Self-assembled single-layer perovskite solar cell and preparation method thereof

Abstract

The invention belongs to the field of solar cells, and particularly discloses a self-assembled single-layer perovskite solar cell and a preparation method thereof. The self-assembled monolayer comprises a self-assembled monolayer molecule and a nanoparticle. Compared with the prior art, the nano-particles have strong interaction with water molecules, and the water and oxygen resistance of self-assembled single-layer molecules can be improved, so that the growth quality of perovskite on a self-assembled single-layer substrate is improved, a perovskite thin film with better quality is obtained, and the prepared perovskite solar cell has better performance and stability.

Description

Technical Field

[0001] The present invention belongs to the field of solar cells, and particularly relates to a self-assembled monolayer, a perovskite solar cell and a preparation method thereof. Background Art

[0002] Perovskite materials, especially organic-inorganic hybrid perovskites (ABX 3 , where A is an organic cation, B is a metal cation, and X is a halogen anion), have made very remarkable progress in the fields of optoelectronics and solar energy in recent years. Among them, wide-bandgap perovskite solar cells have broad application prospects in fields such as tandem cells and semi-transparent cells due to their adjustable bandgap characteristics, and are a hot research direction. In recent years, many researchers have made remarkable progress in aspects such as material design, device structure, efficiency improvement, and stability improvement. However, to achieve large-scale commercial applications, it is still necessary to further improve their performance and stability. The continuous research in this field will continue to promote the breakthrough of photovoltaic technology.

[0003] Self-assembled monolayers (SAMs) have indeed made remarkable progress in improving the power conversion efficiency (PCE) of perovskite solar cells (PSCs). The certified efficiency of single-junction perovskite solar cells has exceeded 26%, the certified efficiency of wide-bandgap perovskite solar cells has exceeded 20.7%, and the certified PCE of perovskite / silicon tandem solar cells (TSCs) has reached 33.9%, which is still far below the theoretical efficiency limit (45% for two-terminal tandem). One of the reasons for this difference is the low performance of wide-bandgap PSCs (WB-PSCs) due to severe phase separation and open-circuit voltage (VOC) losses, which are attributed to defect-induced non-radiative recombination losses. In addition, these high-efficiency solar cells are basically prepared in a glove box protected by an inert atmosphere, which will undoubtedly increase the production cost of perovskite solar cells in the future industrialization process. Currently, the efficiency of inverted solar cells prepared in air lags far behind that of cells prepared in a glove box.

[0004] The lower interface of the perovskite thin film has a great influence on the growth of perovskite crystals. Therefore, it is of great research significance to modify the buried interface of perovskite materials. Preparing functionalized SAMs in an air environment as the bottom interface of wide-bandgap perovskite thin films is an important way to solve the low efficiency of inverted solar cells prepared in air.

[0005] Perovskite / silicon tandem solar cells have great potential in achieving high power conversion efficiency at low cost. However, it is still challenging to achieve large-scale manufacturing of wide-bandgap perovskites in air without inert gas protection.

[0006] The research team at Nanjing University has demonstrated that n-butanol, with low polarity and a medium evaporation rate, can not only mitigate the harmful effects of moisture in the air during large-scale manufacturing but also improve the uniformity of perovskite thin films. This method has achieved a power conversion efficiency of 29.4% (certified value: 28.7%) for planar-textured perovskite / silicon tandem solar cells.

[0007] The team at Central South University has disclosed a method for preparing the perovskite active layer of perovskite solar cells in air. When using a two-step method to prepare the perovskite active layer, an appropriate amount of pyridine-based organic small molecules is added to the lead iodide solution as an additive. Through this method, the influence of humidity on the preparation of the perovskite active layer can be reduced. Under the conditions of natural air with high humidity, a high-quality perovskite active layer can still be prepared, resulting in high-efficiency perovskite solar cells. The preparation of high-efficiency perovskite solar cells in air can be achieved, reducing their preparation cost and facilitating the industrialization of perovskite solar cells.

