A perovskite absorber layer, its preparation method and application

Abstract

This invention provides a perovskite absorber layer, its preparation method, and its application. The preparation method includes the following steps: preparing a metal inorganic salt layer; coating the surface of the metal inorganic salt layer with a metal salt solution containing bicarbonate ions, and performing multi-stage heating and annealing to obtain a porous metal inorganic salt layer; introducing an organic cation salt onto the surface of the porous metal inorganic salt layer, followed by annealing, to obtain the perovskite absorber layer. This invention introduces a metal salt solution containing bicarbonate ions onto the surface of the metal inorganic salt layer, and uses a stepped heating and annealing process to produce carbon dioxide volatilization, thereby creating pores and producing a porous metal inorganic salt layer. This allows the organic cation salt to penetrate into the interior of the metal inorganic salt layer, achieving a high degree of perovskite phase transformation. Simultaneously, the residual metal salt solution containing bicarbonate ions can partially passivate perovskite defects.

Description

Technical Field

[0001] This invention belongs to the field of photovoltaic technology, specifically relating to a perovskite absorber layer, its preparation method, and its application. Background Technology

[0002] The two-step process is one of the important methods for preparing perovskite absorber layers. The first step involves preparing inorganic metal salts such as lead salts and cesium salts through wet methods such as thermal evaporation or spin coating. The second step involves introducing organic cationic salts such as methylamine and formamidinium through evaporation or wet methods. Perovskite absorber layers prepared by this process have advantages such as good uniformity of film thickness, easy control of film thickness, low volatile organic compounds, and strong substrate compatibility, especially for the textured silicon surface in perovskite-silicon tandem solar cells. However, in the two-step process, whether spin coating or evaporation is used to prepare perovskite absorber layers, there are disadvantages such as high difficulty in additive engineering, incomplete conversion, and lower efficiency compared to solution methods. The most significant challenge is the incomplete conversion of lead-containing inorganic metal salts, which leads to increased defects in the perovskite absorber layer, severe non-radiative recombination, and a significant decline in the photoelectric performance of the device.

[0003] Therefore, how to further improve the conversion degree of metal inorganic salts in the two-step process, reduce defects in the perovskite absorber layer, alleviate non-radiative recombination, and thus obtain devices with excellent performance is an urgent technical problem to be solved. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the present invention aims to provide a perovskite absorber layer, its preparation method, and its applications. This invention introduces a metal salt solution containing bicarbonate ions onto the surface of a metal inorganic salt layer. Through a stepped heating annealing process, carbon dioxide volatilization is generated, creating pores and resulting in a loose, porous metal inorganic salt layer. Based on this, the introduction of organic cation salts allows them to penetrate the interior of the metal inorganic salt layer, achieving a high degree of perovskite phase transformation. Simultaneously, the residual bicarbonate ion metal salt solution can partially passivate perovskite defects. Therefore, the perovskite absorber layer prepared by this method exhibits significantly reduced defects and mitigated non-radiative recombination, resulting in a significant improvement in the photoelectric performance of the device.

[0005] To achieve this objective, the present invention adopts the following technical solution:

[0006] In a first aspect, the present invention provides a method for preparing a perovskite absorber layer, characterized in that the preparation method includes the following steps:

[0007] Prepare a metal inorganic salt layer.

[0008] A metal salt solution containing bicarbonate ions is coated onto the surface of the inorganic metal salt layer, and then subjected to multi-stage heating and annealing to obtain a porous inorganic metal salt layer.

[0009] An organic cation salt is introduced onto the surface of the porous metal inorganic salt layer, followed by annealing, to obtain the perovskite absorber layer.

