Solar cell and photovoltaic module

Abstract

The utility model provides a solar cell and a photovoltaic module, and the solar cell comprises the components of a semiconductor substrate which comprises a front surface and a back surface which are oppositely arranged; a first intrinsic amorphous silicon layer, a first doping layer, a first transparent conducting layer and a first metal electrode are sequentially prepared on the front surface of the semiconductor substrate from top to bottom, and a second intrinsic amorphous silicon layer, a second doping layer, a second transparent conducting layer and a second metal electrode are sequentially prepared on the back surface of the semiconductor substrate from top to bottom; and the light one-way transmission layer is located above the first transparent conductive layer, and the light one-way transmission layer reflects light incident on the light one-way transmission layer to the interior of the cell.

Description

Technical Field

[0001] This disclosure relates to the field of solar cells, and more particularly to a solar cell and a photovoltaic module. Background Technology

[0002] Against the backdrop of ever-increasing global energy demand and increasingly severe environmental problems, solar energy, as a clean and renewable energy source, has attracted much attention for its development and utilization. Currently, the mainstream photovoltaic cell technology is transitioning from P-type to N-type cells. Heterojunction cells, as one of the mainstream N-type cell technologies, are constrained by many factors in terms of efficiency. Regarding the light-absorbing layer, the suboptimal quality of its materials is a significant cause of optical loss and a major reason limiting cell efficiency.

[0003] From a material quality perspective, if the light-absorbing layer contains numerous crystal defects, impurities, or uneven composition, it will severely affect its ability to capture and convert photons. Crystal defects become recombination centers for charge carriers, causing photogenerated charge carriers to recombine before being effectively collected, thus failing to convert them into electrical energy output. Some commonly used semiconductor materials have limited absorption ranges for sunlight, failing to fully utilize sunlight and resulting in a large amount of unconverted light, including through frontal reflection, parasitic absorption, transmission, and scattering.

[0004] From an optical perspective, solar cells have the following shortcomings: current solar cell structures have certain limitations in light utilization; light with wavelengths above 900nm passes directly through the cell, resulting in ineffective utilization of incident light, while light with wavelengths below 380nm causes severe UV degradation, leading to a decrease in cell output power. Therefore, improving the utilization rate of incident light across both long and short wavelength bands and reducing cell degradation caused by short wavelengths are among the problems that solar cells currently need to solve. Utility Model Content

[0005] This disclosure provides a solar cell and a photovoltaic module to at least solve the above-mentioned technical problems existing in the prior art.

[0006] According to a first aspect of this disclosure, a solar cell is provided, the solar cell comprising:

[0007] A semiconductor substrate, the semiconductor substrate including a front side and a back side disposed opposite to each other;

[0008] The semiconductor substrate has a first intrinsic amorphous silicon layer, a first doped layer, a first transparent conductive layer and a first metal electrode sequentially formed from the front side upwards, and a second intrinsic amorphous silicon layer, a second doped layer, a second transparent conductive layer and a second metal electrode sequentially formed from the back side downwards.

[0009] A unidirectional light transmission layer is located above the first transparent conductive layer, which reflects incident light into the battery.

[0010] In one possible implementation, it further includes:

[0011] A spectral conversion center film is located on the area of ​​the first transparent conductive layer not covered by the first metal electrode, and the spectral conversion center film includes an upconversion luminescent material layer and a downconversion luminescent material layer.

[0012] In one embodiment, the upconversion luminescent material layer is located between the first transparent conductive layer and the downconversion luminescent material layer; or, the downconversion luminescent material layer is located between the first transparent conductive layer and the upconversion luminescent material layer.

[0013] In one possible embodiment, the material of the upconversion luminescent material layer includes at least one of rare earth salt nanoparticles or halides;

[0014] The material of the downconversion luminescent material layer includes alkaline earth vanadate.

[0015] In one embodiment, the unidirectional optical transmission layer comprises a material having a periodic dielectric structure or a material having a second-order nonlinear optical effect.

[0016] In one embodiment, the material having a second-order nonlinear optical effect includes inorganic crystal materials or semiconductor materials.

[0017] In one embodiment, the thickness of the unidirectional optical transmission layer is 10-500 nm.

[0018] In one embodiment, the thickness of the upconversion luminescent material layer is 10-500 nm; and / or, the thickness of the downconversion luminescent material layer is 10-500 nm.

[0019] In one embodiment, at least one of the front and back sides of the semiconductor substrate is formed as a pyramidal textured surface.

[0020] According to a second aspect of this disclosure, a photovoltaic module is provided, comprising a solar cell as described in any one of the embodiments above.

