A three-terminal stacked solar cell based on silicon nanowire structure

Abstract

This application provides a three-terminal tandem solar cell based on a silicon nanowire structure, relating to the field of solar cell technology. In the perovskite top cell of this application, a first electrode layer is provided facing the incident light, while in the crystalline silicon bottom cell, a second and third electrode layer are provided facing away from the incident light. Furthermore, multiple nanowire structures are spaced apart on the side of the N-type silicon absorber layer facing the incident light. The nanowire structure can enhance the coupling and propagation of long-wavelength photons to the N-type silicon absorber layer through waveguide effects and light field modulation, and it exhibits subwavelength optical characteristics, achieving anti-reflection effects over a wide spectral range and improving the absorption efficiency of the crystalline silicon bottom cell for long-wavelength photons. In addition, by setting a three-electrode structure, the overall energy output performance of the cell is improved.

Description

Technical Field

[0001] This invention relates to the field of solar cell technology, and in particular to a three-terminal tandem solar cell based on a silicon nanowire structure. Background Technology

[0002] The improvement of solar photovoltaic conversion efficiency largely depends on the ability of solar cells to capture and utilize the solar spectrum. Limited by the inherent bandgap characteristics of crystalline silicon materials, single-junction silicon solar cells have a physical limit to the energy utilization of short-wavelength photons. Existing technologies, by stacking wide-bandgap perovskite materials with narrow-bandgap crystalline silicon materials, achieve segmented absorption of the solar spectrum, which has become an important technical approach to improve photoelectric conversion efficiency.

[0003] In perovskite / silicon tandem solar cells, the choice of bottom cell structure has a significant impact on the overall optical performance of the device. Crystalline silicon back-contact solar cells, as bottom cells, place metal electrodes on the back surface, eliminating metal shading losses on the light-receiving surface. From an optical perspective, crystalline silicon back-contact solar cells are an ideal tandem bottom cell structure, and the physical morphology of its light-receiving surface directly determines the interface reflection behavior and the absorption efficiency of long-wavelength photons.

[0004] However, existing technologies for setting silicon absorber layers have some shortcomings. On the one hand, the silicon absorber layers in crystalline silicon back-contact solar cells are mostly planar structures. The significant refractive index difference between the planar silicon absorber layer and the upper functional film makes the interface prone to strong specular reflection, leading to increased long-wavelength light loss. On the other hand, even with a micrometer-scale pyramidal textured structure on the side of the silicon absorber layer facing the incident light, although multiple reflections can reduce some of the interface reflection, its size is much larger than the incident light wavelength. It relies mainly on geometric optics for modulation, which can easily cause uncontrollable deflection of the light propagation path in the multilayer dielectric environment of perovskite / silicon tandem solar cells. This limits its ability to modulate the light field for long-wavelength light, making it difficult to achieve sufficient absorption of long-wavelength photons. Furthermore, existing perovskite / silicon tandem solar cells typically employ a dual-electrode structure. Even if this improves the absorption efficiency for long-wavelength light, the dual-electrode structure easily leads to an imbalance in the recombination of photogenerated electrons and holes in the intermediate conductive layer, and makes it difficult to achieve high current output. Summary of the Invention

[0005] One objective of this invention is to provide a three-terminal tandem solar cell based on a silicon nanowire structure, which solves the technical problem in the prior art that the cells lack the ability to simultaneously improve the absorption capacity of long-wavelength photons and the current output capacity.

[0006] Specifically, this invention provides a three-terminal tandem solar cell based on a silicon nanowire structure, comprising a perovskite top cell, an intermediate connecting layer, and a crystalline silicon bottom cell arranged in a stacked manner, wherein...

[0007] The perovskite top solar cell includes a first electrode layer, a transparent conductive layer, a first electron transport layer, a perovskite absorption layer and a first hole transport layer arranged in sequence from top to bottom, and the first electrode layer is provided with an array of anti-reflection layers.

[0008] The crystalline silicon bottom solar cell includes a second electron transport layer, an N-type silicon absorber layer, a first composite functional layer, and a second composite functional layer stacked sequentially from top to bottom. The N-type silicon absorber layer has multiple nanowire structures that bulge towards the perovskite top solar cell and are spaced apart, such that the first hole transport layer, the intermediate connecting layer, and the second electron transport layer are conformally disposed with the N-type silicon absorber layer. The first composite functional layer includes multiple second hole transport layers and multiple third electron transport layers arranged at intervals, with the second hole transport layers and the third electron transport layers alternating. The second composite functional layer includes multiple second electrode layers aligned with each second hole transport layer and multiple third electrode layers aligned with each third electron transport layer. The height of each nanowire structure is any value between 10 nm and 1000 nm, the diameter is any value between 10 nm and 200 nm, and the spacing between two adjacent nanowire structures is any value between 50 nm and 500 nm.

[0009] Optionally, the thickness of the N-type silicon absorber layer is any value between 100μm and 200μm; the thickness of the second electron transport layer is any value between 5nm and 50nm, and the material is N-type phosphorus-doped polycrystalline silicon or N-type phosphorus-doped amorphous silicon.

