Laminated cell, preparation method thereof and photovoltaic module

Abstract

The invention relates to the field of photovoltaic technology, and provides a laminated cell and a preparation method thereof, and a photovoltaic module, the laminated cell comprises a bottom cell and a top cell which are laminated, the bottom cell comprises a crystalline silicon solar cell, and the top cell comprises a perovskite solar cell; the perovskite solar cell comprises a perovskite light absorption layer and a functional layer which are arranged in a stacked mode, the functional layer comprises a first functional layer and a second functional layer which are arranged in a stacked mode, the first functional layer is adjacent to the perovskite light absorption layer, and the second functional layer is arranged on the side, away from the perovskite light absorption layer, of the first functional layer; the first functional layer comprises a titanium oxide nanorod array, and the second functional layer comprises a zirconium oxide layer with a plurality of pores. The laminated cell provided by the invention has the advantages that the optical utilization rate is improved, so that the photoelectric conversion efficiency is improved.

Description

Technical Field

[0001] This application relates to the field of photovoltaic technology, and in particular to tandem cells and their preparation methods, and photovoltaic modules. Background Technology

[0002] Tandem solar cells, as an important development direction in the field of solar cells, have attracted widespread attention due to their ability to significantly improve photoelectric conversion efficiency. Tandem solar cells achieve more efficient utilization of sunlight by stacking multiple semiconductor materials with different bandgap widths, each absorbing and utilizing energy from different wavelengths of the solar spectrum. However, currently, tandem solar cells composed of perovskite solar cells and crystalline silicon solar cells still suffer from low optical utilization, resulting in poor photoelectric conversion efficiency. Summary of the Invention

[0003] Based on this, this application provides a tandem battery and its preparation method, as well as a photovoltaic module. The tandem battery has improved optical utilization, thereby having improved photoelectric conversion efficiency.

[0004] A first aspect of this application provides a tandem solar cell, comprising a bottom cell and a top cell stacked together, wherein the bottom cell comprises a crystalline silicon solar cell and the top cell comprises a perovskite solar cell;

[0005] The perovskite solar cell includes a perovskite light-absorbing layer and a functional layer stacked together. The functional layer includes a first functional layer and a second functional layer stacked together. The first functional layer is adjacent to the perovskite light-absorbing layer, and the second functional layer is disposed on the side of the first functional layer away from the perovskite light-absorbing layer.

[0006] The first functional layer includes a titanium oxide nanopillar array, which includes a plurality of spaced titanium oxide nanopillars. One end of each titanium oxide nanopillar is adjacent to the perovskite light-absorbing layer along the axial direction, and the other end along the axial direction is adjacent to the second functional layer.

[0007] The second functional layer includes a zirconia layer having multiple pores. The porosity of the bottom surface of the zirconia layer is less than that of the top surface. The bottom surface and the top surface are disposed opposite each other along the thickness direction of the zirconia layer, and the top surface is adjacent to the first functional layer.

[0008] In some embodiments of this application, one or more of the following conditions are met:

[0009] (1) The axial direction of each of the titanium dioxide nanopillars is parallel to the thickness direction of the functional layer;

[0010] (2) Any two of the titanium dioxide nanopillars have the same length.

[0011] In some embodiments of this application, one or more of the following conditions are met:

[0012] (1) The average diameter of the titanium dioxide nanopillars is 50 nm to 300 nm, and can be selected as 80 nm to 200 nm;

[0013] (2) The average length of the titanium dioxide nanopillars is 100nm~350nm, and can be selected as 130nm~300nm;

[0014] (3) The spacing between two adjacent titanium oxide nanopillars is 100nm~300nm, and can be selected as 150nm~200nm;

[0015] (4) The aspect ratio of the titanium oxide nanopillars is 1~2.

[0016] In some embodiments of this application, the porosity of the zirconia layer increases from the bottom surface to the top surface along the thickness direction;

[0017] Optionally, in the zirconia layer, based on the porosity of the bottom surface, from the bottom surface to the top surface, the porosity of the zirconia layer increases by 1% for every 2 nm increase in thickness.

[0018] In some embodiments of this application, one or more of the following conditions are met:

[0019] (1) In the zirconium oxide layer, the porosity of the bottom surface is 20%~30%, and the porosity of the top surface is 60%~80%;

[0020] Optionally, in the zirconium oxide layer, the porosity of the central interface is 45%~50%;

[0021] (2) In the zirconium oxide layer, the refractive index of the bottom surface is 1.9~2.0, and the refractive index of the top surface is 1.3~1.5;

[0022] Optionally, in the zirconium oxide layer, the refractive index of the central interface is 1.6 to 1.7;

[0023] (3) In the zirconium oxide layer, the average pore size of the pores is 100nm~300nm, and can be selected as 100nm~200nm;

[0024] (4) The thickness of the zirconium oxide layer is 80nm~130nm.

[0025] In some embodiments of this application, the perovskite solar cell further includes a first charge transport layer and a second charge transport layer, wherein the first charge transport layer is adjacent to the perovskite light-absorbing layer, and the second charge transport layer is located between the second functional layer and the crystalline silicon solar cell;

[0026] Optionally, the first charge transport layer is an electron transport layer, and the second charge transport layer is a hole transport layer.

