Platinum porphyrin dimer-based organic monomolecular luminescent device and preparation method thereof

Abstract

The invention 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 of the organic monomolecular light-emitting device. The organic monomolecular light-emitting device comprises a graphene electrode pair and a functional molecule, the functional molecule is connected between the graphene electrode pair, and the functional molecule is an organic compound containing a platinum porphyrin dimer structure. The selected functional molecules can integrate three functions of hole transport, luminescence and electron transport into a whole, the number of interfaces in a traditional multilayer structure is greatly reduced, the energy loss and non-radiative recombination probability at the interfaces are reduced, and the overall performance and long-term operation stability of the device are remarkably improved; the functional molecules and the graphene electrode pair are combined through covalent linkage, and electroluminescence can be achieved. According to the preparation method provided by the invention, the connection of the functional molecules and the graphene electrode pair is completed by adopting the dehydration condensation reaction, the preparation process is simple, the reproducibility is good, and large-scale production is favorably realized.

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, achieving 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: 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, further exacerbating the non-radiative recombination of carriers at the interface, and adversely affecting the light-emitting efficiency of the device.

[0005] 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, and recombination region deviating from the light-emitting center, directly restricting the performance of the device.

[0006] 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.

[0007] 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

[0008] The present application aims to at least solve one of the technical problems existing in the related art. To this end, the first object of the present application is to provide an organic monomolecular light-emitting device based on platinum porphyrin dimer; the second object of the present application is to provide a preparation method of the organic monomolecular light-emitting device based on platinum porphyrin dimer.

[0009] In order to achieve the first object, the technical solution adopted by the present application is: 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. The functional molecule contains a platinum porphyrin dimer structure, and the functional molecule is any one of the following structural formulae: 、 ; R1 and R3 are each independently selected from or -OCH3; R2 and R4 are each independently selected from -OH or NH2.

[0010] Further, the functional molecule with the structure of A has a synthesis route as shown below: wherein 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.

[0011] Further, the functional molecule with the structure of B has a synthesis route as shown below: wherein 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.

[0012] Further, the number of the functional molecules connected between the pair of graphene electrodes is single.

[0013] Further, the graphene electrode is a triangular graphene array electrode, and the graphene array electrode is a graphene nanogap point electrode.

[0014] Further, the graphene electrode pair is loaded on an insulating layer, and the insulating layer mainly comprises silicon dioxide.

[0015] Further, 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 sequentially evaporated on the graphene electrode, and the cathode electrode is composed of Ca and Al which are sequentially evaporated on the graphene electrode.

[0016] 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.

[0017] In order to achieve the second object, the technical scheme adopted by the present application is: 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: S100, a device I with a graphene electrode pair is prepared by using chemical vapor deposition technology; S200, the device I, a functional molecule, a dehydration condensation agent and an organic solvent are placed in a reaction container under anhydrous and oxygen-free conditions, and are left for at least 48 hours, 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 a condensation reaction, thereby obtaining an organic monomolecular light-emitting device based on platinum porphyrin dimer.

[0018] Further, in the 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.

[0019] The one or more technical solutions in the embodiments of the present application at least have one of the following technical effects: The present application provides an organic monomolecular light-emitting device based on platinum porphyrin dimer and a preparation method thereof. The organic monomolecular light-emitting device comprises a graphene electrode pair and a functional molecule, wherein the functional molecule is connected between the graphene electrode pair, and the functional molecule is an organic compound containing a platinum porphyrin dimer structure. The organic monomolecular light-emitting device based on platinum porphyrin dimer has the following advantages: I. The functional molecule can integrate the functions of hole transport, light emission and electron transport in 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. II. The functional molecules can be combined with the graphene electrode pair through covalent connection to realize electroluminescence; when the functional molecules are single molecules, the device can also provide an effective solution for ultra-high density electronic integration; III. The graphene is used as an interface modification layer between the metal electrode and the functional molecules, so that the Fermi pinning effect can be effectively inhibited, and the carrier injection efficiency can be significantly improved. Meanwhile, the atom-level flat surface of the graphene electrode can reduce scattering and energy loss at the interface, and thus the carrier transmission path can be optimized.

[0020] The preparation method provided by the application can complete the connection of the functional molecules and the graphene electrode pair through one-step dehydration condensation reaction. The method has simple preparation process and good reproducibility, and is conducive to realizing large-scale production.

[0021] Additional aspects and advantages of the application will be described in part below, will become apparent from the following description, or will be learned by practice of the application. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 is a structural schematic diagram of an organic single-molecule light-emitting device based on a platinum porphyrin dimer provided by an embodiment of the application.