[0010] Optionally, the thickness of each second hole transport layer is any value between 10 nm and 100 nm, and the material is P-type boron-doped amorphous silicon, P-type boron-doped polycrystalline silicon, or NiO. x ;

[0011] The thickness of each of the third electron transport layers is any value between 10 nm and 100 nm, and the material is N-type phosphorus-doped polycrystalline silicon, N-type phosphorus-doped amorphous silicon, or TiO₂. x .

[0012] Optionally, the thickness of each second electrode layer and each third electrode layer is any value between 50nm and 500nm, and the material is selected from silver, copper or gold.

[0013] Optionally, the thickness of the first electrode layer is any value between 50nm and 500nm, and the material is selected from silver, copper or gold.

[0014] The thickness of the antireflection layer is any value between 50nm and 500nm, and the material is selected as MgF₂. x LiF, SiO x Or at least one of Al2O3.

[0015] Optionally, the thickness of the transparent conductive layer is any value between 20nm and 500nm, and the material is at least one of ITO, AZO, IZO, or FTO.

[0016] Optionally, the thickness of the perovskite absorber layer is any value between 100 nm and 1500 nm.

[0017] Optionally, the thickness of the first electron transport layer is any value between 10nm and 100nm, and the material is selected from at least one of SnO2, TiO2, ZnO, C60, or PCBM.

[0018] Optionally, the thickness of the first hole transport layer is any value between 1 nm and 10 nm, and the material is selected as MeO, PTAA, or NiO. x Any one of them.

[0019] Optionally, the thickness of the intermediate connecting layer is any value between 1nm and 100nm, and the material is ITO or IZO.

[0020] In this invention, the N-type silicon absorber layer is provided with multiple nanowire structures convex towards the perovskite top cell and arranged at intervals. These nanowire structures can form local waveguide channels under the action of incident light and modulate the optical field, thereby enhancing the coupling and propagation of long-wavelength photons into the N-type silicon absorber layer. This increases the effective optical path length of long-wavelength photons in the N-type silicon absorber layer, thus improving the absorption efficiency of long-wavelength light by the crystalline silicon bottom cell. Simultaneously, by synergistically designing the periodic size parameters of the nanowire structures, the period and size of multiple nanowire structures are made smaller than or close to the wavelength of the incident light. This allows the multiple arrayed nanowire structures on the surface of the N-type silicon absorber layer to exhibit subwavelength optical characteristics, resulting in a continuous gradual change in the equivalent refractive index of the incident light within the nanowire structures. This effectively reduces the reflection loss at the N-type silicon absorber layer interface, achieving anti-reflection effects over a wide spectral range and further promoting the coupling and propagation of long-wavelength photons into the N-type silicon absorber layer. Furthermore, the first hole transport layer, the intermediate connecting layer, and the second electron transport layer are all conformally configured with the N-type silicon absorber layer, allowing each layer to adhere closely. This eliminates photon scattering and reflection losses at the interface and guides light to propagate along the concave-convex conformal interface, forming a complex path. This increases the effective optical path length within the N-type silicon absorber layer, enhancing the trapping efficiency of long-wavelength photons and improving the capture efficiency of long-wavelength photons in the crystalline silicon bottom cell. Additionally, the back surface of the crystalline silicon bottom cell has independent second and third electrode layers, while the light-receiving surface of the perovskite top cell has a first electrode layer. This three-terminal electrode configuration ensures that the optical gain achieved by the silicon nanowire structure in the crystalline silicon bottom cell can be fully extracted, thereby simultaneously improving the utilization efficiency of incident light and the overall energy output performance of the three-terminal tandem solar cell.

[0021] The above and other objects, advantages and features of the present invention will become more apparent to those skilled in the art from the following detailed description of specific embodiments of the invention in conjunction with the accompanying drawings. Attached Figure Description

[0022] The following sections will describe some specific embodiments of the invention in detail by way of example and not limitation, with reference to the accompanying drawings. The same reference numerals in the drawings denote the same or similar parts or portions. Those skilled in the art should understand that these drawings are not necessarily drawn to scale. In the drawings:

[0023] Figure 1 This is a schematic front view of a three-terminal tandem solar cell according to an embodiment of the present invention;

[0024] Figure 2 This is a schematic top view of a three-terminal tandem solar cell according to an embodiment of the present invention;

[0025] Figure 3 The absorption spectra of the three-terminal tandem solar cells according to Example 1 and Comparative Example 1 are shown.

[0026] Figure 4The reflection spectra are based on the three-terminal tandem solar cells of Example 1 and Comparative Example 1.

[0027] Figure 5 This is a schematic diagram of the electric field distribution of the three-terminal tandem solar cells according to Example 1 and Comparative Example 1 at a wavelength of 800 nm.

[0028] Figure 6 This is a schematic diagram of the electric field distribution of the three-terminal tandem solar cells according to Example 1 and Comparative Example 1 at a wavelength of 900nm.

