Method for forming self-assembled monomolecular layer, preparation method of perovskite solar cell and perovskite solar cell

Abstract

The invention provides a method for forming a self-assembled monomolecular layer, a preparation method of a perovskite solar cell and the solar cell obtained by the method. The method for forming the self-assembled monomolecular layer comprises the following steps: dissolving an SAM material in a composite solvent to form an SAM solution; coating an SAM solution on a substrate to form an SAM wet film; and vacuum flash evaporation treatment is conducted on the substrate with the SAM wet film, and the composite solvent comprises an A-type solvent used for dissolving an SAM material and a B-type solvent capable of improving the film forming characteristic of the SAM layer. According to the method for forming the self-assembled monomolecular layer and the preparation method of the perovskite solar cell disclosed by the invention, the uniformity and coverage rate of the SAM layer and the uniformity of the subsequent perovskite layer can be improved, and the purpose of improving the efficiency of a solar device is finally achieved.

Description

Technical Field

[0001] The present disclosure relates to the technical field of solar cells, and in particular to a method for forming a self-assembled monolayer, a method for preparing a perovskite solar cell, and a perovskite solar cell. Background Art

[0002] Perovskite solar cells utilize perovskite-type organometallic halide semiconductors as light-absorbing materials. Perovskite materials tend to have low carrier recombination probability and high carrier mobility, resulting in long carrier diffusion distances and lifetimes, resulting in perovskite solar cells with excellent photoelectric performance.

[0003] In inverse perovskite solar cells, the uniformity and stability of the self-assembled monolayer (SAM) are crucial for improving cell efficiency. Many SAM materials, such as [4-(3,6-dimethyl-9H-carbazol-9-yl)butyl]phosphonic acid (Me-4PACz), easily aggregate to form polymers due to intermolecular π-π stacking interactions and weak coordination between the anchoring groups and the substrate (e.g., phosphonic acid groups and ITO). This introduces trap states at the buried interface, increasing non-radiative recombination and reducing the turn-on voltage. Furthermore, low SAM coverage can also result in leakage current.

[0004] In addition, the process of forming the SAM layer usually includes: coating a solution containing the SAM material on the substrate, and then annealing it. If the annealing temperature is too high or the time is too long, it may cause some of the SAM material to decompose or desorb the SAM material from the substrate, further reducing the short-circuit current and photoelectric conversion efficiency of the final battery device. For example, when the annealing temperature is higher than 130°C, the decomposition rate of the carboxyl group in Me-4PACz can reach 15-20%, resulting in a decrease of 0.38eV in the interface dipole moment. Due to the limitations of the operating conditions in the annealing process, the application of high-boiling-point solvents in the preparation of SAM layers is limited. Summary of the Invention

[0005] In order to solve the above problems, the present disclosure provides a method for forming a self-assembled monolayer, comprising the following steps:

[0006] dissolving the SAM material in the composite solvent to form a SAM solution;

[0007] coating a SAM solution on a substrate to form a SAM wet film; and

[0008] The substrate with SAM wet film is vacuum flash-evaporated.

[0009] The composite solvent comprises a type A solvent for dissolving the SAM material and a type B solvent capable of improving the film-forming properties of the SAM layer.

[0010] According to the method for forming a self-assembled monolayer described in the present disclosure, the type A solvent can be selected from one or more of isopropyl alcohol (IPA), ethanol, n-butanol or chlorobenzene.

[0011] According to the method for forming a self-assembled monolayer of the present disclosure, the type B solvent comprises a solvent having a boiling point higher than 130° C. The solvent having a boiling point higher than 130° C. can be selected from one or more of ethylene glycol, dimethyl sulfoxide (DMSO), and N,N-dimethylformamide (DMF).

[0012] According to the method for forming a self-assembled monolayer of the present disclosure, the ratio of the type A solvent to the type B solvent in the composite solvent is 1:9 to 9:1.

