Near-infrared ytterbium complex as well as preparation method and application thereof

Abstract

The invention provides a near-infrared ytterbium complex as well as a preparation method and application thereof. The near-infrared ytterbium complex has a structure as shown in a formula I or a formula II, which is respectively called YbQ3 and [Yb (DPyPDA) 2] (DIEA) for short. Tests show that the photoluminescence quantum efficiency of YbQ3 is up to 10.69%, the luminescence life of YbQ3 is as long as 94 microseconds, and YbQ3 has good thermal stability and can emit near-infrared light of 978 nm under the excitation of visible light of 466 nm. Therefore, when YbQ3 is applied to near-infrared imaging, an excellent effect can be achieved. The [Yb (DPyPDA) 2] (DIEA) has excellent thermal stability and chemical stability and longer luminescence lifetime, the [Yb (DPyPDA) 2] (DIEA) is used as a luminescent material, the prepared OLEDs device can emit characteristic emission of ytterbium ions in a near-infrared region at 978nm, and the [Yb (DPyPDA) 2] (DIEA) has higher near-infrared irradiance under different operating voltages.

Description

Technical Field

[0001] The invention belongs to the field of metal complexes, and in particular relates to a near-infrared ytterbium complex and a preparation method and application thereof. Background Art

[0002] Near-infrared complexes based on rare earth ions such as neodymium (Nd), erbium (Er), and ytterbium (Yb) have the advantages of long luminescence lifetime, narrow emission half-peak width, and strong ligand design and modification, and have broad application prospects in the fields of biological imaging, optical fiber communication, infrared imaging, and organic light-emitting diodes (OLEDs). 3+ , Er 3+ Compared with other 3+ The excited state energy level of Yb is relatively high and is less affected by the quenching of high-energy vibration bonds. 3+ The excited state energy level of ytterbium is single, and theoretically has fewer non-radiative transition pathways and higher internal quantum efficiency, so ytterbium complexes have higher photoluminescence quantum efficiency. However, the pursuit of near-infrared ytterbium complexes with higher quantum efficiency, better chemical and thermal stability, and simple synthesis and low cost is still a concern of many researchers.

[0003] Currently, there are reports of perfluorinated porphyrin ring sensitization, full deuterated The quantum efficiency of the ligand-protected near-infrared ytterbium complex has reached 63%. However, due to the great difficulty and high cost of perfluorinated and perdeuterated synthesis, and the fact that perfluorinated complexes can greatly reduce the thermal and chemical stability of the complex, it is not suitable for mass synthesis and application. Michael Seitz reported a complex sensitized by a non-fluorinated, non-deuterated bipyridine derivative, which simplified the synthesis process, reduced the synthesis cost, and improved the thermal and chemical stability of the complex. The quantum efficiency reached 3%, but this is the highest quantum efficiency reported so far for near-infrared luminescence of ytterbium ions sensitized by non-fluorinated, non-deuterated ligands, and it still cannot meet the needs of application scenarios. Further improving the luminescence efficiency is still a key topic at present. Summary of the invention

[0004] In view of this, the object of the present invention is to provide a near-infrared ytterbium complex and a preparation method and application thereof. The near-infrared ytterbium complex has excellent performance.

[0005] To achieve this object, the present invention adopts the following technical solutions:

[0006] In a first aspect, the present invention provides a near-infrared ytterbium complex having a structure shown in Formula I or Formula II:

[0007]

[0008] Wherein, R1 to R3 are independently selected from hydrogen, nitro, trihaloalkyl, substituted or unsubstituted C1 to C6 alkoxy, substituted or unsubstituted C1 to C6 alkyl;

[0009] Or R1, R2 and the carbon atoms where they are located form an aromatic ring; R2, R3 and the carbon atoms where they are located form an aromatic ring.

[0010] Preferably, R1 to R3 are independently selected from hydrogen, nitro, trihalomethyl, substituted or unsubstituted C1 to C3 alkoxy, substituted or unsubstituted C1 to C4 alkyl;

[0011] Or R1, R2 and the carbon atoms where they are located form a benzene ring; R2, R3 and the carbon atoms where they are located form a benzene ring.

[0012] Preferably, the near-infrared ytterbium complex shown in Formula II is selected from any one of the following Formulas 1 to 7:

[0013]

[0014]

[0015] In a second aspect, the present invention provides a method for preparing a near-infrared ytterbium complex as shown in the above formula I, comprising the following steps:

[0016] S1: reacting a ligand precursor represented by formula A with phenylhydrazine in the presence of a solvent to obtain a ligand represented by formula B;

[0017] S2: reacting a solution of the ligand represented by formula B with a solution of an ytterbium compound to obtain a near-infrared ytterbium complex represented by formula I;

[0018]

[0019] Preferably, the solvent is selected from ethanol.

[0020] Preferably, the solvent in the solution of the ligand represented by formula B is selected from acetone.

[0021] Preferably, the solvent in the solution containing the ytterbium compound is selected from ethanol.

[0022] Preferably, the ytterbium-containing compound is selected from any one or more of ytterbium chloride, ytterbium nitrate or ytterbium trifluoromethanesulfonate.

[0023] Preferably, the molar ratio of the ligand precursor represented by formula A to phenylhydrazine is 1:3.2 to 1:3.8.

[0024] Preferably, the molar ratio of the ligand represented by formula B to the ytterbium-containing compound is 2.8:1 to 3.2:1.

[0025] Preferably, the reaction temperature in step S1 is 75-90° C. and the reaction time is 6-10 h.

[0026] Preferably, the reaction temperature in step S2 is 45-65° C. and the reaction time is 6-10 h.

[0027] Preferably, after the reaction in step S2 is completed, a purification step is also included.

[0028] In a third aspect, the present invention provides a method for preparing a near-infrared ytterbium complex as shown in the above formula ⅠⅠ, comprising the following steps:

[0029] S1: Under ice-water bath conditions, dimethyl-o-phenanthroline is reacted with sulfuric acid in the presence of potassium bromate to obtain a ligand precursor shown in formula C;

[0030] S2: reacting the ligand precursor represented by formula C with the compound represented by formula D in the presence of a solvent to obtain the ligand represented by formula E;

[0031] S2: mixing and reacting a solution of the ligand represented by formula E, diisopropylethylamine and a solution of the ytterbium compound to obtain a near-infrared ytterbium complex represented by formula ⅠⅠ;

[0032]

[0033] Preferably, the solvent is selected from ethanol.

[0034] Preferably, the solvent in the solution of the ligand represented by formula E is selected from ethanol.

[0035] Preferably, the solvent in the solution containing the ytterbium compound is selected from ethanol.

[0036] Preferably, the ytterbium-containing compound is selected from any one or more of ytterbium chloride, ytterbium nitrate or ytterbium trifluoromethanesulfonate.

[0037] Preferably, the molar ratio of dimethylphenanthroline, sulfuric acid and potassium bromate is 1:(90-110):(1-1.2).

[0038] Preferably, the molar ratio of the ligand precursor represented by formula C to the compound represented by formula D is 1:1.05 to 1:1.15.

[0039] Preferably, the molar ratio of the ligand represented by formula E, diisopropylethylamine and the ytterbium-containing compound is (2.8-3.2):(5.6-6.4):1.

[0040] Preferably, the reaction temperature in steps S1 and S3 is independently 15 to 30° C., and the reaction time is 20 to 36 hours.

[0041] Preferably, the reaction temperature in step S2 is 15-30° C. and the reaction time is 4-10 h.

