Germanium-containing organic compound, germanium-containing exciplex and application thereof

Abstract

The invention discloses a germanium-containing organic compound, a germanium-containing exciplex and application of the germanium-containing organic compound and the germanium-containing exciplex, and relates to the technical field of organic electroluminescent materials. The germanium-containing organic compound is a compound as shown in a general formula A; the germanium-containing exciplex is composed of a first main body material and a second main body material, the first main body material and the second main body material are both selected from a compound shown in a general formula A and / or a compound shown in a general formula B, at least one material is a germanium-containing organic compound, the first main body material contains a substituted or unsubstituted hole transport type group, and the second main body material contains a substituted or unsubstituted electron transport type group. The germanium-containing exciplex has excellent carrier transport capacity due to the fact that the germanium-containing exciplex contains the germanium with the metalloid property and has the beneficial effect of balancing hole and electron transport capacity, meanwhile, the heavy atom effect of germanium atoms can promote reverse intersystem crossing of a main body material, the effective utilization rate of exciton energy is increased, and therefore the germanium-containing exciplex can be applied to the field of organic light emitting devices. According to the invention, the luminous efficiency and the efficiency roll-off of the organic electroluminescent element can be more effectively improved.

Description

Technical Field

[0001] The invention relates to the technical field of organic electroluminescent materials, and in particular to an organic compound containing germanium, a germanium-containing exciplex and applications thereof. Background Art

[0002] Organic light-emitting diodes (OLEDs) are light-emitting devices made by the composite light emission of electrons and holes in organic thin films. They have the advantages of self-luminescence, light weight, wide viewing angle, high resolution, low power consumption, fast response speed, wide operating temperature range, and flexible display. They have been widely used in various display fields such as mobile phones, televisions, and instruments. The key to the performance of OLEDs depends mainly on the selection and use of luminescent materials in the organic light-emitting layer. Efficient and stable three-primary color red, green, and blue light materials are necessary for the realization of full-color display OLEDs. At present, efficient and stable red and green light materials used for OLEDs have been commercialized and applied on a large scale, but blue light materials are still not efficient and stable. Blue light materials include blue light guest materials and host materials. Although many blue light guest materials have been reported in literature and patents, the low external quantum efficiency and high efficiency roll-off problems of blue light guest materials in devices need to be solved by finding high-performance host materials. Summary of the invention

[0003] Exciplex is a dual-host material system obtained by selecting a suitable first host and a second host material. Exciplex has the characteristics of broadening the luminescence spectrum relative to the first host and the second host material and having a thermal activation delay characteristic. Therefore, compared with the traditional single host material, it improves the utilization rate of triplet excitons, thereby improving the quantum efficiency of the device. The design of the light-emitting layer of the dual-host mixture of the exciplex is also conducive to achieving carrier balance and uniform distribution of excitons, which is conducive to reducing the efficiency roll-off of the device.

[0004] In view of the problems or defects existing in the prior art, the purpose of the present invention is to provide a host material and its application that can be used as an exciplex, so as to solve or at least partially solve the above-mentioned technical defects existing in the prior art. The exciplex of the present invention includes a germanium-containing exciplex, which is composed of a germanium-containing compound and a second component. The introduction of the germanium-containing compound can improve the carrier transport performance, and germanium as a heavy atom can effectively improve the reverse intersystem crossing of the main body of the exciplex. The present application also provides an organic electroluminescent device, which solves the problems of severe efficiency roll-off and low external quantum efficiency of light-emitting devices in the prior art.

[0005] To achieve the above object, the technical solution adopted by the present invention is as follows.

[0006] Specifically, the present invention provides a germanium-containing organic compound, which is a compound represented by the following general formula A:

[0007]

[0008] Wherein, in the general formula A, the symbols and marks used therein have the following meanings:

[0009] X1 may not exist, may be a single bond, or may be O, S, N, or C; R1, R2, and R3 are each independently selected from C1-C3 alkyl groups or independently selected from substituted or unsubstituted C4-C10 aryl or heteroaryl groups; Ar1 ​​is independently selected from substituted or unsubstituted C4-C10 aryl or heteroaryl groups; L1 is selected from substituted or unsubstituted hole transport groups or electron transport groups.

[0010] In some other embodiments, L1 may independently have 2 to 4 germanium-containing groups, and preferred germanium-containing groups include trimethylgermanium, dimethylphenylgermanium, and triphenylgermanium.

[0011] Further, R1, R2 and R3 are each independently selected from methyl, ethyl, propyl or substituted or unsubstituted phenyl, furanyl, biphenyl, naphthyl, thienyl, dibenzofuranyl, benzofuranyl, benzothienyl, N-phenylcarbazolyl, 9,9-dimethylfluorene, 9-methyl-9-phenylfluorene, 9,9-diphenylfluorenyl, 9,9'-spirobifluorenyl, spiro[fluorene-9,9'-oxanthene]yl, spiro[fluorene-9,9'-thioanthene]yl; Ar is selected from phenyl, biphenyl, naphthyl, furanyl, thienyl, dibenzofuranyl, dibenzothienyl, benzofuranopyridyl, benzothienopyridyl or pyridyl, carbazolyl, triazine.