[0013] According to the method for forming a self-assembled monolayer described in the present disclosure, the temperature of the vacuum flash evaporation treatment is 10° C. to 50° C., the pressure is 5 Pa to 1000 Pa, and the holding time is 20 s to 120 s.

[0014] The method for forming a self-assembled monolayer according to the present disclosure further includes performing an annealing process after the vacuum flash evaporation process.

[0015] According to the method for forming a self-assembled monolayer described in the present disclosure, the temperature of the annealing treatment is 80° C. to 120° C., the annealing time is 3 min to 20 min, and the atmosphere is air or nitrogen atmosphere.

[0016] The present disclosure also provides a method for preparing a perovskite solar cell, comprising: forming a self-assembled monolayer according to the above method for forming a self-assembled monolayer.

[0017] According to a method for preparing a perovskite solar cell disclosed herein, before forming a self-assembled monolayer, the method further includes a step of cleaning the TCO conductive substrate.

[0018] According to a method for preparing a perovskite solar cell disclosed herein, after forming a self-assembled monolayer, the method further includes the following steps:

[0019] coating a solution containing a perovskite material on the SAM layer to form a perovskite wet film;

[0020] annealing the perovskite wet film to form a perovskite layer;

[0021] forming one or more electron transport layers on the perovskite layer; and

[0022] An electrode layer is formed on the electron transport layer.

[0023] The present disclosure also provides a perovskite solar cell having a self-assembled monolayer formed according to the above method for forming a self-assembled monolayer.

[0024] According to the present disclosure, a composite solvent containing a high-boiling-point functional solvent can be selected when preparing a SAM material, thereby optimizing the overall properties of the composite solvent, such as its solubility, surface tension, and polarity. Combined with a vacuum flash evaporation process, most of the solvent can be quickly and uniformly removed at low temperatures, inhibiting molecular aggregation. Simultaneously, annealing conditions can be significantly relaxed, such as by lowering the annealing temperature or shortening the annealing time, thereby improving the uniformity and coverage of the SAM layer and the uniformity of the subsequent perovskite layer, thereby increasing the efficiency of solar devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 is a schematic flow chart of a method for forming a self-assembled monolayer according to one embodiment of the present disclosure.

[0026] Figure 2 is a schematic flow chart of a method for preparing a perovskite solar cell according to one embodiment of the present disclosure.

[0027] Figure 3 Schematic diagram of the structure of a perovskite solar cell according to one embodiment of the present disclosure.

[0028] Figures 4 to 9 The figure compares the film surface conditions of a perovskite solar cell according to one embodiment of the present disclosure and a traditional perovskite solar cell. DETAILED DESCRIPTION

[0029] In order to enable those skilled in the art to better understand the technical solution of the present disclosure, the technical solution of the present disclosure is described in detail below with reference to the accompanying drawings.

[0030] Example embodiments will be described more fully hereinafter with reference to the accompanying drawings, but the example embodiments may be embodied in different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete and will fully convey the scope of this disclosure to those skilled in the art.

[0031] In the absence of conflict, the various embodiments of the present disclosure and the various features therein may be combined with each other.

[0032] As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0033] The terms used herein are used only to describe specific embodiments and are not intended to limit the present disclosure. As used herein, the singular forms "a," "an," and "the" are also intended to include the plural forms, unless the context clearly indicates otherwise. It will also be understood that when the terms "comprising" and / or "made of" are used in this specification, the presence of the features, wholes, steps, operations, elements, and / or components is specified, but the presence or addition of one or more other features, wholes, steps, operations, elements, components, and / or groups thereof is not excluded.

[0034] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art. It will also be understood that terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant art and the present disclosure, and will not be interpreted as having an idealized or overly formal meaning unless expressly defined as such herein.

[0035] Unless otherwise specified, the term "concentration" herein refers to mass concentration. The concentration of each substance in a mixed solution refers to the mass concentration of each substance based on the total amount of the mixed solution.

