Method for gas phase passivation of perovskite thin film, perovskite thin film and perovskite solar cell

Abstract

The invention provides a method for gas phase passivation of a perovskite thin film, the perovskite thin film and a perovskite solar cell, and the method comprises the following steps: carrying out the crystallization of a perovskite precursor solution coating the surface of a substrate in a passivation atmosphere, and obtaining the perovskite thin film after gas phase passivation; or, in a passivation atmosphere, performing passivation post-treatment on the perovskite thin film subjected to crystallization treatment to obtain a perovskite thin film subjected to gas phase passivation; the passivation gas in the passivation atmosphere comprises H2S and / or SO2. According to the method provided by the invention, passivation treatment is carried out during crystallization treatment or after crystallization treatment, the passivation depth is increased, the crystallization performance of perovskite is improved, the repeated heating process is reduced, and the solvent in the perovskite precursor solution can be well removed, so that the perovskite thin film with good passivation quality is obtained; and the defect that the passivation effect is reduced along with size increase in a solution method can be overcome.

Description

Technical Field

[0001] This invention belongs to the field of solar cell technology, and relates to a thin film passivation method, particularly to a method for vapor-phase passivation of perovskite thin films, perovskite thin films, and perovskite solar cells. Background Technology

[0002] Perovskite solar cells have attracted widespread attention in the photovoltaic industry due to their advantages such as wide absorption bandgap, high absorption factor, tunable bandgap, low exciton binding energy, and low cost. However, due to the characteristics of their soft lattice structure, perovskite thin films are easily decomposed by factors such as light, heat, water, and oxygen, and the starting point of decomposition is often defects in the perovskite thin film.

[0003] Improving the encapsulation process to block water and oxygen, or passivating the perovskite film, can reduce the adverse effects of defects in the perovskite film. Traditional surface passivation methods are performed by solution coating, but as the size of perovskite solar cells increases, the non-uniformity of the coating further increases, resulting in a decrease in the final passivation effect with increasing size.

[0004] Therefore, there is a need for an efficient passivation method that can overcome size limitations to improve the passivation effect of perovskite thin films in perovskite solar cells. Summary of the Invention

[0005] In view of the shortcomings of the existing technology, the purpose of this invention is to provide a method for vapor-phase passivation of perovskite thin films, perovskite thin films and perovskite solar cells, which can overcome the defect of the traditional solution method that reduces the passivation effect as the size increases, and can also improve the passivation quality of perovskite thin films.

[0006] To achieve this objective, the present invention adopts the following technical solution:

[0007] In a first aspect, the present invention provides a method for vapor-phase passivation of perovskite thin films, the method comprising the following steps: in a passivation atmosphere, performing crystallization treatment on a perovskite precursor solution coated on a substrate surface to obtain a vapor-phase passivated perovskite thin film.

[0008] Alternatively, the perovskite film after crystallization treatment can be passivated in a passivating atmosphere to obtain a perovskite film after vapor phase passivation.

[0009] The passivating gas in the passivating atmosphere includes H2S and / or SO2.

[0010] The method provided by this invention utilizes H2S and / or SO2 for passivation during or after the crystallization process of the perovskite precursor solution. Hydrogen sulfide can form hydrogen bonds with iodide ions and passivate Pb vacancies in the perovskite film. Sulfur dioxide can react with defect sites on the surface of the perovskite film to form a passivation layer, thereby preventing the corrosion of the perovskite film by the external water and oxygen environment, improving stability, and also interacting with iodide ions to reduce iodide ion migration. The technical solution of passivation during crystallization increases the passivation depth, improves the crystallinity of perovskite, reduces repeated heating processes, and effectively removes the solvent in the perovskite precursor solution, thus obtaining a perovskite film with good passivation quality. It also overcomes the defect of solution methods where the passivation effect decreases with increasing size. In addition, combining the gas passivation process with the crystallization process of the perovskite film achieves process integration, which is beneficial to speed up the production cycle and reduce production costs.

[0011] Preferably, the passivating gas further includes NH3.