[0042] In a fourth aspect, the present invention provides a use of the near-infrared ytterbium complex represented by the above formula I in near-infrared imaging.

[0043] In a fifth aspect, the present invention provides a use of the near-infrared ytterbium complex represented by the above formula Ⅱ in the preparation of a near-infrared organic light-emitting diode.

[0044] Compared with the prior art, the present invention has the following beneficial effects:

[0045] The present invention provides a near-infrared ytterbium complex having a structure shown in Formula I or Formula II. In the present invention, the near-infrared ytterbium complex shown in Formula I is referred to as YbQ3; the near-infrared ytterbium complex shown in Formula II is referred to as [Yb(DPyPDA)2](DIEA).

[0046] Among them, YbQ3 is a non-fluorinated, non-deuterated near-infrared ytterbium complex. Its core structure, octahydroxyquinoline structure, has excellent luminescence properties and can efficiently transfer energy to Yb ions. At the same time, its oxygen and nitrogen chelate structure has good stability. According to tests, the photoluminescence quantum efficiency of YbQ3 is as high as 10.69%, and its luminescence lifetime is as long as 94 microseconds. It has good thermal stability and can emit 978nm near-infrared light under the excitation of 466nm visible light. Therefore, the application of YbQ3 in near-infrared imaging can achieve the effect of long-distance infrared signal detection under visible light excitation.

[0047] [Yb(DPyPDA)2](DIEA) has a rigid conjugated plane, which reduces the quenching of near-infrared luminescence by the non-radiative relaxation process, thereby improving the luminescence performance. At the same time, its dicarboxylic acid chelated structure greatly increases its stability. According to tests, [Yb(DPyPDA)2](DIEA) has excellent thermal and chemical stability and a longer luminescence lifetime. Using it as a luminescent material, the prepared organic light-emitting diode (OLEDs) device can emit the characteristic emission of ytterbium ions at 978nm in the near-infrared region, and has a high near-infrared irradiance at different operating voltages. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 Schematic diagram of the synthesis route of YbQ3;

[0049] Figure 2 Schematic diagram of the synthesis route of [Yb(DPyPDA)2](DIEA);

[0050] Figure 3 is the luminescence lifetime diagram of YbQ3;

[0051] Figure 4 It is the thermogravimetric curve of YbQ3;

[0052] Figure 5 The excitation spectrum and emission spectrum of YbQ3;

[0053] Figure 6 Schematic diagram of photoluminescence quantum efficiency of YbQ3;

[0054] Figure 7 The excitation and emission spectra of [Yb(L7)2](DIEA);

[0055] Figure 8 is the luminescence lifetime diagram of [Yb(L7)2](DIEA);

[0056] Fig. 9 is the thermogravimetric curve of [Yb(L7)2](DIEA);

[0057] Fig.10 Schematic diagram of the near-infrared luminescence stability of [Yb(L7)2](DIEA) in solid and solution states;

[0058] Fig.11 The electroluminescence spectrum of a near-infrared organic light-emitting diode prepared using the near-infrared ytterbium complex [Yb(L7)2](DIEA) as the luminescent material;

[0059] Fig.12 The voltage-current density-near infrared irradiance characteristic curve of the near-infrared organic light-emitting diode prepared with [Yb(L7)2](DIEA) as the luminescent material;

[0060] Fig.13 The voltage-current density-near infrared irradiance characteristic curve of the near-infrared organic light-emitting diode prepared with [Yb(L5)2](DIEA) as the luminescent material;

[0061] Fig.14 The voltage-current density-near infrared irradiance characteristic curve of the near-infrared organic light-emitting diode prepared with [Yb(L1)2](DIEA) as the luminescent material;

[0062] Fig.15 It is a schematic diagram of the structure of a near-infrared organic light-emitting diode device;

[0063] Among them, 1 is substrate 1, 2 is anode layer, 3 is hole injection layer, 4 is light-emitting layer, 5 is electron transport layer / hole blocking layer, 6 is cathode modification layer, and 7 is metal cathode layer. DETAILED DESCRIPTION

[0064] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0065] At present, a very small number of near-infrared ytterbium complexes with high photoluminescence quantum efficiency have problems such as high synthesis cost, great synthesis difficulty, poor chemical stability and thermal stability, and limited batch synthesis and practical application; while most near-infrared ytterbium complexes with simple synthesis process, low synthesis cost, good chemical stability and thermal stability have low quantum efficiency, less than 3%.

[0066] Therefore, the present invention provides a near-infrared ytterbium complex, characterized in that it has a structure shown in Formula I or Formula II:

[0067]

[0068] Wherein, R1 to R3 are independently selected from hydrogen, nitro, trihaloalkyl, substituted or unsubstituted C1 to C6 alkoxy, substituted or unsubstituted C1 to C6 alkyl;

[0069] Or R1, R2 and the carbon atoms where they are located form an aromatic ring; R2, R3 and the carbon atoms where they are located form an aromatic ring.

[0070] In the present invention, the near-infrared ytterbium complex shown in Formula I can be referred to as YbQ3 for short. As a non-fluorinated, non-deuterated near-infrared ytterbium complex, its core structure of octahydroxyquinoline structure has excellent luminescence performance and can efficiently transfer energy to Yb ions. At the same time, its oxygen and nitrogen chelate structure has good stability. According to the test, the photoluminescence quantum efficiency of YbQ3 is as high as 10.69%, its luminescence lifetime is as long as 94 microseconds, it has good thermal stability, and can emit 978nm near-infrared light under the excitation of 466nm visible light.

[0071] The present invention also provides a method for preparing the above YbQ3, comprising the following steps:

[0072] S1: reacting a ligand precursor represented by formula A with phenylhydrazine in the presence of a solvent to obtain a ligand represented by formula B;

[0073] S2: reacting a solution of the ligand represented by formula B with a solution of an ytterbium compound to obtain YbQ3;

[0074]

[0075] According to the present invention, the ligand precursor shown in formula A is reacted with phenylhydrazine in the presence of a solvent to obtain the ligand shown in formula B. The molar ratio of the ligand precursor shown in formula A to phenylhydrazine is 1:3.2 to 1:3.8, preferably 1:3.5; the solvent is preferably ethanol. In the present invention, the ligand precursor shown in formula A can be prepared according to the following method:

[0076] Mix aldehyde hydroxyquinoline with concentrated hydrochloric acid, heat and stir at 40-60°C, preferably 50°C, then add acetophenone dropwise into the reaction system, and stop heating when the reaction system turns from turbid to clear, and continue stirring for 2-4 hours. Pour the obtained liquid onto crushed ice, filter, wash the filtered solid with ether, air dry naturally, and then dry at 60-80°C, preferably 70°C.

[0077] In some preferred embodiments of the present invention, after obtaining the ligand precursor shown in formula A, it is uniformly dispersed in ethanol and stirred at room temperature for 10 to 40 minutes, preferably 20 to 30 minutes. Phenylhydrazine is then added dropwise and the solid is observed to dissolve. The reaction solution is refluxed at 75 to 90°C, preferably 80 to 85°C for 6 to 10 hours, preferably 8 to 9 hours, to obtain the ligand shown in formula B. In some more preferred embodiments of the present invention, after the reaction is completed, it is preferably filtered, and the filtered solid (that is, the ligand shown in formula B) is preferably washed and dried. The washing is carried out with ice ethanol, and the drying is carried out after air drying, and the drying is preferably carried out at 60 to 80°C, more preferably at 70°C.