[0010] This invention first introduces a metal salt solution containing bicarbonate ions onto the surface of a metal inorganic salt layer. Then, through multi-stage heating and annealing, carbon dioxide volatilization is produced, creating pores and thus forming a porous metal inorganic salt layer. Based on this, the introduction of organic cation salts allows them to penetrate into the interior of the metal inorganic salt layer, achieving a high degree of perovskite phase transformation. Simultaneously, the residual bicarbonate ion metal salt solution can partially passivate perovskite defects. Therefore, the perovskite absorber layer prepared by this method has significantly reduced defects and mitigated non-radiative recombination, resulting in a significant improvement in the photoelectric performance of the device.

[0011] In this invention, multi-stage heating and annealing can effectively adjust the porosity and pore size in the metal inorganic salt layer, thereby improving the degree of perovskite phase transformation and enhancing the photoelectric conversion efficiency of the device.

[0012] For example, the chemical equation for the production of carbon dioxide from a metal salt containing bicarbonate ions is as follows:

[0013] 2HXCO3→X2CO3+CO2↑+H2O, where X can be sodium ion, cesium ion, rubidium ion, or potassium ion, etc.

[0014] Preferably, the metal inorganic salt layer includes any one or a combination of at least two of lead salts, tin salts, or cesium salts.

[0015] Preferably, the lead salt is a lead halide salt, such as lead iodide, lead bromide, or lead chloride.

[0016] Preferably, the tin salt is a tin halide.

[0017] Preferably, the cesium salt is a cesium halide salt, for example, it may be a cesium bromide, cesium iodide or a cesium chloride layer.

[0018] Preferably, the method for preparing the metal inorganic salt layer includes thermal evaporation or solution deposition. For example, the solution deposition method may be a spin coating method.

[0019] Preferably, the thickness of the metal inorganic salt layer is 200-300 nm, for example, it can be 200 nm, 250 nm or 300 nm.

[0020] Preferably, the metal salt solution containing bicarbonate ions includes any one or a combination of at least two of sodium bicarbonate solution, cesium bicarbonate solution, rubidium bicarbonate solution, or potassium bicarbonate solution.

[0021] Preferably, the concentration of the metal salt solution containing bicarbonate ions is 0.05-0.2 mg / mL, for example, it can be 0.05 mg / mL, 0.1 mg / mL, 0.15 mg / mL or 0.2 mg / mL, and more preferably 0.1-0.15 mg / mL.

[0022] In this invention, if the concentration of the metal salt solution containing bicarbonate ions is too low, too little carbon dioxide will be generated, which will not be able to effectively create pores and will not improve the porosity of the metal inorganic salt layer. If the concentration of the metal salt solution containing bicarbonate ions is too high, too much carbon dioxide gas will be generated, which will affect the morphology of the film and create more non-radiative recombination centers. It will also affect the contact effect with the upper interface functional layer, which is not conducive to the quality of perovskite phase film formation.

[0023] Preferably, the specific steps of the coating include:

[0024] A metal salt solution containing bicarbonate ions is coated onto the surface of a metal inorganic salt layer, allowed to stand, and then spin-coated.

[0025] In this invention, the purpose of allowing the solution to stand is to allow the metal salt solution containing bicarbonate ions to fully contact the metal inorganic salt layer and immerse it downwards.

[0026] Preferably, the settling time is 25-35 seconds, for example, 25 seconds, 30 seconds, or 35 seconds.

[0027] Preferably, the spin coating rate is 2500-3500 rpm, for example, it can be 2500 rpm, 3000 rpm or 3500 rpm.

[0028] In this invention, a suitable spin coating rate is beneficial for the appropriate removal of solvent, thereby increasing the contact degree and time between the metal salt containing bicarbonate ions and the metal inorganic salt layer.

[0029] Preferably, the spin coating time is 25-35 seconds, for example, 25 seconds, 30 seconds, or 35 seconds.

[0030] Preferably, the multi-stage heating annealing includes a first stage, a second stage, a third stage, and a fourth stage performed sequentially.

[0031] Preferably, the temperature of the first stage is 30-60℃, for example, 30℃, 40℃, 50℃ or 60℃, and the annealing time is 1-3min, for example, 1min, 2min or 3min.

