Solar laminated cell, preparation method thereof and photovoltaic module

Abstract

The application provides a solar laminated cell and a preparation method and a photovoltaic module thereof, and relates to the technical field of photovoltaics. The solar laminated cell comprises a bottom cell and a top cell stacked along a first direction, and a composite layer is arranged between the bottom cell and the top cell. The top cell comprises a first transport layer, a perovskite layer, a second transport layer, a transparent conductive layer and a first electrode arranged along the first direction. The surface of the perovskite layer facing the transparent conductive layer has a first textured structure, and the first textured structure comprises a plurality of convex portions. The height of the convex portions along the first direction is D1, the thickness of the perovskite layer along the first direction is D2, and D1 and D2 satisfy the condition: 0.1 <= D1 / D2 <= 0.3. The first textured structure arranged on the perovskite layer enables the solar laminated cell to absorb more incident light, and simultaneously increases the contact area of the perovskite layer and the second transport layer, so that the short-circuit current and the fill factor of the solar laminated cell are improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of photovoltaic, in particular to a solar laminated cell, a preparation method thereof and a photovoltaic module. BACKGROUND

[0002] The solar laminated cell is used for converting solar energy into electric energy, which can be laminated by a top cell, a composite layer and a bottom cell. At present, the short circuit current and the fill factor of the solar laminated cell are difficult to improve, which affects the efficiency of the solar laminated cell. SUMMARY

[0003] Therefore, the present application provides a solar laminated cell, a preparation method thereof and a photovoltaic module, so as to solve the problem that the short circuit current and the fill factor of the solar laminated cell are difficult to improve in the prior art.

[0004] In a first aspect, an embodiment of the present application provides a solar laminated cell, comprising a bottom cell and a top cell stacked along a first direction, a composite layer is arranged between the bottom cell and the top cell, the top cell comprises a first transport layer, a perovskite layer, a second transport layer, a transparent conductive layer and a first electrode arranged along the first direction, wherein a surface of the perovskite layer facing the transparent conductive layer has a first textured structure, the first textured structure comprises a plurality of protruding portions, a height of the protruding portions along the first direction is D1, a thickness of the perovskite layer along the first direction is D2, and D1 and D2 satisfy: 0.1≤D1 / D2≤0.3.

[0005] In a possible implementation, the height D1 of the protruding portions along the first direction satisfies: 50nm≤D1≤500nm, and / or the thickness D2 of the perovskite layer along the first direction satisfies: 500nm≤D2≤1500nm.

[0006] In a possible implementation, a width of the protruding portions along a second direction gradually decreases towards the transparent conductive layer.

[0007] In a possible implementation, the protruding portions comprise a first bottom wall and a first side wall connected to both sides of the first bottom wall along the second direction, and an included angle α between the first side wall and the first bottom wall satisfies: 35°≤α≤65°.

[0008] In a possible implementation, a cross-sectional shape of the protruding portions along the first direction is triangular.

[0009] In a possible implementation, the protrusions further include a first top wall, the first top wall is arranged along the first direction with the first bottom wall, and the first top wall is connected with the first side wall, a width of the first top wall along a second direction is less than a width of the first bottom wall along the second direction.

[0010] In a possible implementation, a width W1 of the first top wall along the second direction satisfies: 500nm≤W1≤5μm, and a width W2 of the first bottom wall along the second direction satisfies: 500nm≤W2≤5μm.

[0011] In a possible implementation, the first textured structure further includes recesses, the recesses are arranged alternately with the protrusions, and a cross-sectional shape of the recesses along the first direction is triangular, trapezoidal or arched.

[0012] In a possible implementation, one of the first transport layer and the second transport layer is an electron transport layer, and the other is a hole transport layer, and the second transport layer has a second textured structure on a surface thereof facing the transparent conductive layer.

[0013] In a possible implementation, a thickness D3 of the first transport layer along the first direction satisfies: 10nm≤D3≤40nm, and / or a thickness D4 of the second transport layer along the first direction satisfies: 10nm≤D4≤30nm.

[0014] In a possible implementation, the solar laminated cell further includes a protective layer, the protective layer is located on a side of the transparent conductive layer away from the second transport layer along the first direction, and the transparent conductive layer has a third textured structure on a surface thereof facing the protective layer.

[0015] In a possible implementation, a thickness D5 of the transparent conductive layer along the first direction satisfies: 30nm≤D5≤100nm, and / or a thickness D6 of the protective layer along the first direction satisfies: 50nm≤D6≤200nm.

[0016] In a possible implementation, a side of the bottom cell away from the composite layer is provided with a second electrode, a thickness D7 of the composite layer along the first direction satisfies: 5nm≤D7≤30nm, and / or a thickness D8 of the substrate of the bottom cell satisfies: 100μm≤D8≤260μm.

[0017] In a second aspect, an embodiment of the present application provides a photovoltaic module, including a cover plate, an encapsulation layer and a cell string, wherein the cell string includes a plurality of solar laminated cells according to any one of the above.

[0018] In a third aspect, the embodiments of the present application provide a method for manufacturing a solar laminated cell, comprising:

[0019] manufacturing a substrate, the substrate comprising a bottom cell, a composite layer and a first transport layer arranged along a first direction;

[0020] forming a perovskite layer with a thickness of D2 on the substrate, the perovskite layer being located on a side of the first transport layer away from the composite layer;

[0021] etching the perovskite layer to form a first textured structure on a surface of the perovskite layer facing away from the substrate, the first textured structure comprising a plurality of protrusions with a height of D1, D1 and D2 satisfying: 0.1≤D1 / D2≤0.3;

[0022] forming a second transport layer on the first textured structure;

[0023] forming a transparent conductive layer on the second transport layer;

[0024] forming a first electrode on the transparent conductive layer.

[0025] In a possible implementation, before the step of forming the second transport layer on the first textured structure, the method for manufacturing the solar laminated cell further comprises:

[0026] cleaning the first textured structure.

