An oled device based on thioxanthone derivative organic electroluminescent material

Abstract

The application discloses an OLED device of an organic electroluminescent material based on thioxanthone derivatives, and relates to the technical field of OLEDs.The OLED device structure is as follows: ITO / HATCN / TAPC / TcTa / mCP / organic electroluminescent material / TmPyPB / LiF / Al.The organic electroluminescent material is one of compounds 1-3 with carbazole and cyclothioxanthone as a core.The OLED device has high efficiency, a small degree of efficiency roll-off, low starting voltage, and can maintain high device efficiency under high brightness.

Description

Technical Field

[0001] This invention belongs to the field of OLED technology, specifically relating to an OLED device based on an organic electroluminescent material derived from thioxanthone derivatives. Background Technology

[0002] Organic light-emitting diodes (OLEDs), also known as organic light-emitting diodes, are a class of devices based on organic light-emitting materials. They convert electrical energy into light energy. Their working principle involves charge carriers being injected from two electrodes under an electric field and recombinating in the light-emitting layer, causing light emission. However, OLEDs fabricated with traditional fluorescent materials have very low efficiency because their exciton utilization rate is only about 25%. The remaining 75% of triplet excitons return to the ground state through non-radiative decay without emitting light.

[0003] OLEDs based on phosphorescent materials can achieve 100% exciton utilization, but their inclusion of precious metals, poor stability, and high manufacturing costs limit their practical application in electroluminescent devices. (Nat. Photon., 2012, 6: 253-258; Phys. Rev. B, 1999, 60: 14422-14428; Chem. Mater. 2012, 24, 2178–2185; Adv. Mater. 2013, 25, 2666–2671; Adv. Funct. Mater. 2013, 23, 2329–2337; Adv. Funct. Mater. 2014, 24, 3621–3630). In 2012, Professor Chihaya Adachi and colleagues first reported on purely organic TADF (Thermally Activated Delayed Fluorescence) materials and their OLED devices in the journal *Nature*. TADF materials utilize small ΔE... ST Molecular design allows triplet excitons to return to the singlet state and emit light through a RISC (Reverse Inter-System Crossing) process, theoretically achieving 100% exciton utilization. TADF possesses this characteristic of 100% exciton utilization and a unique light-emitting mechanism. Furthermore, it boasts lower cost, better stability, and meets the increasing demands for sustainable development and environmental protection. TADF materials are among the most promising light-emitting materials for OLEDs. However, because RISC is an upconversion process, it easily leads to a large accumulation of triplet excitons, making further brightness improvements difficult, and the efficiency roll-off problem remains severe.

[0004] Therefore, developing a type of OLED device with high stability, high brightness, and high luminous efficiency is a technical problem that the industry urgently needs to solve. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides an OLED device based on an organic electroluminescent material derived from thioxanthone derivatives.

[0006] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0007] An OLED device based on an organic electroluminescent material derived from thioxanthone, the structure of which is as follows:

[0008] ITO / HATCN / TAPC / TcTa / mCP / Organic Electroluminescent Materials / TmPyPB / LiF / Al

[0009] The organic electroluminescent material is one of the following compounds:

[0010]

[0011] Preferably, the synthetic route for compound 1 in the organic electroluminescent material is as follows:

[0012]

[0013] A further preferred embodiment is the method for synthesizing compound 1 in the organic electroluminescent material as follows:

[0014] C 13 H6Br2OS (i.e., compound M, with the structural formula shown below) and 5-phenyl-5,11-dihydroindolo[3,2-B]carbazole, sodium tert-butoxide, tris(dibenzylacetone)dipalladium and tritert-butylphosphine tetrafluoroborate were added to a reaction flask, the gas was purged three times, and then toluene was added and the reaction was heated. After the reaction was completed, the reaction solution was extracted with a 1:1 volume ratio of dichloromethane and water. The dichloromethane phase was collected as the extract, concentrated, and then column chromatography was performed to obtain compound 1.