[0032] Preferably, the temperature of the second stage is 60-80℃, for example, 60℃, 65℃, 70℃, 75℃ or 80℃, and the annealing time is 1-3 minutes, for example, 1 minute, 2 minutes or 3 minutes.

[0033] In this invention, a second stage of annealing is performed based on the first stage, which can further increase the porosity and pore size of the metal inorganic salt layer.

[0034] Preferably, the temperature of the third stage is 80-100℃, for example, 80℃, 85℃, 90℃, 95℃ or 100℃, and the annealing time is 1-3 minutes, for example, 1 minute, 2 minutes or 3 minutes.

[0035] In this invention, the third-stage annealing can further increase the porosity and pore size.

[0036] Preferably, the temperature of the fourth stage is 90-120℃, for example, 90℃, 100℃, 110℃ or 120℃, and the annealing time is 4-6 minutes, for example, 4 minutes, 5 minutes or 6 minutes.

[0037] In this invention, the fourth-stage annealing, as a higher-temperature annealing process, can significantly increase the porosity and pore size of the metal inorganic salt layer.

[0038] Preferably, the atmosphere for the multi-stage heating and annealing is an inert atmosphere. For example, it can be argon or nitrogen.

[0039] Preferably, the organic cations in the organic cation salt include methylamine cations and / or formamidin cations.

[0040] Preferably, the method for introducing the organic cation salt includes thermal evaporation or solution method.

[0041] Preferably, the annealing temperature is 130-180℃, for example, 130℃, 140℃, 150℃, 160℃, 170℃ or 180℃, and the annealing time is 10-20min, for example, 10min, 11min, 12min, 13min, 15min, 18min, 19min or 20min.

[0042] Preferably, the preparation method includes the following steps:

[0043] (1) Place the inorganic metal salt material in a thermal evaporation equipment and control the evaporation rate of the inorganic metal salt material to obtain an inorganic metal salt layer with a thickness of 200-300nm.

[0044] (2) Apply a metal salt solution containing bicarbonate ions at a concentration of 0.05-0.2 mg / mL to the surface of the metal inorganic salt layer, let it stand for 25-35 s, then spin coat at 2500-3500 rpm for 25-35 s, then perform a first stage annealing at 30-60℃ for 1-3 min, a second stage annealing at 60-80℃ for 1-3 min, a third stage annealing at 80-100℃ for 1-3 min, and a fourth stage annealing at 90-120℃ for 4-6 min. After the annealing is completed, spin coat with an organic solvent (e.g., isopropanol) and rinse away the residual solute (e.g., cesium carbonate) to obtain a porous metal inorganic salt layer.

[0045] (3) Spin-coat the surface of the porous metal inorganic salt layer with an organic salt solution, and then anneal at 130-180°C for 10-20 min to obtain the perovskite absorption layer.

[0046] In a second aspect, the present invention provides a perovskite absorber layer, which is prepared by the preparation method described in the first aspect.

[0047] Thirdly, the present invention provides a solar cell, the solar cell comprising a perovskite absorber layer as described in the second aspect; the solar cell is a single-junction perovskite solar cell or a perovskite-silicon tandem solar cell.

[0048] Preferably, the single-junction perovskite solar cell comprises a stacked conductive substrate, a hole transport layer, a perovskite absorber layer, an electron transport layer, and electrodes.

[0049] For example, the conductive substrate can be ITO glass or FTO glass, etc.; the hole transport layer can be a nickel oxide layer or a self-assembled monolayer, etc.; the electron transport layer can be C 60 The electrode can be Ag or Au, etc., and the electrode can be a layer and / or a SnO2 layer.

[0050] Fourthly, the present invention provides a photovoltaic module, the photovoltaic module comprising the solar cell as described in the third aspect.

[0051] The numerical range described in this invention includes not only the point values ​​listed above, but also any point values ​​within the numerical ranges not listed above. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific point values ​​included in the range.

