Solar cell, solar cell module and preparation method of solar cell

Abstract

The invention discloses a solar cell, a solar cell module and a preparation method of the solar cell, and relates to the technical field of solar cells, the solar cell comprises a crystalline silicon bottom cell, an interconnection layer and a perovskite top cell; the gradient change of the band gap of the perovskite layer is designed, so that the perovskite layer is composed of multiple layers of gradient-assembled multi-size perovskite quantum dots, the sizes of the perovskite quantum dots in the direction from the light-facing surface to the backlight surface are gradually increased, and the band gap of the perovskite layer is gradually reduced in the direction from the light-facing surface to the backlight surface due to the size effect of the quantum dots. The band gap of the backlight surface of the perovskite layer is larger than the band gap of the absorption layer of the crystalline silicon cell unit. As the band gap is gradually reduced, the solar spectrum is sequentially absorbed by different band gap regions according to the energy level, so that the conversion efficiency of the cell and the assembly is improved. According to the solar cell module, the solar cell module main body is more convenient to fix during assembly through the connecting plate.

Description

Technical Field

[0001] The present invention application relates to the technical field of solar cells, and specifically relates to a solar cell, a solar cell module, and a preparation method of a solar cell. Background Art

[0002] Currently, crystalline silicon solar cells are still the mainstream photovoltaic technology, accounting for about 90% of the entire photovoltaic market. Its highest efficiency has reached 27.3%, which is very close to the theoretical efficiency of 29.4% of single-crystalline silicon cells. The room for improvement in the efficiency of crystalline silicon cells is limited. In order to further improve the conversion efficiency of silicon-based solar cells, people have proposed to construct a tandem cell based on crystalline silicon, that is, a wide-bandgap material is stacked on the top layer of the crystalline silicon cell to broaden the spectral response of the cell and improve the efficiency of the solar cell. Its theoretical efficiency exceeds 40%. Among them, perovskite has become one of the preferred materials for tandem cells due to its excellent optoelectronic properties and adjustable bandgap.

[0003] In current perovskite or crystalline silicon tandem solar cells, the perovskite layer and the crystalline silicon layer each have a relatively fixed bandgap. When absorbing the solar spectrum, although it is more extensive than that of a single-junction cell, there are still problems of insufficiently fine energy matching and insufficient utilization of photon energy. Summary of the Invention

[0004] In order to solve the problems of insufficiently fine energy matching and insufficient utilization of photon energy in solar cells, the present invention provides a solar cell, a solar cell module, and a preparation method of a solar cell to solve the above problems.

[0005] To achieve the above object, the present invention provides the following technical solutions: A solar cell includes a lower electrode, a crystalline silicon bottom cell is disposed on the lower electrode, an interconnection layer is disposed on the crystalline silicon bottom cell, a first carrier transport layer is disposed on the interconnection layer, a multi-layer perovskite quantum dot thin film is disposed on the first carrier transport layer, a second carrier transport layer is disposed on the multi-layer perovskite quantum dot thin film, a transparent conductive oxide is disposed on the second carrier transport layer, and an upper electrode is disposed on the transparent conductive oxide.

[0006] Furthermore, the solar cell module includes a solar cell module main body, a connecting plate, and a fixing sleeve plate. Each solar cell module main body includes multiple solar cells, tempered glass, encapsulation materials (EVA, POE, etc.), a functional backplane, interconnection bars, bus bars, a junction box, and an aluminum alloy frame, etc. A connecting plate is symmetrically fixed on the back of each solar cell module main body. The connecting plates between two adjacent solar cell module main bodies up and down are slidably sleeved inside the fixing sleeve plate, and each connecting plate and the fixing sleeve plate are fixed by bolts.

[0007] Further, a number of reinforcing backplates are equidistantly fixed to the back of each solar cell module body. Each connecting plate is set to be L-shaped, and two convex shapes matching the connecting plates are provided inside each fixed sleeve plate.

[0008] Further, a support plate is fixed to the back of the lowermost solar cell module body. A rotating link is rotatably connected to the side of the support plate. One end of the rotating link away from the support plate is rotatably connected to an adjusting screw. A threaded sleeve block is sleeved on the adjusting screw. The bottom of the threaded sleeve block is fixed to the top surface of the fixed base. The bottom of the support plate is rotatably connected to the top surface of the fixed base.

