Perovskite thin film, preparation method thereof and perovskite solar cell

Abstract

The invention provides a perovskite thin film, a preparation method thereof and a perovskite solar cell. According to the perovskite thin film preparation method, in the process of preparing the organic salt layer on the inorganic salt layer through the wet method, the organic salt solution contains the additive, and the additive contains the mixture of the biphenyl ammonium derivative and the methyl ammonium thiocyanate. According to the invention, the uniform, compact, hole-free and high-quality perovskite thin film can be prepared, and the stability and preparation efficiency of the perovskite laminated solar cell in the aspect of large-area application can be effectively improved.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to the technical field of solar cell, and particularly relates to a perovskite thin film, a preparation method thereof and a perovskite solar cell. BACKGROUND

[0002] As a new type of thin-film photovoltaic technology, perovskite solar cells have developed rapidly in recent years. The photoelectric conversion efficiency of single-junction cells has been significantly improved from about 3.8% to more than 26.7%, showing great application potential. Perovskite materials have the advantages of relatively low manufacturing cost and adjustable band gap (1.18-2.3 eV), making them particularly suitable as top cells in stacked cell structures.

[0003] In the preparation process of perovskite thin films, a dry-wet two-step method is mainly used. The dry-wet two-step method includes forming an inorganic precursor thin film composed of lead iodide, cesium iodide and lead bromide by vapor deposition, spin-coating an organic amine salt solution, and finally forming a perovskite layer through annealing treatment. Since the dry-wet two-step method can effectively solve the problem of uniform coverage of perovskite materials on substrates with a textured structure, it is considered as one of the feasible paths for large-area production.

[0004] However, the existing dry-wet two-step method still has obvious process defects, especially in the process of coating the organic amine salt solution. These defects mainly manifest as the formation of "holes", "tears" and "incomplete coverage" (i.e., "full coverage problem") in the thin film. These defects can significantly reduce the quality of the perovskite thin film and become a key factor limiting the further improvement of cell performance. Studies have shown that the introduction of appropriate additives can regulate the crystallization kinetics of perovskite, such as accelerating the nucleation rate and increasing the crystal nucleus density, thereby helping to obtain a more dense, pore-free high-quality perovskite thin film, and ultimately achieving higher photoelectric conversion efficiency.

[0005] When perovskite solar cells are applied to stacked structures (such as crystalline silicon / perovskite stacked cells) and used as top cells, they need to be deposited on the bottom cells (such as crystalline silicon cells) with a textured structure (usually used for light trapping). In this specific application scenario, how to reliably and large-area prepare a dense, pore-free, defect-free high-quality perovskite thin film on a complex three-dimensional textured structure through an improved coating process (such as the dry-wet two-step method) is directly related to the improvement of the overall photoelectric conversion efficiency of the stacked cell.

[0006] Currently, the process optimization for applying the dry-wet two-step method to achieve high-quality perovskite thin film coverage on a textured substrate, especially effectively overcoming coating defects such as "holes", "tears" and "incomplete coverage" to meet the needs of high-efficiency stacked cells, is still a key technical problem that needs to be solved in the field. SUMMARY

[0007] Therefore, the present disclosure provides a perovskite thin film and a preparation method thereof, and a perovskite solar cell.

[0008] According to a first aspect of the present disclosure, a preparation method of a perovskite thin film used as a perovskite absorption layer of a perovskite solar cell is provided, and the preparation method comprises: depositing an inorganic salt layer on a substrate; wetly preparing an organic salt layer on the inorganic salt layer and annealing to obtain the perovskite thin film; wherein, during the process of wetly preparing the organic salt layer on the inorganic salt layer, an additive is contained in the organic salt solution, and the additive comprises a mixture of a diphenylammonium derivative and methyl thiocyanate.

[0009] In some embodiments of the first aspect of the present disclosure, the mass ratio of the diphenylammonium derivative to the methyl thiocyanate in the mixture of the diphenylammonium derivative and the methyl thiocyanate is 3:1.

[0010] In some embodiments of the first aspect of the present disclosure, the structural formula of the diphenylammonium derivative is , R1, R2, R3, R4 are independently selected from H, Cl, CH3.