[0036] The present disclosure provides a method for forming a self-assembled monolayer, such as Figure 1 As shown, the following steps are included:

[0037] S11-dissolving the SAM material in the composite solvent to form a SAM solution;

[0038] S12-coating the SAM solution on the substrate to form a SAM wet film; and

[0039] S13 - performing vacuum flash evaporation on the substrate having the SAM wet film, wherein the composite solvent comprises a type A solvent for dissolving the SAM material and a type B solvent capable of reducing agglomeration of the SAM material or slowing down the volatilization and evaporation rate.

[0040] SAM materials include, but are not limited to, one or more of [2-(9H-carbazol-9-yl)ethyl]phosphonic acid (2PACz), [2-(3,6-dimethoxy-9H-carbazol-9-yl)ethyl]phosphonic acid (MeO-2PACz), [4-(3,6-dimethyl-9H-carbazol-9-yl)butyl]phosphonic acid (Me-4PACz), [4-(9H-9'-phenyl-3,3'-dicarbazol-9-yl)butyl]phosphonic acid (4PABCz), Poly-DBPP, Poly-DCPA, etc.

[0041] The Class A solvent is typically a solvent that can effectively dissolve the SAM material and can be selected from one or more of isopropyl alcohol (IPA), ethanol, n-butanol, or chlorobenzene. The Class B solvent can include solvents with a boiling point above 130°C to provide various functionalities, such as solvents that can reduce micelle formation, such as acetonitrile (ACN) or DMF (153°C); or solvents that slow down the volatilization rate to improve film uniformity, such as ethylene glycol (197°C) and DMSO (189°C).

[0042] Optionally, various additives for conditioning the performance of the SAM solution, such as surfactants, ligand coupling agents, and viscosity modifiers, may be additionally added to the composite solvent.

[0043] The ratio of type A to type B solvent in the composite solvent can be adjusted according to the solubility of the selected SAM material, the polarity of the solvent itself, and the equipment conditions. Preferably, the ratio of type A to type B solvent in the composite solvent is 1:9 to 9:1.

[0044] The SAM material can be uniformly dissolved in the composite solvent by stirring or other methods. Those skilled in the art can adjust the total concentration of the SAM material in the composite solvent according to actual needs. Preferably, the total concentration of the SAM material in the composite solvent is 0.2-1.2 mg / ml.

[0045] The step of coating the SAM solution on the substrate to form a SAM wet film can be performed by various methods known in the art, such as dipping, spin coating, blade coating, and the like.

[0046] According to the method for forming a self-assembled monolayer described in the present disclosure, the temperature of the vacuum flash evaporation treatment is 10° C. to 50° C., the pressure is 5 Pa to 1000 Pa, and the holding time is 20 s to 120 s.

[0047] The method for forming a self-assembled monolayer according to the present disclosure further includes performing an annealing process after the vacuum flash evaporation process.

[0048] According to the method for forming a self-assembled monolayer described in the present disclosure, the temperature of the annealing treatment is 80° C. to 120° C., the annealing time is 3 min to 20 min, and the atmosphere is air or nitrogen atmosphere.

[0049] The present disclosure also provides a method for preparing a perovskite solar cell, which includes the above-mentioned method for forming a self-assembled monolayer.

[0050] According to a method for preparing a perovskite solar cell disclosed herein, before forming a self-assembled monolayer, the method further includes a step of cleaning the TCO conductive substrate.

[0051] The oxide material in the TCO conductive substrate includes one or more of tin fluoride oxide, indium tin oxide, indium zinc oxide, tungsten-doped indium oxide, and aluminum-doped zinc oxide.

