Polyoxometallate-initiated polymerized'polyacid-polymer 'composite material and application thereof in photoelectric device

Abstract

The invention discloses a polyoxometallate-initiated small molecule polymerized polyacid-polymer composite material and an application of the polyacid-polymer composite material in a photoelectric device. The composite material is a polyacid-polymer as shown in a formula II and a formula III. The polyacid oxidant is mainly divided into six structures, namely a Keggin type structure, a Daswon type structure, a Lindeqvist type structure, a Waugh type structure, an Anderson type structure and a Silverton type structure, and the formulas I-1 to I-5 are polymerized small molecular monomers. The polyacid-polymer material has high doping concentration, so that the polyacid-polymer material has high conductivity when being applied to photoelectric devices, solution preparation can be realized, the synthesis cost is low, and the polyacid-polymer material has good application potential in large-scale commercial production. The'polyacid-polymer 'composite material provided by the invention is not only an excellent charge transport material, but also a material with neutral pH, so that the stability of a photoelectric device is improved to a great extent, and relatively high photoelectric conversion efficiency is realized.

Description

Technical Field

[0001] The present invention relates to a "polyoxometalate-polymer" composite material initiated by polyoxometalate polymerization and its application in optoelectronic devices, belonging to the field of organic optoelectronics. Background Art

[0002] Organic optoelectronic devices are a class of optoelectronic devices based on organic semiconductor materials, with significant advantages such as light weight, flexibility, and large-area manufacturability. These devices include organic light-emitting diodes (OLEDs), organic solar cells (OPVs), organic field-effect transistors (OFETs), organic photodetectors (OPDs), etc., and are widely used in fields such as display, lighting, sensing, biomedicine, and energy conversion.

[0003] The research on organic optoelectronic devices began in the 1990s, and with the discovery and application of conductive polymers, this field has developed rapidly. Due to their unique optoelectronic properties and designability, organic materials have gradually become an important part of optoelectronic devices. For example, OLEDs utilize the electroluminescence characteristics of organic materials to achieve high-brightness and low-power consumption display technology; while OPVs achieve efficient optoelectronic conversion through the separation and transport of photo-generated carriers.

[0004] Organic photovoltaic cells have good application prospects due to their advantages such as flexible preparation, low cost, simple preparation process, and easy modification. At present, the efficiency of single-junction OPV cells certified by the National Renewable Energy Laboratory (NREL) in the United States has exceeded 19%, basically meeting the requirements of commercialization for the cells. How to ensure high optoelectronic conversion efficiency while improving the stability of organic photovoltaic cells and achieving large-area processing and preparation has become a key factor for their commercial application. Therefore, the research on improving the efficiency and stability of organic photovoltaic devices has important practical significance.

[0005] Organic photovoltaic cells are composed of a transparent substrate, a bottom electrode, an interface layer, an active layer, an interface layer, and a top electrode from top to bottom, and are divided into forward OPV devices and reverse OPV devices according to the different functions of the electrodes. Forward OPV devices usually use low work function active metals such as aluminum and calcium as the cathode and indium tin oxide as the anode bottom cell, and usually use water-soluble anode interface layer poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS), which has strong acidity and hygroscopicity, will seriously reduce the service life of the device and affect the stability of the device. Reverse devices usually use high work function inert metals such as gold and silver as the top electrode and indium tin oxide as the cathode bottom electrode, and usually use transition metal oxide - MoO3 as the anode interface layer. MoO3 has low conductivity and poor solution processability, and needs to be prepared by high-temperature evaporation, which limits its application in large-area devices.

[0006] It can be seen that the interfacial layer plays a vital role in improving the photoelectric conversion efficiency and device stability of organic solar cells, both in forward and reverse devices. Therefore, there is an urgent need to develop hole transport layer materials that are easy to process, highly stable, have a deep work function, high conductivity, and possess excellent charge transport properties. Summary of the Invention

[0007] The object of the present invention is to provide a "polyacid-polymer" composite material in which polymerization is initiated by a polyoxometalate, which can be used as a hole transport layer of a photoelectric functional device; due to the strong oxidizing property of the polyoxometalate, electrons are induced to transfer from the polymer to the polyacid molecules, forming an n-type doped polyoxometalate and a p-type doped polymer; the composite material has a high doping density, so the conductivity and work function of the photovoltaic device made of the hole transport layer are greatly improved, and the pH value of the composite material such as Formula IV is neutral; the organic photovoltaic cell based on the "polyacid-polymer" composite material in which polymerization is initiated by a polyoxometalate can achieve a high photoelectric conversion efficiency while improving the stability of the device; the "polyacid-polymer" composite material provided by the present invention can also be applied to organic photoelectric devices such as organic light emitting diodes and organic effect transistors.