[0012] An organic mixture comprising at least one compound represented by general formula A and at least one compound represented by general formula B:

[0013]

[0014] Wherein, in the general formula B, X2 may not exist, may be a single bond, may be O, S, N, C; R4, R5 and R6 are each independently selected from C1~C3 alkyl or independently selected from substituted or unsubstituted C4~C10 aryl or heteroaryl; Ar2 may not exist, may be independently selected from substituted or unsubstituted C4~C10 aryl or heteroaryl; L2 is selected from substituted or unsubstituted hole transport group or electron transport group; and the compound represented by the general formula A and the compound represented by the general formula B are different compounds.

[0015] In some other embodiments, L2 may independently have 0 to 4 germanium-containing groups, and preferred germanium-containing groups include trimethylgermanium, dimethylphenylgermanium, and triphenylgermanium.

[0016] Further, R4, R5 and R6 are each independently selected from methyl, ethyl, propyl or substituted or unsubstituted phenyl, furanyl, biphenyl, naphthyl, thienyl, dibenzofuranyl, benzofuranyl, benzothienyl, N-phenylcarbazolyl, 9,9-dimethylfluorene, 9-methyl-9-phenylfluorene, 9,9-diphenylfluorenyl, 9,9'-spirobifluorenyl, spiro[fluorene-9,9'-oxanthene]yl, spiro[fluorene-9,9'-thioanthene]yl; Ar is selected from phenyl, biphenyl, naphthyl, furanyl, thienyl, dibenzofuranyl, dibenzothienyl, benzofuranopyridyl, benzothienopyridyl or pyridyl, carbazolyl, triazine.

[0017] The present invention also provides a germanium-containing exciplex, which is composed of a first host material and a second host material; the first host material contains a substituted or unsubstituted hole transport group, selected from the compound represented by the above general formula A and / or the compound represented by the general formula B (i.e., L1 in the general formula A and L2 in the general formula B are hole transport groups); the second host material contains a substituted or unsubstituted electron transport group, selected from the compound represented by the above general formula A and / or the compound represented by the general formula B (i.e., L1 in the general formula A and L2 in the general formula B are electron transport groups); at least one of the first host material and the second host material is a germanium-containing organic compound; wherein min((LUMO(1)-HOMO(2), LUMO(2)-HOMO(1))≤min(ET(1), ET(2))±0.2eV, wherein LUMO(1), HOMO(1) and E T (1) are the highest occupied molecular orbital, lowest unoccupied molecular orbital and triplet energy levels of the first host material, LUMO(2), HOMO(2) and E T (2) are the energy levels of the highest occupied orbital, lowest unoccupied orbital and triplet state of the second host material, respectively.

[0018] Furthermore, the hole transport group is selected from but not limited to substituted or unsubstituted carbazole and diphenylamine; preferably, the hole transport group is selected from any one of the following groups:

[0019]

[0020] in, It represents the connection site between Ar1 and L1, or the connection site between Ar2 and L2.

[0021] Furthermore, the first host material is a compound having formula 1-1 to 1-204:

[0022]

[0023]

[0024]

[0025]

[0026]

[0027]

[0028]

[0029] The formulas 1-1 to 1-204 are only representative first host materials, and the first host material is not limited to the scope of formulas 1-1 to 1-204.

[0030] Further, the electron transport group is selected from but not limited to substituted or unsubstituted triazine group and pyridine. Preferably, the electron transport group is selected from any one of the following groups:

[0031]

[0032] in, represents the connection site between Ar1 and L1, or the connection site between Ar2 and L2. Further, the second host material is a compound having formula 2-1 to 2-264:

[0033]

[0034]

[0035]

[0036]

[0037]

[0038]

[0039]

[0040]

[0041]

[0042]

[0043] The formulas 2-1 to 2-264 are only representative second host materials, and the second host material is not limited to the scope of formulas 2-1 to 2-264.

[0044] The above-mentioned germanium-containing excited complex of the present invention can be used as an organic electroluminescent functional material; preferably, the organic electroluminescent functional material also includes an organic functional material, and the organic functional material is selected from hole injection materials, hole transport materials, electron transport materials, electron injection materials, electron blocking materials, hole blocking materials, and luminescent guest materials.

[0045] The present invention also provides an organic electroluminescent device, which comprises a cathode, an anode and a light-emitting functional layer located between the cathode and the anode, wherein the light-emitting functional layer comprises the above-mentioned germanium-containing organic compound or germanium-containing exciplex provided by the present invention.

[0046] Specifically, the organic electroluminescent device of the present invention comprises a substrate, and an anode layer, a light-emitting functional layer and a cathode layer sequentially formed on the substrate; the light-emitting functional layer comprises a hole injection layer, a hole transport layer, a light-emitting layer, an electron transport layer and an electron injection layer; the hole injection layer is formed on the anode layer, the hole transport layer is formed on the hole injection layer, the electron injection layer is formed on the electron transport layer, the cathode layer is formed on the electron injection layer, and a light-emitting layer is provided between the hole transport layer and the electron transport layer; wherein the light-emitting layer contains the germanium-containing organic compound or the germanium-containing excited complex provided by the present invention.

