Perovskite-based laminated solar cell and preparation method therefor, and electric device

Abstract

The present application provides a perovskite-based laminated solar cell, comprising a first perovskite layer and a second perovskite layer which have different band gaps. The side surface of the first perovskite layer close to the second perovskite layer is a non-smooth surface in which recessed channels are formed, and ribs are formed between at least some of adjacent recessed channels. The laminated solar cell satisfies at least one of the following features: at least some of recessed channels have different widths in at least some of depth positions; and at least some of ribs have different widths in at least some of height positions.

Description

Perovskite-based tandem solar cell, preparation method and electrical device

[0001] Related applications

[0002] This application claims priority to Chinese patent application number CN2023114351873, filed on October 31, 2023, entitled “Perovskite-based tandem solar cells, preparation methods and electrical devices,” the entire text of which is hereby incorporated by reference. Technical Field

[0003] The present application relates to the technical field of solar cells, and in particular to a tandem solar cell, a preparation method and an electrical device, and further to a tandem solar cell based on perovskite, a preparation method and an electrical device. Background Art

[0004] The statements herein merely provide background information related to the present application and do not necessarily constitute prior art.

[0005] Perovskite solar cells are devices that convert solar energy into electrical energy using the photoelectric conversion mechanism of perovskite-type crystal materials. They are currently the third generation of solar cells and have many advantages, such as high photoelectric conversion efficiency, simple manufacturing process, and low production cost. They have been extensively studied in recent years. However, the improvement of the photoelectric conversion efficiency of traditional single-junction perovskite solar cells is limited by theoretical limits. By stacking semiconductors with different band gaps, tandem solar cells can expand the absorption spectrum of solar cells and convert light energy into electrical energy to a greater extent. This is an important way to overcome the efficiency of single-junction cells, the Shockley-Queisser limit, and an important strategy for improving the photoelectric conversion efficiency of solar cells in the future. For perovskite-based tandem solar cells, how to further improve the short-circuit current level of the device is one of the important research directions for improving device performance.

[0006] Summary of the Invention

[0007] According to various embodiments and examples of the present application, a perovskite-based tandem solar cell, a preparation method, and an electrical device are provided. The perovskite-based tandem solar cell includes a perovskite light-absorbing layer, which can provide a high short-circuit current density and improve photoelectric conversion efficiency.

[0008] In a first aspect of the present application, a perovskite-based tandem solar cell is provided, comprising a first perovskite layer and a second perovskite layer having different band gaps; a surface of the first perovskite layer adjacent to the second perovskite layer is a non-smooth surface having concave grooves, and ridges are formed between at least a portion of adjacent concave grooves; the tandem solar cell satisfies at least one of the following characteristics: at least a portion of the concave grooves has different widths at at least a portion of the depth positions; and at least a portion of the ridges has different widths at at least a portion of the height positions.

[0009] In some embodiments, a perovskite-based tandem solar cell is provided, the tandem solar cell comprising a first perovskite sub-cell, a carrier recombination layer, and a second perovskite sub-cell stacked in sequence, wherein the first perovskite sub-cell comprises a first perovskite layer, and the second perovskite sub-cell comprises a second perovskite layer; the band gap of the first perovskite layer is different from the band gap of the second perovskite layer;

[0010] Wherein, the thickness direction of the first perovskite layer is recorded as the longitudinal direction;

[0011] The surface of the first perovskite layer on one side close to the carrier recombination layer is a non-smooth surface, the non-smooth surface is provided with concave grooves, and convex ridges are formed between at least a portion of adjacent concave grooves;

[0012] The stacked solar cell satisfies at least one of the following characteristics:

[0013] At least a portion of the concave grooves have different widths at at least a portion of their depths;

[0014] At least a portion of the ridges have different widths at at least a portion of their heights.

[0015] By providing perovskite light-absorbing layers with different band gaps in a tandem solar cell, photons of different wavelengths can be fully absorbed, thermal relaxation losses can be reduced, and the utilization rate of incident light can be improved. A non-smooth surface comprising concave grooves and convex ridges can be provided on the surface of the first perovskite layer near the carrier recombination layer, so that this non-smooth surface forms a long concave-convex interface with the adjacent surface of the adjacent structural layer, which can be recorded as the first interface. When at least one of the following two characteristics is met: "at least a portion of the concave grooves has a different width at at least a portion of its depth" and "at least a portion of the ridges has a different width at at least a portion of its height" is met, at least a portion of the photons incident on the first interface can undergo at least one of multiple refractions and multiple reflections at the first interface. For photons directed toward the first interface, compared to the situation in which a traditional smooth interface is only reflected and / or refracted once after contacting the interface, the non-smooth first interface in the present application can increase the chance of photons contacting the first interface, thereby increasing the probability of photons being captured by the perovskite layer in the perovskite-based tandem solar cell, and increasing the efficiency of light utilization; for photons that are not absorbed by the first perovskite layer and are directed toward the first interface, the probability of the photons entering the second perovskite layer can be increased, thereby increasing the number of photons in the wavelength band that can be absorbed by the second perovskite layer; for photons that are still not absorbed by the second perovskite layer and are directed toward the first interface, the probability of entering the first perovskite layer can be increased, thereby increasing the number of photons in the wavelength band that can be absorbed by the first perovskite layer. Therefore, the overall current level of the tandem solar cell can be improved, the short-circuit current density can be improved, and in addition, it is also beneficial to improve the photoelectric conversion efficiency.

[0016] Based on any suitable embodiment in the present application, in some further embodiments, the morphologies of the interfaces formed by different structural layers between the first perovskite layer and the second perovskite layer are substantially matched.

[0017] When the morphologies of the interfaces formed by different structural layers between the first perovskite layer and the second perovskite layer are basically matched, the different structural layers have uniform thicknesses. At this time, the surface of the second perovskite layer close to the first perovskite layer can form a non-smooth surface with similar morphology; corresponding to the "convex-concave" interface on the surface of the first perovskite layer, a corresponding "convex-concave" interface (which can be recorded as a second interface) can be formed on the surface of the second perovskite layer. The second interface is also beneficial to increasing the number of absorbable wavelength photons and light utilization rate in the perovskite layer in the stacked solar cell, which is beneficial to improving the overall current level of the stacked solar cell and also beneficial to improving the photoelectric conversion efficiency.

[0018] Based on any suitable embodiment of the present application, in some further embodiments, the tandem solar cell satisfies one or more of the following characteristics:

[0019] The width of at least a portion of the ridges is 0.5 μm to 4 μm, and can further be 2 μm to 3.5 μm;

[0020] The half-height width of at least a portion of the ridges is 1 μm to 2.5 μm, and can be optionally 1.5 μm to 2 μm;

[0021] The height of at least a portion of the ridges is greater than or equal to 100 nm, and can further be 100 nm to 250 nm;

[0022] In at least a portion of the non-smooth surface, the average width of the ridges is 0.5 μm to 4 μm, and may be further 2 μm to 3.5 μm;

[0023] In at least a portion of the non-smooth surface, the average half-height width of the ridges is 1 μm to 2.5 μm, and can be optionally 1.5 μm to 2 μm;

[0024] In at least a portion of the non-smooth surface, the average height of the ridges is 100 nm to 500 nm, and may be 100 nm to 250 nm.

[0025] Optionally, the longitudinal projection area of ​​at least a portion of the non-smooth surface is greater than or equal to 0.1 mm 2 , further optionally greater than or equal to 0.6 mm 2 .

[0026] By adjusting one or more of the ridge width, half-width, height, and average values ​​of these parameters, the probability of photons emitted from the interior of the first perovskite layer toward the first interface after being reflected multiple times at the ridge interface of the first perovskite layer can be adjusted. By controlling one or more of these parameters within the above range, more photons are absorbed by the second perovskite layer, which helps increase the utilization rate of photons that are not absorbed after passing through the first perovskite layer. These photons may include photons in the wavelength band that can be absorbed by the second perovskite layer, thereby further improving the short-circuit current density and the photoelectric conversion efficiency of the stacked solar cell. Photons emitted from the side of the first perovskite layer toward the first interface can come from external incident light.

[0027] Based on any suitable embodiment of the present application, in some further embodiments, the tandem solar cell satisfies one or more of the following characteristics:

[0028] The width of at least a portion of the concave grooves is less than or equal to 1.2 μm, and may be 0.5 μm to 1 μm;

[0029] The half-height width of at least a portion of the concave grooves is less than or equal to 1 μm, and can be optionally 0.2 μm to 0.7 μm;

[0030] The depth of at least a portion of the concave grooves is greater than or equal to 100 nm, and can further be 100 nm to 250 nm;

[0031] The aspect ratio of at least a portion of the concave grooves is 0.03 to 0.5, and can further be 0.25 to 0.35;

[0032] In at least a portion of the non-smooth surface, the average width of the grooves is 0.3 μm to 1 μm, and may be 0.5 μm to 1 μm;

[0033] In at least a portion of the non-smooth surface, the average half-height width of the concave groove is 0.2 μm to 0.7 μm, and can be optionally 0.3 μm to 0.55 μm;

[0034] In at least a portion of the non-smooth surface, the average depth of the concave grooves is 100 nm to 500 nm, and can be optionally 100 nm to 250 nm;

[0035] In at least a portion of the non-smooth surface, the average aspect ratio of the concave groove is 0.03 to 0.5, and may be further 0.25 to 0.35;

[0036] Optionally, the longitudinal projection area of ​​at least a portion of the non-smooth surface is greater than or equal to 0.1 mm 2 , further optionally greater than or equal to 0.6 mm 2 .

[0037] By adjusting one or more parameters of the concave groove width, half-height width, depth, aspect ratio, and the average value of these parameters, the probability of photons emitted from the second perovskite layer side toward the first interface entering the first perovskite layer at the concave groove interface of the first perovskite layer can be adjusted. By controlling one or more of the above parameters within the above range, the optical path length of photons that are not absorbed after reflection from the interface of the second perovskite layer is significantly increased in the first perovskite layer, and more photons can be absorbed by the first perovskite layer. These photons may include photons in the wavelength band that can be absorbed by the first perovskite layer, thereby improving light utilization efficiency, thereby better improving the overall current level and improving the photoelectric conversion efficiency of the tandem solar cell. Among them, the photons emitted from the second perovskite layer side toward the first interface can come from reflected light at the second electrode.

[0038] By comprehensively adjusting the width and length of the concave groove, the proportion of the longitudinal projection area of ​​the concave groove in the longitudinal projection area of ​​the first perovskite layer can be adjusted. The higher the proportion, the more significant the comprehensive improvement of the overall current level and photoelectric conversion efficiency by the concave groove. The longitudinal projection area of ​​the first perovskite layer can be considered to be substantially equal to the longitudinal projection area of ​​the non-smooth surface. Therefore, the proportion of the longitudinal projection area of ​​the concave groove in the longitudinal projection area of ​​the first perovskite layer is substantially equal to the percentage of the sum of the longitudinal projection areas of the concave groove relative to the longitudinal projection area of ​​the non-smooth surface.

[0039] Based on any suitable embodiment of the present application, in some further embodiments, the tandem solar cell satisfies one or more of the following characteristics:

[0040] In at least a portion of the non-smooth surface, the average spacing of the ridges is 1 μm to 20 μm, and can be optionally 10 μm to 20 μm;

[0041] In at least a portion of the non-smooth surface, the average spacing of the grooves is 1 μm to 20 μm, and can be optionally 10 μm to 20 μm;

[0042] The half-height width of at least a portion of the convex ridges is greater than the half-height width of the adjacent concave grooves;

[0043] In at least a portion of the non-smooth surface, the ratio of the average half-height width of the ridges to the average half-height width of the grooves is 1 to 6, and can further be 4 to 5;

[0044] In at least a portion of the non-smooth surface, the ratio of the sum of the half-height cross-sectional areas of the ridges to the sum of the half-height cross-sectional areas of the grooves is 1 to 36, and may further be 10 to 30;

[0045] In at least a portion of the non-smooth surface, the percentage of the sum of the projected areas of the concave grooves along the longitudinal direction relative to the projected area of ​​the non-smooth surface along the longitudinal direction is 5% to 95%, and can further be 5% to 50%;

[0046] Optionally, the longitudinal projection area of ​​at least a portion of the non-smooth surface is greater than or equal to 0.1 mm 2 , further optionally greater than or equal to 0.6 mm 2 .

[0047] By adjusting one or more parameters such as the average spacing of the ridges, the average spacing of the concave grooves, the ratio of the average half-height width of the ridges to the average half-height width of the concave grooves, and the ratio of the sum of the half-height cross-sectional areas of the ridges to the sum of the half-height cross-sectional areas of the concave grooves, the density of the concave grooves and / or ridges on the non-smooth surface of the first perovskite layer can be adjusted, the unevenness of the non-smooth surface can be adjusted, and thus the degree of improvement in the photoelectric conversion effect can be adjusted. By controlling one or more of these parameters within the above range, the concave-convex morphology of the first interface can be fully utilized to allow the first perovskite layer and / or the second perovskite layer to absorb more photons, which is more conducive to improving the short-circuit current density. In addition, it can also be more conducive to improving the photoelectric conversion efficiency. When external incident light is incident from the first electrode, by controlling the half-height width of at least a portion of the ridges to be greater than the half-height width of the adjacent concave grooves, it is beneficial for more photons that are not utilized by the first perovskite layer among the photons initially incident on the first interface to enter the second perovskite layer.

[0048] Based on any suitable embodiment of the present application, in some further embodiments, the opening width of at least a portion of the concave grooves is greater than the bottom width;

[0049] Optionally, based on the proportion of the projected area of ​​the concave grooves along the longitudinal direction, at least 50% of the concave grooves have an opening width greater than the bottom width; further optionally, at least 80% of the concave grooves have an opening width greater than the bottom width;

[0050] Optionally, based on the proportion of the projected area of ​​the concave groove along the longitudinal direction, the opening width of at least a portion of the concave grooves is greater than the half-height width and the bottom width; further optionally, the opening width of at least 50% of the concave grooves is greater than the half-height width and the bottom width; further optionally, the opening width of at least 80% of the concave grooves is greater than the half-height width and the bottom width.

[0051] When the concave groove as a whole has a cross-sectional shape of "wide at the top and narrow at the bottom", at this time, the opening width of the concave groove is greater than the bottom width. Furthermore, the opening width > half-height width > bottom width, which is beneficial to increase the number of photons entering the first perovskite layer, can correspondingly increase the amount of light absorption, can better improve the short-circuit current density, and in addition, it is also beneficial to better improve the photoelectric conversion efficiency.

[0052] Based on any suitable embodiment of the present application, in some further embodiments, the bottom width of at least a portion of the ridges is greater than the top width;

[0053] Optionally, based on the proportion of the projected area of ​​the ridges along the longitudinal direction, at least 50% of the ridges have a bottom width greater than the top width; further optionally, at least 80% of the ridges have a bottom width greater than the top width.

[0054] Optionally, based on the proportion of the projected area of ​​the ridges along the longitudinal direction, the bottom width of at least a portion of the ridges is greater than the half-height width and the top width; further optionally, at least 50% of the ridges have a bottom width greater than the half-height width and the top width; further optionally, at least 80% of the ridges have a bottom width greater than the half-height width and the top width.

[0055] When the ridge as a whole has a cross-sectional shape of "narrow at the top and wide at the bottom", the bottom width of the ridge is greater than the top width. Furthermore, the bottom width > half-height width > top width, which is beneficial to increase the number of photons entering the second perovskite layer, and can correspondingly increase the amount of light absorption, which can better improve the short-circuit current density. In addition, it is also beneficial to better improve the photoelectric conversion efficiency.

[0056] Based on any suitable embodiment of the present application, in some further embodiments, the tandem solar cell satisfies one or more of the following characteristics:

[0057] At least a portion of the concave grooves have corners in their extending directions;

[0058] At least a portion of the concave grooves has a non-linear extension direction;

[0059] At least a portion of the concave grooves have intersection nodes;

[0060] At least a portion of the ridges have corners in their extension direction;

[0061] At least a portion of the ridges have a non-linear extension direction;

[0062] At least a portion of the ridges have intersection nodes;

[0063] The maximum width of at least a portion of the concave grooves within the extended length deviates by no more than 30% from the average width of the concave grooves;

[0064] The maximum width of at least a portion of the ridges within the extended length deviates by no more than 30% from the average width of the ridges;

[0065] The extension length of at least a portion of the concave grooves is greater than or equal to 50 μm;

[0066] The extension length of at least a portion of the ridges is greater than or equal to 50 μm;

[0067] The aspect ratio of at least a portion of the concave grooves is greater than or equal to 2. Optionally, the aspect ratio of at least a portion of the concave grooves is greater than or equal to 5.

[0068] The aspect ratio of at least a portion of the concave grooves is 1 to 10, and can be 5 to 10;

[0069] The aspect ratio of at least a portion of the ridges is greater than or equal to 2. Optionally, the aspect ratio of at least a portion of the ridges is greater than or equal to 5.

[0070] The aspect ratio of at least a portion of the ridges is 1-20, and can be optionally 10-20.

[0071] When at least a portion of the concave grooves have one or more of the following characteristics in the extension direction: (1) there is a corner in the extension direction of the concave groove; (2) at least a length of the extension direction of the concave groove is non-linear; and (3) there are intersection nodes in the concave grooves, in this case, the concave grooves are more likely to be randomly distributed on the non-smooth surface of the first perovskite layer, which is beneficial to shorten the transmission distance of photons in the concave grooves that contact the first interface twice continuously, which is beneficial to improve the transmission efficiency of photons, thereby helping to better improve the short-circuit current density and photoelectric conversion efficiency. Among them, the existence of intersection nodes in different concave grooves means that the extension directions of these concave grooves are not parallel or not completely parallel, so that different concave grooves are connected.

[0072] When at least a portion of the ridges have one or more of the following characteristics in their extension direction: (1) there are corners in the extension direction of the ridges; (2) at least a length in the extension direction of the ridges is non-linear; and (3) there are intersection nodes in the ridges, then the ridges are more likely to be randomly distributed on the non-smooth surface of the first perovskite layer, which is beneficial to shortening the transmission distance of photons at the ridge interface that contact the first interface twice in a row, thereby improving the transmission efficiency of photons and thus better improving the optical short-circuit current density and electrical conversion efficiency. The existence of intersection nodes in different ridges means that the extension directions of these ridges are not parallel or not completely parallel, so that different ridges are connected.

[0073] When the concave grooves and the convex ridges respectively meet at least one of the above characteristics, it is beneficial to more effectively exert the synergistic effect between the concave grooves and the convex ridges, while increasing the number of photons and the amount of light absorption in the first perovskite layer and the second perovskite layer, which can better improve the short-circuit current density. In addition, it is also beneficial to better improve the photoelectric conversion efficiency.

[0074] Based on any suitable embodiment of the present application, in some further embodiments, the tandem solar cell satisfies one or more of the following characteristics:

[0075] The angle between the extension directions of at least two adjacent concave grooves satisfies ≤30° in an extension length region of at least 30 μm;

[0076] The angle between the extension directions of at least a portion of two adjacent ridges satisfies ≤30° in an extension length region of at least 30 μm.

[0077] Based on any suitable embodiment of the present application, in some further embodiments, the tandem solar cell satisfies one or more of the following characteristics:

[0078] The angle between the extension directions of at least two adjacent concave grooves satisfies ≤15° over an extension length of at least 30 μm; optionally, the angle between the extension directions of at least two adjacent concave grooves satisfies ≤15° over an extension length of at least 50 μm; further optionally, the angle between the extension directions of at least two adjacent concave grooves satisfies ≤15° over an extension length of at least 80 μm;

[0079] The angle between the extension directions of at least two adjacent concave grooves satisfies ≤30° over an extension length of at least 50 μm; optionally, the angle between the extension directions of at least two adjacent concave grooves satisfies ≤30° over an extension length of at least 80 μm;

[0080] The angle between the extension directions of at least two adjacent ridges satisfies ≤15° over an extension length of at least 30 μm; optionally, the angle between the extension directions of at least two adjacent ridges satisfies ≤15° over an extension length of at least 50 μm; further optionally, the angle between the extension directions of at least two adjacent ridges satisfies ≤15° over an extension length of at least 80 μm;

[0081] The angle between the extension directions of at least two adjacent ridges satisfies ≤30° over an extension length of at least 50 μm; optionally, the angle between the extension directions of at least two adjacent ridges satisfies ≤30° over an extension length of at least 80 μm.

[0082] The regularity of the concave grooves in the non-smooth surface of the first perovskite layer can be adjusted by adjusting the angle between the extension directions of two adjacent concave grooves. The smaller the angle, the more consistent the extension directions of the two adjacent concave grooves and the better the parallelism. The longer the extension length with a relatively small angle, the higher the regularity of the concave grooves and the better the parallelism between the two adjacent concave grooves.

[0083] The regularity of the ridges on the non-smooth surface of the first perovskite layer can be adjusted by adjusting the angle between the extension directions of two adjacent ridges. The smaller the angle, the more consistent the extension directions of the two adjacent ridges, and the better the parallelism. The longer the extension length with a relatively small angle, the higher the regularity of the ridges and the better the parallelism between the two adjacent ridges.

[0084] When the concave grooves and the convex ridges respectively meet at least one of the above characteristics, the functions of the concave grooves and the convex ridges can be effectively exerted.

[0085] Based on any suitable embodiment of the present application, in some further embodiments, the band gap of the first perovskite layer is greater than the band gap of the second perovskite layer;

[0086] Optionally, the band gap of the first perovskite layer is 1.2 eV to 2.4 eV, optionally 1.6 eV to 2.3 eV; the band gap of the second perovskite layer is 1.0 eV to 1.4 eV.

[0087] By regulating the band gap of the perovskite layer, the wavelength range in which the perovskite layer can absorb photons can be regulated. When the band gaps of the first perovskite layer and the second perovskite layer are respectively controlled within the above ranges, it is beneficial to better broaden the absorption band of incident light. Combined with the special morphology of the first interface, the first perovskite layer and the second perovskite layer can have a higher total light absorption and light utilization rate as a whole, which can better improve the photoelectric conversion efficiency and short-circuit current density.

[0088] Based on any suitable embodiment of the present application, in some further embodiments, the first perovskite layer includes a first perovskite metal halide, and the halogen in the first perovskite metal halide includes bromine and iodine; optionally, the halogen in the first perovskite metal halide is a combination of bromine and iodine;

[0089] Optionally, the second perovskite layer includes a second perovskite metal halide, and the halogen in the second perovskite metal halide includes iodine; further optionally, the halogen in the second perovskite metal halide is iodine.

[0090] According to the composition design of the perovskite metal halide in the first perovskite layer, bromine and iodine elements can be set simultaneously in the perovskite precursor solution. By adjusting the atomic molar ratio of the two elements, the size-related parameters of the grooves and ridges (such as length, width, depth or height, aspect ratio or height-to-width ratio, half-height width, half-height cross-section and the average value of any of the above parameters, etc.), distribution-related parameters (average spacing, proportion of the projected area of ​​the grooves or ridges on the non-smooth surface, the ratio of the average half-height width of the ridges to the average half-height width of the grooves, the ratio of the sum of the half-height cross-section areas of the ridges to the sum of the half-height cross-section areas of the grooves) and other parameters can be controlled, thereby flexibly adjusting the enhancing effect of the concave-convex interface on the short-circuit current density and photoelectric conversion efficiency.

[0091] In addition, by adjusting the halogen composition of the perovskite-type metal halide in the first perovskite layer and the second perovskite layer, it is also possible to adjust the band gap difference in the two light-absorbing layers and the first interface morphology, thereby broadening the absorbable band of incident light, promoting more photons to enter the perovskite layer in the stacked solar cell through the first interface, and improving the comprehensive performance of short-circuit current density and photoelectric conversion efficiency.

[0092] Based on any suitable embodiment in the present application, in some further embodiments, the atomic molar ratio of bromine element to iodine element in the first perovskite metal halide is (3 - y):y, where 0 < y ≤ 2; optionally, 1 ≤ y ≤ 2.

[0093] According to the composition design of the perovskite metal halide in the first perovskite layer, the atomic molar ratio of bromine element to iodine element in the perovskite precursor solution can be adjusted, thereby regulating the comprehensive performance of the short - circuit current density and photoelectric conversion efficiency of the tandem solar cell. By adjusting the atomic molar ratio of bromine element to iodine element in the perovskite metal halide in the first perovskite layer within the above range, the short - circuit current density of the tandem solar cell can be preferably improved, and it can also be used to improve the photoelectric conversion efficiency.

[0094] Based on any suitable embodiment in the present application, in some further embodiments, at least a part of the perovskite grains in the first perovskite layer are through - type grains, and both ends of the through - type grains along the longitudinal direction are respectively located on both side surfaces of the first perovskite layer.

[0095] When the perovskite grains in the first perovskite layer include through - type grains along the thickness direction of the first perovskite layer (i.e., along the longitudinal direction), it means that these perovskite grains grow continuously in the longitudinal direction, with fewer cracks in the longitudinal cross - section of the first perovskite layer, presenting as large - sized grains longitudinally penetrating. At this time, the through - type grains longitudinally penetrating the first perovskite layer are beneficial to the smoother and more efficient transport of carriers, beneficial to reducing non - radiative recombination caused by grain interfaces, and improving the short - circuit current density and photoelectric conversion efficiency of the device.

[0096] Based on any suitable embodiment in the present application, in some further embodiments, the lateral size of at least a part of the through - type grains is greater than or equal to 400 nm; where the lateral direction is orthogonal to the longitudinal direction, and the lateral size of the through - type grains represents the maximum size among the grain sizes in the lateral cross - section;

[0097] Optionally, the lateral size of at least a part of the through - type grains is greater than or equal to 400 nm, and can be optionally greater than or equal to 500 nm;

[0098] Optionally, the average lateral size of the through - type grains is 300 nm to 2 μm, optionally 400 nm to 1 μm, and further optionally 500 nm to 800 nm.

[0099] By controlling the lateral size of the through-type grains, the number of interfaces between perovskite grains can be adjusted. A larger lateral size results in fewer through-type seams between grains, which in turn leads to fewer defects and higher quality in the perovskite layer. By controlling the lateral size of the through-type grains within the aforementioned range, the aforementioned promoting effect of the through-type grains can be fully utilized.

[0100] Based on any suitable embodiment of the present application, in some further embodiments, within at least a portion of the width region of the longitudinal cross section of the first perovskite layer, the area percentage of the through-type grains relative to the longitudinal cross section is greater than or equal to 80%, and may be greater than or equal to 90%;

[0101] Optionally, at least a portion of a width region of a longitudinal cross section of the first perovskite layer corresponds to a width region of at least 10 μm.

