Light-emitting device, display panel and display device

Abstract

The invention discloses a light-emitting device, a display panel and a display device. The device comprises a first hole injection layer, a first light-emitting layer, a first hole blocking layer and a first electron injection layer which are arranged in a stacked mode. The first light-emitting layer comprises a host material and a guest material; the hole blocking material of the first hole blocking layer meets the following condition: T1 (HBM) is less than T1 (Guest); hOMO (Host) is less than HOMO (HBM); lUMO (Host) is less than LUMO (HBM); t1 (HBM) represents the triplet state energy level of the hole blocking material, and T1 (Guest) represents the triplet state energy level of the guest material; hOMO (Host) represents the highest occupied molecular orbital energy level of the host material, and HOMO (HBM) represents the highest occupied molecular orbital energy level of the hole blocking material; lUMO (Host) represents the lowest occupied molecular orbital energy level of the host material, and LUMO (HBM) represents the lowest occupied molecular orbital energy level of the hole blocking material. Through energy level cooperation of the host material, the guest material and the hole blocking layer material in the light-emitting layer, the device can emit light more stably, the light-emitting efficiency is improved, and the service life of the device is prolonged.

Description

Technical Field

[0001] The present invention belongs to the technical field of display, and particularly relates to a light-emitting device, a display panel, and a display device. Background Art

[0002] PhOLED has bright colors and high efficiency, and has been widely used in display and lighting applications. Compared with red PhOLED and green PhOLED, the device life of blue PhOLED is extremely short and it has not been applied yet. The main energy driving mechanisms that cause the short life of blue PhOLED are triplet-triplet annihilation (TTA) and / or triplet-polaron annihilation (TPA). These reactions approximately double the energy of the excited state to reach about 6.0 eV, which is sufficient to break the intramolecular bonds and convert the organic molecules into non-radiative quenching centers, resulting in an extremely short device life. In order to minimize the occurrence probability of high-energy annihilation events while maintaining high efficiency, the triplet exciton density in the light-emitting layer should be reduced to avoid triplet accumulation. Summary of the Invention

[0003] An object of the embodiments of the present invention is to provide a light-emitting device, a display panel, and a display device to solve the problem of short service life of the light-emitting device.

[0004] In a first aspect, an embodiment of the present invention provides a light-emitting device, including:

[0005] A first hole injection layer, a first light-emitting layer, a first hole blocking layer, and a first electron injection layer that are stacked;

[0006] The first light-emitting layer includes a host material and a guest material;

[0007] The hole blocking material of the first hole blocking layer satisfies:

[0008] T1(HBM) < T1(Guest);

[0009] |HOMO(Host)| < |HOMO(HBM)|;

[0010] |LUMO(Host)| < |LUMO(HBM)|;

[0011] Wherein, T1(HBM) represents the triplet energy level of the hole blocking material, and T1(Guest) represents the triplet energy level of the guest material;

[0012] HOMO(Host) represents the highest occupied molecular orbital energy level of the host material, and HOMO(HBM) represents the highest occupied molecular orbital energy level of the hole blocking material;

[0013] LUMO(Host) represents the lowest unoccupied molecular orbital energy level of the host material, and LUMO(HBM) represents the lowest unoccupied molecular orbital energy level of the hole-blocking material.

[0014] Optionally, |HOMO(HBM)| - |HOMO(Host)| > 0.3 eV and |LUMO(HBM)| - |LUMO(Host)| ≤ 0.2 eV.

[0015] Optionally, T1(Host) > T1(Guest), where T1(Host) represents the triplet energy level of the host material and T1(Guest) represents the triplet energy level of the guest material; and / or

[0016] |HOMO(Guest)| < |HOMO(Host)|, where HOMO(Host) represents the highest occupied molecular orbital energy level of the host material and HOMO(Guest) represents the highest occupied molecular orbital energy level of the guest material; and / or

[0017] |LUMO(Host)| < |LUMO(Guest)|, where LUMO(Host) represents the lowest unoccupied molecular orbital energy level of the host material and LUMO(Guest) represents the lowest unoccupied molecular orbital energy level of the guest material; and / or

[0018] It further includes a first electron transport layer disposed between the first electron injection layer and the first hole-blocking layer, and |LUMO(ETM)| > |LUMO(HBM)|, where LUMO(ETM) represents the lowest unoccupied molecular orbital energy level of the electron transport material and LUMO(HBM) represents the lowest unoccupied molecular orbital energy level of the hole-blocking material.