[0015] The structural formula of compound M is shown below:

[0016]

[0017] Preferably, the synthetic route for compound 2 in the organic electroluminescent material is as follows:

[0018]

[0019] A further preferred embodiment is the method for synthesizing compound 2 in the organic electroluminescent material as follows:

[0020] Compound M, 5-phenyl-5,12-dihydroindolo[3,2-A]carbazole, sodium tert-butoxide, tris(dibenzylacetone)dipalladium, and tritert-butylphosphine tetrafluoroborate were added to a reaction flask. The mixture was purged three times, and toluene was added before heating. After the reaction was completed, the reaction solution was extracted with a mixture of dichloromethane and water at a volume ratio of 1:1. The dichloromethane phase was collected as the extract, which was then concentrated and purified by column chromatography to obtain compound 2.

[0021] Preferably, the synthetic route for compound 3 in the organic electroluminescent material is as follows:

[0022]

[0023] A further preferred embodiment is the method for synthesizing compound 3 in the organic electroluminescent material as follows:

[0024] M, 12-phenyl-5,12-dihydroindole[3,2-A]carbazole, sodium tert-butoxide, tris(dibenzylideneacetone)dipalladium, and tritert-butylphosphine tetrafluoroborate were added to a reaction flask, the gas was purged three times, toluene was added, and the reaction was heated. After the reaction was completed, the reaction solution was extracted with a mixture of dichloromethane and water, and the dichloromethane phase was collected as the extract. The extract was concentrated and purified by column chromatography to obtain compound 3.

[0025] The method for synthesizing compound M according to the present invention is as follows:

[0026]

[0027] (1) 3-Bromothiophenol (20 mmol), 4-bromo-2-fluorobenzonitrile (30 mmol), and potassium carbonate (40 mmol) were added to a reaction flask, the gas was purged three times, 100 mL of anhydrous N,N-dimethylformamide was added, and the reaction was heated to 150 °C. After the reaction was completed, the reaction solution was extracted with a mixture of dichloromethane and water, and the dichloromethane phase was collected as the extract. After concentration, the extract was subjected to column chromatography to obtain intermediate 1 with a yield of 94%.

[0028]

[0029] (2) Intermediate 1 was dissolved in 54 mL of ethanol and added to a reaction flask. Then, 54 mL of potassium hydroxide (388 mmol) aqueous solution was added to the reaction flask, and the mixture was stirred at room temperature. After the reaction, 80 mL of hydrochloric acid was added. The obtained solid was washed with water to obtain intermediate 2, with a yield of 83%.

[0030]

[0031] (3) Intermediate 2 was dissolved in 140 mL of dichloromethane and added to a reaction flask. Then, under ice bath conditions, trifluoroacetic anhydride (42 mmol) was added dropwise to the reaction flask, and the mixture was stirred for 5 minutes. Then, boron trifluoride diethyl ether (36 mmol) was added dropwise, and the mixture was stirred until it reached room temperature for 8 hours. The reactants were neutralized with saturated sodium bicarbonate aqueous solution. After the reaction was completed, the reaction solution was extracted with a mixture of dichloromethane and water at a volume ratio of 1:1. The dichloromethane phase was collected as the extract, concentrated, and then subjected to column chromatography to obtain compound M.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] The OLED device structure of this invention is as follows: ITO / HATCN / TAPC / TcTa / mCP / organic electroluminescent material / TmPyPB / LiF / Al. The OLED device of this invention has high efficiency, a small efficiency roll-off, and also a low start-up voltage, with even smaller efficiency roll-off at high brightness. Attached Figure Description

[0034] Figure 1 J–V–L curves of the OLED device prepared in Example 1;

[0035] Figure 2 The graph shows the external quantum efficiency of the OLED device prepared in Example 1 as a function of brightness.

[0036] Figure 3 The J–V–L curve of the OLED device prepared in Example 2;

[0037] Figure 4 The graph shows the external quantum efficiency of the OLED device prepared in Example 2 as a function of brightness.

[0038] Figure 5 The J–V–L curve of the OLED device prepared in Example 3;

[0039] Figure 6 The graph shows the external quantum efficiency of the OLED device prepared in Example 3 as a function of brightness. Detailed Implementation

[0040] To make the objectives, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention are described in detail below. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that the disclosure of the present invention will be thorough and complete.