[0027] In some embodiments of this application, the perovskite solar cell further includes a transparent electrode;

[0028] Optionally, the transparent electrode is disposed on the side of the first charge transport layer opposite to the perovskite light-absorbing layer.

[0029] A second aspect of this application provides a method for preparing a tandem solar cell, comprising:

[0030] Perovskite solar cells are fabricated on crystalline silicon solar cells to form tandem cells. The fabrication method of the perovskite solar cells includes:

[0031] Provide a functional layer;

[0032] After coating the surface of the functional layer with a perovskite precursor liquid, laser treatment is performed to form a perovskite light-absorbing layer.

[0033] The functional layer includes a first functional layer and a second functional layer stacked together. The first functional layer is adjacent to the perovskite light-absorbing layer, and the second functional layer is disposed on the side of the first functional layer away from the perovskite light-absorbing layer.

[0034] The first functional layer includes a titanium oxide nanopillar array, which includes a plurality of spaced titanium oxide nanopillars. One end of each titanium oxide nanopillar is adjacent to the perovskite light-absorbing layer along the axial direction, and the other end along the axial direction is adjacent to the second functional layer.

[0035] The second functional layer includes a zirconia layer having multiple pores. The porosity of the bottom surface of the zirconia layer is less than that of the top surface. The bottom surface and the top surface are disposed opposite each other along the thickness direction of the zirconia layer, and the top surface is adjacent to the first functional layer.

[0036] In some embodiments of this application, one or more of the following conditions are met:

[0037] (1) The energy density of the laser treatment is 25 mJ / cm². 2 ~35mJ / cm 2 ;

[0038] (2) The pulse width of the laser processing is 15ns~25ns;

[0039] (3) The wavelength of the laser processing is 500nm~600nm.

[0040] A third aspect of this application provides a photovoltaic module, including at least one of the tandem cells described in the first aspect of this application and the tandem cells prepared according to the preparation method described in the second aspect of this application.

[0041] The photovoltaic module of this application includes the tandem cell provided in this application, and therefore has at least the same advantages as the tandem cell.

[0042] The above-mentioned tandem solar cell provided in this application, through the synergistic interaction between the titanium dioxide nanopillar array in the first functional layer and the zirconium oxide layer with multiple pores in the second functional layer, is beneficial to enhance the absorption efficiency of incident light, especially long-wavelength photons, thereby improving the optical utilization and photoelectric conversion efficiency of the tandem solar cell. Attached Figure Description

[0043] Figure 1 This is a schematic diagram of the structure of a stacked battery according to one embodiment of this application.

[0044] Figure reference numerals: 1 Perovskite solar cell; 2 Crystalline silicon solar cell; 10 Second charge transport layer; 11 Second functional layer; 12 First functional layer; 13 Perovskite light-absorbing layer; 14 First charge transport layer; 15 Transparent electrode; 20 Back electrode; 110 Pore; 120 Titanium oxide nanopillar. Detailed Implementation

[0045] To facilitate understanding of this application, a more complete description will be provided below. However, this application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the disclosure of this application.

[0046] For simplicity, this application only explicitly discloses some numerical ranges. However, any lower limit can be combined with any upper limit to form a range not explicitly stated; and any lower limit can be combined with other lower limits to form a range not explicitly stated, just as any upper limit can be combined with any other upper limit to form a range not explicitly stated. Furthermore, although not explicitly stated, every point or individual value between the endpoints of the range is included within that range. Therefore, each point or individual value can be used as its own lower or upper limit and combined with any other point or individual value or with other lower or upper limits to form a range not explicitly stated.

[0047] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the specification of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. It should be noted that, unless otherwise stated, the term "and / or" as used herein includes any and all combinations of one or more of the associated listed items, "above," "below," includes the stated number, and "one or more" with "multiple" means two or more.

[0048] In this document, when referring to numerical intervals (i.e., numerical ranges), unless otherwise specified, the distribution of selectable values ​​within a numerical interval is considered continuous, and includes the two endpoints (i.e., the minimum and maximum values) of the numerical interval, as well as every value between these two endpoints. Unless otherwise specified, when a numerical interval refers only to integers within that interval, it includes the two endpoint integers of the numerical range, as well as every integer between the two endpoints, which is equivalent to directly listing every integer. When multiple numerical ranges are provided to describe features or characteristics, these numerical ranges can be merged. In other words, unless otherwise specified, the numerical ranges disclosed herein should be understood to include any and all subranges included therein. The "numerical value" in this numerical interval can be any quantitative value, such as a number, percentage, ratio, etc. The term "numerical interval" can be broadly included to include percentage intervals, ratio intervals, proportion intervals, and other numerical interval types.

[0049] In this document, for methods involving multiple steps, unless otherwise explicitly stated herein, there is no strict order constraint on the execution of these steps; they may be executed in any order other than those described. Moreover, any step may include multiple sub-steps or multiple stages, which are not necessarily completed at the same time, but may be executed at different times, and their execution order is not necessarily sequential, but may be executed in turn, alternately, or simultaneously with other steps or parts of the sub-steps or stages of other steps.