[0019] Optionally, T1(Host) - T1(Guest) > 0.2 eV.

[0020] Optionally, |HOMO(Host)| - |HOMO(Guest)| > 0.3 eV.

[0021] Optionally, |LUMO(Guest)| - |LUMO(Host)| > 0.3 eV and |LUMO(ETM)| - |LUMO(HBM)| < 0.2 eV.

[0022] Optionally, the structure of the hole-blocking material includes at least one of D-A, D-π-A, A-D-A, A-π-D-A;

[0023] where D includes pyrenyl, triphenylenyl, fluorenyl, anthracenyl, phenanthrenyl or perylenyl;

[0024] A includes: pyrazino[2,3-f]phthalazinyl, benzo[g]phthalazinyl, phthalazinyl, acridinyl, phenazinyl, dibenzo-γ-pyrone-4-yl, 1,8-naphthyridinyl or 1,5-naphthyridinyl;

[0025] π is selected from phenyl, phenyl with a substituent group, or dibenzo six-membered heterocyclic group; and / or

[0026] The guest material includes at least one of a carbene iridium(III) complex and a carbene platinum(II) complex;

[0027] The carbene iridium(III) complex includes: Ir(X) 2 (L), and the carbene platinum(II) complex includes: Pt(X)(L);

[0028] X is:

[0029] wherein, R1, R2, and R3 are each independently hydrogen, alkyl, alkenyl, alkynyl, substituted or unsubstituted aryl, substituted or unsubstituted heteroaryl; R2 can form a ring with R1 and R3; Ar is substituted or unsubstituted aryl, substituted or unsubstituted heteroaryl.

[0030] Optionally, the light-emitting device further includes:

[0031] A first hole transport layer, which is disposed between the first hole injection layer and the first light-emitting layer; and / or

[0032] A first electron transport layer, which is disposed between the first electron injection layer and the first hole blocking layer; and / or

[0033] A first electron blocking layer, which is disposed between the first hole transport layer and the first light-emitting layer.

[0034] Optionally, the light-emitting device further includes:

[0035] A charge generation layer and a second light-emitting layer, the charge generation layer is disposed on a side of the first hole blocking layer away from the first light-emitting layer;

[0036] The second light-emitting layer is disposed on a side of the charge generation layer away from the first light-emitting layer; the first electron injection layer is disposed on a side of the second light-emitting layer away from the first hole blocking layer.

[0037] In a second aspect, an embodiment of the present invention provides a display panel, including:

[0038] The light-emitting device described in the above embodiment.

[0039] In a third aspect, an embodiment of the present invention provides a display device, including:

[0040] The display panel described in the above embodiment.

[0041] The light-emitting device according to the embodiment of the present invention includes a first hole injection layer, a first light-emitting layer, a first hole blocking layer, and a first electron injection layer which are stacked; the first light-emitting layer includes a host material and a guest material; the hole blocking material of the first hole blocking layer satisfies: T1(HBM) < T1(Guest); |HOMO(Host)| < |HOMO(HBM)|; |LUMO(Host)| < |LUMO(HBM)|; where T1(HBM) represents the triplet energy level of the hole blocking material, T1(Guest) represents the triplet energy level of the guest material; HOMO(Host) represents the highest occupied molecular orbital energy level of the host material, HOMO(HBM) represents the highest occupied molecular orbital energy level of the hole blocking material; LUMO(Host) represents the lowest unoccupied molecular orbital energy level of the host material, and LUMO(HBM) represents the lowest unoccupied molecular orbital energy level of the hole blocking material. By setting the energy level matching of the host material, the guest material in the first light-emitting layer and the material of the first hole blocking layer, the triplet energy level of the hole blocking material is lower than that of the guest material, the density of triplet excitons in the light-emitting layer can be reduced, the light emission of the light-emitting device can be made more stable, the light-emitting efficiency can be improved, and the service life of the device can be extended. Description of the Drawings

[0042] Figure 1 It is a schematic structural diagram of the light-emitting device in the embodiment of the present invention;

[0043] Figure 2 It is another schematic structural diagram of the light-emitting device in the embodiment of the present invention;

[0044] Figure 3 It is a schematic structural diagram of the light-emitting device in the embodiment of the present invention;

[0045] Figure 4 It is another schematic structural diagram of the light-emitting device in the embodiment of the present invention;

[0046] Figure 5 It is the lifetime decay curve of the light-emitting device in Embodiment 2. Detailed Embodiments

[0047] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without making creative efforts fall within the protection scope of the present invention.