[0047] Furthermore, the light-emitting functional layer further comprises an electron blocking layer between the hole transport layer and the light-emitting layer, and the electron blocking layer contains any compound shown in the first host material in the present invention;

[0048] The light-emitting functional layer further comprises a hole blocking layer located between the light-emitting layer and the electron transport layer, and the hole blocking layer contains any compound shown in the second host material in the present invention.

[0049] In another preferred embodiment, the exciplex contained in the light-emitting layer, in some embodiments, the mixture, preferably min((LUMO(1)-HOMO(2), LUMO(2)-HOMO(1))≤min(E T (1),E T (2))-0.05 eV; In other embodiments, preferably min((LUMO(1)-HOMO(2), LUMO(2)-HOMO(1))≤min(E T (H),E T (H))-0.1 eV; In other embodiments, it is more preferred that min((LUMO(1)-HOMO(2),LUMO(2)-HOMO(1))≤min(E T (1),ET (2))-0.15 eV; In other embodiments, it is most preferred that min((LUMO(1)-HOMO(2),LUMO(2)-HOMO(1))≤min(E T (1),E T (H2))-0.2eV; In the embodiment of the present invention, the energy level structure of the organic material, the triplet energy level E T , HOMO, and LUMO play a key role.

[0050] Preferably, the mass ratio of the first host material to the second host material of the excited complex contained in the light-emitting layer is (1-10):(10-1). In some embodiments, the preferred mass ratio is 3:7; in other embodiments, the preferred mass ratio is 7:3; and the most preferred mass ratio is 1:1.

[0051] Still further preferably, the hole blocking layer has a thickness of 1nm-200nm, preferably 10nm-30nm; the light emitting layer has a thickness of 1nm-100nm, preferably 20nm-80nm; the electron blocking layer has a thickness of 1nm-200nm, preferably 10nm-30nm.

[0052] The organic electroluminescent device prepared by using the germanium-containing exciplex of the invention has high external quantum efficiency and low efficiency roll-off.

[0053] The specific reasons why the germanium-containing exciplex of the present invention has excellent performance when used in an organic electroluminescent device are not yet clear. The following are speculations of the inventors, but these speculations do not limit the protection scope of the present invention.

[0054] The germanium-containing excited complex of the present invention comprises a first main material having a structure of the general formula A and / or the general formula B and containing a hole-transporting group, and a second main material having a structure of the general formula A and / or the general formula B and containing an electron-transporting group. Germanium is a metalloid element with excellent electron-transporting ability and hole-transporting ability. The introduction of germanium into organic molecules may increase the electron-transporting ability and hole-transporting ability of the organic molecules. At the same time, germanium is a heavy atom, and there is a strong heavy atom effect in organic molecules containing germanium, which improves the reverse intersystem crossing rate of organic molecules and excited complexes. With the superposition of the two factors, the germanium-containing excited complex has both high carrier-transporting ability and high reverse intersystem crossing rate, thereby improving the external quantum efficiency of the device and reducing the efficiency roll-off. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0056] Figure 1 The ultraviolet absorption spectrum, thin film room temperature fluorescence and low temperature phosphorescence spectrum at 77K of the compound of formula 1-52 obtained in Test Example 1 in dichloromethane solution.

[0057] Figure 2 The ultraviolet absorption spectrum, thin film room temperature fluorescence and low temperature phosphorescence spectrum at 77K of the compound of formula 2-27 obtained in Test Example 2 in dichloromethane solution.

[0058] Figure 3 The room temperature fluorescence and low temperature phosphorescence spectra at 77K of the germanium-containing exciplex material film obtained in Test Example 3 are shown.

[0059] Figure 4 This is a transient fluorescence decay spectrum of the film prepared from the compound of formula 1-52 obtained in Test Example 1.

[0060] Figure 5 This is the transient fluorescence decay spectrum of the film prepared from the compound of formula 2-27 obtained in Test Example 2.

[0061] Figure 6 This is a transient fluorescence decay spectrum of the film prepared from the germanium-containing exciplex in Test Example 3.

[0062] Figure 7 This is a cyclic voltammetry curve of the compound of formula 1-52 obtained in Test Example 10 in dichloromethane.

[0063] Figure 8 This is the cyclic voltammetry curve of the compound of formula 1-188 obtained in Test Example 11 in dichloromethane.

[0064] Fig. 9 This is the cyclic voltammetry curve of the compound of formula 2-24 obtained in Test Example 12 in dichloromethane.

[0065] Fig.10 This is the cyclic voltammetry curve of the compound of formula 2-27 obtained in Test Example 13 in dichloromethane.

[0066] Fig.11 Schematic diagram of organic electroluminescent devices according to embodiments of the present invention and comparative examples.

[0067] Fig.121 is a relationship diagram between the external quantum efficiency and brightness of the organic electroluminescent devices of Example 1 and Comparative Example 1.

[0068] Fig.13 The current-voltage-brightness curves of the organic electroluminescent devices of Example 1 and Comparative Example 1 are shown.

[0069] Fig.14 This is a relationship diagram between the external quantum efficiency and brightness of the organic electroluminescent devices of Example 6 and Comparative Example 2.

[0070] Fig.15 The current-voltage-brightness curves of the organic electroluminescent devices of Example 6 and Comparative Example 2 are shown.

[0071] Fig.16 This is a graph showing the relationship between the external quantum efficiency and brightness of the organic electroluminescent device of Example 20.

