Zoned down-conversion composite adhesive film and preparation method therefor, and perovskite heterojunction tandem cell

Abstract

The present invention relates to the technical field of tandem cells. Disclosed are a zoned down-conversion composite adhesive film and a preparation method therefor, and a perovskite heterojunction tandem cell. The zoned down-conversion composite adhesive film is used for encapsulating a tandem cell comprising a perovskite top cell layer and a heterojunction bottom cell layer, and comprises a colloid component and light-conversion components, wherein the light-conversion components comprise a first light-conversion component and a second light-conversion component; the first light-conversion component is used for down-converting ultraviolet light to generate short-wavelength light that is suitable for being absorbed by the perovskite top cell layer; and the second light-conversion component is used for down-converting the ultraviolet light to generate long-wavelength light that is suitable for being absorbed by both the perovskite top cell layer and the heterojunction bottom cell layer. The zoned down-conversion composite adhesive film provided in the present invention can solve the problem of insufficient photostability of perovskite materials, and can also achieve a spectral balance between the perovskite top cell layer and the heterojunction bottom cell layer by means of zoned light conversion, thereby maintaining the photogenerated current matching between upper and lower cells.

Description

Partitioned downlink composite film and its preparation method and perovskite heterojunction tandem solar cell

[0001] Cross-reference to related applications

[0002] This application claims priority to Chinese patent application No. CN202410861698.X, filed on June 28, 2024, the entire contents of which are incorporated herein by reference. Technical Field

[0003] This invention relates to the field of tandem battery technology, and more specifically, to partitioned down-conversion composite films and their preparation methods, and perovskite heterojunction tandem batteries. Background Technology

[0004] Monocrystalline silicon solar cells are solar cells made from high-purity monocrystalline silicon. Their theoretical efficiency limit is 29.4%, and currently, the photoelectric conversion efficiency of mass-produced monocrystalline silicon solar cells is in the range of 23-26%, approaching their theoretical efficiency limit. Further improvements in cell efficiency require the development of tandem technology. Perovskite materials possess excellent optical absorption properties, and since their first successful fabrication in 2009, their laboratory efficiency has improved rapidly, currently reaching a peak of 26%. Combining these two technologies could potentially achieve tandem cell efficiencies exceeding 40% in the future.

[0005] Currently, perovskite heterojunction tandem solar cell technology is in its early stages of development. Perovskite materials suffer from insufficient stability and are prone to structural decomposition under conditions of light, heat, water, and electric fields. While ultraviolet radiation from sunlight can excite photogenerated carriers in perovskite heterojunction tandem solar cells, contributing to photocurrent formation, high-energy ultraviolet radiation negatively impacts the stability of these cells. Prolonged exposure to high-energy ultraviolet light significantly reduces their photostability. Furthermore, the series-connected stacking of perovskite heterojunction tandem solar cells at both ends introduces current matching issues. Currently, there are no solutions for outdoor applications that address the photoelectric stability and current matching problems of perovskite heterojunction tandem solar cells.

[0006] Current perovskite heterojunction tandem solar cell technology employs conventional encapsulation with low-temperature processes to minimize structural decomposition that may occur during high-temperature fabrication. However, no solution exists for the long-term photostability of perovskite materials in outdoor applications. Furthermore, conventional techniques address the current matching issue in perovskite heterojunction tandem solar cells by adjusting the bandgap of the perovskite layer, the thickness of the silicon layer, and interface treatments to reduce current mismatch. However, there is an upper limit to increasing the thickness of the perovskite top layer; thicknesses exceeding the micrometer level lead to severe internal carrier recombination, significantly reducing efficiency. Therefore, conventional solutions have considerable limitations. Summary of the Invention

[0007] The purpose of this invention is to provide a partitioned down-conversion composite film and its preparation method, as well as a perovskite heterojunction tandem solar cell, so as to simultaneously solve the long-term light stability problem and the current matching problem of perovskite heterojunction tandem solar cells under outdoor use conditions.

