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

Abstract

The invention belongs to the photovoltaic field, and particularly relates to a self-assembled monolayer (SAMs), a perovskite solar cell and a preparation method. The self-assembled monolayer comprises a self-assembled monolayer molecule and a thiophene organic matter. The thiophene organic matter forms a frame structure after SAMs film forming, the stability of SAMs can be improved, meanwhile, the carrier transport efficiency of a hole transport layer is improved through the pi-pi conjugation effect, and the performance of a device is improved.

Description

Technical Field

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

[0002] As the third-generation high-efficiency thin-film battery, the efficiency of perovskite solar cells has been rapidly improved in recent years and has exceeded 25%. At present, most high-efficiency perovskite solar cells or perovskite / silicon heterojunction tandem cells use self-assembled monolayers (SAMs) as the hole transport layer. Such materials can spontaneously anchor on the oxygen atoms of the substrate metal oxide and have strong hole transport and extraction capabilities as well as electron blocking capabilities. However, there are significant problems with the film-forming compactness, thermal stability, photo-stability, and the wettability of perovskite materials on their surface, resulting in low device repeatability.

[0003] In 2022, the Mariadriana team used the NiO x / SAMs double hole transport layer method to improve the compactness of SAMs. In 2023, the Tan Hairen team used the method of mixing 2PACz and MeO-2PACz SAMs to improve its compactness. However, the above methods only solve the problem of SAMs compactness unilaterally and cannot simultaneously alleviate other defects of SAMs, such as the wettability and stability of solution-processed perovskite on its surface. Moreover, these improvements have increased the process steps and prolonged the process time. Summary of the Invention

[0004] To solve the problems existing in the prior art, without adding an additional hole transport layer preparation process, by adding thiophene-based organic compounds to the SAMs layer, the thermal and photo-stability of the SAMs layer is increased, the carrier transport efficiency of the hole transport layer is improved, and at the same time, the wettability of the perovskite solution is also improved, thereby improving the device performance as a whole.

[0005] Specifically, the present invention provides a self-assembled monolayer, which comprises self-assembled monolayer molecules and thiophene-based organic compounds.

[0006] In one or more embodiments, the molecular weight of the thiophene-based organic compound ≤ 400; and / or the molecular weight of the thiophene-based organic compound ≥ 100.

[0007] In one or more embodiments, the thiophene-based organic compound is one or more selected from dithieno[3,2-b:2′,3′-d]thiophene, binaphtho[2,3-b:2′,3′-f]thieno[3,2-b]thiophene, bithiophene, 2,7-diphenyl[1]benzothieno[3,2-b][1]benzothiophene, dibenzothiophene, and α-quaterthiophene.

[0008] In one or more embodiments, the mass fraction of the thiophene-based organic compound in the self-assembled monolayer is 5% to 10%.

[0009] In one or more embodiments, the self-assembled monolayer molecules are selected from one or more of [2-(9H-carbazol-9-yl)ethyl]phosphonic acid, [2-(3,6-dimethyl-9H-carbazol-9-yl)ethyl]phosphonic acid, [2-(3,6-dimethoxy-9H-carbazol-9-yl)ethyl]phosphonic acid, [4-(9H-carbazol-9-yl)butyl]phosphonic acid, [4-(3,6-dimethyl-9H-carbazol-9-yl)butyl]phosphonic acid, and [4-(3,6-dimethoxy-9H-carbazol-9-yl)butyl]phosphonic acid.

[0010] In one or more embodiments, the mass fraction of the self-assembled monolayer molecules in the self-assembled monolayer is 90% to 95%.

[0011] In one or more embodiments, the thickness of the self-assembled monolayer is 1 to 3 nm.

[0012] Another aspect of the present invention provides a method for preparing the self-assembled monolayer described in any embodiment of the present invention. The method includes dispersing the self-assembled monolayer molecules and the thiophene-based organic compound in a solvent, stirring evenly to obtain a self-assembled monolayer solution, coating the self-assembled monolayer solution, and then annealing to obtain the self-assembled monolayer.