[0008] The present invention first provides a "polyacid-polymer" composite material, which is a product of the polymerization of polyacid monomers shown in Formula II and Formula III;

[0009] In formula II and formula III, Ar1 and Ar2 are the same or different and are independently selected from unsubstituted and substituted phenyl, cycloethyl and thienyl groups, m is a natural number between 1 and 20, and n is a natural number between 1 and 20;

[0010] The counter cations in formula IV include Na+, NH4+, Li+, Cs+, K+, etc.

[0011]

[0012] Oxidants that initiate polymerization reactions—polyoxometalates, such as Figure 11 As shown in formulas I-1 to I-6, the polymerized small molecule monomers include phenols, tyrosine, 3,4-ethylenedioxythiophene, dopamine and tannic acid (as shown in formulas I-1 to I-5);

[0013]

[0014] The "polyacid-polymer" composite materials represented by Formula II-1, Formula II-2, Formula III-1 and Formula III-2 can be prepared according to the following method:

[0015] 1) One of the polyoxometalates reacts with at least one of the compounds represented by formulas I-1 to I-5 to obtain a compound represented by formula II-1 or II-2;

[0016] 2): The compound represented by Formula II-1 or Formula II-2 further reacts to obtain the compound represented by Formula III-1 or Formula III-2; wherein:

[0017] The reaction in Step 1) is carried out in a solvent, and the reaction is carried out at room temperature for 24 to 72 hours. After filtering the reaction solution, the filtrate is retained and washed with petroleum ether and dichloromethane, and after drying, a solid product of Formula II-1 or Formula II-2 is obtained;

[0018] The above-mentioned solvent can be one of deionized water, ethanol, methanol, ether, etc.

[0019] The reaction in Step 2) is carried out in ammonia water, and after drying, a solid product of Formula III-1 or Formula III-2 is obtained.

[0020] In the above-mentioned "polyoxometalate-polymer" composite material, the molar ratio of one of the polyoxometalates to Formula I-1 to I-5 is 1:0.5 to 1:30, preferably 1:2.

[0021] The reagents in the reaction conditions of Step 2 include: NH3●H2O, Cs2CO3, K2CO3, NaHCO3, Li2CO3, etc.

[0022] The "polyoxometalate-polymer" composite material provided by the present invention can be used as a hole transport layer in the following organic optoelectronic functional devices:

[0023] Organic photovoltaic devices, organic effect transistors, and organic light-emitting diodes;

[0024] Taking the organic photovoltaic cell as an example, from top to bottom, it is an anode substrate, a hole transport layer, an active layer, an electron transport layer, and a metal cathode; the hole transport layer is a single-layer, double-layer, or multi-layer structure, and at least one layer is an interface layer made of the "polyoxometalate-polymer" composite material;

[0025] The "polyoxometalate-polymer" composite material exhibits electrical properties such as high conductivity and high work function.

[0026] The thickness of the hole transport layer is 5 to 200 nm, preferably 10 to 50 nm, more preferably 15 to 30 nm;

[0027] In the organic photovoltaic cell to which the "polyoxometalate-polymer" composite material is applicable, that is, the anode substrate, the active layer, the cathode interface layer (electron transport layer), and the cathode can all be selected according to the organic solar cells in the prior art, such as:

[0028] The substrate can be an ITO conductive substrate, an FTO conductive substrate, a carbon nanotube conductive substrate, a silver nanowire conductive substrate, a PEDOT conductive substrate, or a graphene conductive substrate;

[0029] The material of the active layer can be PBDB-T-F:L8-BO, PBDB-T-F:BTP-eC9, PBDB-T-F:Y6, PBDB-T-F:IT-4F, etc.;

