Organic monomolecular light-emitting device based on platinum porphyrin dimer and preparation method thereof

Abstract

The present application relates to the technical field of light-emitting devices, and particularly relates to an organic monomolecular light-emitting device based on platinum porphyrin dimer and a preparation method thereof. The organic monomolecular light-emitting device comprises a pair of graphene electrodes and a functional molecule, wherein the functional molecule is connected between the pair of graphene electrodes, and the functional molecule is an organic compound containing a platinum porphyrin dimer structure. The selected functional molecule can integrate the three functions of hole transport, light emission and electron transport in one, greatly reduce the number of interfaces in the traditional multi-layer structure, reduce the energy loss and non-radiative recombination probability at the interface, and significantly improve the overall performance and long-term operation stability of the device; the functional molecule and the pair of graphene electrodes are combined through covalent connection, and electroluminescence can be realized. The preparation method provided by the present application uses dehydration condensation reaction to complete the connection of the functional molecule and the pair of graphene electrodes, and the preparation process is simple and has good reproducibility, which is conducive to realizing large-scale production.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of light-emitting devices, in particular to an organic monomolecular light-emitting device based on a platinum porphyrin dimer and a preparation method thereof. BACKGROUND

[0002] An organic light-emitting device (OLED) is an electronic device that utilizes organic materials to emit light under the action of an electric field. Its core principle is to emit photons through the use of organic semiconductor materials under the driving of an electric current, thereby realizing the conversion of electricity into light. Organic light-emitting devices have the advantages of thinness, low power consumption, high contrast, wide color gamut, material diversity, flexibility, and low-cost large-area preparation, and have been widely used in display technology, solid-state lighting, and other fields.

[0003] Monomolecular organic light-emitting devices are an important research direction in the field of organic light-emitting devices in recent years. Their core feature is the use of a single organic molecule as a light-emitting unit to achieve electroluminescence. Such devices have the advantages of small size, simplified structure, and unique performance, and are considered to be one of the important development directions of future display and optoelectronic devices.

[0004] However, there are still several key technical bottlenecks in the development of monomolecular organic light-emitting devices, mainly in the following three aspects:

[0005] First, the electrode-molecule interface level: when a traditional metal electrode directly contacts a molecule, it easily causes a serious Fermi pinning effect, which causes the metal Fermi level to be bound to the interface state level, severely hindering the effective injection of carriers and significantly degrading device performance. In addition, the high-energy states of the metal surface strongly couple with the molecular orbitals, which can destroy the electronic structure of the molecule and further exacerbate the non-radiative recombination of carriers at the interface, adversely affecting the light-emitting efficiency of the device.

[0006] Second, the molecule structure and integration level: how to achieve the precise, controllable, and stable arrangement of functional molecules between electrodes is one of the core challenges in this field. Existing technologies cannot simultaneously ensure the directional orientation, energy level matching, and structural stability of the molecules, resulting in problems such as poor carrier transport path, deviation of the recombination region from the light-emitting center, and directly restricting the performance of the device.

[0007] Third, the material system and energy level matching level: selecting appropriate functional molecules and achieving their gradient alignment of energy levels is the key to ensuring the performance of monomolecular organic light-emitting devices. In current technologies, there is a lack of integrated molecular design schemes that can simultaneously consider efficient carrier transport, stable light emission, and interface compatibility, which directly limits the further improvement of the performance of monomolecular organic light-emitting devices.

[0008] Based on the above technical status, how to provide a new type of organic light-emitting device to break through the bottleneck of the prior art is still a technical problem that needs to be solved at present. SUMMARY

[0009] The present application aims to at least solve one of the technical problems existing in the related art. To this end, a first object of the present application is to provide an organic monomolecular light-emitting device based on platinum porphyrin dimer; a second object of the present application is to provide a preparation method of the organic monomolecular light-emitting device based on platinum porphyrin dimer.

[0010] To achieve the first object, the technical solution adopted by the present application is:

[0011] The organic monomolecular light-emitting device based on platinum porphyrin dimer comprises a pair of graphene electrodes and a functional molecule, wherein the functional molecule is connected between the pair of graphene electrodes.

[0012] The functional molecule contains a platinum porphyrin dimer structure, and the functional molecule is any one of the following structural formulae:

[0013] 、

[0014] ;

[0015] R1 and R3 are each independently selected from or -OCH3;

[0016] R2 and R4 are each independently selected from -OH or NH2.

[0017] Further, the functional molecule with the structure of A has a synthesis route as shown below:

[0018]

[0019] Ar is Zn(OAc)2 is zinc acetate, AgPF6 is silver hexafluorophosphate, NBS is N-bromosuccinimide, TFA is trifluoroacetic acid, PtCl2 is dichloroplatinum, and PhCN is benzonitrile.

[0020] Further, the functional molecule with the structure of B has a synthesis route as shown below:

[0021]

[0022] Ar is Zn(OAc)2 is zinc acetate, AgPF6 is silver hexafluorophosphate, NBS is N-bromosuccinimide, Fe(OTf)3 is iron trifluoromethanesulfonate, TFA is trifluoroacetic acid, PtCl2 is dichloroplatinum, and PhCN is benzonitrile.

[0023] Further, the number of the functional molecules connected between the graphene electrode pairs is single.

[0024] Further, the graphene electrode is a triangular graphene array electrode, and the graphene array electrode is a graphene nanogap point electrode.

[0025] Further, the graphene electrode pair is loaded on an insulation layer, and the insulation layer mainly comprises silicon dioxide.

[0026] Further, the graphene electrode pair is respectively loaded with an anode electrode and a cathode electrode.