[0048] The terms "first", "second", etc. in the description and claims of the present invention are used to distinguish similar objects, rather than to describe a specific order or sequence. It should be understood that such data can be interchanged under appropriate circumstances so that the embodiments of the present invention can be implemented in an order other than those illustrated or described herein. In addition, "and / or" in the description and claims means at least one of the connected objects, and the character " / " generally indicates an "or" relationship between the associated objects before and after.

[0049] The light-emitting device according to an embodiment of the present invention, such as Figure 1 shown, includes:

[0050] A first hole injection layer 11, a first light-emitting layer 14, a first hole blocking layer 17, and a first electron injection layer 15 that are stacked; the first light-emitting layer 14 includes a host material and a guest material; the hole blocking material of the first hole blocking layer satisfies:

[0051] T1(HBM) < T1(Guest); that is, T1(Guest) - T1(HBM) > 0 eV;

[0052] |HOMO(Host)| < |HOMO(HBM)|;

[0053] |LUMO(Host)| < |LUMO(HBM)|;

[0054] Wherein, T1(HBM) represents the triplet energy level of the hole blocking material, T1(Guest) represents the triplet energy level of the guest material; HOMO(Host) represents the highest occupied molecular orbital energy level of the host material, HOMO(HBM) represents the highest occupied molecular orbital energy level of the hole blocking material; LUMO(Host) represents the lowest unoccupied molecular orbital energy level of the host material, and LUMO(HBM) represents the lowest unoccupied molecular orbital energy level of the hole blocking material.

[0055] In the light-emitting device according to an embodiment of the present invention, by setting the energy level matching of the host material, the guest material in the first light-emitting layer and the material of the first hole blocking layer, the triplet energy level of the hole blocking material is lower than the triplet energy level of the guest material, the density of triplet excitons in the light-emitting layer can be reduced, the light emission of the light-emitting device can be made more stable, the light emission efficiency can be improved, and the service life of the device can be extended.

[0056] In some embodiments, |HOMO(HBM)| - |HOMO(Host)| > 0.3 eV and |LUMO(HBM)| - |LUMO(Host)| ≤ 0.2 eV.

[0057] In other embodiments, T1(Host) > T1(Guest), where T1(Host) represents the triplet energy level of the host material and T1(Guest) represents the triplet energy level of the guest material. The host material can be a hole-type material (P-type material) and an electron-type material (N-type material) with thermally activated delayed fluorescence ( TADF ) properties. T1(Host) of the host material can be the lower value of T1 of both the hole-type material and the N-type material with TADF properties. The hole-type material can satisfy the condition that the hole mobility is at least one order of magnitude higher than the electron mobility. The electron-type material with TADF properties can satisfy the condition that ΔEST < 0.3 eV and the electron mobility is at least one order of magnitude higher than its hole mobility. The hole mobility of the hole-type material and the electron mobility of the electron-type material with TADF properties can be within one order of magnitude. The hole-type material and the electron-type material with TADF properties do not form an exciplex and can satisfy ||HOMO(P) – LUMO(N)| - Epeak(P)| ≤ 0.3 eV, where Epeak refers to the energy intensity corresponding to the peak of the PL spectrum of the material. The hole blocking layer has good electron transport and hole blocking effects, and the excitons in the light-emitting layer can leak into this layer. The lifetime range of the triplet excitons of the hole blocking material can be 0.1 ms < τ < 10 s.

[0058] Optionally, |HOMO(Guest)| < |HOMO(Host)|, where HOMO(Host) represents the highest occupied molecular orbital energy level of the host material and HOMO(Guest) represents the highest occupied molecular orbital energy level of the guest material. |HOMO(Host)| can be the smaller value of the absolute values of HOMO of both the hole-type material and the N-type material with TADF properties.

