Synthesis and electroluminescent application of phenanthroimidazole-containing blue light heat exciton material
By modifying the blue light thermal exciton material containing phenanthromymidazole, using its long-range conjugation and nuclear energy level staggered arrangement characteristics, the problem of low exciton utilization in blue light OLED is solved, and high-efficiency and stable blue light OLED devices are achieved.
Patent Information
- Application Number
- CN202510439655.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-09
- Publication Date
- 2025-08-08
AI Technical Summary
The low exciton utilization rate of existing blue light OLED materials leads to insufficient device efficiency and lifetime, especially the difficulty in efficient utilization of triplet excitons, affecting the performance indicators of the device.
The blue thermal exciton material containing phenanthimidazole is used to modify the structure by introducing different groups containing aromatic rings or aromatic heterocycles and their derivative groups. The long-range conjugation and nuclear energy level staggered arrangement of phenanthimidazole-nuclear and modified groups are used to promote the generation of thermal exciton channels.
A photoluminescence quantum efficiency of nearly 80% is achieved, and a high-efficiency non-doped organic light emitting diode is obtained, which improves the luminescence efficiency and stability of blue light OLEDs.
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Abstract
Description
Technical Field
[0001] The present invention belongs to the field of organic photoelectric materials, and particularly relates to a phenanthroimidazole- Synthesis and electroluminescent applications of blue light-emitting thermoexciton materials. Background Art
[0002] Organic light-emitting diodes (OLEDs), a next-generation display and lighting technology, boast self-luminescence, high brightness, high luminous efficiency, low energy consumption, a wide color gamut, light weight, and excellent flexibility. Their applications in display and lighting fields are becoming increasingly widespread. The core technology behind OLED materials lies in the development of the OLED light-emitting layer. From traditional fluorescent and phosphorescent materials to third-generation fluorescent materials (including thermally activated delayed fluorescence, TTA, and thermoexciton materials), research on the types and mechanisms of luminescent materials has continued to advance, resulting in an increasing number of red, green, and blue luminescent materials. However, compared to red and green luminescent materials, the wide bandgap of blue luminescent materials typically results in a larger carrier injection barrier, which in turn affects carrier recombination and, consequently, device efficiency. Furthermore, the higher energy of blue light places high demands on the structural stability of the luminescent material. Consequently, the performance of blue OLEDs, such as luminous efficiency, lifetime, and efficiency roll-off, is limited, significantly disparate from that of red and green luminescent materials. Therefore, the design and fabrication of blue OLED devices with a wide bandgap, long lifetime, and low roll-off is a worthy research topic.
[0003] Indicators such as OLED efficiency and lifespan are closely related to the utilization of triplet excitons. According to spin statistics theory, electrically driven luminescent materials will produce 25% singlet excitons (S state) and 75% triplet excitons (T state). The process of singlet excitons radiating back to the ground state (S0) is spin-allowed, so it has a faster radiative transition rate. However, the electron spin direction of triplet excitons is the same as that of ground state electrons, and the process of their radiation back to the ground state is spin-forbidden, resulting in their radiative transition rate being far lower than that of singlet excitons, causing a large number of triplet excitons to undergo non-radiative transitions, releasing energy in the form of heat, etc., thereby reducing the exciton utilization rate of the material. In order to effectively utilize triplet excitons, thermally activated delayed fluorescence (TADF) materials, thermoexciton materials, and TTA materials have been proposed. However, due to the limitation of its anti-intersystem crossing rate, TADF materials have a serious efficiency roll-off at high current density, and there are few reports in the deep blue light field. TTA materials form a singlet state through triplet-triplet annihilation, and their theoretical maximum exciton utilization rate is 62.5%. Compared with TADF materials, they have no advantage in theoretical efficiency.
