A laminated solar cell and a method for preparing the same

Abstract

The present application discloses a stacked solar cell and a preparation method thereof, which relates to the technical field of solar cells, including: a silicon heterojunction solar cell; a perovskite solar cell located on the light-incident side of the silicon heterojunction solar cell; the silicon heterojunction solar cell includes: a crystalline silicon substrate, the crystalline silicon substrate having a first surface and a second surface opposite to each other, the first surface facing the perovskite solar cell; a first organic passivation layer located on the first surface; a second organic passivation layer located on the second surface; a hole selection contact layer located on the surface of the first organic passivation layer, the hole selection contact layer and the first organic passivation layer and the first surface of the crystalline silicon substrate form a first heterojunction; an electron selection contact layer located on the surface of the second organic passivation layer, the electron selection contact layer and the second organic passivation layer and the second surface of the crystalline silicon substrate form a second heterojunction. The technical solution of the present application can reduce parasitic absorption, reduce the difficulty of the passivation process and the preparation cost.

Description

Technical Field

[0001] The present application relates to the technical field of solar cells, and in particular to a stacked solar cell and a method for preparing the same. Background Art

[0002] At present, perovskite / silicon tandem solar cells achieve optimal spectrum utilization by stacking wide-bandgap perovskite top cells and narrow-bandgap crystalline silicon bottom cells, becoming one of the most promising research directions for the future development of ultra-high efficiency solar cells. In conventional perovskite / silicon tandem solar cells, the bottom cell mainly uses undoped intrinsic amorphous silicon to passivate the surface of the crystalline silicon substrate.

[0003] In conventional perovskite / silicon tandem solar cells, the surface defects of the crystalline silicon substrate are passivated based on amorphous silicon, which results in a large parasitic absorption problem, thus affecting the photoelectric conversion efficiency. Summary of the invention

[0004] In view of the above problems, the present application provides a stacked solar cell and a method for preparing the same, the specific scheme is as follows:

[0005] The first aspect of the present application provides a stacked solar cell, comprising:

[0006] Silicon heterojunction solar cells;

[0007] Perovskite solar cell on the light-incoming side of a silicon heterojunction solar cell;

[0008] Among them, silicon heterojunction solar cells include:

[0009] A crystalline silicon substrate, wherein the crystalline silicon substrate has a first surface and a second surface opposite to each other, wherein the first surface faces the perovskite solar cell;

[0010] a first organic passivation layer located on the first surface;

[0011] a second organic passivation layer on the second surface;

[0012] A hole selection contact layer is located on the surface of the first organic passivation layer, and the hole selection contact layer forms a first heterojunction with the first organic passivation layer and the first surface of the crystalline silicon substrate;

[0013] The electron selective contact layer is located on the surface of the second organic passivation layer, and the electron selective contact layer, the second organic passivation layer and the second surface of the crystalline silicon substrate form a second heterojunction.

[0014] Optionally, in the above-mentioned stacked solar cell, the first heterojunction and the second heterojunction are asymmetric structures.

[0015] Optionally, in the above-mentioned stacked solar cell, the crystalline silicon substrate is N-type doped crystalline silicon, the hole selective contact layer and the electron selective contact layer are both non-silicon inorganic materials, and the hole selective contact layer and the electron selective contact layer are different non-silicon inorganic materials.

[0016] Optionally, in the above-mentioned tandem solar cell, the hole selective contact layer comprises NiO x 、MoO x and V 2 O 5 Any of;

[0017] The electron selective contact layer includes ZnS, TiO 2 , MgO and LiF.

[0018] Optionally, in the above-mentioned stacked solar cell, the first organic passivation layer and the second organic passivation layer have different thicknesses;

[0019] And / or, the thickness of the hole selective contact layer is different from the thickness of the electron selective contact layer.

[0020] Optionally, in the above-mentioned stacked solar cell, the thickness of the first organic passivation layer is less than the thickness of the second organic passivation layer.

[0021] Optionally, in the above-mentioned stacked solar cell, the thickness of the hole selective contact layer is smaller than the thickness of the electron selective contact layer.

[0022] Optionally, in the above-mentioned stacked solar cell, the first organic passivation layer and the hole selective contact layer are both spin-coated film layers;

[0023] And / or, the second organic passivation layer and the electron selective contact layer are both spin-coated film layers.

[0024] Optionally, in the above-mentioned tandem solar cell, the tandem solar cell includes at least one of the following structures:

[0025] The thickness of the first organic passivation layer and the thickness of the second organic passivation layer are both in the range of 2nm to 10nm;

[0026] The thickness of the hole selective contact layer and the thickness of the electron selective contact layer are both in the range of 10nm to 30nm;

[0027] The silicon heterojunction solar cell and the perovskite solar cell are connected and fixed via a light-transmitting composite connection layer, and the composite connection layer is uniformly mixed with ultraviolet filter materials.

[0028] The present application secondly provides a method for preparing the above-mentioned laminated solar cell, comprising:

[0029] Preparation of silicon heterojunction solar cells;

[0030] The perovskite solar cell is bonded and fixed on the light incident side of the silicon heterojunction solar cell;

[0031] Among them, silicon heterojunction solar cells include:

[0032] A crystalline silicon substrate, wherein the crystalline silicon substrate has a first surface and a second surface opposite to each other, wherein the first surface faces the perovskite solar cell;

[0033] a first organic passivation layer located on the first surface;

[0034] a second organic passivation layer on the second surface;

[0035] A hole selection contact layer is located on the surface of the first organic passivation layer, and the hole selection contact layer forms a first heterojunction with the first organic passivation layer and the first surface of the crystalline silicon substrate;

[0036] The electron selective contact layer is located on the surface of the second organic passivation layer, and the electron selective contact layer, the second organic passivation layer and the second surface of the crystalline silicon substrate form a second heterojunction.

[0037] Optionally, in the above preparation method, an organic passivation material is spin-coated on the first surface and the second surface respectively to form a first organic passivation layer and a second organic passivation layer;

[0038] A hole selective contact layer is formed on the surface of the first organic passivation layer, and an electron selective contact layer is formed on the surface of the second organic passivation layer by a spin coating method, respectively.