[0052] Compared with the prior art, the present invention has the following beneficial effects:

[0053] This invention introduces a metal salt solution containing bicarbonate ions onto the surface of a metal inorganic salt layer. Through a stepped heating annealing process, carbon dioxide volatilization is generated, creating pores and producing a porous metal inorganic salt layer. Based on this, the introduction of organic cation salts allows them to penetrate the interior of the metal inorganic salt layer, achieving a high degree of perovskite phase transformation. Simultaneously, the residual bicarbonate ion metal salt solution can partially passivate perovskite defects. Therefore, the perovskite absorber layer prepared by this method has significantly fewer defects and reduced non-radiative recombination, resulting in a significant improvement in the photoelectric performance of the device. Attached Figure Description

[0054] Figure 1 This is a schematic diagram of the structure of a single-junction perovskite solar cell provided in Embodiment 1 of the present invention.

[0055] Among them, 1-ITO conductive glass; 2-hole transport layer; 3-perovskite absorber layer; 4-electron transport layer; 5-electrode. Detailed Implementation

[0056] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0057] Example 1

[0058] This embodiment provides a method for preparing a perovskite absorber layer, characterized in that the preparation method includes the following steps:

[0059] (1) Preparation of the metal inorganic salt layer, the specific steps of which include:

[0060] Lead iodide and cesium bromide were placed in a thermal evaporation equipment and evacuated to a vacuum of 2 × 10⁻⁶. -5 Pa, controlling the evaporation rate of lead iodide to be The evaporation rate of cesium bromide is A metal inorganic salt layer with a thickness of 250 nm was obtained.

[0061] (2) A cesium bicarbonate solution with a concentration of 0.1 mg / mL was applied to the surface of the metal inorganic salt layer and left to stand for 30 seconds. Then, it was spin-coated at 3000 rpm for 30 seconds. Subsequently, a multi-stage annealing process was carried out under an argon atmosphere, including: a first stage annealing at 50 °C for 2 minutes, a second stage annealing at 70 °C for 2 minutes, a third stage annealing at 90 °C for 2 minutes, and a fourth stage annealing at 100 °C for 5 minutes. After the process, isopropanol solvent was spin-coated to wash away the residual solute (cesium carbonate) and a porous metal inorganic salt layer was obtained.

[0062] (3) Spin-coat the surface of the porous metal inorganic salt layer with a 0.65 mol / L organic salt solution (including formamidine bromide and formamidine iodide in a mass ratio of 1:1) and then anneal at 150 °C for 15 min to obtain the perovskite absorber layer.

[0063] This embodiment also provides a single-junction perovskite solar cell, the structural schematic diagram of which is shown below. Figure 1 As shown, the device includes a stacked ITO conductive glass 1, a hole transport layer 2, a perovskite absorber layer 3 as described above, an electron transport layer 4, and an electrode 5; wherein, the hole transport layer 2 is made of MeO-2PACZ (2,2'-(1,4-phenylenebis(4,1-phenylene))bis(4,6-di-tert-butylphenoxy)dimethylsilane), and the electron transport layer 4 comprises stacked C atoms with a thickness of 20 nm. 60 The electrode 5 is made of Ag with a thickness of 120 nm and a SnO2 layer with a thickness of 15 nm.

[0064] This embodiment also provides a method for fabricating the above-mentioned single-junction perovskite solar cell, including the following steps:

[0065] (a) Using ITO conductive glass as the conductive substrate, the glass was ultrasonically treated with glass cleaner, deionized water, ethanol, acetone, isopropanol and ethanol for 15 min in sequence, then dried with dry air, and then treated with ultraviolet-ozone for 20 min.

[0066] (b) A MeO-2PACZ solution with a concentration of 0.5 mg / mL was spin-coated onto ITO conductive glass and annealed at 100 °C for 10 min to form a hole transport layer.

