Near-infrared ytterbium complex and preparation method and application thereof

Abstract

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

Description

Technical Field

[0001] This invention belongs to the field of metal complexes, specifically relating to a near-infrared ytterbium complex, its preparation method, and its application. Background Technology

[0002] Near-infrared complexes based on rare-earth ions such as Nd, Erbium, and Yb possess advantages such as long luminescence lifetime, narrow emission half-maximum width, and strong ligand designability, showing broad application prospects in fields such as bioimaging, fiber optic communication, infrared imaging, and organic light-emitting diodes (OLEDs). (The last sentence appears to be incomplete and possibly refers to a different topic.) 3+ Er 3+ In comparison, Yb 3+ The excited state energy level is relatively high, and it is less affected by the quenching of high-energy vibrational bonds; at the same time, Yb 3+ Ytterbium complexes have a single excited-state energy level, theoretically possessing fewer non-radiative transition pathways and higher internal quantum efficiency, thus exhibiting higher photoluminescence quantum efficiency. However, the pursuit of near-infrared ytterbium complexes with higher quantum efficiency, better chemical and thermal stability, and simple and inexpensive synthesis remains a focus for many researchers.

[0003] Currently, there are reports of using perfluorinated porphyrin ring sensitization and fully deuterated... Ligand-protected near-infrared ytterbium complexes have achieved a quantum efficiency of 63%. However, the synthesis of perfluorinated and perdeuterated complexes is extremely difficult and costly, and perfluorination significantly reduces the thermal and chemical stability of the complexes, making them unsuitable for large-scale synthesis and application. Michael Seitz reported a complex sensitized with a non-fluorinated, non-deuterated bipyridine derivative, which simplified the synthesis process, reduced costs, and improved the thermal and chemical stability of the complexes, achieving a quantum efficiency of 3%. However, this is currently the highest reported quantum efficiency for near-infrared luminescence of non-fluorinated, non-deuterated ligand-sensitized ytterbium ions, and still cannot meet the requirements of application scenarios. Further improving luminescence efficiency remains a key research topic. Summary of the Invention

[0004] In view of this, the purpose of this invention is to provide a near-infrared ytterbium complex, its preparation method, and its application. The near-infrared ytterbium complex exhibits excellent performance characteristics.

[0005] To achieve this objective, the present invention adopts the following technical solution:

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

[0007]

[0008] 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] Alternatively, R1 and R2, along with their respective carbon atoms, can form an aromatic ring; or R2 and R3, along with their respective carbon atoms, can form an aromatic ring.

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

[0011] Alternatively, R1 can form a benzene ring with R2 and the carbon atoms they contain; or R2 can form a benzene ring with R3 and the carbon atoms they contain.

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

[0013]

[0014]

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

[0016] S1: 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;

[0017] S2: React a solution of the ligand shown in Formula B with a solution containing a ytterbium compound to obtain the near-infrared ytterbium complex shown in 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 shown in 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 in step S2 is carried out at a temperature of 45–65°C for 6–10 hours.

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

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

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

[0030] S2: The ligand precursor shown in formula C is reacted with the compound shown in formula D in the presence of a solvent to obtain the ligand shown in formula E;

[0031] S2: Mix and react the solution of the ligand shown in Formula E, diisopropylethylamine, and a solution containing ytterbium to obtain the near-infrared ytterbium complex shown in 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 15–30°C and the reaction time is 20–36 h, respectively.

[0041] Preferably, the reaction in step S2 is carried out at a temperature of 15–30°C for 4–10 hours.

[0042] Fourthly, the present invention provides an application of the near-infrared ytterbium complex shown in Formula I above in near-infrared imaging.

[0043] Fifthly, the present invention provides an application of the near-infrared ytterbium complex shown in Formula ⅠⅠ above in the preparation of near-infrared organic light-emitting diodes.

[0044] Compared with the prior art, the beneficial effects of the present invention are as follows:

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

[0046] YbQ3, a non-fluorinated, non-deuterated near-infrared ytterbium complex, possesses an octahydroxyquinoline core structure exhibiting excellent luminescence properties and the ability to efficiently transfer energy to Yb ions. Furthermore, its oxygen-nitrogen chelate structure demonstrates good stability. Testing revealed that YbQ3 achieves a photoluminescence quantum efficiency of 10.69%, a luminescence lifetime of 94 microseconds, and good thermal stability. Excited with 466 nm visible light, it emits 978 nm near-infrared light. Therefore, applying YbQ3 to near-infrared imaging can achieve long-range infrared signal detection under visible light excitation.

[0047] The rigid conjugated plane of [Yb(DPyPDA)2](DIEA) reduces the quenching of near-infrared luminescence during non-radiative relaxation, thus improving its luminescence performance. Simultaneously, its dicarboxylic acid chelate structure significantly enhances its stability. Testing shows that [Yb(DPyPDA)2](DIEA) exhibits excellent thermal and chemical stability, as well as a longer luminescence lifetime. When used as a luminescent material, organic light-emitting diodes (OLEDs) can emit the characteristic emission of ytterbium ions at 978 nm in the near-infrared region, exhibiting high near-infrared irradiance under various operating voltages. Attached Figure Description

[0048] Figure 1 A schematic diagram of the synthesis route for YbQ3;

[0049] Figure 2 This is a schematic diagram of the synthetic route for [Yb(DPyPDA)2](DIEA);

[0050] Figure 3 The luminescence lifetime diagram of YbQ3;

[0051] Figure 4 Thermogravimetric curve of YbQ3;

[0052] Figure 5 The excitation and emission spectra of YbQ3 are shown below.