[0008] This invention is implemented as follows:

[0009] In a first aspect, the present invention provides a partitioned downconversion composite film for encapsulating a stacked solar cell including a perovskite top cell layer and a heterojunction bottom cell layer. The partitioned downconversion composite film includes a colloidal component and a light-converting component. The light-converting component includes a first light-converting component and a second light-converting component. The first light-converting component is used to downconvert ultraviolet light to generate short-wavelength light, and the short-wavelength light is suitable for absorption by the perovskite top cell layer. The second light-converting component is used to downconvert ultraviolet light to generate long-wavelength light, and the long-wavelength light is suitable for joint absorption by the perovskite top cell layer and the heterojunction bottom cell layer.

[0010] In an optional embodiment, the weight ratio of the colloidal component to the light-converting component is 100:(1-5); the weight ratio of the first light-converting component to the second light-converting component is 1:(0.1-10).

[0011] In an optional embodiment, the first light-converting component comprises a short-wavelength light-converting material matrix and a first doping element. The short-wavelength light-converting material matrix comprises at least one of Na3Y(PO4)2, Sr3La(BO3)3, NaYF4, and CaAl2Si2O8, and the first doping element comprises Tb. 3+ Tm 3+ Ce 3+ and Er 3+ At least one of them;

[0012] Preferably, the first light-converting component includes Na3Y(PO4)2:Tb 3+ Na3Y(PO4)2:Tm 3+ Sr3La(BO3)3:Ce 3+ Sr3La(BO3)3:Tb 3+ NaYF4:Er 3+ CaAl2Si2O8:Ce 3+ CaAl2Si2O8:Tb 3+ NaYF4:Tb 3+ and NaYF4:Tm 3+ At least one of them;

[0013] Preferably, the amount of the first dopant element in the first light-converting component is 0.5-5% of the molar amount of the short-wavelength light-converting material matrix;

[0014] Preferably, the weight ratio of the colloidal component to the first light-converting component is 100:(0.5-2).

[0015] In an optional embodiment, the second light-converting component comprises a long-wavelength light-converting material matrix and a second doping element. The long-wavelength light-converting material matrix comprises at least one of NaYF4, CaAl2Si2O8, Na3Y(PO4)2, and Sr3La(BO3)3, and the second doping element comprises Yb. 3+ and Pr 3+ At least one of them;

[0016] Preferably, the second light-converting component comprises NaYF4:Yb 3+ CaAl2Si2O8:Yb 3+ Na3Y(PO4)2:Yb 3+ Na3Y(PO4)2:Pr 3+ Sr3La(BO3)3:Pr 3+ NaYF4:Pr 3+ and Sr3La(BO3)3:Yb 3+ At least one of them;

[0017] Preferably, the amount of the second dopant element in the second light-converting component is 0.5-5% of the molar amount of the long-wavelength light-converting material matrix;

[0018] Preferably, the weight ratio of the colloidal component to the second light-converting component is 100:(0.5-2).

[0019] In an optional embodiment, the wavelength of the ultraviolet light is below 400 nm, the wavelength of the short-wavelength light is 400-600 nm, and the wavelength of the long-wavelength light is 700-1200 nm.

[0020] Secondly, the present invention provides a method for preparing a partitioned down-conversion composite film as described in any of the foregoing embodiments, comprising: stirring and mixing the colloidal component and the light-converting component evenly to obtain a mixture; melting and extruding the mixture, and then casting it to form a film.

[0021] In an optional embodiment, the temperature of the melt extrusion is 90-120°C and the pressure is 40-50 MPa.

[0022] Thirdly, the present invention provides a perovskite heterojunction tandem solar cell, which includes a functional structure layer, wherein the functional structure layer is encapsulated using a partitioned transfer composite film as described in any of the foregoing embodiments, and the partitioned transfer composite film is located at least on one side of the functional structure layer.

[0023] In an optional embodiment, the perovskite heterojunction tandem solar cell includes a back cover layer, a functional structure layer, and a front cover layer stacked sequentially from bottom to top. The functional structure layer includes a bottom electrode, a heterojunction bottom cell layer, a tunneling composite junction, a first charge transport layer, a perovskite top cell layer, a second charge transport layer, a current collection layer, and a top electrode stacked sequentially from bottom to top. The partitioned bottom transfer composite film is disposed between the functional structure layer and the front cover layer, and between the functional structure layer and the back cover layer. The partitioned bottom transfer composite film covers the outer surface of the functional structure layer.