[0004] In contrast, the "hot exciton" materials proposed by Academician Ma Yuguang exhibit a large energy difference between their Tn (n≥2) and T1 states, making it difficult for excitons to internalize to the T1 state. Instead, they undergo a RISC transition from the high-energy triplet state to the singlet state, ultimately emitting light through radiative transition. These materials have a theoretical upper limit of 100% exciton utilization while ensuring device stability at high brightness, making them an effective approach for the production of high-efficiency blue OLEDs. However, current research on "hot exciton" materials primarily focuses on anthracene nuclei, with fewer reports on blue-emitting hot exciton materials based on other nuclei. Summary of the Invention
[0005] In order to overcome the above-mentioned shortcomings and deficiencies of the prior art, the primary purpose of the present invention is to provide a class of phenanthroimidazole- Blue light-emitting hot exciton materials, based on phenanthroimidazole- To build the foundation, different aromatic or heterocyclic groups and their derivatives were introduced to modify the structure, and phenanthroimidazole- Long-range conjugation between the core and the modified groups and bipolar transport of phenanthroimidazole The staggered arrangement of the nuclear energy levels achieves a photoluminescence quantum efficiency of nearly 80%, thereby obtaining a high-efficiency blue organic light-emitting diode.
[0006] Another object of the present invention is to provide the above-mentioned phenanthroimidazole-containing Application of blue light-emitting thermoexciton materials.
[0007] The purpose of the present invention is achieved through the following solutions:
[0008] A type of phenanthroimidazole-containing Blue light-emitting hot exciton materials, based on phenanthroimidazole- and its derivatives as the construction basis, introducing different aromatic ring or aromatic heterocyclic group and its derivative groups to carry out structural modification, wherein the derivative groups include halogenated or alkyl substituents thereof.
[0009] Preferably, the phenanthroimidazole-containing The blue light-emitting thermoexciton material has one of the following structural formulas:
[0010]
[0011] Ar1 is a phenanthroimidazole-containing group and one of its derivative groups, wherein the derivative group refers to a halogenated, C1-C 12 Alkyl chain substitution, C1-C 12 One of alkoxy chain substitution and cyano substitution.
[0012] Preferably, Ar1 is one of the following structural formulas:
[0013]
[0014] Ar2 is C6-C 30 One of the aromatic ring or aromatic heterocyclic group and its derivative groups.
[0015] Preferably, Ar2 is one of the following structural formulas and derivatives thereof, wherein the derivative refers to a halogenated product or a C1-C 12 The product of alkyl chain substitution:
[0016]
[0017] More preferably, the phenanthroimidazole-containing The blue light-emitting thermoexciton material has one of the following structural formulas:
[0018]
[0019] A blue light thermal exciton luminescent material, which is the above-mentioned phenanthroimidazole-containing The blue light thermal exciton material or the above-mentioned phenanthroimidazole-containing Molecules of structural fragments of blue light-emitting thermoexciton materials.
[0020] The application of the above-mentioned blue light thermoexciton luminescent material in organic electroluminescent devices, especially in organic light emitting diodes.
[0021] An organic electroluminescent device comprises, from bottom to top, an anode, a hole injection layer, a hole transport layer, an organic light-emitting layer, an electron transport layer, an electron injection layer, and a cathode; the light-emitting layer material comprises the blue light thermoexciton light-emitting material of the present invention.
[0022] The organic electroluminescent device further comprises an exciton blocking layer, which is located between the hole transport layer and the organic light-emitting layer.
[0023] Preferably, the organic light-emitting layer is a blue light thermoexciton luminescent material or a doped film of a blue light thermoexciton luminescent material and other light-emitting materials, and the other light-emitting material is preferably 3,3′-di(9H-carbazole-9-yl)-1,1′-biphenyl (mCBP).
[0024] Compared with the prior art, the present invention has the following advantages and beneficial effects:
[0025] 1. The luminescent molecules described in this application are phenanthroimidazole- In order to construct the unit, different aromatic ring or aromatic heterocyclic groups and their derivative groups are introduced to carry out structural modification, thereby achieving the regulation of the excited state and promoting the generation of thermal exciton channels.
[0026] 2. This application provides a class of phenanthroimidazole- Blue light thermal exciton material and its preparation method and application, due to phenanthroimidazole- Long-range conjugation between the core and the modified groups and bipolar transport of phenanthroimidazole The staggered arrangement of nuclear energy levels achieves high luminescence efficiency and high exciton utilization based on the thermal exciton mechanism, thereby obtaining a high-efficiency non-doped organic light-emitting diode. BRIEF DESCRIPTION OF THE DRAWINGS
[0027] Figure 1 is the hydrogen nuclear magnetic resonance spectrum of compound 1 in Example 1.
[0028] Figure 2 is the hydrogen nuclear magnetic resonance spectrum of compound 2 in Example 1.
[0029] Figure 3 is the hydrogen nuclear magnetic resonance spectrum of compound 3 in Example 1.