[0023] Figure 2 is a current-voltage (I-V) curve diagram of an organic single-molecule light-emitting device based on a platinum porphyrin dimer provided by embodiment 4 of the application.

[0024] Figure 3 is an electroluminescence (EL) spectrum of an organic single-molecule light-emitting device based on a platinum porphyrin dimer provided by embodiment 4 of the application and a photoluminescence (PL) spectrum of a functional molecule BI.

[0025] REFERENCE NUMERALS 1. graphene electrode pair; 2. functional molecule. DETAILED DESCRIPTION

[0026] In order to make the objects, technical solutions and advantages of the application clearer, the technical solutions in the application will be described clearly and completely below in combination with specific embodiments. Obviously, the described embodiments are some embodiments of the application, but not all the embodiments of the application. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the application. The following embodiments are used to illustrate the application, but cannot be used to limit the scope of the application.

[0027] As Figure 1As shown, 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; wherein the functional molecule contains a platinum porphyrin dimer structure, and the functional molecule is any one of the following structural formulae: 、 .

[0028] 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.

[0029] 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.

[0030] 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.

[0031] 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.

[0032] 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.

[0033] 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.

[0034] 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.

[0035] 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 -NH2.

[0036] According to one specific embodiment provided by the present application, the functional molecule with structural formula A is synthesized according to the following route: wherein 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.

[0037] According to one specific embodiment of the present application, a functional molecule with the structure of B is provided, and its synthetic route 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.

[0038] In the following examples, the experimental methods used are conventional methods, and the used materials, reagents, etc. are commercially available unless otherwise specified, and are performed according to the techniques or conditions described in the literature in the art or according to the product instructions unless otherwise specified.

[0039] Example 1 Preparation of compound 4, and its synthetic route is shown as follows: The synthesis process is described as follows: I. Synthesis of compound 1.

[0040] p-tert-butylbenzaldehyde (0.616 g, 3.8 mmol) and dipyrromethane (0.56 g, 3.8 mmol) were dissolved in chloroform (700 mL), and the solution was saturated with nitrogen, then trifluoroacetic acid (0.5 mL, 7.6 mmol) was added, and 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, and 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, in a volume ratio of 80:20) to obtain purple solid compound 1, and its 1 H NMR, 13 C NMR characterization data are as follows: 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); 13C 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.

[0041] II. Synthesis of compound 2.

[0042] Zn(OAc)2-2H2O (0.92 g, 4.2 mmol) was added to methanol (10 mL) and stirred to dissolve, then the solution was added to a chloroform (70 mL) solution of compound 1 (0.477 g, 0.83 mmol), stirred at 25 °C for 3.5 h, then evaporated to obtain a concentrated solution, which was separated and purified by silica gel column chromatography (eluent: mixed solvent of petroleum ether and dichloromethane, volume ratio 80:20) to obtain pink zinc porphyrin solid compound 2, which had a yield of 0.48 g (0.73 mmol, 87.5%). 1 H NMR, 13 The characterization data of C NMR are as follows: 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); 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.

[0043] III. Synthesis of compound 3.

[0044] 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, mixed uniformly to obtain a mixed solution, which was heated to 50°C, reacted for 20 h, then concentrated under reduced pressure, and separated by silica gel column chromatography and gel permeation chromatography in turn to obtain brown dimer compound 3; wherein the eluent of silica gel column chromatography was a mixed solvent of petroleum ether and dichloromethane, and the volume ratio of the two was 19:1, and the eluent of gel permeation chromatography was a mixed solvent of toluene and pyridine, and the volume ratio of the two was 100:1; The characterization data of compound 3 by H NMR, 1 H NMR, 13 C NMR are as follows: 1 H 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); 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.

[0045] IV. Synthesis of compound 4.

[0046] 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 this solution was composed of 10 mL of chloroform and 40 μL of pyridine) was added dropwise, and stirred for 15 min at 0 °C, thin layer chromatography showed complete conversion, then acetone (10 mL) was added to the reaction solution, stirred for 5 min, quenched the reaction, and the solvent was removed by concentration under reduced pressure, then separated and purified by silica gel column chromatography (eluent was a mixed solvent of petroleum ether and pyridine, the volume ratio of the two was 98:2) twice (eluent was a mixed solvent of petroleum ether and dichloromethane, the volume ratio of the two was 9:1) to obtain compound 4 as a brown solid, which was characterized by 1 H NMR, 13 C NMR characterization data are as follows: 1 H 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), 6.93 (s, 1H), 6.85 (s, 1H), 6.73 (s, 1H), 6.66 (s, 1H), 6.63 (s, 1H), 6.54 (s, 1H), 1.34 (s, 36H); 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.