[0067] (c) Using the perovskite absorber layer preparation method described above, a perovskite absorber layer with a thickness of 500 nm is prepared on the hole transport layer.

[0068] (d) A 20 nm thick C layer was prepared on the perovskite absorber layer using a thermal evaporation method. 60 Layer, evaporation rate is

[0069] (e) Using atomic layer deposition (ALD) on C 60 A SnO2 layer with a thickness of 15 nm was prepared on the layer.

[0070] (f) An Ag layer with a thickness of 120 nm was prepared on the SnO2 layer using a thermal evaporation method at a deposition rate of [missing information].

[0071] Example 2

[0072] This embodiment provides a method for preparing a perovskite absorber layer, characterized in that the preparation method includes the following steps:

[0073] (1) Preparation of the metal inorganic salt layer, the specific steps of which include:

[0074] Lead iodide and cesium bromide were placed in a thermal evaporation equipment and evacuated to a vacuum of 2 × 10⁻⁶. -5 Pa, controlling the evaporation rate of lead iodide to be The evaporation rate of cesium bromide is A metal inorganic salt layer with a thickness of 200 nm was obtained.

[0075] (2) A cesium bicarbonate solution with a concentration of 0.05 mg / mL was applied to the surface of the metal inorganic salt layer and left to stand for 35 s. Then, it was spin-coated at 2500 rpm for 35 s. Subsequently, a multi-stage heating annealing was performed under an argon atmosphere, including: a first stage annealing at 40 °C for 3 min, a second stage annealing at 60 °C for 3 min, a third stage annealing at 80 °C for 3 min, and a fourth stage annealing at 90 °C for 6 min. After the annealing was completed, isopropanol solvent was spin-coated to wash away the residual solute (cesium carbonate) and a porous metal inorganic salt layer was obtained.

[0076] (3) A 0.65 mol / L organic salt solution (including formamidine bromide and formamidine iodide in a mass ratio of 1:1) was spin-coated onto the surface of the porous metal inorganic salt layer, and then annealed at 130 °C for 20 min to obtain the perovskite absorber layer.

[0077] This embodiment also provides a single-junction perovskite solar cell, comprising a stacked ITO conductive glass, a hole transport layer, a perovskite absorber layer as described above, an electron transport layer, and an electrode; wherein, the hole transport layer is made of MeO-2PACZ (2,2'-(1,4-phenylenebis(4,1-phenylene))bis(4,6-di-tert-butylphenoxy)dimethylsilane), and the electron transport layer comprises stacked C atoms with a thickness of 20 nm. 60 The material consists of a SnO2 layer with a thickness of 15 nm and an Ag electrode with a thickness of 120 nm.

[0078] This embodiment also provides a method for fabricating the above-mentioned single-junction perovskite solar cell, including the following steps:

[0079] (a) Using ITO conductive glass as the conductive substrate, the glass was ultrasonically treated with glass cleaner, deionized water, ethanol, acetone, isopropanol and ethanol for 15 min in sequence, then dried with dry air, and then treated with ultraviolet-ozone for 20 min.

[0080] (b) A MeO-2PACZ solution with a concentration of 0.5 mg / mL was spin-coated onto ITO conductive glass and annealed at 100 °C for 10 min to form a hole transport layer.

[0081] (c) Using the perovskite absorber layer preparation method described above, a perovskite absorber layer with a thickness of 500 nm is prepared on the hole transport layer.

[0082] (d) A 20 nm thick C layer was prepared on the perovskite absorber layer using a thermal evaporation method. 60 Layer, evaporation rate is

[0083] (e) Using atomic layer deposition (ALD) on C 60 A SnO2 layer with a thickness of 15 nm was prepared on the layer.

[0084] (f) An Ag layer with a thickness of 120 nm was prepared on the SnO2 layer using a thermal evaporation method at a deposition rate of [missing information].