[0009] Further, a connecting rod penetrates through all the support plates. A nut is threadedly sleeved on one end of the connecting rod extending outside the support plate. The connecting rod is set to be a horizontally placed T-shaped. Fixed holes are symmetrically opened inside both sides of the fixed base.

[0010] Further, a preparation method of a solar cell, the preparation method includes the following steps: Step A: Provide a crystalline silicon bottom cell unit. The bottom cell unit has a light-facing surface and a backlight-facing surface arranged oppositely. The crystalline silicon bottom cell can be one of PERC, TOPCon, HJT or back-contact cell, and the preparation of the lower electrode is completed; Step B: Prepare an intermediate interconnection structure on the light-facing surface of the bottom cell unit. The interconnection layer can be an nc-Si:H(p+) / nc-Si:H(n+) tunneling junction or a TCO composite layer; Step C: Prepare a first carrier transport layer on the intermediate interconnection layer, which can be a hole transport layer or an electron transport layer; Step D: Prepare a multi-layer perovskite quantum dot thin film on the first carrier transport layer. The band gap of the perovskite quantum dot thin film changes in a gradient manner; Step E: Prepare a second carrier transport layer on the perovskite quantum dot thin film. The conductivity type of the second carrier transport layer is opposite to that of the first carrier transport layer; Step F: Prepare a transparent conductive oxide on the second carrier transport layer, such as indium tin oxide (ITO), indium oxide doped with zinc IZO, indium oxide doped with tungsten IWO, aluminum-doped zinc oxide (AZO), tin oxide doped with fluorine (FTO), zinc oxide doped with boron, etc.

[0011] Step G: Prepare an upper electrode on the transparent conductive oxide, such as one or a combination of gold, silver, aluminum, copper, platinum.

[0012] Further, in step B, the TCO layer can be prepared by any method commonly used in the art for preparing transparent conductive layers, including but not limited to deposition methods such as chemical vapor deposition, magnetron sputtering deposition, or reactive plasma deposition. The TCO layer includes but is not limited to indium tin oxide (ITO), indium zinc oxide (IZO) doped with zinc, indium tungsten oxide (IWO) doped with tungsten, aluminum-doped zinc oxide (AZO), fluorine-doped tin oxide (FTO), and zinc oxide doped with boron, etc.

[0013] Further, the preparation methods in step C and step E can be one of vacuum evaporation, transfer printing method, and ALD. Between the first carrier transport layer and the second carrier transport layer and the perovskite absorption layer, there are passivation layers, modification layers, buffer layers, and other functional preparation layers, which are also included in the first carrier transport layer and the second carrier transport layer.

[0014] Further, in step D, specifically, the perovskite layer is composed of multi-size perovskite quantum dots assembled by multi-layer gradients. The size of the perovskite quantum dots gradually increases from the light-facing surface to the backlight-facing surface. The size range of the perovskite quantum dots is 1 - 20 nm. Due to the size effect of quantum dots, the bandgap of the perovskite layer gradually decreases from the light-facing surface to the backlight-facing surface. The bandgap at the backlight-facing surface of the perovskite layer is greater than the bandgap of the absorption layer of the crystalline silicon cell unit, which is 1.12 eV. The bandgap range of the perovskite quantum dots is 1.15 eV - 3.06 eV.

[0015] Further, the perovskite quantum dot material in step D is of the MPbX3 type, where M can be one or a mixture of two of FA (formamidinium) and Cs components, and X is one or a mixture of more of the elements I, Br, and Cl; the preparation method of the perovskite quantum dot thin film can be spin coating, inkjet printing, slot coating, or blade coating, etc.; the total thickness of the multi-layer perovskite quantum dot thin film is 100 nm - 1000 nm.

[0016] Compared with the prior art, the beneficial effects of the present invention are: 1. In the present invention, by designing the gradient change of the bandgap of the perovskite layer, the perovskite layer is composed of multi-size perovskite quantum dots assembled by multi-layer gradients. The size of the perovskite quantum dots gradually increases from the light-facing surface to the backlight-facing surface. Due to the size effect of quantum dots, the bandgap of the perovskite layer gradually decreases from the light-facing surface to the backlight-facing surface. The bandgap at the backlight-facing surface of the perovskite layer is greater than the bandgap of the absorption layer of the crystalline silicon cell unit; since the bandgap gradually changes from large to small, it can better match the energy distribution of the solar spectrum. The solar spectrum is absorbed by different bandgap regions in order of energy level from high to low, minimizing the waste of photon energy, thereby improving the conversion efficiency.

