A lead halide composite film layer, its preparation method and application

Abstract

The present invention provides a lead halide composite film layer, a preparation method and an application thereof. The lead halide composite film layer comprises a first PbX2 layer, a CsX' layer and a second PbX”2 layer which are laminated in sequence; wherein X, X' and X” independently comprise any one or a combination of at least two of Clˉ, Brˉ or Iˉ. The present invention constructs a lead halide composite film layer with a "sandwich" structure. This structure can improve the morphology of the lead halide composite film layer. The cesium halide in the middle layer can react with the lead halides on both sides, increasing the number of holes and the size of the pores, and promoting sufficient reaction with the organic salt solution, thereby forming a high-quality perovskite film, thus improving the photovoltaic performance and stability of the perovskite solar cell. In addition, the halogen ions in the "sandwich" structure can regulate the band gap of the perovskite, which enables the prepared perovskite film layer to better adapt to different types of batteries.

Description

Technical Field

[0001] The present invention belongs to the field of photovoltaic cells, and particularly relates to a lead halide composite film layer, a preparation method thereof, and an application thereof. Background Art

[0002] With the continuous development of the global economy and technology, the shortage of energy resources poses a huge challenge to mankind. As the most abundant renewable energy source in nature, solar energy plays a crucial role in solving the energy shortage problem, especially solar cells that convert light energy into electrical energy. The latest generation of solar cells is a new concept solar cell, among which perovskite solar cells have received extensive attention from scientific researchers due to their advantages such as high efficiency, low cost, simple thin film preparation, and adjustable bandgap. The development of perovskite solar cells has been particularly rapid, and the cell efficiency has increased from 3.8% in 2009 to the current 25.7%.

[0003] For perovskite solar cells, the preparation of perovskite thin films is particularly important. Currently, the methods for preparing perovskite thin films can be roughly divided into solution methods, vacuum methods, and vacuum-solution methods. The solution method is to dissolve the perovskite precursor material into an organic solvent such as N,N-dimethylformamide or dimethyl sulfoxide to form a solution, and then prepare a wet film through methods such as spin coating, blade coating, spray coating, or slot die coating, and then form a perovskite thin film through annealing. The vacuum method is to directly deposit the perovskite precursor material onto the substrate in a vacuum state through physical vapor deposition (PVD) or chemical vapor deposition (CVD), and then anneal to promote crystallization to form a perovskite thin film through co-evaporation or sequential evaporation. Common PVD mainly includes: vacuum evaporation, sputtering coating, and ion coating. The vacuum-solution method is a relatively novel method for preparing perovskite thin films. First, a lead iodide thin film is prepared by vacuum evaporation using the common PVD method, and then an organic amine salt solution is coated by methods such as spin coating, blade coating, or slot die coating, and a perovskite thin film is formed after annealing.

[0004] For example, CN115425156A discloses a method for preparing a perovskite thin film by a two-step method, including the following steps: preparing a first film layer by a vacuum method, preparing a second film layer by a solution method, and heat-treating to form a perovskite thin film.

[0005] CN115241385A discloses a perovskite film layer, a preparation method thereof, a preparation system, and a perovskite battery. The preparation method of the perovskite film layer includes the following steps: depositing a vapor deposition raw material on the surface of a moving perovskite substrate by vacuum evaporation to form a first film layer; coating a solution of an organic salt or vapor depositing the organic salt on the surface of the first film layer, and obtaining a perovskite film layer after heat treatment; the vapor deposition raw material is vapor deposited using a linear evaporation source; the vapor deposition raw material includes a first raw material, and the first raw material includes lead halide.

[0006] Although the vacuum solution method can avoid the use of organic solvents N,N-dimethylformamide and dimethyl sulfoxide that are harmful to the human body, the preparation of perovskite films by the vacuum solution method also has certain shortcomings. The main problem is that the lead iodide films prepared by the PVD evaporation method are mostly cross-stacked in the form of lead iodide nanosheets. The film is relatively dense, which is not conducive to the penetration of the second step organic amine salt solution, resulting in the remaining lead iodide at the bottom unable to react with the organic amine salt to form perovskite. In addition, on the one hand, the bottom lead iodide layer will form a carrier recombination center, resulting in unnecessary non-radiative recombination, a certain loss of photocurrent, and a decrease in the performance of perovskite solar cells. On the other hand, there are a large number of defects such as dislocations and iodine vacancies inside the perovskite layer. The above defects are not conducive to the preparation of high-quality perovskite films, and pinhole-like holes are prone to appear. Not only that, studies have shown that excessive lead iodide will have an adverse effect on the stability of the device, resulting in a decrease in device stability.

[0007] Therefore, how to effectively improve the quality of perovskite films and enhance the photovoltaic performance and stability of perovskite solar cells is a technical problem that needs to be solved urgently. Summary of the invention

[0008] In view of the deficiencies of the prior art, the purpose of the present invention is to provide a lead halide composite film layer and a preparation method and application thereof. The present invention constructs a lead halide composite film layer with a "sandwich" structure, which can improve the morphology of the lead halide composite film layer. The cesium halide in the middle layer can react with the lead halide on both sides to increase the number of holes and the size of the pores, and promote full reaction with the organic salt solution to form a high-quality perovskite film, thereby improving the photovoltaic performance and stability of the perovskite solar cell. In addition, the halogen ions in the "sandwich" structure can regulate the band gap of the perovskite, which makes the prepared perovskite film layer better adapted to different types of batteries.