[0029] Figure reference numerals: 100-Three-terminal tandem solar cell, 1-Perovskite top cell, 2-Intermediate connecting layer, 3-Crystalline silicon bottom cell, 11-First electrode layer, 12-Transparent conductive layer, 13-First electron transport layer, 14-Perovskite absorber layer, 15-First hole transport layer, 16-Antireflection layer, 31-Second electron transport layer, 32-N-type silicon absorber layer, 33-First composite functional layer, 34-Second composite functional layer, 35-Nanowire structure, 331-Second hole transport layer, 332-Third electron transport layer, 341-Second electrode layer, 342-Third electrode layer. Detailed Implementation

[0030] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, the specific embodiments of this application will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of this application. Furthermore, it should be noted that, for ease of description, only the parts relevant to this application are shown in the accompanying drawings, not the entire structure. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without inventive effort are within the scope of protection of this application.

[0031] The terms “comprising” and “having”, and any variations thereof, used in this application are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or apparatus that includes a series of steps or units is not limited to the steps or units listed, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to such process, method, product, or apparatus.

[0032] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0033] Figure 1 This is a schematic front view of a three-terminal tandem solar cell according to an embodiment of the present invention. Figure 2 This is a schematic top view of a three-terminal tandem solar cell according to an embodiment of the present invention.

[0034] like Figure 1 and Figure 2 As shown, the three-terminal tandem solar cell 100 includes a perovskite top cell 1, an intermediate connecting layer 2, and a crystalline silicon bottom cell 3 arranged in a stacked manner. The perovskite top cell 1 includes a first electrode layer 11, a transparent conductive layer 12, a first electron transport layer 13, a perovskite absorption layer 14, and a first hole transport layer 15 arranged in a stacked manner from top to bottom. The first electrode layer 11 is provided with an array of antireflection layers 16. The crystalline silicon bottom cell 3 includes a second electron transport layer 31, an N-type silicon absorber layer 32, a first composite functional layer 33, and a second composite functional layer 34 stacked sequentially from top to bottom. The N-type silicon absorber layer 32 has multiple nanowire structures 35 that protrude toward the perovskite top cell 1 and are spaced apart, so that the first hole transport layer 15, the intermediate connection layer 2, and the second electron transport layer 31 are conformally disposed with the N-type silicon absorber layer 32. The first composite functional layer 33 includes multiple second hole transport layers 331 and multiple third electron transport layers 332 arranged at intervals, with the second hole transport layers 331 and the third electron transport layers 332 arranged alternately. The second composite functional layer 34 includes multiple second electrode layers 341 aligned with each second hole transport layer 331 and multiple third electrode layers 342 aligned with each third electron transport layer 332. Each nanowire structure 35 has a height of any value between 10 nm and 1000 nm, a diameter of any value between 10 nm and 200 nm, and a spacing between two adjacent nanowire structures 35 of any value between 50 nm and 500 nm. Notably, the side of the N-type silicon absorber layer 32 facing away from the incident light is a planar structure.

[0035] In this embodiment, the N-type silicon absorber layer 32 is provided with a plurality of nanowire structures 35 that protrude toward the perovskite top cell 1 and are spaced apart. These nanowire structures can form local waveguide channels under the action of incident light and modulate the light field, thereby enhancing the coupling and propagation of long-wavelength photons into the N-type silicon absorber layer 32. This increases the effective optical path of long-wavelength photons in the N-type silicon absorber layer 32, thereby improving the absorption efficiency of long-wavelength light by the crystalline silicon bottom cell 3. Meanwhile, by coordinating the periodic size parameters of the nanowire structure 35, the period and size of multiple nanowire structures 35 are made smaller than or close to the wavelength of the incident light. This allows the multiple arrays of nanowire structures 35 arranged on the surface of the N-type silicon absorber layer 32 to exhibit subwavelength optical characteristics, so that the incident light exhibits a continuous and gradual change in equivalent refractive index in the nanowire structure 35. This effectively reduces the reflection loss at the interface of the N-type silicon absorber layer 32, achieves antireflection effect over a wide spectral range, and further promotes the coupling and propagation of long-wavelength photons into the N-type silicon absorber layer 32, so that the crystalline silicon bottom cell 3 has both wide-spectral antireflection capability and long-wavelength light absorption enhancement effect. Furthermore, the first hole transport layer 15, the intermediate connecting layer 2, and the second electron transport layer 31 are all conformally configured with the N-type silicon absorption layer 32, allowing each layer to adhere closely. This eliminates photon scattering and reflection losses at the interface and guides light to propagate along the concave-convex conformal interface, forming a complex path. This increases the effective optical path length within the N-type silicon absorption layer 32, enhancing the trapping efficiency of long-wavelength photons and improving the capture efficiency of long-wavelength photons by the crystalline silicon bottom cell 3. In addition, the back surface of the crystalline silicon bottom cell 3 has independent second electrode layers 341 and third electrode layers 342, and the light-receiving surface of the perovskite top cell 1 has a first electrode layer 11. The arrangement of the three electrodes ensures that the optical gain achieved by the silicon nanowire structure 35 in the crystalline silicon bottom cell 3 can be fully extracted, thereby simultaneously improving the utilization efficiency of the incident light and the overall energy output performance of the three-terminal tandem solar cell 100.