[0027] The anode electrode is composed of Cr and Au which are sequentially evaporated on the graphene electrode, and the cathode electrode is composed of Ca and Al which are sequentially evaporated on the graphene electrode.

[0028] Further, an oxidation protection layer is further included, and the oxidation protection layer covers the anode electrode and the cathode electrode, and the oxidation protection layer mainly comprises silicon dioxide.

[0029] In order to achieve the second object, the technical scheme adopted by the present application is:

[0030] The preparation method of the organic monomolecular light-emitting device based on platinum porphyrin dimer is used for preparing the organic monomolecular light-emitting device based on platinum porphyrin dimer as described in any one of the above, and characterized in that the method comprises the following steps:

[0031] S100, using chemical vapor deposition technology, preparing a device I with a graphene electrode pair;

[0032] S200, placing the device I, the functional molecules, the dehydration condensation agent and the organic solvent in a reaction container under anhydrous and oxygen-free conditions, and standing for at least 48 h, so that the -OH or NH2 at the end of the functional molecules and the -COOH at the end of the graphene electrode pair form a covalent bond after condensation reaction, thereby obtaining an organic monomolecular light-emitting device based on platinum porphyrin dimer.

[0033] Further, in step S200, the dehydration condensation agent is selected from 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride, and the organic solvent is selected from anhydrous pyridine.

[0034] The one or more technical solutions in the embodiments of the present application at least have one of the following technical effects:

[0035] The application provides an organic monomolecular light-emitting device based on a platinum porphyrin dimer and a preparation method thereof.

[0036] 1. The functional molecule can integrate hole transport, light emission and electron transport into one, greatly reducing the number of interfaces in the traditional multi-layer structure, reducing the energy loss and non-radiative recombination probability at the interface, and significantly improving the overall performance and long-term operation stability of the device.

[0037] 2. The functional molecule and the graphene electrode pair are covalently connected and combined, and electroluminescence can be realized; when the functional molecule is a single molecule, the device can also provide an effective solution for ultra-high density electronic integration.

[0038] 3. Graphene is used as an interface modification layer between the metal electrode and the functional molecule, which can effectively suppress the Fermi pinning effect and significantly improve the carrier injection efficiency. At the same time, the atomically smooth surface of the graphene electrode can reduce scattering and energy loss at the interface, thereby optimizing the carrier transport path.

[0039] The preparation method provided by the application uses one-step dehydration condensation reaction to complete the connection of the functional molecule and the graphene electrode pair. The method has simple preparation process and good reproducibility, and is conducive to realizing large-scale production.

[0040] Additional aspects and advantages of the application will be given in part in the following description, part will become apparent from the following description, or will be understood by those skilled in the art through practice of the application. BRIEF DESCRIPTION OF DRAWINGS

[0041] Figure 1 is a structural schematic diagram of the organic monomolecular light-emitting device based on the platinum porphyrin dimer provided by the embodiment of the application.

[0042] Figure 2 is a current-voltage (I-V) curve diagram of the organic monomolecular light-emitting device based on the platinum porphyrin dimer provided by the embodiment 4 of the application.

[0043] Figure 3 is an electroluminescence (EL) spectrum of the organic monomolecular light-emitting device based on the platinum porphyrin dimer provided by the embodiment 4 of the application and a photoluminescence (PL) spectrum of the functional molecule B I.

[0044] REFERENCE NUMERALS

[0045] 1. Graphene electrode pair; 2. Functional molecule. DETAILED DESCRIPTION

[0046] In order to make the objects, technical solutions and advantages of the present application clearer, the technical solutions in the present application will be described clearly and completely below in connection with specific embodiments. Obviously, the described embodiments are only some but not all of the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts should fall into the scope of the present application. The following embodiments are used to illustrate the present application but should not be used to limit the scope of the present application.

[0047] As shown in Figure 1 , the organic monomolecular light-emitting device based on platinum porphyrin dimer includes a pair of graphene electrodes 1 and a functional molecule 2 connected between the pair of graphene electrodes 1;

[0048] wherein the functional molecule contains a platinum porphyrin dimer structure, and the functional molecule is any one of the following structural formulae:

[0049] ,

[0050] .

[0051] According to one specific embodiment provided by the present application, the functional molecule is shown as structural formula A, R1 is selected from , and R2 is selected from -OH.

[0052] According to one specific embodiment provided by the present application, the functional molecule is shown as structural formula A, R1 is selected from -OCH3, and R2 is selected from -OH.

[0053] According to one specific embodiment provided by the present application, the functional molecule is shown as structural formula A, R1 is selected from , and R2 is selected from -NH2.

[0054] According to one specific embodiment provided by the present application, the functional molecule is shown as structural formula A, R1 is selected from -OCH3, and R2 is selected from -NH2.

[0055] According to one specific embodiment provided by the present application, the functional molecule is shown as structural formula B, R3 is selected from , and R4 is selected from -OH.

[0056] According to one specific embodiment provided by the present application, the functional molecule is shown as structural formula B, R3 is selected from -OCH3, and R4 is selected from -OH.

[0057] According to one specific embodiment provided by the present application, the functional molecule is shown as structural formula B, R3 is selected from , and R4 is selected from -NH2.

[0058] According to one specific embodiment provided by the present application, the functional molecule has the structure of Formula A, R3 is selected from -OCH3, and R4 is selected from -NH2.

[0059] According to one specific embodiment provided by the present application, the functional molecule has the structure of Formula A, and its synthetic route is shown as follows:

[0060]

[0061] wherein Ar is Zn(OAc)2 is zinc acetate, AgPF6 is silver hexafluorophosphate, NBS is N-bromosuccinimide, Fe(OTf)3 is iron triflate, TFA is trifluoroacetic acid, PtCl2 is platinum dichloride, and PhCN is benzonitrile.