[0017] 2. In the present invention, by means of the connecting plates on the sides of two adjacent solar cell module bodies above and below, inserting the connecting plates into the fixed sleeve plates can quickly splice and align the solar cell module bodies, making it more convenient to fix the solar cell module bodies during assembly.

[0018] 3. In the present invention, through the adjustable design during the installation of the solar cell module body, during use, the inclination angle during the installation of the solar cell module body can be adjusted according to the height of the building at the construction site, enabling the solar cell module body to better absorb solar energy. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0020] Figure 1 is a schematic diagram of the internal structure of a solar cell according to an embodiment of the present application; Figure 2 is Figure 1 a front view schematic diagram of the structure of a solar cell module in the illustrated embodiment; Figure 3 is Figure 1 a rear view schematic diagram of the structure of a solar cell module in the illustrated embodiment; Figure 4 is Figure 1 a bottom view schematic diagram of the structure of a solar cell module in the illustrated embodiment; Figure 5 is Figure 1 a partial structure schematic diagram of a solar cell module in the illustrated embodiment; Figure 6 is Figure 1 in the illustrated embodiment Figure 4 a magnified schematic diagram of the structure at location A.

[0021] The meanings of the reference numerals in the drawings: 1, solar cell module body; 11, lower electrode; 12, crystalline silicon bottom cell; 13, interconnection layer; 14, first carrier transport layer; 15, multi-layer perovskite quantum dot thin film; 16, second carrier transport layer; 17, transparent conductive oxide; 18, upper electrode; 2, reinforcement backplane; 3, connecting plate; 4, fixed sleeve plate; 5, support plate; 6, connecting rod; 7, rotating link; 8, threaded sleeve block; 9, adjusting screw; 10, fixed base. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0022] In order to make the application purpose, features, and advantages of the present application more obvious and understandable, the following will clearly and completely describe the technical solutions in the embodiments of the present application with reference to the accompanying drawings in the embodiments of the present application. Obviously, the embodiments described below are only a part of the embodiments of the present application, rather than all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present application.

[0023] Referring to Figure 1 , a solar cell includes a solar cell. The solar cell includes a lower electrode 11, a crystalline silicon bottom cell 12 is disposed on the lower electrode 11, an interconnection layer 13 is disposed on the crystalline silicon bottom cell 12, a first carrier transport layer 14 is disposed on the interconnection layer 13, a multi-layer perovskite quantum dot thin film 15 is disposed on the first carrier transport layer 14, a second carrier transport layer 16 is disposed on the multi-layer perovskite quantum dot thin film 15, a transparent conductive oxide 17 is disposed on the second carrier transport layer 16, and an upper electrode 18 is disposed on the transparent conductive oxide 17; It can be used in perovskite / silicon tandem cells, perovskite / perovskite tandem cells, and perovskite and inorganic thin film tandem solar cells, etc. The structure can be a two-terminal tandem or a four-terminal tandem, and can also be applied to perovskite cells. The core structure is the change in bandgap caused by the quantum dot size effect. By applying this effect, a perovskite thin film structure with a bandgap gradient change is obtained.

[0024] Embodiment 2 As Figure 2 , Figure 4 and Figure 6 shown, the solar cell module is applied to the aforementioned solar cell, and includes a solar cell module main body 1, a connecting plate 3, and a fixing sleeve plate 4. Each solar cell module main body 1 includes multiple solar cells, tempered glass, encapsulation materials (such as EVA, POE, etc.), a functional backplane, interconnection bars, busbars, a junction box, and an aluminum alloy frame, etc. A plurality of reinforcing backplates 2 are equally spaced and fixed on the back of each solar cell module main body 1. A connecting plate 3 is symmetrically fixed on the back of each solar cell module main body 1. The connecting plates 3 between the upper and lower adjacent solar cell module main bodies 1 are all slidably sleeved inside the fixing sleeve plate 4. Each connecting plate 3 and the fixing sleeve plate 4 are fixed by bolts. Each connecting plate 3 is set to be L-shaped, and two convex shapes matching the connecting plate 3 are provided inside each fixing sleeve plate 4.