[0050] The foregoing description of this application is not intended to describe every disclosed implementation or method. Instead, the following description provides more specific examples of exemplary embodiments. Throughout the application, guidance is provided through a series of embodiments that can be used in various combinations. The examples listed are representative only and should not be construed as exhaustive.

[0051] Currently, in tandem solar cells consisting of a perovskite solar cell at the top and a crystalline silicon solar cell at the bottom, when incident light propagates between the charge transport layer and the perovskite light-absorbing layer, the large difference in refractive index between the two layers, along with a sudden change in interface refractive index, results in significant interfacial reflection loss of the incident light within the multilayer film composed of the perovskite light-absorbing layer and the charge transport layer. This makes it difficult for incident photons, especially long-wavelength photons, to reach the bottom crystalline silicon solar cell after reflection loss through the multilayer film, leading to low optical utilization and poor photoelectric conversion efficiency in the tandem solar cell. To address this technical problem, this application proposes the following technical solution.

[0052] Firstly, this application provides a stacked battery, see [link to previous application]. Figure 1 It includes a bottom cell and a top cell stacked together, wherein the bottom cell includes a crystalline silicon solar cell 2 and the top cell includes a perovskite solar cell 1;

[0053] The perovskite solar cell 1 includes a perovskite light-absorbing layer 13 and a functional layer stacked together. The functional layer includes a first functional layer 12 and a second functional layer 11 stacked together. The first functional layer 12 is adjacent to the perovskite light-absorbing layer 13, and the second functional layer 11 is disposed on the side of the first functional layer 12 away from the perovskite light-absorbing layer 13.

[0054] The first functional layer 12 includes a titanium oxide nanopillar array, which includes a plurality of spaced titanium oxide nanopillars 120. One end of each titanium oxide nanopillar 120 along the axial direction is adjacent to the perovskite light-absorbing layer 13, and the other end along the axial direction is adjacent to the second functional layer 11.

[0055] The second functional layer 11 includes a zirconia layer having a plurality of pores 110. The porosity of the bottom surface of the zirconia layer is less than that of the top surface. The bottom surface and the top surface are disposed opposite to each other along the thickness direction of the zirconia layer, and the top surface is adjacent to the first functional layer.

[0056] The tandem solar cell provided in this application has a functional layer disposed between the perovskite light-absorbing layer and the crystalline silicon solar cell. The functional layer includes a first functional layer and a second functional layer stacked together. In the first functional layer, the titanium dioxide nanopillar array can excite surface plasmon resonance, reducing reflection of incident light and improving the absorption efficiency of incident light, especially long-wavelength photons, and guiding photons to the second functional layer. Based on this, the zirconium oxide layer in the second functional layer absorbs the incident light guided by the first functional layer. Through the change in porosity from the bottom to the top surface and the resulting change in refractive index, it further enhances the absorption efficiency of incident light, especially long-wavelength photons, and facilitates the scattering of photons to the bottom crystalline silicon solar cell. Thus, the titanium dioxide nanopillar array in the first functional layer and the zirconium oxide layer in the second functional layer work synergistically to enhance the absorption efficiency of incident light, especially long-wavelength photons, thereby improving the optical utilization and photoelectric conversion efficiency of the tandem solar cell.

[0057] Furthermore, the titanium dioxide nanopillar array in the first functional layer and the perovskite light-absorbing layer have similar energy bands, which is beneficial for promoting carrier extraction and thus further improving photoelectric conversion efficiency. Simultaneously, the titanium dioxide nanopillar array in the first functional layer and the zirconium oxide layer in the second functional layer have well-matched coefficients of thermal expansion, which helps reduce or even avoid high-temperature cracking and provides good structural stability. This facilitates synergistic cooperation between the first and second functional layers.

[0058] Furthermore, the zirconia layer in the second functional layer possesses high mechanical strength, which is beneficial for supporting the titanium dioxide nanopillar array and giving the entire functional layer high structural stability. Simultaneously, the zirconia layer has a low extinction coefficient in the near-infrared region, which facilitates the transmission of long-wavelength photons to the bottom crystalline silicon solar cell, improving optical utilization.

[0059] It should be noted that the "long-wavelength photons" mentioned in this application refer to photons with wavelengths of 900nm to 1200nm.

[0060] In some embodiments, the axial direction of each titanium oxide nanopillar is parallel to the thickness direction of the functional layer. This arrangement helps to further enhance the synergy between the titanium oxide nanopillar array and the zirconium oxide layer, thereby further enhancing the absorption efficiency of incident light, especially long-wavelength photons, scattering more photons to the bottom crystalline silicon solar cell, and further improving the optical utilization and photoelectric conversion efficiency of the tandem cell.

[0061] In some embodiments, any two of the titanium dioxide nanopillars are of equal length. This arrangement helps to further enhance the synergy between the titanium dioxide nanopillar array and the zirconium oxide layer, thereby further enhancing the absorption efficiency of incident light, especially long-wavelength photons, scattering more photons to the bottom crystalline silicon solar cell, and further improving the optical utilization and photoelectric conversion efficiency of the tandem cell.

