Organic red electroluminescent host material, light-emitting layer, light-emitting device and display device

Abstract

The application discloses an organic electroluminescent red host material, a light-emitting layer, a light-emitting device and a display device. The host material comprises one or a combination of structures shown in the following formulae: the scheme can at least solve the matching problem of the organic electroluminescent red device host material and the guest material, and further optimizes the voltage, efficiency, service life and other performances of the organic electroluminescent red device.

Description

Technical Field

[0001] This invention relates to the field of display technology. More specifically, it relates to an organic electroluminescent red light host material, a light-emitting layer, a light-emitting device, and a display apparatus. Background Technology

[0002] Currently mass-produced OLED red light devices utilize phosphorescence, employing a premixed material as the host material. This material comprises both hole-type and electron-type host materials, which interact to form exciton complexes. The guest material is an iridium metal complex; due to the presence of heavy metal elements, it achieves room-temperature triplet emission. Holes and electrons recombine in the host material to form excitons, which are then transferred to the guest material for emission.

[0003] Because the triplet energy level of red light guest materials is low, in order to achieve efficient energy transfer between the host and guest materials, the host material needs to be designed to reduce its triplet energy level. At the same time, it is also necessary to ensure its molecular stability and high molecular mobility, thereby extending the device lifetime and improving the device's working efficiency. Summary of the Invention

[0004] Based on the above facts, the purpose of this invention is to provide an organic electroluminescent red light host material, an emissive layer, an emissive device, and a display device, so as to at least solve the matching problem between the host material and the guest material of the organic electroluminescent red light device, and at the same time further optimize the performance of the organic electroluminescent red light device in terms of voltage, efficiency, lifespan, etc.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] An organic electroluminescent red light host material, characterized in that the host material comprises one or a combination of the following structures:

[0007]

[0008]

[0009] in:

[0010] X1-X13 are each independently selected from C-Ar1 or N; and two adjacent X1-X13 can form the following fused rings:

[0011] Where X is selected from O or S; * indicates the connection site of each of the two adjacent X1-X13 that form a fused ring;

[0012] L is selected from O, S, C-Ar2Ar3, N-Ar2 or aryl groups with 6-12 carbon atoms;

[0013] n1 and n2 are each independently selected from integers between 0 and 5, and n1 + n2 ≥ 1;

[0014] n3 are independent integers selected from 0 to 4;

[0015] n4 are independent integers selected from 0 to 6;

[0016] R1, R2, R3 and R4 are each independently selected from hydrogen, deuterium, halogen, alkyl with 1-6 carbon atoms, aryl with 6-20 carbon atoms (substituted or unsubstituted), and heteroaryl with 6-20 carbon atoms (substituted or unsubstituted).

[0017] Ar1, Ar2, and Ar3 are each independently selected from hydrogen, deuterium, alkyl groups with 1-6 carbon atoms, aryl groups with 6-20 carbon atoms (substituted or unsubstituted), and heteroaryl groups with 6-20 carbon atoms (substituted or unsubstituted).

[0018] Optionally, the body material comprises one or a combination of the structures shown in the following formulas:

[0019]

[0020] The definitions of R1, R2, R3, and R4 are as described above;

[0021] n1 is an independent integer selected from 0 to 4; n2 is an independent integer selected from 0 to 5; n3 is an independent integer selected from 0 to 4; and n4 is an independent integer selected from 0 to 6.

[0022] Alternatively, the structure shown in Equation 1 may be represented by one of the following equations:

[0023]

[0024]

[0025] Alternatively, the structure shown in Equation 2 may be represented by one of the following equations:

[0026]

[0027]

[0028]

[0029] Alternatively, the structure shown in Equation 3 may be represented by one of the following equations:

[0030]

[0031] Alternatively, the structure shown in Equation 4 is as follows:

[0032]

[0033] Optionally, the main material has one of the structures shown in formulas 5-1 to 5-16:

[0034]

[0035]

[0036] In another aspect, the present invention provides an organic electroluminescent layer, the material of which comprises:

[0037] Main materials; and

[0038] Dopant material incorporated into the host material;

[0039] The host material includes the organic electroluminescent red light host material as described above.