[0013] In one or more embodiments, in the self-assembled monolayer solution, the mass of the self-assembled monolayer molecules is 1 to 2 mg relative to each milliliter of the solvent.

[0014] In one or more embodiments, in the self-assembled monolayer solution, the mass of the thiophene-based organic compound is 0.05 to 0.1 mg relative to each milliliter of the solvent.

[0015] In one or more embodiments, the solvent is selected from one or both of ethanol and isopropanol.

[0016] In one or more embodiments, the ethanol is anhydrous ethanol.

[0017] In one or more embodiments, the isopropanol is anhydrous isopropanol.

[0018] In one or more embodiments, the coating is selected from one or more of spin coating, blade coating, spraying, spray pyrolysis, and slot coating.

[0019] In one or more embodiments, the temperature of the annealing is 80 to 100 °C.

[0020] In one or more embodiments, the time of the annealing is 3 to 10 min.

[0021] Another aspect of the present invention also provides a self-assembled monolayer prepared by the method described in any of the embodiments of the present invention.

[0022] Another aspect of the present invention also provides a perovskite solar cell, which comprises the self-assembled monolayer described in any one of the embodiments of the present invention.

[0023] In the present invention, an appropriate amount of thiophene-based organic matter is added to the SAMs solution. The S atoms in the thiophene-based organic matter increase the wettability of perovskite on SAMs through the affinity with Pb and Cs atoms in the perovskite. At the same time, the introduction of thiophene enhances the electron delocalization effect and the rigidity of adjacent units, enabling SAMs to be closely and orderly arranged. The thiophene-based organic matter forms a polymerization framework after the SAMs film is formed, increasing the stability of the SAMs layer. At the same time, the hole transport layer carrier transport efficiency is also improved through the intermolecular π-π conjugation effect. Thus, without adding new process steps, the device performance is improved in multiple aspects. Description of the Drawings

[0024] Figure 1 It is a structural diagram of a perovskite / heterojunction crystalline silicon tandem cell in some embodiments.

[0025] Figure 2 It is the repeatability test results of the solar cell modules in Examples 1-3 and Comparative Examples 1-3. Detailed Embodiments

[0026] 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 in the specification and claims. 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 definition in this specification shall prevail.

[0027] The theories or mechanisms described and disclosed herein, whether correct or incorrect, shall not limit the scope of the present invention in any way, that is, the content of the present invention can be implemented without being limited by any specific theory or mechanism.

[0028] As used herein, terms such as "comprising", "including", "containing" and similar terms encompass the meanings of "consisting essentially of" and "consisting of". For example, when the present disclosure states 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.

[0029] In this text, 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 a numerical range or percentage range should be regarded as having covered and specifically disclosed all possible sub-ranges and individual numerical values within the range (including integers and fractions).

[0030] In this text, unless otherwise specified, percentages refer to mass percentages, and ratios refer to mass ratios.

[0031] In this text, when describing embodiments or examples, it should be understood that they are 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 claims.

[0032] In this text, for the sake of brevity, 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 within the scope described in this specification.

[0033] The present invention provides a self-assembled monolayer comprising self-assembled monolayer molecules and thiophene-based organic compounds.

[0034] In the present invention, the thiophene-based organic compound refers to an organic compound containing structure. The molecular weight of the thiophene-based organic compound applicable to the present invention is ≤400; and / or the molecular weight of the thiophene-based organic compound is ≥100, preferably 100 - 400, such as 140, 184, 196, 330, 340, 392.

[0035] In some embodiments, the mass fraction of the thiophene-based organic compound in the self-assembled monolayer is 5% - 10%, such as 5.5%, 6%, 6.5%, 7%, 7.5%, 8%, 8.5%, 9%, 9.5%.

[0036] In some embodiments, the mass fraction of the self-assembled monolayer molecules in the self-assembled monolayer is 90% - 95%, such as 90.5%, 91%, 91.5%, 92%, 92.5%, 93%, 93.5%, 94%, 94.5%.