[0062] In some embodiments, the average diameter of the titanium dioxide nanopillars is 50 nm to 300 nm, and can be selected as 80 nm to 200 nm. For example, the average diameter of the titanium dioxide nanopillars can be 50 nm, 81 nm, 112 nm, 153 nm, 184 nm, 225 nm, 256 nm, 287 nm, 300 nm, or within any range of the above values. This configuration helps to extend the scattering optical path of the titanium dioxide nanopillar array to incident light, thereby improving its light absorption rate.

[0063] In some embodiments, the average length of the titanium dioxide nanopillars is 100 nm to 350 nm, and can be selected as 130 nm to 300 nm. For example, the average length of the titanium dioxide nanopillars can be 100 nm, 121 nm, 152 nm, 183 nm, 214 nm, 265 nm, 296 nm, 327 nm, 350 nm, or within any range of the above values. This configuration not only helps to extend the scattering optical path of the titanium dioxide nanopillar array to the incident light, thereby improving its light absorption rate, but also helps to give the titanium dioxide nanopillar array higher impact resistance, making its structure less prone to collapse.

[0064] In some embodiments, the spacing between two adjacent titanium oxide nanopillars is 100 nm to 300 nm, optionally 150 nm to 200 nm. For example, the spacing between two adjacent titanium oxide nanopillars can be 100 nm, 121 nm, 152 nm, 183 nm, 214 nm, 265 nm, 296 nm, 300 nm, or any value within the range above. This arrangement, on the one hand, helps to disrupt the symmetry of photonic crystals, broaden the light absorption range of the titanium oxide nanopillar array, improve the light absorption effect, and increase the light absorption rate; on the other hand, it also helps to provide suitable permeation channels for the perovskite material, enabling the formation of a three-dimensional interpenetrating interface between the titanium oxide nanopillar array and the perovskite light-absorbing layer, reducing carrier recombination losses, and improving photoelectric conversion efficiency.

[0065] In some embodiments, the aspect ratio of the titanium oxide nanopillars is 1 to 2. For example, the aspect ratio of the titanium oxide nanopillars can be 1, 1.2, 1.4, 1.6, 1.8, 2, or any value within the range above. This configuration is beneficial in two ways: firstly, it enhances the light absorption of the titanium oxide nanopillar array, giving it a higher light-trapping factor and improving the light absorption rate; secondly, it also facilitates carrier transport.

[0066] In some embodiments, the porosity of the zirconia layer increases from the bottom surface to the top surface along the thickness direction. This gradient porosity from bottom to top in the zirconia layer allows for a gradient change in refractive index, which helps to reduce or even eliminate abrupt changes in interfacial refractive index, thereby reducing light reflection and increasing light absorption.

[0067] It is understandable that by adjusting the porosity of the cross-section corresponding to different thicknesses in the zirconium oxide layer, the refractive index can be changed accordingly.

[0068] In some embodiments, in the zirconia layer, based on the porosity of the bottom surface, the porosity increases by 1% for every 2 nm increase in the thickness of the zirconia layer from the bottom surface to the top surface. This arrangement facilitates a continuous gradual change in refractive index within the zirconia layer, thereby further reducing or even eliminating abrupt changes in interfacial refractive index, and consequently further reducing light reflection and increasing light absorption.

[0069] In some embodiments, the porosity of the bottom surface of the zirconia layer is 20% to 30%, and the porosity of the top surface is 60% to 80%; optionally, the porosity of the central interface is 45% to 50%. This configuration helps to reduce or even eliminate abrupt changes in interface refractive index, thereby reducing interface reflection of light and increasing light absorption.

[0070] For example, the porosity of the bottom surface can be 20%, 23%, 27%, 30%, or any of the above values; the refractive index of the top surface can be 60%, 64%, 75%, 80%, or any of the above values; and the refractive index of the central interface can be 45%, 48%, 50%, or any of the above values.

[0071] It is understood that the “central interface” mentioned in this application refers to the central plane of the zirconium oxide layer along the thickness direction, that is, the cross section obtained at 1 / 2 along the thickness direction.

[0072] In some embodiments, the refractive index of the bottom surface of the zirconia layer is 1.9 to 2.0, and the refractive index of the top surface is 1.3 to 1.5; optionally, the refractive index of the central interface is 1.6 to 1.7. This configuration facilitates better matching with the refractive index of the perovskite light-absorbing layer, reduces or even eliminates abrupt changes in interface refractive index, reduces interface reflection of light, and improves light absorption.

[0073] In some embodiments, the average pore size of the pores in the zirconium oxide layer is 100 nm to 300 nm, and can be selected as 100 nm to 200 nm. For example, the average pore size can be 100 nm, 142 nm, 174 nm, 206 nm, 248 nm, 280 nm, 300 nm, or within any range of the above values. This setting is beneficial for constraining the nucleation of the perovskite light-absorbing layer grown thereon, inducing the perovskite to preferentially grow towards the (100) crystal plane, reducing grain boundary defects, and improving photoelectric conversion efficiency.

[0074] In some embodiments, the thickness of the zirconium oxide layer is 80 nm to 130 nm. For example, the thickness of the zirconium oxide layer can be 80 nm, 91 nm, 101 nm, 113 nm, 124 nm, 130 nm, or within any range of these values. This configuration is beneficial for providing better support for the titanium oxide nanopillar array placed on it, and facilitates the synergistic effect between the two.