[0024] In an optional embodiment, the thickness of the partitioned transfer composite film is 0.3-0.7 mm.

[0025] The present invention has the following beneficial effects:

[0026] The partitioned downconversion composite film provided by this invention incorporates a light-converting component into its colloidal composition. This component enables partitioned downconversion of ultraviolet light from the solar spectrum, generating both short-wavelength and long-wavelength light. The short-wavelength light is primarily absorbed by the perovskite top solar cell layer, while the long-wavelength light is absorbed by both the perovskite top solar cell layer and the heterojunction bottom solar cell layer. Since ultraviolet light has higher energy than visible light, it more easily excites molecules or causes reactions, leading to reduced photostability of perovskite materials. This invention modulates the incident spectrum by adjusting the ratio of short-wavelength to long-wavelength light, converting ultraviolet light into low-energy visible light, thus solving the problem of insufficient photostability in perovskite materials. Simultaneously, partitioned downconversion achieves spectral balance between the perovskite top solar cell layer and the heterojunction bottom solar cell layer, maintaining the photocurrent matching between the upper and lower cells. The partitioned downconversion composite film provided by this invention can be widely used in the fabrication of battery modules that improve the photocurrent of tandem cells by modulating and distributing the spectral intensities of short-wavelength and long-wavelength bands. In particular, the perovskite heterojunction tandem solar cell encapsulated with the above-mentioned partitioned bottom-transfer composite film has good light stability and excellent photocurrent matching between the upper and lower cells. Attached Figure Description

[0027] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1 is a schematic diagram of the structure of a perovskite heterojunction tandem solar cell according to a specific embodiment of the present invention. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0030] The first aspect of the present invention provides a partitioned bottom-conversion composite film for encapsulating a stacked battery including a perovskite top cell layer and a heterojunction bottom cell layer, the partitioned bottom-conversion composite film comprising a colloidal component and a light-converting component.

[0031] The colloidal component is a conventional component of the film. The colloidal component may include polyethylene (50%-80%), polybutene or polyhexene or polyoctene (20-50%) by weight percentage.

[0032] The light conversion component includes a first light conversion component and a second light conversion component. The first light conversion component is used to convert ultraviolet light down to generate short-wavelength light, which is suitable for absorption by the perovskite top cell layer. The second light conversion component is used to convert ultraviolet light down to generate long-wavelength light, which is suitable for absorption by both the perovskite top cell layer and the heterojunction bottom cell layer.

[0033] In this invention, both the first and second light-converting components belong to light-emitting conversion materials. These materials are generally classified as upconversion light-emitting materials and downconversion light-emitting materials. Upconversion light-emitting materials can absorb low-energy, long-wavelength light (such as infrared light) and emit high-energy, short-wavelength light (such as visible light), thus improving the light utilization efficiency of solar cells in the infrared region. Downconversion light-emitting materials, when excited by short-wavelength light (such as ultraviolet light), emit long-wavelength light (such as visible light), broadening the light absorption range of the solar cell into the ultraviolet region, thereby improving the photoelectric conversion efficiency of the cell. Specifically, in this invention, both the first and second light-converting components belong to downconversion light-emitting materials.

[0034] Furthermore, the first light-converting component can convert ultraviolet light with wavelengths below 400 nm into short-wavelength light, with a wavelength range of 400-600 nm. The second light-converting component can convert ultraviolet light with wavelengths below 400 nm into long-wavelength light, with a wavelength range of 700-1200 nm. In this invention, by adding light-converting components to the colloidal component, ultraviolet light is converted into light in sections. By adjusting the ratio of short-wavelength to long-wavelength light, the incident spectrum is modulated, converting ultraviolet light into low-energy visible light. This solves the problem of insufficient photostability in perovskite materials. At the same time, the sectioned light conversion achieves spectral balance between the perovskite top cell layer and the heterojunction bottom cell layer, maintaining the matching of photocurrent between the upper and lower cells.