[0053] Figure 6 A schematic diagram of the photoluminescence quantum efficiency of YbQ3;

[0054] Figure 7 The excitation and emission spectra of [Yb(L7)2](DIEA) are shown below.

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

[0056] Figure 9 Thermogravimetric curve of [Yb(L7)2](DIEA);

[0057] Figure 10 This is a schematic diagram of the near-infrared luminescence stability of [Yb(L7)2](DIEA) in solid and solution states;

[0058] Figure 11 Electroluminescence spectra of near-infrared organic light-emitting diodes prepared using near-infrared ytterbium complex [Yb(L7)2] (DIEA) as the luminescent material;

[0059] Figure 12 Voltage-current density-near-infrared irradiance characteristic curves of near-infrared organic light-emitting diodes prepared using [Yb(L7)2](DIEA) as the luminescent material;

[0060] Figure 13 Voltage-current density-near-infrared irradiance characteristic curves of near-infrared organic light-emitting diodes prepared using [Yb(L5)2](DIEA) as the luminescent material;

[0061] Figure 14 Voltage-current density-near-infrared irradiance characteristic curves of near-infrared organic light-emitting diodes prepared using [Yb(L1)2](DIEA) as the luminescent material;

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

[0063] Wherein, 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 Implementation

[0064] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0065] Currently, a very small number of near-infrared ytterbium complexes with high photoluminescence quantum efficiency suffer from problems such as high synthesis cost, high synthesis difficulty, poor chemical and thermal stability, and limitations in batch synthesis and practical applications; while most near-infrared ytterbium complexes with simple synthesis processes, low synthesis cost, and good chemical and thermal stability have low quantum efficiency, below 3%.

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

[0067]

[0068] 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] Alternatively, R1 and R2, along with their respective carbon atoms, can form an aromatic ring; or R2 and R3, along with their respective carbon atoms, can form an aromatic ring.

[0070] In this invention, the near-infrared ytterbium complex represented by Formula I, abbreviated as YbQ3, is a non-fluorinated, non-deuterated near-infrared ytterbium complex. Its core octahydroxyquinoline structure exhibits excellent luminescence properties and can efficiently transfer energy to Yb ions. Simultaneously, its oxygen and nitrogen chelate structure demonstrates good stability. Testing shows that YbQ3 has a photoluminescence quantum efficiency as high as 10.69%, a luminescence lifetime of up to 94 microseconds, good thermal stability, and can emit 978nm near-infrared light when excited by 466nm visible light.

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

[0072] S1: 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;

[0073] S2: Reaction of a solution of the ligand shown in Formula B with a solution containing ytterbium yields 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 by the following method:

[0076] Aldehyde-hydroxyquinoline was mixed with concentrated hydrochloric acid and heated with stirring at 40–60°C, preferably 50°C. Acetophenone was then added dropwise to the reaction system. The system was observed to change from turbid to clear. Heating was stopped, and stirring continued for 2–4 hours. The resulting liquid was poured onto crushed ice, filtered, and the filtered solid was washed with diethyl ether, air-dried, and then dried at 60–80°C, preferably 70°C.

[0077] In some preferred embodiments of the present invention, after obtaining the ligand precursor of Formula A, it is uniformly dispersed in ethanol and stirred at room temperature for 10–40 min, preferably 20–30 min. Then, phenylhydrazine is added dropwise, and the solid is observed to dissolve. The reaction solution is refluxed at 75–90°C, preferably 80–85°C, for 6–10 h, preferably 8–9 h, to obtain the ligand of Formula B. In some more preferred embodiments of the present invention, after the reaction is completed, it is preferred to filter the solid, and the filtered solid (i.e., the ligand of Formula B) is preferably washed and dried. The washing is performed using ice-cold ethanol, followed by air drying, preferably at 60–80°C, more preferably 70°C.

[0078] After obtaining the ligand represented by Formula B, according to the present invention, a solution of the ligand represented by Formula B is reacted with a solution containing a ytterbium compound to obtain YbQ3. The solvent in the solution of the ligand represented by Formula B is preferably acetone, and the solvent in the solution of the ytterbium compound is preferably ethanol. The ytterbium 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 represented by Formula B to the ytterbium compound is 2.8:1 to 3.2:1, preferably 3:1, and the reaction is preferably carried out at 45–65°C for 6–10 h, more preferably at 45–55°C for 8–9 h.

[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 the mixture is 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 preferred embodiments of the present invention, a purification step is further included after the reaction of the ligand represented by Formula B with the ytterbium-containing compound. The present invention preferably employs a vacuum sublimation purification device to further purify the crude YbQ3 product. Specifically, the crude YbQ3 product is purified at a temperature less than 1 × 10⁻⁶ m³ / s. -4Under a vacuum of Pa, the crude product was kept at 130°C for 7 days to sublimate and remove small molecule impurities of organic ligands, thereby improving the purity of YbQ3.