[0072] Fig.17 This is a graph showing the relationship between the external quantum efficiency and brightness of the organic electroluminescent device of Example 23. DETAILED DESCRIPTION

[0073] The specific preparation method and use of the above-mentioned exciplex of the present invention will be described in detail below using multiple synthesis and application examples as examples, but the preparation method and use of the present invention are not limited to these synthesis examples.

[0074] Synthesis Example

[0075] Synthesis Example 1: Synthesis of the compound of formula 1-52 (first host material)

[0076]

[0077] Under nitrogen protection, 1-52-1 (0.92 g, 2 mmol), 3,9'-bicarbazole (1.00 g, 3 mmol) were added to a 250 ml round-bottom flask, and toluene (80 mL) was used as solvent. tBu3P (40.4 mg, 0.20 mmol), sodium tert-butoxide (0.58 g, 4 mmol) and Pd2(dba)3 (55 mg, 0.06 mmol) were added. The mixture was heated to reflux for 36 hours, cooled and the solvent was removed by distillation under reduced pressure. The target product 1-52 (1.3 g, yield 89%, HPLC analysis purity 99.35%) was obtained by column chromatography purification (eluent 5:1 petroleum ether: ethyl acetate). HRMS (ES I) theoretical calculation C 48 H 34 GeN2, [M+H] + 713.2007; the actual measured value is 713.1014.

[0078] Synthesis Example 2: Synthesis of the compound of formula 1-188 (first host material)

[0079]

[0080] Under nitrogen protection, at -78 degrees Celsius, 1-188-1 (4.40 g, 10 mmol) and tetrahydrofuran (80 mL) were added to a 250 ml round-bottom flask as solvent, and then n-butyl lithium (2.5 M) (8 mL, 20 mmol) was added. After reacting for 5 minutes, diphenyl germanium dichloride (3.57 g, 12 mmol) was added. After adding diphenyl germanium dichloride, the reaction was allowed to react at room temperature for 12 hours. After cooling, the solvent was removed by distillation under reduced pressure, and the intermediate product 1-188-2 (1.2 g, yield 26%, HPLC analysis purity 98.43%) was obtained by column chromatography purification (eluent: petroleum ether). HRMS (ES I) theoretical calculation C 24 H 17 BrGe, [M+H] + 458.9798; the actual measured value is 458.9800.

[0081] The reaction of the intermediate product 1-188-2 with 3,9'-bicarbazole is basically the same as in Synthesis Example 1, except that 1-52-1 is replaced with 1-188-2 in this example. The scale of the reaction of 1-188-2 is 2 mmol, and the final product 1-188 (1.1 g, yield 77%, HPLC analysis purity 99.61%). HRMS (ES I) theoretical calculation C 24 H 32 BrGe, [M+H] + 711.1850; the actual measured value is 711.1858.

[0082] Synthesis Example 3: Synthesis of the compound of formula 2-2 (second host material)

[0083]

[0084] Under nitrogen protection, 2-2-1 (1.1 g, 2 mmol) and tetrahydrofuran (40 mL) were added to a 250 ml round-bottom flask, and 2.5 M n-butyl lithium (0.8 mL, 2 mmol) was added at -78 degrees Celsius. After reacting for 1 hour, phenyldimethylgermanium chloride (0.60 g, 3 mmol) was added, and then the reaction was carried out at room temperature for 11 hours. After cooling, the solvent was distilled off under reduced pressure, and the target product 2-2 (0.85 g, yield 64%, HPLC analysis purity 99.49%) was obtained by purification by column chromatography (eluent was 3:1 petroleum ether: dichloromethane).

[0085] Synthesis Example 4: Synthesis of the compound of formula 2-27 (second host material)

[0086]

[0087] Under nitrogen protection, 2-27-1 (1.1 g, 2 mmol), 9,9'-(6-chloro-1,3,5-triazine-2,4-diyl)bis(9H-carbazole) (0.89 g, 2 mmol), tetrakistriphenylphosphine palladium (23.0 mg, 0.02 mmol), potassium carbonate (0.55 g, 4 mmol), tetrahydrofuran (20 mL), water (20 mL) were added to a 100 ml round-bottom flask, and the mixture was reacted at 65 degrees for 24 hours. After cooling, the solvent was removed by vacuum distillation, and the target product 2-27 (1.2 g, yield 75%, HPLC analysis purity 99.49%) was obtained by column chromatography purification (eluent 3:1 petroleum ether: dichloromethane). HRMS (ES I) theoretical calculation C 51 H 35 GeN5, [M+H] + 792.2177; the measured value is 792.2183.

[0088] Synthesis Example 5: Synthesis of the compound of formula 2-8 (second host material)

[0089]

[0090] Under nitrogen protection, at 0 degrees, 2-8-1 (4.40 g, 10 mmol) was added to a 250 ml round-bottom flask, tetrahydrofuran (80 mL) was used as solvent, and then 2.5 M n-butyl lithium (8 mL, 20 mmol) was added. After reacting for 60 minutes, 2,4-dichloro-6-phenyl-1,3,5-triazine (2.26 g, 10 mmol) was added. The reaction was continued at 60 degrees for 24 hours. After cooling, the solvent was removed by distillation under reduced pressure. The target product 2-8 (3.2 g, yield 27%, HPLC analysis purity 98.51%) was obtained by column chromatography purification (eluent 2:1 petroleum ether: dichloromethane). HRMS (ES I) theoretical calculation C 65 H 61 Ge4N5, [M+H] + 1208.1847; the measured value is 1208.1856.