[0012] Preferably, the passivation gas contains not less than 20 vol% NH3 and not less than 20 vol% H2S and / or SO2.

[0013] Preferably, the passivation gas source includes any one or a combination of at least two of ammonium sulfide, ammonium hydrosulfide, ammonium sulfate, or ammonium sulfite.

[0014] Preferably, the passivation gas comprises a mixture of NH3 and H2S in a volume ratio of 1.8:1 to 2.2:1.

[0015] Preferably, the molar concentration of the passivating gas in the passivating atmosphere is from 0.44 mM to 22.06 mM.

[0016] Preferably, the passivating gas is a mixed gas obtained by heating an aqueous solution of ammonium sulfide, the mixed gas including water vapor, and the heating temperature is 40°C to 65°C.

[0017] Preferably, the temperature of the crystallization treatment is above 100°C, and more preferably between 100°C and 180°C.

[0018] Preferably, the crystallization treatment time is 5 minutes or more, more preferably 5 minutes to 90 minutes, and even more preferably 10 minutes to 20 minutes.

[0019] In a second aspect, the present invention provides a perovskite thin film, wherein the perovskite thin film is a perovskite thin film obtained by the method described in the first aspect after vapor-phase passivation.

[0020] Thirdly, the present invention provides a perovskite solar cell, the perovskite solar cell comprising a perovskite thin film obtained by the method described in the first aspect after vapor-phase passivation.

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0022] The method provided by this invention utilizes H2S and / or SO2 for passivation during or after the crystallization process of the perovskite precursor solution. Hydrogen sulfide can form hydrogen bonds with iodide ions and passivate Pb vacancies in the perovskite film. Sulfur dioxide can react with defect sites on the surface of the perovskite film to form a passivation layer, thereby preventing the corrosion of the perovskite film by the external water and oxygen environment, improving stability, and also interacting with iodide ions to reduce iodide ion migration. The technical solution of passivation during crystallization increases the passivation depth, improves the crystallinity of perovskite, reduces repeated heating processes, and effectively removes the solvent in the perovskite precursor solution, thus obtaining a perovskite film with good passivation quality. It also overcomes the defect of solution methods where the passivation effect decreases with increasing size. In addition, combining the gas passivation process with the crystallization process of the perovskite film achieves process integration, which is beneficial to speed up the production cycle and reduce production costs. Detailed Implementation

[0023] The technical solution of the present invention will be further illustrated below through specific embodiments.

[0024] An embodiment of the present invention provides a method for vapor-phase passivation of perovskite thin films, the method comprising the following steps: in a passivation atmosphere, performing crystallization treatment on a perovskite precursor solution coated on a substrate surface to obtain a vapor-phase passivated perovskite thin film.

[0025] Alternatively, the perovskite film after crystallization treatment can be passivated in a passivating atmosphere to obtain a perovskite film after vapor phase passivation.

[0026] The passivating gas in the passivating atmosphere includes H2S and / or SO2.

[0027] The method provided by this invention utilizes H2S and / or SO2 for passivation during the crystallization process of the perovskite precursor solution. Hydrogen sulfide can form hydrogen bonds with iodide ions and passivate Pb vacancies in the perovskite film. Sulfur dioxide can react with defect sites on the surface of the perovskite film to form a passivation layer, thereby preventing the corrosion of the perovskite film by the external water and oxygen environment, improving stability, and also interacting with iodide ions to reduce iodide ion migration. The technical solution of passivation during crystallization treatment increases the passivation depth, improves the crystallinity of perovskite, reduces repeated heating processes, and effectively removes the solvent in the perovskite precursor solution, thus obtaining a perovskite film with good passivation quality. It also overcomes the defect of solution method where the passivation effect decreases with increasing size. In addition, combining the gas passivation process with the crystallization process of the perovskite film achieves process integration, which is conducive to accelerating the production cycle and reducing production costs.

[0028] This invention does not specifically limit the temperature of the post-passivation treatment. Those skilled in the art can make reasonable settings according to process requirements, including but not limited to the annealing temperature of the perovskite film or the same temperature as the crystallization temperature of this invention.

[0029] In some embodiments, the passivating gas also includes NH3.