[0075] In some implementations, see Figure 1 The perovskite solar cell 1 further includes a first charge transport layer 14 and a second charge transport layer 10. The first charge transport layer 14 is adjacent to the perovskite light-absorbing layer 13, and the second charge transport layer 10 is located between the second functional layer 11 and the crystalline silicon solar cell 2. Optionally, the first charge transport layer 14 is an electron transport layer, and the second charge transport layer 10 is a hole transport layer.

[0076] In some implementations, see Figure 1 The perovskite solar cell 1 further includes a transparent electrode 15; optionally, the transparent electrode 15 is disposed on the side of the first charge transport layer 14 away from the perovskite light-absorbing layer 13.

[0077] In some implementations, see Figure 1 The tandem cell further includes a back electrode 20; optionally, the back electrode 20 is disposed on the side of the crystalline silicon solar cell 2 away from the perovskite solar cell 1.

[0078] Secondly, this application provides a method for preparing a tandem battery, which can be used to prepare the tandem battery of the first aspect of this application, and may include the following steps:

[0079] Perovskite solar cells are fabricated on crystalline silicon solar cells to form tandem cells. The fabrication method of the perovskite solar cells includes:

[0080] Provide a functional layer;

[0081] After coating the surface of the functional layer with a perovskite precursor liquid, laser treatment is performed to form a perovskite light-absorbing layer.

[0082] The functional layer includes a first functional layer and a second functional layer stacked together. The first functional layer is adjacent to the perovskite light-absorbing layer, and the second functional layer is disposed on the side of the first functional layer away from the perovskite light-absorbing layer.

[0083] The first functional layer includes a titanium oxide nanopillar array, which includes a plurality of spaced titanium oxide nanopillars. One end of each titanium oxide nanopillar is adjacent to the perovskite light-absorbing layer along the axial direction, and the other end along the axial direction is adjacent to the second functional layer.

[0084] The second functional layer includes a zirconia layer having multiple pores. The porosity of the bottom surface of the zirconia layer is less than that of the top surface. The bottom surface and the top surface are disposed opposite each other along the thickness direction of the zirconia layer, and the top surface is adjacent to the first functional layer.

[0085] The preparation method provided in this application involves coating the surface of the functional layer with a perovskite precursor solution and then performing laser treatment. Compared with the traditional annealing process, laser treatment is beneficial to improving the crystallinity of perovskite, achieving in-situ crystallization of perovskite, reducing thermal damage, improving the crystal quality of perovskite, and thus increasing the current density.

[0086] In some embodiments, the energy density of the laser treatment is 25 mJ / cm². 2 ~35mJ / cm 2 For example, the energy density of laser treatment can be 25 mJ / cm². 2 27mJ / cm 2 29mJ / cm 2 31mJ / cm 2 33mJ / cm 2 35mJ / cm 2 Or it may fall within any of the above value ranges. This setting is beneficial for both the full crystallization of the perovskite and the reduction of thermal damage to the perovskite, thereby contributing to a higher photoelectric conversion efficiency.

[0087] In some embodiments, the pulse width of the laser treatment is 15ns to 25ns. For example, the pulse width of the laser treatment can be 15ns, 17ns, 19ns, 21ns, 23ns, 25ns, or any value within the range above. This setting can reduce or avoid heat diffusion to the bottom and damage to the crystalline silicon cell, and also facilitate obtaining sufficient temperature rise so that the perovskite can crystallize and form a film.

[0088] In some embodiments, the wavelength of the laser treatment is 500 nm to 600 nm. For example, the wavelength of the laser treatment can be 500 nm, 530 nm, 560 nm, 590 nm, 600 nm, or any range of these values. This setting is beneficial for both increasing the crystallinity of the perovskite and reducing thermal damage to the perovskite.

[0089] In some embodiments, the titanium oxide nanopillar array can be prepared using a nanoimprint stencil method.

[0090] In some embodiments, the zirconium oxide layer may be prepared using a sol-gel method.

[0091] Thirdly, this application provides a photovoltaic module, including at least one of the tandem cells described in the first aspect of this application and the tandem cells prepared according to the preparation method described in the second aspect of this application.

[0092] The following are specific embodiments, which describe the disclosure of this application in more detail. These embodiments are merely illustrative, as various modifications and variations within the scope of the disclosure of this application will be apparent to those skilled in the art. Unless otherwise stated, all parts, percentages, and ratios reported in the following embodiments are based on weight, and all reagents used in the embodiments are commercially available or synthesized by conventional methods and can be used directly without further processing, and the instruments used in the embodiments are commercially available.

[0093] Example 1

[0094] (1.1) Fabrication of crystalline silicon bottom solar cells

[0095] 1. Cleaning and sizing:

[0096] NaOH solution was used to texturize both sides (i.e., the two opposite sides of the Cz-Si wafer) of the n-type Cz-Si wafer (the texturized height of both sides was 1.2 μm).