[0035] In one specific embodiment, the weight ratio of the colloidal component and the light-converting component can be 100:(1-5), for example, it can be any one of 100:1, 100:2, 100:3, 100:4, 100:5 or any range between two of them. The present invention has found that when the amount of the light-converting component exceeds 5%, the light-converting components are prone to agglomeration, which makes the light conversion effect worse.

[0036] Furthermore, there is no specific limitation on the ratio of the first and second light-converting components. It can be adjusted based on spectral compatibility, the specific design of the perovskite top cell and the heterojunction bottom cell, current matching, etc. A typical but non-limiting example is provided in this invention: the weight ratio of the first and second light-converting components can be 1:(0.1-10), for example, any one of 1:0.1, 1:0.2, 1:0.5, 1:0.8, 1:1, 1:2, 1:5, 1:8, or 1:10, or a range between any two. Preferably, the weight ratio of the first and second light-converting components is 1:(1-5), within which the light conversion matching is better.

[0037] In one specific embodiment, the weight ratio of the colloidal component to any one of the first light-converting components can be 100:(0.5-2); the weight ratio of the colloidal component to any one of the second light-converting components can also be 100:(0.5-2). In this invention, by limiting the total amount of the light-converting components and the individual amounts of any one of the first and second light-converting components, and adjusting the amounts of the first and second light-converting components within the aforementioned ranges, superior stability and current matching can be achieved.

[0038] In one specific embodiment, the first light-converting component may include a short-wavelength light-converting material matrix and a first doping element. Further, the short-wavelength light-converting material matrix may include at least one of Na3Y(PO4)2, Sr3La(BO3)3, NaYF4, and CaAl2Si2O8, and the first doping element may include Tb. 3+ Tm 3+ Ce 3+ and Er 3+ At least one of them.

[0039] Preferably, the first light-converting component includes Na3Y(PO4)2:Tb 3+ Na3Y(PO4)2:Tm 3+ Sr3La(BO3)3:Ce 3+ Sr3La(BO3)3:Tb 3+ NaYF4:Er 3+ CaAl2Si2O8:Ce 3+ CaAl2Si2O8:Tb 3+ NaYF4:Tb 3+ and NaYF4:Tm 3+ At least one of the following; the amount of the first dopant element in the first light-converting component can be 0.5-5% of the molar amount of the short-wavelength light-converting material matrix. For example, Tb 3+ The amount of dopant element used is 0.5-5% of the molar amount of Na3Y(PO4)2. In this invention, the first light-converting component can convert ultraviolet light with a wavelength range below 400nm into short-wavelength light, with a wavelength range of 400-600nm, thereby improving the absorption of the perovskite top cell layer.

[0040] In one specific embodiment, the second light-converting component may include a long-wavelength light-converting material matrix and a second doping element. Further, the long-wavelength light-converting material matrix may include at least one of NaYF4, CaAl2Si2O8, Na3Y(PO4)2, and Sr3La(BO3)3, and the second doping element may include Yb. 3+ and Pr 3+ At least one of them.

[0041] Preferably, the second light-converting component includes NaYF4:Yb 3+ CaAl2Si2O8:Yb 3+ Na3Y(PO4)2:Yb 3+ Na3Y(PO4)2:Pr 3+ Sr3La(BO3)3:Pr 3+ NaYF4:Pr 3+and Sr3La(BO3)3:Yb 3+ At least one of the following; wherein NaYF4, CaAl2Si2O8, Na3Y(PO4)2, Sr3La(BO3)3, etc. are used as matrix materials, while Yb 3+ Pr 3+ The second dopant element can be used as a dopant; the amount of the second dopant element in the second optical conversion component can be 0.5-5% of the molar amount of the long-wavelength optical conversion material matrix. For example, Yb 3+ The amount of dopant element used is 0.5-5% of the molar amount of NaYF4. In this invention, the second light-converting component can convert ultraviolet light with a wavelength range below 400nm into long-wavelength light with a wavelength range of 700-1200nm, thereby improving the common absorption of the perovskite top cell layer and the heterojunction bottom cell layer.