[0081] For example, the synthetic route of YbQ3 is as follows (the specific method can be found in the relevant content above):

[0082]

[0083] It is evident that the preparation method of YbQ3 provided by the present invention is simple, convenient, and easy to implement, which is conducive to achieving large-scale production or industrial production.

[0084] It should be noted that the YbQ3 provided by this invention has a high photoluminescence quantum efficiency compared with other non-fluorinated and 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 well known, the recognition accuracy of near-infrared rare earth complex imaging detection signals mainly depends on two aspects: the luminescence effect of the near-infrared rare earth complex itself, and the signal acquisition and processing capabilities of the near-infrared detection equipment. The YbQ3 provided by this invention already possesses a high photoluminescence quantum efficiency. Therefore, this invention further optimizes the acquisition and processing capabilities 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 indoor location 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. Finally, select a camera that can recognize the clear near-infrared light signal of the YbQ3 for long-distance imaging testing.

[0088] (2) Selecting a suitable camera lens: First, place the YbQ3 under corridor lighting, ensuring the distance between the camera lens and the YbQ3 sample is greater than 50 meters. Then, replace the lens with a near-infrared lens to conduct near-infrared imaging and detection experiments. Experiments revealed that zoom lenses with multiple filters cause severe signal attenuation, and their large size makes them inconvenient to carry, which is not conducive to practical imaging applications. Therefore, this invention is equipped with a 100-meter fixed-focus lens with band matching. By optimizing the lens's light transmission range and equipping it with narrowband filters and polarizers, stray light interference on near-infrared imaging and signal detection is eliminated. Tests show that polarizers have little impact on signal acquisition, and filters can effectively filter out stray light from other bands. By customizing and equipping narrowband filters of a specific band (975±5nm), the detection limit and sensitivity of the infrared detection equipment are improved, enabling long-distance infrared imaging and detection under outdoor sunlight.

[0089] In this invention, the near-infrared ytterbium complex shown in Formula ⅠⅠ can be simply referred to as [Yb(DPyPDA)2](DIEA). It 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 chelate structure greatly increases its stability.

[0090] In some embodiments of the present invention, the near-infrared ytterbium complex has the 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] Alternatively, R1 can form a benzene ring with R2 and the carbon atoms they contain; or R2 can form a benzene ring with R3 and the carbon atoms they contain.

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

[0093] Alternatively, R1 and R2, along with the carbon atom they are on, can form a benzene ring.

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

[0095]

[0096]

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

[0098] The infrared and mass spectrometry data for the ligands 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] The infrared and mass spectrometry data of 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 includes the following steps:

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

[0117] S2: The ligand precursor shown in formula C is reacted with the compound shown in formula D in the presence of a solvent to obtain the ligand shown in formula E;

[0118] S2: Mix and react the solution of the ligand shown in Formula E, diisopropylethylamine, and a solution containing ytterbium to obtain [Yb(DPyPDA)2](DIEA);

[0119]

[0120] First, the ligand precursor shown in Formula C is prepared. In this invention, dimethyl-o-phenanthroline is preferably reacted with sulfuric acid in the presence of potassium bromate under ice-water bath conditions to obtain the ligand precursor shown in Formula C. Sulfuric acid and potassium bromate act together as oxidants, oxidizing dimethyl-o-phenanthroline to obtain the ligand precursor shown in Formula C. In this 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 20-36 h, preferably 24-30 h.

[0121] In some embodiments of the present invention, it is preferred that dimethylo-phenanthroline be added to a 60 wt% sulfuric acid solution under ice-water bath conditions. After the solid has completely dissolved, potassium bromate solid is slowly added to the reaction system over 0.5 h. The resulting mixture is stirred at 15–30 °C for 24 h. Preferably, after the reaction is complete, the reaction solution is poured onto crushed ice. This allows the product to precipitate for subsequent filtration and dilutes the concentrated sulfuric acid, preventing the release of heat during dilution that could cause a temperature rise and side reactions. After the ice has completely melted, the mixture is filtered, and the solid is washed with water until the pH of the washing solution reaches 7 to ensure complete removal of concentrated sulfuric acid. Subsequently, the solid is washed sequentially with acetone and dichloromethane. Finally, the obtained solid is dried in a vacuum oven to obtain the ligand precursor shown in Formula C.

[0122] Then, preferably, the ligand precursor shown in Formula C is reacted with the compound shown in Formula D in the presence of a solvent to obtain the ligand shown in Formula E. In this invention, the solvent is preferably selected from ethanol. The molar ratio of the ligand precursor shown in Formula C to the compound shown in 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 h, preferably 6 to 8 h.

[0123] In some embodiments of the present invention, it is preferable to disperse the ligand precursor of Formula C in ethanol, dissolve or disperse the compound of Formula D in ethanol, mix the two, and stir the mixture at 15–30°C for 6 hours. Preferably, after the reaction is complete, the mixture is filtered, and the filtered solid is washed sequentially with ethanol and dichloromethane, and then dried in a vacuum oven to obtain the ligand of Formula E.