[0097] 2. Double-sided passivation:

[0098] Bilateral SiO2 was thermally oxidized on both sides of a Cz-Si wafer at 800℃ (1.5 nm thick on each side); then intrinsic α-Si was deposited on both sides using LPCVD (60 nm thick on the front side and 60 nm thick on the back side); subsequently, phosphorus diffusion was performed on the front side using POCl3 at 880℃ to form n-Si on the front side. + -polySi; Backside boron diffusion was performed using BCl3 at 950℃ to form p on the backside. + -polySi; finally, annealing and crystallization were carried out at 750℃ under H2 atmosphere.

[0099] (1.2) Fabrication of perovskite rooftop solar cells

[0100] ① On the crystalline silicon substrate prepared in step (1.1), the crystalline silicon substrate was subjected to oxygen plasma treatment for 15 minutes. At room temperature, a 10 nm NiOx layer was deposited on the pre-cleaned substrate by radio frequency sputtering. The sputtering chamber pressure was 0.40 Pa, the radio frequency power was 90 W, the argon flow rate was 20 sccm, and the deposition time was 15 minutes. After deposition, the substrate was annealed in air for 40 minutes at a temperature of 350 °C. Subsequently, the NiOx substrate was directly transferred to a nitrogen glove box for subsequent processes.

[0101] ② Preparation of the second functional layer: Prepare ZrO2 sol: ZrCl4: ethanol: acetylacetone = 1:20:0.3:0.5 (molar ratio), add PS microspheres (average median particle size of 120 nm), and then perform a gradient spin coating process:

[0102] First layer (i.e., bottom surface): Spin coating at 3000 rpm for 30 seconds, thickness of 30 nm, porosity of 30%, and refractive index of 1.9;

[0103] Second layer: Spin coating at 1500 rpm for 30 seconds, thickness of 40 nm, porosity of 45%, refractive index of 1.7;

[0104] The third layer (i.e., the top surface): spin coating at 800 rpm for 30 seconds, with a thickness of 55 nm, a porosity of 60%, and a refractive index of 1.5.

[0105] After spin coating, the material was annealed at 150°C for 1 hour to remove the PS microspheres and form a ZrO2 layer with multiple pores. The thickness of the ZrO2 layer was 125 nm and the average pore size was 100 nm.

[0106] ③ Preparation of the first functional layer:

[0107] Step 1: Nanoimprint lithography to form a resin template

[0108] The glass substrate surface is cleaned and pretreated; UV-curable resin is spin-coated onto the surface to a thickness of 200 nm. This step is performed under a yellow fluorescent lamp to prevent pre-crosslinking.

[0109] Imprinting: Imprinting was then performed using a transparent quartz template with a hexagonal close-packed nanopillar array of punches with a period of 200 nm (imprinting parameters: pressure: 5 bar, imprinting time: 30 seconds).

[0110] UV curing: Under compressed conditions, irradiate with ultraviolet light (wavelength 365nm, intensity 100mW / cm²) for 300 seconds to fully cure the resin.

[0111] Demolding: Slowly separate the quartz template, leaving a cured resin layer with a nanopore array on the substrate surface. (Note: At this point, a "negative" pattern of the resin is obtained, i.e., the template is a raised pillar, and what is left is a concave hole).

[0112] Step 2: Reactive ion etching (RIE) transfer pattern to TiO2 layer

[0113] Depositing TiO2 thin film: A dense, amorphous TiO2 thin film is deposited on the cured resin layer after imprinting using atomic layer deposition (ALD); the thickness is equal to the length of the target nanopillar.

[0114] Reactive ion etching (RIE): This step involves anisotropic etching, with the etching rate in the vertical direction being much higher than in the horizontal direction. This transfers the pattern from the resin layer to the underlying TiO2 layer, forming nanopillars. The etching gas is a mixture of carbon tetrafluoride (CF4) and oxygen (O2); the chamber pressure is 10 mTorr; the RF power is 100 W; and the etching time is 90 seconds. During the etching process, an endpoint detector is used to monitor the process and ensure that excess TiO2 is completely etched away.

[0115] Residual resin removal: After etching, a small amount of resin etching products remain on the surface. Oxygen plasma ashing is used to treat the surface at 200W power for 60 seconds to completely remove all organic residues and obtain a pure TiO2 nanopillar array. The TiO2 nanopillar array is then transferred to the ZrO2 layer.

[0116] In this TiO2 nanopillar array, the axial direction of each titanium oxide nanopillar is parallel to the thickness direction of the first functional layer, and the diameter and length of any two titanium oxide nanopillars are equal. The diameter of the titanium oxide nanopillar is 250 nm, the length of the titanium oxide nanopillar is 250 nm, the aspect ratio of the titanium oxide nanopillar is 1, and the spacing between two adjacent titanium oxide nanopillars is 200 nm.

[0117] ④ Preparation of the perovskite absorbing layer: 0.075 mmol CsI, 1.098 mmol FAI, 0.327 mmol MABr, 0.354 mmol PbBr2, and 1.146 mmol PbI2 were dissolved in 1 mL of a mixed solvent of DMF:DMSO (volume ratio 4:1) to prepare a 1.5 mol / L perovskite precursor solution. Then, the solution was spin-coated at 4000 rpm for 30 s, followed by laser annealing to form a perovskite absorbing layer. The chemical formula of the perovskite material is CsI. 0.05 FA 0.79 MA 0.16 PbI 2.55 Br 0.45 The laser annealing process used a wavelength of 532 nm and an energy density of 30 mJ / cm³. 2 The pulse width is 20ns.

