A method for improving the stability of lead halide perovskite thin films and products

Abstract

The application discloses a method for improving stability of a lead halide perovskite thin film and a product, and the method comprises the following steps: covering an alcohol solution of a polymerizable acrylic small molecule on a crystallized perovskite polycrystalline thin film, and passivating surface defects of the perovskite through a light curing mode at room temperature, so as to improve hydrophobicity of the perovskite thin film and further improve performance and stability of a device; the structure of the polymerizable acrylic small molecule is [CH2=CHCOO] n R, R is a single or multiple groups of phenyl, a saturated alkyl chain, a methoxy group, a carbonyl group, a nitrile group, a carboxyl group, an aldehyde group and a hydroxyl group in any combination, the method of the application can obviously improve hydrophobicity of the perovskite thin film, repair surface defects of the perovskite thin film, improve performance and stability of a perovskite solar cell, and has the advantages of simple process, low requirement on equipment, high stability and repeatability, good universality, low dependence on environment and low cost.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of perovskite solar cells, and particularly relates to a method for improving stability of a lead halide perovskite film and a product. BACKGROUND

[0002] As a leading photovoltaic technology, metal halide perovskite solar cells have attracted widespread attention from academia and industry. The perovskite light-absorbing layer has excellent optoelectronic properties, such as strong light absorption, high charge carrier mobility and low-cost manufacturing, making perovskite solar cells one of the most promising photovoltaic technologies and promising for commercialization.

[0003] Although in the laboratory, the efficiency of perovskite solar cells has exceeded other commercialized thin-film solar cells based on CdTe, (Cu, In) GaSe2 and amorphous silicon, and is very close to the efficiency of crystalline silicon solar cells. The progress in photoelectric conversion efficiency may be the fastest in the history of photovoltaic development, which is largely due to the ideal optoelectronic properties of the perovskite absorber itself and the application of the knowledge accumulated over decades of photovoltaic technology research and development. The progress in photoelectric conversion efficiency may be the fastest in the history of photovoltaic development, which is mainly due to the ideal optoelectronic properties of the perovskite absorber itself and the application of the knowledge accumulated over decades of photovoltaic technology research and development. The perovskite material for light harvesting has the same ABX3 chemical formula, where A contains monovalent cations; B is a divalent metal ion; and X contains halogen. In theory, these components can be easily combined into a crystal lattice with any stoichiometric ratio. However, halide perovskites are prone to react when exposed to aging stressors such as light, heat, moisture, oxygen and electric field, most of which cannot be avoided during device operation. It inevitably causes decomposition of the material, loss of components, collapse of the crystal lattice, phase transition, etc., resulting in failure of the device.

[0004] Since 2009, when the first perovskite solar cells were reported with a lifetime of only a few seconds, to date, perovskite solar cells have been reported to have a lifetime of about 1 year under standard aging conditions, which is far below the 25-year lifetime guarantee of most commercial photovoltaic modules. To date, in order to improve the service life of perovskite solar cells under actual working conditions, research work has gradually shifted from efficiency to device stability. Since the formation and growth of crystals are always accompanied by the transition from the liquid phase to the solid phase during the solution processing of perovskite thin films. Due to the self-assembly characteristics, the formation of perovskite thin films generally starts from the substrate. The periodic lattice arrangement on the surface of the perovskite thin film is stopped. This will introduce a large number of dangling bonds on the surface as defect sites (especially vacancy defects). In addition, perovskite degradation usually starts from the defect sites on the surface, which are more reactive to water and oxygen, and other environmental factors. All these factors indicate that there are a large number of defects on the surface of the perovskite thin film and they can be the initiators of perovskite degradation, so developing an effective surface passivation method is an important step to improve the working stability of perovskite solar cells. The common surface passivation method is to introduce some small molecules, the characteristics of these molecules are that some of them can react with the excess lead iodide in the perovskite to form other forms of perovskite, covering the surface of the perovskite; some of them can coordinate with the defects on the surface of the perovskite, passivating the defects on the surface of the perovskite. The main role of introducing these molecules is to improve the intrinsic stability of the perovskite thin film, but it cannot change the water and oxygen intolerance of the perovskite thin film, so the stability of the devices prepared under high humidity and other environments has not been significantly improved.

[0005] Besides the effective surface passivation method of perovskite thin film, encapsulating perovskite solar cell device is another common method to improve the stability of perovskite cell. Generally, the encapsulation method of perovskite device is to cover the outer surface of the device with sealing glue, and to bond the device on the glass substrate. For example, polyisobutylene is used as a hydrophobic layer in the flat-plate structure of perovskite solar cell. The edge encapsulation process based on polyisobutylene effectively inhibits the erosion of moisture, and improves the stability of the device under the conditions of humid heat test and thermal cycle. Or use ethylene-vinyl acetate (EVA) to encapsulate the device, the encapsulated device can still retain 90% of the initial efficiency after 200 times of thermal cycle test, but EVA material will react with perovskite under the action of temperature, which is not conducive to the further improvement of the stability of the device. Although the encapsulation process can improve the stability of the device, this method has high requirements for equipment and environment, and generally requires additional heating process, which may cause damage to the perovskite solar device. When the curing glue is heated, it is easy to appear holes and cannot uniformly cover the device. The appearance of holes will adversely affect the working stability of the device. At the same time, due to the complexity and diversity of perovskite composition, some curing glue may also react with perovskite thin film, destroy perovskite thin film and further reduce the stability of the efficiency of the device. Therefore, the method based on encapsulation has great limitations, which is not conducive to the wide application of this technology.