[0030] In some embodiments, the NH3 content in the passivation gas is not less than 20 vol%, for example, it can be 20 vol%, 30 vol%, 40 vol%, 45 vol%, or 50 vol%, but is not limited to the listed values; other unlisted values ​​within the range are also applicable. The H2S and / or SO2 content is not less than 20 vol%, for example, it can be 20 vol%, 30 vol%, 40 vol%, 45 vol%, or 50 vol%, but is not limited to the listed values; other unlisted values ​​within the range are also applicable.

[0031] In some embodiments, the passivation gas source includes substances that decompose upon heating to produce sulfur-containing gases.

[0032] In some embodiments, the source of the sulfur-containing gas includes any one or a combination of at least two of ammonium sulfide, ammonium hydrosulfide, ammonium sulfate, or ammonium sulfite. Typical but non-limiting combinations include a combination of ammonium sulfide and ammonium hydrosulfide, a combination of ammonium hydrosulfide and ammonium sulfate, a combination of ammonium sulfate and ammonium sulfate, or a combination of ammonium sulfide, ammonium hydrosulfide, ammonium sulfate, and ammonium sulfite.

[0033] This invention uses a specific source of sulfur-containing gas, which facilitates the on-demand preparation of passivation gas and avoids storage safety and cost issues related to passivation gas. This helps to improve the safety of perovskite thin film vapor phase passivation and reduce the cost of vapor phase passivation.

[0034] Taking ammonium sulfate as an example, solid ammonium sulfate can decompose into NH3, SO2, N2, and water under heating conditions. This allows for the synergistic effect of ammonia, sulfur dioxide, and water molecules, promoting the passivation and crystallization of perovskite. In mixed gases prepared directly from the aforementioned sulfur-containing gas sources, the water vapor content may be too high (i.e., not meeting the requirements for perovskite thin film preparation). If this occurs, a desiccant can be added to the gas path, and combined with the monitoring function of a hygrometer, the water vapor content in the mixed gas can be easily and conveniently adjusted to a suitable level.

[0035] In some embodiments, the passivation gas comprises a mixture of NH3 and H2S in a volume ratio of 1.8:1 to 2.2:1, for example, 1.8:1, 1.9:1, 2:1, 2.1:1, or 2.2:1, but not limited to the listed values. Other unlisted values ​​within the range are also applicable, with 2:1 being preferred. When the volume ratio of NH3 to H2S in the passivation gas is preferred, the composition of the passivation gas can be obtained by directly heating the ammonium sulfide aqueous solution, reducing the difficulty of preparing the passivation gas composition, which is beneficial for reducing passivation costs and improving passivation efficiency.

[0036] In some embodiments, the molar concentration of the passivating gas in the passivating atmosphere is from 0.44 mM to 22.06 mM, for example, it can be 0.44 mM, 1 mM, 3 mM, 5 mM, 8 mM, 10 mM, 15 mM, 20 mM or 22.06 mM, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0037] The molar concentration of passivating gas in the passivation atmosphere described in this invention refers to the total molar concentration of all passivating gases in the chamber during crystallization treatment.

[0038] In some embodiments, the passivating gas is a mixture obtained by heating an aqueous solution of ammonium sulfide, the mixture including water vapor, and the heating temperature is from 40°C to 65°C, for example, 40°C, 45°C, 50°C, 55°C, 60°C or 65°C, but not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0039] Ammonium sulfide aqueous solution generates hydrogen sulfide gas, ammonia gas, and trace amounts of water molecules under relatively low heating conditions. In addition to hydrogen sulfide gas playing a passivation role, ammonia gas can also repair perovskite films. The generated water molecules can form hydrogen bonds with iodide ions, passivating Pb vacancies in perovskite, thus achieving synergistic passivation by hydrogen sulfide, ammonia gas, and water molecules.

[0040] In some embodiments, the temperature of the crystallization treatment is above 100°C, for example, it can be 100°C, 110°C, 130°C, 140°C, 150°C, 160°C, 180°C or 200°C, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable, preferably 100°C to 180°C.