[0118] ⑤ Preparation of electron transport layer: A C60 thin film with a thickness of 15 nm was deposited on the surface of the perovskite light-absorbing layer using an evaporation machine.

[0119] ⑥ Fabrication of transparent electrode: 40nm IZO was sputtered using PVD.

[0120] ⑦ Preparation of antireflection layer: 100 nm of MgF2 was deposited using an evaporation machine.

[0121] ⑧ Preparation of back electrode Ag: Ag with a thickness of 1 μm was deposited using an evaporation deposition machine.

[0122] Example 2

[0123] Similar to the preparation method in Example 1, the main difference is that in step ③, nanoimprint templates of different sizes are used so that the diameter of the titanium oxide nanopillars in the prepared TiO2 nanopillar array is 150 nm, the length of the titanium oxide nanopillars is 300 nm, and the aspect ratio of the titanium oxide nanopillars is 1.5.

[0124] Example 3

[0125] Similar to the preparation method in Example 1, the main difference is that in step ③, nanoimprint templates of different sizes are used so that in the prepared TiO2 nanopillar array, the diameter of the titanium oxide nanopillars is 100 nm, the length of the titanium oxide nanopillars is 200 nm, and the aspect ratio of the titanium oxide nanopillars is 2.

[0126] Example 4

[0127] Similar to the preparation method in Example 1, the main difference is that in step ②, PS microspheres with an average median particle size of 210 nm are used, so that the average pore size of the ZrO2 layer is 200 nm.

[0128] Example 5

[0129] Similar to the preparation method in Example 1, the main difference is that in step ②, PS microspheres with an average median particle size of 315 nm are used, so that the average pore size of the ZrO2 layer is 300 nm.

[0130] Comparative Example 1

[0131] Similar to the preparation method of Example 1, the main difference is that in step ②, the preparation of the second and third layers is omitted, and the spin coating time of the first layer is adjusted to 90s (so that the thickness of the first layer is equal to the thickness of the ZrO2 layer in Example 1), so that the prepared ZrO2 layer consists only of the first layer; the porosity of the ZrO2 layer is 30%, the refractive index is 1.9, and the average pore size is equal to that of Example 1.

[0132] Comparative Example 2

[0133] Similar to the preparation method in Example 1, the main difference is that in step ②, the preparation order of the first layer and the third layer is reversed, so that the third layer is the bottom surface and the first layer is the top surface, that is, the porosity of the bottom surface is greater than that of the top surface.

[0134] Comparative Example 3

[0135] Similar to the preparation method in Example 1, the main difference is that step ② is omitted, that is, the second functional layer (i.e., ZrO2 layer) is not set.

[0136] Comparative Example 4

[0137] Similar to the preparation method in Example 1, the main difference is that steps ② and ③ are omitted, that is, the second functional layer (i.e., ZrO2 layer) and the first functional layer (i.e. TiO2 nanopillar array) are not set.

[0138] The stacked cells prepared in Examples 1-5 and Comparative Examples 1-4 were subjected to relevant performance tests, and the test results are shown in Table 1 below.

[0139] The test conditions or standards for each performance test item are as follows:

[0140] (1) Photovoltaic conversion efficiency test of tandem solar cells

[0141] Under normal temperature and pressure, and under standard simulated sunlight (AM 1.5G, 1000 milliwatts per square centimeter (mW / cm²)... 2Under illumination, the battery performance was tested to obtain the IV curve (volt-ampere characteristic curve). Based on the IV curve and the data fed back by the testing equipment (four-channel digital source meter, Keithley 2440), the short-circuit current density Jsc (mA / cm2), open-circuit voltage Voc (volts (V)), maximum light output current Jmpp (mA (mA)), maximum light output voltage Vmpp (V) and series resistance (Ω) can be obtained.

[0142] The fill factor FF of the battery can be calculated using the formula FF = Jsc × Voc / (Jmpp × Vmpp), in percentage (%). The photoelectric conversion efficiency PCE of the battery can be calculated using the formula PCE = Jsc × Voc × FF / Area, in percentage (%). Area represents the effective area of ​​the battery under illumination, in cm². 2 ).

[0143] "Normal temperature and pressure" refers to normal pressure: the pressure is one atmosphere at a temperature of 25℃; normal temperature refers to 20℃ to 30℃, and further, it can be 25℃.

[0144] Table 1

[0145]

[0146] Table 1 shows that, by comparing Examples 1-5 with Comparative Example 1, the zirconia layer with a gradient porosity in this application is beneficial for improving the photoelectric conversion efficiency of the tandem solar cell compared to a zirconia layer with a single porosity. A comparison of Examples 1-5 with Comparative Example 2 shows that, in the zirconia layer of this application, setting the bottom porosity to be smaller than the top porosity is beneficial for improving the photoelectric conversion efficiency of the tandem solar cell. A comparison of Examples 1-5 with Comparative Examples 3-4 shows that the synergistic cooperation between the first functional layer and the second functional layer is beneficial for improving the photoelectric conversion efficiency of the tandem solar cell.