[0041] Example 1

[0042] An OLED device based on an organic electroluminescent material derived from thioxanthone, the structure of which is as follows:

[0043] ITO / HATCN / TAPC / TcTa / mCP / Organic Electroluminescent Materials / TmPyPB / LiF / Al

[0044] The organic electroluminescent material is compound 1, and its structural formula is as follows:

[0045]

[0046] Its synthetic route is as follows:

[0047]

[0048] The specific synthetic steps involved adding compound M (1 mmol), 5-phenyl-5,11-dihydroindolo[3,2-B]carbazole (2.5 mmol), sodium tert-butoxide (6 mmol), tris(dibenzylacetone)dipalladium (0.16 mmol), and tri-tert-butylphosphine tetrafluoroborate (0.16 mmol) to a reaction flask. The mixture was purged three times, and 50 mL of toluene was added. The reaction was heated to 110 °C. The reaction solution was extracted with a 1:1 volume ratio of dichloromethane and water. The dichloromethane phase was collected as the extract, concentrated, and purified by column chromatography to obtain compound 1 in 55% yield.

[0049] The structure of compound 1 was determined as follows:

[0050] 1 H NMR(400MHz,THF-d8)δ8.95(d,J=8.6Hz,2H),8.39(s,2H),8.26–8.15(m,8H),8.04–8.01(m,2H),7 .80–7.67(m,8H),7.64(d,J=8.2Hz,2H),7.56–7.51(m,2H),7.48–7.35(m,6H),7.31–7.19(m,4H). 13 C NMR (100MHz, CDCl3) δ178.27,142.53,141.16,139.02,138.16,137.63,136.02,132.1 8,130.10,127.50,126.47,124.94,124.02,123.31,122.78,120.61,100.25,100.10.

[0051] High-resolution mass spectrometry (HRMS) (ESI, m / z) calcd. for C 61 H 37N4O1S1[M+H] + :895.2502; found:895.2514.

[0052] Figure 1 The graph shows the J-V-L curves of an OLED device made from compound 1 as an organic electroluminescent material. The graph indicates that the OLED device has a high maximum brightness and a low start-up voltage of 50440 cd / m². 2 , 3.4V. Figure 2 The graph shows the external quantum efficiency of the OLED device as a function of brightness. It can be seen from the graph that the device based on compound 1 has a maximum external quantum efficiency of 21.1% at a brightness of 10000 cd / m². 2 At that time, the external quantum efficiency remained at 7.5%.

[0053] Example 2

[0054] An OLED device based on an organic electroluminescent material derived from thioxanthone, the structure of which is as follows:

[0055] ITO / HATCN / TAPC / TcTa / mCP / Organic Electroluminescent Materials / TmPyPB / LiF / Al

[0056] The organic electroluminescent material is compound 2, and its structural formula is as follows:

[0057]

[0058] The synthesis route is as follows:

[0059]

[0060] Compound M (1 mmol), 5-phenyl-5,12-dihydroindolo[3,2-A]carbazole (2.5 mmol), sodium tert-butoxide (6 mmol), tris(dibenzylacetone)palladium (0.16 mmol), and tri-tert-butylphosphine tetrafluoroborate (0.16 mmol) were added to a reaction flask. The mixture was purged three times, and 50 mL of toluene was added. The reaction was heated to 110 °C. The reaction solution was extracted with a 1:1 volume ratio of dichloromethane and water. The dichloromethane phase was collected as the extract, concentrated, and purified by column chromatography to give the final product, compound 2, in 77% yield.

[0061] The results of the detection of compound 2 are as follows:

[0062] 1H NMR(400MHz,CD2Cl2)δ8.97(d,J=8.4Hz,2H),8.28–8.07(m,4H),7.94–7.87(m,2H) ,7.79–7.52(m,12H),7.45–7.19(m,10H),6.86–6.78(m,2H),6.26(d,J=8.1Hz,2H). 13 CNMR (100MHz, CDCl3) δ179.84,143.16,142.62,142.02,140.16,138.84,137.21,132. 96,131.33,129.38,127.70,126.57,124.58,122.74,122.53,119.10,113.16,104.20.

[0063] High-resolution mass spectrometry (HRMS) (ESI, m / z) calcd. for C 61 H 37 N4O1S1[M+H] + :895.2502; found:895.2505.