[0036] In this embodiment, the height of each nanowire structure 35 is set to 10nm-1000nm, enabling the nanowire structure 35 to have good optical field modulation capability in the vertical direction. This allows for multiple refractions and scatterings within the multiple nanowire structures 35, enhancing the light-trapping effect of long-wavelength photons and significantly extending the effective optical path within the N-type silicon absorber layer 32, thereby improving the absorption efficiency of long-wavelength photons by the crystalline silicon bottom cell 3. The diameter of each nanowire structure 35 is set to 10nm-200nm, causing the nanowire structure 35 to exhibit subwavelength optical characteristics within the incident light wavelength range. This achieves a continuous transition in refractive index while also possessing a certain scattering capability, thus improving the coupling efficiency of long-wavelength photons into the N-type silicon absorber layer 32. The spacing between two adjacent nanowire structures 35 is set to 50nm-500nm, creating an effective optical field coupling and modulation space between adjacent nanowire structures 35. This ensures the continuity of the refractive index gradient while enhancing multiple scattering and interference of long-wavelength light, thereby increasing the light propagation path. Through the synergistic design of the height, diameter, and period of the nanowire structure 35, the nanowire structure 35 achieves a comprehensive effect of antireflection and light field modulation over a wide spectral range, thereby promoting the coupling and propagation of long-wavelength photons to the N-type silicon absorption layer 32, and further enhancing the light-harvesting capability and photoelectric conversion efficiency of the crystalline silicon bottom cell 3.

[0037] In this embodiment, the height of each nanowire structure 35 can be, for example, 10nm, 100nm, 200nm, 600nm, 800nm, or 1000nm, or any other value between 10nm and 1000nm. The diameter of each nanowire structure 35 can be 10nm, 50nm, 100nm, or 200nm, or any other value between 10nm and 200nm. The spacing between two adjacent nanowire structures 35, i.e., the spacing between the center of one nanowire structure 35 and the center of another adjacent nanowire structure 35, can be, for example, 50nm, 200nm, 400nm, or 500nm, or any other value between 50nm and 500nm.

[0038] In this embodiment, the perovskite absorption layer 14 has a planar structure on the side facing the incident light, and the side facing away from the light is conformally configured with the first hole transport layer 15. The first hole transport layer 15, the intermediate connecting layer 2, and the second electron transport layer 31 are all conformally configured with the N-type silicon absorption layer 32, so that the transmitted light undergoes multiple refractions, scattering, and optical path reconstruction between the conformal interfaces, and further scattering and direction modulation are generated at the nanowire structure 35. This allows some unabsorbed short-wavelength photons to be recoupled and return to the perovskite absorption layer 14, thereby improving the absorption efficiency of the perovskite top cell 1 for short-wavelength photons.

[0039] In this embodiment, the perovskite absorption layer 14 absorbs short-wavelength photons in visible light to generate a first photogenerated hole-first photogenerated electron pair. Under the action of the built-in electric field in the perovskite top cell 1, the first photogenerated hole-first photogenerated electron pair separates, the first electrode layer 11 collects the first photogenerated electron, and the first photogenerated hole is transmitted to the intermediate connecting layer 2. Due to the arrangement of the nanowire structure 35, the absorption efficiency of the N-type silicon absorber layer 32 for long-wavelength photons passing through the perovskite top cell 1 is improved, thereby generating more second photogenerated hole-second photogenerated electron pairs. Under the action of the built-in electric field in the crystalline silicon bottom cell 3, the second photogenerated hole-second photogenerated electron pairs separate, and the second electrode layer 341 collects the second photogenerated holes. Some of the second photogenerated electrons are transported to the intermediate connecting layer 2 to recombine with the first photogenerated holes in the intermediate connecting layer 2, thereby achieving charge recombination and current matching. The remaining second photogenerated electrons in the N-type silicon absorber layer 32 are collected by the third electrode layer 342, ensuring that the optical gain achieved by the silicon nanowire structure 35 in the crystalline silicon bottom cell 3 can be fully extracted, thereby improving the utilization efficiency of the three-terminal tandem solar cell 100 for incident light and the overall energy output performance.

[0040] In a further embodiment, the thickness of the N-type silicon absorber layer 32 is any value between 100 μm and 200 μm, and the thickness of the second electron transport layer 31 is any value between 5 nm and 50 nm. The material is N-type phosphorus-doped polycrystalline silicon or N-type phosphorus-doped amorphous silicon. Setting the thickness of the N-type silicon absorber layer 32 to 100 μm-200 μm can balance the transmission distance and recombination loss of photogenerated carriers, avoiding insufficient light absorption due to an excessively small thickness of the N-type silicon absorber layer 32, and increasing carrier recombination and series resistance due to an excessively large thickness of the N-type silicon absorber layer 32. This achieves a better balance between light absorption performance and electrical transport performance.