[0040] Optionally, the host material contains a P-type organic semiconductor material and an N-type organic semiconductor material; wherein the P-type organic semiconductor material and / or the N-type organic semiconductor material are selected from the organic electroluminescent host material.

[0041] Optionally, the mass ratio of the P-type organic semiconductor material to the N-type organic semiconductor material is 3:7-7:3.

[0042] Optionally, the N-type organic semiconductor material is selected from the organic electroluminescent red light host material, and in this case, the organic electroluminescent red light host material contains functional groups in its structure. and / or

[0043] The p-type organic semiconductor material is selected from the organic electroluminescent red light host material, and in this case, the structure of the organic electroluminescent red light host material does not contain any functional groups.

[0044] In another aspect, the present invention provides an organic electroluminescent device comprising a red light-emitting layer;

[0045] The red light emitting layer is selected from the organic electroluminescent layer described above.

[0046] In another aspect, the present invention provides a display device comprising the organic electroluminescent device as described above.

[0047] The beneficial effects of this invention are as follows:

[0048] This invention provides an organic electroluminescent red light-emitting host material, an emissive layer, a light-emitting device, and a display device. The organic electroluminescent red light-emitting host material features a low triplet energy level through structural design. Furthermore, bridging groups are introduced at specific positions to form a large-planar polycyclic host material with minimal change in the triplet energy level. This large-planar polycyclic host material increases molecular rigidity, further improving molecular stability and mobility under optical and electrical conditions. The resulting organic electroluminescent device exhibits superior voltage, efficiency, and lifetime. Detailed Implementation

[0049] To illustrate the present invention more clearly, the following description, in conjunction with preferred embodiments, should be understood by those skilled in the art. The specific descriptions below are illustrative rather than restrictive and should not be construed as limiting the scope of protection of the present invention.

[0050] Unless the context otherwise requires, throughout the specification and claims, the term "comprise" and its other forms, such as the third-person singular "comprises" and the present participle "comprising," are interpreted as open-ended and encompassing, meaning "including, but not limited to." In the description of the specification, terms such as "one embodiment," "some embodiments," "exemplary embodiments," "example," "specific example," or "some examples," etc., are intended to indicate that a particular feature, structure, material, or characteristic associated with that embodiment or example is included in at least one embodiment or example of this disclosure. The illustrative representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics mentioned may be included in any suitable manner in any one or more embodiments or examples.

[0051] To address the issue of low triplet energy levels in red light guest materials of OLED red light devices, a matching red light host material with similarly low triplet energy levels is needed to achieve efficient energy transfer between the host and guest materials. Therefore, a suitable host material for OLED red light devices is required. This invention reveals that the design of the host material requires the introduction of large fused-ring segments to lower the triplet energy level, and the size of the triplet energy level of these large fused-ring segments directly determines the triplet energy level of the entire molecule. Since the triplet excitons of the molecule are localized on these large fused-ring segments, the stability of these segments also determines the molecular stability and thus affects the device lifetime.

[0052] Common green light host materials are mostly molecules composed of carbazole fragments, and their structure may contain fragments. Its triplet energy level is relatively high, with a high T1 value; the structure of the red light host material may contain fragments. Compared to the aforementioned green light host material structure containing the aforementioned green light fragments, it has a lower triplet energy level and a lower T1 value. To improve the rigidity of the red light host material molecules, the red light host molecule can be further designed to contain fragments...

[0053] Based on this, one specific embodiment of the present invention provides an organic electroluminescent red light host material, the host material comprising one or a combination of the following structures:

[0054]

[0055] in:

[0056] X1-X13 are each independently selected from C-Ar1 or N; and two adjacent X1-X13 can form the following fused rings:

[0057] Where X is selected from O or S; * indicates the connection site of each of the two adjacent X1-X13 that form a fused ring;

[0058] L is selected from O, S, C-Ar2Ar3, N-Ar2 or aryl groups with 6-12 carbon atoms;

[0059] n1 and n2 are each independently selected from integers between 0 and 5, and n1 + n2 ≥ 1;

[0060] n3 are independent integers selected from 0 to 4;

[0061] n4 are independent integers selected from 0 to 6;

[0062] R1, R2, R3 and R4 are each independently selected from hydrogen, deuterium, halogen, alkyl with 1-6 carbon atoms, aryl with 6-20 carbon atoms (substituted or unsubstituted), and heteroaryl with 6-20 carbon atoms (substituted or unsubstituted).