[0047] The following examples illustrate the synthesis process of functional molecules, and the synthesis process of other types of functional molecules is similar. and For example, the synthesis process of functional molecules is illustrated, and the synthesis process of other types of functional molecules is similar.

[0048] Example 2 Preparation of functional molecule A I, the synthetic route of which is shown as follows: The synthetic process is described as follows: I. Synthesis of compound 5.

[0049] 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) at 20 °C, stirred for 15 min, TLC (eluent: petroleum ether and dichloromethane mixed solvent, volume ratio 50:1) observation 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: petroleum ether and dichloromethane mixed solvent, volume ratio 25:1) to obtain purple solid compound 5, which had a yield of 18 μmol, 100% (based on compound 4). 1 H NMR, 13 The characterization data of H NMR and C NMR are described as follows: 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); 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.

[0050] II. Synthesis of compound 6.

[0051] 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 nitrogen. 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 mixture of petroleum ether and dichloromethane with a volume ratio of 100:25) to obtain solid compound 6, which was characterized by 1 H NMR, 13 C NMR data are as follows: 1 H 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); 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.

[0052] III. Synthesis of functional molecule AI.

[0053] Toluene (20 ml), compound 6 (0.876 g, 0.52 mmol) were sequentially added to a 50 mL round-bottom flask, and nitrogen was introduced for 10 min, then tetraphenylphosphonium (0.040 g, 0.04 mmol), potassium carbonate (0.281 g, 0.52 mmol), and compound 7 (0.876 g, 0.52 mmol) were sequentially added to the reaction flask, and the reaction was stirred at 80 °C for 24 h. The reaction was filtered, and the filtrate was concentrated under reduced pressure to obtain a concentrate, which was separated and purified by silica gel column chromatography (eluent: a mixture of petroleum ether and dichloromethane with a volume ratio of 100:25) to obtain solid compound AI, which was characterized by (0.281 g, 0.52 mmol), (0.225 g, 0.52 mmol) and aqueous sodium carbonate solution (3 mL, 1.98 mmol / mL) under nitrogen atmosphere, heated to reflux for 5 h, cooled to room temperature, diluted with dichloromethane (10 mL) and transferred to a separatory funnel. The aqueous phase was discarded after each layer was shaken and separated. The organic phase was dried over anhydrous sodium sulfate and concentrated to give a crude product. The crude product was purified by silica gel column chromatography (eluent: methanol / dichloromethane, 1:100, v / v) to give functional molecule AI as a red solid. 1 H NMR, 13 C NMR data are as follows: 1 H 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); 13C 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.

[0054] Example 3 Preparation of functional molecule B I, the synthetic route of which is shown below: The preparation process is described as follows: I. Preparation of compound 7.

[0055] 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, and after stirring for 30 min, the reaction solution was concentrated to obtain a crude product, which was separated and purified by silica gel column chromatography (eluent: petroleum ether and dichloromethane mixed solvent, volume ratio 8:2) to obtain purple compound 7, which had a yield of 70% and its 1 H NMR, 13 The characterization data of C NMR are described as follows: 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), 6.72 (d, J = 3.3 Hz, 2H), 6.66 (s, 1H), 1.34 (s, 36H); 13C 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.

[0056] II. Preparation of compound 8.

[0057] Trifluoroacetic acid chloroform solution (67 mL) with concentration of 1.2 mmol / ml was slowly added to compound 7 chloroform solution (12 mL) with concentration of 1.5 μmol / mL, stirred at 20 °C for 15 min, TLC (eluent: 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, with yield of 0.8 g, 70.0%. 1 H NMR, 13 The characterization data of C NMR are as follows: 1 H 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); 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.

[0058] III. Preparation of compound 9.

[0059] 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. The reaction was stirred 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 silica gel column chromatography (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 of1H NMR and13C NMR are as follows: 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); 13 C 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.

[0060] IV. Preparation of functional molecule B I.