[0030] Figure 4 is the hydrogen nuclear magnetic resonance spectrum of the luminescent compound M1 in Example 1.
[0031] Figure 5 Thermogravimetric analysis diagrams of luminescent compounds M1-M4.
[0032] Figure 6 This is the absorption spectrum of the luminescent compounds M1-M4 in toluene solution.
[0033] Figure 7 The fluorescence emission spectra of luminescent compounds M1-M4 in toluene solution.
[0034] Figure 8 Electroluminescence spectra of non-doped devices prepared based on luminescent compounds M1-M4.
[0035] Figure 9 is the excited state energy level structure of M1 calculated by time-dependent density functional theory.
[0036] Figure 10 These are the low-temperature fluorescence and low-temperature phosphorescence spectra of the M1 molecule. DETAILED DESCRIPTION
[0037] The present invention will be described in further detail below with reference to the Examples and accompanying drawings, but the embodiments of the present invention are not limited thereto. Where specific conditions are not specified in the Examples, conventional conditions or conditions recommended by the manufacturer were followed. Reagents or instruments used, where the manufacturer is not specified, are commercially available conventional products.
[0038] The term "comprising" and other equivalent descriptions in the description and claims of this application are intended to cover non-exclusive inclusions, including both the contents clearly described in the description and claims and the steps or units that are not described in the description and claims but are inherent in the product, method or structure.
[0039] The electroluminescence test instrument and test conditions used in the examples are as follows:
[0040] The EL spectrum was obtained by using a Keithley 2450 source meter to provide direct current to apply a gradually increasing voltage to the device. The optical signal was collected by a PR745 and analyzed by computer.
[0041] Example 1
[0042] This embodiment provides a luminescent compound M1, whose molecular formula is C 52 H 31 N3, the structural formula is:
[0043]
[0044] Its specific synthetic route and steps are as follows:
[0045]
[0046] (1) Synthesis of Compound 1
[0047] 9,10-Phenanthrenequinone (12 mmol), 4-bromobenzaldehyde (12 mmol), aniline (24 mmol), ammonium acetate (50 mmol), and acetic acid (260 mL) were placed in a 500 mL round-bottom flask and purged with nitrogen three times. The mixed solution was allowed to react at 120°C for 4 hours. After the solution cooled to room temperature, it was evaporated under reduced pressure. The evaporated product was then poured into an aqueous solution and extracted several times with dichloromethane. Finally, the extract was dried over anhydrous magnesium sulfate and evaporated under reduced pressure to obtain a crude product, which was purified by silica gel column chromatography to obtain a white powder. 1 HNMR, 13 CNMR, MS and elemental analysis results showed that the obtained compound was the target product.
[0048] (2) Synthesis of Compound 2
[0049] 6,12-dibromo (12mmol), 4-cyanophenylboronic acid (12mmol), potassium carbonate (24mmol), and tetrakis(triphenylphosphine)palladium (1mmol) were placed in a 500mL round-bottom flask, and then the flask was filled with nitrogen. A mixed solution of 120mL tetrahydrofuran and 30mL water was injected into the round-bottom flask, and the mixed solution was refluxed at 70°C for 24 hours. When the solution was cooled to room temperature, it was evaporated under reduced pressure. Then, the evaporated product was poured into an aqueous solution and extracted several times with dichloromethane. Finally, the extract was dried over anhydrous magnesium sulfate and evaporated under reduced pressure to obtain a crude product, which was purified by silica gel column chromatography to obtain a white powder. 1 HNMR, 13 CNMR, MS and elemental analysis results showed that the obtained compound was the target product.
[0050] (3) Synthesis of Compound 3
[0051] A mixture of compound 2 (6 mmol), pinacol diboronate (9 mmol), potassium acetate (18 mmol), and [1,1'-bis(diphenylphosphino)ferrocene]palladium dichloride (1.32 mmol) was placed in a 250 mL round-bottom flask and filled with nitrogen. 120 mL of dioxane was added to the flask, and the mixed solution was refluxed at 90°C for 8 hours. After the solution cooled to room temperature, the reaction product was poured into an aqueous solution and extracted several times with dichloromethane. The extract was dried over anhydrous magnesium sulfate and evaporated under reduced pressure to obtain a crude product, which was purified by silica gel column chromatography to obtain a white powder. 1 HNMR, 13 CNMR, MS and elemental analysis results showed that the obtained compound was the target product.