[0006] Prior art one:

[0007] The encapsulation method of perovskite cell is to cover the outer surface and side surface of the device with sealing glue, and then cover it with a glass plate. The disadvantage of this method is that the processing method has high requirements for equipment and environment, and requires additional heating and glass plate covering process. There are problems such as holes on the surface of the sealing glue and uneven coverage of the device.

[0008] Prior art two:

[0009] Another method to improve the stability of perovskite solar cell device is to add a polymerizable molecule with carbon-carbon double bond or triple bond to the precursor solution of perovskite, coat the solution on the substrate, and then obtain a mixed film of perovskite and polymer by heating and annealing. The disadvantage of this method is that the solubility of the molecule is required, and the selected molecule must be soluble in the precursor solution of perovskite. During the heating and annealing process of the thin film, the polymerization reaction of the molecule may have adverse effects on the nucleation and crystallization of perovskite, reducing the photoelectric conversion efficiency of the device. At the same time, the random distribution of molecules in the perovskite layer leads to large differences in the stability of the obtained device, which is not conducive to the large-scale production.

[0010] At present, the intrinsic stability of the thin film is improved based on the surface passivation of the thin film, but the water and oxygen stability of the corresponding device is not obviously improved, and the device outer surface packaging method can improve the device stability, but the process is complex and has great limitations, therefore, a repeatable and simple method is sought, which can not only passivate the surface defects of the perovskite thin film, but also improve the stability of the perovskite thin film and the solar cell device, which has important significance for improving the service life of the perovskite device. SUMMARY

[0011] The technical problem to be solved by the present application is to provide a method for improving the stability of a lead halide perovskite thin film and a product, which improves the stability of the perovskite layer and also improves the efficiency and stability of the solar cell device; it is not only suitable for rigid solar cells based on glass substrates, but also suitable for flexible devices based on plastic substrates, which is conducive to the further commercialization of perovskite solar cells.

[0012] The technical scheme adopted by the present application is as follows:

[0013] A method for improving the stability of a lead halide perovskite thin film, which covers an alcohol solution of a polymerizable acrylic small molecule on the surface of a crystallized perovskite material, and obtains a perovskite polycrystalline thin film layer with improved hydrophobicity after light treatment under room temperature conditions.

[0014] Specifically, the molecular structure of the polymerizable acrylic small molecule has the following general formula:

[0015] [CH2=CHCOO] n -R

[0016] Among them, R is a phenyl group, a saturated alkyl chain, a carbonyl group, a CH3-O methoxy group, a C≡N nitrile group, a -COOH carboxyl group, an aldehyde group and an -OH hydroxyl group, and n is 1, 2, 3 or 4.

[0017] Further, the polymerizable acrylic small molecule is specifically:

[0018] (3-methoxyphenyl) methyl 2-acrylate;

[0019] 2-oxo-1,2-diphenyl ethyl acrylate;

[0020] benzyl acrylate;

[0021] hydroxyethyl methacrylate;

[0022] (3,5-di-tert-butyl-4-hydroxybenzyl) acrylate.

[0023] Specifically, the concentration of the alcohol solution is 5-20 mg / mL.

[0024] Specifically, the alcohol solution is isopropanol, and the perovskite material is methylamine lead iodine, formamidinium lead iodine or cesium lead iodine.

[0025] Specifically, the alcohol solution of the polymerizable acrylic small molecule is coated on the surface of the crystallized perovskite material by spin coating, spraying, soaking or blade coating process.

[0026] Another technical solution of the present application is a solar cell device, comprising a substrate, a transparent conductive cathode, an electron transport layer, a perovskite polycrystalline thin film layer, a hole transport layer and an anode which are sequentially stacked, the perovskite polycrystalline thin film layer is prepared by the method for improving the stability of lead halide perovskite thin film, and the thickness of the perovskite polycrystalline thin film layer is 300-600 nm.

[0027] Specifically, the transparent conductive cathode is made of inorganic material or organic conductive polymer, the inorganic material is one of indium tin oxide, zinc oxide or tin oxide, or one of gold, copper, silver or zinc; the organic conductive polymer is polythiophene, polyethylene basic sodium phenyl sulfonate or polyaniline.

[0028] Specifically, the electron transport layer is tin oxide, titanium oxide, zinc oxide, fullerene or fullerene derivative.

