Zinc oxide@carbon core-shell nanoparticles and their preparation and application

Abstract

The present invention relates to zinc oxide-on-carbon core-shell nanoparticles. These particles are prepared by adding a benzene derivative or pyridine derivative substituted with at least one amino and / or carboxyl group, or a small silane molecule capable of undergoing a coupling reaction with zinc oxide, as a carbon source to a nano-zinc oxide methanol solution, followed by a solvothermal reaction at 150-200°C. The zinc oxide-on-carbon core-shell nanoparticles are coated with a nanocarbon material to suppress surface defects in zinc oxide. When used in the electron transport layer of organic solar cells, they can inhibit the photocatalytic reaction between zinc oxide and non-fullerene materials, reduce the number of oxygen adsorption sites on zinc oxide, and minimize the occurrence of the "light bathing" phenomenon, thereby improving the device's air and UV stability.

Description

Technical Field

[0001] The present invention belongs to the technical field of organic solar cells and relates to cathode interface layer materials for organic solar cells, in particular to a zinc oxide@carbon core-shell nanoparticle composite nanomaterial that can be used as a cathode interface layer material, and a method for preparing the composite nanomaterial. Background Art

[0002] In recent years, organic photovoltaic (OPV) has achieved rapid development due to its advantages such as light weight, roll-to-roll printing and environmental protection. With the development of non-fullerene small molecule acceptor materials in recent years, the power conversion efficiency (PCE) of organic solar cells has also made great progress.

[0003] For example, the research group of Hou Jianhui, a researcher at the Institute of Chemistry, Chinese Academy of Sciences (Single-Junction Organic Photovoltaic Cell with 19% Efficiency. Adv. Mater. , 2021, 33, 2102420.) explored a new donor-acceptor combination PBQx-TF and eC9-2Cl, and used another acceptor F-BTA3 as the third component to further construct a ternary OPV cell device, achieving a PCE of 19% for organic solar cells.

[0004] In practical applications, organic solar cells require not only a high PCE but also a sufficiently long working life. Therefore, battery stability becomes a key issue that needs to be addressed.

[0005] In organic solar cells, an interface material is typically inserted between the active layer and the electrode as a buffer layer. This layer, on the one hand, separates charges, facilitates charge extraction and collection, and improves PCE; on the other hand, it isolates the electrode from direct contact with the active layer material, improving cell stability. Therefore, the performance of the interface material plays a crucial role in improving the device's photoelectric conversion performance and stability.

[0006] While zinc oxide nanoparticles are the most commonly used electron transport layer (ETL) in organic solar cells, they are also well-known as photocatalysts. Therefore, under sunlight, zinc oxide and non-fullerene acceptors inevitably undergo photocatalytic degradation reactions, destroying the non-fullerene acceptor structure, reducing the long-term stability of organic solar cells, and shortening their service life. Furthermore, zinc oxide's surface contains a large number of hydroxyl groups, which absorb oxygen from the air, causing the well-known "light bathing" phenomenon and promoting the aforementioned photocatalytic degradation reaction.

[0007] Carbon nanomaterials offer advantages such as low preparation cost, tunable surface states, and non-toxicity. Their exceptional optoelectronic properties and solution processability, in particular, make them promising for applications in organic solar cells. Numerous reports have been published on the application of various carbon nanomaterials in organic solar cells, including carbon nanotubes, graphene, and carbon quantum dots (CDs), all of which have been successfully incorporated into cells and demonstrated improved device performance.

[0008] Given the excellent properties of carbon nanomaterials, researchers have explored using them to modify nano-zinc oxide. For example, Wang et al. modified zinc oxide with N and S co-doped CDs, achieving the goal of suppressing the "light bathing" phenomenon of zinc oxide (ACS ApplMater Inter. 2019, 11, 2243-2253). Lin et al. modified zinc oxide with amino-containing CDs. The results confirmed that CD modification can reduce the work function of zinc oxide, allowing for good ohmic contact between zinc oxide and the cathode and active layer, reducing series resistance and increasing battery efficiency (Nano Energy. 2016, 26, 216-223).