[0041] In this embodiment, the thickness of the second electron transport layer 31 is set to 5nm-50nm, which ensures high transmittance of incident light while reducing absorption and reflection losses of transmitted light. This allows long-wavelength photons transmitted from the perovskite top cell 1 to the crystalline silicon bottom cell 3 to enter the N-type silicon absorber layer 32 more effectively, thereby improving the utilization rate of incident light by the crystalline silicon bottom cell 3. Simultaneously, the material of the second electron transport layer 31 is N-type phosphorus-doped polycrystalline silicon or N-type phosphorus-doped amorphous silicon, giving the second electron transport layer 31 good electronic conductivity and selective transport characteristics. Furthermore, with the appropriate thickness range of the second electron transport layer 31, stable electron transport capability can be maintained without increasing the carrier transport path resistance, thereby improving the extraction efficiency of some second photogenerated electrons.

[0042] The thickness of the N-type silicon absorber layer 32 can be, for example, 100 μm, 150 μm, or 200 μm, or any other value between 100 μm and 200 μm. The thickness of the second electron transport layer 31 can be, for example, 5 nm, 25 nm, or 50 nm, or any other value between 5 nm and 50 nm.

[0043] In a further embodiment, the thickness of each second hole transport layer 331 is any value between 10 nm and 100 nm, and the material is P-type boron-doped amorphous silicon, P-type boron-doped polycrystalline silicon, or NiO. x The thickness of each third electron transport layer 332 is any value between 10 nm and 100 nm, and the material is N-type phosphorus-doped polycrystalline silicon, N-type phosphorus-doped amorphous silicon, or TiO2. x The thickness of the second hole transport layer 331 is set to 10nm-100nm, enabling it to achieve good coverage of the N-type silicon absorber layer 32 surface within its corresponding region. This allows for the construction of a stable second photogenerated hole transport path in a localized area and the formation of effective electrical contact with the corresponding second electrode layer 341, maintaining the selective transport and extraction efficiency of the second photogenerated holes. Simultaneously, P-type boron-doped amorphous silicon, P-type boron-doped polycrystalline silicon, or NiO... x The materials all possess suitable band structures and work function characteristics, enabling effective selectivity for the second photogenerated holes and their collection by the second electrode layer 341. The synergistic effect of the thickness setting of the second hole transport layer 331 and the material selection helps to improve the extraction and transport efficiency of the second photogenerated holes.

[0044] The thickness of the third electron transport layer 332 is 10nm-100nm, enabling effective interfacial contact with the N-type silicon absorber layer 32 within the corresponding region. This allows for the formation of a stable second photogenerated electron transport path in a localized area and a good electrical connection with the corresponding third electrode layer 342, ensuring the selective transport and extraction efficiency of another portion of the second photogenerated electrons in the N-type silicon absorber layer 32. Simultaneously, N-type phosphorus-doped polycrystalline silicon, N-type phosphorus-doped amorphous silicon, or TiO2 can be used. x The material possesses excellent electronic conductivity and selective electron transport characteristics, which facilitates the efficient extraction of another portion of the second photogenerated electrons, thereby reducing interfacial recombination losses. The synergistic effect of the thickness setting and material selection of the third electron transport layer 332 helps to improve the collection efficiency of the other portion of the second photogenerated electrons.

[0045] The thickness of the second hole transport layer 331 can be, for example, 10nm, 30nm, 60nm or 100nm, or any other value between 10nm and 100nm. The thickness of the third electron transport layer 332 can be, for example, 10nm, 40nm, 80nm or 100nm, or any other value between 10nm and 100nm.

[0046] In a further embodiment, the thickness of each second electrode layer 341 and each third electrode layer 342 is any value between 50 nm and 500 nm, and the material is selected from silver, copper, or gold. Specifically, the thickness is set to 50 nm-500 nm. This ensures good conductivity of the second electrode layer 341 and the third electrode layer 342 while avoiding excessive resistance due to insufficient thickness, which would affect the carrier collection efficiency, and avoiding the problems of increased material usage and stress accumulation due to excessive thickness. Silver, copper, or gold all have excellent electrical conductivity, improving the collection and transport efficiency of carriers. Furthermore, by making the second electrode layer 341 and the third electrode layer 342 opaque, unabsorbed long-wavelength photons can be reflected back into the N-type silicon absorber layer 32, extending the propagation path of long-wavelength photons within the N-type silicon absorber layer 32 and improving light utilization efficiency. The thickness of the second electrode layer 341 and the third electrode layer 342 can be, for example, 50 nm, 200 nm, 400 nm or 500 nm, or any other value between 50 nm and 500 nm.