[0052] Alternatively, a single or multiple metal oxide layers can be formed on the TCO conductive substrate by spin coating, doctor blade coating, ALD, or vacuum sputtering. The metal oxides may include one or more of tin oxide, aluminum oxide, silicon oxide, molybdenum oxide, nickel oxide, indium oxide, sodium-doped nickel oxide, magnesium-doped nickel oxide, chromium-doped indium oxide, tin-doped indium oxide, aluminum-doped indium oxide, tungsten-doped indium oxide, and molybdenum-doped indium oxide. These metal oxides can effectively increase the content of -OH hydroxyl groups on the substrate surface. The thickness of the metal oxide layer is 10-20 nm.

[0053] The TCO conductive substrate can be cleaned in sequence using deionized water, acetone, and isopropyl alcohol solutions and then dried.

[0054] According to a method for preparing a perovskite solar cell disclosed herein, after forming a self-assembled monolayer, the method further includes the following steps:

[0055] coating a solution containing a perovskite material on the SAM layer to form a perovskite wet film;

[0056] annealing the perovskite wet film to form a perovskite layer;

[0057] forming one or more electron transport layers on the perovskite layer; and

[0058] An electrode layer is formed on the electron transport layer.

[0059] The perovskite material includes any one or more perovskite minerals selected from the group consisting of FAMAPbI3, FACsPbI3, and FAMACsPbI3. The solvent used to form the perovskite solution may be selected from one or more of N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), γ-butyrolactone, N-methylpyrrolidone (NMP), and acetonitrile (ACN).

[0060] The perovskite wet film can be formed on the SAM layer by spin coating, blade coating or evaporation.

[0061] When the perovskite wet film is annealed, the annealing temperature may be 100-150° C., and the annealing time may be 15-60 minutes. Preferably, the annealing temperature is 100-130° C., and the annealing time is 25-60 minutes.

[0062] Materials used to form the electron transport layer include but are not limited to C60, PCBM, SnO2, BCP, IWO and the like.

[0063] Materials used to form the electrode layer include, but are not limited to, Au, Ag, Cu, ITO, and the like.

[0064] The electron transport layer and the electrode layer can be formed by evaporation or deposition.

[0065] According to one embodiment of the present disclosure, Figure 2 As shown, the method for preparing the perovskite solar cell includes the following steps:

[0066] S1-cleaning TCO conductive substrate;

[0067] The TCO conductive substrate was cleaned with deionized water, acetone, and isopropyl alcohol solutions for 30 minutes, dried, and plasma treated for 1 minute.

[0068] S2-forming a SAM wet film on a TCO conductive substrate;

[0069] The SAM material is dissolved in a composite solvent by stirring. The composite solvent comprises a Class A solvent for dissolving the SAM material and a Class B solvent for improving the film-forming properties of the SAM layer. The Class A solvent can be selected from one or more of isopropyl alcohol (IPA), ethanol, n-butanol, or chlorobenzene. The Class B solvent comprises a solvent having a boiling point greater than 130°C, such as one or more of ethylene glycol, dimethyl sulfoxide (DMSO), and N,N-dimethylformamide (DMF).

[0070] S3-Vacuum flash evaporation and annealing of the TCO conductive substrate with the SAM wet film;

[0071] The vacuum flash treatment is performed at a temperature of 10°C to 50°C, a pressure of 5 Pa to 1000 Pa, and a holding time of 20s to 120s. The annealing treatment is performed at a temperature of 80°C to 120°C, a time of 3 min to 20 min, and an atmosphere of air or nitrogen.

[0072] S4-coating a solution containing a perovskite material on the SAM layer to form a perovskite wet film;

[0073] One or more perovskite materials selected from the group consisting of FAMAPbI3, FACsPbI3, and FAMACsPbI3 are dissolved in a solvent to form a solution containing the perovskite material. The solvent comprises one or more of N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), γ-butyrolactone, N-methylpyrrolidone (NMP), and acetonitrile (ACN).

[0074] A perovskite wet film is formed on the SAM layer by spin coating, blade coating or evaporation.