[0102] By controlling the percentage of the area occupied by the through-type grains in the longitudinal cross-section of the first perovskite layer, the role of the through-type grains can be adjusted. By controlling the area percentage of the through-type grains relative to the longitudinal cross-section of the first perovskite layer within the above range, the advantages of the through-type grains can be more fully utilized, further facilitating improvements in carrier transport and photoelectric conversion efficiency.

[0103] Based on any suitable embodiment in the present application, in some further embodiments, on the longitudinal cross-section of the first perovskite layer, the area percentage of the through-type grains with a lateral size greater than or equal to 400 nm relative to the longitudinal cross-section is greater than or equal to 80%, and can be optionally greater than or equal to 90%.

[0104] By controlling the area ratio of larger through-type grains within the longitudinal cross-section of the first perovskite layer, the role of the through-type grains can be adjusted. By controlling the area ratio of through-type grains of a certain lateral size relative to the longitudinal cross-section of the first perovskite layer within the above range, the advantages of the through-type grains can be more fully utilized, further facilitating improvements in carrier transport and photoelectric conversion efficiency.

[0105] Based on any suitable embodiment of the present application, in some further embodiments, the tandem solar cell satisfies one or more of the following characteristics:

[0106] The first carrier transport layer and the third carrier transport layer are both electron transport layers, and the second carrier transport layer and the fourth carrier transport layer are both hole transport layers, or the first carrier transport layer and the third carrier transport layer are both hole transport layers, and the second carrier transport layer and the fourth carrier transport layer are both electron transport layers;

[0107] The tandem solar cell further includes a first electrode and a second electrode, wherein the first electrode is located on a side of the first perovskite sub-cell away from the carrier recombination layer, and the second electrode is located on a side of the second perovskite sub-cell away from the carrier recombination layer; the first electrode is a transparent electrode;

[0108] At least one side of the first carrier transport layer comprises a heterogeneous carrier blocking layer;

[0109] At least one side of the second carrier transport layer includes a heterogeneous carrier blocking layer;

[0110] At least one side of the third carrier transport layer comprises a heterogeneous carrier blocking layer;

[0111] At least one side of the fourth carrier transport layer includes a heterogeneous carrier blocking layer.

[0112] The first perovskite sub-cell and the second perovskite sub-cell may both be nip-type or both be pin-type.

[0113] When the first electrode is a transparent electrode, the incident light entering the stacked solar cell can enter from the first electrode side. At this time, when the incident light is first emitted from the first perovskite layer side to the first interface, the first interface is conducive to achieving the aforementioned effect of improving the comprehensive performance of short-circuit current density and photoelectric conversion efficiency.

[0114] In addition, a heterogeneous carrier blocking layer may be provided on at least one side of one or more of the first carrier transport layer, the second carrier transport layer, the third carrier transport layer, and the fourth carrier transport layer to block the transport of heterogeneous carriers, thereby facilitating the reduction of the recombination probability of electrons and holes.

[0115] Based on any suitable embodiment in the present application, in some further embodiments, the first perovskite sub-cell and the second perovskite sub-cell form a two-terminal integrated structure.

[0116] Based on any suitable embodiment in the present application, in some further embodiments, the tandem solar cell is a two-terminal tandem solar cell.

[0117] Based on any suitable embodiment in the present application, in some further embodiments, the tandem solar cell is a full perovskite tandem solar cell.

[0118] In a second aspect of the present application, a method for preparing the perovskite-based tandem solar cell according to the first aspect of the present application is provided, comprising the following steps: sequentially stacking a first carrier transport layer, a first perovskite layer, a second carrier transport layer, a carrier recombination layer, a third carrier transport layer, a second perovskite layer, a fourth carrier transport layer, and a second electrode on a surface of one side of a first electrode to prepare the perovskite-based tandem solar cell;

[0119] The method of stacking the first perovskite layer on the side of the first carrier transport layer facing away from the first electrode comprises the following steps:

[0120] Applying the precursor solution I of the first perovskite layer to the surface of the first carrier transport layer on the side facing away from the first electrode to form a coating layer I;

[0121] The coating layer I is subjected to vacuum flash evaporation treatment and annealing treatment to form the first perovskite layer, and the non-smooth surface is formed on the side of the first perovskite layer facing away from the first electrode.

[0122] By preparing the first perovskite layer through a vacuum flash evaporation process, the aforementioned concave grooves and convex ridges can be formed on the surface of the first perovskite layer near the carrier recombination layer. This increases the amount of photons contacting the perovskite layer and the light utilization rate, thereby improving the short-circuit current density of the tandem solar cell and the photoelectric conversion efficiency. Furthermore, it can promote the formation of large-sized through-type grains, thereby enhancing carrier transport and photoelectric conversion efficiency.

[0123] Based on any suitable embodiment of the present application, in some further embodiments, the method for preparing the perovskite-based tandem solar cell satisfies one or more of the following characteristics:

[0124] The vacuum flash evaporation treatment is carried out under negative pressure conditions, which are less than or equal to 100 Pa, and can be selected from 50 Pa to 100 Pa;

[0125] The temperature for the vacuum flash evaporation treatment is -10°C to 100°C, optionally 0°C to 30°C, and further optionally 20°C to 30°C;

[0126] The duration of the vacuum flash evaporation treatment is 10s to 100s, optionally 10s to 30s, and further optionally 15s to 25s;

[0127] The annealing treatment is performed on a hot plate, optionally on a 30°C to 200°C hot plate, further optionally on a 90°C to 110°C hot plate, and further optionally on a 98°C to 102°C hot plate;

[0128] The annealing time for the annealing treatment is 30 seconds to 60 minutes, optionally 5 minutes to 20 minutes, and further optionally 14 minutes to 16 minutes.

[0129] Based on any suitable embodiment of the present application, in some further embodiments, the step of coating the precursor solution I of the first perovskite layer onto the surface of the first carrier transport layer on a side facing away from the first electrode includes:

[0130] Spin coating a portion of the precursor solution I onto a surface of the first carrier transport layer facing away from the first electrode at a first rotation speed;

[0131] accelerating the rotation speed from the first rotation speed to a second rotation speed, and continuing to spin-coat another portion of the precursor liquid I at the second rotation speed;

[0132] Wherein, the second speed is greater than the first speed.

[0133] Based on any suitable embodiment of the present application, in some further embodiments, the method for preparing the perovskite-based tandem solar cell satisfies one or more of the following characteristics:

[0134] The first rotation speed is 1000 rpm to 6000 rpm, and can be optionally 1000 rpm to 2000 rpm; the spin coating is performed at the first rotation speed for 8 s to 12 s;

[0135] In the step of accelerating the rotational speed from the first rotational speed to the second rotational speed, the acceleration is 200 rpm / s to 2000 rpm / s, and can be optionally 800 rpm / s to 1200 rpm / s;

[0136] The second rotation speed is 3000 rpm to 4500 rpm, and can be optionally 3800 rpm to 4200 rpm; the spin coating is performed at the second rotation speed for 18 s to 22 s.

[0137] By adjusting one or more parameters in the preparation process of the first perovskite layer and regulating the surface morphology and / or grain size of the first perovskite layer as needed, the comprehensive performance of the short-circuit current density and photoelectric conversion efficiency of the stacked solar cell can be better improved through process parameter optimization.

[0138] In a third aspect of the present application, an electrical device is provided, comprising at least one of the perovskite-based tandem solar cells described in the first aspect of the present application and the perovskite-based tandem solar cell prepared by the preparation method of the perovskite-based tandem solar cell described in the second aspect of the present application.

[0139] The details of one or more embodiments and examples of the present application are set forth in the following drawings and description. Other features, objects, and advantages of the present application will become apparent from the description, drawings, and claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0140] In order to better describe and illustrate the embodiments, examples, or examples of the applications disclosed herein, reference may be made to one or more of the accompanying drawings. The additional details or examples used to describe the accompanying drawings should not be considered as limiting the scope of the disclosed applications, the embodiments, examples, or examples currently described, and the best modes currently understood for these applications. Moreover, the same reference numerals are used throughout the drawings to represent the same parts. In the drawings:

[0141] FIG1 is an optical microscope observation image of a non-smooth surface of a first perovskite layer in one embodiment of the present application.

[0142] FIG2 is a schematic diagram of the transmission path of incident light at the non-smooth surface of the first perovskite layer in one embodiment of the present application.

[0143] FIG3 is an optical microscope observation image of a stacked solar cell from the glass substrate side in one embodiment of the present application, wherein a transparent electrode is provided on the surface of the glass substrate near the carrier recombination layer.

[0144] FIG4 is a scanning electron microscope (SEM) image of a longitudinal cross section of a stacked solar cell prepared by a vacuum flash evaporation method in one embodiment of the present application.

[0145] FIG5 is a scanning electron microscope (SEM) image of a longitudinal cross section of a stacked solar cell prepared by a vacuum flash evaporation method in one embodiment of the present application.

[0146] FIG6 is a scanning electron microscope (SEM) image of a transverse cross section of a wide bandgap perovskite layer prepared by vacuum flash evaporation in one embodiment of the present application.

[0147] FIG7 is a schematic diagram of the transmission path of the incident light at the interface between the wide bandgap perovskite layer and the intermediate interconnect layer in a comparative example of the present application, in which the wide bandgap perovskite layer is prepared by the anti-solvent method.

[0148] FIG8 is an optical microscope observation image of a full perovskite stacked solar cell from the glass substrate side in a pair of ratios of the present application, wherein a transparent electrode is provided on the surface of the glass substrate near the carrier recombination layer.

[0149] FIG9 is a scanning electron microscope (SEM) image of a longitudinal cross section of a stacked solar cell prepared by an anti-solvent method in a comparative example of the present application.

[0150] FIG10 is a schematic diagram of a stacked solar cell in one embodiment of the present application; the stacked solar cell includes a first perovskite sub-cell, a carrier recombination layer, and a second perovskite sub-cell stacked in sequence.

[0151] Figure 11 is a schematic diagram of a stacked solar cell in one embodiment of the present application; the stacked solar cell includes a substrate layer, a first perovskite sub-cell, a carrier recombination layer and a second perovskite sub-cell stacked in sequence; wherein the first perovskite sub-cell includes a first electrode, a first carrier transport layer, a first perovskite layer and a second carrier transport layer stacked in sequence, and the second perovskite sub-cell includes a third carrier transport layer, a second perovskite layer, a fourth carrier transport layer and a second electrode stacked in sequence; wherein the first electrode, the first carrier transport layer, the first perovskite layer, the second carrier transport layer, the carrier recombination layer, the third carrier transport layer, the second perovskite layer, the fourth carrier transport layer and the second electrode are stacked in sequence.

[0152] FIG12 is a schematic diagram of a stacked solar cell in one embodiment of the present application; the stacked solar cell includes a substrate layer, a first perovskite subcell, a carrier recombination layer, and a second perovskite subcell stacked in sequence; wherein the first perovskite subcell includes a first electrode, a first carrier transport layer, a first perovskite layer, and a second carrier transport layer stacked in sequence, and the second perovskite subcell includes a third carrier transport layer, a second perovskite layer, a fourth carrier transport layer, and a second electrode stacked in sequence; wherein the first electrode, the first perovskite subcell, the first carrier transport layer, the first perovskite layer, and the second carrier transport layer stacked in sequence. A carrier transport layer, a first perovskite layer, a second carrier transport layer, a carrier recombination layer, a third carrier transport layer, a second perovskite layer, a fourth carrier transport layer and a second electrode are stacked in sequence; wherein the fourth carrier transport layer and the second carrier transport layer are both electron transport layers, and the third carrier transport layer and the first carrier transport layer are both hole transport layers; the side of the fourth carrier transport layer close to the second perovskite layer includes a second hole blocking layer, and the side of the second carrier transport layer close to the first perovskite layer includes a first hole blocking layer.

[0153] FIG13 is a schematic diagram of an electrical device in which a stacked solar cell according to an embodiment of the present application is used as a power generation device.

[0154] Explanation of the accompanying figures: 10 is a stacked solar cell; 100 is a substrate layer; 200 is a first perovskite sub-cell; 220 is a first electrode; 230 is a first carrier transport layer; 240 is a first perovskite layer; 250 is a second carrier transport layer; 2501 is a first hole blocking layer; 400 is an intermediate interconnect layer; 410 is a carrier recombination layer; 600 is a second perovskite sub-cell; 630 is a third carrier transport layer; 640 is a second perovskite layer; 650 is a fourth carrier transport layer; 6501 is a second hole blocking layer; 660 is a second electrode; 6 is an electrical device; the double-headed arrow X indicates the thickness direction of the first perovskite layer; 900 is an intermediate interconnect layer with smooth interfaces on both sides, and 920 and 940 are two perovskite layers on both sides of the intermediate interconnect layer, respectively.

[0155] In Figures 4, 5, 6, and 9, EHT corresponds to the accelerating voltage, WD corresponds to the working distance, Mag corresponds to the magnification, Signal A corresponds to the detector model, Date corresponds to the test date, and Iprobe corresponds to the probe current. DETAILED DESCRIPTION

[0156] Below, some embodiments and examples of the laminated solar cell, preparation method, and electrical device of the present application are described in detail with appropriate reference to the accompanying drawings. However, unnecessary detailed descriptions may be omitted. For example, detailed descriptions of well-known matters and repeated descriptions of substantially identical structures may be omitted. This is to avoid the following description from becoming unnecessarily lengthy and to facilitate understanding by those skilled in the art. In addition, the drawings and the following description are provided to enable those skilled in the art to fully understand the present application and are not intended to limit the subject matter described in the claims.

[0157] " scope " disclosed in the present application can be limited in the form of lower limit and upper limit, and given range is limited by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of special range. The scope limited in this way can be to include end value or not include end value, and any end value can be included or not included independently, and can be arbitrarily combined, that is, any lower limit can form a scope with any upper limit combination. For example, if the scope of 60-120 and 80-110 is listed for specific parameters, it is understood that the scope of 60-110 and 80-120 is also expected. In addition, if minimum range values ​​1 and 2 are listed, and if maximum range values ​​3,4 and 5 are also listed, then the following scope can all be expected: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5. In the present application, unless otherwise specified, numerical range " ab " represents the abbreviation of any real number combination between a and b, wherein a and b are all real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0-5" are listed herein, and "0-5" is merely an abbreviation for these numerical combinations. Furthermore, when a parameter is expressed as an integer greater than or equal to 2, this is equivalent to listing the parameter as, for example, the integers 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, and so on. For example, when a parameter is expressed as an integer selected from "2-10," this is equivalent to listing the integers 2, 3, 4, 5, 6, 7, 8, 9, and 10.

[0158] In this application, terms such as "multiple," "multiple," "multiple," "multiple times," and "several" refer to a number greater than or equal to two, unless otherwise specified. For example, "one or more" refers to one or greater than or equal to two. It is understood that when "any number" of items is mentioned, it refers to any suitable combination of multiple items, that is, any combination of "any number" of items that is not conflicting and that can implement this application.

[0159] Unless otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.

[0160] References to "embodiments" herein mean that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment or implementation of the present application. The appearance of such phrases in various locations in the specification does not necessarily refer to the same embodiment, nor does it necessarily refer to independent or alternative embodiments that are mutually exclusive with other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments. References to "implementations" herein have a similar understanding.

[0161] Those skilled in the art will appreciate that, in the method for each embodiment or embodiment, the writing order of each step does not mean a strict execution order and constitutes any limitation to the implementation process, and the detailed execution order of each step should be determined by its function and possible internal logic. Unless otherwise specified, all steps of the application can be performed in sequence, or can be performed randomly, or can preferably be performed in sequence. For example, method M includes steps (a) and (b), indicating that method M may include steps (a) and (b) performed in sequence, or may include steps (b) and (a) performed in sequence. For example, method M may also include step (c), indicating that step (c) can be added to method M in any order, for example, method M may include steps (a), (b) and (c), or may include steps (a), (c) and (b), or may include steps (c), (a) and (b), etc.

[0162] In this application, in open technical features or technical solutions described with words such as "contain," "include," and "include," unless otherwise specified, additional members other than the listed members are not excluded, and it can be regarded as providing both closed features or solutions consisting of the listed members and open features or solutions that also include additional members in addition to the listed members. For example, if A includes a1, a2, and a3, it may also include other members or not, unless otherwise specified. It can be regarded as providing both the feature or solution of "A consists of a1, a2, and a3" or "A is selected from the group consisting of a1, a2, and a3," and the feature or solution of "A includes not only a1, a2, and a3, but also other members."

[0163] In this application, unless otherwise specified, A (such as B) means that B is a non-limiting example of A. It can be understood that A is not limited to B.

[0164] In this application, "optionally", "optional", and "optional" mean optional, that is, any one of the two parallel schemes of "yes" or "no". If multiple "optional" appear in a technical solution, unless otherwise specified and there is no contradiction or mutual constraint, each "optional" is independent. Unless otherwise specified, the descriptions of "optionally include", "optionally contain", etc. in this application, taking "optionally include" as an example, mean "may include or not include". As a non-limiting example, "optional substance A" means including or not including substance A.

[0165] In this application, unless otherwise specified, the features or solutions corresponding to "and / or" include any one of two or more relevant listed items, and also include any and all combinations of the relevant listed items, wherein the arbitrary and all combinations include any two relevant listed items, any more relevant listed items, or a combination of all relevant listed items. For example, "A and / or B" means a group consisting of A, B, and "a combination of A and B." Among them, "including A and / or B" can mean "including A, including B, and including A and B", and can also mean "including A, including B, or including A and B", which can be appropriately understood according to the sentence in which it is located.

[0166] As used herein, "combination thereof", "any combination thereof", "any combination thereof" and the like include all suitable combinations of any two or more of the listed items.

[0167] Herein, the “suitable” mentioned in “suitable combination”, “suitable method”, “any suitable method”, etc. shall be based on the technical solution that can implement the present application.

[0168] Herein, the terms "preferred," "better," "more preferable," "suitable," "comparatively better," and "preferable" are used solely to describe preferred implementations or examples and should not be construed as limiting the scope of protection of this application. If multiple "preferred" terms appear in a technical solution, each "preferred" term is considered independent unless otherwise specified and there are no contradictions or mutual constraints.

[0169] In this application, "further", "further", "particularly", "for example", "such as", "example", "for example", etc. are used for descriptive purposes to indicate differences in content, but should not be understood as limiting the scope of protection of this application.

[0170] In this application, the terms "first," "second," "third," "fourth," etc. in "the first aspect," "the second aspect," "the third aspect," "the fourth aspect," etc. are used for descriptive purposes only and should not be understood as indicating or implying relative importance or quantity, nor should they be understood as implicitly indicating the importance or quantity of the indicated technical features. Furthermore, "first," "second," "third," "fourth," etc. serve only as non-exhaustive enumeration and description, and should be understood not to constitute a closed-ended limitation on quantity.

[0171] In this application, the term "room temperature" generally refers to 4°C to 35°C, and may refer to 20°C ± 5°C. In some embodiments of this application, room temperature refers to 20°C to 30°C.

[0172] In this application, reference to a "numerical value" includes the number itself and its reasonable approximations. The definition of the "numerical value" may be applicable to discrete numerical points as well as to the endpoints of a numerical range. In this application, whenever a numerical value or a numerical range is involved, unless otherwise specified, it should be understood that the numerical value covers its reasonable approximations, and the numerical range covers the reasonable approximations of the two endpoints. Those skilled in the art will understand that the acceptable fluctuation range of the relevant approximations can be included in the definition of the numerical value or the numerical range. In this application, unless otherwise specified, "N1" may be reasonably understood as "about N1", and "N1-N2" may be reasonably understood as "about N1 to about N2", wherein N1 and N2 are two unequal numerical values. For example, in some cases, due to one or more factors such as reasonable deviations allowed in the art, instrument control accuracy, etc., it is reasonable to include the approximate values ​​within the approximate range into the range defined by the numerical range; for example, "the temperature is 20°C to 30°C" can be understood as "about 20°C to about 30°C"; further, taking the endpoint "20°C" and its approximate number is ±1°C as an example, the approximate values ​​of 19°C, 19.5°C, etc. within the approximate range of "about 20°C" should also be included in the range indicated by 20°C to 30°C. As a non-limiting example, the percentage content "10%" can be reasonably understood as "about 10%". As another non-limiting example, the percentage content "2% to 10%" can be reasonably understood as "about 2% to about 10%". As another non-limiting example, the percentage content "0%" at least includes "none" and can also include the situation of "below the detection limit".

[0173] In this application, unless otherwise specified, "approximate number" covers the number itself and its approximate value within a reasonable fluctuation range based on the number. The reasonable fluctuation range may vary depending on the type and value of the number.

[0174] In this application, when describing a range of units, if only the right endpoint is followed by a unit, it means that the units of the left and right endpoints are the same. For example, 3~5h or 3-5h both indicate that the units of the left endpoint "3" and the right endpoint "5" are both hours, and both have the same meaning as 3h~5h. This understanding applies not only to time units, but also to unit descriptions of parameters such as temperature, size, and band gap.

[0175] The weights of the relevant components mentioned in the examples of this application may not only refer to the content of each component, but also represent the proportional relationship between the weights of the components. Therefore, as long as the content of the relevant components is proportionally enlarged or reduced according to the examples of this application, it is within the scope disclosed in the examples of this application. Furthermore, the masses involved in the examples of this application may be mass units known in the chemical industry such as micrograms (μg), milligrams (mg), grams (g), and kilograms (kg).

[0176] In this application, "greater than or equal to" and "greater than or equal to" can be equivalently expressed as "≥", "less than or equal to" and "less than or equal to" can be equivalently expressed as "≤", "greater than" can be equivalently expressed as ">", and "less than" can be equivalently expressed as "<". In this application, unless otherwise specified, "greater than or equal to", "greater than or equal to", and "≥" can be regarded as providing two solutions of "greater than" and "equal to". In this application, unless otherwise specified, "less than or equal to", "less than or equal to", and "≤" can be regarded as providing two solutions of "less than" and "equal to".

[0177] In this application, if there is no other indication regarding parameter units, the temperature unit ℃ means "degrees Celsius", the time unit min means "minute", the time unit s means "second", the length unit mm means "millimeter", μm means "micrometer", nm means "nanometer", the volume unit μL means "microliter", the area unit mm means "micrometer", and the 2 represents "square millimeter", the pressure unit Pa represents "Pascal", and the short-circuit current density unit is mA / cm 2 It stands for "milliampere per square centimeter", the speed unit rpm stands for "revolutions per minute", and the energy unit eV stands for "electron volt".

[0178] In this application, exemplary descriptions such as "in some embodiments (or examples)" and "in one embodiment (or example)" may include but are not limited to the following meanings: these solutions can be combined with other solutions in a suitable manner to form new technical solutions.

[0179] In a first aspect, the present application provides a perovskite-based tandem solar cell, which includes a perovskite light-absorbing layer, can provide a higher short-circuit current density, and is also beneficial to improving the photoelectric conversion efficiency.

[0180] In some embodiments, a perovskite-based tandem solar cell is provided, comprising a first perovskite layer and a second perovskite layer having different band gaps; a surface of the first perovskite layer adjacent to the second perovskite layer is a non-smooth surface having concave grooves, and ridges are formed between at least a portion of adjacent concave grooves; the tandem solar cell satisfies at least one of the following characteristics: at least a portion of the concave grooves has different widths at at least a portion of the depth positions; and at least a portion of the ridges has different widths at at least a portion of the height positions.

[0181] In some embodiments, a perovskite-based tandem solar cell is provided, comprising a first perovskite subcell, a carrier recombination layer, and a second perovskite subcell stacked in sequence; the first perovskite layer has a non-smooth surface on a side adjacent to the carrier recombination layer, the non-smooth surface being provided with concave grooves; further, at least a portion of the concave grooves have different widths at at least a portion of their depths. Optionally, the aspect ratio of the concave grooves is greater than 1. Optionally, the band gap of the first perovskite layer in the first perovskite subcell is different from the band gap of the second perovskite layer in the second perovskite subcell.

[0182] In some embodiments, a perovskite-based tandem solar cell is provided, comprising a first perovskite subcell, a carrier recombination layer, and a second perovskite subcell stacked in sequence; the first perovskite layer has a non-smooth surface on a side adjacent to the carrier recombination layer, the non-smooth surface being provided with concave grooves; further, ridges are formed between at least a portion of adjacent concave grooves. Optionally, the aspect ratio of the concave grooves is greater than 1. Optionally, the band gap of the first perovskite layer in the first perovskite subcell is different from the band gap of the second perovskite layer in the second perovskite subcell.

[0183] In some embodiments, a perovskite-based tandem solar cell is provided, comprising a first perovskite subcell, a carrier recombination layer, and a second perovskite subcell stacked in sequence; the first perovskite layer having a non-smooth surface on a side adjacent to the carrier recombination layer, the non-smooth surface being provided with ridges; further, at least a portion of adjacent ridges form concave grooves. Optionally, the concave grooves have an aspect ratio greater than 1. Optionally, the band gap of the first perovskite layer in the first perovskite subcell is different from the band gap of the second perovskite layer in the second perovskite subcell.

[0184] In some embodiments, a perovskite-based tandem solar cell is provided, comprising a first perovskite sub-cell, a carrier recombination layer, and a second perovskite sub-cell stacked in sequence; the first perovskite layer has a non-smooth surface on a side adjacent to the carrier recombination layer, the non-smooth surface being provided with ridges; further, at least a portion of the ridges have different widths at at least a portion of their heights. Optionally, the band gap of the first perovskite layer in the first perovskite sub-cell is different from the band gap of the second perovskite layer in the second perovskite sub-cell.

[0185] In some embodiments, a perovskite-based tandem solar cell is provided, comprising a first perovskite subcell, a carrier recombination layer, and a second perovskite subcell stacked in sequence; the surface of the first perovskite layer adjacent to the carrier recombination layer is non-smooth, the non-smooth surface being provided with concave grooves, and ridges being formed between at least a portion of adjacent concave grooves; the tandem solar cell satisfies at least one of the following characteristics (i) and (ii): (i) at least a portion of the concave grooves have different widths at at least a portion of their depths; and (ii) at least a portion of the ridges have different widths at at least a portion of their heights. Optionally, the aspect ratio of the concave grooves is greater than 1. Optionally, the band gap of the first perovskite layer in the first perovskite subcell is different from the band gap of the second perovskite layer in the second perovskite subcell.

[0186] In some embodiments, a perovskite-based tandem solar cell is provided, comprising a first perovskite subcell, a carrier recombination layer, and a second perovskite subcell stacked in sequence; the surface of the first perovskite layer adjacent to the carrier recombination layer is non-smooth, the non-smooth surface being provided with concave grooves, with ridges formed between at least a portion of adjacent concave grooves; the concave-convex interface formed by the concave grooves and the ridges with the adjacent structural layer is referred to as a first interface; the tandem solar cell satisfies at least one of the following characteristics (i) and (ii): (i) at least a portion of the concave grooves has a different width at at least a portion of the depth; and (ii) at least a portion of the ridges has a different width at at least a portion of the height. The tandem solar cell has a good combination of short-circuit current density and photoelectric conversion efficiency. Optionally, the band gap of the first perovskite layer in the first perovskite subcell is different from the band gap of the second perovskite layer in the second perovskite subcell.