[0078] After obtaining the ligand shown in formula B, according to the present invention, the solution of the ligand shown in formula B is reacted with the solution of the ytterbium-containing compound to obtain YbQ3. Wherein, the solvent in the solution of the ligand shown in formula B is preferably acetone, and the solvent in the solution of the ytterbium-containing compound is preferably ethanol, and the ytterbium-containing compound is selected from any one or more of ytterbium chloride, ytterbium nitrate or ytterbium trifluoromethanesulfonate, preferably ytterbium chloride. In the present invention, the molar ratio of the ligand shown in formula B to the ytterbium-containing compound is 2.8:1 to 3.2:1, preferably 3:1, and the reaction of the two is preferably carried out at 45 to 65°C for 6 to 10 hours, and more preferably at 45 to 55°C for 8 to 9 hours.

[0079] In some preferred embodiments of the present invention, the ligand is preferably dispersed in acetone, an ethanol solution containing ytterbium chloride is added dropwise, and refluxed at 55°C for 8 hours, filtered, and the filtered solid is washed with acetone and then dried at 70°C.

[0080] In some more preferred embodiments of the present invention, the reaction of the ligand represented by formula B with the ytterbium-containing compound further comprises a purification step. The present invention preferably uses a vacuum sublimation purification device to further purify the crude YbQ3 product. Specifically, the crude YbQ3 product is purified by a vacuum sublimation purification device at a concentration of less than 1×10 -4Under a vacuum degree of 100 Pa, the temperature is kept at 130°C for 7 days to sublimate and remove small molecule impurities of organic ligands contained in the crude product, thereby improving the purity of YbQ3.

[0081] Exemplarily, the synthesis route of YbQ3 is as follows (for specific methods, refer to the above-mentioned related content):

[0082]

[0083] It can be seen that the preparation method of the above-mentioned YbQ3 provided by the present invention is simple, convenient, easy to implement, and is conducive to large-scale production or industrial production.

[0084] It should be noted that the YbQ3 provided by the present invention has a very high photoluminescence quantum efficiency compared with other non-fluorinated, non-deuterated near-infrared ytterbium complexes, which helps to improve the signal recognition of infrared imaging.

[0085] Based on this, the present invention provides applications of YbQ3 near-infrared imaging detection and signal recognition, which can achieve the effect of long-distance infrared signal detection under visible light excitation.

[0086] As is known to all, the recognition degree of the near-infrared rare earth complex imaging detection signal mainly depends on two aspects: one is the luminescence effect of the near-infrared rare earth complex itself; the other is the signal acquisition and processing capability of the near-infrared detection equipment. The YbQ3 provided by the present invention has a very high photoluminescence quantum efficiency. Therefore, the present invention further optimizes the acquisition and processing capability of the near-infrared imaging and detection equipment. The optimization process is as follows:

[0087] (1) Select a suitable near-infrared camera: First, place the YbQ3 in a well-lit location indoors and adjust the near-infrared zoom lens to the maximum aperture and optimal focal length. Then, observe the signal recognition capabilities of different near-infrared cameras at close range, and finally select a camera that can recognize the clear near-infrared light signal of the YbQ3 for long-distance imaging testing.

[0088] (2) Select a suitable camera lens: First, place YbQ3 under the light of the corridor, and ensure that the distance between the camera lens and the YbQ3 sample is greater than 50 meters, and then replace the near-infrared lens to perform near-infrared imaging and detection experiments. The experiment found that the zoom lens has multiple filters, which will cause serious signal attenuation. At the same time, its large size is not portable, which is not conducive to practical imaging applications. Therefore, the present invention is equipped with a 100-meter fixed-focus lens with band matching, and eliminates the interference of stray light on near-infrared imaging and signal detection by optimizing the lens transmittance range, assembling narrow-band filters and polarizers. The test shows that the polarizer has little effect on signal collection, and the filter can effectively filter out stray light in other bands. By customizing and assembling narrow-band filters of specific bands (975±5nm), the detection limit and sensitivity of the infrared detection equipment are improved, and long-distance infrared imaging and detection under outdoor sunlight are realized.

[0089] In the present invention, the near-infrared ytterbium complex shown in formula ⅠⅠ can be abbreviated as [Yb(DPyPDA)2](DIEA), which has a rigid conjugated plane, reduces the quenching of near-infrared luminescence by the non-radiative relaxation process, thereby improving the luminescence performance. At the same time, its dicarboxylic acid chelated structure greatly increases its stability.

[0090] In some embodiments of the present invention, the near-infrared ytterbium complex has a structure shown in Formula II, wherein R1 to R3 are independently preferably selected from hydrogen, nitro, trihalomethyl, substituted or unsubstituted C1 to C3 alkoxy, substituted or unsubstituted C1 to C4 alkyl;

[0091] Or R1, R2 and the carbon atoms where they are located form a benzene ring; R2, R3 and the carbon atoms where they are located form a benzene ring.

[0092] In some preferred embodiments of the present invention, the near-infrared ytterbium complex has a structure shown in Formula II, wherein R1 to R3 are independently preferably selected from hydrogen, nitro, trifluoromethyl, methoxy or tert-butyl;

[0093] Or R1, R2 and the carbon where they are located form a benzene ring.

[0094] In some specific embodiments of the present invention, the near-infrared ytterbium complex shown in Formula II is selected from any one of the following Formulas 1 to 7:

[0095]

[0096]

[0097] The near-infrared ytterbium complexes [Yb(DPyPDA)2](DIEA) represented in the above formulas 1 to 7 can be abbreviated as: [Yb(L1)2](DIEA), [Yb(L2)2](DIEA), [Yb(L3)2](DIEA), [Yb(L4)2](DIEA), [Yb(L5)2](DIEA), [Yb(L6)2](DIEA), [Yb(L7)2](DIEA), and their corresponding ligands can be abbreviated as: L1-DPyPDA, L2-DPyPDA, L3-DPyPDA, L4-DPyPDA, L5-DPyPDA, L6-DPyPDA, L7-DPyPDA.

[0098] Among them, the infrared spectrum and mass spectrum data corresponding to the ligand are as follows:

[0099] [1]L1-DPyPDA: 1 H-NMR(500MHz,DMSO)δ9.74(d,2H),8.57(d,2H),8.45(m,2H),8.13(m,2H).IR(KBr disk):3200-2400,1722,1571,1482,1448,1391cm -1 .ESI-MS(DMF,positive mode):m / z:calculated for C 20 H 10 N4O4(TM),370.07; found,393.32(TM+Na + ).

[0100] [2]L2-BDPyPDA: 1 H-NMR(500MHz,DMSO)δ9.73(d,2H),9.16(s,2H),8.57(d,2H),8.40(m,2H),7.75(m,2H).IR(KBr disk):3200-2400,1722,1570,1444,1382cm -1 .ESI-MS(DMF,negative mode):m / z:calculated for C 24 H 12 N4O4(TM),420.38; found,438.48(TM+H2O+e - ).

[0101] [3]L3-MO-DPyPDA: 1H-NMR(500MHz,DMSO)δ9.53(m,2H),8.49(t,2H),8.20(d,1H),7.67(d,1H),7.58(s,1H),4.06(s,3H).IR(KBr disk):3200-2400,1725,1621,1597,1567,1500,1480,1434,1414,1382,1242,1012cm -1 .ESI-MS(DMF,negative mode):m / z:calculated for C 21 H 12 N4O5(T.M.),400.34;found,418.44(T.M.+H2O+e - ).