[0052] (4) Synthesis of Compound M1
[0053] Compound 1 (12 mmol), compound 3 (12 mmol), tetrakis(triphenylphosphine)palladium (1 mmol), and potassium carbonate (24 mmol) were placed in a 250 mL round-bottom flask and filled with nitrogen. Then, a mixed solution of 120 mL of tetrahydrofuran and 30 mL of water was injected into the flask, and the mixed solution was refluxed at 70 ° C for 24 hours. When the solution was cooled to room temperature, it was evaporated under reduced pressure. Thereafter, the evaporated product was poured into an aqueous solution and extracted several times with dichloromethane. Finally, the extract was dried over anhydrous magnesium sulfate and evaporated under reduced pressure to obtain a crude product, which was purified by silica gel column chromatography to obtain a light green powder. 1 HNMR, 13 CNMR, MS and elemental analysis results showed that the obtained compound was the target product.
[0054] Example 2
[0055] This embodiment provides a luminescent compound M2, whose molecular formula is C 52 H 31 N3, the structural formula is:
[0056]
[0057] Its specific synthetic route and steps are as follows:
[0058]
[0059] (1) Synthesis of compound 4
[0060] 9,10-Phenanthrenequinone (12 mmol), 4-bromobenzaldehyde (12 mmol), aniline (24 mmol), ammonium acetate (50 mmol), and acetic acid (260 mL) were placed in a 500 mL round-bottom flask and purged with nitrogen three times. The mixed solution was allowed to react at 120°C for 4 hours. After the solution cooled to room temperature, it was evaporated under reduced pressure. The evaporated product was then poured into an aqueous solution and extracted several times with dichloromethane. Finally, the extract was dried over anhydrous magnesium sulfate and evaporated under reduced pressure to obtain a crude product, which was purified by silica gel column chromatography to obtain a white powder. 1 HNMR, 13 CNMR, MS and elemental analysis results showed that the obtained compound was the target product.
[0061] (2) Synthesis of compound 5
[0062] 6,12-dibromo (12mmol), 3-cyanophenylboronic acid (12mmol), potassium carbonate (24mmol), and tetrakis(triphenylphosphine)palladium (1mmol) were placed in a 500mL round-bottom flask, and then the flask was filled with nitrogen. A mixed solution of 120mL tetrahydrofuran and 30mL water was injected into the round-bottom flask, and the mixed solution was refluxed at 70°C for 24 hours. When the solution was cooled to room temperature, it was evaporated under reduced pressure. Then, the evaporated product was poured into an aqueous solution and extracted several times with dichloromethane. Finally, the extract was dried over anhydrous magnesium sulfate and evaporated under reduced pressure to obtain a crude product, which was purified by silica gel column chromatography to obtain a white powder. 1 HNMR, 13 CNMR, MS and elemental analysis results showed that the obtained compound was the target product.
[0063] (3) Synthesis of Compound 6
[0064] A mixture of compound 5 (6 mmol), pinacol diboronate (9 mmol), potassium acetate (18 mmol), and [1,1'-bis(diphenylphosphino)ferrocene]palladium dichloride (1.32 mmol) was placed in a 250 mL round-bottom flask and filled with nitrogen. 120 mL of dioxane was poured into the flask, and the mixed solution was refluxed at 90°C for 8 hours. After the solution cooled to room temperature, the reaction product was poured into an aqueous solution and extracted several times with dichloromethane. The extract was dried over anhydrous magnesium sulfate and evaporated under reduced pressure to obtain a crude product, which was purified by silica gel column chromatography to obtain a white powder. 1HNMR, 13CNMR, MS, and elemental analysis confirmed that the obtained compound was the target product.
[0065] (4) Synthesis of Compound M2
[0066] Compound 4 (12 mmol), compound 6 (12 mmol), tetrakis(triphenylphosphine)palladium (1 mmol), and potassium carbonate (24 mmol) were placed in a 250 mL round-bottom flask and filled with nitrogen. Then, a mixed solution of 120 mL of tetrahydrofuran and 30 mL of water was injected into the flask, and the mixed solution was refluxed at 70 ° C for 24 hours. When the solution was cooled to room temperature, it was evaporated under reduced pressure. Thereafter, the evaporated product was poured into an aqueous solution and extracted several times with dichloromethane. Finally, the extract was dried over anhydrous magnesium sulfate and evaporated under reduced pressure to obtain a crude product, which was purified by silica gel column chromatography to obtain a light green powder. 1 HNMR, 13 CNMR, MS and elemental analysis results showed that the obtained compound was the target product.