[0009] However, most carbon nanomaterials are used to modify zinc oxide by simple physical blending. This method can only partially improve the surface defects of zinc oxide, but cannot inhibit the internal defects of zinc oxide. The modification effect is limited, and the composite interface layer obtained by this physical modification has poor stability. Summary of the Invention

[0010] The purpose of the present invention is to provide a zinc oxide @ carbon core-shell nanoparticles, which suppress the surface defects of zinc oxide by coating with nanocarbon materials, so that it has the ability to absorb ultraviolet light while reducing the photocatalytic reaction.

[0011] Another object of the present invention is to provide the application of the zinc oxide@carbon core-shell nanoparticles as an electron transport layer in organic solar cells, inhibit the photocatalytic reaction between zinc oxide and non-fullerene materials, reduce the oxygen adsorption sites of zinc oxide, reduce the probability of the "light bath" phenomenon, and improve the air and ultraviolet stability of the device.

[0012] The zinc oxide@carbon core-shell nanoparticles of the present invention are made of any of the following organic small molecule carbon source materials:

[0013] a) a benzene derivative or pyridine derivative substituted with at least one amino group and / or carboxyl group;

[0014] b) small silane molecules that can undergo coupling reaction with zinc oxide;

[0015] The product is obtained by adding it to a nano zinc oxide methanol solution and performing a solvent thermal reaction at 150-200°C.

[0016] The core of the present invention's technical solution is to select a suitable organic small molecule carbon source material to coat zinc oxide to form zinc oxide@carbon core-shell nanoparticles. The specific principles for selecting the carbon source material are: 1) it cannot reduce the conductivity of the zinc oxide nanoparticles, that is, the carbon source material molecules need to have excellent conductivity, and therefore, their structure needs to have a high degree of conjugation; 2) it can form chemical bonds with the surface of the zinc oxide nanoparticles, that is, the carbon source material molecules can react with groups such as hydroxyl groups on the zinc oxide surface to form strong chemical bonds, ensuring the chemical stability of the core-shell particles; 3) the carbon source material is widely available, low-cost, and easy to obtain.

[0017] Since carboxyl and amino groups are easy to react with oxygen-containing functional groups on the surface of zinc oxide, and amino groups are beneficial to improving the electron mobility of zinc oxide, the present invention preferably uses organic small molecules with carboxyl and / or amino groups as carbon source materials.

[0018] Specifically, the at least one amino- and / or carboxyl-substituted benzene derivative or pyridine derivative can be any organic small molecule having both a benzene ring or pyridine structure and an amino- and / or carboxyl substituent. The amino- and / or carboxyl substituent can be directly attached to the benzene ring or pyridine ring, or attached to other substituents attached to the benzene ring or pyridine ring. Examples include, but are not limited to, o-, m-, and p-phenylenediamine and their derivatives; o-, m-, and terephthalic acid and their derivatives; trimesic acid; 3-aminopyridine-2-carboxylic acid; and 4-aminopyridine-3-carboxylic acid.

[0019] Specifically, the silane small molecules capable of undergoing coupling reaction with zinc oxide include but are not limited to various types of silane coupling agents such as KH-792 and KH-560.

[0020] The nano zinc oxide is a particle obtained by various conventional nano zinc oxide preparation methods, and the present invention has no particular limitation on its preparation method.

[0021] Preferably, the present invention adopts a typical particle precipitation method (Hybrid Zinc Oxide Conjugated Polymer Bulk Heterojunction Solar Cells. J. Phys. Chem. B 2005, 109, 9505-9516.) Preparation of nano zinc oxide.

[0022] Furthermore, the present invention disperses the nano zinc oxide in anhydrous methanol through strong ultrasonication to obtain a nano zinc oxide methanol solution of a required concentration for use.

[0023] The specific preparation method of the zinc oxide @ carbon core-shell nanoparticles of the present invention is to add the organic small molecule carbon source material to the nano zinc oxide methanol solution according to the mass ratio of the organic small molecule carbon source material to the nano zinc oxide at 0.05 to 1:1, mix evenly, heat to 150 to 200 ° C for solvent thermal reaction, and realize the carbon source molecule coating on the surface of the zinc oxide and carbonizing into a carbon shell through high temperature and high pressure to form a composite material of carbon shell-coated zinc oxide quantum dots.

[0024] Furthermore, the solvent thermal reaction time is not less than 3 hours.