[0102] [4]L4-NO-DPyPDA: 1 H-NMR(500MHz,DMSO)δ13.75(br,2H),9.52(s,2H),9.08(s,1H),8.69(d,1H),8.52(d,1H),8.47(dd,2H).IR(KBr disk):3200-2400,1722,1623,1598,1572,1557,1525,1479,1448,1379,1348cm -1 .ESI-MS(CH3CH2OH+DIEA,negative mode):m / z:calculated for C 20 H7N5O 62 - (T.M.),413.31;found,436.21[(T.M.+Na + ) - ].

[0103] [5]L5-TFM-DPyPDA: 1 H-NMR(500MHz,DMSO)δ13.66(br,2H),9.34(s,2H),8.54(s,1H),8.37(s,3H),8.21(d,1H).IR(KBr disk):3200-2400,1731,1572,1482,1450,1393,1171,1128cm -1 .ESI-MS(DMF,positive mode):m / z:calculated for C 21H9F3N4O4(TM),438.32; found,461.20(TM+Na + ).

[0104] [6] L6-TBu-DPyPDA: 1 H-NMR(500MHz,DMSO)δ9.60(m,2H),8.50(dd,2H),8.18-8.31(m,3H),1.51(s,9H).IR(KBr disk):3200-2400,2961,1727,1623,1599,1568,1498,1479,1453,1381cm -1 .ESI-MS(DMF,negative mode):m / z:calculated for C 24 H 18 N4O4(TM),426.13; found,444.12(TM+H2O+e - ).

[0105] [7]L7-DTFM-DPyPDA: 1 H-NMR(500MHz,DMSO)δ9.69(d,1H),9.61(d,1H),9.15(s,1H),8.72(s,1H),8.62(m,2H).IR(KBr disk):3200-2400,1732,1580,1478,1456,1388,1192,1144cm -1 .ESI-MS(DMF,negative mode):m / z:calculated for C 22 H8F6N4O4(TM),506.3; found,524.0(TM+H2O+e - ).

[0106] Among them, the infrared spectrum and mass spectrum data corresponding to the complex are as follows:

[0107] [1][Yb(L1)2](DIEA):IR(KBr disk):1653,1578,1486,1449,1371cm -1 .ESI-MS(DMF,negative mode):m / z:calculated for[Yb(L1)2] - (TM),910.1;found,910.4(TM).

[0108] [2][Yb(L2)2](DIEA):IR(KBr disk):1651,1578,1450,1399,1380cm -1 .ESI-MS(DMF,negative mode):m / z:calculated for[Yb(L2)2] - (T.M.),1010.1;found,1010.4(T.M.).

[0109] [3][Yb(L3)2](DIEA):IR(KBr disk):1653,1606,1577,1500,1484,1444,1416,1368cm -1 .ESI-MS(DMF,negative mode):m / z:calculated for[Yb(L3)2] - (T.M.),970.0;found,970.3(T.M.).

[0110] [4][Yb(L4)2](DIEA):IR(KBr disk):1657,1609,1579,1484,1446,1381cm -1 .ESI-MS(DMF,negative mode):m / z:calculated for[Yb(L4)2] - (T.M.),1000.0;found,1000.4(T.M.).

[0111] [5][Yb(L5)2](DIEA):IR(KBr disk):1657,1611,1577,1474,1448,1380,1371cm -1 .ESI-MS(DMF,negative mode):m / z:calculated for[Yb(L5)2] - (T.M.),1046.0;found,1046.2(T.M.).

[0112] [6][Yb(L6)2](DIEA):IR(KBr disk):1635,1606,1591,1499,1454,1387,1368cm -1 .ESI-MS(DMF,negative mode):m / z:calculated for[Yb(L6)2] - (T.M.),1021.9;found,1021.4(T.M.).

[0113] [7][Yb(L7)2](DIEA):IR(KBr disk):1662,1613,1581,1484,1452,1388,1371cm -1 .ESI-MS(DMF,negative mode):m / z:calculated for[Yb(L7)2] - (TM),1182.0; found,1182.8(TM).

[0114] As a preferred technical solution, [Yb(DPyPDA)2](DIEA) is selected from any one of the above formulas 1, 5 or 7.

[0115] The present invention also provides a method for preparing the above-mentioned [Yb(DPyPDA)2](DIEA), which comprises the following steps:

[0116] S1: Under ice-water bath conditions, dimethyl-o-phenanthroline is reacted with sulfuric acid in the presence of potassium bromate to obtain a ligand precursor shown in formula C;

[0117] S2: reacting the ligand precursor represented by formula C with the compound represented by formula D in the presence of a solvent to obtain the ligand represented by formula E;

[0118] S2: mixing and reacting a solution of the ligand represented by formula E, diisopropylethylamine and a solution of an ytterbium-containing compound to obtain [Yb(DPyPDA)2](DIEA);

[0119]

[0120] First, prepare the ligand precursor shown in formula C. In the present invention, preferably under ice-water bath conditions, dimethyl-o-phenanthroline is reacted with sulfuric acid in the presence of potassium bromate to obtain the ligand precursor shown in formula C. Wherein, sulfuric acid and potassium bromate are used as oxidants to oxidize dimethyl-o-phenanthroline to obtain the ligand precursor shown in formula C. In the present invention, the molar ratio of dimethyl-o-phenanthroline, sulfuric acid and potassium bromate is 1:(90-110):(1-1.2), preferably 1:100:1.1. The reaction temperature is 15-30°C, preferably 20-25°C; the reaction time is 20-36h, preferably 24-30h.

[0121] In some embodiments of the present invention, dimethyl-o-phenanthroline is preferably added to a 60wt% sulfuric acid solution under the condition of an ice-water bath, and after the solid is completely dissolved, potassium bromate solid is slowly added to the reaction system within 0.5h, and the resulting mixture is stirred at 15-30°C for 24h. The present invention preferably pours the reaction solution onto crushed ice after the reaction is completed, so that the product is precipitated for subsequent filtration on the one hand, and the concentrated sulfuric acid is diluted on the other hand to prevent the release of heat during the dilution process from causing the temperature to rise and cause side reactions. After the ice is completely melted, filter, wash the solid with water until the pH of the washing liquid is 7 to ensure that the concentrated sulfuric acid is completely removed, then wash with acetone and dichloromethane in sequence, and finally put the obtained solid into a vacuum oven for drying to obtain the ligand precursor shown in Formula C.

[0122] Then, the ligand precursor of formula C is preferably reacted with the compound of formula D in the presence of a solvent to obtain the ligand of formula E. In the present invention, the solvent is preferably selected from ethanol. The molar ratio of the ligand precursor of formula C to the compound of formula D is 1:1.05 to 1:1.15, preferably 1:1.1. The reaction temperature is 15 to 30°C, preferably 20 to 25°C; the reaction time is 4 to 10 hours, preferably 6 to 8 hours.

[0123] In some embodiments of the present invention, the ligand precursor represented by formula C is preferably dispersed in ethanol, the compound represented by formula D is dissolved or dispersed in ethanol, the two are mixed, and the mixture is stirred at 15-30° C. for 6 hours. In the present invention, after the reaction is completed, it is preferably filtered, and the filtered solid is washed with ethanol and dichloromethane in sequence, and then placed in a vacuum oven for drying to obtain the ligand represented by formula E.