[0085] Example 3

[0086] This embodiment provides a method for preparing a perovskite absorber layer, characterized in that the preparation method includes the following steps:

[0087] (1) Preparation of the metal inorganic salt layer, the specific steps of which include:

[0088] Lead iodide and cesium bromide were placed in a thermal evaporation equipment and evacuated to a vacuum of 2 × 10⁻⁶. -5 Pa, controlling the evaporation rate of lead iodide to be The evaporation rate of cesium bromide is A metal inorganic salt layer with a thickness of 300 nm was obtained.

[0089] (2) A cesium bicarbonate solution with a concentration of 0.2 mg / mL was applied to the surface of the metal inorganic salt layer and left to stand for 25 seconds. Then, it was spin-coated at 3500 rpm for 25 seconds. Subsequently, a multi-stage annealing process was carried out under an argon atmosphere, including: a first stage annealing at 60 °C for 1 min, a second stage annealing at 80 °C for 1 min, a third stage annealing at 100 °C for 1 min, and a fourth stage annealing at 110 °C for 4 min. After the process, isopropanol solvent was spin-coated to wash away the residual solute (cesium carbonate) and a porous metal inorganic salt layer was obtained.

[0090] (3) Spin-coat the porous metal inorganic salt layer with a 0.65 mol / L organic salt solution (including formamidine bromide and formamidine iodide in a mass ratio of 1:1) and then anneal at 180°C for 10 min to obtain the perovskite absorber layer.

[0091] This embodiment also provides a single-junction perovskite solar cell, comprising a stacked ITO conductive glass, a hole transport layer, a perovskite absorber layer as described above, an electron transport layer, and an electrode; wherein, the hole transport layer is made of MeO-2PACZ (2,2'-(1,4-phenylenebis(4,1-phenylene))bis(4,6-di-tert-butylphenoxy)dimethylsilane), and the electron transport layer comprises stacked C atoms with a thickness of 20 nm. 60 The material consists of a SnO2 layer with a thickness of 15 nm and an Ag electrode with a thickness of 120 nm.

[0092] This embodiment also provides a method for fabricating the above-mentioned single-junction perovskite solar cell, including the following steps:

[0093] (a) Using ITO conductive glass as the conductive substrate, the glass was ultrasonically treated with glass cleaner, deionized water, ethanol, acetone, isopropanol and ethanol for 15 min in sequence, then dried with dry air, and then treated with ultraviolet-ozone for 20 min.

[0094] (b) A MeO-2PACZ solution with a concentration of 0.5 mg / mL was spin-coated onto ITO conductive glass and annealed at 100 °C for 10 min to form a hole transport layer.

[0095] (c) Using the perovskite absorber layer preparation method described above, a perovskite absorber layer with a thickness of 500 nm is prepared on the hole transport layer.

[0096] (d) A 20 nm thick C layer was prepared on the perovskite absorber layer using a thermal evaporation method. 60 Layer, evaporation rate is

[0097] (e) Using atomic layer deposition (ALD) on C 60 A SnO2 layer with a thickness of 15 nm was prepared on the layer.

[0098] (f) An Ag layer with a thickness of 120 nm was prepared on the SnO2 layer using a thermal evaporation method at a deposition rate of [missing information].

[0099] Example 4

[0100] The difference between this embodiment and embodiment 1 is that the cesium bicarbonate solution in step (2) is replaced with a rubidium bicarbonate solution.

[0101] The remaining preparation methods and parameters are consistent with those in Example 1.

[0102] Example 5

[0103] The difference between this embodiment and embodiment 1 is that the concentration of the cesium bicarbonate solution in step (2) is 0.05 mg / mL.

[0104] The remaining preparation methods and parameters are consistent with those in Example 1.

[0105] Example 6

[0106] The difference between this embodiment and embodiment 1 is that the concentration of the cesium bicarbonate solution in step (2) is 0.2 mg / mL.

[0107] The remaining preparation methods and parameters are consistent with those in Example 1.