[0029] Specifically, the hole transport layer is 2,2',7,7'-tetrakis[N,N-di(4-methoxyphenyl) amino]-9,9'-spirobifluorene, poly-3 hexylthiophene or poly[bis(4-phenyl)(2,4,6-trimethylphenyl) amine].

[0030] Compared with the prior art, the present application has at least the following beneficial effects:

[0031] The method for improving the stability of lead halide perovskite thin film of the present application has no requirements for equipment and operating environment, the concentration of the alcohol solution of the polymerizable acrylic base molecule is adjusted to realize uniform coverage of the perovskite polycrystalline thin film layer, and the appearance of holes is avoided; at the same time, the present application does not need additional glass plate covering, so that the efficiency and stability of the flexible device can be effectively improved; after the perovskite thin film is formed, the corresponding treatment is carried out on the thin film, which does not affect the nucleation and crystallization of the perovskite, and can effectively modify the surface defects of the perovskite thin film; the type of the acrylic base molecule is rich; the acrylic base molecule in the present application is crosslinked by light, which avoids the damage of heating to the perovskite thin film, realizes effective protection of the perovskite thin film, and improves the efficiency and working stability of the device.

[0032] Further, the polymerizable acrylic small molecule can passivate the surface defects of the light-absorbing layer due to its structural characteristics, and improve the hydrophobicity of the light-absorbing layer.

[0033] Further, the polymerizable acrylic small molecule is not limited to one or several structures, and the combination of different groups determines that the polymerizable acrylic small molecule is a universal encapsulating material.

[0034] Further, by setting the use concentration of the polymerizable acrylic small molecule, a targeted encapsulation method can be made for various types of perovskite light-absorbing layers.

[0035] Further, the modified perovskite light-absorbing layer is not limited to one or several structures. For a universal ABX3-type perovskite such as methylamine lead iodine, formamidinium lead iodine, or cesium lead iodine, the stability of the thin film can be effectively improved after modification by the polymerizable acrylic small molecule due to the structural characteristics of the molecule, which demonstrates the universality of the polymerizable acrylic small molecule. By setting the alcohol solution as isopropyl alcohol, the concentration of the polymerizable acrylic small molecule can be accurately controlled to achieve precise encapsulation of the perovskite light-absorbing layer.

[0036] Further, for different application scenarios, based on the good spreadability of the polymerizable acrylic small molecule alcohol solution on the perovskite surface, various processes such as spin coating, spraying, soaking, or blade coating can be used to cover the crystallized perovskite material, and then the encapsulation of the perovskite layer can be achieved after light curing.

[0037] A solar cell device is composed of a substrate, a transparent conductive cathode, an electron transport layer, a perovskite polycrystalline thin film layer, a hole transport layer, and an anode, which are stacked in sequence to form a multilayer thin film accumulation. The preparation is relatively simple, the cost is low, and it is conducive to large-scale application.

[0038] Further, the use of a transparent conductive cathode can reduce light loss, allowing the perovskite layer to absorb more light energy. On the other hand, it can form a loop with the backend equipment to facilitate the transmission of generated electrical energy.

[0039] Further, the electron transport layer is tin oxide, titanium oxide, zinc oxide, fullerene, or fullerene derivative. Due to its good electron transport characteristics and low-temperature preparation characteristics, it is conducive to the preparation of high-performance perovskite solar cells.

[0040] Further, the hole transport layer is 2,2',7,7'-tetra[N,N-di(4-methoxyphenyl)amino]-9,9'-spirobifluorene, poly-3-hexylthiophene, or poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine]. Due to its excellent transport characteristics and suitability for various preparation methods, it helps to improve the efficiency of the battery device.

[0041] In summary, the present application effectively improves the hydrophobicity of the light-absorbing layer and the conversion efficiency and stability of the device by uniformly covering the surface of the perovskite light-absorbing layer with the polymerizable acrylic-based small molecule.

[0042] The technical solutions of the present application are described in further detail below with reference to the accompanying drawings and examples. BRIEF DESCRIPTION OF DRAWINGS

[0043] Figure 1 Structure diagram of a positive perovskite solar cell;

[0044] Figure 2 Molecular structure diagram of benzyl acrylate;

[0045] Figure 3 Scanning electron microscope images of Example 1 before and after coverage;

[0046] Figure 4 Perovskite film water drop test images of Example 1 before and after coverage;

[0047] Figure 5 Voltage-current density curve diagram of the devices prepared using the modified perovskite layer of Example 1 and the unmodified perovskite layer;

[0048] Figure 6 Molecular structure diagram of 2-oxo-1,2-diphenyl ethyl acrylate;

[0049] Figure 7 Scanning electron microscope images of Example 2 before and after coverage;

[0050] Figure 8 Perovskite film water drop test images of Example 2 before and after coverage;

[0051] Figure 9 Voltage-current density curve diagram of the devices prepared using the modified perovskite layer of Example 2 and the unmodified perovskite layer;

[0052] Figure 10 Molecular structure diagram of (3-methoxyphenyl) methyl 2-acrylate;

[0053] Figure 11 Scanning electron microscope images of Example 3 before and after coverage;

[0054] Figure 12 Perovskite film contact angle test images of Example 3 before and after coverage;

[0055] Figure 13 Voltage-current density curve diagram of the devices prepared using the modified perovskite layer of Example 3 and the unmodified perovskite layer;

[0056] Figure 14The voltage-current density curve of the device prepared by the un-encapsulated and encapsulated perovskite layer of Comparative Example 1.