[0061] Toluene (20 mL), compound 9 (0.876 g, 0.52 mmol), and compound 10 (0.281 g, 0.52 mmol) were sequentially added to a 50 mL round-bottom flask, and nitrogen was introduced for 10 min. Tetraphenylphosphonium (0.040 g, 0.04 mmol) was then added to the reaction flask, followed by the addition of a platinum chloride solution (4 mL) with a concentration of 0.12 mmol / mL. The temperature was raised to 190 °C, and the reaction was stirred at this temperature for 4 d under a nitrogen atmosphere. The toluene was removed by concentration under reduced pressure to obtain a concentrate. The concentrate was separated and purified by silica gel column chromatography (eluent: a mixture of petroleum ether and dichloromethane with a volume ratio of 100:25) to obtain compound 11 as a red-brown solid. (0.281 g, 0.52 mmol), (0.225 g, 0.52 mmol) and aqueous sodium carbonate solution (3 mL, 1.98 mmol / mL) under nitrogen atmosphere, heated to reflux for 5 h, cooled to room temperature, diluted with dichloromethane (10 mL) and transferred to a separatory funnel. The organic phase was washed with water (20 mL x 3), the aqueous phase was discarded after each time the layers were shaken, dried over anhydrous sodium sulfate and the crude product was obtained. The crude product was purified by silica gel column chromatography (eluent: acetone and dichloromethane in a volume ratio of 2:100) to obtain the red-brown solid functional molecule AI, which was characterized by1H NMR, 1 H NMR, 13 C NMR data are described as follows: 1 H 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); 13C 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.

[0062] Example 4 Taking the functional molecule provided in Example 3 as an example, an organic monomolecular light-emitting device based on platinum porphyrin dimer is prepared, and the process is as follows: I. Preparing a graphene film on a silicon substrate.

[0063] (I) Growing graphene on a copper foil.

[0064] Taking methane (CH4) gas as a carbon source, a graphene layer is prepared on a copper foil with a thickness of 25 μm by chemical vapor deposition (CVD) as follows: At room temperature, the copper foil is soaked in glacial acetic acid for 20 min to remove the oxides and impurities on the surface and improve the surface flatness. The copper foil is placed in a tube furnace and vacuumed to below 0.1 Pa by a mechanical pump. After purging with 14 sccm of hydrogen (H2) for 5 min, the temperature is raised to 1040°C and annealed for 90 min to further reduce the copper foil and improve its flatness. The H2 flow is adjusted to 7 sccm, and the CH4 flow is adjusted to 1.4 sccm for graphene growth, which lasts for 30 min. Subsequently, the gas flow is adjusted: H2 is 14 sccm, CH4 is 0.7 sccm, the temperature is cooled to 500°C, the H2 flow is maintained, and the CH4 is turned off. After cooling to room temperature, the copper foil with graphene grown on the surface is taken out.

[0065] (II) Transferring graphene to the surface of the substrate.

[0066] The transfer of graphene uses a polymethyl methacrylate (PMMA) high molecular film with a polymerization degree of 950 as a flexible substrate to transfer graphene to the surface of a SiO2 (thickness of 300 nm) silicon substrate, and the process is as follows: PMMA was spin-coated onto the surface of the graphene grown copper foil at room temperature, and the PMMA was cured 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 was removed by oxygen plasma etching to improve the etching efficiency of the copper in the next step; the cured "PMMA-graphene-copper" sheet was cut according to the size of the silicon substrate, and then immersed in a fresh ferric chloride solution with a pH of about 3 (ensuring that the Cu was completely in contact with the solution), and left to stand until the Cu was completely dissolved to obtain a "PMMA-graphene" transparent film structure; the film was sequentially cleaned with hydrochloric acid solutions with a volume fraction of 10%, 5%, and 2%, respectively, and after each step, the film was left to stand for 30 min and then immersed in ultrapure water for cleaning three times.

[0067] The SiO2 / Si substrate (1 cm x 1 cm) was immersed in an otter solution (30 wt% H2O2 and concentrated H2SO4 at a volume ratio of 3:7) and cleaned by heating at 110°C for 5 h; the substrate was then removed, ultrasonically cleaned with ultrapure water for 10 min, and the cleaning process was repeated four times; the silicon substrate was then ultrasonically cleaned in acetone, ethanol, and ultrapure water for 10 min each, and then dried with nitrogen; the "PMMA-graphene" film was taken out of the water using the silicon substrate (ensuring that the film was flat), and then left to dry naturally in a fume hood for 12 h; the dried "PMMA-graphene-SiO2 / Si" sheet was placed in a tube furnace and annealed at 400°C for 3 min under an atmospheric atmosphere to remove the PMMA layer, thereby obtaining a graphene film that was covered on the silicon substrate.