[0063] Ar1, Ar2, and Ar3 are each independently selected from hydrogen, deuterium, alkyl groups with 1-6 carbon atoms, aryl groups with 6-20 carbon atoms (substituted or unsubstituted), and heteroaryl groups with 6-20 carbon atoms (substituted or unsubstituted).

[0064] In some preferred embodiments, the aryl group having 6-12 carbon atoms includes, but is not limited to, phenyl or naphthyl groups.

[0065] In some preferred embodiments, among the substituted or unsubstituted aryl groups having 6-20 carbon atoms, the unsubstituted aryl groups having 6-20 carbon atoms include, but are not limited to, those selected from... etc.; where "—" represents a connector key.

[0066] In some preferred embodiments, the aryl group having 6-20 carbon atoms, whether substituted or unsubstituted, includes, but is not limited to, those selected from... wait.

[0067] In some preferred embodiments, among the substituted or unsubstituted heteroaryl groups having 6-20 carbon atoms, the unsubstituted heteroaryl groups having 6-20 carbon atoms include, but are not limited to, those selected from... etc.; where "—" represents a connector key.

[0068] In some preferred embodiments, the heteroaryl groups having 6-20 substituted or unsubstituted carbon atoms include, but are not limited to, those selected from... wait.

[0069] In some preferred embodiments, n1 is 1.

[0070] In the aforementioned organic electroluminescent red light host material, the design of its host material structure enables the red light host material to have a low triplet energy level. The structure is formed by oxygen bridges to create rings, which improves the rigidity of the molecules while keeping the triplet energy level relatively stable. This results in a large planar multi-ring host material, which further improves the stability and mobility of the molecules under optical and electrical conditions, and enhances the performance of the fabricated devices (such as lower start-up voltage, higher efficiency, and longer lifespan).

[0071] In some possible implementations, the body material comprises one or a combination of the following structures:

[0072]

[0073] The definitions of R1, R2, R3, and R4 are as described above;

[0074] n1 is an independent integer selected from 0 to 4; n2 is an independent integer selected from 0 to 5; n3 is an independent integer selected from 0 to 4; and n4 is an independent integer selected from 0 to 6.

[0075] The advantages of the two compounds in terms of molecular structure and performance are due to their good molecular planarity, the electron-donating ability of both N and O, and their high hole transport capability. When used in organic electroluminescent devices, these devices have lower voltage and lower power consumption.

[0076] In some possible implementations, the structure shown in Equation 1 is as follows:

[0077]

[0078]

[0079]

[0080] In some possible implementations, the structure shown in Equation 2 is as follows:

[0081]

[0082]

[0083] In some possible implementations, the structure shown in Equation 3 is as follows:

[0084]

[0085] In some possible implementations, the structure shown in Equation 4 is as shown in one of the following equations:

[0086]

[0087] In some possible implementations, the body material has one of the structures shown in Formulas 5-1 to 5-16:

[0088]

[0089]

[0090] The host material having the structure shown in any one of Formulas 5-1 to 5-16 can be used as an N-type organic semiconductor material in red-light organic electroluminescent materials. The resulting organic electroluminescent device has a lower start-up voltage, higher efficiency, and longer lifespan.

[0091] According to another specific embodiment of the present invention, an organic electroluminescent layer is provided, the material of which comprises:

[0092] Main materials; and

[0093] Dopant material incorporated into the host material;

[0094] The host material includes the organic electroluminescent red light host material as described above.

[0095] Because the aforementioned organic electroluminescent host material possesses a low triplet energy level and its large planar multi-ring host structure enhances molecular rigidity, it further improves the stability of the organic electroluminescent host material under optical and electrical conditions, as well as the molecular mobility. Therefore, the organic electroluminescent layer containing it also possesses its inherent properties, and the organic electroluminescent device fabricated from this organic electroluminescent layer can be further optimized in terms of voltage, efficiency, lifetime, and other performance characteristics. Further details are omitted here.