[0047] In a further embodiment, the thickness of the first electrode layer 11 is any value between 50 nm and 500 nm, and the material is selected from silver, copper, or gold; the thickness of the antireflection layer 16 is any value between 50 nm and 500 nm, and the material is selected from MgF₂. x LiF, SiO x Or at least one of Al2O3. Specifically, the material of the first electrode layer 11 is selected from silver, copper, or gold, and the thickness is set to 50nm-500nm to ensure that the first electrode layer 11 has sufficient conductivity to achieve efficient collection of the first photogenerated electrons. An array of antireflection layers 16 is provided in the first electrode layer 11, and the material of the antireflection layer 16 is selected from MgF2O3. x LiF, SiO xOr at least one of Al2O3. Since the antireflection layer 16 is an optically transparent medium material and is located between the air and the transparent conductive layer 12, a transition structure of air-antireflection layer 16-transparent conductive layer 12 is formed in the corresponding region, thereby adjusting the equivalent refractive index distribution of incident light in this region, reducing the optical discontinuity between the air and the antireflection layer 16 and between the antireflection layer 16 and the transparent conductive layer 12, thereby reducing the reflection loss of incident light and allowing more incident light to enter the interior of the three-terminal tandem solar cell 100 to participate in photoelectric conversion. The thickness of the antireflection layer 16 is set to 50nm-500nm, and is the same as the thickness of the first electrode layer 11. While realizing the optical control function, the antireflection layer 16 does not weaken the conductive continuity of the first electrode layer 11, thereby reducing interface reflection loss without reducing the conductivity of the first electrode layer 11, and ensuring the efficient collection capability of the first electrode layer 11 for the first photogenerated electrons. The thickness of the first electrode layer 11 and the antireflection layer 16 can be, for example, 50 nm, 250 nm, 300 nm or 500 nm, or any other value between 50 nm and 500 nm.

[0048] In this embodiment, the antireflection layer 16 has a periodic continuous bending structure and is regularly arranged in an array in the first electrode layer 11, thereby providing multiple optical entry channels in the incident light direction. Under the premise of ensuring the conductivity of the first electrode layer 11, the synergistic optimization of the optical incident channel and reflection suppression is achieved, which helps to improve the utilization efficiency of the incident light.

[0049] In a further embodiment, the thickness of the transparent conductive layer 12 is any value between 20nm and 500nm, and the material is at least one of ITO, AZO, IZO, or FTO. The thickness of the transparent conductive layer 12 can be, for example, 20nm, 200nm, 400nm, or 500nm, or any other value between 20nm and 500nm, so that the transparent conductive layer 12 has good optical transmittance and electrical conductivity, and can provide a low-resistance current transmission path while ensuring effective transmission of incident light, and is used to transmit the first photogenerated electrons to the first electrode layer 11.

[0050] In a further embodiment, the thickness of the perovskite absorption layer 14 is any value between 100nm and 1500nm. For example, the thickness of the perovskite absorption layer 14 can be 100nm, 400nm, 800nm ​​or 1500nm, or any other value between 100nm and 1500nm, so that it can fully absorb short-wavelength photons and transmit long-wavelength light.

[0051] In a further embodiment, the thickness of the first electron transport layer 13 is any value between 10 nm and 100 nm, and the material is selected from at least one of SnO2, TiO2, ZnO, C60, or PCBM. Through synergistic optimization of the thickness and material of the first electron transport layer 13, the first electron transport layer 13 is ensured to have good optical transmittance and interface matching, and to ensure that the first electron transport layer 13 has good electron selectivity and transport capability, thereby achieving efficient extraction and transport of the first photogenerated electrons and effectively blocking the first photogenerated holes to reduce the carrier recombination probability. The thickness of the first electron transport layer 13 can be, for example, 10 nm, 50 nm, or 100 nm, or any other value between 10 nm and 100 nm.

[0052] In a further embodiment, the thickness of the first hole transport layer 15 is any value between 1 nm and 10 nm, and the material is selected as MeO, PTAA, or NiO. x In any of the above methods, through synergistic optimization of the thickness and material of the first hole transport layer 15, the first hole transport layer 15 can effectively reduce the absorption loss of incident light, and achieve efficient selective extraction of the first photogenerated holes and effective blocking of the first photogenerated electrons, thereby improving carrier separation and transport efficiency. The thickness of the first hole transport layer 15 can be, for example, 1 nm, 5 nm, or 10 nm, or any other value between 1 nm and 10 nm.

[0053] In a further embodiment, the thickness of the intermediate connecting layer 2 is any value between 1 nm and 100 nm, and the material is ITO or IZO. By synergistically optimizing the thickness and material of the intermediate connecting layer 2, while ensuring efficient electrical connection, optical transmittance and interface energy level matching are also taken into account, thus ensuring a comprehensive improvement in the photoelectric conversion efficiency of the three-terminal tandem solar cell 100. The thickness of the intermediate connecting layer 2 can be 1 nm, 30 nm, 90 nm, or 100 nm, or any other value between 1 nm and 100 nm.

[0054] The following detailed description uses specific embodiments and comparative examples.

[0055] Example 1

[0056] The three-terminal tandem solar cell 100 includes a perovskite top cell 1, an intermediate connecting layer 2, and a crystalline silicon bottom cell arranged in layers.

[0057] The perovskite top solar cell 1 includes a first electrode layer 11, a transparent conductive layer 12, a first electron transport layer 13, a perovskite absorption layer 14 and a first hole transport layer 15 arranged sequentially from top to bottom. The first electrode layer 11 is provided with an array of antireflection layers 16.