[0057] Wherein: 1. substrate; 2. transparent conductive cathode; 3. electron transport layer; 4. perovskite polycrystalline thin film layer; 5. hole transport layer; 6. anode. DETAILED DESCRIPTION

[0058] The technical solutions of the present application will be described clearly and completely below. Obviously, the described embodiments are part of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all the other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the present application.

[0059] In the present application, all the embodiments and preferred embodiments mentioned in the present application can be combined to form new technical solutions, if not otherwise specified.

[0060] In the present application, all the technical features and preferred features mentioned in the present application can be combined to form new technical solutions, if not otherwise specified.

[0061] In the present application, the percentage (%) or part refers to the percentage by weight or weight part of the composition, if not otherwise specified.

[0062] In the present application, the components or preferred components involved can be combined to form new technical solutions, if not otherwise specified.

[0063] In the present application, unless otherwise specified, the numerical range "a~b" represents a shorthand notation for any real number combination between a and b, wherein a and b are both real numbers. For example, the numerical range "6~22" represents that all the real numbers between "6~22" have been listed herein, and "6~22" is only a shorthand notation for these numerical combinations.

[0064] The lower limit and upper limit of the range disclosed in the present application can be one or more lower limits and one or more upper limits, respectively.

[0065] In the present application, the term "and / or" used herein refers to any combination of one or more of the associated listed items and all possible combinations, and includes these combinations.

[0066] In the present application, unless otherwise specified, each reaction or operation step can be carried out sequentially or according to the sequence. Preferably, the reaction method herein is carried out sequentially.

[0067] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. Methods and materials similar or equivalent to those described herein can be used in the practice of the present application.

[0068] In order to effectively improve the stability of the thin film and the device under high humidity conditions, and to solve the problems of complex process and great limitation of encapsulation treatment for perovskite devices, and not suitable for flexible devices, the application provides a method for improving the stability of lead halide perovskite thin film and a product, relates to an internal encapsulation strategy of perovskite thin film, and achieves polymerization of molecules by coating a prepared polymerizable acrylic small molecule solution on the surface of the perovskite layer and then curing the solution under room temperature and light irradiation, and the polymerized molecules uniformly cover the surface of the perovskite layer, which can effectively passivate the surface defects of the perovskite layer and protect the perovskite layer, thereby improving the stability of the perovskite layer and the conversion efficiency and stability of the solar cell device.

[0069] The application provides a method for improving the stability of lead halide perovskite thin film, which covers specific polymerizable acrylic small molecules on the surface of the perovskite layer and cures the small molecules under room temperature and light irradiation, thereby effectively passivating the defects of the perovskite thin film, improving the photoelectric conversion efficiency of the device, and improving the overall stability from the inside of the device, which is beneficial to the further application of the perovskite solar cell, and the specific steps are as follows.

[0070] The alcohol solution of the polymerizable acrylic small molecules with a concentration of 5-20 mg / mL is covered on the crystallized perovskite polycrystalline thin film, and then the solution is cured under room temperature and light irradiation, so that the perovskite polycrystalline thin film with improved hydrophobicity is obtained, the water resistance of the perovskite polycrystalline thin film is improved, and the performance of the perovskite device is improved.

[0071] In the application, the alcohol solution of the polymerizable acrylic small molecules is covered on the perovskite thin film by using a spin coating, spraying, soaking or blade coating process.

[0072] The molecular structure of the polymerizable acrylic small molecules is as follows:

[0073] [CH2=CHCOO] n -R

[0074] In the application, R is a phenyl group, a saturated alkyl chain, a carbonyl group, a CH3-O methoxy group, a C≡N nitrile group, a -COOH carboxyl group, an aldehyde group and an -OH hydroxyl group.

[0075] In the application, n is 1, 2, 3 or 4.

[0076] The solvent is selected from alcohol solvents, and the alcohol is isopropyl alcohol; the perovskite material includes methylamine lead iodine, formamidinium lead iodine, or cesium lead iodine.

[0077] The optional molecules include:

[0078] (3-methoxyphenyl)methyl 2-propenoate;

[0079] 2-oxo-1,2-diphenylethyl propenoate;

[0080] benzyl propenoate;

[0081] hydroxyethyl methacrylate;

[0082] (3,5-di-tert-butyl-4-hydroxybenzyl) acrylate.

[0083] A solar cell device includes a substrate 1, a transparent conductive cathode 2, an electron transport layer 3, a perovskite polycrystalline thin film layer 4, a hole transport layer 5, and an anode 6, which are sequentially stacked; wherein the perovskite polycrystalline thin film layer is prepared by the above method, and the thickness of the perovskite polycrystalline thin film layer 4 is 300-600 nm.