[0039] By means of the above technical scheme, in the stacked solar cell and its preparation method provided by the present application, the silicon heterojunction solar cell realizes surface passivation through organic materials to form a first organic passivation layer and a second organic passivation layer on the first surface and the second surface respectively, which can realize low-temperature passivation of the surface of the crystalline silicon substrate, improve the surface passivation effect, and reduce the difficulty of the passivation process and the preparation cost. In addition, on the side of the crystalline silicon substrate facing the first surface, a first heterojunction is formed based on the hole selection contact layer, the first organic passivation layer and the first surface, and on the side of the crystalline silicon substrate facing the second surface, a second heterojunction is formed based on the electron selection contact layer, the second organic passivation layer and the second surface. In the heterojunction, the parasitic absorption problem of amorphous silicon is solved, and the photoelectric conversion efficiency can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the related technologies, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0041] The structures, proportions, sizes, etc. illustrated in the drawings of this specification are only used to match the contents disclosed in the specification so as to facilitate understanding and reading by persons familiar with this technology. They are not used to limit the conditions under which this application can be implemented, and therefore have no substantive technical significance. Any structural modification, change in proportion or adjustment of size, without affecting the effects and purposes that can be achieved by this application, should still fall within the scope of the technical contents disclosed in this application.

[0042] Figure 1 A schematic diagram of the structure of a silicon heterojunction solar cell in a perovskite / silicon tandem solar cell;

[0043] Figure 2 A schematic diagram of the structure of a stacked solar cell provided in an embodiment of the present application;

[0044] Figure 3 for Figure 2 A schematic diagram of the structure of a silicon heterojunction solar cell in a stacked solar cell is shown;

[0045] Figure 4 A schematic diagram of a process for preparing a stacked solar cell provided in an embodiment of the present application.

[0046] Reference numerals:

[0047] 11-crystalline silicon substrate; 111-first surface; 112-second surface; 12-first intrinsic amorphous silicon film; 13-second intrinsic amorphous silicon film; 14-P-type doped amorphous silicon film; 15-N-type doped amorphous silicon film; 16-first transparent conductive layer; 17-second transparent conductive layer; 18-first electrode; 19-second electrode; 20-composite connection layer; 100-silicon heterojunction solar cell; 200-perovskite solar cell; 21-first organic passivation layer; 22-second organic passivation layer; 23-hole selective contact layer; 24-electron selective contact layer. DETAILED DESCRIPTION

[0048] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the embodiments of the present application. It is known to those skilled in the art that with the development of technology and the emergence of new scenarios, the technical solutions provided in the embodiments of the present application are also applicable to similar technical problems.

[0049] Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of the present application. The terms used in the embodiments of the present application are only used to explain the specific embodiments of the present application, and are not intended to limit the present application.

[0050] refer to Figure 1 , Figure 1 The schematic diagram of the structure of a silicon heterojunction solar cell in a perovskite / silicon tandem solar cell is shown. The silicon heterojunction solar cell (Silicon Heterojunction Solar Cell, referred to as SHJ) includes:

[0051] A crystalline silicon substrate 11;

[0052] A first intrinsic amorphous silicon thin film 12 located on one side surface of the crystalline silicon substrate 11;

[0053] A second intrinsic amorphous silicon thin film 13 located on the other side surface opposite to the crystalline silicon substrate 11;

[0054] A P-type doped amorphous silicon film 14 located on the surface of the first intrinsic amorphous silicon film 12;

[0055] an N-type doped amorphous silicon film 15 located on the surface of the second intrinsic amorphous silicon film 13;

[0056] A first transparent conductive layer 16 is located on the surface of the P-type doped amorphous silicon film 14, and a first electrode 18 is disposed on the surface of the first transparent conductive layer 16;

[0057] The second transparent conductive layer 17 is located on the surface of the N-type doped amorphous silicon film 15 , and a second electrode 19 is disposed on the surface of the second transparent conductive layer 17 .

[0058] The P-type doping may be boron doping, and the N-type doping may be phosphorus doping. The doping method may also be implemented by using other elements, and the embodiment of the present application does not limit the doping elements.

[0059] Optionally, the thickness of the P-type doped amorphous silicon film 14 and the N-type doped amorphous silicon film 15 may be 10 nm. The thickness of the first intrinsic amorphous silicon film 12 and the second intrinsic amorphous silicon film 13 may be 5 nm.

[0060] exist Figure 1In the silicon heterojunction solar cell shown, the upper and lower surfaces of the crystalline silicon substrate 11 are respectively passivated by the first intrinsic amorphous silicon film 12 and the second intrinsic amorphous silicon film 13 as passivation layers to achieve surface passivation of the crystalline silicon substrate 11. In addition, in the silicon heterojunction solar cell, the P-type doped amorphous silicon film 14 is used as a hole selection contact layer, and the N-type doped amorphous silicon film 15 is used as an electron selection contact layer, so that a top heterojunction is formed on the upper surface of the crystalline silicon substrate 11 based on the P-type doped amorphous silicon film 14, the first intrinsic amorphous silicon film 12 and the upper surface of the crystalline silicon substrate 11, and a bottom heterojunction is formed on the lower surface of the crystalline silicon substrate 11 based on the N-type doped amorphous silicon film 15, the second intrinsic amorphous silicon film 13 and the lower surface of the crystalline silicon substrate 11.

[0061] like Figure 1 As shown, a layer of intrinsic amorphous silicon film and a layer of doped amorphous silicon film are required to passivate the substrate surface and form a heterojunction on the upper and lower surfaces (first surface 111 and second surface 112) of the crystalline silicon substrate 11. The heterojunction formed on the upper and lower surfaces of the crystalline silicon substrate 11 is a symmetrical structure, and requires a P-type doped and N-type doped amorphous silicon films to serve as a selective contact layer for carrier selective transmission.

[0062] Silicon heterojunction solar cells achieve surface passivation of the substrate based on intrinsic amorphous silicon thin films, and construct heterojunctions based on doped amorphous silicon to achieve selective carrier transmission, which can reduce the surface recombination rate of carriers on the crystalline silicon substrate 11, and can achieve industrial thin-film SHJ cells, so that the cell components have a lower temperature coefficient (about 0.258%), and can also reduce light-induced degradation and increase battery life.

[0063] However, due to the small band gap width (about 1.7eV) of intrinsic amorphous silicon film and doped amorphous silicon film, it will cause a large parasitic absorption problem, which restricts the improvement of battery short-circuit current (Jsc). Experiments show that amorphous silicon materials will cause the loss of spectral response below 600nm, resulting in 2.1mA / cm 2 The loss of short-circuit current is converted into an efficiency loss of 5%. In addition, the preparation of amorphous silicon thin film requires a high-temperature vacuum process, which increases the difficulty and cost of battery preparation.