[0030] The cathode interface layer material can be PDINN, PDINO, PFN-Br, LiF, etc.;

[0031] The cathode material can be gold, silver, aluminum, copper, platinum, molybdenum, nickel, zinc, titanium, iron, calcium, etc.;

[0032] The present invention also provides a preparation method of the organic photovoltaic cell, including the following steps:

[0033] S1. Clean the anode and perform surface treatment on the anode substrate;

[0034] S2. Prepare the hole transport layer on the anode substrate processed in step S1;

[0035] S3. Sequentially prepare the active layer, the electron transport layer and the cathode on the hole transport layer, and then the organic photovoltaic cell is obtained;

[0036] In the above preparation method, in step S1, the cleaning steps are as follows:

[0037] Ultrasonically clean with dishwashing liquid, deionized water, acetone, and absolute ethanol in sequence for 10 - 30 minutes; and dry the substrate with a nitrogen gun or dry it in a vacuum oven at 70 - 90 °C;

[0038] The surface treatment is ultraviolet ozone surface treatment for 10 - 30 minutes.

[0039] In the above preparation method, in step S2, the hole transport layer is prepared according to the following method:

[0040] Prepare a film of the solution on the anode substrate, and then perform thermal annealing to obtain it;

[0041] The solution is a "polyacid-polymer" composite material such as formula II or formula III, dissolved in a solvent;

[0042] The solvent of the solution is at least one of deionized water, ethanol, methanol, chlorobenzene, chloroform, dimethyl sulfoxide, tetrafluorobenzoic acid, and ethyl acetate.

[0043] In the solution, the concentrations of formula II-1, II-2, formula III-1 and formula III-2 are all 0.5 - 30 mg / mL, preferably 1 - 10 mg / mL, and more preferably 4 mg / mL;

[0044] The method for preparing into a thin film is as follows: Place the anode substrate in a spin coater, spin coat the above solution on the anode substrate at a rotation speed of 2000 - 5000 rpm / min for 20 seconds to 2 minutes.

[0045] The thermal annealing temperature is 100 - 250 °C and the time is 10 - 80 minutes.

[0046] The "polyoxometalate - polymer" composite material provided by the present invention, as a hole transport layer of an organic photovoltaic device, has a high conductivity and work function, which is beneficial to achieving high performance of the device.

[0047] Compared with the prior art, the present invention has the following beneficial effects:

[0048] (1) If the molar ratio of one of the polyoxometalates to the small molecule monomers of formulas I - 1 to I - 5 is 1:0.5 - 1:30, preferably 1:2. During the polymerization reaction, the strong oxidizing property of the polyoxometalate molecules induces electrons to move from the polymer to the polyoxometalate molecules, forming n - type doped polyoxometalates and p - type doped polymers, making the composite material have a high doping density, thereby improving the conductivity and work function of the material;

[0049] (2) For the "polyoxometalate - polymer" composite material with a neutral pH as shown in formulas III - 1 and III - 2, compared with the traditional hole transport layer, the neutral interfacial material can protect the electrode from erosion and improve the storage stability of the overall device. Description of the Drawings

[0050] Figure 1 1H NMR spectrum of the "polyoxometalate - polymer" composite material (formulas II - 1 and III - 1) prepared in Example 1.

[0051] Figure 2 Thin - film ultraviolet - visible absorption spectrum of the "polyoxometalate - polymer" composite material (formulas II - 1 and III - 1) prepared in Example 1.

[0052] Figure 3 Electron paramagnetic resonance spectrum of the "polyoxometalate - polymer" composite material (formulas II - 1 and III - 1) prepared in Example 1.

[0053] Figure 4 Ultraviolet photoelectron spectrum of the "polyoxometalate - polymer" composite material (formulas II - 1 and III - 1) prepared in Example 1.

[0054] Figure 5 Current - voltage (I - V curve) of the device with the structure of ITO / HTL / Al prepared based on the "polyoxometalate - polymer" composite material (formulas II - 1 and III - 1) in Example 1.