[0108] Example 7

[0109] The difference between this embodiment and embodiment 1 is that the concentration of the cesium bicarbonate solution in step (2) is 0.01 mg / mL.

[0110] The remaining preparation methods and parameters are consistent with those in Example 1.

[0111] Example 8

[0112] The difference between this embodiment and embodiment 1 is that the concentration of the cesium bicarbonate solution in step (2) is 0.5 mg / mL.

[0113] The remaining preparation methods and parameters are consistent with those in Example 1.

[0114] Example 9

[0115] The difference between this embodiment and Embodiment 1 is that the first stage of annealing is not performed.

[0116] The remaining preparation methods and parameters are consistent with those in Example 1.

[0117] Example 10

[0118] The difference between this embodiment and Embodiment 1 is that the fourth stage of annealing is not performed.

[0119] The remaining preparation methods and parameters are consistent with those in Example 1.

[0120] Comparative Example 1

[0121] The difference between this comparative example and Example 1 is that step (2) is omitted.

[0122] The remaining preparation methods and parameters are consistent with those in Example 1.

[0123] Comparative Example 2

[0124] The difference between this comparative example and Example 1 is that the multi-stage heating annealing in step (2) is replaced by constant temperature annealing, with an annealing temperature of 80°C and a time of 11 min.

[0125] The remaining preparation methods and parameters are consistent with those in Example 1.

[0126] Comparative Example 3

[0127] The difference between this comparative example and Example 1 is that the multi-stage heating annealing in step (2) is replaced by constant temperature annealing, with an annealing temperature of 100°C and a time of 11 min.

[0128] The remaining preparation methods and parameters are consistent with those in Example 1.

[0129] Comparative Example 4

[0130] The difference between this comparative example and Example 1 is that the multi-stage heating annealing in step (2) is replaced by isothermal annealing, with an annealing temperature of 120°C and a time of 11 min.

[0131] The remaining preparation methods and parameters are consistent with those in Example 1.

[0132] Comparative Example 5

[0133] The difference between this comparative example and Example 1 is that the multi-stage heating and annealing described in step (2) is not performed.

[0134] The remaining preparation methods and parameters are consistent with those in Example 1.

[0135] Performance testing

[0136] The photoelectric performance of the single-junction perovskite solar cells provided in the above embodiments and comparative examples was tested under the following conditions: AM1.5, 1000 W / m 2 , 25±2℃.

[0137] The test results are shown in Table 1.

[0138] Table 1

[0139]

[0140]

[0141] analyze:

[0142] As shown in the table above, this invention introduces a metal salt solution containing bicarbonate ions onto the surface of a metal inorganic salt layer. Through multi-stage heating and annealing, carbon dioxide volatilization is generated, creating pores and producing a porous metal inorganic salt layer. Based on this, the introduction of organic cation salts allows them to penetrate the interior of the metal inorganic salt layer, achieving a high degree of perovskite phase transformation. Simultaneously, the residual carbonate ion metal salt solution can partially passivate perovskite defects. Therefore, the perovskite absorber layer prepared by this method has significantly fewer defects and reduced non-radiative recombination. The photoelectric conversion efficiency of the perovskite solar cell prepared based on this method can reach 21.22%.

[0143] As can be seen from Examples 1 and 4, different types of metal salt solutions containing bicarbonate ions all have an effect on perovskite solar cells.

[0144] As shown in Examples 1, 5-6, and 7-8, when the concentration of the bicarbonate-containing metal salt is maintained between 0.05-0.2 mg / mL, the photoelectric conversion efficiency of the device can be above 19%. If the concentration of the cesium bicarbonate solution is too low, the carbon dioxide produced by heating decomposition will be insufficient, failing to effectively create pores and thus not significantly improving device performance. If the concentration of the cesium bicarbonate solution is too high, the generated carbon dioxide gas will be excessive, affecting the film morphology and creating more non-radiative recombination centers, while also affecting the contact effect with the upper interface functional layer.