[0008] The above research mainly focuses on the modification of the perovskite active layer prepared in air. However, SAMs molecules are vulnerable to the influence of water and oxygen in the air, leading to a decrease in device performance. Currently, SAMs are easily affected by environmental water and oxygen during the preparation process in air, resulting in poor anchoring effects and thus poor performance of perovskite solar cells. Therefore, there is great research value in how to prepare high-quality SAMs in air. Summary of the Invention

[0009] In view of the above problems in the prior art, the present invention proposes a new SAMs doping process to improve the anchoring effect of SAMs in air, solve the problem of poor quality of SAMs prepared in air, thereby enhancing the performance of perovskite solar cells, and providing a new solution for the preparation of SAMs in large-scale commercial perovskite solar cells.

[0010] Specifically, one aspect of the present invention provides a self-assembled monolayer, which comprises self-assembled monolayer molecules and nanoparticles, and the nanoparticles are one or more selected from cellulose nanoparticles, hydrogel nanoparticles, chitosan nanoparticles, sodium polyacrylate nanoparticles, and montmorillonite nanoparticles.

[0011] In one or more embodiments, the self-assembled monolayer molecules are one or more selected from [2-(9H-carbazol-9-yl)ethyl]phosphonic acid, [2-(3,6-dimethoxy-9H-carbazol-9-yl)ethyl]phosphonic acid, [4-(3,6-dimethyl-9H-carbazol-9-yl)butyl]phosphonic acid, 4-mercaptopyridine, 2,3,5,6-tetrafluoro-7,7',8,8'-tetracyanoquinodimethane, and polyethyleneimine ethoxy bromide.

[0012] In one or more embodiments, the mass fraction of the self-assembled monolayer molecules in the self-assembled monolayer is 70% to 99%.

[0013] In one or more embodiments, the mass fraction of the nanoparticles in the self-assembled monolayer is 1% to 30%.

[0014] In one or more embodiments, the particle size of the nanoparticles is 1 to 100 nm.

[0015] In one or more embodiments, the thickness of the self-assembled monolayer is 1 to 20 nm.

[0016] Another aspect of the present invention provides a method for preparing the self-assembled monolayer according to any one of the embodiments of the present invention. The method includes dispersing self-assembled monolayer molecules and nanoparticles in a solvent to obtain a self-assembled monolayer solution, coating the self-assembled monolayer solution, and then annealing to obtain the self-assembled monolayer.

[0017] In one or more embodiments, in the self-assembled monolayer solution, the mass of the self-assembled monolayer molecules is 0.1 to 200 mg relative to each milliliter of the solvent.

[0018] In one or more embodiments, in the self-assembled monolayer solution, the mass of the nanoparticles is 0.001 to 100 mg relative to each milliliter of the solvent.

[0019] In one or more embodiments, the solvent is one or both selected from ethanol and isopropanol.

[0020] In one or more embodiments, the coating is one or more selected from spin coating, blade coating, spray coating, spray pyrolysis, and slot die coating.

[0021] In one or more embodiments, the temperature of the annealing is 50 to 200 °C.

[0022] In one or more embodiments, the time of the annealing is 2 to 200 min.

[0023] Another aspect of the present invention provides a self-assembled monolayer prepared by the method according to any one of the embodiments of the present invention.

[0024] Another aspect of the present invention provides a perovskite solar cell, which includes the self-assembled monolayer according to any one of the embodiments of the present invention.

[0025] In one or more embodiments, the perovskite solar cell further includes a hole transport layer and a perovskite light-absorbing layer, and two surfaces of the self-assembled monolayer are respectively in contact with the hole transport layer and the perovskite light-absorbing layer.

[0026] In one or more embodiments, the perovskite solar cell sequentially includes a conductive substrate, a hole transport layer, a self-assembled monolayer, a perovskite light-absorbing layer, an electron transport layer, and a back electrode.

[0027] The present invention proposes a new SAMS preparation process. On the original basis, only trace amounts of water-absorbing nanoparticles are doped. The water-absorbing nanoparticles have a strong interaction with water molecules, and without the introduction of additional complex processes, the water and oxygen resistance of SAMs molecules can be improved, thereby improving the growth quality of perovskite on the modified SAMs substrate, obtaining a perovskite thin film with better quality, and enhancing the performance and stability of the prepared perovskite solar cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a schematic structural diagram of a wide-bandgap perovskite solar cell in some embodiments of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0029] To enable those skilled in the art to understand the features and effects of the present invention, the following provides a general description and definition of the terms and expressions mentioned herein. Unless otherwise specified, all technical and scientific terms used herein shall have the ordinary meaning understood by those skilled in the art regarding the present invention. In case of conflict, the definitions in this specification shall prevail.