[0067] Example 3
[0068] This embodiment provides a luminescent compound M3, whose molecular formula is C 63 H 40 N2, the structural formula is:
[0069]
[0070] Its specific synthetic route and steps are as follows:
[0071]
[0072] (1) Synthesis of compound 7
[0073] 9,10-Phenanthrenequinone (12 mmol), 4-bromobenzaldehyde (12 mmol), aniline (24 mmol), ammonium acetate (50 mmol), and acetic acid (260 mL) were placed in a 500 mL round-bottom flask and purged with nitrogen three times. The mixed solution was allowed to react at 120°C for 4 hours. After the solution cooled to room temperature, it was evaporated under reduced pressure. The evaporated product was then poured into an aqueous solution and extracted several times with dichloromethane. Finally, the extract was dried over anhydrous magnesium sulfate and evaporated under reduced pressure to obtain a crude product, which was purified by silica gel column chromatography to obtain a white powder. 1 HNMR, 13 CNMR, MS and elemental analysis results showed that the obtained compound was the target product.
[0074] (2) Synthesis of Compound 8
[0075] 6,12-dibromo (12mmol), 3,5-diphenylboronic acid pinacol ester (12mmol), potassium carbonate (24mmol), and tetrakis(triphenylphosphine)palladium (1mmol) were placed in a 500mL round-bottom flask, and then the flask was filled with nitrogen. A mixed solution of 120mL tetrahydrofuran and 30mL water was injected into the round-bottom flask, and the mixed solution was refluxed at 70°C for 24 hours. When the solution was cooled to room temperature, it was evaporated under reduced pressure. Then, the evaporated product was poured into an aqueous solution and extracted several times with dichloromethane. Finally, the extract was dried over anhydrous magnesium sulfate and evaporated under reduced pressure to obtain a crude product, which was purified by silica gel column chromatography to obtain a white powder. 1 HNMR, 13 CNMR, MS and elemental analysis results showed that the obtained compound was the target product.
[0076] (3) Synthesis of compound 9
[0077] A mixture of compound 8 (6 mmol), pinacol diboronate (9 mmol), potassium acetate (18 mmol), and [1,1'-bis(diphenylphosphino)ferrocene]palladium dichloride (1.32 mmol) was placed in a 250 mL round-bottom flask and filled with nitrogen. 120 mL of dioxane was added to the flask, and the mixed solution was refluxed at 90°C for 8 hours. After the solution cooled to room temperature, the reaction product was poured into an aqueous solution and extracted several times with dichloromethane. The extract was dried over anhydrous magnesium sulfate and evaporated under reduced pressure to obtain a crude product, which was purified by silica gel column chromatography to obtain a white powder. 1 HNMR, 13 CNMR, MS and elemental analysis results showed that the obtained compound was the target product.
[0078] (4) Synthesis of Compound M3
[0079] Compound 7 (12 mmol), compound 9 (12 mmol), tetrakis(triphenylphosphine)palladium (1 mmol), and potassium carbonate (24 mmol) were placed in a 250 mL round-bottom flask and filled with nitrogen. Then, a mixed solution of 120 mL of tetrahydrofuran and 30 mL of water was injected into the flask, and the mixed solution was refluxed at 70 ° C for 24 hours. When the solution was cooled to room temperature, it was evaporated under reduced pressure. Thereafter, the evaporated product was poured into an aqueous solution and extracted several times with dichloromethane. Finally, the extract was dried over anhydrous magnesium sulfate and evaporated under reduced pressure to obtain a crude product, which was purified by silica gel column chromatography to obtain a light green powder. 1 HNMR, 13 CNMR, MS and elemental analysis results showed that the obtained compound was the target product.