[0091] Synthesis Example 6: Synthesis of the compound of formula 1-26 (first host material)

[0092]

[0093] The reaction of 1-26-1 and bis(2-bromophenyl)amine in this example is basically the same as that in Example 1, except that: in this example, 1-26-1 replaces 1-52-1, bis(2-bromophenyl)amine replaces 3,9'-bicarbazole, the reaction temperature is 70°C, and the reaction time is 12 hours. The intermediate product 1-26-2 (0.89 g, yield 63%) was obtained by column chromatography purification (eluent is petroleum ether), and then all of it was used for the next step reaction. HRMS (ES I) theoretical calculation C 36 H 27 Br2GeN, [M+H] + 705.9795; the actual measured value is 705.9793.

[0094] The reaction of the intermediate product 1-26-2 with diphenylgermanium chloride is basically the same as in Example 2, except that 1-26-2 replaces 1-188-1 in this example. The target product 1-26 (0.58 g, yield 75%, HPLC analysis purity 98.99%) was obtained by column chromatography purification (eluent is petroleum ether). HRMS (ES I) theoretical calculation C 48 H 37 Ge2N, [M+H] + 776.1422; the measured value is 776.1430.

[0095] Synthesis Example 7: Synthesis of the compound of formula 1-1 (first host material)

[0096]

[0097] The reaction of 1,3-diiodobenzene and dimethylphenylgermanium chloride in this example is basically the same as that in Example 6, except that the equivalents of 1,3-diiodobenzene and dimethylphenylgermanium chloride are the same in this example. The intermediate product 1-1-1 (2.7 g, yield 55%) was obtained by column chromatography purification (eluent: petroleum ether), and then all of it was used in the next step. HRMS (ES I) theoretical calculation C 13 H 15 Ge I, [M+H] + 384.9503; the measured value is 384.9509.

[0098] The reaction of 1-1 and 3-bromocarbazole in this example is basically the same as that in Example 6, except that 1-1-1 replaces 1-26-1, and 3-bromocarbazole replaces 3,9'-bicarbazole. The intermediate product 1-1-2 (1.3 g, yield 38%) was obtained by column chromatography purification (eluent: petroleum ether), and then all of it was used in the next step. HRMS (ESI) theoretical calculation C 26 H 22 BrGeN, [M+H] +502.0220; the actual measured value is 502.0224.

[0099] The reaction of 1-1-2 and 9,10-dihydro-9,9-diphenylacridine in this example is basically the same as that in Example 1, with 1-1-2 replacing 1-52-1,9,10-dihydro-9,9-diphenylacridine replacing 3,9'-bicarbazole. The product 1-1 (1.1 g, yield 55%, HPLC analysis purity 99.72%) was obtained by column chromatography purification (eluent: petroleum ether). HRMS (ES I) theoretical calculation C 51 H 40 GeN2, [M+H] + 755.2476; the measured value is 755.2782. Synthesis Example 8: Synthesis of the compound of formula 1-4 (first host material)

[0100]

[0101] The reaction of 1,3-diiodobenzene and phenyldiethylgermanium chloride is basically the same as that in Example 6, except that phenyldiethylgermanium chloride replaces diphenylgermanium chloride in this example, and the reaction scale is 20 mmol. The intermediate product 1-4-1 (2.0 g, yield 24%) is obtained by column chromatography purification (eluent is petroleum ether), and then all of it is used for the next step reaction. HRMS (ES I) theoretical calculation C 16 H 19 Ge I, [M+H] + 412.9816; the measured value is 412.9823. The reaction of 1-4-1 and 3,6-bis(trimethylgermanium)carbazole is basically the same as that in Example 6, except that: in this example, 1-4-1 replaces 1-26-1, and 3,6-bis(trimethylgermanium)carbazole replaces bis(2-bromophenyl)amine. The target product 1-4 (1.9 g, 58%, HPLC analysis purity 99.67%) was obtained by column chromatography purification (eluent is 10:1 petroleum ether: dichloromethane). HRMS (ES I) theoretical calculation C 34 H 43 Ge3N, [M+H] + 688.1104; the actual measured value is 688.1107.

[0102] Synthesis Example 9: Synthesis of the compound of formula 2-4 (second host material)

[0103]

[0104] The reaction of 2-4-1 and carbazole is basically the same as that in Example 6, except that: in this example, carbazole (3.4 g, 20 mmol) is added to a 250 ml round-bottom flask, tetrahydrofuran (80 mL) is used as a solvent, and then 2.5 M n-butyl lithium (8 mL, 20 mmol) is added. After 60 minutes of reaction, 2-4-1 (4.5 g, 20 mmol) is added, and the reaction is reacted at 60 degrees for 24 hours to generate 2-4-2 without separation. 3,6-bis (trimethylgermanium) carbazole (8.0 g, 20 mmol) is added to a 250 ml round-bottom flask, tetrahydrofuran (80 mL) is used as a solvent, and then 2.5 M n-butyl lithium (8 mL, 20 mmol) is added. After 60 minutes of reaction, the reagent in the round-bottom flask is transferred to the round-bottom flask containing 2-4-2, and the reaction is reacted at 60 degrees for 24 hours. After the reaction was completed, 100 mL of water was used to quench the reaction, and the target product 2-4 (1.9 g, yield 12%, HPLC analysis purity 99.04%) was obtained by column chromatography purification (eluent 5:1 petroleum ether: dichloromethane). HRMS (ES I) theoretical calculation C 39 H 37 Ge2N5, [M+H] + 724.1545; the actual measured value is 724.1551.