[0055] Figure 6Photocurrent density-voltage (J-V) curve of the organic photovoltaic cell with the structure of ITO / HTL / PBDB-T-F:BTP-eC9 / Ag prepared from the "polyoxometalate-polymer" composite materials (Formula II-1 and Formula III-1) prepared in Example 1.

[0056] Figure 7 External quantum efficiency (EQE) curve of the organic photovoltaic cell with the structure of ITO / HTL / PBDB-T-F:BTP-eC9 / Ag prepared from the "polyoxometalate-polymer" composite materials (Formula II-1 and Formula III-1) prepared in Example 1.

[0057] Figure 8 Test photos of the interfacial water contact angle of the "polyoxometalate-polymer" composite materials (Formula II-1 and Formula III-1) prepared in Example 1.

[0058] Figure 9 Height image of the interfacial atomic force microscope of the "polyoxometalate-polymer" composite materials (Formula II-1 and Formula III-1) prepared in Example 1.

[0059] Figure 10 Curve of the change of the energy conversion efficiency over time of the organic photovoltaic cell with the structure of ITO / HTL / PBDB-T-F:BTP-eC9 / Ag prepared from the "polyoxometalate-polymer" composite materials (Formula II-1 and Formula III-1) prepared in Example 1 during storage in N2.

[0060] Figure 11 Synthesis route diagram of Formula II.

[0061] Figure 12 Synthesis route diagram of Formula III. Detailed implementation manners

[0062] Unless otherwise specified, the experimental methods used in the following examples are all conventional methods.

[0063] Unless otherwise specified, the materials, reagents, etc. used in the following examples can all be obtained from commercial sources.

[0064] Example 1: Synthesis of the "polyoxometalate-polymer" composite materials (Formula II-1 and Formula III-1) by the polymerization of dopamine monomers initiated by phosphomolybdic acid

[0065] Synthesis of the "polyoxometalate-polymer" composite material (Formula II-1): 1.825 g (1 mmol) of phosphomolybdic acid (H3PMo 12 O 40) Dissolve it in 120 ml of deionized water, then add 0.379 g (2 mmol) of dopamine hydrochloride monomer, stir at room temperature for 48 h, filter the mixed solution and retain the filtrate. After evaporating the deionized water in the filtrate with a rotary evaporator, the product is washed with petroleum ether and dichloromethane and dried to obtain a blue-black solid powder (Formula II-1).

[0066]

[0067] Synthesis of the "polyoxometalate-polymer" composite material (Formula III-1): Add excessive ammonia water to the filtrate obtained in Formula III. After evaporating the deionized water in the solution with a rotary evaporator, the product is washed with petroleum ether and dichloromethane and dried to obtain a black-green solid powder (Formula III-1).

[0068]

[0069] Characterization of the 1H NMR spectrum of the product obtained by the polymerization of dopamine monomer initiated by polyoxometalate (Formula II-1 and Formula III-1). The spectrum is as Figure 1 shown.

[0070] Example 2: Copolymerization of dopamine monomer and 3,4-ethylenedioxythiophene (EDOT) initiated by phosphomolybdic acid to form the "polyoxometalate-polymer" composite material (Formula II-2 and Formula III-2) synthesis

[0071] Synthesis of the "polyoxometalate-polymer" composite material (Formula II-2): Dissolve 1.825 g (1 mmol) of phosphomolybdic acid (H3PMo 12 O 40 ) in 120 ml of deionized water, then add 0.095 g (0.5 mmol) of dopamine hydrochloride monomer and 0.213 g (1.5 mmol) of 3,4-ethylenedioxythiophene (EDOT), stir at room temperature for 48 h, filter the mixed solution and retain the filtrate. Evaporate the deionized water in the filtrate with a rotary evaporator. The product is washed with petroleum ether and dichloromethane and dried to obtain a blue-black solid powder (Formula II-2).

[0072]

[0073] Synthesis of the "polyoxometalate-polymer" composite material (Formula III-2): Add excessive ammonia water to the filtrate obtained in Formula II-2. Evaporate the deionized water in the solution with a rotary evaporator. The product is washed with petroleum ether and dichloromethane and dried to obtain a black-green solid powder (Formula III-2).