[0059] Optionally, |LUMO(Host)| < |LUMO(Guest)|, where LUMO(Host) represents the lowest occupied molecular orbital energy level of the host material and LUMO(Guest) represents the lowest occupied molecular orbital energy level of the guest material. |LUMO(Host)| can be the larger value of the absolute values of LUMO of both the hole-type material and the N-type material with TADF properties.

[0060] Optionally, a first electron transport layer may also be included. The first electron transport layer is disposed between the first electron injection layer and the first hole blocking layer, and |LUMO(ETM)| > |LUMO(HBM)|, where LUMO(ETM) represents the lowest unoccupied molecular orbital energy level of the electron transport material, and LUMO(HBM) represents the lowest unoccupied molecular orbital energy level of the hole blocking material.

[0061] Optionally, T1(Host) - T1(Guest) > 0.2 eV.

[0062] Optionally, |HOMO(Host)| - |HOMO(Guest)| > 0.3 eV.

[0063] Optionally, |LUMO(Guest)| - |LUMO(Host)| > 0.3 eV, and |LUMO(ETM)| - |LUMO(HBM)| < 0.2 eV.

[0064] In an embodiment of the present invention, the structure of the hole blocking material may include at least one of D-A, D-π-A, A-D-A, and A-π-D-A;

[0065] wherein, D includes: pyrenyl, triphenylenyl, -yl, anthryl, phenanthryl, or perylenyl;

[0066] A includes: pyrazino-phenanthrolinyl, benzo-phenanthrolinyl, phenanthrolinyl, acridinyl, phenazinyl, dibenzo-γ-pyroneyl, 1,8-naphthyridinyl, or 1,5-naphthyridinyl;

[0067] π is selected from phenyl, phenyl containing a substituent group, or dibenzo-hexacyclic heteroaryl;

[0068] For example, the hole blocking material may be selected from the following compound materials:

[0069]

[0070]

[0071] Optionally, the guest material includes at least one of a carbene iridium(III) complex and a carbene platinum(II) complex;

[0072] The carbene iridium(III) complex includes: Ir(X) 2 (L), and the carbene platinum(II) complex includes: Pt(X)(L);

[0073] X is:

[0074] Among them, R1, R2, and R3 are each independently hydrogen, alkyl, alkenyl, alkynyl, substituted or unsubstituted aryl, or substituted or unsubstituted heteroaryl; R2 can form a ring with R1 and R3; Ar is substituted or unsubstituted aryl or substituted or unsubstituted heteroaryl. The main peak range of the photoluminescence spectrum of the guest material can be 450 - 480 nm. The carbene iridium(III) complex or carbene platinum(II) complex has a high bond energy and a stable molecular structure. The combination of the p-type host and the TADF n-type host is beneficial to carrier transport, reduces the driving voltage, expands the exciton recombination center, inhibits the formation of adducts and charge traps, and inhibits TTA and TPA, thereby increasing the device lifetime and efficiency and reducing efficiency roll-off.

[0075] For example, the guest material can be selected from the following compound materials:

[0076]

[0077] In some embodiments, as Figure 1 shown, the light-emitting device further includes:

[0078] A first hole transport layer 12, which is disposed between the first hole injection layer 11 and the first light-emitting layer 14.

[0079] Optionally, the light-emitting device further includes: a first electron transport layer 16, which is disposed between the first electron injection layer 15 and the first hole blocking layer 17.

[0080] Optionally, the light-emitting device further includes: a first electron blocking layer 13, which is disposed between the first hole transport layer 12 and the first light-emitting layer 14.

[0081] In an embodiment of the present invention, the light-emitting device may further include:

[0082] An anode 10 and a cathode 20. The anode 10 is disposed on the side of the first hole injection layer 11 away from the first light-emitting layer 14, and the cathode 20 is disposed on the side of the first electron injection layer 15 away from the first light-emitting layer 14.