[0025] Furthermore, the present invention preferably washes the prepared zinc oxide@carbon core-shell nanoparticles precipitate with methanol solvent for multiple times and then disperses them in methanol by strong ultrasonication.

[0026] The zinc oxide@carbon core-shell nanoparticles of the present invention can be applied to the preparation of organic solar cells.

[0027] More specifically, the zinc oxide@carbon core-shell nanoparticles of the present invention can be used as an electron transport layer material in the preparation of organic solar cells.

[0028] Using the zinc oxide@carbon core-shell nanoparticles prepared in this invention as the electron transport layer material, an inverted organic solar cell with a specific device structure of ITO / ZnO@C / PM6:Y6 / MoO3 / Al was prepared, and the device efficiency and stability were characterized. The results showed that the carbon source materials selected in this invention can successfully coat the nano-zinc oxide to form a core-shell structure, which can effectively inhibit the photocatalytic reaction between zinc oxide and non-fullerene materials, while also reducing the oxygen adsorption sites of zinc oxide, reducing the probability of "light bathing" phenomenon, and improving the electron transport efficiency of intrinsic zinc oxide, thereby simultaneously improving the efficiency and stability of the final organic solar cell.

[0029] Similarly, the zinc oxide@carbon core-shell nanoparticles of the present invention can also be used in the preparation of organic light-emitting diodes (OLEDs).

[0030] More specifically, the zinc oxide@carbon core-shell nanoparticles of the present invention can be used as a barrier layer material in the preparation of organic light-emitting diodes.

[0031] Given that its core-shell structure can suppress surface defects in zinc oxide and reduce oxygen adsorption sites on the surface of zinc oxide, it can serve as a barrier layer in electronic devices such as OLEDs similar to organic solar cells, and can also improve device stability. The strong emission peak at 420nm can have more luminescent applications.

[0032] As an emerging optoelectronic material, carbon nanomaterials, rich in tunable surface functional groups, impart unique physicochemical properties. Examples include zero-dimensional carbon quantum dots and two-dimensional carbon nanotubes, which have found widespread application in the optoelectronics field. This invention utilizes a green and widely available carbon source to modify zinc oxide, the electron transport layer material in organic solar cells. The preparation method is simple and efficient, making it suitable for large-scale commercial applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 TEM images of ZnO nanoparticles (a) and ZnO@C core-shell nanoparticles prepared in various examples (b-g).

[0034] Figure 2 yes Figure 1 HRTEM images of the nanoparticles.

[0035] Figure 3 yes Figure 1 UV-visible absorption spectra corresponding to each nanoparticle.

[0036] Figure 4 yes Figure 1 Photoluminescence spectra corresponding to each nanoparticle.

[0037] Figure 5 1 is the X-ray diffraction pattern of ZnO nanoparticles and ZnO@C core-shell nanoparticles prepared in Example 3.

[0038] Figure 6 It is the XPS energy spectrum of ZnO nanoparticles and ZnO@C core-shell nanoparticles prepared in Examples 2 to 5.

[0039] Figure 7 It is the UPS energy spectrum of ZnO nanoparticles and ZnO@C core-shell nanoparticles prepared in different embodiments.

[0040] Figure 8 yes Figure 1 The water contact angle and DIM contact angle test results corresponding to each nanoparticle.

[0041] Figure 9 These are the air stability test graphs of organic solar cell devices V0, V2 and V4.

[0042] Figure 10 This is a test chart of the ultraviolet light stability of organic solar cell devices V0 and V2. DETAILED DESCRIPTION

[0043] The following embodiments are only used to more clearly illustrate the technical solutions of the present invention so that those skilled in the art can better understand and utilize the present invention, but are not intended to limit the scope of protection of the present invention.

[0044] The names and abbreviations of the experimental methods, production processes, instruments and equipment involved in the embodiments and comparative examples of the present invention are conventional names in the field and are very clear and unambiguous in the relevant fields of use. Those skilled in the art can understand the conventional process steps and apply the corresponding equipment based on the names and implement them according to conventional conditions or the conditions recommended by the manufacturer.

[0045] The various raw materials or reagents used in the Examples and Comparative Examples of the present invention are not particularly limited in their sources and are all commercially available conventional products and can also be prepared according to conventional methods well known to those skilled in the art.