[0075] S5-annealing the perovskite wet film to form a perovskite layer;

[0076] The perovskite wet film is annealed at a temperature of 100-150°C for a duration of 15-60 minutes.

[0077] S6-forming one or more electron transport layers on the perovskite layer;

[0078] An electron transport layer is formed on the perovskite layer by evaporation using materials such as C60, PCBM, SnO2, BCP, and IWO.

[0079] S7-forming an electrode layer on the electron transport layer;

[0080] The electrode layer is formed on the electron transport layer by evaporation using materials such as Au, Ag, Cu, and ITO.

[0081] The present disclosure also provides a perovskite solar cell, such as Figure 3 As shown, it includes a conductive substrate 1, a hole transport layer 2, a SAM layer 3, a perovskite light absorption layer 4, an electron transport layer 5 and a top electrode 6, and the SAM layer is formed according to the above method.

[0082] In order to enable those skilled in the art to more clearly understand the technical solution of the present disclosure, the technical solution of the present disclosure is described in detail below through specific embodiments.

[0083] Example 1

[0084] A set of 300mm*300mm FTO conductive glass was selected and P1 was etched using laser. The etched conductive glass surface was cleaned with deionized water, acetone, and isopropyl alcohol for 30 minutes in sequence. After drying, it was temporarily stored in a nitrogen cabinet.

[0085] The cleaned conductive glass was placed in a magnetron sputtering (PVD) device to deposit a nickel oxide layer NiOx as a hole transport layer. The thickness of the hole transport layer was 15 nm.

[0086] Me-4PACz and Poly-4PACz were prepared in a mass ratio of 9:1 as SAM materials. DMSO (boiling point 189°C) and IPA (boiling point 82.4°C) were used as solvents in a volume ratio of 9:1. The SAM materials were uniformly dissolved in the composite solvent to form a solution with a concentration of 0.8 mg / ml. The solution was then coated onto the substrate surface.

[0087] The coated substrate was transferred to a VCD device with a set pressure of 20 Pa, a holding time of 40 s, and a VCD platform temperature of 20° C.; the substrate was then transferred to an annealing device with an annealing time of 10 minutes and an annealing temperature of 100° C.

[0088] A 1 mol concentration of Cs0.15FA0.85PbI3 was selected, and a mixed solvent of DMF:DMSO:NMP = 3:1:1 was used to coat the perovskite solution onto the SAM layer. The coating platform moved at a speed of 30 mm / s, with a gap of 100 μm between the platform and the die. The film was then transferred to a VCD apparatus with a set pressure of 20 Pa, a hold time of 60 seconds, and a VCD platform temperature of 20°C. The film was then transferred to an annealing apparatus for 30 minutes at a temperature of 150°C.

[0089] On the perovskite layer, The fullerene (C60) layer and the 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP) layer are sequentially formed as electron transport layers at a rate of 30 nm and 7 nm, respectively. After the BCP is evaporated, the substrate is laser etched P2.

[0090] The Cu electrode layer is evaporated to a thickness of 100 nm, followed by laser etching P3 and P4 edge cleaning processes.

[0091] Among them, the P1 groove penetrates the conductive material layer of the conductive substrate 1; the P2 groove sequentially penetrates the hole transport layer 2, the self-assembled monolayer 3, the perovskite light absorption layer 4, and the electron transport layer 5; the P3 groove penetrates the metal electrode 6; the conductive material layer in the conductive substrate 1 of a perovskite sub-cell is connected to the metal electrode 6 of the next perovskite sub-cell through the P2 groove, completing the series connection between the perovskite sub-cells to form a perovskite solar cell device; the width, depth, quantity and other parameters of P1, P2, P3, P4 can be adjusted according to actual needs.

[0092] Example 2: The perovskite solar cell module of Comparative Example 1 was prepared by referring to the preparation method of Example 1, except that the ratio of the SAM solvent was changed to 5:1.