[0084] Specifically, the substrate 1 is glass or a flexible substrate, wherein the flexible substrate is a polyester or a polythiophene compound.

[0085] The transparent conductive cathode 2 is made of inorganic material or organic conductive polymer, the inorganic material is one of indium tin oxide, zinc oxide or tin oxide, or is one of gold, copper, silver or zinc; the organic conductive polymer is polythiophene, polyethylene basic benzene sulfonic acid sodium or polyaniline.

[0086] The material of the electron transport layer 3 is tin oxide, titanium oxide, zinc oxide, fullerene or fullerene derivative.

[0087] The hole transport layer 5 is 2,2',7,7'-tetra[N,N-di(4-methoxyphenyl)amino]-9,9'-spirobifluorene (Spiro-OMeTAD for short), poly-3 hexylthiophene (P3HT for short), or poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA for short).

[0088] The material of the anode 6 is metal, and the metal is gold, silver, copper or aluminum.

[0089] Finally, as shown in Figure 1A positive type perovskite solar cell of the structure shown; from bottom to top in the figure are substrate 1, transparent conductive cathode 2, electron transport layer 3, perovskite polycrystalline thin film layer 4, hole transport layer 5 and anode 6.

[0090] To make the objects, technical solutions and advantages of the embodiments of the present application clearer, the following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are some but not all of the embodiments of the present application. The components of the embodiments of the present application described and shown in the drawings herein can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the claimed present application, but merely represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the scope of protection of the present application.

[0091] Embodiment 1

[0092] The present application provides a CH3NH3PbI3 lead-based perovskite thin film and device, which introduces benzyl acrylate molecules to modify the perovskite solar cell to improve the performance and stability of the device. The specific implementation is as follows:

[0093] Please refer to Figure 1 The perovskite solar device according to the first embodiment of the present application has the following structure:

[0094] Glass (plastic) substrate / ITO (100 nm) / SnO2 (30 nm) / CH3NH3PbI3 (300 nm) / Spiro-OMeTAD (120 nm) / Ag (120 nm).

[0095] (1) Cleaning of the plastic substrate pre-engraved with ITO:

[0096] The transparent conductive substrate 1 (ITO / plastic) is cleaned by ultrasonic treatment with ethanol, acetone and deionized water, and then placed under an infrared lamp for drying. The ITO film on the transparent conductive substrate 1 serves as the cathode layer of the device, and the sheet resistance of the ITO film is 15-30 Ω, and the film thickness is 80-120 nm.

[0097] (2) Preparation of the electron transport layer:

[0098] The dried substrate was treated with UV-ozone for 5-10 minutes, and then placed on a spin coater. A Sn02aqueous solution was prepared and spin-coated onto the substrate using a static dispensing method at a speed of 3000 rpm for 30 seconds. The sample was dried at 150°C for 0.5 hours, and the thickness of the film was 30 nm.

[0099] (3) Preparation of the perovskite layer:

[0100] 462 mg of PbI2and 159 mg of CH3NH3I were weighed and added to a mixture of 0.8 mL of DMF and 0.2 mL of DMSO to form a precursor solution, which was heated and stirred at 60°C overnight. After filtration, the solution was spin-coated onto the electron transport layer at a speed of 3000 rpm for 40 seconds, and 0.7 mL of chlorobenzene was added to the top of the solution at the 10thsecond. After spin-coating, the substrate was annealed on a hot plate at 100°C for 10 minutes. The thickness of the film was 300 nm. For the film covered with a polymerizable small molecule, an additional 5 mg / mL solution of benzyl acrylate (BA) in alcohol was used to cover the perovskite film. The molecules were cured by irradiation for 5 minutes at room temperature. Figure 2 The molecular structure of benzyl acrylate is shown in FIG. 1, Figure 3 The scanning electron microscope images before and after covering are shown in FIG. 2, Figure 4 The water droplet test images of the perovskite film before and after covering are shown in FIG. 3, which shows that the hydrophobicity of the perovskite film is enhanced after covering.

[0101] (4) Preparation of the hole transport layer:

[0102] The solution of Spiro-OMeTAD was prepared and spin-coated onto the substrate using a static dispensing method at a speed of 3000 rpm for 30 seconds. The thickness of the film was 120 nm.

[0103] (5) Preparation of the anode:

[0104] The spin-coated and dried substrate was placed in a vacuum chamber, and silver was evaporated. The evaporation rate of the material film was 0.1 nm / s, and the film thickness was 120 nm.

[0105] Figure 5 The voltage-current density curves of the devices prepared with the modified and unmodified perovskite layers are shown in FIG. 4. It can be seen from the figure that the performance of the device prepared with the treated perovskite layer is greatly improved:

[0106] The short-circuit current density increased from 22.85 mA / cm 2 to 24.23 mA / cm 2The energy conversion efficiency is increased from 17.12% to 19.50%.