[0009] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0010] In a first aspect, the present invention provides a lead halide composite film layer, wherein the lead halide composite film layer comprises a first PbX 2 layer, CsX' layer and the second PbX' 2 layer;

[0011] Wherein, X, X' and X" independently include any one of Clˉ, Brˉ or Iˉ or a combination of at least two thereof.

[0012] The present invention constructs a lead halide composite film layer with a "sandwich" structure, which can improve the morphology of the lead halide composite film layer. The cesium halide in the middle layer can react with the lead halides on both sides, increasing the number of pores and the size of the pores, promoting sufficient reaction with the organic salt solution, forming a high-quality perovskite film, thereby improving the photovoltaic performance and stability of the perovskite solar cell. In addition, the halogen ions in the "sandwich" structure can regulate the band gap of the perovskite, enabling the prepared perovskite film layer to better adapt to different types of batteries.

[0013] Preferably, the thickness of the CsX' layer is 10 - 40 nm, for example, it can be 10 nm, 15 nm, 20 nm, 25 nm, 30 nm, 35 nm or 40 nm, etc.

[0014] In the present invention, if the thickness of the CsX' layer is too small, the number of pinholes in the lead iodide film is small and the pores are small, which is not conducive to the infiltration of the organic salt solution; if the thickness of the CsX' layer is too large, too much CsPbI 3 will be formed, the perovskite band gap increases, and the battery efficiency decreases.

[0015] Preferably, the thickness ratio of the first PbX 2 layer to the second PbX” 2 layer is 1:(0.25 - 4), for example, it can be 1:0.25, 1:0.5, 1:0.75, 1:1, 1:1.25, 1:1.5, 1:1.75, 1:2, 1:2.25, 1:2.5, 1:2.75, 1:3, 1:2.75, 1:3.25, 1:3.5, 1:3.75 or 1:4, etc.

[0016] In the present invention, if the thickness ratio of the first PbX 2 layer to the second PbX” 2 layer is too small, CsX' is close to the first PbX 2 layer, and the upper second PbX” 2 layer is thicker, which is not conducive to the infiltration of the organic salt to the bottom PbX 2 layer; if the thickness ratio of the first PbX 2 layer to the second PbX” 2 layer is too large, that is, the thickness of the first PbX 2 layer is too thick, it will affect the improvement of the device efficiency.

[0017] In the second aspect, the present invention provides a preparation method of the lead halide composite film layer as described in the first aspect, and the preparation method includes:

[0018] Using the thermal evaporation method, PbX 2 , CsX' and PbX” 2 are sequentially evaporated on the substrate to obtain the lead halide composite film layer.

[0019] Preferably, the evaporation of the PbX 2 and the evaporation of the PbX” 2 each independently include primary evaporation and secondary evaporation. It should be noted that the term “independently” means that the method for evaporating the PbX 2 includes primary evaporation and secondary evaporation, and the method for evaporating the PbX” 2 also includes primary evaporation and secondary evaporation. The parameter selection of the method for evaporating the PbX 2 and the method for evaporating the PbX” 2 does not interfere with each other. The same evaporation parameters can be selected for both, or different evaporation parameters can be selected.

[0020] Preferably, the temperature of the primary evaporation is 260 to 270 °C, for example, it can be 260 °C, 261 °C, 262 °C, 263 °C, 264 °C, 265 °C, 266 °C, 267 °C, 268 °C, 269 °C or 270 °C, etc.

[0021] Preferably, the rate of the primary evaporation is For example, it can be or etc.

[0022] Preferably, the temperature of the secondary evaporation is 280 to 290 °C, for example, it can be 280 °C, 281 °C, 282 °C, 283 °C, 284 °C, 285 °C, 286 °C, 287 °C, 288 °C, 289 °C or 290 °C, etc.

[0023] Preferably, the rate of the secondary evaporation is For example, it can be or etc.

[0024] Preferably, the evaporation rate of the CsX' is V, V = V 0 + a×h / 10, where V represents the evaporation rate of the CsX', V 0 represents the initial evaporation rate of the CsX', a is the acceleration of the evaporation rate of the CsX', and h is the thickness of the CsX' layer.

[0025] Preferably, the initial evaporation rate of the CsX' is For example, it can be or etc.

[0026] In the present invention, if the initial evaporation rate of the CsX' is too low, then compared with the PbX 2The reaction is slow and the production beat is slow. If the initial evaporation rate of CsX' is too high, the film evaporation uniformity is poor.

[0027] Preferably, the acceleration of the evaporation rate of the CsX' is For example, it can be

[0028] or etc.

[0029] As a preferred technical solution, the preparation method includes the following steps:

[0030] (1) Using the thermal evaporation method, evaporate part of PbX on the substrate at 260 - 270 °C, 2 and then evaporate another part of PbX at 280 - 290 °C, 2 to obtain the first PbX 2 layer;

[0031] (2) Evaporate CsX' on the first PbX 2 layer to obtain the CsX' layer;

[0032] Among them, the evaporation rate of the CsX' is V = V 0 + a×h / 10, where V represents the evaporation rate of CsX', V 0 represents the initial evaporation rate of CsX', a is the acceleration of the evaporation rate of CsX', and h is the thickness of the CsX' layer;

[0033] (3) Evaporate part of PbX” on the CsX' layer at 260 - 270 °C, 2 and then evaporate another part of PbX” at 280 - 290 °C, 2 to obtain the second PbX” 2 layer.