[0062] According to one specific embodiment provided by the present application, the functional molecule has the structure of Formula B, and its synthetic route is shown as follows:

[0063]

[0064] wherein Ar is Zn(OAc)2 is zinc acetate, AgPF6 is silver hexafluorophosphate, NBS is N-bromosuccinimide, Fe(OTf)3 is iron triflate, TFA is trifluoroacetic acid, PtCl2 is platinum dichloride, and PhCN is benzonitrile.

[0065] In the following examples, the experimental methods used are conventional methods, and the techniques or conditions described in the literature in the art or according to the product instructions are used for the materials, reagents, etc. used, unless otherwise specified, which can be obtained from commercial channels.

[0066] Example 1

[0067] The preparation of compound 4, and its synthetic route is shown as follows:

[0068]

[0069] The synthesis process is described as follows:

[0070] I. Synthesis of compound 1.

[0071] The preparation of compound 1, and its synthetic route is shown as follows: (0.616 g, 3.8 mmol) and dipyrromethane (0.56 g, 3.8 mmol) were dissolved in chloroform (700 mL), the solution was saturated with nitrogen, then trifluoroacetic acid (0.5 mL, 7.6 mmol) was added, after stirring in the dark for 3 h, 2,3-dichloro-5,6-dicyano-p-benzoquinone (1.5 g, 6.6 mmol) was added, and stirring was continued for 20 min, then triethylamine (3.8 mL) was added, and stirring was continued in the dark for 15 min, the reaction was quenched, and the reaction solution was concentrated, and then separated and purified by silica gel column chromatography (eluent: a mixture of petroleum ether and dichloromethane, volume ratio 80:20) to obtain compound 1 as a purple solid, 1 H NMR, 13 The characterization data of1H NMR and13C NMR are as follows:

[0072] 1 H NMR (500 MHz, chloroform-d) : δ 7.47 (s, 1H), 7.44-7.36 (m, 7H), 7.36-7.28 (m, 5H), 7.18 (s, 1H), 7.09 (s, 1H), 7.03 (s, 1H), 6.76 (s, 1H), 6.70 (s, 1H), 1.34 (s, 18H), -2.56 (s, 2H);

[0073] 13 C NMR (125 MHz, chloroform-d) : δ 152.81, 152.77, 150.84, 148.92, 147.70, 146.68, 144.82, 143.46, 143.42, 139.50, 138.53, 131.53, 131.35, 129.92, 128.87, 128.54, 128.08, 127.65, 127.59, 126.52, 123.43, 122.97, 121.42, 121.32, 117.30, 103.42, 102.47, 37.05, 32.88.

[0074] II. Synthesis of compound 2.

[0075] Zn(OAc)2·2H2O (0.92 g, 4.2 mmol) was added to methanol (10 mL), and after stirring to dissolve, the dissolved solution was added to a chloroform (70 mL) solution of compound 1 (0.477 g, 0.83 mmol), and after stirring at 25°C for 3.5 h, evaporation was performed to obtain a concentrated solution, which was separated and purified by silica gel column chromatography (eluent: a mixture of petroleum ether and dichloromethane, volume ratio 80:20) to obtain compound 2 as a pink zinc porphyrin solid, 1 H NMR,13 The characterization data of C NMR are as follows:

[0076] 1 H NMR (500 MHz, Chloroform-d): δ 7.66 (s, 1H), 7.46 (s, 1H), 7.35-7.29 (m, 6H), 7.31-7.26 (m, 1H), 7.23 (d, J = 12.3 Hz, 2H), 7.14 (s, 1H), 7.07 (d, J = 7.9 Hz, 2H), 6.89 (s, 1H), 6.82 (d, J = 6.6 Hz, 2H), 6.63 (s, 1H), 1.34 (s, 18H);

[0077] 13 C NMR (125 MHz, Chloroform-d): δ 154.03, 153.00, 152.77, 152.33, 151.58, 151.05, 149.56, 148.91, 147.03, 140.81, 139.83, 131.52, 131.36, 128.64, 127.19, 126.61, 125.59, 125.47, 125.40, 124.96, 123.63, 123.13, 121.25, 120.90, 111.10, 108.61, 37.05, 32.88.

[0078] III. Synthesis of compound 3.

[0079] Compound 2 (0.172 g, 0.270 mmol) was dissolved in dry chloroform (100 mL), then silver hexafluorophosphate (AgPF6) (137 mg, 0.54 mmol) was added, and the mixture was uniformly mixed to obtain a mixed solution, which was heated to 50°C and reacted for 20 h, and then concentrated under reduced pressure, and then separated by silica gel column chromatography and gel permeation chromatography, to obtain a brown dimer compound 3;

[0080] The eluent for silica gel column chromatography was a mixed solvent of petroleum ether and dichloromethane, and the volume ratio of the two was 19:1. The eluent for gel permeation chromatography was a mixed solvent of toluene and pyridine, and the volume ratio of the two was 100:1.