[0107] Embodiment 2

[0108] The application provides a lead-based perovskite thin film and device based on (NH2)2CHPbI3, and the performance and stability of a perovskite solar cell are improved by introducing 2-oxo-1,2-diphenyl ethyl acrylate molecules to modify the perovskite solar cell.

[0109] Please refer to Figure 1 The perovskite solar device according to the first embodiment of the application has the following structure:

[0110] Glass (plastic) substrate / ITO (100 nm) / SnO2 (30 nm) / (NH2)2CHPbI3 (500 nm) / Spiro-OMeTAD (120 nm) / Ag (150 nm).

[0111] (1) Cleaning of the ITO pre-etched glass substrate:

[0112] The transparent conductive substrate 1 (ITO glass) is cleaned by ultrasonic treatment with ethanol, acetone and deionized water, and then is placed under an infrared lamp for drying, wherein the ITO film on the transparent conductive substrate 1 serves as the cathode layer of the device, the square resistance of the ITO film is 15-30 Ω, and the film thickness is 80-120 nm.

[0113] (2) Preparation of the electron transport layer:

[0114] The dried substrate is treated with ultraviolet-ozone for 5-10 minutes, and then is placed on a spin coater to spin-coat the prepared SnO2 aqueous solution into a film by static dosing, the rotation speed of the spin coater is 3000 rpm, the spin coating time is controlled to be 30 s, and the sample is dried at 150 DEG C for 0.5 hours, and the thickness is 30 nm.

[0115] (3) Preparation of the perovskite layer:

[0116] Weigh 462 mg of PbI2, 172 mg of (NH2)2CHI, and add the above materials to a mixed solution of 0.8 mL of DMF and 0.2 mL of DMSO to form a precursor solution and heat and stir at 60°C overnight. After filtration, spin coating is performed on the electron transport layer at a speed of 3000 rpm for 40 s, and 0.7 mL of chlorobenzene is added dropwise to the solution at the 10th s. After spin coating, the substrate is annealed on the baking table at 150°C for 10 min. The film thickness is 500 nm. For the film covered with a polymerizable small molecule, an additional 10 mg / mL alcohol solution of 2-oxo-1,2-diphenyl ethyl acrylate is covered on the perovskite film, and the light is cured for 10 min at room temperature. Figure 6 A molecular structure diagram of 2-oxo-1,2-diphenyl ethyl acrylate, Figure 7 A scanning electron microscope image before and after covering, Figure 8 A perovskite film water drop test image before and after covering, it can be seen that the hydrophobicity of the perovskite film after covering is enhanced.

[0117] (4) Preparation of the hole transport layer:

[0118] On the substrate where the perovskite film is generated, the solution of the prepared Spiro-OMeTAD is spin-coated into a film by a static dosing method, the rotation speed of the film applicator is 3000 rpm, the film coating time is controlled to be 30 s, and the thickness is 120 nm.

[0119] (5) Preparation of the anode:

[0120] The spin-coated and dried substrate is placed in a vacuum chamber, and silver is evaporated, the evaporation rate of the material film is 0.1 nm / s, and the film thickness is 150 nm.

[0121] Figure 9 The voltage-current density curve of the device prepared by the modified perovskite layer and the unmodified perovskite layer is compared, and it can be seen from the figure that the device performance of the device prepared by the treated perovskite layer is greatly improved:

[0122] The short-circuit current density is increased from 23.89 mA / cm 2 to 25.12 mA / cm 2 , and the energy conversion efficiency is increased from 18.31% to 20.52%.

[0123] Example 3

[0124] The application provides a CsPbI3 lead-based perovskite film and device, which introduces (3-methoxyphenyl) methyl 2-propenoate molecules to modify the perovskite solar cell to improve the performance and stability of the device. The specific embodiments are as follows:

[0125] Referring to Figure 1 The perovskite solar device according to the first embodiment of the present application has the following structure:

[0126] Glass (plastic) substrate / ITO (100 nm) / SnO2 (30 nm) / CsPbI3 (500 nm) / Spiro-OMeTAD (120 nm) / Cu (150 nm).

[0127] (1) Cleaning of the ITO pre-etched glass substrate:

[0128] The transparent conductive substrate 1 (ITO glass) was cleaned by ultrasonic treatment with ethanol, acetone and deionized water, and then dried under an infrared lamp. The ITO film on the transparent conductive substrate 1 served as the cathode layer of the device, and had a sheet resistance of 15-30 Ω and a film thickness of 80-120 nm.

[0129] (2) Preparation of the electron transport layer:

[0130] The dried substrate was treated with UV-ozone for 5-10 minutes, and then placed on a spin coater. A SnO2 aqueous solution was prepared and spin-coated onto the substrate using a static dispensing method. The spin coater was operated at a speed of 3000 rpm for 30 seconds, and the sample was dried at 150 °C for 0.5 hours. The thickness of the film was 30 nm.