[0034] In a third aspect, the present invention provides a perovskite film layer, which is obtained by annealing an organic salt solution deposited on the surface of the lead halide composite film layer described in the first aspect.

[0035] Preferably, in the organic salt solution, the cations of the solute include formamidinium ions and / or methylamine ions.

[0036] Preferably, in the organic salt solution, the anions of the solute include any one or a combination of at least two of chloride ions, bromide ions or iodide ions.

[0037] Preferably, the solvent in the organic salt solution includes isopropanol.

[0038] Preferably, the concentration of the organic salt solution is 0.3 - 0.7 mol / mL, and it can be, for example, 0.3 mol / mL, 0.35 mol / mL, 0.4 mol / mL, 0.45 mol / mL, 0.5 mol / mL, 0.55 mol / mL, 0.6 mol / mL, 0.65 mol / mL or 0.7 mol / mL, etc.

[0039] Preferably, the deposition method includes a solution method or a vacuum evaporation method.

[0040] Preferably, the solution method includes any one or a combination of at least two of a doctor blade method, a coating method, a spraying method or an immersion method.

[0041] Preferably, the annealing temperature is 120 - 160 °C, and it can be, for example, 120 °C, 125 °C, 130 °C, 135 °C, 140 °C, 145 °C, 150 °C, 155 °C or 160 °C, etc.

[0042] In a fourth aspect, the present invention provides a perovskite solar cell, and the perovskite solar cell includes the perovskite film layer as described in the third aspect.

[0043] The numerical ranges described in the present invention not only include the point values exemplified above, but also include any point values between the above numerical ranges not exemplified. Due to space limitations and for the sake of brevity, the present invention does not exhaustively list the specific point values included in the range.

[0044] Compared with the prior art, the present invention has the following beneficial effects:

[0045] (1) The present invention constructs a lead halide composite film layer with a "sandwich" structure, and this structure can improve the morphology of the lead halide composite film layer. Cesium halide in the middle layer can react with lead halides on both sides, increasing the number of pores and the size of the pores, promoting sufficient reaction with the organic salt solution, thereby forming a high-quality perovskite thin film, and thus improving the photovoltaic performance and stability of the perovskite solar cell;

[0046] (2) In the lead halide composite film layer with a "sandwich" structure provided by the present invention, the halogen ions in the doped cesium halide can regulate the band gap of the perovskite, which enables the prepared perovskite film layer to better adapt to different types of batteries;

[0047] (3) The lead halide composite film layer provided by the present invention can be widely used in perovskite solar cells, modules and perovskite / silicon heterojunction tandem cells, and can meet the requirements of the production line. Description of the Drawings

[0048] Figure 1This is a diagram of the vacuum evaporation equipment for preparing the lead iodide composite film layer in Example 1 of the present invention.

[0049] Among them, 1 - the first organic evaporation source; 2 - the second organic evaporation source; 3 - the first metal evaporation source; 4 - the second metal evaporation source.

[0050] Figure 2 This is a surface SEM morphology diagram of the lead iodide composite film layer provided in Example 1 of the present invention.

[0051] Figure 3 This is a cross-section SEM morphology diagram of the lead iodide composite film layer provided in Example 1 of the present invention.

[0052] Figure 4 This is a surface SEM morphology diagram of the perovskite film layer prepared in Example 1 of the present invention.

[0053] Figure 5 This is a cross-section SEM morphology diagram of the perovskite film layer prepared in Example 1 of the present invention.

[0054] Figure 6 This is the J-V curve of the perovskite solar cell prepared in Application Example 1 of the present invention.

[0055] Figure 7 This is the J-V curve of the perovskite solar cell prepared in Application Example 2 of the present invention.

[0056] Figure 8 This is a surface SEM morphology diagram of the lead iodide film layer provided in Comparative Example 3 of the present invention.

[0057] Figure 9 This is a cross-section SEM morphology diagram of the lead iodide film layer provided in Comparative Example 3 of the present invention.

[0058] Figure 10 This is a surface SEM morphology diagram of the perovskite film layer provided in Comparative Example 3 of the present invention.

[0059] Figure 11 This is a cross-section SEM morphology diagram of the perovskite film layer provided in Comparative Example 3 of the present invention.

[0060] Figure 12 This is the J-V curve of the perovskite solar cell prepared by applying Comparative Example 4 of the present invention.

[0061] Figure 13 This is the XRD pattern of the perovskite film layers provided in Example 1 and Comparative Example 3 of the present invention. Detailed implementation manners

[0062] The technical solution of the present invention will be further described below through specific embodiments. Those skilled in the art should understand that the embodiments are only for helping to understand the present invention and should not be regarded as specific limitations on the present invention.

[0063] Example 1

[0064] This embodiment provides a lead halide composite film layer, which includes a first PbX layer, a CsX' layer, and a second PbX" layer stacked in sequence. 2 layer, a CsX' layer, and a second PbX" 2 layer.

[0065] Among them, X is Iˉ, X' is Iˉ, X" is Iˉ, the thickness of CsI is 20 nm, and the thickness ratio of the first PbI 2 layer and the second PbI 2 layer is 1:1.