[0080] Example 4
[0081] This embodiment provides a luminescent compound M4, whose molecular formula is C 69 H 52 N2, the structural formula is:
[0082]
[0083] The specific synthetic route and preparation method steps are as follows:
[0084]
[0085] (1) Synthesis of compound 10
[0086] 9,10-Phenanthrenequinone (12 mmol), 4-bromobenzaldehyde (12 mmol), aniline (24 mmol), ammonium acetate (50 mmol), and acetic acid (260 mL) were placed in a 500 mL round-bottom flask and purged with nitrogen three times. The mixed solution was allowed to react at 120°C for 4 hours. After the solution cooled to room temperature, it was evaporated under reduced pressure. The evaporated product was then poured into an aqueous solution and extracted several times with dichloromethane. Finally, the extract was dried over anhydrous magnesium sulfate and evaporated under reduced pressure to obtain a crude product, which was purified by silica gel column chromatography to obtain a white powder. 1 HNMR, 13 CNMR, MS and elemental analysis results showed that the obtained compound was the target product.
[0087] (2) Synthesis of compound 11
[0088] 6,12-dibromo (12 mmol), 4,4"-isopropyl-1,1':3',1"-diphenylphenylboronic acid pinacol ester (12 mmol), potassium carbonate (24 mmol), and tetrakis(triphenylphosphine)palladium (1 mmol) were placed in a 500 mL round-bottom flask, which was then filled with nitrogen. A mixed solution of 120 mL of tetrahydrofuran and 30 mL of water was injected into the round-bottom flask, and the mixed solution was refluxed at 70°C for 24 hours. After the solution cooled to room temperature, it was evaporated under reduced pressure. The evaporated product was then poured into an aqueous solution and extracted several times with dichloromethane. Finally, the extract was dried over anhydrous magnesium sulfate and evaporated under reduced pressure to obtain a crude product, which was purified by silica gel column chromatography to obtain a white powder. 1 HNMR, 13 CNMR, MS and elemental analysis results showed that the obtained compound was the target product.
[0089] (3) Synthesis of compound 12
[0090] A mixture of compound 11 (6 mmol), pinacol diboronate (9 mmol), potassium acetate (18 mmol), and [1,1'-bis(diphenylphosphino)ferrocene]palladium dichloride (1.32 mmol) was placed in a 250 mL round-bottom flask and filled with nitrogen. 120 mL of dioxane was added to the flask, and the mixed solution was refluxed at 90°C for 8 hours. After the solution cooled to room temperature, the reaction product was poured into an aqueous solution and extracted several times with dichloromethane. The extract was dried over anhydrous magnesium sulfate and evaporated under reduced pressure to obtain a crude product, which was purified by silica gel column chromatography to obtain a white powder. 1 HNMR, 13 CNMR, MS and elemental analysis results showed that the obtained compound was the target product.
[0091] (4) Synthesis of Compound M4
[0092] Compound 10 (12 mmol), compound 12 (12 mmol), tetrakis(triphenylphosphine)palladium (1 mmol), and potassium carbonate (24 mmol) were placed in a 250 mL round-bottom flask and filled with nitrogen. Then, a mixed solution of 120 mL of tetrahydrofuran and 30 mL of water was injected into the flask, and the mixed solution was refluxed at 70 ° C for 24 hours. When the solution was cooled to room temperature, it was evaporated under reduced pressure. Thereafter, the evaporated product was poured into an aqueous solution and extracted several times with dichloromethane. Finally, the extract was dried over anhydrous magnesium sulfate and evaporated under reduced pressure to obtain a crude product, which was purified by silica gel column chromatography to obtain a light green powder. 1 HNMR, 13 CNMR, MS and elemental analysis results showed that the obtained compound was the target product.
[0093] Figure 1-41-3 and the luminescent compound M1 in Example 1 are H NMR spectra. Figure 1-4 This shows that the structure of the product obtained in each step of the synthesis is consistent with the target product structure.
[0094] Figure 5 Thermogravimetric analysis diagrams of luminescent compounds M1-M4. Figure 5 It shows that M1-M4 has a higher thermal decomposition temperature, indicating that the material has good thermal stability and is suitable for vacuum evaporation for the preparation of OLEDs.
[0095] Figure 6 This is the absorption spectrum of the luminescent compounds M1-M4 in toluene solution. Figure 6 It shows that M1-M4 have a wide optical band gap, and the peak absorption is attributed to Nuclear π-π* transition.
[0096] Figure 7 The fluorescence emission spectra of luminescent compounds M1-M4 in toluene solution. Figure 7 It shows that the emission peaks of M1-M4 in toluene solution are 400-450nm, and all achieve bluer luminescence.