[0046] The ZnO nanoparticles involved in the following examples are based on the literature Hybrid Zinc Oxide Conjugated Polymer Bulk Heterojunction Solar Cells. J. Phys. Chem. B 2005, 109, 9505-9516., prepared by direct particle precipitation method, and the obtained ZnO nanoparticles were strongly ultrasonically dispersed in anhydrous methanol to prepare nano-ZnO methanol solutions of different concentrations.

[0047] Example 1.

[0048] 10 mg of o-phenylenediamine was weighed and added to 20 mL of a 10 mg / mL nano-ZnO methanol solution, and ultrasonically dispersed for 30 minutes to form a ZnO-o-phenylenediamine mixed solution in which the carbon source material was 5% by weight of nano-ZnO.

[0049] The ZnO o-phenylenediamine mixed solution was placed in a polytetrafluoroethylene sealed container, placed in a matching reactor, and heated to 180° C. in an oven for a solvent thermal reaction for 10 hours.

[0050] After the reaction was completed, the temperature was naturally lowered and cooled, the reaction product was taken out, the supernatant was discarded by centrifugation, and the precipitate was dispersed in solvent methanol by strong ultrasonication to prepare ZnO@C-5 core-shell nanoparticles.

[0051] Example 2.

[0052] Weigh 20 mg of o-phenylenediamine and add it to 20 mL of 10 mg / mL nano-ZnO methanol solution, and ultrasonically disperse it for 30 minutes to form a ZnO-o-phenylenediamine mixed solution in which the carbon source material is 10% by weight of nano-ZnO.

[0053] The ZnO o-phenylenediamine mixed solution was placed in a polytetrafluoroethylene sealed container, placed in a matching reactor, and heated to 180° C. in an oven for a solvent thermal reaction for 10 hours.

[0054] After the reaction was completed, the temperature was naturally lowered and cooled, the reaction product was taken out, the supernatant was discarded by centrifugation, and the precipitate was dispersed in solvent methanol by strong ultrasonication to prepare ZnO@C-10 core-shell nanoparticles.

[0055] Example 3.

[0056] 60 mg of o-phenylenediamine was weighed and added to 20 mL of 10 mg / mL nano-ZnO methanol solution, and ultrasonically dispersed for 30 minutes to form a ZnO-o-phenylenediamine mixed solution in which the carbon source material was 30% by weight of nano-ZnO.

[0057] The ZnO o-phenylenediamine mixed solution was placed in a polytetrafluoroethylene sealed container, placed in a matching reactor, and heated to 180° C. in an oven for a solvent thermal reaction for 10 hours.

[0058] After the reaction was completed, the temperature was naturally lowered and cooled, the reaction product was taken out, the supernatant was discarded by centrifugation, and the precipitate was dispersed in the solvent methanol by strong ultrasonication to prepare ZnO@C-30 core-shell nanoparticles.

[0059] Example 4.

[0060] 100 mg of o-phenylenediamine was weighed and added to 20 mL of a 10 mg / mL nano-ZnO methanol solution, and ultrasonically dispersed for 40 minutes to form a ZnO o-phenylenediamine mixed solution in which the carbon source material was 50% by weight of nano-ZnO.

[0061] The ZnO o-phenylenediamine mixed solution was placed in a polytetrafluoroethylene sealed container, placed in a matching reactor, and heated to 180° C. in an oven for a solvent thermal reaction for 10 hours.

[0062] After the reaction was completed, the temperature was naturally lowered and cooled, the reaction product was taken out, the supernatant was discarded by centrifugation, and the precipitate was dispersed in solvent methanol by strong ultrasonication to prepare ZnO@C-50 core-shell nanoparticles.

[0063] Example 5.

[0064] 160 mg of o-phenylenediamine was weighed and added to 20 mL of a 10 mg / mL nano-ZnO methanol solution, and ultrasonically dispersed for 40 minutes to form a ZnO-o-phenylenediamine mixed solution in which the carbon source material was 80% by mass of nano-ZnO.

[0065] The ZnO o-phenylenediamine mixed solution was placed in a polytetrafluoroethylene sealed container, placed in a matching reactor, and heated to 180° C. in an oven for a solvent thermal reaction for 10 hours.