[0066] This embodiment also provides a method for preparing a lead halide composite film layer. The equipment used is as Figure 1 shown. The preparation method includes the following steps:

[0067] (1) Transfer the substrate to the substrate stage of the PVD vacuum evaporation equipment. After the substrate enters the preparation chamber, appropriately place PbI 2 powder and CsI powder on the second organic evaporation source 2 and the first metal evaporation source 3 respectively in advance. Close the chamber valve, and evacuate the preparation chamber. After evacuating to a certain vacuum degree, heat up the second organic evaporation source 2 to deposit the first lead iodide layer. The temperature of the first-stage evaporation of the first lead iodide layer is 265 °C, and the rate is The obtained thickness is 20 nm. The temperature of the second-stage evaporation of the first lead iodide layer is 285 °C, and the rate is The final thickness is 125 nm;

[0068] (2) Then, start to apply current to the first metal evaporation source 3, and slowly increase the current to 68 A. The crystal oscillator can detect the evaporation rate of CsI. The initial rate is After that, the thickness increases by 10 nm, and the evaporation rate increases The thickness of the deposited CsI layer is 20 nm;

[0069] (3) Then, continue to deposit the second lead iodide thin film with a thickness of 125 nm. The evaporation conditions are the same as those for depositing the first lead iodide layer before.

[0070] This embodiment also provides a method for preparing a perovskite film layer, which includes:

[0071] Take out the prepared lead iodide composite film layer and perform spin coating of FAI on its surface. The solvent is isopropyl alcohol solution with a concentration of 0.5 mol / mL, the coating speed is 15 mm / s, the injection volume is 55 uL. Immediately transfer the substrate to a heating stage for annealing after coating, and the annealing temperature is 140 °C.

[0072] Example 2

[0073] This example provides a lead halide composite film layer, and the lead halide composite film layer includes a first PbX layer, a CsX' layer, and a second PbX'' layer that are stacked in sequence. 2 layer, CsX' layer and second PbX'' 2 layer.

[0074] Among them, X is Iˉ, X' is Brˉ, X'' is Iˉ, the thickness of CsBr is 20 nm, and the thickness ratio of the first PbI layer and the second PbI layer is 125:125. 2 layer and second PbI 2 layer is 125:125.

[0075] This example also provides a method for preparing a lead halide composite film layer, and the preparation method includes the following steps:

[0076] (1) Transfer the substrate to the substrate stage of the PVD vacuum evaporation equipment. After the substrate enters the preparation chamber, appropriately place PbI powder and CsBr powder on the second organic evaporation source and the first metal evaporation source in advance, close the chamber valve, and evacuate the preparation chamber. After pumping to a certain vacuum degree, heat up the second organic evaporation source to deposit the first lead iodide layer. The temperature of the first-stage evaporation of the first lead iodide layer is 265 °C, the rate is 2 powder and CsBr powder, close the chamber valve, and evacuate the preparation chamber. After pumping to a certain vacuum degree, heat up the second organic evaporation source to deposit the first lead iodide layer. The temperature of the first-stage evaporation of the first lead iodide layer is 265 °C, the rate is The obtained thickness is 20 nm, the temperature of the second-stage evaporation of the first lead iodide layer is 285 °C, the rate is The final thickness is 125 nm;

[0077] (2) Then, start to apply current to the first metal evaporation source, and the current slowly rises to 68 A. The crystal oscillator can detect the evaporation rate of CsBr, and the initial rate is After that, the thickness increases by 10 nm, and the evaporation rate increases The thickness of the deposited CsI layer is 20 nm;

[0078] (3) Then, continue to deposit the second lead iodide thin film with a thickness of 125 nm, and the evaporation conditions are the same as those for depositing the first lead iodide layer before.

[0079] This example also provides a method for preparing a perovskite film layer, and the preparation method includes:

[0080] Take out the prepared lead iodide composite film layer and perform spin coating of FAI on its surface. The solvent is isopropyl alcohol solution with a concentration of 0.5 mol / mL, the coating speed is 10 mm / s, the injection volume is 50 uL. Immediately transfer the substrate to a heating stage for annealing after coating, and the annealing temperature is 140 °C.

[0081] Example 3

[0082] This example provides a lead halide composite film layer, and the lead halide composite film layer includes a first PbX layer, a CsX' layer, and a second PbX'' layer stacked in sequence. 2 layer, CsX' layer and second PbX” 2 layer.

[0083] Among them, X is Brˉ, X' is Iˉ, X'' is Brˉ, the thickness of CsI is 10 nm, and the thickness ratio of the first PbBr layer and the second PbBr layer is 1:4. 2 layer and second PbBr 2 layer is 1:4.

[0084] This example also provides a method for preparing a lead halide composite film layer, and the preparation method includes the following steps:

[0085] (1) Transfer the substrate to the substrate stage of the PVD vacuum evaporation equipment. After the substrate enters the preparation chamber, appropriately place PbBr powder and CsI powder on the second organic evaporation source and the first metal evaporation source in advance, close the chamber valve, and evacuate the preparation chamber. After pumping to a certain vacuum degree, heat up the second organic evaporation source to deposit the first lead bromide layer. The temperature of the first-stage evaporation of the first lead bromide layer is 260 °C, and the rate is 2 powder and CsI powder, close the chamber valve, and evacuate the preparation chamber. After pumping to a certain vacuum degree, heat up the second organic evaporation source to deposit the first lead bromide layer. The temperature of the first-stage evaporation of the first lead bromide layer is 260 °C, and the rate is The obtained thickness is 20 nm, the temperature of the second-stage evaporation of the first lead bromide layer is 280 °C, and the rate is The final thickness is 50 nm;

[0086] (2) Then, start to apply current to the first metal evaporation source, and slowly increase the current to 65 A. The crystal oscillator can detect the evaporation rate of CsI, and the initial rate is The thickness increases to 10 nm;

[0087] (3) Then, continue to deposit the second lead bromide film with a thickness of 200 nm, and the evaporation conditions are the same as those for depositing the first lead bromide layer before.