[0105] Synthesis Example 10: Synthesis of the compound of formula 2-33 (second host material)

[0106]

[0107] The reaction of 2-33-1 and 2-bromocarbazole is basically the same as in Example 6, except that in this example, 2-33-1 replaces 1-26-1, and 2-bromocarbazole replaces bis(2-bromophenyl)amine. The intermediate product 2-33-2 (2.8 g, yield 65%) was obtained by column chromatography purification (eluent: petroleum ether). HRMS (ES I) theoretical calculation C 36 H 26 BrGeN, [M+H] + 626.0533; the actual measured value is 626.0539.

[0108] The intermediate product 2-33-2 (1.9 g, 3 mmol), diboronic acid pinacol ester (1.5 g, 6 mmol), PdCl2 (dppf) (22.0 mg, 1%), potassium acetate (0.6 g, 6 mmol) were placed in a 100 ml round-bottom flask, the atmosphere in the round-bottom flask was replaced with nitrogen, 40 mL of dimethyl sulfoxide was added, and the reaction was carried out at 120 degrees for 24 hours. The target product 2-33-3 (1.2 g, yield 60%) was obtained by column chromatography purification (eluent was 10:1 petroleum ether: ethyl acetate), and then all of it was used for the next step reaction. HRMS (ESI) theoretical calculation C 42 H 38 BGeNO2, [M+H] + 674.2280; the measured value is 674.2288.

[0109] The synthesis reaction of 2-33-3 and 2-chloro-4,6-diphenyl-1,3,5-triazine is basically the same as that in Example 4, except that: in this example, 2-33-3 replaces 1-1-1, and 2-chloro-4,6-diphenyl-1,3,5-triazine replaces 9,9'-(6-chloro-1,3,5-triazine-2,4-diyl)bis(9H-carbazole). The target product 2-33 (0.95 g, yield 68%, HPLC analysis purity 99.41%) was obtained by column chromatography purification (eluent 3:1 petroleum ether: dichloromethane). HRMS (ES I) theoretical calculation C 51 H 36 GeN4, ​​[M+H] + 779.2225; the actual measured value is 779.2230.

[0110] Test example: Performance and characterization of germanium-containing exciplexes

[0111] Test Example 1: Testing the UV absorption spectrum of the first host material 1-52 in a dichloromethane solution. The concentration of the first host material 1-52 in the dichloromethane solution is 1×10 -5 mol L -1 The room temperature fluorescence emission spectrum of the first host material 1-52 film and the low temperature phosphorescence spectrum at 77K were tested.

[0112] Test Example 2: Testing the UV absorption spectrum of the second host material 2-27 in a dichloromethane solution. The concentration of the second host material 2-27 in the dichloromethane solution is 1×10 -5 mol L -1 The second host material 2-27 was tested for its room temperature fluorescence emission spectrum and low temperature phosphorescence spectrum at 77K.

[0113] Test Example 3: Testing the room temperature fluorescence emission spectrum of a film of a mixture of the first host material 1-52 and the second host material 2-27 in a mass ratio of 1:1 and the low temperature phosphorescence spectrum at 77K.

[0114] Test Example 4, testing the room temperature fluorescence emission spectrum of the first host material 1-188 film and the low temperature phosphorescence spectrum at 77K.

[0115] Test Example 5, testing the room temperature fluorescence emission spectrum of the first host material 1-10 film and the low temperature phosphorescence spectrum at 77K.

[0116] Test Example 6, testing the room temperature fluorescence emission spectrum of the second host material 2-2 film and the low temperature phosphorescence spectrum at 77K.

[0117] Test Example 7, testing the room temperature fluorescence emission spectrum of the second host material 2-24 film and the low temperature phosphorescence spectrum at 77K.

[0118] Test Example 8, testing the room temperature fluorescence emission spectrum of a film of a mixture of the first host material 1-188 and the second host material 2-24 in a mass ratio of 1:1 and the low temperature phosphorescence spectrum at 77K.

[0119] Test Example 9, testing the room temperature fluorescence emission spectrum of a film of a mixture of the first host material 1-10 and the second host material 2-2 in a mass ratio of 1:1 and the low temperature phosphorescence spectrum at 77K.

[0120] Figure 1 The ultraviolet absorption spectrum in dichloromethane solution, the room temperature fluorescence of the film and the low temperature phosphorescence spectrum at 77K obtained in Test Example 1 are shown. Figure 2 The ultraviolet absorption spectrum in dichloromethane solution, the room temperature fluorescence of the film and the low temperature phosphorescence spectrum at 77K obtained in Test Example 2 are shown. Figure 3 The room temperature fluorescence and low temperature phosphorescence spectra of the film of Test Example 3 at 77K.