[0083] The anode is an electrode material with a high work function, and the electrode can be Ag / ITO, Ag / IZO, Ag / SnO 2 , Ag / ZnO, Al / ITO, Al / IZO. The thickness of the metal layer in the electrode can be 50 - 200 nm, and the thickness of the oxide layer can be 5 - 20 nm. The average reflectivity reference value of the anode in the visible light region can be 85% - 95%. The hole injection layer (HIL): Its main function is to reduce the hole injection barrier and improve the hole injection efficiency. HATCN, MnO 3, hole injection materials such as CuPc; p-type doping can also be carried out in the hole transport material, such as NPB:F4TCNQ, TAPC:MnO 3 etc. The thickness of the hole injection layer is 5 nm to 20 nm, and the p-type doping concentration is 0.5% to 10%. Hole transport layer (HTL): Its main function is to transfer holes. This layer can be prepared by evaporation using carbazole-based materials with higher hole mobility. The thickness is 20 - 150 nm. Electron blocking layer (EBL): Its main function is to block electrons and excitons generated in the light-emitting layer and transfer holes. The thickness can be 1 - 10 nm. The lowest triplet excited state (T1) energy of the material of this layer is greater than the lowest triplet excited state (T1) energy of the transition metal complex material in the light-emitting layer, and the difference is greater than or equal to 0.2 eV. The HOMO energy level of the material of this layer is deeper than the HOMO energy level of the host material in the light-emitting layer, and the difference is less than or equal to 0.2 eV.

[0084] N-type charge generation layer (NCGL): Electron transport materials are doped with low work function active metals. The active metals can be Li, Ca, Yb, etc. The doping ratio is 0.6% - 2%, and the thickness is 10 - 20 nm. P-type charge generation layer (PCGL): It is formed by doping hole transport materials with p-type dopants such as molybdenum oxide, etc. The doping ratio is 5% - 15%, and the thickness is 10 - 20 nm. Electron injection layer (EIL): Its main function is to inject electrons. The materials of the electron injection layer can include Yb, Li, LiF, NaCl, CsF, Li 2 O, BaO, Liq, etc. materials, or combinations of these materials, with a thickness of 0.5 - 2 nm. Cathode: The cathode material is an electrode material with a low work function, such as Mg, Ag, Al, Al-Li, Ca, Mg:In, Mg:Ag, etc. The thickness of this layer is 10 - 20 nm, and it can be prepared using alloys such as Mg:Ag. The adjustment ratio of Mg:Ag is 3:7 - 1:9. Light extraction layer (CPL): In the case of a top-emitting device, a cathode covering layer should also be evaporated. Its main function is to improve the light extraction efficiency and protect the cathode. The thickness of this layer is 50 - 100 nm. Preferably, the refractive index of the material of this layer at 530 nm should be greater than 1.9. Hole blocking layer (HBL): This layer has good electron transport and hole blocking effects.

[0085] Electron transport layer (ETL): This layer has good electron transport and exciton blocking effects. This layer is Liq doped in the electron transport material, and the doping ratio is 10:1 - 1:1, with a thickness of 10 - 70 nm.

[0086] Liq ：

[0087] The electron transport material can be imidazole, pyridine, pyrimidine, triazine, thiophene, azine, derivatives, etc. Light-emitting layer (EML): The thickness can be 5 to 30 nm, and the light-emitting layer can include a host material and a guest material.

[0088] In an embodiment of the present invention, the light-emitting device further includes:

[0089] A charge generation layer and a second light-emitting layer 24, and the charge generation layer is disposed on a side of the first hole blocking layer 17 away from the first light-emitting layer 14;

[0090] The second light-emitting layer 24 is disposed on a side of the charge generation layer away from the first light-emitting layer 14; the first electron injection layer 15 is disposed on a side of the second light-emitting layer 24 away from the first hole blocking layer 17.

[0091] In an embodiment of the present invention, as Figure 2 shown, the light-emitting device includes:

[0092] An anode 10, a first hole injection layer 11, a first hole transport layer 12, a first electron blocking layer 13, a first light-emitting layer 14, a first hole blocking layer 17, a first electron transport layer 16, a charge generation layer, a second hole transport layer 22, a second electron blocking layer 23, a second light-emitting layer 24, a second hole blocking layer 27, a second electron transport layer 26, a first electron injection layer 15, a cathode 20, and a light extraction layer 30, which are stacked.

[0093] The charge generation layer may include an N-type charge generation layer 41 (NCGL) and a P-type charge generation layer 42 (PCGL), and the N-type charge generation layer may be disposed close to the first electron transport layer 16.

[0094] The display panel according to an embodiment of the present invention includes:

[0095] The light-emitting device described in the above embodiment. The display panel having the light-emitting device described in the above embodiment makes the light emission of the light-emitting device more stable, improves the light emission efficiency, and extends the service life of the device.