[0187] In some embodiments, a perovskite-based tandem solar cell is provided, the tandem solar cell comprising a first perovskite sub-cell, a carrier recombination layer, and a second perovskite sub-cell stacked in sequence, the first perovskite sub-cell comprising a first perovskite layer, the second perovskite sub-cell comprising a second perovskite layer; the band gap of the first perovskite layer is different from the band gap of the second perovskite layer;

[0188] The thickness direction of the first perovskite layer is recorded as the longitudinal direction;

[0189] The surface of the first perovskite layer on the side close to the carrier recombination layer is a non-smooth surface, and the non-smooth surface is provided with concave grooves; convex ridges are formed between at least a portion of adjacent concave grooves; and a concave-convex interface formed by the concave grooves, the convex ridges, and the adjacent structural layer is recorded as a first interface;

[0190] The tandem solar cell meets at least one of the following characteristics:

[0191] At least a portion of the concave grooves have different widths at at least a portion of their depths;

[0192] At least some of the ridges have different widths at at least some height positions.

[0193] In this application, unless otherwise specified, "perovskite-based tandem solar cell" refers to a tandem solar cell in which the light-absorbing layer of at least one sub-cell includes a perovskite semiconductor material. Unless otherwise specified, "tandem solar cell" has the commonly known meaning in the art, referring to a solar cell formed by stacking sub-cells based on semiconductor materials with different band gaps. This can broaden the solar cell's absorption spectrum and reduce thermal relaxation losses.

[0194] In this application, unless otherwise specified, "perovskite layer" refers to a light-absorbing layer containing a perovskite semiconductor material. Depending on the sub-cell in which it is located, it can be divided into different perovskite layers, such as the first perovskite layer contained in the first perovskite sub-cell, the second perovskite layer contained in the second perovskite sub-cell, etc.

[0195] In the present application, unless otherwise specified, the "carrier recombination layer" is a structural layer for the recombination of electrons and holes transmitted from the first perovskite sub-cell and the second perovskite sub-cell, or a structural layer for the recombination of holes and electrons transmitted from the first perovskite sub-cell and the second perovskite sub-cell, so that the first perovskite sub-cell and the second perovskite sub-cell are connected in series.

[0196] In this application, unless otherwise specified, "band gap" has a commonly understood meaning in the art and can be analyzed, compared, and confirmed using conventional methods in the art. Without limitation, the band gap of a material can be determined by its absorption or emission spectrum. Common optical methods include UV-visible absorption spectroscopy, photoluminescence spectroscopy, and Raman spectroscopy.

[0197] In some embodiments, the band gap of the first perovskite layer is greater than the band gap of the second perovskite layer. In this case, the first perovskite layer is also referred to as a wide-bandgap perovskite layer, and the second perovskite layer is also referred to as a narrow-bandgap perovskite layer. In this application, unless otherwise specified, "wide-bandgap" and "narrow-bandgap" are relative concepts, and the absolute values ​​of the band gaps are not particularly limited. It means that the band gap of the "wide-bandgap structural layer" is greater than the band gap of the "narrow-bandgap structural layer."

[0198] In this application, unless otherwise specified, the thickness direction of the first perovskite layer is referred to as the "longitudinal direction," as indicated by the X-direction in Figures 10-12. Along the longitudinal direction, the first perovskite layer has two opposing surfaces, the surface proximal to the carrier recombination layer being referred to as the first surface, and the surface facing away from the carrier recombination layer being referred to as the second surface. The cross-sectional direction of the thickness of the first perovskite layer refers to the direction orthogonal to the longitudinal direction, and may also be referred to as the transverse direction. When the first perovskite layer is a thin film of uniform thickness, the longitudinal and transverse directions are orthogonal, and the first and second surfaces are parallel. For example, Figure 10 is a schematic diagram of a stacked solar cell 10 according to one embodiment of the present application; it includes a first perovskite sub-cell 200, a carrier recombination layer 410, and a second perovskite sub-cell 600 stacked in sequence.

[0199] In this application, unless otherwise specified, the longitudinal direction from the first perovskite layer to the second perovskite layer is referred to as a “first direction”.

[0200] In this application, unless otherwise specified, a “concave groove” refers to a strip-shaped groove with an aspect ratio greater than 1.

[0201] In this application, unless otherwise specified, the "non-smooth surface" in the first perovskite layer refers to the presence of a non-smooth area on the surface of one side of the first perovskite layer close to the carrier recombination layer (i.e., the first surface), and the first surface in the non-smooth area has ups and downs along the thickness direction of the first perovskite layer, so that the non-smooth surface has a certain degree of roughness.

[0202] In the application, unless otherwise specified, a "concave groove" on the non-smooth surface of the first perovskite layer refers to a depression of a certain depth along the thickness of the first perovskite layer. The concave groove has a certain aspect ratio in the transverse direction, and its longitudinal projection forms a long strip-shaped profile. The length direction of the long strip-shaped profile can be recorded as the extension direction of the concave groove. Unless otherwise specified, the aspect ratio of the concave groove is greater than 1.

[0203] In the application, unless otherwise specified, a "ridge" on the non-smooth surface of the first perovskite layer refers to a protrusion of a certain height along the thickness direction of the first perovskite layer. The ridge has a certain aspect ratio in the transverse direction, and its longitudinal projection forms a long strip-shaped profile. The length direction of the long strip-shaped profile can be recorded as the extension direction of the ridge. Unless otherwise specified, the aspect ratio of the ridge is greater than 1.

[0204] Raised ridges are formed between adjacent concave grooves, and concave grooves are formed between adjacent convex ridges. The patterns formed by multiple groups of staggered concave grooves and convex ridges can be called "wrinkle patterns".

[0205] It can be understood that due to the presence of the concave grooves, there are non-smooth areas in the non-smooth surface.

[0206] By providing perovskite light-absorbing layers with different band gaps in a tandem solar cell, photons of different wavelengths can be fully absorbed, thermal relaxation losses can be reduced, and the utilization rate of incident light can be improved. A non-smooth surface comprising concave grooves and convex ridges can be provided on the surface of the first perovskite layer near the carrier recombination layer, so that this non-smooth surface forms a long concave-convex interface with the adjacent surface of the adjacent structural layer, which can be recorded as the first interface. When at least one of the following two characteristics is met: "at least a portion of the concave grooves has a different width at at least a portion of its depth" and "at least a portion of the ridges has a different width at at least a portion of its height" is met, at least a portion of the photons incident on the first interface can undergo at least one of multiple refractions and multiple reflections at the first interface. For photons directed toward the first interface, compared to the situation in which a traditional smooth interface is only reflected and / or refracted once after contacting the interface, the non-smooth first interface in the present application can increase the chance of photons contacting the first interface, thereby increasing the probability of photons being captured by the perovskite layer in the perovskite-based tandem solar cell, and increasing the efficiency of light utilization; for photons that are not absorbed by the first perovskite layer and are directed toward the first interface, the probability of the photons entering the second perovskite layer can be increased, thereby increasing the number of photons in the wavelength band that can be absorbed by the second perovskite layer; for photons that are still not absorbed by the second perovskite layer and are directed toward the first interface, the probability of entering the first perovskite layer can be increased, thereby increasing the number of photons in the wavelength band that can be absorbed by the first perovskite layer. Therefore, the overall current level of the tandem solar cell can be improved, the short-circuit current density can be improved, and in addition, it is also beneficial to improve the photoelectric conversion efficiency.

[0207] The "extension direction of the concave groove" refers to the lateral extension direction of the concave groove. The lateral extension direction of the concave groove can be determined by collecting the outer extension profile of the concave groove on the first surface of the first perovskite layer, sequentially connecting the width centers of the extension profile at different lengths, and using a line connecting the width centers of the resulting profile to characterize the extension direction of the concave groove. This line connecting the width centers of the profile can be referred to as the "extension line of the concave groove." Within the extended profile of the concave groove on the first surface, the length of the line connecting the width centers of the concave groove can be referred to as the "length of the concave groove."

[0208] On a non-smooth surface with grooves, the "average groove spacing" can be calculated by statistically analyzing the average distance between each extension line. For example, the distance between each extension line at different groove sampling locations can be statistically averaged to obtain the average spacing. The average groove spacing within a selected area can also be estimated using the following formula: A1 / L1, where A1 is the longitudinal projection area of ​​the selected non-smooth area and L1 is the sum of the lengths of the extension lines of each groove within the selected non-smooth area.

[0209] The "longitudinal cross section of the concave groove" is a cross section perpendicular to the groove's extension line and parallel to the thickness direction of the first perovskite layer. The contour line of this longitudinal cross section is an open line that opens at the top and sinks downward. The position of the longitudinal cross section contour line near the outside of the first perovskite layer is denoted as "top." The two upper endpoints of the longitudinal cross section contour line are connected to form the "opening line" of the concave groove. The length of this opening line is denoted as the "opening width of the concave groove" or "width of the concave groove." The position of the longitudinal contour line farthest from the opening line is denoted as the "bottom of the concave groove." At this bottom position, a straight line parallel to the opening line is drawn. The length of the line segment of this straight line between the longitudinal cross section contour lines is denoted as the "bottom width of the concave groove." The vertical distance between each point on the longitudinal section contour line and the opening connection line corresponds to the depth of the different contour positions of the concave groove, and the maximum vertical distance is recorded as the "depth of the concave groove"; a straight line parallel to the opening connection line is drawn at the midpoint of the maximum depth (that is, half the height), and the length of the line segment of this straight line between the longitudinal section contour lines is recorded as the "half-height width of the concave groove", and the corresponding mean can be recorded as the "half-height width of the concave groove".

[0210] The ratio of the length of the concave groove to the width of the concave groove is recorded as the "aspect ratio of the concave groove". Unless otherwise specified, the aspect ratio of the concave groove is greater than 1.

[0211] The ratio of the depth of the concave groove to the width of the concave groove is recorded as the "aspect ratio of the concave groove".

[0212] Cross-section at half-height of the concave groove The area surrounded by the concave groove outline on a cross-section perpendicular to the longitudinal direction at half-height of the concave groove is recorded as the "concave groove half-height cross-section".

[0213] The average width, average depth, average half-height width, and average length of the grooves can be obtained by performing arithmetic averaging on multi-point test values ​​of the corresponding parameters.

[0214] The "extending direction of a ridge" refers to the ridge's transverse extending direction. In the transverse direction, the ridge's extending direction can be determined by projecting the ridge longitudinally onto a plane orthogonal to the longitudinal direction, capturing the ridge's projected contour as an extended contour, and sequentially connecting the width centers of the extended contour at different lengths. The resulting line connecting the contour width centers can be used to characterize the ridge's extending direction. This line connecting the contour width centers can be referred to as the "ridge extension line." In the extended contour of the ridge located on the first surface, the length of the line connecting the contour width centers of the ridge can be referred to as the "ridge length."

[0215] On a non-smooth surface with ridges, the "average ridge spacing" can be calculated by statistically analyzing the average distance between each extension line. For example, the distance between each extension line at different ridge sampling locations can be statistically averaged to obtain the average spacing. The average ridge spacing within a selected area can also be estimated using the following formula: A1 / L2, where A1 is the projected area of ​​the selected non-smooth area along the longitudinal direction, and L2 is the sum of the lengths of the extension lines of each ridge within the selected non-smooth area.

[0216] The "longitudinal cross section of the ridge" is a cross section perpendicular to the ridge's extension line and parallel to the thickness of the first perovskite layer. The contour of this longitudinal cross section is an open line with an open bottom and a convex top. The location outside the first perovskite layer of the raw material in the longitudinal cross section contour line is denoted as the "bottom." The two bottom endpoints of the longitudinal cross section contour line are connected to form the "opening line" of the ridge. The length of this opening line is denoted as the "bottom width of the ridge" or "width of the ridge." The location of the longitudinal contour line farthest from the opening line is denoted as the "top width of the ridge." At this top location, draw a straight line parallel to the ridge opening line. The length of this straight line segment between the longitudinal cross section contour lines is denoted as the "top width of the ridge." The vertical distance between each point on the longitudinal section contour line and the opening line corresponds to the height of the different contour positions of the ridge, and the maximum vertical distance is recorded as the "height of the ridge"; a straight line parallel to the opening line is drawn at the midpoint of the maximum depth (that is, half the height), and the length of the line segment of this straight line between the longitudinal section contour lines is recorded as the "half-height width of the ridge", and the corresponding mean can be recorded as the "half-height width of the ridge".

[0217] The ratio of the length of the ridge to the width of the ridge is recorded as the "aspect ratio of the ridge". Unless otherwise specified, the aspect ratio of the ridge is greater than 1.

[0218] The ratio of the height of the ridge to the width of the ridge is recorded as the "ridge aspect ratio".

[0219] When the concave grooves and convex ridges are arranged alternately, adjacent concave grooves and convex ridges share side surfaces, and the average spacing of the convex ridges is substantially consistent with the average spacing of the concave grooves. In addition, the depth of the concave grooves is substantially consistent with the height of the convex ridges in average value.

[0220] Cross-section at half-height of the ridge The area enclosed by the ridge outline on a cross-section perpendicular to the longitudinal direction at half-height of the ridge is recorded as the "ridge half-height cross-section".

[0221] The average width, average depth, average length, average half-height width, and average aspect ratio of the ridges can be obtained by performing arithmetic averaging on multi-point test values ​​of the corresponding parameters.

[0222] In the present application, the shape parameters of the grooves and ridges on the non-smooth surface of the first perovskite layer can be tested and analyzed using methods including but not limited to the following:

[0223] (1) obtaining a topography or surface roughness curve of the non-smooth surface of the first perovskite layer by scanning electron microscopy (SEM), optical microscopy, step profiler, etc., and analyzing the following information and / or parameters in combination with image analysis software such as Image-J: including but not limited to the extended profile of the concave grooves on the non-smooth surface of the first perovskite layer, the extended line of the concave grooves, the extended direction of the concave grooves, the length of the concave grooves, the average spacing of the concave grooves, the extended profile of the ridges on the non-smooth surface of the first perovskite layer, the extended line of the ridges, the extended direction of the ridges, the length of the ridges, the average spacing of the ridges, and the projected area of ​​the non-smooth area along the longitudinal direction;

[0224] (2) obtaining a longitudinal cross-sectional view of the first perovskite layer by scanning electron microscopy (SEM), optical microscope photographs, and the like, and combining with image analysis software such as Image-J to test and analyze the following information and / or parameters: longitudinal cross-sectional view of the concave groove, contour line of the longitudinal cross-sectional view of the concave groove, line connecting the opening of the concave groove, opening width of the concave groove, width of the concave groove, bottom width of the concave groove, depth of the concave groove, half-height width of the concave groove, aspect ratio of the concave groove, depth-to-width ratio of the concave groove, half-height cross-sectional view of the concave groove, longitudinal cross-sectional view of the convex ridge, contour line of the longitudinal cross-sectional view of the convex ridge, line connecting the opening of the convex ridge, bottom width of the convex ridge, width of the convex ridge, top width of the convex ridge, height of the convex ridge, half-height width of the convex ridge, aspect ratio of the convex ridge, aspect ratio of the convex ridge, half-height cross-sectional view of the convex ridge, etc.;

[0225] (3) Parameter average values: average width of the concave groove, average half-height width of the concave groove, average depth of the concave groove, average depth-to-width ratio of the concave groove, average length of the concave groove, average length-to-width ratio of the concave groove, average half-height cross-section of the concave groove, average width of the ridge, average half-height width of the ridge, average height of the ridge, average height-to-width ratio of the ridge, average length of the ridge, average length-to-width ratio of the ridge, average half-height cross-section of the ridge, etc. can be obtained by collecting corresponding parameter values ​​at multiple locations and performing simple arithmetic average operation. The number of collection locations can be appropriately selected according to the degree of differentiation of the shapes and sizes of the concave grooves and the ridges. For example, the minimum amount of data collection can be determined by controlling the standard deviation of the average value to be less than or equal to (≤) 10% of the average value. As a non-limiting example, the width values ​​of the concave grooves at an appropriate number of locations (e.g., 20) can be collected, and the average value obtained by performing a simple arithmetic average operation can be used as the "average width of the concave grooves."

[0226] The method described in the following embodiment can be used to obtain a sample to be tested comprising a first perovskite layer. Taking SEM observation as an example, a component in which the first perovskite layer has been deposited on the first carrier transport layer but the second carrier transport layer has not yet been deposited can be selected as the sample to be tested, and the test analysis can be performed in both the longitudinal and transverse directions: (1) the observation surface is the transverse surface of the exposed side of the first perovskite layer; (2) a glass knife is used to cut the component or stacked solar cell comprising the first perovskite layer longitudinally, and the longitudinal cross section is directed upward for SEM testing; (3) a cryo-focused electron beam (FIB) is used to slice the component longitudinally, and the resulting cross section is the longitudinal cross section, and the cross section is subjected to SEM morphology observation.

[0227] It can be understood that some parameter values ​​in this application based on the statistical results of a larger sample set can be determined by random sampling statistics. For example, some parameter values ​​of grooves in the entire non-smooth surface area (average width, average half-height width, average depth, average aspect ratio, average length, etc.), some parameter values ​​of ridges (average width, average half-height width, average height, average aspect ratio, average length, etc.) and other parameters can be determined by the statistical average value of multiple randomly selected areas within the non-smooth surface.

[0228] Based on any appropriate embodiment in the present application, in some further embodiments, the average half-height width of the ridges is 1 μm to 2.5 μm, and can be optionally 1.5 μm to 2 μm.

[0229] In this application, unless otherwise specified, "surface roughness" refers to the surface unevenness resulting from the alternating arrangement of micro- and nano-scale convex and concave features. A smaller surface roughness indicates a smoother surface; a larger surface roughness indicates a more uneven surface. In the non-smooth surface of the first perovskite layer, the greater the surface roughness caused by grooves and ridges, the more uneven the non-smooth surface.

[0230] In this application, unless otherwise specified, the "surface roughness" of a non-smooth surface can be characterized by the distance between the highest and lowest points along the longitudinal direction of the surface. Generally, the concave portion between two nearest protrusions with a height difference between the highest and lowest points greater than or equal to 100 nm (≥100 nm) is referred to as a "groove," and fluctuations less than 100 nm are considered topographical variations within the groove. Unless otherwise specified, the "surface roughness" of a specified area is numerically equal to the average depth of the grooves within the specified area, or the average height of the ridges within the specified area.

[0231] The surface roughness of the selected non-smooth area can be measured using, but is not limited to, a step profiler. A stylus profilometer can be used. The test method described in the Examples section below can be used to statistically analyze the dimensions of the grooves and / or ridges based on the surface roughness curves obtained.

[0232] In some embodiments, the surface roughness is measured using a step profiler method.

[0233] The shape and size of the concave grooves (e.g., length, width, depth, aspect ratio, length-to-depth ratio, depth-to-width ratio, etc.), the distribution amount and distribution pattern of the concave grooves on the non-smooth surface of the first perovskite layer, the shape and size of the ridges (e.g., length, width, height, aspect ratio, length-to-height ratio, height-to-width ratio, etc.), the distribution amount and distribution pattern of the ridges on the non-smooth surface of the first perovskite layer, etc., can affect the surface roughness of the non-smooth surface. By controlling the surface roughness of the non-smooth region of the non-smooth surface within a relatively suitable range, the non-smooth surface can be controlled to have a relatively suitable morphology, which is conducive to more fully utilizing the light capture effect of the first interface and is more conducive to improving the comprehensive performance of short-circuit current density and photoelectric conversion efficiency.

[0234] For photons emitted from the first perovskite layer or the second perovskite layer to the first interface, generally speaking, a portion of the photons enter the adjacent structural layer after a single refraction, and a portion of the photons are reflected once and emitted back to the first perovskite layer. At this time, the concave-convex morphology at the first interface can be used to enable at least a portion of the photons to undergo at least one of the following effects: (i) multiple reflections and refractions are used to enable at least a portion of the photons to be refracted out of the first perovskite layer at the ridge interface. At this time, at least a portion of the photons that can be absorbed by the second perovskite layer (which can be recorded as second-band photons) can be captured by the second perovskite layer after a second or more reflections. (ii) utilizing the effects of secondary refraction and reflection, at least a portion of the photons can be reflected at the concave groove interface and then refracted into the first perovskite layer. At this time, at least a portion of the photons that can be absorbed by the first perovskite layer (which can be recorded as first-band photons) can be captured and absorbed by the first perovskite layer after secondary refraction. Based on the above-mentioned effects of the concave-convex morphology at the first interface, the contact opportunities between the perovskite light-absorbing layer and the photons in the stacked solar cell can be increased, the utilization rate of the incident light by the stacked solar cell can be improved, the short-circuit current density of the stacked solar cell can be increased, and in addition, it is also beneficial to improve the photoelectric conversion efficiency of the stacked solar cell.

[0235] In this application, photons that can be absorbed by the first perovskite layer are referred to as “first wavelength band photons”.

[0236] The concave-convex interface morphology of the first perovskite layer near the carrier recombination layer can be obtained by preparing the first perovskite layer using a vacuum flash evaporation process, and can also be adjusted by adjusting the vacuum flash evaporation process parameters and the composition of the perovskite material of the first perovskite layer. In some embodiments, increasing the bromine content of the perovskite material in the first perovskite layer is beneficial to promoting the formation of wrinkle lines, and is beneficial to increasing the aspect ratio of the concave grooves and the wrinkle density. During the vacuum flash evaporation process, the higher the vacuum degree and the faster the solvent removal pumping speed, the greater the aspect ratio of the concave grooves, the greater the wrinkle density formed, the smaller the spacing between the concave grooves, and the smaller the spacing between the ridges. In some embodiments, lowering the temperature of the sample during the vacuum flash evaporation process is also beneficial to promoting the formation of wrinkle lines, and is beneficial to increasing the aspect ratio of the concave grooves and the wrinkle density. Taking the process parameters of 100Pa vacuum flash evaporation for 20s as an example, in one embodiment, the average aspect ratio of the concave grooves in the wrinkle lines is 0.3, and the average spacing between the concave grooves is 15μm.

[0237] In some embodiments, the ratio of the sum of the extended lengths of the concave grooves to the sum of the extended lengths of the convex ridges is 0.9 to 1.1, and may further be 1.

[0238] Based on any suitable embodiment in the present application, in some further embodiments, the morphologies of the interfaces formed by different structural layers between the first perovskite layer and the second perovskite layer are substantially matched.

[0239] When the morphologies of the interfaces between the structural layers between the first perovskite layer and the second perovskite layer are basically consistent, each structural layer has a uniform thickness. When the morphologies of the interfaces formed by different structural layers between the first perovskite layer and the second perovskite layer are basically matched, the different structural layers have a uniform thickness. At this time, the surface of the second perovskite layer close to the first perovskite layer can form a non-smooth surface with similar morphology; corresponding to the "convex-concave" interface on the surface of the first perovskite layer, a corresponding "convex-concave" interface (which can be recorded as a second interface) can be formed on the surface of the second perovskite layer. The second interface is also beneficial to increasing the number of absorbable wavelength photons and light utilization rate in the perovskite layer in the stacked solar cell, which is beneficial to improving the overall current level of the stacked solar cell and also beneficial to improving the photoelectric conversion efficiency.

[0240] The light absorption band of the second perovskite layer is denoted as the "second band," and the interface formed between the second perovskite layer and the adjacent structural layer near the intermediate interconnect layer is denoted as the "second interface." When light in the second band passes through the first perovskite layer, some of it is reflected at the second interface. Due to the presence of the concave-convex wrinkles, the reflected light reaches the second interface again and is absorbed by the second perovskite layer, thereby increasing the second perovskite layer's absorption of light in the second band.

[0241] Figure 2 is a schematic diagram of the transmission path of incident light at a non-smooth surface of the first perovskite layer in one embodiment of the present invention. For a conventional smooth interface, the transmission path of incident light can be seen in Figure 7.

[0242] Figure 2 is a schematic diagram of the transmission path of incident light at the non-smooth surface of the first perovskite layer in one embodiment of the present application. In this embodiment, the first perovskite layer is prepared using a vacuum flash evaporation process. The structure shown in Figure 2 includes a first perovskite layer 240, an intermediate interconnect layer 400, and a second perovskite layer 640, which are stacked in sequence. The structure shown in Figure 2 can be obtained by the following method: after forming the first perovskite layer, an intermediate interconnect layer of uniform thickness is deposited by evaporation, and then a second perovskite layer is formed. In this case, a wrinkled intermediate interconnect layer with a substantially matching uneven topography and uniform thickness is formed at the interface between the two perovskite sub-cells. When photons in the second wavelength band pass through the first perovskite layer, some of the light will be reflected at the second interface, or some of the reflected light from the second electrode may be reflected at the second interface or the first interface. Due to the presence of the uneven wrinkles between the first and second perovskite layers, the reflected light can reach the second interface again and be absorbed by the second perovskite layer, thereby increasing the absorption effect of the second perovskite layer on light in the second wavelength band. In some further embodiments, the first perovskite layer has a wide bandgap, and the second perovskite layer has a narrow bandgap.

[0243] Figure 7 is a schematic diagram of the transmission path of incident light at the interface between an intermediate interconnect layer 900 with smooth interfaces on both sides and the perovskite layers 920 and 940 on both sides thereof in a comparative example of the present application. This comparative example uses an anti-solvent method to prepare the first perovskite layer. In this comparative example, the interface between the two perovskite sub-cells is a flat, smooth planar structure. Some long-wavelength incident light passes through the first perovskite and then through the intermediate interconnect layer into the second perovskite and is absorbed. However, some light will be reflected once at the interface, resulting in light loss. In some further embodiments, the first perovskite layer has a wide bandgap, and the second perovskite layer has a narrow bandgap.

[0244] The morphology of the first surface of the first perovskite layer and the morphology of the intermediate interconnect layer between the first and second perovskite layers can be observed, photographed, and analyzed using an optical microscope from the transparent electrode side, at a magnification of, for example, 200X. For example, when the first electrode is transparent, some visible light passes through the first perovskite layer, while some is reflected and exits the transparent electrode side, making optical microscopic observation possible. Alternatively, longitudinal and transverse cross-sectional morphology can be observed using focused ion beam (LIB) sectioning combined with scanning electron microscopy (SEM).