[0042] This invention, by adding a light-converting component to the colloidal component, enables the segmented downconversion of ultraviolet light from the solar spectrum, generating two types of light: short-wavelength and long-wavelength. The short-wavelength light is primarily absorbed by the perovskite top solar cell layer, while the long-wavelength light is absorbed by both the perovskite top solar cell layer and the heterojunction bottom solar cell layer. Since ultraviolet light has higher energy than visible light, it more easily excites molecules or reactions, leading to reduced photostability of perovskite materials. Therefore, this invention modulates the incident spectrum by adjusting the ratio of short-wavelength to long-wavelength light, converting ultraviolet light into low-energy visible light, thereby solving the problem of insufficient photostability in perovskite materials. Meanwhile, spectral modulation perfectly solves the current matching problem caused by the series stacking of the perovskite top layer and the heterojunction bottom layer in the two-end structure. This allows the perovskite materials in the perovskite top layer and the heterojunction bottom layer to achieve good current matching at a conventional thickness (e.g., 400-600 nm), without needing to increase the thickness of the perovskite top layer to improve the current matching problem. Therefore, it avoids the problem of severe internal carrier recombination caused by an excessively thick perovskite top layer (micrometer level). The solution of this invention provides an outdoor application component solution for achieving photoelectric stability and current matching in tandem solar cells.

[0043] To achieve better light conversion effect, the thickness of the partitioned down-conversion composite film in this invention is 0.3-0.7 mm. Research in this invention has found that when the thickness of the partitioned down-conversion composite film is within the above range, its light conversion effect is even better.

[0044] A second aspect of the present invention also provides a method for preparing the above-mentioned partitioned down-conversion composite film, comprising: mixing a colloidal component and a light-converting component uniformly to obtain a mixture; melting and extruding the mixture, and then casting it to form a film. At this point, the light-converting component is uniformly dispersed within the colloidal component, and after subsequent casting to form a film, the partitioned down-conversion composite film can be prepared.

[0045] In one specific embodiment, the melt extrusion temperature can be 90-120°C, and the pressure can be 40-50 MPa. It should be understood that after the mixture is extruded and cast, conventional cooling, traction, and winding processes are also included.

[0046] The partitioned down-conversion composite film provided by this invention can be widely used in the fabrication of battery modules that improve the photocurrent of tandem cells by modulating and distributing the spectral intensity of short-wavelength and long-wavelength bands. Specifically, the partitioned down-conversion composite film can be used to fabricate perovskite heterojunction tandem cells.

[0047] Therefore, a third aspect of the present invention also provides a perovskite heterojunction tandem solar cell, which includes a functional structure layer, wherein the functional structure layer is encapsulated using the aforementioned partitioned transfer composite film, and the partitioned transfer composite film is located at least on one side of the functional structure layer.

[0048] In one specific embodiment, referring to Figure 1, the perovskite heterojunction tandem solar cell may include a back cover layer, a functional structure layer, and a front cover layer stacked sequentially from bottom to top. The functional structure layer may include a bottom electrode, a heterojunction bottom cell layer, a tunneling composite junction, a first charge transport layer, a perovskite top cell layer, a second charge transport layer, a current collection layer, and a top electrode stacked sequentially from bottom to top. A partitioned transfer composite film is disposed between the functional structure layer and the front cover layer, and between the functional structure layer and the back cover layer, and the partitioned transfer composite film covers the outer surface of the functional structure layer.

[0049] It should be understood that, in other embodiments, the partitioned undercoat composite film may be located only between the functional structure layer and the front cover layer, while the functional structure layer and the back cover layer are encapsulated by a common film.

[0050] Alternatively, the partitioned undercoat composite film can be located only between the functional structure layer and the back cover layer, while the functional structure layer and the front cover layer are encapsulated by ordinary film.

[0051] The encapsulation structure described above in this invention can significantly improve the light stability and current matching of perovskite heterojunction tandem solar cells. Furthermore, using a combination of partitioned down-conversion composite film and ordinary film for encapsulation can also improve light stability and current matching to a certain extent, while also helping to reduce costs.