[0027] In a possible implementation, the step of cleaning the first textured structure comprises:

[0028] spin-coating a cleaning solution on the first textured structure, a spin-coating speed V satisfying: 4000rpm≤V≤5000rpm, and a spin-coating time t1 satisfying: 5s≤t1≤15s;

[0029] performing annealing treatment on the first textured structure, an annealing temperature T satisfying: 85℃≤T≤115℃, and an annealing time t2 satisfying: 5min≤t2≤10min.

[0030] In a possible implementation, the etching process for etching the perovskite layer is plasma etching, ion beam etching or focused ion beam etching.

[0031] In a possible implementation, the step of forming the second transport layer on the first textured structure comprises:

[0032] forming the second transport layer with a thickness D4 satisfying: 10nm≤D4≤30nm, the surface of the second transport layer facing away from the perovskite layer having a second textured structure.

[0033] In a possible implementation, the step of forming the transparent conductive layer on the second transport layer comprises:

[0034] The transparent conductive layer has a third textured surface facing away from the perovskite layer, and has a thickness D5 satisfying 30 nm≤D5≤100 nm.

[0035] The beneficial effects of the present application are: the first textured surface is arranged to make the solar tandem cell absorb more incident light, reduce optical loss, thereby improving the short-circuit current of the solar tandem cell, improving the photoelectric conversion efficiency of the solar tandem cell, increasing the contact area of the perovskite layer and the second transport layer, reducing the recombination loss, improving the extraction efficiency of the carriers, and improving the short-circuit current and the fill factor of the solar tandem cell.

[0036] It should be understood that the above general description and the following detailed description are only exemplary and do not limit the present application. BRIEF DESCRIPTION OF DRAWINGS

[0037] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed in the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0038] Figure 1 a schematic diagram of a solar tandem cell in an embodiment of the present application;

[0039] Figure 2 a schematic diagram of a perovskite layer of a solar tandem cell in the embodiment of the present application; Figure 1

[0040] a schematic diagram of a perovskite layer of a solar tandem cell in the embodiment of the present application; Figure 3 Figure 2 a schematic diagram of a solar tandem cell in another embodiment of the present application;

[0041] Figure 4 a schematic diagram of a perovskite layer of a solar tandem cell in the embodiment of the present application;

[0042] Figure 5 Figure 4 a schematic diagram of a perovskite layer of a solar tandem cell in the embodiment of the present application;

[0043] Figure 6 a schematic diagram of a solar tandem cell in another embodiment of the present application;

[0044] Figure 7 a schematic diagram of a perovskite layer of a solar tandem cell in the embodiment of the present application; Figure 6

[0045] Figure 8 ​​​A flow chart of a method for manufacturing a solar laminated cell in an embodiment of the present application.

[0046] Figure 9 A schematic diagram of a photovoltaic module in an embodiment of the present application.

[0047] Reference signs:

[0048] 1000 - photovoltaic module; 1001 - first cover plate; 1002 - first encapsulation layer; 1003 - cell string; 1004 - second encapsulation layer; 1005 - second cover plate.

[0049] 100 - solar laminated cell; 10 - top cell; 11 - first transport layer; 12 - perovskite layer; 121 - first textured structure; 1211 - protrusion; 1211a - first end; 1211b - second end; 1211c - first bottom wall; 1211d - first side wall; 1211e - first top wall; 1212 - recess; 122 - body part; 1221 - third end; 1222 - fourth end; 13 - second transport layer; 131 - second textured structure; 14 - transparent conductive layer; 141 - third textured structure; 15 - first electrode; 16 - protective layer; 20 - bottom cell; 21 - substrate; 2 - second electrode; 30 - composite layer.

[0050] D1 - height of protrusion along first direction; D2 - thickness of perovskite layer along first direction; W1 - width of first top wall along second direction; W2 - width of first bottom wall along second direction; a - included angle between first side wall and first bottom wall. DETAILED DESCRIPTION

[0051] In order to better understand the technical solutions of the present application, the embodiments of the present application are described in detail below with reference to the drawings.

[0052] It should be clear that the described embodiments are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative labor fall within the scope of protection of the present application.

[0053] The terms used in the embodiments of the present application are merely for the purpose of describing the specific embodiments, and are not intended to limit the present application. The singular forms "a", "an" and "the" used in the embodiments of the present application and the appended claims are also intended to include the plural forms, unless the context clearly indicates otherwise.

[0054] It should be understood that the term "and / or" used herein is only a description of the association relationship of the associated objects, which means that there can be three relationships, for example, A and / or B, which can represent the three cases of A alone, A and B together, and B alone. In addition, the character " / " herein generally represents that the front and rear associated objects are in an "or" relationship.

[0055] As shown in Figure 1 The embodiments of the present application provide a solar laminated cell 100, which comprises a bottom cell 20 and a top cell 10 stacked along a first direction Z, and a composite layer 30 is arranged between the bottom cell 20 and the top cell 10. The first direction Z can be the thickness direction of the solar laminated cell 100.

[0056] The top cell 10 can be a perovskite cell, and the top cell 10 comprises a first transport layer 11, a perovskite layer 12, a second transport layer 13, a transparent conductive layer 14 and a first electrode 15 arranged along the first direction Z. The first transport layer 11 is arranged on the composite layer 30, the perovskite layer 12 is arranged on the first transport layer 11, the second transport layer 13 is arranged on the side of the perovskite layer 12 away from the first transport layer 11, one of the first transport layer 11 and the second transport layer 13 is an electron transport layer, and the other is a hole transport layer. The electron transport layer can be a metal oxide or a fullerene derivative, and the hole transport layer can be a metal oxide or a SAM (self-assembled monolayer). The transparent conductive layer 14 is arranged on the second transport layer 13, and the first electrode 15 is arranged on the transparent conductive layer 14 and electrically connected with the transparent conductive layer 14. The conductive layer can be IZO (indium zinc oxide), which is a transparent conductive oxide with excellent light transmittance and good conductivity. The first electrode 15 can be sintered from a metal paste, and the metal paste can include at least one of silver, gallium, copper, tin, gold, lead or nickel.