[0245] Figure 3 is an optical microscope observation of a laminated solar cell from the glass substrate side in one embodiment of the present application, wherein a transparent electrode is provided on the surface of the glass substrate near the carrier recombination layer, and distinct wrinkles can be observed. In this example, after the first perovskite layer was prepared by vacuum flash evaporation, an optical microscope observation from the side of the first perovskite layer was used, as shown in Figure 2. A distinct wrinkled surface morphology can be observed, with grooves and ridges generally evenly distributed. The width of the grooves does not vary much, and the width of the ridges is relatively stable. The observation results of Figure 3 are consistent with those of Figure 2.

[0246] FIG8 is an optical microscope observation image of a full perovskite stacked solar cell from the glass substrate side in a pair of ratios of the present application, wherein a transparent electrode is provided on the surface of the glass substrate near the carrier recombination layer, and no obvious wrinkles are observed.

[0247] Based on any suitable embodiment of the present application, in some further embodiments, an intermediate interconnection layer is provided between the first perovskite layer and the second perovskite layer; from the first perovskite layer to the second perovskite layer, the intermediate interconnection layer sequentially includes a second carrier transport layer, a carrier recombination layer, and a fourth carrier transport layer, wherein one of the second carrier transport layer and the fourth carrier transport layer is an electron transport layer, and the other is a hole transport layer;

[0248] The internal structural layers and the interfaces on both sides of the intermediate interconnection layer have basically matching concave-convex morphologies.

[0249] When the internal structural layers and the interfaces on both sides of the intermediate interconnection layer have basically matching concave and convex morphologies, the structural layers in the intermediate interconnection layer have uniform thicknesses and the interfaces are basically parallel. At this time, on the one hand, it is beneficial to give full play to the reflection and refraction effects of the concave grooves and convex ridges at the interfaces on both sides, which is beneficial to increase the number of absorbable wavelength photons and light utilization rate in the perovskite layer in the stacked solar cell, which is beneficial to improve the overall current level of the stacked solar cell and also beneficial to improve the photoelectric conversion efficiency.

[0250] Based on any suitable embodiment of the present application, in some further embodiments, the width of at least a portion of the ridges is 0.5 μm to 4 μm, optionally 1 μm to 4 μm, and further optionally 2 μm to 3.5 μm. Without limitation, the width of at least a portion of the ridges can also be selected from any of the following values, or a range consisting of any two of the following values: 0.5 μm, 0.6 μm, 0.8 μm, 1 μm, 1.2 μm, 1.5 μm, 1.6 μm, 1.8 μm, 2 μm, 2.5 μm, 3 μm, 3.5 μm, 4 μm, etc.

[0251] Based on any suitable embodiment of the present application, in some further embodiments, the half-height width of at least a portion of the ridges is 1 μm to 2.5 μm, and optionally 1.5 μm to 2 μm. Without limitation, the half-height width of at least a portion of the ridges can also be selected from any of the following values, or a range consisting of any two of the following values: 1 μm, 1.2 μm, 1.5 μm, 1.6 μm, 1.8 μm, 2 μm, 2.5 μm, etc.

[0252] Based on any suitable embodiment of the present application, in some further embodiments, the height of at least a portion of the ridges is ≥ 100 nm, and may be 100 nm to 500 nm, and further may be 100 nm to 250 nm. Without limitation, the height of the ridges may also be selected from any of the following values, or from a range consisting of any two of the following values: 100 nm, 110 nm, 120 nm, 130 nm, 140 nm, 150 nm, 160 nm, 180 nm, 200 nm, 210 nm, 220 nm, 240 nm, 250 nm, 300 nm, 350 nm, 400 nm, 450 nm, 500 nm, etc.

[0253] Based on any suitable embodiment of the present application, in some further embodiments, the average width of the ridges in at least a portion of the non-smooth surface is 0.5 μm to 4 μm, optionally 1 μm to 4 μm, and further optionally 2 μm to 3.5 μm. Without limitation, the average width of the ridges in at least a portion of the non-smooth surface can also be selected from any of the following values, or a range consisting of any two of the following values: 0.5 μm, 0.6 μm, 0.8 μm, 1 μm, 1.2 μm, 1.5 μm, 1.6 μm, 1.8 μm, 2 μm, 2.5 μm, 3 μm, 3.5 μm, 4 μm, etc.

[0254] Based on any suitable embodiment of the present application, in some further embodiments, the average half-width at half-maximum of the ridges in at least a portion of the non-smooth surface is 1 μm to 2.5 μm, and optionally 1.5 μm to 2 μm. Without limitation, the average half-width at half-maximum of the ridges in at least a portion of the non-smooth surface can also be selected from any of the following values, or a range consisting of any two of the following values: 1 μm, 1.2 μm, 1.5 μm, 1.6 μm, 1.8 μm, 2 μm, 2.5 μm, etc.

[0255] Based on any suitable embodiment of the present application, in some further embodiments, the average height of the ridges in at least a portion of the non-smooth surface is 100 nm to 500 nm, or optionally 100 nm to 250 nm. Without limitation, the average height of the ridges in at least a portion of the non-smooth surface can also be selected from any of the following values, or a range consisting of any two of the following values: 100 nm, 110 nm, 120 nm, 130 nm, 140 nm, 150 nm, 160 nm, 180 nm, 200 nm, 210 nm, 220 nm, 240 nm, 250 nm, 300 nm, 350 nm, 400 nm, 450 nm, 500 nm, etc.

[0256] Based on any suitable embodiment of the present application, in some further embodiments, the tandem solar cell satisfies one or more of the following characteristics (the reference in any of the following characteristics can also be selected from any suitable numerical value or range in the context):

[0257] The aspect ratio of at least a portion of the ridges is greater than 1. Optionally, the aspect ratio of at least a portion of the ridges is ≥ 2. Further, optionally, the aspect ratio of at least a portion of the ridges is ≥ 3. Even further, optionally, the aspect ratio of at least a portion of the ridges is ≥ 5.

[0258] The width of at least a portion of the ridges is 0.5 μm to 4 μm, optionally 1 μm to 4 μm, and further optionally 2 μm to 3.5 μm;

[0259] The half-height width of at least a portion of the ridges is 1 μm to 2.5 μm, and can be optionally 1.5 μm to 2 μm;

[0260] The height of at least a portion of the ridges is ≥100 nm, and may be 100 nm to 500 nm, and further may be 100 nm to 250 nm;

[0261] In at least a portion of the non-smooth surface, the average width of the ridges is 0.5 μm to 4 μm, optionally 1 μm to 4 μm, and further optionally 2 μm to 3.5 μm;

[0262] In at least a portion of the non-smooth surface, the average half-height width of the ridges is 1 μm to 2.5 μm, and can be optionally 1.5 μm to 2 μm;

[0263] In at least a portion of the non-smooth surface, the average height of the ridges is 100 nm to 500 nm, and can be optionally 100 nm to 250 nm;

[0264] Optionally, the longitudinal projection area of ​​at least a portion of the non-smooth surface is ≥ 0.1 mm 2 , further optional ≥0.5mm 2 , further optional ≥0.6mm2 .

[0265] In the present application, unless otherwise specified, the aforementioned “at least a portion of the ridge” may be measured in terms of the extended length of the ridge, and may mean at least 80% of the extended length, or 90% to 100% of the extended length.

[0266] In this application, unless otherwise specified, the "at least a portion of the area in the non-smooth surface" refers to the portion of the non-smooth surface corresponding to the projected area area along the longitudinal direction of which is at least a certain value. "At least a portion of the area in the non-smooth surface" can also be expressed as "the non-smooth surface area corresponding to at least a portion of the projected area of ​​the non-smooth surface along the longitudinal direction". The projected area of ​​at least a portion of the non-smooth surface along the longitudinal direction can be ≥ 0.1mm 2 , further optional ≥0.5mm 2 , further optional ≥0.6mm 2 , non-limiting example such as 960000μm 2 .

[0267] The aspect ratio, width, full width at half maximum, height of the ridges and the average values ​​of these parameters can be combined in any appropriate manner.

[0268] By adjusting one or more of the ridge width, half-width, height, and average values ​​of these parameters, the probability of photons emitted from the interior of the first perovskite layer toward the first interface after being reflected multiple times at the ridge interface of the first perovskite layer can be adjusted. By controlling one or more of these parameters within the above range, more photons are absorbed by the second perovskite layer, which helps increase the utilization rate of photons that are not absorbed after passing through the first perovskite layer. These photons may include photons in the wavelength band that can be absorbed by the second perovskite layer, thereby further improving the short-circuit current density and the photoelectric conversion efficiency of the stacked solar cell. Photons emitted from the side of the first perovskite layer toward the first interface can come from external incident light.

[0269] Based on any suitable embodiment of the present application, in some further embodiments, the width of at least a portion of the concave grooves is ≤1.2 μm, and may be 0.5 μm to 1 μm. Without limitation, the width of at least a portion of the concave grooves may also be selected from any of the following values, or less than or equal to any of the following values, or selected from a range consisting of any two of the following values: 0.5 μm, 0.6 μm, 0.8 μm, 1 μm, 1.1 μm, 1.2 μm, etc.

[0270] Based on any suitable embodiment in the present application, in some further embodiments, the average half-height width of the concave groove is ≤1 μm, and can be selected from 0.2 μm to 0.7 μm, and further can be selected from 0.3 μm to 0.55 μm. Without limitation, the average half-height width of the concave groove can also be selected from any of the following values, or from an interval consisting of any two of the following values: 0.2 μm, 0.25 μm, 0.3 μm, 0.35 μm, 0.4 μm, 0.45 μm, 0.5 μm, 0.55 μm, 0.6 μm, 0.65 μm, 0.7 μm, 0.75 μm, 0.8 μm, 0.9 μm, etc.

[0271] Based on any suitable embodiment of the present application, in some further embodiments, the depth of at least a portion of the concave grooves is ≥ 100 nm, and can be 100 nm to 500 nm, and can further be 100 nm to 250 nm. Without limitation, the depth of at least a portion of the concave grooves can also be selected from any of the following values, or from an interval consisting of any two of the following values: 100 nm, 110 nm, 120 nm, 130 nm, 140 nm, 150 nm, 160 nm, 180 nm, 200 nm, 210 nm, 220 nm, 240 nm, 250 nm, 300 nm, 350 nm, 400 nm, 450 nm, 500 nm, 600 nm, etc.

[0272] Based on any suitable embodiment in the present application, in some further embodiments, the aspect ratio of at least a portion of the concave grooves is 0.03 to 0.5, optionally 0.2 to 0.5, and further optionally 0.25 to 0.35. Without limitation, the aspect ratio of at least a portion of the concave grooves can also be selected from any of the following values, or from an interval consisting of any two of the following values: 0.03, 0.05, 0.1, 0.15, 0.2, 0.22, 0.24, 0.25, 0.26, 0.275, 0.28, 0.30, 0.32, 0.35, 0.36, 0.38, 0.40, 0.42, 0.45, 0.46, 0.48, 0.50, etc.

[0273] In the present application, unless otherwise specified, “at least a portion of the concave groove” may be measured based on the extended length of the concave groove, and may mean at least 80% of the extended length, or 90% to 100% of the extended length.

[0274] Based on any suitable embodiment of the present application, in some further embodiments, in at least a portion of the non-smooth surface, the average width of the concave grooves is 0.3 μm to 1 μm, and optionally 0.5 μm to 1 μm. Without limitation, the average width of the concave grooves can also be selected from any of the following values, or less than or equal to any of the following values ​​between 0.4 μm and 1 μm, or selected from an interval consisting of any two of the following values: 0.3 μm, 0.4 μm, 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm, 1 μm, etc.

[0275] Based on any suitable embodiment of the present application, in some further embodiments, the average half-width at half-maximum of the concave grooves in at least a portion of the non-smooth surface is 0.2 μm to 0.7 μm, and optionally 0.3 μm to 0.55 μm. Without limitation, the average half-width at half-maximum of the concave grooves in at least a portion of the non-smooth surface can also be selected from any of the following values, or a range consisting of any two of the following values: 0.2 μm, 0.3 μm, 0.4 μm, 0.5 μm, 0.6 μm, 0.7 μm, etc.

[0276] Based on any suitable embodiment of the present application, in some further embodiments, in at least a portion of the non-smooth surface, the average depth of the concave grooves is 100 nm to 500 nm, and optionally 100 nm to 250 nm. Without limitation, the average depth of the concave grooves can be selected from any of the following values, or from a range consisting of any two of the following values: 100 nm, 110 nm, 120 nm, 130 nm, 140 nm, 150 nm, 160 nm, 180 nm, 200 nm, 210 nm, 220 nm, 240 nm, 250 nm, 300 nm, 350 nm, 400 nm, 450 nm, 500 nm, etc.

[0277] Based on any suitable embodiment of the present application, in some further embodiments, in at least a portion of the non-smooth surface, the average aspect ratio of the concave groove is 0.03 to 0.5, optionally 0.2 to 0.5, and further optionally 0.25 to 0.35. Without limitation, the average aspect ratio of the concave groove can also be selected from any of the following values, or from an interval consisting of any two of the following values: 0.03, 0.05, 0.1, 0.15, 0.2, 0.22, 0.24, 0.25, 0.26, 0.275, 0.28, 0.30, 0.32, 0.35, 0.36, 0.38, 0.40, 0.42, 0.45, 0.46, 0.48, 0.50, etc.

[0278] Based on any suitable embodiment of the present application, in some further embodiments, the tandem solar cell satisfies one or more of the following characteristics (the reference in any of the following characteristics can also be selected from any suitable numerical value or range in the context):

[0279] The aspect ratio of at least a portion of the concave grooves is greater than 1, optionally, the aspect ratio of at least a portion of the concave grooves is ≥3, further optionally, the aspect ratio of at least a portion of the concave grooves is ≥5, further optionally, the aspect ratio of at least a portion of the concave grooves is ≥10, and more optionally, the aspect ratio of at least a portion of the concave grooves is ≥15;

[0280] The width of at least a portion of the concave grooves is ≤1.2 μm, and may be 0.5 μm to 1 μm;

[0281] The half-height width of at least a portion of the concave grooves is ≤1 μm, and can be optionally 0.2 μm to 0.7 μm;

[0282] The depth of at least a portion of the concave grooves is ≥100 nm, and may be 100 nm to 500 nm, and may further be 100 nm to 250 nm.

[0283] The aspect ratio of at least a portion of the concave grooves is 0.03 to 0.5, optionally 0.2 to 0.5, and further optionally 0.25 to 0.35;

[0284] In at least a portion of the non-smooth surface, the average width of the concave grooves is 0.3 μm to 1 μm, and can be 0.5 μm to 1 μm;

[0285] In at least a portion of the non-smooth surface, the average half-height width of the concave grooves is 0.2 μm to 0.7 μm, and can be optionally 0.3 μm to 0.55 μm;

[0286] In at least a portion of the non-smooth surface, the average depth of the concave grooves is 100 nm to 500 nm, and can be optionally 100 nm to 250 nm;

[0287] In at least a portion of the non-smooth surface, the average aspect ratio of the concave grooves is 0.03 to 0.5, optionally 0.2 to 0.5, and further optionally 0.25 to 0.35;

[0288] Optionally, the longitudinal projection area of ​​at least a portion of the non-smooth surface is ≥ 0.1 mm 2 , further optional ≥0.5mm 2 , further optional ≥0.6mm 2 .

[0289] The aspect ratio, width, full width at half maximum, depth, aspect ratio of the concave trench and the average values ​​of these parameters may be combined in any appropriate manner.

[0290] By adjusting one or more parameters of the concave groove width, half-height width, depth, aspect ratio, and the average value of these parameters, the probability of photons emitted from the second perovskite layer side toward the first interface entering the first perovskite layer at the concave groove interface of the first perovskite layer can be adjusted. By controlling one or more of the above parameters within the above range, the optical path length of photons that are not absorbed after reflection from the interface of the second perovskite layer is significantly increased in the first perovskite layer, and more photons can be absorbed by the first perovskite layer. These photons may include photons in the wavelength band that can be absorbed by the first perovskite layer, thereby improving light utilization efficiency, thereby better improving the overall current level and improving the photoelectric conversion efficiency of the tandem solar cell. Among them, the photons emitted from the second perovskite layer side toward the first interface can come from reflected light at the second electrode.

[0291] By comprehensively adjusting the width and length of the concave groove, the proportion of the longitudinal projection area of ​​the concave groove in the longitudinal projection area of ​​the first perovskite layer can be adjusted. The higher the proportion, the more significant the comprehensive improvement of the overall current level and photoelectric conversion efficiency by the concave groove. The longitudinal projection area of ​​the first perovskite layer can be considered to be substantially equal to the longitudinal projection area of ​​the non-smooth surface. Therefore, the proportion of the longitudinal projection area of ​​the concave groove in the longitudinal projection area of ​​the first perovskite layer is substantially equal to the percentage of the sum of the longitudinal projection areas of the concave groove relative to the longitudinal projection area of ​​the non-smooth surface.

[0292] Based on any suitable embodiment of the present application, in some further embodiments, in at least a portion of the non-smooth surface, the average spacing of the ridges is 1 μm to 20 μm, and may be 10 μm to 20 μm. Without limitation, in at least a portion of the non-smooth surface, the average spacing of the ridges may be selected from any of the following values, or a range consisting of any two of the following values: 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, 16 μm, 17 μm, 18 μm, 19 μm, 20 μm, etc.

[0293] Based on any suitable embodiment of the present application, in some further embodiments, in at least a portion of the non-smooth surface, the average spacing of the concave grooves is 1 μm to 20 μm, and can be 10 μm to 20 μm. Without limitation, in at least a portion of the non-smooth surface, the average spacing of the concave grooves can also be selected from any of the following values, or a range consisting of any two of the following values: 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, 16 μm, 17 μm, 18 μm, 19 μm, 20 μm, etc.

[0294] Based on any suitable embodiment in the present application, in some further embodiments, the half-height width of at least a portion of the convex ridges is greater than the half-height width of adjacent concave grooves.

[0295] Based on any suitable embodiment of the present application, in some further embodiments, in at least a portion of the non-smooth surface, the ratio of the average half-width at half-maximum of the ridges to the average half-width at half-maximum of the concave grooves is 1 to 6, and can further be 4 to 5. Without limitation, the ratio of the average half-width at half-maximum of the ridges to the average half-width at half-maximum of the concave grooves can also be selected from any of the following values, or from an interval consisting of any two of the following values: 1.0, 1.5, 1.6, 2, 2.5, 3, 3.5, 3.6, 4, 4.5, 5, 5.5, 6, etc.

[0296] Based on any suitable embodiment in the present application, in some further embodiments, in at least a portion of the non-smooth surface, the ratio of the sum of the half-height cross-sectional areas of the ridges to the sum of the half-height cross-sectional areas of the grooves is 1 to 36, and can further be 10 to 30. Without limitation, in at least a portion of the non-smooth surface, the ratio of the sum of the half-height cross-sectional areas of the ridges to the sum of the half-height cross-sectional areas of the grooves can be selected from any of the following values, or from an interval consisting of any two of the following values: 1, 1.1, 1.2, 1.21, 1.25, 1.3, 1.4, 1.44, 1.5, 1.56, 1.6, 1.69, 1.7, 1.8, 1.9, 1.96, 2, 2.25, 2.5, 2.56, 2.6, 2.8, 2.89, 3, 3.2, 3.24, 3.5, 3.6, 2.61, 4, 4.2, 4.4, 4.5, 4.6, 4.8, 4.84, 4.9, 5, 5.2, 5.4, 5.5, 5.6, 5.8 , 6, 6.2, 6.25, 6.4, 6.5, 6.76, 7, 7.2, 7.5, 7.6, 7.8, 7.84, 8, 8.1, 8.2, 8.4, 8.5, 9, 9.5, 9.6, 10, 10.24, 11, 11.56, 12, 12.25, 12.5, 12.6, 12.96, 13, 13. 5, 14, 14.44, 14.5, 16, 16.5, 17, 17.5, 18, 18.48, 19, 19.36, 20, 20.25, 21.26, 22, 23.04, 24, 25, 26, 28, 29.16, 30, 30.25, 31.36, 32, 33.64, 34, 35, 36, etc.

[0297] Based on any suitable embodiment in the present application, in some further embodiments, in at least a portion of the non-smooth surface, the percentage of the sum of the longitudinal projection areas of the concave grooves relative to the longitudinal projection area of ​​the non-smooth surface is 5% to 95%, optionally 5% to 90%, further optionally 5% to 70%, and further optionally 5% to 50%. Without limitation, in at least a portion of the non-smooth surface, the percentage of the sum of the projected areas of the concave grooves in the longitudinal direction relative to the projected area of ​​the non-smooth surface in the longitudinal direction can also be selected from any two of the following percentages or an interval consisting of any two percentages: 5%, 6%, 6.4%, 6.5%, 7%, 8%, 9%, 10%, 12%, 15%, 16%, 18%, 20%, 25%, 30%, 35%, 36%, 38%, 40%, 45%, 48%, 50%, 54%, 55%, 56%, 60%, 64%, 65%, 66%, 68%, 70%, 75%, 80%, 81%, 84%, 85%, 90%, 95%, etc. In at least a portion of the non-smooth surface, the percentage of the sum of the projected areas of the concave grooves along the longitudinal direction relative to the projected area of ​​the non-smooth surface along the longitudinal direction can also be selected from any of the following ranges: 10% to 95%, 10% to 90%, 10% to 70%, 10% to 50%, 15% to 95%, 15% to 90%, 15% to 70%, 15% to 50%, 20% to 95%, 20% to 90%, 20% to 70%, 20% to 50%, etc.

[0298] Based on any suitable embodiment of the present application, in some further embodiments, the tandem solar cell satisfies one or more of the following characteristics (the reference in any of the following characteristics can also be selected from any suitable numerical value or range in the context):

[0299] In at least a portion of the non-smooth surface, the average spacing of the ridges is 1 μm to 20 μm, and can be optionally 10 μm to 20 μm;

[0300] In at least a portion of the non-smooth surface, the average spacing of the grooves is 1 μm to 20 μm, and can be optionally 10 μm to 20 μm;

[0301] The half-height width of at least a portion of the ridges is greater than the half-height width of the adjacent grooves;

[0302] In at least a portion of the non-smooth surface, the ratio of the average half-height width of the ridges to the average half-height width of the grooves is 1 to 6, and can further be 4 to 5;

[0303] In at least a portion of the non-smooth surface, the ratio of the sum of the half-height cross-sectional areas of the ridges to the sum of the half-height cross-sectional areas of the grooves is 1 to 36, and may further be 10 to 30;

[0304] In at least a portion of the non-smooth surface, the percentage of the sum of the projected areas of the concave grooves along the longitudinal direction relative to the projected area of ​​the non-smooth surface along the longitudinal direction is 5% to 95%, optionally 5% to 90%, and further optionally 5% to 70%;

[0305] Optionally, the longitudinal projection area of ​​at least a portion of the non-smooth surface is ≥ 0.1 mm 2 , further optional ≥0.5mm 2 , further optional ≥0.6mm 2 .

[0306] “The percentage of the sum of the projected areas of the concave grooves along the longitudinal direction to the projected area of ​​the non-smooth surface along the longitudinal direction” may reflect the proportion of the concave grooves in the non-smooth surface.

[0307] By adjusting one or more parameters such as the average spacing of the ridges, the average spacing of the concave grooves, the ratio of the average half-height width of the ridges to the average half-height width of the concave grooves, and the ratio of the sum of the half-height cross-sectional areas of the ridges to the sum of the half-height cross-sectional areas of the concave grooves, the density of the concave grooves and / or ridges on the non-smooth surface of the first perovskite layer can be adjusted, the unevenness of the non-smooth surface can be adjusted, and thus the degree of improvement in the photoelectric conversion effect can be adjusted. By controlling one or more of these parameters within the above range, the concave-convex morphology of the first interface can be fully utilized to allow the first perovskite layer and / or the second perovskite layer to absorb more photons, which is more conducive to improving the short-circuit current density. In addition, it can also be more conducive to improving the photoelectric conversion efficiency. When external incident light is incident from the first electrode, by controlling the half-height width of at least a portion of the ridges to be greater than the half-height width of the adjacent concave grooves, it is beneficial for more photons that are not utilized by the first perovskite layer among the photons initially incident on the first interface to enter the second perovskite layer.

[0308] Based on any suitable embodiment in the present application, in some further embodiments, the opening width of at least a portion of the concave grooves is greater than the bottom width.

[0309] Based on any suitable embodiment of the present application, in some further embodiments, based on the proportion of the projected area of ​​the concave grooves along the longitudinal direction, at least 50% of the concave grooves have an opening width greater than the bottom width. Further optionally, at least 80% of the concave grooves have an opening width greater than the bottom width. Without limitation, the percentage of the sum of the projected areas of the concave grooves along the longitudinal direction that meet the "opening width greater than the bottom width" relative to the sum of the projected areas of all concave grooves on the non-smooth surface can also be selected from any of the following percentages, or greater than or equal to any of the following percentages, or selected from the interval consisting of any of the following percentages and 100%, or selected from the interval consisting of any two of the following percentages: 50%, 60%, 70%, 80%, 90%, 95%, 99%, etc. In some embodiments, 100% of the concave grooves have an opening width greater than the bottom width. The above percentage values ​​can be determined by random sampling statistics.

[0310] Based on any suitable embodiment of the present application, in further embodiments, based on the proportion of the projected area of ​​the concave grooves along the longitudinal direction, at least a portion of the concave grooves have an opening width > half-height width > bottom width; further optionally, at least 50% of the concave grooves have an opening width > half-height width > bottom width; further optionally, at least 80% of the concave grooves have an opening width > half-height width > bottom width. Without limitation, the percentage of the sum of the projected areas of the concave grooves along the longitudinal direction that satisfy "opening width > half-height width > bottom width" relative to the sum of the projected areas of all concave grooves along the longitudinal direction can also be selected from any of the following percentages, or greater than or equal to any of the following percentages, or selected from the interval consisting of any of the following percentages and 100%, or selected from the interval consisting of any two of the following percentages: 50%, 60%, 70%, 80%, 90%, 95%, 99%, etc. In some embodiments, 100% of the concave grooves have an opening width > half-height width > bottom width. The above percentage values ​​can be determined by random sampling statistics.

[0311] When the concave groove as a whole has a cross-sectional shape of "wide at the top and narrow at the bottom", at this time, the opening width of the concave groove is greater than the bottom width. Furthermore, the opening width > half-height width > bottom width, which is beneficial to increase the number of photons entering the first perovskite layer, can correspondingly increase the amount of light absorption, can better improve the short-circuit current density, and in addition, it is also beneficial to better improve the photoelectric conversion efficiency.

[0312] Based on any suitable embodiment in the present application, in some further embodiments, the bottom width of at least a portion of the ridges is greater than the top width.