[0041] In some embodiments, the crystallization process refers to placing a substrate coated with a perovskite precursor solution on a heating stage and controlling the temperature of the heating stage to perform the crystallization process at a specific temperature.

[0042] Sufficient crystallization time ensures that the perovskite film can be fully formed and has good film quality, while a longer crystallization time is not conducive to improving the efficiency of vapor-phase passivated perovskite solar cells.

[0043] In some embodiments, the crystallization treatment time is 5 minutes or more, for example, it can be 5 minutes, 10 minutes, 20 minutes, 30 minutes, 40 minutes, 50 minutes, 60 minutes, 70 minutes, 80 minutes, 90 minutes or 100 minutes, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable. Preferably, it is 5 minutes to 90 minutes, and more preferably 10 minutes to 20 minutes.

[0044] In some embodiments, the perovskite film is made of ABX3 type perovskite, where A is Cs. + Ru + CH3NH3 + C(NH2)3 + CH(NH2)2 + Any one or at least two of them, for example, CH3NH3 + C(NH2)3 + With CH(NH2)2 + Combination, Cs + Ru + With CH3NH3 + The combination, or Cs + Ru + CH3NH3 + C(NH2)3 + With CH(NH2)2 + The combination; B is Pb 2+ and / or Sn 2+ X is Br - I - or Cl - Any one or at least two of them; X is Br - I - or Cl- Any one or at least two of the above, typical but non-limiting combinations include Br - with I - The combination, I - With Cl - The combination, Br - With Cl - The combination, or Br - I - With Cl - The combination of .

[0045] The composition of the perovskite precursor solution corresponds to the material of the perovskite film.

[0046] An embodiment of the present invention provides a perovskite thin film, wherein the perovskite thin film is a perovskite thin film obtained by the method described in any embodiment after vapor phase passivation.

[0047] An embodiment of the present invention also provides a perovskite solar cell, the perovskite solar cell comprising a perovskite thin film after vapor-phase passivation obtained by the method described in any embodiment.

[0048] In some embodiments, the perovskite solar cell has a structure that includes any one of a formal structure, an inverted structure, or a stacked structure.

[0049] In some embodiments, the perovskite solar cell includes a transparent conductive layer, a hole transport layer, a perovskite thin film after vapor phase passivation, an electron transport layer, a buffer layer, and an electrode layer stacked sequentially.

[0050] In some embodiments, the transparent conductive layer is made of fluorine-doped indium oxide (FTO) or indium tin oxide (ITO).

[0051] In some embodiments, the hole transport layer is made of any one or a combination of at least two of nickel oxide, aluminum oxide, styrene sulfonate, polytriarylamine, or cuprous thiocyanate. Typical but non-limiting combinations include combinations of nickel oxide and aluminum oxide, combinations of styrene sulfonate and polytriarylamine, combinations of polytriarylamine and cuprous thiocyanate, combinations of nickel oxide, aluminum oxide, and styrene sulfonate, combinations of aluminum oxide, styrene sulfonate, polytriarylamine, and cuprous thiocyanate, or combinations of nickel oxide, aluminum oxide, styrene sulfonate, polytriarylamine, and cuprous thiocyanate.

[0052] In some embodiments, the thickness of the perovskite film after vapor passivation is 300 nm to 900 nm, for example, it can be 300 nm, 400 nm, 500 nm, 600 nm, 700 nm, 800 nm or 900 nm, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0053] In some embodiments, the electron transport layer comprises a fullerene (C0) 60 )layer.

[0054] In some embodiments, the thickness of the fullerene layer is 15 nm to 20 nm, for example, it can be 15 nm, 16 nm, 17 nm, 18 nm, 19 nm or 20 nm, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0055] In some embodiments, the buffer layer comprises a tin oxide layer or a 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP) layer.

[0056] In some embodiments, the thickness of the buffer layer is 10 nm to 20 nm, for example, it can be 10 nm, 12 nm, 15 nm, 18 nm or 20 nm, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0057] In this invention, the electrode layer is made of a conventional material in the art.

[0058] In some embodiments, the electrode layer is made of metal and / or conductive non-metal.