[0057] The bottom cell 20 can be a crystalline silicon cell, such as a PERC cell (emitter and back passivation cell), a PERT cell (passivated emitter and rear totally diffused cell), a TOPCon cell (tunnel oxide passivated contact cell) or a HJT cell (intrinsic thin film heterojunction cell). The bottom cell 20 comprises a substrate 21, which can be an N-type substrate or a P-type substrate. The N-type substrate 21 can be a silicon substrate doped with an N-type element, which can be one or a combination of a phosphorus element, an arsenic element or an antimony element. The P-type substrate 21 can be a silicon substrate doped with a P-type element, which can be one or a combination of a boron element, an indium element or a gallium element.

[0058] The composite layer 30 can be a transparent conductive oxide, such as ITO (indium tin oxide), AZO (aluminum-doped zinc oxide), FTO (fluorine-doped tin oxide) or ATO (antimony-doped tin oxide).

[0059] Please refer to Figure 2 The surface of the perovskite layer 12 in the top cell 10 facing the transparent conductive layer 14 has a first textured structure 121, which includes a plurality of protruding portions 1211, that is, the surface of the perovskite layer 12 facing the transparent conductive layer 14 is a protruding uneven textured surface. Compared with the surface of the perovskite layer 12 facing the transparent conductive layer 14 being flat, the first textured structure 121 reduces the light reflection of the incident light, that is, reduces the reflectivity of the solar laminated battery 100, so that the solar laminated battery 100 absorbs more incident light, reduces the optical loss, thereby improving the short-circuit current of the solar laminated battery 100 and improving the photoelectric conversion efficiency of the solar laminated battery 100. At the same time, the first textured structure 121 has a plurality of protruding portions 1211, so that the first textured structure 121 has a large surface area, thereby increasing the contact area of the perovskite layer 12 and the second transport layer 13, reducing the recombination loss, improving the extraction efficiency of the carriers, and improving the short-circuit current and the fill factor of the solar laminated battery 100.

[0060] The perovskite layer 12 further includes a body portion 122, and the protruding portion 1211 is arranged on one side of the body portion 122 facing the transparent conductive layer 14, and the protruding portion 1211 is connected with the body portion 122. Along the first direction Z, the protruding portion 1211 includes a first end 1211a facing the transparent conductive layer 14 and a second end 1211b away from the transparent conductive layer 14, and the body portion 122 includes a third end 1221 facing the transparent conductive layer 14 and a fourth end 1222 away from the transparent conductive layer 14, and the second end 1211b of the protruding portion 1211 is connected with the third end 1221 of the transparent conductive layer 14. The height of the protruding portion 1211 along the first direction Z (i.e. the height of the first textured structure 121) is D1, which is the distance between the first end 1211a and the second end 1211b of the protruding portion 1211 along the thickness direction of the solar laminated battery 100. The thickness of the perovskite layer 12 along the first direction Z is D2, which is the distance between the first end 1211a of the protruding portion 1211 and the fourth end 1222 of the body portion 122 along the thickness direction of the solar laminated battery 100.

[0061] The height D1 of the protruding portion 1211 along the first direction Z and the thickness D2 of the perovskite layer 12 along the first direction Z satisfy: 0.1≤D1 / D2≤0.3, and the ratio of D1 to D2 can be 0.1, 0.12, 0.14, 0.16, 0.18, 0.2, 0.22, 0.24, 0.26, 0.28 or 0.3, and of course it can also be other values in the above range.

[0062] If the ratio of D1 to D2 decreases, that is, if the height D1 of the protrusion 1211 is too small and the height D2 of the perovskite layer 12 is too large, the morphology of the first textured structure 121 becomes too flat, resulting in increased reflectivity of the surface of the perovskite layer 12, which increases optical loss and is not conducive to increasing the surface area of ​​the first textured structure 121, affecting the contact area between the perovskite layer 12 and the second transport layer 13. At the same time, if the overall thickness of the perovskite layer 12 is too large, it will lead to increased recombination loss and increased resistance, thereby affecting the short-circuit current and fill factor of the solar tandem cell 100.

[0063] If the ratio of D1 to D2 increases, that is, if the height D1 of the protrusion 1211 is too large and the height D2 of the perovskite layer 12 is too small, the part between adjacent protrusions 1211 in the first textured structure 121 is prone to breakage or holes, increasing recombination loss and leakage risk. At the same time, if the height of the protrusion 1211 is too large, the perovskite layer 12 is prone to stress concentration, which reduces the reliability of the perovskite layer 12 structure and causes the perovskite layer 12 to detach from other film layers, thereby causing the solar tandem cell 100 to fail to work properly.

[0064] As can be seen from the above, both excessively small height D1 of the protrusion 1211 and excessively large height D2 of the perovskite layer 12, and excessively large height D1 of the protrusion 1211 and excessively small height D2 of the perovskite layer 12, will affect the performance of the solar tandem cell 100. Therefore, this application limits the relationship between the height D1 of the protrusion 1211 and the height D2 of the perovskite layer 12, so that the thickness of the first textured structure 121 matches the thickness of the perovskite layer 12. This reduces the optical loss of the solar tandem cell 100, increases the contact area between the perovskite layer 12 and the second transmission layer 13, and improves the reliability and stability of the first textured structure 121 and the entire perovskite layer 12 structure, thereby improving the performance of the solar tandem cell 100, increasing its power, and enabling the solar tandem cell 100 to operate normally and stably.

[0065] like Figure 2 As shown, in one possible implementation, the height D1 of the protrusion 1211 along the first direction Z satisfies: 50nm≤D1≤500nm, for example 50nm, 60nm, 70nm, 80nm, 90nm, 100nm, 150nm, 200nm, 250nm, 300nm, 350nm, 400nm, 450nm or 500nm, or other values ​​within the above range.