[0096] Furthermore, the host material contains P-type organic semiconductor materials and N-type organic semiconductor materials; wherein the P-type organic semiconductor materials and / or N-type organic semiconductor materials are selected from the organic electroluminescent host material.

[0097] That is, in some examples, the p-type organic semiconductor material in the host material is the organic electroluminescent red light host material, and in this case, the structure of the organic electroluminescent red light host material does not contain any functional groups.

[0098] It is understandable that N-type organic semiconductor materials are a conventional choice at this point, and will not be elaborated upon here.

[0099] In some other examples, the N-type organic semiconductor material in the host material is the organic electroluminescent red light host material, and in this case, the structure of the organic electroluminescent red light host material contains functional groups.

[0100] This structure compared A stronger electron-withdrawing ability allows for better electron transport in the light-emitting layer, resulting in lower device voltage.

[0101] It is understandable that P-type organic semiconductor materials are a conventional choice at this time, and will not be elaborated here.

[0102] In some other examples, the mass ratio of the P-type organic semiconductor material to the N-type organic semiconductor material is 3:7 to 7:3. Exemplary mass ratios of the P-type organic semiconductor material to the N-type organic semiconductor material include, but are not limited to, 1:0.5-1:2, 1:0.5-1:1.5, 1:1-1:2, 1:1.5-1:2, 1:1.5, etc.

[0103] According to another specific embodiment of the present invention, an organic electroluminescent device is provided, which includes a red light emitting layer;

[0104] The red light emitting layer is selected from the organic electroluminescent layer described above.

[0105] It is understood that the organic electroluminescent device may include HIL, HTL, R', R-EML, HBL, ETL, EIL, cathode and CPL arranged in sequence.

[0106] In some examples, the material of the HIL layer may be Thickness includes, but is not limited to, 10nm.

[0107] In some examples, the material of the HTL layer may be The thickness can be 100nm, etc.

[0108] In some examples, the material of the R' layer may be... The thickness can be 80nm, etc.

[0109] In some examples, the thickness of the R-EML layer is 45 nm.

[0110] In some examples, the material of the RD layer may be

[0111] In some examples, the material of the HBL layer may be The thickness can be as thin as 5nm, etc.

[0112] In some examples, the material of the ETL layer may be The thickness can be 30nm, etc.

[0113] In some examples, the cathode material is Yb, 1nm, Mg:Ag (1:9), and the thickness can be 12nm, etc.

[0114] In some examples, the CPL material is The thickness is 65nm.

[0115] According to another specific embodiment of the present invention, a display device is provided, comprising the organic electroluminescent device as described above.

[0116] The technical solution of the present invention will be described below with reference to some specific examples:

[0117] It should be noted that, unless otherwise specified, all materials used in this embodiment are commercially available. The properties of some materials used in the following embodiments and comparative examples are shown in Table 1 below.

[0118] As shown in Table 1, under conditions where the HOMO, LUMO, and T1 values ​​of the p-type and n-type materials are relatively similar, the mobility of the material is approximately one order of magnitude higher than that of the comparative example. The compounds provided in the embodiments of the present invention exhibit even faster molecular mobility. When further applied to organic electroluminescent devices, the resulting devices have lower voltages and higher efficiency.