[0021] The solar cell and photovoltaic module disclosed herein improve the utilization rate of light conversion into electricity by setting a light unidirectional transmission layer on the first transparent conductive layer. The light unidirectional transmission layer only allows light to enter the cell and prevents the light converted by the spectral conversion center film from returning to the outside, thereby increasing the short-circuit current density of the solar cell and improving the photoelectric conversion efficiency.

[0022] It should be understood that the description in this section is not intended to identify key or essential features of the embodiments of this disclosure, nor is it intended to limit the scope of this disclosure. Other features of this disclosure will become readily apparent from the following description. Attached Figure Description

[0023] The above and other objects, features, and advantages of this disclosure will become readily apparent from the following detailed description of exemplary embodiments, taken in conjunction with the accompanying drawings. Several embodiments of this disclosure are illustrated in the drawings by way of example and not limitation, in which:

[0024] In the accompanying drawings, the same or corresponding reference numerals indicate the same or corresponding parts.

[0025] Figure 1 This is a schematic diagram of the structure of a solar cell provided in an embodiment of this disclosure.

[0026] Icon labels:

[0027] 10. Semiconductor substrate; 21. First intrinsic amorphous silicon layer; 22. Second intrinsic amorphous silicon layer; 31. First doped layer; 32. Second doped layer; 41. First transparent conductive layer; 42. Second transparent conductive layer; 51. Spectral conversion center film layer; 511. Upconversion luminescent material layer; 512. Downconversion luminescent material layer; 61. Unidirectional light transmission layer; 71. First metal electrode; 72. Second metal electrode. Detailed Implementation

[0028] To make the objectives, features, and advantages of this disclosure more apparent and understandable, the technical solutions in the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this disclosure, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this disclosure without creative effort are within the scope of protection of this disclosure.

[0029] In existing technologies, to improve the light utilization efficiency (reduce optical losses) of heterojunction solar cells, the following approaches can be taken: 1. Employing bifacial microcrystalline technology allows for efficient absorption and conversion of light energy on both sides of the cell, significantly increasing overall light utilization; 2. Optimizing the material of the light absorption layer by selecting high-quality, low-defect, and low-impurity materials and precisely controlling its thickness to ensure sufficient light absorption while reducing carrier recombination; 3. Improving the cell structure design, such as optimizing surface passivation, to reduce optical losses and enhance carrier separation and transport, thereby improving the collection efficiency of photogenerated carriers; 4. Exploring suitable encapsulation materials to reduce light reflection and loss, allowing more light to be effectively utilized by the cell; 5. Researching low-indium target materials can also reduce costs and potentially positively impact light utilization efficiency; 6. Stacking heterojunction cells with perovskite cells is also an effective approach, fully leveraging the advantages of both at different wavelengths to further improve the overall absorption and utilization efficiency of sunlight; 7. Using special processes such as light injection to activate relevant atoms and improve the conductivity of the thin film, thereby enhancing the photoelectric conversion efficiency of the cell.

[0030] This disclosure provides a solar cell, Figure 1 This is a schematic diagram of the structure of a solar cell provided in an embodiment of this disclosure, such as... Figure 1 As shown, the solar cell includes:

[0031] Semiconductor substrate 10 includes a front side and a back side disposed opposite to each other.

[0032] The semiconductor substrate 10 can be a single-element semiconductor material substrate (e.g., a silicon substrate, a germanium substrate, etc.), a composite semiconductor material substrate (e.g., a germanium-silicon substrate, etc.), a silicon-on-insulator (SOI) substrate, a germanium-on-insulator (GOI) substrate, or a polycrystalline silicon substrate, etc. In a preferred embodiment, the semiconductor substrate 10 can be crystalline silicon, which can be P-type single-crystal silicon or N-type single-crystal silicon. Preferably, it can be N-type single-crystal silicon.

[0033] At least one of the front and back sides of the semiconductor substrate 10 is formed as a pyramidal textured structure (not shown in the figure).

[0034] The solar cell also includes: a first intrinsic amorphous silicon layer 21, a first doped layer 31, a first transparent conductive layer 41 and a first metal electrode 71 are sequentially formed on the front side of the semiconductor substrate 10, and a second intrinsic amorphous silicon layer 22, a second doped layer 32, a second transparent conductive layer 42 and a second metal electrode 72 are sequentially formed on the back side of the semiconductor substrate 10.

[0035] In one embodiment, the first intrinsic amorphous silicon layer 21 and the second intrinsic amorphous silicon layer 22 are passivation layers. The passivation layer has a good passivation effect on the surface of the semiconductor substrate. The superior surface passivation capability is an important condition for obtaining high battery efficiency and can significantly improve the minority carrier lifetime of the battery.

[0036] In one embodiment, the first doped layer 31 can be an N-type doped layer, and the second doped layer 32 can be a P-type doped layer.

[0037] The first doped layer 31 and the second doped layer 32 can be microcrystalline silicon doped layers or amorphous silicon doped layers.