[0066] The thickness D2 of the perovskite layer 12 along the first direction Z satisfies: 500nm≤D2≤1500nm, for example, 500nm, 550nm, 600nm, 650nm, 700nm, 750nm, 800nm, 850nm, 900nm, 950nm, 1000nm, 1100nm, 1200nm, 1300nm, 1400nm or 1500nm, or other values ​​within the above range.

[0067] As mentioned above, both excessively small heights (D1) of the protrusion 1211 and excessively large heights (D2) of the perovskite layer 12, and excessively large heights (D1) of the protrusion 1211 and excessively small heights (D2) of the perovskite layer 12, will affect the performance of the solar tandem cell 100. Therefore, in this embodiment, the height of the protrusion 1211 and the thickness of the perovskite layer 12 are specifically limited to improve the performance and power of the solar tandem cell 100, thereby enabling the solar tandem cell 100 to operate normally and stably.

[0068] In another possible implementation, the height D1 of the protrusion 1211 along the first direction Z satisfies: 50nm ≤ D1 ≤ 500nm, or the thickness D2 of the perovskite layer 12 along the first direction Z satisfies: 500nm ≤ D2 ≤ 1500nm. The solar tandem cell 100 in this embodiment satisfies at least one of the above conditions D1 and D2.

[0069] like Figure 1 and Figure 2 As shown, in one possible implementation, the width of the protrusion 1211 along the second direction X gradually decreases toward the transparent conductive layer 14.

[0070] The second direction X is perpendicular to the first direction Z mentioned above. The second direction X can be the length direction and / or width direction of the solar tandem cell 100. The width of the protrusion 1211 gradually decreases towards the transparent conductive layer 14 along the second direction X, making the shape of the protrusion 1211 approximately pyramidal. That is, the protrusion 1211 can reflect incident light in multiple directions, which is beneficial for the incident light to be reflected multiple times inside the perovskite layer 12, thereby improving the light absorption efficiency of the solar tandem cell 100 and improving the efficiency of the solar tandem cell 100. On the other hand, in the embodiments of this application, the first textured structure 121 with the protrusion 1211 can be prepared by processes such as dry etching, which is conducive to large-scale mass production.

[0071] like Figure 3As shown, in one possible implementation, the protrusion 1211 includes a first bottom wall 1211c and a first side wall 1211d connected to both sides of the first bottom wall 1211c along the second direction X, and an included angle a between the first side wall 1211d and the first bottom wall 1211c satisfies: 35°≤a≤65°, for example, 35°, 40°, 45°, 50°, 55°, 60°, or 65°, and of course, other values within the above range are also possible.

[0072] Please refer to Figure 1 and Figure 2 As mentioned above, the protrusion 1211 includes a first end 1211a facing the transparent conductive layer 14 and a second end 1211b away from the transparent conductive layer 14, the first bottom wall 1211c is located at the first end 1211a, the first bottom wall 1211c is connected to the body part 122 of the perovskite layer 12, and the setting direction of the first bottom wall 1211c can be parallel to the second direction X. The smaller the angle of the included angle a, the smaller the inclination of the first side wall 1211d, in other words, the first side wall 1211d is set relatively gently. If the angle of the included angle a is too small, the protrusion 1211 as a whole presents a flat shape, which not only cannot increase the light absorption efficiency, but also is not conducive to increasing the surface area of the perovskite layer 12, thereby affecting the contact area of the perovskite layer 12 and the second transport layer 13, affecting the short-circuit current and the fill factor of the solar laminated battery 100. The larger the angle of the included angle a, the greater the inclination of the first side wall 1211d, in other words, the first side wall 1211d is set relatively steep. If the angle of the included angle a is too large, the protrusion 1211 as a whole presents a high and narrow shape, which makes the stability of the structure of the protrusion 1211 itself poor, is easy to crack due to stress concentration, and affects the stability and reliability of the overall structure of the solar laminated battery 100.

[0073] Based on this, the present application limits the angle of the included angle a between the first side wall 1211d and the first bottom wall 1211c of the protrusion 1211, that is, limits the shape of the protrusion 1211, so as to increase the absorption effect of the first textured structure 121 to sunlight while ensuring the stability of the structure of the protrusion 1211, thereby reducing the optical loss of the solar laminated battery 100, and increasing the surface of the first textured structure 121, thereby increasing the contact area of the perovskite layer 12 and the second transport layer 13 and the transparent conductive layer 14, and further improving the short-circuit current and the fill factor of the solar laminated battery 100.

[0074] As Figure 2As shown in FIG. 12, in a possible implementation, the cross-sectional shape of the protrusion 1211 along the first direction Z is triangular, so that the protrusion 1211 has a structure of a pyramid, thereby enabling the protrusion 1211 to reflect incident light in multiple directions and improving the light absorption efficiency of the solar laminated battery 100.

[0075] As shown in FIG. 12, in a possible implementation, the protrusion 1211 further includes a first top wall 1211e, which is arranged along the first direction Z with the first bottom wall 1211c and connected with the first side wall 1211d, and the width of the first top wall 1211e along the second direction X is less than the width of the first bottom wall 1211c along the second direction X. Figure 4 Figure 5 As shown in FIG. 12, in a possible implementation, the protrusion 1211 further includes a first top wall 1211e, which is arranged along the first direction Z with the first bottom wall 1211c and connected with the first side wall 1211d, and the width of the first top wall 1211e along the second direction X is less than the width of the first bottom wall 1211c along the second direction X.

[0076] The cross-sectional shape of the protrusion 1211 along the first direction Z can be trapezoidal, and the area of the first top wall 1211e can be less than the area of the first bottom wall 1211c, so that the protrusion 1211 has a structure of a truncated pyramid. The first top wall 1211e of the protrusion 1211 can also reflect light, thereby enabling the protrusion 1211 to reflect incident light in multiple directions and improving the light absorption efficiency of the solar laminated battery 100. The structure of the protrusion 1211 in the form of a truncated pyramid is more stable, reduces the risk of stress concentration, and is easy to manufacture, thereby improving the stability and reliability of the solar laminated battery 100 as a whole.