[0088] This example also provides a method for preparing a perovskite film layer, and the preparation method includes:

[0089] Take out the prepared lead bromide composite film layer and spray MAI on its surface. The solvent is isopropyl alcohol solution with a concentration of 0.3 mol / mL. The spraying moving speed is 3 cm / s, the gas flow rate is constantly 0.3 mL / min. Immediately after spraying, transfer the substrate to a heating stage for annealing, and the annealing temperature is 120 °C.

[0090] Example 4

[0091] This example provides a lead halide composite film layer, and the lead halide composite film layer includes a first PbX layer, a CsX' layer, and a second PbX” layer stacked in sequence. 2 layer, CsX' layer and second PbX” 2 layer.

[0092] Among them, X is Iˉ, X' is Clˉ, X” is Iˉ, the thickness of CsCl is 40 nm, and the thickness ratio of the first PbI 2 layer and the second PbI 2 layer is 1:0.67.

[0093] This example also provides a preparation method of a lead halide composite film layer, and the preparation method includes the following steps:

[0094] (1) Transfer the substrate to the substrate stage of the PVD vacuum evaporation equipment. After the substrate enters the preparation chamber, appropriately place PbI 2 powder and CsI powder on the second organic evaporation source and the first metal evaporation source in advance, close the chamber valve, and evacuate the preparation chamber. After pumping to a certain vacuum degree, heat up the second organic evaporation source to deposit the first lead iodide layer. The temperature of the first-stage evaporation of the first lead iodide layer is 270 °C, and the rate is The obtained thickness is 20 nm. The temperature of the second-stage evaporation of the first lead iodide layer is 290 °C, and the rate is The final thickness is 150 nm;

[0095] (2) Then, start to apply current to the first metal evaporation source, and slowly increase the current to 70 A. The crystal oscillator can detect the evaporation rate of CsCl. The initial rate is After that, the thickness increases by 10 nm, and the evaporation rate increases The thickness of the deposited CsCl layer is 40 nm;

[0096] (3) Then, continue to deposit the second lead iodide film with a thickness of 100 nm, and the evaporation conditions are the same as those for depositing the first lead iodide layer before.

[0097] This example also provides a preparation method of a perovskite film layer, and the preparation method includes:

[0098] Take out the prepared lead iodide composite film layer and scrape MACl on the surface. The solvent is isopropyl alcohol solution with a concentration of 0.7 mol / mL, the coating speed is 20 mm / s, the injection volume is 60 uL. Immediately transfer the substrate to a heating stage for annealing after coating, and the annealing temperature is 160 °C.

[0099] Example 5

[0100] The difference between this example and Example 1 is that the thickness of the CsI layer is 5 nm.

[0101] The remaining preparation methods and parameters are the same as those in Example 1.

[0102] Example 6

[0103] The difference between this example and Example 1 is that the thickness of the CsI layer is 45 nm.

[0104] The remaining preparation methods and parameters are the same as those in Example 1.

[0105] Example 7

[0106] The difference between this example and Example 1 is that the thickness ratio of the first lead iodide layer to the second lead iodide layer is 1:5.25, so the thickness of the first lead iodide layer is 40 nm and the thickness of the second lead iodide layer is 210 nm.

[0107] The remaining preparation methods and parameters are the same as those in Example 1.

[0108] Example 8

[0109] The difference between this example and Example 1 is that the thickness ratio of the first lead iodide layer to the second lead iodide layer is 1:0.2, so the thickness of the first lead iodide layer is 210 nm and the thickness of the second lead iodide layer is 40 nm.

[0110] The remaining preparation methods and parameters are the same as those in Example 1.

[0111] Example 9

[0112] The difference between this example and Example 1 is that the initial evaporation rate of CsI is

[0113] The remaining preparation methods and parameters are the same as those in Example 1.

[0114] Example 10

[0115] The difference between this example and Example 1 is that the initial evaporation rate of CsI is

[0116] The remaining preparation methods and parameters are the same as those in Example 1.

[0117] Comparative Example 1

[0118] The difference between this comparative example and Example 1 is that the lead halide composite film layer includes a first PbI layer, a second PbI layer, and a CsI layer stacked in sequence, and the preparation method is also replaced by sequentially evaporating the first PbI layer, the second PbI layer, and the CsI layer. 2 layer, second PbI 2 layer and CsI layer, and the preparation method is also replaced by sequentially evaporating the first PbI 2 layer, second PbI 2 layer and CsI layer.

[0119] The remaining preparation methods and parameters are the same as those in Example 1.

[0120] Comparative Example 2

[0121] The difference between this comparative example and Example 1 is that the lead halide composite film layer includes a CsI layer, a first PbI layer, and a second PbI layer stacked in sequence, and the preparation method is also replaced by sequentially evaporating the CsI layer, the first PbI layer, and the second PbI layer. 2 layer and second PbI 2 layer, and the preparation method is also replaced by sequentially evaporating the CsI layer, the first PbI 2 layer and second PbI 2 layer.