[0119] Table 1. Material property data

[0120] Material code |HOMO| / eV |LUMO| / eV T1 / eV <![CDATA[Hole mobility / cm 2 / v·s]]> <![CDATA[Electron mobility / cm 2 / v·s]]> RH-P1 5.36 2.32 2.41 <![CDATA[8.2×10 -7 ]]> - RH-P2 5.32 2.35 2.42 <![CDATA[5.5×10 -7 ]]> - RH-P3 5.37 2.31 2.38 <![CDATA[6.6×10 -7 ]]> - RH-P4 5.38 2.33 2.39 <![CDATA[4.7×10 -7 ]]> - RH-P5 5.31 2.34 2.37 <![CDATA[8.6×10 -7 ]]> - RH-P6 5.28 2.37 2.38 <![CDATA[6.2×10 -7 ]]> - RH-N1 5.96 2.91 2.41 <![CDATA[4.2×10 -6 ]]> RH-N2 5.92 2.90 2.42 <![CDATA[4.8×10 -6 ]]> RH-N3 2.94 2.93 2.40 - <![CDATA[6.2×10 -6 ]]> RH-N4 5.95 2.94 2.43 - <![CDATA[7.8×10 -6 ]]> RH-N5 5.96 2.92 2.44 - <![CDATA[5.6×10 -6 ]]> RH-N6 5.97 2.91 2.41 - <![CDATA[9.8×10 -7 ]]> RH-P 5.32 2.36 2.41 <![CDATA[6.2×10 -8 ]]> - RH-N 5.98 2.92 2.40 - <![CDATA[3.8×10 -7 ]]>

[0121] The structures of the compounds used in the following examples and comparative examples are shown below:

[0122]

[0123]

[0124] The structure and fabrication of the organic electroluminescent devices in each embodiment and comparative example include the following steps:

[0125] The glass plate with ITO was ultrasonically treated in deionized water and then dried at 100°C.

[0126] Red light device fabrication: ITO glass was placed in a vacuum evaporation equipment and HIL (10nm), HTL (100nm), R' (80nm), R-EML (45nm), HBL (5nm), ETL (30nm), EIL, cathode (Yb, 1nm, Mg:Ag (1:9), 12nm) and CPL (65nm) were deposited in sequence.

[0127] R-EML comprises RH and RD, wherein RH contains P-type organic semiconductor material and N-type organic semiconductor material in a mass ratio of 4:6; RD is doped into the host material RH at a rate of 2wt%.

[0128] The materials of the above layers are as follows:

[0129]

[0130]

[0131] Example 1

[0132] A red-light organic electroluminescent device, the preparation method of which includes the following steps:

[0133] The glass plate with ITO was ultrasonically treated in deionized water and then dried at 100°C.

[0134] Red light device fabrication: ITO glass is placed in a vacuum evaporation equipment, and HIL, HTL, R', R-EML, HBL, ETL, EIL, cathode and CPL are deposited sequentially.

[0135] R-EML comprises RH and RD, wherein RH comprises RH-P1 and RH-N in a mass ratio of 4:6; RD is doped into the host material RH at an amount of 2 wt% relative to the total mass of the host material RH.

[0136] Example 2

[0137] A red organic electroluminescent device, compared to Example 1, except that RH-P1 is replaced with RH-P2, and all other aspects are the same as in Example 1.

[0138] Example 3

[0139] A red organic electroluminescent device, compared to Example 1, except that RH-P1 is replaced with RH-P3, and all other aspects are the same as in Example 1.

[0140] Example 4

[0141] A red organic electroluminescent device, compared to Example 1, except that RH-P1 is replaced with RH-P4, and all other aspects are the same as in Example 1.

[0142] Example 5

[0143] A red organic electroluminescent device, compared to Example 1, except that RH-P1 is replaced with RH-P5, and all other aspects are the same as in Example 1.

[0144] Example 6

[0145] A red-light organic electroluminescent device, compared to Example 1, except that RH-P1 is replaced with RH-P6, and all other aspects are the same as in Example 1.

[0146] Example 7

[0147] A red organic electroluminescent device, compared with Example 1, wherein RH comprises RH-P and RH-N1 in a mass ratio of 4:6; RD is doped into the main body at a ratio of 2%, and the rest are the same as in Example 1.

[0148] Example 8

[0149] A red organic electroluminescent device, compared to Example 7, except that RH-N1 is replaced with RH-N2, ​​and all other aspects are the same as in Example 7.

[0150] Example 9

[0151] A red organic electroluminescent device, compared to Example 7, except that RH-N1 is replaced with RH-N3, and all other aspects are the same as in Example 7.

[0152] Example 10

[0153] A red organic electroluminescent device, compared to Example 7, except that RH-N1 is replaced with RH-N4, and all other aspects are the same as in Example 7.