[0077] As shown in FIG. 12, in a possible implementation, the width W1 of the first top wall 1211e along the second direction X satisfies: 500 nm≤W1≤5 μm, for example, 500 nm, 600 nm, 700 nm, 800 nm, 900 nm, 1 μm, 1.5 μm, 2 μm, 2.5 μm, 3 μm, 3.5 μm, 4 μm, 4.5 μm, or 5 μm. Figure 5 The width W2 of the first bottom wall 1211c along the second direction X satisfies: 500 nm≤W2≤5 μm. For example, 500 nm, 600 nm, 700 nm, 800 nm, 900 nm, 1 μm, 1.5 μm, 2 μm, 2.5 μm, 3 μm, 3.5 μm, 4 μm, 4.5 μm, or 5 μm.

[0078] As described above, the width of the first top wall 1211e along the second direction X is less than the width of the first bottom wall 1211c along the second direction X. By designing the width of the first top wall 1211e and the width of the second bottom wall, it is beneficial to increase the absorption effect of the perovskite layer 12 on sunlight while ensuring the stability of the structure of the protrusion 1211, thereby improving the stability and reliability of the solar laminated battery 100.

[0079] As described above, the width of the first top wall 1211e along the second direction X is less than the width of the first bottom wall 1211c along the second direction X. By designing the width of the first top wall 1211e and the width of the second bottom wall, it is beneficial to increase the absorption effect of the perovskite layer 12 on sunlight while ensuring the stability of the structure of the protrusion 1211, thereby improving the stability and reliability of the solar laminated battery 100.​

[0080] As shown in Figure 6 and Figure 7 In a possible implementation, the first textured structure 121 further includes recessed portions 1212, which are arranged alternately with the protruding portions 1211, and the cross-sectional shape of the recessed portions 1212 along the first direction Z is triangular, trapezoidal or arched.

[0081] Along the first direction Z, the depth of the recessed portions 1212 is equal to the height of the protruding portions 1211. The second transport layer 13 is arranged on the first textured structure 121 and extends into the recessed portions 1212, i.e., fills the recessed portions 1212. By limiting the shape of the recessed portions 1212, the second transport layer 13 is facilitated to fill the recessed portions 1212, the risk of a gap between the second transport layer 13 and the perovskite layer 12 is reduced, and the contact quality between the second transport layer 13 and the perovskite layer 12 is improved. At the same time, the recessed portions 1212 can reflect light, and by limiting the shape of the recessed portions 1212, the overall light absorption efficiency of the first textured structure 121 is also improved, thereby reducing the optical loss of the solar tandem cell 100.

[0082] As shown in Figure 6 In a possible implementation, one of the first transport layer 11 and the second transport layer 13 is an electron transport layer, and the other is a hole transport layer. When the first transport layer 11 is an electron transport layer and the second transport layer 13 is a hole transport layer, the top cell 10 is a formal perovskite cell (i.e., a positive perovskite cell), which has a simple preparation process and high efficiency. When the first transport layer 11 is a hole transport layer and the second transport layer 13 is an electron transport layer, the top cell 10 is a reverse perovskite cell (i.e., a negative perovskite cell), which has a simple preparation process, high structural stability, and is suitable for being stacked with a crystalline silicon cell (i.e., a bottom cell 20) to form the solar tandem cell 100.

[0083] The surface of the second transport layer 13 facing the transparent conductive layer 14 has a second textured structure 131. The shape of the second textured structure 131 is the same as that of the first textured structure 121, and the second transport layer 13 is provided with the second textured structure 131 to increase the surface area of the side surface of the second transport layer 13 facing the transparent conductive layer 14, thereby increasing the contact area between the second transport layer 13 and the transparent conductive layer 14. The transparent conductive layer 14 is used to collect and lead out the carriers inside the solar tandem cell 100, and the increase in the area of the second transport layer 13 and the transparent conductive layer 14 reduces the contact resistance between the second transport layer 13 and the transparent conductive layer 14, improves the collection efficiency of the carriers, and improves the short-circuit current and the fill factor of the solar tandem cell 100, thereby improving the efficiency of the solar tandem cell 100.

[0084] In this embodiment, the perovskite layer 12 has a first textured structure 121 and the second transport layer 13 has a second textured structure 131, thereby increasing the contact area between the perovskite layer 12 and the second transport layer 13 and between the second transport layer 13 and the transparent conductive layer 14. In other words, the contact area between the perovskite layer 12 and the transparent conductive layer 14 is increased, thereby improving the short-circuit current and fill factor of the solar tandem cell 100, and thus improving the efficiency of the solar tandem cell 100.

[0085] like Figure 6 As shown, in one possible implementation, the thickness D3 of the first transmission layer 11 along the first direction Z satisfies: 10nm≤D3≤40nm, for example 10nm, 15nm, 20nm, 25nm, 30nm, 35nm or 40nm, and of course other values ​​within the above range are also possible.

[0086] The thickness D4 of the second transport layer 13 along the first direction Z satisfies: 10nm≤D4≤30nm, for example, 10nm, 15nm, 20nm, 25nm or 30nm, or other values ​​within the above range.

[0087] If the thickness of the first transport layer 11 and the second transport layer 13 is too large, it will affect the carrier transport efficiency and the stability of the film structure of the first transport layer 11 and the second transport layer 13, making them prone to cracking. If the thickness of the first transport layer 11 and the second transport layer 13 is too small, it will affect the extraction of carriers, thereby affecting the efficiency of the solar tandem cell 100, and also affecting the mechanical strength of the first transport layer 11 and the second transport layer 13, reducing the stability of their film structure. Based on this, this application designs the thickness of the first transport layer 11 and the second transport layer 13 to improve the extraction and transport efficiency of carriers while ensuring the structural stability of the first transport layer 11 and the second transport layer 13, thereby improving the efficiency of the solar tandem cell 100 and extending its service life.