[0030] The theories or mechanisms described and disclosed herein, whether correct or incorrect, shall not in any way limit the scope of the present invention, that is, the content of the present invention can be implemented without being limited by any specific theory or mechanism.

[0031] In this article, terms such as "comprising", "including", "containing" and similar expressions cover the meanings of "consisting essentially of..." and "consisting of...". For example, when it is disclosed herein that "A comprises B and C", it should be considered that "A consists essentially of B and C" and "A consists of B and C" have been disclosed herein.

[0032] In this article, all features defined in the form of numerical ranges or percentage ranges, such as numerical values, quantities, contents, and concentrations, are only for the sake of brevity and convenience. Accordingly, the description of numerical ranges or percentage ranges should be regarded as having covered and specifically disclosed all possible sub-ranges and individual numerical values within the range (including integers and fractions).

[0033] In this article, unless otherwise specified, the percentage refers to the mass percentage, and the ratio refers to the mass ratio.

[0034] In this document, when describing an embodiment or example, it should be understood that it is not used to limit the present invention to these embodiments or examples. On the contrary, all alternatives, improvements, and equivalents of the methods and materials described in the present invention can be covered within the scope defined by the present invention.

[0035] In this document, for the sake of brevity of description, not all possible combinations of all technical features in each embodiment or example are described. Therefore, as long as there is no contradiction in the combination of these technical features, the technical features in each embodiment or example can be combined arbitrarily, and all possible combinations should be considered as the scope described in this specification.

[0036] In the present invention, the transparent conductive oxide layer used for the conductive substrate can be selected from one or more of ITO, IZO, FTO, AZO, GZO, ZnO, IGZO, In 2 O 3 、WO 3 and CuAIO 2 and the like.

[0037] The present invention provides a self-assembled monolayer, which comprises self-assembled monolayer molecules and nanoparticles, and the nanoparticles are selected from one or more of cellulose nanoparticles, hydrogel nanoparticles, chitosan nanoparticles, sodium polyacrylate nanoparticles, and montmorillonite nanoparticles.

[0038] In the present invention, the thickness of the self-assembled monolayer is 1 to 20 nm, such as 2 nm, 4 nm, 6 nm, 8 nm, 10 nm, 12 nm, 14 nm, 16 nm, 18 nm.

[0039] In the present invention, the mass fraction of the self-assembled monolayer molecules in the self-assembled monolayer is 70% to 99%, such as 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%.

[0040] In the present invention, the mass fraction of the nanoparticles in the self-assembled monolayer is 1% to 30%, such as 2%, 4%, 6%, 8%, 10%, 12%, 14%, 16%, 18%, 20%, 22%, 24%, 26%, 28%.

[0041] In the present invention, the particle size of the nanoparticles is preferably 1 to 100 nm, such as 2 nm, 4 nm, 6 nm, 8 nm, 10 nm, 12 nm, 14 nm, 16 nm, 18 nm, 20 nm, 22 nm, 24 nm, 26 nm, 28 nm, 30 nm, 32 nm, 34 nm, 36 nm, 38 nm, 40 nm, 42 nm, 44 nm, 46 nm, 48 nm, 50 nm, 52 nm, 54 nm, 56 nm, 58 nm, 60 nm, 62 nm, 64 nm, 66 nm, 68 nm, 70 nm, 72 nm, 74 nm, 76 nm, 78 nm, 80 nm, 82 nm, 84 nm, 86 nm, 88 nm, 90 nm, 92 nm, 94 nm, 96 nm, 98 nm.

[0042] In the present invention, the material of the hole transport layer can be selected from one or more of Spiro-OMeTAD, poly(triarylamine), copper phthalocyanine, tris(4-carbazol-9-ylphenyl)amine, (poly(3,4-ethylenedioxythiophene):polystyrenesulfonic acid), poly(trihexylthiophene), PolyTPD, nickel oxide, copper thiocyanate, vanadium pentoxide, molybdenum trioxide, and tungsten trioxide.