[0124] Then, the solution of the ligand represented by Formula E, diisopropylethylamine, and the solution of the ytterbium-containing compound are mixed and reacted to obtain [Yb(DPyPDA)2](DIEA). In this invention, the solvent in the solution of the ligand represented by Formula E is selected from ethanol; the solvent in the solution of the ytterbium-containing compound is selected from ethanol; and the ytterbium-containing compound is selected from any one or more of ytterbium chloride, ytterbium nitrate, or ytterbium trifluoromethanesulfonate. 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, preferably 3:6:1. The reaction temperature is 15–30°C, preferably 20–25°C; and the reaction time is 20–36 h, preferably 24–30 h.

[0125] In some embodiments of the present invention, the ligand represented by formula E is preferably dispersed in ethanol, followed by the dropwise addition of diisopropylethylamine (DIEA) until the solid is completely dissolved. YbCl3 is dissolved in ethanol and added, and solid is observed to continuously precipitate. The reaction is stirred at 15–30°C for 24 h. Preferably, after the reaction is complete, the mixture is filtered, the filter residue is washed with ethanol, and the resulting solid is dried in a vacuum oven to obtain [Yb(DPyPDA)2](DIEA).

[0126] For example, the synthetic route of [Yb(DPyPDA)2](DIEA) is as follows (the specific method can be found in the relevant content above):

[0127]

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

[0129] Testing revealed that [Yb(DPyPDA)2](DIEA) exhibits excellent thermal and chemical stability, as well as a longer luminescent lifetime. Therefore, this invention also provides near-infrared OLEDs using the near-infrared ytterbium complex [Yb(DPyPDA)2](DIEA) as the luminescent material, and a method for its fabrication. The structure of the OLEDs is as follows: Figure 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 configuration is as follows:

[0131] Substrate 1 is a glass substrate;

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

[0133] Hole injection layer 3 is made of poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonate) (PEDOT:PSS), with the following molecular structure:

[0134]

[0135] The light-emitting layer 4 is an organic hybrid material composed 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 this invention; the organic host material includes hole-type organic host materials, electron-type organic host materials, and bipolar organic host materials.

[0136] Among them, the hole-type organic host materials include tris(4-carbazolyl-9-ylphenyl)amine (TcTa), poly(9-vinylcarbazole) (PVK), and 1,3-dicarbazolyl-9-ylphenyl (mCP), with the following molecular structures:

[0137]

[0138] Electronic organic host materials include (5-triphenyl-1,3-phenylene)bis(diphenylphosphine oxide) (POPH), diphenyl[4-(triphenylsilyl)phenyl]oxyphosphine (TSPO1), and di[2-((oxo)diphenylphosphino)phenyl] ether (DPEPO), with the following molecular structures:

[0139]

[0140] Bipolar organic host materials include 2,6-bis[3-(9H-carbazole-9-yl)phenyl]pyridine (abbreviated as 26DCzPPy) and [9-[3-(9H-carbazole-9-yl)phenyl]-9H-carbazole-3-yl]diphenylphosphine oxide (abbreviated as mCPPO1), with the following molecular structures:

[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-((oxo)diphenylphosphino)phenyl] ether (abbreviated as DPEPO), with the following molecular structures:

[0143]

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

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

[0146] The fabrication methods for OLED devices are as follows:

[0147] The ITO glass was washed three times alternately with cleaning solution and water, then rinsed three times with deionized water. It was then sonicated in a clean beaker containing deionized water for 15 minutes, followed by rinsing three more times with deionized water. The ITO glass was then dried at 120°C. After drying, the ITO glass was placed in a UV-ozone treatment device for 20 minutes, then removed. The ITO glass was transferred to a glove box, and hole injection layer 3 and luminescent layer 4 were spin-coated sequentially. The ITO glass was then transferred to an organic evaporation chamber and treated at temperatures less than 5.0 × 10⁻⁶. -6Under a vacuum of Pa, an electron transport layer / hole blocking layer 5 of a certain thickness is deposited at a certain rate. Finally, the unfinished substrate is transferred to a metal chamber, where a cathode modification layer 6 and a metal cathode layer 7 are deposited.

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

[0149] Tests have shown that organic light-emitting diodes (OLEDs) prepared using the near-infrared ytterbium complex [Yb(DPyPDA)2](DIEA) as the luminescent material can emit the characteristic emission of ytterbium ions at 978 nm in the near-infrared region, and have high near-infrared irradiance under different operating voltages.

[0150] In summary, [Yb(DPyPDA)2](DIEA) exhibits high photoluminescence quantum efficiency (5.20%), while also improving chemical and thermal stability. Furthermore, due to its large π-conjugated ligand system, it possesses excellent conductivity, which is beneficial for enhancing carrier transport capabilities in near-infrared organic light-emitting diodes, reducing the turn-on voltage of near-infrared OLEDs, and improving the near-infrared irradiance performance of the devices.

[0151] To further illustrate the present invention, the following embodiments provide a detailed description. The experimental materials used in the following embodiments of the present invention are all commercially available products.