[0059] The metal includes, but is not limited to, any one or a combination of at least two of copper, silver, or gold.

[0060] The conductive nonmetal includes, but is not limited to, any one or a combination of at least two of transparent conductive oxides, conductive polymers, or carbon.

[0061] In some embodiments, the thickness of the electrode layer is 80 nm to 120 nm, for example, it can be 80 nm, 90 nm, 100 nm, 110 nm or 120 nm, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0062] In some embodiments, the method for fabricating the perovskite solar cell includes:

[0063] (1) A solution of the hole transport layer material is coated on the surface of the transparent conductive layer and baked to obtain the hole transport layer.

[0064] (2) A perovskite precursor solution is coated on the surface of the hole transport layer away from the transparent conductive layer, and then crystallization treatment is performed in a passivation atmosphere; after the crystallization treatment is completed, a perovskite film after gas phase passivation is obtained.

[0065] (3) An electron transport layer is deposited on the surface of the perovskite thin film far from the hole transport layer after vapor passivation.

[0066] (4) A buffer layer is deposited on the surface of the electron transport layer that is far from the hole transport layer.

[0067] (5) Deposit an electrode layer on the surface of the buffer layer that is far from the electron transport layer.

[0068] The tests in the following specific implementation include current-voltage tests performed under standard sunlight with a light intensity of 100 mW / cm². 2 The testing instruments include conventional solar simulators and digital source meters. The photovoltaic parameters tested include short-circuit current (Isc), series resistance (Rs), parallel resistance (Rsh), open-circuit voltage (Voc), fill factor (FF), and photoelectric conversion efficiency (PCE).

[0069] Example 1

[0070] This embodiment provides a perovskite solar cell, comprising a transparent conductive layer, a hole transport layer, a perovskite thin film after vapor phase passivation, an electron transport layer, a buffer layer, and an electrode layer sequentially stacked, and the fabrication method includes:

[0071] (1) ITO transparent conductive layer with a size of 1cm×1cm was ultrasonically cleaned with deionized water, acetone and anhydrous ethanol for 10min and then dried with nitrogen; then a nickel oxide ethanol solution of 25mg / mL was coated on the surface of the ITO transparent conductive layer and baked at 100℃ for 10min to obtain hole transport layer.

[0072] (2) A perovskite precursor solution is coated on the surface of the hole transport layer away from the transparent conductive layer, and then crystallization treatment is performed in a passivation atmosphere. After the crystallization treatment, a perovskite film with a thickness of 500 nm after gas phase passivation is obtained.

[0073] The passivating gas in the passivating atmosphere includes H2S and NH3. The passivating gas source includes an aqueous solution of ammonium sulfide, which decomposes at 55°C to produce hydrogen sulfide, ammonia, and water molecules, constituting the passivating atmosphere in this embodiment. The volume ratio of NH3 to H2S in the passivating gas is 2:1, and the molar concentration of the passivating gas in the passivating atmosphere is 13.24 mM.

[0074] The crystallization treatment was performed at a temperature of 150℃ for 15 minutes.

[0075] The solvent in the perovskite precursor solution includes N,N-dimethylformamide and 1-methyl-2-pyrrolidone in a volume ratio of 9:1, and the solvents are 1.5M PbI2, 1.425M FAI, and 0.075M CsI, where FA is formamidinyl CH5N2. + .

[0076] (3) Then, using a vapor deposition apparatus, a 20nm electron transport layer, a 15nm buffer layer, and an 80nm electrode layer are deposited sequentially; the material of the electron transport layer is C. 60 The buffer layer is made of BCP, and the electrode layer is made of Cu.

[0077] Example 2

[0078] This embodiment provides a perovskite solar cell, which is the same as that in Embodiment 1 except that the size of the transparent conductive layer is 20cm×20cm.

[0079] Example 3

[0080] This embodiment provides a perovskite solar cell, which is the same as that in Embodiment 1 except that the size of the transparent conductive layer is 30cm×30cm.