[0037] The thickness of the SAMs of the present invention is 1 - 3 nm, such as 1.2 nm, 1.4 nm, 1.6 nm, 1.8 nm, 2 nm, 2.2 nm, 2.4 nm, 2.6 nm, 2.8 nm.

[0038] In the present invention, the raw material of the perovskite structure material can be AX and BX 2, the A ion is a monovalent cation, and may include but not be limited to cesium ion (Cs + ), rubidium ion (Rb + ), methylammonium ion (CH 3 NH 3 + , MA + ) and formamidinium ion (CH(NH 2 ) 2 + , FA + ) of one or more; the B ion is a divalent cation, and may include but not be limited to lead ion (Pb 2+ ) and / or tin ion (Sn 2+ ); the X ion is a monovalent anion, and may include but not be limited to iodide ion (I - ), bromide ion (Br - ) and chloride ion (Cl - ) of one or more; preferably, in the perovskite structure material raw material, the A ion is selected from one or more of cesium ion, methylammonium ion and formamidinium ion; the B ion is lead ion; the X ion is iodide ion and / or bromide ion. Using the preferably perovskite structure material raw material is beneficial to prepare a ternary mixed organic halogen hybrid perovskite structure material, which has the most commercial prospects in terms of optoelectronic parameters and stability. In some embodiments, the perovskite structure material raw material is PbI 2 , FAI, MABr and CsBr.

[0039] In some embodiments, the chemical formula of the perovskite structure material of the present invention is ABX 3 ; the A ion may be selected from one or more of methylammonium ion, formamidinium ion, cesium ion and rubidium ion; the B ion may be selected from one or more of lead ion, tin ion, copper ion, zinc ion, gallium ion, tin ion and calcium ion; the X ion may be selected from F - , I - , Br - , Cl - and SCN - of one or more.

[0040] The electron transport layer of the present invention may be selected from one or more of 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 , TiSnO x , SnZnO x , fullerenes (such as C60 and C70) and fullerene derivatives (such as PCBM).

[0041] The electrode material of the present invention can be one or more selected from Au, Ag, Al, Cu, graphene, TCO materials, and nanocrystalline silicon, and the electrode preparation method includes one or more of, but is not limited to, spin coating, blade coating, evaporation coating, printing, spraying, spray pyrolysis, and slot die coating.

[0042] The present invention provides a method for preparing a self-assembled monolayer. The method includes dispersing self-assembled monolayer molecules and thiophene-based organic compounds in a solvent, stirring evenly to obtain a self-assembled monolayer solution, coating the self-assembled monolayer solution, and then annealing to obtain a self-assembled monolayer.

[0043] In the self-assembled monolayer solution, with respect to each milliliter of the solvent, the mass of the self-assembled monolayer molecules is 1 to 2 mg, such as 1.1 mg, 1.2 mg, 1.3 mg, 1.4 mg, 1.5 mg, 1.6 mg, 1.7 mg, 1.8 mg, 1.9 mg.

[0044] In the self-assembled monolayer solution, with respect to each milliliter of the solvent, the mass of the thiophene-based organic compounds is 0.05 to 0.1 mg, such as 0.055 mg, 0.06 mg, 0.065 mg, 0.07 mg, 0.075 mg, 0.08 mg, 0.085 mg, 0.09 mg.

[0045] In the present invention, the coating method can be one or more of spin coating, blade coating, spraying, spray pyrolysis, and slot die coating.

[0046] In the present invention, the annealing process is one-step annealing or two-step annealing. The annealing temperature can be 80 to 100 °C, such as 82 °C, 84 °C, 86 °C, 88 °C, 90 °C, 92 °C, 94 °C, 96 °C, 98 °C. In the present invention, the annealing time can be 3 to 10 min, such as 3.5 min, 4 min, 4.5 min, 5 min, 5.5 min, 6 min, 6.5 min, 7 min, 7.5 min, 8 min, 8.5 min, 9 min, 9.5 min.