[0058] The crystalline silicon bottom cell 3 includes a second electron transport layer 31, an N-type silicon absorber layer 32, a first composite functional layer 33, and a second composite functional layer 34 stacked sequentially from top to bottom. The N-type silicon absorber layer 32 has multiple nanowire structures 35 that protrude toward the perovskite top cell 1 and are spaced apart, so that the first hole transport layer 15, the intermediate connection layer 2, and the second electron transport layer 31 are conformally disposed with the N-type silicon absorber layer 32. The first composite functional layer 33 includes multiple second hole transport layers 331 and multiple third electron transport layers 332 arranged at intervals, with the second hole transport layers 331 and the third electron transport layers 332 arranged alternately. The second composite functional layer 34 includes multiple second electrode layers 341 aligned with each second hole transport layer 331 and multiple third electrode layers 342 aligned with each third electron transport layer 332.

[0059] The first electrode layer 11, the second electrode layer 341, and the third electrode layer 342 are all 200 nm thick and made of Ag. The transparent conductive layer 12 is 100 nm thick and made of ITO. The first electron transport layer 13 is 20 nm thick and made of C60. The perovskite absorber layer 14 is 300 nm thick. The first hole transport layer 15 is 5 nm thick and made of MeO. The antireflection layer 16 is 200 nm thick and made of LiF. The intermediate connecting layer 2 is 30 nm thick and made of ITO.

[0060] The second electron transport layer 31 has a thickness of 20 nm and is made of N-type phosphorus-doped amorphous silicon. The N-type silicon absorber layer 32 has a thickness of 200 μm. Each nanowire structure 35 has a height of 500 nm and a diameter of 200 nm. The spacing between two adjacent nanowire structures 35 is 300 nm. The second hole transport layer 331 has a thickness of 20 nm and is made of P-type boron-doped amorphous silicon. The third electron transport layer 332 has a thickness of 20 nm and is made of N-type phosphorus-doped amorphous silicon.

[0061] Comparative Example 1

[0062] The difference between Comparative Example 1 and Example 1 is that the N-type silicon absorber layer 32 has a planar structure on both sides.

[0063] The three-terminal tandem solar cells of Example 1 and Comparative Example 1 were simulated using simulation software. The simulated ambient temperature was 300K, and the incident light source used was the AM1.5G standard solar spectrum, i.e., the global solar irradiance spectrum under atmospheric mass 1.5 conditions, to simulate the actual spectral distribution of sunlight reaching the Earth's surface after passing through the Earth's atmosphere. This spectrum includes both direct and diffuse radiation components, and its total irradiance is typically 1000 W / m². 2 .

[0064] Figure 3The above are the absorption spectra of the three-terminal tandem solar cells according to Example 1 and Comparative Example 1.

[0065] like Figure 3 As shown, in the long-wavelength region beyond 700 nm, the absorptivity curve of the three-terminal tandem solar cell 100 of Example 1 is consistently above that of Comparative Example 1. This indicates that the nanowire structure 35 has a good light-trapping effect, extending the effective propagation path of long-wavelength photons in the N-type silicon absorber layer 32. This allows the N-type silicon absorber layer 32 to fully absorb long-wavelength photons that are normally easily transmitted or reflected, thereby improving the absorption efficiency of long-wavelength photons. Consequently, the integrated photocurrent density increases from 17.48 mA / cm² in Comparative Example 1. 2 It was increased to 18.61 mA / cm² in Example 1. 2 It increased by approximately 1.13 mA / cm 2 In the 300nm-700nm wavelength range, although the absorption rate curves of Example 1 and Comparative Example 1 for short-wavelength photons basically overlap, the absorption curve of Example 1 in the 600nm-700nm range is superior to that of Comparative Example 1, resulting in an integrated photocurrent density higher than that of the perovskite top cell 1 in Comparative Example 1 (18.57 mA / cm²). 2 Increased to 18.83 mA / cm in Example 1. 2 This indicates that the nanowire structure 35 not only improves the optical performance of the crystalline silicon bottom cell 3, but also optimizes the optical performance of the perovskite top cell 1, achieving synergistic optical gains between the perovskite top cell 1 and the crystalline silicon bottom cell 3 in the three-terminal tandem solar cell 100.

[0066] Figure 4 The reflection spectra are based on the three-terminal tandem solar cells of Example 1 and Comparative Example 1.

[0067] Depend on Figure 4 It can be seen that in the long-wavelength region of 700nm-1000nm, the reflectivity of Comparative Example 1 is higher than that of Example 1, indicating that multiple nanowire structures 35, as subwavelength structures, reduce the specular reflection caused by the N-type silicon absorption layer 32 as a planar structure, and are beneficial to the absorption of long-wavelength photons by the crystalline silicon bottom cell 3.

[0068] Figure 5 This is a schematic diagram of the electric field distribution of the three-terminal tandem solar cells according to Example 1 and Comparative Example 1 at a wavelength of 800 nm. Figure 6 This is a schematic diagram of the electric field distribution of the three-terminal tandem solar cells according to Example 1 and Comparative Example 1 at a wavelength of 900nm.