[0025] Specifically, when assembling the solar cell module main body 1, align and fit the connecting plates 3 of the upper and lower two solar cell module main bodies 1 and insert them into the fixing sleeve plate 4, and fix them with bolts. Select a fixing sleeve plate 4 with a corresponding length according to the horizontal arrangement length of the solar cell module main body 1, and the solar cell module main body 1 can be assembled and fixed.

[0026] As a further optimization solution, as Figure 2 , Figure 4 and Figure 5 shown, a support plate 5 is fixedly attached to the back surface of the lowermost solar cell module body 1. A connecting rod 6 passes through all the support plates 5. One end of the connecting rod 6 extending outside the support plate 5 is threadedly sleeved with a nut. The connecting rod 6 is arranged as a horizontally placed T-shaped. One side of the support plate 5 is rotatably connected to a rotating connecting rod 7. One end of the rotating connecting rod 7 away from the support plate 5 is rotatably connected to an adjusting screw rod 9. A threaded sleeve block 8 is threadedly sleeved on the adjusting screw rod 9. The bottom of the threaded sleeve block 8 is fixedly attached to the top surface of the fixed base 10. The bottom of the support plate 5 is rotatably connected to the top surface of the fixed base 10. Fixed holes are symmetrically formed in both inner sides of the fixed base 10.

[0027] Specifically, before assembling the solar cell module body 1, the support plates 5 are welded and fixed to the reinforcement backplane 2 of the lowermost solar cell module body 1 one by one. Then, the connecting rod 6 is passed through the support plates 5 and fixed by nuts. After fixing, the fixed base 10 is fixed to a building or the ground through fixing members such as bolts. At the same time, the adjusting screw rod 9 is rotated, so that under the action of the threaded sleeve block 8, the adjusting screw rod 9 pulls the rotating connecting rod 7 and pushes the support plate 5, thereby adjusting the angle of the solar cell module body 1.

[0028] Embodiment 3 A method for preparing a solar cell, the preparation method comprising the following steps: Step A: Provide a crystalline silicon bottom cell 12. The bottom cell unit has a light-facing surface and a backlight-facing surface arranged opposite to each other. The crystalline silicon bottom cell 12 can be one of PERC, TOPCon, HJT or back contact cells, and the preparation of the lower electrode 11 is completed; Step B: Prepare an intermediate interconnection structure on the light-facing surface of the bottom cell unit. The interconnection layer 13 can be a heavily doped inverted silicon-based tunneling layer including n ++ / p ++ a-Si:H, nc-Si:H or TCO composite layer; In step B, the TCO layer can be prepared by any method commonly used in the art for preparing a transparent conductive layer, including but not limited to deposition methods such as chemical vapor deposition, magnetron sputtering deposition or reactive plasma deposition. The TCO layer includes but is not limited to indium tin oxide (ITO), indium zinc oxide doped with zinc (IZO), indium tungsten oxide doped with tungsten (IWO), aluminum-doped zinc oxide (AZO), fluorine-doped tin oxide (FTO), and zinc oxide doped with boron, etc.; Step C: Prepare a first carrier transport layer 14 on the intermediate interconnection layer 13, which can be a hole transport layer or an electron transport layer; Step D: Prepare a multi-layer perovskite quantum dot thin film 15 on the first carrier transport layer 14, and the band gap of the perovskite quantum dot thin film changes in a gradient manner; Specifically in Step D, the perovskite layer is composed of multi-size perovskite quantum dots assembled in multiple layers with a gradient. The size of the perovskite quantum dots gradually increases from the light-facing side to the backlight-facing side. The size range of the perovskite quantum dots is 1 - 20 nm. Due to the size effect of quantum dots, the band gap of the perovskite layer gradually decreases from the light-facing side to the backlight-facing side. The band gap at the backlight-facing side of the perovskite layer is greater than the band gap of 1.12 eV of the absorption layer of the crystalline silicon solar cell unit. The band gap range of the perovskite quantum dots is 1.15 eV - 3.06 eV; The perovskite quantum dot material in Step D is of the MPbX3 type, where M can be one or a mixture of two of FA (formamidinium), Cs components, and X is one or a mixture of multiple elements of I, Br, Cl; The preparation method of the perovskite quantum dot thin film can be spin coating, inkjet printing, slot coating, blade coating, etc.; The total thickness of the multi-layer perovskite quantum dot thin film 15 is 100 nm - 1000 nm; Step E: Prepare a second carrier transport layer 16 on the perovskite quantum dot thin film. The second carrier transport layer 16 has a conductivity type opposite to that of the first carrier transport layer 14; The preparation methods in Step C and Step E can be one of vacuum evaporation, transfer printing, atomic layer deposition, magnetron sputtering, reactive plasma deposition, and spin coating. Among them, there are other functional preparation layers such as a passivation layer, a modification layer, and a buffer layer between the first carrier transport layer 14 and the second carrier transport layer 16 and the perovskite absorption layer, which are also included in the first carrier transport layer 14 and the second carrier transport layer 16; Step F: Prepare a transparent conductive oxide 17 on the second carrier transport layer 16, such as indium tin oxide (ITO), indium zinc oxide doped with zinc (IZO), indium tungsten oxide doped with tungsten (IWO), aluminum-doped zinc oxide (AZO), fluorine-doped tin oxide (FTO), and zinc oxide doped with boron, etc.