[0121] The test examples include emission peak wavelength, the lowest singlet energy level (S1), the lowest triplet energy level (T1), the difference between S1 and T1 (ΔE ST ) as shown in Table 1.

[0122] Table 1 Photophysical data of test examples 1-9

[0123]

[0124] As can be seen from Table 1, the ΔE of the germanium-containing excited complex after the first host material and the second host material are mixed in Test Example 3, Test Example 8, and Test Example 9. ST The value is consistent with the TADF characteristics.

[0125] The films obtained in Test Examples 1 to 3 were subjected to transient fluorescence decay spectroscopy tests. Figure 4 is the transient fluorescence decay spectrum of the film of Test Example 1, Figure 5 is the transient fluorescence decay spectrum of the film of Test Example 2, Figure 6 This is the transient fluorescence decay spectrum of the film of Test Example 3; the results show that Test Examples 1 and 2 have no delayed fluorescence, while Test Example 3 has delayed fluorescence, which is consistent with the TADF characteristics.

[0126] Test Example 10, using 0.1M TBAPF6 DMF solution as electrolyte and ferrocene as internal reference, the cyclic voltammetry curve of the first host material 1-52 was tested. The results are as follows: Figure 7 shown.

[0127] Test Example 11, using 0.1M TBAPF6 DMF solution as electrolyte and ferrocene as internal reference, the cyclic voltammetry curve of the first host material 1-188 was tested. The results are as follows: Figure 8 shown.

[0128] Test Example 12 uses 0.1M TBAPF6 DMF solution as electrolyte and ferrocene as internal reference to test the cyclic voltammetry curve of the second host material 2-24. The results are as follows: Fig. 9 shown.

[0129] Test Example 13 uses 0.1M TBAPF6 DMF solution as electrolyte and ferrocene as internal reference to test the cyclic voltammetry curve of the second host material 2-27. The results are as follows: Fig.10 shown.

[0130] The oxidation potential of the material is estimated from the cyclic voltammetry curve of the test example, and then the HOMO of the material is calculated, and then the energy gap Eg of the compound is calculated according to the wavelength at the peak of the ultraviolet absorption spectrum, and finally the LUMO value of the compound is further calculated according to the Eg and HOMO values ​​(Eg = LUMO-HOMO). The test results of test examples 10 to 13 are shown in Table 2.

[0131] Table 2 Electrochemical data of test examples 10-13

[0132]

[0133] As can be seen from Table 2, the energy level structure of the material conforms to min((LUMO(1)-HOMO(2),LUMO(2)-HOMO(1))≤min(ET(1),ET(2))±0.2eV.

[0134] Test Examples Organic electroluminescent device embodiments and comparative examples.

[0135] The basic structures of the organic electroluminescent devices of the following Examples 1-33 and Comparative Examples 1-8 are as follows: Fig.11 As shown, ITO anode layer 100, hole injection layer 101 (HAT-CN, thickness 10nm), hole transport layer 102 (TAPC, thickness 30nm), hole transport layer 103 (TCTA, thickness 15nm), electron blocking layer 104 (20nm), light-emitting layer 105 (host material and guest material doping, as shown in Table 3, thickness 25nm; first host material: second host material: guest material, mass ratio mixed, as shown in Table 3, thickness 25nm), hole blocking layer 106 (as shown in Table 3, thickness 20nm), electron transport layer 107 (ANT-BIZ, 30nm), electron injection layer 108 (Liq, thickness 2nm) / cathode layer 109 (Al, thickness 100nm).

[0136] Table 3 Light-emitting layer, electron blocking layer, hole blocking layer of organic electroluminescent devices of Examples 1-33 and Comparative Examples 1-8

[0137]

[0138]

[0139]

[0140] The structures of the materials involved in the above embodiments and comparative examples are as follows:

[0141]

[0142] The performance of the organic electroluminescent devices prepared in the above examples and comparative examples is shown in Table 4 below.

[0143] Table 4 Performance of organic electroluminescent devices of Examples 1-33 and Comparative Examples 1-8

[0144]

[0145]

[0146]

[0147] The relationship between the external quantum efficiency and brightness of the organic electroluminescent devices in Example 1 and Comparative Example 1 is as follows: Fig.12 As shown; the current-voltage-brightness curves of the organic electroluminescent devices of Example 1 and Comparative Example 1 are as shown Fig.13The relationship between the external quantum efficiency and brightness of the organic electroluminescent device in Example 6 and Comparative Example 2 is shown as follows: Fig.14 The current-voltage-brightness curves of the organic electroluminescent devices of Example 6 and Comparative Example 2 are shown as follows: Fig.15 The relationship between the external quantum efficiency and brightness of the organic electroluminescent device in Example 20 is shown as Fig.16 As shown; the relationship between the external quantum efficiency and brightness of the organic electroluminescent device in Example 23 is as shown Fig.17 shown.