[0011] In some embodiments of the first aspect of the present disclosure, the mixture of the diphenylammonium derivative and the methyl thiocyanate is one of the following: a mixture of 3,3',5,5'-tetramethylbenzidine and methyl thiocyanate; a mixture of 2,2'-dichloro-1,1'-biphenyl-4,4'-diamine and methyl thiocyanate.

[0012] In some embodiments of the first aspect of the present disclosure, the mass of the additive in the organic salt solution is 4% to 6% of the total mass of the organic salt.

[0013] In some embodiments of the first aspect of the present disclosure, the mass of the additive in the organic salt solution is 4.5% to 5% of the total mass of the organic salt.

[0014] In some embodiments of the first aspect of the present disclosure, the solvent of the organic salt solution is a mixture of methyl chloride amine, formamidine bromide amine, formamidine iodide amine and methyl iodide amine in a mass ratio of (6-8):(17-23):(38-45):(9-12).

[0015] According to a second aspect of the present disclosure, a perovskite thin film is provided, which is prepared by the above method.

[0016] In a third aspect of the present disclosure, a perovskite solar cell is provided, which comprises, from bottom to top, a bottom electrode, a hole transport layer, a perovskite absorption layer, a passivation layer, an electron transport layer, an N-face second transparent conductive layer, and a top electrode; wherein the perovskite absorption layer is prepared by the method.

[0017] In some embodiments of the third aspect of the present disclosure, the perovskite solar cell is a perovskite tandem solar cell.

[0018] In the embodiments of the present disclosure, the high-quality perovskite thin film with uniform density and no holes can be prepared by adding a mixture of diphenylammonium derivative and methyl thiocyanate ammonium in an organic salt solution, which solves the problems of "holes", "peeling", "full coating" and the like in the preparation of high-quality perovskite thin film, and effectively improves the photoelectric performance and stability of the perovskite thin film, and the stability and preparation efficiency of the perovskite tandem solar cell in large-area application. BRIEF DESCRIPTION OF DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present disclosure or the prior art, the drawings needed in the embodiments will be briefly introduced as follows. Obviously, the drawings in the following description are only some embodiments of the present disclosure, and other drawings can be obtained by those skilled in the art without creative labor.

[0020] Figure 1 A flowchart of the perovskite thin film preparation method provided by the embodiments of the present disclosure is shown in the figure. Figure 2 A perovskite thin film prepared by the perovskite thin film preparation method provided by Embodiment One of the present disclosure is shown in the figure. Figure 3 A structure diagram of the perovskite solar cell provided by Embodiment One of the present disclosure is shown in the figure. Figure 4a An N-face diagram of the perovskite solar cell provided by Embodiment One of the present disclosure is shown in the figure. Figure 4b A P-face diagram of the perovskite solar cell provided by Embodiment One of the present disclosure is shown in the figure. Figure 5 A perovskite thin film prepared by the perovskite thin film preparation method provided by Embodiment Two of the present disclosure is shown in the figure. Figure 6 A perovskite thin film prepared by the perovskite thin film preparation method provided by Embodiment Three of the present disclosure is shown in the figure. Figure 7 A perovskite thin film of Comparative Example 1 is shown in the figure. Figure 8 A perovskite thin film of Comparative Example 2 is shown in the figure. Figure 9A perovskite film diagram of Comparative Example 3. DETAILED DESCRIPTION

[0021] The technical solutions in the embodiments of the present disclosure will be clearly and completely described below with reference to the drawings in the embodiments of the present disclosure. Obviously, the described embodiments are only part of the embodiments of the present disclosure, rather than all the embodiments. Based on the embodiments in the present disclosure, all other embodiments obtained by a person of ordinary skill in the art without creative work fall within the protection scope of the present disclosure.

[0022] The terms used in the embodiments of the present disclosure are merely for the purpose of describing specific embodiments, and are not intended to limit the present disclosure. The singular forms "a", "an" and "the" used in the embodiments of the present disclosure and the appended claims are also intended to include the plural forms, unless the context clearly indicates otherwise.

[0023] Depending on the context, the word "if" as used herein can be interpreted to mean "when" or "upon" or "in response to a determination" or "in response to a detection." Similarly, the phrase "if determined" or "if detecting (a stated condition or event)" can be interpreted to mean "when determined" or "in response to a determination" or "when detecting (a stated condition or event)" or "in response to a detection (of a stated condition or event)", depending on the context.