[0131] (3) Preparation of the perovskite layer:

[0132] PbI2 (462 mg) and CsI (260 mg) were weighed, and then added to a mixed solution of 0.6 mL of DMF and 0.4 mL of DMSO. The resulting precursor solution was heated and stirred at 60 °C overnight. After filtration, the solution was spin-coated onto the electron transport layer at a speed of 3000 rpm for 40 seconds, and 0.7 mL of chlorobenzene was added to the top of the solution at the 10th second. After spin-coating, the substrate was annealed on a hot plate at 200 °C for 10 minutes. The thickness of the film was 500 nm. For the film covered with a polymerizable small molecule, an additional 15 mg / mL alcohol solution of (3-methoxyphenyl) methyl 2-propenoate was applied to the perovskite film, and then cured under light at room temperature for 10 minutes. Figure 10 The molecular structure of (3-methoxyphenyl) methyl 2-propenoate is shown in Figure 1, Figure 11 The scanning electron microscope images before and after covering are shown in Figure 2, Figure 12 The contact angle test images of the perovskite film before and after covering are shown in Figure 3. It can be seen that the hydrophobicity of the perovskite film is enhanced after covering.

[0133] (4) Preparation of hole transport layer:

[0134] The substrate on which the perovskite film is generated is spin-coated with the solution of the configured Spiro-OMeTAD by a static dosing method, the rotation speed of the spin coater is 3000 rpm, the spin coating time is controlled to be 30 s, and the thickness is 120 nm;

[0135] (5) Preparation of anode:

[0136] The substrate spin-coated and dried is placed into a vacuum chamber, and silver is evaporated, the evaporation rate of the material film is 0.1 nm / s, and the film thickness is 150 nm.

[0137] Figure 13 In order to compare the voltage-current density curves of the devices prepared by the modified perovskite layer and the unmodified perovskite layer, it can be seen from the figure that the device performance of the device prepared by the treated perovskite layer is greatly improved:

[0138] The short-circuit current density is increased from 23.12 mA / cm 2 to 23.50 mA / cm 2 , and the energy conversion efficiency is increased from 17.74% to 18.74%.

[0139] Comparative Example 1

[0140] The application provides a CH3NH3PbI3 lead-based perovskite film and device, and a sealant is introduced to encapsulate the perovskite battery.

[0141] Please refer to Figure 1 The perovskite solar device according to the first embodiment of the application has the following structure:

[0142] Glass (plastic) substrate / ITO (100 nm) / SnO2 (30 nm) / CH3NH3PbI3 (300 nm) / Spiro-OMeTAD (120 nm) / Ag (120 nm).

[0143] (1) Cleaning of the plastic substrate pre-engraved with ITO:

[0144] The transparent conductive substrate 1 (ITO / plastic) is cleaned by ultrasonic treatment with ethanol, acetone and deionized water, and then is placed under an infrared lamp for drying, wherein the ITO film on the transparent conductive substrate 1 serves as the cathode layer of the device, the sheet resistance of the ITO film is 15-30 Ω, and the film thickness is 80-120 nm;

[0145] (2) Preparation of electron transport layer:

[0146] The substrate after drying treatment is treated with UV-ozone for 5-10 minutes, and then placed on a spin coater. The prepared SnO2 aqueous solution is spin-coated into a film by static dosing, the rotation speed of the spin coater is 3000 rpm, the spin coating time is controlled to be 30 s, and the sample is dried at 150 ℃ for 0.5 hours, and the thickness is 30 nm.

[0147] (3) Preparation of perovskite layer:

[0148] 462 mg of PbI2 and 159 mg of CH3NH3I are weighed, and the above materials are added to a mixed solution of 0.8 mL of DMF and 0.2 mL of DMSO to form a precursor solution, which is heated and stirred at 60 ℃ overnight. After filtration, spin-coating is performed on the electron transport layer at a speed of 3000 rpm, and the spin-coating time is 40 s; and 0.7 mL of chlorobenzene is added to the solution at the 10th second. After spin-coating, the substrate is annealed on a baking table at 100 ℃ for 10 min. The thickness of the film is 300 nm.

[0149] (4) Preparation of hole transport layer:

[0150] The prepared Spiro-OMeTAD solution is spin-coated into a film by static dosing, the rotation speed of the spin coater is 3000 rpm, the spin coating time is controlled to be 30 s, and the thickness is 120 nm.

[0151] (5) Preparation of anode:

[0152] The spin-coated and dried substrate is placed in a vacuum chamber, and silver is evaporated, the evaporation rate of the material film is 0.1 nm / s, and the film thickness is 120 nm.

[0153] (6) Packaging treatment:

[0154] The sealing glue is applied to the surface of the perovskite device, and then a glass cover plate is covered, and the packaging treatment of the perovskite device is realized by heating at 80 ℃ for 30 min.

[0155] Figure 14 For comparison of the voltage-current density curves of the devices prepared with and without packaging of the perovskite layer, it can be seen from the figure that the performance of the device prepared with the treated perovskite layer decreases:

[0156] The short-circuit current density is increased from 22.46 mA / cm 2 to 20.18 mA / cm 2 , and the energy conversion efficiency is reduced from 18.94% to 16.39%.