[0313] Based on any suitable embodiment of the present application, in some further embodiments, based on the longitudinal projection area of ​​the ridges, at least 50% of the ridges have a base width greater than the top width. Further optionally, at least 80% of the ridges have a base width greater than the top width. Without limitation, the percentage of the sum of the longitudinal projection areas of the ridges satisfying the "base width greater than the top width" requirement relative to the sum of the projection areas of all ridges on the non-smooth surface can also be selected from any of the following percentages, or greater than or equal to any of the following percentages, or selected from an interval consisting of any of the following percentages and 100%, or selected from an interval consisting of any two of the following percentages: 50%, 60%, 70%, 80%, 90%, 95%, 99%, etc. In some embodiments, 100% of the concave grooves have an opening width greater than the base width. The above percentage values ​​can be determined by random sampling statistics.

[0314] Based on any suitable embodiment of the present application, in further embodiments, based on the proportion of the projected area of ​​the ridges along the longitudinal direction, at least a portion of the ridges have a bottom width > half-height width > top width; further optionally, at least 50% of the ridges have a bottom width > half-height width > top width; further optionally, at least 80% of the ridges have a bottom width > half-height width > top width. Without limitation, the percentage of the sum of the projected areas of the ridges along the longitudinal direction that satisfy the "bottom width > half-height width > top width" relative to the sum of the projected areas of all ridges on the non-smooth surface can also be selected from any of the following percentages, or greater than or equal to any of the following percentages, or selected from an interval consisting of any of the following percentages and 100%, or selected from an interval consisting of any two of the following percentages: 50%, 60%, 70%, 80%, 90%, 95%, 99%, etc. In some embodiments, 100% of the concave grooves have an opening width > half-height width > bottom width. The above percentage values ​​can be determined by random sampling statistics.

[0315] When the ridge as a whole has a cross-sectional shape of "narrow at the top and wide at the bottom", the bottom width of the ridge is greater than the top width. Furthermore, the bottom width > half-height width > top width, which is beneficial to increase the number of photons entering the second perovskite layer, and can correspondingly increase the amount of light absorption, which can better improve the short-circuit current density. In addition, it is also beneficial to better improve the photoelectric conversion efficiency.

[0316] Based on any suitable embodiment of the present application, in some further embodiments, the tandem solar cell satisfies one or more of the following characteristics (the reference in any of the following characteristics can also be selected from any suitable numerical value or range in the context):

[0317] At least a portion of the concave grooves have corners in their extending directions;

[0318] At least a portion of the concave grooves has a non-linear extension direction;

[0319] At least a portion of the concave grooves have intersection nodes;

[0320] At least a portion of the ridges have corners in their extension direction;

[0321] At least a portion of the ridges has a non-linear extension direction;

[0322] At least a portion of the ridges have intersection nodes;

[0323] The maximum width of at least a portion of the concave grooves within the extended length deviates by no more than 30% from the average width of the concave grooves;

[0324] The maximum width of at least a portion of the ridges over their extended length does not deviate by more than 30% from the average width of the ridges;

[0325] The extension length of at least a portion of the concave grooves is ≥50 μm;

[0326] The extension length of at least a portion of the ridges is ≥50 μm;

[0327] The aspect ratio of at least a portion of the concave grooves is ≥2, and optionally, the aspect ratio of at least a portion of the concave grooves is ≥5;

[0328] The aspect ratio of at least a portion of the concave grooves is 1 to 10, and can be 5 to 10;

[0329] The aspect ratio of at least a portion of the ridges is ≥2, and optionally, the aspect ratio of at least a portion of the ridges is ≥5;

[0330] The aspect ratio of at least a portion of the ridges is 1-20, and can be optionally 10-20.

[0331] Based on any suitable embodiment of the present application, in some further embodiments, the aspect ratio of at least a portion of the concave grooves is greater than 1. Optionally, the aspect ratio of at least a portion of the concave grooves is ≥ 2. Further optionally, the aspect ratio of at least a portion of the concave grooves is ≥ 3. Even further optionally, the aspect ratio of at least a portion of the concave grooves is ≥ 5. Without limitation, the aspect ratio of at least a portion of the concave grooves may be any of the following values, or greater than or equal to any of the following values, or selected from a range consisting of any two of the following values: 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8, 9, 10, etc. The aspect ratio of at least a portion of the concave grooves may also be any of the following ranges: greater than 1 and less than or equal to 10, 2-10, 5-10, etc. See Figure 1.

[0332] Based on any suitable embodiment of the present application, in some further embodiments, the aspect ratio of at least a portion of the ridges is greater than 1. Optionally, the aspect ratio of at least a portion of the ridges is ≥3. Further, optionally, the aspect ratio of at least a portion of the ridges is ≥5. Even further, optionally, the aspect ratio of at least a portion of the ridges is ≥10. Even more optionally, the aspect ratio of at least a portion of the ridges is ≥15. Without limitation, the aspect ratio of at least a portion of the ridges may also be any of the following values, or greater than or equal to any of the following values, or a range consisting of any two of the following values: 1.5, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, etc. The aspect ratio of at least a portion of the ridges may also be any of the following ranges: greater than 1 and less than or equal to 20, 2-20, 5-20, 10-20, etc. See Figure 1.

[0333] When at least a portion of the concave grooves have one or more of the following characteristics in the extension direction: (1) there is a corner in the extension direction of the concave groove; (2) at least a length of the extension direction of the concave groove is non-linear; and (3) there are intersection nodes in the concave grooves, in this case, the concave grooves are more likely to be randomly distributed on the non-smooth surface of the first perovskite layer, which is beneficial to shorten the transmission distance of photons in the concave grooves that contact the first interface twice continuously, which is beneficial to improve the transmission efficiency of photons, thereby helping to better improve the short-circuit current density and photoelectric conversion efficiency. Among them, the existence of intersection nodes in different concave grooves means that the extension directions of these concave grooves are not parallel or not completely parallel, so that different concave grooves are connected.

[0334] When at least a portion of the ridges have one or more of the following characteristics in their extension direction: (1) there are corners in the extension direction of the ridges; (2) at least a length in the extension direction of the ridges is non-linear; and (3) there are intersection nodes in the ridges, then the ridges are more likely to be randomly distributed on the non-smooth surface of the first perovskite layer, which is beneficial to shortening the transmission distance of photons at the ridge interface that contact the first interface twice in a row, thereby improving the transmission efficiency of photons and thus better improving the optical short-circuit current density and electrical conversion efficiency. The existence of intersection nodes in different ridges means that the extension directions of these ridges are not parallel or not completely parallel, so that different ridges are connected.

[0335] When the concave grooves and the convex ridges respectively meet at least one of the above characteristics, it is beneficial to more effectively exert the synergistic effect between the concave grooves and the convex ridges, while increasing the number of photons and the amount of light absorption in the first perovskite layer and the second perovskite layer, which can better improve the short-circuit current density. In addition, it is also beneficial to better improve the photoelectric conversion efficiency.

[0336] In the application, unless otherwise specified, when statistically analyzing the "deviation of the maximum width of the concave groove within the extended length relative to the average width of the concave groove" and the "deviation of the maximum width of the ridge within the extended length relative to the average width of the ridge", the 10% length of the sealed end portions at both ends may not be included in the statistical range of the extended length.

[0337] Based on any suitable embodiment of the present application, in some further embodiments, the tandem solar cell satisfies one or more of the following characteristics (the reference in any of the following characteristics can also be selected from any suitable numerical value or range in the context):

[0338] The angle between the extension directions of at least two adjacent concave grooves satisfies ≤30° in an extension length region of at least 30 μm;

[0339] The angle between the extension directions of at least a portion of two adjacent ridges satisfies ≤30° in an extension length region of at least 30 μm.

[0340] Based on any suitable embodiment of the present application, in some further embodiments, the tandem solar cell satisfies one or more of the following characteristics (the reference in any of the following characteristics can also be selected from any suitable numerical value or range in the context):

[0341] The angle between the extension directions of at least two adjacent concave grooves satisfies ≤15° over an extension length of at least 30 μm; optionally, the angle between the extension directions of at least two adjacent concave grooves satisfies ≤15° over an extension length of at least 50 μm; further optionally, the angle between the extension directions of at least two adjacent concave grooves satisfies ≤15° over an extension length of at least 80 μm;

[0342] The angle between the extension directions of at least two adjacent concave grooves satisfies ≤30° over an extension length of at least 50 μm; optionally, the angle between the extension directions of at least two adjacent concave grooves satisfies ≤30° over an extension length of at least 80 μm;

[0343] The angle between the extension directions of at least two adjacent ridges satisfies ≤15° over an extension length of at least 30 μm; optionally, the angle between the extension directions of at least two adjacent ridges satisfies ≤15° over an extension length of at least 50 μm; further optionally, the angle between the extension directions of at least two adjacent ridges satisfies ≤15° over an extension length of at least 80 μm;

[0344] The angle between the extension directions of at least two adjacent ridges satisfies ≤30° over an extension length of at least 50 μm; optionally, the angle between the extension directions of at least two adjacent ridges satisfies ≤30° over an extension length of at least 80 μm.

[0345] Based on any suitable embodiment in the present application, in some further embodiments, one or more of the following features are met (the reference in any of the following features can also be selected from any suitable numerical value or range in the context):

[0346] At least a portion of adjacent concave grooves and convex ridges have the same extension direction over an extension length of at least 50 μm;

[0347] At least a portion of adjacent concave grooves and convex ridges extend in the same direction over at least 60% of their adjacent lengths.

[0348] In the present application, unless otherwise specified, "the extending directions are consistent" means that the included angle does not exceed 10°, further may not exceed 5°, and further may not exceed 2°.

[0349] The regularity of the concave grooves in the non-smooth surface of the first perovskite layer can be adjusted by adjusting the angle between the extension directions of two adjacent concave grooves. The smaller the angle, the more consistent the extension directions of the two adjacent concave grooves and the better the parallelism. The longer the extension length with a relatively small angle, the higher the regularity of the concave grooves and the better the parallelism between the two adjacent concave grooves.

[0350] The regularity of the ridges on the non-smooth surface of the first perovskite layer can be adjusted by adjusting the angle between the extension directions of two adjacent ridges. The smaller the angle, the more consistent the extension directions of the two adjacent ridges, and the better the parallelism. The longer the extension length with a relatively small angle, the higher the regularity of the ridges and the better the parallelism between the two adjacent ridges.

[0351] When the concave grooves and the convex ridges respectively meet at least one of the above characteristics, the functions of the concave grooves and the convex ridges can be effectively exerted.

[0352] Based on any suitable embodiment in the present application, in some further embodiments, the band gap of the first perovskite layer is greater than the band gap of the second perovskite layer.

[0353] When the first perovskite layer is a wide-bandgap perovskite layer with a relatively wide bandgap, and the second perovskite layer is a narrow-bandgap perovskite layer with a relatively narrow bandgap, the first electrode can be a transparent electrode, the first perovskite sub-cell can be a top cell, and the second perovskite sub-cell can be a bottom cell. At this time, it is beneficial to more effectively utilize the different bandgap differences of different perovskite layers and more fully utilize the incident light.

[0354] Based on any suitable embodiment in the present application, in some further embodiments, the band gap of the first perovskite layer is 1.2 eV to 2.4 eV, optionally 1.6 eV to 2.3 eV; the band gap of the second perovskite layer is 1.0 eV to 1.4 eV.

[0355] By regulating the band gap of the perovskite layer, the wavelength range in which the perovskite layer can absorb photons can be regulated. When the band gaps of the first perovskite layer and the second perovskite layer are respectively controlled within the above ranges, it is beneficial to better broaden the absorption band of incident light. Combined with the special morphology of the first interface, the first perovskite layer and the second perovskite layer can have a higher total light absorption and light utilization rate as a whole, which can better improve the photoelectric conversion efficiency and short-circuit current density.

[0356] Based on any suitable embodiment in the present application, in some further embodiments, the first perovskite layer includes a first perovskite metal halide, and the halogen in the first perovskite metal halide includes bromine and iodine elements; optionally, the halogen in the first perovskite metal halide is a combination of bromine and iodine elements.

[0357] According to the composition design of the perovskite metal halide in the first perovskite layer, bromine and iodine elements can be set simultaneously in the perovskite precursor solution. By adjusting the atomic molar ratio of the two elements, the size-related parameters of the grooves and ridges (such as length, width, depth or height, aspect ratio or height-to-width ratio, half-height width, half-height cross-section and the average value of any of the above parameters, etc.), distribution-related parameters (average spacing, proportion of the projected area of ​​the grooves or ridges on the non-smooth surface, the ratio of the average half-height width of the ridges to the average half-height width of the grooves, the ratio of the sum of the half-height cross-section areas of the ridges to the sum of the half-height cross-section areas of the grooves) and other parameters can be controlled, thereby flexibly adjusting the enhancing effect of the concave-convex interface on the short-circuit current density and photoelectric conversion efficiency.

[0358] Based on any suitable embodiment in the present application, in some further embodiments, the second perovskite layer includes a second perovskite metal halide, and the halogen in the second perovskite metal halide includes iodine; further optionally, the halogen in the second perovskite metal halide is iodine.

[0359] In addition, by adjusting the halogen composition of the perovskite-type metal halide in the first perovskite layer and the second perovskite layer, it is also possible to adjust the band gap difference in the two light-absorbing layers and the first interface morphology, thereby broadening the absorbable band of incident light, promoting more photons to enter the perovskite layer in the stacked solar cell through the first interface, and improving the comprehensive performance of short-circuit current density and photoelectric conversion efficiency.

[0360] Based on any suitable embodiment in the present application, in some further embodiments, the atomic molar ratio of bromine element to iodine element in the first perovskite-type metal halide is (3 - y):y, where 0 < y ≤ 2; optionally, 1 ≤ y ≤ 2. Non-limiting examples of y may also include the following values: 0.3, 0.4, 0.5, 0.6, 2 / 3, 0.7, 0.75, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.8, 1.9, 2, etc., and may also be selected from the intervals formed by any two of the above values.

[0361] In some embodiments, the atomic molar ratio of bromine element to iodine element is 2:3. At this time, y is 1.8.

[0362] In some embodiments, the atomic molar ratio of bromine element to iodine element is 1:2. At this time, y is 2.

[0363] According to the composition design of the perovskite-type metal halide in the first perovskite layer, the atomic molar ratio of bromine element to iodine element in the perovskite precursor solution can be adjusted, thereby regulating the comprehensive performance of the short-circuit current density and photoelectric conversion efficiency of the tandem solar cell. By adjusting the atomic molar ratio of bromine element to iodine element in the perovskite-type metal halide in the first perovskite layer within the above range, the short-circuit current density of the tandem solar cell can be preferably increased, and it can also be used to improve the photoelectric conversion efficiency.

[0364] Non-limitingly, the chemical composition of the first perovskite-type metal halide is ABX3, where A is a monovalent cation, B is a divalent metal ion, and X is a halogen anion. Optionally, A in the first perovskite-type metal halide includes one or more of alkali metal ions, monovalent amine cations, and monovalent amidinium cations. Optionally, B in the first perovskite-type metal halide includes 2+ Be 2+ Mg 2+ Ca 2+ Sr 2+ Ba 2+ Zn 2+ Ge 2+ Fe 2+ Co 2+ and Ni 2+ one or more of them. Optionally, X in the first perovskite-type metal halide includes at least one of - Br - and I. As a non-limiting example, A in the first perovskite-type metal halide includes CH(NH2)2 + CH3NH3 + Li + Na + K+ 、Rb + and Cs + or more than one of them.

[0365] Non-limiting examples of monovalent amine cations are CH3NH3 + (methylamine, MA + ), ammonium (NH4 + ). Non-limiting examples of monovalent amidinium cations are NH2CH=NH2 + (formamidine, denoted as FA + ).

[0366] In some embodiments, A in the first perovskite metal halide includes CH(NH2)2 + , CH3NH3 + , Li + , Na + , K + , Rb + and Cs + or more than one of them.

[0367] In some embodiments, in the first perovskite metal halide, A includes CH(NH2)2 + and Cs + , B includes Pb 2+ , X includes Br - and I - , wherein the molar ratio of CH(NH2)2 + and Cs + is (1-a):a, where 0 < a < 1. Optionally, a is 0.3 to 0.9, further optionally any one of the following values, or a ratio composed of any two of the following values: 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, etc. In some of these embodiments, the molar ratio of CH(NH2)2 + and Cs + is 3:2. Further, the atomic molar ratio of bromine element and iodine element can be 2:3 or 1:2.

[0368] Non-limitingly, the chemical composition of the second perovskite metal halide is MNY3, where M is a monovalent cation, N is a divalent metal ion, and Y is a halogen anion. Optionally, M in the second perovskite metal halide includes one or more of alkali metal ions, monovalent amine cations, and monovalent amidinium cations. Optionally, N in the second perovskite metal halide includes one or more of Sn 2+ and Pb 2+ . Optionally, Y in the second perovskite metal halide includes I - .

[0369] In some embodiments, M in the second perovskite metal halide comprises CH(NH2) 2+ 、CH3NH3 + 、Li + 、Na + , K + , Rb + and Cs + One or more of .

[0370] In some embodiments, in the second perovskite metal halide, M comprises CH(NH2)2 + and CH3NH3 + , N including Pb 2+ and Sn 2+ , Y includes I - , among which CH(NH2)2 + and CH3NH3 + The molar ratio of Pb is 7:3. 2+ and Sn 2+ The molar ratio is 1:1.

[0371] Appropriate perovskite metal halide can be selected according to the performance of the perovskite film and process control requirements.

[0372] Based on any suitable embodiment in the present application, in some further embodiments, at least a portion of the perovskite grains in the first perovskite layer are through-type grains, and the two ends of the through-type grains in the longitudinal direction are respectively located on both side surfaces of the first perovskite layer.

[0373] When the perovskite grains in the first perovskite layer include through-type grains along the thickness direction of the first perovskite layer (i.e., along the longitudinal direction), it means that these perovskite grains grow continuously in the longitudinal direction, with few cracks in the longitudinal cross-section of the first perovskite layer, and appear as large-sized grains that penetrate the longitudinal direction. In this case, the through-type grains that penetrate the first perovskite layer longitudinally facilitate smoother and more efficient carrier transmission, reduce non-radiative recombination caused by grain interfaces, and improve the short-circuit current density and photoelectric conversion efficiency of the device.

[0374] In this application, unless otherwise specified, the "lateral size" of a perovskite grain in the first perovskite layer refers to the maximum size of the grain in each dimension in a transverse cross-section of the first perovskite layer. Statistical analysis can be performed based on the longitudinal and transverse cross-sectional views of the first perovskite layer. The longitudinal and transverse cross-sectional views of the first perovskite layer can be obtained using scanning electron microscopy, optical microscopy, and other methods. Based on the grain width in the longitudinal cross-sectional view, a semi-quantitative analysis of the transverse size of the grain can be performed. Quantitative statistical analysis data of the transverse size of the grain can also be obtained by analyzing longitudinal cross-sectional views at different positions and directions. Based on the transverse cross-sectional view, quantitative statistics of the transverse size of the grain can be performed.

[0375] In the present application, when performing statistical analysis on the grain size in the first perovskite layer, the amount of data collected is appropriately selected based on the shape, size, uniformity, distribution pattern, etc. of the grains. For example, the minimum amount of data collected can be determined by controlling the standard deviation of the average value to be ≤ 10% of the average value.

[0376] Based on any suitable embodiment in the present application, in some further embodiments, the lateral dimension of at least a portion of the through-type grains is ≥400 nm; wherein the lateral dimension is orthogonal to the longitudinal dimension, and the lateral dimension of the through-type grains represents the maximum dimension of the grains in all directions in the lateral cross section.

[0377] In this application, unless otherwise specified, the term "at least a portion" in "at least a portion of the through-type grains" may be measured by the number of grains, the lateral area of ​​the grains, or the volume of the grains. In terms of quantity, "at least a portion" may represent greater than or equal to any of the following percentages: 30%, 40%, 50%, 60%, 70%, 80%, 90%, 95%, 99%, etc.

[0378] Without limitation, the lateral dimension of at least a portion of the through-type grains may also be greater than or equal to any of the following sizes: 0.4 μm, 400 nm, 0.5 μm, 500 nm, 0.6 μm, 600 nm, 0.7 μm, 0.8 μm, 800 nm, 0.9 μm, 1.0 μm, 1.2 μm, etc. In some embodiments, the lateral dimension of at least a portion of the through-type grains is ≥ 0.400 nm, and may optionally be ≥ 500 nm.

[0379] Without limitation, the lateral dimension of at least a portion of the through-type grains can also be selected from any one of the following sizes or from a range consisting of any two of the following sizes: 0.4μm, 400nm, 0.5μm, 500nm, 0.6μm, 600nm, 0.7μm, 0.8μm, 800nm, 0.9μm, 1.0μm, 1.2μm, 1.4μm, 1.5μm, 1.6μm, 1.8μm, 2μm, etc.

[0380] Without limitation, the average lateral size of the through-type grains is 300 nm to 2 μm, optionally 400 nm to 1 μm, and further optionally 500 nm to 800 nm. The average lateral size of the through-type grains can also be selected from any one of the following sizes or a range consisting of any two of the following sizes: 0.3 μm, 400 nm, 0.3 μm, 400 nm, 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm, 1.0 μm, 1.2 μm, 1.4 μm, 1.5 μm, 1.6 μm, 1.8 μm, 2 μm, etc.

[0381] By controlling the lateral size of the through-type grains, the number of interfaces between perovskite grains can be adjusted. A larger lateral size results in fewer through-type seams between grains, which in turn leads to fewer defects and higher quality in the perovskite layer. By controlling the lateral size of the through-type grains within the aforementioned range, the aforementioned promoting effect of the through-type grains can be fully utilized.

[0382] Based on any suitable embodiment of the present application, in some further embodiments, within at least a portion of the width region of a longitudinal cross-section of the first perovskite layer, the area percentage of the through-type grains relative to the longitudinal cross-section is ≥80%, and optionally ≥90%. Without limitation, the area percentage of the through-type grains relative to the longitudinal cross-section can also be selected from any of the following percentages, or greater than or equal to any of the following percentages, or selected from a range consisting of any two of the following percentages: 80%, 85%, 90%, 95%, etc. Optionally, at least a portion of the width region of the longitudinal cross-section of the first perovskite layer corresponds to a width region of at least 10 μm.

[0383] By controlling the area ratio of the through-going grains in the longitudinal cross-section of the first perovskite layer, the role of the through-going grains can be adjusted. By controlling the area ratio of the through-going grains relative to the longitudinal cross-section of the first perovskite layer within the above range, the advantages of the through-going grains can be more fully utilized, further facilitating improved carrier transport and photoelectric conversion efficiency.

[0384] Based on any suitable embodiment of the present application, in some further embodiments, in a longitudinal cross-section of the first perovskite layer, the area percentage of through-type grains with a lateral dimension of 400 nm or greater relative to the longitudinal cross-section is ≥80%, and optionally ≥90%. Without limitation, the area percentage of through-type grains with a lateral dimension of 600 nm or greater relative to the longitudinal cross-section can also be selected from any of the following percentages, or greater than or equal to any of the following percentages, or selected from a range consisting of any two of the following percentages: 80%, 85%, 90%, etc.

[0385] By controlling the area ratio of larger through-type grains within the longitudinal cross-section of the first perovskite layer, the role of the through-type grains can be adjusted. By controlling the area ratio of through-type grains of a certain lateral size relative to the longitudinal cross-section of the first perovskite layer within the above range, the advantages of the through-type grains can be more fully utilized, further facilitating improvements in carrier transport and photoelectric conversion efficiency.

[0386] FIG4 is a scanning electron microscope (SEM) image of a longitudinal cross-section of a stacked solar cell in one embodiment of the present application. FIG5 is a scanning electron microscope (SEM) image of a longitudinal cross-section of a stacked solar cell in another embodiment of the present application. In the first perovskite layer, a large number of longitudinal through-type grains with large lateral dimensions can be observed, and there are few broken crystals in the first perovskite layer. In addition, in the embodiments shown in FIG4 and FIG5, the second perovskite layer is also prepared by vacuum flash evaporation. Similarly, in the second perovskite layer, a large number of longitudinal through-type grains with large lateral dimensions can be observed, and there are few broken crystals in the second perovskite layer.

[0387] Figure 9 is a scanning electron microscope (SEM) image of a longitudinal cross-section of a stacked solar cell prepared by the anti-solvent method in a comparative example of the present application. The first perovskite layer is prepared by the anti-solvent method. The surface of the first perovskite layer away from the first electrode is a flat and smooth surface, and the first electrode is a transparent electrode. In the comparative example of Figure 9, an optical microscope observation was performed on the transparent electrode layer of the stacked solar cell. No obvious wrinkles were observed between the wide-bandgap perovskite layer and the narrow-bandgap perovskite layer. In Figure 9, there are fewer longitudinal through-type grains in the first perovskite layer, more broken crystals, and the lateral size of the grains is also smaller. According to the analysis of the grain area in the longitudinal cross-section of the first perovskite layer, the longitudinal through-type grains account for less than 50% of the area of ​​the first perovskite layer in Figure 9.

[0388] In some embodiments, the thickness of the first perovskite layer may be 300 nm to 500 nm, and may further be 400 nm.

[0389] In some embodiments, the thickness of the second perovskite layer may be 300 nm to 500 nm, and further may be 400 nm.

[0390] In some embodiments, referring to FIG. 11 , the stacked solar cell 10 includes a substrate layer 100, a first perovskite sub-cell 200, a carrier recombination layer 410, and a second perovskite sub-cell 600 stacked in sequence; wherein the first perovskite sub-cell 200 includes a first electrode 220, a first carrier transport layer 230, a first perovskite layer 240, and a second carrier transport layer 250 stacked in sequence, and the second perovskite sub-cell 600 includes a third carrier transport layer 630, a second perovskite layer 640, a fourth carrier transport layer 650, and a second electrode 660 stacked in sequence; wherein the first electrode 220, the first carrier transport layer 230, the first perovskite layer 240, the second carrier transport layer 250, the carrier recombination layer 410, the third carrier transport layer 630, the second perovskite layer 640, the fourth carrier transport layer 650, and the second electrode 660 are stacked in sequence. At this time, the second carrier transport layer 250 is located between the first perovskite layer 240 and the carrier recombination layer 410, and the third carrier transport layer 630 is located between the carrier recombination layer 410 and the second perovskite layer 640. The second carrier transport layer 250, the carrier recombination layer 410, and the third carrier transport layer 630 constitute the intermediate interconnect layer 400, and the interface between the intermediate interconnect layer 400 and the first perovskite layer 240 corresponds to the aforementioned first interface. Furthermore, the second carrier transport layer and the third carrier transport layer on both sides of the carrier recombination layer are heterogeneous carrier transport layers, one being an electron transport layer and the other being a hole transport layer. Of the first and second carrier transport layers, one is an electron transport layer and the other is a hole transport layer. Of the third and fourth carrier transport layers, one is an electron transport layer and the other is a hole transport layer. Therefore, the first carrier transport layer and the third carrier transport layer are both electron transport layers or both hole transport layers, and correspondingly, the second carrier transport layer and the fourth carrier transport layer are both hole transport layers or both electron transport layers.