[0043] In the present invention, the self-assembled monolayer molecules can be selected from one or more of [2-(9H-carbazol-9-yl)ethyl]phosphonic acid, [2-(3,6-dimethoxy-9H-carbazol-9-yl)ethyl]phosphonic acid, [4-(3,6-dimethyl-9H-carbazol-9-yl)butyl]phosphonic acid, 4-mercaptopyridine, 2,3,5,6-tetrafluoro-7,7',8,8'-tetracyanoquinodimethane, and polyethyleneimine ethoxy bromide.

[0044] The hole transport layer of the present invention can be prepared by the following steps:

[0045] Disperse the hole transport material in a solvent to obtain a hole transport material solution, coat the hole transport material solution, and then anneal to obtain the hole transport layer.

[0046] In the hole transport material solution, the mass of the hole transport material is 0.1 to 200 mg per milliliter of solvent, such as 0.2 mg, 0.3 mg, 0.4 mg, 0.5 mg, 0.6 mg, 0.7 mg, 0.8 mg, 0.9 mg, 1 mg, 5 mg, 10 mg, 15 mg, 20 mg, 25 mg, 30 mg, 35 mg, 40 mg, 45 mg, 50 mg, 55 mg, 60 mg, 65 mg, 70 mg, 75 mg, 80 mg, 85 mg, 90 mg, 95 mg, 100 mg, 105 mg, 110 mg, 115 mg, 120 mg, 125 mg, 130 mg, 135 mg, 140 mg, 145 mg, 150 mg, 155 mg, 160 mg, 165 mg, 170 mg, 175 mg, 180 mg, 195 mg.

[0047] The self-assembled monolayer of the present invention can be prepared by the following steps:

[0048] Disperse the self-assembled monolayer molecules and nanoparticles in a solvent to obtain a self-assembled monolayer solution, coat the self-assembled monolayer solution, and then anneal to obtain the self-assembled monolayer.

[0049] In the self-assembled monolayer solution, the mass of the self-assembled monolayer molecules is 0.1 to 200 mg per milliliter of solvent, such as 0.2 mg, 0.3 mg, 0.4 mg, 0.5 mg, 0.6 mg, 0.7 mg, 0.8 mg, 0.9 mg, 1 mg, 5 mg, 10 mg, 15 mg, 20 mg, 25 mg, 30 mg, 35 mg, 40 mg, 45 mg, 50 mg, 55 mg, 60 mg, 65 mg, 70 mg, 75 mg, 80 mg, 85 mg, 90 mg, 95 mg, 100 mg, 105 mg, 110 mg, 115 mg, 120 mg, 125 mg, 130 mg, 135 mg, 140 mg, 145 mg, 150 mg, 155 mg, 160 mg, 165 mg, 170 mg, 175 mg, 180 mg, 195 mg.

[0050] In the self-assembled monolayer solution, the mass of the nanoparticles is 0.001 to 100 mg per milliliter of solvent, such as 0.002 mg, 0.003 mg, 0.004 mg, 0.005 mg, 0.006 mg, 0.007 mg, 0.008 mg, 0.009 mg, 0.01 mg, 0.02 mg, 0.03 mg, 0.04 mg, 0.05 mg, 0.06 mg, 0.07 mg, 0.08 mg, 0.09 mg, 0.1 mg, 0.2 mg, 0.3 mg, 0.4 mg, 0.5 mg, 0.6 mg, 0.7 mg, 0.8 mg, 0.9 mg, 1 mg, 5 mg, 10 mg, 15 mg, 20 mg, 25 mg, 30 mg, 35 mg, 40 mg, 45 mg, 50 mg, 55 mg, 60 mg, 65 mg, 70 mg, 75 mg, 80 mg, 85 mg, 90 mg, 95 mg.

[0051] In the method for preparing the hole transport layer or self-assembled monolayer of the present invention, the solvent is one or both selected from ethanol and isopropanol.

[0052] In the method for preparing the hole transport layer or self-assembled monolayer of the present invention, the coating method can be one or more selected from spin coating, blade coating, spraying, spray pyrolysis, and slot coating.

[0053] In the method for preparing the hole transport layer or self-assembled monolayer of the present invention, the annealing temperature is 50 to 200 °C, such as 55 °C, 60 °C, 65 °C, 70 °C, 75 °C, 80 °C, 85 °C, 90 °C, 95 °C, 100 °C, 105 °C, 110 °C, 115 °C, 120 °C, 125 °C, 130 °C, 135 °C, 140 °C, 145 °C, 150 °C, 155 °C, 160 °C, 165 °C, 170 °C, 175 °C, 180 °C, 185 °C, 190 °C, 195 °C.