[0064] Figure 3 The graph shows the J-V-L curves of an OLED device using compound 2 as an organic electroluminescent material. As can be seen from the graph, this OLED device exhibits high maximum brightness and low startup voltage (56570 cd / m²). 2 , 3.2V. Figure 4 The graph shows the external quantum efficiency of the OLED device as a function of brightness. It can be seen from the graph that the maximum external quantum efficiency of the OLED device is 20.5% at a brightness of 10000 cd / m². 2 At that time, the external quantum efficiency remained at 12.1%.

[0065] Example 3

[0066] An OLED device based on an organic electroluminescent material derived from thioxanthone, the structure of which is as follows:

[0067] ITO / HATCN / TAPC / TcTa / mCP / Organic Electroluminescent Materials / TmPyPB / LiF / Al

[0068] The organic electroluminescent material is compound 3, and its structural formula is as follows:

[0069]

[0070] The synthetic route for compound 3 is as follows:

[0071]

[0072] Compound M (1 mmol), 12-phenyl-5,12-dihydroindole[3,2-A]carbazole (2.5 mmol), sodium tert-butoxide (6 mmol), tris(dibenzylacetone)palladium (0.16 mmol), and tri-tert-butylphosphine tetrafluoroborate (0.16 mmol) were added to a reaction flask, the mixture was purged three times, 50 mL of toluene was added, and the reaction was heated to 110 °C. The reaction mixture was extracted with a 1:1 volume ratio of dichloromethane and water, and the dichloromethane phase was collected as the extract. After concentration, the extract was purified by column chromatography to give the final product, compound 3, in 72% yield.

[0073] The results of the detection of compound 3 are as follows:

[0074] 1 H NMR (400MHz, CD2Cl2) δ8.92(d,J=8.6Hz,2H),8.25(d,J=8.5Hz,2H),8.17(d,J=7.1Hz,2H),7.95(d,J=1.9Hz,2H),7. 85–7.82(m,2H),7.71–7.64(m,10H),7.52–7.46(m,4H),7.38–7.26(m,8H),6.85–6.81(m,2H),5.98(d,J=8.2Hz,2H).

[0075] 13 C NMR (100MHz, CD2Cl2) δ178.84,140.89,133.17,131.31,130.21,126.69,123. 38,121.84,121.53,120.31,119.43,118.35,110.44,109.82,104.74,101.15.

[0076] High-resolution mass spectrometry (HRMS) (ESI, m / z) calcd. for C 61 H 37 N4O1S1[M+H] + :895.2502; found:895.2528.

[0077] Figure 5 The figure shows the J-V-L curves of the OLED device using organic electroluminescent material in Example 3. As can be seen from the figure, this OLED device has a high maximum brightness and a low start-up voltage of 43960 cd / m². 2 , 3.4V. Figure 6The graph shows the external quantum efficiency of the OLED device as a function of brightness. It can be seen from the graph that the maximum external quantum efficiency of the OLED device is 23.0% at a brightness of 10000 cd / m². 2 At that time, the external quantum efficiency remained at 10.5%.

[0078] As can be seen from Examples 1-3, the OLED devices fabricated using the organic optoelectronic material with carbazole-cyclothioxanthone as the core of this invention as the light-emitting layer have high efficiency and a small efficiency roll-off. OLED devices with simple structures based on this type of material have low start-up voltage, high efficiency, and even smaller efficiency roll-off at high brightness. This type of high-brightness, low-roll-off material has broad commercial prospects in the field of organic electroluminescence.

[0079] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. An OLED device based on an organic electroluminescent material derived from thioxanthone, characterized in that, The OLED device structure is as follows: ITO / HATCN / TAPC / TcTa / mCP / Organic Electroluminescent Materials / TmPyPB / LiF / Al The organic electroluminescent material is one of the following compounds:

2. The OLED device based on the thioxanthone derivative-based organic electroluminescent material according to claim 1, wherein the synthetic route of compound 1 in the organic electroluminescent material is as follows:

3. The OLED device based on the thioxanthone derivative-based organic electroluminescent material according to claim 1, wherein the synthetic route of compound 2 in the organic electroluminescent material is as follows:

4. The OLED device based on the thioxanthone derivative-based organic electroluminescent material according to claim 1, wherein the synthetic route of compound 3 in the organic electroluminescent material is as follows:

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