[0093] Example 3:

[0094] Select FTO conductive glass with a specification of 50mm*50mm, use laser to etch P1, and clean the etched conductive glass surface with deionized water, acetone and isopropyl alcohol for 30 minutes in sequence. After drying, place it in a nitrogen cabinet for temporary storage.

[0095] The cleaned conductive glass was placed in a magnetron sputtering (PVD) device to deposit a nickel oxide layer NiOx as a hole transport layer. The thickness of the hole transport layer was 15 nm.

[0096] Me-4PACz and Poly-4PACz (mass ratio 9:1) were selected as SAM materials, and DMSO (boiling point 189°C) and IPA (boiling point 82.4°C) were used as solvents in a volume ratio of 9:1. The SAM materials were uniformly dissolved in the composite solvent to form a solution with a concentration of 0.8 mg / ml. The solution was then spin-coated onto the substrate surface with a spin-coating parameter of 3000 rp and a spin-coating time of 30 s.

[0097] The coated substrate was transferred to a VCD device with a set pressure of 20 Pa, a holding time of 40 s, and a VCD platform temperature of 20° C.; the substrate was then transferred to an annealing device with an annealing time of 5 minutes and an annealing temperature of 100° C.

[0098] A 1.5 mol Cs0.15FA0.85PbI3 perovskite solution was selected as the perovskite material, and a 4:1 DMF:DMSO mixture was used as the solvent. The perovskite solution was applied to the SAM layer by spin coating. The spin coating parameters were: first step, 1000 rpm, acceleration 200 rpm / s, time 10 seconds; second step, 4000 rpm, acceleration 1000 rpm / s, time 32 seconds. The film was then transferred to a VCD apparatus with a holding pressure of 20 Pa, a holding time of 60 seconds, and a VCD platform temperature of 20°C. The film was then transferred to an annealing apparatus for 30 minutes at a temperature of 150°C.

[0099] On the perovskite layer, Fullerene (C60) and 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP) layers were sequentially deposited as electron transport layers at a rate of 30 nm and 7 nm, respectively. After BCP was evaporated, the substrate was laser etched P2.

[0100] The Cu electrode layer is evaporated to a thickness of 100 nm, followed by laser etching P3 and P4 edge cleaning processes.

[0101] Among them, the P1 groove penetrates the conductive material layer of the conductive substrate 1; the P2 groove sequentially penetrates the hole transport layer 2, the self-assembled monolayer 3, the perovskite light absorption layer 4, and the electron transport layer 5; the P3 groove penetrates the metal electrode 6; the conductive material layer in the conductive substrate 1 of a perovskite sub-cell is connected to the metal electrode 6 of the next perovskite sub-cell through the P2 groove, completing the series connection between the perovskite sub-cells to form a perovskite solar cell device; the width, depth, quantity and other parameters of P1, P2, P3, P4 can be adjusted according to actual needs.

[0102] Example 4-5:

[0103] The perovskite solar cell module of the embodiment was prepared by referring to the preparation method of embodiment 3, except that the pressure of the VCD treatment was set to 200 Pa and 2000 Pa respectively.

[0104] Example 6-7:

[0105] The perovskite solar cell module of the embodiment was prepared by referring to the preparation method of embodiment 3, except that the holding time of the VCD treatment was set to 10s and 100s respectively.

[0106] Comparative Example 1:

[0107] The perovskite solar cell module of Comparative Example 1 was prepared by referring to the preparation method of Example 1, except that, after coating the SAM layer, the annealing process was performed directly instead of vacuum flash evaporation.

[0108] Comparative Example 2:

[0109] The perovskite solar cell module of Comparative Example 2 was prepared by referring to the preparation method of Example 1, except that only IPA was used as the solvent.

[0110] Comparative Example 3:

[0111] The perovskite solar cell module of the embodiment was prepared by referring to the preparation method of embodiment 3, except that after the SAM layer was spin-coated, the vacuum flash evaporation was not performed but an annealing process was directly performed.