[0054] In the method for preparing the hole transport layer or self-assembled monolayer of the present invention, the annealing time is 2 to 200 min, such as 4 min, 6 min, 8 min, 10 min, 15 min, 20 min, 25 min, 30 min, 35 min, 40 min, 45 min, 50 min, 55 min, 60 min, 65 min, 70 min, 75 min, 80 min, 85 min, 90 min, 95 min, 100 min, 105 min, 110 min, 115 min, 120 min, 125 min, 130 min, 135 min, 140 min, 145 min, 150 min, 155 min, 160 min, 165 min, 170 min, 175 min, 180 min, 185 min, 190 min, 195 min.

[0055] In the present invention, the chemical formula of the perovskite structure material is ABX 3 ; the A ion can be one or more selected from methylammonium ion, formamidinium ion, cesium ion and rubidium ion; the B ion can be one or more selected from lead ion, tin ion, copper ion, zinc ion, gallium ion, tin ion and calcium ion; the X ion can be one or more selected from F - , I - , Br - , Cl - and SCN - .

[0056] In the present invention, the thickness of the perovskite thin film can be 0.01 - 10 μm, such as 0.02 μm, 0.03 μm, 0.04 μm, 0.05 μm, 0.06 μm, 0.07 μm, 0.08 μm, 0.09 μm, 0.1 μm, 0.2 μm, 0.3 μm, 0.4 μm, 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm, 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm.

[0057] The solvent used in the perovskite precursor solution of the present invention can be one or more selected from DMF, DMSO, NMP, acetonitrile, methoxyethanol and ionic liquid.

[0058] The electron transport layer of the present invention can be one or more selected from n-type single crystal silicon, n-type polycrystalline silicon, n-type amorphous silicon, TiO 2 , SnO 2 , ZnO, ZrO 2 , GZO, IZO, FTO, ITO, BaSnO 3 , TiSnOx, SnZnOx, fullerene (such as C60 and C70) and fullerene derivatives (such as PCBM).

[0059] The electrode material of the present invention can be one or more selected from Au, Ag, Al, Cu, graphene, TCO material and nanocrystalline silicon, and the electrode preparation methods include but are not limited to one or more of spin coating, blade coating, evaporation coating, printing, spraying, spray pyrolysis and slot die coating.

[0060] The present invention will be described below by way of specific examples. It should be understood that these examples are only illustrative and are not intended to limit the scope of the present invention. The methods, reagents and materials used in the examples are conventional methods, reagents and materials in the art unless otherwise specified. The compounds in the examples can all be obtained through commercial channels.

[0061] Example 1

[0062] As Figure 1 shown, a wide-bandgap perovskite solar cell is prepared in the order of a conductive substrate, a hole transport layer, a self-assembled monolayer (SAMs), a perovskite light-absorbing layer, an electron transport layer, and a back electrode. The specific steps are as follows:

[0063] (1) Pretreatment of the conductive substrate: Provide ITO conductive glass with a thickness of 0.5 mm, perform laser P1 scribing on the ITO glass, then clean it and dry it with nitrogen to obtain a clean conductive substrate;

[0064] (2) Preparation of the hole transport layer: Sputter NiOx on the clean conductive substrate by PVD method with a sputtering power of 200 W to obtain a NiOx layer with a thickness of 10 nm;

[0065] (3) Preparation of the SAMs layer: Prepare a self-assembled monolayer with a thickness of 10 nm on the surface of the NiOx layer by spin coating method: Disperse (2-(9H-carbazol-9-yl)ethyl)phosphonic acid and hydroxypropyl methylcellulose (Sigma-Aldrich; H7509; particle size 1-50 nm) in the solvent isopropanol to obtain a self-assembled monolayer solution. In the self-assembled monolayer solution, the mass of the self-assembled monolayer molecules is 0.99 mg and the mass of the cellulose nanoparticles is 0.01 mg per milliliter of the solvent; coat the self-assembled monolayer solution, and then anneal it at 120 °C for 20 min to obtain a self-assembled monolayer. In the self-assembled monolayer, the mass fraction of the self-assembled monolayer molecules is 99% and the mass fraction of the cellulose nanoparticles is 1%;