[0152] Example 1: Laboratory Synthesis of YbQ3

[0153] 0.208 g of aldehyde-hydroxyquinoline was weighed and mixed with 5 mL of concentrated hydrochloric acid. The mixture was heated and stirred at 50 °C. Then, 280 μL of acetophenone was added dropwise to the reaction system. The system was observed to change from turbid to clear. Heating was stopped, and stirring was continued for 2 h. The resulting liquid was poured onto crushed ice, filtered, and the filtered solid was washed with diethyl ether, air-dried, and then dried in a 70 °C oven to obtain the ligand precursor. Next, 0.12 g of the ligand precursor was weighed and dispersed in 4 mL of ethanol, and stirred at room temperature for 20 min. Then, 138 μL of phenylhydrazine was added dropwise, and the solid was observed to dissolve. The reaction solution was refluxed at 80 °C for 8 h, filtered, and the filtered solid was washed with ice-cold ethanol, air-dried, and then 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. An ethanol solution containing 0.032 g of ytterbium chloride was added dropwise, and the mixture was refluxed at 55 °C for 8 h. After filtration, the filtered solid was washed with acetone and dried in an oven at 70 °C to obtain the complex YbQ3.

[0154] Example 2: Pilot-scale synthesis of YbQ3

[0155] Weigh 20.8 g of aldehyde-hydroxyquinoline and mix it with 500 mL of concentrated hydrochloric acid in a 2 L distillation flask. Stir thoroughly at 50 °C for 1 h using a cantilevered constant-speed electric stirrer. Then, add 28 mL of acetophenone dropwise to the reaction system. Observe the reaction system change from turbid to clear. Continue stirring for 1 h, then stop heating and continue stirring for 12 h. Slowly pour the resulting liquid onto crushed ice (note that the pouring process must be very slow, the entire pouring process should be completed over 2 h, and crushed ice should be added as needed. The entire pouring process should be carried out in a well-ventilated fume hood). Filter, wash the filtered solid with diethyl ether, air dry for three days, and then dry in a 70 °C oven for 24 h to obtain the ligand precursor. Then, weigh 12 g of the ligand precursor and disperse it in 400 mL of ethanol in a 1 L distillation flask, stirring at room temperature for 1 h. Then, add 14 mL of phenylhydrazine dropwise and stir continuously for 2 h. Observe the solid dissolve. The reaction solution was refluxed at 80°C for 24 hours, filtered, and the filtered solid was washed with ice-cold ethanol, air-dried for 3 days, and then dried in a 70°C oven for 1 day to obtain ligand Q. Subsequently, 12 g of ligand Q was weighed and dispersed in 250 mL of acetone, and an ethanol solution containing 3.2 g of ytterbium chloride was added dropwise (note that the ethanol solution should be added slowly to the ytterbium chloride powder while stirring continuously to keep the solution temperature below 30°C). The mixture was refluxed at 55°C for 24 hours, filtered, and the filtered solid was washed with acetone and dried in a 70°C oven for 1 day to obtain complex YbQ3.

[0156] Example 3: Batch synthesis of YbQ3

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

[0158] Weigh 2 kg of aldehyde-hydroxyquinoline and mix it with 50 L of concentrated hydrochloric acid in a 100 L glass-lined reaction vessel (note that the concentrated hydrochloric acid should be added slowly at a rate of 100 mL / min and vigorously stirred with a cantilevered constant-speed stirrer). Set the speed of the cantilevered constant-speed electric stirrer to 50 r / min and stir thoroughly at 50 °C for 2 h (connect to a cooling tower and turn on the circulating cooling water). Then, slowly add 3 L of acetophenone to the reaction system at a rate of 50 mL / min and continue stirring for 1 h. After observing that the reaction system changes from turbid to clear, stop heating and continue stirring for 2 days. The resulting liquid was slowly poured onto crushed ice (note that the pouring process must be extremely slow, taking more than 12 hours to complete, with 5 kg of crushed ice added every 2 hours; the entire pouring process must be carried out in a well-ventilated area, and the generated acid gas must be collected and centrally treated to prevent environmental pollution and harm). The mixture was then introduced into a rotary vacuum filter for filtration. The filter cake was washed with freshly produced diethyl ether (note that it is necessary to test whether peroxides are generated in the diethyl ether used; the specific method is as follows: add 2-3 drops of concentrated sulfuric acid, 1 mL of 2% potassium iodide solution, and 1-2 drops of starch solution to a test tube, mix well, and then add 1 mL of distilled mixed solvent; a blue color indicates the presence of peroxides, and the diethyl ether solvent should not be used in this case). The mixture was air-dried naturally for 3 days, and then baked at 70℃ for 3 days to obtain the ligand precursor. Then, 1.2 kg of the ligand precursor was weighed and dispersed in 40 L of ethanol in a 100 L glass-lined reactor, and stirred at room temperature for 6 hours. Subsequently, 1.4 L of phenylhydrazine was slowly added at a rate of 50 mL / min, and the mixture was stirred continuously for 2 h, during which solid dissolution was observed. The reaction solution was refluxed at 80 °C for 3 days, and the mixture was introduced into a rotary vacuum filter for filtration. The filtered cake was washed with ice-cold ethanol, air-dried for 3 days, and then baked at 70 °C for 1 day to obtain ligand Q. Subsequently, 1.2 kg of ligand Q was weighed and dispersed in 25 L of acetone. An ethanol solution containing 320 g of ytterbium chloride was added at a rate of 50 mL / min (note that the ethanol solution was added to the ytterbium chloride powder slowly while stirring continuously to keep the solution temperature below 30 °C), and the mixture was refluxed at 55 °C for 3 days. The mixture was then introduced into a rotary vacuum filter for filtration, and the filtered cake was washed with acetone and baked at 70 °C for 3 days to obtain complex YbQ3.