[0122] The remaining preparation methods and parameters are the same as those in Example 1.

[0123] Comparative Example 3

[0124] The lead halide composite film layer prepared in this comparative example is a cesium iodide-doped lead iodide film layer, and its preparation method is: using the co-evaporation method, co-evaporating cesium iodide and lead iodide to obtain a cesium iodide-doped lead iodide film layer.

[0125] The method for preparing the perovskite film layer in this comparative example is the same as that in Example 1.

[0126] Comparative Example 4

[0127] The difference between this comparative example and Example 1 is that the lead halide composite film layer only includes a PbI layer, does not add a CsI layer, and there is no evaporation step of CsI in its preparation method. 2 layer, without adding a CsI layer, and there is no evaporation step of CsI in its preparation method.

[0128] The remaining preparation methods and parameters are the same as those in Example 1.

[0129] Figure 2 and Figure 8 respectively show the surface SEM morphology diagrams of the lead iodide composite film layer and the lead iodide film layer provided in Example 1 and Comparative Example 3. From the surface morphology comparison diagram, after doping CsI in the middle of the lead iodide thin film, the number of pores on the surface of the lead iodide thin film increases, and the pore size increases, which is beneficial for the organic amine salt to penetrate to the bottom of the lead iodide thin film.

[0130] Figure 3and Figure 9 respectively show the cross-sectional SEM morphologies of the lead iodide composite film layer and the lead iodide film layer provided in Example 1 and Comparative Example 3. From the SEM cross-sectional morphology comparison diagram, after CsI is doped in the middle of the lead iodide thin film, a delamination phenomenon appears in the middle of the lead iodide thin film. Looking from the vertical direction, the "sandwich structure" PbI 2 / CsI / PbI 2 film has a reduced density and is relatively loose, which is also beneficial for the second-step organic amine salt to penetrate to the bottom of the lead iodide thin film, fully react to form perovskite, and improve the quality of the perovskite thin film.

[0131] Figure 4 and Figure 10 respectively show the surface SEM morphologies of the perovskite film layers provided in Example 1 and Comparative Example 3. It can be seen from the figure that after CsI is doped in the middle of the lead iodide thin film, the pores of the lead iodide thin film increase, which is beneficial for the reaction of the organic amine salt with lead iodide, the perovskite grain size increases, is relatively flat, and there are no pinholes on the surface of the perovskite thin film.

[0132] Figure 5 and Figure 11 respectively show the cross-sectional SEM morphologies of the perovskite film layers provided in Example 1 and Comparative Example 3. It can be seen from the figure that after CsI is doped in the middle of the lead iodide thin film, the perovskite thin film grains increase and there are almost no pores, and the overall quality of the perovskite thin film has been improved.

[0133] Figure 13 shows the XRD patterns of the perovskite film layers provided in Example 1 and Comparative Example 3 of the present invention. It is observed from the perovskite XRD patterns that the perovskite doped with cesium in the middle has better crystallinity and the perovskite peak intensity is significantly enhanced, indicating that doping cesium in the middle of the lead iodide thin film can effectively promote the full reaction of the second-step organic amine salt with lead iodide to form a high-quality perovskite thin film. For the perovskite thin film prepared from the lead iodide thin film, since the number of pores in the lead iodide thin film is small, the second-step organic amine salt solution is not easily penetrated to the bottom of the lead iodide thin film, resulting in incomplete reaction and the formation of a two-layer film of lead iodide / perovskite. For perovskite solar cells, the excess lead iodide thin film will form non-radiative recombination centers, resulting in unnecessary carrier recombination losses, reducing the current density, and ultimately leading to a decline in the photovoltaic performance of the device. After doping with cesium, the surface pores of the lead iodide thin film increase, which is beneficial for the infiltration of the organic amine salt solution, fully reacts with it to generate perovskite, and the quality of the perovskite thin film has been improved.

[0134] Application Example 1

[0135] This application example provides a preparation method of a perovskite solar cell, and the preparation method includes the following steps:

[0136] (1) A magnesium-doped nickel oxide thin film with a thickness of 15 nm was prepared on indium tin oxide (ITO) conductive glass by magnetron sputtering method.

[0137] (2) A perovskite film layer was deposited on the nickel oxide thin film by using the preparation method provided in Example 1.

[0138] (3) By thermal evaporation method, 25 nm thick C was evaporated successively on the perovskite film layer. 60 And 5 nm thick BCP, and finally 80 nm thick Cu electrode was evaporated, and a perovskite solar cell was finally prepared.

[0139] Figure 6 The J-V curve of the perovskite solar cell prepared in this application example is shown. It can be seen from the curve that after CsI is doped in the middle of the lead iodide thin film, the photovoltaic performance parameters of the device are significantly improved, and the hysteresis phenomenon of the device is significantly suppressed.

[0140] Application Example 2

[0141] The difference between this application example and Application Example 1 is that the method for preparing the perovskite film layer in this application example is provided by Example 2.

[0142] The remaining preparation methods and parameters are the same as those in Application Example 1.

[0143] Figure 7 The J-V curve of the perovskite solar cell prepared in this application example is shown. It can be seen from the J-V curve graph that after CsBr is doped in the middle of the lead iodide thin film, due to the doping of Br, the band gap of the perovskite increases, resulting in an increase in the open circuit voltage, and the device performance is also significantly improved, and the device hysteresis phenomenon is also suppressed.