[0024] As described above, there are coating defects such as "holes", "tears" and "incomplete coverage" in the current preparation of perovskite films, which directly affects the improvement of the overall photoelectric conversion efficiency of the stacked battery, resulting in problems such as poor stability, insufficient efficiency, and perovskite film defects in the large-area application of perovskite stacked solar cells. In view of this, the present disclosure provides a perovskite film and a preparation method thereof, and a perovskite solar cell, which improves the photoelectric performance and stability of the perovskite film by doping a mixture of diphenylammonium derivative and ammonium methyl thiocyanate as an additive during the preparation of the perovskite film, thereby overcoming coating defects such as "holes", "tears" and "incomplete coverage", and improving the stability and preparation efficiency of perovskite stacked solar cells in large-area applications.

[0025] The specific embodiments of the present disclosure will be described in detail below.

[0026] Embodiment One Figure 1 A flowchart of the perovskite film preparation method provided by the embodiments of the present disclosure is shown, which can be used as a perovskite absorption layer of a perovskite solar cell. Referring to Figure 1 The perovskite film preparation method of the embodiments of the present disclosure includes the following steps: Step 101, depositing an inorganic salt layer on a substrate; Step 102, wetly preparing an organic salt layer on the inorganic salt layer and annealing to obtain a perovskite film.

[0027] In the process of wetly preparing the organic salt layer on the inorganic salt layer, the organic salt solution contains an additive, and the additive contains a mixture of diphenyl ammonium derivative and ammonium methyl thiocyanate.

[0028] In step 101, the selection of the substrate depends on the structure of the target device. In the embodiments of the present disclosure, the perovskite film is applied to a perovskite solar cell, and the corresponding substrate is determined by the structure of the perovskite solar cell. Specifically, the substrate can be, but is not limited to, an electron transport layer, a hole transport layer, a click layer, a buffer layer / modification layer, etc.

[0029] Taking the hole transport layer as the substrate, a vacuum evaporation process can be used to deposit the inorganic salt layer on the upper surface of the hole transport layer in step 101. The deposition rate can be 0.2 Å / s~5.2 Å / s, and the deposition thickness of the inorganic salt layer can be controlled within 500 mm~600 mm. For example, the inorganic salt layer film can be formed by lead iodide, cesium iodide, and lead bromide. The lead iodide, cesium iodide, and lead bromide are respectively located in three evaporation boats, and the deposition rate of the lead iodide, cesium iodide, and lead bromide is controlled by controlling the current flowing through each evaporation boat. The deposition rate of the lead iodide can be 5 Å / s, the deposition rate of the lead bromide can be 0.5 Å / s, and the deposition rate of the cesium iodide can be 0.2 Å / s. The deposition thickness of the inorganic salt layer can be 550 mm.

[0030] In step 102, a slot coating method can be used to wetly prepare the organic salt layer in an air atmosphere. Specifically, in step 102, wetly preparing the organic salt layer on the inorganic salt layer can include: configuring an organic salt solution, placing the prepared organic salt solution in a liquid injection pump, starting a slot coater, synchronously starting a wind knife fixed on the main structure of the slot coater, the liquid injection pump injecting the organic salt solution into the coating knife head of the slot coater and dropping on the substrate (for example, the hole transport layer) by inertia, at the same time the slot coater continuously moving the substrate, and finally covering a layer of perovskite wet film on the substrate, which is the organic salt layer.

[0031] In some examples, the solvent in the organic salt solution can be methylammonium chloride (MACl), formamidinium bromide (FABr), formamidinium iodide (FAI), and methylammonium iodide (MAI) mixed in a mass ratio of (6~8):(17~23):(38~45):(9~12). For example, 1 mL of the organic salt solution can include 6~8 mg of methylammonium chloride, 17~23 mg of formamidinium bromide, 38~45 mg of formamidinium iodide, and 9~12 mg of methylammonium iodide. In other examples, the solvent of the organic salt solution can be isopropyl alcohol or ethanol.

[0032] In some examples, the biphenyl ammonium derivative has a structure of , R1, R2, R3, R4 are independently selected from H, Cl, CH3.

[0033] In some examples, the mass ratio of the biphenyl ammonium derivative to the methyl thiocyanate ammonium in the mixture of the biphenyl ammonium derivative and the methyl thiocyanate ammonium can be 3:1.