[0159] YbQ3 Performance Testing

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

[0161] The testing method is as follows:

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

[0163] Test results are as follows Figures 3-6 As shown. Among them, Figure 3 The luminescence lifetime diagram of YbQ3 is shown below. Figure 3 It is known that its luminescence lifetime is as long as 94 microseconds. Figure 4 The thermogravimetric curve of YbQ3 is shown below. Figure 4 It can be seen that it remains stable at 216℃, indicating good thermal stability. Figure 5 The excitation and emission spectra of YbQ3 are shown below. Figure 5 It can be seen that when excited by 466nm visible light, it can emit 978nm near-infrared light. Figure 6 This is a schematic diagram of the photoluminescence quantum efficiency of YbQ3, which reaches 10.69% under 466nm light excitation.

[0164] Application Example 1

[0165] 10 mg of YbQ3 was dissolved in 1 mL of dichloromethane and sprayed onto a clean nonwoven fabric. After the dichloromethane evaporated naturally, the YbQ3 adhered to the fabric. First, the nonwoven fabric was placed in a well-lit indoor location. The near-infrared zoom lens was adjusted to its maximum aperture and optimal focal length. Then, the signal recognition capabilities of different near-infrared cameras were observed at close range. Finally, the camera capable of clearly recognizing the near-infrared light signal of YbQ3 was selected for long-distance imaging testing. Subsequently, the nonwoven fabric was placed under corridor lighting, ensuring a distance greater than 50 meters between the camera lens and the YbQ3 sample. Further selection of the near-infrared lens, assembly of the narrowband filter, and assembly of the polarizer were then performed sequentially to improve the detection limit and sensitivity of the infrared detection equipment, enabling long-distance infrared imaging and detection under outdoor sunlight.

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

[0167] The temperature of the cooling circulation pump was set to 0℃ to cool the reaction vessel, a distillation flask. 62.5 g of dimethyl-o-phenanthroline was weighed and added to 700 mL of 60% sulfuric acid solution. After the solid was completely dissolved, 55.1 g of potassium bromate solid was slowly added to the reaction system over 3 hours. The resulting mixture was stirred at room temperature for 3 days. After the reaction was complete, the reaction solution was poured onto crushed ice (note that the pouring process must be very slow, the entire process should be completed over 2 hours, and crushed ice should be added as needed; the entire pouring process should be carried out in a well-ventilated fume hood). After the ice had completely melted, the mixture was filtered, and the solid was washed with water until the washing liquid was neutral. Then, it was washed successively with acetone and dichloromethane, and dried in a vacuum oven to obtain the ligand precursor. 50 mmol of the ligand precursor was weighed and dispersed in 500 mL of ethanol, and 50 mmol of the o-phenylenediamine derivative was weighed and dissolved in 500 mL of ethanol. The two were mixed, and the mixture was stirred at room temperature for 24 hours. After the reaction was complete, the mixture was filtered, and the filtered solid was washed successively with ethanol and dichloromethane. The solid was then dried in a vacuum oven to obtain ligand L. Subsequently, 30 mmol of ligand L was weighed and dispersed in 1.3 L of ethanol, followed by the addition of approximately 15 mL of diisopropylethylamine (DIEA) until the solid was completely dissolved. 15 mmol of YbCl3 was dissolved in 200 mL of ethanol and added to the solution. Solid precipitation was observed, and the reaction was stirred at room temperature for 2 days. The mixture was then filtered, and the residue was washed with ethanol. The resulting solid was dried in a vacuum oven to obtain the complex [Yb(L)2](DIEA).

[0168] The structural formula of ligand L7 is shown in formula E (where R1 = R3 = CF3, R2 = H):

[0169]

[0170] Performance testing 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 testing method is as follows:

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

[0174] Test results are as follows Figures 7-10 As shown. Figure 7 The excitation and emission spectra of [Yb(L7)2](DIEA) show that it can emit near-infrared light of 978nm when excited by 396nm light. Figure 8The luminescence lifetime diagram of [Yb(L7)2](DIEA) shows that its luminescence lifetime is as long as 107 microseconds; Figure 9 The thermogravimetric curve of [Yb(L7)2](DIEA) shows that it remains stable at 322℃, which is good thermal stability and is beneficial for its application in organic light-emitting diodes. Figure 10 The diagram shows 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 properties in both solid and solution states, exhibiting excellent chemical stability, which is beneficial for its application in organic light-emitting diodes.

[0175] Application Example 2: Fabrication of Near-Infrared OLEDs Based on [Yb(L7)2](DIEA)