[0081] Example 4

[0082] This embodiment provides a perovskite solar cell, comprising a transparent conductive layer, a hole transport layer, a vapor-passivated perovskite thin film, an electron transport layer, a buffer layer, and an electrode layer sequentially stacked, and its fabrication method includes:

[0083] (1) ITO transparent conductive layer with a size of 1cm×1cm was ultrasonically cleaned with deionized water, acetone and anhydrous ethanol for 10min and then dried with nitrogen; then a nickel oxide ethanol solution of 25mg / mL was coated on the surface of the ITO transparent conductive layer and baked at 100℃ for 10min to obtain hole transport layer.

[0084] (2) A perovskite precursor solution is coated on the surface of the hole transport layer away from the transparent conductive layer, and then crystallization treatment is performed. After the crystallization treatment, a perovskite film with a thickness of 500 nm is obtained. The perovskite film is passivated in a passivation atmosphere to obtain a gas-phase passivated perovskite film.

[0085] The crystallization treatment was performed at a temperature of 150℃ for 15 minutes.

[0086] The solvent in the perovskite precursor solution includes N,N-dimethylformamide and 1-methyl-2-pyrrolidone in a volume ratio of 9:1, and the solvents are 1.5M PbI2, 1.425M FAI, and 0.075M CsI, where FA is formamidinyl CH5N2. + .

[0087] The passivating gases in the passivating atmosphere include H2S and NH3. The sources of the passivating gases include an aqueous solution of ammonium sulfide, which decomposes at 55°C to produce hydrogen sulfide, ammonia, and water molecules, constituting the passivating atmosphere in this comparative example. The volume ratio of NH3 to H2S in the passivating atmosphere is 2:1, and the molar concentration of the passivating gases in the passivating atmosphere is 13.24 mM.

[0088] (3) Then, using a vapor deposition apparatus, a 20nm electron transport layer, a 15nm buffer layer, and an 80nm electrode layer are deposited sequentially; the material of the electron transport layer is C. 60 The buffer layer is made of BCP, and the electrode layer is made of Cu.

[0089] Comparative Example 1

[0090] This comparative example provides a perovskite solar cell, comprising a transparent conductive layer, a hole transport layer, a perovskite thin film, an electron transport layer, a buffer layer, and an electrode layer sequentially stacked, and its fabrication method includes:

[0091] (1) ITO transparent conductive layer with a size of 1cm×1cm was ultrasonically cleaned with deionized water, acetone and anhydrous ethanol for 10min and then dried with nitrogen; then a nickel oxide ethanol solution of 25mg / mL was coated on the surface of the ITO transparent conductive layer and baked at 100℃ for 10min to obtain hole transport layer.

[0092] (2) A perovskite precursor solution was coated on the surface of the hole transport layer away from the transparent conductive layer, and then crystallization was performed. After the crystallization treatment, a perovskite film with a thickness of 500 nm was obtained. The crystallization treatment temperature was 150 °C and the time was 15 min.

[0093] (3) Then, using a vapor deposition apparatus, a 20nm electron transport layer, a 15nm buffer layer, and an 80nm electrode layer are deposited sequentially; the material of the electron transport layer is C. 60 The buffer layer is made of BCP, and the electrode layer is made of Cu.

[0094] Comparative Example 2

[0095] This comparative example provides a perovskite solar cell, which is identical to Comparative Example 1 except that the size of the transparent conductive layer is 30cm×30cm.

[0096] Comparative Example 3

[0097] This comparative example provides a perovskite solar cell, comprising a transparent conductive layer, a hole transport layer, a solution passivated perovskite thin film, an electron transport layer, a buffer layer, and an electrode layer sequentially stacked, and its fabrication method includes:

[0098] (1) ITO transparent conductive layer with a size of 1cm×1cm was ultrasonically cleaned with deionized water, acetone and anhydrous ethanol for 10min and then dried with nitrogen; then a nickel oxide ethanol solution of 25mg / mL was coated on the surface of the ITO transparent conductive layer and baked at 100℃ for 10min to obtain hole transport layer.