[0148] As can be seen from Table 4, a high-efficiency organic electroluminescent device can be successfully prepared by using a germanium-containing organic compound as a single host material. The organic electroluminescent device prepared by using the germanium-containing exciplex containing a mixture of the first host material and the second host material of the present invention has an improved external quantum efficiency (EQE) and a significantly reduced efficiency roll-off compared with the comparative example and the organic electroluminescent device containing only a single first host material or a second host material containing germanium (Examples 28-33 of the germanium-containing exciplex) and a single germanium-containing organic compound host (Examples 4-5, 7-8, 10-11, 15-16, 18-19, 21-22, 24-25); the organic electroluminescent device containing only a single first host material or a second host material containing germanium (Examples 28-33) is also better than the comparative example; the above results show that mixed host materials such as germanium-containing exciplexes have a significant gain in device performance. Therefore, the germanium-containing organic compound and the exciplex of the present invention can be applied to the field of organic electroluminescence, and the OLED device prepared using the germanium-containing exciplex has low efficiency roll-off, high luminous efficiency, higher current efficiency and power efficiency.

[0149] ΔE of the germanium-containing excited complex after mixing the first host material and the second host material in Test Example 3, Test Example 8, and Test Example 9 ST The value is consistent with the TADF characteristics.

[0150] The applicant declares that the present invention uses the above-mentioned embodiments to illustrate the germanium-containing exciplex and its application, but the present invention is not limited to the above-mentioned embodiments, that is, it does not mean that the present invention must rely on the above-mentioned embodiments to be implemented. Those skilled in the art should understand that any improvement of the present invention, equivalent replacement of the raw materials selected by the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A germanium-containing organic compound, characterized in that: It is a compound shown in the following general formula A: Among them, X1 may not exist, may be a single bond, or may be O, S, N, or C; R1, R2, and R3 are each independently selected from C1-C3 alkyl groups or independently selected from substituted or unsubstituted C4-C10 aryl or heteroaryl groups; Ar1 ​​is independently selected from substituted or unsubstituted C4-C10 aryl or heteroaryl groups; L1 is selected from substituted or unsubstituted hole transport groups or electron transport groups.

2. An organic mixture, characterized in that It includes at least one compound represented by general formula A and at least one compound represented by general formula B: Wherein, X2 may not exist, may be a single bond, may be O, S, N, C; R4, R5 and R6 are each independently selected from C1-C3 alkyl or independently selected from substituted or unsubstituted C4-C10 aryl or heteroaryl; Ar2 is independently selected from substituted or unsubstituted C4-C10 aryl or heteroaryl; L2 is selected from substituted or unsubstituted hole transport type group or electron transport type group; Furthermore, the compound represented by general formula A and the compound represented by general formula B are different compounds.

3. A germanium-containing exciplex, characterized in that: The invention is composed of a first host material and a second host material; the first host material contains a substituted or unsubstituted hole transport group selected from the compound represented by the general formula A and / or the compound represented by the general formula B in claim 2; the second host material contains a substituted or unsubstituted electron transport group selected from the compound represented by the general formula A and / or the compound represented by the general formula B in claim 2; at least one of the first host material and the second host material is a germanium-containing organic compound; wherein min((LUMO(1)-HOMO(2), LUMO(2)-HOMO(1))≤min(ET(1), ET(2))±0.2eV, wherein LUMO(1), HOMO(1) and E T (1) are the highest occupied molecular orbital, lowest unoccupied molecular orbital and triplet energy levels of the first host material, LUMO(2), HOMO(2) and E T (2) are the energy levels of the highest occupied orbital, lowest unoccupied orbital and triplet state of the second host material, respectively.

4. The germanium-containing exciplex according to claim 3, characterized in that: The hole transport group is selected from substituted or unsubstituted carbazole and diphenylamine.

5. The germanium-containing exciplex according to claim 3, characterized in that: The first host material is selected from compounds of formula 1-1 to 1-204:

6. The germanium-containing exciplex according to claim 3, characterized in that: The electron transport group is selected from substituted or unsubstituted 1,3,5-triazine and pyridyl.

7. The germanium-containing exciplex according to claim 3, characterized in that: The second host material is selected from compounds of formula 2-1 to 2-264:

8. An organic electroluminescent device, characterized in that: It comprises an anode layer, a cathode layer and a light-emitting functional layer located between the anode layer and the cathode layer; the light-emitting functional layer comprises the germanium-containing organic compound according to claim 1 or 2 or the germanium-containing excited complex according to any one of claims 3-7.

9. The organic electroluminescent device according to claim 8, characterized in that: The light-emitting functional layer includes a hole injection layer, a hole transport layer, a light-emitting layer, an electron transport layer, and an electron injection layer; the hole injection layer is formed on the anode layer, the hole transport layer is formed on the hole injection layer, the electron injection layer is formed on the electron transport layer, the cathode layer is formed on the electron injection layer, and the light-emitting layer is between the hole transport layer and the electron transport layer; wherein the light-emitting layer contains the germanium-containing excited complex.

10. The organic electroluminescent device according to claim 9, characterized in that: The light-emitting functional layer further comprises an electron blocking layer located between the hole transport layer and the light-emitting layer, wherein the electron blocking layer contains a compound shown in any one of the first host materials of claims 3 to 5; The light-emitting functional layer further comprises a hole blocking layer located between the light-emitting layer and the electron transport layer, and the hole blocking layer contains a compound shown in any one of the second host materials of claim 3, 6 or 7.

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