[0064] In order to solve the above problems, the embodiment of the present application provides a stacked solar cell, in which the silicon heterojunction solar cell realizes surface passivation through organic materials to form a first organic passivation layer and a second organic passivation layer on the first surface and the second surface respectively, which can realize low-temperature passivation of the surface of the crystalline silicon substrate, improve the surface passivation effect, and reduce the difficulty of the passivation process and the preparation cost. In addition, on the side of the crystalline silicon substrate facing the first surface, a first heterojunction is formed based on the hole selection contact layer, the first organic passivation layer and the first surface, and on the side of the crystalline silicon substrate facing the second surface, a second heterojunction is formed based on the electron selection contact layer, the second organic passivation layer and the second surface. In the heterojunction, the parasitic absorption problem of amorphous silicon is solved, and the photoelectric conversion efficiency can be improved.

[0065] The above is the core inventive concept of the present application. In order to make the above-mentioned objects, features and advantages of the present application more obvious and easy to understand, the present application is further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0066] refer to Figure 2 and Figure 3 , Figure 2 A schematic diagram of the structure of a stacked solar cell provided in an embodiment of the present application, Figure 3 for Figure 2 Schematic diagram of the structure of a silicon heterojunction solar cell in a stacked solar cell.

[0067] like Figure 2 As shown, the stacked solar cell includes: a silicon heterojunction solar cell 100; and a perovskite solar cell 200 located on the light incident side of the silicon heterojunction solar cell 100.

[0068] The silicon heterojunction solar cell 100 and the perovskite solar cell 200 are connected and fixed by a light-transmitting composite connection layer 20. The perovskite solar cell 200 is bonded and fixed to the light-incident side of the silicon heterojunction solar cell 100 based on the light-transmitting composite connection layer 20, which can not only realize the stacking and bonding of the two solar cells, but also ensure good light transmittance, so that the light not absorbed by the perovskite solar cell 200 can be incident on the silicon heterojunction solar cell 100, so that the silicon heterojunction solar cell 100 performs photovoltaic power generation. The composite connection layer 20 may include a transparent colloidal material.

[0069] The perovskite solar cell 200 can absorb light in the first band for photovoltaic power generation, and the silicon heterojunction solar cell 100 can absorb light in the second band for photovoltaic power generation. The second band is at least partially outside the spectrum of the first band, so a portion of the light can pass through the perovskite solar cell 200 and then be absorbed by the silicon heterojunction solar cell 100 for photovoltaic power generation, which can increase the spectrum range of the overall photovoltaic power generation of the stacked solar cell.

[0070] Optionally, the first wavelength band includes 300nm~700nm, and the second wavelength band includes 700nm~1200nm.

[0071] The potential negative impact of ultraviolet (UV) radiation on the performance of silicon heterojunction solar cells 100 is mainly reflected in performance degradation. UV radiation can cause surface degradation of silicon heterojunction solar cells 100, and this degradation phenomenon usually leads to a significant decrease in power output and a reduction in photovoltaic efficiency.

[0072] In the embodiment of the present application, the perovskite solar cell 200 can absorb ultraviolet light to generate photovoltaic power. The perovskite solar cell 200 is arranged on the light incident side of the silicon heterojunction solar cell 100, and the perovskite solar cell 200 can filter out ultraviolet light for the silicon heterojunction solar cell 100 to reduce the irradiation damage of ultraviolet light to the silicon heterojunction solar cell 100.

[0073] Optionally, in order to further reduce the irradiation damage of ultraviolet light to the silicon heterojunction solar cell 100, an ultraviolet filter material may be uniformly mixed in the composite connection layer 20. The ultraviolet filter material includes at least one of magnesium fluoride, polyvinyl cinnamate, diazo compounds, nano-alumina, and nano-titanium dioxide.

[0074] Combination Figure 2 and Figure 3 As shown, based on any of the above embodiments, the silicon heterojunction solar cell 100 includes:

[0075] A crystalline silicon substrate 11, wherein the crystalline silicon substrate 11 has a first surface 111 and a second surface 112 opposite to each other, wherein the first surface 111 faces the perovskite solar cell 200;

[0076] A first organic passivation layer 21 located on the first surface 111;

[0077] A second organic passivation layer 22 located on the second surface 112;

[0078] A hole selective contact layer 23 located on the surface of the first organic passivation layer 21, wherein the hole selective contact layer 23 forms a first heterojunction with the first organic passivation layer 21 and the first surface 111 of the crystalline silicon substrate 11;

[0079] The electron selective contact layer 24 is located on the surface of the second organic passivation layer 22 , and the electron selective contact layer 24 forms a second heterojunction with the second organic passivation layer 22 and the second surface 112 of the crystalline silicon substrate 11 .

[0080] In the embodiment of the present application, the silicon heterojunction solar cell 100 realizes surface passivation through organic materials to form a first organic passivation layer 21 and a second organic passivation layer 22 on the first surface 111 and the second surface 112, respectively, so as to realize low-temperature passivation of the surface of the crystalline silicon substrate 11, improve the surface passivation effect, and reduce the difficulty of the passivation process and the preparation cost. In addition, on the side of the crystalline silicon substrate 11 facing the first surface 111, a first heterojunction is formed based on the hole selection contact layer 23, the first organic passivation layer 21 and the first surface 111, and on the side of the crystalline silicon substrate 11 facing the second surface 112, a second heterojunction is formed based on the electron selection contact layer 24, the second organic passivation layer 22 and the second surface 112. In the heterojunction, the parasitic absorption problem of amorphous silicon is solved, and the photoelectric conversion efficiency can be improved.

[0081] Optionally, a first transparent conductive layer 16 is disposed on the surface of the hole selective contact layer 23, and a second transparent conductive layer 17 is disposed on the surface of the electron selective contact layer. A first electrode 18 is disposed on the surface of the first transparent conductive layer 16, and a second electrode 19 is disposed on the surface of the second transparent conductive layer 17. The first transparent conductive layer 16 and the second transparent conductive layer 17 may be a transparent conductive oxide material (Transparent Conductive Oxide, referred to as TCO). Both the first electrode 18 and the second electrode 19 may be Ag electrodes.

[0082] The first transparent conductive layer 16 and the second transparent conductive layer 17 are surface electrodes, which can collect current well and collect it to the first electrode 18 and the second electrode 19. The first electrode 18 and the second electrode 19 are respectively located on the surface of the first transparent conductive layer 16 and the second transparent conductive layer 17, and are directly in electrical contact with the transparent conductive layer without sintering.