[0038] The first doped layer 31 and the second doped layer 32 form the PN junction and back field of the heterojunction solar cell.

[0039] In one embodiment, the first transparent conductive layer 41 and the second transparent conductive layer 42 are selected as transparent conductive oxides. The transparent conductive oxides can be single-layer or stacked structures of materials such as indium tin oxide, aluminum-doped zinc oxide, or tungsten-doped indium oxide. The transparent conductive layers can effectively increase the collection of charge carriers and reduce light reflection.

[0040] In one embodiment, the first metal electrode 71 and the second metal electrode 72 are the positive and negative electrodes for forming the battery, effectively collecting photogenerated carriers. Their materials can be silver, silver-clad copper grids, or copper. The first metal electrode 71 is disposed on the first transparent conductive layer 41, and the second metal electrode 72 is disposed on the second transparent conductive layer 42, achieving direct contact between the metal electrodes and the transparent conductive layer, ensuring good ohmic contact.

[0041] The solar cell also includes a spectral conversion center film layer 51, which is located on the area of ​​the first transparent conductive layer 41 not covered by the first metal electrode 71. The spectral conversion center film layer 51 includes an upconversion light-emitting material layer 511 and a downconversion light-emitting material layer 512.

[0042] In one embodiment, the upconversion light-emitting material layer 511 is located between the first transparent conductive layer 41 and the downconversion light-emitting material layer 512; or, the downconversion light-emitting material layer 512 is located between the first transparent conductive layer 41 and the upconversion light-emitting material layer 511.

[0043] In one specific embodiment, such as Figure 1 As shown, the upconversion light-emitting material layer 511 is located on the first transparent conductive layer 41, and the downconversion light-emitting material layer 512 is located on the upconversion light-emitting material layer 511.

[0044] In another specific embodiment, the downconversion luminescent material layer is located on the first transparent conductive layer, and the upconversion luminescent material layer is located on the downconversion luminescent material layer.

[0045] In one embodiment, the thickness of the upconversion luminescent material layer 511 is 10-500 nm; the thickness of the downconversion luminescent material layer 512 is 10-500 nm. In a specific embodiment, for example, the thickness of the upconversion luminescent material layer 511 can be 10-100 nm, 100-200 nm, 200-300 nm, 300-400 nm, 400-500 nm, etc., and the thickness of the downconversion luminescent material layer 512 can be 10-100 nm, 100-200 nm, 200-300 nm, 300-400 nm, 400-500 nm, etc.

[0046] Upconversion luminescence, also known as anti-Stokes luminescence, refers to materials that, when excited by low-energy light, emit high-energy light; that is, when excited by long-wavelength, low-frequency light, they emit short-wavelength, high-frequency light. Downconversion luminescence, on the other hand, is a photoluminescence phenomenon that follows Stokes' law, where the energy of the emitted photons is lower than the energy of the absorbed photons. The material's emission spectrum is located on the long-wavelength side of the excitation spectrum; in other words, the material absorbs high-energy, short-wavelength radiation and emits low-energy, long-wavelength radiation.

[0047] Upconversion luminescent materials are typically composed of at least one of rare earth salt nanoparticles or halides, while downconversion luminescent materials typically include alkaline earth vanadates (LaVO4). Alkaline earth vanadates exhibit good performance in terms of light transmittance, crystallinity, and thermal stability.

[0048] In this embodiment, the spectral conversion center film captures and converts photons (mainly short-wavelength and long-wavelength incident light) passing through the solar cell. The upconversion luminescent material layer in the spectral conversion center film converts the long-wavelength photons into mid-wavelength photons, and the downconversion luminescent material layer converts the short-wavelength photons into mid-wavelength photons. Furthermore, since the incident light is concentrated in the mid-wavelength, the optical requirements for the TCO are reduced, and a lower-cost target material can be used, thus reducing the cost of the TCO target material.

[0049] The solar cell also includes a light-transmitting layer 61, located above the first transparent conductive layer 41, which reflects incident light into the cell.

[0050] Specifically, see Figure 1 The optical unidirectional transmission layer 61 is located on the spectral conversion center film layer 51. The optical unidirectional transmission layer 61 includes a material with a periodic dielectric structure or a material with a second-order nonlinear optical effect.

[0051] In one embodiment, the thickness of the unidirectional optical transmission layer 61 is 10-500 nm. In a specific embodiment, for example, the thickness of the unidirectional optical transmission layer 61 can be 10-100 nm, 100-200 nm, 200-300 nm, 300-400 nm, 400-500 nm, etc.