[0052] The features and performance of the present invention will be further described in detail below with reference to embodiments.

[0053] Example 1

[0054] This embodiment provides a partitioned down-conversion composite film, which includes an adhesive component and a light-converting component. The adhesive component comprises 60% polyethylene and 40% polybutene by weight percentage. The light-converting component includes Na3Y(PO4)2:Tb. 3+ Na3Y(PO4)2:Tm 3+ Sr3La(BO3)3:Yb 3+ Based on the weight of the colloidal components, the corresponding amounts of the light-converting components are 0.5%, 0.5%, and 2%. Among them, Na3Y(PO4)2:Tb 3+ Na3Y(PO4)2:Tm 3+ The first light-converting component, wherein the amount of the first dopant element is 3% of the molar amount of the short-wavelength light-converting material matrix; Sr3La(BO3)3:Yb 3+ The second light-converting component is used, wherein the amount of the second dopant element is 0.5% of the molar amount of the long-wavelength light-converting material matrix.

[0055] The preparation method includes mixing the colloidal component and the light-converting component according to the above ratio, placing them in an extruder for melt extrusion, the melt extrusion temperature is 100℃ and the pressure is 40MPa, and the extrudate is cast to form a film.

[0056] Example 2

[0057] This embodiment provides a partitioned down-conversion composite film, which includes a colloidal component and a light-converting component. The colloidal component is the same as in Example 1, and the light-converting component includes NaYF4:Yb. 3+ CaAl2Si2O8:Ce 3+ CaAl2Si2O8:Tb 3+ Based on the weight of the colloidal components, the corresponding amounts of the light-converting components are 2%, 0.8%, and 0.8%. Among them, NaYF4:Yb 3+ The second light-converting component, wherein the amount of the second dopant element is 1% of the molar amount of the long-wavelength light-converting material matrix; CaAl2Si2O8:Ce 3+ and CaAl2Si2O8:Tb 3+ The first light-converting component is used, wherein the amount of the first dopant element is 5% of the molar amount of the short-wavelength light-converting material matrix.

[0058] Example 3

[0059] This embodiment provides a partitioned down-conversion composite film, which includes a colloidal component and a light-converting component. The colloidal component is the same as in Example 1, and the light-converting component includes Na3Y(PO4)2:Pr 3+ Sr3La(BO3)3:Pr 3+ NaYF4:Tm 3+Based on the weight of the colloidal components, the corresponding amounts of the light-converting components are 1.8%, 0.8%, and 1%. Among them, Na3Y(PO4)2:Pr 3+ and Sr3La(BO3)3:Pr 3+ The second light-converting component, wherein the amount of the second dopant element is 5% of the molar amount of the long-wavelength light-converting material matrix; NaYF4:Tm 3+ The first light-converting component is used, wherein the amount of the first dopant element is 0.5% of the molar amount of the short-wavelength light-converting material matrix.

[0060] Comparative Example 1

[0061] This comparative example provides a film that is basically the same as that in Example 1, except that the first light-converting component and the second light-converting component are not added in this comparative example.

[0062] Comparative Example 2

[0063] This comparative example provides a film that is basically the same as that in Example 1, except that no first light-converting component is added in this comparative example.

[0064] Comparative Example 3

[0065] This comparative example provides a film that is basically the same as that in Example 1, except that no second light-converting component is added in this comparative example.

[0066] Experimental Example

[0067] The encapsulant films provided in Examples 1-3 and Comparative Examples 1-3 were used as encapsulation films to prepare perovskite heterojunction tandem solar cells. Please refer to Figure 1. The perovskite heterojunction tandem solar cell includes, from bottom to top, a back cover layer, a functional structure layer, and a front cover layer. The functional structure layer includes, from bottom to top, a lower electrode, a heterojunction bottom cell layer, a tunneling composite junction, a first charge transport layer, a perovskite top cell layer, a second charge transport layer, a current collection layer, and an upper electrode. A partitioned bottom transfer composite encapsulant film is disposed between the back cover layer and the front cover layer. The partitioned bottom transfer composite encapsulant film covers the outer surface of the functional structure layer. The thickness of the partitioned bottom transfer composite encapsulant film is 0.5 mm.