[0083] As mentioned above, Figure 1 In the silicon heterojunction solar cell shown, the heterojunctions on both sides of the crystalline silicon substrate 11 are symmetrical structures, and it is necessary to make the two heterojunctions use the same material. For example, it is necessary that all film layers constituting the heterojunction are made of amorphous silicon materials, and it is also necessary that the thicknesses of the corresponding film layers of the two heterojunctions are the same. For example, it is necessary that the thicknesses of the first intrinsic amorphous silicon film 12 and the second intrinsic amorphous silicon film 13 are the same, and it is necessary that the thicknesses of the P-type doped amorphous silicon film 14 and the N-type doped amorphous silicon film 15 are the same. These associated settings make it impossible to independently set the heterojunctions on both sides of the crystalline silicon substrate 11, which is not convenient for optimizing the performance of the silicon heterojunction solar cell.

[0084] In one implementation of the present application, the first heterojunction and the second heterojunction may be set to an asymmetric structure. In this way, the film layer design schemes in the first heterojunction and the second heterojunction may be independently adjusted to further optimize the performance of the silicon heterojunction solar cell.

[0085] The first heterojunction and the second heterojunction are asymmetric structures, including at least one of the following aspects: the first organic passivation layer 21 and the second organic passivation layer 22 are different, and the hole selective contact layer 23 and the electron selective contact layer 24 are different.

[0086] The first organic passivation layer 21 and the second organic passivation layer 22 are different, including that the materials of the first organic passivation layer 21 and the second organic passivation layer 22 are different, and / or the thicknesses of the first organic passivation layer 21 and the second organic passivation layer 22 are different. The hole selection contact layer 23 and the electron selection contact layer 24 are different, including that the materials of the hole selection contact layer 23 and the electron selection contact layer 24 are different, and / or the thicknesses of the hole selection contact layer 23 and the electron selection contact layer 24 are different.

[0087] In the embodiment of the present application, the film material and / or film thickness in the first heterojunction and the second heterojunction can be set to form asymmetric structures of the first heterojunction and the second heterojunction, so as to independently optimize the heterojunction performance on both sides of the crystalline silicon substrate 11, thereby further improving the performance of the silicon heterojunction solar cell.

[0088] In one implementation of the embodiment of the present application, the crystalline silicon substrate 11 can be set to be N-type doped crystalline silicon, the hole selection contact layer 23 and the electron selection contact layer 24 are both non-silicon inorganic materials, and the hole selection contact layer 23 and the electron selection contact layer 24 are different non-silicon inorganic materials. In this way, compared with the method of forming a heterojunction with the crystalline silicon substrate 11 by doping amorphous silicon, the first surface 111 and the second surface 112 form a heterojunction based on different non-silicon inorganic materials, respectively, and the hole selection contact layer 23 and the electron selection contact layer 24 do not need to be doped, which can reduce the difficulty of the battery preparation process and reduce the preparation cost.

[0089] In addition, since the hole selective contact layer 23 and the electron selective contact layer 24 are different non-silicon inorganic materials, inorganic non-materials that are adapted to hole selective transmission and electron selective transmission can be selected as the hole selective contact layer 23 and the electron selective contact layer 24 respectively. This can enable the hole selective contact layer 23 and the electron selective contact layer 24 to better adapt to carrier selective transmission, thereby improving the performance of the battery.

[0090] Optionally, the hole selective contact layer 23 comprises NiO x 、MoO x and V 2 O 5 Any of the following. Using NiO x 、MoO x and V 2 O 5The hole selection contact layer 23 is prepared by any one of the methods, which can not only realize an effective hole selection transmission effect, but also form a first heterojunction with good performance on the first surface 111. Compared with the scheme of forming a heterojunction with an amorphous silicon thin film, the parasitic absorption problem of the amorphous silicon material can be effectively prevented on the first surface 111.

[0091] Optionally, the electron selective contact layer 24 includes ZnS, TiO 2 , MgO and LiF. ZnS, TiO 2 The electron selective contact layer 24 is prepared by using any one of MgO and LiF, which can not only achieve effective electron selective transmission effect, but also form a second heterojunction with good performance on the second surface 112. Compared with the solution of forming a heterojunction with amorphous silicon thin film, it can effectively optimize the red light management on the back side of the silicon heterojunction solar cell on the second surface 112 and improve the battery performance.

[0092] Based on any of the above implementations, the thicknesses of the first organic passivation layer 21 and the second organic passivation layer 22 may be different.

[0093] If the thicknesses of the first organic passivation layer 21 and the second organic passivation layer 22 are different, the first heterojunction and the second heterojunction can be made into an asymmetric structure, so that the battery performance can be optimized and adjusted.

[0094] In any implementation of the embodiments of the present application, the thickness of the first organic passivation layer 21 and the thickness of the second organic passivation layer 22 are both in the range of 2nm to 10nm. The thickness of the organic passivation layer is set to be in the range of 2nm to 10nm, which can effectively passivate the surface of the crystalline silicon substrate 11 while preventing the organic passivation layer from being too thick to affect carrier tunneling, so as to ensure the photoelectric conversion efficiency.

[0095] In any implementation of the embodiments of the present application, the thickness of the first organic passivation layer 21 may be set to be smaller than the thickness of the second organic passivation layer 22 .

[0096] Since the first organic passivation layer 21 is closer to the light incident side of the silicon heterojunction solar cell, the thickness of the first organic passivation layer 21 is set to be smaller than the thickness of the second organic passivation layer 22, so that the thicknesses of the two organic passivation layers can be adapted to the distances from the light incident side of the silicon heterojunction solar cell, respectively. While effectively passivating the two surfaces of the crystalline silicon substrate 11, the two organic passivation layers each have a good carrier tunneling effect.

[0097] Optionally, the thickness of the first organic passivation layer 21 is set to H1, and the thickness of the second organic passivation layer 22 is set to H2. The thickness ratio H1 / H2 of the first organic passivation layer 21 to the second organic passivation layer 22 may be set to be less than 1 and not less than 1 / 3.

[0098] In the silicon heterojunction solar cell 100, light is incident from one side of the first heterojunction, the thickness of the first organic passivation layer 21 is set to be less than the thickness of the second organic passivation layer 22, and H1 / H2 is not less than 1 / 3. Compared with the implementation method in which H1 is equal to H2, the carrier tunneling effect in the first heterojunction and the second heterojunction can be further improved, thereby improving the battery performance.

[0099] Based on any of the above embodiments, the thickness of the hole selective contact layer 23 and the thickness of the electron selective contact layer 24 may be different.

[0100] In any implementation of the embodiments of the present application, the thickness of the hole selective contact layer 23 is smaller than the thickness of the electron selective contact layer 24 .