[0144] Application Example 3

[0145] The difference between this application example and Application Example 1 is that the method for preparing the perovskite film layer in this application example is provided by Example 3.

[0146] The remaining preparation methods and parameters are the same as those in Application Example 1.

[0147] Application Example 4

[0148] The difference between this application example and Application Example 1 is that the method for preparing the perovskite film layer in this application example is provided by Example 4.

[0149] The remaining preparation methods and parameters are the same as those in Application Example 1.

[0150] Application Example 5

[0151] The difference between this application example and Application Example 1 is that the method for preparing the perovskite film layer in this application example is provided by Example 5.

[0152] The remaining preparation methods and parameters are the same as those in Application Example 1.

[0153] Application Example 6

[0154] The difference between this application example and Application Example 1 is that the method for preparing the perovskite film layer in this application example is provided by Example 6.

[0155] The remaining preparation methods and parameters are the same as those in Application Example 1.

[0156] Application Example 7

[0157] The difference between this application example and Application Example 1 is that the method for preparing the perovskite film layer in this application example is provided by Example 7.

[0158] The remaining preparation methods and parameters are the same as those in Application Example 1.

[0159] Application Example 8

[0160] The difference between this application example and Application Example 1 is that the method for preparing the perovskite film layer in this application example is provided by Example 8.

[0161] The remaining preparation methods and parameters are the same as those in Application Example 1.

[0162] Application Example 9

[0163] The difference between this application example and Application Example 1 is that the method for preparing the perovskite film layer in this application example is provided by Example 9.

[0164] The remaining preparation methods and parameters are the same as those in Application Example 1.

[0165] Application Example 10

[0166] The difference between this application example and Application Example 1 is that the method for preparing the perovskite film layer in this application example is provided by Example 10.

[0167] The remaining preparation methods and parameters are the same as those in Application Example 1.

[0168] Application Comparative Example 1

[0169] The difference between this application comparative example and Application Example 1 is that the method for preparing the perovskite film layer in this application comparative example is provided by Comparative Example 1.

[0170] The remaining preparation methods and parameters are the same as those in Application Example 1.

[0171] Application Comparative Example 2

[0172] The difference between this application comparative example and Application Example 1 is that the method for preparing the perovskite film layer in this application comparative example is provided by Comparative Example 2.

[0173] The remaining preparation methods and parameters are the same as those in Application Example 1.

[0174] Application Comparative Example 3

[0175] The difference between this application comparative example and Application Example 1 is that the method for preparing the perovskite film layer in this application comparative example is provided by Comparative Example 3.

[0176] The remaining preparation methods and parameters are the same as those in Application Example 1.

[0177] Application Comparative Example 4

[0178] The difference between this application comparative example and Application Example 1 is that the method for preparing the perovskite film layer in this application comparative example is provided by Comparative Example 4.

[0179] The remaining preparation methods and parameters are the same as those in Application Example 1.

[0180] Figure 12 The J-V curve of the perovskite solar cell prepared in this application comparative example is shown. It can be seen from the J-V curve that the short-circuit current density (J sc ) and fill factor (FF) of the cell are relatively low, and the photovoltaic performance of the cell is poor.

[0181] Performance Test

[0182] The perovskite solar cells provided in Application Examples 1-10 and Application Comparative Examples 1-4 were subjected to photovoltaic performance tests and stability tests.

[0183] Test conditions: The effective area of the cells is 1 cm 2 . The J-V curves were all measured under simulated sunlight with AM 1.5, and the irradiance provided by the solar simulator was 100 mW cm -2 .

[0184] The test results are shown in Table 1 and Table 2.

[0185] Table 1

[0186]

[0187]

[0188]

[0189] Table 2

[0190]

[0191]

[0192] Analysis:

[0193] From the data results of Application Examples 1-4, it can be seen that the first PbI 2 layer and the second PbI 2 layer are doped with a 20-nm CsI thin film in the middle to form a "sandwich" structure, and the perovskite solar cell can obtain excellent photovoltaic performance and stability.

[0194] From the comparison of the data results of Application Example 1 and Application Examples 5-6, it can be seen that the optimal thickness of cesium halide is 20 nm. Being too thick or too thin will have an adverse impact on the photovoltaic performance and stability of the battery.

[0195] From the comparison of the data results of Application Example 1 and Application Examples 7-8, it can be seen that if the thickness ratio of the first PbX 2 layer and the second PbX" 2 layer is too small, then CsX' is close to the first PbX 2 layer, and the upper second PbX" 2 layer is thicker, which is not conducive to the infiltration of organic salts into the underlying PbX 2 layer. If the thickness ratio of the first PbX 2 layer and the second PbX" 2 layer is too large, it will affect the improvement of device efficiency.

[0196] From the comparison of the data results of Application Example 1 and Application Examples 9-10, it can be seen that if the initial evaporation rate of CsX' is too low, the reaction with PbX 2 is slow and the production beat is slow; if the initial evaporation rate of CsX' is too high, the film evaporation uniformity is poor. Both situations will reduce the efficiency and stability of the device.

[0197] From the comparison of the data results of Application Example 1 and Comparative Example 1, it can be seen that the photovoltaic performance of the perovskite solar cell with cesium doped in the middle of the lead halide thin film is better than that of the perovskite solar cell prepared by doping cesium on the top of the lead iodide thin film.