[0066] After the reaction is completed, the temperature is naturally lowered and cooled, the reaction product is taken out, the supernatant is discarded by centrifugation, and the precipitate is dispersed in solvent methanol by strong ultrasonication to prepare ZnO@C-80 core-shell nanoparticles.

[0067] Example 6.

[0068] 200 mg of o-phenylenediamine was weighed and added to 20 mL of a 10 mg / mL nano-ZnO methanol solution, and ultrasonically dispersed for 40 minutes to form a ZnO o-phenylenediamine mixed solution in which the carbon source material was 100% by mass of nano-ZnO.

[0069] The ZnO o-phenylenediamine mixed solution was placed in a polytetrafluoroethylene sealed container, placed in a matching reactor, and heated to 180° C. in an oven for a solvent thermal reaction for 10 hours.

[0070] After the reaction is completed, the temperature is naturally lowered and cooled, the reaction product is taken out, the supernatant is discarded by centrifugation, and the precipitate is dispersed in solvent methanol by strong ultrasonication to prepare ZnO@C-100 core-shell nanoparticles.

[0071] Figure 1 TEM images of ZnO nanoparticles (a) and ZnO@C core-shell nanoparticles (b-g) prepared in Examples 1-6 are shown. As can be seen, the particle size of the ZnO@C core-shell nanoparticles increases significantly with increasing carbon source material dosage, and a thin carbon layer appears on their surface, indicating successful carbon shell coating.

[0072] and then, Figure 2 HRTEM images of each of the aforementioned nanoparticles are presented. The high-resolution TEM images clearly demonstrate the significant size increase of the ZnO@C core-shell nanoparticles, along with a thin carbon layer on their surface, further demonstrating successful encapsulation and the formation of an ideal core-shell structure. This encapsulation structure, when applied to organic solar cells, can passivate ZnO surface defects and physically isolate them from the effects of water and oxygen in the air, providing a protective effect.

[0073] Figure 3 The ultraviolet-visible absorption spectra of ZnO nanoparticles and ZnO@C core-shell nanoparticles prepared in Examples 1 to 6 were tested.

[0074] from Figure 3It can be seen that as the amount of carbon source material increases, the particle size of the nanoparticles increases, and the ultraviolet absorption cutoff edge belonging to ZnO at 360nm undergoes a significant red shift. According to the formula E=1240 / λ, as the absorption cutoff edge red shifts, the optical band gap of ZnO@C core-shell nanoparticles is smaller than that of ZnO nanoparticles. The cutoff wavelength of standard ZnO in the figure is 359.4nm and the optical band gap is 3.45eV. The cutoff wavelength of ZnO@C-80 core-shell nanoparticles prepared in Example 5 is 378.2nm and the optical band gap is 3.28eV. Using it as the electron transport layer material of organic solar cells will be beneficial to the conductive properties of ZnO and improve the final device efficiency.

[0075] Figure 4 Photoluminescence spectra of ZnO nanoparticles and ZnO@C core-shell nanoparticles prepared in Examples 1-6 are provided. The PL spectra show a decrease in the ZnO emission peak at 550nm, which is an intrinsic defect of zinc oxide, demonstrating that carbon coating can suppress zinc oxide defects. Application in organic solar cells can reduce the probability of photocatalytic oxidation, helping to improve device stability. Furthermore, the strong emission peak of ZnO@C at 420nm also demonstrates its suitability as a barrier layer in electronic devices such as OLEDs.

[0076] from Figure 5 Comparison of the X-ray diffraction patterns of the ZnO nanoparticles and the ZnO@C core-shell nanoparticles represented by Example 3 shows that the crystal structure of the ZnO@C core-shell nanoparticles has not changed, and the crystallinity has been enhanced to a certain extent, which is beneficial to conductivity.

[0077] Figure 6 The X-ray photoelectron spectroscopy of ZnO nanoparticles and ZnO@C core-shell nanoparticles prepared in Examples 2 to 5 is further provided. XPS data show that the Zn 2p 3 / 2 and 2p 1 / 2 The peaks shifted toward higher energy compared to the Zn peak in ZnO and increased with the increase in the amount of carbon source material, which indicates the formation of Zn-N bonds and the formation of ZnO@C core-shell nanoparticles.