[0096] The display device according to an embodiment of the present invention includes:

[0097] The display panel described in the above embodiment. The display device having the display panel described in the above embodiment has more stable light emission, high light emission efficiency, and a long service life of the device.

[0098] The light-emitting device in the present invention will be further described below by way of examples.

[0099] P-type material:

[0100] N-type material:

[0101] Photophysical properties of different materials:

[0102] Material τ / ms <![CDATA[T 1 / eV]]> HOMO LUMO P / 3.1 -6.1 -2.5 N / 3.2 -6.0 -2.6 Guest / 2.8 -5.7 -3.0 HB1 0.08 2.6 -6.4 -2.8 HB2 274 3.3 -6.5 -2.7 HB3 355 2.5 -6.1 -2.8 HB4 106 2.4 -6.4 -3.2 HB5 230 2.5 -6.4 -2.8 ET / / -6.7 -2.7

[0103] The structure of the light-emitting device is as Figure 3 shown, and the film layers in the device are stacked. The specific film layers of the device are as follows:

[0104] Comparative Example 1:

[0105] ITO / Ag / ITO(150nm) / HIL(10nm) / HTL(100nm) / EBL(5nm) / EML(20nm) / HB1(5nm) / ETL(35nm) / EIL(1nm) / Mg:Ag(13nm) / CPL(75nm), and the HBL layer is selected as the HB1 layer.

[0106] Comparative Example 2:

[0107] ITO / Ag / ITO(150nm) / HIL(10nm) / HTL(100nm) / EBL(5nm) / EML(20nm) / HB2(5nm) / ETL(35nm) / EIL(1nm) / Mg:Ag(13nm) / CPL(75nm), and the HBL layer is selected as the HB2 layer.

[0108] Comparative Example 3:

[0109] ITO / Ag / ITO(150nm) / HIL(10nm) / HTL(100nm) / EBL(5nm) / EML(20nm) / HB3(5nm) / ETL(35nm) / EIL(1nm) / Mg:Ag(13nm) / CPL(75nm), and the HBL layer is selected as the HB3 layer.

[0110] Comparative Example 4:

[0111] ITO / Ag / ITO(150nm) / HIL(10nm) / HTL(100nm) / EBL(5nm) / EML(20nm) / HB4(5nm) / ETL(35nm) / EIL(1nm) / Mg:Ag(13nm) / CPL(75nm), and the HBL layer is selected as the HB4 layer.

[0112] Example 1: ITO / Ag / ITO(150nm) / HIL(10nm) / HTL(100nm) / EBL(5nm) / EML(20nm) / HB5(5nm) / ETL(35nm) / EIL(1nm) / Mg:Ag(13nm) / CPL(75nm), and the HBL layer is selected as the HB5 layer.

[0113] The test results of the comparative examples and the examples are shown in Table 1.

[0114] Table 1 Test Results of Comparative Examples and Examples

[0115] Device Voltage / (V) CIEx CIEy CE / (Cd / A) <![CDATA[LT 95 / (h)@35mA / cm 2 > Comparative Example 1 3.7 0.134 0.045 16 54 Comparative Example 2 3.6 0.133 0.045 17 50 Comparative Example 3 3.8 0.134 0.046 20 62 Comparative Example 4 3.7 0.135 0.045 19 64 Example 1 3.5 0.134 0.045 23 73

[0116] As can be seen from Table 1, the lifetime of the triplet excited state of the hole blocking layer material in the example is relatively long, the energy of the first triplet excited state is lower than that of the triplet first excited state of the guest material, and the HOMO and LUMO energy levels match. Therefore, the device has excellent carrier transport properties, a wide exciton recombination center, TTA and TPA are suppressed, and the device has the most excellent lifetime and efficiency.

[0117] The structure of the light-emitting device is as Figure 4 shown, and the film layers in the device are stacked, and the specific film layers of the device are as follows:

[0118] Comparative Example 5:

[0119] ITO / Ag / ITO(150nm) / HIL(10nm) / HTL1(30nm) / EBL1(30nm) / EML1(42nm) / HB1(5nm) / ETL1(15nm) / NCGL(15nm) / PCGL(10nm) / HTL2(35nm) / EBL2(x nm) / EML2(42nm) / HB1(5nm) / ETL2(35nm) / EIL(1nm) / Mg:Ag(1:9,13nm) / CPL(75nm), and the HBL1 layer and the HBL2 layer are selected as the HB1 layer.