[0088] In another possible implementation, the thickness D3 of the first transport layer 11 along the first direction Z satisfies: 10nm ≤ D3 ≤ 40nm, or the thickness D4 of the second transport layer 13 along the first direction Z satisfies: 10nm ≤ D4 ≤ 30nm. In this embodiment, the solar tandem cell 100 satisfies at least one of the above conditions D3 and D4.

[0089] like Figure 6As shown, in one possible implementation, the solar tandem cell 100 further includes a protective layer 16 located along a first direction Z on the side of the transparent conductive layer 14 away from the second transmission layer 13, and the surface of the transparent conductive layer 14 facing the protective layer 16 has a third textured structure 141.

[0090] The shape of the third textured structure 141 can be the same as the shape of the first textured structure 121 and the second textured structure 131 described above. The transparent conductive layer 14 has the third textured structure 141 to reduce the light reflection loss of the solar tandem cell 100 and increase the light absorption efficiency of the solar tandem cell 100.

[0091] The protective layer 16 can be magnesium fluoride, which can improve the light absorption rate of the solar tandem cell 100 and also play a protective role, reducing the possibility of foreign objects such as water vapor entering the interior of the solar tandem cell 100 and improving the stability of the transparent conductive layer 14 and other film layers. The first electrode 15 mentioned above is the top electrode of the solar tandem cell 100. At least part of the structure of the first electrode 15 extends into the protective layer 16 and is electrically connected to the transparent conductive layer 14.

[0092] like Figure 6 As shown, in one possible implementation, the thickness D5 of the transparent conductive layer 14 along the first direction Z satisfies: 30nm≤D5≤100nm, for example 30nm, 40nm, 50nm, 60nm, 70nm, 80nm, 90nm or 100nm, or other values ​​within the above range.

[0093] If the thickness of the transparent conductive layer 14 is too large, it will affect the light transmittance of the transparent conductive layer 14, thereby affecting the light absorption rate of the solar tandem cell 100. If the thickness of the transparent conductive layer 14 is too small, it will affect the carrier collection efficiency, thereby affecting the efficiency of the solar energy. Therefore, the present application embodiment limits the thickness of the transparent conductive layer 14 in order to improve the carrier collection efficiency and improve the efficiency of the solar tandem cell 100 while ensuring the light transmittance of the transparent conductive layer 14.

[0094] The thickness D6 of the protective layer 16 along the first direction Z satisfies: 50nm ≤ D6 ≤ 200nm, such as 50nm, 60nm, 70nm, 80nm, 90nm, 100nm, 120nm, 140nm, 160nm, 180nm, or 200nm, or other values ​​within the above range. By designing the thickness of the protective layer 16, the stability of the film structure of the protective layer 16 is improved, reducing the risk of cracking, while providing reliable protection and reducing the possibility of moisture and other foreign matter intruding into the solar tandem cell 100, thereby extending the service life of the solar tandem cell 100.

[0095] In another possible implementation, the thickness D5 of the transparent conductive layer 14 along the first direction Z satisfies: 30 nm≤D5≤100 nm, or the thickness D6 of the protective layer 16 along the first direction Z satisfies: 50 nm≤D6≤200 nm, and the solar laminated cell 100 in the embodiment of the present application satisfies at least one of the above two conditions of D5 and D6.

[0096] As shown in Figure 6 In a possible implementation, the second electrode 22 is arranged on the side of the bottom cell 20 away from the composite layer 30, and the second electrode 22 is the bottom electrode of the solar laminated cell 100. The second electrode 22 can be sintered from metal paste, and the metal paste can include at least one of silver, palladium, copper, tin, gold, lead, or nickel.

[0097] The thickness D7 of the composite layer 30 along the first direction Z satisfies: 5 nm≤D7≤30 nm, for example, 5 nm, 10 nm, 15 nm, 20 nm, 25 nm, or 30 nm, and of course, other values within the above range are also possible. The composite layer 30 realizes the electrical connection between the top cell and the bottom cell 20, and by designing the thickness of the composite layer 30, the stability and reliability of the composite layer 30 itself are ensured, and the stable connection between the top cell 10 and the bottom cell 20 is ensured.

[0098] As mentioned above, the bottom cell 20 includes a substrate 21, and the thickness D8 of the substrate 21 of the bottom cell 20 satisfies: 100 μm≤D8≤260 μm, for example, 100 μm, 120 μm, 140 μm, 160 μm, 180 μm, 200 μm, 220 μm, 240 μm, or 260 μm, and of course, other values within the above range are also possible. By designing the thickness of the substrate 21 of the bottom cell 20, the bottom cell 20 can absorb the unused light of the top cell 10, improve the efficiency of the solar laminated cell 100, and at the same time, ensure the stability and reliability of the structure of the bottom cell 20 itself.

[0099] In another possible implementation, the thickness D7 of the composite layer 30 along the first direction Z satisfies: 5 nm≤D7≤30 nm, or the thickness D8 of the substrate 21 of the bottom cell 20 satisfies: 100 μm≤D8≤260 μm. The solar laminated cell 100 in the embodiment of the present application satisfies at least one of the above two conditions of D7 and D8.

[0100] The structure of the solar laminated cell is described in detail above, and the preparation method of the solar laminated cell will be introduced below by taking the first transport layer as a hole transport layer and the second transport layer as an electron transport layer, i.e., taking the top cell as an inverted perovskite cell.

[0101] As shown in Figure 6 and Figure 8As shown, the embodiment of the present application provides a preparation method of a solar laminated cell 100, comprising:

[0102] S1, preparing a substrate, the substrate comprising a bottom cell 20, a composite layer 30 and a first transport layer 11 arranged along a first direction Z.

[0103] Among them, the composite layer 30 can be formed on the bottom cell 20 by using a sputtering process, and the hole transport layer (i.e. the first transport layer 11) can be formed on the composite layer 30 by using an evaporation process or a spin coating process.

[0104] S2, forming a perovskite layer 12 with a thickness of D2 on the substrate 21 layer, the perovskite layer 12 being located on the side of the first transport layer 11 away from the composite layer 30.