[0101] Since the hole selection contact layer 23 is closer to the light incident side of the silicon heterojunction solar cell, the thickness of the hole selection contact layer 23 is set to be smaller than the thickness of the electron selection contact layer 24, so that the thicknesses of the two carrier selection transport layers (the hole selection contact layer 23 and the electron selection contact layer 24) can be adapted to the distances from the light incident side of the silicon heterojunction solar cell, respectively. Based on this distance, the thicknesses of the carrier selection transport layers are adapted on both side surfaces of the crystalline silicon substrate 11, respectively, so that the first heterojunction and the second heterojunction have good carrier selection transport performance, respectively.

[0102] If the thickness of the hole selective contact layer 23 is different from that of the electron selective contact layer 24, the first heterojunction and the second heterojunction can be made into an asymmetric structure, and the battery performance can be optimized and adjusted.

[0103] In any implementation of the embodiments of the present application, the thickness of the hole selective contact layer 23 and the thickness of the electron selective contact layer 24 are both in the range of 10nm to 30nm, which can enable the hole selective contact layer 23 to have good hole selective transport performance and the electron selective contact layer 24 to have good electron selective transport performance, thereby improving the performance of the battery.

[0104] Due to the small band gap width of amorphous silicon (usually 1.7~1.8 eV), the material itself absorbs light (i.e. parasitic absorption). In addition, the refractive index of crystalline silicon is generally smaller than that of amorphous silicon thin films.

[0105] Therefore, in Figure 1In the silicon heterojunction solar cell shown, on the upper surface of the crystalline silicon substrate 11, the P-type doped amorphous silicon film 14 and the first intrinsic amorphous silicon film 12 are optically dense media, and the crystalline silicon substrate 11 is an optically sparse medium. After the light enters the silicon heterojunction solar cell, when the light propagates from the P-type doped amorphous silicon film 14 and the first intrinsic amorphous silicon film 12 to the crystalline silicon substrate 11, it enters the optically sparse medium from the optically dense medium. Therefore, the light incident at a large angle is easily reflected by total reflection at the interface between the first intrinsic amorphous silicon film 12 and the crystalline silicon substrate 11, resulting in a portion of the light being reflected out of the silicon heterojunction solar cell, which will reduce the battery's utilization of light.

[0106] In addition, on the lower surface of the crystalline silicon substrate 11, the second intrinsic amorphous silicon film 13 and the N-type doped amorphous silicon film 15 are optically dense media, and the crystalline silicon substrate 11 is an optically sparse medium. Therefore, when light propagates from the crystalline silicon substrate 11 to the second intrinsic amorphous silicon film 13 and the N-type doped amorphous silicon film 15, it enters the optically dense medium from the optically sparse medium. Therefore, the light will not be totally reflected at the interface between the crystalline silicon substrate 11 and the second intrinsic amorphous silicon film 13, which will cause a portion of the light to be transmitted out of the silicon heterojunction solar cell, reducing the battery's utilization of light.

[0107] In the embodiment of the present application, the hole selection contact layer 23 and the first organic passivation layer 21 are both wide bandgap materials, which can eliminate the parasitic absorption of light by the material itself, and the refractive indexes of the first organic passivation layer 21 and the hole selection contact layer are both less than the refractive index of the crystalline silicon substrate 11. In this way, after the light enters the silicon heterojunction solar cell 100, when the light propagates from the hole selection contact layer 23 and the first organic passivation layer 21 to the crystalline silicon substrate 11, the light enters the light dense medium (crystalline silicon substrate 11) from the light sparse medium (hole selection contact layer 23 and the first organic passivation layer 21), and will not be totally reflected at the interface between the first organic passivation layer 21 and the crystalline silicon substrate 11, which can prevent part of the incident light from being totally reflected at the interface between the first organic passivation layer 21 and the crystalline silicon substrate 11, and can improve the utilization rate of the light by the silicon heterojunction solar cell 100.

[0108] Furthermore, the refractive index of the hole selective contact layer 23 can be set to be smaller than the refractive index of the first organic passivation layer 21. In this way, at the interface between the hole selective contact layer 23 and the first organic passivation layer 21, the hole selective contact layer 23 is a light-sparse medium, and the first organic passivation layer 21 is a light-dense medium. When light propagates from the hole selective contact layer 23 to the first organic passivation layer 21, it is possible to prevent the incident light from being totally reflected at the interface, thereby further improving the light utilization rate of the silicon heterojunction solar cell 100.

[0109] Among them, the first organic passivation layer 21 and the hole selective contact layer 23 are both spin-coated film layers. The first organic passivation layer 21 and the hole selective contact layer 23 can be prepared by a spin coating process, and the preparation process is simple, does not require a high temperature process, and has a low preparation cost. The refractive index of the prepared first organic passivation layer 21 and the hole selective contact layer 23 can be adjusted by respectively adjusting the composition ratio of the spin coating solution for preparing the first organic passivation layer 21 and the composition ratio of the spin coating solution for preparing the hole selective contact layer 23, so that the refractive index of the first organic passivation layer 21 is greater than the refractive index of the hole selective contact layer 23, and / or, the refractive index of the first organic passivation layer 21 and the hole selective contact layer are both less than the refractive index of the crystalline silicon substrate 11.

[0110] In the embodiment of the present application, the second organic passivation layer 22 and the electron selective contact layer 24 are also wide bandgap materials, which can eliminate the parasitic absorption of light by the material itself. In addition, the refractive index of the crystalline silicon substrate 11 can be set to be greater than the refractive index of the second organic passivation layer 22 and the electron selective contact layer 24. In this way, after the light is incident on the silicon heterojunction solar cell 100, when the light propagates from the crystalline silicon substrate 11 to the second organic passivation layer 22 and the electron selective contact layer 24, the light enters the light-sparse medium (the second organic passivation layer 22 and the electron selective contact layer 24) from the optically dense medium (the crystalline silicon substrate 11), and the large-angle incident light can be totally reflected at the interface between the crystalline silicon substrate 11 and the second organic passivation layer 22, which can prevent this part of the light from directly passing through the interface between the crystalline silicon substrate 11 and the second organic passivation layer 22, thereby preventing this part of the light from transmitting out of the silicon heterojunction solar cell, and can reflect this part of the light back to the inside of the silicon heterojunction solar cell again, which can improve the utilization rate of the light by the silicon heterojunction solar cell 100.