[0391] In some embodiments, the first carrier transport layer and the third carrier transport layer are both electron transport layers, and the second carrier transport layer and the fourth carrier transport layer are both hole transport layers.

[0392] In other embodiments, the first carrier transport layer and the third carrier transport layer are both hole transport layers, and the second carrier transport layer and the fourth carrier transport layer are both electron transport layers.

[0393] In some embodiments, a perovskite-based tandem solar cell includes a first electrode and a second electrode, one of which is a positive electrode and the other is a negative electrode. The first electrode is located at the end of the first perovskite subcell facing away from the carrier recombination layer, and the second electrode is located at the end of the second perovskite subcell facing away from the carrier recombination layer. The positive electrode can collect electron carriers transported via the electron transport layer. The negative electrode can collect hole carriers transported via the hole transport layer.

[0394] At least one of the first electrode and the second electrode is a transparent electrode for light incidence. In some embodiments, the first electrode is a transparent electrode.

[0395] In some embodiments, one of the first electrode and the second electrode is a transparent electrode, and the other is a metal electrode. In some embodiments, the first electrode is a transparent electrode, and the second electrode is a metal electrode.

[0396] Without limitation, the tandem solar cell based on tandem perovskite further comprises a substrate layer. The substrate may be disposed on the side of the first electrode facing away from the carrier recombination layer, or may be disposed on the side of the second electrode facing away from the carrier recombination layer. In some embodiments, the tandem cell comprises a substrate layer, a first perovskite sub-cell, a carrier recombination layer, and a second perovskite sub-cell disposed in sequence. In some embodiments, the tandem cell comprises a substrate layer, a first electrode, a first carrier transport layer, a first perovskite layer, a second carrier transport layer, a carrier recombination layer, a third carrier transport layer, a second perovskite layer, a fourth carrier transport layer, and a second electrode disposed in sequence. In some embodiments, a stacked cell includes a substrate layer, a first electrode, a first carrier transport layer, a first perovskite layer, an intermediate interconnect layer, a second perovskite layer, a fourth carrier transport layer, and a second electrode, arranged in sequence. The intermediate interconnect layer may include a second carrier transport layer, a carrier recombination layer, and a third carrier transport layer. The second carrier transport layer is located between the first perovskite layer and the carrier recombination layer, and the third carrier transport layer is located between the carrier recombination layer and the second perovskite layer. Furthermore, the second carrier transport layer and the third carrier transport layer on both sides of the carrier recombination layer are heterogeneous carrier transport layers, one being an electron transport layer and the other being a hole transport layer.

[0397] The substrate layer referred to in the embodiments or examples of this application may be, but is not limited to, a glass substrate or a flexible substrate. Without limitation, the flexible substrate may include one or more materials selected from polyethylene terephthalate, polyimide, polyethylene, polypropylene, polystyrene, and polyethylene naphthalate. Unless otherwise specified, the substrate layer is a transparent substrate.

[0398] In some embodiments, the base layer is a flexible base layer. Further, the base layer material may be, for example, (but not limited to) an organic polymer material, and further, may be a mixture of one or more of the following materials in different proportions: including but not limited to polyvinyl alcohol (PVA), polyester (PET), polyimide (PI), polyethylene naphthalate (PEN), polydimethylsiloxane (PDMS), etc.

[0399] Taking the first electrode as a transparent electrode, and the transparent base layer being located on the side of the first electrode away from the carrier recombination layer, that is, on the side of the first perovskite sub-cell, as an example, when the stacked solar cell based on stacked perovskite is working, part of the incident light is absorbed by the first perovskite layer, and part of the incident light passes through the first perovskite layer and the first interface and is absorbed by the second perovskite layer. After the two perovskite light-absorbing layers receive photons, the internal electrons gain energy and break free from the constraints of the light-absorbing layers to form negatively charged electron carriers, and at the same time form positively charged hole carriers, thereby obtaining electron-hole pairs. The free electrons and free holes are transmitted in opposite directions through the corresponding transport layers, causing the electrons and holes to flow. Among them, the second carrier transport layer and the third carrier transport layer on both sides of the carrier recombination layer are one electron transport layer and the other is a hole transport layer. Electrons and holes from both sides of the carrier recombination layer recombine in the carrier recombination layer, so that the first perovskite sub-cell and the second perovskite sub-cell are connected in series, thereby forming an electric current in the stacked solar cell and realizing the conversion of light energy into electrical energy.

[0400] When the first carrier transport layer and the third carrier transport layer are both electron transport layers, and the second carrier transport layer and the fourth carrier transport layer are both hole transport layers, free electrons are collected by the first electrode through the first carrier transport layer, and free holes are collected by the second electrode through the fourth carrier transport layer, thereby forming an optical circuit in the stacked solar cell.

[0401] The electron transport layer can extract and transport electron carriers and block the passage of free holes.

[0402] The hole transport layer can extract and transport hole carriers and block the passage of free electrons.

[0403] In some embodiments, the material of the transparent electrode may be exemplified by, but not limited to, one or more of the following materials: FTO (fluorine-doped tin oxide), ITO (tin-doped indium oxide), AZO (aluminum-doped zinc oxide), BZO (boron-doped zinc oxide), IZO (indium zinc oxide), IWO (tungsten-doped indium oxide), etc.

[0404] In some embodiments, the transparent electrode primarily includes a transparent conductive material, which may include a transparent conductive oxide. Without limitation, the transparent conductive oxide in the transparent electrode may include one or more of indium tin oxide, fluorine-doped tin oxide, indium-doped tungsten oxide, indium-doped zinc oxide, and aluminum-doped zinc oxide.

[0405] In some embodiments, the metal electrode mainly includes a metal material, and the metal material may include one or more of gold, silver, copper, aluminum, nickel, chromium, bismuth, platinum, magnesium, molybdenum, tungsten, etc.

[0406] In this application, when referring to a component as "mainly comprising one or more of substances a1, a2, ..., etc.", unless otherwise specified, "mainly comprising" means a weight percentage of at least 80%, and may also be ≥90%, ≥95%, ≥98%, etc., or 100%. When the weight percentage is 100%, "mainly comprising one or more of substances a1, a2, ..., etc." means that the component is composed of one or more of substances a1, a2, ..., etc.

[0407] In some embodiments, the electron transport material in the electron transport layer of the first perovskite subcell (which may be referred to as the first electron transport material) includes an N-type semiconductor. The first electron transport material may include, but is not limited to, one or more of the following materials: bathocuproine, [6,6]-phenyl-C 61 -Isomethyl butyrate, [6,6]-phenyl C 71 -Methyl butyrate, C 60 、C 70 , tin oxide (SnO x , the value of x can range from 1.5 to 2), zinc oxide and its derivatives, and modified products of any of the above materials after doping or passivation.

[0408] In some embodiments, the hole transport material in the hole transport layer of the first perovskite subcell (which may be referred to as the first hole transport material) comprises a P-type semiconductor. The first hole transport material may include, but is not limited to, one or more of the following materials: phosphocarbazole-based materials (a non-limiting example of phosphocarbazole-based materials is [4-(3,6-dimethoxy-9H-carbazole-9-yl)butyl]phosphonic acid (MeO-4PACz)), poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine], poly-3-hexylthiophene, triphenylamine with a triptycene core, 3,4-ethylenedioxythiophene-methoxytriphenylamine, N-(4-phenylamino)carbazole-spirobifluorene, poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid) (PEDOT:PSS), polythiophene, nickel oxide, molybdenum oxide, cuprous iodide, cuprous oxide, and derivatives thereof, as well as doped or passivated modifications of any of the foregoing materials.

[0409] Without limitation, the material of the carrier recombination layer may include at least one of a transparent conductive oxide and a metal. Without limitation, the transparent conductive oxide in the carrier recombination layer may include one or more of indium tin oxide, fluorine-doped tin oxide, indium-doped tungsten oxide, indium-doped zinc oxide, and aluminum-doped zinc oxide. The metal in the carrier recombination layer may include one or more of gold, silver, copper, aluminum, nickel, chromium, bismuth, platinum, magnesium, molybdenum, tungsten, and the like.

[0410] In some embodiments, the electron transport material in the electron transport layer of the second perovskite subcell (which may be referred to as the second electron transport material) includes an N-type semiconductor. The second electron transport material may include, but is not limited to, one or more of the following materials: bathocuproine, [6,6]-phenyl-C 61 -Isomethyl butyrate, [6,6]-phenyl C 71 -Methyl butyrate, C 60 、C 70 , tin oxide (SnO x , the value of x can range from 1.5 to 2), zinc oxide and its derivatives, and modified products of any of the above materials after doping or passivation.

[0411] In some embodiments, the hole transport material (referred to as the second hole transport material) in the hole transport layer of the second perovskite subcell comprises a P-type semiconductor. The second hole transport material may include, but is not limited to, one or more of the following materials: phosphocarbazole-based materials (a non-limiting example of phosphocarbazole-based materials is [4-(3,6-dimethoxy-9H-carbazole-9-yl)butyl]phosphonic acid), poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine], poly-3-hexylthiophene, triphenylamine with a triptycene core, 3,4-ethylenedioxythiophene-methoxytriphenylamine, N-(4-phenylamino)carbazole-spirobifluorene, poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid) (PEDOT:PSS), polythiophene, nickel oxide, molybdenum oxide, cuprous iodide, cuprous oxide, and derivatives thereof, as well as doped or passivated modifications of any of the foregoing materials.

[0412] Based on any suitable embodiment in the present application, in some further embodiments, a heterogeneous carrier blocking layer is provided on at least one side of one or more carrier transport layers among the first carrier transport layer, the second carrier transport layer, the third carrier transport layer and the fourth carrier transport layer.

[0413] In some embodiments, referring to FIG12 , the stacked solar cell 10 includes a substrate layer 100, a first perovskite sub-cell 200, a carrier recombination layer 410, and a second perovskite sub-cell 600 stacked in sequence; wherein the first perovskite sub-cell 200 includes a first electrode 220, a first carrier transport layer 230, a first perovskite layer 240, and a second carrier transport layer 250 stacked in sequence, and the second perovskite sub-cell 600 includes a third carrier transport layer 630, a second perovskite layer 640, a fourth carrier transport layer 650, and a second electrode 660 stacked in sequence; wherein the first electrode 220, the first carrier transport layer 230, the first perovskite layer 240, and the second carrier transport layer 250 stacked in sequence. The transport layer 230, the first perovskite layer 240, the second carrier transport layer 250, the carrier recombination layer 410, the third carrier transport layer 630, the second perovskite layer 640, the fourth carrier transport layer 650, and the second electrode 660 are stacked in sequence. The fourth carrier transport layer and the second carrier transport layer are both electron transport layers, and the third carrier transport layer and the first carrier transport layer are both hole transport layers. The fourth carrier transport layer 650 includes a second hole blocking layer 6501 on the side close to the second perovskite layer 640, and the second carrier transport layer 250 includes a first hole blocking layer 2501 on the side close to the first perovskite layer 240. The second carrier transport layer 250, the carrier recombination layer 410, and the third carrier transport layer 630 constitute the intermediate interconnect layer 400. The interface between the intermediate interconnect layer 400 and the first perovskite layer 240 corresponds to the aforementioned first interface.

[0414] Based on any suitable embodiment of the present application, in some further embodiments, any one of the first carrier transport layer, the second carrier transport layer, the third carrier transport layer, and the fourth carrier transport layer may be independently provided with a different carrier blocking layer. In some of these embodiments, any of the aforementioned transport layers may be independently provided on at least one side of the transport layer.

[0415] Based on any suitable embodiment of the present application, in some further embodiments, the tandem solar cell satisfies one or more of the following characteristics (the reference in any of the following characteristics can also be selected from any suitable numerical value or range in the context):

[0416] The first carrier transport layer and the third carrier transport layer are both electron transport layers, and the second carrier transport layer and the fourth carrier transport layer are both hole transport layers, or the first carrier transport layer and the third carrier transport layer are both hole transport layers, and the second carrier transport layer and the fourth carrier transport layer are both electron transport layers;

[0417] The tandem solar cell further includes a first electrode and a second electrode, wherein the first electrode is located on a side of the first perovskite subcell away from the carrier recombination layer, and the second electrode is located on a side of the second perovskite subcell away from the carrier recombination layer; the first electrode is a transparent electrode;

[0418] At least one side of the first carrier transport layer includes a foreign carrier blocking layer;

[0419] At least one side of the second carrier transport layer includes a foreign carrier blocking layer;

[0420] At least one side of the third carrier transport layer includes a foreign carrier blocking layer;

[0421] At least one side of the fourth carrier transport layer includes a foreign carrier blocking layer.

[0422] The first perovskite sub-cell and the second perovskite sub-cell may both be nip-type or both be pin-type.

[0423] When the first electrode is a transparent electrode, the incident light entering the stacked solar cell can enter from the first electrode side. At this time, when the incident light is first emitted from the first perovskite layer side to the first interface, the first interface is conducive to achieving the aforementioned effect of improving the comprehensive performance of short-circuit current density and photoelectric conversion efficiency.

[0424] In addition, a heterogeneous carrier blocking layer may be provided on at least one side of one or more of the first carrier transport layer, the second carrier transport layer, the third carrier transport layer, and the fourth carrier transport layer to block the transport of heterogeneous carriers, thereby facilitating the reduction of the recombination probability of electrons and holes.

[0425] In some embodiments, the hole blocking layer in the first perovskite subcell (which may be referred to as the first hole blocking layer) is composed of materials including fullerene and its derivatives, SnO x One or more of, wherein the value of x ranges from 1.5 to 2. Non-limiting examples of fullerenes may include one or more of C60, C61, C70, and the like.

[0426] In some embodiments, the hole blocking layer in the second perovskite subcell (which may be referred to as the second hole blocking layer) is composed of materials including fullerene and its derivatives, SnO x One or more of, wherein the value of x ranges from 1.5 to 2. Non-limiting examples of fullerenes may include one or more of C60, C61, C70, and the like.

[0427] In some embodiments, the thickness of the electron transport layer may be 20 nm.

[0428] In some embodiments, when the respective blocking layers are present, the thickness of the first hole blocking layer and the second hole blocking layer are each independently 10 nm.

[0429] In some embodiments, the hole transport layer may have a thickness of 20 nm.

[0430] Based on any suitable embodiment in the present application, in some further embodiments, the first perovskite sub-cell and the second perovskite sub-cell form a two-terminal integrated structure.

[0431] Based on any suitable embodiment in the present application, in some further embodiments, the tandem solar cell is a two-terminal tandem solar cell.

[0432] Based on any suitable embodiment in the present application, in some further embodiments, the tandem solar cell is an all-perovskite tandem solar cell.

[0433] In a tandem solar cell including a perovskite layer, taking a full perovskite tandem solar cell in which the first perovskite subcell is a wide bandgap perovskite subcell and the second perovskite subcell is a narrow bandgap perovskite subcell as an example, the conventional preparation method is to first use a solvent method to prepare a wide bandgap perovskite layer on the carrier transport layer, and then deposit the functional layers and narrow bandgap perovskite layers of the intermediate interconnect layer layer by layer, wherein the solvent in the functional layers other than the perovskite layer (such as the carrier transport layer) is usually removed by a thermal evaporation method, which requires multiple high-temperature processes. The accumulation of these high-temperature processes is equivalent to annealing the wide bandgap perovskite layer in the bottom cell, which easily leads to a decrease in the photoelectric conversion efficiency of the bottom wide bandgap perovskite subcell. In some embodiments, the third carrier transport layer is prepared by a vacuum flash evaporation process, and the high-temperature treatment process of the first perovskite layer is beneficial to reducing the effect of the subsequent process on the efficiency attenuation of the first perovskite layer subcell. In some further embodiments, both the third carrier layer and the second perovskite layer are prepared by a vacuum flash evaporation process.

[0434] In this application, unless otherwise specified, any perovskite layer in a perovskite-based tandem solar cell can be disassembled in the following manner and the surface of the perovskite layer can be tested and analyzed: Taking the electron transport layer as C60 / BCP, and the second electrode located on the surface of the electron transport layer away from the light absorbing layer and being a Cu electrode as an example, the tandem solar cell can be disassembled, the first electrode and the second electrode (such as the Cu electrode) can be removed, and the electron transport layer (such as C60 / BCP) can be washed away with the antisolvent of the corresponding perovskite layer (such as chlorobenzene). The second electrode can be removed by, for example, removing it with tape.

[0435] It is understood that the structure of the perovskite subcell involved in this application may not be limited to the structural layers listed above. Other functional layers, such as buffer layers and insertion layers, may also be introduced as needed. In some embodiments, the perovskite subcell may be provided with a buffer layer of suitable energy level, which may play one or more roles in reducing energy level barriers, promoting energy level matching, improving carrier extraction efficiency, passivating interface defect states, protecting the light absorption layer, inhibiting water molecules and oxygen from oxidative decomposition of the battery, improving photoelectric conversion efficiency, and improving the stability of the perovskite subcell and the tandem solar cell. Depending on the location of the buffer layer, the types of buffer layers may include four types: a buffer layer between the hole transport layer and the anode, a buffer layer between the electron transport layer and the cathode, a buffer layer between the hole transport layer and the absorption layer, and a buffer layer between the electron transport layer and the absorption layer. Materials that can be used for the buffer layer in the tandem solar cell may include, but are not limited to: Cu2O, NiO, AZO, TiO2, etc. In some embodiments, an insertion layer may be provided between the electron transport layer and the adjacent electrode. An example of the material of the insertion layer is bathocuproin (BCP).

[0436] In a second aspect of the present application, a method for preparing a perovskite-based tandem solar cell as described in the first aspect of the present application is provided, comprising the following steps: sequentially stacking a first carrier transport layer, a first perovskite layer, a second carrier transport layer, a carrier recombination layer, a third carrier transport layer, a second perovskite layer, a fourth carrier transport layer, and a second electrode on a surface of one side of a first electrode to prepare a perovskite-based tandem solar cell;

[0437] The method of stacking the first perovskite layer on the side of the first carrier transport layer facing away from the first electrode comprises the following steps:

[0438] Applying a precursor solution I of the first perovskite layer to a surface of the first carrier transport layer facing away from the first electrode to form a coating layer I;

[0439] The coating layer I is subjected to a vacuum flash evaporation treatment and an annealing treatment to form a first perovskite layer, and a non-smooth surface is formed on a side of the first perovskite layer facing away from the first electrode.

[0440] By preparing the first perovskite layer through a vacuum flash evaporation process, the aforementioned concave grooves and convex ridges can be formed on the surface of the first perovskite layer near the carrier recombination layer. This increases the amount of photons contacting the perovskite layer and the light utilization rate, thereby improving the short-circuit current density of the tandem solar cell and the photoelectric conversion efficiency. Furthermore, it can promote the formation of large-sized through-type grains, thereby enhancing carrier transport and photoelectric conversion efficiency.

[0441] Principle of preparing perovskite layer by vacuum flash evaporation treatment: After the wet film of perovskite is spin-coated and placed in a vacuum flash evaporation device, the atmosphere in the device is evacuated by a vacuum pump, making the internal air pressure much lower than the atmospheric pressure, thereby reducing the saturated vapor pressure of the solvent in the perovskite wet film. Within a few seconds, the boiling point of the solvent in the perovskite wet film will be reduced below room temperature, and then it will evaporate from the wet film and be continuously evacuated, so as to achieve the effect of removing the solvent and rapidly crystallizing.

[0442] Non-restrictively, the precursor solution of any perovskite layer can be prepared by the following method: Prepare the perovskite precursor materials according to the stoichiometric ratio of perovskite-type metal halides in the perovskite layer, dissolve the perovskite precursor materials in a solvent to form a mixed solution, stir for 1 h, and filter with a 0.22 μm organic filter membrane to obtain the perovskite precursor solution. In this application, unless otherwise specified, the perovskite precursor solution is the perovskite precursor solution.

[0443] Taking the precursor solution of the first perovskite layer as an example, taking the perovskite-type metal halide as Cs a FA 1-a PbI 3-y Br y (0 < a < 1, 0 < y ≤ 1.2) as an example, the perovskite precursor materials can be a combination of lead iodide, lead bromide, formamidinium bromide, formamidinium iodide, cesium iodide and cesium bromide, and the active substance of the perovskite absorption layer is the CsFA system.

[0444] Non-restrictively, in the process of preparing the first perovskite layer, the preparation method of the perovskite-based tandem solar cell can further meet one or more of the following characteristics:

[0445] The vacuum flash evaporation treatment is carried out under negative pressure conditions. Optionally, the negative pressure condition is ≤ 100 Pa, and further optionally 50 Pa - 100 Pa;

[0446] The temperature for the vacuum flash evaporation treatment is -10 °C - 100 °C, optionally 0 °C - 30 °C, and further optionally 20 °C - 30 °C;

[0447] The duration of the vacuum flash evaporation treatment is 10 s - 100 s, optionally 10 s - 30 s, and further optionally 15 s - 25 s;

[0448] The annealing treatment is carried out by a hot stage method. Optionally, a 30 °C - 200 °C hot stage is used, further optionally a 90 °C - 110 °C hot stage, and even more optionally a 98 °C - 102 °C hot stage;

[0449] The annealing duration for the annealing treatment is 30 s - 60 min, optionally 5 min - 20 min, and further optionally 14 min - 16 min.

[0450] Based on any suitable embodiment of the present application, in some further embodiments, the step of coating the precursor solution I of the first perovskite layer onto the surface of the first carrier transport layer facing away from the first electrode includes:

[0451] Spin coating a portion of the precursor solution I onto a surface of the first carrier transport layer facing away from the first electrode at a first rotation speed;

[0452] Accelerating the rotation speed from the first rotation speed to the second rotation speed, and continuing to spin-coat another portion of the precursor liquid I at the second rotation speed;

[0453] The second rotational speed is greater than the first rotational speed.

[0454] Based on any suitable embodiment of the present application, in some further embodiments, during the process of preparing the first perovskite layer, the method for preparing a perovskite-based tandem solar cell satisfies one or more of the following characteristics (the reference in any of the following characteristics can also be selected from any suitable numerical value or range in the context):

[0455] The first rotation speed is 1000 rpm to 6000 rpm, and can be optionally 1000 rpm to 2000 rpm; the spin coating is performed at the first rotation speed for 8 s to 12 s;

[0456] In the step of accelerating the rotational speed from the first rotational speed to the second rotational speed, the acceleration is 200 rpm / s to 2000 rpm / s, and can be optionally 800 rpm / s to 1200 rpm / s;

[0457] The second rotation speed is 3000 rpm to 4500 rpm, and can be optionally 3800 rpm to 4200 rpm; the spin coating is performed at the second rotation speed for 18 s to 22 s.

[0458] By adjusting one or more parameters in the preparation process of the first perovskite layer and regulating the surface morphology and / or grain size of the first perovskite layer as needed, the comprehensive performance of the short-circuit current density and photoelectric conversion efficiency of the stacked solar cell can be better improved through process parameter optimization.

[0459] In some embodiments, the second perovskite layer is also prepared by vacuum flash evaporation, comprising the following steps: applying a precursor solution II of the second perovskite layer to a surface of the third carrier transport layer facing away from the carrier recombination layer to form a coating layer II; performing a vacuum flash evaporation on the coating layer II; and performing an annealing treatment to form the second perovskite layer. The vacuum flash evaporation treatment of the coating layer II and the annealing treatment parameters can be found in the description of the coating layer I.

[0460] The vacuum flash evaporation process, used to prepare the second perovskite layer, can form similar concave grooves and convex ridges on the surface of the second perovskite layer facing away from the carrier recombination layer. This increases the chances of light secondary incident on the second perovskite layer, increasing light utilization, improving the photoelectric conversion efficiency of the tandem solar cell, and also improving the short-circuit current density. Furthermore, it can promote the formation of large-sized through-type grains, improving carrier transport and photoelectric conversion efficiency.

[0461] Each structural layer other than the perovskite layer in the tandem solar cell can be prepared by one or more of the following methods, including but not limited to: chemical bath deposition, electrochemical deposition, chemical vapor deposition, thermal evaporation co-evaporation, atomic layer deposition, magnetron sputtering, precursor liquid spin coating, precursor liquid slit coating, precursor liquid doctor blade coating, mechanical pressing, etc. An appropriate method can be selected based on the material properties of each structural layer to be stacked with the adjacent structural layer. In some embodiments, each structural layer other than the perovskite layer in the tandem solar cell can be prepared by one or more of the following methods, including but not limited to: thermal evaporation, precursor liquid coating, etc., wherein the precursor liquid coating method can be a precursor liquid spin coating method.

[0462] Without limitation, the second perovskite layer may be prepared using vacuum flash evaporation process parameters similar to those used to prepare the first perovskite layer.

[0463] Based on any suitable embodiment of the present application, in some further embodiments, the precursor liquid II is subjected to vacuum flash evaporation treatment, and the annealing includes: vacuum flash evaporation treatment of the precursor liquid II under negative pressure conditions, and then annealing treatment under heating conditions;

[0464] Without limitation, during the preparation of the second perovskite layer, the method for preparing a perovskite-based tandem solar cell may further satisfy one or more of the following characteristics (the reference in any of the following characteristics may also be selected from any appropriate numerical value or range in the context):

[0465] Negative pressure condition is less than or equal to 100Pa (≤100Pa), and can be selected as 50Pa~100Pa;

[0466] The temperature of the vacuum flash treatment is -10°C to 100°C, optionally 0°C to 30°C, and further optionally 20°C to 30°C;

[0467] The time of the vacuum flash evaporation treatment is 10s to 100s, optionally 10s to 30s, and further optionally 15s to 25s;

[0468] The heating condition adopts a 30°C to 200°C hot plate, optionally a 90°C to 110°C hot plate, and further optionally, a 98°C to 102°C hot plate;

[0469] The annealing time of the annealing treatment is 30 seconds to 60 minutes, optionally 5 minutes to 20 minutes, and further optionally 8 minutes to 12 minutes.

[0470] Based on any suitable embodiment of the present application, in some further embodiments, the step of coating the precursor solution II of the second perovskite layer onto the surface of the third carrier transport layer facing away from the carrier recombination layer includes:

[0471] Spin coating a portion of the precursor solution II at a third rotation speed onto a surface of the third carrier transport layer facing away from the carrier recombination layer;

[0472] accelerating the rotation speed from the third rotation speed to the fourth rotation speed, and continuing to spin-coat another portion of the precursor liquid II at the fourth rotation speed;

[0473] The fourth speed is greater than the third speed.