[0047] In the present invention, the perovskite thin film can contain a perovskite structure substance, and the chemical formula of the perovskite structure substance is ABX 3 , where the A ion is a monovalent cation and can include, but is not limited to, cesium ion (Cs + ), rubidium ion (Rb + ), methylammonium ion (CH 3 NH 3 + , MA + ), and formamidinium ion (CH(NH 2 ) 2 + , FA +one or more of those in 2+ ) and / or tin ions (Sn 2+ );X ions are monovalent anions, and may include, but are not limited to, iodide ions (I - ), bromide ions (Br - ), and chloride ions (Cl - ), and one or more of them. For example, the perovskite-structured material may be Cs 0.05 MA 0.15 FA 0.8 PbI 2.28 Br 0.72 .

[0048] The present invention provides a perovskite solar cell comprising the perovskite thin film of the present invention. In the present invention, the perovskite solar cell may include a single-junction perovskite solar cell or a tandem perovskite solar cell; the perovskite solar cell may include a normal perovskite solar cell (n-i-p type perovskite solar cell) or an inverted perovskite solar cell (p-i-n type perovskite solar cell). Specifically, the perovskite solar cell may be a normal single-junction perovskite solar cell, an inverted single-junction perovskite solar cell, or a tandem perovskite solar cell.

[0049] In the present invention, the normal single-junction perovskite solar cell may sequentially include a transparent conductive substrate, an electron transport layer, a perovskite thin film, a hole transport layer, and a metal electrode. In the present invention, the inverted single-junction perovskite solar cell may sequentially include a transparent conductive substrate, a hole transport layer, a perovskite thin film, an electron transport layer, a hole blocking layer, and a metal electrode. In the present invention, the tandem perovskite solar cell may sequentially include a bottom electrode, a bottom cell, a tunneling layer, a perovskite top cell, and a top electrode, and the top cell may sequentially include a hole transport layer, a perovskite thin film, and an electron transport layer.

[0050] The present invention will be described below by way of specific embodiments. It should be understood that these embodiments are merely illustrative and are not intended to limit the scope of the present invention. The methods, reagents, and materials used in the embodiments are conventional methods, reagents, and materials in the art unless otherwise specified. The raw material compounds in the embodiments can be obtained through commercial channels.

[0051] Example 1

[0052] This example prepares an inverted broadband-gap perovskite / heterojunction silicon tandem solar cell with the structure as Figure 1 shown, and the specific steps are as follows:

[0053] Preparation of perovskite precursor solution: 39.5 mg of cesium iodide (CsI), 418 mg of formamidinium iodide (FAI), 51 mg of methylammonium bromide (MABr), 332 mg of lead bromide (PbBr 2 ) and 1057 mg of lead iodide (PbI 2 ) were mixed and added to 2 mL of a mixed solvent of N,N-dimethylformamide:methylphenylsulfoxide (MPSO) = 9:1 (v / v) for dissolution. It was filtered using a 0.22 μm oil filter to obtain a perovskite precursor solution with a concentration of 1.7 mol / L of Cs 0.05 MA 0.15 FA 0.8 PbI 2.28 Br 0.72 ;

[0054] (1) Preparation of the bottom cell:

[0055] n-type monocrystalline silicon was selected and cleaned using the RCA standard process. The back side of the silicon wafer was etched with a KOH aqueous solution of n(H 2 O):n(KOH):n(H 2 O 2 ) = 5:1:1 to prepare a pyramid structure with a depth of 3.5 μm. The front side was etched with a KOH aqueous solution of n(H 2 O):n(KOH):n(H 2 O 2 ) = 10:1:2 to prepare a pyramid structure with a depth of about 1 μm on the front side of the bone piece, obtaining a single-crystalline silicon substrate 1 with a thickness of 260 μm;