[0157] The additional heat treatment process of the device makes the device efficiency decrease obviously, and does not meet the requirement that the packaging does not affect the device efficiency. Through the comparative example, the excellent performance of the present application can be obviously embodied, and the device performance can be improved, and good stability is maintained.

[0158] For the existing problem one, the polymerizable acrylic-based molecules are coated on the surface of the perovskite film, the perovskite film is directly protected through room temperature light curing, so that the device stability is further improved, and the damage of heating to the film is avoided, the method is simple to operate, and there is no requirement for equipment and operation environment. Through simplifying the process, the process of removing the external cover glass plate is removed, and the present application can also be applied to the packaging of flexible solar cell devices. For the uneven covering and the existence of holes in the existing technology, the present application can realize uniform spreading of the solution on the perovskite film by adjusting the alcohol solution concentration of the acrylic-based molecules, and after light curing, the perovskite film is uniformly covered, and the hydrophobicity of the device can be effectively improved.

[0159] For the existing problem two, the solution of the acrylic-based molecules is coated on the surface of the perovskite layer, and the solubility of the molecules has no special requirement, and the types of the selected solvents are various, and the present application can be applied to different acrylic-based molecules. In addition, the post-processing method of the present application does not need to be annealed, and the process is mild; after the perovskite surface is coated with the solution, the light process is carried out at room temperature, the polymerization of the acrylic-based molecules is realized through light, and a uniform hydrophobic film is formed on the perovskite surface. The mild post-processing method of the perovskite film does not affect the nucleation and crystallization of the perovskite, and can improve the stability of the perovskite film, so as to improve the stability of the device, and has good repeatability.

[0160] Compared with the way of introducing polymerizable molecules in the perovskite layer in the existing problem two, the perovskite film is treated after being formed, which does not affect the nucleation and crystallization of the perovskite, and can effectively modify the surface defects of the perovskite film, and the types of the selected acrylic-based molecules are various. Meanwhile, the acrylic-based molecules in the present application are crosslinked through light, which avoids the damage of heating to the perovskite film, realizes the effective protection of the perovskite film, and improves the efficiency and working stability of the device.

[0161] In summary, the method for improving the stability of lead halide perovskite thin film and the product, after the formation of the perovskite thin film, the thin film is treated, and under room temperature conditions, the light curing method is adopted, which effectively avoids the damage of high temperature to the perovskite thin film, and enriches the types of acrylic acid-based molecules that can be selected, which has universality; through the regulation of the alcohol solution concentration of the selected molecules, the uniform coverage of the thin film is realized, which ensures the improvement of the water and oxygen resistance of the perovskite thin film, passivates the surface defects of the perovskite thin film, and can effectively improve the efficiency and stability of the perovskite solar cell device. In addition, the packaging method can be extended to various metal halide organic-inorganic perovskite layers, the packaging method is simple and controllable, the environmental requirements are low, large-area preparation can be realized, and it is also suitable for the packaging of flexible devices.

[0162] Finally, it should be noted that: the above embodiments 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 embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement for part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for improving the stability of a lead halide perovskite thin film, the method comprising: The alcohol solution of the polymerizable acrylic small molecule is covered on the surface of the crystallized perovskite material, and the perovskite polycrystalline thin film layer with improved hydrophobicity is obtained after light treatment under room temperature conditions, the concentration of the alcohol solution is 5-20 mg / mL, and the polymerizable acrylic small molecule is specifically: ​ (3-methoxyphenyl)methyl 2-propenoate; Or 2-oxo-1,2-diphenylethyl acrylate.

2. The method of claim 1, wherein the lead halide perovskite thin film is a CH3NH3PbI3 thin film. The alcohol solution is isopropanol, and the perovskite material is methylamine lead iodine, formamidinium lead iodine or cesium lead iodine.

3. The method of claim 1, wherein the lead halide perovskite thin film is a CH3NH3PbI3 thin film. The alcohol solution of the polymerizable acrylic small molecule is covered on the surface of the crystallized perovskite material by using a spin coating, spraying, soaking or blade coating process.

4. A solar cell device, characterized by, The device comprises a substrate (1), a transparent conductive cathode (2), an electron transport layer (3), a perovskite polycrystalline thin film layer (4), a hole transport layer (5) and an anode (6) which are stacked in sequence, the perovskite polycrystalline thin film layer (4) is prepared by the method for improving the stability of a lead halide perovskite thin film according to claim 1 or 2 or 3, and the thickness of the perovskite polycrystalline thin film layer (4) is 300-600 nm.

5. The solar cell device according to claim 4, characterized by The transparent conductive cathode (2) is made of inorganic material or organic conductive polymer, the inorganic material is one of indium tin oxide, zinc oxide or tin oxide, or one of gold, copper, silver or zinc, and the organic conductive polymer is polythiophene, polyethylene benzene sulfonic acid sodium or polyaniline.

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