[0066] (4) Preparation of the perovskite light-absorbing layer: In an air environment, coat the prepared perovskite precursor solution on the SAMs layer by slot-die coating method; in the slot-die coating process, the coating height is 100 μm, the coating liquid output is set to 90 μL, the injection speed of the plunger pump is 50 μL / s, the moving speed of the adjustment platform is 15 mm / s, the preparation ambient temperature is 25 ± 5 °C, and the ambient humidity is 20 ± 5% RH; after the coating is completed to form a perovskite wet film, immediately move the wet film to a vacuum extraction chamber for vacuum drying. The vacuum pressure is 0.1 Pa and the vacuum time is 10 s. Place the dried film on a hot stage with a temperature set at 150 °C and anneal it for 30 min to obtain a perovskite film with a thickness of 700 nm.

[0067] (5) Preparation of the electron transport layer: Evaporate a C60 layer with a thickness of 10 nm and a BCP layer with a thickness of 10 nm on the perovskite light-absorbing layer in sequence by thermal evaporation method. The C60 layer and the BCP layer together form the electron transport layer;

[0068] (6) Preparation of the back electrode: Evaporate Ag with a thickness of 90 nm on the electron transport layer by thermal evaporation method to obtain the back electrode and obtain the perovskite solar cell module.

[0069] Example 2

[0070] The wide-bandgap perovskite solar cell of Example 2 was prepared by a method similar to that of Example 1, except that the cellulose nanoparticles were replaced with an equal mass of hydrogel nanoparticles (Beijing University of Science and Technology Nano; 10 - 100 nm).

[0071] Example 3

[0072] The wide-bandgap perovskite solar cell of Example 3 was prepared by a method similar to that of Example 1, except that the cellulose water-absorbing nanoparticles were replaced with an equal mass of chitosan water-absorbing nanoparticles (Jike JK-09-018 chitosan copper sulfide nanoparticles; 10 - 100 nm).

[0073] Example 4

[0074] The wide-bandgap perovskite solar cell of Example 4 was prepared by a method similar to that of Example 1, except that the cellulose water-absorbing nanoparticles were replaced with an equal mass of sodium polyacrylate water-absorbing nanoparticles (Wuxi Fengmin; 10 - 100 nm).

[0075] Example 5

[0076] The wide-bandgap perovskite solar cell of Example 5 was prepared by a method similar to that of Example 1, except that the cellulose water-absorbing nanoparticles were replaced with an equal mass of montmorillonite water-absorbing nanoparticles (Henan Banglai, 10 - 100 nm).

[0077] Comparative Example 1

[0078] The wide-bandgap perovskite solar cell of Comparative Example 1 was prepared by a method similar to that of Example 1, except that the water-absorbing nanoparticles were not doped in the SAMs.

[0079] Test Example

[0080] PL Mapping is a photoluminescence scanning technique used to characterize the properties and defects of semiconductor materials. PL Mapping obtains the fluorescence intensity information of each point on the sample surface by scanning the photoluminescence spectrum of the sample surface and displays it in the form of a 3D image. In the present invention, the PL maping technique was used. By using a xenon lamp solar simulator (Enlitech, SS-F5), in an N 2 filled glove box at room temperature, the J-V characteristics of the photovoltaic devices of the wide-bandgap perovskite solar cells prepared in Examples 1 - 5 and Comparative Example 1 were measured: The power of the light was calibrated to 100 mW / cm² through a silicon reference cell (with a KG2 filter). 2The broadband perovskite solar cells prepared in Examples 1-5 and Comparative Example 1 were measured using a Keithley 2400 source meter in a scanning mode of reverse scan (1.20 V to -0.01 V) and forward scan (-0.01 V to 1.20 V), where the scan rate was 0.01 V / s and the delay time was 10 ms (no pretreatment was required before measurement), and the effective area was defined and characterized as a small area of 0.0414 cm 2 and a centimeter area of 1.00 cm 2 , and the stable current density output (extracted from the reverse scan J-V curve) at the maximum power point (MPP) bias was monitored to perform stable power output. The test results are shown in Table 1.

[0081] The open-circuit voltage (Voc), short-circuit current density (Jsc), fill factor (FF), and power conversion efficiency (PCE) of the broadband perovskite solar cells prepared in Examples 1-5 and Comparative Example 1 were measured using a solar simulator, and the measurement results are shown in Table 2.