[0124] Then, the solution of the ligand shown in formula E, diisopropylethylamine and the solution of the ytterbium-containing compound are mixed and reacted to obtain [Yb(DPyPDA)2](DIEA). In the present invention, the solvent in the solution of the ligand shown in formula E is selected from ethanol; the solvent in the solution of the ytterbium-containing compound is selected from ethanol; the ytterbium-containing compound is selected from any one or more of ytterbium chloride, ytterbium nitrate or ytterbium trifluoromethanesulfonate. Among them, the molar ratio of the ligand shown in formula E, diisopropylethylamine and the ytterbium-containing compound is (2.8-3.2):(5.6-6.4):1, preferably 3:6:1. The reaction temperature is 15-30°C, preferably 20-25°C; the time is 20-36h, preferably 24-30h.

[0125] In some embodiments of the present invention, the ligand shown in formula E is preferably dispersed in ethanol, and then diisopropylethylamine (DIEA) is added dropwise until all solids are dissolved. YbCl3 is dissolved in ethanol and added, and solids are observed to precipitate continuously, and the reaction is stirred at 15-30°C for 24 hours. After the reaction is completed, the preferred reaction of the present invention is filtered, the filter residue is washed with ethanol, and the obtained solid is placed in a vacuum oven to dry to obtain [Yb(DPyPDA)2](DIEA).

[0126] For example, the synthesis route of [Yb(DPyPDA)2](DIEA) is as follows (for the specific method, please refer to the above-mentioned related content):

[0127]

[0128] It can be seen that the preparation method of the above-mentioned [Yb(DPyPDA)2](DIEA) provided by the present invention is simple, convenient, easy to implement, and is conducive to large-scale production or industrial production.

[0129] After testing, [Yb(DPyPDA)2](DIEA) has excellent thermal stability and chemical stability, and a longer luminescence lifetime. Therefore, the present invention also provides a near-infrared ytterbium complex [Yb(DPyPDA)2](DIEA) as a luminescent material near-infrared OLEDs device and a preparation method thereof. The structure of the OLEDs device is as follows: Fig.15 As shown, it is composed of a substrate 1, an anode layer 2, a hole injection layer 3, a light-emitting layer 4, an electron transport layer / hole blocking layer 5, a cathode modification layer 6 and a metal cathode layer 7 connected in sequence.

[0130] In some embodiments of the present invention, the specific structure is as follows:

[0131] Substrate 1 is a glass substrate;

[0132] The anode layer 2 is an indium tin oxide (ITO) coating;

[0133] The hole injection layer 3 is made of poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonate) (PEDOT:PSS for short), and the molecular structure is as follows:

[0134]

[0135] The light-emitting layer 4 is an organic mixed material of an organic light-emitting material and an organic host material. The organic light-emitting material is the near-infrared ytterbium complex [Yb(DPyPDA)2](DIEA) provided in the present invention; the organic host material includes a hole-type organic host material, an electron-type organic host material and a bipolar organic host material:

[0136] Among them, the hole-type organic host materials include tris(4-carbazolyl-9-ylphenyl)amine (TcTa for short), poly(9-vinylcarbazole) (PVK for short), 1,3-dicarbazole-9-ylbenzene (mCP for short), and the molecular structures are as follows:

[0137]

[0138] Electronic organic host materials include (5-triphenyl-1,3-phenylene)bis(diphenylphosphine oxide) (abbreviated as POPH), diphenyl[4-(triphenylsilyl)phenyl]phosphine oxide (abbreviated as TSPO1), and bis[2-((oxy)diphenylphosphino)phenyl]ether (abbreviated as DPEPO). The molecular structures are as follows:

[0139]

[0140] The bipolar organic host materials include 2,6-bis[3-(9H-carbazole-9-yl)phenyl]pyridine (26DCzPPy for short) and [9-[3-(9H-carbazole-9-yl)phenyl]-9H-carbazole-3-yl]diphenylphosphine oxide (mCPPO1 for short). The molecular structures are as follows:

[0141]

[0142] The electron transport layer / hole blocking layer 5 uses 1,3,5-tris(6-(3-(pyridin-3-yl)phenyl)pyridin-2-yl)benzene (abbreviated as Tm3PyP26PyB), 1,3,5-tris(1-phenyl-1H-benzimidazol-2-yl)benzene (abbreviated as TPBi), and di[2-((oxy)diphenylphosphino)phenyl]ether (abbreviated as DPEPO), and the molecular structure is as follows:

[0143]

[0144] The cathode modification layer 6 is lithium fluoride (LiF);

[0145] The metal cathode 7 is metal aluminum (Al).

[0146] The preparation method of OLEDs device is as follows:

[0147] The ITO glass was scrubbed three times with washing liquid and water alternately, then rinsed with deionized water three times, and then placed in a clean beaker filled with deionized water for 15 minutes of ultrasonic treatment. After the ultrasonic treatment, it was rinsed with deionized water three times, and then the ITO glass was dried at 120 degrees Celsius. The dried ITO glass was placed in a UV-ozone treatment device for treatment and taken out after 20 minutes. The ITO glass was transferred to a glove box and the hole injection layer 3 and the light-emitting layer 4 were spin-coated in sequence. The ITO glass was then transferred to an organic evaporation chamber and heated to less than 5.0×10 -6 Under a vacuum degree of 100 Pa, an electron transport layer / hole blocking layer 5 of a certain thickness is evaporated at a certain rate. Finally, the unfinished substrate is transferred to a metal chamber, and a cathode modification layer 6 and a metal cathode layer 7 are continuously evaporated.

[0148] The parameters in the above preparation method can be adjusted within a reasonable range, and will not be described in detail here to avoid complexity.

[0149] After testing, it was found that the organic light-emitting diode (OLEDs) device prepared using the near-infrared ytterbium complex [Yb(DPyPDA)2](DIEA) as the luminescent material can emit the characteristic emission of ytterbium ions at 978nm in the near-infrared region, and has a high near-infrared irradiance under different operating voltages.

[0150] In summary, [Yb(DPyPDA)2](DIEA) has a high photoluminescence quantum efficiency (5.20%) while also having improved chemical and thermal stability. At the same time, due to its large π-conjugated system of ligands, it has good electrical conductivity, which is beneficial to improving the carrier transport capacity in near-infrared organic electroluminescent diodes, reducing the turn-on voltage of near-infrared OLEDs, and improving the near-infrared irradiance performance of the device.

[0151] In order to further illustrate the present invention, the following examples are provided for detailed description. The experimental raw materials used in the following examples of the present invention are all common commercially available products.

[0152] Example 1: Laboratory Synthesis of YbQ3

[0153] Weigh 0.208g of aldehyde hydroxyquinoline and mix it with 5mL of concentrated hydrochloric acid, heat and stir at 50°C, then add 280μL of acetophenone dropwise to the reaction system, observe that the reaction system changes from turbid to clear, stop heating, and continue stirring for 2h. The resulting liquid is poured onto crushed ice, filtered, and the filtered solid is washed with ether, air-dried naturally, and then dried in a 70°C oven to obtain a ligand precursor. Then, weigh 0.12g of the ligand precursor, disperse it with 4mL of ethanol, and stir at room temperature for 20min. Then, 138μL of phenylhydrazine is added dropwise, and the solid is observed to dissolve. The reaction solution is refluxed at 80°C for 8h, filtered, and the filtered solid is washed with ice ethanol, air-dried, and dried in a 70°C oven to obtain ligand Q. Subsequently, 0.12 g of ligand Q was weighed and dispersed in 2.5 mL of acetone, and an ethanol solution containing 0.032 g of ytterbium chloride was added dropwise, and refluxed at 55°C for 8 h. The filtered solid was washed with acetone and dried in an oven at 70°C to obtain the complex YbQ3.