[0147] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0148] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A stacked battery, characterized in that, It includes a bottom cell and a top cell stacked together, wherein the bottom cell includes a crystalline silicon solar cell and the top cell includes a perovskite solar cell; The perovskite solar cell includes a perovskite light-absorbing layer and a functional layer stacked together. The functional layer includes a first functional layer and a second functional layer stacked together. The first functional layer is adjacent to the perovskite light-absorbing layer, and the second functional layer is disposed on the side of the first functional layer away from the perovskite light-absorbing layer. The first functional layer includes a titanium oxide nanopillar array, which includes a plurality of spaced titanium oxide nanopillars. One end of each titanium oxide nanopillar is adjacent to the perovskite light-absorbing layer along the axial direction, and the other end along the axial direction is adjacent to the second functional layer. The second functional layer includes a zirconia layer having multiple pores. The porosity of the bottom surface of the zirconia layer is less than that of the top surface. The bottom surface and the top surface are disposed opposite each other along the thickness direction of the zirconia layer, and the top surface is adjacent to the first functional layer.

2. The stacked battery according to claim 1, characterized in that, One or more of the following conditions must be met: (1) The axial direction of each of the titanium dioxide nanopillars is parallel to the thickness direction of the functional layer; (2) Any two of the titanium dioxide nanopillars have the same length.

3. The stacked battery according to claim 1 or 2, characterized in that, One or more of the following conditions must be met: (1) The average diameter of the titanium dioxide nanopillars is 50 nm to 300 nm; (2) The average length of the titanium dioxide nanopillars is 100 nm to 350 nm; (3) The spacing between two adjacent titanium oxide nanopillars is 100 nm to 300 nm; (4) The aspect ratio of the titanium oxide nanopillars is 1~2.

4. The stacked battery according to claim 1 or 2, characterized in that, The porosity of the zirconia layer increases from the bottom surface to the top surface along the thickness direction.

5. The stacked battery according to claim 4, characterized in that, In the zirconia layer, based on the porosity of the bottom surface, from the bottom surface to the top surface, the porosity increases by 1% for every 2nm increase in the thickness of the zirconia layer.

6. The stacked battery according to claim 1 or 2, characterized in that, One or more of the following conditions must be met: (1) In the zirconium oxide layer, the porosity of the bottom surface is 20%~30%, and the porosity of the top surface is 60%~80%; (2) In the zirconium oxide layer, the refractive index of the bottom surface is 1.9~2.0, and the refractive index of the top surface is 1.3~1.5; (3) In the zirconium oxide layer, the average pore size of the pores is 100 nm to 300 nm; (4) The thickness of the zirconium oxide layer is 80nm~130nm.

7. The stacked battery according to claim 6, characterized in that, One or more of the following conditions must be met: (1) In the zirconium oxide layer, the porosity of the central interface is 45%~50%; (2) In the zirconium oxide layer, the refractive index of the central interface is 1.6~1.7; (3) In the zirconium oxide layer, the average pore size of the pores is 100nm~200nm.

8. The stacked battery according to claim 1 or 2, characterized in that, The perovskite solar cell further includes a first charge transport layer and a second charge transport layer, wherein the first charge transport layer is adjacent to the perovskite light-absorbing layer, and the second charge transport layer is located between the second functional layer and the crystalline silicon solar cell; The first charge transport layer is an electron transport layer, and the second charge transport layer is a hole transport layer.

9. The stacked battery according to claim 8, characterized in that, The perovskite solar cell also includes a transparent electrode; The transparent electrode is located on the side of the first charge transport layer away from the perovskite light-absorbing layer.

10. A method for preparing a stacked battery, characterized in that, include: Perovskite solar cells are fabricated on crystalline silicon solar cells to form tandem cells. The fabrication method of the perovskite solar cells includes: Provide a functional layer; After coating the surface of the functional layer with a perovskite precursor liquid, laser treatment is performed to form a perovskite light-absorbing layer. The functional layer includes a first functional layer and a second functional layer stacked together. The first functional layer is adjacent to the perovskite light-absorbing layer, and the second functional layer is disposed on the side of the first functional layer away from the perovskite light-absorbing layer. The first functional layer includes a titanium oxide nanopillar array, which includes a plurality of spaced titanium oxide nanopillars. One end of each titanium oxide nanopillar is adjacent to the perovskite light-absorbing layer along the axial direction, and the other end along the axial direction is adjacent to the second functional layer. The second functional layer includes a zirconia layer having multiple pores. The porosity of the bottom surface of the zirconia layer is less than that of the top surface. The bottom surface and the top surface are disposed opposite each other along the thickness direction of the zirconia layer, and the top surface is adjacent to the first functional layer.

11. The method for preparing a stacked battery according to claim 10, characterized in that, One or more of the following conditions must be met: (1) The energy density of the laser treatment is 25 mJ / cm². 2 ~35mJ / cm 2 ; (2) The pulse width of the laser processing is 15ns~25ns; (3) The wavelength of the laser processing is 500nm~600nm.

12. A photovoltaic module, characterized in that, It includes at least one of the stacked battery according to any one of claims 1 to 9 and the stacked battery prepared by the method according to any one of claims 10 to 11.

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