[0056] Using the plasma-enhanced chemical vapor deposition (PECVD) process, an intrinsic amorphous silicon layer (a-Si(i)) was deposited on both sides of the single-crystalline silicon substrate 1 at 200 °C to obtain a passivation layer 2 with a thickness of 5 nm;

[0057] Using the PECVD process, a boron-doped nc-Si(p) layer was deposited on the surface of the passivation layer 2 on the back side of the single-crystalline silicon substrate 1 at 200 °C to obtain a hole transport layer 3 with a thickness of 20 nm;

[0058] Using the PECVD process, a phosphorus-doped nc-Si(n) layer was deposited on the surface of the passivation layer 2 on the front side of the single-crystalline silicon substrate 1 at 200 °C to obtain an electron transport layer 6 with a thickness of 15 nm;

[0059] Furthermore, a bottom cell with a total thickness of 260 μm was obtained;

[0060] (2) Preparation of the back electrode and the composite layer: Indium oxide (In 2 O 3) A transparent electrode layer 4 with a thickness of 100 nm (sheet resistance is about 120 Ω / sq) is obtained; then silver is deposited on the surface of the transparent electrode layer 4 at a low temperature (150 °C) to obtain a silver grid line electrode 5 with a height of 8 μm and a width of 50 μm. The transparent electrode layer 4 and the silver grid line electrode 5 together form the back electrode; Indium zinc oxide (IZO) is deposited on the surface of the electron transport layer 6 by magnetron sputtering to obtain a composite layer 7 with a thickness of 10 nm;

[0061] (3) Preparation of the hole transport layer: Dissolve [4-(3,6-dimethoxy-9H-carbazol-9-yl)butyl]phosphonic acid (MeO-4PACZ) in isopropyl alcohol (IPA) to prepare a MeO-4PACZ solution with a concentration of 2 mg / mL. Add 1 mL of a 0.1 mg / mL solution of dinaphtho[2,3-b:2′,3′-f]thieno[3,2-b]thiophene (DNTT) (using IPA as the solvent) to 1 mL of the MeO-4PACZ solution, stir magnetically at 50 °C for 30 min, then filter it through a 0.22 μm polytetrafluoroethylene (PTFE) filter, and drop it on the IZO surface of the composite layer 7. Then spin-coat it at a speed of 4000 rpm for 15 s, and after the spin-coating is completed, transfer it to a heating plate at 100 °C for annealing for 5 min to obtain a hole transport layer 8 with a thickness of 1 nm;

[0062] (4) Spin-coat the perovskite precursor solution on the surface of the hole transport layer 8, and then transfer it to a heating plate at 100 °C for annealing for 30 min to obtain a perovskite light-absorbing layer 9 with a bandgap of 1.68 eV and a thickness of 500 nm;

[0063] (5) Preparation of the passivation layer: Deposit LiFx on the surface of the perovskite light-absorbing layer 9 by thermal evaporation to obtain a first passivation layer 10 with a thickness of 1 nm; By spin-coating method, take 100 μL of an isopropyl alcohol solution of ethylenediamine iodide (EDAI) with a concentration of 0.3 mg / ml, drop it on the surface of the LiFx first passivation layer 10, then spin-coat it at a speed of 4000 rpm for 15 s, and after the spin-coating is completed, transfer it to a heating plate at 100 °C for annealing for 5 min to obtain a second passivation layer 11 with a thickness of 5 nm; The first passivation layer 10 and the second passivation layer 11 together form the passivation layer;

[0064] (6) Preparation of the electron transport layer: Deposit fullerene (C60) on the surface of the second passivation layer 11 by thermal evaporation to obtain an electron transport layer 12 with a thickness of 10 nm;

[0065] (7) Preparation of the buffer layer: Deposit tin dioxide (SnO 2 ) on the surface of the electron transport layer 12 by atomic layer deposition (ALD) to obtain a buffer layer 13 with a thickness of 15 nm;