[0081] The characterization data of compound 3 are as follows: 1 H NMR, 13 The characterization data of C NMR are as follows:

[0082] 1H NMR (500 MHz, Chloroform-d) δ 8.01 (s, 1H), 7.46 (s, 1H), 7.35 - 7.27 (m, 16H), 7.25 (s, 1H), 7.22 (s, 1H), 7.15 (s, 1H), 7.12 (s, 1H), 7.10 (s, 1H), 7.08 (s, 1H), 7.06 (s, 1H), 7.03 (s, 1H), 7.00 (s, 1H), 6.97 (d, J = 3.5 Hz, 2H), 6.89 (s, 1H), 6.82 (s, 1H), 6.63 (d, J = 0.7 Hz, 2H), 6.54 (s, 1H), 1.34 (s, 36H);

[0083] 13 C NMR (125 MHz, Chloroform-d) δ 152.77, 140.81, 139.83, 131.52, 131.41, 131.36, 130.17, 128.64, 128.31, 127.95, 127.68, 127.27, 127.19, 126.61, 126.37, 126.26, 125.68, 125.59, 125.40, 124.48, 124.01, 123.63, 121.25, 121.00, 111.10, 108.61, 37.05, 32.88.

[0084] IV. Synthesis of compound 4.

[0085] Compound 3 (24 mg, 0.019 mmol) was dissolved in a mixed solvent of chloroform (40 mL) and pyridine (0.16 mL), and cooled to 0°C, then a solution of N-bromosuccinimide (NBS) (6.9 mg, 0.039 mmol) (the solvent of the solution was composed of 10 mL of chloroform and 40 μL of pyridine) was added dropwise, and stirred for 15 min at 0°C. TLC showed complete conversion, then acetone (10 mL) was added to the reaction solution, stirred for 5 min, and the reaction was quenched. After removing the solvent by reduced pressure concentration, it was separated and purified by silica gel column chromatography (eluent: mixed solvent of petroleum ether and pyridine, volume ratio 98:2) and twice column chromatography (eluent: mixed solvent of petroleum ether and dichloromethane, volume ratio 9:1) to obtain compound 4 as a brown solid. 1 H NMR, 13 The characterization data of C NMR are as follows:

[0086] 1H NMR (500 MHz, Chloroform-d): δ 7.34-7.24 (m, 16H), 7.12 (s, 1H), 7.10 (s, 2H), 7.03 (d, J = 1.6 Hz, 3H), 7.00 (d, J = 4.8 Hz, 2H), 6.97 (d, J = 3.5 Hz, 2H), 6.85 (s, 1H), 6.73 (s, 1H), 6.66 (s, 1H), 6.63 (s, 1H), 6.54 (s, 1H), 1.34 (s, 36H);

[0087] 13 C NMR (125 MHz, Chloroform-d): δ 152.77, 140.81, 139.83, 131.52, 131.41, 131.36, 130.58, 130.17, 129.54, 128.64, 128.31, 127.95, 127.80, 127.76, 127.68, 127.27, 126.45, 126.37, 126.26, 125.17, 123.94, 123.29, 121.54, 120.78, 37.05, 32.88.

[0088] The following examples illustrate the synthesis of functional molecules, and the synthesis of other types of functional molecules is similar. and The following examples illustrate the synthesis of functional molecules, and the synthesis of other types of functional molecules is similar.

[0089] Example 2

[0090] Functional molecule A I was prepared according to the following synthetic route:

[0091]

[0092] The synthesis process is as follows:

[0093] I. Synthesis of compound 5.

[0094] A chloroform solution (0.7 mL) of trifluoroacetic acid with a concentration of 0.85 mmol was slowly added to a chloroform solution (12 mL) of compound 4 (25 mg, 18 μmol), stirred at 20 °C for 15 min, TLC (eluent: petroleum ether and dichloromethane mixed solvent, volume ratio 50:1) showed that the reactant was completely converted, and the crude product was obtained by vacuum concentration, which was separated and purified by silica gel column chromatography (eluent: petroleum ether and dichloromethane mixed solvent, volume ratio 25:1) to obtain purple solid compound 5, which had a yield of 18 μmol (100%). 1 H NMR, 13The characterization data of C NMR are as follows:

[0095] 1 H NMR (500 MHz, Chloroform-d): δ 7.62 (s, 1H), 7.52 (d, J = 3.7 Hz, 2H), 7.49 (s, 1H), 7.46 (s, 1H), 7.45 (s, 1H), 7.40 (tt, J = 7.7, 1.9 Hz, 10H), 7.35-7.26 (m, 9H), 7.16 (s, 1H), 7.13 (s, 2H), 6.84 (s, 1H), 6.79 (s, 1H), 6.71 (d, J = 6.2 Hz, 2H), 1.34 (s, 36H), -2.65 (s, 4H);

[0096] 13 C NMR (125 MHz, Chloroform-d): δ 152.77, 139.50, 138.57, 131.53, 131.35, 130.11, 129.46, 128.76, 128.54, 128.37, 128.22, 127.65, 127.62, 127.56, 127.45, 127.23, 126.43, 125.99, 125.72, 125.27, 124.80, 123.84, 123.38, 121.03, 120.28, 37.05, 32.88.

[0097] II. Synthesis of compound 6.

[0098] Compound 5 (98 mg, 75 μmol) was dissolved in benzonitrile (10 mL), and the solution was purged with nitrogen for 10 min, then a platinum chloride benzonitrile solution (4 mL) with a concentration of 0.12 mmol / mL was added, the temperature was raised to 190°C, and the reaction was stirred at this temperature for 4 d under a nitrogen atmosphere, then the benzonitrile was removed by concentration under reduced pressure to obtain a concentrate, which was separated and purified by silica gel column chromatography (eluent: a mixed solvent of petroleum ether and dichloromethane with a volume ratio of 100:25) to obtain solid compound 6, which had a yield of 70% (68 mg, 53 μmol). 1 H NMR, 13 The characterization data of C NMR are as follows:

[0099] 1¹H NMR (500 MHz, chloroform-d): δ 7.54 (s, 1H), 7.46 (d, J = 4.4 Hz, 2H), 7.37 (s, 1H), 7.36–7.26 (m, 20H), 7.24 (d, J = 3.7 Hz, 2H), 7.17 (s, 1H), 7.14 (s, 1H), 6.46 (s, 1H), 6.36 (s, 1H), 6.33 (s, 1H), 6.21 (s, 1H), 1.34 (s, 36H);

[0100] 13 C NMR (125 MHz, chloroform-d): δ 152.77, 142.19, 138.78, 132.92, 132.82, 132.77, 131.52, 131.36, 128.88, 128.70, 128.64, 128.31, 127.75, 127.45, 127.31, 127.10, 127.06, 126.75, 124.72, 124.56, 122.41, 119.64, 37.05, 32.88.

