Compound 7 is replaced by Compound 12, and Compound 12 and Compound 5 cannot form an interfacial exciplex.

[0112] Example 4

[0113] This embodiment provides a blue organic electroluminescent device.

[0114] The only difference from Example 1 is that, in this example, Compound 4 is replaced by Compound 5, that is, Compound 4 serves as both the first host material and the material of the second hole transport layer.

[0115] Example 5

[0116] This embodiment provides a blue organic electroluminescent device.

[0117] The only difference from Example 1 is that in this example, compound 4 is replaced by a compound containing a phenoxazine group.

[0118] Example 6

[0119] This embodiment provides a blue organic electroluminescent device.

[0120] The only difference from Example 1 is that, in this example, compound 7 is replaced by

[0121] Example 7

[0122] This embodiment provides a blue organic electroluminescent device.

[0123] The only difference from Example 1 is that, in this example, compound 7 is replaced by a compound containing a benzimidazole group. Comparative Example 1

[0124] This comparative example provides a blue organic electroluminescent device.

[0125] The only difference from Example 1 is that, in this comparative example, Compound 4 is replaced by Compound 6, and Compound 7 is replaced by Compound 5, that is, the materials of the second hole transport layer and the second electron transport layer are the same as the host material.

[0126] Performance Testing

[0127] The performance test of the blue organic electroluminescent devices provided in the examples and comparative examples was carried out as follows:

[0128] (1) The compound to be tested was coated to form a thin film, and then tested using a fluorescence spectrometer. The test results are as follows:

[0129] Figure 4 is the emission spectrum of the mixed film of compounds 5 and 6 in Example 1, Figure 5 : is the emission spectrum of the mixed film of compounds 4 and 6 in Example 1; Figure 6 : is the emission spectrum of the mixed film of compounds 5 and 7 in Example 1; Figure 7 : is the emission spectrum of the mixed film of compounds 6 and 11 in Example 2; Figure 8 is the emission spectrum of the mixed film of compounds 5 and 12 in Example 3; Figure 4-8 It can be seen that in Example 1, interfacial exciplexes were formed between Compound 4 and Compound 6, and between Compound 5 and Compound 7, while no interfacial exciplexes were formed between Compound 6 and Compound 11, and between Compound 5 and Compound 12, which were only mixtures of the two compounds.

[0130] Figure 9 The emission spectra of the devices provided in Examples 1-3 and Comparative Example 1 are as follows. As can be seen from the figure, the peak values ​​of the emission spectra of the devices provided in the Examples and Comparative Example are both around 460 nm, that is, the blue light organic electroluminescent device provided by the present invention does not significantly affect the color purity of the device after the introduction of the interfacial excimer complex.

[0131] Performance tests were performed on the blue organic electroluminescent devices provided in Examples 1-3 and Comparative Example 1. The voltage test was performed using a current source meter, and the external quantum efficiency (EQE) and service life (LT, with Comparative Example 1 as 100%) were tested using a CS2000 spectrometer. The test results are shown in Table 1:

[0132] Table 1

[0133]

[0134]

[0135] As can be seen from the table and figure, the introduction of the interfacial exciplex into the blue organic electroluminescent device of the present invention can significantly enhance the service life and luminous efficiency of the blue organic electroluminescent device without significantly affecting the color purity of the device and selectively improving the stability of the device.

[0136] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article, or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or elements inherent to such process, method, article, or device. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of other identical elements in the process, method, article, or device comprising the element.

[0137] The foregoing description is intended only to provide specific embodiments of the present invention, which will enable those skilled in the art to understand and implement the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not intended to be limited to the embodiments described herein, but is to be construed in the widest manner consistent with the principles and novel features disclosed herein.