[0066] (8) Preparation of the top electrode: IZO was deposited on the surface of the buffer layer 13 by magnetron sputtering to obtain a transparent conductive layer 14 with a thickness of 50 nm; MgF was deposited on the transparent electrode layer 14 by thermal evaporation x , obtaining a full-area MgF antireflection layer 15 with a thickness of 110 nm x ; silver was deposited on the surface of the antireflection layer 15 through a mask by thermal evaporation to obtain a silver electrode 16 with a thickness of 400 nm; the transparent conductive layer 14, the antireflection layer 15, and the silver electrode 16 together form the top electrode, and at the same time, a reverse broadband-gap perovskite / heterojunction silicon tandem solar cell is obtained.

[0067] Example 2

[0068] Other conditions of this example are the same as those of Example 1, except that the thiophene organic compound used in this example is bianthiophene, and the concentration is 0.1 mg / ml.

[0069] Example 3

[0070] Other conditions of this Example 3 are the same as those of Example 1, except that the thiophene organic compound used in this example is dibenzothiophene, and the concentration is 0.05 mg / ml.

[0071] Comparative Example 1

[0072] Other conditions of this Comparative Example 1 are the same as those of Example 1, except that the hole transport layer of this comparative example only uses a 1 mg / mL DNTT solution (using IPA as the solvent) as the material of the hole transport layer 8.

[0073] Comparative Example 2

[0074] Other conditions of this Comparative Example 2 are the same as those of Example 1, except that DNTT is not added to the SAMs layer of this comparative example, but a DNTT passivation layer with a thickness of 2 nm is deposited between the hole transport layer 8 and the perovskite light-absorbing layer 9 by spin coating.

[0075] Comparative Example 3

[0076] Other conditions of this Comparative Example 3 are the same as those of Example 1, except that the SAMs layer of this comparative example only contains MeO-4PACZ and does not add DNTT.

[0077] Test Example 1

[0078] At 25 °C, under the standard solar spectrum of AM 1.5G and a light intensity of 100 mW / cm 2 , using a solar simulator, the voltage range was set to -0.1 - 2 V, and the performance (open-circuit voltage, short-circuit current density, fill factor, and photoelectric conversion efficiency) of the solar cell modules in Examples 1 - 3 and Comparative Examples 1 - 3 was measured. The specific results are shown in Table 1.

[0079] (1) Open-circuit voltage (Voc): The voltage value corresponding to the zero current.

[0080] (2) Short-circuit current density (Jsc): The current value when the voltage is zero is the short-circuit current (Isc), and the current magnitude per unit cell surface area is the short-circuit current density.

[0081] (3) Fill factor (FF): The ratio of the maximum output power (Pmax) of the battery to the product of the open-circuit voltage and the short-circuit current, and the calculation formula is (Pmax / Voc*Isc), where the maximum power point is the point where the battery output power reaches the maximum value.

[0082] (4) Photovoltaic conversion efficiency (PCE): The photovoltaic conversion efficiency refers to the ratio of the maximum output power to the incident light power (Pin), and the calculation formula is (Pmax / Pin)*100%.

[0083] (5) Maximum power point tracking throughout the process (MPP): Using the first measured maximum power of the battery P = FF·Voc·Isc as the denominator, and measuring the maximum power once after being placed in a normal atmospheric environment for 500 h as the numerator. The ratio represents the power attenuation of the solar cell module after this period of time.

[0084] Table 1: Photovoltaic performance test results of the solar cell modules of Examples 1-3 and Comparative Examples 1-3

[0085]

[0086] As can be seen from Table 1, in Example 1, by adding thiophene-based organic compounds as additives to the SAMs, the SAMs became denser, and the non-radiative recombination between layers was reduced through the cascade of components in the perovskite, thereby improving the FF and Voc of the device, and further improving the photovoltaic performance of the device.

[0087] Test Example 2

[0088] The solar cell modules of Examples 1-3 and Comparative Examples 1-3 were made into 19 groups of parallel solar cell modules respectively, and the PCE values of the nineteen groups of parallel solar cell modules of Examples 1-3 and Comparative Examples 1-3 were tested respectively. The test results are shown in Table 2 and Figure 2 as follows.