[0154] Example 2: Pilot synthesis of YbQ3

[0155] Weigh 20.8g of aldehyde hydroxyquinoline, measure 500mL of concentrated hydrochloric acid and mix them in a 2L distillation flask, stir thoroughly at 50°C for 1h with a cantilever constant speed electric stirrer, then add 28mL of acetophenone dropwise to the reaction system, and observe that the reaction system changes from turbid to clear. After continuous stirring for 1h, stop heating and continue stirring for 12h. The resulting liquid is slowly poured onto crushed ice (note that the pouring process must be quite slow, the entire pouring process is completed in more than 2h, and crushed ice is added in time. The entire pouring process needs to be carried out in a fume hood with good ventilation), filter, wash the filtered solid with ether, air dry for three days, and then put it in a 70°C oven to dry for 24h to obtain a ligand precursor. Then, weigh 12g of the ligand precursor, disperse it with 400mL of ethanol in a 1L distillation flask, and stir it at room temperature for 1h. Then, add 14mL of phenylhydrazine dropwise, continue stirring for 2h, and observe that the solid dissolves. The reaction solution was refluxed at 80°C for 24h, filtered, and the filtered solid was washed with ice ethanol, air-dried for 3 days, and dried in a 70°C oven for 1 day to obtain ligand Q. Subsequently, 12g of ligand Q was weighed and dispersed in 250mL of acetone, and an ethanol solution containing 3.2g of ytterbium chloride was added dropwise (note that the ethanol solution was slowly added to the ytterbium chloride powder, and stirred continuously to keep the solution temperature below 30°C), and refluxed at 55°C for 24h, filtered, and the filtered solid was washed with acetone and dried in a 70°C oven for 1 day to obtain the complex YbQ3.

[0156] Example 3: Batch Synthesis of YbQ3

[0157] (Note that the equipment and pipelines required for this process route are all made of glass or thick polytetrafluoroethylene, and metal or alloy materials cannot be used).

[0158] Weigh 2kg of aldehyde hydroxyquinoline and 50L of concentrated hydrochloric acid and mix them in a 100L glass-lined reaction tank (note that concentrated hydrochloric acid is added slowly at a rate of 100mL / min, and stirred vigorously with a cantilever constant speed stirrer), set the speed of the cantilever constant speed electric stirrer to 50r / min, and stir thoroughly at 50°C for 2h (connect to the cooling tower and start circulating cooling water), then slowly add 3L of acetophenone to the reaction system at a rate of 50mL / min. After continuous stirring for 1h, the reaction system is observed to change from turbid to clear, stop heating, and continue stirring for 2 days. The obtained liquid is slowly poured onto crushed ice (note that the pouring process must be quite slow, the entire pouring process is completed in more than 12 hours, 5 kg of crushed ice is added every 2 hours, the entire pouring process needs to be carried out in a well-ventilated place, and the generated acid gas is collected and centrally treated to avoid pollution and harm to the environment), the mixed liquid is introduced into a rotary vacuum filter, filtered, and the filtered cake is washed with newly produced ether (note that it is necessary to check whether peroxide is generated in the ether used. The specific method is: add 2 to 3 drops of concentrated sulfuric acid, 1 mL of 2% potassium iodide solution and 1 to 2 drops of starch solution in a test tube, mix well, and then add 1 mL of the evaporated mixed solvent. The appearance of blue indicates the presence of peroxides. At this time, the ether solvent cannot be used again), air-dry for 3 days, and then bake and dry at 70°C for 3 days to obtain a ligand precursor. Then, weigh 1.2 kg of the ligand precursor, disperse it with 40 L of ethanol in a 100 L glass-lined reactor, and stir it at room temperature for 6 hours. Then, 1.4L phenylhydrazine was slowly added at a rate of 50mL / min, and stirring was continued for 2h, and solid dissolution was observed. The reaction solution was refluxed at 80°C for 3 days, and the mixed solution was introduced into a rotary vacuum filter, filtered, and the filter cake was washed with ice ethanol, air-dried for 3 days, and baked and dried at 70°C for 1 day to obtain ligand Q. Then, 1.2kg of ligand Q was weighed and dispersed in 25L acetone, and an ethanol solution containing 320g of ytterbium chloride was added at a rate of 50mL / min (note that the ethanol solution was slowly added to the ytterbium chloride powder, and stirred continuously to keep the solution temperature below 30°C), and refluxed at 55°C for 3 days, and the mixed solution was introduced into a rotary vacuum filter, filtered, and the filter cake was washed with acetone, and baked and dried at 70°C for 3 days to obtain the complex YbQ3.

[0159] Performance test of YbQ3

[0160] The YbQ3 obtained in Example 1 was tested for luminescence lifetime and thermal stability, as well as excitation spectrum, emission spectrum and photoluminescence quantum efficiency.

[0161] The test method is as follows:

[0162] The luminescence lifetime, excitation emission spectrum and photoluminescence quantum efficiency were collected on an FLS1000 Edinburgh steady-state transient fluorescence spectrometer, and the thermal stability test was collected on a thermogravimetric analyzer.

[0163] The test results are as follows Figures 3 to 6 As shown. Among them, Figure 3 is the luminescence lifetime diagram of YbQ3, Figure 3 It can be seen that its luminescence lifetime is as long as 94 microseconds. Figure 4 is the thermogravimetric curve of YbQ3. Figure 4 It can be seen that it can remain stable at 216°C and has good thermal stability. Figure 5 The excitation spectrum and emission spectrum of YbQ3 are shown in Figure 1. Figure 5 It can be seen that under the excitation of 466nm visible light, it can emit 978nm near-infrared light. Figure 6 Schematic diagram of the photoluminescence quantum efficiency of YbQ3. Under the excitation of 466nm light, the photoluminescence quantum efficiency is as high as 10.69%.

[0164] Application Example 1

[0165] Dissolve 10 mg of YbQ3 in 1 ml of dichloromethane and spray it on a clean non-woven fabric. After the dichloromethane evaporates naturally, YbQ3 adheres to the non-woven fabric. First, place the non-woven fabric in a well-lit location indoors, adjust the near-infrared zoom lens to the maximum aperture and optimal focal length, and then observe the signal recognition capabilities of different near-infrared cameras at close range. Finally, select a camera that can recognize the clear near-infrared light signal of YbQ3 for long-distance imaging testing. Subsequently, place the non-woven fabric under the light of the corridor, and ensure that the distance between the camera lens and the YbQ3 sample is greater than 50 meters. Then, further select the near-infrared lens, assemble the narrow-band filter, and assemble the polarizer in turn, so as to improve the detection limit and sensitivity of the infrared detection equipment and realize long-distance infrared imaging and detection under outdoor sunlight.