[0111] Furthermore, the refractive index of the second organic passivation layer 22 can be set to be greater than the refractive index of the electron selective contact layer 24. In this way, at the interface between the second organic passivation layer 22 and the electron selective contact layer 24, the second organic passivation layer 22 is a light-dense medium, and the electron selective contact layer 24 is a light-sparse medium. When light propagates from the second organic passivation layer 22 to the electron selective contact layer 24, light incident at a large angle can be totally reflected at the interface, preventing this part of the light from transmitting out of the silicon heterojunction solar cell 100, thereby further improving the light utilization rate of the silicon heterojunction solar cell 100.

[0112] Among them, the second organic passivation layer 22 and the electron selective contact layer 24 are both spin-coated film layers. The second organic passivation layer 22 and the electron selective contact layer 24 can be prepared by a spin coating process, and the preparation process is simple, does not require a high temperature process, and has a low preparation cost. The refractive index of the prepared second organic passivation layer 22 and the electron selective contact layer 24 can be adjusted by respectively adjusting the composition ratio of the spin coating solution for preparing the second organic passivation layer 22 and the composition ratio of the spin coating solution for preparing the electron selective contact layer 24, so that the refractive index of the second organic passivation layer 22 is greater than the refractive index of the electron selective contact layer 24, and / or the refractive index of the crystalline silicon substrate 11 is greater than the refractive index of the second organic passivation layer 22 and the electron selective contact layer 24.

[0113] From the above description, it can be seen that for the stacked solar cell provided in the embodiment of the present application, the parasitic absorption of the intrinsic amorphous silicon passivation layer can be reduced by replacing the intrinsic amorphous silicon passivation layer in the conventional cell with an organic passivation layer in the silicon heterojunction solar cell 100.

[0114] The band gap width of intrinsic amorphous silicon is about 1.7eV. In the embodiment of the present application, the band gap width of the organic passivation layer can reach 4eV~5eV, which has a larger band gap width. The organic passivation layer can have a comparable film thickness or a smaller thickness as the intrinsic amorphous silicon passivation layer, which is convenient for carrier tunneling. For example, the thickness of the organic passivation layer can be 5nm. The organic passivation layer can have a passivation effect comparable to that of the intrinsic amorphous silicon passivation layer, and can make the minority carrier lifetime greater than 10ms. Therefore, the silicon heterojunction solar cell provided in the application embodiment is a new type of silicon heterojunction solar cell with broadband passivation.

[0115] In addition, a carrier transport layer is prepared by using a non-silicon inorganic material with a wide band gap to replace the carrier transport layer prepared by doped amorphous silicon material in conventional cells. The carrier transport layer prepared by the non-silicon inorganic material can have a film thickness comparable to that of the carrier transport layer prepared by doped amorphous silicon material or a smaller thickness. The thickness of the carrier transport layer prepared by the non-silicon inorganic material can be 10nm. And the carrier transport layer prepared by the non-silicon inorganic material can have good carrier selection and transmission capabilities, which can meet the commercial use requirements of the photoelectric conversion of the silicon heterojunction solar cell 100.

[0116] Moreover, the carrier selective contact layer prepared based on non-silicon inorganic materials in the embodiments of the present application has a wider band gap than the carrier transport layer prepared based on doped amorphous silicon materials. Therefore, the silicon heterojunction solar cell provided in the embodiments of the application is a new type of silicon heterojunction solar cell with a wide band gap carrier selective contact.

[0117] As mentioned above, the carrier transport layer prepared based on non-silicon inorganic materials does not require doping treatment, has a simple preparation process and low production cost. Therefore, the silicon heterojunction solar cell provided in the application embodiment is a new type of silicon heterojunction solar cell with a carrier transport layer that does not require doping treatment.

[0118] As mentioned above, the first heterojunction and the second heterojunction may be asymmetric structures, so the silicon heterojunction solar cell provided in the application embodiment is a new type of silicon heterojunction solar cell with an asymmetric heterojunction.

[0119] Based on the above description, it can be known that the silicon heterojunction solar cell provided in one embodiment of the present application can be a dopant free asymmetric heterogeneous (DASH) solar cell. It can solve the parasitic absorption problem and the complex preparation process problem caused by the use of amorphous silicon materials to construct heterojunctions in conventional SHJs, and can achieve efficient and low-cost preparation of silicon heterojunction solar cells 100 and stacked solar cells.

[0120] Based on the tandem solar cell provided in the above embodiment, another embodiment of the present application further provides a method for preparing a tandem solar cell, which is used to prepare the tandem solar cell provided in any of the above embodiments. The preparation method can be as follows: Figure 4 shown.

[0121] refer to Figure 4 , Figure 4 A schematic diagram of a process for preparing a stacked solar cell provided in an embodiment of the present application, combined with Figure 2-Figure 4 As shown, the preparation method comprises:

[0122] Step S11: preparing a silicon heterojunction solar cell 100 .

[0123] Step S12: bonding and fixing the perovskite solar cell 200 on the light incident side of the silicon heterojunction solar cell 100; wherein the silicon heterojunction solar cell 100 comprises: a crystalline silicon substrate 11, the crystalline silicon substrate 11 having a first surface 111 and a second surface 112 relative to each other, the first surface 111 facing the perovskite solar cell 200; a first organic passivation layer 21 located on the first surface 111; a second organic passivation layer 22 located on the second surface 112; a hole selective contact layer 23 located on the surface of the first organic passivation layer 21, the hole selective contact layer 23 forms a first heterojunction with the first organic passivation layer 21 and the first surface 111 of the crystalline silicon substrate 11; an electron selective contact layer 24 located on the surface of the second organic passivation layer 22, the electron selective contact layer 24 forms a second heterojunction with the second organic passivation layer 22 and the second surface 112 of the crystalline silicon substrate 11.

[0124] In the embodiment of the present application, the silicon heterojunction solar cell 100 realizes surface passivation through organic materials to form a first organic passivation layer 21 and a second organic passivation layer 22 on the first surface 111 and the second surface 112, respectively, so as to realize low-temperature passivation of the surface of the crystalline silicon substrate 11, improve the surface passivation effect, and reduce the difficulty of the passivation process and the preparation cost. In addition, on the side of the crystalline silicon substrate 11 facing the first surface 111, a first heterojunction is formed based on the hole selection contact layer 23, the first organic passivation layer 21 and the first surface 111, and on the side of the crystalline silicon substrate 11 facing the second surface 112, a second heterojunction is formed based on the electron selection contact layer 24, the second organic passivation layer 22 and the second surface 112. In the heterojunction, the parasitic absorption problem of amorphous silicon is solved, and the photoelectric conversion efficiency can be improved.