[0145] As can be seen from Examples 1, 9-10 and Comparative Examples 2-5, the post-annealing method of metal salts containing bicarbonate has a significant impact on device performance. Heating at a constant temperature or not heating at all cannot meet the required porosity and number of pores of the thin film, resulting in a decrease in device performance.

[0146] In summary, the introduction of bicarbonate-containing metal salts is very effective in improving device performance. However, it is necessary to control the generation rate and flow rate of carbon dioxide gas by precisely adjusting its concentration and the heating and annealing temperature and method, so as to effectively improve the porosity of the thin film and improve the photoelectric conversion efficiency of the device.

[0147] The applicant declares that the present invention is illustrated by the above embodiments, but the present invention is not limited to the above process steps, that is, it does not mean that the present invention must rely on the above process steps to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions of the raw materials used in the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for preparing a perovskite absorber layer, characterized in that, The preparation method includes the following steps: Preparation of metal inorganic salt layers; A metal salt solution containing bicarbonate ions is coated on the surface of the metal inorganic salt layer, and multi-stage heating annealing is performed to obtain a porous metal inorganic salt layer. An organic cation salt is introduced onto the surface of the porous metal inorganic salt layer, followed by annealing, to obtain the perovskite absorber layer.

2. The preparation method according to claim 1, characterized in that, The metal inorganic salt layer includes any one or a combination of at least two of lead salts, tin salts, or cesium salts; Preferably, the method for preparing the metal inorganic salt layer includes thermal evaporation or solution deposition. Preferably, the thickness of the metal inorganic salt layer is 200-300 nm.

3. The preparation method according to claim 1 or 2, characterized in that, The metal salt solution containing bicarbonate ions includes any one or a combination of at least two of sodium bicarbonate solution, cesium bicarbonate solution, rubidium bicarbonate solution, or potassium bicarbonate solution. Preferably, the concentration of the metal salt solution containing bicarbonate ions is 0.05-0.2 mg / mL, and more preferably 0.1-0.15 mg / mL.

4. The preparation method according to any one of claims 1-3, characterized in that, The specific steps of the coating process include: A metal salt solution containing bicarbonate ions is coated onto the surface of a metal inorganic salt layer, allowed to stand, and then spin-coated.

5. The preparation method according to claim 4, characterized in that, The settling time is 25-35 seconds; Preferably, the spin coating rate is 2500-3500 rpm; Preferably, the spin coating time is 25-35 seconds.

6. The preparation method according to any one of claims 1-5, characterized in that, The multi-stage heating annealing includes a first stage, a second stage, a third stage, and a fourth stage performed sequentially; Preferably, the annealing temperature in the first stage is 30-60℃, and the annealing time is 1-3 min; Preferably, the annealing temperature in the second stage is 60-80℃, and the annealing time is 1-3 min; Preferably, the annealing temperature in the third stage is 80-100℃, and the annealing time is 1-3 minutes; Preferably, the annealing temperature in the fourth stage is 90-120℃, and the annealing time is 4-6 min; Preferably, the atmosphere for the multi-stage heating and annealing is an inert atmosphere.

7. The preparation method according to any one of claims 1-6, characterized in that, The organic cations in the organic cation salt include methylamine cations and / or formamidin cations; Preferably, the method for introducing the organic cationic salt includes thermal evaporation or solution method; Preferably, the annealing temperature is 130-180℃ and the annealing time is 10-20 min.

8. A perovskite absorber layer, characterized in that, The perovskite absorber layer is prepared using the preparation method described in any one of claims 1-7.

9. A solar cell, characterized in that, The solar cell includes the perovskite absorber layer as described in claim 8; The solar cell is a single-junction perovskite solar cell or a perovskite-silicon tandem solar cell.

10. A photovoltaic module, characterized in that, The photovoltaic module includes the solar cell as described in claim 9.

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