[0034] In some examples, the mass of the additive in the organic salt solution is 4% to 6% of the total mass of the organic salt. Preferably, the mass of the additive in the organic salt solution is 4.5% to 5% of the total mass of the organic salt.

[0035] For example, if a 50 mL organic salt solution doped with an additive is to be prepared, the solvent of the organic salt solution can be isopropyl alcohol, the organic salt solution includes 1000 mg of formamidine bromide (FABr), 2000 mg of formamidine iodide (FAI), 400 mg of methyl chloride amine (MACl), and 600 mg of methyl iodide amine (MAI), and the additive of the organic salt solution is a mixture of the biphenyl ammonium derivative and the methyl thiocyanate ammonium, which includes 135 mg of biphenyl ammonium and 45 mg of methyl thiocyanate ammonium.

[0036] In some examples, the slot coating method satisfies at least one of the following conditions: 1) the distance between the lip of the coating knife head and the coating platform is 150 μm to 250 μm; 2) the coating speed is 15 mm / s to 25 mm / s; 3) the air knife is selected as the air knife, and the pressure is 0.1 MPa to 1 MPa; 4) the injection speed is 10 μL / s to 30 μL / s.

[0037] In step 102, the heat treatment condition of the annealing treatment can be: annealing at 130 to 160 °C for 10 min. For example, the annealing temperature in step 102 can be set to 150 °C, and the annealing time can be set to 10 min.

[0038] Illustratively, the preparation process of the perovskite thin film can include: transferring the silicon wafer with the prepared hole transport layer into an evaporation cavity to evaporate an inorganic salt layer, using isopropyl alcohol solvent to dissolve the organic salt, and dissolving the additive together, using a wet method to prepare an organic compound layer on the inorganic salt layer, and finally forming a perovskite thin film after annealing treatment. Specifically, the battery piece with the prepared hole transport layer is transferred to a mask plate, and then placed in a vacuum chamber for vacuumizing treatment. When the vacuum degree decreases to 2*10 -6After the substrate baffle is opened after 0.5 MPa, the inorganic salt layer is deposited by co-evaporation. The evaporation rate of different film materials is controlled by controlling the temperature of different heating sources (in the order of priority of cesium iodide > lead bromide > lead iodide), so as to achieve the effect of fast evaporation first and slow evaporation later. The deposition rate of the inorganic salt layer is 0.2 Å / s~5.2 Å / s, and the deposition thickness of the inorganic salt layer is controlled to be 500~600 mm. The silicon wafer on which the inorganic salt is deposited is converted, which can be performed by spraying an organic salt, slot coating an organic salt, spin coating an organic salt, and squeegee coating an organic salt. Subsequently, annealing treatment is performed to generate the required perovskite phase.

[0039] The present disclosure further provides a perovskite thin film prepared by the perovskite thin film preparation method. Figure 2 A schematic diagram of the perovskite thin film prepared by the method is shown.

[0040] The present disclosure further provides a perovskite solar cell including a perovskite absorption layer prepared by the perovskite thin film preparation method, i.e., the perovskite absorption layer is the perovskite thin film.

[0041] Figure 3 A structural schematic diagram of the perovskite solar cell is shown. Referring to Figure 3 , the perovskite solar cell includes, from bottom to top, a bottom electrode, a hole transport layer, a perovskite absorption layer, a passivation layer, an electron transport layer, an N-face second transparent conductive layer, and a top electrode. The bottom electrode has a P-face transparent conductive layer and an N-face first transparent conductive layer.

[0042] Further, the perovskite solar cell of the present disclosure can be a perovskite tandem solar cell. For example, the perovskite solar cell can be a crystalline silicon / perovskite tandem solar cell. For another example, the perovskite solar cell can be a large-area crystalline silicon / perovskite tandem solar cell.

[0043] Figure 4a An N-face schematic diagram of the perovskite solar cell is shown, Figure 4b A P-face schematic diagram of the perovskite solar cell is shown.

[0044] Further, the preparation method of the perovskite solar cell provided by the present disclosure can include the following steps a1~a7: Step a1, forming a bottom electrode; A vacuum deposition process can be used to sputter a transparent conductive layer on the N-face (i.e., the electron output end) and the P-face (i.e., the hole output end) of the original silicon wafer. An evaporation process is used to form a silver electrode on the P-face transparent conductive layer of the bottom electrode, thereby obtaining the bottom electrode.