[0078] Likewise, from Figure 7 The ultraviolet photoelectron energy spectra of ZnO nanoparticles and ZnO@C core-shell nanoparticles with different carbon source material dosages can also show that with the increase of carbon source material dosage, the work function of ZnO@C is significantly reduced, which will be conducive to forming an ideal ohmic contact when applied to organic solar cell devices, reducing unnecessary voltage drop and improving charge extraction efficiency.

[0079] Furthermore, water contact angle and diiodomethane (DIM) contact angle tests were conducted on ZnO nanoparticles and ZnO@C core-shell nanoparticles prepared in Examples 1 to 6. The test results are as follows: Figure 8 shown.

[0080] Among them, the ZnO film has the smallest water contact angle, at 60.4°, while the ZnO@C prepared in Example 3 has the largest water contact angle, reaching 112°. The others are also larger than the ZnO film. This will help isolate water and oxygen in the air and ensure the long-term stability of the device.

[0081] The opposite pattern was observed for the DIM contact angle. The DIM contact angles of the ZnO@C films were all lower than the 50.1° of the standard ZnO films, which facilitates the formation of active layer organic molecules on the ETL surface. The optimal value was achieved in Example 3, which can be understood as achieving a relatively ideal carbon coating. Less than this coating is incomplete, while more than this results in an excessive carbon content.

[0082] Example 7.

[0083] The o-phenylenediamine in Example 3 was replaced with p-phenylenediamine of equal mass, and the preparation method was the same to prepare ZnO@C core-shell nanoparticles.

[0084] Example 8.

[0085] The o-phenylenediamine in Example 3 was replaced with m-phenylenediamine of equal mass and the preparation method was the same to prepare ZnO@C core-shell nanoparticles.

[0086] Example 9.

[0087] The o-phenylenediamine in Example 3 was replaced with an equal mass of phthalic acid and the preparation method was the same to prepare ZnO@C core-shell nanoparticles.

[0088] Example 10.

[0089] The o-phenylenediamine in Example 3 was replaced with terephthalic acid of equal mass and the preparation method was the same to prepare ZnO@C core-shell nanoparticles.

[0090] Example 11.

[0091] The o-phenylenediamine in Example 3 was replaced with isophthalic acid of equal mass and the preparation method was the same to prepare ZnO@C core-shell nanoparticles.

[0092] Example 12.

[0093] The o-phenylenediamine in Example 3 was replaced with an equal mass of trimesic acid and the preparation method was the same to prepare ZnO@C core-shell nanoparticles.

[0094] Example 13.

[0095] The o-phenylenediamine in Example 3 was replaced with KH-792 of equal mass, and the preparation method was the same to prepare ZnO@C core-shell nanoparticles.

[0096] Example 14.

[0097] The o-phenylenediamine in Example 3 was replaced with an equal mass of 3-aminopyridine-2-carboxylic acid, and the preparation method was the same to prepare ZnO@C core-shell nanoparticles.

[0098] Application example 1.

[0099] An inverted organic solar cell was prepared using the ZnO@C-10 core-shell nanoparticles prepared in Example 2 of the present invention as an electron transport layer material, and the device structure was ITO / ZnO@C / PM6:Y6 / MoO3 / Al.

[0100] The ZnO@C core-shell nanoparticles were dispersed in anhydrous methanol and diluted to a concentration of 10 mg / mL, and ultrasonically dispersed to obtain a ZnO@C core-shell nanoparticle dispersion.

[0101] Weigh 2.1 mg PM6 and 2.52 mg Y6, add them to 300 μL chloroform, stir at 50°C for 2 h, then add 1.5 μL chloronaphthalene, stir for 30 min to obtain an active layer solution.

[0102] Fix the ITO glass with a size of 25mm×1mm×25mm on a polytetrafluoroethylene cleaning rack and place it in a beaker. First, ultrasonically clean it with a detergent solution for 30 minutes, then use deionized water and anhydrous ethanol to ultrasonically clean it twice, each for 30 minutes. Take it out and soak it in a flask filled with isopropyl alcohol for later use.