[0166] Example 4: Pilot-scale synthesis of [Yb(L)2](DIEA)

[0167] Set the temperature of the cooling circulation pump to 0°C and cool the reaction vessel distillation flask. Weigh 62.5g of dimethyl o-phenanthroline and add it to 700mL of 60% sulfuric acid solution. After the solid is completely dissolved, slowly add 55.1g of potassium bromate solid to the reaction system within 3h, and continue to stir the resulting mixture at room temperature for 3 days. After the reaction is completed, pour the reaction solution onto crushed ice (note that the pouring process must be quite slow, the entire pouring process is completed in more than 2h, and crushed ice is added in time. The entire pouring process needs to be carried out in a fume hood with good ventilation). After the ice cubes are completely melted, filter, wash the solid with water until the washing liquid is neutral, then wash with acetone and dichloromethane in turn, put it into a vacuum oven for drying to obtain a ligand precursor. Weigh 50 mmol of the ligand precursor and disperse it in 500mL of ethanol, weigh 50 mmol of the o-phenylenediamine derivative and dissolve it in 500mL of ethanol, mix the two, and stir the mixed solution at room temperature for 24h. After the reaction is completed, filter, wash the filtered solid with ethanol and dichloromethane in turn, and then put it into a vacuum oven to dry to obtain ligand L. Subsequently, weigh 30 mmol of ligand L and disperse it in 1.3L of ethanol, and then add about 15mL of diisopropylethylamine (DIEA) until the solid is completely dissolved. Dissolve 15 mmol of YbCl3 in 200mL of ethanol and add it. Solids are observed to precipitate continuously. Stir and react at room temperature for 2 days. Filter, wash the filter residue with ethanol, and dry the obtained solid in a vacuum oven to obtain the complex [Yb(L)2](DIEA);

[0168] Wherein, the structural formula of ligand L7 is shown in Formula E (wherein, R1=R3=CF3, R2=H):

[0169]

[0170] Performance test of [Yb(L7)2](DIEA)

[0171] The luminescence lifetime, thermal stability, chemical stability, excitation spectrum and emission spectrum of [Yb(L7)2](DIEA) obtained in Example 4 were tested.

[0172] The test method is as follows:

[0173] The luminescence lifetime, excitation emission spectrum and photoluminescence quantum efficiency were collected on an FLS1000 Edinburgh steady-state transient fluorescence spectrometer, and the thermal stability test was collected on a thermogravimetric analyzer.

[0174] Test results such as Figures 7-10 shown. Figure 7 The excitation and emission spectra of [Yb(L7)2](DIEA) show that under the excitation of 396nm light, it can emit 978nm near-infrared light; Figure 8This is the luminescence lifetime diagram of [Yb(L7)2](DIEA), which has a luminescence lifetime of up to 107 microseconds; Fig. 9 The thermogravimetric curve of [Yb(L7)2](DIEA) shows that it can remain stable at 322°C and has good thermal stability, which is conducive to its application in organic light-emitting diodes. Fig.10 This is a schematic diagram of the near-infrared luminescence stability of [Yb(L7)2](DIEA) in solid and solution states. It can be seen that after ten days of exposure to the atmosphere and sunlight, the material can maintain its original luminescence performance in both solid and solution states, and has good chemical stability, which is conducive to its application in organic light-emitting diodes.

[0175] Application Example 2: Preparation of near-infrared OLEDs based on [Yb(L7)2](DIEA)

[0176] First, the ITO glass with strip electrodes (wherein the substrate is glass and the anode layer is the ITO coating on the glass surface) is washed alternately with special glass washing liquid and tap water, then ultrasonicated with deionized water for 15 minutes and then placed in an oven for drying. The dried ITO glass is then transferred to a glove box through a pre-treated vacuum chamber. The hole injection layer 3PEDOT:PSS is spin-coated at 3000 rpm for 60 seconds and then annealed at 120°C for 20 minutes. Then, the solution of the light-emitting layer 4 (a mixed solution of 10 mg per mL [Yb(L7)2](DIEA) and 10 mg per mL of the hole-type host material TcTa in chlorobenzene) is spin-coated at 3000 rpm for 30 seconds and then annealed at 70°C for 30 minutes. The substrate is then transferred to an organic vapor deposition chamber and heated to less than 5.0×10 -6 Pa vacuum, evaporate 60 nm thick TPBi electron transport layer / hole blocking layer 5. Then, transfer the substrate to the metal evaporation chamber and deposit it under a vacuum of less than 8.0×10 -5 A 1-nanometer-thick LiF cathode modification layer 6 is evaporated under a vacuum degree of 100 Pa, and finally a 100-nanometer-thick Al metal cathode layer 7 is evaporated on the LiF layer through a special mask to prepare near-infrared OLEDs with a structure of ITO / PEDOT:PSS(32nm) / TcTa:[Yb(L7)2](DIEA)(20wt%) / TPBi(60nm) / LiF(1nm) / Al(100nm). The evaporation rate of TPBi in the electron transport layer / hole blocking layer 5 is controlled at 0.05 nanometers / second, the evaporation rate of LiF in the cathode modification layer 6 is controlled at 0.01 nanometers / second, and the evaporation rate of Al in the metal cathode layer 7 is controlled at 0.5 nanometers / second. The resulting device has a turn-on voltage of 5.8V and a maximum near-infrared irradiance of 86986 microwatts per square meter when driven by a DC voltage.

[0177] The electroluminescence spectrum of the near-infrared organic light-emitting diode prepared using the near-infrared ytterbium complex [Yb(L7)2](DIEA) as the luminescent material is shown in the figure below. Fig.11 As shown, it can be seen that the organic light-emitting diode device can emit the characteristic emission of ytterbium ions at 978nm in the near-infrared region; the voltage-current density-near-infrared irradiance characteristic curve of the near-infrared organic light-emitting diode prepared with [Yb(L7)2](DIEA) as the luminescent material is shown in Fig.12 shown.

[0178] Application Example 3: Preparation of near-infrared OLEDs based on [Yb(L5)2](DIEA)

[0179] First, the ITO glass with strip electrodes was washed alternately with special glass washing liquid and tap water, then ultrasonicated with deionized water for 15 minutes and then dried in an oven. Then, the dried ITO glass was transferred to the glove box through a pre-treated vacuum chamber. The hole injection layer 3PEDOT:PSS was spin-coated at 3000 rpm for 60 seconds and then annealed at 120°C for 20 minutes. Then, the solution of the light-emitting layer 4 (a mixed solution of 10 mg per mL [Yb(L5)2](DIEA) and 10 mg per mL of the hole-type host material TcTa in chlorobenzene) was spin-coated at 3000 rpm for 30 seconds and then annealed at 70°C for 30 minutes. The substrate was then transferred to an organic vapor deposition chamber and heated to less than 5.0×10 -6 Pa vacuum, evaporate 60 nm thick TPBi electron transport layer / hole blocking layer 5. Then, transfer the substrate to the metal evaporation chamber and deposit it under a vacuum of less than 8.0×10 -5 A 1-nanometer-thick LiF cathode modification layer 6 is evaporated under a vacuum degree of 100 Pa, and finally a 100-nanometer-thick Al metal cathode layer 7 is evaporated on the LiF layer through a special mask to prepare near-infrared OLEDs with a structure of ITO / PEDOT:PSS(32nm) / TcTa:[Yb(L5)2](DIEA)(20wt%) / TPBi(60nm) / LiF(1nm) / Al(100nm). The evaporation rate of TPBi in the electron transport layer / hole blocking layer 5 is controlled at 0.05 nanometers / second, the evaporation rate of LiF in the cathode modification layer 6 is controlled at 0.01 nanometers / second, and the evaporation rate of Al in the metal cathode layer 7 is controlled at 0.5 nanometers / second. The resulting device has a turn-on voltage of 5.5V and a maximum near-infrared irradiance of 77477 microwatts per square meter when driven by a DC voltage.

[0180] The voltage-current density-near infrared irradiance characteristic curve of the near-infrared organic light-emitting diode prepared with [Yb(L5)2](DIEA) as the luminescent material is shown in the figure. Fig.13 as shown.