[0045] The original silicon wafer can be a silicon wafer with a nano-pyramid structure, the height of the tip of the pyramid can be 1-3 μm, the thickness of the P-face indium zinc oxide (also referred to as indium zinc oxide) (IZO) can be 100 nm-115 nm, and the thickness of the N-face IZO can be 20 nm-30 nm. When silver is evaporated on the entire surface of the P-face transparent conductive layer, a silver electrode can be prepared on the top of the P-face IZO of the original silicon wafer by using a magnetron sputtering, evaporation or other method, and the thickness of the silver electrode can be 0.9-1.1 μm, and the sputtering loss can be repaired by annealing.

[0046] In one example, the process of forming the bottom electrode can be as follows: after pretreatment such as cleaning and texturing of the silicon wafer, an M6 original silicon wafer (with a size of 166 mm x 166 nm) is obtained, IZO is first physically vapor deposited (PVD) on the P-face and N-face of the M6 original silicon wafer, the thickness of the P-face IZO can be 110 nm, and the thickness of the N-face IZO can be 20 nm, on this basis, the P-face is then evaporated with a silver thickness of about 1 μm, and then annealing is performed in an anaerobic environment, the annealing temperature is 185 °C, and the annealing time is about 20 min, thereby obtaining the bottom electrode.

[0047] Step a2, forming a hole transport layer on the N-face of the bottom electrode; The hole transport layer can be prepared by spin coating, magnetron sputtering, blade coating, evaporation, spraying or the like, and the material of the hole transport layer can be, but is not limited to, cuprous thiocyanate, nickel oxide, 2,2',7,7'-tetrakis[N,N-bis(4-methoxyphenyl)amino]-9,9'-spirobifluorene (MeO-2PACz), [4-(3,6-dimethyl-9H-carbazole-9-yl)butyl] phosphonic acid (Me-4PACz), etc.

[0048] The hole transport layer can be formed on the N-face of the bottom electrode by using a slot coating process. Specifically, on the basis of the bottom electrode obtained in step a1, nickel oxide is physically vapor deposited, and then a prepared [4-(3,6-dimethyl-9H-carbazole-9-yl)butyl] phosphonic acid Me-4PACz solution (solvent: methanol, solution concentration: 0.5 mg / mL) is placed in a liquid injection pump, a slot coater is started, an air knife is started, the liquid injection pump injects the Me-4PACz solution into the coating knife head of the slot coater and drops on the coating platform, at the same time, the slot coater continuously moves the knife head, and finally a layer of Me-4PACz wet film is covered on the substrate, after the coating is completed, annealing is performed in an anaerobic environment, the annealing temperature can be 100 °C, and the annealing time is about 10 min, thereby obtaining the hole transport layer.

[0049] Step a3, forming a perovskite absorption layer on the hole transport layer by the aforementioned perovskite thin film preparation method. Step a4: Form a passivation layer on the perovskite absorber layer; Specifically, a lithium fluoride (LiF) layer is deposited as a passivation layer on the perovskite absorber layer. The deposition rate of lithium fluoride (LiF) can be around 0.05 Å / s, and the deposition thickness of lithium fluoride (LiF) can be controlled between 0.9 and 1.1 nm. Preferably, a vacuum evaporation process can be used to deposit the passivation layer on the surface of the perovskite absorber layer, and the deposition thickness of lithium fluoride (LiF) can be around 1 nm.

[0050] Step a5: Form an electron transport layer on the passivation layer; Specifically, forming an electron transport layer on the passivation layer refers to applying C to the passivation layer through methods such as spin coating, vacuum evaporation, or atomic layer deposition. 60 Materials such as SnO2 are deposited on the top of the passivation layer. 60 The deposition rate can be around 0.01~0.05 Å / s, C 60 The deposition thickness can be controlled within 18-22 nm. Atomic layer deposition (ALD) is used for SnO2, and the SnO2 deposition thickness can be controlled within 18-22 nm. Preferably, C... 60 The deposition rate is 0.05 Å / s, C 60 The deposition thickness is 20 nm, and the deposition thickness of SnO2 is approximately 20 nm.