[0125] In the embodiment of the present application, the organic passivation material is spin-coated on the first surface 111 and the second surface 112 respectively to form the first organic passivation layer 21 and the second organic passivation layer 22; the hole selection contact layer 23 is formed on the surface of the first organic passivation layer 21, and the electron selection contact layer 24 is formed on the surface of the second organic passivation layer 22 respectively by spin coating. In this way, compared with the solution of preparing heterojunction by epitaxial amorphous silicon material, high temperature vacuum process is not required, the difficulty and cost of process preparation are reduced, and it is also convenient to adjust the refractive index of the passivation layer and the carrier selection transmission layer to improve the utilization rate of light by the battery.

[0126] In the present embodiment, 2PACz (molecular formula is C 14 H 14 NO 3 The first organic passivation layer 21 and the second organic passivation layer 22 are prepared by using organic materials such as P) or other organic passivation materials. The organic passivation materials of the two passivation layers can be the same or different. The thickness of the first organic passivation layer 21 and the second organic passivation layer 22 can range from 2nm to 10nm. The high resistance (10 3 Ω·cm~10 6 The minority carrier lifetime on a polished silicon wafer with a density of 0.1 Ω·cm is greater than 10 ms, and the minority carrier lifetime on a doped silicon wafer with a density of 1 Ω·cm~3 Ω·cm is greater than 2 ms. The measurement data show that the minority carrier lifetime of cells based on organic passivation layers meets the minority carrier lifetime requirements of silicon heterojunction solar cells.

[0127] In one embodiment, ultra-thin NiO can be prepared on the surfaces of the first organic passivation layer 21 and the second organic passivation layer 22 by a spin coating process. x The prepared ultrathin NiO film and the ultrathin ZnS film are used as the hole selective contact layer 23 and the electron selective contact layer 24. xThe thickness of thin film and ultra-thin ZnS film can range from 10nm to 30nm. x Thin films and ultra-thin ZnS films can be subjected to low temperature annealing treatment, and the annealing temperature can be 200°C to obtain ultra-thin NiO with excellent optoelectronic properties. x Thin films and ultra-thin ZnS films.

[0128] The contact characteristics of the silicon heterojunction solar cell provided in the embodiment of the present application were tested by a dark state I / V (current / voltage) test device. The measured data showed that the ultra-thin NiO x The first heterojunction formed by the thin film, the first organic passivation layer 21 and the first surface 111 of the crystalline silicon substrate 11 and the second heterojunction formed by the ultra-thin ZnS film, the second organic passivation layer 22 and the second surface 112 of the crystalline silicon substrate 11 are both Schottky contact heterojunctions with good passivation effects.

[0129] The interface microstructure of the two heterojunctions in the silicon heterojunction solar cell provided in the embodiment of the present application can be studied by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). By combining X-ray photoelectron spectroscopy (XPS) with etching and stripping technology, a method of "testing-etching (thinning)-retesting-reetching-..." is adopted to find the coexistence of Si and S, Si and Ni signals, that is, the interface between NiOx film / first organic passivation layer 21, the interface between the second organic passivation layer 22 / ZnS film, and the interface between the organic passivation layer / crystalline silicon substrate 11, and even the interface where the carrier selection transport layer / organic passivation layer / crystalline silicon substrate 11 coexist, to obtain the element valence state at the interface and the microstructure of the interface. The test data shows that the element valence state at the interface of the silicon heterojunction solar cell provided in the embodiment of the present application and the microstructure of the interface meet the use requirements of the silicon heterojunction solar cell.

[0130] The heterojunction band structure is determined by ultraviolet photoelectron spectroscopy (UPS) and CV (capacitance-voltage) tests. By testing the variable temperature IV (current-voltage) curve with the help of the thermal electron emission model, the interface band matching and interface barrier height between the NiOx film / first organic passivation layer 21 / crystalline silicon substrate 11 and the crystalline silicon substrate 11 / second organic passivation layer 22 / ZnS film can be obtained, and the interface carrier transport law can be obtained. The test data shows that the interface band matching and interface barrier height of the silicon heterojunction solar cell provided in the embodiment of the present application can meet the use requirements of the silicon heterojunction solar cell.

[0131] After preparing a complete silicon heterojunction solar cell, the photovoltaic performance parameters of the cell can be fully characterized using a solar simulator, IPCE measurement system, and Keithley meter: open circuit voltage (Voc), short circuit current (Jsc), fill factor (FF), and energy conversion efficiency (PCE), as well as the spectral response of the cell, etc.; and a comprehensive loss analysis of the cell performance can be performed, including recombination, optical, and transport losses. The macroscopic performance analysis is combined with the microscopic mechanism research, and the mutual feedback is used to determine the cell operation mechanism and performance regulation mechanism. These test data all show that the silicon heterojunction solar cell that meets the use requirements can be prepared based on the technical solution of the embodiment of this application.

[0132] Based on the description of the embodiments of the present application, it can be seen that the preparation method of the present application can use a spin coating method to prepare a passivation layer and a carrier selection and transport layer, without the need to use vacuum high-temperature equipment, thereby simplifying the preparation process and reducing the preparation cost.

[0133] In addition, the use of wide-bandgap organic materials to passivate the substrate surface can fundamentally avoid the parasitic absorption problem caused by the use of amorphous silicon passivation, providing a new passivation method for silicon heterojunction solar cells.

[0134] In the embodiment of the present application, the carriers in the non-silicon inorganic material are transported by means of drift or diffusion mechanisms, while the carriers in the organic material are transported by a hopping mechanism, so the organic passivation material and the non-silicon inorganic material have different carrier transport mechanisms, while the amorphous silicon passivation layer and the doped amorphous silicon carrier selective transport layer have the same carrier transport mechanism. Therefore, the carrier selective transport layer in the embodiment of the present application has a different carrier transport mechanism from the carrier selective transport layer in the conventional scheme, and the passivation mechanism is different, which can form a special "inorganic-organic-inorganic" heterojunction interface, construct a new type of carrier transport mechanism, and can improve the performance of silicon heterojunction batteries.

[0135] In the specification of this application, each embodiment is described in a progressive, parallel, or progressive and parallel manner, and each embodiment focuses on the differences from other embodiments, and the same or similar parts between the embodiments can be referred to each other. The embodiments provided in the embodiments of this application can be combined with each other if there is no contradiction.

[0136] It should be noted that in the description of the present application, it should be understood that the description of the drawings and embodiments is illustrative rather than restrictive. The same reference numerals throughout the embodiments of the specification identify the same structure. In addition, for the sake of understanding and ease of description, the drawings may exaggerate the thickness of some layers, films, panels, regions, etc. It is also understood that when an element such as a layer, film, region, or substrate is referred to as "on" another element, the element may be directly on the other element or there may be an intermediate element. In addition, "on" refers to positioning an element on or below another element, but does not essentially refer to positioning on the upper side of another element according to the direction of gravity.