[0074]

[0075] Measurement of the ultraviolet-visible absorption spectrum of the "polyoxometalate-polymer" composite materials (Formula II-1 and Formula III-1) in Example 3 and Example 1;

[0076] The composite materials of Formula II-1 and Formula III-1 prepared in Example 1 were dissolved in deionized water, and a solid film was prepared by spin-coating on a quartz wafer treated with ultraviolet ozone. Its absorption was tested with an ultraviolet-visible absorption spectrometer.

[0077] From Figure 2 It can be seen that the absorption of the "polyoxometalate-polymer" composite material (Formula II-1) between 280 nm and 400 nm is due to the charge transfer between the bridging oxygen atoms and molybdenum ions and the conjugated Π-Π transition in the polymer. The broad absorption in the long wavelength band of 750 nm to 950 nm is due to the inter-valence charge transfer of molybdenum ions. Thus, it can be proved that while polymerization occurs, a redox reaction occurs, forming an "inter-doped" "polyoxometalate-polymer" composite material.

[0078] Example 4, Electron Paramagnetic Resonance Characterization of "Polyoxometalate-Polymer" Composite Materials

[0079] The solid powder of the "polyoxometalate-polymer" composite material (Formula II-1 and Formula III-1) was loaded into a paramagnetic tube for EPR testing. The test results are as Figure 3 shown;

[0080] It can be seen that the Formula II-1 material shows a strong electron paramagnetic resonance signal at 3500. The EPR signal of the Formula III-1 material at 3500 is significantly stronger than that of Formula II-1. Formula II-1 shows a relatively broad spectral peak at 3500 - 4000, which is due to the reduction of molybdenum ions. The electron paramagnetic resonance results verify the conclusion of the ultraviolet-visible absorption spectrum, that is, a redox reaction occurs during the polymerization process, forming an "inter-doped" effect and forming a "polyoxometalate-polymer" composite material with a high doping density.

[0081] Example 5, Preparation of the Interface Layer of the "Polyoxometalate-Polymer" Composite Material and Ultraviolet Photoelectron Spectroscopy Characterization

[0082] The composite materials of (Formula II-1 and Formula III-1) prepared in Example 1 were dissolved in deionized water to prepare a 4 mg / ml solution, which was spin-coated on indium tin oxide glass treated with ultraviolet ozone and made into an interface layer after thermal annealing. The work functions of each material were obtained through ultraviolet photoelectron spectroscopy testing as Figure 4 shown.

[0083] It can be seen that the work functions of the "polyoxometalate-polymer" composite films of Formula II-1 and Formula III-1 are 5.08 eV and 5.11 eV respectively. For a hole transport layer, a higher work function means that better interfacial contact can be formed between indium tin oxide and the active layer donor, reducing the potential barrier for hole transport, thereby reducing the energy loss during the operation of the device.

[0084] Example 6. Current-voltage (I-V curve) of a device with the structure of ITO / HTL / Al prepared based on the "polyoxometalate-polymer" composite materials (Formula II-1 and Formula III-1)

[0085] Dissolve the composite materials (Formula II-1 and Formula III-1) prepared in Example 1 in deionized water to prepare a solution with a concentration of 10 mg / ml. Spin-coat the solution on the surface of indium tin oxide glass treated with ultraviolet ozone at a rotation speed of 1000 rpm / min, and anneal at 100 °C for 10 minutes. Then, place the sample in a vacuum evaporation chamber to evacuate. At a vacuum degree of about 2E-4 Pa, evaporate about 100 nm of aluminum as the cathode top electrode. Finally, under the irradiation of a xenon lamp-simulated solar light source (AM1.5G, 100 mW / cm 2 ), measure the current-voltage (I-V) curve. Calculate the conductivity of each material from the slope of the obtained curve (as Figure 5 shown)

[0086] It can be seen that the composite materials of Formula II-1 and Formula III-1 have relatively high conductivity, and the values both reach 10 -3 orders of magnitude, verifying the test results of electron paramagnetic resonance.

[0087] Example 7. Preparation of an organic photovoltaic cell based on the interfacial layer of the "polyoxometalate-polymer" composite materials (Formula II-1 and Formula III-1)

[0088] Dissolve the composite materials of Formula II-1 and Formula III-1 prepared in Example 1 in deionized water to prepare a solution with a concentration of 4 mg / ml. Stir at room temperature for 15 minutes. Then, spin-coat the above solution on indium tin oxide conductive glass treated with ultraviolet ozone surface treatment at a rotation speed of 3000 rpm / min to prepare an interfacial layer film with a thickness of about 15 nm, and then anneal at 150 °C for 10 minutes.