[0029] Step G: Prepare a top electrode 18 on the transparent conductive oxide 17, such as one or a combination of gold, silver, aluminum, copper, and platinum.

[0030] For those skilled in the art, it is obvious that the present application is not limited to the details of the above exemplary embodiments, and without departing from the spirit or basic characteristics of the present application, the present application can be implemented in other specific forms. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-limiting. The scope of the present application is defined by the appended claims rather than the above description. Therefore, all changes falling within the meaning and scope of the same elements of the claims are intended to be included in the present application. Any reference signs in the claims should not be regarded as limiting the claimed rights.

[0031] As described above, the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A solar cell, characterized in that: The invention comprises a lower electrode (11), a crystalline silicon bottom battery (12) is arranged on the lower electrode (11), an interconnection layer (13) is arranged on the crystalline silicon bottom battery (12), a first carrier transport layer (14) is arranged on the interconnection layer (13), a multilayer perovskite quantum dot film (15) is arranged on the first carrier transport layer (14), a second carrier transport layer (16) is arranged on the multilayer perovskite quantum dot film (15), a transparent conductive oxide (17) is arranged on the second carrier transport layer (16), and an upper electrode (18) is arranged on the transparent conductive oxide (17).

2. A solar cell assembly, applied to the solar cell according to claim 1, characterized in that: The invention comprises a solar cell module body (1), a connecting plate (3) and a fixed sleeve plate (4); the connecting plate (3) is symmetrically fixed to the back of each solar cell module body (1); the connecting plates (3) between two upper and lower adjacent solar cell module bodies (1) are slidably sleeved inside the fixed sleeve plate (4); and each connecting plate (3) is fixed to the fixed sleeve plate (4) by bolts.

3. The solar cell assembly according to claim 2, characterized in that: Each solar cell assembly body (1) comprises a plurality of solar cells, tempered glass, packaging materials (EVA, POE, etc.), a functional backplane, interconnection bars, bus bars, a junction box, and an aluminum alloy frame, etc.

4. The solar cell assembly according to claim 2, characterized in that: A plurality of reinforcing back plates (2) are fixed at equal intervals on the back of each solar cell assembly body (1); each connecting plate (3) is arranged in an L shape; and each fixing sleeve plate (4) has a convex shape inside which two connecting plates (3) cooperate.

5. The solar cell assembly according to claim 2, characterized in that: A support plate (5) is fixed on the back of the solar cell assembly body (1) at the bottom, and a rotating connecting rod (7) is rotatably connected to the side of the support plate (5), and an end of the rotating connecting rod (7) away from the support plate (5) is rotatably connected to an adjusting screw (9), and a threaded sleeve (8) is threadedly sleeved on the adjusting screw (9), and the bottom of the threaded sleeve (8) is fixed to the top surface of the fixed base (10), and the bottom of the support plate (5) is rotatably connected to the top surface of the fixed base (10).