Claims

1. A blue organic electroluminescent device, characterized in that: It includes an anode, a hole transport unit, a light-emitting unit, an electron transport unit and a cathode stacked in sequence, wherein: The light-emitting material of the light-emitting unit includes a host material and a guest material, and at least one of the materials included in the hole transport unit and / or the materials included in the electron transport unit forms an interface exciplex with the host material; The luminescence spectrum of the interfacial exciplex is different from the emission spectrum of the host material, and at least one of the material of the hole transport unit and the material of the electron transport unit is different from the host material.

2. The blue organic electroluminescent device according to claim 1, characterized in that: The blue organic electroluminescent device satisfies: |λ peak 界面激基复合物 -λ peak 主体材料 |≥5nm; And / or, the peak value of the emission spectrum of the host material is 380 to 500 nm, and the full width at half maximum of the emission spectrum is 30 to 120 nm; The guest material emits blue light, and the peak value of the emission spectrum of the guest material is 400-480 nm, and the full width at half maximum of the emission spectrum is 10-40 nm; The peak value of the luminescence spectrum of the interface excimer complex is 380-500 nm, and the full width at half maximum of the emission spectrum is 50-120 nm.

3. The blue organic electroluminescent device according to claim 2, characterized in that: The host material includes a first host material and a second host material, and the mass ratio of the first host material to the second host material is 10:(1-100); the first host material and the second host material are different and the triplet energy levels are both higher than 2.5 eV.

4. The blue organic electroluminescent device according to claim 3, characterized in that: The first host material is at least one selected from compounds containing a carbazole group, an aromatic amine group, a phenoxazine group, a carbazole derivative group, an aromatic amine derivative group, and a phenoxazine derivative group; And / or, the second host material is at least one selected from compounds containing a triazine group, a phosphorus oxide group, a benzimidazole group, a triazine derivative group, a phosphorus oxide derivative group, and a benzimidazole derivative group.

5. The blue organic electroluminescent device according to claim 3, characterized in that: The hole transport unit includes a hole injection layer, a first hole transport layer, and a second hole transport layer arranged in sequence, wherein the hole injection layer is close to the anode side, and at least one of the materials of the second hole transport layer contacts the second host material to form a first interface exciplex; And / or, the electron transport unit includes an electron injection layer, a first electron transport layer and a second electron transport layer arranged in sequence, the electron injection layer is close to the cathode side, and at least one of the materials of the second electron transport layer contacts the first main material to form a second interface radical complex.

6. The blue organic electroluminescent device according to claim 5, characterized in that: The material of the second hole transport layer includes at least one compound containing a carbazole group, an aromatic amine group, a phenoxazine group, a carbazole derivative group, an aromatic amine derivative group, and a phenoxazine derivative group, and the triplet energy level of the material of the second hole transport layer is higher than 2.5 eV; And / or, the material of the second electron transport layer is selected from at least one of a triazine group, a phosphorus oxide group, a benzimidazole group, a triazine derivative group, a phosphorus oxide derivative group, and a benzimidazole derivative group, and the triplet energy level of the material of the second electron transport layer is higher than 2.5 eV.

7. The blue organic electroluminescent device according to claim 5, characterized in that: The thickness of the first hole transport layer is greater than the thickness of the second hole transport layer; and / or, the thickness of the first electron transport layer is greater than the thickness of the second electron transport layer; And / or, the thickness of the light-emitting unit is 10 to 70 nm.

8. The blue organic electroluminescent device according to any one of claims 1 to 7, characterized in that: The guest material includes a phosphorescent material; And / or, the guest material includes a phosphorescent material and a fluorescent material, and the mass ratio of the fluorescent material to the phosphorescent material is 1:(2-40).

9. The blue organic electroluminescent device according to any one of claims 1 to 7, characterized in that: The light-emitting material further includes a third component in addition to the host material and the guest material. The third component includes at least one of a thermally activated delayed fluorescent material and a phosphorescent light-emitting material and is different from both the host material and the guest material.

10. The blue organic electroluminescent device according to claim 9, characterized in that: The mass proportion of the third component in the light-emitting layer is 5% to 40%.

11. An organic light-emitting display device comprising the blue organic electroluminescent device according to any one of claims 1 to 10.

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