[0099] (2) A perovskite precursor solution is coated on the surface of the hole transport layer away from the transparent conductive layer, and then crystallization treatment is performed. After the crystallization treatment, a perovskite film with a thickness of 500 nm is obtained. A 1 mg / mL ammonium sulfide isopropanol solution is coated on the surface of the obtained perovskite film and treated at 100 °C for 5 min to obtain a solution passivated perovskite film.

[0100] The crystallization treatment was performed at a temperature of 150℃ for 15 minutes.

[0101] The solvent in the perovskite precursor solution includes N,N-dimethylformamide and 1-methyl-2-pyrrolidone in a volume ratio of 9:1, and the solvents are 1.5M PbI2, 1.425M FAI, and 0.075M CsI, where FA is formamidinyl CH5N2. + .

[0102] (3) Then, using a vapor deposition apparatus, a 20nm electron transport layer, a 15nm buffer layer, and an 80nm electrode layer are deposited sequentially; the material of the electron transport layer is C. 60 The buffer layer is made of BCP, and the electrode layer is made of Cu.

[0103] Comparative Example 4

[0104] This comparative example provides a perovskite solar cell, which is identical to Comparative Example 3 except that the size of the transparent conductive layer is 30cm×30cm.

[0105] Comparative Example 5

[0106] This comparative example provides a perovskite solar cell, comprising a transparent conductive layer, a hole transport layer, a vapor-phase passivated perovskite thin film, an electron transport layer, a buffer layer, and an electrode layer sequentially stacked, and its fabrication method includes:

[0107] (1) ITO transparent conductive layer with a size of 1cm×1cm was ultrasonically cleaned with deionized water, acetone and anhydrous ethanol for 10min and then dried with nitrogen; then a nickel oxide ethanol solution of 25mg / mL was coated on the surface of the ITO transparent conductive layer and baked at 100℃ for 10min to obtain hole transport layer.

[0108] (2) A perovskite precursor solution is coated on the surface of the hole transport layer away from the transparent conductive layer, and then crystallization treatment is performed. After the crystallization treatment, a perovskite film with a thickness of 500 nm is obtained. The perovskite film is passivated in a passivation atmosphere to obtain a gas-phase passivated perovskite film.

[0109] The crystallization treatment was performed at a temperature of 150℃ for 15 minutes.

[0110] The solvent in the perovskite precursor solution includes N,N-dimethylformamide and 1-methyl-2-pyrrolidone in a volume ratio of 9:1, and the solvents are 1.5M PbI2, 1.425M FAI, and 0.075M CsI, where FA is formamidinyl CH5N2. + .

[0111] The passivating gases in the passivating atmosphere include HF and NH3. The sources of the passivating gases include an aqueous solution of ammonium fluoride, which, upon heating and decomposition, produces hydrogen fluoride, ammonia, and water molecules, constituting the passivating atmosphere in this comparative example. The volume ratio of HF to H2S in the passivating gases is 1:1, the molar concentration of the passivating gases in the passivating atmosphere is 13.24 mM, and the temperature of the passivating gases is 55 °C.

[0112] (3) Then, using a vapor deposition apparatus, a 20nm electron transport layer, a 15nm buffer layer, and an 80nm electrode layer are deposited sequentially; the material of the electron transport layer is C. 60 The buffer layer is made of BCP, and the electrode layer is made of Cu.

[0113] Performance testing

[0114] The photovoltaic parameters of the perovskite solar cells obtained in the above embodiments and comparative examples were measured, and the results are shown in Table 1.

[0115] Table 1

[0116] Transparent conductive layer size Voc(V) Isc(mA) FF (%) PCE (%) Rs(ohm) Rsh(ohm) Example 1 1cm×1cm 1.09 24.64 73.40 19.87 6.51 960.24 Example 2 20cm×20cm 27.25 287.62 75.21 19.26 7.29 15556.98 Example 3 30cm×30cm 38.68 405.66 76.35 19.04 8.51 2356.98 Example 4 1cm×1cm 1.09 23.86 73.77 19.32 6.45 3301.42 Comparative Example 1 1cm×1cm 1.03 23.72 71.24 17.40 5.90 895.18 Comparative Example 2 30cm×30cm 36.72 389.32 72.29 16.41 8.26 1539.68 Comparative Example 3 1cm×1cm 1.10 24.50 72.12 19.51 6.66 4205.21 Comparative Example 4 30cm×30cm 37.98 401.46 74.30 17.94 9.31 8939.35 Comparative Example 5 1cm×1cm 1.10 23.86 72.26 19.03 6.70 1263.58

[0117] In Examples 5 and 6, except for the crystallization treatment time which varies as shown in Table 2, everything else is the same as in Example 1.