[0120] Comparative Example 6:

[0121] ITO / Ag / ITO(150nm) / HIL(10nm) / HTL1(30nm) / EBL1(30nm) / EML1(42nm) / HB2(5nm) / ETL1(15nm) / NCGL(15nm) / PCGL(10nm) / HTL2(35nm) / EBL2(x nm) / EML2(42nm) / HB2(5nm) / ETL2(35nm) / EIL(1nm) / Mg:Ag(1:9,13nm) / CPL(75nm), and the HBL1 layer and the HBL2 layer are selected as the HB2 layer.

[0122] Comparative Example 7:

[0123] ITO / Ag / ITO(150nm) / HIL(10nm) / HTL1(30nm) / EBL1(30nm) / EML1(42nm) / HB3(5nm) / ETL1(15nm) / NCGL(15nm) / PCGL(10nm) / HTL2(35nm) / EBL2(x nm) / EML2(42nm) / HB3(5nm) / ETL2(35nm) / EIL(1nm) / Mg:Ag(1:9,13nm) / CPL(75nm), the HBL1 layer and the HBL2 layer are selected as the HB3 layer.

[0124] Comparative Example 8:

[0125] ITO / Ag / ITO(150nm) / HIL(10nm) / HTL1(30nm) / EBL1(30nm) / EML1(42nm) / HB4(5nm) / ETL1(15nm) / NCGL(15nm) / PCGL(10nm) / HTL2(35nm) / EBL2(x nm) / EML2(42nm) / HB4(5nm) / ETL2(35nm) / EIL(1nm) / Mg:Ag(1:9,13nm) / CPL(75nm), the HBL1 layer and the HBL2 layer are selected as the HB4 layer.

[0126] Example 2:

[0127] ITO / Ag / ITO(150nm) / HIL(10nm) / HTL1(30nm) / EBL1(30nm) / EML1(42nm) / HB5(5nm) / ETL1(15nm) / NCGL(15nm) / PCGL(10nm) / HTL2(35nm) / EBL2(x nm) / EML2(42nm) / HB5(5nm) / ETL2(35nm) / EIL(1nm) / Mg:Ag(1:9,13nm) / CPL(75nm), the HBL1 layer and the HBL2 layer are selected as the HB5 layer.

[0128] The thickness x of the second electron blocking layer (EBL2) ranges from 20 to 50 nm. For example, the thickness x of the second electron blocking layer (EBL2) is 30 nm, aiming to keep the CIE color coordinates of the device basically consistent.

[0129] The test results of the comparative examples and the examples are shown in Table 2.

[0130] Table 2 Test Results of Comparative Examples and Examples

[0131] Device Voltage / (V) CIEx CIEy CE / (Cd / A) <![CDATA[LT 95 / (h)@35 mA / cm 2 > Comparative Example 5 7.1 0.136 0.045 24 103 Comparative Example 6 7.0 0.135 0.045 23 107 Comparative Example 7 7.2 0.135 0.046 27 119 Comparative Example 8 7.1 0.134 0.046 28 123 Example 2 6.8 0.135 0.046 35 140

[0132] As can be seen from Table 2, the triplet excited state of the hole blocking layer material in the embodiment has a relatively long lifetime, the energy of the first triplet excited state is lower than that of the triplet first excited state of the guest material, and the HOMO and LUMO energy levels match. Therefore, the carrier transport properties of the device are excellent, the exciton recombination center is wide, TTA and TPA are suppressed, and the lifetime and efficiency of the device are the most excellent. Figure 5 It is the lifetime decay curve of the light-emitting device in Example 2. From the lifetime decay curve of the device, it can be seen that the service life of the device is long.

[0133] The embodiments of the present invention have been described above in conjunction with the accompanying drawings. However, the present invention is not limited to the above specific embodiments. The above specific embodiments are merely illustrative and not restrictive. Under the inspiration of the present invention, those of ordinary skill in the art can also make many forms without departing from the spirit and scope protected by the claims of the present invention, and all of them belong to the protection scope of the present invention.