[0103] The ITO glass surface was dried from the side using compressed air in a fume hood, and then treated with UV-ozone for 30 min to improve the wettability and work function of the ITO glass surface and remove the residual solution on the ITO glass surface.

[0104] Place the ITO glass on a spin coater, take 100 μL of ZnO@C core-shell nanoparticle dispersion, and statically spin-coat it onto the ITO glass at a speed of 3000 r / min. After the spin coating is completed, anneal the ITO glass at 100°C for 10 minutes to obtain a ZnO@C electron transport layer.

[0105] The active layer solution was dynamically spin-coated on the previously prepared ITO / electron transport layer at a rotation speed of 2400 r / min for 35 s, and thermally annealed at 100° C. on a hot stage for 10 min.

[0106] Then the prepared ITO / ZnO@C / PM6:Y6 film was placed in a vacuum evaporation apparatus at 4×10-4 Pa vacuum, and then 10 nm MoO3 was deposited. -4 A 100nm thick Al electrode was deposited under a vacuum degree of Pa.

[0107] Take out the ITO glass from the evaporator to obtain the organic solar cell V1, with an effective area of ​​0.09mm 2 .

[0108] Application example 2.

[0109] Except for using the ZnO@C-30 core-shell nanoparticles prepared in Example 3, the rest were prepared according to the method of Application Example 1 to prepare the organic solar cell V2.

[0110] Application example 3.

[0111] Except for using the ZnO@C-50 core-shell nanoparticles prepared in Example 4, the rest were prepared according to the method of Application Example 1 to prepare the organic solar cell V3.

[0112] Application example 4.

[0113] Except for using the ZnO@C-80 core-shell nanoparticles prepared in Example 5, the rest were prepared according to the method of Application Example 1 to prepare the organic solar cell V4.

[0114] Application example 5.

[0115] Except for using ZnO@C core-shell nanoparticles prepared using p-phenylenediamine as the carbon source material in Example 7, the rest of the methods were followed according to Application Example 1 to prepare the organic solar cell V5.

[0116] Application Example 6.

[0117] Except for using ZnO@C core-shell nanoparticles prepared with phthalic acid as the carbon source material in Example 9, the rest of the methods were followed according to Application Example 1 to prepare organic solar cell V6.

[0118] Application example 7.

[0119] The organic solar cell V7 was prepared according to the method of Application Example 1 except that the ZnO@C core-shell nanoparticles prepared using trimesic acid as the carbon source material in Example 12 were used.

[0120] Application Example 8.

[0121] Except for using ZnO@C core-shell nanoparticles prepared with KH-792 as the carbon source material in Example 13, the rest were prepared according to the method of Application Example 1 to prepare the organic solar cell V8.

[0122] Application Example 9.

[0123] The organic solar cell V9 was prepared according to the method of Application Example 1, except that the ZnO@C core-shell nanoparticles prepared using 3-aminopyridine-2-carboxylic acid as the carbon source material in Example 14 were used.

[0124] Comparative Example 1.

[0125] Using ZnO nanoparticles, an organic solar cell V0 having a device structure of ITO / ZnO / PM6:Y6 / MoO3 / Al was prepared according to the method of Application Example 1.

[0126] Comparative Example 2.

[0127] ZnO@C core-shell nanoparticles were prepared according to the preparation method of Example 3, except that o-phenylenediamine was replaced with an equal mass of glucose. Then, organic solar cell VV1 was prepared according to the method of Application Example 1.

[0128] Comparative Example 3.

[0129] ZnO@C core-shell nanoparticles were prepared according to the preparation method of Example 3, except that o-phenylenediamine was replaced with citric acid of equal mass. Then, organic solar cell VV2 was prepared according to the method of Application Example 1.

[0130] The device efficiencies of the organic solar cells prepared in the above Application Examples 1 to 9 and Comparative Examples 1 to 3 were tested, and the specific test results are listed in Table 1.

[0131]

[0132] As can be seen from Table 1, the device efficiency of organic solar cells prepared by coating ZnO with common organic small molecules glucose and citric acid as carbon source materials and using them as electron transport layer materials is very poor, and even short circuit occurs.