[0082] As can be seen from Table 1, the PL intensity of the perovskite films (Examples 1-5) prepared on the modified SAMs substrate with the water-absorbing nanoparticles of the present invention was significantly improved, indicating that the modification of SAMs with the water-absorbing nanoparticles helped to reduce the non-radiative recombination efficiency of the perovskite material, and the electrons and holes of the perovskite film prepared on the SAMs modified with the water-absorbing nanoparticles were effectively separated; as can be seen from Table 2, the device efficiency of the broadband perovskite solar cells prepared on the modified SAMs substrate with the water-absorbing nanoparticles of the present invention was improved, especially the parameters such as Jsc, Voc, and FF were significantly improved.

[0083] Table 1: PL maping test of the broadband perovskite solar cells prepared in Examples 1-5 and Comparative Example 1

[0084] Perovskite thin film PL maping Comparative Example 1 9638 Example 1 49762 Example 2 45827 Example 3 41092 Example 4 38654 Example 5 29376

[0085] Table 2: Cell performance parameters of the broadband perovskite solar cells prepared in Examples 1-5 and Comparative Example 1

[0086] Device Voc (V) <![CDATA[Jsc (mA / cm 2 )]]> FF (%) PCE (%) Comparative Example 1 1.194 18.11 70.62 15.27 Example 1 1.239 20.21 81.05 20.30 Example 2 1.235 19.99 80.23 19.81 Example 3 1.228 19.78 78.27 19.01 Example 4 1.218 20.43 77.82 19.36 Example 5 1.211 19.62 76.98 18.29

Claims

1. A self-assembled monolayer, characterized in that The self-assembled monolayer comprises self-assembled monolayer molecules and nanoparticles, wherein the nanoparticles are one or more selected from cellulose nanoparticles, hydrogel nanoparticles, chitosan nanoparticles, sodium polyacrylate nanoparticles and montmorillonite nanoparticles.

2. The self-assembled monolayer according to claim 1, characterized in that The self-assembled monolayer molecules are selected from one or more of [2-(9H-carbazole-9-yl)ethyl]phosphonic acid, [2-(3,6-dimethoxy-9H-carbazole-9-yl)ethyl]phosphonic acid, [4-(3,6-dimethyl-9H-carbazole-9-yl)butyl]phosphonic acid, 4-mercaptopyridine, 2,3,5,6-tetrafluoro-7,7',8,8'-tetracyanodimethyl-p-benzoquinone and polyethyleneimine ethoxy bromide; The mass fraction of the self-assembled monolayer molecules in the self-assembled monolayer is 70% to 99%.

3. The self-assembled monolayer according to claim 1, characterized in that The mass fraction of the nanoparticles in the self-assembled monolayer is 1% to 30%; The particle size of the nanoparticles is 1 to 100 nm.

4. The self-assembled monolayer according to claim 1, characterized in that The thickness of the self-assembled monolayer is 1-20 nm.

5. A method for preparing the self-assembled monolayer according to any one of claims 1 to 4, characterized in that: The method comprises dispersing self-assembled monolayer molecules and nanoparticles in a solvent to obtain a self-assembled monolayer solution, coating the self-assembled monolayer solution, and then annealing to obtain a self-assembled monolayer.

6. The method according to claim 5, characterized in that The method has one or more of the following features: In the self-assembled monolayer solution, the mass of the self-assembled monolayer molecules is 0.1 to 200 mg per milliliter of solvent; In the self-assembled monolayer solution, the mass of the nanoparticles is 0.001 to 100 mg per milliliter of solvent; The solvent is one or two selected from ethanol and isopropanol.

7. The method according to claim 5, characterized in that The method has one or more of the following features: The coating is one or more selected from spin coating, blade coating, spray coating, spray pyrolysis and slit coating; The annealing temperature is 50-200°C; The annealing time is 2 to 200 minutes.

8. A self-assembled monolayer prepared by the method according to any one of claims 5 to 7.

9. A perovskite solar cell comprising the self-assembled monolayer according to any one of claims 1 to 4 and 8.

10. The perovskite solar cell according to claim 9, characterized in that: The perovskite solar cell comprises a conductive substrate, a hole transport layer, a self-assembled monolayer, a perovskite light absorption layer, an electron transport layer and a back electrode in sequence.

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