[0105] Among them, the perovskite layer 12 can be prepared by using a method such as an evaporation process, a spin coating process or a doctor blade coating process, and the thickness D2 of the perovskite layer 12 can satisfy: 500nm≤D2≤1500nm.

[0106] S3, etching the perovskite layer 12 to form a first rough structure 121 on the surface of the perovskite layer 12 away from the substrate 21 layer, the first rough structure 121 comprising a plurality of protruding portions 1211 with a height of D1, and D1 and D2 satisfy: 0.1≤D1 / D2≤0.3.

[0107] The height D1 of the protruding portion 1211 can satisfy: 50nm≤D1≤500nm, and the technical effects of setting the first rough structure 121 and limiting the ratio of the height D1 of the protruding portion 1211 to the thickness D2 of the perovskite layer 12 have been described in detail above, and will not be described here.

[0108] S4, forming a second transport layer 13 on the first rough structure 121. The electron transport layer (i.e. the second transport layer 13) can be prepared by using a method such as an evaporation process, a spin coating process or a doctor blade coating process.

[0109] S5, forming a transparent conductive layer 14 on the second transport layer 13. The transparent conductive layer 14 can be prepared by using an evaporation process or a sputtering process.

[0110] S6, forming a first electrode 15 on the transparent conductive layer 14. The first electrode 15 can be sintered from metal paste.

[0111] In some embodiments, when the hole transport layer is prepared by using a spin coating process, the spin coating speed is 3000rpm to 4000rpm, and the spin coating time is 20s to 35s. After the spin coating step is completed, an annealing treatment can be performed, the annealing temperature is 80° to 115°, and the annealing time is 10min to 15min.

[0112] In some embodiments, when the perovskite layer is prepared by using a spin coating process, the spin coating speed is 3000 rpm to 4000 rpm, and the spin coating time is 30 s to 45 s. After the spin coating step, an annealing process can be performed, the annealing temperature is 90° to 110°, and the annealing time is 10 min to 15 min.

[0113] In a possible implementation, before the step of forming the second transport layer on the first textured structure, the method for preparing the solar laminated cell further comprises:

[0114] cleaning the first textured structure.

[0115] By cleaning the first textured structure, residues in the previous etching process are removed, a good interface is provided for the preparation of the second transport layer, and the forming quality of the second transport layer is improved.

[0116] In a possible implementation, the step of cleaning the first textured structure specifically comprises:

[0117] spin coating a cleaning solution on the first textured structure, the spin coating speed V satisfies: 4000 rpm≤V≤5000 rpm, and the spin coating time t1 satisfies: 5 s≤t1≤15 s.

[0118] annealing the first textured structure, the annealing temperature T satisfies: 85℃≤T≤115℃, and the annealing time t2 satisfies: 5 min≤t2≤10 min.

[0119] The cleaning solution can contain a DMF solution, a DMSO solution, and an IPA solution. The cleaning solution can remove residues in the previous etching process, and at the same time, the cleaning solution can also etch the first textured structure, with an etching depth of about 5 nm to 15 nm, to optimize the morphology of the first textured structure. The annealing process is beneficial to repairing damage caused by the etching process and improving the quality of the first textured structure.

[0120] In a possible implementation, the etching process for etching the perovskite layer is plasma etching, ion beam etching, or focused ion beam etching.

[0121] Plasma etching, ion beam etching, and focused ion beam etching are all dry etching processes. Using a dry etching process is beneficial to accurately controlling the morphology of the first textured structure, so as to improve the forming quality of the first textured structure.

[0122] As shown in FIG. 1, Figure 6 In a possible implementation, the step of forming the second transport layer 13 on the first textured structure 121 comprises:

[0123] The second transport layer 13 is formed to have a thickness D4 satisfying 10 nm≤D4≤30 nm, and a second surface of the second transport layer 13 away from the perovskite layer 12 has a second textured structure 131.

[0124] The technical effects of the thickness design of the second transport layer 13 and the technical effects of the second textured structure 131 are described in detail above, and will not be repeated here.

[0125] Continuing as shown in Figure 6 In a possible implementation, the step of forming the transparent conductive layer 14 on the second transport layer 13 includes:

[0126] The transparent conductive layer 14 is formed to have a thickness D5 satisfying 30 nm≤D5≤100 nm, and a third surface of the transparent conductive layer 14 away from the perovskite layer 12 has a third textured structure 141.

[0127] The technical effects of the thickness design of the transparent conductive layer 14 and the technical effects of the third textured structure 141 are described in detail above, and will not be repeated here.

[0128] As shown in Figure 9 The present application also provides a photovoltaic module 1000, which includes a cover plate, an encapsulation layer, and a cell string 1003. The cell string 1003 includes a plurality of the above-mentioned solar laminated cells.

[0129] The cover plate at the top of the photovoltaic module 1000 is a first cover plate 1001, the cover plate at the bottom of the photovoltaic module 1000 is a second cover plate 1005, the encapsulation layer between the first cover plate 1001 and the cell string 1003 is a first encapsulation layer 1002, and the encapsulation layer between the second cover plate 1005 and the cell string 1003 is a second encapsulation layer 1004. The first cover plate 1001, the first encapsulation layer 1002, the cell string 1003, the second encapsulation layer 1004, and the second cover plate 1005 can be arranged along the thickness direction of the photovoltaic module 1000 and laminated together. The first cover plate 1001 can be a glass cover plate, and the first cover plate 1001 has a high light transmittance. The first encapsulation layer 1002 bonds the first cover plate 1001 and the cell string 1003 together to protect the cell string 1003, and the material of the first encapsulation layer 1002 can be one or more of ethylene-vinyl acetate copolymer (EVA), polyolefin elastomer (POE), and polyvinyl butyral (PVB). The second encapsulation layer 1004 connects the cell string 1003 and the second cover plate 1005 together, and also protects the cell string 1003, and the material of the second encapsulation layer 1004 can be one or more of the above-mentioned EVA, POE, and PVB. The material of the second cover plate 1005 can be glass, or the second cover plate 1005 can also be composed of a plurality of polymer film layers.