[0068] The photostability and current matching of the perovskite heterojunction tandem solar cells prepared with the above different films were tested.

[0069] The methods for detecting photostability include: MPPT stability test 1 day, 300 hours.

[0070] Methods for detecting current matching include: EQE test.

[0071] The test results are as follows:

[0072] As can be seen from the table above, Examples 1-3 of the present invention exhibit excellent photostability, and the photocurrents of the perovskite and silicon heterojunction are closer, resulting in high matching. In Comparative Example 1, the absence of the first and second light-converting components leads to significantly lower photostability and matching compared to Example 1. In Comparative Example 2, the second light-converting component was added, but the first component was not. The second component converted ultraviolet light to produce long-wavelength light, which is mainly absorbed by both the perovskite and silicon heterojunction. Therefore, it can be seen that the photocurrent of the perovskite in Comparative Example 2 is significantly lower than that in Example 1, resulting in a significant decrease in matching. In Comparative Example 3, the first light-converting component was added, but the second component was not. The first component converted ultraviolet light to produce short-wavelength light, which is mainly absorbed by the perovskite. In this case, the photocurrent of the heterojunction cell is significantly lower than that in Example 1, also resulting in a significant decrease in matching. Because Comparative Examples 2-3 only added one of the first and second light-converting components, they were unable to effectively convert ultraviolet light into low-energy visible light, resulting in significantly lower photostability than Example 1. Furthermore, compared to Comparative Example 1, which did not add any of the first or second light-converting components, their photostability increased slightly, but not significantly. In contrast, Example 1, by adding both components simultaneously, showed a significant improvement in photostability, demonstrating that the combined addition of the first and second light-converting components has a synergistic effect. In summary, the photostability of the perovskite heterojunction tandem solar cells obtained in Examples 1-3 of this invention is significantly better than that of Comparative Examples 1-3. Simultaneously, the matching between the photocurrent generated by the perovskite and the photocurrent generated by the heterojunction solar cell is better, significantly superior to Comparative Examples 1-3.

[0073] In summary, the partitioned downconversion composite film provided by this invention incorporates a light-converting component into the colloidal component. This component enables partitioned downconversion of ultraviolet light from the solar spectrum, generating both short-wavelength and long-wavelength light. The short-wavelength light is primarily absorbed by the perovskite top solar cell layer, while the long-wavelength light is absorbed by both the perovskite top solar cell layer and the heterojunction bottom solar cell layer. Since ultraviolet light has higher energy than visible light, it more easily excites molecules or reactions, leading to reduced photostability of perovskite materials. This invention modulates the incident spectrum by adjusting the ratio of short-wavelength to long-wavelength light, converting ultraviolet light into low-energy visible light, thus solving the problem of insufficient photostability in perovskite materials. Simultaneously, partitioned downconversion achieves spectral balance between the perovskite top solar cell layer and the heterojunction bottom solar cell layer, maintaining the matching of photocurrent between the upper and lower cells.

[0074] The partitioned down-conversion composite film provided by this invention can be widely used in the preparation of battery modules that improve the photocurrent of tandem cells by modulating and distributing the spectral intensity of short-wave and long-wave bands. In particular, perovskite heterojunction tandem cells encapsulated with the above-mentioned partitioned down-conversion composite film have good light stability and excellent photocurrent matching between the upper and lower cells.

[0075] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A partitioned transfer composite film, characterized in that, For encapsulating stacked solar cells including a perovskite top cell layer and a heterojunction bottom cell layer, the partitioned downconversion composite film includes a colloidal component and a light-converting component. The light-converting component includes a first light-converting component and a second light-converting component. The first light-converting component is used to downconvert ultraviolet light to generate short-wavelength light, and the short-wavelength light is suitable for absorption by the perovskite top cell layer. The second light-converting component is used to downconvert ultraviolet light to generate long-wavelength light, and the long-wavelength light is suitable for joint absorption by the perovskite top cell layer and the heterojunction bottom cell layer.