[0198] From the comparison of the photovoltaic performance data results of Application Example 1 and Comparative Example 2, it can be seen that the photovoltaic performance of the perovskite solar cell with cesium doped in the middle of the lead halide thin film is better than that of the perovskite solar cell prepared by doping cesium at the bottom of the lead iodide thin film.

[0199] From the comparison of the photovoltaic performance data results of Application Example 1 and Comparative Example 3, it can be seen that the photovoltaic performance of the perovskite solar cell with cesium doped in the middle of the lead halide thin film is better than that of the perovskite solar cell prepared by co-evaporating lead iodide and cesium iodide with cesium doping.

[0200] From the comparison of the photovoltaic performance data results of Application Example 1 and Comparative Example 4, it can be seen that the photovoltaic performance of the perovskite solar cell with cesium doped in the middle of the lead halide thin film is better than that of the perovskite solar cell prepared by the standard lead iodide thin film.

[0201] From the comparison of the stability data of Application Example 1 and Application Comparative Examples 1-4, it can be seen that the stability of the perovskite solar cell with cesium doped in the middle of the lead halide film is better than that of the perovskite solar cells prepared in Application Comparative Examples 1-4.

[0202] The applicant declares that the process method of 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 improvement to the present invention, the equivalent substitution of the raw materials selected for the present invention, the addition of auxiliary components, the selection of specific methods, etc., all fall within the protection scope and the disclosure scope of the present invention.

Claims

1. A lead halide composite film layer, characterized in that, The lead halide composite film layer includes a first PbX layer, a CsX' layer, and a second PbX'' layer that are stacked in sequence; 2 2 layer;​ wherein X, X' and X” independently include any one or a combination of at least two of Clˉ, Brˉ or Iˉ; the thickness of the CsX' layer is 10 - 40 nm; The first PbX 2 layer and the second PbX" 2 layer have a thickness ratio of 1:(0.25 to 4).

2. A method for preparing the lead halide composite film layer according to claim 1, characterized in that, the preparation method includes: Using the thermal evaporation method, PbX is evaporated on the substrate in sequence 2 , CsX', and PbX" 2 , to obtain the lead halide composite film layer.

3. According to the preparation method described in claim 2, characterized in that, The evaporation of the PbX 2 and the evaporation of the PbX” 2 each independently include primary evaporation and secondary evaporation.

4. According to the preparation method described in claim 3, characterized in that, the temperature of the first evaporation is 260 - 270 °C.

5. According to the preparation method described in claim 3, characterized in that, The rate of the primary evaporation is 6. According to the preparation method described in claim 3, characterized in that, the temperature of the second evaporation is 280 - 290 °C.

7. According to the preparation method described in claim 3, characterized in that, The rate of the secondary evaporation is 8. According to the preparation method described in claim 2, characterized in that, The evaporation rate of the CsX' is V, and V = V 0 + a×h / 10, where V represents the evaporation rate of CsX', and V 0 represents the initial evaporation rate of CsX', a is the acceleration of the evaporation rate of CsX', and h is the thickness of the CsX' layer.

9. According to the preparation method described in claim 8, characterized in that, The initial evaporation rate of the CsX' is 10. According to the preparation method described in claim 8, characterized in that, The acceleration of the evaporation rate of the CsX' is 11. According to the preparation method described in claim 2, characterized in that, the preparation method includes the following steps: (1) Using the thermal evaporation method, at 260 - 270 °C on the substrate, evaporate a part of PbX 2 , and then at 280 - 290 °C, evaporate another part of PbX 2 to obtain the first PbX 2 layer; (2) Evaporate CsX' on the first PbX 2 layer to obtain a CsX' layer; Among them, the evaporation rate of the CsX' is V, and V = V 0 + a×h / 10, where V represents the evaporation rate of CsX', and V 0 represents the initial evaporation rate of CsX', a is the acceleration of the evaporation rate of CsX', and h is the thickness of the CsX' layer; (3) On the CsX' layer, at 260 - 270 °C, evaporate part of PbX” 2 , and then at 280 - 290 °C, evaporate the other part of PbX” 2 to obtain the second PbX” 2 layer.

12. A perovskite film layer, characterized in that, the perovskite film layer is obtained by annealing after depositing an organic salt solution on the surface of the lead halide composite film layer according to claim 1.

13. According to the perovskite film layer described in claim 12, characterized in that, in the organic salt solution, the cation of the solute includes formamidinium ions and / or methylamine ions.

14. According to the perovskite film layer described in claim 12, characterized in that, in the organic salt solution, the anion of the solute includes any one or a combination of at least two of chloride ions, bromide ions or iodide ions.

15. According to the perovskite film layer described in claim 12, characterized in that, the solvent in the organic salt solution includes isopropyl alcohol.

16. According to the perovskite film layer described in claim 12, characterized in that, the concentration of the organic salt solution is 0.3 - 0.7 mol / mL.

17. According to the perovskite film layer described in claim 12, characterized in that, the deposition method includes solution method or vacuum evaporation method.

18. According to the perovskite film layer described in claim 17, characterized in that, the solution method includes any one or a combination of at least two of spin coating method, coating method, spraying method or dipping method.

19. According to the perovskite film layer described in claim 12, characterized in that, the annealing temperature is 120 - 160 °C.

20. A perovskite solar cell, characterized in that, the perovskite solar cell includes the perovskite film layer according to any one of claims 12 - 19.

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