[0097] Figure 8 This is the electroluminescence spectrum of the organic light-emitting diode device described in Application Example 2 based on luminescent compounds M1-M4. As can be seen from Table 4, the OLED device based on M1-M4 has an emission peak in the 430-450 nm range, exhibiting deep blue light emission properties. Furthermore, the device achieves deep blue light emission while also having a high external quantum efficiency.
[0098] In order to prove that the material has the property of thermoexciton luminescence, theoretical calculation and spectral analysis were carried out using M1 as an example. The results are as follows Figure 9 、 10 shown.
[0099] Figure 9 is the excited state energy level structure of M1 calculated by time-dependent density functional theory. Figure 9 This shows that the S1 and T1 of the M1 material have a large energy level difference, which is close to the high-energy triplet state energy level, indicating that the material emits light through the thermal exciton mechanism.
[0100] Figure 10 These are the low-temperature fluorescence and low-temperature phosphorescence spectra of the M1 molecule. Figure 10 This indicates that there is a large peak position difference between the low-temperature fluorescence peak and the phosphorescence peak of the M1 molecule, which excludes the possibility of luminescence via the TADF mechanism, and indirectly indicates the possible existence of an effective thermal exciton channel.
[0101] In addition, since the materials described in the present invention are The core is the core building unit, so similar materials have similar energy level characteristics.
[0102] Application Example 1
[0103] This application embodiment provides a non-doped organic light-emitting diode device, and its preparation method is as follows: take a pre-prepared indium tin oxide (ITO) glass with a square resistance of 15Ω, clean it with detergent, deionized water, isopropyl alcohol and detergent ultrasonically in sequence, and plasma treat it for 3 minutes, then spin-coat polyethylene dioxythiophene doped poly (styrene sulfonate) (PEDOT:PSS) on the ITO surface as a hole injection layer, anneal it at 150°C for 30 minutes to obtain a hole injection layer with a thickness of 40nm; then place the wafer in a vacuum evaporation device, and wait until the vacuum degree of the vacuum device is 10 -5 Pa after A 20 nm thick 4,4',4"-tris(carbazol-9-yl)triphenylamine (TCTA) was evaporated at a rate of The luminescent layer (M1 to M4) was deposited at a rate of 20 nm thick. 1,3,5-tris(1-phenyl-1H-benzimidazol-2-ylbenzene) (TPBi) with a thickness of 30 nm was evaporated at a rate as an electron transport layer. After evaporating 1 nm thick lithium fluoride (LiF) as the electron injection layer at a rate of and Aluminum (Al) with a thickness of 10 nm and 90 nm was evaporated at a rate of 100 nm as the cathode. The device structure is: ITO / PEDOT:PSS / TCTA / light-emitting layer (M1-M4) / TPBi / LiF / Al.
[0104] The performance parameters of the prepared non-doped OLED device are shown in Table 1.
[0105] Table 1: Performance parameters of non-doped organic light-emitting devices
[0106] Luminescent materials Turn-on voltage (V) <![CDATA[Maximum brightness (cd m -2 )]]> Maximum external quantum efficiency (%) Color coordinates (x, y) M1 4.6 12000 12.2 (0.16,0.11) M2 4.8 11690 13.7 (0.15,0.09) M3 4.8 9320 9.5 (0.15,0.08) M4 5.0 8300 10.3 (0.14,0.07)
[0107] As can be seen from the table, all devices based on M1-M4 exhibit relatively blue emission, with CIE y coordinates close to the y value of 0.08 specified for standard blue light, and EL spectrum peaks between 440-450nm. In addition, the turn-on voltages of these devices are all between 4.0-4.4V, and they have high brightness and external quantum efficiency, indicating that the phenanthroimidazole-containing This type of blue light-emitting thermoexciton material can be used to construct efficient non-doped blue light-emitting organic light-emitting diode devices.