6. The solar cell assembly according to claim 5, characterized in that: A connecting rod (6) is passed through all the support plates (5), one end of the connecting rod (6) extending to the outside of the support plate (5) is threadedly sleeved with a nut, the connecting rod (6) is arranged in a transversely placed T-shape, and fixing holes are symmetrically opened inside both sides of the fixed base (10).

7. A method for preparing a solar cell, applied to the solar cell according to claim 1, characterized in that: The preparation method comprises the following steps: Step (A): providing a crystalline silicon bottom cell (12) unit, the bottom cell unit having a light-facing surface and a backlight surface that are arranged opposite to each other, the crystalline silicon bottom cell (12) can be one of PERC, TOPCon, HJT or a back contact cell, and completing the preparation of the bottom electrode (11); Step (B): preparing an intermediate interconnection structure on the light-facing side of the bottom battery unit, wherein the interconnection layer (13) may be a heavily doped inversion silicon-based tunneling layer including n ++ / p ++ a-Si:H, nc-Si:H or TCO composite layer; Step (C): preparing a first carrier transport layer (14) on the intermediate interconnect layer (13), which may be a hole transport layer or an electron transport layer; Step (D): preparing a multilayer perovskite quantum dot film (15) on the first carrier transport layer (14), wherein the band gap of the perovskite quantum dot film changes in a gradient; Step (E): preparing a second carrier transport layer (16) on the perovskite quantum dot film, wherein the conductivity type of the second carrier transport layer (16) is opposite to that of the first carrier transport layer (14); Step (F): preparing a transparent conductive oxide (17) on the second carrier transport layer (16), such as indium tin oxide (ITO), zinc-doped indium oxide (IZO), tungsten-doped indium oxide (IWO), aluminum-doped zinc oxide (AZO), fluorine-doped tin oxide (FTO) and boron-doped zinc oxide. Step (G): preparing an upper electrode (18) on the transparent conductive oxide (17), such as one or a combination of gold, silver, aluminum, copper, and platinum.

8. The method for preparing a solar cell according to claim 7, characterized in that: In step (B), the TCO layer can be prepared by any method commonly used in the art to prepare a transparent conductive layer, including but not limited to a deposition method such as chemical vapor deposition, magnetron sputtering deposition or reactive plasma deposition. The TCO layer includes but is not limited to indium tin oxide (ITO), zinc-doped indium oxide (IZO), tungsten-doped indium oxide (IWO), aluminum-doped zinc oxide (AZO), fluorine-doped tin oxide (FTO) and boron-doped zinc oxide.

9. The method for preparing a solar cell according to claim 7, characterized in that: The preparation method in step (C) and step (E) may be one of vacuum evaporation, transfer method, atomic layer deposition, magnetron sputtering, reactive plasma deposition and spin coating, wherein the first carrier transport layer (14) and the second carrier transport layer (16) and the perovskite absorption layer both contain a passivation layer, a modification layer, a buffer layer and other functional preparation layers are also contained in the first carrier transport layer (14) and the second carrier transport layer (16).

10. The method for preparing a solar cell according to claim 7, characterized in that: The step (D) specifically comprises making the perovskite layer consist of multi-layer gradient-assembled multi-size perovskite quantum dots, wherein the size of the perovskite quantum dots gradually increases from the light-facing side to the backlight side, and the size range of the perovskite quantum dots is 1-20 nm. Due to the size effect of the quantum dots, the band gap of the perovskite layer gradually decreases from the light-facing side to the backlight side, and the band gap of the perovskite layer at the backlight side is greater than the band gap (1.12 eV) of the absorption layer of the crystalline silicon battery unit, and the band gap range of the perovskite quantum dots is (1.15 eV-3.06 eV).

11. The method for preparing a solar cell according to claim 7, characterized in that: In the step (D), the perovskite quantum dot material is of the MPbX3 type, wherein M can be one or a mixture of two of the components FA (formamidine) and Cs, and X can be a mixture of one or more of the elements I, Br, and Cl. The preparation method of the perovskite quantum dot film can be spin coating, inkjet printing, slit coating, or scraping. The total thickness of the multilayer perovskite quantum dot film (15) is 100nm-1000nm.

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