[0176] First, the ITO glass with strip electrodes (where the substrate is glass and the anode layer is an ITO coating on the glass surface) was cleaned alternately with a special glass cleaning solution and tap water, then ultrasonicated with deionized water for 15 minutes and dried in an oven. The dried ITO glass was then transferred to a glove box via a pretreatment vacuum chamber. The hole injection layer 3, PEDOT:PSS, was spin-coated at 3000 rpm for 60 seconds and then annealed at 120°C for 20 minutes. Next, the solution of the luminescent layer 4 (a chlorobenzene mixture of 10 mg / mL [Yb(L7)2](DIEA) and 10 mg / mL TcTa, the hole-type host material) was spin-coated at 3000 rpm for 30 seconds and then annealed at 70°C for 30 minutes. Finally, the substrate was transferred to an organic evaporation chamber and annealed at a temperature less than 5.0 × 10⁻⁶ mm. -6 A 60 nm thick TPBi electron transport layer / hole blocking layer was deposited under a vacuum of 5 Pa. The substrate was then transferred to a metal evaporation chamber at a vacuum level of less than 8.0 × 10⁻⁶ Pa. -5 A 1 nm thick LiF cathode modification layer 6 was deposited under a vacuum of 6 Pa. Finally, a 100 nm thick Al metal cathode layer 7 was deposited on the LiF layer using a specially designed mask, to prepare near-infrared OLEDs with the structure ITO / PEDOT:PSS (32 nm) / TcTa:[Yb(L7)2](DIEA) (20 wt%) / TPBi (60 nm) / LiF (1 nm) / Al (100 nm). The evaporation rate of TPBi in the electron transport layer / hole blocking layer 5 was controlled at 0.05 nm / s, the evaporation rate of LiF in the cathode modification layer 6 was controlled at 0.01 nm / s, and the evaporation rate of Al in the metal cathode layer 7 was controlled at 0.5 nm / s. The resulting device, driven by DC voltage, had a turn-on voltage of 5.8 V and a maximum near-infrared irradiance of 86,986 microwatts per square meter.

[0177] 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 is shown in the figure below. Figure 11 As shown, organic light-emitting diode devices can emit the characteristic emission of ytterbium ions at 978 nm in the near-infrared region; the voltage-current density-near-infrared irradiance characteristic curves of near-infrared organic light-emitting diodes prepared using [Yb(L7)2](DIEA) as the luminescent material are shown in the figure. Figure 12 As shown.

[0178] Application Example 3: Fabrication of Near-Infrared OLEDs Based on [Yb(L5)2](DIEA)

[0179] First, the ITO glass with strip electrodes was alternately cleaned with a special glass cleaning solution and tap water, then ultrasonicated with deionized water for 15 minutes and dried in an oven. The dried ITO glass was then transferred to a glove box via a pretreatment vacuum chamber. The hole-injection layer 3, PEDOT:PSS, was spin-coated at 3000 rpm for 60 seconds, and then annealed at 120°C for 20 minutes. Next, the solution of the light-emitting layer 4 (a chlorobenzene mixture of 10 mg / mL [Yb(L5)2](DIEA) and 10 mg / mL TcTa, the hole-type host material) was spin-coated at 3000 rpm for 30 seconds, and then annealed at 70°C for 30 minutes. Finally, the substrate was transferred to an organic evaporation chamber and annealed at a temperature less than 5.0 × 10⁻⁶ mm. -6 A 60 nm thick TPBi electron transport layer / hole blocking layer was deposited under a vacuum of 5 Pa. The substrate was then transferred to a metal evaporation chamber at a vacuum level of less than 8.0 × 10⁻⁶ Pa. -5 A 1 nm thick LiF cathode modification layer 6 was deposited under a vacuum of 6 Pa. Finally, a 100 nm thick Al metal cathode layer 7 was deposited on the LiF layer using a specially designed mask, to prepare near-infrared OLEDs with the structure ITO / PEDOT:PSS (32 nm) / TcTa:[Yb(L5)2](DIEA) (20 wt%) / TPBi (60 nm) / LiF (1 nm) / Al (100 nm). The evaporation rate of TPBi in the electron transport layer / hole blocking layer 5 was controlled at 0.05 nm / s, the evaporation rate of LiF in the cathode modification layer 6 was controlled at 0.01 nm / s, and the evaporation rate of Al in the metal cathode layer 7 was controlled at 0.5 nm / s. The resulting device, driven by DC voltage, had a turn-on voltage of 5.5 V and a maximum near-infrared irradiance of 77477 μW / m².

[0180] The voltage-current density-near-infrared irradiance characteristic curves of near-infrared organic light-emitting diodes prepared using [Yb(L5)2](DIEA) as the luminescent material are shown in the figure below. Figure 13 As shown.

[0181] Application Example 4: Fabrication of Near-Infrared OLEDs Based on [Yb(L1)2](DIEA)

[0182] First, the ITO glass with strip electrodes was alternately cleaned with a special glass cleaning solution and tap water, then ultrasonicated with deionized water for 15 minutes and dried in an oven. The dried ITO glass was then transferred to a glove box via a pretreatment vacuum chamber. The hole-injection layer 3, PEDOT:PSS, was spin-coated at 3000 rpm for 60 seconds, and then annealed at 120°C for 20 minutes. Next, the solution of the luminescent layer 4 (a chlorobenzene mixture of 10 mg / mL [Yb(L1)2](DIEA) and 10 mg / mL TcTa, the hole-type host material) was spin-coated at 3000 rpm for 30 seconds, and then annealed at 70°C for 30 minutes. Finally, the substrate was transferred to an organic evaporation chamber and annealed at a temperature less than 5.0 × 10⁻⁶ mm. -6 A 60 nm thick TPBi electron transport layer / hole blocking layer was deposited under a vacuum of 5 Pa. The substrate was then transferred to a metal evaporation chamber at a vacuum level of less than 8.0 × 10⁻⁶ Pa. -5 A 1 nm thick LiF cathode modification layer 6 was deposited under a vacuum of 6 Pa. Finally, a 100 nm thick Al metal cathode layer 7 was deposited on the LiF layer using a specially designed mask, fabricating near-infrared OLEDs with the structure ITO / PEDOT:PSS (32 nm) / TcTa:[Yb(L1)2](DIEA) (20 wt%) / TPBi (60 nm) / LiF (1 nm) / Al (100 nm). The evaporation rate of TPBi in the electron transport layer / hole blocking layer 5 was controlled at 0.05 nm / s, the evaporation rate of LiF in the cathode modification layer 6 was controlled at 0.01 nm / s, and the evaporation rate of Al in the metal cathode layer 7 was controlled at 0.5 nm / s. The resulting device, driven by DC voltage, had a turn-on voltage of 4.9 V and a maximum near-infrared irradiance of 37788 microwatts per square meter.