[0069] Figure 5 and Figure 6 The electric field intensity color scale in the image transitions from dark blue to dark red; the more reddish the color, the stronger the electric field intensity in that region. Figure 5 and Figure 6It can be seen that, compared with Comparative Example 1, the three-terminal tandem solar cell 100 in Example 1 exhibits a stronger and more spatially complex electric field enhancement phenomenon in the N-type silicon absorber layer 32. This indicates that the multiple nanowire structures 35, as subwavelength optical structures, scatter and refract long-wavelength light, so that long-wavelength light forms a local high electric field region in the nanowire structure 35 region, extending the effective propagation path of long-wavelength light, thereby improving the absorption of long-wavelength photons.

[0070] Specifically, the electric field distribution characteristics mentioned above are consistent with the absorption and reflection spectrum results, indicating that the silicon nanowire structure 35 can enhance the capture and utilization efficiency of long-wavelength photons in the crystalline silicon bottom cell 3. Furthermore, the three-terminal electrode structure designed in this application ensures that the additional photocurrent gain generated by the silicon nanowire structure 35 can be extracted and converted into electrical energy. This proves that the technical solution of combining the independent output of the nanowire structure 35 with the three-terminal electrode ensures that long-wavelength light can be accurately captured and fully converted into effective energy, effectively improving the overall energy output performance of the three-terminal tandem solar cell 100.

[0071] Therefore, those skilled in the art should recognize that although numerous exemplary embodiments of the present invention have been shown and described in detail herein, many other variations or modifications conforming to the principles of the present invention can be directly determined or derived from the disclosure of the present invention without departing from the spirit and scope of the invention. Thus, the scope of the present invention should be understood and construed as covering all such other variations or modifications.

Claims

1. A three-terminal tandem solar cell based on a silicon nanowire structure, characterized in that, It includes a perovskite top cell, an intermediate connecting layer, and a crystalline silicon bottom cell arranged in a stacked manner, wherein, The perovskite top solar cell includes a first electrode layer, a transparent conductive layer, a first electron transport layer, a perovskite absorption layer and a first hole transport layer arranged in sequence from top to bottom, and the first electrode layer is provided with an array of anti-reflection layers. The crystalline silicon bottom solar cell includes a second electron transport layer, an N-type silicon absorber layer, a first composite functional layer, and a second composite functional layer stacked sequentially from top to bottom. The N-type silicon absorber layer has multiple nanowire structures that bulge towards the perovskite top solar cell and are spaced apart, such that the first hole transport layer, the intermediate connecting layer, and the second electron transport layer are conformally disposed with the N-type silicon absorber layer. The first composite functional layer includes multiple second hole transport layers and multiple third electron transport layers arranged at intervals, with the second hole transport layers and the third electron transport layers alternating. The second composite functional layer includes multiple second electrode layers aligned with each second hole transport layer and multiple third electrode layers aligned with each third electron transport layer. The height of each nanowire structure is any value between 10 nm and 1000 nm, the diameter is any value between 10 nm and 200 nm, and the spacing between two adjacent nanowire structures is any value between 50 nm and 500 nm.

2. The three-terminal tandem solar cell according to claim 1, characterized in that, The thickness of the N-type silicon absorber layer is any value between 100μm and 200μm; the thickness of the second electron transport layer is any value between 5nm and 50nm, and the material is N-type phosphorus-doped polycrystalline silicon or N-type phosphorus-doped amorphous silicon.

3. The three-terminal tandem solar cell according to claim 2, characterized in that, The thickness of each second hole transport layer is any value between 10nm and 100nm, and the material is P-type boron-doped amorphous silicon, P-type boron-doped polycrystalline silicon, or NiO. x ; The thickness of each of the third electron transport layers is any value between 10 nm and 100 nm, and the material is N-type phosphorus-doped polycrystalline silicon, N-type phosphorus-doped amorphous silicon, or TiO₂. x .

4. The three-terminal tandem solar cell according to claim 3, characterized in that, The thickness of each second electrode layer and each third electrode layer is any value between 50nm and 500nm, and the material is selected from silver, copper or gold.

5. The three-terminal tandem solar cell according to any one of claims 1-4, characterized in that, The thickness of the first electrode layer is any value between 50nm and 500nm, and the material is selected from silver, copper or gold. The thickness of the antireflection layer is any value between 50nm and 500nm, and the material is selected as MgF₂. x LiF, SiO x Or at least one of Al2O3.

6. The three-terminal tandem solar cell according to claim 5, characterized in that, The thickness of the transparent conductive layer is any value between 20nm and 500nm, and the material is at least one of ITO, AZO, IZO or FTO.

7. The three-terminal tandem solar cell according to claim 6, characterized in that, The thickness of the perovskite absorber layer is any value between 100nm and 1500nm.

8. The three-terminal tandem solar cell according to claim 7, characterized in that, The thickness of the first electron transport layer is any value between 10nm and 100nm, and the material is selected from at least one of SnO2, TiO2, ZnO, C60 or PCBM.

9. The three-terminal tandem solar cell according to claim 8, characterized in that, The thickness of the first hole transport layer is any value between 1 nm and 10 nm, and the material is selected as MeO, PTAA, or NiO. x Any one of them.

10. The three-terminal tandem solar cell according to claim 9, characterized in that, The thickness of the intermediate connecting layer is any value between 1nm and 100nm, and the material is ITO or IZO.

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