[0089] Then, the PBDB-TF:BTP-eC9 blend solution (1:1.2, chloroform, polymer 7mg / ml, and adding 0.5% volume fraction of DIO) was spin-coated on the aforementioned interface layer film at a speed of 3500rpm / min for 40 seconds to prepare a 110nm active layer film, and annealed at 100℃ for 10 minutes. After that, PDINN was dissolved in methanol solution at a concentration of 1mg / ml and spin-coated on the active layer at a speed of 3000rpm / min for 30 seconds. The sample was then placed in a vacuum evaporation chamber and evacuated. At a vacuum degree of about 2E10-4Pa, about 100nm of silver was evaporated as the cathode top electrode, and finally the sample was exposed to a xenon lamp simulated sunlight light source (AM1.5G, 100mW / cm 2 ) is irradiated, and the photocurrent density-voltage (JV) curve is tested. From the JV curve, the open circuit voltage (V oc ), short-circuit current density (J SC ), fill factor (FF), and photoelectric conversion efficiency (PCE) and other parameters.

[0090] Based on the JV curves of formula II-1 and formula III-1, Figure 6 As shown. Among them, the open circuit voltage V of the organic photovoltaic cell device based on the interface layer of formula II-1 oc =0.8369V, short-circuit current density J SC =27.24mA / cm 2 , fill factor FF = 74.62%, photoelectric conversion efficiency = 17.02%; the open circuit voltage V of the organic photovoltaic cell device based on the interface layer of formula Ⅲ-1 oc =0.8374V, short-circuit current density J SC =27.41mA / cm 2 , filling factor FF = 75.43%, photoelectric conversion efficiency = 17.32%;.

[0091] Example 8: External quantum conversion efficiency of organic photovoltaic cells prepared based on the interface layer of the "polyacid-polymer" composite material (Formula II-1 and Formula III-1)

[0092] The organic photovoltaic cell prepared in Example 7 was tested using an external quantum efficiency tester to determine its external quantum efficiency curve. The results are as follows: Figure 7 As shown, it can be seen that the composite material based on "polyacid-polymer" (

[0093] The external quantum efficiency of the organic photovoltaic cell prepared with the interface layer of formula II-1 and formula III-1 has a high value in the entire spectral range.

[0094] Example 9: Interface layer antenna test based on "polyacid-polymer" composite materials (Formula II-1 and Formula III-1)

[0095] Prepare the "polyoxometalate-polymer" composite material interface layer according to the above method and test its contact angle with water. The results are as Figure 8 shown.

[0096] It can be seen that the contact angle of the "polyoxometalate-polymer" composite material interface layer with water is larger than that of the traditional interface layer, which means that the solar cell device prepared therefrom has greater advantages in terms of water resistance stability.

[0097] Example 10. Atomic force microscope test of the interface layer material based on the "polyoxometalate-polymer" composite material (Formula II-1 and Formula III-1)

[0098] Prepare the "polyoxometalate-polymer" composite material interface layer according to the above method, and use an atomic force microscope to test its surface roughness. The results are as Figure 9 shown.

[0099] It can be seen that the surface roughness of the "polyoxometalate-polymer" composite material interface layer is small, which means that it can form a smooth and uniform thin film.

[0100] Example 11. Preparation method of the organic photovoltaic cell prepared according to Example 7 for device storage stability test

[0101] Place the organic photovoltaic device made of the "polyoxometalate-polymer" composite material (Formula II-1 and Formula III-1) in a glove box filled with nitrogen for 600 hours. The results of the change in its photoelectric conversion efficiency over time are as Figure 10 shown.

[0102] It can be seen that after placing in the glove box for 600 hours, the device with the pH-neutral Formula III-1 interface layer material can still maintain 86.4% of its initial efficiency, which is higher than that of the acidic II-1 interface layer material (81.0%). It can be clearly seen that the pH-neutral interface layer material can significantly improve the stability of the photovoltaic device.