[0183] The voltage-current density-near-infrared irradiance characteristic curves of near-infrared organic light-emitting diodes prepared using [Yb(L1)2](DIEA) as the luminescent material are shown in the figure below. Figure 14 As shown.

[0184] As can be seen from Application Examples 2 to 4, the different near-infrared ytterbium complexes provided by the present invention can all reduce the turn-on voltage of OLED devices and improve the near-infrared irradiance performance of OLED devices after they are prepared.

[0185] In summary, by using YbQ3 as the near-infrared emitting material and selecting matching infrared imaging and detection equipment and filters, long-distance infrared imaging and detection can be achieved in different scenarios. Near-infrared organic light-emitting devices (OLEDs) can be fabricated using [Yb(DPyPDA)2](DIEA) as the near-infrared emitting material. Through screening of the functional layer materials and optimization of 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 make or use the invention. Various modifications to these embodiments will be readily 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 invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A near-infrared ytterbium complex, characterized in that, A near-infrared ytterbium complex of formula I: Formula I.

2. A near-infrared ytterbium complex, characterized in that, is selected from any one of formula 1 to formula 7: Formula 1 ; Formula 2; Formula 3; Formula 4; Formula 5; Formula 6; Formula 7.

3. A process for the preparation of a near infrared ytterbium complex as claimed in claim 1, characterized in that, The preparation method of the near-infrared ytterbium complex of formula I comprises the following steps: S1: reacting a ligand precursor of formula A with phenylhydrazine in the presence of a solvent to obtain a ligand of formula B; S2: reacting a solution of the ligand of formula B with a solution of a ytterbium-containing compound to obtain the near-infrared ytterbium complex of formula I; Formula A; Formula B; Formula I.

4. The production method according to claim 3, characterized by, The solvent is selected from ethanol; The solvent in the solution of the ligand of formula B is selected from acetone; 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 triflate.

5. The production method according to claim 3 or 4, characterized by, The molar ratio of the ligand precursor of formula A to phenylhydrazine is 1:3.2 to 1:3.8, and the molar ratio of the ligand of formula B to the ytterbium-containing compound is 2.8:1 to 3.2:1; The temperature of the reaction in step S1 is 75 to 90°C, and the time is 6 to 10 hours; The temperature of the reaction in step S2 is 45 to 65°C, and the time is 6 to 10 hours; After the reaction in step S2 is completed, a purification step is further included.

6. A process for the preparation of a near infrared ytterbium complex as claimed in claim 2, characterized in that, The preparation method of the near-infrared ytterbium complex of formula II comprises the following steps: S1: reacting dimethyl phenanthroline with sulfuric acid in the presence of potassium bromate under ice water bath conditions to obtain a ligand precursor of formula C; S2: reacting the ligand precursor of formula C with a compound of formula D in the presence of a solvent to obtain a ligand of formula E; S2: mixing and reacting a solution of the ligand of formula E, diisopropylethylamine and a solution of a ytterbium-containing compound to obtain the near-infrared ytterbium complex of any one of formula 1 to 7; wherein R1 is selected from H, methoxy, nitro, trifluoromethyl or tert-butyl; R2 is selected from H; R3 is selected from H or trifluoromethyl; or R1 and R2 form a benzene ring; Formula C; Formula D; Formula E.

7. The production method according to claim 6, wherein The solvent is selected from ethanol; The solvent in the solution of the ligand of 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 triflate.

8. The production method according to claim 7, characterized by, The molar ratio of dimethyl phenanthroline, sulfuric acid and potassium bromate is 1:(90 to 110):(1 to 1.2); The molar ratio of the ligand precursor of formula C to the compound of formula D is 1:1.05 to 1:1.15; The molar ratio of the ligand of formula E, diisopropylethylamine and the ytterbium-containing compound is (2.8 to 3.2):(5.6 to 6.4):1; The temperature of the reaction in steps S1 and S3 is independently 15 to 30°C, and the time is 20 to 36 hours; The temperature of the reaction in step S2 is 15 to 30°C, and the time is 4 to 10 hours.

9. Use of the near-infrared ytterbium complex of formula I according to claim 1 or prepared by the preparation method according to any one of claims 3 to 5 in the preparation of a near-infrared imaging reagent; or Use of the near-infrared ytterbium complex of formula II as defined in claim 2 or the near-infrared ytterbium complex of formula II prepared according to the method of any one of claims 6 to 8 in the manufacture of a near-infrared organic light emitting diode.

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