[0068] II. Preparation of a device basic configuration with graphene-based ends, the process being as follows: (i) Pretreatment and marking pattern: the previously obtained "graphene-SiO2 / Si" substrate was rinsed and blown with acetone, and after drying, a marking area was defined by first photolithography, and then a 600 nm thick gold (Au) layer was deposited by thermal evaporation to form a marking pattern; (ii) Graphene strip patterning: second photolithography was performed to protect the central graphene strip area that needed to be retained on the substrate, and the graphene area that was not protected by the photoresist was oxidized and etched by oxygen plasma; after etching, the remaining 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; (iii) Anode preparation: third photolithography was performed on the surface of the graphene strip to define an anode electrode pattern; then, a 5 nm thick Cr layer (as an adhesion layer for the metal electrode and graphene) and a 150 nm thick Au layer (with a work function of about 5.1-5.3 eV) were deposited by thermal evaporation; finally, a 10 nm thick SiO2 layer (as an oxidation protection layer for the anode) was deposited by electron beam evaporation; (Four), preparation of cathode: fourth photolithography is performed on the surface of the graphene strip (outside the corresponding area of the anode) to define the cathode electrode pattern; then 20 nm thick Ca (work function about 2.9 eV) and 100 nm thick Al (for protecting the internal Ca layer from oxidation) are sequentially deposited by thermal evaporation process; finally, 10 nm thick SiO2 (as an anti-oxidation protective layer for the cathode) is evaporated by electron beam evaporation process, thereby obtaining a basic configuration of the device with graphene-based ends.

[0069] III. Preparation of nanoscale graphene point contact electrode array: Prepared according to the method disclosed in the reference, the process is as follows: (I) Preparation of mask layer: PMMA is used as a mask layer and spin-coated on the surface of the device prepared above, and baked on a 180°C heating platform for 2 min to volatilize and solidify the solvent; (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); (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; (IV) Etching and monitoring: the developed device is subjected to oxygen plasma etching, and the current between the anode and the 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 carboxyl groups; (V) Removal of mask: the etched device is immersed in acetone for more than 12 h to remove the residual PMMA mask layer on the surface; (VI) A bias voltage is applied to the two ends of the clean device by a probe station, and the Joule heating effect is used to further cut off the graphene electrode pairs that have not been completely etched until the monitored current is 0, thereby obtaining a nanoscale graphene point contact electrode array.

[0070] The aforementioned references are as follows: 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.

[0071] IV. Connecting the functional molecule to the graphene electrode pair: After the nanoscale graphene point contact electrode array prepared in the foregoing preparation was cleaned with acetone, it was placed in a 60°C oven and dried for 30 min; then 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) were sequentially added to a reaction container, and the reaction was allowed to stand for 48 h under a nitrogen atmosphere; after the reaction was completed, the device surface was sequentially rinsed with acetone and deionized water, and the device was electrically characterized by a semiconductor parameter analyzer; the current value obtained by the test was compared with the fA-level background current of the device without the functional molecule. The results are shown in Figure 2 When the device current was increased to the nA level and above, it was proved that the functional molecule B I was successfully connected between the graphene electrode pair, i.e., an organic monomolecular light-emitting device based on platinum porphyrin dimers was obtained; it can also be seen from the figure that the I-V curve showed clear asymmetry and rectification characteristics: the current sharply rose with the increase of voltage under forward bias.

[0072] The organic monomolecular light-emitting device based on platinum porphyrin dimers was subjected to electroluminescence testing, and the process was as follows: while a forward direct current bias was applied to the monomolecular light-emitting device, a confocal microscope objective was used to collect the extremely weak light signal emitted from the nanogap region, and a single-photon detector coupled to a spectrometer was used for signal detection, so as to obtain the EL spectrum of the device and the PL spectrum of the functional molecule B I. The results are shown in Figure 3 It can be seen from the figure that the spectral peak positions and peak shape heights of the two were consistent, which indicated that the light emission source of the device after being powered on was the functional molecule B I, and the interference of background stray light or other substance light emission was excluded.

[0073] Finally, it should be noted that the above examples are only used to illustrate the technical solutions of the present application, and 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 described 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 functional molecule is any one of the following structural formulae: 、 ； wherein R1and R3are each independently selected from or -OCH3; R2 and R4 are each independently selected from -OH or NH2.

2. The platinum porphyrin dimer-based organic monomolecular light-emitting device according to claim 1, wherein The functional molecule with the A structural formula is synthesized according to the following route: wherein Ar is Zn(OAc)2 is zinc acetate, AgPF6 is silver hexafluorophosphate, NBS is N-bromosuccinimide, 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 functional molecule with the B structural formula is synthesized according to the following route: 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.

4. 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.

5. 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.

6. 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 insulating layer mainly contains silicon dioxide.

7. The organic single-molecule light-emitting device based on platinum porphyrin dimer as described in claim 1, characterized in that, 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 sequentially evaporated on the graphene electrode, and the cathode electrode is composed of Ca and Al which are sequentially evaporated on the graphene electrode.

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

9. 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 8, 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 anaerobic 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.

10. The method for preparing an organic single-molecule light-emitting device based on platinum porphyrin dimer as described in claim 9, 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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