2. The partitioned transfer composite film according to claim 1, characterized in that, The weight ratio of the colloidal component to the optically convertible component is 100:(1-5); the weight ratio of the first optically convertible component to the second optically convertible component is 1:(0.1-10).

3. The partitioned transfer composite film according to claim 1 or 2, characterized in that, The first light-converting component comprises a short-wavelength light-converting material matrix and a first doping element. The short-wavelength light-converting material matrix comprises at least one of Na3Y(PO4)2, Sr3La(BO3)3, NaYF4, and CaAl2Si2O8, and the first doping element comprises Tb. 3+ Tm 3+ Ce 3+ and Er 3+ At least one of them; and / or, The second light-converting component comprises a long-wavelength light-converting material matrix and a second doping element. The long-wavelength light-converting material matrix comprises at least one of NaYF4, CaAl2Si2O8, Na3Y(PO4)2, and Sr3La(BO3)3, and the second doping element comprises Yb. 3+ and Pr 3+ At least one of them.

4. The partitioned transfer composite film according to any one of claims 1-3, characterized in that, The first optically convertible component includes Na3Y(PO4)2:Tb 3+ Na3Y(PO4)2:Tm 3+ Sr3La(BO3)3:Ce 3+ Sr3La(BO3)3:Tb 3+ NaYF4:Er 3+ CaAl2Si2O8:Ce 3+ CaAl2Si2O8:Tb 3+ NaYF4:Tb 3+ and NaYF4:Tm 3+ At least one of them; and / or, The second optically convertible component includes NaYF4:Yb 3+ CaAl2Si2O8:Yb 3+ Na3Y(PO4)2:Yb 3+ Na3Y(PO4)2:Pr 3+ Sr3La(BO3)3:Pr 3+ NaYF4:Pr 3+ and Sr3La(BO3)3:Yb 3+ At least one of them.

5. The partitioned transfer composite film according to claim 3 or 4, characterized in that, The amount of the first dopant element in the first light-converting component is 0.5-5% of the molar amount of the short-wavelength light-converting material matrix; and / or, The amount of the second doping element in the second light-converting component is 0.5-5% of the molar amount of the long-wavelength light-converting material matrix.

6. The partitioned transfer composite film according to any one of claims 1-5, characterized in that, The weight ratio of the colloidal component to the first optically convertible component is 100:(0.5-2); and / or, The weight ratio of the colloidal component to the second optically convertible component is 100:(0.5-2).

7. The partitioned transfer composite film according to any one of claims 1-6, characterized in that, The wavelength of the ultraviolet light is below 400nm, the wavelength of the short-wavelength light is 400-600nm, and the wavelength of the long-wavelength light is 700-1200nm.

8. A method for preparing a partitioned transfer composite film as described in any one of claims 1-7, characterized in that, It includes: The colloidal component and the light-converting component are stirred and mixed evenly to obtain a mixture. The mixture is melt-extruded and then cast to form a film.

9. The method for preparing the partitioned transfer composite film as described in claim 8, characterized in that, The temperature of the melt extrusion is 90-120℃ and the pressure is 40-50MPa.

10. A perovskite heterojunction tandem solar cell, characterized in that, It includes a functional structure layer, which is encapsulated using a partitioned transfer composite film as described in any one of claims 1-7, wherein the partitioned transfer composite film is located at least on one side of the functional structure layer.

11. The perovskite heterojunction tandem solar cell according to claim 10, characterized in that, The perovskite heterojunction tandem solar cell includes a back cover layer, the functional structure layer, and a front cover layer stacked sequentially from bottom to top. The functional structure layer includes a bottom electrode, a heterojunction bottom cell layer, a tunneling composite junction, a first charge transport layer, a perovskite top cell layer, a second charge transport layer, a current collection layer, and a top electrode stacked sequentially from bottom to top. A partitioned bottom-transfer composite film is disposed between the functional structure layer and the front cover layer, and between the functional structure layer and the back cover layer, and the partitioned bottom-transfer composite film covers the outer surface of the functional structure layer.

12. The perovskite heterojunction tandem solar cell according to claim 10 or 11, characterized in that, The thickness of the partitioned transfer composite film is 0.3-0.7 mm.

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