[0133] The carbon source material-coated devices selected in this invention all exhibited good device efficiencies, comparable to the V0 efficiency of standard ZnO devices, with the V2 efficiency being the highest. Combined with the previous analysis, this demonstrates that the ZnO@C core-shell nanoparticles prepared in this invention can form good contact with the organic material in the active layer.

[0134] Long-term stability of organic solar cells is a prerequisite for their commercialization. Once ZnO@C-based devices achieve efficiencies comparable to standard devices, their stability becomes equally important.

[0135] Figure 9 The air stability diagrams of organic solar cell devices V0, V2 and V4 are given.

[0136] After aging in air for 100 hours, the device efficiency of the standard device V0 decays to about 45% of the original efficiency, but devices V2 and V4 still have about 75% of the initial efficiency, which is mainly reflected in the short-circuit current density. J SC The fill factor (FF) is more stable, significantly improving the air stability of the device. This is attributed to its core-shell structure, which, on the one hand, effectively blocks the infiltration of water and oxygen in the air due to the change in contact angle, and on the other hand, suppresses the reaction between ZnO and water and oxygen by passivating ZnO surface defects.

[0137] Figure 10 The figure below shows the UV stability of organic solar cell devices V0 and V2. It can be found that similar to the air stability, the ZnO@C device under UV light J SC and FF maintain strong stability, and its V OC The ZnO@C-based device also maintained a high degree of stability. After 3 hours of UV irradiation, the standard device V0 only maintained 30% of its original efficiency, while the ZnO@C-based device maintained 75% of its original efficiency, demonstrating stronger UV stability. This is attributed to the core-shell structure suppressing surface defects in ZnO, thereby blocking the photocatalytic reaction between ZnO and the active layer acceptor material under UV irradiation.

[0138] The above embodiments of the present invention do not describe all details in detail, nor do they limit the present invention to the above embodiments. Various changes, modifications, substitutions, and variations made by those skilled in the art without departing from the principles and purpose of the present invention are intended to be included within the scope of protection of the present invention.

Claims

1. A zinc oxide@carbon core-shell nanoparticle, using any of the following organic small molecule carbon source materials: a) a benzene derivative or pyridine derivative substituted with at least one amino group and / or carboxyl group; b) small silane molecules that can undergo coupling reaction with zinc oxide; It is added to a nano zinc oxide methanol solution and subjected to solvent thermal reaction at 150-200°C. The carbon source molecules are coated on the surface of the zinc oxide and carbonized into a carbon shell through high temperature and high pressure to form a composite material of carbon shell-coated zinc oxide quantum dots.

2. The zinc oxide@carbon core-shell nanoparticles according to claim 1, characterized in that The benzene derivatives are o-phenylenediamine, m-phenylenediamine, p-phenylenediamine and their derivatives; o-phenylenediamine, m-phenylenediamine, terephthalic acid and their derivatives; and trimesic acid.

3. The zinc oxide@carbon core-shell nanoparticles according to claim 1, characterized in that The pyridine derivative is 3-aminopyridine-2-carboxylic acid or 4-aminopyridine-3-carboxylic acid.

4. The zinc oxide@carbon core-shell nanoparticles according to claim 1, characterized in that The silane small molecule is a silane coupling agent KH-792 or KH-560.

5. The method for preparing the zinc oxide@carbon core-shell nanoparticles according to claim 1 comprises adding the organic small molecule carbon source material to a nano-zinc oxide methanol solution in a mass ratio of 0.05 to 1:1, mixing the organic small molecule carbon source material uniformly, heating the solution to 150 to 200° C. for a solvothermal reaction, and forming a composite material of carbon shell-coated zinc oxide quantum dots.

6. The method for preparing zinc oxide@carbon core-shell nanoparticles according to claim 5, characterized in that The solvent thermal reaction time is not less than 3 hours.

7. Use of the zinc oxide@carbon core-shell nanoparticles according to claim 1 in the preparation of organic solar cells.

8. Use of the zinc oxide@carbon core-shell nanoparticles according to claim 1 as an electron transport layer material for organic solar cells.

9. Use of the zinc oxide@carbon core-shell nanoparticles according to claim 1 in the preparation of organic light-emitting diode devices.

10. Use of the zinc oxide@carbon core-shell nanoparticles according to claim 1 as a barrier layer material for an organic light-emitting diode.

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