[0089] Table 2: Repeatability test results of the solar cell modules of Examples 1-3 and Comparative Examples 1-3

[0090] PCE Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 1 32.58 32.44 32.06 28.57 30.6 29.89 2 32.01 32.18 31.78 26.1 30.48 29.89 3 32.15 31.97 31.73 27.03 29.77 28.25 4 32.2 31.96 32 25.34 28.28 28.48 5 32.31 32 31.84 26.22 28.04 28.33 6 32.42 31.99 32.02 27.77 29.84 29.07 7 32.53 32.22 31.87 28.28 27.7 26.96 8 32.55 32.16 32.04 25.22 29.13 29.58 9 32.16 32.39 31.5 25.63 29.03 27.31 10 31.98 32.23 31.55 25.27 28.22 29.22 11 32 21.96 31.8 27.47 27.87 28.74 12 32.26 32.09 31.55 26.8 29.17 26.92 13 32.05 31.94 31.82 26.62 30 27.02 14 32.52 31.94 31.5 28.16 28.81 26.64 15 32.44 31.99 31.83 27.12 29.26 26.32 16 32.12 32.30 31.77 25.61 29.21 29.08 17 32.56 32.04 31.89 24.7 28.39 29.03 18 32.29 32.38 31.82 26.69 27.94 26.94 19 32.29 32.43 31.71 27.32 29.33 27.82

[0091] From Table 2 and Figure 2As can be seen, due to the addition of thiophene-based organic compounds, the SAMs are denser and more stable after modification, resulting in high repeatability of the photovoltaic devices prepared by the solution of the present invention.

Claims

1. A self-assembled monolayer, characterized in that The self-assembled monolayer comprises self-assembled monolayer molecules and thiophene organic matter.

2. The self-assembled monolayer according to claim 1, characterized in that The molecular weight of the thiophene organic compound is ≤400; and / or the molecular weight of the thiophene organic compound is ≥100.

3. The self-assembled monolayer according to claim 1, characterized in that The thiophene organic compound is one or more selected from dithiophene [3,2-b: 2′,3′-d] thiophene, dinaphtho [2,3-b: 2′,3′-f] thieno [3,2-b] thiophene, dithiophene, 2,7-diphenyl [1] benzothiophene [3,2-b] [1] benzothiophene, dibenzothiophene and α-quadithiophene; and / or The mass fraction of the thiophene organic matter in the self-assembled monolayer is 5% to 10%.

4. 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-dimethyl-9H-carbazole-9-yl)ethyl]phosphonic acid, [2-(3,6-dimethoxy-9H-carbazole-9-yl)ethyl]phosphonic acid, [4-(9H-carbazole-9-yl)butyl]phosphonic acid, [4-(3,6-dimethyl-9H-carbazole-9-yl)butyl]phosphonic acid and [4-(3,6-dimethoxy-9H-carbazole-9-yl)butyl]phosphonic acid; and / or The mass fraction of the self-assembled monolayer molecules in the self-assembled monolayer is 90% to 95%.

5. The self-assembled monolayer according to claim 1, characterized in that The thickness of the self-assembled monolayer is 1-3 nm.

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

7. The method according to claim 6, 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 1 to 2 mg per milliliter of solvent; In the self-assembled monolayer solution, the mass of the thiophene organic compound is 0.05 to 0.1 mg per milliliter of solvent; The solvent is one or both selected from ethanol and isopropanol, the ethanol is preferably anhydrous ethanol, and the isopropanol is preferably anhydrous isopropanol.

8. The method according to claim 6, 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 80-100°C; The annealing time is 3 to 10 minutes.

9. A self-assembled monolayer prepared by the method according to any one of claims 6 to 8.

10. A perovskite solar cell comprising the self-assembled monolayer according to any one of claims 1 to 5 and 9.

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