[0112] Table 1 Comparison of data such as solvent ratio, VCD pressure and holding time, substrate area, etc. in each embodiment and comparative example

[0113] sample SAM solvent ratio VCD holding pressure (Pa) VCD holding time (s) <![CDATA[Area (cm 2 )]]> Example 1 9:1 20 40 626 Example 2 5:1 20 40 626 Example 3 9:1 20 40 16.2 Example 4 9:1 200 40 16.2 Example 5 9:1 2000 40 16.2 Example 6 9:1 20 10 16.2 Example 7 9:1 20 100 16.2 Comparative Example 1 9:1 / / 626 Comparative Example 2 Use only IPA 20 40 626 Comparative Example 3 9:1 / / 16.2

[0114] The solar cells prepared in the various embodiments and comparative examples were subjected to performance tests, and Table 2 shows the relevant performance data.

[0115] Table 2 Comparison of the performance of the solar cells obtained in the examples and comparative examples

[0116] sample Isc(A) Voc(V) FF(%) PEC (%) <![CDATA[Area (cm 2 )]]> Example 1 0.358 46.57 68.26 18.21 626 Example 2 0.356 46.28 68.11 17.91 626 Example 3 0.05927 7.478 76.57 20.95 16.2 Example 4 0.05936 7.401 75.58 20.50 16.2 Example 5 0.05923 7.349 74.45 20.01 16.2 Example 6 0.05833 7.399 75.13 20.02 16.2 Example 7 0.05943 7.427 75.74 20.64 16.2 Comparative Example 1 0.355 45.86 64.98 16.93 626 Comparative Example 2 0.357 46.03 66.95 17.58 626 Comparative Example 3 0.05961 7.291 73.18 19.63 16.2

[0117] With reference to Comparative Example 1 and Example 1, Example 3 and Comparative Example 3, it can be seen that the open circuit voltage and photoelectric conversion efficiency of Example 1 and Example 3 are improved compared with Comparative Example 1 and Comparative Example 3. Vacuum flash evaporation of the SAM wet film containing the composite solvent can effectively remove the solvent, especially the high-boiling point solvent, and reduce the agglomeration of the SAM micelles. With reference to Comparative Example 2 and Example 1, it can be seen that the introduction of the vacuum flash evaporation step can broaden the selection range of the composite solvent, which is conducive to better dissolving the SAM material and reducing agglomeration. With reference to Comparative Examples 1 and 2, it can be seen that when direct annealing is performed without vacuum flash evaporation, the use of the composite solvent may lead to solvent residues and an increased degree of agglomeration of the SAM molecular micelles, introduce trap states at the buried interface, and ultimately reduce the photoelectric conversion efficiency of the battery.

[0118] With reference to Example 1, Example 2, and Comparative Example 1, it can be seen that the use of a composite solvent and the optimization of the solvent ratio can help to better dissolve the SAM material, reduce agglomeration, and improve the open circuit voltage and photoelectric conversion efficiency of the device. With reference to Examples 3-5, it can be seen that optimizing the VCD holding pressure can more thoroughly remove residual solvent, reduce SAM micelle agglomeration, improve the quality of the subsequently prepared perovskite film layer, and improve the open circuit voltage and photoelectric conversion efficiency of the device. With reference to Examples 3, 6, and 7, it can be seen that optimizing the VCD holding time can effectively remove the solvent, improve the quality of the subsequently prepared perovskite film layer, and improve the open circuit voltage and photoelectric conversion efficiency of the device.