[0108] Application Example 2
[0109] This application embodiment provides a doped organic electroluminescent device, and its preparation method is as follows: take a pre-made indium tin oxide (ITO) glass with a square resistance of 15Ω, ultrasonically clean it with acetone, isopropyl alcohol, detergent, deionized water and anhydrous ethanol in sequence, and plasma treat it for 3 minutes. Then, in a vacuum evaporation device, A 5 nm thick 2,3,6,7,10,11-hexacyano-1,4,5,8,9,12-hexaazatriphenylene (HATCN) was deposited at a rate of A 50 nm thick N,N'-diphenyl-N,N'-(1-naphthyl)-1,1'-biphenyl-4,4'-diamine (NPB) was evaporated at a rate of 100 nm as a hole transport layer; 5 nm thick 4,4',4"-tris(carbazole-9-yl)triphenylamine (TCTA) was evaporated at a rate of 100 nm as an exciton blocking layer; then M1 to M4 and 3,3'-di(9H-carbazole-9-yl)-1,1'-biphenyl (mCBP) were added at a mass fraction ratio of 5%:95%. A 20 nm thick mixed film was evaporated at a rate of 40 nm thick 1,3,5-tris(1-phenyl-1H-benzimidazol-2-yl)benzene (TPBi) was evaporated at a rate of After evaporating 1 nm thick lithium fluoride (LiF) as the electron injection layer at a rate of Aluminum (Al) with thicknesses of 10 nm and 90 nm was evaporated as the cathode at a rate of 10 nm and 90 nm, respectively. Device structure: ITO / HATCN / NPB / TCTA / light-emitting layer (M1-M4 (5%): mCBP (95%)) / TPBi / LiF / Al.
[0110] The performance results of the prepared doped organic electroluminescent device are shown in Table 2.
[0111] Table 2: Performance parameters of doped OLED devices
[0112] Luminescent materials Turn-on voltage (V) <![CDATA[Maximum brightness (cd m -2 )]]> Maximum external quantum efficiency (%) Color coordinates (x, y) mCBP:M1 4.0 17350 13.2 (0.15,0.09) mCBP:M2 4.2 15860 14.9 (0.15,0.08) mCBP:M3 4.2 12370 10.7 (0.16,0.07) mCBP:M4 4.4 13560 12.6 (0.14,0.06)
[0113] As can be seen from Table 2, the doped device based on M1-M4 has a turn-on voltage of about 4.2V, and the device brightness and maximum external quantum efficiency are significantly improved compared with the non-doped device, proving that M1-M4 also has great application potential in doped devices.
[0114] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be considered as equivalent replacement methods and are included in the scope of protection of the present invention.
Claims
1. A class of phenanthroimidazole-containing The blue light-emitting thermoexciton material is characterized in that Has one of the following structural formulas: Ar1 is a phenanthroimidazole-containing group and one of its derivative groups, wherein the derivative group refers to a halogenated, C1-C 12 Alkyl chain substitution, C1-C 12 One of alkoxy substitution and cyano substitution; Ar2 is C6-C 30 One of the aromatic ring or aromatic heterocyclic group and its derivative groups, wherein the derivative groups refer to halogenated or C1-C 12 substituted with an alkyl chain.
2. The phenanthroimidazole-containing compound according to claim 1 The blue light-emitting thermoexciton material is characterized by: The Ar1 is one of the following structural formulas: Ar2 is one of the following structural formulas and its derivatives, wherein the derivative refers to the halogenated product or C1-C 12 The product of alkyl chain substitution:
3. The phenanthroimidazole-containing compound according to claim 1 The blue light-emitting thermoexciton material is characterized in that It has one of the following structural formulas:
4. A blue light-emitting thermoexciton luminescent material, characterized in that The phenanthroimidazole-containing compound according to any one of claims 1 to 3 The blue light thermal exciton material or the phenanthroimidazole-containing material according to any one of claims 1 to 3 Molecules of structural fragments of blue light-emitting thermoexciton materials.
5. Use of the blue light thermoexciton luminescent material according to claim 4 in an organic electroluminescent device.
6. Use of the blue light thermoexciton luminescent material according to claim 4 in an organic light emitting diode.
7. An organic electroluminescent device, characterized in that From bottom to top, it includes an anode, a hole injection layer, a hole transport layer, an organic light-emitting layer, an electron transport layer, an electron injection layer, and a cathode; the light-emitting layer material includes the blue light thermoexciton light-emitting material according to claim 4.
8. The organic electroluminescent device according to claim 7, wherein: The organic electroluminescent device further comprises an exciton blocking layer, which is located between the hole transport layer and the organic light-emitting layer.
9. The organic electroluminescent device according to claim 7, wherein: The organic light-emitting layer is a blue light thermoexciton light-emitting material or a doped film of a blue light thermoexciton light-emitting material and other light-emitting materials, and the other light-emitting material is 3,3'-di(9H-carbazole-9-yl)-1,1'-biphenyl.