[0181] Application Example 4: Preparation of near-infrared OLEDs based on [Yb(L1)2](DIEA)

[0182] First, the ITO glass with strip electrodes was washed alternately with special glass washing liquid and tap water, then ultrasonicated with deionized water for 15 minutes and then dried in an oven. Then, the dried ITO glass was transferred to the glove box through a pre-treated vacuum chamber. The hole injection layer 3PEDOT:PSS was spin-coated at 3000 rpm for 60 seconds and then annealed at 120°C for 20 minutes. Then, the solution of the light-emitting layer 4 (a mixed solution of 10 mg per mL [Yb(L1)2](DIEA) and 10 mg per mL of the hole-type host material TcTa in chlorobenzene) was spin-coated at 3000 rpm for 30 seconds and then annealed at 70°C for 30 minutes. The substrate was then transferred to an organic evaporation chamber and heated to less than 5.0×10 -6 Pa vacuum, evaporate 60 nm thick TPBi electron transport layer / hole blocking layer 5. Then, transfer the substrate to the metal evaporation chamber and deposit it under a vacuum of less than 8.0×10 -5 A 1-nanometer-thick LiF cathode modification layer 6 is evaporated under a vacuum degree of 100 Pa, and finally a 100-nanometer-thick Al metal cathode layer 7 is evaporated on the LiF layer through a special mask to prepare near-infrared OLEDs with a structure of ITO / PEDOT:PSS(32nm) / TcTa:[Yb(L1)2](DIEA)(20wt%) / TPBi(60nm) / LiF(1nm) / Al(100nm). The evaporation rate of TPBi in the electron transport layer / hole blocking layer 5 is controlled at 0.05 nanometers / second, the evaporation rate of LiF in the cathode modification layer 6 is controlled at 0.01 nanometers / second, and the evaporation rate of Al in the metal cathode layer 7 is controlled at 0.5 nanometers / second. The resulting device has a turn-on voltage of 4.9V and a maximum near-infrared irradiance of 37788 microwatts per square meter when driven by a DC voltage.

[0183] The voltage-current density-near-infrared irradiance characteristic curve of the near-infrared organic light-emitting diode prepared with [Yb(L1)2](DIEA) as the luminescent material is shown in the figure. Fig.14 shown.

[0184] It can be seen from Application Examples 2 to 4 that after the OLEDs devices are prepared using the different near-infrared ytterbium complexes provided by the present invention, the turn-on voltage of the OLEDs devices can be reduced and the near-infrared irradiance performance of the OLEDs devices can be improved.

[0185] In summary, using YbQ3 as the near-infrared luminescent material and selecting matching infrared imaging detection equipment and filters can achieve long-distance infrared imaging and detection in different scenarios. Using [Yb(DPyPDA)2](DIEA) as the near-infrared luminescent material to prepare near-infrared organic electroluminescent devices, after screening the device functional layer materials and optimizing the device structure, the turn-on voltage of near-infrared OLEDs based on near-infrared ytterbium complexes can be reduced, and the irradiance of near-infrared OLEDs can be improved.

[0186] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A near-infrared ytterbium complex, characterized in that: It has the structure shown in Formula I or Formula II: Wherein, R1 to R3 are independently selected from hydrogen, nitro, trihaloalkyl, substituted or unsubstituted C1 to C6 alkoxy, substituted or unsubstituted C1 to C6 alkyl; Or R1, R2 and the carbon atoms where they are located form an aromatic ring; R2, R3 and the carbon atoms where they are located form an aromatic ring.

2. The near-infrared ytterbium complex according to claim 1, characterized in that R1 to R3 are independently selected from hydrogen, nitro, trihalomethyl, substituted or unsubstituted C1 to C3 alkoxy, substituted or unsubstituted C1 to C4 alkyl; Or R1, R2 and the carbon atoms where they are located form a benzene ring; R2, R3 and the carbon atoms where they are located form a benzene ring.

3. The near-infrared ytterbium complex according to claim 1 or 2, characterized in that: The near-infrared ytterbium complex shown in Formula II is selected from any one of the following Formulas 1 to 7:

4. A method for preparing a near-infrared ytterbium complex as claimed in any one of claims 1 to 3, characterized in that: The preparation method of the near-infrared ytterbium complex shown in formula I comprises the following steps: S1: reacting a ligand precursor represented by formula A with phenylhydrazine in the presence of a solvent to obtain a ligand represented by formula B; S2: reacting a solution of the ligand represented by formula B with a solution of an ytterbium compound to obtain a near-infrared ytterbium complex represented by formula I; 5. The preparation method according to claim 4, characterized in that: The solvent is selected from ethanol; The solvent in the solution of the ligand represented by formula B is selected from acetone; The solvent in the solution containing the ytterbium compound is selected from ethanol; The ytterbium-containing compound is selected from any one or more of ytterbium chloride, ytterbium nitrate or ytterbium trifluoromethanesulfonate.

6. The preparation method according to claim 4 or 5, characterized in that: The molar ratio of the ligand precursor represented by formula A to phenylhydrazine is 1:3.2 to 1:3.8; the molar ratio of the ligand represented by formula B to the ytterbium-containing compound is 2.8:1 to 3.2:1; The reaction temperature in step S1 is 75-90°C and the reaction time is 6-10h; The reaction temperature in step S2 is 45-65°C and the reaction time is 6-10h; After the reaction in step S2 is completed, a purification step is also included.

7. A method for preparing a near-infrared ytterbium complex as claimed in any one of claims 1 to 3, characterized in that: The preparation method of the near-infrared ytterbium complex shown in formula ⅠⅠ comprises the following steps: S1: Under ice-water bath conditions, dimethyl-o-phenanthroline is reacted with sulfuric acid in the presence of potassium bromate to obtain a ligand precursor shown in formula C; S2: reacting the ligand precursor represented by formula C with the compound represented by formula D in the presence of a solvent to obtain the ligand represented by formula E; S2: mixing and reacting a solution of the ligand represented by formula E, diisopropylethylamine and a solution of the ytterbium compound to obtain a near-infrared ytterbium complex represented by formula ⅠⅠ; 8. The preparation method according to claim 7, characterized in that: The solvent is selected from ethanol; The solvent in the solution of the ligand represented by formula E is selected from ethanol; The solvent in the solution containing the ytterbium compound is selected from ethanol; The ytterbium-containing compound is selected from any one or more of ytterbium chloride, ytterbium nitrate or ytterbium trifluoromethanesulfonate.

9. The preparation method according to claim 8, characterized in that: The molar ratio of dimethyl-o-phenanthroline, sulfuric acid and potassium bromate is 1:(90-110):(1-1.2); The molar ratio of the ligand precursor represented by formula C to the compound represented by formula D is 1:1.05 to 1:1.15; The molar ratio of the ligand represented by formula E, diisopropylethylamine and the ytterbium-containing compound is (2.8-3.2):(5.6-6.4):1; The reaction temperature in steps S1 and S3 is independently 15 to 30° C. and the reaction time is 20 to 36 hours; The reaction temperature in step S2 is 15-30° C. and the reaction time is 4-10 h.

10. Use of a near-infrared ytterbium complex of formula I as described in any one of claims 1 to 3 or a near-infrared ytterbium complex of formula I prepared by the preparation method of any one of claims 4 to 6 in near-infrared imaging; or Use of the near-infrared ytterbium complex represented by formula ⅠⅠ as described in any one of claims 1 to 3 or the near-infrared ytterbium complex represented by formula ⅠⅠ prepared by the preparation method described in any one of claims 7 to 9 in the preparation of near-infrared organic light-emitting diodes.

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