[0101] III. Synthesis of functional molecules AI.

[0102] Toluene (20 mL) and compound 6 (0.876 g, 0.52 mmol) were added sequentially to a 50 mL round-bottom flask, and nitrogen gas was purged for 10 min. Then, tetraphenylphosphine (0.040 g, 0.04 mmol) was added sequentially to the reaction flask. (0.281g, 0.52mmol) (0.225 g, 0.52 mmol) and 3 mL of a 1.98 mmol / mL sodium carbonate aqueous solution were heated under nitrogen atmosphere and refluxed for 5 h. After cooling to room temperature, 10 mL of dichloromethane was added to the reaction flask to dilute the reaction solution. The diluted reaction solution was transferred to a separatory funnel and washed with water (20 mL × 3). After each shaking and separation, the aqueous phase was discarded. Anhydrous sodium sulfate was added to the organic phase and dried to obtain the crude product. The crude product was purified by silica gel column chromatography (using a mixed solvent of methanol and dichloromethane, with a volume ratio of 1:100) to obtain the red solid functional molecule AI. 1 H NMR, 13 The characterization data of C NMR are as follows:

[0103] 1H NMR (500 MHz, Chloroform-d): δ 8.04 (s, 1H), 7.97 (s, 1H), 7.56 (s, 1H), 7.55-7.51 (m, 4H), 7.47-7.43 (m, 6H), 7.40 (s, 1H), 7.37 (s, 1H), 7.35-7.25 (m, 23H), 7.24-7.21 (m, 2H), 7.18 (dt, J = 7.5, 1.0 Hz, 2H), 6.36 (s, 1H), 6.33 (s, 1H), 6.19 (s, 1H), 6.13 (s, 1H), 4.26 (d, J = 12.4 Hz, 1H), 4.04 (d, J = 12.4 Hz, 1H), 3.68 (d, J = 5.4 Hz, 4H), 2.69-2.60 (m, 6H), 1.98 (s, 1H), 1.81-1.70 (m, 4H), 1.44 (d, J = 12.4 Hz, 1H), 1.38-1.28 (m, 43H), 0.90 (d, J = 2.4 Hz, 6H);

[0104] 13 C NMR (125 MHz, Chloroform-d): δ 152.77, 151.86, 142.19, 138.78, 133.20, 132.77, 131.92, 131.88, 131.52, 131.36, 131.14, 130.47, 129.46, 129.18, 129.16, 128.88, 128.75, 128.70, 128.67, 128.64, 128.36, 127.89, 127.84, 127.75, 127.67, 127.45, 127.10, 125.94, 124.28, 123.72, 121.99, 121.48, 114.10, 107.41, 77.58, 61.21, 42.34, 37.05, 35.55, 34.16, 32.88, 30.94, 29.91, 25.80, 23.38, 14.38, 11.57.

[0105] Example 3

[0106] Preparation of functional molecule B I, whose synthetic route is shown below:

[0107]

[0108] Its preparation process is described as follows:

[0109] I. Preparation of compound 7.

[0110] Compound 4 (68 mg, 0.048 mmol) was dissolved in anhydrous dichloromethane (50 mL), then Fe(OTf)3(122 mg, 0.243 mmol) was added, stirred for 6 h under argon atmosphere, then a 0.24 mmol / mL Zn(OAc)2methanol solution (2 mL) was added, after stirring for 30 min, the reaction was concentrated to obtain a crude product, which was separated and purified by silica gel column chromatography (eluent: mixed solvent of petroleum ether and dichloromethane, volume ratio 8:2) to obtain purple compound 7, which 1 H NMR, 13 The characterization data of1C NMR are as follows:

[0111] 1 H NMR (500 MHz, chloroform-d) δ 7.99 (s, 1H), 7.79 (s, 1H), 7.77 (s, 1H), 7.35-7.27 (m, 16H), 7.14 (s, 1H), 7.03 (d, J = 1.8 Hz, 2H), 7.01 (s, 1H), 6.93 (s, 1H), 6.85 (s, 1H), 6.72 (d, J = 3.3 Hz, 2H), 6.66 (s, 1H), 1.34 (s, 36H);

[0112] 13 C NMR (125 MHz, chloroform-d) δ 152.77, 138.96, 131.52, 131.36, 131.15, 130.58, 128.64, 127.45, 126.45, 125.17, 125.00, 123.94, 123.29, 122.82, 122.51, 120.78, 119.67, 118.12, 37.05, 32.88.

[0113] II. Preparation of compound 8.