[0474] Based on any suitable embodiment of the present application, in some further embodiments, during the preparation of the first perovskite layer, the method for preparing a perovskite-based tandem solar cell satisfies one or more of the following characteristics (the reference in any of the following characteristics can also be selected from any suitable numerical value or range in the context):

[0475] The third speed is 1000 rpm to 6000 rpm, and can be optionally 1000 rpm to 2000 rpm; the spin coating is performed at the third speed for 8 s to 12 s;

[0476] In the step of accelerating the rotational speed from the third rotational speed to the fourth rotational speed, the acceleration is 200 rpm / s to 2000 rpm / s, and can be optionally 800 rpm / s to 1200 rpm / s;

[0477] The fourth rotation speed is 3000 rpm to 4500 rpm, and can be optionally 3800 rpm to 4200 rpm; the spin coating is performed for 18 s to 22 s at the fourth rotation speed.

[0478] In some embodiments, for example, where the base layer is located on the side of the first perovskite subcell facing away from the carrier recombination layer, and where each structural layer is fabricated layer by layer on a first substrate comprising the base layer and the first electrode, one or more of the structural layers from the first perovskite layer to the second electrode in the tandem solar cell are fabricated using a vacuum flash evaporation method. In this case, after the non-smooth surface of the first perovskite layer facing away from the first electrode is formed, the thermal evaporation process is reduced, thereby reducing the adverse effects of conventional thermal annealing processes on the photoelectric conversion efficiency of the first perovskite layer.

[0479] In some embodiments, other structural layers in the stacked solar cell, except for the structural layers prepared by the vacuum flash evaporation process, can be prepared by evaporation. For example, the first electrode and the first carrier transport layer can both be prepared by the evaporation process.

[0480] In the third aspect of the present application, an electrical device is provided, which includes at least one of the perovskite-based tandem solar cells described in the first aspect of the present application and the perovskite-based tandem solar cell prepared by the preparation method of the perovskite-based tandem solar cell described in the second aspect of the present application.

[0481] In some embodiments, the tandem solar cell can be used as a power generation device in an electrical device. The type of power generation device can include, but is not limited to, an integrated power generation device. The location of the power generation device can include, but is not limited to, the roof or back panel of a vehicle.

[0482] Furthermore, the above-mentioned electrical devices may include mobile devices, such as mobile phones, laptop computers, etc., electric vehicles, electric trains, ships and satellites, power generation systems, etc., but are not limited thereto.

[0483] Figure 13 shows an example of an electric device 6. The electric device 6 is a car, and can further be a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle.

[0484] As another example, the electric device may be a mobile phone, a tablet computer, a laptop computer, a calculator, etc.

[0485] As another example, the power-consuming device may be a wearable device, such as a watch.

[0486] Below, some embodiments of the present application are described. The embodiment described below is exemplary, is only used to explain the present application, and cannot be construed as limiting the present application. In the embodiment, if no technology or conditions are indicated, it is carried out according to the description above, or according to the technology or conditions described in the document in this area or according to the product specification. Reagents used or instruments that are not indicated by the manufacturer are conventional products that can be obtained commercially, or can be synthesized in a conventional manner by commercially available products.

[0487] In the following examples, room temperature refers to 20°C to 30°C.

[0488] The fabrication method for a perovskite-based tandem solar cell involves using a vacuum flash evaporation method to prepare the first and second perovskite layers. Both perovskite sub-cells are inverted pin (PIN) configurations. The first perovskite layer is a wide-bandgap perovskite layer with a bandgap of 1.2eV to 2.4eV, and also 1.6eV to 2.3eV. The second perovskite layer is a narrow-bandgap perovskite layer with a bandgap of 1.0eV to 1.4eV.

[0489] S10. Clean the glass on which the transparent conductive film ITO has been deposited using acetone, alcohol, and deionized water, sequentially, to obtain the first electrode. Dry the glass substrate and prepare it for the next step. The base layer is a glass substrate, and the ITO layer serves as the first electrode. The first electrode has a length × width × height of 20 mm × 15 mm × 200 mm.

[0490] S20. Spin-coat the ethanol solution of MeO-4PACz onto the surface of the first electrode of the first substrate at a spin-coating speed of 4000 rpm and a spin-coating time of 30 s; then transfer the solution to a hot plate and anneal at 100°C for 10 min to form a hole transport layer (first carrier transport layer) with a thickness of 1 nm on the surface of the first electrode.

[0491] Wherein, MeO-4PACz is [4-(3,6-dimethoxy-9H-carbazol-9-yl)butyl]phosphonic acid, and the ethanol solution of MeO-4PACz is prepared by the following method: 0.3 mg of MeO-4PACz is added to 1 mL of ethanol and stirred evenly.

[0492] S30, 85 μL of the first perovskite precursor solution is added dropwise to the surface of the hole transport layer formed in step S20 at a speed of 1000 rpm to 2000 rpm, rotated for 10 seconds, and then increased to 4000 rpm with an acceleration of 1000 rpm / s. After spin coating at a speed of 4000 rpm for 20 seconds, it is transferred to a vacuum flash chamber, and the pressure in the chamber is pumped to below 100 Pa (room temperature, about 60 Pa) with a vacuum pump, and then maintained for 20 seconds. After the vacuum flash treatment is completed, the multilayer film is annealed on a hot stage at 100°C for 15 minutes to form a first perovskite layer, also recorded as a wide band gap perovskite layer, with a thickness of about 400 nm.

[0493] Among them, the precursor solution of the first perovskite layer is also recorded as a wide bandgap perovskite precursor solution or a first perovskite precursor solution, and is prepared by the following method: the perovskite precursor material is added to 1 mL of a mixed solvent of dimethylformamide (DMF) and dimethyl sulfoxide (DMSO) with a volume ratio of 3:1, stirred at a speed of 600 rpm on a magnetic stirrer for 2 hours, and filtered for use.

[0494] Taking Example 1 as an example, the precursor solution of the first perovskite layer is prepared by the following method: 123 mg FAI (formamidine iodide), 59 mg FABr (formamidine bromide), 46 mg CsI (cesium iodide), 25 mg CsBr (cesium bromide), 428 mg PbI2 (lead iodide) and 209 mg PbBr2 (lead bromide) of the perovskite precursor material are added to 1 mL of a mixed solvent of dimethylformamide (DMF) and dimethyl sulfoxide (DMSO) with a volume ratio of 3:1, stirred at 600 rpm on a magnetic stirrer for 2 hours, filtered and set aside. The chemical formula of the corresponding perovskite material is Cs a FA 1-a PbI 3-y Br y , where a is 0.4 and y is 2.

[0495] S40 , vapor-depositing a 20 nm thick layer of C60 on the wide bandgap perovskite layer prepared in step S30 to form a C60 film layer as an electron transport layer (second carrier transport layer).

[0496] S50, using ALD equipment (atomic layer deposition equipment) to prepare a 20nm SnO layer on the C60 film layer prepared in step S40 by atomic layer deposition process x (1.5≤x≤2), as the first hole blocking layer. In this example, the second carrier transport layer is composed of a 20nm thick C60 film layer and a 20nm thick SnO film prepared in steps S40 and S50. x (1.5≤x≤2) film layer composition.

[0497] S60, SnO prepared in step S50 x Au with a thickness of about 1 nm is evaporated on the film layer as a carrier recombination layer.

[0498] S70. Spin-coat a solution of poly(3,4-ethylenedioxythiophene):polystyrenesulfonic acid (PEDOT:PSS) on the carrier recombination layer prepared in step S60, using water as the solvent, a spin-coating speed of 4000 rpm, and a spin-coating time of 30 s; then transfer to a hot plate and anneal at 150°C for 10 min to form a PEDOT:PSS film layer (the third carrier transport layer, serving as a hole transport layer) with a thickness of approximately 20 nm.

[0499] S80, 100 μL of the second perovskite precursor solution is added dropwise to the PEDOT:PSS film layer prepared in step S70 at a speed of 1000 rpm to 2000 rpm, rotated for 10 seconds, then increased to 4000 rpm at an acceleration of 1000 rpm / s, and spin-coated for 20 seconds at a spin coating speed of 4000 rpm, and then transferred to a vacuum flash chamber, and the pressure in the chamber is pumped to below 100 Pa (60 Pa) with a vacuum pump, and maintained for 20 seconds. After the vacuum flash treatment is completed, the multilayer film is annealed on a hot stage at 100°C for 10 minutes to form a second perovskite layer, also recorded as a narrow bandgap perovskite layer or a second perovskite precursor solution, with a thickness of about 700 nm.

[0500] The second perovskite precursor solution was prepared by the following method: the perovskite precursor material was added to 1 mL of a mixed solvent of DMF and DMSO with a volume ratio of 3:1, stirred at 600 rpm on a magnetic stirrer for 2 h, and filtered for later use.

[0501] Taking Example 1 as an example, the second perovskite precursor solution is prepared by the following method: 216 mg of FAI, 85 mg of MAI, 414 mg of PbI2, 335 mg of SnI2 and 0.1 mg to 1 mg (0.6 mg in Example 1) of MeO-4PACz are added to 1 mL of a mixed solvent of DMF and DMSO with a volume ratio of 3:1, stirred at 600 rpm on a magnetic stirrer for 2 hours, filtered and set aside. In Example 1, the perovskite metal halide in the second perovskite precursor solution and the second perovskite layer is FA 0.7 MA 0.3 Pb 0.5 Sn 0.5 I3.

[0502] S90, using an evaporation device to sequentially evaporate 25 nm thick C60, 10 nm thick BCP (bathocuproin) and 80 nm thick Cu on the narrow bandgap perovskite layer prepared in step S80, as an electron transport layer (third carrier transport layer), an insertion layer and a second electrode, respectively.

[0503] Example 2 uses a method basically the same as Example 1 to prepare a stacked solar cell. The operating processes of steps S10, S30, S40, S50, S60, S80 and S90 are the same as those in Example 1, except that: step S20 to prepare the hole transport layer and step S70 to prepare the PEDOT:PSS film layer both use a vacuum flash evaporation process.

[0504] S20: Spin-coat the MeO-4PACz ethanol solution onto the first substrate prepared in step S10 at a spin-coating speed of 4000 rpm for 30 seconds; then transfer the solution into a vacuum flash chamber, pump the pressure inside the chamber to below 100 Pa using a vacuum pump, and maintain the pressure for 20 seconds.

[0505] S70: a PEDOT:PSS film layer is prepared on the carrier recombination layer prepared in step S60 by spin coating, with a spin coating speed of 4000 rpm and a spin coating time of 30 s; then the film is transferred to a vacuum flash chamber, and the pressure in the chamber is pumped down to below 100 Pa by a vacuum pump, and then maintained for 20 s.

[0506] Examples 3 to 9 adopt substantially the same method as Example 1, and the preparation parameters can be found in Table 1. The only difference is the composition of the perovskite metal halide.

[0507] Comparative Example 1. Preparation of the first perovskite layer and the second perovskite layer by anti-solvent method

[0508] Comparative Example 1 uses a method substantially the same as Example 1, except that the methods for preparing the first perovskite layer in S30 and the second perovskite layer in S80 are different, both using the anti-solvent method.

[0509] S30 used the anti-solvent method to prepare the first perovskite layer: 123 mg of CH(NH2)2I, 59 mg of CH(NH2)2Br, 46 mg of CsI, 25 mg of CsBr, 428 mg of PbI2 and 209 mg of PbBr2 were added to 1 mL of a mixed solvent of DMF and DMSO (the volume ratio of DMF and DMSO was 3:1), stirred at 600 rpm on a magnetic stirrer for 2 h, and filtered to obtain the first perovskite precursor solution. 100 μL of the above-mentioned first perovskite precursor solution was spin-coated onto the hole transport layer prepared in step S20 (spin-coated at a spin-coating speed of 2000 rpm for 10 s, and then spin-coated at a spin-coating speed of 4000 rpm for 30 s), and then 250 μL of chlorobenzene was added dropwise to the spin-coated first perovskite precursor solution, followed by spin-coating the above-mentioned first perovskite precursor solution again, and then transferred to a hot stage for annealing at 100°C for 10 min to form a first perovskite layer.

[0510] S80 used the anti-solvent method to prepare the second perovskite layer: 216 mg of CH(NH2)2I, 85 mg of CH3NH2I, 414 mg of PbI2, 335 mg of SnI2, and 0.3 mg of MeO-4PACz were added to 1 mL of a mixed solvent of DMF and DMSO (the volume ratio of DMF and DMSO was 3:1), stirred at 600 rpm on a magnetic stirrer for 2 h, and filtered to obtain the second perovskite precursor solution. liquid; 100 μL of the above-mentioned second perovskite precursor solution was spin-coated onto the PEDOT:PSS film layer prepared in step S70 (spin coating at a spin coating speed of 1000 rpm for 10 s, and then spin coating at a spin coating speed of 4000 rpm for 30 s), and then 300 μL of ethyl acetate was added dropwise onto the spin-coated second perovskite precursor solution, followed by spin coating of the above-mentioned second perovskite precursor solution, and then transferred to a hot stage for annealing at 100° C. for 10 min to form a second perovskite layer.

[0511] Comparative Example 2. Preparation of the first perovskite layer and the second perovskite layer by anti-solvent method

[0512] Comparative Example 2 uses a method substantially the same as Example 2, except that the methods for preparing the first perovskite layer in S30 and the second perovskite layer in S80 are different, both using the anti-solvent method.

[0513] S20 used the anti-solvent method to prepare the first perovskite layer: 123 mg of CH(NH2)2I, 59 mg of CH(NH2)2Br, 46 mg of CsI, 25 mg of CsBr, 428 mg of PbI2 and 209 mg of PbBr2 were added to 1 mL of a mixed solvent of DMF and DMSO (the volume ratio of DMF and DMSO was 3:1), stirred at 600 rpm on a magnetic stirrer for 2 h, and filtered to obtain the first perovskite precursor solution. 100 μL of the above-mentioned first perovskite precursor solution was spin-coated onto the hole transport layer prepared in step S20 (spin-coated at a spin-coating speed of 2000 rpm for 10 s, and then spin-coated at a spin-coating speed of 4000 rpm for 30 s), and then 250 μL of chlorobenzene was added dropwise to the spin-coated first perovskite precursor solution, followed by spin-coating the above-mentioned first perovskite precursor solution, and then transferred to a hot stage for annealing at 100°C for 10 min to form a first perovskite layer.

[0514] S80 used the anti-solvent method to prepare the second perovskite layer: 216 mg of CH(NH2)2I, 85 mg of CH3NH2I, 414 mg of PbI2, 335 mg of SnI2, and 0.3 mg of MeO-4PACz were added to 1 mL of a mixed solvent of DMF and DMSO (the volume ratio of DMF and DMSO was 3:1), stirred at 600 rpm on a magnetic stirrer for 2 h, and filtered to obtain the second perovskite precursor solution. liquid; 100 μL of the above-mentioned second perovskite precursor solution was spin-coated onto the PEDOT:PSS film layer prepared in step S70 (spin coating at a spin coating speed of 1000 rpm for 10 s, and then spin coating at a spin coating speed of 4000 rpm for 30 s), and then 300 μL of ethyl acetate was added dropwise onto the spin-coated second perovskite precursor solution, followed by spin coating of the above-mentioned second perovskite precursor solution, and then transferred to a hot stage for annealing at 100° C. for 10 min to form a second perovskite layer.

[0515] Comparative Example 3. Preparation of the first perovskite layer and the second perovskite layer by anti-solvent method

[0516] Comparative Example 3 uses a method that is basically the same as that of Comparative Example 2. Both use the anti-solvent method to prepare the first perovskite layer and the second perovskite layer. The difference is that the first perovskite precursor solution used in S30 to prepare the first perovskite layer is the same, and the corresponding perovskite metal halide is FAPbI 3-y Br y , y=1.2.

[0517] Comparative Examples 4-5 use a method substantially the same as that of Example 1, except that the first perovskite precursor solution used in preparing the first perovskite layer is the same, and the corresponding perovskite metal halide CsaFA 1-a PbI 3-y Br y The y in (a=0.4) is 0 and 3 respectively. Please refer to Table 1.

[0518] Comparative Examples 6-7 use a method substantially the same as Example 1, except that the first and second perovskite layers are prepared using different methods, both of which are evaporation methods.

[0519] Among them, the step of preparing a wide band gap in step S30 is: 154mg of CH(NH2)2I, 74mg of CH(NH2)2Br, 428mg of PbI2 and 209mg of PbBr2 are added to 1mL of a mixed solvent of DMF and DMSO (the volume ratio of DMF and DMSO is 3:1), stirred at 600rpm on a magnetic stirrer for 2h, filtered, and a first perovskite precursor solution is prepared. 100μL of the above-mentioned first perovskite precursor solution is spin-coated onto the hole transport layer prepared in step S20 (spin-coated at a spin-coating speed of 2000rpm for 10s, then spin-coated at a spin-coating speed of 4000rpm for 30s), and then 250μL of chlorobenzene is added dropwise to the spin-coated perovskite precursor solution, followed by spin-coating the above-mentioned perovskite precursor solution, and then transferred to a hot stage for annealing at 100°C for 10min to form a first perovskite layer.

[0520] Among them, the step of preparing the narrow band gap in step S80 is as follows: 216 mg of CH(NH2)2I, 85 mg of CH3NH2I, 414 mg of PbI2, 335 mg of SnI2, and 0.3 mg of MeO-4PACz are added to 1 mL of a mixed solvent of DMF and DMSO (the volume ratio of DMF and DMSO is 3:1), stirred at 600 rpm on a magnetic stirrer for 2 h, and filtered to obtain the second perovskite Precursor solution; 100 μL of the above-mentioned second perovskite precursor solution was spin-coated onto the PEDOT:PSS film layer prepared in step S70 (spin-coating at a spin-coating speed of 1000 rpm for 10 s, and then spin-coating at a spin-coating speed of 4000 rpm for 30 s), and then 300 μL of ethyl acetate was added dropwise to the spin-coated perovskite precursor solution, followed by spin-coating the above-mentioned perovskite precursor solution, and then transferred to a hot stage for annealing at 100°C for 10 min to form a second perovskite layer.

[0521] Please refer to Table 1.

[0522] Table 1.

[0523] Test Method

[0524] 1. Morphology and structure testing

[0525] The sample to be tested is fixed to the sample holder using conductive tape for testing. A scanning electron microscope (SEM) is an experimental observation method intermediate between a transmission electron microscope and an optical microscope. It uses an electron beam to scan the surface of the sample being observed. The electron information generated by the interaction between the electron beam and the sample is then converted, amplified, and digitally processed to form an image. It offers a large depth of field, a wide field of view, and excellent three-dimensional imaging, making it effective for analyzing the sample's surface morphology. By varying the scanning amplitude of the electron beam across the sample surface, the magnification can be varied. Test samples can be observed at magnifications ranging from approximately 20x to 200,000x, such as 7K, 10K, 20K, and 30K, with 1K = 1000x. The SEM can be used to observe the crystallization of perovskite samples (such as grain size, grain thickness, and the presence of through-type grains with lateral dimensions ≥400nm) and their morphological characteristics.

[0526] SEM test objects: Based on the first electrode (transparent electrode), it can be a component sample in which the first perovskite layer has been deposited on the hole transport layer but the second carrier transport layer has not yet been deposited. It can be tested and analyzed in both the vertical and horizontal directions; component samples in which the second perovskite layer has been deposited.

[0527] (1) The observation surface is the exposed surface of the first perovskite layer, or the transparent surface of the first electrode.

[0528] (2) Use a glass cutter to cut a piece of 1×0.5cm 2 The component sample was glued onto the SEM sample preparation table with the longitudinal section facing upwards, and the crystal quality and grain thickness were observed using SEM.

[0529] Based on the SEM images of longitudinal cross-sections, combined with analysis software such as Image-J, relevant information can be obtained, including the dimensions of grooves and ridges, and the area percentage of through-type grains with a lateral dimension ≥400 nm in the longitudinal cross-section. Groove dimensions include groove width, average width, length, aspect ratio, full width at half maximum, average full width at half maximum, depth, average depth, aspect ratio, average depth-to-width ratio, and average spacing. Ridge dimensions include ridge width, average width, length, aspect ratio, full width at half maximum, average full width at half maximum, height, average height, aspect ratio, average aspect ratio, and average spacing. The average of these parameters should be collected from at least three areas.

[0530] The depth of the concave groove and the height of the convex ridge are basically consistent in average value.

[0531] 2. Analysis of the surface roughness and structural dimensions of the first perovskite layer.

[0532] The surface roughness and groove structure of the first perovskite layer were tested using a step profiler (probe profilometer).

[0533] Test sample: A device with a first perovskite layer deposited on a first carrier transport layer but not yet deposited with a second carrier transport layer (step S30 completed, step S40 not yet performed) served as the test sample. The lateral surface of one side of the perovskite layer served as the test surface. The test results can be found in Table 2.

[0534] Test conditions: The probe directly contacts the surface to record the profile change, which can obtain the two-dimensional profile change and calculate the line roughness.

[0535] The test is conducted using a contact-motion method: When the stylus slides gently along the surface being tested, the stylus moves up and down along the tiny peaks and valleys on the surface. The motion trajectory of the stylus reflects the surface contour.

[0536] Test results and analysis methods: A surface topography curve (also known as a surface roughness curve) can be obtained. The "valleys" in the curve correspond to concave grooves, and the area between the two nearest peaks with a fluctuation depth ≥100nm is considered a "valley." The "peaks" in the curve correspond to ridges, and the area between the two nearest valleys with a fluctuation height ≥100nm is considered a "peak." By calculating the "valley depth" or "peak height" in the surface roughness curve, the surface roughness of the surface under test can be obtained. Further analysis can be performed to obtain dimensional parameters such as the width, average width, length, aspect ratio, half-height width, average half-height width, depth, average depth, aspect ratio, average aspect ratio, and average spacing of the concave grooves. Similarly, the width, average width, length, aspect ratio, half-height width, average half-height width, height, average height, aspect ratio, average aspect ratio, and average spacing of the ridges can be analyzed. In addition, these dimensional parameters of the concave grooves and convex ridges can also be obtained from observation and analysis of SEM images of the longitudinal cross-section at certain magnifications, such as magnifications of 20K, 30K, and 40K.

[0537] 3. Optical microscope observation

[0538] Test sample: A thin-film device with a first perovskite layer deposited on a first carrier transport layer but not yet deposited with an electron transport layer (step S30 completed, step S40 not yet performed). The exposed surface of the first perovskite layer serves as the test surface. The lateral dimension of the device is designated as A2.

[0539] Instrument: Optical microscope (Keyence VHX-S650E). Place the test surface directly under the light beam and adjust the focus for observation.

[0540] Sample to be tested: A thin film component in which a first perovskite layer has been deposited on a first carrier transport layer but an electron transport layer has not yet been deposited (step S30 has been completed and step S40 has not yet been performed), with the exposed surface of the first perovskite layer being used as the test surface.

[0541] Test analysis method:

[0542] Select at least 960000μm 2 Statistical analysis was performed within the area.

[0543] (1) A non-smooth surface morphology image of the first perovskite can be obtained. The area enclosed by the outline of the concave groove in the image is recorded as A1, and the "percentage of the sum of the projected areas of the concave grooves along the longitudinal direction relative to the projected area of ​​the non-smooth surface along the longitudinal direction (recorded as R1)" = A1 / A2×100%.

[0544] (2) The average spacing of the grooves can be obtained by measuring the spacing between multiple adjacent grooves based on the center line analysis of the groove width and taking the average value.

[0545] The average spacing between the ridges and the average spacing between the grooves are basically consistent in value.

[0546] 4. Performance test of stacked solar cells

[0547] The stacked solar cell to be tested is connected to a dedicated capacitor and used as a variable load. During the process of charging the capacitor by the stacked solar cell, current and voltage sampling is performed, and the corresponding current and voltage data are recorded and plotted into a volt-ampere characteristic curve (IV curve). The various electrical performance parameters are calculated to obtain the test values ​​of open circuit voltage (Voc), short circuit current density (Jsc), fill factor (FF), and photoelectric conversion efficiency (PCE).

[0548] Test method: Using a solar simulator, test according to the national standard IEC61215. Using a crystalline silicon solar cell to calibrate the light intensity to the intensity of one sun, AM 1.5. The cell is connected to a digital source meter and the photoelectric conversion efficiency (PCE) is tested under light.

[0549] In the atmospheric environment, the sunlight simulation light source uses the AM1.5G standard light source, and a four-channel digital source meter (Keithley 2440) is used to measure the volt-ampere characteristic curve of the battery under the light source. The open circuit voltage Voc, short-circuit current density Jsc, and fill factor FF (Fill Factor) of the battery are obtained, and the photoelectric conversion efficiency PCE of the stacked solar cell is calculated based on this.

[0550] Photoelectric conversion efficiency is calculated as follows: PCE = Pout / Popt

[0551] =Voc×Jsc×(Vmpp×Jmpp) / (Voc×Jsc)

[0552] =Voc×Jsc×FF

[0553] Among them, Pout, Popt, Vmpp, and Jmpp are the battery operating output power, incident light power, battery maximum power point voltage, and maximum power point current, respectively.

[0554] Test analysis results

[0555] According to the test results, the first perovskite layer prepared in Examples 1-9 formed a non-smooth surface on the side facing away from the first electrode. The non-smooth surface included staggered concave grooves and convex ridges, with convex ridges formed between adjacent concave grooves, and concave grooves formed between adjacent convex ridges. The resulting tandem solar cell had a "concave-convex" interface at the first interface, formed by staggered concave grooves and convex ridges.

[0556] In Comparative Examples 1-7, the first perovskite layer in Comparative Examples 1-3 was prepared using a traditional anti-solvent method, the two perovskite layers in Comparative Examples 6-7 were both prepared using an evaporation process, and Comparative Examples 4-5 included only one halogen, I and Br. In Comparative Examples 1-7, basically no non-smooth surface was formed at the first interface, and it can be regarded as a relatively flat surface with basically no concave grooves or convex ridge structures.

[0557] Figure 1 is an optical microscope observation image of the non-smooth surface of the first perovskite layer prepared by the vacuum flash evaporation method in Example 1; Figure 2 is an optical microscope observation image of the non-smooth surface of the first perovskite layer prepared by the vacuum flash evaporation method in Example 2; Figure 3 is an optical microscope observation image observed from the glass substrate side in Example 1, in which a transparent electrode, a hole transport layer and a first perovskite layer are arranged in sequence.

[0558] In Figure 1, distinct grooves can be observed, with ridges forming between them. The overall distribution of the grooves and ridges on the surface of the first perovskite layer is relatively uniform, and the lateral dimensions of the grooves and ridges are well matched, resulting in an overall wrinkled morphology.

[0559] 1 , the non-smooth surface of the first perovskite layer has concave grooves with an extension length of ≥50 μm and convex ridges with an extension length of ≥50 μm.