[0130] The above only is optional embodiment of the present application, and is not used to limit the present application, for the person skilled in the art, the present application can have various changes and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A solar tandem battery, characterized in that, It includes a bottom battery and a top battery stacked along a first direction, with a composite layer disposed between the bottom battery and the top battery; The top battery includes a first transport layer, a perovskite layer, a second transport layer, a transparent conductive layer, and a first electrode arranged along the first direction; The surface of the perovskite layer facing the transparent conductive layer has a first textured structure. The first textured structure includes a plurality of protrusions. The height of the protrusions along the first direction is D1, and the thickness of the perovskite layer along the first direction is D2. D1 and D2 satisfy: 0.1≤D1 / D2≤0.

3. The protrusion includes a first top wall, a first bottom wall, and a first side wall connected to both sides of the first bottom wall along a second direction. The first top wall and the first bottom wall are arranged along the first direction, and the first top wall is connected to the first side wall. The width of the first top wall along the second direction is smaller than the width of the first bottom wall along the second direction.

2. The solar tandem battery according to claim 1, characterized in that, The height D1 of the protrusion along the first direction satisfies: 50nm≤D1≤500nm, and / or; The thickness D2 of the perovskite layer along the first direction satisfies: 500nm ≤ D2 ≤ 1500nm.

3. The solar tandem battery according to claim 1, characterized in that, The included angle α between the first sidewall and the first bottom wall satisfies: 35°≤α≤65°.

4. The solar tandem battery according to claim 3, characterized in that, The width W1 of the first top wall along the second direction satisfies: 500nm≤W1≤5μm; The width W2 of the first bottom wall along the second direction satisfies: 500nm≤W2≤5μm.

5. The solar tandem cell according to any one of claims 1 to 4, characterized in that, The first velvet structure also includes recessed portions, which are alternately arranged with the raised portions; The cross-sectional shape of the recessed portion along the first direction is triangular, trapezoidal, or arched.

6. The solar tandem cell according to any one of claims 1 to 4, characterized in that, One of the first transport layer and the second transport layer is an electron transport layer, and the other is a hole transport layer; The surface of the second transport layer facing the transparent conductive layer has a second textured surface.

7. The solar tandem cell according to claim 6, characterized in that, The thickness D3 of the first transport layer along the first direction satisfies: 10nm≤D3≤40nm, and / or; The thickness D4 of the second transport layer along the first direction satisfies: 10nm≤D4≤30nm.

8. The solar tandem battery according to claim 6, characterized in that, The solar tandem battery also includes a protective layer; The protective layer is located along the first direction on the side of the transparent conductive layer away from the second transmission layer; the surface of the transparent conductive layer facing the protective layer has a third textured surface structure.

9. The solar tandem battery according to claim 8, characterized in that, The thickness D5 of the transparent conductive layer along the first direction satisfies: 30nm≤D5≤100nm, and / or; The thickness D6 of the protective layer along the first direction satisfies: 50nm ≤ D6 ≤ 200nm.

10. The solar tandem cell according to any one of claims 1 to 4, characterized in that, A second electrode is provided on the side of the bottom battery opposite to the composite layer; The thickness D7 of the composite layer along the first direction satisfies: 5nm≤D7≤30nm, and / or; The thickness D8 of the substrate of the bottom battery satisfies: 100μm≤D8≤260μm.

11. A photovoltaic module, characterized in that, This includes the cover plate, encapsulation layer, and battery string; The battery string includes a plurality of solar tandem cells as described in any one of claims 1 to 10.

12. A method for preparing a solar tandem cell, characterized in that, include: A substrate is prepared, the substrate comprising a bottom cell, a composite layer, and a first transport layer arranged along a first direction; A perovskite layer with a thickness of D2 is formed on the substrate, and the perovskite layer is located on the side of the first transport layer away from the composite layer; The perovskite layer is etched to form a first textured structure on the surface of the perovskite layer opposite to the substrate. The first textured structure includes a plurality of protrusions with a height of D1, where D1 and D2 satisfy: 0.1 ≤ D1 / D2 ≤ 0.

3. Each protrusion includes a first top wall, a first bottom wall, and a first side wall connected to both sides of the first bottom wall along a second direction. The first top wall and the first bottom wall are arranged along the first direction, and the first top wall is connected to the first side wall. The width of the first top wall along the second direction is smaller than the width of the first bottom wall along the second direction. A second transport layer is formed on the first velvet structure; A transparent conductive layer is formed on the second transport layer; A first electrode is formed on the transparent conductive layer.

13. The method for preparing a solar tandem cell according to claim 12, characterized in that, Before the step of forming the second transport layer on the first textured structure, the method for fabricating the solar tandem cell further includes: The first velvet structure is cleaned.

14. The method for preparing a solar tandem cell according to claim 13, characterized in that, The step of cleaning the first velvet structure includes: A cleaning solution is spin-coated onto the first velvety structure. The spin-coating speed V satisfies: 4000rpm≤V≤5000rpm, and the spin-coating time t1 satisfies: 5s≤t1≤15s. The first velvet structure is annealed, and the annealing temperature T satisfies: 85℃≤T≤115℃, and the annealing time t2 satisfies: 5min≤t2≤10min.

15. The method for preparing a solar tandem cell according to any one of claims 12 to 14, characterized in that, The etching process for etching the perovskite layer is plasma etching, ion beam etching, or focused ion beam etching.

16. The method for preparing a solar tandem cell according to any one of claims 12 to 14, characterized in that, The step of forming the second transport layer on the first velvet structure includes: A second transport layer with a thickness D4 is formed, satisfying: 10nm≤D4≤30nm, and the surface of the second transport layer away from the perovskite layer has a second textured structure.

17. The method for preparing a solar tandem cell according to claim 16, characterized in that, The step of forming a transparent conductive layer on the second transport layer includes: A transparent conductive layer with a thickness D5 is formed, satisfying 30nm≤D5≤100nm, and the surface of the transparent conductive layer opposite to the perovskite layer has a third textured structure.

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