[0114] A trifluoroacetic acid chloroform solution (67 mL) with a concentration of 1.2 mmol / mL was slowly added to a compound 7 chloroform solution (12 mL) with a concentration of 1.5 μmol / mL, stirred at 20°C for 15 min, TLC (eluent: mixed solvent of petroleum ether and dichloromethane, 10:1) showed that the reactants were completely converted, and the crude product was obtained by vacuum concentration, which was separated and purified by silica gel column chromatography (eluent: chloroform) to obtain purple solid compound 8, which 1 H NMR, 13 The characterization data of1C NMR are as follows:

[0115] 1H NMR (500 MHz, Chloroform-d): δ 8.04 (s, 1H), 7.79 (s, 1H), 7.62 (s, 1H), 7.52 (d, J = 3.7 Hz, 2H), 7.46 (s, 1H), 7.44-7.38 (m, 8H), 7.35-7.27 (m, 9H), 7.13 (d, J = 8.2 Hz, 2H), 6.84 (s, 1H), 6.72 (s, 1H), 6.64 (s, 1H), 1.34 (s, 36H), -2.88 (s, 4H);

[0116] 13 C NMR (125 MHz, Chloroform-d): δ 152.77, 139.09, 131.53, 131.35, 128.76, 128.54, 127.65, 127.62, 127.53, 127.45, 125.72, 125.27, 124.00, 123.38, 120.28, 117.80, 117.17, 116.34, 37.05, 32.88.

[0117] III. Preparation of compound 9.

[0118] Compound 8 (98 mg, 75 μmol) was dissolved in benzonitrile (10 mL), and the solution was purged with nitrogen for 10 min. A platinum chloride solution (4 mL) with a concentration of 0.12 mmol / mL was added, and the temperature was raised to 190 °C. After stirring at this temperature for 4 d under a nitrogen atmosphere, the benzonitrile was removed by concentration under reduced pressure to obtain a concentrate. The concentrate was separated and purified by column chromatography on silica gel (eluent: a mixture of petroleum ether and dichloromethane with a volume ratio of 100:25) to obtain compound 9 as a red-brown solid. 1 H NMR, 13 The characterization data of C NMR are as follows:

[0119] 1 H NMR (500 MHz, Chloroform-d): δ 7.73 (s, 1H), 7.63 (s, 1H), 7.50 (s, 1H), 7.37 (s, 1H), 7.34-7.26 (m, 17H), 7.24 (d, J = 3.7 Hz, 2H), 7.17 (s, 1H), 7.14 (s, 1H), 6.93 (s, 1H), 6.46 (s, 1H), 6.13 (s, 1H), 1.34 (s, 36H);

[0120] 13C NMR (125 MHz, chloroform-d): δ 152.77, 140.68, 132.78, 131.52, 131.36, 128.64, 127.31, 127.06, 126.75, 125.53, 124.72, 124.56, 122.98, 122.41, 122.28, 120.57, 119.64, 110.79, 37.05, 32.88.

[0121] IV. Preparation of functional molecule BⅠ.

[0122] Toluene (20 mL) and compound 9 (0.876 g, 0.52 mmol) were added sequentially to a 50 mL round-bottom flask, and nitrogen gas was purged for 10 min. Then, tetraphenylphosphine (0.040 g, 0.04 mmol) was added sequentially to the reaction flask. (0.281g, 0.52mmol) (0.225 g, 0.52 mmol) and 3 mL of a 1.98 mmol / mL sodium carbonate aqueous solution were heated under nitrogen atmosphere and refluxed for 5 h. After cooling to room temperature, 10 mL of dichloromethane was added to the reaction flask to dilute the reaction solution. The diluted reaction solution was transferred to a separatory funnel and washed with water (20 mL × 3). After each shaking and separation, the aqueous phase was discarded. Anhydrous sodium sulfate was added to the organic phase and dried to obtain the crude product. The crude product was purified by silica gel column chromatography (using a mixed solvent of acetone and dichloromethane, with a volume ratio of 2:100) to obtain a reddish-brown solid functional molecule AI. 1 H NMR, 13 The characterization data of C NMR are as follows:

[0123] 1H NMR (500 MHz, Chloroform-d): δ 8.04 (s, 1H), 7.97 (s, 1H), 7.73 (s, 1H), 7.63 (s, 1H), 7.56 (s, 1H), 7.55-7.51 (m, 3H), 7.50 (s, 1H), 7.47-7.43 (m, 5H), 7.40 (s, 1H), 7.37 (s, 1H), 7.35-7.25 (m, 18H), 7.25-7.20 (m, 3H), 7.18 (dt, J = 7.5, 1.0 Hz, 2H), 6.93 (s, 1H), 6.19 (s, 1H), 6.13 (s, 1H), 4.26 (d, J = 12.4 Hz, 1H), 4.04 (d, J = 12.4 Hz, 1H), 3.68 (d, J = 5.4 Hz, 4H), 2.69-2.59 (m, 6H), 1.98 (s, 1H), 1.80-1.73 (m, 4H), 1.46-1.26 (m, 44H), 0.90 (d, J = 2.4 Hz, 6H);

[0124] 13 C NMR (125 MHz, Chloroform-d): δ 152.77, 140.68, 131.92, 131.88, 131.52, 131.36, 131.14, 130.47, 129.18, 129.16, 128.75, 128.67, 128.64, 127.89, 127.84, 127.75, 127.71, 127.45, 125.94, 125.53, 124.28, 123.72, 122.98, 122.28, 121.48, 120.57, 114.10, 110.79, 107.41, 77.58, 61.21, 42.34, 37.05, 35.55, 34.16, 32.88, 30.94, 29.91, 25.80, 23.38, 14.38, 11.57.

[0125] Example 4

[0126] Taking the functional molecule provided in Example 3 as an example, an organic single-molecule light-emitting device based on platinum porphyrin dimer is prepared, and the process is as follows:

[0127] I. Preparation of graphene film on silicon substrate.

[0128] (I) Growth of graphene on copper foil.