[0051] Step a6: Form a second transparent conductive layer on the N-side of the electron transport layer; Specifically, a second transparent conductive layer on the N-side can be formed on the electron transport layer using a vacuum deposition process. This vacuum deposition process can be, but is not limited to, magnetron sputtering, atomic layer deposition, laser pulse deposition, or thermal evaporation coating. Then, physical vapor deposition of IZO is performed on the basis of this second transparent conductive layer on the N-side, with a deposition thickness of approximately 61 nm.

[0052] Step a7: A metal electrode is deposited on top of the IZO film to form a top electrode.

[0053] Specifically, silver electrodes can be fabricated on the top of the IZO film using methods such as screen printing, magnetron sputtering, and evaporation to create a complete large-area crystalline silicon / perovskite tandem solar cell device. For example, a silver grid can be deposited on the surface of the second transparent conductive layer on the N-side obtained in step a6 using a vacuum evaporation process. First, the sub-grid is deposited, and then the main grid is deposited, with a grid line thickness of 1 μm, to obtain a large-area crystalline silicon / perovskite tandem solar cell.

[0054] It should be noted that the preparation method of the perovskite solar cell described above is only an example, and those skilled in the art should understand that the preparation method of the perovskite solar cell with different structures or different performance requirements can be flexibly improved as needed. The present embodiment does not limit this.

[0055] The entire process of the preparation method of the large-area crystalline silicon / perovskite stacked solar cell can be completed by a machine, which is efficient, simple to operate, and has high stability. The perovskite single-crystal thin film and the perovskite stacked device with consistent specifications such as thickness and area can be produced, which is conducive to commercial application.

[0056] Embodiment Two The embodiment provides a preparation method of a perovskite thin film, which is basically the same as that in Embodiment One, except that the organic salt solution contains a mixture of 2,2'-dichloro-1,1'-biphenyl-4,4'-diamine and methyl thiocyanate ammonium.

[0057] The embodiment provides a preparation method of a perovskite solar cell, which is basically the same as that in Embodiment One, except that the organic salt solution contains a mixture of 2,2'-dichloro-1,1'-biphenyl-4,4'-diamine and methyl thiocyanate ammonium, and a large-area crystalline silicon / perovskite stacked solar cell is obtained.

[0058] Figure 5 A schematic diagram of the perovskite thin film obtained by the preparation method of the embodiment is shown.

[0059] Embodiment Three The embodiment provides a preparation method of a perovskite thin film, which is basically the same as that in Embodiment One, except that the organic salt solution contains a mixture of 3,3',5,5'-tetramethylbenzidine and methyl thiocyanate ammonium.

[0060] The embodiment provides a preparation method of a perovskite solar cell, which is basically the same as that in Embodiment One, except that the organic salt solution contains a mixture of 3,3',5,5'-tetramethylbenzidine and methyl thiocyanate ammonium, and a large-area crystalline silicon / perovskite stacked solar cell is obtained.

[0061] Figure 6 A schematic diagram of the perovskite thin film obtained by the preparation method of the embodiment is shown.

[0062] Figure 7 A schematic diagram of a perovskite thin film (hereinafter referred to as Comparative Example 1) prepared without adding an additive to the organic salt solution is shown. Figure 8 A schematic diagram of a perovskite thin film (hereinafter referred to as Comparative Example 2) prepared by adding only biphenyl ammonium to the organic salt solution is shown. Figure 9A schematic diagram of the perovskite thin film prepared by adding only methyl thiocyanate ammonium in the organic salt solution (hereinafter referred to as Comparative Example 3) is shown.

[0063] Comparative Example Figure 2 , Figure 5 , Figure 6 and Figures 7 to 9 It can be seen that after the organic salt solution of the mixture of the doped diphenyl ammonium derivative and methyl thiocyanate ammonium is coated on the inorganic salt, the two react to form a perovskite intermediate, and the perovskite thin film obtained by annealing treatment has a bright surface, a mirror black phase, no peeling defects on the surface, and is uniform and dense. This shows that the mixture of the diphenyl ammonium derivative and methyl thiocyanate ammonium can be used as an additive to homogenize the perovskite crystallization and inhibit the light-induced phase segregation, and it can be used to extend the processing window of the blade-coated perovskite thin film, selectively passivate the defects at the buried perovskite interface, so that the perovskite thin film exhibits enhanced charge mobility and inhibited charge recombination, increases the perovskite crystal nucleus density, and obtains a dense, pore-free high-quality perovskite thin film to achieve high photoelectric conversion efficiency. The preparation method of the embodiments of the present disclosure can be fully mechanized, which not only solves the problems of low efficiency, complicated operation and poor stability of the traditional preparation method, but also is easier to produce perovskite single crystal thin films and stacked devices (i.e., perovskite solar cells) with highly consistent thickness and area specifications, which is beneficial to commercial application.