[0103] The above embodiments are only several preferred embodiments of the present invention, but the protection scope of the present invention is not limited thereto. It should be noted that for any person skilled in the art, without departing from the concept of the present invention in this technical field, any equivalent replacement or change made according to the technical solution and inventive concept of the present invention should be covered within the protection scope of the present invention.

Claims

1. A "polyoxometalate-polymer" composite material initiated by polyoxometalate polymerization, characterized in that: The composite material described above is a "polyoxometalate-polymer" represented by Formula II and Formula III; the polyoxometalate structures that initiate the polymerization of the "polyoxometalate-polymer" represented by Formula II and Formula III are mainly divided into Keggin type, Daswon type, Lindqvist type, Waugh type, Anderson type and Silverton type structures; Formulae I-1 to I-5 are polymerized small molecule monomers; the small molecule monomers include any several of phenols, tyrosine, 3,4-ethylenedioxythiophene, dopamine and tannic acid, and the structures of the small molecule monomers are as shown in Formulae I-1 to I-5: The molar ratio of the above-mentioned polyoxometalate oxidant to the small molecule monomers shown in I-1 to I-5 is 1:0.5 to 1:

30.

2. A "polyoxometalate-polymer" composite material polymerized by a polyoxometalate according to claim 1, characterized in that: The specific structures of the products of the polymerization reactions represented by Formula II and Formula III are as follows: In Formulae II and III, Ar1 and Ar2 are the same or different and are independently selected from unsubstituted and substituted phenyl, cyclohexyl and thiophenyl groups, j is a natural number between 1 and 20, k is a natural number between 1 and 20; x is a natural number between 1 and 10; m is a natural number between 1 and 20; m is a natural number between y and 62; y is a natural number between 1 and 10; X is a heteroatom (central atom); M is a ligand atom (polyatom); the M and X atoms are coordinated and bridged by oxygen atoms in a certain structure by a high oxidation state of a pre-transition metal. In formula Ⅲ, the counter cations include Na + , NH4 + , Li + , Cs + , K + Any several of them.

3. Use of the "polyoxometalate-polymer" composite material as claimed in claim 1 in the preparation of an organic optoelectronic functional device, characterized in that: The "polyoxometalate-polymer" composite material is used to prepare the hole transport layer of the organic optoelectronic functional material.

4. The application according to claim 3, wherein: The optoelectronic functional device is mainly an organic photovoltaic cell.

5. The application according to claim 4, characterized in that: For the organic photovoltaic cell, from bottom to top, there are an anode substrate, a hole transport layer, an active layer, an electron transport layer and a metal cathode in sequence: the hole transport layer is a single-layer or multi-layer structure, and at least one layer is the "polyoxometalate-polymer" composite material described in Claim 1.

6. The application according to claim 4, wherein: The thickness of the hole transport layer is 5 to 100 nm.

7. The application according to claim 4, wherein: The preparation method of the organic photovoltaic cell includes the following steps: S1. Clean the anode substrate and perform surface treatment on the anode substrate; S2. Prepare the hole transport layer on the anode substrate treated in step S1; S3. Prepare the active layer, the electron transport layer and the cathode on the hole transport layer in sequence, and then the organic photovoltaic cell is obtained.

8. The application according to claim 7, wherein; In step S2, the hole transport layer is prepared according to the following steps: Hole transport layer: The solution is formed into a film on the substrate and then thermally annealed to obtain it; The solution is the "polyoxometalate-polymer" composite material as described in Formulae II and III, dissolved in a solvent.

9. The application according to claim 8, wherein: In the solution, the concentrations of Formulae II and III are both 0.5 to 30 mg / mL; the solvent of the solution is at least one of deionized water, ethanol, methanol, chlorobenzene, chloroform, dimethyl sulfoxide, tetrafluorobenzoic acid, and ethyl acetate.

10. The application according to claim 8, wherein: The method for forming the film is: place the device in a spin coater, spin coat the solution on the anode substrate, the rotation speed is 2000 to 5000 rpm / min, and the time is 20 seconds to 2 minutes; the thermal annealing temperature is 100 to 250 °C, and the time is 10 to 80 minutes.

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