[0119] like Figures 4 to 9 As shown, Figure 4 It is the actual film surface of the perovskite layer formed after the SAM layer is prepared by the traditional method. Figure 5 It is a membrane surface prepared using the disclosed technology. Figure 4 As shown in Figure 2, after the annealing step, the perovskite wet film has multiple tiny holes visible to the naked eye. Figure 4 There are obviously a large number of membrane holes, which are shown in the figure as a large number of small white dots randomly distributed in the black membrane surface. Figure 6 、 Figure 7 The CCD camera is used to further magnify these small white dots. The scale unit is mm. The radius of the holes in the figure can reach 0.1 to 0.2 mm ( Figure 6 、 Figure 7 The yellow dotted circles in the figure indicate the holes), which directly leads to a decrease in the photoelectric conversion efficiency of the device. Figure 8 、 Figure 9 It is a line diagram. Figure 8 This is a schematic diagram of the PVK membrane surface after SAM is prepared by the traditional method. Figure 9 It is obtained according to the preparation method disclosed in this disclosure. The gray is the perovskite film surface, the black in the middle is the laser P1 line, and the white circle represents the hole. Figure 9 There will be significantly fewer holes, which shows that the surface quality of these membranes is excellent.

[0120] Example embodiments have been disclosed herein, and although specific terms are employed, they are used and should be interpreted only in a general illustrative sense and not for purposes of limitation. In some embodiments, it will be apparent to those skilled in the art that, unless otherwise expressly stated, features, characteristics, and / or elements described in conjunction with a particular embodiment may be used alone or in combination with features, characteristics, and / or elements described in conjunction with other embodiments. Therefore, it will be understood by those skilled in the art that various changes in form and detail may be made without departing from the scope of the present disclosure as set forth in the appended claims.

Claims

1. A method for forming a self-assembled monolayer, characterized in that: The following steps are involved: dissolving the SAM material in the composite solvent to form a SAM solution; coating a SAM solution on a substrate to form a SAM wet film; as well as The substrate with SAM wet film is vacuum flash-evaporated. The composite solvent comprises a type A solvent for dissolving the SAM material and a type B solvent capable of improving the film-forming properties of the SAM layer.

2. The method for forming a self-assembled monolayer according to claim 1, wherein The type A solvent may be selected from one or more of isopropyl alcohol (IPA), ethanol, n-butanol or chlorobenzene; and the type B solvent includes a solvent having a boiling point higher than 130°C.

3. The method for forming a self-assembled monolayer according to claim 2, wherein: The solvent having a boiling point higher than 130° C. can be selected from one or more of ethylene glycol, dimethyl sulfoxide (DMSO), and N,N-dimethylformamide (DMF).

4. The method for forming a self-assembled monolayer according to claim 1, wherein The ratio of the type A solvent to the type B solvent in the composite solvent is 1:9 to 9:

1.

5. The method for forming a self-assembled monolayer according to claim 1, wherein The temperature of the vacuum flash treatment is 10° C. to 50° C., the pressure is 5 Pa to 1000 Pa, and the pressure holding time is 20 s to 120 s.

6. The method for forming a self-assembled monolayer according to claim 1, wherein The method further includes performing an annealing treatment after the vacuum flash treatment, wherein the annealing treatment is performed at a temperature of 80° C. to 120° C., for a time of 3 min to 20 min, and in an air or nitrogen atmosphere.

7. A method for preparing a perovskite solar cell, characterized in that: include: The method for forming a self-assembled monolayer according to any one of claims 1 to 6, wherein the self-assembled monolayer is formed.

8. The method for preparing a perovskite solar cell according to claim 7, wherein: Before forming the self-assembled monolayer, the method further includes a step of cleaning the TCO conductive substrate.

9. The method for preparing a perovskite solar cell according to claim 7, wherein: After forming the self-assembled monolayer, the following steps are also included: coating a solution containing a perovskite material on the SAM layer to form a perovskite wet film; annealing the perovskite wet film to form a perovskite layer; forming one or more electron transport layers on the perovskite layer; and An electrode layer is formed on the electron transport layer.

10. A perovskite solar cell, characterized in that: A self-assembled monolayer formed according to the method for forming a self-assembled monolayer according to any one of claims 1 to 6.

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