[0064] The perovskite solar cell of the embodiments of the present disclosure was tested for photoelectric conversion efficiency under standard test conditions (1.5 AM), and the scanning direction was reverse scanning. The test results are shown in Table 1. Table 1 also shows the test results of the perovskite solar cells corresponding to the aforementioned proportions. Among them, Voc represents the open circuit voltage, Jsc represents the short circuit current density, FF represents the fill factor, and PCE represents the photoelectric conversion efficiency.

[0065] As can be seen from Table 1, the perovskite solar cell obtained by adding the mixture of the diphenyl ammonium derivative and methyl thiocyanate ammonium in the organic salt solution has a significant improvement in the open circuit voltage (Voc), short circuit current density, fill factor (EF) and photoelectric conversion efficiency (PCE%) compared to the perovskite solar cell corresponding to the comparative example. Figures 7 to 9

[0066]

[0067] Table 1 ​The technical solutions provided by the present disclosure are described in detail above, and the principles and implementation manners of the present disclosure are described by applying specific examples. The above description of the examples is only used to help understand the method of the present disclosure and its core idea; meanwhile, for those skilled in the art, according to the idea of the present disclosure, the specific implementation manners and application ranges can be changed. In summary, the content of the specification should not be understood as a limitation of the present disclosure.

[0068] The above only describes preferred embodiments of the present disclosure and is not intended to limit the present disclosure. Any modifications, equivalent replacements, etc. made within the spirit and principle of the present disclosure shall be included in the protection scope of the present disclosure.

Claims

1. A method for preparing a perovskite thin film, characterized in that, The perovskite thin film is used as the perovskite absorber layer in a perovskite solar cell, and the method for preparing the perovskite thin film includes: An inorganic salt layer was obtained by deposition on the substrate; An organic salt layer was prepared on the inorganic salt layer by wet process, and then annealed to obtain a perovskite film; In the process of wet-processing the organic salt layer on the inorganic salt layer, the organic salt solution contains additives, which include a mixture of biphenylammonium derivatives and ammonium methylthiocyanate.

2. The method according to claim 1, characterized in that, The mass ratio of the biphenylammonium derivative to ammonium methylthiocyanate in the mixture is 3:

1.

3. The method according to claim 1, characterized in that, The structural formula of the biphenylammonium derivative is as follows: R1, R2, R3, and R4 are independently selected from H, Cl, and CH3, respectively.

4. The method according to claim 1, characterized in that, The mixture of the biphenylammonium derivative and ammonium methylthiocyanate is one of the following: A mixture of 3,3',5,5'-tetramethylbenzidine and ammonium methylthiocyanate; A mixture of 2,2'-dichloro-1,1'-biphenyl-4,4'-diamine and ammonium methylthiocyanate.

5. The method according to claim 1, characterized in that, The mass of the additive in the organic salt solution is 4% to 6% of the total mass of the organic salt.

6. The method according to claim 1 or 5, characterized in that, The mass of the additive in the organic salt solution is 4.5% to 5% of the total mass of the organic salt.

7. The method according to claim 1, characterized in that, The solvent of the organic salt solution is a mixture of methylammonium chloride, formamidinium bromide, formamidinium iodide and methylammonium iodide in a mass ratio of (6~8):(17~23):(38~45):(9~12).

8. A perovskite thin film, characterized in that, The perovskite thin film is prepared by the method described in any one of claims 1 to 7.

9. A perovskite solar cell, characterized in that, The perovskite solar cell comprises, from bottom to top: a bottom electrode, a hole transport layer, a perovskite absorber layer, a passivation layer, an electron transport layer, an N-side second transparent conductive layer, and a top electrode; wherein the perovskite absorber layer is prepared by the method described in any one of claims 1 to 7.

10. The perovskite solar cell according to claim 9, characterized in that, The perovskite solar cell is a perovskite tandem solar cell.

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