Claims

1. A light emitting device, characterized in that: include: A first hole injection layer, a first light-emitting layer, a first hole blocking layer, and a first electron injection layer are stacked; The first light-emitting layer includes a host material and a guest material; The hole blocking material of the first hole blocking layer satisfies: T1(HBM)<T1(Guest); |HOMO(Host)|<|HOMO(HBM|; |LUMO(Host)|<|LUMO(HBM)|; Wherein, T1(HBM) represents the triplet energy level of the hole blocking material, and T1(Guest) represents the triplet energy level of the guest material; HOMO (Host) represents the highest occupied molecular orbital energy level of the host material, and HOMO (HBM) represents the highest occupied molecular orbital energy level of the hole blocking material; LUMO (Host) represents the lowest occupied molecular orbital energy level of the host material, and LUMO (HBM) represents the lowest occupied molecular orbital energy level of the hole blocking material.

2. The light emitting device according to claim 1, characterized in that: |HOMO(HBM)|-|HOMO(Host)|>0.3eV, |LUMO(HBM)|-|LUMO(Host)|≤0.2eV.

3. The light emitting device according to claim 1, characterized in that: T1(Host)>T1(Guest), T1(Host) represents the triplet energy level of the host material, T1(Guest) represents the triplet energy level of the guest material; and / or |HOMO(Guest)|<|HOMO(Host)|, HOMO(Host) represents the highest occupied molecular orbital energy level of the host material, HOMO(Guest) represents the highest occupied molecular orbital energy level of the guest material; and / or |LUMO(Host)|<|LUMO(Guest)|, LUMO(Host) represents the lowest occupied molecular orbital energy level of the host material, LUMO(Guest) represents the lowest occupied molecular orbital energy level of the guest material; and / or It also includes a first electron transport layer, which is arranged between the first electron injection layer and the first hole blocking layer, |LUMO(ETM)|>|LUMO(HBM)|, LUMO(ETM) represents the lowest occupied molecular orbital energy level of the electron transport material, and LUMO(HBM) represents the lowest occupied molecular orbital energy level of the hole blocking material.

4. The light emitting device according to claim 3, characterized in that: T1(Host)-T1(Guest)>0.2eV.

5. The light emitting device according to claim 3, characterized in that: |HOMO(Host)|-|HOMO(Guest)|>0.3eV.

6. The light emitting device according to claim 3, characterized in that: |LUMO(Guest)|-|LUMO(Host)|>0.3eV, |LUMO(ETM)|-|LUMO(HBM)|<0.2eV.

7. The light emitting device according to claim 1, characterized in that: The structure of the hole blocking material includes at least one of DA, D-π-A, ADA, and A-π-DA; Wherein, D includes: pyrenyl, triphenylene, phenanthrenyl, anthracenyl, phenanthrenyl or peryl; A includes: pyrazinophenanthroline, benzophenanthroline, o-phenanthroline, acridinyl, phenazine, dibenzo-γ-pyrone, 1,8-naphthyridinyl or 1,5-naphthyridinyl; π is selected from phenyl, phenyl containing a substituted group or dibenzo six-membered heterocyclic group; and / or The guest material includes at least one of a carbene iridium (III) complex and a carbene platinum (II) complex; Carbene iridium (III) complexes include: Ir(X)2(L), carbene platinum (II) complexes include: Pt(X)(L); X is: Wherein, R1, R2, and R3 are each independently hydrogen, alkyl, alkenyl, alkynyl, substituted or unsubstituted aryl, or substituted or unsubstituted heteroaryl; R2 can form a ring with R1 and R3; and Ar is substituted or unsubstituted aryl, or substituted or unsubstituted heteroaryl.

8. The light emitting device according to claim 1, characterized in that: Also includes: A first hole transport layer, wherein the first hole transport layer is disposed between the first hole injection layer and the first light emitting layer; and / or A first electron transport layer is disposed between the first electron injection layer and the first hole blocking layer.

9. The light emitting device according to claim 1, characterized in that: Also includes: A charge generation layer and a second light-emitting layer, wherein the charge generation layer is arranged on a side of the first hole blocking layer away from the first light-emitting layer; The second light-emitting layer is disposed on a side of the charge generating layer away from the first light-emitting layer; and the first electron injection layer is disposed on a side of the second light-emitting layer away from the first hole blocking layer.

10. A display panel, characterized in that: include: The light emitting device according to any one of claims 1 to 9.

11. A display device, characterized in that: include: The display panel as claimed in claim 10.

Images