[0129] The graphene layer is prepared by chemical vapor deposition (CVD) on a copper foil with a thickness of 25 μm using methane (CH4) gas as a carbon source in the following process:

[0130] The copper foil is immersed in glacial acetic acid at room temperature for 20 min to remove the oxides and impurities on the surface thereof and improve the surface flatness thereof; the copper foil is placed in a tube furnace, and vacuumized by a mechanical pump to below 0.1 Pa; after purging with hydrogen (H2) at a flow rate of 14 sccm for 5 min, the temperature is raised to 1040°C and annealed for 90 min to further reduce the copper foil and improve the flatness thereof; the flow rate of H2 is adjusted to 7 sccm, and CH4 is introduced at a flow rate of 1.4 sccm for graphene growth, which lasts for 30 min. Subsequently, the gas flow rates are adjusted as follows: H2 is 14 sccm, and CH4 is 0.7 sccm; after cooling to 500°C, the flow rate of H2 is maintained, and CH4 is turned off; after cooling to room temperature, the copper foil with graphene grown on the surface thereof is taken out.

[0131] (ii) transferring the graphene to the surface of a substrate.

[0132] The transfer of the graphene uses a polymethyl methacrylate (PMMA) polymer film with a polymerization degree of 950 as a flexible substrate, and the graphene is transferred to the surface of a SiO2 (with a thickness of 300 nm) silicon substrate in the following process:

[0133] The PMMA is spin-coated on the surface of the copper foil with graphene at room temperature, and the PMMA is solidified by heating at 180°C for 2 min to obtain a “PMMA-graphene-copper” sandwich structure; the graphene on the lower surface of the copper foil is removed by oxygen plasma etching to improve the etching efficiency of the copper in the next step; the “PMMA-graphene-copper” sheet layer after solidification is cut according to the size of the silicon substrate, immersed in a fresh ferric chloride solution with a pH of about 3 (to ensure that the Cu is completely in contact with the solution), and left to stand until the Cu is completely dissolved to obtain a “PMMA-graphene” transparent film structure; the film is sequentially cleaned with hydrochloric acid solutions with volume fractions of 10%, 5% and 2%, respectively, and left to stand for 30 min after each step, and then soaked and cleaned with ultrapure water three times.

[0134] SiO2 / Si substrate (1 cm x 1 cm) was soaked in piranha solution (30 wt% H2O2 and concentrated H2SO4 in volume ratio of 3:7) and cleaned at 110 °C for 5 h; then the substrate was taken out and ultrasonicated in ultrapure water for 10 min, and the cleaning process was repeated for 4 times. The silicon substrate was then ultrasonicated in acetone, ethanol and ultrapure water for 10 min, respectively, and dried with nitrogen. The "PMMA-graphene" film was taken out of water with the silicon substrate (make sure the film is flat), and left to dry naturally in the fume hood for 12 h. The dried "PMMA-graphene-SiO2 / Si" sheet was annealed at 400 °C for 3 min in a tube furnace under atmospheric air to remove the PMMA layer, and a graphene film was obtained, which was covered on the silicon substrate.

[0135] II. Preparation of a device basic configuration with graphene-based terminals, the process is as follows:

[0136] (I) Pretreatment and marking pattern: the obtained "graphene-SiO2 / Si" substrate was rinsed and blown with acetone, and after drying, a marking area was defined on the surface by first photolithography, and then a 600 nm thick gold (Au) layer was deposited by thermal evaporation process to form a marking pattern;

[0137] (II) Graphene strip patterning: the second photolithography was performed to protect the graphene central strip area to be reserved on the substrate, and the graphene area not protected by the photoresist was oxidized and etched by oxygen plasma; after etching, the residual photoresist was removed by rinsing with acetone, and the graphene nanostrip with a length of 250 μm and a width of 40 mm was obtained after drying;

[0138] (III) Anode preparation: the third photolithography was performed on the surface of the graphene strip to define the anode electrode pattern; then a 5 nm thick Cr layer (as an adhesion layer between the metal electrode and graphene) and a 150 nm thick Au layer (work function about 5.1-5.3 eV) were deposited by thermal evaporation process; finally, a 10 nm thick SiO2 layer (as an oxidation protection layer for the anode) was deposited by electron beam evaporation process;

[0139] (IV) Cathode preparation: the fourth photolithography was performed on the surface of the graphene strip (outside the area corresponding to the anode) to define the cathode electrode pattern; then a 20 nm thick Ca layer (work function about 2.9 eV) and a 100 nm thick Al layer (for protecting the internal Ca layer from oxidation) were deposited by thermal evaporation process; finally, a 10 nm thick SiO2 layer (as an oxidation protection layer for the cathode) was deposited by electron beam evaporation process, and a device basic configuration with graphene-based terminals was obtained.

[0140] III. Preparation of nanoscale graphene point contact electrode array:

[0141] Prepared according to the method disclosed in the reference, the process is as follows:

[0142] (I) Preparation of mask layer: PMMA is spin-coated on the surface of the device prepared above as a mask layer, and baked on a 180°C heating platform for 2 min to volatilize the solvent and solidify;

[0143] (II) Patterned exposure: electron beam lithography is performed on each graphene strip to obtain an equidistant dotted line structure with a line width of 5 nm (wherein the solid line segment is about 150 nm long and the interval segment is about 40 nm wide);

[0144] (III) Development and fixing: methyl isobutyl ketone and isopropyl alcohol mixture (volume ratio of 1:3) is used as the developing solution, and pure isopropyl alcohol is used as the fixing solution; after development (about 20 s) and fixing treatment, the graphene strip surface forms a dotted line pattern after exposure;

[0145] (IV) Etching and monitoring: the developed device is subjected to oxygen plasma etching, and the current between the anode and cathode of the device is monitored in real time by a semiconductor parameter analyzer; when the monitored current is exactly 0, it indicates that the graphene dotted line has been completely cut off, and the electrode end is modified by oxidation to form a carboxyl group;

[0146] (V) Removal of mask: the etched device is soaked in acetone for more than 12 h to remove the residual PMMA mask layer on the surface;

[0147] (VI) A bias voltage is applied to the ends of the clean device by a probe station, and the unetched graphene electrode pairs are further cut off by Joule heating effect until the monitored current is 0, i.e. a nanoscale graphene point contact electrode array is prepared.