[0137] The terms "upper", "lower", "top", "bottom", "inner", "outer", etc. indicate positions or positional relationships based on the positions or positional relationships shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present application. When a component is considered to be "connected" to another component, it may be directly connected to the other component or there may be a centrally arranged component at the same time.

[0138] It should also be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "comprises", "comprising" or any other variants thereof are intended to cover non-exclusive inclusion, so that an article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such article or device. In the absence of further restrictions, the elements defined by the sentence "comprising a ..." do not exclude the existence of other identical elements in the article or device including the above elements.

[0139] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A stacked solar cell, characterized in that: include: Silicon heterojunction solar cells; a perovskite solar cell located on the light-incident side of the silicon heterojunction solar cell; The perovskite solar cell can absorb light of 300nm to 700nm to generate photovoltaic power; the silicon heterojunction solar cell can absorb light of 700nm to 1200nm to generate electricity; the silicon heterojunction solar cell and the perovskite solar cell are connected and fixed by a light-transmitting composite connection layer, and the composite connection layer is uniformly mixed with ultraviolet filter material; Wherein, the silicon heterojunction solar cell comprises: A crystalline silicon substrate, the crystalline silicon substrate having a first surface and a second surface opposite to each other, the first surface facing the perovskite solar cell; a first organic passivation layer located on the first surface; a second organic passivation layer located on the second surface; the thickness of the first organic passivation layer and the thickness of the second organic passivation layer are both in the range of 2nm to 10nm; the thickness of the first organic passivation layer is less than the thickness of the second organic passivation layer, so that the thicknesses of the two organic passivation layers are respectively adapted to the light incident side distance of the silicon heterojunction solar cell; the ratio of the thickness of the first organic passivation layer to the second organic passivation layer is less than 1 and not less than 1 / 3; a hole selection contact layer located on the surface of the first organic passivation layer, wherein the hole selection contact layer forms a first heterojunction with the first organic passivation layer and the first surface of the crystalline silicon substrate; an electron selective contact layer located on the surface of the second organic passivation layer, wherein the electron selective contact layer, the second organic passivation layer and the second surface of the crystalline silicon substrate form a second heterojunction, and the first heterojunction and the second heterojunction are asymmetric structures; Wherein, the first organic passivation layer and the hole selective contact layer are both spin-coated film layers, and / or the second organic passivation layer and the electron selective contact layer are both spin-coated film layers; The refractive index of the first organic passivation layer is greater than the refractive index of the hole selective contact layer, and / or the refractive index of the first organic passivation layer and the refractive index of the hole selective contact layer are both less than the refractive index of the crystalline silicon substrate; The refractive index of the second organic passivation layer is greater than that of the electron selective contact layer, and / or the refractive index of the crystalline silicon substrate is greater than that of the second organic passivation layer and the electron selective contact layer.

2. The tandem solar cell according to claim 1, characterized in that: The crystalline silicon substrate is N-type doped crystalline silicon, the hole selection contact layer and the electron selection contact layer are both non-silicon inorganic materials, and the hole selection contact layer and the electron selection contact layer are different non-silicon inorganic materials.

3. The tandem solar cell according to claim 2, characterized in that: The hole selective contact layer includes NiO x 、MoO x and any of V2O5; The electron selective contact layer includes any one of ZnS, TiO2, MgO and LiF.

4. The tandem solar cell according to claim 1, characterized in that: The thickness of the hole selective contact layer is different from the thickness of the electron selective contact layer.

5. The tandem solar cell according to claim 4, characterized in that: The thickness of the hole selective contact layer is smaller than the thickness of the electron selective contact layer.

6. The tandem solar cell according to any one of claims 1 to 5, characterized in that: The thickness of the hole selective contact layer and the thickness of the electron selective contact layer are both in the range of 10 nm to 30 nm.

7. A method for preparing a laminated solar cell according to any one of claims 1 to 6, characterized in that: include: Preparation of silicon heterojunction solar cells; Adhesively fixing a perovskite solar cell on the light incident side of the silicon heterojunction solar cell; The perovskite solar cell can absorb light of 300nm to 700nm to generate photovoltaic power; the silicon heterojunction solar cell can absorb light of 700nm to 1200nm to generate electricity; the silicon heterojunction solar cell and the perovskite solar cell are connected and fixed by a light-transmitting composite connection layer, and the composite connection layer is uniformly mixed with ultraviolet filter material; Wherein, the silicon heterojunction solar cell comprises: A crystalline silicon substrate, the crystalline silicon substrate having a first surface and a second surface opposite to each other, the first surface facing the perovskite solar cell; a first organic passivation layer located on the first surface; a second organic passivation layer located on the second surface; the thickness of the first organic passivation layer and the thickness of the second organic passivation layer are both in the range of 2nm to 10nm; the thickness of the first organic passivation layer is less than the thickness of the second organic passivation layer, so that the thicknesses of the two organic passivation layers are respectively adapted to the light incident side distance of the silicon heterojunction solar cell; the ratio of the thickness of the first organic passivation layer to the second organic passivation layer is less than 1 and not less than 1 / 3; a hole selection contact layer located on the surface of the first organic passivation layer, wherein the hole selection contact layer forms a first heterojunction with the first organic passivation layer and the first surface of the crystalline silicon substrate; an electron selective contact layer located on the surface of the second organic passivation layer, wherein the electron selective contact layer forms a second heterojunction with the second organic passivation layer and the second surface of the crystalline silicon substrate; Wherein, the first organic passivation layer and the hole selective contact layer are both spin-coated film layers, and the second organic passivation layer and the electron selective contact layer are both spin-coated film layers; The refractive index of the first organic passivation layer is greater than the refractive index of the hole selective contact layer, and / or the refractive index of the first organic passivation layer and the refractive index of the hole selective contact layer are both less than the refractive index of the crystalline silicon substrate; The refractive index of the second organic passivation layer is greater than that of the electron selective contact layer, and / or the refractive index of the crystalline silicon substrate is greater than that of the second organic passivation layer and the electron selective contact layer.

8. The preparation method according to claim 7 comprises: Spin-coating an organic passivation material on the first surface and the second surface respectively to form the first organic passivation layer and the second organic passivation layer; A hole selective contact layer is formed on the surface of the first organic passivation layer, and an electron selective contact layer is formed on the surface of the second organic passivation layer by a spin coating method.

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