[0154] Example 11

[0155] A red organic electroluminescent device, compared to Example 7, except that RH-N1 is replaced with RH-N5, and all other aspects are the same as in Example 7.

[0156] Example 12

[0157] A red organic electroluminescent device, compared to Example 7, except that RH-N1 is replaced with RH-N6, and all other aspects are the same as in Example 7.

[0158] Example 13

[0159] A red organic electroluminescent device, compared to Example 1, replaces RH-N with RH-N1; that is, RH-P1 is paired with RH-N1, and the rest is the same as in Example 1.

[0160] Comparative Example 1

[0161] A red organic light-emitting device, compared to Example 1, wherein RH comprises RH-P and RH-N in a mass ratio of 4:6; RD is doped into the host material RH at 2 wt% relative to the total mass of the host material RH. Other aspects are the same as in Example 1.

[0162] The TVL data and lifetime of the above devices were tested. During performance testing, V, cd / A, Ciex, and Ciey were measured using an IVL (current, voltage, and brightness) testing device at a current density of 15 mA / cm². 2 The lifespan was tested using an OLED lifespan tester at 25°C and 1000 nits brightness. The results are shown in Table 2 below.

[0163] Table 2. Device IVL Data and Lifetime

[0164] serial number V(V) Cd / A CIE x CIE y LT95(h)@1000nit Example 1 94％ 108％ 0.685 0.312 106％ Example 2 96％ 106％ 0.684 0.314 110％ Example 3 98％ 104％ 0.685 0.313 108％ Example 4 95％ 106％ 0.686 0.311 108％ Example 5 94％ 105％ 0.687 0.315 109％ Example 6 92％ 106％ 0.686 0.316 114％ Example 7 93％ 108％ 0.688 0.314 118％ Example 8 95％ 109％ 0.686 0.315 102％ Example 9 96％ 107％ 0.685 0.316 107％ Example 10 95％ 105％ 0.684 0.315 109％ Example 11 97％ 106％ 0.685 0.314 106％ Example 12 98％ 109％ 0.687 0.316 107％ Example 13 99％ 110％ 0.685 0.312 120％ Comparative Example 1 100％ 100％ 0.686 0.313 100％

[0165] In Table 2 above, the V, Cd, and LT95h values ​​in Examples 1-12 are all relative to Comparative Example 1. In Comparative Example 1, the absolute value of V is 3.8V, the absolute value of Cd is 76A, and the LT95h@1000nit value is 650h.

[0166] As can be seen from the results in Table 2 above, in the specific embodiments of the present invention, by selecting the host material in the organic electroluminescent red light-emitting layer, and by selecting and combining the hole-type host material and the electron-type host material in the host material, the prepared organic electroluminescent device has low voltage, high efficiency, and long lifespan. Furthermore, the display device containing this organic electroluminescent device is endowed with the same effect, which will not be elaborated further here.

[0167] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. For those skilled in the art, other variations or modifications can be made based on the above description. It is impossible to exhaustively list all the implementation methods here. All obvious variations or modifications derived from the technical solutions of the present invention are still within the protection scope of the present invention.

Claims

1. An organic electroluminescent layer, characterized by The material comprises: a host material; and a dopant material doped in the host material; the host material contains a P-type organic semiconductor material and an N-type organic semiconductor material; wherein, The P-type organic semiconductor material is selected from one of , , , , , and and The N-type organic semiconductor material is selected from one of , , , , , , ; wherein, when the P-type organic semiconductor material is selected from when the P-type organic semiconductor material is selected from The N-type organic semiconductor material is selected from one of , , , , or . when the N-type organic semiconductor material is selected from when the N-type organic semiconductor material is selected from The P-type organic semiconductor material is selected from one of , , , , or . the mass ratio of the P-type organic semiconductor material to the N-type organic semiconductor material is 3:7-7:

3.

2. An organic electroluminescent device, characterized by comprising a red light emitting layer; wherein the red light emitting layer is selected from the organic electroluminescent layer according to claim 1.

3. A display device, characterized by comprising: comprising the organic electroluminescent device according to claim 2.

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