[0148] The foregoing references are as follows:

[0149] Yang C, Yang C, Guo Y, et al. Graphene–molecule–graphene single-molecule junctions to detect electronic reactions at the molecular scale. Nature Protocols, 2023, 18(6): 1958-1978.

[0150] IV. Connecting functional molecules to graphene electrode pairs:

[0151] After the nanoscale graphene point contact electrode array prepared in the foregoing preparation is cleaned with acetone and dried in a 60°C oven for 30 min, the dried nanoscale graphene point contact electrode array, functional molecule B I (1 mg), 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride (0.1 g), and anhydrous pyridine (10 mL) are sequentially added to a reaction container, and the reaction is allowed to stand for 48 h under a nitrogen atmosphere. After the reaction is completed, the device surface is sequentially rinsed with acetone and deionized water, and the device is electrically characterized by a semiconductor parameter analyzer. The current value obtained by the test is compared with the fA-level background current of the device without the functional molecule. The results are shown in FIG. 6. Figure 2 When the device current is increased to the nA level or above, it is proved that the functional molecule B I is successfully connected between the graphene electrode pairs, i.e., an organic monomolecular light-emitting device based on platinum porphyrin dimers is obtained. As can be seen from the figure, the I-V curve presents clear asymmetry and rectification characteristics: the current sharply rises with the increase of voltage under forward bias.

[0152] The organic monomolecular light-emitting device based on platinum porphyrin dimers is subjected to electroluminescence test, and the process is as follows: while a forward direct current bias is applied to the monomolecular light-emitting device, a confocal microscope objective is used to collect extremely weak light signals emitted from the nanogap region, and a single-photon detector coupled with a spectrometer is used for signal detection to obtain the EL spectrum of the device and the PL spectrum of the functional molecule B I. The results are shown in FIG. 7. Figure 3 As can be seen from the figure, the spectral peak positions and peak shape heights of the two are consistent, which indicates that the light-emitting source of the device after power-on is the functional molecule B I, and the interference of background stray light or other substance light emission is excluded.

[0153] Finally, it should be noted that the above examples are only used to illustrate the technical solutions of the present application, but not to limit them; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that the technical solutions recorded in the foregoing examples can still be modified, or some technical features can be replaced by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. An organic monomolecular light-emitting device based on platinum porphyrin dimer, characterized in that, The graphene electrode pair and a functional molecule connected between the graphene electrode pair are included. The functional molecule contains a platinum porphyrin dimer structure, and the structural formula of the functional molecule is as follows: ； wherein R3is selected from ; R4 is selected from -OH or NH2.

2. The platinum porphyrin dimer-based organic monomolecular light-emitting device according to claim 1, wherein The synthesis route of the functional molecule is shown as follows: wherein Ar is Zn(OAc)2 is zinc acetate, AgPF6 is silver hexafluorophosphate, NBS is N-bromosuccinimide, Fe(OTf)3 is iron triflate, TFA is trifluoroacetic acid, PtCl2 is platinum dichloride, and PhCN is benzonitrile.

3. The platinum porphyrin dimer-based organic monomolecular light-emitting device according to claim 1, wherein The number of the functional molecules connected between the graphene electrode pair is single.

4. The platinum porphyrin dimer-based organic monomolecular light emitting device according to claim 1, wherein The graphene electrode is a triangular graphene array electrode, and the graphene array electrode is a graphene nanogap point electrode.

5. The platinum porphyrin dimer-based organic monomolecular light emitting device according to claim 1, wherein The graphene electrode pair is loaded on an insulating layer, and the main component of the insulating layer is silicon dioxide.

6. The platinum porphyrin dimer-based organic monomolecular light emitting device according to claim 1, wherein An anode electrode and a cathode electrode are respectively loaded on the graphene electrode pair. The anode electrode is composed of Cr and Au which are evaporated on the graphene electrode in sequence, and the cathode electrode is composed of Ca and Al which are evaporated on the graphene electrode in sequence.

7. The organic single-molecule light-emitting device based on platinum porphyrin dimer as described in claim 6, characterized in that, An oxidation protection layer is also included, which covers the anode electrode and the cathode electrode, and the main component of the oxidation protection layer is silicon dioxide.

8. A method for preparing an organic monomolecular light emitting device based on platinum porphyrin dimers, characterized in that, A method for preparing the platinum porphyrin dimer-based organic monomolecular light-emitting device according to any one of claims 1 to 7, characterized in that it comprises the following steps: S100, using chemical vapor deposition technology to prepare a device I with a graphene electrode pair; S200, placing the device I, a functional molecule, a dehydration condensation agent and an organic solvent in a reaction container under anhydrous and oxygen-free conditions, and standing for at least 48 h, so that the -OH or NH2 at the end of the functional molecule and the -COOH at the end of the graphene electrode pair form a covalent bond after condensation reaction to obtain a platinum porphyrin dimer-based organic monomolecular light-emitting device.

9. The method for preparing an organic single-molecule light-emitting device based on platinum porphyrin dimer as described in claim 8, characterized in that, In step S200, the dehydration condensation agent is selected from 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride, and the organic solvent is selected from anhydrous pyridine.

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