[0118] Table 2

[0119] Time (min) Temperature (°C) Voc(V) Isc(mA) FF (%) PCE (%) Rs(ohm) Rsh(ohm) Example 1 15 150 1.09 24.64 73.40 19.87 6.51 960.24 Example 5 10 150 1.07 24.37 71.94 18.84 6.98 26041.67 Example 6 20 150 1.07 24.72 70.11 18.54 6.86 1435.33

[0120] In Examples 7 and 8, except for the change in the concentration of the passivating gas in the passivating atmosphere as shown in Table 3, everything else was the same as in Example 1.

[0121] Table 3

[0122]

[0123]

[0124] In summary, the method provided by this invention utilizes H2S and / or SO2 for passivation during the crystallization process of the perovskite precursor solution. Hydrogen sulfide can form hydrogen bonds with iodide ions and passivate Pb vacancies in the perovskite film. Sulfur dioxide can react with defect sites on the surface of the perovskite film to form a passivation layer, thereby preventing the corrosion of the perovskite film by the external water and oxygen environment, improving stability, and also interacting with iodide ions to reduce iodide ion migration. The technical solution of passivation during crystallization treatment increases the passivation depth, improves the crystallinity of perovskite, reduces repeated heating processes, and effectively removes the solvent in the perovskite precursor solution, thus obtaining a perovskite film with good passivation quality. It also overcomes the defect of solution methods where the passivation effect decreases with increasing size. In addition, combining the gas passivation process with the crystallization process of the perovskite film achieves process integration, which is beneficial for accelerating the production cycle and reducing production costs.

[0125] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for vapor-phase passivation of perovskite thin films, characterized in that, The method includes the following steps: in a passivation atmosphere, the perovskite precursor solution coated on the substrate surface is subjected to crystallization treatment to obtain a perovskite film after vapor phase passivation. Alternatively, in a passivation atmosphere, the perovskite film after crystallization is passivated to obtain a perovskite film after vapor phase passivation. The passivating gas in the passivating atmosphere includes H2S and / or SO2.

2. The method according to claim 1, characterized in that, The passivating gas also includes NH3.

3. The method according to claim 2, characterized in that, The passivation gas contains not less than 20 vol% NH3 and not less than 20 vol% H2S and / or SO2.

4. The method according to claim 3, characterized in that, The passivation gas source includes any one or a combination of at least two of ammonium sulfide, ammonium hydrosulfide, ammonium sulfate, or ammonium sulfite.

5. The method according to claim 3, characterized in that, The passivation gas comprises a mixture of NH3 and H2S in a volume ratio of 1.8:1 to 2.2:

1.

6. The method according to claim 5, characterized in that, The molar concentration of the passivating gas in the passivating atmosphere is from 0.44 mM to 22.06 mM.

7. The method according to claim 5, characterized in that, The passivating gas is a mixture obtained by heating an aqueous solution of ammonium sulfide, the mixture containing water vapor, and the heating temperature is 40°C to 65°C.

8. The method according to claim 1, characterized in that, The temperature of the crystallization treatment is above 100°C, preferably between 100°C and 180°C; Preferably, the crystallization treatment time is 5 minutes or more, more preferably 5 minutes to 90 minutes, and even more preferably 10 minutes to 20 minutes.

9. A perovskite thin film, characterized in that, The perovskite film is a perovskite film obtained by the method described in any one of claims 1 to 8 after vapor-phase passivation.

10. A perovskite solar cell, characterized in that, The perovskite solar cell comprises a perovskite thin film obtained by the method of any one of claims 1 to 8 after vapor-phase passivation.

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