[0560] It can also be seen from Figure 1 that the aspect ratio of most ridges is greater than 1, and a variety of aspect ratio ranges of ridges can be met, including but not limited to ridges meeting the following aspect ratios: ≥2, ≥3, ≥5, greater than 1 and less than or equal to 20, 2-10, 5-10, etc.

[0561] It can also be seen from FIG1 that the aspect ratio of most concave grooves is greater than 1; the illustrated area can meet a variety of aspect ratio ranges of concave grooves, including but not limited to concave grooves meeting the following aspect ratios: ≥5, ≥10, ≥15, greater than 1 and less than or equal to 20, 2 to 20, 5 to 20, 10 to 20, etc.

[0562] As can be seen from Figure 1, some of the concave grooves have corners in their extension direction. Some of the concave grooves have non-straight lines in their extension direction. Some adjacent concave grooves have intersection nodes, that is, some adjacent concave grooves are connected through the intersection nodes.

[0563] As can be seen from Figure 1, some ridges have corners in their extension direction. Some ridges have non-straight lines in their extension direction. Some adjacent ridges have intersection nodes, meaning that some adjacent ridges are connected through the intersection nodes.

[0564] Figure 8 is an optical microscope image of the all-perovskite tandem solar cell from the glass substrate side in Comparative Example 1, wherein a transparent electrode is provided on the surface of the glass substrate near the carrier recombination layer. Figure 9 is a scanning electron microscope (SEM) image of a longitudinal cross-section of the tandem solar cell prepared by the anti-solvent method in Comparative Example 1.

[0565] Based on the direct observation results of the non-smooth surface of the first perovskite layer under an optical microscope, the transverse and longitudinal cross-sections of the SEM (see Figures 1 and 4-6), and the surface roughness test and analysis results of the non-smooth surface, the morphology and size parameters of the grooves and ridges can be obtained, including but not limited to: the width, average width, length, aspect ratio, half-height width, average half-height width, depth, average depth, aspect ratio, average aspect ratio, average spacing and other size parameters of the grooves, and the width, average width, length, aspect ratio, half-height width, average spacing and other size parameters of the ridges. Dimensional parameters such as the average half-height width, height, average height, aspect ratio, average aspect ratio, average spacing, etc.; the percentage of the sum of the projected areas of the concave grooves along the longitudinal direction to the projected area of ​​the non-smooth surface along the longitudinal direction; the ratio of the half-height width of a ridge to the half-height width of adjacent concave grooves; the ratio of the average half-height width of a ridge to the average half-height width of a concave groove; the ratio of the sum of the half-height cross-sectional areas of a ridge to the sum of the half-height cross-sectional areas of a concave groove; the percentage of the sum of the projected areas of the concave grooves along the longitudinal direction to the projected area of ​​the non-smooth surface along the longitudinal direction, etc. The average depth of the concave grooves, the average height of the ridges, and the surface roughness within the test area are generally equal in value; and the average spacing of the ridges and the average spacing of the concave grooves within the test area are generally consistent in value.

[0566] In Examples 1-9, the average width of the concave grooves at the non-smooth surface of the first perovskite layer satisfies both the ranges of 0.3μm to 1μm and 0.5μm to 1μm, the average half-height width satisfies both the ranges of 0.2μm to 0.7μm and 0.3μm to 0.55μm, the average depth satisfies both the ranges of 100nm to 500nm and 100nm to 250nm, and the average aspect ratio satisfies both the ranges of 0.03 to 0.5, 0.2 to 0.5, and 0.25 to 0.3. As an example, the average width of Example 1 is about 0.8μm, the average half-height width is about 0.4μm, the average depth is about 200nm, and the average aspect ratio is about 0.28. The average width, average half-height width, average depth, and average aspect ratio in each of Examples 1-9 are relatively close. In Examples 1-9, the ratio of the sum of the half-height cross-sectional areas of the ridges to the sum of the half-height cross-sectional areas of the grooves satisfies both 1-36 and 10-30. In each of Examples 1-9, the morphologies of the interfaces formed by the different structural layers between the first and second perovskite layers are substantially matched. In most non-smooth regions, the ridges and grooves satisfy the requirement that the half-height width of the ridges is greater than the half-height width of the adjacent grooves. According to the test and analysis results, on the non-smooth surface of the first perovskite layer, most of the concave grooves have a longitudinal cross-section that is wide at the top and narrow at the bottom. Some of the concave grooves have an opening width that is greater than the bottom width, and some of the concave grooves have an opening width > half-height width > bottom width. In some non-smooth regions, the opening width of the concave grooves is greater than the bottom width, and in some non-smooth regions, the opening width is greater than the bottom width. In some non-smooth regions, the opening width is greater than the bottom width, and in some non-smooth regions, the opening width is greater than the bottom width. In some non-smooth regions, the opening width is greater than the half-height width, and in some non-smooth regions, the opening width is greater than the bottom width. In some non-smooth regions, the opening width is greater than the half-height width, and in some non-smooth regions, the opening width is greater than the half-height width, and in some non-smooth regions, the bottom width is greater than the top width. According to the test and analysis results, on the non-smooth surface of the first perovskite layer, most of the ridges have a longitudinal cross-section that is narrow at the top and wide at the bottom, and the bottom width of the ridges is greater than the top width. In some non-smooth regions, the bottom width of the ridges is greater than the top width, and in some non-smooth regions, the bottom width is greater than the top width. The half-width at half-height of at least a portion of the ridges is within the following two ranges: 1 μm to 2.5 μm and 1.5 μm to 2 μm. The half-width at half-height of at least a portion of the grooves is within the following two ranges: ≤ 1 μm and 0.2 μm to 0.7 μm. In a portion of the test area, the ratio of the average half-width at half-height of the ridges to the average half-width at half-height of the grooves is within the ranges of 1 to 6 and 4 to 5, and the ratio of the sum of the half-height cross-sectional areas to the sum of the half-height cross-sectional areas of the grooves is within the ranges of 1 to 36 and 10 to 30.

[0567] In each case, there are some test areas that satisfy the following conditions: the maximum width of the ridge within the extended length deviates from the average width of the ridge by no more than 30%; there are also some test areas that satisfy the following conditions: the maximum width of the ridge within the extended length deviates from the average width of the ridge by no more than 30%. See Figure 1.

[0568] In Examples 1-9, the average spacing between the concave grooves in most test areas was between 1 μm and 20 μm; in some test areas, the average spacing between the concave grooves was between 10 μm and 20 μm. Within the test areas, the average spacing between the ridges and the concave grooves was essentially the same. See Figure 1 for details.

[0569] In Examples 1-9, there are two adjacent concave grooves that satisfy the angle between the extension directions ≤ 15° or ≤ 30° within a certain extension length region, including but not limited to at least one of an extension length region of at least 30 μm, at least 50 μm, and at least 80 μm; there are also two adjacent convex ridges that satisfy the angle between the extension directions ≤ 15° or ≤ 30° within a certain extension length region, including but not limited to at least one of an extension length region of at least 30 μm, at least 50 μm, and at least 80 μm. In some embodiments of Examples 1-9, there are two adjacent concave grooves that satisfy the angle between the extension directions ≤ 30° within an extension length region of at least 80 μm. In some embodiments of Examples 1-9, there are two adjacent convex ridges that satisfy the angle between the extension directions ≤ 30° within an extension length region of at least 80 μm. Please refer to Figure 1.

[0570] Figure 4 is a scanning electron microscope (SEM) image of a longitudinal cross-section of a tandem solar cell prepared by the vacuum flash evaporation method in the embodiment shown in Figure 1. Figure 5 is a scanning electron microscope (SEM) image of a longitudinal cross-section of a tandem solar cell prepared by the vacuum flash evaporation method in Example 2 shown in Figure 2. Figure 6 is a scanning electron microscope (SEM) image of a transverse cross-section of a wide bandgap perovskite layer prepared by the vacuum flash evaporation method in Example 2 shown in Figure 5.

[0571] According to Figures 4 and 5, in the stacked solar cells prepared by the vacuum flash evaporation method in Examples 1 and 2, the perovskite crystals of the first and second perovskite layers have high quality, and the average size of the perovskite grains in the perovskite layers is large and has few defects. The longitudinal cross-section of the perovskite layer has few cracks, forming through-type grains that are integrated in the longitudinal direction. The lateral size of some through-type grains is ≥400nm. The lateral size of some through-type grains is ≥500nm. In Figure 5, the percentage of the area of ​​the through-type grains with a lateral size ≥400nm relative to the longitudinal cross-section is greater than 80%. In Figure 4, the percentage of the area of ​​the through-type grains with a lateral size ≥400nm relative to the longitudinal cross-section is greater than 80%.

[0572] In Examples 1-9, the average lateral size of the through-type grains satisfies 300 nm to 2 μm. In some of the embodiments, the average lateral size of the through-type grains satisfies 400 nm to 1 μm. In some of the embodiments, the average lateral size of the through-type grains satisfies 500 nm to 800 nm. In some of the embodiments, within a width of at least 10 μm of a longitudinal cross-section of the first perovskite layer, the area percentage of the through-type grains with a lateral size of ≥400 nm relative to the longitudinal cross-section satisfies ≥90%.

[0573] As shown in Figure 9, in the tandem solar cell prepared using the anti-solvent method in Comparative Example 1, the average perovskite grain size in the first and second perovskite layers is relatively small, and the perovskite layers are prone to defects. Numerous fragments are observed in the longitudinal cross-section, with virtually no through-type grains. This indicates that most grains struggle to integrate vertically, potentially hindering carrier transport.

[0574] Table 2. Non-smooth surface of the first perovskite layer (the surface of the first perovskite layer facing away from the first electrode)

[0575] In Examples 1-9, the average depth of the concave grooves, the average height of the ridges, and the surface roughness in the test area are substantially equal in value; and the average spacing of the ridges and the average spacing of the concave grooves in the test area are substantially consistent in value.

[0576] Table 3.

[0577] In Table 3, R1 represents the percentage of the sum of the projected areas of the concave grooves along the longitudinal direction relative to the projected area of ​​the non-smooth surface along the longitudinal direction.

[0578] The above description of various implementation modes and embodiments tends to emphasize the differences between the various implementation modes and embodiments. The same or similar aspects thereof can be referenced with each other and will not be described in detail herein for the sake of brevity.

[0579] The technical features of the above-mentioned embodiments and examples can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments and examples 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.

[0580] It should be noted that the present application is not limited to the above-mentioned embodiments and examples. The above-mentioned embodiments and examples are only examples, and within the scope of the technical solution of the present application, embodiments that have substantially the same structure as the technical idea and exert the same effect are all included in the technical scope of the present application. The above embodiments and examples only express several embodiments of the present application, and their descriptions are relatively detailed, but they cannot be understood as limiting the scope of the patent. In addition, without departing from the scope of the subject matter of the present application, various modifications that can be thought of by those skilled in the art to the embodiments or examples, and other methods of constructing by combining some of the constituent elements in the embodiments or examples are also included in the scope of the present application.

Claims

1. A perovskite-based tandem solar cell, wherein: The stacked solar cell comprises a first perovskite subcell, a carrier recombination layer, and a second perovskite subcell which are stacked in sequence, wherein the first perovskite subcell comprises a first perovskite layer, and the second perovskite subcell comprises a second perovskite layer; the band gap of the first perovskite layer is different from the band gap of the second perovskite layer; Wherein, the thickness direction of the first perovskite layer is recorded as the longitudinal direction; The surface of the first perovskite layer on one side close to the carrier recombination layer is a non-smooth surface, the non-smooth surface is provided with concave grooves, and convex edges are formed between at least a portion of adjacent concave grooves; The stacked solar cell meets at least one of the following characteristics: At least a portion of the concave grooves have different widths at at least a portion of the depth positions; At least a portion of the ridges have different widths at at least a portion of their heights.

2. The tandem solar cell according to claim 1, wherein: The morphologies of interfaces formed by different structural layers between the first perovskite layer and the second perovskite layer are substantially matched.

3. The tandem solar cell according to claim 1 or 2, which satisfies one or more of the following characteristics: The width of at least a portion of the ridges is 0.5 μm to 4 μm, and can be further 2 μm to 3.5 μm; The half-height width of at least a portion of the ridges is 1 μm to 2.5 μm, and can be 1.5 μm to 2 μm; The height of at least a portion of the ridges is greater than or equal to 100 nm, and may further be 100 nm to 250 nm; In at least a portion of the non-smooth surface, the average width of the ridges is 0.5 μm to 4 μm, and may be further 2 μm to 3.5 μm; In at least a portion of the non-smooth surface, the average half-height width of the ridges is 1 μm to 2.5 μm, and can be 1.5 μm to 2 μm; In at least a portion of the non-smooth surface, the average height of the ridges is 100 nm to 500 nm, and may be 100 nm to 250 nm; Optionally, the projection area of ​​at least a portion of the non-smooth surface along the longitudinal direction is greater than or equal to 0.1 mm 2 , further optionally greater than or equal to 0.6 mm 2 .

4. The tandem solar cell according to any one of claims 1 to 3, which satisfies one or more of the following characteristics: The width of at least a portion of the concave grooves is less than or equal to 1.2 μm, and may be 0.5 μm to 1 μm; The half-height width of at least a portion of the concave grooves is less than or equal to 1 μm, and can be optionally 0.2 μm to 0.7 μm; The depth of at least a portion of the concave grooves is greater than or equal to 100 nm, and may further be 100 nm to 250 nm; The aspect ratio of at least a portion of the concave grooves is 0.03 to 0.5, and can be further 0.25 to 0.35; In at least a portion of the non-smooth surface, the average width of the concave groove is 0.3 μm to 1 μm, and can be 0.5 μm to 1 μm; In at least a portion of the non-smooth surface, the average half-height width of the concave groove is 0.2 μm to 0.7 μm, and can be 0.3 μm to 0.55 μm; In at least a portion of the non-smooth surface, the average depth of the concave groove is 100nm to 500nm, and can be 100nm to 250nm; In at least a portion of the non-smooth surface, the average depth-to-width ratio of the concave groove is 0.03 to 0.5, and can be further 0.25 to 0.35; Optionally, the projection area of ​​at least a portion of the non-smooth surface along the longitudinal direction is greater than or equal to 0.1 mm 2 , further optionally greater than or equal to 0.6 mm 2 .

5. The tandem solar cell according to any one of claims 1 to 4, which satisfies one or more of the following characteristics: In at least a portion of the non-smooth surface, the average spacing of the ridges is 1 μm to 20 μm, and can be 10 μm to 20 μm; In at least a portion of the non-smooth surface, the average spacing of the concave grooves is 1 μm to 20 μm, and can be 10 μm to 20 μm; The half-height width of at least a portion of the convex ridges is greater than the half-height width of the adjacent concave grooves; In at least a portion of the non-smooth surface, the ratio of the average half-height width of the convex ridges to the average half-height width of the concave grooves is 1 to 6, and can further be 4 to 5; In at least a portion of the non-smooth surface, the ratio of the sum of the half-height cross-section areas of the ridges to the sum of the half-height cross-section areas of the concave grooves is 1 to 36, and may further be 10 to 30; In at least a portion of the non-smooth surface, the percentage of the sum of the projection areas of the concave grooves along the longitudinal direction relative to the projection area of ​​the non-smooth surface along the longitudinal direction is 5% to 95%, and can further be 10% to 50%; Optionally, the projection area of ​​at least a portion of the non-smooth surface along the longitudinal direction is greater than or equal to 0.1 mm 2 , further optionally greater than or equal to 0.6 mm 2 .

6. The tandem solar cell according to any one of claims 1 to 5, wherein: The opening width of at least a portion of the concave grooves is greater than the bottom width; Optionally, based on the proportion of the projection area of ​​the concave grooves along the longitudinal direction, at least 50% of the opening widths of the concave grooves are greater than the bottom widths; Further optionally, at least 80% of the concave grooves have an opening width greater than a bottom width; Optionally, based on the proportion of the projected area of ​​the concave grooves along the longitudinal direction, at least a portion of the concave grooves have an opening width > half-height width > bottom width; further optionally, at least 50% of the concave grooves have an opening width > half-height width > bottom width; Further optionally, at least 80% of the concave grooves have an opening width > half-height width > bottom width.

7. The tandem solar cell according to any one of claims 1 to 6, wherein: The bottom width of at least a portion of the ridges is greater than the top width; Optionally, based on the proportion of the projection area of ​​the ridges along the longitudinal direction, at least 50% of the ridges have a bottom width greater than a top width; Further optionally, at least 80% of the ridges have a bottom width greater than a top width; Optionally, based on the proportion of the projected area of ​​the ridges along the longitudinal direction, at least a portion of the ridges have a bottom width > half-height width > top width; further optionally, at least 50% of the ridges have a bottom width > half-height width > top width; further optionally, at least 80% of the ridges have a bottom width > half-height width > top width.

8. The tandem solar cell according to any one of claims 1 to 7, which satisfies one or more of the following characteristics: At least a portion of the concave grooves have corners in their extending directions; At least a portion of the concave grooves have a non-linear extension direction; At least a portion of the concave grooves have intersection nodes; At least a portion of the ridges have corners in their extension direction; At least a portion of the ridges extending in a direction in which at least a portion of the ridges extend is non-linear; At least a portion of the convex edges have intersection nodes; The maximum width of at least a portion of the concave grooves within the extended length deviates by no more than 30% from the average width of the concave grooves; The maximum width of at least a portion of the ridges within the extended length deviates by no more than 30% from the average width of the ridges; The extension length of at least a portion of the concave grooves is greater than or equal to 50 μm; The extension length of at least a portion of the ridges is greater than or equal to 50 μm; The aspect ratio of at least a portion of the concave grooves is greater than or equal to 2. Optionally, the aspect ratio of at least a portion of the concave grooves is greater than or equal to 5. The aspect ratio of at least a portion of the concave grooves is 1 to 10, and can be 5 to 10; The aspect ratio of at least a portion of the ridges is greater than or equal to 2, and optionally, the aspect ratio of at least a portion of the ridges is greater than or equal to 5; The aspect ratio of at least a portion of the ridges is 1-20, and can be optionally 10-20.

9. The tandem solar cell according to any one of claims 1 to 8, which satisfies one or more of the following characteristics: The angle between the extension directions of at least a portion of two adjacent concave grooves satisfies ≤30° in an extension length region of at least 30 μm; The angle between the extension directions of at least a portion of two adjacent convex ridges satisfies ≤30° in an extension length region of at least 30 μm.

10. The tandem solar cell according to claim 9, which satisfies one or more of the following characteristics: The angle between the extension directions of at least a portion of two adjacent concave grooves satisfies ≤15° over an extension length of at least 30 μm; optionally, the angle between the extension directions of at least a portion of two adjacent concave grooves satisfies ≤15° over an extension length of at least 50 μm; further optionally, the angle between the extension directions of at least a portion of two adjacent concave grooves satisfies ≤15° over an extension length of at least 80 μm; The angle between the extension directions of at least a portion of two adjacent concave grooves satisfies ≤30° over an extension length of at least 50 μm; optionally, the angle between the extension directions of at least a portion of two adjacent concave grooves satisfies ≤30° over an extension length of at least 80 μm; The angle between the extension directions of at least a portion of two adjacent ridges satisfies ≤15° over an extension length of at least 30 μm; optionally, the angle between the extension directions of at least a portion of two adjacent ridges satisfies ≤15° over an extension length of at least 50 μm; further optionally, the angle between the extension directions of at least a portion of two adjacent ridges satisfies ≤15° over an extension length of at least 80 μm; The angle between the extension directions of at least a portion of two adjacent ridges satisfies ≤30° over an extension length of at least 50 μm; optionally, the angle between the extension directions of at least a portion of two adjacent ridges satisfies ≤30° over an extension length of at least 80 μm.

11. The tandem solar cell according to any one of claims 1 to 10, wherein: The band gap of the first perovskite layer is greater than the band gap of the second perovskite layer; Optionally, the band gap of the first perovskite layer is 1.2 eV to 2.4 eV, and optionally 1.6 eV to 2.3 eV; the band gap of the second perovskite layer is 1.0 eV to 1.4 eV.

12. The tandem solar cell according to any one of claims 1 to 11, wherein: The first perovskite layer includes a first perovskite metal halide, and the halogen in the first perovskite metal halide includes bromine and iodine elements; optionally, the halogen in the first perovskite metal halide is a combination of bromine and iodine elements; Optionally, the second perovskite layer includes a second perovskite metal halide, and the halogen in the second perovskite metal halide includes iodine element; further optionally, the halogen in the second perovskite metal halide is iodine element.

13. The tandem solar cell according to claim 12, wherein: The atomic molar ratio of bromine element to iodine element in the first perovskite metal halide is (3 - y):y, where 0 < y ≤ 2; optionally, 1 ≤ y ≤ 2.

14. The tandem solar cell according to any one of claims 1 to 13, wherein: At least a part of the perovskite grains in the first perovskite layer are through - type grains, and both ends of the through - type grains along the longitudinal direction are located on both side surfaces of the first perovskite layer respectively.

15. The tandem solar cell according to claim 14, wherein: The lateral size of at least a part of the through - type grains is greater than or equal to 500 nm; wherein, the lateral direction is orthogonal to the longitudinal direction, and the lateral size of the through - type grains represents the maximum size among the anisotropic sizes of the grains in the lateral cross - section. Optionally, the lateral size of at least a part of the through - type grains is greater than or equal to 400 nm, and can be greater than or equal to 500 nm; Optionally, the average lateral size of the through - type grains is 300 nm - 2 μm, can be 400 nm - 1 μm, and further can be 500 nm - 800 nm.

16. The tandem solar cell according to claim 14 or 15, wherein: On the longitudinal section of the first perovskite layer, the area percentage of the through - type grains relative to the longitudinal section is greater than or equal to 80%, and can be greater than or equal to 90%.

17. The tandem solar cell according to any one of claims 14 to 16, wherein: In at least a part of the width region of the longitudinal section of the first perovskite layer, the area percentage of the through - type grains with a lateral size greater than or equal to 400 nm relative to the longitudinal section is greater than or equal to 80%, and can be greater than or equal to 90%; Optionally, at least a part of the width region of the longitudinal section of the first perovskite layer corresponds to a width region of at least 10 μm.

18. The tandem solar cell according to any one of claims 1 - 17, which satisfies one or more of the following characteristics: Both the first charge carrier transport layer and the third charge carrier transport layer are electron transport layers, and both the second charge carrier transport layer and the fourth charge carrier transport layer are hole transport layers, or both the first charge carrier transport layer and the third charge carrier transport layer are hole transport layers, and both the second charge carrier transport layer and the fourth charge carrier transport layer are electron transport layers; The tandem solar cell further includes a first electrode and a second electrode. The first electrode is located on the side of the first perovskite sub - cell背离 the carrier recombination layer, and the second electrode is located on the side of the second perovskite sub - cell背离 the carrier recombination layer; the first electrode is a transparent electrode; At least one side of the first charge carrier transport layer includes a hetero - charge carrier blocking layer; At least one side of the second charge carrier transport layer includes a hetero - charge carrier blocking layer; At least one side of the third charge carrier transport layer includes a hetero - charge carrier blocking layer; At least one side of the fourth carrier transport layer includes a foreign carrier blocking layer.

19. The tandem solar cell according to any one of claims 1 to 18, wherein: The first perovskite sub-cell and the second perovskite sub-cell form an integrated structure with two ends.

20. The tandem solar cell according to any one of claims 1 to 19, wherein: The stacked solar cell is a two-end stacked solar cell.

21. The tandem solar cell according to any one of claims 1 to 20, wherein: The stacked solar cell is a full perovskite stacked solar cell.

22. A method for preparing a perovskite-based tandem solar cell according to any one of claims 1 to 21, comprising the following steps: sequentially stacking a first carrier transport layer, a first perovskite layer, a second carrier transport layer, a carrier recombination layer, a third carrier transport layer, a second perovskite layer, a fourth carrier transport layer and a second electrode on a surface of one side of a first electrode to prepare the perovskite-based tandem solar cell; in, The method of stacking the first perovskite layer on a side of the first carrier transport layer away from the first electrode comprises the following steps: Applying the precursor solution I of the first perovskite layer to the surface of the first carrier transport layer on the side away from the first electrode to form a coating layer I; The coating layer I is subjected to vacuum flash evaporation treatment and annealing treatment to form the first perovskite layer, and the non-smooth surface is formed on a side of the first perovskite layer away from the first electrode.

23. The method for preparing a perovskite-based tandem solar cell according to claim 22, wherein: The method for preparing the perovskite-based tandem solar cell meets one or more of the following characteristics: The vacuum flash evaporation treatment is carried out under negative pressure conditions, and the negative pressure condition is less than or equal to 100 Pa, and can be selected from 50 Pa to 100 Pa; The temperature for the vacuum flash treatment is -10°C to 100°C, optionally 0°C to 30°C, and further optionally 20°C to 30°C; The duration of the vacuum flash treatment is 10s to 100s, optionally 10s to 30s, and further optionally 15s to 25s; The annealing treatment is performed by a hot stage, optionally, a 30°C to 200°C hot stage, further optionally, a 90°C to 110°C hot stage, and further optionally, a 98°C to 102°C hot stage; The annealing time of the annealing treatment is 30s to 60min, optionally 5min to 20min, and further optionally 14min to 16min.

24. The method for preparing a perovskite-based tandem solar cell according to claim 22 or 23, wherein: The step of coating the precursor solution I of the first perovskite layer onto the surface of the first carrier transport layer on the side away from the first electrode comprises: Spin coating a portion of the precursor solution I onto a surface of the first carrier transport layer that is away from the first electrode at a first rotation speed; Accelerating the rotation speed from the first rotation speed to a second rotation speed, and continuing to spin-coat another portion of the precursor liquid I at the second rotation speed; Wherein, the second rotation speed is greater than the first rotation speed.

25. The method for preparing a perovskite-based tandem solar cell according to claim 24, which satisfies one or more of the following characteristics: The first rotation speed is 1000 rpm to 6000 rpm, and can be optionally 1000 rpm to 2000 rpm; the spin coating is performed at the first rotation speed for 8 s to 12 s; In the step of accelerating the rotation speed from the first rotation speed to the second rotation speed, the acceleration is 200 rpm / s to 2000 rpm / s, and can be optionally 800 rpm / s to 1200 rpm / s; The second rotation speed is 3000 rpm to 4500 rpm, and can be optionally 3800 rpm to 4200 rpm; the spin coating is performed at the second rotation speed for 18 s to 22 s.

26. An electrical device comprising at least one of the perovskite-based tandem solar cell described in any one of claims 1 to 21 and the perovskite-based tandem solar cell prepared by the method for preparing a perovskite-based tandem solar cell described in any one of claims 22 to 25.

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