[0052] In one specific embodiment, the unidirectional optical transmission layer can be based on a photonic crystal, which is a material with a periodic dielectric structure. By carefully designing its structure and parameters, a specific band structure can be formed, allowing light of certain frequencies to propagate only in specific directions, while a band gap exists in the opposite direction to prevent light propagation. This prevents light converted by the spectral conversion center layer from returning to the outside. For example, a two-dimensional photonic crystal structure can be constructed using silicon as a high-refractive-index medium and air as a low-refractive-index medium. The photonic crystal consists of periodically arranged silicon pillars, the diameter and spacing of which are precisely designed to achieve a specific photonic band structure. Defects are introduced into the photonic crystal to form a waveguide structure. By adjusting the shape and size of the defects, the propagation characteristics of light in the waveguide can be controlled. To achieve unidirectional light transmission, an asymmetric structure is introduced on one side of the waveguide, such as adding additional silicon pillars at the edge of the waveguide or changing the diameter of the silicon pillars.

[0053] In another specific embodiment, the unidirectional optical transmission layer can also be based on nonlinear optical effects. When light propagates in certain nonlinear materials, nonlinear optical effects are generated, such as second harmonic generation and four-wave mixing. By utilizing these nonlinear optical effects, unidirectional light transmission can be achieved. For example, in a material with second-order nonlinear optical effects, when two beams of light with different frequencies are incident simultaneously, sum-frequency or difference-frequency light is generated. By designing appropriate nonlinear optical processes and material structures, light can be made to pass through only one direction and not the other.

[0054] In one embodiment, the material exhibiting second-order nonlinear optical effects includes inorganic crystal materials or semiconductor materials. Inorganic crystal materials include lithium niobate (LiNbO3), potassium dihydrogen phosphate (KDP), and their isomorphic crystals, while semiconductor materials include gallium arsenide (GaAs), cadmium sulfide (CdS), and the like.

[0055] In this embodiment, the unidirectional light transmission layer allows only light to enter the cell, preventing the light converted by the spectral conversion center film from returning to the outside, thereby improving the utilization rate of light conversion into electricity, thus increasing the short-circuit current density of the solar cell and improving the photoelectric conversion efficiency.

[0056] This disclosure also provides a photovoltaic module, including a solar cell as described in any of the above embodiments.

[0057] It should be understood that the various forms of processes shown above can be used to rearrange, add, or delete steps. For example, the steps described in this disclosure can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution disclosed in this disclosure can be achieved, and this is not limited herein.

[0058] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this disclosure, "a plurality of" means two or more, unless otherwise explicitly specified.

[0059] The above description is merely a specific embodiment of this disclosure, but the scope of protection of this disclosure is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this disclosure should be included within the scope of protection of this disclosure. Therefore, the scope of protection of this disclosure should be determined by the scope of the claims.

Claims

1. A solar cell, characterized in that, The solar cell includes: A semiconductor substrate, the semiconductor substrate including a front side and a back side disposed opposite to each other; The semiconductor substrate has a first intrinsic amorphous silicon layer, a first doped layer, a first transparent conductive layer and a first metal electrode sequentially formed from the front side upwards, and a second intrinsic amorphous silicon layer, a second doped layer, a second transparent conductive layer and a second metal electrode sequentially formed from the back side downwards. A unidirectional light transmission layer is located above the first transparent conductive layer, which reflects incident light into the battery.

2. The solar cell according to claim 1, characterized in that, Also includes: A spectral conversion center film is located on the area of ​​the first transparent conductive layer not covered by the first metal electrode, and the spectral conversion center film includes an upconversion luminescent material layer and a downconversion luminescent material layer.

3. The solar cell according to claim 2, characterized in that, The upconversion luminescent material layer is located between the first transparent conductive layer and the downconversion luminescent material layer; or, the downconversion luminescent material layer is located between the first transparent conductive layer and the upconversion luminescent material layer.

4. The solar cell according to claim 2, characterized in that, The material of the upconversion luminescent material layer includes at least one of rare earth salt nanoparticles or halides. The material of the downconversion luminescent material layer includes alkaline earth vanadate.

5. The solar cell according to claim 1, characterized in that, The optical unidirectional transmission layer comprises a material with a periodic dielectric structure or a material with a second-order nonlinear optical effect.

6. The solar cell according to claim 5, characterized in that, The materials with second-order nonlinear optical effects include inorganic crystal materials or semiconductor materials.

7. The solar cell according to claim 1, characterized in that, The thickness of the optical unidirectional transmission layer is 10-500 nm.

8. The solar cell according to claim 2, characterized in that, The thickness of the upconversion luminescent material layer is 10-500 nm; and / or, the thickness of the downconversion luminescent material layer is 10-500 nm.

9. The solar cell according to claim 1, characterized in that, At least one of the front and back sides of the semiconductor substrate is formed as a pyramidal textured surface.

10. A photovoltaic module, characterized in that, Includes the solar cell as described in any one of claims 1-9.

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